cement plant primary crusher design

primary crushing

primary crushing

The term primary crusher, by definition, might embrace any type and size of crushing machine. The term implies that at least two stages of crushing are involved, but in many cases the machine which performs the function of initial crusher is the only crusher in the plant. The factors influencing the selection of a crusher for this service are much the same, regardless of how many crushing stages there are in the flowsheet; therefore, the term primary crusher, by common usage, is applied to the crusher which takes up the job of reduction where the blasting operations leave off. Selecting the right type and size of primary crusher is a problem of prime importance in the designing of a crushing plant of any nature and size. Usually this machine is the largest and most expensive single item of equipment in the plant; a mistake in the choice can only be remedied fully by replacement; and, because the entire primary crusher-house arrangement is generally tailored.to fit the crusher, such .replacement is almost always a costly procedure. While personal favouritism toward some particular type of crusher may safely be allowed to swing a close decision, it should never blind the engineer or operator to the merits of other types, nor to the limitations of his favorite. The following factors all have a more or less important bearing upon the choice of the primary crusher.

The first three of these factors will almost always be ascertainable at least to a close approximation before the matter of crusher choice is taken up. Sometimes, as when a new crushing plant, or a new primary crusher set-up, is to be installed at an existing operation the last three factors will be pre-established. Otherwise, it is sound practice to consider them as a part of the problem of crusher selection. The primary crushing setup is closely linked to the quarrying or mining operation, and it is only by careful adjustment of all equipment selections to the general plan of operation that optimum operating results may be realized.

While it is convenient to discuss the influence of these several factors separately, it is well to keep in mind that they are more or less closely interlocked, and that a change in one of them may necessitate altering one or more of the others.In addition to the factors listed there are usually a few which are peculiar to each individual problem such as labor costs and so on. Any plant design problem is an economic as well as an engineering one. We are concerned here ,chiefly with the engineering phases.

Characteristics of the material to be crushed include the geological classification of the rock, its physical structure, its chemical analysis (at least so far as abrasive constituents are concerned), and at least a qualitative evaluation of its resistance to crushing that is, whether soft, medium, hard, or very hard and tough. Frequently such information may be obtained from contiguous deposits which are being operated; sometimes the values must be arrived at by laboratory tests. It is never safe to make blanket assumptions, even on such a material as limestone, which can sometimes prove to be quite tough, as well as to contain significant amounts of abrasive silica.

Physical, or geological, structure of the deposit often has an important bearing upon selection of size or type, or both. If the deposit is thinly stratified, as, for example, many deposits of limestone are, it is safe to assume that the rock can be blasted economically into a condition for feeding a gyratory crusher of medium proportions, or, if other characteristics are suitable, a sledging roll crusher, such as the Fairmount machine. If, on the other hand, the formation is of massive character, again, some limestones are, the gyratory crusher might be ruled out in favour of the jaw crusher, unless the operation is of sufficient magnitude to warrant installation of a large size of gyratory. The proposed quarrying or mining procedure will of course have some bearing upon the size of rock to go to the crusher, regardless of its physical structure, as will be pointed out in further detail later on. If the chemical analysis of the rock discloses that substantial amounts of free silica or any other abrasive are present, crushers of the sledging roll or hammermill types are usually ruled out unless the material is extremely soft and friable. There are occasional speciality applications where such machines may be indicated for crushing abrasive materials, but from the standpoint of, economical operation their use for such service is rarely justifiable. The same restriction holds true for hard and tough materials. For such rock or ore our choice of a primary crusher is restricted to the gyratory and jaw types except, again, for the occasional specialty application where economy in maintenance may be sacrificed for other considerations such as lower first cost, or space restrictions.

The significance of this factor is so obvious that it sometimes does not receive quite as much thought as it should. From the standpoint of minimum requirement, it is of course closely tied up with product size, or crusher setting. But the primary crusher can seldom be chosen solely on the basis of capacity; it should never be selected with a view to just meeting the average capacity required to feed the rest of the crushing plant. Just how much the rated capacity of the primary crusher (at the required discharge setting) should exceed the average capacity of the plant depends upon how uniformly the crusher will be fed; or to put it more definitely, what percentage of the total operating period the crusher will operate at full rated capacity. The answer to this is not always an easy one to predetermine, as it may depend upon several details of plant design and quarry operation.

In the average quarry operation, the only surge capacity between the quarry and the primary crusher consists of whatever quantity of rock may be, at the moment, loaded in cars or trucks, and usually this is not large. For that reason, any operating delays occurring in loading, transportation or primary crushing quickly affect all three of them, with the result that the feed to the balance of the crushing plant is cut-off until the trouble is rectified. If the plant as a whole is to maintain its rated average output, these departments must be capable of making up for such interruptions, and they can only do this if they have reserve capacity over and above the average requirement.

