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magnetic separator how to make

build a magnet separator : 5 steps (with pictures) - instructables

build a magnet separator : 5 steps (with pictures) - instructables

At the North Carolina Maker Faire, I helped TechShop give away somewhere over a thousand throwies. This was awesome, and people of all ages had an excellent time. But, at the end of the day, my fingers were a bit sore and my fingernails somewhat ragged from trying to separate that many rare earth magnets from big stacks. Sure, you can do it, but it gets tiring. And we were using small magnets: 1/2" diameter and 1/16" thick. If you have big stacks of rare earth magnets, or not-so-big stacks of bigger rare earth magnets, this instructable is for you. The main tool used in this instructable is the vertical mill. The project is not complicated, and would make an excellent first project on a mill.

The basic design of the magnet separator is very simple. You will probably want to adjust it to work with your available materials and magnets, so I'll give a simple overview rather than detailed plans. You need two pieces of aluminum. One has a hole that the magnets go through; the other has a slot deep enough to hold one magnet. They are held together by a hinge mechanism, creating a scissor-like device that slices one magnet off the stack at a time. Think of a Pez dispenser for magnets. The exact shape of the handles, relative placement of the separating point and hinge, and size of magnet you're designing for are all up to you. The first step is to cut your stock to size, and get out your tools. I used two pieces of aluminum: one 1"x5", one 2"x5", both 0.5" thick. You could use a hard plastic instead if you prefer, but aluminum is cheap and strong and easy to work with, so I went with that. I've seen a similar design made of wood for large magnets, but for small magnets I worry the edge would wear out on something as soft as wood.

Getting a good, simple hinge to work well here is the most important part. I used a shoulder bolt from McMaster-Carr (part number 91259A707). It's a bolt with a non-threaded precision shoulder, in this case 1/2" diameter x 1/2" long, and threads on the end (3/8"-16 for this bolt). This provides the pivot point and attachment mechanism all in one simple piece. Making the shoulder bolt work well requires that your stock be thinner than the shoulder. I used a fly cutter on the vertical mill to cut my stock down to a thickness of 0.498". This also produces an attractive shiny surface. The goal is to have the stock only slightly thinner than the length of the shoulder, so that there isn't a lot of room for movement. This produces a pleasantly smooth but not wobbly hinge. (As you'll see in the pictures, I did this step out of order, but it really doesn't make much difference. It's just easier to get the slot depth right if you do your surfacing before cutting the slot.)

The base block is quite simple: all it needs is a pair of holes. One of the holes is for the magnets to feed through, the other is threaded for the shoulder bolt. I used the 2" wide piece of aluminum for this part. Just drill the two holes where you need them. For the shoulder bolt I used, I needed 3/8-16 threads, which need a 5/16" tap drill. Be sure to check your tap drill size! The hole for the magnets should be slightly oversized. For 1/2" magnets, I used a 33/64" drill bit, with good results. 17/32" would probably also have worked just fine. For the threaded hole, I used a tap wrench with a guide. The guide goes in the drill chuck, and holds the back end of the tap wrench. This ensures that the tap goes into the material straight instead of at an angle. Having the tap enter at an angle can produce angled threads (which won't work well with the shoulder bolt) or even break taps. This is especially a hazard in soft materials like aluminum. If you don't have a tap wrench like this, I highly recommend getting one. Failing that, be careful that your tap goes in straight! (Note that the mill is only used to hold the tap wrench guide; you turn the wrench by hand, and the mill spindle is off, for this process.) Finish the base block with a modest countersink on the back side of the block; this will help make it easier to insert a stack of magnets. You can also countersink the threaded hole slightly; this is an easy way to deburr after tapping. Don't do too much here, or you'll lose the flat surface for the shoulder bolt to rest against.

The second part is almost as simple as the first. It has a hole for the shoulder bolt hinge, and a slot to catch the magnets. The slot isn't even required, but it helps a lot with making sure you get exactly one magnet without catching magnets on the edges. This is also the motivation for cutting the hole in the back plate sized exactly to the magnets you want to use. For larger magnets, it's less important, but the 1/16" thick disk magnets we're using for throwies are more difficult. For the hinge pin hole, I used a reamer to get exactly the right size. I drilled the hole to 31/64", then reamed it to 1/2". This results in a very smoothly moving hinge, without any play or wobble to it. I liked the feel of this hinge, and it was part of the reason for choosing the shoulder bolt design in the first place. The slot for holding the separated magnet is also very simple. I used a 9/16" end mill to create enough clearance for easy operation. Just raise the work up to touch the end mill, raise it another 0.065" or so, and cut the slot. Make the slot a few thousandths of an inch deeper than the magnet, so that everything moves smoothly without jamming when the magnet separates.

After that, it's just a matter of assembly and testing. Deburr any edges, especially around the threaded hole. Burrs here will make the hinge stiff or impossible, and trying to solve that problem by forcing it will only mar the hinge surfaces. Other corners should be cleaned up with a file so that they're smooth and comfortable in the hand. Play with the separator a bit. See what works well. Don't be afraid to just take it to the vertical band saw and try something. Have fun with your magnets!

magnetic separators

magnetic separators

The science of magnetic separation has experienced extraordinary technological advancements over the past decade. As a consequence, new applications and design concepts in magnetic separation have evolved. This has resulted in a wide variety of highly effective and efficient magnetic separator designs.

In the past, a process engineer faced with a magnetic separation project had few alternatives. Magnetic separation was typically limited and only moderately effective. Magnetic separators that utilized permanent ferrite magnets, such as drum-type separators, generated relatively low magnetic field strengths. These separators worked well collecting ferrous material but were ineffective on fine paramagnetic particles. High intensity magnetic separators that were effective in collecting fine paramagnetic particles utilized electromagnetic circuits. These separators were large, heavy, low capacity machines that typically consumed an inordinate amount of power and required frequent maintenance. New developments in permanent magnetic separation technology now provide an efficient alternative for separation of paramagnetic materials.

Technological advances in the field of magnetic separation are the result of several recent developments. First, and perhaps most important, is the ability to precisely model magnetic circuits using sophisticated multi-dimensional finite element analysis (FEA). Although FEA is not a new tool, developments in computing speed over the last decade have made this tool readily accessible to the design engineer. In this technique, a scaled design of the magnetic circuit is created and the magnetic characteristics of the individual components quantified. The FEA model is then executed to determine the magnetic field intensity and gradient. Using this procedure, changes to the magnetic circuit design can be quickly evaluated to determine the optimum separator configuration. This technique can be applied to the design of both permanent and electromagnetic circuits. As a consequence, any type of magnetic separator can be developed (or redesigned) with a high level of confidence and predictability.

Equally important has been the recent development of rare-earth permanent magnets. Advances in rare-earth magnet materials have revolutionized the field of magnetic separation. The advent of rare-earth permanent magnets in the 1980s provided a magnetic energy product an order of magnitude greater than that of conventional ferrite magnets. Rare-earth magnetic circuits commonly exhibit a magnetic attractive force 20 to 30 times greater than that of conventional ferrite magnets. This development has provided for the design of high-intensity magnetic circuits that operate energy-free and surpass the strength and effectiveness of electromagnets.

Finally, the materials of construction used in the fabrication of magnetic separators have advanced to a point that significantly extends service life while decreasing maintenance. Advanced materials, such as fiber composites, kevlar, ultra high molecular weight polyester, and specialty steel alloys are now commonly used in contact areas of the separator. These materials are lightweight, abrasion resistant, and comparatively inexpensive resulting in significant design advantages as compared to previous construction materials.

The evolution of high strength permanent rare-earth magnets has led to the development of high-intensity separators that operate virtually energy free. The use of rare-earth magnetic separators for beneficiation of industrial minerals has become the industry standard with literally hundreds of separators placed in recent years. The following sections present an overview of the most widely used permanent magnetic separators: rare-earth drum and rare-earth roll-type separators.

Of the roll separators, there are at least fourteen manufacturers. Most of the different makes are based on the original Permroll design concept originated by this author. Various enhancements have been mainly focused on the belt tracking methods. New magnetic roll configurations and optimization of roll designs are relatively recent innovations. Additional optimization efforts are in progress.

At last count, seven manufacturers have commercially available drum separators, most based on magnet circuits derived from the use of conventional ferrite magnet. Two unique designs have been developed with one clearly offering advantages over older configurations.

Rare-earth elements have some unique properties that are used in many common applications, such as TV screens and lighters. In the 1970s, rare-earths began to be used in a new generation of magnetic materials, that have very unique characteristics. Not only were these stronger in the sense of attraction force between a magnet and mild steel (high induction, B), the coercivity (Hc) is extremely high. This property makes the magnetization of the magnet body composed of a rare-earth element alloy very stable, i.e., it cannot easily be demagnetized.

It was a well known fact that permanent magnets positioned on both sides of a flat steel body can magnetize the steel to a high level, if the magnet poles were the same on each side, i.e., the magnets would repel each other. However, in the past, large magnet volumes were required to achieve any substantial magnetization. With the new powerful magnets, the magnet volume could be relatively small to generate high steel magnetization. In 1981 this author determined the optimum ring size for samarium-cobalt magnets. Maximum steel magnetization (near saturation) could be obtained if the rings were stacked to make a roll using a 4:1 ratio of magnet to steel thickness, see Figure 1. Since magnetized particles are attracted to the magnetized steel surface on the roll periphery, this means that 20% of the exposed roll surface would collect such material. This collection area is an order of magnitude greater than what could be achieved with prior art magnets, making the magnetic roll useful for mineral separation.

Although one of the first prototype rare-earth magnetic rolls was calculated to have about 14,000 gauss steel magnetization, it was found in comparative testing with electromagnetic induced roll (IMR) separators operating at about 21,000 gauss, that similar performance was obtained in fine particle processing (smaller than 1 mm). When processing coarser particles an improved performance was established (e.g., less weakly magnetic contaminants remaining in the upgraded product and fewer separation passes to achieve high quality). The improvement results because the magnetic force acting on the particles is high, due to a high flux gradient. An electromagnetic induced magnetic roll separator has an air gap, which must be increased to accommodate the processing of larger particles. The rare-earth magnetic roll (REMR) magnetic separator has no such air gap. Consequently, the magnetic force does not decline in the manner of an IMR set with a large air gap.

