high-speed gyratory crushing --> fine cone crushers
I covered briefly the development of various types of reduction crushers of the gyratory family. Below you see a gyratory reduction crusher, which introduced the cylindrical top shell, flared head, and reversible concaves. Even with the older style of straight concaves, with which this machine was originally fitted, it represented a distinct step forward in secondary crusher design, and the later introduction of non-choking concaves increased its efficiency and permitted the use of finer settings than were originally allowable. This type of machine, although it has been superseded in the fine reduction field by more efficient types, still rates as a very excellent crusher for secondary crushing work.It has good capacity at moderate settings, is ruggedly constructed, and has, for comparable sizes, relatively large receiving openings, as compared to machines designed primarily for fine reduction work.
To show why this machine was a distinct step forward in secondary crusher design, it is interesting to compare the action of its crushing chamber to the standard crusher chambers already described. To make clear the fact that the machine had certain advanced features, even before non-choking concaves were developed, letsfirst show a diagram of its crushing chamber with the older type of beveled, straight-face concaves. It should be mentioned that these beveled concaves were not the very earliest type used in this crusher; they were preceded by plain, straight concaves, which utilized the full rated receiving opening of the crusher, but had the same disadvantage we noted in connection with this type, as used in the standard gyratory concentration of wear at the discharge point. The beveled type spread the wear out somewhat, although at the cost of some reduction in the effective receiving opening.
The distinctive feature of the design shown hereis the decided slope of the line-of-mean-diameters away from the center-line of the crusher, as this line runs down through the crushing chamber. As the volumes of the successive rings of material are functions of their diameters, as well as their areas, it is apparent that these progressively increasing diameters tend to offset the decreasing areas; in other words, the flared head spreads the material as it moves downward, thereby tending to minimize the ratio-of-volume-reduction. The actual compression-ratio in this chamber is about 1.5:1, which is lower than in either of the diagramspreviously discussed and very much lower than the case of the standard crusher with straight concaves.
This became the cone crusher and this departure from the older conventional design was a decided improvement for secondary crushing is apparent when we compare two machines of approximately equal head diameters, a logical comparison because the diameter of the bottom of the crushing head directly affects the area of discharge opening and, hence, the capacity of the crusher. This 10 reduction crusher, with its 40 head, compares closely, in this respect, with the 20 standard crusher, which has a 38 head. Using straight-face concaves, the permissible minimum open side settings are 1.5 for the former, and 3.5 for the latter. With non-choking concaves these settings are, respectively, 1 1/8 and 2 1/4.
To show the characteristics of this type of crusher when fitted with non-choking concaves we have prepared a diagram of the same size machine so equipped. You now have the cumulative benefits of the flared head and curved-profile liners. There is a marked reduction in the number of strokes required to shift plane O down to the discharge level; the choke-point has been raised, and the ratio of volume reduction is lower (about 1.2:1).
There is a decrease in the effective receiving opening, as compared with the straight-face chamber, when using full-curve, non-choking concaves, which is the type shown in our diagram. This effective opening is established by the maximum angle of nip; therefore it varies somewhat for different materials, and in different sizes of crusher. For this crusher 26 deg. was chosen as the governing angle; about 28 deg. is the conservative maximum for the largest machines of this type.
So far, all of the crushers we have been discussing have been of the low-speedclass; that is, with eccentric speeds ranging between the approximate limits of 100-200 RPM. It is customary, as before mentioned, to rate such crushers at their open-side discharge settings, because there is a definite relationship between these values. Most modern crushers, designed for what may properly be classed asfine-reduction crushing, are of the high-speed type. The eccentric speeds and shape of the crushing chamber in the machines of this type are such that the maximum one-way dimension of the product particles is established by the close-side discharge setting; consequently it has become customary to rate these crushers at this setting.
The Newhouse crusher was one of the early developments in the highspeed class of fine-reduction crusher incorporates several unusual features, at least one of which is unique in crusher design. The eccentric is direct-driven by a vertical motor mounted above the spider, the drive shaft running down through the hollow-bored mainshaft. Speeds range from 480 to 580 RPM, depending upon the size of the crusher, and upon the frequency of the electric current. Eccentric throws, as compared with those of the crushers we have been dealing with, are relatively low. This combination of small throw and high speed results in a very uniform product with a minimum amount of fines for any setting and ratio of reduction. A unique feature is suspension by means of cables, eliminating the usual foundation, although the crusher can be set on a foundation where required.
This crusher is usually furnished with full-curve, non-choking concaves, which are reversible in the top shell. These concaves are of the same general contour as those shown in the above diagram of the reduction crusher chamber and in general the crushing chamber is similar, except that the chamber in the Newhouse crusher is somewhat deeper and, consequently, the head does not have as pronounced a flare. The important difference in the crushing action of these two machines lies in the difference in eccentric speed. That of the Newhouse crusher is so high that no material can drop through the almost parallel zone just above the discharge point without being caught between head and concaves and broken to a maximum oneway size closely approximating the close-side setting.
This crusher can be set somewhat closer than comparable sizes of the reduction crusher previously described. Although it cannot be classed as a fine-crusher it does belong to the fine-reduction class. Furthermore, by virtue of its large receiving openings, it rates as a machine for secondary reduction work. When so used it is usually fitted with concaves of the non-reversible, non-choking type, which are designed to make use of the full rated receiving opening of the crusher, although they sacrifice the feature of reversibility which permits wearing both ends of the concaves.
cone crushers | mclanahan
A Cone Crusher is a compression type of machine that reduces material by squeezing or compressing the feed material between a moving piece of steel and a stationary piece of steel. Final sizing and reduction is determined by the closed side setting or the gap between the two crushing members at the lowest point. As the wedge or eccentric rotates to cause the compression within the chamber, the material gets smaller as it moves down through the wear liner as the opening in the cavity gets tighter. The crushed material is discharged at the bottom of the machine after they pass through the cavity.
A Cone Crusher will deliver a 4:1 to 6:1 reduction ratio. As we set the closed side setting tighter to create a finer output, we also reduce the volume or throughput capacity of the machine. Generally speaking, multiplying the closed side setting by two is a good guide to the top size of the gradation exiting the machine.
The technology that makes a MSP Cone Crusher outperform competitive cones on the market is the combination of all of the factors of performance i.e. balanced eccentric, higher speeds, fulcrum point position, and stroke. By using sound engineering with years of field testing a truly tried and tested new Cone Crusher has emerged.
A balanced eccentric coupled with a fulcrum point ideally placed over the crushing chamber yields highly effective compression crushing. This allows higher eccentric speeds to maximize performance without disruptive forces. The eccentric stroke is designed to work with the eccentric speed and fulcrum position to produce higher yields and minimize recirculating loads. The torque and resultant crushing forces are as effective as virtually any Cone Crusher on the market.
Spiral bevel gears provide the turning force to the eccentric. The spiral gear is mounted on a sturdy countershaft of the Cone Crusher, which rides in bronze bushings. The gears are precision cut for quiet operation. Misalignment problems are eliminated.
The MSP Cone Crusher features one of the largest volume displacements by a crusher head. When there is a large volume of material displaced this way, it means that more material is crushed in each cycle, more material can be fed to fill the larger void left when the crushing head recedes, and more material flows through the crusher due to the larger throughput and gyrating cycles allowing material to drop further. The benefits of high efficiency, greater crushing force and high capacity coupled with the durability the market expects are the reasons why this design is the best way to increase your productivity and profitability.
Sleeve bearings make removal and installation of the MSP Cone Crusher head and main shaft simple. The tapered main shaft fits into a large opening at the upper end of the tapered eccentric bushing. The shaft does not require precise alignment. It can be inserted from a vertical position and will self-align.
With the MSP Cone Crushers automatic hydraulic overload relief system, the crusher immediately opens in the event of an overload. This action reduces the crushing pressure, allowing the obstruction to pass through the chamber. After the chamber has been cleared, the hydraulic control system automatically returns the crusher to its original setting. Shock loads on the crusher are reduced for longer component life.
MSP Cone Crushers are built to make your operations run more smoothly and easily. Its simple and easy to read control panel provides you with the necessary information to properly run your crusher. For example, the MSP Cone Crusher shows you the exact cone setting to allow the operator to stay on top of a critical set point.
