A crusher is a

machine A machine is a physical system using Power (physics), power to apply Force, forces and control Motion, movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to na ...

designed to reduce large

rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wales ...

s into smaller rocks,

gravel Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone. Gravel is classifi ...

, sand or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or

recycled Recycling is the process of converting waste materials into new materials and objects. The recovery of energy from waste materials is often included in this concept. The recyclability of a material depends on its ability to reacquire the p ...

, or to reduce the size of a solid mix of raw materials (as in rock

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 April 2 ...

), so that pieces of different composition can be differentiated. Crushing is the process of transferring a force amplified by

mechanical advantage Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for t ...

through a material made of molecules that bond together more strongly, and resist deformation more, than those in the material being crushed do. Crushing devices hold material between two parallel or

tangent In geometry, the tangent line (or simply tangent) to a plane curve at a given point is the straight line that "just touches" the curve at that point. Leibniz defined it as the line through a pair of infinitely close points on the curve. More ...

solid surfaces, and apply sufficient force to bring the surfaces together to generate enough energy within the material being crushed so that its molecules separate from (fracturing), or change alignment in relation to (deformation), each other. The earliest crushers were hand-held stones, where the weight of the stone provided a boost to muscle power, used against a stone anvil.

Querns Quern-stones are stone tools for hand-grinding a wide variety of materials. They are used in pairs. The lower stationary stone of early examples is called a saddle quern, while the upper mobile stone is called a muller, rubber or handstone. The ...

and

mortars Mortar may refer to: * Mortar (weapon), an indirect-fire infantry weapon * Mortar (masonry), a material used to fill the gaps between blocks and bind them together * Mortar and pestle, a tool pair used to crush or grind * Mortar, Bihar, a village i ...

are types of these crushing devices.

Background history

In industry, crushers are machines which use a metal surface to break or compress materials into small fractional chunks or denser masses. Throughout most of industrial history, the greater part of crushing and mining part of the process occurred under muscle power as the application of force concentrated in the tip of the miners pick or sledge hammer driven drill bit. Before explosives came into widespread use in bulk mining in the mid-nineteenth century, most initial ore crushing and sizing was by hand and hammers at the mine or by water powered trip hammers in the small

charcoal Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) in minimal oxygen to remove all water and volatile constituents. In the traditional version of this pyrolysis process, cal ...

fired smithies and iron works typical of the

Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history marking the transition from the Middle Ages to modernity and covering the 15th and 16th centuries, characterized by an effort to revive and surpass ideas ...

through the early-to-middle

industrial revolution The Industrial Revolution was the transition to new manufacturing processes in Great Britain, continental Europe, and the United States, that occurred during the period from around 1760 to about 1820–1840. This transition included going f ...

. It was only after explosives, and later early powerful

steam shovel A steam shovel is a large steam-powered excavating machine designed for lifting and moving material such as rock and soil. It is the earliest type of power shovel or excavator. Steam shovels played a major role in public works in the 19th and e ...

s produced large chunks of materials, chunks originally reduced by hammering in the mine before being loaded into sacks for a trip to the surface, chunks that were eventually also to lead to rails and mine railways transporting bulk aggregations that post-mine face crushing became widely necessary. The earliest of these were in the foundries, but as coal took hold the larger operations became the

coal breaker A coal breaker is a coal processing plant which breaks coal into various useful sizes. Coal breakers also remove impurities from the coal (typically slate) and deposit them into a culm dump. The coal breaker is a forerunner of the modern coal pr ...

s that fueled industrial growth from the first decade of the 1600s to the replacement of breakers in the 1970s through the fuel needs of the present day. The gradual coming of that era and displacement of the cottage industry based economies was itself accelerated first by the utility of wrought and cast iron as a desired materials giving impetus to larger operations, then in the late-sixteenth century by the increasing scarcity of wood lands for charcoal production to make the newfangled window glass material that had become—along with the chimney—'' 'all the rage' '' among the growing middle-class and affluence of the sixteenth-and-seventeenth centuries;and as always, the charcoal needed to smelt metals, especially to produce ever larger amounts of

brass Brass is an alloy of copper (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...

and

bronze Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloids such ...