As the name implies, suspended magnets are installed over conveyors to lift tramp iron out of the burden. Suspended magnets have been more frequently applied as conveyor speeds have increased. Suspended type magnets are capable of developing very deep magnetic fields and magnet suspension heights as high as 36 are possible.

Suspended magnets are of two basic types (1) circular and (2) rectangular. Because of cost considerations, the rectangular suspended magnet is nearly always used. Magnet selection requires careful analysis of the individual system to insure adequate tramp iron removal. Factors that must be considered include:

The position in which the magnet must be mounted will also influence the size of magnet required. The preferred position is at an angle over the head pulley of the conveyor where the load breaks open and the tramp iron is free to move easily to the magnet face. When the suspended magnet must be mounted back from the head pulley parallel to the conveyor, tramp iron removal is more difficult and a stronger magnet is required.

Magnetic drum separators come in many different styles. Tramp iron drum separators usually use a magnet design referred to as a radial type. In such a unit the magnet poles alternate across the width of the drum and are of the same polarity at any point along the drums circumference. The magnet assembly is held stationary by clamp bearings and the drum shell is driven around this magnet assembly.

Drum-separators lend themselves to installation in chutes or at the discharge point of bucket elevators or screen conveyors.The capacity and type of tramp iron to be removed will determine the size selection of a drum separator. They are available in both permanent and electro magnetic types.

Standard drum diameters are 30 and 36. General guide lines, in diameter selection, are based on (1) feed volume (2) magnetic loadings and (3) particle size. The 30 diameter drum guide lines are roughly maximum of 75 GPM per foot feed volume, 8 TPH per foot magnetic loading and 10 mesh particle size. The 36 guide lines are 125 GPM per foot feed volume, 15 TPH per foot magnetic loading and 3/8 inch particle size.

For many years, wet magnetic drum separator magnet rating has been on the basis of a specified gauss reading at 2 from the drum face. The gauss reading is an average of readings taken at the centerline of each pole and the center of the magnet gap measured 2 inches from the drum surface. This rating tends to ignore edge of pole readings and readings inside of the 2 inch distance, particularly surface readings which are highly important in effective magnetic performance.

We have previously discussed dry drum separators as used for tramp iron removal. A second variety of drum separator is the alternating polarity drum separator. This separator is designed to handle feeds having a high percentage of magnetics and to obtain a clean, high grade, magnetic concentrate product. The magnet assembly is made up of a series of poles that are uniform in polarity around the drum circumference. The magnet arc conventionally covers 210 degrees. The magnet assembly is held in fixed operating position by means of clamp bearings and the cylinder is driven around this assembly.

Two styles of magnet assemblies are made up in alternating polarity design. The old Ball-Norton type design has from 8 to 10 poles in the 210 arc and develops a relatively deep magnetic field. This design can effectively handle material as coarse as 1 inch while at the same time imparting enough agitation in traversing the magnetic arc to effectively reject non-magnetic material and produce a clean magnetic concentrate product. The 30 diameter alternating polarity drum is usually run in the 25 to 35 RPM speed range.

Application of the high intensity cross-belt is limited to material finer than 1/8 inch size with a minimum amount of minus 200 mesh material. The cost of this separator is relatively high per unit of capacity approaching $1000 per inch of feed width as compared to $200 per inch of feed width on the induced roll separator.

This investigation for an improved separator is a continuation of the previously reported pioneering research of the Bureau of Mines on the matrix-type magnetic separator. When operated with direct current. or a constant magnetic field, the matrix-type magnetic separator has several disadvantages, which include incomplete separation of magnetic and nonmagnetic components in one pass and the retention of some of the. magnetic fraction at the discharge quadrant. Since the particle agitation that results from pulsed magnetic fields may overcome these factors, operation with an alternating current would be an improvement. Another possibility is the separation of dry feeds, which may have applications where the use of water must be avoided.

The effects of an alternating field were first described by Mordey and later by others of whom Doan provides a bibliographical resume. The significant feature to note in the description by Mordey is the change from a repulsion in weak fields to an attraction in strong fields, in addition to a difference in response with different minerals. The application by Mordey was with wet feeds using launders and inclined surfaces, although applications by others are with both wet and dry feeds.

Except for occasional later references the interest in alternating current for magnetic separation has almost disappeared. Lack of interest is probably due to the apparent high power consumption required to generate sufficiently intense magnetic fields, a problem that warrants further consideration.

The matrix separator differed somewhat from the slotted pole type described in a previous report in that the flux passed into the matrix from only one side, the inverted U-shaped magnet cores 4 and 7 illustrated in figure 1. Figure 1 shows a front view, side view, and a bottom view of the matrix-type magnetic separator. By this arrangement, an upward thrust could be exerted on the matrix disk during each current peak; the resulting induced vibration would accelerate the passage of the feed as well as the separation of the magnetic particles from the nonmagnetic particles since the applied field during the upward thrust preferentially lifts

The matrix disk 5 rotates successively through field and field-free quadrants. Where a given point on the disk emerges into a field quadrant, feed is added from a vibrating feeder; nonmagnetic particles fall through the matrix, and magnetic particles are retained and finally discharged in the succeeding field-free quadrant.

Two types of disks were used, a sphere matrix illustrated in top and cross-sectional views in figure 2 and a grooved plate type similarly illustrated in figure 3. Both the spheres and grooved plates were mounted on a nonmagnetic support 1 of optimum thickness for vibration movement (figs. 2-3). The sphere matrix disk, similar to that of the earlier model, had a matrix diameter 8 of 8.5 inches and spokes 7 spaced 45 apart; the spheres were retained by brass screens 4 (fig. 2).

The grooved plate disk was an assemblage of grooved steel plates that tapered so that one edge 5 was thinner than the other 6 (fig. 4) to provide a stack in the form of a circle having an outside diameter 9 of 7.9 inches (fig. 3). The plates were retained by two split aluminum rings 8 and 3 clamped in two places 1 and 11. They were stacked so that the vertically oriented grooves of one plate touched the flat side of the second plate. As illustrated in figure 4, two slots 3 and 4 were added to reduce eddy current losses.

Both disks 5 illustrated in figure 1 were rotated by a pulley 1 through a steel shaft 8 held by two aluminum bars 2 and which in turn were fastened to aluminum bars 3 and steel bars 6. The magnetic cores 4 and 7 were machined from 10- by 12-inch E-shaped Orthosil transformer laminations. For wet feeds,

With the information derived from the performance of this separator, a cross-belt-type separator was also constructed as illustrated in figure 5, which shows a front view and a cross-sectional view through the center of the magnet core. The cross-belt separator mentioned here differs somewhat from the conventional cross-belt separator in that the belt 5 moves parallel to the feed direction instead of 90 with the feed direction. The magnetic core, composed of parts 17, 19, 21 and 22 that were machined from 7--by 9 inch E-shaped Orthosil transformer laminations, supplies a magnetic field between one magnetic pole 6, which has grooves running parallel to the feed direction, and the other magnetic pole 14. Owing to the higher intensity field at the projection from the grooves, magnetic particles are lifted from feeder 15 to the belt 5. By movement on flat-faced pulleys 3 supported by bearings 4 the belt 5 carries the particles to the discharge chute 7. Nonmagnetic particles fall from the feeder edge and are discharged on the chute 8. A special 0.035-inch-thick Macarco neoprene-dacron endless belt permits a close approach of the feeder surface to the magnet pole 6. The feeder 15 constructed of plexiglass to prevent vibration dampening by eddy currents, is fastened to a vibration drive at 16 derived from a small vibrating feeder used for granular materials. A constant distance between poles 6 and 14 was maintained by acrylic plastic plates 9 on each side of the poles 6 and 14 with a recessed portion 13 to provide room for the belt 5 and feeder 15. The structural support for the separator, which consisted of parts 1, 2, 11, 18, and 20, was constructed of 2- by 2- by -inch aluminum angle to form a rectangular frame, and part 10 was machined from angular stock to form a support for the magnet core.

Each U-shaped magnet core in figure 1 was supplied with two 266-turn coils and two 133-turn coils of No. 10 AWG (American wire gage) heavy polythermaleze-insulated copper wire. With alternating current excitation, the current and voltage are out of phase so that the kilovolt-ampere value is very high even though the actual kilowatt power is low. This difference may be corrected with either series capacitors to reduce the input voltage or parallel capacitors to reduce the input current. However, the circuit that was selected is illustrated in figure 6 in which the two 266-turn coils are connected in series with the capacitor 2. Power is supplied by the 133-turn drive coil 7 that is connected in series with the 133-turn drive coil 9 on the other U-shaped magnet core. Coils 4 and 6 and the capacitor 2 form a circuit that resonates at 60 hertz when the capacitor 2 has a value of 49 microfarads in accordance with the equation

For the capacitance in the power input circuit, the value is calculated on the basis of the equality of equations 2-3. When the input at point 10 is 10 amperes at 126 volts or 1.26 kilovolt-amperes, the current at point 3 and the voltage at

point 1 are 10 amperes and 550 volts, respectively, or a total of 11.0 kilovoIt-amperes for the two magnet cores, which provides a 5,320-ampere- turn magnetization current. The capacitors, a standard power factor correction type, had a maximum rating of 600 volts at 60 hertz.

Application of alternating current to the cross-belt separator is not successful. In contrast to the matrix-type separator in which the feed is deposited on the magnetized matrix, the feed for the cross belt is some distance below a magnet pole where the field is weaker and the force is a repulsion. Even though the magnetic force with the matrix-type separator may be a repulsion instead of an attraction, it would result in the retention of the magnetic fraction in the matrix. Replacement of the alternating current with an intermittent current eliminates the repulsion effect but still retains the particle vibration characteristics.

