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galena vibrating feeder

vibrating feeder

vibrating feeder

Vibratory feeders are used in gravimetric feeding systems to handle solids with particles that are loo large to be handled by screw, rotary-vane, or vertical-gate feeders, or in operations where the physical characteristics of the solid particles would be adversely affected by passage through these volumetric feeding devices. The discharge flow pattern of a vibrating feeder is extremely smooth and thus is ideal for continuous weighing in solids flow metering applications.

The vibratory feeder consists of a feed chute (which may be an open pan or closed tube) that is moved back and forth by the oscillating armature of an electromagnetic driver. The flow rate of the solids can be controlled by adjusting the current input into the electromagnetic driver of the feeder.

The vibratory feed chute can be jacketed for heating or cooling, and the tubular chutes can be made dust-tight by flexible connections at both ends. The vibratory feeders can resist flooding (liquid-like flow) and are available for capacity ranges from ounces to tons per hour.

The Electric Vibratory Feeder is a vibratorthat provides an extremely efficient, simple and economical solution to the problem of making the most stubborn material flow freely. No longer need there be a sticking together of wet ore in the ore bin, or the arching over and hanging up of materials in hoppers and chutes with resulting lowered operating efficiency.

The powerful vibration of the simple, electro-magnetic vibrator is controlled by a separate, wall-mounted Controller, which is furnished with each vibrator. The dial rheostat in the controller varies the power of vibration. By merely turning the manual dial rheostat the power of vibration can be turned down to provide the most effective vibration required for the purpose. The controller is in a separate, dust-proof housing, arranged for wall-mounting at any desirable distance away from the vibrating mechanism attached to the bin, hopper, or chute.

These vibrators are furnished in many different sizes. Units are available that range from those equipped to handle large tonnages in ore bins down to the small noiseless model best suited to be attached to a dry reagent feeder. Reagent feeder applications are numerous, but a well-known use is where the vibrator is utilized to keep moist lime or soda-ash stirred up and flowing evenly.

In an ore bin with a flat bottom and a center discharge, the material, especially when wet, will build up in the corners and form a dead storage space just inside the walls of the bin. One or two vibrators mounted on the outside of the ore bin (opposite to each other, when two are used), will eliminate the work that otherwise frequently has to be done by hand with a pick and shovel. Another, and possibly more important aspect, is that maximum treatment efficiency is assured by an even feed to crushers or ball mills.

These vibrators are also available at extra cost with totally-enclosed explosion-proof, or water and dust-proof cases. Also, for special jobs where danger of explosion or fire exists, a water or air-pressure vibrator can be furnished. A major advantage of these hydraulic vibrators over electricvibrators is that they can be made to run at a slow speed as well as at a high speed (2400 to 4800 vibrations per minute).

The flow velocity depends on the method for loading the feederis it fed through a hopper? The velocity is also dependent on the material characteristics, size distribution and moisture content, as well as the slope of the feeder. The only way to determine the value for v is by actual observation and then the feeding rate may vary considerably.

Feeders are used to provide and control the flow of bulk solids to the process from storage units, such as bins, bunkers, silos, and hoppers. In to-days fully instrumented process plants, it is mandatory that feeders maintain a uniform flow of material at the rate set by signals from process equipment farther downstream in the flow. Large variations in feed, due to feeder blocking, arching or ratholing in the bin, may completely defeat the purpose of such a sophisticated control system with all its planned advantages to the process.

Most of the bins used in the mining and metallurgical industry to-day are of the plug flow type, as they are suited for the storage of hard, abrasive or coarse materials. Exceptions are the ore concentrate or fine powder bins which usually are of the mass flow type.

Plug flow occurs in bins or hoppers with flat sloping walls and is characterized by the flow of solids in a vertical channel extending upward from the bin outlet. Plug-flow bins are suited for solids which are free flowing, do not deteriorate with time and in which segregation is of no importance. As flow does not occur at the bin walls, this type of bin is useful for the storage of hard and abrasive materials. The drawbacks of this type of flow, however, are as follows:-

a) The live bin capacity of the bin is drastically reduced. b) The bin is not self-cleaning and usually cannot be emptied by gravity flow. c) Materials which deteriorate with time cannot be stored in this type of bin. d) The flow is erratic and non-uniform, as solids flowing through a vertical channel with a constant cross section tend to form arches which collapse and compact the material below, thus causing arching again. e) This type of flow pattern in the bin aggravates the segregation of particle sizes.

In many instances, hopper openings are large enough to prevent arching: however if the hopper is not designed for mass flow, piping or ratholing may occur. In plug flow bins, the material flows in the centre of the bin, into which the sides slough as the material is drawn from the bin. Reaching a certain level in the bin where the material has time to consolidate, sloughing will cease and a steady channel or rathole (limited flow) will form, drastically reducing the bins live capacity. In mass flow bins, channelling can also occur if the feeder does not draw the material uniformly across the whole area of the feed opening.

To overcome flow problems, flow-promoting devices such as external vibrators, pneumatic air panels, air jets and vibrating internal structures are usually installed. These relatively inexpensive devices can solve the problem in marginal cases. However, where the costly complete re-design of bins or hoppers is indicated by bulk solids flow calculations, other apparently less costly ways for improvement are usually sought.

The extension of the mine workings under adjacent lakes for the reach of the recently found copper ore body, and the introduction of sand fill underground in the past years using the mill tailings, led to build-up of the moisture content of the fine ore. In the meantime, the 50% increase of daily mill output from the original 2000 to 3000 tons necessitated finer fourth stage crushing and the addition of an extra grinding mill. The fine ore actual handled to-day is a roll-crusher product of -5/32 in size with a moisture content of 2% to 3%.