To enhance your Cone Crusher's life and maintain optimal crushing capacities, an automatic liner change reminder is included for your convenience. When the new mantle and liners are installed, the automated reminder is reset. As the crusher operates, the system will track production capacities and calculate the liner wear rate. When the cone liners reach the maximum wear point, it sends a flashing reminder to 'change cone' on the cone setting meter. After the wear parts are changed, simply reset the automated reminder system and continue efficient, reliable crushing.
The MSP Cone Crushers are built heavier than most competitive Cone Crushers. The extra weight means lower stress on the machine, which results in longer operational life. There is no question that the proper use of mass makes for more durable crushers. Additionally, a broad array of manganese liners is offered for each size MSP Cone. A unique and patented feature allows the Liners to fit without the use of any backing material. Improved Chamber matching with crusher feeds virtually eliminates any trial and error.
All these factors combine to give producers more effective compression crushing. This reduces liner wear, which reduces wear cost and allows higher yields, resulting in decreased overall cost per ton of finished product.
In the Symons principle, which is utilized by the MSP Cone Crusher, each cycle is timed so that the feed material and the upward thrust of the crushing head meet at the moment of maximum impact. The optimum speed of gyration and the large eccentric throw produce two important results: 1) the rapidly closing head catches the falling feed material and delivers the extremely high crushing force and 2) on the other side of the chamber the rapidly receding head allows material to fall freely to the next point of impact or exit the chamber. The combination of superior crushing force and free flow of material in the MSP Cone Crusher results in production levels that are unsurpassed and means lower power consumption per ton.
Ten years of testing went into the final combination of speed, stroke, and head angle to deliver the most efficient use of power. Greater efficiency delivers lower power consumption, reduced cost per ton, less maintenance and higher profits.
The power input imparted by the driven eccentric results in a bearing force in opposition to the crushing force at a point on the lower portion of the main shaft. The bearing force as it is transmitted to the main shaft provides the required moment to crush the rock. The distance between the bearing force and the fulcrum point is called the force arm. The longer the force arm, the greater the momentum, which produces a greater crushing force.
Crushing loads are distributed over a large spherical bearing. The socket liner keeps full contact with the crushing head ball and carries all of the vertical component and part of the horizontal. The long force arm, represented by the main shaft, reduces the load transmitted through the eccentric bushing.
Capacities and product gradations produced by Cone Crushers are affected by the method of feeding, characteristics of the material fed, speed of the machine, power applied, and other factors. Hardness, compressive strength, mineral content, grain structure, plasticity, size and shape of feed particles, moisture content, and other characteristics of the material also affect production capacities and gradations. Gradations and capacities are most often based on a typical, well-graded choke feed to the crusher. Well-graded feed is considered to be 90% to 100% passing the closed side feed opening, 40% to 60% passing the midpoint of the crushing chamber on the closed side (average of the closed side feed opening and closed side setting), and 0 to 10% passing the closed side setting. Choke feed is considered to be material located 360 degrees around the crushing head and approximately 6 above the mantle nut. Maximum feed size is the average of the open side feed opening and closed side feed opening.
Minimum closed side setting may vary depending on crushing conditions, the compressive strength of the material being crushed, and stage of reduction. The actual minimum closed side setting is that setting just before the bowl assembly lifts minutely against the factory recommended pressurized hydraulicrelief system.
Overall, industry acceptance of the Symons principle and performance, the McLanahan Cone Crusher works to deliver lower recirculating loads at higher tonnage rates with lower maintenance costs by combining:
A general rule of thumb for applying Cone Crushers is the reduction ratio. A crusher with coarse style liners would typically have a 6:1 reduction ratio. Thus, with a 34 closed side setting, the maximum feed would be 6 x 34 or 4.5 inches. Reduction ratios of 8:1 may be possible in certain coarse crushing applications. Fine liner configurations typically have reduction ratios of 4:1 to 6:1.
The difference between the volume displaced by the crushing head when it is fully closed and fully open is called the displacement volume. A large displacement volume results in greater capacity because:
In order to maintain the maximum levels of capacity, gradation, and cubical product, a Cone Crusher must be choke-fed at all times. The best way to keep a choke-feed to the ConeCrusher is with a surge bin (or hopper) and feeder that are located prior to the crusher. Choke-feeding is almost impossible to achieve without a hopper and feeder.
There are a number of different criteria to consider when selecting the right chambers for your crushing needs. However, the one that must always be considered isthat you have a well-graded feed to the chamber. A well-graded feed is generally thought to be 90 to 100% passing the closed-side feed opening, 40 to 60% passing the midpoint, and 0 to 10% passing the closed-side setting.
One thing you should never do is place a new concave liner in a crusher with a worn mantleor place a new mantle in a crusher with a concave liner. Why? If you have properly selected the replacement component, you will change the complete profile of the Cone Crusher by mating new and worn components. The receiving opening will tend to close down, restricting the feed from entering the chamber and causing a reduction in tons per hour.
If the liner is wearing evenly throughout the chamber, you should consider changing out the manganese when it has worn down to about 1" (2.5 cm) thick at the bottom. At about 3/4" to 5/8" (1.9 to 1.6 cm) thick, the manganese will crack, causing the backing material to begin to disintegrate. This, in turn, will cause the liners to break loose. If this should happen, continued operation could destroy the seat on the support bowl or the head of the Cone Crusher.
McLanahan Symons Principle (MSP) Cone Crushers utilize a
combination of improved factors of performance, which are enhanced by the
Symons Principle of crushing, as well as the latest hydraulic features and
electrical features that create a modern, efficient, reliable and durable Cone Crusher
that ultimately leads to a faster ROI. MSP Cone Crushers are designed to make
your operation run more smoothly and easily, as well as ensuring lower
operating costs and minimal downtime so that MSP Cone Crushers are more
frequently fully operational and processing optimal amounts of material.
Efficiency can be defined by the ratio of the work done by a machine to the energy supplied to it. To apply what this means to your crusher, in your reduction process you are producing exactly the sizes your market is demanding. In the past, quarries produced a range of single-size aggregate products up to 40 mm in size. However, the trend for highly specified aggregate has meant that products have become increasingly finer. Currently, many quarries do not produce significant quantities of aggregate coarser than 20 mm; it is not unusual for material coarser than 10 mm to be stockpiled for further crushing.
new fine quality cone crusher real-time quotes, last-sale prices
Featuresofnew fine quality cone crusherThis cone crusher is suitable for crushing various kinds of ores and rocks with medium over hardness and it has the features of reliable structure, high production efficiency, convenient adjustment and economic use. The spring safety system is the overload protection device which is able to make the iron go through the crushing chamber without damaging machine. It adopts two sealing means: dry oil and water to separate stone powders and lubrication grease, thus ensuring reliable work of the machine.This series of crusher machine is divided into three types, namely coarse cone crusher, medium cone crusher and fine cone crusher, and the standard type is suitable for medium crushing; the medium type and the short-headed type is suitable for fine crushing, so that the customers can choose different types according specific need.Workingprincipleofnew fine quality cone crusherWhen cone crusher begins to work, the electro motor drives the eccentric sleeve through the spring coupling, drive shaft and a pair of angle gear, so that the crushing wall of cone crusher gets close to and then gets away from the surface of the rolling mortar wall fixed on the adjusting sleeve, and the ores inside the crushing chamber will be constantly impacted, squeezed and bent to be crushed.TechnicalParametersofnew fine quality cone crusherodelDiameterofcrushingcone(mm)Max.feedingsize(mm)Widthofdischargeopening(mm)Processingcapacity(t/h)Motorpower(kw)SwingfrequencyofmainshaftTotalweight(t)Dimensions(LWH)(mm)PYB6006006 65223413701675PYD353-1312-235.5223413701675PYB90090011515-5 1.2269216402350PYZ605-2020-6511.2269216402350PYD503-1315-5011.3269216402350PYB1200120014520-50110- .7279018782844PYZ1008-2 018782844PYD503-1518-10525.3279018782844PYB 25-5 550.3391028943809PYZ18510-30115-32050.3391028943809PYD855-1375-23050.2391028943809PYB2200220030030-6 -26022080462233024470PYZ23010-3 233024470PYD1005-15120-34081.4462233024470Packing&DeliverytimeOnemonthwithnude
This cone crusher is suitable for crushing various kinds of ores and rocks with medium over hardness and it has the features of reliable structure, high production efficiency, convenient adjustment and economic use. The spring safety system is the overload protection device which is able to make the iron go through the crushing chamber without damaging machine. It adopts two sealing means: dry oil and water to separate stone powders and lubrication grease, thus ensuring reliable work of the machine.
