rock crushing equipment primary vibrating feeder

static grizzly screen as a rock separator

The screening a Static Grizzly separator does is sort and classify the rock according to size. The first stage is SCALPING. This is the practice of removing any material that may slow production. It may be rock that is too big for the equipment to effectively handle, or fine material that is taking up valuable space and will consume precious energy if there is further handling. The name of the equipment that performs this function is called a GRIZZLY. The equipment is limited to a maximum size of rock that it can accept. The grizzly is a pattern of heavy steel bars that are laid down in a grid pattern. This grid will allow the small rocks to go through. The larger rock being bigger than the grid opening wont. This rock then can be either sent for further size reduction, or removed.

The purpose of this is to keep the grizzlies down time to a minimum by preventing the oversized rock from piling up while on its surface. The effectiveness of the sizing will be lowered due to rock that could go through sliding off. But as a counter balance the overall through put will be better due to the greater availability of the grid. If the Grizzlies performance rate is to low, then causing the grizzly to vibrate will increase the effectiveness of the sizing.

The Ross Chain Feeder illustrated in Fig. 3 is shown discharging the ore over a bar screen, or grizzly. It is advisable to provide a screen of this sort ahead of the primary breaker in order to bypass material that is already small enough to pass straight through the machine. The commonest device is a stationary grizzly from 6 to 12 ft. long, slightly wider than the stream of ore, and set at a slope of from 45 to 60 to the horizontal. The bars, which should be of mild steel, are preferably wedge-shaped with the wider part uppermost. They are held together by long bolts at right-angles to their length and are kept at the desired distance apart by spacing washers, which often consist of old piping cut to the required length. The clearance betweenthe bars at the upper end should be the same as the discharge opening of the crusher which the grizzly serves, but at the lower end it should be slightly greater to prevent choking.

A grizzly of this type, though cheap and simple, tends to get clogged with ore. In conjunction with a Ross Chain Feeder, however, clogging is eliminated and the length of the bars can be reduced by 50% or more.

Bars are a widely used means of reducing the work of primary or secondary crushers. As the ore is fed to the crusher, it passes over the grizzly bars, and the finer pieces drop through into the mill ore bin. The grizzly is made of wear resisting wedge shaped bars easily replaced if necessary.

Grizzly Bars are punched and held in place by steel rods passing through the holes. Cast iron spacers, of the proper shape and width, are placed between the bars. Various types of bars and spacers can be supplied, depending upon the application.

A vibrating grizzly screen has been developed as a distinct improvement over the fixed grizzly now in such wide use.It combines the functions of screening and feeding the ore to the primary crusher, and, by eliminating the undersize product in the ore feed to the crusher, materially increases the crusher capacity. In addition, due to the pulsating action of the unit, the ore is fed positively to the crusher, at a controlled rate and the manual labor usually required is eliminated.

The unit consists of a strong, frame mounted, standard grizzly which receives a positive eccentric motion in a lateral plane through connecting links attached to the head motion of the jaw crusher. Due to this positive action the angle of slope of the grizzly may be much less than that required in fixed type grizzlies; and head room or fall may be reduced.The Shaking Grizzly is constructed in several sizes to fit standard Jaw Crushers.

Aggregate production plants use screens to direct, separate, and control material flow in the process. The two main purposes for screening the aggregates are to remove oversize material from the crusher product or undersizematerial from the crushing plant and to completely size the materials produced. An aggregate production plant must perform both functions.

The feed may contain some material that does not have to be crushed and which should be removed from the input to the primary crusher. A scalping unit is frequently used between the feeder and the primary crusher to remove from the feed material that is smaller than the setting of the crusher. It may be a grid, grate, or screen, and it may be stationary or it may vbrate. Raw material removed from the feed is sent to finish screens and reduction crushers.

apron feeders

Apron Feeders must always be employed to ensure that the feed to a crushing machine is drawn at a constant rate from the bin which serves it. Of the many designs in existence by far the most widely used are the apron and pan feeders, although the Ross Chain Feeder is coming into favour for handling coarse ore.

Aggregate production plants have components such as feeders and scalping units to direct material to be crushed, separated, or stored for later use. Feeders are used mainly to handle input material for the plant. They are of two types: the apron feeders and mechanical, or reciprocating-plate, feeders.

Apron feeders or grizzlies are generally used to feed quarry rock into a primary crusher. They are of a heavy-duty construction to take the shock from rocks dumped directly on them. To cushion the blow of material dumped on the feeder, a large hopper may be used to receive the dumped loads. The apron feeder consists of a series of overlapping pans or plates which form a continuous chain like a conveyor belt. They are generally installed on a slight decline and driven to throw material in the downward direction. Widths of feeders range from one to 15 ft and lengths vary from one (for the largest) to five times their width. Feeders are driven by less than one horsepower up to 40-hp motors, depending on feeder size and expected load.

The main point to consider in selecting a feeder is that it must provide an even flow of material to the primary crusher. The size of the feeder and its speed should provide a capacity 25-35% greater than the capacity of the crusher. It may be necessary to provide for hand Controls to regulate the feeder in the case of irregular dumping of the raw material.

The Industrial Apron Feeder is the best of breed feeder. Earlier I made a statement that feeders are stationary while the rock moves. There is a saying that there is an exception for every rule and this could be classed as that exception. An apron feeder is in fact a conveyor that is constructed from metal. It regulates the feed by carrying the ore to the delivery point at a controlled rate of speed. The face of the conveyor is made from heavy armour plating, and works like the track on a crawler type tractor.

Due to this type of construction it is able to withstand high impact from large ore. This, coupled to the fact that the feeder can have a very large entrance opening, makes it a good choice to he put under stockpiles and equipment where the ore may have a long fall before it enters the feeder. While the conveyor portion of the Apron feeder doesnt have a high wear factor from abrasion, the sides, entry and exit points still do. These will have to be maintained.

Another problem associated with this type of feeder is that it doesnt handle very fine material well. Dust will require special consideration in the design of the equipment, possibly a dust chute prior to the feeder or an easily accessible clean up area to handle spillage as it occurs.

The apron feeder illustrated in Fig. 2 consists of an endless belt made up of flat overlapping steel plates. The line of plates is carried on two roller chains, one on each side, the links of which are of the same length as the plates. Sometimes the inner links of each line of chains are made of angle steel, to which the plates can be bolted, or else lengths of angle are riveted to both sides of the plates and bolted to the corresponding inner links. Each link pin carries a flanged roller ; these run on two lines of rails, and at each end of their travel they pass over head and tail sprockets, the former being driven and the latter running free. Thus the chains take the strain of the drive and the plates have only to carry the weight of the ore. The ends of the plates are curved and fit into each other to prevent leakage through the joints, especially at the point where they begin to turn over the head sprocket. Instead of joining separate links with a separate pin it is common practice to use one long bolt to connect consecutive links on one chain with the corresponding set on the other ; this helps to stiffen the feeder as a whole.

It is preferable to drive each feeder with its own motor, which should be connected with the head sprocket through some device for varying the speed. The maximum linear speed of the plates is seldom required to exceed 20 ft. per minute.

The feeder is usually installed under an opening in the bottom of the bin and takes the weight of the column of ore resting on it. The plates, as they travel forward, draw out a continuous stream of ore, which is discharged as they turn over the head sprocket. The depth of the ore stream can be regulated by an adjustable gate placed immediately in front of the opening in the bin, but the clearance between the bottom edge of the gate and the plates must always be sufficient to allow passage of the largest lump likely to be encountered. If too much ore is being delivered when the gate is in its lowest allowable position, the quantity can be reduced to the required amount by adjustment of the speed regulator.

The apron type of feeder is not suitable if it has to work at an inclination greater than 15, at which angle the ore will slip back downthe slope. The pan feeder is designed to meet this contingency. It is constructed in the same way as the apron feeder except that the plates are recessed in the form of a pan, the depth of which varies according to requirements. Both types are made for normal purposes in widths from 24 to 60 in. and in lengths from 6 to 12 ft., and both dimensions can be increased, should conditions demand a larger size. They are suitable for ore of any size down to in., but below this size leakage through the joints becomes excessive and a belt feeder is preferable.

An apron or pan conveyor is sometimes substituted for a belt conveyor for very heavy duty. Its construction is the same as that ofa feeder except that it is usually longer, and it is driven at a fixed speed which does not as a rule exceed 50 ft. per minute.

T = 5 wds/c where : T = tons of ore per hour, w = effective width of feeder in feet, d = depth of the layer of ore in inches, s = speed of feeder in feet per minute, c = number of cubic feet of broken ore per ton.