The fine ore bin, as originally conceived with its wear angles on the sloped walls, is of the plug-flow type. It performed satisfactorily in the earlier stages of operation of the plant when the material handled was coarser and lower in moisture content. With increasing ore moisture and material fineness, however, the live capacity of the fine ore bin was gradually reduced to a point where, in some instances, only channelling or ratholing occurred over the feed openings.

After visiting installations using long belt feeders, consideration was given to the use of the existing gathering conveyors as belt feeders. This scheme involved the cutting of long slots into the bin bottom above the entire length of the existing belts.

The flow pattern in a flat bottom bin with single or multiple openings is usually of the plug-flow type. The drawbacks of this type of flow have been explained previously. It was felt, however, by the author that improvements could be made by the appropriate location of feed openings and by the use of suitable feeders. The basic idea for this improvement was initiated by the review of the results of model tests performed on flat bottom bins, which indicate a mass flow type of pattern at the beginning of the bin discharge. This pattern switches gradually to plug flow as the material level drops below a certain point. This partial mass flow situation can prevail only if the material handled is reasonably free-flowing, the feed openings are sufficiently closely spaced, and the material is drawn uniformly from each opening.

The example illustrated is taken from an iron ore concentrator, and shows the arrangement in which the mill feed conveyor is receiving material from the gathering belt located underneath the two silos. The fine ore handled is taconite, -5/8 in size, and a tertiary cone crusher product with 1 to 2% moisture.

When drawn empty, the dead material left in the bin generally takes the form of a wedge-shaped hopper. However, the slope of the material should not be mistaken for the angle of repose , as it is really the included half angle e of the flow channel, which is usually much steeper due to material consolidation. Approximate expected values of e can be calculated knowing the flow properties of the material handled.

eriez - vibratory feeders and conveyors

eriez - vibratory feeders and conveyors

With their totally enclosed patented magnetic drive, Light and Medium Duty Feeders are perfect for feeding practically any bulk materialfrom micron size to bulk chunks. They feature solid state controls, which operate the state-of-the-art feeders with watch like precision. Custom designs are available and may include multiple drives, enclosed trays or screens. Additionally, a wide variety of standard and special trays are available.

With their totally enclosed patented magnetic drive, Light and Medium Duty Feeders are perfect for feeding practically any bulk materialfrom micron size to bulk chunks. They feature solid state controls, which operate the state-of-the-art feeders with watch like precision. Custom designs are available and may include multiple drives, enclosed trays or screens. Additionally, a wide variety of standard and special trays are available.

Our Heavy Duty Electromagnetic Vibratory Feeders are ideal for handling coal, ore, aggregates, slagor any other situation where high volume, controlled feeding is required. With their energy-saving intermeshed AC/permanent magnet drive, these powerful units are the workhorses in Eriez' huge stable of Vibratory Feeders and Conveyors. They are available in nine models with capacities to 850 tons (765 MT) per hour*. (*Capacity is based on sand weighing 100 pounds per cubic ft. (1.6 metric tons per cubic meter)

Our Heavy Duty Electromagnetic Vibratory Feeders are ideal for handling coal, ore, aggregates, slagor any other situation where high volume, controlled feeding is required. With their energy-saving intermeshed AC/permanent magnet drive, these powerful units are the workhorses in Eriez' huge stable of Vibratory Feeders and Conveyors. They are available in nine models with capacities to 850 tons (765 MT) per hour*. (*Capacity is based on sand weighing 100 pounds per cubic ft. (1.6 metric tons per cubic meter)

Simple and rugged Mechanical Conveyors from Eriez provide controlled movement of large volumes of bulk materials. They are available in single and two-mass vibrating systems which are excited by a motor-driven eccentric shaft. These vibrating machines feature a compact, straight line design that presents a low profile, yet enables easy maintenance. Minimum headroom is required.

Simple and rugged Mechanical Conveyors from Eriez provide controlled movement of large volumes of bulk materials. They are available in single and two-mass vibrating systems which are excited by a motor-driven eccentric shaft. These vibrating machines feature a compact, straight line design that presents a low profile, yet enables easy maintenance. Minimum headroom is required.

High capacity Vibratory Screeners are designed for liquid/solid separation and wet or dry classification. These easy-to-operate gyratory units allow trouble-free and quick tuning to specific feed rates, product and separation requirements. Benefits are many, including long screen life and no damping under loads. Inline screeners are also available.

High capacity Vibratory Screeners are designed for liquid/solid separation and wet or dry classification. These easy-to-operate gyratory units allow trouble-free and quick tuning to specific feed rates, product and separation requirements. Benefits are many, including long screen life and no damping under loads. Inline screeners are also available.

Eriez Bin Vibrators are used in applications ranging from the tiniest hopper to huge bunkers, providing efficient and economical movement of hard-to-handle bulk materials. Electric Rotary Vibrators (ERVs) serve as a powerful, reliable and effective flow-aid for hoppers and chutes, or a driving force for vibratory screeners, feeders and conveyors.

Eriez Bin Vibrators are used in applications ranging from the tiniest hopper to huge bunkers, providing efficient and economical movement of hard-to-handle bulk materials. Electric Rotary Vibrators (ERVs) serve as a powerful, reliable and effective flow-aid for hoppers and chutes, or a driving force for vibratory screeners, feeders and conveyors.

electrostatic separator

electrostatic separator

Electrostatic separation depends on a number of electrical and mechanical properties such as conductance, contact potential, dielectric constant, end particle shape. In routine testing it is desirable that the application of each of these properties be investigated. The conductance property is best utilized in a separator having an ionic field, whereas the contact potential requires a separator with a pure static field. Dielectric constant and particle shape also influence the response in these two fields. There is no separator on the market that can be adjusted for all these requirements. The separator described in this paper is satisfactory for this purpose and is provided with a dielectric electrode, which permits formation of high-intensity static fields.