For an intermittent current the circuit shown in figure 7 is used. A diode 5 supplies the current to a coil 4, which can be the magnetizing coil for the cross-belt separator, or for one magnet core of the matrix-type separator that is connected in parallel or series with the coil for the other core. A coil 2 is supplied with half-wave-rectified current from a diode 6 but is out of phase with the other coil 4 and is only applicable to a second separator. However, the circuit illustrates the reduction of the kilovolt-ampere load of intermittent magnetizing currents. As an example, measurements were, made with the two magnet cores of figure 1; each core had 532 turns of wire. When the capacitor 9 has a value of 72 microfarads, the current at point 8 is 13 amperes, and the voltages at points 10, 1, and 7 are 75, 440, and 390 volts, respectively. The kilovoIt-ampere input at point 11 is therefore 0.98, and the kilovolt-amperes supplied to the coils is 5.07. This circuit is not a simple resonance circuit, as shown in figure 6, but a circuit in which the correct value of the capacitor 9 depends on the current. At currents lower than 13 amperes, the 72-microfarad value is too large.

However, separations with intermittent current were confined to a simple one-diode circuit. With the matrix-type separator, each magnet core carried 10.5 amperes at 240 volts through 399 wire turns or a total of 21 amperes since the two cores were connected in parallel. For the cross-

belt separator illustrated in figure 5, five 72-turn coils and one 96-turn coil wound with No. 6 AWG heavy polythermaleze-insulated square copper wire were used in series connection. Current-carrying capacity is approximately 40 amperes with an input of approximately 80 volts of half-wave-rectified 60-hertz current. At 40 amperes, the average number of ampere turns would be 18,240. Intermittent current and voltage were measured with the same dynamometer meters used for alternating current; these meters measure an average value.

It is possible to increase the magnetizing current for the matrix-type separator without excessive vibration by increasing the thickness of the plate 1 (figs. 2-3). Another alternative is a combination of intermittent and constant magnetic fields. Although a variety of circuits are possible, the combination of fields was accomplished with the simple adaptation of the stray field losses in a U-shaped magnet core using the circuit of figure 8. The power drawn is full-wave rectification, or half wave for each leg of the magnet core with the flux, from the coils 3 and 4 adding. Owing to magnetic leakage, the flux from the coil nearest to the magnet pole tested predominates. When the magnetic field is measured with a Bell model 300 gaussmeter and observed with a Tektronix type 547 oscilloscope with a type 1A1 amplifier, the results of figure 9 represent a pulsating magnetic field on top of a constant magnetic field plateau.

Although it is known that minerals in water suspension may be separated in the constant-field matrix-type separator at fine sizes, some tests were conducted to investigate if any beneficial effects exist with an intermittent field. One advantage that was found with a minus 325-mesh feed was an increase in the completeness of the discharge of the magnetic fraction with an intermittent field as illustrated in tables 1-2. Both tests had the same average current of 10.5 amperes through the magnetizing coils of each magnet core illustrated in figure 7. The matrix consisted of 1/16-inch-diameter steel spheres.

In the two short-period comparative tests, the wash water for removing the magnetic fraction was the same and was of a quantity that permitted complete discharge with the intermittent field and partial removal with the constant field. After the test was completed, magnetic particles retained with the constant field were determined by a large increase in the intensity of flow of wash water, a flow volume that would not be practical for normal operation. For separation efficiency, the intermittent field had no advantage over the constant field probably because of a lack of vibration response with minus 325-mesh particles at 60 hertz. This will be described later with dry feeds.

Dry magnetic separation at coarse sizes is not a problem because it may be accomplished with a variety of separator types. Difficulty at fine sizes is twofold. First, the feed rate capacity decreases in the separators with moving conveyor surfaces such as the induced roll and cross-belt separators in which the attracted magnetic particles would have to move at nominal feed rates through a thick layer of nonmagnetic particles; second, an agglomeration effect is present that increases with decrease in particle size.

Results of the separation of several mineral combinations in the size range of minus 200 plus 325 mesh are summarized in tables 3-5. Table 3 illustrates the separation of -Fe2O3 from quartz in an ore with one pass through a matrix of 1/8-inch-diameter steel spheres using the alternating current circuit of figure 6.

Application of an intermittent field with a matrix of 75 percent 1/16-inch-diameter steel spheres and 25 percent 1/8-inch-diameter steel spheres is illustrated in table 4 in a one-pass separation of pyrrhotite from quartz using the circuit of figure 7. Unlike table 3, no attempt was made to obtain an intermediate fraction, which would have resulted in raising and lowering the iron compositions of the magnetic and nonmagnetic fractions, respectively, and provided a fraction for repass with increased recovery.

Table 5 gives the results of the application of a partially modulated field using the circuit of figure 8 and the grooved plate matrix of figure 3 in a one-pass separation of ilmenite from quartz. The advantage of the grooved plate over the spheres is that the particles pass through the matrix in a shorter time. The high flow rate obtained using the grooved plate could be increased further, particularly if water is used, by attaching suction chambers under the disk in a manner similar to applications with continuous vacuum filters. Although the grade and recovery of ilmenite are very high, this need not necessarily be attributed to the grooved-plate matrix since the ampere turns are higher than in any of the other tests. Increased ampere turns is a prerequisite for successful application of alternating current separators and intermittent current separators.

When a minus 325-mesh fraction is tested, a separation sometimes occurs, but in most cases the feed passes through without separation. Response at higher frequencies was investigated with a smaller -inch-cross section U-shaped magnet core 1 (fig. 10). Separation was performed with a nonmagnetic nonconducting plane surface 3 moved manually across the magnet pole as illustrated by the direction arrow 4. When separation occurred, the nonmagnetic mineral 5 would move with the plane, and the magnetic mineral would separate from the nonmagnetic mineral by remaining attached to the magnet pole. When no separation occurred, the entire mixture of magnetic and nonmagnetic minerals would either move with the plane or adhere to the magnet pole.

Four magnetising coils of 119 turns each of No. 14 AWG copper wire were used; three were connected in series with a capacitor as in figure 6, and one was connected to a variable-frequency power supply. The current in the resonant circuit is approximately 5 amperes. When the capacitor has a value of 49 microfarads, the resonant frequency is 130 hertz, and no separation occurs. With the capacitor reduced to 10 microfarads to provide a resonant frequency of 300 hertz, a separation occurs. In the case of a minus 325-mesh -Fe2O3-quartz mixture, most of the quartz moves with the plane, and the -Fe2O3 remains attached to the magnet pole. Similar results are obtained with pyrrhotite-quartz. Indications are that the separation may be improved with preliminary treatment of the feed by dry grinding aids.

frequencies, the time per cycle is too short to permit initial magnetization; at very low frequencies, the magnetization is in phase with the field. The frequencies reported here are between these two extremes and probably near, and just above, the low frequency limit. Experimental values on particles in the size range of minus 35 plus 65 mesh were previously published. These data indicate that 0.16 second, the time required to traverse a magnetizing field distance of 0.9 inch at 5.5 inches per second, is adequate time for the magnetization of minerals, but 0.02 second, the time required to traverse approximately 0.1 inch at the same rate, is too short. Time lag has been reported in the literature for magnetic alloys and has been classified, to the exclusion of the eddy current lag, into a lag that is dependent on impurities and a Jordan lag that is independent of temperature.

From evidence derived from the Barkhausen effect, the magnetization does not proceed uniformly and simultaneously throughout a specimen but is initiated in a limited region from which it spreads in a direction parallel to the field direction at a finite velocity. In a changing magnetic field, the number of initiating nuclei is proportional to the cross-sectional area perpendicular to the direction of the field. For a specimen in the form of a cube, the rate of energy W transferred to the cube would therefore be proportional to the aforementioned cross-sectional area so that for a cube of side s,

Application of intermittent current to the cross-belt separator arose from the need for the dry separation of an iron composition material from the copper in a product submitted by personnel of a Bureau of Mines chalcopyrite vacuum decomposition project. Although this product was of a relatively coarse size, the matted mass resulting from the needle shape or fiber form of the copper and the magnetic field coagulation effects of the magnetic particles prevented use of commercial dry separators such as the induced roll separator and constant-field cross-belt separator. The pulsating magnetic field had a separation effect similar to the pulsations in a hydraulic jig; the pulsating magnetic field permits the nonmagnetic fibers to sink back to the vibrating feeder and allows the magnetic particles to rise to the belt. Other applications would include fibrous minerals such as tremolite, actinolite, and chrysolite, and matted and fibrous secondary materials.

Application of alternating and intermittent current to magnetic separation at a relatively high number of ampere turns was made possible by special electronic circuits. Actual power losses are low and include the IR loss, which is the same that occurs in direct-current magnetic separation, and the core loss, which has a magnitude corresponding to the IR loss. Minerals may be dry-separated close to the minus 325-mesh size at 60-hertz frequency and possibly at smaller particle sizes at higher frequency. In the wet separation of minus 325-mesh feeds, intermittent current provides for complete release of the magnetic fraction during the discharge cycle. For matted fibrous and magnetically coagulating feeds, a cross-belt separator with an intermittent magnetizing current provides efficient separations.

k&j magnetics - build a magnet separator tool

k&j magnetics - build a magnet separator tool

We are often asked how we separate large magnets. We have built several magnet separator tools over the years and have been continually improving the design. The tool is made out of wood and is fairly simple to build with only a basic woodworking knowledge. Here we will illustrate and explain the process of building such a tool.

WARNING: Follow all safety procedures when working with and operating woodworking tools. This page is meant only as a guide and not as a step-by-step procedure. Observe all warnings and safety precautions with each tool. Read every users manual from front to back and memorize the part number for every replacement part of each tool before proceeding.

DISCLAIMER: Any information posted on this site is as a public service. Users of this web site are responsible for checking the accuracy, completeness, currency and/or suitability of all information themselves. K&J Magnetics, Inc. does not represent, guarantee or warranty the accuracy, completeness, currency, or suitability of the information on this web site. K&J Magnetics, Inc. specifically disclaims any and all liability for any claims or damages that may result from providing the web site or the information it contains, including any web sites maintained by other parties and linked to this web site.

making oxygen-how to use magnets to separate oxygen from air | science and technology - eminetra

making oxygen-how to use magnets to separate oxygen from air | science and technology - eminetra

OXYGEN is important.. Literally for breathing, and therefore for many inpatients. And figuratively, it applies to the industries that use it in their processes, from steelmaking to pharmaceuticals. Therefore, the global gas market is large. According to various estimates, it was between about $ 28 billion and $ 49 billion in 2019.