By giving d and s their maximum and minimum values the range of the feed rate can be obtained. The formula holds good for a pan feeder or conveyor if d is assumed to be the average depth of the layer of ore.

A jaw crusher fed with an Apron feeder will increase capacity upto 40% by eliminating bridging and supplying a steady even feed. Photo shows shop assembly of a 24 x 36 Traylor Type M Jaw Crusher and a 36 x 12-0 Traylor All-Steel Heavy Duty Apron Feeder. The Type M Crusher is built with a 50,000 pound TENSILE STRENGTH Meehanite Frame, with pitman shaft bearings fitted with removable water-cooled babbitted brushings; Cast Steel Swing Jaw and Pitman; Patented Swing Jaw Suspension fitted with removable bushings with greatly increased bearing area; and Manganese steel patented smooth face Curved Jaw Plates, which increase life of wearing plates up to 100% over Straight Crushing Plates and allow for finer settings.Write us for appointment to talk over this Crusher and Feeder Combination with you.

With over 125 years of combined experience in the application, engineering and manufacturing of heavy-duty apron feeders, Metso is truly the worldwide leader in the supply of this equipment.This is Metsos world class apron feeder (which combines the best features of NICO apron feeder and Stephens-Adamsons apron feeder), you will get the most rugged and reliable machine available for your operation.

Metsos World-Class apron feeder is not a new design. As the originator of the crawler tractor-type apron feeder, Metsos NICO and Stephens-Adamson brands have joined forces to combine the best features of their respective feeder designs. The result is a rugged and reliable tractor-type feeder that remains the preferred design throughout the world. Benefits of the Metso World-Class Apron Feeder put it in a class by itself. Metso offers a robust design with an intense commitment to quality and attention to detail. The main benefit to the end user is ruggedness and dependability for heavy-duty operations. The bottom line: reduced operating downtime and lower overall cost.

micro rock crushers & conveyors | portable rock crusher & concrete crushers for sale

Senya Tech provides cone crusher, vertical shaft impact crusher, impact crusher, jaw crusher,which are widely used for the primary, secondary and tertiary hard-rock crushing for stone-processing line and sand-making line.

Senya Tech provides MP Mobile Crushing Plants and Portable Crushing Plants, which can move to the source of stones with high efficiency, flexibility and low costs, and compose a complicated application. It includes jaw crusher, impact crusher, cone crusher, vibrating screen and other combination type, which can be transported wholly-assembled and apart.

Senya Tech offer a wide range of mobile rock crushers, scalpers&screeners, both tracked and wheeled, including jaw, cone&impact crushers.Mobile crushing and screening equipments developed by Senya are used widely in mining, crushing, construction waste recycling fields etc.

conveying equipment | u.s. conveying manufacturer | superior industries

All that time it took to design and build postponed your ability to generate income. What if we told you we've got a library of pre-engineered plants ready to build, rapidly install and produce profit?

Superior replacement crusher parts are taken from the same warehouse used for our manufacturing operations. That means you get an equal part, with equal quality, thats designed exactly for your machine.

While most conveyor manufacturers outsource parts production, Superior uses our own ingredients in our conveying equipment. All the idlers, pulleys, scrapers and accessories basically the operating components of your conveyor are designed and built right here. From head to tail, our conveyors are 100% Superior.

For almost 50 years, Superior manufactured the conveying equipment to feed, transfer and stockpile dry bulk materials. We earned a reputation for innovation, durability and convenience because of our conveyors.Meanwhile, our customers groaned for a better brand of service for their crushing, screening and washing equipment. The existing manufacturers of this processing equipment stopped being innovative, stripped away durability and were famously inconvenient to work with.In the middle part of the 2010s, Superior launched an aggressive strategy to improve the reliability and performance of the machinery between the conveyors.Today, were building the finest line of crushing, screening and washing equipmentin the world, which is sparking continuous improvement of our traditional conveyors.

superior industries | rock face to load out | bulk material processing equipment

All that time it took to design and build postponed your ability to generate income. What if we told you we've got a library of pre-engineered plants ready to build, rapidly install and produce profit?

Superior replacement crusher parts are taken from the same warehouse used for our manufacturing operations. That means you get an equal part, with equal quality, thats designed exactly for your machine.

Born and raised in the rural Midwest, privately-owned Superior Industries is supported by some of the hardest working people on the planet.Together, we are building an American manufacturingcompany that creatively solves problems, eagerly serves customers, and pursues the lowest cost per ton. Were motivated by new opportunities for our employees, distributors, vendors, communities,and most importantlyyou!

Its a multi-functional portable conveyor that loads, unloads and stockpiles at deep water and inland waterways.See our new comprehensive guide of features, specifications, and applications for TeleStacker Conveyors in marine applications.

Our constructionmanagement team is designing and building high-grade aggregate processing plants throughout North America. Now, were ready to convert your vision from tons of steel to a modern, efficient aggregate plant thats backed for life.

Superior has grown into one of the worlds leading manufacturers of bulk material processing and handling equipment and thelargestdry bulk conveyor builder in the world! All along, the vision of Superior is simple: serve our customers with integrity and provide opportunities for employees.

We always have been and always will be a privately-owned company. That means we can add more employees to our customer service team without Wall Street breathing down our neck. Isnt that the way it should be?

A Superior Industries no Brasil fornece componentes de correias transportadoras para algumas das maiores operaes de minerao com as maiores produes do planeta. Alm disso, nossa equipe pode construir ou localizar equipamentos de transporte, como empilhadeiras radiais telescpicas, terrestres e rastreadores de gafanhotos, por meio da sede da empresa nos Estados Unidos.

Anteriormente conhecida como Parcan Group, a Superior Industries adquiriu a fabricante brasileira de engrenagens intermedirias e polias para correias transportadoras em 2015. Desde ento, tem feito grandes esforos para modernizar as instalaes da empresa, mantendo sua capacidade nica de projetar rapidamente polias e rolos personalizados.

Superior tem a reputao de ser um especialista em solues tcnicas na Amrica do Sul. Por solicitao do cliente, equipes da empresa so enviadas s minas para inspees e avaliaes, muitas vezes propondo ideias para estender a vida til dos investimentos em transportadores. Visitas a minas no local so essenciais para que nossa equipe tcnica avalie produtos, reexamine clculos e desenvolva produtos aprimorados a partir dos dados aprendidos.

elrus grizzly bars and feeders

ELRUS Hydraulic Grizzly Bars and Vibrating Grizzly Feeders work in conjunction with each other to remove oversize rock and fines from the primary crusher feed to optimize production and reduce wear and tear on equipment.

At the beginning of the sorting process, over-size material from pit run or shot rock loaded onto the Hydraulic Side Dump Grizzly is removed. What passes through the grizzly bars lands in the hopper and falls onto the Vibrating Grizzly Feeder (VGF).

A Hydraulic Grizzly can help your operation deal with the larger rock you encounter on your site. With its rugged construction, the Grizzly has been designed and engineered to exceed the demands of the toughest pit, quarry, and mine applications.

Not only is the Grizzly built to handle large feed rates of materials; it has been engineered and manufactured to withstand the extreme rigors of quarry life. The Grizzly bars have been designed for optimum separation efficiency while withstanding maximum punishment. They can be set according to the oversize material you need to remove in order to minimize damage and improve the overall performance of the crushing spread.

Vibrating grizzly feeders remove fine material from crusher feed before it enters the jaw. No contamination within the crushing chamber promotes rock on rock crushing to increase efficiency and reduce wear on equipment.

As its name suggests, the feeder vibrates and this agitation causes the material to separate. This process, known as segregation, causes the small material (Fines) to sink to the bottom and the larger rock moves to the top. The segregation continues as the feed travels down the lengthof the VGF; by the time it reaches the fingers at the end, the fines are able to pass through the spacing, leaving only clear stone to enter the crushing chamber.

I don't know about you, but Earle the Grizzly was SUPER STOKED when he heard about our Vibrating Grizzly Feeders. I've got a feeling he's not gonna be too thrilled when he finds out what they really do.

vibrating grizzly feeders | mclanahan

Vibrating Grizzly Feeders are engineered to combine the functions of feeding and scalping into one unit, reducing the cost of having two separate units. Vibrating Grizzly Feeders are mainly used in a primary applications feeding a primary crusher. The Vibrating Grizzly Feeder provides a continuous feed rate under a variety of loading and material conditions. Vibrating Grizzly Feeders are designed to take heavy shock loads from trucks, shovels and loaders. This type of feeder can be used in quarries, recycling, industrial processing, mining, and sand and gravel operations, as well as in a wide range of processing industries.