This series of crusher machine is divided into three types, namely coarse cone crusher, medium cone crusher and fine cone crusher, and the standard type is suitable for medium crushing; the medium type and the short-headed type is suitable for fine crushing, so that the customers can choose different types according specific need.
When cone crusher begins to work, the electro motor drives the eccentric sleeve through the spring coupling, drive shaft and a pair of angle gear, so that the crushing wall of cone crusher gets close to and then gets away from the surface of the rolling mortar wall fixed on the adjusting sleeve, and the ores inside the crushing chamber will be constantly impacted, squeezed and bent to be crushed.
fine impact crusher,fine crusher for sale,buy fine crusher,fine crusher--zhengzhou bobang heavy industry machinery co.,ltd
The series single-stage fine crusher is developed based on the single-stage (counter-attack) hammer crusher to crush raw materials for industry such as limestone, gypsum, raw coal and so on and further to simplify the work flow of smashing. The product granularity is small (80% <5mm) in comparison with the ordinary single stage hammer crusher. The equipment investment is lower about 35~50% than that of the same scale traditional process. The charge of long-term movement is lower about 30% than that of the same scale traditional process equipment system. It has widely applied in cement, sand and stone material, electric power professions and so on.
This series fine crusher is with such advantages: Reliable and stable running, Simplified technology, Simple structure, Easy maintenance, large capacity and long life hammers. It is widely used in granite, basalt, limestone, river gravel, cement clinker, quartz stone, iron ore, bauxite and other minerals. The mechanism is also used for artificial sand, high-grade highways, railways, water conservancy, airport, construction, cement, refractory, metallurgical and other industries producing high-quality stone. Main Technical Parameters of Fine Impact Crusher
Copyright Zhengzhou Bobang Heavy Industry Machinery Co.,Ltd.
E-mail : [email protected]
Address No.11 West Construction Road, Zhongyuan District,Zhengzhou City,Henan Province, China
cone crushers for sale
The cone crusherwas designed primarily with a view to achieving top performance in the field of fine-reduction crushing. It has also been adapted to what is designated simply as fine crushing, which extends into a range below that ordinarily defined by the term fine-reduction. Although the eccentric speeds of the various sizes of this type are not quite so high as the speeds used for the Newhouse crusher, the Hydro-cone crusher definitely rates as a high-speed machine, its product comparing quite closely to that of the former type, for equal close-side settings.Probably the outstanding feature of the. Hydrocone crusher is the hydraulic support, from which its name is derived and which is clearly shown in the sectional view. This device makes it possible to adjust the crusher to any desired setting within its range in a matter of seconds;adjustments may be made while the crusher is running, although the feed must be shut off before operating the adjusting pump. An accumulator in the hydraulic system provides protection against tramp iron or packing.
Cone crushers are used in AG and SAG grinding circuits to increase tonnage by effectively dealing with any pebble (critical size) build-up problem. Normally, heavy-duty short-head crushers are employed to crush pebbles. Power and crusher cavity level are the key variables for monitoring and controlling the crusher operation. Crusher product size is adjusted by changing the closed side setting.
On the left is a diagram of the Hydro-cone crushing chamber. A comparison of this chamber with those previously discussed is interesting. It will be noted that the choke-point has been raised far above the discharge level, in fact, to a point not far below the nip-point for the recommended maximum one-way feed dimension. By virtue of the decided flare of the head, and the corresponding flare of the top shell bore, the line-of-mean-diameters slopes sharply away from the crusher centerline. For some, distance above the discharge point the angle between head and concave is very acute; in fact, at the open-side position of the head, this zone is almost parallel. For recommended operating conditions, i.e., for safe combinations of throw and setting, and with screened feed, this type of crushing chamber does not approach anything like a choke or near-choke condition. For the combination shown in the diagram the ratio of volume reduction is almost 1:1 from zone 0-1 to zone 2-3 at the choke-point; consequently, if the crusher is given a screened feed (as all fine-reduction crushers should be) the reduction in voids by the time the choke-point is reached cannot very well reach serious proportions. The diagram shows the standard chamber. With screened feed, these crushers will operate at closed-side discharge settings equal to the throw of the head at the discharge point (usually spoken of as eccentric-throw.)
The level in the crusher feed pocket is an important variable since it can indicate whether the feed is building up. A build-up could lead to a plugin the feed chute, a spill through the skirting on the crusher feed, or a crusher plug. None of these are desirable.
In a normal feed situation, the level in the crusher cavity is kept fairly low, just enough to ensure that there is sufficient feed to keep the crusher working, but if the feed has to be suspended suddenly because of impending plugging, the crush-out wont take too long (10 seconds or less). Normal feed is usually used in standard crushers where the feed particle size is quite large, say greater than 65 mm.
Choke feed is when the crusher cavity is kept full, without spilling out through the skirting. Choke feeding is usually used in short-head crushers where the feed particle is smaller than that for a standard crusher.
This crusher is a modification of the standard machine, developed for fine-crushing duty. Mechanically, the machine is the same in every respect as the standard crusher of the same type, but for each developed size of machine a special top shell and the concave ring has been designed, with reduced receiving opening, reduced angularity between head and concave, and, consequently, superior characteristics at the finer settings. Medium crushing chambers may be operated at close-side settings of one-half the eccentric-throw, on screened feed; hence capacities at the finer settings are better than those of the standard type. Fine crushing chambers operate at one-fourth the eccentric throw. Inasmuch as the maximum feed size is smaller in the case of the fine chamber, the ratios of reduction are approximately the same for both machines.
There are two main types of cone crushers: standard and shorthead. They differ by the shape of the cavity. The standard crusher cavity is wider to accommodate larger feed-size material. The short head crusher is designed to crush finer material and to produce a finer product.
The closest approach between the mantle and the bowl liner is called the closed side setting. This is usually specified by the metallurgist to give the desired crusher product discharge size. It can be checked by running the crusher empty, hanging a lead plug into the crusher bowl, and then removing it to measure the gap. The gap is adjusted by rotating the bowl. Some crushers are equipped with a hydraulic jack mechanism on the crushing head assembly instead of having a bowl adjustment ring. The head can be raised or lowered to meet the operators needs. It can be very helpful in operation and process control.
The Symons Cone Crusher has come into almost universal use during the last few years for the final stage of crushing. It is a development of the secondary gyratory crusher, which is merely a small gyratory crusher designed to break the product of the primary machine down to about 1-in. size; but the main shaft of a cone crusher instead of being suspended from a spider is supported on a large socket bearing situated immediately under the crushing head and protected from grit and dust by a sealing assembly, this bearing taking the whole of the crushing load.
Fig. 8 gives a sectional view of the machine. The main shaft is carried in a long gear-driven eccentric, the rotation of which causes the gyration of the head in the usual way, but the center of gyration is at the apex of the crushing head instead of in the spider. At the top of the bowl, therefore, the lumps of ore entering the crushing zone are cracked by short powerful strokes; but at the bottom the head has a much longer but less powerful stroke, enabling the ore in the finishing stages to be rapidly crushed and quickly discharged without any tendency to choke, a condition which reduces over crushing to a minimum. This, together with the curved shape of the bowl, accounts for the large reduction ratio possible with this type of machine and makes it superior to other secondary crushers and coarse rolls.
It will be seen that the head and the bowl are parallel at the lower part of the crushing zone. The parallel space is deep enough, in conjunction with the speed of gyration, to ensure that no piece of ore can pass through it without being struck two or three times by the head before it falls clear. It follows that, unlike the jaw and gyratory crushers, the size of the product is determined by the distance apart of the bottom edges of the head and bowl in the position when they are closest together.
Coarse buttress threads on the outer circumference of the bowl fit into corresponding threads on the inner side of the adjusting ring, which is held down to the mainframe by a circle of long heavy springs, flexible enough to allow the whole assembly to rise should tramp iron or other uncrushable material enters the crushing zone. By means of a windlass and chain, the bowl can be rotated in the threads that support it in the adjusting ring while the machine is running, thus enabling the bowl liner to be adjusted for wear or the size of the product to be changed without stopping. The cone crusher is usually set to give a 3/8-in. or -in. product when discharging to ball mills.