However, it can be larger. A series of reactions, including oxygen and steam, can convert fossil fuels such as coal and natural gas into the energy sources hydrogen and carbon dioxide, which can be separated and sequestered underground. It may enable their continued employment in a world of limited greenhouse gas emissions. However, it requires a cheap and abundant supply of oxygen. Thats why the US Department of Energy is sponsoring a project that aims to use magnets to extract oxygen from the atmosphere.

Dry air is a mixture of 21% oxygen, 78% nitrogen, 1% argon and other trace gases such as carbon dioxide. Today, most of the pure oxygen in the world is made by liquefaction followed by distillation of air, separating the air into its constituents. This is done in a large factory. Another source of oxygen, which is slightly less pure, is a small, mobile plant called an oxygen concentrator. They absorb nitrogen into a porous material called zeolite, leaving a gas that is 90% oxygen, or force air through a membrane that is more permeable to one gas than the other, making it slightly thicker. Produces no mixture. The magnetic separation alternative is the brainchild of John Vetrovec, the boss of Aqwest, a technology company in Larkspur, Colorado.

Oxygen cannot be permanently magnetized like elements like iron, but it is attracted to magnetic fields. As a result, when air is pumped through such fields, the oxygen concentrates in those places where the fields are strongest. This improvement in concentration is small. However, if the oxygen-rich part of the airflow can be separated from the oxygen-deficient part and treated over and over again in the same way, it will be concentrated until it is pure enough to be useful. can do. Dr. Betrobeck believes he knows how to do this.

Previous attempts by another group of engineers used pulsed electromagnets. However, this required both the high voltage, which is expensive to build, and the electromagnet itself, which is expensive to buy and run. Dr. Betrobeck will perform his version of the trick at atmospheric pressure, using permanent magnets. Both of these changes significantly reduce power consumption. In fact, the only moving part of the device is the blower that pushes the air.

A magical addition to Aqwests party is a series of structures called microchannels. These are tubes less than 1 mm in diameter intended to carry liquids or gases. The important thing is that those narrow bores ensure a laminar flow of fluid through them. Translated from the story of physics, this means that it does not cause turbulence, so there is no mixture of their content. It allows them to act as a gas separator for company equipment.

At first glance, the first result is not very impressive. The prototype results in a concentration increase of about 0.1% per passage, but Dr. Vetrovec believes his team can raise this to 0.4%. But the important thing is repetition. As a reward for a service, like the story of the Chancellor who asked the king about the oxygen concentration, such as one grain of rice in the first square of the chess board, two grains in the second, and four grains in the third. It rises rapidly with continuous repetition. Thirty passages at a higher rate yield a 90% concentration of oxygen, which is commercially useful.

It remains to be seen if this approach proves to be cheaper than the actual established alternatives, and if so, whether it really saves fossil fuel bacon. However, some future versions of green energy involve the use of large amounts of hydrogen, so better ways to produce that gas are always welcomed. Meanwhile, many other users of oxygen will certainly welcome cheap sources. The idea of doing this with a magnet is fascinating.

magnetic separation equipment | bunting

magnetic separation equipment | bunting

BuntingMagnetic Separation Equipment is used in the food, dairy, grain & milling, chemical, plastics, oil, textile, recycling, and other industries for applications and products similar to yours. With our products, you have a single source of supply for everything you need for efficient separation. You can rely on our equipment and expertise to eliminate product contamination and damage to machinery from tramp metal in an economical and cost-effective way. Your equipment can be ordered to meet specific construction standards and customized to satisfy your special requirements.

Our sanitary-grade metal separators are the first separators to earn USDA, AMS-Acceptance. Our engineers refined existing designs to help processors meet increased marketplace demands and governmental requirements for safer and purer foodstuffs, meats, pharmaceuticals, and chemicals. All of these approved models have met or exceeded the USDA, AMS criteria as published in the NSF/ANSI/3-A 14159-1 2002 specifications, passed inspection, and earned the right to bear the USDA, AMS Meat and Poultry Accepted Equipment logo.

Metal-Detectable Gaskets and Grommets add another layer of safety in our food-grade (or higher) Magnetic Separation equipment including HF Drawer Filters, Magnetic Liquid Traps, In-Line Magnets, Hump Magnets. Your increased demands for product safety are met even more with this industry-leading feature. With Metal-Detectable Gaskets and Grommets, if a piece chips off or the gasket breaks, it is immediately caught by the equipments magnetic cartridge or plate. The broken piece can also be seen in any metal detection or x-ray system.

The CR-MLT offers high separation capabilities combined with exceptional resistance to corrosion, providing a solution for customers in a wide range of industries who are handling corrosive and acidic materials.

The CR-MLT offers high separation capabilities combined with exceptional resistance to corrosion, providing a solution for customers in a wide range of industries who are handling corrosive and acidic materials.

FF Series Drawer Magnets are built with strong Rare Earth magnets for strong holding force ingravity flow applications. They are temperature compensated with stainless steel construction and designed for the Plastics Industry.

FF Series Drawer Magnets are built with strong Rare Earth magnets for strong holding force ingravity flow applications. They are temperature compensated with stainless steel construction and designed for the Plastics Industry.

HF Drawer Magnets are for gravity flow applications. They house two or more magnetic cartridges for efficient product separation. For all industries - Food, Grain and Milling, Powder and Bulk, Recycling, and Plastics.

HF Drawer Magnets are for gravity flow applications. They house two or more magnetic cartridges for efficient product separation. For all industries - Food, Grain and Milling, Powder and Bulk, Recycling, and Plastics.

Magnetic Liquid Traps remove ferrous tramp including 400 series stainless steel and work-hardened stainless steel from liquid processing and conveying lines. Comes in several styles of traps with High-energy, temperature compensated Neodymium Magnets. Metal Detectable gaskets are standard. For the Food and Powder and Bulk Industries.

Magnetic Liquid Traps remove ferrous tramp including 400 series stainless steel and work-hardened stainless steel from liquid processing and conveying lines. Comes in several styles of traps with High-energy, temperature compensated Neodymium Magnets. Metal Detectable gaskets are standard. For the Food and Powder and Bulk Industries.

Plate Magnets capture fine metal particles from chutes, suspended in powdery, moist, clumpy, abrasive or bulk materials. Various models available. For all industries including, Food, Powder & Bulk, Grain & Milling, Recycling and Plastics.

Plate Magnets capture fine metal particles from chutes, suspended in powdery, moist, clumpy, abrasive or bulk materials. Various models available. For all industries including, Food, Powder & Bulk, Grain & Milling, Recycling and Plastics.

magnetic separation basics - recycling today

magnetic separation basics - recycling today

Magnetic separation systems began appearing in scrap yards after World War II when heavy duty shredders used for grinding automobiles started to pop up across the United States. The early magnetic separation systems were mainly electromagnets; permanent magnets began making inroads when ceramic material became available and the cost to produce them decreased significantly, providing field strengths matching those of their electromagnet cousins. In addition, permanent magnets did not have to rely on an outside power source, and did not have the overheating problems associated with the early electromagnets, which were usually expensive and bulky.

As the scrap industry evolved, magnetic separation systems evolved, too. By the end of the 1970s, three main types of magnetic separation systems were prevalent: the overhead magnet; the magnetic pulley; and the magnetic drum. And by the end of the 1980s, another form of magnetic separator, the eddy current, was becoming popular with both scrap processors and municipal recyclers. Although the eddy current will not be discussed here, its contribution to the recycling industry has been significant. An eddy imparts a magnetic charge to nonferrous metal material via a revolving, alternating-pole magnet usually under the conveying belt and in the head pulley. When the charged particle comes in contact with the field of an opposite pole, it is repelled and sorted.

Today, magnetic separation still dominates the way processors remove ferrous from nonferrous material. While permanent magnets are popular choices, advances in electromagnets have made them competitive again.

The first type of magnetic separation equipment is the overhead magnet. These are stationary magnets with self-cleaning belts that rotate around the magnet assembly. The cleated belt moves the attracted ferrous material and sorts it out of the magnetic field. These magnets can be configured in two main ways parallel to the conveyor, referred to as inline; or perpendicular to the conveyer, referred to as crossbelt. Other configurations are actually variants of the overhead magnet where multiple magnets are used to transfer ferrous material from one magnet to another. These magnets are referred to as "multi-stage" magnets.

In an inline application the magnet is normally positioned at the end of the conveyor above the head pulley. The main advantage to positioning the magnet in this fashion is that entrapment of ferrous pieces and particles is reduced. Material is freed once it leaves the conveyor belt and the magnet can pluck suspended ferrous material out of the air.

If the conveyor is on an incline, the momentum of the particles leaving the conveyor belt results in an initial trajectory upward and toward the magnet. Thus, the material gets closer to the magnet and the ferrous particles have a better chance of getting picked up.

"No matter how hard a processor tries to prevent entrapment, it is always going to occur with an overhead magnet," says one manufacturer of magnetic separation equipment. "But it is not going to occur as much in an inline configuration as it is with in a crossbelt arrangement."

It is especially tough to pull out ferrous from wet, shredded wood streams with an overhead magnet, because the shreds start to interlock and clump. Suppliers say that wet wood and any other wet material is more difficult to process, and should be avoided if possible when applying magnetic separation. However, an inline configuration can free up more of the ferrous material for separation.

For inline applications, the magnet should be the width of the conveyor. Some manufacturers have square magnets. Others offer rectangular magnets where the longer length of the magnet is parallel to the conveyer, providing more coverage of the belt.

The other application for an overhead magnet is in the crossbelt configuration. This is a popular installation because placing the magnet inline over the head pulley is not always practical there may be other equipment, such as a magnetic pulley or an eddy current separator, at the end of the conveyor. Plus, material recovery facility operators like the crossbelt configuration because the magnet can be positioned close to the hand picking stations, and because slower belt speeds increase the magnets efficiency.

In both the inline and the crossbelt configurations, the overhead magnet is working against gravity, so it has to work harder and normally has to be more powerful than a magnetic pulley or drum. However, the inline setup requires less field strength than the crossbelt, because it does not have to combat entrapment, nor does it have to change the direction of the ferrous material. Therefore, an inline overhead magnet can cost less than one used in a cross-belt configuration.