The McLanahan Vibrating Grizzly Feeder has a history of reliability and durability. McLanahan offers feeders in five different widths to match up to the crusher opening width. For example, McLanahan designs feeders with shallower sides for use in portable plants where over plant height is limited. We also design feeders with deeper sides for stationary applications where large haul trucks are dominantly used. Unlike many manufacturers of Vibrating Grizzly Feeders, McLanahan is enthusiastic to work with customers on applications that require special features not offered by our competitors.

The Vibrating Grizzly Feeder consists of a pan section at the feed end to receive and start segregating the material. The discharge end consists of a grizzly section with openings that allow the undersized material to pass before discharging into the crusher. The feeder is mounted on springs and vibrated via a mechanism located underneath the feeder pan, protecting it from misfed material that fails to reach the feed hopper. The vibration force is angled to the feeder, pointing toward the discharge end. This action of the vibrator forces the material toward the discharge end while segregating the material, causing the finer particles to move toward the bottom of the load.

As the material travels to the grizzly section, the finer material settles to the bottom and passes through the openings in the grizzly. This bypassed material decreases the amount of material going into the crusher, reducing the size of the crusher required as well as the wear inside the crusher. The bypassed material can be combined with the material going through the crusher on the under conveyor. This prescreened material protects the under conveyor from the impact of the material exiting the crusher. The prescreened material can be segregated as a product, or it can be discarded if the fines in the material are a contaminate.

The main purpose of a Vibrating Grizzly Feeder is to feed a primary crusher in a primary application. Vibrating Grizzly Feeders reduce the amount of material going into the crusher by scalping out the product size ahead of the crusher. This reduces the size of the primary crusher required.

Vibrating Grizzly Feeders can be used in rip-rap plant applications to sort ROM material for use on dams, water control and decorative stone applications; for sorting gravel in dredge applications for sized decorative landscaping applications; to scalp roots out of dirt and other materials to improve the product value for a customer; or to spread material from a conveyor to a wider secondary crusher, such as a Roll Crusher, where no grizzly section is required.

Feeders are an important part of any processing circuit. They meter and convey material at a controlled rate into a crusher, sizer, scalper, conveyor or other feeder. They must be correctly sized to achieve maximum throughput and optimum uptime. Download this guide for tips on how to size and select a Feeder for your application.

mining equipment,vibrating screen,mining machinery,vibrating feeder,vibrating conveyor,china sunrise mining equipment - mining machinery leader

CHINA SUNRISE MINING EQUIPMENT is one of the leading professional mining machinery manufacturers in China, is a professional development, design, manufacturing, sales in one of the modern environmental science and technology enterprises.Our strong technical force, advanced production equipment and has a complete set of quality system and world-class production equipment. After years of development, we have customers all over the world.

The vibrating screen, vibrating feeder, vibrating conveyor, plate feeder, disc feeder,industrial filter bags,air slide fabric,needle felt producted by SINOCSM are successfully used in a wide variety of applications,such as mining industry, building materials, metallurgy, transportation, railways, environmental protection industry, chemical industry,thermal power,hard-rock crushing for stone-processing line and sand-making line and so on.

CHINA SUNRISE MINING EQUIPMENT is one of the leading mining equipment manufacturers in China, We maintain a long-term and stable cooperation relationship with CHALCO, Zijin Mining, Yangzi Petrochemical, HK ELECTRIC, MA STEEL, Lafarge, TCC, Asia Cement , Onoda Cement, Conch Cement, Tianshan Cement.

SINOCSM industrial filter bags,air slide fabric,needle punched felts,woven filter cloth,provides cone crusher, impact crusher, jaw crusher, gyratory crusher, sand maker and mobile crushers. They are successfully used in a wide variety of applications,such as cement industry, environmental protection industry, chemical industry,thermal power,hard-rock crushing for stone-processing line and sand-making line and so on.

China Sunrise Mining Equipment(SINOCSM) is a professional mining machinery manufacturer, is a professional development, design, manufacturing, sales in one of the modern environmental science and technology enterprises. Our strong technical force, advanced production equipment and has a complete set of quality system and world-class production equipment. After years of development, we have customers all over the world.

vibrating feeder | vibrate feeding machine - eastman rock crusher

Vibrating screen is mainly used for continuous and uniform feeding in front of the coarse crushing crusher, and at the same time, it can screen fine materials to increase the crusher processing capacity.Applicationsin the crushing and screening equipment of metallurgy, coal mines, beneficiation, building materials, chemicals, abrasives and other industries.MaterialRiver pebbles, granite, basalt, iron ore, limestone, quartz, coal, gangue, construction waste, etc.

Frameprotected by guard plate, the main unit is convenient for maintenance and allows extended service life.Isolation bearingsare protected by rubber, less wear and noise.Oil indicatorconvenient for customers to check the lubricating oil.Gearswith high strength and high precision can ensure the reliable operation.Motorare all famous brands, customers can assign the specific brands like Siemens.Grid clearance (screen bar)be adjusted according to working conditions; replaceable guard plates for the grid are convenient for maintenance.

Also the feeder can be divided into a steel plate structure and a grid structure.The feeder with a steel plate structure is mostly used in a sand and gravel production line to uniformly feed the material into the crushing equipment.The feeder with a grid structure can roughly screen the material. Make the system more economical and reasonable in the preparation, has become an indispensable equipment in crushing and screening.

vibrating grizzly feeders | classification & separation | dove

DOVE is a major manufacturer of heavy duty Vibrating Grizzly Feeders, designed for primary feeding of ore to the Minerals Processing Plants, and or Crushing Plants. These heavy duty Grizzly Feeders are designed to regulate the feed rate for various applications, including:

DOVE laboratory will assay your ore samples rapidly and analyze your raw materials and recommend the most efficient processing plant according to the ore specifications, minerals composition, and ore assay results, and your project size and the geologic and topographic conditions of your mine.

WE HIGHLY RECOMMEND FORWARDING SOIL SAMPLES OF YOUR MINE TO US FOR ANALYSIS, IN ORDER TO DESIGN AND RECOMMEND THE MOST EFFICIENT PROCESSING PLANT, TAILOR MAID TO YOUR MINE REQUIREMENTS, FOR HIGHEST PRODUCTION RECOVERY.

p&q university lesson 7- crushing & secondary breaking : pit & quarry

In the quarry, crushing is handled in four potential stages: primary, secondary, tertiary and quaternary. The reduction of aggregate is spread over these stages to better control the product size and quality, while minimizing waste.

The primary stage was once viewed merely as a means to further reduce stone following the blast or excavation prior to secondary crushing. Today, primary crushing is viewed as more important within the balance of production and proper sizing needs. The size and type of the primary crusher should be coordinated with the type of stone, drilling and blasting patterns, and the size of the loading machine. Most operations will use a gyratory, jaw or impact crusher for primary crushing.

In the secondary and subsequent stages, the stone is further reduced and refined for proper size and shape, mostly based on specifications to produce concrete and asphalt. Between stages, screens with two or three decks separate the material that already is the proper size. Most secondary crushers are cone crushers or horizontal-shaft impact crushers. Tertiary and quaternary crushers are usually cone crushers, although some applications can call for vertical-shaft impact crushers in these stages.

A gyratory crusher uses a mantle that gyrates, or rotates, within a concave bowl. As the mantle makes contact with the bowl during gyration, it creates compressive force, which fractures the rock. The gyratory crusher is mainly used in rock that is abrasive and/or has high compressive strength. Gyratory crushers often are built into a cavity in the ground to aid in the loading process, as large haul trucks can access the hopper directly.

Jaw crushers are also compression crushers that allow stone into an opening at the top of the crusher, between two jaws. One jaw is stationary while the other is moveable. The gap between the jaws becomes narrower farther down into the crusher. As the moveable jaw pushes against the stone in the chamber, the stone is fractured and reduced, moving down the chamber to the opening at the bottom.

The reduction ratio for a jaw crusher is typically 6-to-1, although it can be as high as 8-to-1. Jaw crushers can process shot rock and gravel. They can work with a range of stone from softer rock, such as limestone, to harder granite or basalt.

As the name implies, the horizontal-shaft impact (HSI) crusher has a shaft that runs horizontally through the crushing chamber, with a rotor that turns hammers or blow bars. It uses the high-speed impacting force of the turning blow bars hitting and throwing the stone to break the rock. It also uses the secondary force of the stone hitting the aprons (liners) in the chamber, as well as stone hitting stone.

With impact crushing, the stone breaks along its natural cleavage lines, resulting in a more cubical product, which is desirable for many of todays specifications. HSI crushers can be primary or secondary crushers. In the primary stage, HSIs are better suited for softer rock, such as limestone, and less abrasive stone. In the secondary stage, the HSI can process more abrasive and harder stone.