,Burke, James, "''Connections''", page 167

pig iron Pig iron, also known as crude iron, is an intermediate product of the iron industry in the production of steel which is obtained by smelting iron ore in a blast furnace. Pig iron has a high carbon content, typically 3.8–4.7%, along with silic ...

cast iron Cast iron is a class of iron–carbon alloys with a carbon content more than 2%. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured: white cast iron has carbide impuriti ...

and wrought iron demanded by the new consumer classes. Other metallurgical developments such as silver and gold mining mirrored the practices and developments of the bulk material handling methods and technologies feeding the burgeoning appetite for more and more iron and glass, both of which were rare in personal possessions until the 1700s. Things only became worse when the English figured out how to cast the more economical iron cannons (1547), following on their feat of becoming the armorers of the European continent's powers by having been leading producers brass and bronze guns, and eventually by various acts of Parliament, gradually banned or restricted the further cutting of trees for charcoal in larger and larger regions in the United Kingdom. In 1611, a consortium led by courtier

Edward Zouch Sir Edward Zouch of Woking (died 1634) was a courtier to English kings James and Charles I, a masque actor, and Knight Marshal of the King's Household. He was the son of Sir Willam Zouch or Zouche. His mother's name is not known. Career Marriage ...

was granted a patent for the

reverberatory furnace A reverberatory furnace is a metallurgical or process furnace that isolates the material being processed from contact with the fuel, but not from contact with combustion gases. The term ''reverberation'' is used here in a generic sense of ''rebo ...

, a furnace using coal, not precious national timber reserves,Burke, James, ''"Connections"'', page 168 which was immediately employed in glass making. An early politically connected and wealthy Robber Baron figure Sir

Robert Mansell Sir Robert Mansell (1573–1656) was an admiral of the English Royal Navy and a Member of Parliament (MP), mostly for Welsh constituencies. His name was sometimes given as Sir Robert Mansfield and Sir Robert Maunsell. Early life Mansel was a W ...

bought his way into the fledgling furnace company wrested control of it, and by 1615 managed to have James I issue a proclamation forbidding the use of wood to produce glass, giving his families extensive coal holdings a monopoly on both source and means of production for nearly half-a-century. Abraham Darby a century later relocated to Bristol where he had established a building brass and bronze industry by importing Dutch workers and using them to raid Dutch techniques. Both materials were considered superior to iron for cannon, and machines as they were better understood. But Darby would change the world in several key ways. Where the Dutch had failed in casting iron, one of Darby's apprentices, John Thomas succeeded in 1707Burke, James, ''"Connections"'', page 170 and as Burke put it: ''"had given England the key to the Industrial Revolution"''. At the time, mines and

foundries A foundry is a factory that produces metal castings. Metals are cast into shapes by melting them into a liquid, pouring the metal into a mold, and removing the mold material after the metal has solidified as it cools. The most common metals pr ...

were virtually all small enterprises except for the tin mines (driven by the price and utility of brass) and materials came out of the mines already hammered small by legions of miners who had to stuff their work into carry sacks for pack animal slinging. Concurrently, mines needed drainage resulting in

Savery Savery is a surname. Notable people with the surname include: * Constance Savery (1897-1999), English author * Gil Savery (1917-2018), American journalist * Henry Savery (1791–1842), Australian novelist * Jan Savery (1589–1654), Flemish painter ...

and Newcomen's early steam driven pumping systems. The deeper the mines went, the larger the demand became for better pumps, the greater the demand for iron, the greater the need for coal, the greater the demand for each. Seeing ahead clearly, Darby, sold off his brass business interests and relocated to

Coalbrookdale Coalbrookdale is a village in the Ironbridge Gorge in Shropshire, England, containing a settlement of great significance in the history of iron ore smelting. It lies within the civil parish called the Gorge. This is where iron ore was first s ...