Table 9 gives particulars of the different sizes of crushers. The capacity figures are based on material weighing 100 lb. per cubic foot and must be increased in direct proportions for heavier ores. It will be noted that each size of machine has two ranges of capacity; this is due to the fact that it can be fitted with a coarse or a fine crushing bowl according to the duty that is required of it. With either one, the range of reduction is greater than is economically possible with any other type of dry crushing machine.
A possible disadvantage of the cone crusher is that as a rule it cannot be choke-fed, but must be given an even feed of ore if it is to do efficient work. Should circumstances call for the installation of a machine that can be run if necessary with the ore piled up over the top of the head, a secondary gyratory crusher of the suspended shaft type will be required. The Traylor Reduction Crusher Type TZ, which is constructed on the principles of an ordinary gyratory crusher, but is fitted with a curved bowl liner similar to that of the Symons Cone Crusher, is designed to meet the case. Although the suspension of the shaft restricts the movement of the head to a smaller circle of gyration than that of the cone crusher, the ratio of reduction is still large enough to enable it to crush the product of the primary breaker to -in. size (-in. for the large machines), and it fulfills the condition that it can be choke-fed. Owing to the smaller movement of the head, however, the capacity for a given range is much less than that of the equivalent size of cone crusher, and the latter is therefore preferred when choke-feeding can be avoided.
The Symons Shorthead Cone Crusher, which is constructed on the same general principles as the larger machine, is designed to follow the latter, taking its product at 1-in. and reducing it to about -in. size. The strains imposed on the crushing members, however, would be very heavy if the machine were run with the discharge opening set to -in. or less. It is usual, therefore, to crush in closed circuit with a screen, the discharge opening of the bowl being set to 5/8 or in. Thus a circulating load is built up and a certain amount of choke-crushing takes place, but the method actually gives greater efficiency with a finer product than can be obtained in an open circuit, whatever the discharge setting of the bowl in the latter case.
In ordinary crushing practice, the grinding section is supplied with -in. or 3/8-in. material direct from Symons Cone Crushers. But the demand is for a finer feed and it seems likely that the Shorthead Cone Crusher will satisfy this demand to the exclusion of fine crushing rolls.
Symons Cone Crushers have been used extensively for secondary crushing in metallic, non-metallic, rock products, and industrial operations. The Symons Cone was developed to give large capacity, fine crushing. The combination of high speed and wide travel of the cone results in a series of rapid, hammer-like blows on the material as it passes through the crushing cavity and permits the free flow of material through the cavity.
Reduction in size of any particle, with each impact of the head, is regulated by the opening between the head and bowl at that point. A threaded arrangement of the bowl affords a quick and easy method for changing the size of the product or to compensate for wear. This adjustment can be made while the crusher is operating. A parallel zone between the lower portion of the crushing members assures uniform sizing.
Frame, adjustment ring, and cone are made of cast steel; gears are made of specially treated steel and have cut teeth; all bearings are bronze; mantle and bowl liners are manganese steel. The head and shaft can be removed as a unit, and other parts such as the eccentric and thrust bearings can easily be lifted out after the head is removed. The countershaft assembly can also be removed as a complete unit.
The circle of heavy coil springs, which holds the bowl and adjustment ring down firmly onto the frame, provides automatic protection against damage due to tramp iron. These springs compress, allowing the bowl to rise the full movement of the head until non-crushable material passes through. The springs then automatically return to their normal position.
Symons Cone Crushers are made in Standard and Short Head types. They are of the same general construction but differ in the shape of the crushing cavity. The Standard cone is used for intermediate crushing. The Short Head cone is used for finer crushing. It has a steeper angle of the head, a shorter crushing cavity, and greater movement of the head at the top of the crushing cavity.
If you observe the illustrations you will notice that the center line of the main shaft is at an angle to the center line of the crusher. The center of the main shaft bisects the center line of the crusher at the opening of the crushing chamber. As the MANTLE revolves that point is the pivot point of the mantle. This means that both the top and the bottom of the crusher mantle have a circular gyrating motion.
Tramp iron had long been a source of worry to those engaged in fine crushing.Here is what one operator had to say.Shutdowns were frequent, costs were uncertain because of enforced delays due to excessive breakage. Plugged machines had to be freed continually with a torch tocut out frozen and wedged-in tramp iron.The cone crusher overcame these troubles,helped reduce and stabilize costs. The bestevidence of this statement is the universalacceptance of the cone as the outstandingcrusher in its field.
While tramp iron is not recommended as a regular diet for a Cone Crusher, its construction is such that damage will not result should any ordinary noncrushable material get into the crushing cavity. The band of heavy coil springs encircling the frame allows the bowl to lift from its seat with each movement of the head until Such non-crushable object passes off into the discharge. The tramp iron shown in the accompanying illustration passed the protective devices installed for its removal and would have resulted in expensive repairs and long shutdown periods for any crusher except the Symons Cone.
Cone crushers can have two types of heads, standard and short head types. The principle difference between the two is in the shape (size and volume) of the crushing cavities and feed plate arrangements. Standard head cone crushers have cavities that are designed to take a primary crushed feed ranging up to 300mm generating product sizes around 20mm to 40mm. For finer products, short head cone crushers are normally used. They have a steeper angle of the head and a more parallel crushing cavity than the standard machines. Due to the more compact chamber volume and shorter working crushing length, the much needed higher crushing forces/power can be imparted to the smaller-sized material being fed to the crusher. Cavities for the short head machine are designed to produce a crushed product ranging from 5mm to 20mm in a closed circuit.
At the discharge end of the cone crusher is a parallel crushing section, where all material passing through must receive at least one impact. This ensures that all particles, which pass through the cone crusher, will have a maximum size, in at least one dimension, no larger than the set of the crusher. For this reason, the set of a cone crusher can be specified as the minimum discharge opening, being commonly known as the closed side setting (CSS).
Here are facts about the conecrusher known as Hydrocone. This line of hydraulically adjusted gyratory crushers was developed in smaller sizes some fifteen years ago by Allis-Chalmers to meet a demand for improved secondary or tertiary crushing units. The line is now expanded to include sizes up to 84-in. diameter cones.
This modern crusher is the result of many years of experience in building all types of crushing equipment, when the first gyratory or cone crusher, the Gates, was put into operation. Overall these years AC has followed a continuing policy of improvement in crusher engineering, changes in design being based on operating experience of crushers in actual operation.
The Hydrocone cone crusher is the logical outgrowth, a crusher having a means of rapidly changing product size or compensating for wear on the crushing surfaces a crusher which produces a better, more cubical product than any comparable crusher and a crusher so designed that it can be operated and maintained with a minimum of expense.
The most important fact about the Hydrocone crusher is its hydraulic principle of operation. Hydraulic control makes possible quick, accurate product size adjustments fast unloading of the crushing chamber in case of power failure or other emergency protection against tramp iron or other uncrushable materials in the crushing chamber. Another important fact about this crusher is its simplicity of design and operation. The accompanying sketch shows the simplicity of the Hydrocone crushers principle of operation. The main shaft assembly, including the crushing cone, is supported on a hydraulic jack. When oil is pumped into or out of the jack the mainshaft assembly is raised or lowered, changing the crusher setting.
Since the crushing cone is supported on a hydraulic jack, its position with respect to the concave ring, and therefore the crusher setting, can be controlled by the amount of oil in the hydraulic jack.
Speed-Set control raises or lowers the crushing shaft assembly hydraulically, and permits quick adjustment to produce precise product specifications without stopping the crusher. Speed-Set control also provides a convenient way to compensate for wear on crushing surfaces.
On Hydrocone crushers in sizes up to 48-in., the Speed-Set device is a hand-driven gear pump; on the larger sizes a motor-driven gear pump operated by push-button. On all sizes the setting can be changed in a matter of minutes by one man without additional equipment, reducing downtime materially.
Protection against tramp iron or other uncrushable materials is afforded by an accumulator in the hydraulic system. This consists of a neoprene rubber oil-resistant bladder inside a steel shell. This bladder is inflated with nitrogen to a predetermined pressure higher than the average pressures encountered during normal crushing.