Cone crushers are similar to gyratory crushers in that they have a mantle that rotates within a bowl, but the chamber is not as steep. They are compression crushers that generally provide reduction ratios of 6-to-1 to 4-to-1. Cone crushers are used in secondary, tertiary and quaternary stages.

With proper choke-feed, cone-speed and reduction-ratio settings, cone crushers will efficiently produce material that is high quality and cubical in nature. In secondary stages, a standard-head cone is usually specified. A short-head cone is typically used in tertiary and quaternary stages. Cone crushers can crush stone of medium to very hard compressive strength as well as abrasive stone.

The vertical shaft impact crusher (or VSI) has a rotating shaft that runs vertically through the crushing chamber. In a standard configuration, the VSIs shaft is outfitted with wear-resistant shoes that catch and throw the feed stone against anvils that line the outside of the crushing chamber. The force of the impact, from the stone striking the shoes and anvils, fractures it along its natural fault lines.

VSIs also can be configured to use the rotor as a means of throwing the rock against other rock lining the outside of the chamber through centrifugal force. Known as autogenous crushing, the action of stone striking stone fractures the material. In shoe-and-anvil configurations, VSIs are suitable for medium to very hard stone that is not very abrasive. Autogenous VSIs are suitable for stone of any hardness and abrasion factor.

Roll crushers are a compression-type reduction crusher with a long history of success in a broad range of applications. The crushing chamber is formed by massive drums, revolving toward one another. The gap between the drums is adjustable, and the outer surface of the drum is composed of heavy manganese steel castings known as roll shells that are available with either a smooth or corrugated crushing surface.

Double roll crushers offer up to a 3-to-1 reduction ratio in some applications depending on the characteristics of the material. Triple roll crushers offer up to a 6-to-1 reduction. As a compressive crusher, the roll crusher is well suited for extremely hard and abrasive materials. Automatic welders are available to maintain the roll shell surface and minimize labor expense and wear costs.

These are rugged, dependable crushers, but not as productive as cone crushers with respect to volume. However, roll crushers provide very close product distribution and are excellent for chip stone, particularly when avoiding fines.

Hammermills are similar to impact crushers in the upper chamber where the hammer impacts the in-feed of material. The difference is that the rotor of a hammermill carries a number of swing type or pivoting hammers. Hammermills also incorporate a grate circle in the lower chamber of the crusher. Grates are available in a variety of configurations. The product must pass through the grate circle as it exits the machine, insuring controlled product sizing.

Hammermills crush or pulverize materials that have low abrasion. The rotor speed, hammer type and grate configuration can be converted for different applications. They can be used in a variety of applications, including primary and secondary reduction of aggregates, as well as numerous industrial applications.

Virgin or natural stone processing uses a multi-stage crushing and screening process for producing defined aggregate sizes from large lumps of rock. Such classified final fractions are used as aggregates for concrete, asphalt base, binder and surface course layers in road construction, as well as in building construction. The rock is quarried by means of drilling and blasting. There are then two options for processing the bulk material after it has been reduced to feeding size of the crushing plant: mobile or stationary plants.

When stone is processed in mobile primary crushing plants, excavators or wheel loaders feed the rock into the crusher that is set up at the quarry face, gravel pit or in a recycling yard or demolition site. The crushed material is then either sent to the secondary/tertiary processing stage via stacking conveyors or transported by trucks. Some mobile crushers have an independent secondary screen mounted on the unit, effectively replacing a standalone screen.

The higher the compressive strength of rock, the higher also is its quality, which plays an important role particularly in road construction. A materials compressive strength is delineated into hard, medium-hard or soft rock, which also determines the crushing techniques used for processing to obtain the desired particle sizes.

The materials quality is influenced significantly by particle shape. The more cubic-shaped the individual aggregate particles are, the better the resulting particle interlock. Final grains of pronounced cubic shape are achieved by using several crushing stages. A cubicity showing an edge ratio of better than 1-to-3 is typical of high-quality final aggregate.

As the earths natural resources are becoming ever more scarce, recycling is becoming ever more important. In the building industry, recycling and reuse of demolition concrete or reclaimed asphalt pavement help to reduce the requirements for primary raw materials. Mobile impact and jaw plants are uniquely positioned to produce high-quality reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA) for reuse in pavements, road bases, fill and foundations.

Use of RAP and RCA is growing dramatically as road agencies accept them more and more in their specs. But because RAP and RCA come from a variety of sources, to be specified for use by most departments of transportation they must be processed or fractionated and characterized into an engineered, value-added product. RCA or RAP are very commonly crushed and screened to usable sizes often by impact crushers and stored in blended stockpiles that can be characterized by lab testing for use in engineered applications.

Impact crushers are increasingly used for crushing recycling material. Impact crushers are capable of producing mineral aggregate mixes in one single crushing stage in a closed-cycle operation, making them particularly cost-effective. Different crusher units can alternatively be combined to process recycling material. A highly efficient method of processing recycling material combines crushing, screening and separation of metals. To produce an end product of even higher quality, the additional steps of washing to remove light materials such as plastics or paper by air classification and via electromagnetic metal separator are incorporated into the recycling process.

Mobile impact crushers with integrated secondary screens or without integrated screen used in conjunction with an independent mobile screen are ideal for producing large volumes of processed, fractionated RAP or RCA on a relatively small footprint in the plant. Mobile impactors are especially suited for RAP because they break up chunks of asphalt pavement or agglomerations of RAP, rather than downsize the aggregate gradation. Compression-type crushers such as jaws and cones can clog due to packing (caking) of RAP when the RAP is warm or wet.

Contaminants such as soil are part of processing demolition concrete. Mobile impact and jaw crushers when possessing integrated, independent prescreens removing dirt and fines before they ever enter the crushing circuit reduce equipment wear, save fuel, and with some customers, create a salable fill byproduct. A lined, heavy-duty vibrating feeder below the crusher can eliminate belt wear from rebar or dowel or tie bar damage. If present beneath the crusher, this deflector plate can keep tramp metal from degrading the conveyor belt. That way, the feeder below the crusher not the belt absorbs impact of rebar dropping through the crusher.

These mobile jaw and impact crushers may feature a diesel and electric-drive option. In this configuration, the crusher is directly diesel-driven, with the conveyor troughs, belts and prescreen electric-driven via power from the diesel generator. This concept not only reduces diesel fuel consumption, but also results in significantly reduced exhaust emissions and noise levels. This permits extremely efficient operation with low fuel consumption, allowing optimal loading of the crusher.

Jaw crushers operate according to the principle of pressure crushing. The raw feed is crushed in the wedge-shaped pit created between the fixed crusher jaw, and the crusher jaw articulated on an eccentric shaft. The feed material is crushed by the elliptic course of movement and transported downwards. This occurs until the material is smaller than the set crushing size.

Jaw crushers can be used in a wide range of applications. In the weight class up to 77 tons (70 metric tons), they can be used for both virgin stone and recycled concrete and asphalt aggregates processing as a classic primary crusher for natural stone with an active double-deck grizzly, or as a recycling crusher with vibrating discharge chute and the crusher outlet and magnetic separator.

Output for mobile jaw crushers ranges from 100 to 1,500 tph depending on the model size and consistency of the feed material. While larger mobile crushers produce more aggregate faster, transport weights and dimensions may limit how easily the crusher can be shipped long distances. Mobile jaw crushers can have either a vibratory feeder with integrated grizzly, or a vibrating feeder with an independent, double-deck, heavy-duty prescreen. Either way, wear in the system is reduced because medium and smaller gradations bypass the crusher, with an increase in end-product quality because a side-discharge conveyor removes fines. A bypass flap may provide easy diversion of the material flow, eliminating the need for a blind deck.

Jaw crusher units with extra-long, articulated crusher jaws prevent coarse material from blocking while moving all mounting elements of the crusher jaw from the wear area. A more even material flow may be affected if the transfer from the prescreen or the feeder trough is designed so material simply tilts into the crushing jaw.

Mobile jaw and impact crushers alike can be controlled by one operator using a handheld remote. The remote also can be used to move or relocate the crusher within a plant. In other words, the crusher can be run by one worker in the cab of an excavator or loader as he feeds material into the crusher. If he sees something deleterious going into the hopper, he can stop the crusher.

Impact crushing is totally different from pressure crushing. In impact crushing, feed material is picked up by a fast moving rotor, greatly accelerated and smashed against an impact plate (impact toggle). From there, it falls back within range of the rotor. The crushed material is broken again and again until it can pass through the gap between the rotor and impact toggle.

A correctly configured mobile jaw or impact crusher will enhance material flow through the plant and optimize productivity. New-design mobile jaw and impact crushers incorporate a highly efficient flow concept, which eliminates all restriction to the flow of the material throughout the entire plant. With this continuous-feed system, each step the material goes through in the plant is wider than the width of the one before it, eliminating choke or wear points.