with its plentiful coal mines, water power and nearby ore supplies. Over that decade his foundries developed iron casting technologies and began to supplant other metals in many applications. He adapted

Coking Coking is the heating of coal in the absence of oxygen to a temperature above 600 °C to drive off the volatile components of the raw coal, leaving a hard, strong, porous material of high carbon content called coke. Coke consists almost ent ...

of his fuel by copying Brewers practices. In 1822 the pumping industries needs for larger cylinders met up with Darby's ability to melt sufficient quantities of pig iron to cast large inexpensive iron cylinders instead of costly brass ones, reducing the cost of cylinders by nine-tenths. With

gunpowder Gunpowder, also commonly known as black powder to distinguish it from modern smokeless powder, is the earliest known chemical explosive. It consists of a mixture of sulfur, carbon (in the form of charcoal) and potassium nitrate (saltpeter). ...

being increasingly applied to mining, rock chunks from a mining face became much larger, and the blast dependent mining itself had become dependent upon an organized group, not just an individual swinging a pick. Economies of scale gradually infused industrial enterprises, while transport became a key bottleneck as the volume of moved materials continued to increase following demand. This spurred numerous canal projects, inspired laying first wooden, then iron protected rails using draft animals to pull loads in the emerging bulk goods transportation dependent economy. In the coal industry, which grew up hand in hand as the preferred fuel for smelting ores, crushing and preparation (cleaning) was performed for over a hundred years in

s, massive noisy buildings full of conveyors, belt-powered trip-hammer crushing stages and giant metal grading/sorting grates. Like mine pumps, the internal conveyors and trip-hammers contained within these 7—11 story buildings.

Industrial use

Mining operations use crushers, commonly classified by the degree to which they fragment the starting material, with primary and secondary crushers handling coarse materials, and tertiary and Quaternary crushers reducing ore particles to finer gradations. Each crusher is designed to work with a certain maximum size of raw material, and often delivers its output to a screening machine which sorts and directs the product for further processing. As well as size, machines designed for each of these stages must take into account the basic methods of material size reduction; impact, compression, attrition, and cutting. Depending on the material properties and desired outcome some methods of crushing and thus machines designs may be more appropriate for the use case. Typically, crushing stages are followed by milling stages if the materials need to be further reduced. Additionally rock breakers are typically located next to a crusher to reduce oversize material too large for a crusher. Crushers are used to reduce particle size enough so that the material can be processed into finer particles in a grinder. A typical processing line at a mine might consist of a crusher followed by a SAG mill followed by a

ball mill A ball mill is a type of grinder used to grind or blend materials for use in mineral dressing processes, paints, pyrotechnics, ceramics, and selective laser sintering. It works on the principle of impact and attrition: size reduction is done ...

. In this context, the SAG mill and ball mill are considered grinders rather than crushers. In operation, the raw material (of various sizes) is usually delivered to the primary crusher's

hopper Hopper or hoppers may refer to: Places *Hopper, Illinois * Hopper, West Virginia * Hopper, a mountain and valley in the Hunza–Nagar District of Pakistan * Hopper (crater), a crater on Mercury People with the name * Hopper (surname) * Grace H ...

dump truck A dump truck, known also as a dumping truck, dump trailer, dumper trailer, dump lorry or dumper lorry or a dumper for short, is used for transporting materials (such as dirt, gravel, or demolition waste) for construction as well as coal. A typi ...

excavators Excavators are heavy construction equipment consisting of a boom, dipper (or stick), bucket and cab on a rotating platform known as the "house". The house sits atop an undercarriage with tracks or wheels. They are a natural progression fro ...

or wheeled front-end loaders. A feeder device such as an apron feeder,

conveyor A conveyor system is a common piece of mechanical handling equipment that moves materials from one location to another. Conveyors are especially useful in applications involving the transport of heavy or bulky materials. Conveyor systems allow ...