Separation of minerals utilizing differences in their electrical properties may be carried out using an electrostatic separator. It will separate electrical conductors (minerals such as cassiterite and rutile) from those that are electrical non-conductors (minerals such as zircon and siderite). The principle of separation is that as the particles to be treated are passed through an intense electric field each particle acquires a charge. The conductors pass on their charge when emerging from the field while the non-conductors retain theirs momentarily.Separation is effected by passing the particles on to a rotating metal cylinder (the roll); without any external forces all the particles will follow a ballistics trajectory when leaving the roll surface.

In the presence of an electric field, the rotor becomes negatively charged, while the particles are positively charged. The non-conducting particles retain these charges and are attracted (pinned) to the roll while the conducting particles lose their charges (to the roll) and follow the normal projectory as shown in figure 9b. Separation is affected by (adjustable) splitter plates.

In practice electrostatic separators will always be tested in several stages, as one pass separations producing clean products are rare. Inherent physical properties of mineral particles (specific gravity, grain size and composites, surface coating) and their interrelationships all affect the ease of separation. In addition the number of operating variables (temperature, voltage, rotor speed and electrode configuration) make a number of trials necessary to determine optimum conditions for separation.

The essential parts of the separator are the carrier roll A, functioning as grounded electrode, the dielectric electrode, B, and the corona electrode, F shown in figure 1. A field of ions is generated by corona electrode F. This field of ions charges both the particles on the carrier roll A and the surface of the dielectric electrode B. As B rotates continuously, the region between the carrier roll and the dielectric electrode is an electric field that is as near static conditions and free from ions as it is possible to obtain. The region between the carrier roll and the corona electrode is an ionic field that may be changed from high intensity to zero intensity by rotating F about B to a position farthest from A.

The dielectric electrode has the advantage over the metallic or conductive type of electrode in that there are no spark discharges that interrupt the separation. It permits the establishment of high electric-field intensities and does not cause back deflection of conductive particles that may strike it.

Electrode B is a 3-inch-diameter pyrex-glass tube supported by bakelite end disks, V. By coating the midportion of the inside of the tube with an electrically grounded layer of Acheson aquadag graphite, the glass functions as the dielectric of a condenser. An alternative form of the dielectric electrode consists of a 3-inch -diameter methyl methacrylate plastic tube (0.13 inch wall thickness) placed as a close fit over a precision metal tube.

Roll A is a grounded, 6-inch diameter, precision metal tube supported by steel end disks. Shaft support K, detailed in figure 2, has a porous bronze bushing, a, leveling screws, d, and machined faces, b, for parts L and S. Hole f in part L is a sliding fit for the shank of part 0, a shaft support of special design (Boston Gear Works SAP 102).

A cap screw in clearance hole e fastens L rigid to K except for adjustment. This adjustment permits a variation in the angle between the horizontal and the line through the electrode and she.ft centers. The electrode-roll gap distance is adjusted by sliding the shank of part 0 in hole f of part L. Fixed positions are maintained with a set screw.

Ring P supports the corona emitting electrode F and its insulators Y. Adjustments with respect to the corona charging of the particles are made by rotating ring P on a steel cylinder, which is drive-fitted on the bearing housing of shaft support 0. Positions of ring P are fixed by a set screw. Either a 0.003- to 0.01-inch-diameter wire stretched parallel to the shaft center line or a row of needle points nay be used for the corona electrode. Corona wires generate fewer convective air currents then corona-needles.

A 40 kilovolt D. C. supply is satisfactory for most purposes. At higher voltages, up to 100 kilovolts, the electric supply feeder is brought in from above instead of from below, as shown in the illustration. A 60-watt, 10-megohm, 100-kilovolt resistor is connected in series with the corona electrode.

The carrier rolland dielectric electrode are driven by means of 3/8-inch V belts and cast iron variable-pitch sheaves (Browning Manufacturing Co. IVP 30). The special form of these sheaves is essential for belt tightening. J consists of two sheaves fastened on a bronze sleeve, which idles on the shaft of roll A. One sheave receives the cross belt from the main drive shaft. The other receives the belt from N, which then rotates in a direction opposite to that of roll A, and at twice the speed. An ideal speed for A in frictional electrical and conductance separations with convective charging is 150 r,p.m.

Each tray, H, hopper, W, and vibrating spout, E, is heated with 250-watt heaters such as T. A and B have, respectively, 250- and 15-watt internal heaters connected through slip rings, E. When B is constructed of methyl methacrylate plastic, a heater for this electrode is not needed. This method of heating is in contrast to continuous commercial operation where the hot feed heats the separator.

Roll A is cleaned by the wiper underneath it. However, strongly adhering corona-charged particles frequently continue past the wiper. Operation was improved by placing either a metal nonionizing electrode of polarity opposite the dielectric electrode or an ionizing electrode excited by alternating current adjacent to the wiper, so that the particles on the roll passed through the field or ions of these electrodes loosen before reaching the wiper.

part K, the wires are stretched across the roll face parallel to the roll-shaft center line so that they just touch the roll surface and are also at earth potential. The wires remain stationary as the roll rotates, and the effect is to agitate the adhering corona-charged particles. The wires are useful in improving the conductance separation of some mixtures such as rutile-zircon, but for most other conductance separations the improvement is negligible. They are not used in frictional electrical separations. Their function is to diminish entrainment of particles that would not normally adhere to the carrier electrode.