Such interruptions to continuous production are not uncommon in the primary crusher house; they may assume serious proportions if the crusher receiving opening is not large enough for the material it is expected to handle, and the largest crushers of any type will occasionally bridge or block. Crusher capacity tables are predicated upon a continuous feed of rock of a size that will readily enter the crushing chamber; it is obvious therefore that a crusher whose rating just equals the average plant requirement would have no reserve to compensate for the conditions we have outlined. For the average quarry operation this reserve should be not less than 25 percent, and preferably about 50 percent.

Since the minimum dimension of the feed opening of a crusher determines the maximum size of lump that it can take, the choice of a primary breaker is dependent as much on the size of the feed as on the hourly tonnage. Thus a 15 in. by 24 in. jaw crusher would be suitable for a small mine hoisting 300 tons in eight hours from underground workings from which lumps larger than 14 in. are not likely to be received. A crusher of these dimensions will break 40 tons per hour to 2-in. size with a power consumption of 30 h.p. On the other hand, a 14-in. gyratory crusher, working as it should at full capacity, will crush 100 tons per hour to the same size with a power consumption of 70 h.p. ; at 40 tons per hour, it would still require about 50 h.p. The jaw crusher is evidently the more economical machine in this case, and its first cost is only about half that of the gyratory crusher.

If the capacity of the primary breaker is required to be 100 tons per hour or over, a gyratory crusher is likely to be more economical than the other type, since it costs no more than a jaw crusher of similar capacity and consumes less power. Moreover, the difference in power consumption between the two types of machine is greater in practice than in theory; this is due to the fact that, since the gyratory crusher can be choke-fed, it is easier to keep it running at maximum efficiency.

The position is different when mining is done by power-shovel. The maximum size of lump delivered to the crushing plant is much larger than from underground workings, and it is not advisable to use a bin for the storage of the ore on account of the difficulty of handling very large lumps through a bin gate. Consequently the ore is generally sent direct to a preliminary breaker which reduces it to a size suitable for feeding the normal primary breaker. The first machine is often of the jaw type, although this depends on the circumstances. Suppose, to take an instance, that the shovels were equipped with 3-yd. dippers and that 2,000 tons were being mined per day. A 48 in. by 60 in. jaw crusher is more than large enough to take the maximum size of lump that could get through the jaws of the dipper, and it would break the whole days output to 6-in. size in eight hours with a power consumption of under 200 h.p. On the other hand, a 42-in. gyratory crusher, which is the smallest that could be installed with safety, has a maximum capacity of over 5,000 tons in eight hours with a power consumption of about 275 h.p. The jaw breaker would therefore be the more economical machine. It could, if necessary, be installed near the scene of mining operations, and would be set to deliver a 6- or 8-in. product, which could be conveniently transported to the crushing section of the flotation plant where it would be fed through the coarse ore bin to the primary breaker in the ordinary way.

The choice of a primary breaker is an individual problem for every installation. The type of mining and the regularity, size, and rate atwhich the ore is delivered, are the main determining factors, but all local conditions should be taken into consideration before a decision is made.

primary crusher - an overview | sciencedirect topics

primary crusher - an overview | sciencedirect topics

The primary crusher is located in the quarry and consists of a McLanahan 48x72 Shale King Crusher rated at 1,000 TPH (Tons Per Hour). The driving flywheel has a diameter of 2.5 meters and is motor driven through six v-belts. The capacity of the primary crusher had to be increased to 1,250 TPH to produce enough material to serve the wet and both dry lines in the plant. To enable the crusher to operate at the higher capacity, the manufacturer recommended grooving the flywheel for two additional v-belts. To avoid the costs of disassembling, shipping and reassembling, Nesher performed the machining in-place. The operation was performed using portable tools and an auxiliary motor that turned the flywheel for machining the new grooves.

Roll crushers are generally not used as primary crushers for hard ores. Even for softer ores, such as chalcocite and chalcopyrite, they have been used as secondary crushers. Choke feeding is not advisable as it tends to produce particles of irregular size. Both open and closed circuit crushing is employed. For close circuit the product is screened with a mesh size much less than the set.

Figure6.4 is a typical set-up where ores crushed in primary and secondary crushers are further reduced in size by a rough roll crusher in an open circuit followed by finer size reduction in a closed circuit by a roll crusher. Such circuits are chosen as the feed size to standard roll crushers normally does not exceed 50mm.

Secondary coal crusher: Used when the coal coming from the supplier is large enough to be handled by a single crusher. The primary crusher converts the feed size to one that is acceptable to the secondary crusher.