Ordinarily, the Automatic Reset remains inoperative, but if steel or some other foreign material should enter the crushing chamber, the oil pressure in the hydraulic jack will exceed the gas pressure in the accumulator. The bladder will then compress, allowing the oil to enter the steel shell. This permits the crushing cone to lower and discharge the uncrushable material without damage to the crusher.
After the crushing chamber is freed of the foreign material, the gas pressure in the accumulator will again exceed the oil pressure in the hydraulic system. Oil is then expelled from the accumulator shell and the crushing cone is returned to its original operating setting automatically.
A Hydrocone crusher will produce a cubical product with excellent size distribution and a minimum of flats and slivers. This is especially important in the crushed stone industry where a cubical stone is required to meet rigid product specifications. It is also of considerable significance in the mining industry where the elimination of large amounts of tramp oversize reduces circulating loads or makes open circuit crushing possible.
The reason why the Hydrocone crusher will produce such a uniform, cubical product is that it has a small eccentric throw with respect to the crusher setting. This means a smaller effective ratio of reduction during each crushing stroke, and therefore, the production of fewer fines and slivers. Likewise, a small eccentric throw means a small open side setting, which results in a smaller top size of the product. A large percentage of the product from a Hydrocone crusher will be of a size equal to or finer than the close side setting.
For fine crushing, or in installations where the feed to the crusher is irregular, the use of a wobble plate feeder is recommended. This feeder is installed in place of the spider cap and affords a means of controlling the feed to the crusher, as well as a means of distributing the feed evenly around the crushing chamber.
Essentially, the feeder consists of a plate that is oscillated by a shaft extending down into the crushers main shaft. The motion of the main shaft oscillates or wobbles the feeder plate. The plate is supported on a rubber mounting which permits its motion and, at the same time, positively seals the top of the spider bearing against the entry of dust. Maintenance is reduced by the use of self-lubricating bushings between the feeder plate shaft and the crusher main shaft.
Hydrocone crushers are mounted on rubber machinery mountings in order to reduce installation costs and make it possible to locate these machines on the upper floors of crushing plants. These mountings operate without maintenance, absorb the gyrating motion of the crusher, thereby eliminating the need for massive foundations. Rubber mountings also prolong the life of the eccentric bearing, since this bearing is not subjected to the severe pounding encountered when rigid mountings are used.
The exclusion of dust and dirt from the internal mechanism of the crusher is of extreme importance from a maintenance standpoint. To accomplish this, Hydrocone crushers are equipped with one of the most effective dust seals yet devised.
This seal consists of a self-lubricating, graphite impregnated plastic ring which is supported from the head center in such a way that it is free to rotate, or gyrate, independently of the head center.
The plastic ring surrounds the dust collar with only a very slight clearance between the two parts. With the plastic ring being free to move as it is, it accommodates the rotation, gyration, and vertical movement of the main shaft assembly, maintaining the seal around the dust collar at all times. Because of its lightweight and self-lubricating characteristics, wear on the plastic ring is negligible.
The ease with which any wearing part can be replaced is of the utmost importance to any crusher operator. With this in mind, the Hydrocone crusher has been designed so that any part can be replaced by disturbing only a minimum number of other parts.
For example, the Mantalloy crushing surfaces are exposed by simply removing the top shell from the crusher. This can be done easily by removing the nuts from the studs at the top and bottom shell joint. The eccentric and hydraulic support mechanisms are serviced from underneath the crusher without disturbing any of the feeding arrangements, or the upper part of the crusher.
Efficient lubrication of all wearing parts is one of the reasons why crushing costs are low with the Hydrocone crusher. On most sizes, lubrication is divided into three distinct systems, each functioning independently.
This bearing, whether of the ball and socket type as on the smaller sizes, or of the hourglass design (as shown) found on the larger Hydrocone crushers, is pool lubricated. On the 51, 60 and 84-inch sizes, provision is made for introducing the lubricant from outside the top shell through the spider arm. On the smaller crushers, oil is introduced through an oil inlet in the spider cap. On all sizes, oil is retained in the bearing by a garter-type oil seal located in the base of the spider bearing.
All Hydrocone crushers are provided with a compact external lubrication system consisting of an oil storage tank, an independently motor-driven oil pump, a pressure-type oil filter, and a condenser-type cooler.
Cool, clean oil is pumped into the crusher from the conditioning tank, lubricating first the three-piece step bearing assembly. The oil then travels up the inner surface of the eccentric, lubricating the eccentric bearing and main shaft.
At the top of the eccentric, the oil is split into two paths. Part of the oil flow passes through ports in the eccentric and down its outer surface, lubricating the bronze bottom shell bushing, driving gears and wearing ring. On the 48-in. and smaller crushers, the balance of the oil overflows the eccentric and returns over the gears to the bottom of the crusher where it flows by gravity back into the conditioning tank. On the 51-in. and larger Hydrocone crushers, any oil which overflows the top of the eccentric is returned directly to the conditioning system without coming into contact with the gears.
On all but the 36 and 48-in. Hydrocone crushers, the countershaft bearings are of the anti-friction type with separate pool lubrication. Both ends of the countershaft bearing housing are sealed by garter spring-type oil seals to prevent dirt or other contaminants from entering the system.
Rather than use one eccentric throw under all operating conditions, Hydrocone crushers are designed to operate most efficiently with a predetermined ratio of eccentric throw to the crusher setting. By operating with an eccentric throw specifically selected for a given application, the most desirable crushing conditions are attained the most economical use of Mantalloy crushing surfaces reduced crusher maintenance a more cubical product.
The eccentric throw is controlled by a replaceable bronze sleeve in the cast steel eccentric. This sleeve, being a wearing part, can be renewed readily in the field. Also, should operating conditions change, the throw or motion of the crushing head can be changed accordingly.
Because of the large choice of eccentric throws available and the variety of crushing chambers that may be obtained a Hydrocone crusher may be selected that will fulfill the requirements of almost any secondary or tertiary crushing operation.
They may be used in the crushed stone industries to produce a premium cubical product in the mining industries to produce a grinding mill feed having a minimum of oversize, thereby reducing circulating loads and making open circuit crushing possible. The Hydrocone crusher is used in the cement industry to reduce cement clinker prior to finish grinding.
One of three general types of crushing chambers can be furnished for any size Hydrocone crusher to suit your specific needs. The selection of the proper chamber for a given application is dependent upon the feed size, the tonnage to be handled and the product desired. A crusher already in use can be readily converted to meet changing requirements, making this machine highly flexible in operation.
The Coarse crushing chamber affords the maximum feed opening for a given size crusher. Crushers fitted with a Coarse chamber can be choke fed, provided that product size material in the feed is removed.
The Coarse chamber has a relatively short parallel zone and is designed to be operated at a close side setting equal to or greater than the eccentric throw. For example, a crusher with a 3/8-in. the eccentric throw should be operated at a 3/8-in. (or more) close side setting, and therefore a -in. open side setting. Optimum capacity and product will result when operated under these conditions, as well as most economical wear on the mantalloy crushing surfaces.
One way dimension (slot size) of the feed to a crusher fitted with a Coarse chamber should not exceed two-thirds to 70 percent of the feed opening. The maximum feed size to an 848 Hydrocone crusher would therefore be about 5-in. one way dimension.
The use of a wobble plate feeder, furnished as optional equipment, is recommended if the feed size is relatively large, if the crusher is to be operated in closed circuit, or if the feed to the crusher is irregular.
If the Hydrocone crusher is operated with a Coarse crushing chamber, the product will average about 60% passing a square mesh testing sieve equal to the close side setting of the crusher. On certain materials which break very slabby, this percentage will be somewhat lower, and on cubically breaking material the percentage will be somewhat higher. As an average, approximately 90% of the product will pass a square mesh testing sieve corresponding to the open side setting, although this percentage frequently runs higher.
The Intermediate crushing chamber has a feed opening somewhat less than a coarse crushing chamber, but because of its longer parallel zone, is designed to be operated at a close side setting equal to or greater than half the eccentric throw. For example, with a -in. eccentric throw, the minimum close side setting would be 3/8-in.
Crushers fitted with this type of chamber can be choke fed, provided that product size material in the feed be removed ahead of the crusher. The one-way dimension or slot size of the feed to a crusher should not exceed approximately half the receiving opening. A 436 Hydrocone crusher with a 5/8-in. the eccentric throw could be operated at 5/16-in. close side setting and feed size should not exceed 2-in. one-way dimension.