Efficient separations of the good and poor conductors in crushed ores, sands, and industrial products are obtained by adapting the principle of convective charging. In this method the corona electrode, F, is rotated toward the carrier roll, so that the particles on the carrier roll receive a corona charge. The exact position of the corona electrode is determined by the separation that results at the dividing edge, G. In addition to the corona electrode, the position of the dividing edge G, the angular setting of L, and the eloctrode-roll gap distance are varied. Combinations of poor and good conductors can be separated, which will not respond to the pure static field type of separator. An example of this is ilmenito from staurolite in certain Gulf-coast heavy sands.

Crushed ores can be carried through a special procedure of stage crushing and separation, so that the conductors are separated as they are unlocked by crushing without an unnecessary reduction in the size of the conductors. A study and application of this method will be described in a separate paper. Efficient separations are obtained with hematite, ilmenite, and chromite ores.

With convective charging, the separator will collect the blocky materials of intermaediate conductivity with the conductors, and the flat particles and slivers with the nonconductors, which is just opposite to the action of the pure- static field typo of separator.

When the corona electrode is rotated far from the carrier roll so that it is at its greatest distance from the roll, very few ions reach the particles on the roll, and the separator functions as a nonionic or pure static field type. Further decrease in stray ions is obtained by replacing tho corona wire with needles oriented to point directly at the dielectric electrode. With this adjustment, separations based on frictional electrical charging of particles may be obtained. Examples are the separation of sillimanite from quartz- and talc from tremolite.

With some minerals, sufficient frictional electrical charging results from simple pouring. Others require passage over a vibrating surface, such as that of feeder E in figure 1. The surface of feeder E is a horizontal plate whose vibration displacements are in a general vertical direction. A further description may be found in reference.

An alternative form of frictional electrifier, in which more intense vibrations may be obtained, was constructed of vertical plates. These plates, 1.6 inches high and 0.9 inch wide, are separated with spacing strips 1.6 inches high and 0.2 inch wide, placed along the long edges of the plates. With the length direction of the plates in a vertical position and the thickness of the plates and strips, 0.05 inch, the whole assembly of plates and spacing strips results in a series of cavities 0.5 inch long, 0.05 inch wide, and 1.6 inches high, with open tops raid bottoms. The plates and spacing strips are damped together by menus of two horizontal tension bars placed on each side of the assembly.

When a mineral mixture is poured through the cavities and the assembly is vibrated horizontally, which is perpendicular to the surface of the vertical plates, frictional electrification results. This electrifier, a substitute for E, is placed so that the direction of vibration and the perpendicular to the plate surfaces are parallel to the dielectric electrode shaft center line.

Biotite is separated from talc with an efficiency that is higher than with the conductance method using convective charging. With convective charging only the blocky particles of biotite are removed. This is in contrast to the pure static field separator, which removes both the blocky and thin flakes. In addition to flat particles, particles with a low conductivity and a high dielectric constant would be expected to separate more efficiently as apparent conductors in the simple static field type of separator.

Beach sands and some crushed ores receive primary wet concentration and size classification. Since the feed is thus initially wet and must be dried for electrostatic concentration, conditioning with several pounds of sulfuric acid hydrofluoric acids per ton of solid can be accomplished before drying, without much additional cost. Mineral mixtures may be conditioned in the dry state also. Dry conditioning with hydrofluoric acid vapor improves the separation of talc from tremolite. Conditioning with the same reagent in the aqueous and dry states does not always yield the same result. For example, beryl may be separated from quartz and feldspar after aqueous conditioning with hydrofluoric acid but not after dry conditioning with this reagent.

An initially wet feed is also amenable to cleaning. Attrition scrubbing is effective on wet beach sands. In one example a zircon-rutile sand that was heavily iron-stained resisted cleaning by both attrition scrubbing and chemical action with aqueous sulfur dioxide. However, by adding a small amount of metallic iron powder to the aqueous sulfur dioxide pulp, the iron-stain coating dissolved in 50 to 60 minutes. Metallic iron is a substitute for metallic zinc, cautionly used in SO bleaching of iron-stained minerals. Cleaning of particles or coating selectively with reagents promises to make electrostatic separation as versatile as flotation.

The objective of this research was separation of one highly conductive mineral from a second conductive mineral, a procedure which is impractical in commercial electrostatic separators using metal rolls. Such separators permit separation of nonconductive from conductive minerals. A new technique involved use of carrier electrode rolls specially prepared by anodizing and/or oxidizing at high temperatures to form suitable oxide surfaces. Specific oxides included aluminum, copper, and nickel. The significant result provided by the new surfaces was the extension of the separation range to higher conductivities, an extension in relative mineral conductivity from 10 -14 to 10 -11 mhos. The results are in accordance with the blocking-layer theory.

Some ores are best concentrated by a series of stages which may involve gravity, electrostatic, and magnetic methods. Occasionally a fraction of minerals remains unseparated. It is this unseparated fraction of minerals which is of special interest. A common application of electrostatic separations divides the minerals into nonconductor and conductor. For example, conductive minerals such as ilmenite, pyrite, columbite, magnetite, cassiterite, and hematite are separated from nonconductive minerals such as quartz, zircon, monazite, and rhodolite. A separator consisting of a rotating metal cylinder and an adjacent ionizing electrode is used for these separations. The split between conductive and nonconductive minerals is regulated by adjusting the intensity of ionization. More conductive minerals are deflected into the non-conductor bin as the potential of the ionizing electrode is increased. However, a limit is finally reached where the selectivity between various conductors diminishes. This report is based on the separation of these highly conductive minerals from each other by means of a special type of carrier electrode.