or vibrating grid controls the rate at which this material enters the crusher, and often contains a preliminary screening device which allows smaller material to bypass the crusher itself, thus improving efficiency. Primary crushing reduces the large pieces to a size which can be handled by the downstream machinery. Some crushers are mobile and can crush rocks as large as 1.5 meter (60 inches). Primarily used in-pit at the mine face these units are able to move with the large infeed machines (mainly shovels) to increase the tonnage produced. In a mobile road operation, these crushed rocks are directly combined with concrete and

asphalt Asphalt, also known as bitumen (, ), is a sticky, black, highly viscous liquid or semi-solid form of petroleum. It may be found in natural deposits or may be a refined product, and is classed as a pitch. Before the 20th century, the term a ...

which are then deposited on to a road surface. This removes the need for hauling over sized material to a stationary crusher and then back to the road surface.

Types of crushers

Portable Plant - Metso Nordberg HP300 Close Circuit Plant

File:Geevor waterwheel stamps.jpg, Cornish stamps used in the 19th century for breaking tin ore Image:Rock crusher.jpg, A portable rock crusher from the early 20th century Image:Rock crusher jaws.jpg, The entrance bin of a mine rock crusher Image:Steinmühle.jpg, Mobile crusher Crusher bucket quarry.jpg, Crusher bucket in a quarry Опытная дробилка кормов Ф-IМ, вид со стороны электропривода.png, A feed crusher The following table describes typical uses of commonly used crushers:

Jaw crusher

A jaw crusher uses compressive force for breaking of particle. This mechanical pressure is achieved by the two jaws of the crusher of which one is fixed while the other reciprocates. A jaw or toggle crusher consists of a set of vertical jaws, one jaw is kept stationary and is called a fixed jaw while the other jaw called a swing jaw, moves back and forth relative to it, by a

cam Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a multifunctional intermediate calcium-binding messenger protein expressed in all eukaryotic cells. It is an intracellular target of the secondary messenger Ca2+, and the bind ...

pitman Pitman may refer to: * A coal miner, particularly in Northern England * Pitman (surname) * Pitman, New Jersey, United States * Pitman, Pennsylvania, United States * Pitman, Saskatchewan, Canada * Pitman Shorthand, a system of shorthand * Pitman ar ...

mechanism, acting like a class II

lever A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or ''fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is div ...

or a

nutcracker A nutcracker is a tool designed to open nuts by cracking their shells. There are many designs, including levers, screws, and ratchets. The lever version is also used for cracking lobster and crab shells. A decorative version portrays a person w ...

. The volume or cavity between the two jaws is called the crushing chamber. The movement of the swing jaw can be quite small, since complete crushing is not performed in one stroke. The inertia required to crush the material is provided by a

flywheel A flywheel is a mechanical device which uses the conservation of angular momentum to store rotational energy; a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, ass ...

that moves a shaft creating an eccentric motion that causes the closing of the gap. Jaw crushers are heavy duty machines and hence need to be robustly constructed. The outer frame is generally made of cast iron or steel. The jaws themselves are usually constructed from cast steel. They are fitted with replaceable liners which are made of manganese steel, or Ni-hard (a Ni-Cr alloyed cast iron). Jaw crushers are usually constructed in sections to ease the process transportation if they are to be taken underground for carrying out the operations. Jaw crushers are classified on the basis of the position of the pivoting of the swing jaw # Blake crusher-the swing jaw is fixed at the lower position # Dodge crusher-the swing jaw is fixed at the upper position # Universal crusher-the swing jaw is fixed at an intermediate position The Blake crusher was patented by Eli Whitney Blake in 1858. The Blake type jaw crusher has a fixed feed area and a variable discharge area. Blake crushers are of two types- single toggle and double toggle jaw crushers. In the single toggle jaw crushers, the swing jaw is suspended on the eccentric shaft which leads to a much more compact design than that of the double toggle jaw crusher. The swing jaw, suspended on the eccentric, undergoes two types of motion- swing motion towards the fixed jaw due to the action of toggle plate and vertical movement due to the rotation of the eccentric. These two motions, when combined, lead to an elliptical jaw motion. This motion is useful as it assists in pushing the particles through the crushing chamber. This phenomenon leads to higher capacity of the single toggle jaw crushers but it also results in higher wear of the crushing jaws. These type of jaw crushers are preferred for the crushing of softer particles. In the double toggle jaw crushers, the oscillating motion of the swing jaw is caused by the vertical motion of the pitman. The pitman moves up and down. The swing jaw closes, i.e., it moves towards the fixed jaw when the pitman moves upward and opens during the downward motion of the pitman. This type is commonly used in mines due to its ability to crush tough and abrasive materials. In the Dodge type jaw crushers, the jaws are farther apart at the top than at the bottom, forming a tapered chute so that the material is crushed progressively smaller and smaller as it travels downward until it is small enough to escape from the bottom opening. The Dodge jaw crusher has a variable feed area and a fixed discharge area which leads to choking of the crusher and hence is used only for laboratory purposes and not for heavy duty operations.