The wobble plate feeder, although not required under most circumstances, is recommended if the feed is irregular, or if the crusher is operated as a re-crusher, at a relatively close setting, or in a closed circuit.
Because of the longer parallel zone in this crushing chamber, a somewhat greater percentage of the product will pass a square mesh testing sieve equal to the close side setting. This will usually average about 65 to 70%, with this percentage varying, depending on the material being crushed. Very frequently, 100% of the product will pass a square mesh testing sieve equal to the open side setting of the crusher.
The Fine crushing chamber has the longest parallel zone and therefore the smallest feed opening for any given size crusher. It can be operated at ratios of eccentric throw to close side setting of up to 4 to 1. With a -in. throw, for example, a 236 Hydro-cone crusher could be operated at 3/16-in. on the close side.
Because of their design, crushers with Fine crushing chambers cannot be choke fed but must be equipped with the wobble plate feeder. The maximum one-way dimension of the feed approaches the crusher feed opening. A 348 Hydrocone crusher can be fed with material up to 3-in. one-way dimension.
The Fine crushing chamber will give the highest percentage passing the close side setting of any of the chambers discussed here. The product will average approximately 75% passing a square mesh testing sieve equal to the close side setting. Because of the long parallel zone, the top size of the product will be only slightly larger than the close side setting of the crusher.
In addition to the three general types of crushing chambers described here, special chambers can be designed to meet varying operating requirements, giving the crusher even greater flexibility than can be obtained with these three main types.
For example, a special concave ring can be used in a 636 Hydro-cone crusher which will reduce the feed opening to 5 inches and permits a two to one ratio of eccentric throw to close side setting. Thus, the crusher can be furnished to fit the exact requirements of any application.
The following capacity table gives a complete range of all Hydrocone cone crusher capacities with varying crushing chambers and eccentric throws. This table shows the minimum recommended setting for any given eccentric throw, the recommended maximum one-way (slot size) dimension of the feed, and the maximum recommended horsepower for any eccentric throw.
Capacities given are based on crushing dry feed from which the product size material has been removed. The material must readily enter the feed opening and be evenly distributed around the crushing chamber. The table is based on material weighing 100 lb per cubic foot crushed. Any variation from this must be accounted for.
The curves on the following page can be used to approximate the screen analysis of the product from any given Hydrocone crusher. These curves are only approximations since the actual screen analysis of the product of a Hydrocone crusher will depend upon the nature of the material being crushed, the feed size and a number of other considerations which could not be taken into account in these curves. Within these limits, the curves should give fairly accurate estimates.
Note that the Coarse crushing chamber is represented as giving a product of which 60 percent will pass the close side setting, the Intermediate chamber 67 percent and the Fine chamber 75 percent passing the close side setting. These percentages are the averages of a large number of tests and some variations from these must be expected. If material breaks slabby the percentage with a coarse crushing chamber may be as low as 50 percent; if it breaks very cubically it might be as high as 70 percent, or even higher.
These curves have been prepared so that they can be used for any crushing chamber. To estimate the product of any Hydrocone crusher, it is necessary to know the type of crushing chamber used (Coarse, Intermediate or Fine), the close side setting and the eccentric throw.
If the crusher is a 636 Hydrocone crusher with a 3/8-in. throw and a 3/8-in. close side setting, the approximate screen analysis would be the curve that would pass through the 3/8-in. horizontal line and the vertical line representing the close side setting for the Coarse crushing chamber, which is the 60 percent passing line. If no curve passes through the precise point of intersection between the horizontal and vertical lines, an approximate curve can be sketched in which parallels the other curves. The same procedure can be used for approximating the products from any other crushing chamber.
Barite..170 Basalt.100 Cement Clinker.95 Coal..40-60 Coke.23-32 Glass..95 Granite100 Gravel.100 Gypsum..85 Iron Ore.125-150 Limestone..95-100 Magnesite.100 Perlite..95 Porphyry.100 Quartz..95 Sandstone..85 Slag..80 Taconite125 Talc..95 Trap Rock100
We canprovide testing to solve the most difficult crushing problems. Laboratory equipment makes it possible to measure the crushing strengths and characteristics of rock or ore samples accurately, and this data is used in the selection of a crusher of proper size and type.
Impact and batch tests are frequently sufficient to indicate the type and size crusher that will be the most economical for a particular application. However, batch testing is often followed by pilot plant tests to provide additional information about large-scale operations, or to observe rock or ore reduction under actual plant operating conditions.
Pilot plant tests duplicate a continuous crushing operation provide a practical demonstration of the commercial potential of the process on a pilot scale. Such tests are useful because they may disclose factors that affect the full-scale operation, favorably or otherwise, but which remain hidden in tests on limited samples.
All Laboratory tests are guided by modern scientific knowledge of crushing fundamentals and by ourinvaluable backlog of experience in engineering and building all types of crushing equipment for any crushing application.
In addition to the facilities for crushing tests, the Laboratory maintains complete batch and pilot mill facilities for use in investigating an entire process. Tests in grinding, sizing, concentrating, thickening, filtering, drying, and pyro- processing can be made.
cone crusher - an overview | sciencedirect topics
Cone crushers were originally designed and developed by Symons around 1920 and therefore are often described as Symons cone crushers. As the mechanisms of crushing in these crushers are similar to gyratory crushers their designs are similar, but in this case the spindle is supported at the bottom of the gyrating cone instead of being suspended as in larger gyratory crushers. Figure5.3 is a schematic diagram of a cone crusher.
The breaking head gyrates inside an inverted truncated cone. These crushers are designed so that the head-to-depth ratio is larger than the standard gyratory crusher and the cone angles are much flatter and the slope of the mantle and the concaves are parallel to each other. The flatter cone angles help to retain the particles longer between the crushing surfaces and therefore produce much finer particles. To prevent damage to the crushing surfaces, the concave or shell of the crushers is held in place by strong springs or hydraulics which yield to permit uncrushable tramp material to pass through.
The secondary crushers are designated as Standard cone crushers having stepped liners and tertiary Short Head cone crushers, which have smoother crushing faces and steeper cone angles of the breaking head. The approximate distance of the annular space at the discharge end designates the size of the cone crushers. A brief summary of the design characteristics is given in Table5.4 for crusher operation in open-circuit and closed-circuit situations.
The Standard cone crushers are for normal use. The Short Head cone crushers are designed for tertiary or quaternary crushing where finer product is required. These crushers are invariably operated in closed circuit. The final product sizes are fine, medium or coarse depending on the closed set spacing, the configuration of the crushing chamber and classifier performance, which is always installed in parallel.
For finer product sizes, i.e., less than 6mm, special cone crushers known as Gyradisc crushers are available. The operation is similar to the standard cone crushers, except that the size reduction is caused more by attrition than by impact . The reduction ratio is around 8:1 and as the product size is relatively small the feed size is limited to less than 50mm with a nip angle between 25 and 30. The Gyradisc crushers have head diameters from around 900 to 2100mm. These crushers are always operated under choke feed conditions. The feed size is less than 50mm and therefore the product size is usually less than 69mm.
Maintenance of the wear components in both gyratory and cone crushers is one of the major operating costs. Wear monitoring is possible using a Faro Arm (Figure 6.10), which is a portable coordinate measurement machine. Ultrasonic profiling is also used. A more advanced system using a laser scanner tool to profile the mantle and concave produces a 3D image of the crushing chamber (Erikson, 2014). Some of the benefits of the liner profiling systems include: improved prediction of mantle and concave liner replacement; identifying asymmetric and high wear areas; measurement of open and closed side settings; and quantifying wear life with competing liner alloys.
Various types of rock fracture occur at different loading rates. For example, rock destruction by a boring machine, a jaw or cone crusher, and a grinding roll machine are within the extent of low loading rates, often called quasistatic loading condition. On the contrary, rock fracture in percussive drilling and blasting happens under high loading rates, usually named dynamic loading condition. This chapter presents loading rate effects on rock strengths, rock fracture toughness, rock fragmentation, energy partitioning, and energy efficiency. Finally, some of engineering applications of loading rate effects are discussed.