For example, a grizzly feeder can be wider than the hopper, and the crusher inlet wider than the feeder. The discharge chute under the crusher is 4 inches wider than the inner width of the crusher, and the subsequent discharge belt is another 4 inches wider than the discharge chute. This configuration permits rapid flow of crushed material through the crusher. Also, performance can be significantly increased if the conveying frequencies of the feeder trough and the prescreen are adapted independently to the level of the crusher, permitting a more equal loading of the crushing area. This flow concept keeps a choke feed to the crusher, eliminating stops/starts of the feed system, which improves production, material shape and wear.

Users are focused on cost, the environment, availability, versatility and, above all, the quality of the end product. Simple crushing is a relatively easy process. But crushing material so that the particle size, distribution and cleanliness meet the high standards for concrete and asphalt requires effective primary screening, intelligent control for optimal loading, an adjustable crusher with high drive output, and a screening unit with oversize return feed.

This starts with continuous flow of material to the crusher through a variable-speed control feeder. Having hopper walls that hydraulically fold integrated into the chassis makes for quick erection of hopper sides on mobile units. If available, a fully independent prescreen for either jaw or impact models offers the ability to effectively prescreen material prior to crushing this allows for product to be sized prior to crushing, as opposed to using a conventional vibrating grizzly. This has the added value of increasing production, reducing wear costs and decreasing fuel consumption.

This independent double-deck vibrating screen affects primary screening of fines and contaminated material via a top-deck interchangeable punched sheet or grizzly, bottom-deck wire mesh or rubber blank. Discharged material might be conveyed either to the left or to the right for ease of positioning. The independent double-deck vibrating prescreen improves flow of material to the crusher, reducing blockages and feed surges.

Modern electrical systems will include effective guards against dust and moisture through double-protective housings, vibration isolation and an overpressure system in which higher air pressure in the electrical box keeps dust out. Simple and logical control of all functions via touch panel, simple error diagnostics by text indicator and remote maintenance system all are things to look for. For crushing demolition concrete, look for a high-performance electro- or permanent magnet with maximum discharge capacity, and hydraulic lifting and lowering function by means of radio remote control.

For impact crushers, a fully hydraulic crusher gap setting with automatic zero-point calculation can speed daily set-up. Featured only on certain mobile impact crushers, a fully hydraulic adjustment capability of the crushing gap permits greater plant uptime, while improving quality of end product.

Not only can the crushing gap be completely adjusted via the touch panel electronic control unit, but the zero point can be calculated while the rotor is running. This ability to accurately set the crusher aprons from the control panel with automatic detection of zero-point and target-value setting saves time, and improves the overall efficiency and handling of the crusher. On these mobile impact crushers, the zero point is the distance between the ledges of the rotor and the impact plates of the lower impact toggle, plus a defined safety distance. The desired crushing gap is approached from this zero point.

While the upper impact toggle is adjusted via simple hydraulic cylinders, the lower impact toggle has a hydraulic crushing gap adjustment device, which is secured electronically and mechanically against collision with the rotor. The crushing gap is set via the touch screen and approached hydraulically. Prior to setting of the crushing gap, the zero point is determined automatically.

For automatic zero-point determination with the rotor running, the impact toggle moves slowly onto the rotor ledges until it makes contact, which is detected by a sensor. The impact toggle then retracts to the defined safe distance. During this procedure, a stop ring slides on the piston rod. When the zero point is reached, the locking chamber is locked hydraulically and the stop ring is thus fixed in position. The stop ring now serves as a mechanical detent for the piston rod. During the stop ring check, which is carried out for every crusher restart, the saved zero point is compared to the actual value via the electronic limit switch. If the value deviates, a zero-point determination is carried out once again.

These impact crushers may feature a new inlet geometry that allows even better penetration of the material into the range of the rotor. Also, the wear behavior of the new C-form impact ledges has been improved to such an extent that the edges remain sharper longer, leading to improved material shape.

The machines come equipped with an efficient direct drive that improves performance. A latest-generation diesel engine transmits its power almost loss-free directly to the crushers flywheel, via a fluid coupling and V-belts. This drive concept enables versatility, as the rotor speed can be adjusted in four stages to suit different processing applications.

Secondary impact crushers and cone crushers are used to further process primary-crushed aggregate, and can be operated with or without attached screening units. These crushers can be used as either secondary or tertiary crushers depending on the application. When interlinked to other mobile units such as a primary or screen, complicated technical processing can be achieved.

Mobile cone crushers have been on the market for many years. These machines can be specially designed for secondary and tertiary crushing in hard-stone applications. They are extraordinarily efficient, diverse in application and very economical to use. To meet the diverse requirements in processing technology, mobile cone crushing plants are available in different sizes and configurations. Whether its a solo cone crusher, one used in addition to a triple-deck screen for closed-loop operation, or various-size cone crushers with a double-deck screen and oversize return conveyor, a suitable plant will be available for almost every task.

Mobile cone crushers may be available with or without integrated screen units. With the latter, an extremely efficient triple-deck screen unit may be used, which allows for closed-loop operation and produces three final products. Here the screen areas must be large so material quantities can be screened efficiently and ensure that the cone crusher always has the correct fill level, which is particularly important for the quality of the end product.

Mobile, tracked crushers and screen plants are advancing into output ranges that were recently only possible using stationary plants. Previously, only stationary plants were used for complicated aggregate processing applications. But thanks to the advancements made in machine technology, it is becoming increasingly possible to employ mobile technology for traditional stationary applications.

Mobile crushers are used in quarries, in mining, on jobsites, and in the recycling industry. These plants are mounted on crawler tracks and can process rock and recycling material, producing mineral aggregate and recycled building materials respectively for the construction industry. A major advantage of mobile crushers is their flexibility to move from one location to the next. They are suitable for transport, but can also cover short distances within the boundaries of their operating site, whether in a quarry or on the jobsite. When operating in quarries, they usually follow the quarry face, processing the stone directly on site.

For transport over long distances to a new location or different quarry, mobile crushers are loaded on low trailers. No more than 20 minutes to an hour is needed for setting the plant up for operation. Their flexibility enables the mobile crushers to process even small quantities of material with economic efficiency.

Mobile plants allow the combination of prescreening that prepares the rock for the crushing process and grading, which precisely separates defined aggregate particle sizes into different end products to be integrated with the crushing unit into one single machine. In the first stage, the material is screened using an active prescreen. After prescreening, it is transferred to the crusher, from where it is either stockpiled via a discharge conveyor or forwarded to a final screen or a secondary crushing stage. Depending on the specified end product, particles are then either graded by screening units or transported to additional crushing stages by secondary or tertiary impact crushers or cone crushers. Further downstream screening units are used for grading the final aggregate fractions.

The process of prescreening, crushing and grading is a common operation in mobile materials processing and can be varied in a number of ways. Mobile crushers with up to three crushing stages are increasingly used in modern quarries. Different mobile crushing and screening plants can be combined for managing more complex crushing and screening jobs that would previously have required a stationary crushing and screening plant.

Interlinked mobile plants incorporate crushers and screens that work in conjunction with each other, and are coordinated in terms of performance and function. Mining permits are under time constraints and mobile plants provide faster setup times. They provide better resale value and reusability, as mobile plants can also be used individually. They also reduce operating costs in terms of fewer haul trucks and less personnel.

With a so-equipped mobile crusher, the feed operator can shut the machine down or change the size of the material, all using the remote control, or use it to walk the crusher from one part of the site to the other, or onto a flat bed trailer for relocation to a different quarry or recycling yard. This reduces personnel and hauling costs compared to a stationary plant. With the mobile jaw or impact primary crusher, the only additional personnel needed would be a skid-steer operator to remove scrap steel, and someone to move the stockpiles.

Thanks to better technology, mobile plants can achieve final aggregate fractions, which previously only were possible with stationary plants. Production availability is on par with stationary plants. Theyre applicable in all quarries, but can be used for small deposits if the owner has several quarries or various operation sites. For example, an operator of several stone quarries can use the plants in changing market situations at different excavation sites. In addition, they also can be used as individual machines. A further factor is that mobile plants, in general, require simpler and shorter licensing procedures.

The high cost of labor keeps going up. A stationary crusher might be able to produce multiple times the amount of product, but also would require about seven or eight workers. Aggregate producers can benefit when producing material with the minimized crew used for mobile jaw and impact crushers.