Variants of the overhead magnet include single- and three-stage magnets. In a single-stage magnet, ferrous material is carried through a magnetic field and offloaded onto another conveyor, while nonferrous material drops down into a container.

In a three-stage configuration, the ferrous goes through three separate magnets that are contained in a single housing. When the ferrous material is transferred from one magnet to the other, the particles are flipped and any entrapped nonferrous material falls out, resulting in a cleaner end product. Both the single- and three-stage variants are powerful magnets that can pick up heavy pieces of ferrous metal.

While many manufacturers sell both permanent and electromagnetic configurations, one manufacturer recommends that a processor use an electromagnet in the overhead position when the distance between the magnet and conveyor has to be greater than 12 inches.

Another type of magnetic separator is the magnetic pulley. In this configuration the magnet is embedded in the head pulley of the conveyor. As the pulley spins, the magnetic force grabs the ferrous particles and carries them around and under the pulley until the natural belt separation from the face of the pulley forces the particles to fall in a separate bin. While suppliers are wary of recommending a pulley versus an overhead magnet unless they know the specific application, most say that, generally, a pulley will pull out finer particles of ferrous than an overhead magnet.

This better sort is possible because material is closer to the magnet, which is just under the belt. Also, the pulley has gravity working in its favor. This method, however, may not be effective in pulling off larger pieces of ferrous material or material that is trapped on top of the material stream.

Another drawback of the magnetic pulley is that the strength of the magnet is limited by the size of the pulley. Usually, a magnetic pulley can achieve only 6 to 7 inches of penetration at best, according to one supplier.

Magnetic pulleys can also be configured in conjunction with an overhead magnet. These combinations are recommended when the material stream contains a preponderance of ferrous metals. When this is done, make sure that the two types of magnetic devices are adequately separated by 8 feet or even more in some cases in order to avoid magnetic interference.

In order to determine the optimal type and position of a magnet, its useful to calculate burden depth. Several factors must be considered before the calculation can be made. The operator must know capacity in cubic feet per minute (C); belt width in feet (W) and belt speed feet per minute (V); and the burden depth factor (F). The F factor is needed to compensate for the normal dip in the center of the conveyor; and to compensate for the tilt angle of the magnet if it is positioned over the head pulley at the end of the conveyor.

For example, consider an operation which has a 3-foot wide conveyor belt with outside idlers at 35-degree angles. The speed of the conveyor is 500 feet per minute, and the capacity of the conveyor is 800 tons per hour of material.

First, the capacity of 800 tons per hour needs to be converted into cubic feet per minute. In order to accomplish this, the material density of the main medium must also be known. Lets say the material is 3-inch minus in size, with a density of 50 pounds per cubic foot. In this case the capacity in cubic feet per minute would be: (800 tons per hour)(2,000 pounds/1 ton)(1 hour/60 minutes)(1/50 pounds per cubic foot) = 533 cubic feet per minute.

Drum magnets are similar to pulley magnets; however, in the drum magnet, the magnetic element is stationary and positioned only on one side of the drum with a maximum of 180 degrees of arc. While the outer casing of the drum rotates, material is pulled through the magnetic field.

Drum magnets can be positioned for three methods of feed: up-and-over feed; down-and-under feed; and top feed. In an up-and-over configuration, ferrous is lifted out of the stream and carried up and over the magnet while the nonferrous material drops off the feeder. This application is commonly used in auto shredders, ash handling and other high-ferrous content streams.

In down-and-under feed, ferrous is carried under the drum and dropped on the other side. It has the shortest and most direct transfer area for the ferrous and is usually used for streams with larger ferrous pieces.

Finally, in the top-feed configuration, material cascades off the front side of the drum and the ferrous is carried through the magnetic field and separated. This type is used mainly for material streams that contain ferrous with weak magnetic properties.

The preponderance of drum magnets used today are in the scrap industry and on auto shredders. They are normally fed by a vibratory feeder or conveyor, and the speed of the drum can be adjusted to match the incoming feed. As with all types of magnetic separation equipment, the incoming feed must be controlled so that it does not overwhelm the ability of the magnet to pull out ferrous.

Drum magnets also come in two types: axial- and radial-pole. In an axial-pole drum magnet, the alternating poles are situated along the circumference of the drum. This configuration results in the same polarity across the width of the drum. With the same polarity across the width, there arent any dips in the magnetic field. So, axial-pole drum magnets are recommended for pieces that are 1 inch or less in size.

Radial-pole drum magnets have the same polarity along the circumference of the drum, which gives alternating polarity across the width. This results in dips in the magnetic field across the width of the drum. Therefore, radial-pole drum magnets are recommended for material pieces of 1 inch or greater.

Again, these types of magnets can be permanent or electromagnet. One manufacturer recommends that auto shredder operators considering adding a drum magnet install an electromagnetic one because it is hard to work around a permanent magnet in that configuration.

There are several areas to consider before buying a magnetic separation device. Processors must consider the depth of material that will be processed (the burden depth); the range of particle size; conveyor troughing; speed, width and overall capacity of the conveyor; and the density of the material stream.

Conveyor troughing applies only to overhead magnets because conveyors normally run in a concave fashion so that material does not fall off when the conveyor is moving. Therefore, the overhead magnet field must be able to reach into the trough of the conveyor to pull out material. Idlers on the end of the conveyor are normally inclined at 20, 35 or 45 degrees to create the trough.

Burden depth is the average depth of the material on the conveyor belt. Calculating burden depth is useful to determine the maximum amount of material that the magnetic field must penetrate, and to position the magnet optimally over a conveyor (see sidebar). Many suppliers will give processors a chart that has the burden depths and other data for the different streams that a company may run, and for different throughputs.

Magnets are usually positioned for the most difficult situation. "That is the first thing we ask is what is the range of materials being processed," says one supplier. "We want to make sure that the magnet is large enough to pick up the target material in the most demanding scenario possible."

While most overhead magnets are adjustable, some scrap companies and recyclers have built special platforms for the overhead magnet so that it can be adjusted to the optimum height more quickly. One company that was processing a wide range of materials needed to constantly adjust its overhead magnet, so it built a hydraulic platform for the overhead magnet that could be easily raised or lowered depending on the application

Another supplier recommends that buyers considering purchasing an electromagnet should check to see if the magnetic circuit is balanced and provides a uniform magnetic field and the appropriate depth of field. Unbalanced electromagnets can cause excessive power drains .

Over the years, steel mills have been steadily increasing their use of scrap. At the same time, end users of steel products, such as automobile manufacturers, have stepped up their quality requirements. As a result, mills are buying more scrap material which must be consistently delivered and of a higher quality. In order to better control their raw material, a few mills such as North Star Steel, Minneapolis, own and operate their own scrap processing and brokerage facilities. Other mills designate preferred or even exclusive suppliers, and may even agree for a scrap processor to operate on their facilities, handling all stages of scrap preparation right up to loading charging buckets.

"There seems to be, across the steel industry, a trend toward putting suppliers in the position to supply mills needs," says William Heenan, president of the Steel Recycling Institute, Pittsburgh. "In scrap, simplistically, this means they tell suppliers, Im making this kind of steel give me scrap that provides the right residuals, etc., to make the right kind of steel. Weve seen a number of companies do that. This type of effort is now being pushed by suppliers as well. The steel companies like outsourcing, in some respects. It puts the burden on the guy that has the scrap."

This trend shows the level of trust that has been building up between mills and suppliers for the past 10 or 15 years, he says, and leads to all sorts of benefits. "It builds a stronger relationship when they are that dependent on each other," he says. "Having a scrap supplier on site really allows companies to cut their inventory costs it prevents the necessity of having two sets of inventories."

Luntz Corp., Canton, Ohio, which was on the road to being purchased by Philip Environmental Inc., Hamilton, Ontario, at press time, has a close relationship with the ARMCO mill in Mansfield, Ohio. The mill has entrusted all of its scrap handling operations to the scrap supplier, according to Eric Schnackel, assistant manager of Luntz Mansfield facility.

"One hundred percent of ARMCOs scrap, and other furnace materials including coal and lime, come through here," says Schnackel. "We load the charging buckets and then send it to the furnace, and then they send the buckets back and we reload them."

The two companies negotiated the agreement about a year ago, he says. "Basically, we took over their stockhouse. ARMCO handles the purchasing, but we do the inspections and grading. If theres a problem, we call one of their people to come and look the material over. We process all their home scrap, including slabs and coils. But we dont handle the reclaiming pit scrap thats processed by someone else."

It makes sense for mills to contract out their scrap handling to scrap processors, who have the needed expertise, says Schnackel. "We handle scrap better. We have a lab where we analyze the materials, and we handle the inventorying, accounting, and rail traffic. It takes all that headache away from them." Luntz goes so far as to guarantee that the mixture in the bucket will yield the grade of scrap required. "The idea of scrap management helping mills best use scrap is catching on," says Schnackel.

Exclusive or preferred supplier relationships make sense from a mill point of view, he says. If mills only buy from two or three companies that are very familiar with their specifications, they can get the level of quality they need much more easily. But these sorts of relationships can be a double-edged sword for processors. "For us, some of these close relationships have been great, and some have turned sour," says Schnackel. "As brokers, we are traded like ball players. It depends on how valuable we are and what we can offer."

But close relationships with mills can benefit scrap processors, as well, says Jim Macaluso, vice president of the ferrous division of Sims Bros. Inc., Marion, Ohio. "You know exactly what they want and can give them the quality they need," says Macaluso. "Also, when you know youre shipping a certain number of tons, it makes it easier to buy. This ties up the scrap makes sure you have a home for it and its not going to just sit there."

More mills are asking for regularly scheduled deliveries, he says. "Its a matter of knowing your customers, knowing their schedules," he says. However, that particular area of the country is not conducive to exclusive supplier agreements, says Macaluso. "Nothing is guaranteed when mills slow down, our shipments stop."

In fact, there was a period of about a year when one major mill the company supplies was closed for repair. This had a big impact on its scrap suppliers. "When you are in a relationship and it changes, theres a lot of tonnage you have to find a home for," he says.