Gyratory crusher

A gyratory crusher is similar in basic concept to a jaw crusher, consisting of a concave surface and a conical head; both surfaces are typically lined with manganese steel surfaces. The inner cone has a slight circular movement, but does not rotate; the movement is generated by an

eccentric Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

arrangement. As with the jaw crusher, material travels downward between the two surfaces being progressively crushed until it is small enough to fall out through the gap between the two surfaces. A gyratory crusher is one of the main types of primary crushers in a mine or ore processing plant. Gyratory crushers are designated in size either by the gape and mantle diameter or by the size of the receiving opening. Gyratory crushers can be used for primary or secondary crushing. The crushing action is caused by the closing of the gap between the mantle line (movable) mounted on the central vertical spindle and the concave liners (fixed) mounted on the main frame of the crusher. The gap is opened and closed by an eccentric on the bottom of the spindle that causes the central vertical spindle to gyrate. The vertical spindle is free to rotate around its own axis. The crusher illustrated is a short-shaft suspended spindle type, meaning that the main shaft is suspended at the top and that the eccentric is mounted above the gear. The short-shaft design has superseded the long-shaft design in which the eccentric is mounted below the gear.

Cone crusher

With the rapid development of mining technology, the cone crusher can be divided into four types: compound cone crusher, spring cone crusher, hydraulic cone crusher and gyratory crusher. According to different models, the cone crusher is divided into vertical shaft cone (VSC) series cone crusher (compound cone crusher), Symons cone crusher, PY cone crusher, single cylinder hydraulic cone crusher, multi-cylinder hydraulic cone crusher, gyratory crusher, etc. A cone crusher is similar in operation to a gyratory crusher, with less steepness in the crushing chamber and more of a parallel zone between crushing zones. A cone crusher breaks rock by squeezing the rock between an eccentrically gyrating spindle, which is covered by a wear-resistant mantle, and the enclosing concave hopper, covered by a manganese concave or a bowl liner. As rock enters the top of the cone crusher, it becomes wedged and squeezed between the mantle and the bowl liner or concave. Large pieces of ore are broken once, and then fall to a lower position (because they are now smaller) where they are broken again. This process continues until the pieces are small enough to fall through the narrow opening at the bottom of the crusher. A cone crusher is suitable for crushing a variety of mid-hard and above mid-hard ores and rocks. It has the advantage of reliable construction, high productivity, better granularity and shape of finished products, easy adjustment and lower operational costs. The spring release system of a cone crusher acts an overload protection that allows tramp to pass through the crushing chamber without damage to the crusher.

Compound cone crusher

Compound cone crusher (VSC series cone crusher) can crush materials of over medium

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...

. It is mainly used in mining, chemical industry, road and bridge construction, building, etc. As for VSC series cone crusher, there are four crushing cavities (coarse, medium, fine and superfine) to choose. Compared with the same type, VSC series cone crusher, whose combination of crushing frequency and eccentricity is the best, can make materials have higher comminution degree and higher yield. In addition, VSC series cone crusher's enhanced laminating crushing effect on material particles makes the cubic shape of crushed materials better, which increases the selling point.