Using correct maintenance practices, mobile crushers will remain dependable throughout their working life. Crushing and processing material can result in excessive wear on certain components, excessive vibration throughout the plant, and excessive dust in the working environment. Some applications are more aggressive than others. A hard rock application is going to require more maintenance on top of standard maintenance, as there will be more vibration, more dust and more wear than from a softer aggregate.

Due to the nature of its purpose, from the moment a mobile crusher starts, the machine is wearing itself out and breaking itself down. Without routine, regular maintenance and repair, a mobile crusher will not be reliable nor provide the material customers demand.

The first area of wear on any machine is the feed system. Whether its a feeder with an integrated grizzly, or a feeder with an independent prescreen, how the machine is fed contributes to wear. When setting up and maintaining a machine, the machine must be level. A machine that is unlevel left to right will experience increased wear on all components, including the feeder, the screens, the crushing chambers and the conveyor belts. In addition, it reduces production and screening efficiency, as the whole area of the machine is not being effectively used. Also, having the machine sit high at the discharge end will have the effect of feeding the material uphill in the feeder and reducing its efficiency, thus reducing production.

Another area for consideration is the equipment used to feed the machine. The operator using a loader to feed the crusher will have no control over the feed size, as he cannot see whats in the bucket. Whereas with an excavator, the operator can see whats inside and has more control over the feed into the hopper. That is, the operator is not feeding so much material all at once and is controlling the size of the feed. This reduces wear in the feed hoppers impact zones and eliminates material blockages due to feed size being too large to enter the chamber.

Dust is a problem in its own right, especially for the power plant of the mobile crusher. In a very dusty application, it is easy to plug the radiator and have engine-overheating problems. High dust levels cause increased maintenance intervals on air filters, and if not controlled properly, can enter the diesel tank and cause problems with the fuel system. Also, dust that gets inside the crusher increases wear. But if systems are put in place to remove the dust, it should keep it from going into the machine in the first place.

Dust also is a hazard on walkways and a problem for conveyors. If maintained, side-skirting and sealing the conveyors keeps dust from spilling out, building up underneath the conveyor, or building up in rollers, pulleys, bearings, and causing wear on shafts. Its important to maintain the sealing rubbers on the conveyor belts to avoid those issues. Routine maintenance calls for removing accumulated dust from inside and under the machine.

Dust also is a problem for circuit boards and programmable controllers. Dust causes electrical switches to malfunction because it stops the contacts from correctly seating. Electrical systems under positive air pressure dont permit dust to penetrate the control system. In control panels with a correctly maintained positive pressure system, filters remove dust from air that is being pumped into the cabinets. If the filters are plugged, the system will not pull as much air through, allowing dust, moisture and heat to build in the cabinet.

There are also impact aprons against which the rock is thrown, which also see high wear. There are side plates or wear sheets on the sides of the machine. The highest wear area is around the impact crusher itself, around the circumference of the rotor. If not maintained, the wear items will wear through and compromise the structure of the crusher box.

Conduct a daily visual check of the machine. The jaw is simple; just stand up on the walkway and take a look down inside. A crushers jaw plate can be flipped so there are two sides of wear on them. Once half the jaw is worn out, flip it; once that side is worn, change it.

The impact crusher will have an inspection hatch to see inside. Check to see how much material is left on the blow bars and how much is left on the wear sheets on the side of the crusher box. If half the bar is worn out after one week, change the blow bars in another week.The frequency of changes depends entirely on the application and the rock that is being crushed.

They have to be user serviceable, user friendly, and able to be changed in a short time. The best way to change these parts is a service truck with a crane; some use excavators but thats not recommended by any means.

After initial blasting, breakers are used to break down aggregate that typically is not only too large to be hauled in dump trucks, but also too large for crushers that size rock to meet asphalt, drainage system, concrete and landscaping specifications. Breakers can be mounted to a mobile carrier, such as an excavator, or to stationary boom systems that can be attached to a crusher. The total number of hydraulic breakers can vary from site to site depending on production levels, the type of aggregate materials and the entire scope of the operation.

Without hydraulic breakers, workers rely on alternative practices that can quickly affect production rates. For instance, blasting mandates shutting down operations and moving workers to a safe location. And when you consider how many times oversize aggregate might need to be reduced, this can lead to a significant amount of downtime and substantially lower production rates.

Aggregate operations can use hydraulic breakers to attack oversize without having to clear the quarry. But with an ever-growing variety of manufacturers, sizes and models to choose from, narrowing the decision to one hydraulic breaker can be overwhelming with all of the stats and speculation. Thats why its important to know what factors to consider before investing in a new hydraulic breaker.

In most cases, heavy equipment dealers are very knowledgeable about quarry equipment, including breakers, so they are a good resource for finding the best model for a carrier, usually an excavator or stationary boom system. More than likely, they will have specifications and information about various breaker sizes to help gauge what model is best. But being familiar with what to look for in a breaker can streamline the selection process.

The best places to look for breaker information are in the manufacturers brochure, website, owners manual or catalogue. First, carefully review the carrier weight ranges. A breaker that is too big for the carrier can create unsafe working conditions and cause excessive wear to the carrier. An oversized breaker also transmits energy in two directions, toward the aggregate and through the equipment. This produces wasted energy and can damage the carrier. But using a breaker thats too small puts excessive force on the tool steel, which transmits percussive energy from the breaker to the material. Using breakers that are too small also can damage mounting adapters and internal components, which considerably decreases their life.

Once you find a breaker that meets the carriers capacity, check its output power, which is typically measured in foot-pounds. Foot-pound classes are generalizations and are not based on any physical test. Often the breakers output will be documented in one of two ways: as the manufacturers calculated foot-pound class or as an Association of Equipment Manufacturers measured foot-pound rating. Foot-pound class ratings can be deceiving since they are loosely based on the breakers service weight and not the result of any physical test. The AEM rating, on the other hand, measures the force a breaker exerts in a single blow through repeatable and certified testing methods. The AEM rating, which was developed by the Mounted Breaker Manufacturers Bureau, makes it easier to compare breaker models by reviewing true figures collected during an actual test procedure.

For instance, three breaker manufacturers might claim their breakers belong in a 1,000-lb. breaker class. But AEM testing standards could reveal all three actually have less foot-pound impact. You can tell if a breaker has been AEM tested if a manufacturer provides a disclosure statement or if the breaker is labeled with an AEM Tool Energy seal. If you cannot find this information, contact the manufacturer. In addition to output energy specifications, manufacturers often supply estimates for production rates on different types of aggregate material. Make sure to get the right measurements to make the best decision.

In addition to weight and output power, look at the breakers mounting package. Two things are crucial for mounting a breaker to a carrier: a hydraulic installation kit and mounting components. Breakers need hydraulic plumbing with unidirectional flow to move oil from the carrier to the breaker and back again. A one-way flow hydraulic kit is sufficient to power the breaker as long as the components are sized to properly handle the required flows and pressures. But, consider a bidirectional flow hydraulic kit if you plan to use the same carrier with other attachments that require two-way flow. Check with the dealer or breaker manufacturer to determine which hydraulic package best fits current and future needs.

Hydraulic flow and pressure specifications also need to be considered when pairing a breaker to a hydraulic system. If the carrier cannot provide enough flow at the right pressure, the breaker wont perform with maximum output, which lowers productivity and can damage the breaker. Additionally, a breaker receiving too much flow can wear quickly, which reduces its service life. For the best results, follow the hydraulic breaker specifications found in owners manuals, catalogs and brochures. Youll find out if a breaker has additional systems that might require additional servicing. For instance, some breakers feature nitrogen gas-assist systems that work with the hydraulic oil to accelerate the breakers piston. The nitrogen systems specifications need to be followed for consistent breaker power output.

Brackets or pin and bushing kits are commonly required to attach the breaker to the carrier. Typically they are bolted to the top of a breaker and are configured to match a specific carrier. Some manufacturers make universal mounting brackets that can accommodate two or three different sizes of carriers. With the adjustable pins, bushings or other components inside these universal brackets, the breaker can fit a range of carriers. However, varying distances between pin centers can complicate hookups to quick coupling systems. In addition, loose components, such as spacers, can become lost when the breaker is not in use and detached from the carrier.

Some carriers are equipped with quick-coupling systems, which require a breakers mounting interface to be configured like the carriers original attachment. Some manufacturers produce top-mount brackets that pair extremely well with couplers. This allows an operator to use the original bucket pins from the carrier to attach the breaker, and eliminates the need for new pins. This pairing also ensures a fast pickup with the quick coupler.

Its also a good idea to check which breaker tools are available through the dealer and manufacturer. The most common for aggregate mining are chisels and blunts. There are two kinds of chisels commonly used in aggregate mines: crosscut and inline. Both chisels resemble a flat head screwdriver, but the crosscut chisels are used when carrier operators want to direct force in a left-to-right concentration; whereas, inline chisels direct force fore and aft. With chisel tools, operators can concentrate a breakers energy to develop cracks, break open seams or define scribe lines.