Another Midwestern ferrous scrap executive agrees that its impossible for scrap processors to exist successfully without having close relationships with mills. His company has operated as the scrap handling department for a number of mills.

Mills delegate the scrap function for a number of reasons, he says. For one, scrap processors may be non-union or at least operate under different unions than mills. Two, scrap processors have the experience and the equipment such as testing labs and radioactivity detectors to handle scrap. "We put our best people on it, whereas mills tend to put their newest, least experienced people on it. There, it is not considered a prime assignment."

The method of trade between mills and suppliers may vary depending on the market, he says. If there is a market surplus, it makes sense for mills to buy directly from dealers. "But in a market like weve had for the last two years, a tight market, its much better to deal through a third party who can check to make sure youre getting the best price."

Providing service and value, as well as the best price, is key. "The mills need our expertise because the market is complicated by geography and the fact that scrap is not homogenous from region to region," he says. "Some grades may not move up and down with the market. If we can give mills a menu of attractive options to come out with the same product, they can make a lot of money. Our purpose is to help, not to preempt."

Similar trends are taking place in the nonferrous industry. For example, following its move designating Calbag Metals, Portland, Ore., its exclusive scrap supplier, Columbia Aluminum Recycling Corp., also based in Portland, has gone even further in its alliance with the scrap firm, according to Doug Shaw, general manager of CARCO. The two companies have formed a limited partnership which will now operate CARCO.

The first undertaking of the new partnership is the installation of a new reverbatory furnace at CARCO which will begin production before the end of the year. The new furnace will triple CARCOs production capabilities and enable the company to remelt a wider variety of scrap feedstock, from shredded and delacquered UBCs to heavy forgings. This enables the company to smelt the largest array of materials in the Pacific Northwest, according to Warren Rosenfeld, president of Calbag.

The joint venture is a logical next step in the partnership between the two companies, he adds. "This venture is an outgrowth of the tighter quality and delivery control we were able to achieve through our sole source agreement," says Rosenfeld. "This follows our game plan of moving toward production of higher value products for our customers."

CARCOs name under the new agreement will officially become Columbia Aluminum Recycling Co. LLC. The activities of the company will be guided by a board of directors which is made up of the principals from both companies.

It was advantageous for CARCO to negotiate the exclusive supplier arrangement with Calbag in order to guarantee reliability and quality of scrap, according to Shaw. "When we are running with the level we anticipate with our new furnace, we will need a steady stream of scrap," he explains. "Calbag will do the prep work they will shred and clean the scrap. When we get it, well just put it directly into the furnace."

Calbag will deliver scrap on a just-in-time basis, says Shaw. "They will give us a certain number of loads a day to meet our needs, and nothing will be sitting on the ground like it used to," he says. "These kinds of concepts drive this type of agreement."

The two companies are working on developing a grade of scrap that exactly meets the smelters needs. "It is based on Institute of Scrap Recycling Industries specs, but then has proprietary aspects that enable it to meet the needs of our furnace," he says. "Having this very specific grade gives us better recoveries and fewer problems and probably allows us to use more scrap. Metal management is the foundation of the secondary metal industry. If the metal doesnt work, you have to devote labor and time to fixing the problem. Its a matter of economic viability."

CARCO is very concerned about shipping its customers on-spec material, says Shaw. This is made easier by having one supplier that can assure the quality of the scrap coming in rather than having multiple suppliers.

Designating an exclusive scrap supplier and then forming a new company with that supplier may seem like radical steps to take. But in fact, these types of partnership efforts are not new to CARCO, says Shaw. "The whole Columbia philosophy, since the companys founding, has been to seek partners in various aspects of the business to help us do business more efficiently," he explains.

CARCO has not considered buying its own scrap yard, preferring to let each company stick with its area of expertise, says Shaw. "As Warren would say, they dont have melting skills, and we dont have the skills to run a scrap yard," he says.

Others on the nonferrous side agree that partnering with the scrap industry is catching on. "I do see this as a trend as consumers are concerned about getting a steady, consistent supply of materials, and quality needs are higher," says John Beach, trading manager for the David J. Joseph Co.s Frank H. Nott Division, Richmond, Va. "This is not a regional trend; it is more a philosophy on the consumers part their approach to supplying raw materials. Price is just one factor. You have to look at quality, delivery, packaging all those are factored in."

Some mills want fewer suppliers because they can get more consistent supply and more consistent quality, says Beach. "Quality specs are tighter these days since the product the consumer is making has to be of higher quality," he explains. "They have to meet strict ISO 9000 standards they need better quality on the raw material end so that they can produce a better product."

The David J. Joseph Co. works with consumers to find better ways for them to use scrap, identifying which materials are best suited to various uses, he says. "Were trying to achieve an open relationship, understand the challenges, put our heads together, and come up with solutions that are satisfactory for both parties," says Beach. "Its more open than it used to be, although this is on a case-by-case basis."

There is an increasing interdependence between the two industries, he says. "The use of scrap is increasing, so mills have to work with suppliers to get what they need. There are cost advantages to using scrap over prime."

Few nonferrous consumers own their own scrap yards, says Beach. "There is a tendency for mills to move away from the recycling end of it," he says. For example, Golden Aluminum, which used to handle aluminum beverage can recycling for Coors, recently closed its recycling operations.

On the other hand, some nonferrous consumers such as TIMCO, Fontana, Calif., prefer to have many suppliers, according to Jeff Arrow, account executive for TIMCO. Arrow says the company has long-term agreements with certain suppliers, but is unlikely to designate any exclusive supplier relationships.

"We like to do business with a lot of people we need so much scrap, we cant have preferred suppliers," he says. "If someone can put out a good package, thats fine. But we need a high volume of scrap. If we are too picky, we could be put in the position of not finding the scrap we need."

In his experience, suppliers generally prefer not to negotiate fixed long-term agreements, he says. "In a down market, they are very optimistic and dont want to be locked in because they feel it will go back up," he says. "Then in an up market, they are optimistic it will go up even higher."

Another nonferrous consumer that prefers to work with a number of suppliers is Kaiser Aluminum, Heath, Ohio. The company has a core group of about 10 different suppliers it does considerable business with, but it does not discourage others, according to Robert Abel, commodity purchasing agent.

"I would buy from a new supplier as long as they could meet our specs and requirements," he says. "We are limited by geography and the cost of freight. The distribution of scrap generators tends to be centralized. Our producers tend to be in Greater Detroit, in auto applications."

Steel involves much larger tonnages, as well as alloying materials that are more forgiving than those contained in aluminum, says Abel, so it may be more practical for steel mills to establish preferred supplier agreements. He says the best thing a supplier could do to assist his company would be to keep their scrap separate by alloy. "This makes it more valuable," Abel explains.

But exclusive supplier relationships definitely are the future, for nonferrous as well as ferrous scrap, according to another Midwestern ferrous and nonferrous scrap processor. In aluminum, this may increasingly be in the form of a tolling arrangement where processors handle materials for mills that want materials returned.

As the aluminum industry develops, price plays a smaller role, and service plays a larger role, he says. "More and more were seeing consumers that want to deal with a few people they can depend on rather than buying material a little more cheaply."

The first step is to decide what aspect to pursue: collecting demolition debris; collecting construction debris; or processing demolition or construction debris. The split between C&D materials is quite distinct when it comes to the materials handled and the types of equipment required for the job. Within each area, there is opportunity to specialize in certain materials. Conigliaro Industries, Framingham, Mass., for example, has carved a market niche by specializing in polystyrene and vinyl materials in addition to other C&D recyclables.

No matter how you slice it, C&D is big business. But just because you are running an aluminum or paper recycling operation today does not mean you can be successful in C&D. "Theres a 100 percent difference in the materials," says Bob Brickner, senior vice president of GBB, Falls Church, Va. "The cast of characters moving the materials is different; the transportation requirements are totally different; and the competitors are different."

Outside of being in business as an entrepreneur and knowing that it takes hard work to do the job, there is little cross-over. In fact, Brickner indicates that a person with experience in general contracting or construction may be better positioned to start a C&D recycling operation than a recycler. At least that individual would be familiar with the players, the types of material generated, and the market.

"Id recommend that anyone who wants to get started in this business take a rolloff container full of C&D debris and go through it to get a proper understanding of the percentages of each material," says Tom Roberts, vice president of Atlas Environmental, Inc., Plantation, Fla., and president of the Florida C&D Recyclers Coalition.

Then, says Roberts, take each material and draw an itemized flow chart for the handling costs and markets available. Weigh those numbers versus basics like tip fees and market share, and see if you can make a buck. In an area that supports a $12 per cubic yard tip fee, an operation can afford better equipment. If the going fee is $5 a yard, the operation will have to make it up some other way.

Ted Ondrick Construction, Chicopee, Mass., operates portable C&D processing equipment. However, when the company got into the business 17 years ago, doing a job at Westover Air Force Base there were no materials specifications and no guidelines. Most of the companys early work was with private landowners or parking lot contractors. Later, the state became interested in recycling, and then some towns got on the bandwagon. Today, Ondrick is a regional leader in a business based on state specifications, including M11-1. "We were crazy when we got started," says Ondricks Paul Mullen. "But now that it is approved, it was a brilliant idea."

Regional factors play an important role. For example, most successful C&D recyclers are located in areas where tipping fees for disposing of materials are high, says Brickner. While there is no exact figure on the tonnage of C&D material processed each year, he estimates 100 million tons of C&D debris are landfilled or recycled annually.

Tipping fees are the market push, agrees Peter Yost, project manager in the structures and environmental systems division of the National Association of Home Builders Research Center, Upper Marlboro, Md. But demand is the market pull. The association conducted a study comparing Baltimore and Grand Rapids, Mich. Both areas have a $30 a ton tip fee. But in Michigan, the fee for clean, separated wood was $2 per cubic yard; in Maryland it was $4, the same as the $30 per ton tip fee. Why? In Michigan, Yost notes, there was a wood-fired generation plant less than 90 miles away, providing a good, steady demand for wood.