In Chapter4, we have already seen the mechanism of crushing in a jaw crusher. Considering it further we can see that when a single particle, marked 1 in Figure11.5a, is nipped between the jaws of a jaw crusher the particle breaks producing fragments, marked 2 and 3 in Figure11.5b. Particles marked 2 are larger than the open set on the crusher and are retained for crushing on the next cycle. Particles of size 3, smaller than the open set of the crusher, can travel down faster and occupy or pass through the lower portion of the crusher while the jaw swings away. In the next cycle the probability of the larger particles (size 2) breaking is greater than the smaller sized particle 3. In the following cycle, therefore, particle size 2 is likely to disappear preferentially and the progeny joins the rest of thesmaller size particles indicated as 3 in Figure11.5c. In the figures, the position of the crushed particles that do not exist after comminution is shaded white (merely to indicate the positions they had occupied before comminution). Particles that have been crushed and travelled down are shown in grey. The figure clearly illustrates the mechanism of crushing and the classification that takes place within the breaking zone during the process, as also illustrated in Figure11.4. This type of breakage process occurs within a jaw crusher, gyratory crusher, roll crusher and rod mills. Equation (11.19) then is a description of the crusher model.
In practice however, instead of a single particle, the feed consists of a combination of particles present in several size fractions. The probability of breakage of some relatively larger sized particles in preference to smaller particles has already been mentioned. For completeness, the curve for the probability of breakage of different particle sizes is again shown in Figure11.6. It can be seen that for particle sizes ranging between 0 K1, the probability of breakage is zero as the particles are too small. Sizes between K1 and K2 are assumed to break according a parabolic curve. Particle sizes greater than K2 would always be broken. According to Whiten , this classification function Ci, representing the probability of a particle of size di entering the breakage stage of the crusher, may be expressed as
The classification function can be readily expressed as a lower triangular matrix [1,16] where the elements represent the proportion of particles in each size interval that would break. To construct a mathematical model to relate product and feed sizes where the crusher feed contains a proportion of particles which are smaller than the closed set and hence will pass through the crusher with little or no breakage, Whiten  advocated a crusher model as shown in Figure11.7.
The considerations in Figure11.7 are similar to the general model for size reduction illustrated in Figure11.4 except in this case the feed is initially directed to a classifier, which eliminates particle sizes less than K1. The coarse classifier product then enters the crushing zone. Thus, only the crushable larger size material enters the crusher zone. The crusher product iscombined with the main feed and the process repeated. The undersize from the classifier is the product.
While considering the above aspects of a model of crushers, it is important to remember that the size reduction process in commercial operations is continuous over long periods of time. In actual practice, therefore, the same operation is repeated over long periods, so the general expression for product size must take this factor into account. Hence, a parameter v is introduced to represent the number of cycles of operation. As all cycles are assumed identical the general model given in Equation (11.31) should, therefore, be modified as
Multiple vectors B C written in matrix form:BC=0.580000.200.60000.120.180.6100.040.090.20.571.000000.700000.4500000=0581+00+00+000.580+00.7+00+000580+00+00.45+000.580+00+00+000.21+0.60+00+000.20+0.60.7+00+000.20+0.60+00.45+000.20+0.60+00+000.121+0.180+0.610+000.120+0.180.7+0.610+000.120+0.180+0.610.45+000.120+0.180+0.610+000.041+0.090+0.20+0.5700.040+0.090.7+0.20+0.5700.040+0.090+0.20.45+0.5700.040+0.090+0.20+0.570=0.580000.20.42000.120.1260.274500.040.0630.090
Now determine (I B C) and (I C)(IBC)=10.5800000000.210.42000000.1200.12610.27450000.0400.06300.0910=0.420000.20.58000.120.1260.725500.040.0630.091and(IC)=000000.300000.5500001
Now find the values of x1, x2, x3 and x4 as(0.42x1)+(0x2)+(0x3)+(0x4)=10,thereforex1=23.8(0.2x1)+(0.58x2)+(0x3)+(0x4)=33,thereforex2=65.1(0.12x1)+(0.126x2)+(0.7255x3)+(0x4)=32,thereforex3=59.4(0.04x1)+(0.063x2)+(0.09x3)+(1x4)=20,thereforex4=30.4
In this process, mined quartz is crushed into pieces using crushing/smashing equipment. Generally, the quartz smashing plant comprises a jaw smasher, a cone crusher, an impact smasher, a vibrating feeder, a vibrating screen, and a belt conveyor. The vibrating feeder feeds materials to the jaw crusher for essential crushing. At that point, the yielding material from the jaw crusher is moved to a cone crusher for optional crushing, and afterward to effect for the third time crushing. As part of next process, the squashed quartz is moved to a vibrating screen for sieving to various sizes.
Crushers are widely used as a primary stage to produce the particulate product finer than about 50100mm. They are classified as jaw, gyratory, and cone crushers based on compression, cutter mill based on shear, and hammer crusher based on impact.
A jaw crusher consists essentially of two crushing plates, inclined to each other forming a horizontal opening by their lower borders. Material is crushed between a fixed and a movable plate by reciprocating pressure until the crushed product becomes small enough to pass through the gap between the crushing plates. Jaw crushers find a wide application for brittle materials. For example, they are used for comminution of porous copper cake. A Fritsch jaw crusher with maximal feed size 95mm, final fineness (depends on gap setting) 0.315mm, and maximal continuous throughput 250Kg/h is shown in Fig. 2.8.
A gyratory crusher includes a solid cone set on a revolving shaft and placed within a hollow body, which has conical or vertical sloping sides. Material is crushed when the crushing surfaces approach each other and the crushed products fall through the discharging opening.
Hammer crushers are used either as a one-step primary crusher or as a secondary crusher for products from a primary crusher. They are widely used for crushing hard metal scrap for different hard metal recycling processes. Pivoted hammers are pendulous, mounted on the horizontal axes symmetrically located along the perimeter of a rotor. Crushing takes place by the impact of material pieces with the high speed moving hammers and by contact with breaker plates. A cylindrical grating or screen is placed beneath the rotor. Materials are reduced to a size small enough to pass through the openings of the grating or screen. The size of the product can be regulated by changing the spacing of the grate bars or the opening of the screen.
The feature of the hammer crushers is the appearance of elevated pressure of air in the discharging unit of the crusher and underpressure in the zone around the shaft close to the inside surface of the body side walls. Thus, the hammer crushers also act as high-pressure, forced-draught fans. This may lead to environmental pollution and product losses in fine powder fractions. A design for a hammer crusher (Fig. 2.9) essentially allows a decrease of the elevated pressure of air in the crusher discharging unit . The A-zone beneath the screen is communicated through the hollow ribs and openings in the body side walls with the B-zone around the shaft close to the inside surface of body side walls. As a result, the circulation of suspended matter in the gas between A and B zones is established and the high pressure of air in the discharging unit of crusher is reduced.
Crushers are widely used as a primary stage to produce the particulate product finer than about 50100 mm in size. They are classified as jaw, gyratory and cone crushers based on compression, cutter mill based on shear and hammer crusher based on impact.
A jaw crusher consists essentially of two crushing plates, inclined to each other forming a horizontal opening by their lower borders. Material is crushed between a fixed and a movable plate by reciprocating pressure until the crushed product becomes small enough to pass through the gap between the crushing plates. Jaw crushers find a wide application for brittle materials. For example, they are used for comminution of porous copper cake.
A gyratory crusher includes a solid cone set on a revolving shaft and placed within a hollow body, which has conical or vertical sloping sides. Material is crushed when the crushing surfaces approach each other and the crushed products fall through the discharging opening.
Hammer crushers are used either as a one-step primary crusher or as a secondary crusher for products from a primary crusher. They are widely used for crushing of hard metal scrap for different hard metal recycling processes.
Pivoted hammers are pendulous, mounted on the horizontal axes symmetrically located along the perimeter of a rotor and crushing takes place by the impact of material pieces with the high speed moving hammers and by contact with breaker plates. A cylindrical grating or screen is placed beneath the rotor. Materials are reduced to a size small enough pass through the openings of the grating or screen. The size of product can be regulated by changing the spacing of the grate bars or the opening of the screen.
The feature of the hammer crushers is the appearance of elevated pressure of air in the discharging unit of the crusher and underpressure in the zone around of the shaft close to the inside surface of the body side walls. Thus, the hammer crushers also act as high-pressure forced-draught fans. This may lead to environmental pollution and product losses in fine powder fractions.