Detail descriptions of designs are given of large gyratory crushers that are used as primary crushers to reduce the size of large run-of-mine ore pieces to acceptable sizes. Descriptions of secondary and tertiary cone crushers that usually follow gyratory crushers are also given in detail. The practical method of operation of each type of gyratory crusher is indicated and the various methods of computing operating variables such as speed of gyration, capacities and power consumption given are prescribed by different authors. The methods of calculations are illustrated to obtain optimum operating conditions of different variables of each type using practical examples.

Shale, a low-moisture content soft rock, is quarried, transferred to blending stockpiles before it is reduced by primary crushers and dry-milled to a powder of less than 250m. This powder is homogenized and stored ready for pelletization in manner similar to that used for making aggregate from PFA except that no fuel is added. However, after the pellets have been produced to the appropriate size, which depends on the expansion required, they are compacted and coated with finely powdered limestone. The resulting pellets are spherical with a green strength sufficient for conveying to a three-stage kiln consisting of a pre-heater, expander and cooler. Unlike other aggregates produced from argillaceous materials, the feedstock is reduced to a powder and then reconstituted to form a pellet of predetermined size. The expansion (bloating) is controlled during kilning to produce an aggregate of the required particle density. Different particle densities are produced by controlling the firing temperature and the rotational speed of the kiln. The coating of limestone applied to the green pellet increases the degree of surface vitrification which results in a particle of low permeability. This product gives versatility to the designer for pre-selecting an appropriate concrete density. As Figure7.6 shows, while the particle shape and surface texture of the aggregate remain essentially the same, the internal porosity can be varied according to the bloating required for the specified density.

Mined crushed stone is loaded into trucks or onto conveyors and transported to the processing facility. The broken stone is dumped into a primary crusher where the large rock fragments are broken into smaller sizes. Crushing to the proper size usually occurs in stages because rapid size reduction, accomplished by applying large forces, commonly results in the production of excessive fines (Rollings and Rollings 1996). After primary crushing, the material is run through one or more secondary crushers. These crushers use compression, impact, or shear to break the rock into smaller pieces. The material is screened after each crushing cycle to separate properly sized particles (throughs) from those needing additional crushing (overs). Additional washing, screening, or other processing may be required to remove undesirable material. The material is then stockpiled awaiting shipment.

After mining, sand and gravel may be used as is, which is called bank-run or pit-run gravel, or it may be further processed. The procedures for processing sand and gravel are similar to those for processing crushed stone. The amount of processing depends on the characteristics of the sand and gravel deposit and the intended use. If the gravel deposits contain very large cobbles or boulders, that material may be run through a primary crusher. The material may be run through one or more secondary crushers, then washed, screened, or further processed to remove undesirable material. The material is then stockpiled awaiting shipment.

The design of belt and apron feeders is fairly standardized, and most of the producing companies use pre-defined models and calculation methods to get short delivery times with a low-cost approach. The main features of the apron and belt feeders are:

Although the conveying devices are reasonably well defined and standardized, there is still room for improvement of the overall plant layout and construction, e.g. crushing plant, silo discharge system, train unloading system, etc. One of the most obvious ways to improve the overall design of such systems is to develop a better understanding of the equipment itself. Today, most OEMs want to be involved in the process of seeking the solution rather than only the supply of the equipment. This will enable the market to make use of the expertise of the equipment supplier and, at the same time, use their knowledge base for developing a wider scope, including other aspects such as silo design, hopper design, electrical and hydraulic issues, etc.

Highland Valley copper mine experienced a decline in mill throughput after implementing larger holes for blasting, which resulted in coarser fragmentation and a coarser product from the primary crushers [24]. In the quarry at Vrsi, as drilling geometry decreased from 3.0m4.5m to 2.9m3.0m while other parameters such as borehole sizes were constant, a significant savings of 14% was achieved for the quarry [25]. Due to a mine-to-mill implementation at the Red Dog Mine, the mine achieved savings exceeding $30 million per year [26]. This indicates that, at least in some ores, improved internal fragmentation carries through the crushing and grinding circuits. The mine-to-mill project in the same mine identified further benefit, specifically the marked reduction in SAG feed size and throughput variability [5]. A second but important benefit was the reduced wear in the gyratory crusher, resulting in a significantly longer period between relines. When electronic detonators with very short delay time were applied in the Chuquicamata open pit copper mine, the fragmentation was markedly improved [27]. In the Aitik copper mine a raised specific charge from 0.9 to 1.3kg/m3 gave rise to an increase in the throughput by nearly 7% due to more fines produced and shorter grinding time achieved [28].

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.

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 [5]. 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.

design objectives of crushing plant from redstar staff - hxjq mining machine manufacturer

design objectives of crushing plant from redstar staff - hxjq mining machine manufacturer

Henan Hongxing Mining Machinery Co., Ltd is a joint-stock mining machinery manufacturing enterprise integrated in scientific research, production and marketing. Hongxing company will tell you the design plan of a crushing plant.