"It is more difficult to separate the plastic, paper, caulking tubes and old lunch containers from construction," says Jonathan Hixon, vice president of ERRCO. That material has to be landfilled. In contrast, demolition is 80 percent wood and the rest of the material is relatively clean.

ERRCO deals mainly with contractors and haulers. The plant is set up to take mixed C&D material, including shingles, wood, sheet rock, windows, all metals and hardware. The firm does not handle rugs, furniture, or other inside materials, but it does take separated loads of shingle, concrete and asphalt or wood at a reduced tipping fee. A typical tip fee for the area would be $65 per ton. ERRCO gets $40 to $60 per ton for mixed demolition material.

Again, although they are lumped together in most discussions, construction debris and demolition debris are quite different in content and should be approached as separate businesses. The materials are often disposed of in the same place, but recovery and marketing of the materials is not the same.

"About 99.99 percent of demolition debris can be recycled without any problem," says Michael Taylor, executive director of the National Association of Demolition Contractors, Doyle-stown, Pa. "But construction debris has mastics (protective coatings), caulks and tars that have greater potential for coming under Resource Conservation and Recovery Act coverage."

Brickner, however, points out that new construction or remodeling debris generally is a known commodity, whereas a firm tearing down old buildings may encounter walls that contain lead paint or asbestos. For this reason, a vital first step for demolition projects includes a walk-through visual inspection to identify items that will require special handling or testing.

Both agree that there are major differences in the makeup of construction and of demolition debris. Demolition material generally is developed from a tear-down operation and the recycler must deal with what is there. Usually a bidder will have a much better idea of what is going to be recycled in new construction. The fractions of materials differ, too. Perhaps 99 percent of the cinder block in a demolition job is recyclable. However, less than one-half percent of the cinder block in new construction is broken or wasted and therefore recycled. Demolition debris requires lots of heavy equipment and large trucks for transportation.

On a demolition site, floor coverings, ceiling material and interior walls must be removed before structural demolition takes place. Yost says wood, drywall and cardboard make up the majority of new residential construction debris. New construction debris goes into a roll-off box and is relatively easy to cart off, and there is a market opportunity there for recycling.

Since new construction debris is generated at discrete times, it is usually source-separated at disposal. Yost says there is a big opportunity for recycling-cleanup services, billed by the square foot of construction. Builders like being able to subcontract the service out and, charging by the foot, have a handle on their costs. Fees range from 30 cents to $1.25, Yost says, depending on the degree of service. NAHB figures show the typical builder pays $511 per house for debris disposal.

Keeping those 30-yard boxes off the job site eliminates another pollution problem for builders, since as much as 25 percent of the material in a new construction site dump box is made up of foreign items such as broken furniture, tires, and other material dumped by outsiders. Yost recommends recyclers set aside a small area with a mesh fence and pick up debris regularly.

One area of opportunity in the C&D recycling market is in concrete recycling. A typical job is taking concrete out of old highways being repaved. Most of the recyclable material gets processed on the spot, going back as crushed aggregate for the new roadbed.

In Southern California, Florida and much of the Southeast, concrete recycling is a big business with a big future. Since the areas are aggregate-poor, they are hot markets for material that can be used as base for paving projects.

Wood is not as easy a market as it would appear. By weight, wood is the largest fraction of debris from new home construction. The material is sometimes processed for sludge drying operations and for particle board. But the product coming in can vary from job to job, and without steady quality and consistency of product, marketing is tough. One firm that went into the wood processing business producing landscaping chips for consumers, found itself stuck with expensive equipment in a losing proposition, since it had no enduring markets.

Roberts says there are three levels of entry to the market. The first is to go with a low-technology C&D materials recovery facility, using a lot of physical labor and hand sorters, and skid-steer loaders to move materials around. The second is a medium-tech operation with some sorting conveyors and screens, perhaps chipping equipment or a wood grinder. A high-tech outfit will have a series of shaker or vibrator screens to clean materials, air rectifiers to pull out papers and plastics, and magnets for metals. An operation handling 1,000 cubic yards a day will need more than $1 million in capital to get started, Roberts says. He also warns newcomers to have ready markets for the materials.

"We dont care what the prices are or will be in the market for our end material, because we dont play the commodities game," he says. "We work backward. First, we determine our handling costs, then the transportation costs, then the processing costs, then we look at what the price is that day for the material. Then we quote a price, and it is only good for one week. We make sure every run is profitable."

Another factor to consider is the size of the yard at your plant. It may sound trivial, but it is actually important to make sure your facility is large enough to handle the volume youll be processing. Taylor also warns that, under some state regulations, a yard handling C&D materials may be considered a transfer station and be subject to additional regulation.

One pearl of wisdom shared by almost every C&D contractor interviewed for this article is that the right guy can make a living in C&D recycling...but not in my city." Actually, that philosophy makes some sense both for the established operator and the newcomer. Some areas like Philadelphia, Cleveland, Chicago and Southern California have entrenched C&D recycling firms with long-term clients. The only way to break into the market would be to cut prices drastically, and most of those operations are working on razor-thin margins already.

Also, Fundamental Action to Conserve Energy, an organization in Fitchburg, Mass., in the course of its C&D Material Infrastructure Development Project, has identified two areas of Massachusetts ripe for C&D handling. Since the data was published, it appears that Springfield will get a transfer station with a 500-ton-per-day capacity. However, nothing yet has happened in Worcester, the other target site. State and federal environmental resource departments; rural development committees; and contractor, recycling and remodeling groups are all good places to hitch up to potential market opportunities.

Waste management costs on a residential job site range from 1 percent to 2 percent of the total cost of a project. Its a sizable enough amount that builders must consider disposal when figuring their building costs, Yost says. Since residential builders are not making a lot of money right now, with profits ranging between 3 percent and 5 percent, they are looking everywhere to save money.

An average new home building project generates about four tons of debris, according to Yost. That includes two tons of wood debris, a ton of drywall, 1,000 pounds of masonry, 600 pounds of cardboard, 150 pounds vinyl and 150 pounds of metals.

Brickner notes that specifications are currently being developed in many areas of C&D debris handling. Those who were recycling in the early days know about the challenges of developing specifications and building a market. Latecomers were, in effect, handed market specifications.

That reflects Mullens point about markets opening up once the groundwork is laid. Ondrick, which can handle 350 to 400 tons per hour, says the secret is to look at a job and see what can be made of the debris and where it can be used beneficially on-site. "Anyone can crush," Mullen says. "The challenge is making something extra perhaps fill for a parking lot out of the material."

There are several bases a newcomer to construction and demolition debris recycling must touch before getting started in business, according to Tom Roberts, vice president of Atlas Environmental Inc., Plantation, Fla.

Know your local tip fees. If the gate rate is $4 a yard in your area, a C&D debris recycling operation will be marginal. If there is a C&D landfill 100 miles away charging $2 a yard, it will pay to take a 60- or 80-yard truck to the other location. If a Class I landfill is charging $50 a ton, you will not be able to charge much more than $25, depending on location.

Next, know what your cost will be to capitalize a C&D debris recycling operation. Roberts puts the cost of a good 1,000-cubic-yard-per-day operation at about $1 million. Add in fuel, maintenance, transportation and costs to dispose of residues.

Ever since the introduction of radial and synthetic compounds, tire recycling has been a tough business. Todays modern tire is highly engineered and built to last 30,000, 50,000 and even 100,000 miles. Reinforced with fiber, steel and in some cases aramid and silica, the tire poses a unique challenge to recyclers who must separate the different fractions in order to get decent prices for the steel and rubber.

But even with all the hard work and effort that goes into this process, in many cases tire recyclers are finding that the prices they are currently getting for tire crumb are not very high. With a glut of crumb currently on the market, market observers say there could be a shakeout of recycled tire crumb producers on the horizon.

"Currently, pricing for crumb rubber is down," says Tiffany Hughes, vice president of marketing for American Tire Recyclers, Jacksonville, Fla. "Production is uneven with demand." Other crumb rubber makers echo Hughes statement. Recyclers who were once getting 50 to 60 cents a pound are now only getting about 40 to 50 cents a pound. And lower grades of crumb are fetching as low as 10 cents a pound, or even less.

Adding to the depression of the tire crumb market is the availability of tire buffings from retreading operations. The popularity of truck tire retreading has pushed about 182 million pounds of tire buffings into the crumb rubber stream. These come from the 30 to 33 million retreads generated annually in the United States. Since buffings are high quality, rubber-only scrap, they are more easily processed and in higher demand.

Buffings currently make up about 70 percent of the annual 260-million-pound crumb rubber stream. The remainder about 78 million pounds of crumb rubber comes mainly from whole-tire grinding operations that consume approximately 4 to 6 million scrap tires a year. Currently, there are 122 companies in the U.S. and 14 in Canada that produce tire crumb. Of these companies, 8 to 10 are producing about 80 percent of the crumb rubber in the market. "The rest are simply fighting for market share," says Michael Blumenthal, executive director of the Scrap Tire Management Council, Washington.

"The market is looking at a downswing," continues Blumenthal. He says that tire crumb companies are looking to sell equipment to downsize or get out of the market altogether. "It looks like there is going to be a shakeout in this market segment in the near-term future," he adds.

Part of the reason for the shakeout is that many of the firms ramped up operations based on the Intermodal Surface Transportation Efficiency Act of 1992 that mandated a certain percentage of crumb rubber in federally-funded roads beginning in 1995. The legislation was never enacted and is essentially dead. Even though the mandate is gone, a large portion of the recycled crumb market is still dependent on paving applications with about 40 percent, or 112 million pounds, of crumb being diverted to this segment annually. But it seems that there are not enough paving applications to go around. Companies that invested in crumbing operations for the sole purpose of supplying the asphalt paving industry are having to look elsewhere to sell their product.

While several companies are marketing crumb rubber additives to soil, the American Society for Testing Materials, West Conshohocken, Pa., is planning to hold a special symposium on the topic titled Testing Soil Mixed With Waste Or Recycled Materials. The symposium will be held Jan. 16 and 17 at the Hyatt Regency, New Orleans. At the symposium 27 papers will be presented covering the use of crumb rubber, ash, plastics, and paper-by-products as soil additives. For more information, call Mark Wasemiller at (509) 372-9702, Bob Morgan at (610) 832-9732 or Keith Hoddinott at (410) 671-2953.