Symons cone crusher

Symons cone crusher (spring cone crusher) can crush materials of above medium hardness. And it is widely used in metallurgy, building, hydropower, transportation, chemical industry, etc. When used with jaw crusher, it can be used as secondary, tertiary or quaternary crushing. Generally speaking, the standard type of Symons cone crusher is applied to medium crushing. The medium type is applied to fine crushing. The short head type is applied to coarse fine crushing. As casting steel technique is adopted, the machine has good rigidity and large high strength.

Single cylinder hydraulic cone crusher

Single cylinder hydraulic cone crusher is mainly composed of main frame, transmission device, eccentric shaft, bowl-shaped bearing, crushing cone, mantle, bowl liner, adjusting device, adjusting sleeve, hydraulic control system, hydraulic safety system, dust-proof ring, feed plate, etc. It is applied to cement mill, mining, building construction, road &bridge construction, railway construction and metallurgy and some other industries.

Multi-cylinder hydraulic cone crusher

Multi-cylinder hydraulic cone crusher is mainly composed of main frame, eccentric shaft, crushing cone, mantle, bowl liner, adjusting device, dust ring, transmission device, bowl-shaped bearing, adjusting sleeve, hydraulic control system, hydraulic safety system, etc. The electric motor of the cone crusher drives the eccentric shaft to make periodic swing movement under the shaft axis, and consequently surface of mantle approaches and leaves the surface of bowl liner now and then, so that the material is crushed due to squeezing and grinding inside the crushing chamber. The safety cylinder of the machine can ensure safety as well as lift supporting sleeve and static cone by a hydraulic system and automatically remove the blocks in the crushing chamber when the machine is suddenly stuffy. Thus the maintenance rate is greatly reduced and production efficiency is greatly improved as it can remove blocks without disassembling the machine.

Impact crusher

Impact crushers involve the use of

impact Impact may refer to: * Impact (mechanics), a high force or shock (mechanics) over a short time period * Impact, Texas, a town in Taylor County, Texas, US Science and technology * Impact crater, a meteor crater caused by an impact event * Impact ...

rather than

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

to crush material. The material is contained within a cage, with openings on the bottom, end, or side of the desired size to allow pulverized material to escape. There are two types of impact crushers: horizontal shaft impactor and vertical shaft impactor.

Horizontal shaft impactor (HSI) / hammermill

The HSI crushers break rock by impacting the rock with hammers that are fixed upon the outer edge of a spinning rotor. HSI machines are sold in stationary, trailer mounted and crawler mounted configurations. HSI's are used in recycling, hard rock and soft materials. In earlier years the practical use of HSI crushers is limited to soft materials and non abrasive materials, such as

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

phosphate In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid . The phosphate or orthophosphate ion is derived from phospho ...

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywall. ...

, weathered

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

s, however improvements in metallurgy have changed the application of these machines.

Vertical shaft impactor (VSI)

VSI crushers use a different approach involving a high speed rotor with wear resistant tips and a crushing chamber designed to 'throw' the rock against. The VSI crushers utilize

velocity Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...

rather than surface force as the predominant force to break rock. In its natural state, rock has a jagged and uneven surface. Applying surface force (

) results in unpredictable and typically non-cubical resulting particles. Utilizing

rather than surface force allows the breaking force to be applied evenly both across the surface of the rock as well as through the mass of the rock. Rock, regardless of size, has natural

fissures A fissure is a long, narrow crack opening along the surface of Earth. The term is derived from the Latin word , which means 'cleft' or 'crack'. Fissures emerge in Earth's crust, on ice sheets and glaciers, and on volcanoes. Ground fissure A ...