The fundamental goal for the design of a crushing plant is an installation that meets the required production requirements, operates at competitive cost, complies with today's tough environmental regulations, and can be built at a reasonable price despite the rising costs of equipment, energy and construction labor. The following industry trends must be taken into account:

Electronic control of crusher discharge opening and feed rate. With adjustment of a crusher's discharge opening, as the production continues through an on-line coarse size analysis of the crushed product (digital image analyses). Dance, A. 2001)

There are three main steps in designing a good crushing plant: process design, equipment selection, and layout. The first two are dictated by production requirements and design parameters, but the layout can reflect the input, preferences and operational experience of a number of parties. These can include the owner's engineering staff, safety personnel, operations and maintenance personnel, equipment manufacturers, and the engineering consultant. Ideally, the consultant combines his knowledge and experience with an understanding of all parties' needs, to provide a balanced, workable, safe and economic plant design.

stone crushing plant - automatic stone crusher plant | agico

stone crushing plant - automatic stone crusher plant | agico

The stone crushing plant is a kind of special plant for building stone production. AGICO stone crushing production line is a project launched by our company after several years of development and research. Compared with the traditional crushing model, it saves a lot of energy and labor. At the same time, it has the characteristics of reasonable design, reliable operation, convenient operation, high efficiency, and energy-saving. We provide the equipment and design the production line according to the customers specific needs. AGICO has the ability to provide you with the best technical support.

The stone crushing plant manufactured by AGICO mainly consists of a vibrating feeder, jaw crusher, impact crusher, vibrating screen, belt conveyorcentralized electronic control system, and other equipment. The designed output is generally 30-350 tons per hour. According to different technological requirements, we can also equip the dust collector, cone crusher, or other cement crushersto meet the different production needs of customers.

In the production process, large stones are evenly sent to the jaw crusher by a vibrating feeder for coarse crushing (primary crushing), then sent to the impact crusher by the belt conveyor for secondary crushing. After that, all the stones will be divided into three different sizes on the vibrating screen. The large-sized stone which beyond the specification will be sent back to the impact crusher by the belt conveyor for re-crushing, and then sent to the vibrating screen again forming closed-circuit multiple cycles until the completion of production.

Our stone crushing plant has a high degree of automation. Except for equipment start-up, shutdown, and daily maintenance, the whole plant requires almost no manual operation. Besides, our equipment is easy to maintain. The wearing parts are made of high-strength wear-resistant materials, with a small loss, and long service life, which can bring considerable economic benefits to customers.

This plant has been successfully applied in the crushing processing of limestone, basalt, granite, pebble, and other rocks. The product quality completely reaches the GB14685-2001 standard, which can be regarded as aggregate for high-grade highway, railway, water conservancy, concrete mixing plant, and other industries.

The performance of the stone crushing plant can be judged according to the product quality. There are mainly two quality indexes of crushed stone: the ratio of elongated and flaky particles and the content of the powder. If these two indicators exceed the specified range, the product quality is unqualified and cannot be used in large projects. The quality of crushed stones produced by our crushing plant is in line with the relevant standards. The content of elongated and flaky particles and powder in the crushed stone is very small and the product particle size is uniform, the particle shape is good with no internal crack, the compressive strength is high, and the granular composition is reasonable.

AGICO has large manufacturing workshops and professional processing equipment to ensure the fast and high-quality production of related equipment in the automatic stone crusher plant. In addition, we have more than 20 years of production and sales experience, the products are exported to all over the world, therefore, we can ensure the timely and safe delivery, reducing the time cost of customers.

AGICO provides EPC turnkey projects. It not only includes the manufacture of various specialized equipment in the stone crushing plant but also includes the plant design, onsite installation, real-time commissioning, equipment operation training and usual spare parts service.

Customization is the most basic service our company provides for each customer. We will design the production lines and choose equipment according to customers specific needs on stone specification, output, application, construction environment, etc. Every customer will get their satisfied stone crushing production line here.

Jaw crusher is mainly used for raw material coarse and medium crushing in the cement plant and crushing plant. According to the width of the feed port, it can be divided into three types: large type (feed port is larger than 600mm), the medium type (feed port is between 300-600mm), and small type (feed port is smaller than 300mm). It features small noise, small dust, simple structure, low cost, which is the idol choice for raw material crushing.

Impact crusher can handle the material with side length between 100-500mm and the resistance pressure no higher than 350mpa. It has the advantages of large crushing ratio, low power consumption and long service life. Its discharge size is adjustable, and after crushing, the material presents a cubic shape. As a crushing mill that can finely crush materials, it is widely used in building material, tone crushing, railway, cement, and chemical industry.

AGICO Group is an integrative enterprise group. It is a Chinese company that specialized in manufacturing and exporting cement plants and cement equipment, providing the turnkey project from project design, equipment installation and equipment commissioning to equipment maintenance.

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