If a chisel cant access or develop a crack or seam, a blunt can be used. Blunts have a flattened head that spreads the energy equally in all directions. This creates a shattering effect that promotes cracks and seam separation. Ask your dealer if the tools you are considering are suited for the application. Using non-original equipment manufacturer tool steel can damage the percussive piston in the breaker, seize into the wear bushings, or cause excessive wear.

Regular breaker maintenance is necessary, yet its one of the biggest challenges for aggregate operations. It not only extends the life of the breaker, but also can keep minor inconveniences from turning into expensive problems. Some manufacturers recommend operators inspect breakers daily to check grease levels and make sure there are no worn or damaged parts or hydraulic leaks.

Breakers need to be lubricated with adequate amounts of grease to keep the tool bushing area clear and reduce friction, but follow the manufacturers recommendations. For example, adding grease before properly positioning the breaker can lead to seal damage or even catastrophic failure. And too little grease could cause the bushings to overheat, seize and damage tools. Also, manufacturers advise using high-moly grease that withstands working temperatures greater than 500 degrees. Some breakers have automatic lube systems that manage grease levels, but those systems still need inspections to ensure there is adequate grease in their vessels. Shiny marks on the tool are a good indication the breaker is not properly lubricated.

Little has changed in basic crusher design over past decades, other than that of improvements in speed and chamber design. Rebuilding and keeping the same crusher in operation year after year has long been the typical approach. However, recent developments have brought about the advent of new hydraulic systems in modern crusher designs innovations stimulated by the need for greater productivity as well as a safer working environment. Importantly, the hydraulic systems in modern crusher designs are engineered to deliver greater plant uptime and eliminate the safety risks associated with manual intervention.

Indeed the crushing arena is a hazardous environment. Large material and debris can jam inside the crusher, damaging components and causing costly downtime. Importantly, manually digging out the crusher before repairs or restarts puts workers in extremely dangerous positions.

The Mine Safety and Health Administration has reported numerous injuries and fatalities incurred when climbing in or under the jaw to manually clear, repair or adjust the typical older-style jaw crusher. Consider that fatalities and injuries can occur even when the machine is locked out and tagged out. Recent examples include a foreman injured while attempting to dislodge a piece of steel caught in the primary jaw crusher. Another incident involved a fatality when a maintenance man was removing the toggle plate seat from the pitman on a jaw crusher. The worker was standing on a temporary platform when the bolts holding the toggle seat were removed, causing the pitman to move and strike him.

The hydraulic systems on modern crusher designs eliminate the need for workers to place themselves in or under the crusher. An overview of hydraulic system technology points to these three key elements:

A hydraulic chamber-clearing system that automatically opens the crusher to a safe position, allowing materials to pass. A hydraulic overload relief that protects parts and components against overload damage. A hydraulic adjustment that eliminates the maintenance downtime associated with manual crusher adjustments, and maintains safe, consistent crusher output without the need for worker intervention.

Whether a crusher is jammed by large material, tramp iron or uncrushable debris; or is stalled by a power failure the chamber must be cleared before restarting. Manual clearing is a lengthy and risky task, especially since material can be wedged inside the crusher with tremendous pressure, and dislodging poses much danger to workers placed in harms way inside the crusher.

Unlike that of the older-style jaw, the modern jaw will clear itself automatically with hydraulics that open the crusher to a safe position, and allow materials to pass again, without the need for manual intervention. If a feeder or deflector plate is installed under the crusher, uncrushable material will transfer smoothly onto the conveyor without slicing the belt.

To prevent crusher damage, downtime and difficult maintenance procedures, the hydraulic overload relief system opens the crusher when internal forces become too high, protecting the unit against costly component failure. After relief, the system automatically returns the crusher to the previous setting for continued crushing.

The modern crusher is engineered with oversized hydraulic cylinders and a traveling toggle beam to achieve reliable overload protection and simple crusher adjustment. All closed-side setting adjustments are made with push-button controls, with no shims being needed at any time (to shim is the act of inserting a timber or other materials under equipment). This is a key development as many accidents and injuries have occurred during shim adjustment, a process which has no less than 15 steps as described in the primary crusher shim adjustment training program offered by MSHA.

crushing equipment selection

In open pitquarry operations the loading of the blasted rock for transportation to the primary crusher house involves either power-shovels. Any size of primary crusher may be used for hand-loaded rock; it all depends upon how much secondary shooting, and hand sledging, the operator feels he can afford. So called one-man stone or stone of a size that can be lifted into small cars or carts by the average laborer can be handled through a 10 or 13 gyratory crusher, or a jaw crusher of equivalent receiving opening. Usually, for hand-loading operations, capacity and product size govern the choice of the primary crusher. The unit labor cost of feeding hand-loaded stone is higher for small crushers than it is for larger machines but, if the labor market is such as to permit hand-loading in the quarry, a little additional labor at the crusher will not add materially to the cost of production.

In the American quarry, gravel pit, and open-cut mine, the power shovel, supplemented to a lesser extent by other types of excavating equipment, has, within the last forty years, practically eliminated hand loading. Today, in these operations the power shovel is just as necessary as the crushing plant. In any quarrying or open-pit mining operation the primary crusher, shovel, and transportation equipment should function as a team; therefore these three items of equipment, when possible, should be considered as complements of each other when making selections. This is especially important with respect to the crusher and the shovel.

It has been customary for writers on this subject to tabulate a list of shovel dipper sizes and opposite these to list sizes of gyratory and jaw crushers that are considered to be suitable for operating in conjunction with power shovels equipped with such sizes of dippers. This is a little like putting the cart before the horse. The procedure omits one very essential factor: the character of the material that is to be crushed. For example, most limestone deposits are stratified, the cleavage planes usually being roughly parallel, and ranging anywhere from horizontal to almost vertical.

Regardless of how these strata lie, their thickness not only has an important bearing upon the type and size of primary crusher that can be expected to handle the rock with a minimum amount of secondary shooting, or bridging and blocking, but it also has a bearing upon the maximum size of shovel dipper that is suited for use in conjunction with a certain size of primary crusher. This statement is particularly applicable to the gyratory crusher because of the shape of its receiving openings. Two or three different maximum dipper sizes may be indicated for any one size of gyratory, depending upon the maximum strata thickness. In the case of the jaw crusher, with its rectangular opening, maximum dipper width and maximum strata thickness are established simply by the opening dimensions, and one maximum size dipper applies for each machine.

Gyratory Crushers Size and FittingsMaximum Thickness of Strata in Quarry in Inches. 12 8 20-in. Straight Concaves 1.51 1/4 20-in. Non-Choking Concaves1.75 30-in. Straight Concaves 2 1/21.75 30-in. Non-Choking Concaves2.51 1/2 36-in. Straight Concaves 4 3/22.51.5 36-in. Non-Choking Concaves32 42-in. Straight Concaves 4.531.5 42-in. Non-Choking Concaves4 1/242.5 50-in. Straight Concaves 4.532.5 54-in. Straight Concaves 4.53 60-in. Straight Concaves 4.53 Jaw Crushers Straight Jaw Plates 42 x 30 in.1.5 42 x 40 in.1.33333333333 48 x 36 in.2 60 x 48 in.2.5 84 x 60 in. 4.5 84 x 66 in.4.5

This table takes both dipper width and strata thickness into consideration. Opposite each listed size of gyratory crusher is tabulated the maximum advisable size of dipper, in cubic yards, for the different strata thicknesses up to the thickest ledge for which each crusher is suitable; that is, which it can be expected to handle with a minimum amount of secondary blasting. Crushers up to and including the 42 machine are listed with both straight and non-choking concaves. Six sizes of jaw crushers are listed, the dipper sizes for each having been chosen as outlined in the preceding paragraph. These dipper selections are of course predicated upon the assumption that the dipper is expected to act as a a measuring stick for the crusher, which necessarily presupposes that all rock will be passed through the dipper; a procedure that is rarely followed completely in any quarry operation. The experienced shovel runner soon learns how to judge the rock he is loading, with respect to the size and shape of the receiving opening it must enter, and a certain amount of shuffling off of the dipper teeth goes on in most quarries.

Admittedly no tabulation of this sort can substitute for actual experience with any particular rock or ore deposit. Some deposits which are of monolithic structure, and hence might be expected to shoot out in massive form, are readily shattered into workable sizes in the primary blasting operation; on the other hand, some stratified rocks shoot out in large slabs, which require either a large primary receiving opening, or a considerable amount of secondary shooting, or both. For those cases where no operational data are available to point the way, the table will serve as a guide that is believed to be on the safe side.