Separations based on the conductivity of particles may be obtained with ionized and static electric fields. The conductivity of the particle determines the amount of charge which passes to the carrier electrode. This flow of charge from the particle to the carrier electrode is shown in figure 1. In 1A the particle receives positive ion charges from the ionizing electrode, I. The particle in positions 1 and 2 is uncharged. In position 3 a positive ion charge is received, and in position 4, part of this charge is conducted to the carrier electrode, R. In 1B both positive and negative charges are induced on the opposite sides of the particle as a result of the static field generated by electrode E. In position 4, part of the positive induced charge is conducted to the carrier electrode, R. The net particle charge in position 5 is of opposite polarity for the ionizing and static field systems, but

In the arrangement in figure 1A the dividing edge, D, is placed closer to R than in figure 1B. This is determined by the trajectory of the separated particles. The main stream tends to be attracted to R with an ionizing electrode, and to E with a static-field electrode, although in both cases there is a separation based on differences in conductivity.

The amount of mineral in fraction C versus intensity of ionization is illustrated in figure 2, where the ionization current to a fine wire electrode is plotted on a logarithmic scale, and the amount collected in fraction C is plotted on a probability scale. Other uses of the probability scale are described in a previous publication. Two sets of data are presented in

figure 2, one with a positive and the other with a negative ionizing electrode. These data show that changing the polarity of the ionizing electrode when treating minerals on metallic-carrier electrodes makes little difference.

Magnetite, galena, and the variety of conductive minerals described here are distinguished as semiconductors which may either be n or p type. The type indicates the polarity of the electric charge carriers, n for negative, and p for positive. When semiconductors are in contact with a metal surface, the conductivity across the contact interface is not the same in either direction. An established rule is that the charge carriers encounter maximum conductivity when flowing from the semiconductor to the metal. Thus with an n-type semiconductor having negative charge carriers, the conductivity would be greatest when the negative current flows from the semiconductor to the metal. With a p-type semiconductor, having positive charge carriers, the conductivity would be greatest when the equivalent of a negative current flows from the metal to the semiconductor.

An experimental verification of this fact was demonstrated by Hartmann with high resistance films of shellac about 10 -4 centimeter thick on the metal surface. For contact phases he used cuprous oxide and zinc oxide as semiconductors and copper for the metal. After addition of the shellac films, a directional conductivity or rectifying action was present at the semiconductor- metal contact. The shellac film has the effect of a barrier or blocking layer.

Barrier films are particularly applicable to electrostatic separations based on differences in conductivity. The roll-type separator, described elsewhere as most frequently used for conductivity separations, has a metal carrier electrode in the form of a rotating cylinder or roll. Soft barrier films such as those of shellac would not be practical for this application, but one of the hardest oxide films, aluminum oxide, is easily produced in film form by anodizing the aluminum metal.

To compare surfaces, only half the length of the carrier electrode was provided with the film surface, the metal surface of the remaining half length was not altered. The film of aluminum oxide on aluminum was formed by anodizing half the length of a cylinder, 5 inches long, 4 inches in outside diameter, and inch in wall thickness in 10 percent sulfuric acid for one hour; washing in dilute ammonia; and drying. The electrolysis was at a constant current ranging from 0.13 to 0.15 amperes per square inch of outer electrolyzed surface. Although the electrolytic vessel was immersed in a cooling water bath, the aluminum cylinder was approximately 50 C when removed from the electrolyte. The anodized film has a smooth satin finish.

Anodization of aluminum may be accomplished with a variety of electrolytes ranging from alkaline to acid. Dilute sulfuric acid electrolytes produce harder films than the more concentrated acid electrolytes.

Oxide films may also be formed in an oxygen atmosphere at elevated temperatures . The green form of nickel oxide, NiO, is a nonconductor and can be substituted for aluminum oxide as an insulating film. The film was formed on a nickel cylinder 4 inches in outside diameter and with a wall 0.109 inches thick by heating in air in a temperature range increasing from 900 to 1000 C in 30 minutes. After cooling, half the length of oxide covering the cylinder was removed by abrading with emery cloth. The nickel oxide film is firmly adherent, unlike most other oxide films, such as iron oxide. Some of the other metal oxides are semiconductors. Use of a nonconductive base will be described as an alternative to forming semiconductors on metal.

In contrast to the metal-semiconductor contacts previously described, a carrier electrode with a semiconductor surface provides combinations of p- and n-type semiconductor contacts. The p-n junctions have rectification proper- ties similar to metal-semiconductor junctions with barrier layers.

The semiconductor may be used in the massive state or as a layer on a sub-base. A semiconductor surface was prepared for these tests on a refractory aluminum oxide cylinder that was 5 inches long, 3- inches in outside diameter, and that had a wall 3/8 inch thick. It was of a variety sold for electric furnace construction. The surface of the cylinder was coated by painting with a water suspension of cuprous oxide, was dried, and then was heated in air to 1100 C for a short time. The coating was applied on the outside surface of the cylinder and around the ends to provide a contact with the ground potential shaft. Copper oxide reacts energetically with aluminum oxide and the time and temperature for heating must be carefully controlled. After cooling, a hard adherent surface of black cupric oxide is obtained. With insufficient heating the copper oxide is powdery, and with too long heating it disintegrates the aluminum oxide surface. The cupric oxide coating is much thicker than the nickel and aluminum oxide films on metal. Other semi- conductors may be adapted in the same way. Some of these may form a compound with a metal base.

Two alternate methods were used for comparing copper oxide with metal, either covering half the copper oxide cylinder with aluminum foil or substituting a fired on coating of ceramic silver paint in place of the oxide on half the cylinder length.