While there seems to be an over-supply of crumb currently on the market, some in the industry say the glut is mainly with lower quality material. "I agree that there is a crumb rubber glut," says Mike Rouse, president of Rouse Rubber, Vicksburg, Miss., "but the glut is in sub-standard crumb, not high quality crumb." Rouse says the market is currently saturated with one-quarter-inch to the 35 mesh (about 0.02 inches) crumb. His company, on the other hand, produces a finer crumb in the 40 to 200 mesh range (0.0164 to 0.0029 inches).

"Every segment within the market has its own standards for crumb, and you cant just throw every tire together and grind them up," he says. "For one, each type of tire has its own unique compounding; and two, an application may require a finer particle size."

The crumb rubber market is certainly differentiated by product quality and size, adds John Serumgard, chairman of the Scrap Tire Management Council. "We are seeing high demand for top quality crumb in several areas, especially the Southwest," he says.

Rouse recommends that companies in the crumbing business maintain strict quality standards by having a dedicated material analysis lab that monitors crumb parameters. "Even for low-level products such as mats, you still need a certain level of quality," he adds. "I dont worry about volume, I only worry about quality."

This emphasis on quality can lead to a higher price for the material, according to Rouse, who says he is getting a decent price for his tire crumb because he can back it up with analytical data and assure the buyer about the material he delivers.

There are markets out there, but you have to have access to them, according to Blumenthal. Some emerging markets for tire crumb include soil amendments and top dressings where crumb is mixed with soil and other ingredients to provide a better growing environment for grass. Currently, there are two patented soil amendment products on the market that use crumb rubber. The first is Rebound, marketed by American Tire Recyclers, and the second is Crown III, marketed by Jai Tire Industries, Denver. Both are use-type patents that were awarded to the inventor of Rebound and to the University of Michigan for Crown III.

Because of the patents, a company cannot sell a similar product to golf courses or athletic fields. "A lot of research was done by the University of Michigan to make sure that the product was safe to use and viable," says Cornelia Snyder, president of Jai Tire, "and that is why the patent was issued. Anyone can add crumb rubber to soil, but if an organization buys crumb rubber from a producer without the patent, then legal action can be levied against both parties."

Rebound has been on the market for several years, and is used mainly in high traffic areas, such as athletic fields and parks. The crumb acts as an aerator and promotes drainage of water, as well as preventing the soil from compacting. Unlike Crown III which is layered on top of the soil, Rebound is mixed into the soil.

Other markets include molded products such as mats, tiles, parking lot stops, railroad crossing pads, dock bumpers, carpet underlayment, other walkway type pads, and many other products that can be made out of rubber. Crumb can also be combined with another polymer for auto applications, such as truck liners, step pads and brake pads. Related to the asphalt paving industry are uses for athletic tracks and as an underlayment for artificial grass playing fields.

Snyder has these three recommendations for those seeking to start in the recycled rubber market today. First, establish your markets, she says. Many in the industry recommend that a recycler has at least three markets secured before starting to produce crumb.

Second, try marketing someone elses crumb, instead of making a huge investment in equipment. With the glut of crumb rubber on the market, it should be easy to hook up with a supplier and get a feel for the market. Hughes supports that statement, and says the industry needs more brokers. "I know that I havent knocked on all the doors yet," she says, "and our company has a full-time marketing staff. Other companies put so much effort into the manufacturing end that they dont have the time or money to adequately support their marketing efforts. We simply need more marketing people in this industry, because there are markets out there."

Its necessary to research the market carefully and exhaustively, adds Dave Emmerit, owner of Recycled Rubber Technologies, Somerset, Pa. "Find the market, then find the equip-ment to match that market," he says.

Emmerits company makes 18 different products that range from rubber bullet stops for police training to driveway patching material. His company can also colorize rubber pavement to match color schemes around pools and patios.

Another service that RRT performs is packing heavy-duty tires with a crumb rubber filler for use in harsh environments such as scrap yards, so the tires do not go flat. "We can do it for one-third the cost of buying a new tire," says Emmerit.

Other advances for the use of crumb include the use of recycled material in new tires. Michelin and other major tire companies are currently working on ways to incorporate more recycled crumb into new tires to reduce costs and meet recycled-content goals by the automakers. Currently less than 1 percent of recycled crumb is used in the construction of a tire. Michelin is now testing tires with more than 10 percent of recycled crumb by rubber weight. With about 13 pounds of rubber in a 20-pound passenger tire, Michelin is putting more than 1 pound of recycled crumb into its test tires. The tires are being tested by taxi cab fleets in two cities.

"We are very pleased with the testing to date," says Douglas Bell, director of corporate administration for Michelin North America, Greenville, S.C., and the companys environmental manager. "We are looking to fit the tires on 1999-model-year cars at the earliest."

Bell says there are currently no long-term contracts with crumb suppliers, but any future supplier of crumb will have to meet Michelins quality standards and be approved just like any other supplier the company uses.

Another unique product comes from Aquapore Moisture Systems Inc., Phoenix. Fifteen years ago the company developed a soaker hose for watering residential plants and grass. The company will not say how much recycled crumb goes into the making of each foot of hose, but will say that it consumes about 3 million pounds of crumb rubber per year to produce the hose and 300 other products from recycled rubber, including landscape edging and false mulch. The company makes about 200 million feet of soaker hose a year.

Since the hoses are of high quality and have to withstand a certain water pressure, Tim Mannchen, vice president of marketing for Aquapore, says that the company is actually having a difficult time finding the quality crumb that it needs. "Currently, we are using four sources for recycled crumb," he says. "But we need more high-quality suppliers to handle our growth."

One of the suppliers is National Rubber Baker Materials Inc., Toronto, which operates a crumbing plant in Phoenix, and is considered to be the largest producer of crumb rubber in North America. But in fact, a lot of the crumb used in the Aquapore products come from retread buffings because of the quality required.

Mannchen has some advice for recyclers looking to market products from recycled crumb rubber. "You have to stand by your product," he says. The companys soaker hose, for instance, comes with a seven-year warranty, and the company will replace it for free if there are any defects.

"Next, try to get a premium price," he adds. "Prove to the consumer that your product demands a higher price." The company took the landscape edging market from 13 cents a foot to 28 cents a foot by making the product more resilient and flexible with crumb rubber.

"And finally, look for alternative merchandising venues," says Mannchen. "Try listing your product in a catalog, for example. There are more than 2,000 catalogs in the U.S. that are targeted toward a wide range of industries and markets. It is not as complicated as trying to get your product on a store shelf."

The Chicago Board of Trade has recently overhauled its year-old Recyclables Exchange where buyers and sellers can trade various recycled commodities. The new Internet-based system has expanded listings for rubber grades and now includes shredded tires, whole tires, crumbed rubber and tire-derived fuel.

The subscription rate for the Recyclables Exchange is a one-time registration fee of $10. Companies can place a sell order for only $2 a month, with volume discounts available. Buyers can list their purchasing parameters for free, but listing matches cost 50 cents each. Matches between buyers and sellers are delivered immediately to the buyer via e-mail, and the system constantly searches for matches based on the specification parameters set by both buyers and sellers.

With the virgin rubber price hovering just above $1 a pound, it would seem that recycled crumb rubber would be a good buy and in high demand. But recycled crumb is vulcanized, and, as a thermoset material, it wont chemically bind without some kind of adhesive or another polymer. However, several companies claim to have special processes that break the tough sulfur bonds that are created during the vulcanizing process, or at least make the rubber more adhesive for molding. These processes called "surface treatments" include ultrasonic devulcanization, reactive gas surface modification, catalytic regeneration, chemical modification and microbes that reportedly attack the sulfur bonds on the surface of the rubber.

While all of these surface treatments promise to make recycled rubber more "virgin-like" or more adhesive in the molding process, most of the treatments have only been on the market for the last year or so, and the verdict is still out on their effectiveness.

Special binders also can help in the molding process. Uniroyal Chemical, Elmira, Ontario, has a urethane binder that allows the recycled crumb to adhere better in the molding process, according to the company. The binder is sold under the trademark name Royalbond. There are several other types of binders on the market as well.

With the constant flow of about 250 million scrap tires entering the U.S. market annually, there will always be ample supply. On the demand side, existing markets will have to be expanded and new ones created. Some point to a growing export market that could fill the void. Others say that many manufacturers are now starting to conduct research and development on recycled crumb.

Despite past events that have rattled the rubber recycling industry, Hughes believes that the market is slowly becoming more focused. "Producers and suppliers are sharing more information through associations and industry meetings," she says. "And thats good but more needs to be done."

Created in 1948, the Bureau of International Recycling, Brussels, is the international federation of industries involved in the recovery and recycling of iron and steel, nonferrous metals, paper stock, textiles and plastics. More than 50 countries are represented.

For some time, BIR members and the recycling industry as a whole have had to tackle an increasing number of environmental challenges, mainly as a result of the confusion between the waste management sector and our profession. The Basel Convention on the Transboundary Movement of Hazardous Waste, especially, has been the focus of a lot of attention.

Due to the erroneous belief that many of the materials we trade are mere "wastes", the decision to ban the export of "hazardous waste" from a series of developed countries those belonging to the Organization of Economic Cooperation and Development and others to non-OECD countries, as of December 31,1997, has placed recyclers in an uncomfortable position. The question of what is or is not hazardous is up to the conventions Technical Working Group.

At that meeting, the TWG confirmed the decision, made at a previous meeting, to exclude a long list of secondary metals from the export ban. It added to this list lead, cadmium and beryllium. But unsorted batteries and batteries containing lead, cadmium or mercury were among recyclables confirmed as subject to the ban. The Group also transferred to the "B" list of materials not subject to the ban if they are uncontaminated some substances previously slated for further study.

However, it was unable to come to a conclusion on the classification of PVC-insulated cables and materials containing copper or zinc compounds, including zinc ash. Further technical information will have to be presented by the industry at the next TWG meeting scheduled for February. In Manchester, BIR consultant John Donaldson submitted scientific data as technical evidence that the majority of materials under consideration were not hazardous.

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