A design for a hammer crusher (Figure 2.6) allows essentially a decrease of the elevated pressure of air in the crusher discharging unit . The A-zone beneath the screen is communicated through the hollow ribs and openings in the body side walls with the B-zone around the shaft close to the inside surface of body side walls. As a result, circulation of suspended matter in the gas between A- and B-zones is established and high pressure of air in the discharging unit of crusher is reduced.
For a particular operation where the ore size is known, it is necessary to estimate the diameter of rolls required for a specific degree of size reduction. To estimate the roll diameter, it is convenient to assume that the particle to be crushed is spherical and roll surfaces are smooth. Figure6.2 shows a spherical particle about to enter the crushing zone of a roll crusher and is about to be nipped. For rolls that have equal radius and length, tangents drawn at the point of contact of the particle and the two rolls meet to form the nip angle (2). From simple geometry it can be seen that for a particle of size d, nipped between two rolls of radius R:
Equation (6.2) indicates that to estimate the radius R of the roll, the nip angle is required. The nip angle on its part will depend on the coefficient of friction, , between the roll surface and the particle surface. To estimate the coefficient of friction, consider a compressive force, F, exerted by the rolls on the particle just prior to crushing, operating normal to the roll surface, at the point of contact, and the frictional force between the roll and particle acting along a tangent to the roll surface at the point of contact. The frictional force is a function of the compressive force F and is given by the expression, F. If we consider the vertical components of these forces, and neglect the force due to gravity, then it can be seen that at the point of contact (Figure6.2) for the particle to be just nipped by the rolls, the equilibrium conditions apply where
As the friction coefficient is roughly between 0.20 and 0.30, the nip angle has a value of about 1117. However, when the rolls are in motion the friction characteristics between the ore particle will depend on the speed of the rolls. According to Wills , the speed is related to the kinetic coefficient of friction of the revolving rolls, K, by the relation
Equation (6.4) shows that the K values decrease slightly with increasing speed. For speed changes between 150 and 200rpm and ranging from 0.2 to 0.3, the value of K changes between 0.037 and 0.056. Equation (6.2) can be used to select the size of roll crushers for specific requirements. For nip angles between 11 and 17, Figure6.3 indicates the roll sizes calculated for different maximum feed sizes for a set of 12.5mm.
The maximum particle size of a limestone sample received from a cone crusher was 2.5cm. It was required to further crush it down to 0.5cm in a roll crusher with smooth rolls. The friction coefficient between steel and particles was 0.25, if the rolls were set at 6.3mm and both revolved to crush, estimate the diameter of the rolls.
It is generally observed that rolls can accept particles sizes larger than the calculated diameters and larger nip angles when the rate of entry of feed in crushing zone is comparable with the speed of rotation of the rolls.
Jaw crushers are mainly used as primary crushers to produce material that can be transported by belt conveyors to the next crushing stages. The crushing process takes place between a fixed jaw and a moving jaw. The moving jaw dies are mounted on a pitman that has a reciprocating motion. The jaw dies must be replaced regularly due to wear. Figure 8.1 shows two basic types of jaw crushers: single toggle and double toggle. In the single toggle jaw crusher, an eccentric shaft is installed on the top of the crusher. Shaft rotation causes, along with the toggle plate, a compressive action of the moving jaw. A double toggle crusher has, basically, two shafts and two toggle plates. The first shaft is a pivoting shaft on the top of the crusher, while the other is an eccentric shaft that drives both toggle plates. The moving jaw has a pure reciprocating motion toward the fixed jaw. The crushing force is doubled compared to single toggle crushers and it can crush very hard ores. The jaw crusher is reliable and robust and therefore quite popular in primary crushing plants. The capacity of jaw crushers is limited, so they are typically used for small or medium projects up to approximately 1600t/h. Vibrating screens are often placed ahead of the jaw crushers to remove undersize material, or scalp the feed, and thereby increase the capacity of the primary crushing operation.
Both cone and gyratory crushers, as shown in Figure 8.2, have an oscillating shaft. The material is crushed in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly. An eccentric shaft rotated by a gear and pinion produces the oscillating movement of the main shaft. The eccentricity causes the cone head to oscillate between the open side setting (o.s.s.) and closed side setting (c.s.s.). In addition to c.s.s., eccentricity is one of the major factors that determine the capacity of gyratory and cone crushers. The fragmentation of the material results from the continuous compression that takes place between the mantle and bowl liners. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners. This is also called interparticle crushing. The gyratory crushers are equipped with a hydraulic setting adjustment system, which adjusts c.s.s. and thus affects product size distribution. Depending on cone type, the c.s.s. setting can be adjusted in two ways. The first way is by rotating the bowl against the threads so that the vertical position of the outer wear part (concave) is changed. One advantage of this adjustment type is that the liners wear more evenly. Another principle of setting adjustment is by lifting/lowering the main shaft. An advantage of this is that adjustment can be done continuously under load. To optimize operating costs and improve the product shape, as a rule of thumb, it is recommended that cones always be choke-fed, meaning that the cavity should be as full of rock material as possible. This can be easily achieved by using a stockpile or a silo to regulate the inevitable fluctuation of feed material flow. Level monitoring devices that detect the maximum and minimum levels of the material are used to start and stop the feed of material to the crusher as needed.
Primary gyratory crushers are used in the primary crushing stage. Compared to the cone type crusher, a gyratory crusher has a crushing chamber designed to accept feed material of a relatively large size in relation to the mantle diameter. The primary gyratory crusher offers high capacity thanks to its generously dimensioned circular discharge opening (which provides a much larger area than that of the jaw crusher) and the continuous operation principle (while the reciprocating motion of the jaw crusher produces a batch crushing action). The gyratory crusher has capacities starting from 1200 to above 5000t/h. To have a feed opening corresponding to that of a jaw crusher, the primary gyratory crusher must be much taller and heavier. Therefore, primary gyratories require quite a massive foundation.
The cone crusher is a modified gyratory crusher. The essential difference is that the shorter spindle of the cone crusher is not suspended, as in the gyratory, but is supported in a curved, universal bearing below the gyratory head or cone (Figure 8.2). Power is transmitted from the source to the countershaft to a V-belt or direct drive. The countershaft has a bevel pinion pressed and keyed to it and drives the gear on the eccentric assembly. The eccentric assembly has a tapered, offset bore and provides the means whereby the head and main shaft follow an eccentric path during each cycle of rotation. Cone crushers are used for intermediate and fine crushing after primary crushing. The key factor for the performance of a cone type secondary crusher is the profile of the crushing chamber or cavity. Therefore, there is normally a range of standard cavities available for each crusher, to allow selection of the appropriate cavity for the feed material in question.
The main task of renovation construction waste handling is the separation of lightweight impurities and construction waste. The rolling crusher with opposite rollers is capable of crushing the brittle debris and compressing the lightweight materials by the low-speed and high-pressure extrusion of the two opposite rollers. As the gap between the opposite rollers, rotation speed, and pressure are all adjustable, materials of different scales in renovation construction waste can be handled.
The concrete C&D waste recycling process of impact crusher+cone crusher+hoop-roller grinder is also capable of handling brick waste. In general, the secondary crushing using the cone crusher in this process with an enclosed crusher is a process of multicrushing, and the water content of waste will become an important affecting factor. The wet waste will be adhered on the wall of the grinding chamber, and the crushing efficiency and waste discharging will be affected. When the climate is humid, only coarse impact crushing is performed and in this case the crushed materials are used for roadbase materials. Otherwise, three consecutive crushings are performed and the recycled coarse aggregate, fine aggregate, and powder materials are collected, respectively.
The brick and concrete C&D waste recycling process of impact crusher+rolling crusher+hoop-roller grinder is also capable of handling the concrete waste. In this case, the water content of waste will not be an important affecting factor. This process is suitable in the regions with wet climates.
The renovation C&D waste recycling process of rolling crusher (coarse/primary crushing)+rolling crusher (intermediate/secondary crushing)+rolling crusher (fine/tertiary crushing) is also capable of handling the two kinds of waste discussed earlier. The particle size of debris is crushed less than 20mm and the lightweight materials are compressed, and they are separated using the drum sieve. The energy consumption is low in this process; however, the shape of products is not good (usually flat and with cracks). There is no problem in roadbase material and raw materials of prefabricated product production. But molders (the rotation of rotors in crusher is used to polish the edge and corner) should be used for premixed concrete and mortar production.