The various cylinders were mounted on a shaft with a special device constructed from parts of cast iron V-belt sheaves of adjustable pitch. Each sheave consists of two parts, one is a threaded shank that mounts on the shaft, and the other fits on a threaded shank. The conical belt surface provides a resting point for the carrier electrode cylinder. To provide a wide gap to accommodate the length of the cylinder, the shaft part of a second sheave is used as in figure 3. Although the second sheave had a smaller outside diameter, the threaded shanks of the two sheaves were the same size.

ionizing wire electrode, I, the vibrating feeder, V, the dividing edge, D, and the shield, B. Elements J and A were not used in the initial tests. They are described in the section on elimination of carrier electrode wear. In all the tests described here the cylinder rotated at constant speed of 100 rpm. The vibrating feeder consisted of two troughs, one for each half of the carrier electrode surface. The ionizing electrode, a wire 0.010 inch in diameter, was maintained at a constant angle and distance from the cylinder, but the current to the ionizing electrode was varied. The current values are for the total length of wire, which was 6 inches.

Results for several minerals are given in figure 2. There is very little change with polarity change for either magnetite or galena on aluminum metal surfaces. This is not true for anodized surfaces, where the curves for each polarity are appreciably different. The greater conductivity for magnetite with a negative wire, and the greater conductivity for galena with a positive wire, suggests that the two are n- and p-type semiconductors respectively.

Similar results are given in figure 5 with mineral particles of zincite and cassiterite on nickel metal and nickel oxide surfaces; and in figure 6 with mineral particles of columbite and ilmenite on aluminum metal and anodized aluminum surfaces. Minerals in all the tests of this report were sized to the range of minus 35- to plus 65-mesh.

Returning again to figure 2 we note the quantity of conductor fraction at various ionizing electrode currents. If these data are applied to actual separations, the ratio of galena to magnetite in figure 2 should be equivalent to the composition of the deflectate (conductor fraction), provided the feed is composed of equal parts of galena and magnetite. Several conductor fraction values taken from figure 2 are presented in table 1 and calculated to ratio values. The ratio of galena to magnetite is much higher with the aluminum oxide surface.

Two tests were run to verify these data, one with an aluminum metal carrier electrode and 200 microamperes current and the other with an anodized aluminum carrier electrode and 20 microamperes current. The feed in both tests was a synthetic mixture of galena and magnetite in equal proportion. With the metal carrier electrode, one pass was sufficient to demonstrate a poor separation. The conductor or deflectate fraction C in table 2 contained only 60 percent galena.

The separation of galena from magnetite was much better with an anodized aluminum carrier electrode and 20 microamperes current. In table 3 the conductor fraction C contained 99 percent galena after one pass with a recovery of 56 percent, which is 10 percent higher than the recovery reported in table 2. The nonconductor portion recovered from the first pass (table 3) was repassed to illustrate that the high selectivity is retained in repasses, and the combined conductor product represented a recovery of 73 percent of the total galena in a 95 percent galena product.

Similarly, ratio values calculated from the data for ilmenite and columbite (figure 6) are listed in table 4. In this case comparative separation tests were run on an aluminum metal roll at 150 microamperes current and on an anodized aluminum roll at 10 microamperes. The results are summarized in tables 5 and 6. In both tests the nonconductor fraction was repassed twice. It is interesting to note that the results from using a metal roll in table 5 are in accordance with the microampere data of table 4, the concentrate representing an enrichment of ilmenite instead of columbite. The better separation is shown in table 6, in which 73 percent of the total columbite was recovered in a combined 81 percent conductor product, whereas in table 5 the same recovery is indicated in a nonconductor concentrate containing only 65 percent columbite.

The minerals previously described belong to the high conductivity range. For minerals of lower conductivity the increased separation efficiency is not obtained; for some combinations, such as nonconductors and intermediate conductors, the metal carrier electrode is more efficient. These facts are illustrated in figure 7, where the conductor fraction, or the amount of individual samples of pure mineral particles collected on the ionizing electrode side of the dividing edge, is plotted versus the logarithm of the relative resistivity of the particle. Both are on linear scales. The relative resistivity values are for single particles measured at 50 C, determined by the method described in a previous report.

roll, which had an adjacent single wire ionizing electrode, the metal roll was used with a combination of ionizing wire and static- field electrodes. The combination electrode is a typical adaptation of metal- roll, electrostatic separators now in commercial use.

The highest conductivity mineral in figure 7 is galena. The amount collected as a conductor fraction is 99 percent with the metal roll and 72 percent with the copper oxide roll. Although both curves have an abrupt dip in the quantity collected as a conductor fraction, the dip occurs at different mineral resistivities for the two roll surfaces. The dip for the metal roll is in the range from 10 13 to 10 14 ohms, while for the copper oxide roll it is in the range from 10 10 to 10 11 ohms. Minerals with a greater or lesser resistivity than this range may be separated from each other with high efficiency. For example columbite and samarskite with resistivities of 10 10 and 10 11 ohms respectively cannot be separated with the metal roll, but are efficiently separated with the copper oxide roll. Similarly samarskite and hornblende with resistivities of 10 11 and approximately 10 14 ohms, respectively, can be separated with the metal roll but cannot be separated with the copper oxide roll. Galena is one of the highest conductivity minerals. Included with galena are the sulfides of copper and iron and the arsenides of nickel and cobalt, such as niccolite, rammelsbergite, and smaltite.

The effect of a combination of ionizing and static-field electrodes was investigated with the arrangement illustrated in figure 8. R is the carrier electrode or roll; V, a feed device; D, a dividing edge; and I and E are electrodes. I is the single wire ionizing electrode used previously, but in this case it is partly surrounded by the metal shield, S, at ground potential. E is a staticfield electrode in the form of a metal cylinder 2 inches in diameter. The function of the metal shield, S, is to isolate electrodes I and E so that neither has an influence on the other. Without the shield, S, a change in the potential of electrode E would cause a change in the ionized discharge from electrode I.