(faults) throughout its structure. As rock is 'thrown' by a VSI rotor against a solid anvil, it fractures and breaks along these

. Final particle size can be controlled by 1) the

at which the rock is thrown against the anvil and 2) the distance between the end of the rotor and the impact point on the anvil. The product resulting from VSI crushing is generally of a consistent cubical shape such as that required by modern Superpave

highway A highway is any public or private road or other public way on land. It is used for major roads, but also includes other public roads and public tracks. In some areas of the United States, it is used as an equivalent term to controlled-access ...

applications. Using this method also allows materials with much higher abrasiveness to be crushed than is capable with an HSI and most other crushing methods. VSI crushers generally utilize a high speed spinning rotor at the center of the crushing chamber and an outer impact surface of either abrasive resistant metal anvils or crushed rock. Utilizing cast metal surfaces 'anvils' is traditionally referred to as a "shoe and anvil VSI". Utilizing crushed rock on the outer walls of the crusher for new rock to be crushed against is traditionally referred to as "rock on rock VSI". VSI crushers can be used in static plant set-up or in mobile tracked equipment.

Mineral sizers

Mineral sizers are a variety of ''roll crushers'' which use two rotors with large teeth, on small diameter shafts, driven at a low speed by a direct high torque drive system. This design produced three-stage breaking action which all interact when breaking materials using sizer technology. * The gripping: at the first stage, the material is gripped by the leading faces of opposed rotor teeth. These subject the rock to multiple point loading, inducing stress into the material to exploit any natural weaknesses. At the second stage, material is broken in tension by being subjected to a three-point loading, applied between the front tooth faces on one rotor, and rear tooth faces on the other rotor. Any lumps of material that still remain oversize, are broken as the rotors chop through the fixed teeth of the breaker bar, thereby achieving a three dimensional controlled product size. * The rotating screen effect: The interlaced toothed rotor design allows free flowing undersize material to pass through the continuously changing gaps generated by the relatively slow moving shafts. * The deep scroll tooth pattern: The deep scroll conveys the larger material to one end of the machine and helps to spread the feed across the full length of the rotors. This feature can also be used to reject oversize material from the machine. MMD Group - http://www.mmdsizers.com/products/sizers Their primary advantage is a compact geometry and size which is valuable in mining industry, .e.g. in

underground hard-rock mining Underground hard-rock mining refers to various underground mining techniques used to excavate "hard" minerals, usually those containing metals, such as ore containing gold, silver, iron, copper, zinc, nickel, tin, and lead. It also involves the ...

Crusher bucket

A crusher bucket is an attachment for hydraulic excavators. Its way of working consists on a bucket with two crushing jaws inside, one of them is fixed and the other one moves back and forth relative to it, as in a

jaw crusher A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, sand or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or to re ...

. They are manufactured with a high inertia power train, circular jaw movement and an antiestagnation plate, which prevents large shredding pieces from getting stuck in the bucket's mouth, not allowing them to enter the crushing jaws. They have also the crushing jaws placed in a cross position. This position together with its circular motion gives these crusher buckets the faculty of grinding wet material. Crushing jaws movement in a Xcentric Crusher bucket

Crushing jaws movement in a Xcentric Crusher bucket

Technology

For the most part advances in crusher design have moved slowly. Jaw crushers have remained virtually unchanged for sixty years. More reliability and higher production have been added to basic cone crusher designs that have also remained largely unchanged. Increases in rotating speed have provided the largest variation. For instance, a 48-inch (120 cm) cone crusher manufactured in 1960 may be able to produce 170 tons/h of crushed rock, whereas the same size crusher manufactured today may produce 300 tons/h. These production improvements come from speed increases and better crushing chamber designs. The largest advance in cone crusher reliability has been seen in the use of hydraulics to protect crushers from being damaged when uncrushable objects enter the crushing chamber. Foreign objects, such as

steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...

, can cause extensive damage to a cone crusher, and additional costs in lost production. The advance of hydraulic relief systems has greatly reduced downtime and improved the life of these machines.

References

External links

Faults And Solutions Of Sand Making Machine

The Common Questions Of Cone Crusher
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