Table 7 summarizes the results of treating individual samples of pure, unmixed minerals with anodized aluminum and copper oxide carrier electrodes, as well as double field electrodes. When the potential of electrode E is zero the conditions are equivalent to the previous single wire ionizing electrode tests. Tests 1 and 2 (galena on anodized aluminum) and tests 5 and 6 (rutile on copper oxide) were conducted under these conditions. The results were predictable. Rutile has a lower conductivity than galena, but with the higher conductivity copper oxide roll, the amount of conductor fraction is approximately the same. However, a significant change occurs when a potential is applied to electrode E. In tests 3 and 4 (anodized carrier electrode) the amount of conductor fraction decreases, and in tests 7 and 8 (copper oxide carrier electrode) the amount of conductor fraction increases.

The difference is that in tests 3 and 4 with the barrier-layer electrode, the potential between particle and electrode drops to a plateau value. This value is a minimum potential below which no current can flow across the barrier layer. The particle thus carries a residual charge; and when the static field is added, there is an increased adhesion of the particle to the carrier electrode.

With the copper oxide carrier electrode in tests 7 and 8 there was no barrier layer, and the potential between particle and electrode gradually dropped to zero. The particle acquired an opposite induced charge from the added static field, and thus had an increased deflection toward the staticfield electrode.

The separation response of particles is dependent on particle conductivity, roll- surface conductivity, ionizing-electrode current, and static-field intensity to such an extent that the relative separation efficiency of single and double electrodes cannot be predicted. Table 8 summarizes the results of treating individual samples of pure minerals with a single wire electrode at two ionizing currents and with a double electrode having two adjustments. Figure 9 shows the apparatus for the double electrode. The ionizing wire electrode in the double electrode arrangement is not shielded and it is therefore not possible to independently vary the ionizing current and the staticfield intensity. However, the potential is maintained approximately constant, and with the ionizing and staticfield electrodes connected to the same potential source, the ionizing current, although not measured, varies with respect to the adjustment of angle i.

Data of table 8 illustrate that one electrode system cannot be stated as being better than the other. For example, with individual samples of pure wolframite and acmite the calculated ratio of conductor fractions is greater with the single wire electrode than with the double electrode. However, with wolframite and hubnerite the reverse is true.

The greatest disadvantage in using film surfaces is wear. With semiconductor surfaces the layers may be deep enough that wear is negligible. It is also possible to select exceptionally hard materials for film surfaces. Most of the wear is caused by the abrading action of brushing adhering mineral particles off the carrier electrode. A soft bristle brush was used in the tests to minimize wear. If the particles are fed to the carrier electrode with a vibrating feeder arranged so that the drop distance to the electrode surface is small, electrode wear other than that caused by a brush should be negligible.

Adhering particles can be removed to some extent by a second or secondary ionizing electrode excited with either alternating current or reversed-polarity direct current. All particles are usually not removed by this method, but those that remain adhere only weakly and may be removed by a gentle mechanical force. Figure 4 illustrates an arrangement of secondary electrode, J, and air jet, A. Actually A is a cross section of a tube that is inch in outside diameter, is oriented parallel to the roll shaft, and is spaced to 1 inch from the roll surface. The holes for the air jet are 0.040 inches in diameter and spaced at inch intervals. An air pressure of 3 psi was adequate for residual particle removal. Electrode J is similar to I, consisting of a 0.0 10- inch- diameter wire. The ionizing current to J is opposite in polarity to the current to I and smaller. A current of approximately 3 microamperes per inch length of wire is satisfactory. When the current to I is held constant, and the current to J is varied, there is variation in the amount of conductor fraction. However, the current to J, compared to the current to I, has only about one-tenth the effect on the amount of conductor fraction.

For successful electrostatic separation, the behavior of the component minerals of the tested ore under various conditions should be known. In the course of investigation, it was found that these are difficult to measure accurately by the presently available methods. The method used by Johnson is handicapped by the fact that particles in the extreme front and rear end of the falling stream are difficult to control or observe accurately. Furthermore, this method is not applicable when the tested sample consists of more than one mineral. The deflection method, as reported by Fraas, is inadequate to show the differential amounts of mineral particles deposited at the various horizontal positions under the grounded roll of the separator. This weakness is further noted when the tested sample contains more than one mineral.

Experimental: A new apparatus termed, distribution analyzer, was used to replace both the dividing gauge and the two attached collecting chutes of a Johnson separator. This distribution analyzer consists of sixty or more 1.0-cm wide cells as shown in part in fig. 1; it has been fully described in a previous article.

Except where otherwise stated, the testing procedure used in this paper is as follows: (a) calculate the weight of feed for a 1-min run at a constant feed rate of one layer of closely packed particles falling on the grounded roll; (b) weigh and dry the feed at 100C for 12 hr; (c) place the

top of the distribution analyzer level 4 cm below the bottom of the grounded roll, so that the cells are longitudinally parallel to the grounded roll and the zero edge of a suitable cell is directly under the front vertical tangent to the grounded roll (see fig. 1); (d) with the charged roll at a negative potential of 15.5 kv, the dry hot sample is introduced into the feed chute at a constant feed rate; and (e) finally the deposited mineral particles are removed from each cell and weighed and analyzed when the tested sample contains more than one mineral.

Optimum Condition of Separation: There are two methods to ascertain the optimum condition of electrostatic separation of minerals. One is to test the ore sample directly under various conditions and is termed ore-method. This can be exemplified by the tested data of a synthetic mixture of 82 pet anthracite coal, 14 pct quartz and 4 pct pyrite by weight.

It should be noted that the surface condition of the component minerals used for the mineral-method requires special attention. For example, it was found in the course of investigation that the conductivity of lower conducting minerals was somewhat increased by contamination with higher conducting minerals, such as coal, graphite, and galena.

In comparison of the ore-method with the mineral-method, the former is more direct and accurate but requires analysis of the mineral particles deposited in each cell of the analyzer. The latter is indirect and less accurate but requires no analytical

The behavior of mineral particles in an electrostatic field is a surface phenomenon and is governed chiefly by the surface atoms and ions instead of the internal composition of mineral particles. For example, the electrostatic behavior of quartz can bealtered by changing its surface condition with chemicals and moisture.

Potential and Polarity: In regard to the effect of the magnitude of applied voltage on the behavior of mineral particles, shows that to a certain limit calcite particles are repelled farther with the increase of applied voltage. When applied voltage is increased the field intensity is also increased and consequently the electric induction of mineral particle.

Virtually all commercial use of electrostatic separation has employed separators depending on differences of conductance of the broken, solid mixtures treated by them. The two main types of conductance separators have been: (1) Those in which the separating field is as near a static field between two charged electrodes as it is possible to maintain in the face of the usual leakage that takes place between electrodes with some 5 to 50 kv tension between them and spacing of to 3 in.; (2) those in which a convective discharge of corona or spray type, but not a spark discharge, takes place between the carrier electrode and a charged electrode facing it, which is of very restricted area, such as a row of needle points or a small diameter wire parallel to the face of the carrier electrode.

The ions emitted by the corona electrode, or wire F, charge both the particles on the carrier electrode, or roll A, and the surface of the dielectric electrode B. Whereas the space between roll A and wire F contains ions, the space between electrode B and roll A is a pure static field free of ions.

In operation the ionic field from the corona electrode is balanced with the static field from the dielectric electrode. The ionic field charges the particle so that it adheres to the roll. The static field intensifies the discharge of the corona charge by interfacial conduction and permits the release of the particle. The ionic and static fields therefore have opposing effects. The values of both fields are adjusted so that the poor conductor will adhere and the good conductor will be released.

In the field F, the corona-charged particle has a greater adhesion to the roll than out of the field. When the particle is in the field but off the roll, the attraction toward the roll is less than when the particle is on the roll. This is an explanation for the violent ejection of the conductors from the roll. A great force of adhesion, if present momentarily with the conductive particles, is a factor contributing a favorable interfacial surface conductance.

If for a given particle size the separator is adjusted so that for the nonconductive particle fe = fc then for all larger particles, fe < fc, and for all smaller particles, fe > fc. The correct procedure is to select an adjustment so that fe > fc, for the maximum nonconductor particle size.

A frequency distribution of charging rates may result from either variations on each particle or variations between particles. The former has been demonstrated with straight-line probability plots. With the latter, some particles may have, by chance, a low conductance surface exposed. Regrinding would yield a new distribution.

Ilmenite, high-iron chromite, and magnetite have conductivities which correspond to specular hematite and yield equivalent results. Low-iron chromites have lower conductivities, and when associated with diopside and serpentine having apparent conductivities higher than that of quartz, size classification of the fine fraction is required. Commercial operation would require air or an electrostatic method for classification at sizes finer than 20-mesh. Electrostatic sizing will be discussed in a later paper.

vibrating feeder | henan deya machinery co., ltd

vibrating feeder | henan deya machinery co., ltd

Vibrating feeder is used for feeding the materials from the silo to receiving device evenly, regularly, and continuously. In the crushing plant, it feeds the crusher evenly and continuously, and it has the pre-screening function. Vibration feeder is widely combined used in crushing and screening equipment for metallurgy, coal, mineral processing, building materials, chemicals, abrasives and other industries.

Vibrating Feeders are used where a compact feeder with variable speed control is required. Vibrating Grizzly Feeders have features similar to the Vibrating Feeder plus grizzly bars for separating fines from crusher feed. This feeder increases crushing plant production and reduces crusher liner wear because fines are bypassed around the primary crusher.

synonyms: vibrating feeder, grizzly feeder, vibrating grizzly feeder, vibrating feeder, vibration feeder, stone crusher vibrating feeder, crusher vibrating feeder

crusher plant | henan deya machinery co., ltd

crusher plant | henan deya machinery co., ltd

A Stone Crushing Plant is one-stop crushing installation, typical materials like limestone, granite, river gravel, basalt, etc., the plant produces different sizes of gravels and sand which can be used for constructions.

Stone Crushing plants may be either fixed or mobile. A stone crushing plant has different stations, primary, secondary, tertiary, etc., where different crushing, selection and transport cycles are done in order to obtain different stone sizes, for fixed plant different stages combines together to form a complete stone crushing plant.

Raw materials are evenly and gradually conveyed into jaw stone crushing equipment for primary crushing via the hopper of vibrating feeder. The crushed stone materials are conveyed to crushing plant by belt conveyor for secondary crushing before they are sent to vibrating screen to be separated. After separating, qualified materials will be taken away as final products, while unqualified materials will be carried back to the stone crushing equipment for re-crushing. Customers can classify final products according to different size ranges, also according to different requirements, final products sizes can be adjusted from the crusher machines.

meyer industries, inc./precesion food | vibratory feeder manufacturers

meyer industries, inc./precesion food | vibratory feeder manufacturers

Meyer Industries, Inc. is a leading manufacturer of high-quality vibratory feeders. Our feeders include AFN vibratory feeders, EDN vibratory feeders and automatic feeders. We are your single source for food handling and processing equipment. For more information please contact us today!

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