No particular problem exists in the matching of primary crusher and dipper size in the average gravel pit operation. The primary crusher is chosen on the basis of capacity (usually arrived at by estimating as closely as possible the percentage of boulders in the deposit), and receiving opening (as large as is consistent with the size of the operation), which may or may not involve crushing all of the boulders encountered in the bed of material. Quite frequently, in small or medium gravel operations, the larger boulders are cast aside and left in the pit.

The question of first cost of the crusher versus continued cost of disposing of oversize boulders is one that each gravel pit operator must settle to his own satisfaction. Most gravel pit operations involving the handling of large boulders incorporate some form of grizzly ahead of the primary crusher to stop out any boulders that are too large to enter the receiving opening. Therefore, the shovel dipper can generally be selected on the basis of required capacity. If the boulders are extremely large, and the plant capacity is high enough to justify the installation of a large primary crusher, the grizzly may be dispensed with, and the shovel dipper matched to the crusher receiving opening in the same manner as for the quarry.

The size and type of transportation equipment in the quarry, pit, or mine should be coordinated with the primary crusher and with the proposed method of feeding this machine. It is not our purpose to discuss the selection of quarry equipment, other than to point out the ways in which different types and sizes of transportation equipment may affect the operation at the primary crusher house. It is difficult to deal with this subject in precise terms, because the factors involved are so variable, but a few general statements about what is, and what is not, considered to be sound practice may serve to point in the right direction, even if they do not give the exact distance. Except for those rare cases where the size of the primary crusher receiving opening is greatly in excess of the size of the largest pieces of rock to be fed to it, the amount of material dumped into it at one time should not be much more than to fill the crushing chamber; otherwise, if blocking or hridging occurs, the time consumed in clearing the receiving opening is bound to be excessive. Therefore, if quarry cars of the quick-dumping type are to be used, their size should be selected with a . view to preventing such a condition. For the average quarry operation the following table will serve as an approximate guide in establishing the maximum size of quick-dumping car that should be used to feed different sizes of gyratory crushers:

Crusher SizeCar Capacity 20 in.4-5 tons 30 in.6-8 tons 36 in. 8-10 tons 42 in.8-10 tons 50 in.10-12 tons 54 in.12-15 tons 60 in.15-20 tons If there are only occasional pieces in the feed that exceed about one- half the smallest dimension of the crusher receiving opening, these car sizes may be increased as much as 25 percent. They may of course be exceeded considerably in mining operations where there is a high percentage of undersize which is grizzlied out ahead of the crusher.

Generally speaking, jaw crushers should not be fed from quick-dumping cars unless the receiving opening is large enough to virtually eliminate any danger of bridging. Because the receiving opening of this type of crusher is relatively narrow, it is almost always necessary to use a flared hopper above it to receive the feed from the car or truck, the hopper may be two or three times as long as the receiving opening is wide. This means that the material must converge as it flows or falls toward the receiving opening, and this confluence is a natural invitation to bridging if a large amount of rock is dumped quickly into the hopper.

Controlled-dumping, used in conjunction with side-hinged cars and incorporated in all modern quarry trucks, permits the use of larger equipment. While it does not entirely eliminate bridging, it materially lessens the likelihood of its occurrence by the simple method of holding back part of the load until the crusher has a chance to clear itself of the other part.

Controlled-dumping works out well with any type of primary crusher. While it does not provide absolute control of- feed regulation, it is, next to the mechanical feeder, the best means of regulation for coarse material such as quarry-run or mine-run rock, certainly far superior to the quick-dumping car in this respect. It has one disadvantage: the time required to dump a load in two or more portions ties up the transportation equipment while the crusher is disposing of a considerable part of the original load. This tie-up is of no particular moment if the equipment consists of cars that are handled in trains of several units; for such operations the time-difference between quick- and controlled-dumping is negligible. On the other hand, if trucks are used, the aggregate idle time over an entire shift may add up to as much in the crusher house as it does at the shovel. Gyratory crushers, because of the greater volumes of their crushing chambers and their higher capacities, will usually function with less time-loss on this score than will comparable sizes of jaw crushers.

Car, skip, or truck bodies used for dumping directly into crushers of the jaw or single sledging roll types should be as short as is consistent with required capacity because of the relatively narrow receiving openings of these types. This will help to cut down congestion of material in the hopper above the crushing chamber, a tendency which we have mentioned in a preceding paragraph. Another point in favor of the short body is the saving in headroom between receiving opening and dump level. Somewhat longer bodies are permissible for gyratory crushers of comparable sizes because of the greater area and length of the receiving openings.

The ideal feeding arrangement for jaw crushers of any size is the mechanical feeder. This device, which has been developed in several forms, provides regulation as smooth as is possible to achieve in the handling of coarse materials; it permits instant shut-off of the flow of feed when blockades occur; it allows quick dumping of cars or trucks; and it delivers the feed to the crusher in a ribbon, the width of which can be adapted to the width of the receiving opening. For those installations employing grizzlies ahead of the crusher the advantage of the uniform flow is obvious; very short grizzlies will handle the coarse separation ordinarily required at this point, whereas grizzlies three or four times as long will generally be required if large amounts of material are dumped over them in a one-shot dose.

The mechanical feeder is of course an excellent device for feeding any type of primary crusher. Some type of feeder is used for such service in almost every gravel plant, at some point in the system at the shovel, under the surge pile, or immediately ahead of the crusher* depending upon the methods utilized in excavating and transporting the; pit-run gravel to the crushing plant. Feeders of the reciprocating plate type, steel apron type, and electromagnetic type are all popular for this duty. These types are also extensively used in conjunction with underground mining operations. For heavy-duty quarry or open-pit mining operations the heavy-duty steel apron feeder is the most practical type. It can be made in any length to fit in with any type and size of transportation equipment and crusher house arrangement. It has been developed in sizes to suit any size of primary crusher, and of proportions suitable for handling any rock that the largest sizes of crushers will take.

Because of their heavy construction these heavy-duty apron feeders add materially to the initial cost of the primary crusher installation; naturally they add something to the overall cost of maintenance and power. The question of whether or not this added expense is justified will depend upon conditions surrounding each particular installation. If the crusher has an ample margin of capacity over and above the plant requirements, as is often the case when it has been chosen from the standpoint of an amply large receiving opening, occasional delays due to bridging are not apt to be serious; and the shovel and transportation equipment, chosen to work with such a crusher, are usually capable of making up for any time-losses thus incurred.

For such operations it is questionable if the cost of the heavy feeder is justified. On the other hand, if the operation demands full-time, or nearly full-time, crushing to meet the plant requirements, the case for the feeder is clear cut from every standpoint, at least so far as the jaw crusher is concerned. For reasons which have been discussed, their use with gyratory crushers, especially the larger sizes, is debatable, unless, as is done in some large mining operations, the designer wishes to establish a surge or stockpile ahead of the primary crusher. To revert to the gravel and underground mining operations, now that vibrating screens of extra-heavy construction have been developed to handle large pieces of rock over their top deck, it is very probable that such screens will come to be used more and more as combination scalpers and feeders; a service for which they are admirably adapted. The advantage of being able to make a clean cut and definitely sized separation at this point will be of great value in many cases; and the high efficiency of the vibrating screen, as compared to the stationary bar grizzly, will appeal to those operators who want no undersize material in the feed to the primary crusher. The same idea in modified form, using smaller and lighter screens, can be applied to operations involving small rock and small crushers.

It is not within the province of this work to discuss methods of drilling and blasting of rock or ore other than to point out that the system employed at any particular operation may have some influence upon the choice of the primary crusher, specifically, upon the size of the receiving opening. The foregoing discussion of primary crusher selection, for open-pit workings, has been predicated upon normal present-day practice in primary drilling and blasting, which in most cases involves either the familiar well drill or some system of tunnel shooting.

Admittedly, any kind of rock, regardless of physical structure or geological formation, can be blasted to suit any size of crusher receiving opening. During the early years of the application of power shovels to quarry operations in this country it was not uncommon to see crushers as small as the No. 6 (12 receiving opening) operating in conjunction with shovels of 1.5 or 2 cubic yard dipper capacity; crushers such as the No. 8 (18) and No. 9 (21) were considered adequate for practically any primary crushing application within the ranges of their capacities.

Such operations almost invariably called for extensive secondary shooting in the quarry, even where the old tripod drills were employed for the primary drilling operation. They also necessitated the employment of from two to four men at the crusher to hand-feed the rock to the machine. Thus the labor and explosives costs were, in the light of present day practice, quite high, and with present day labor costs the expense of such a system of quarrying and crushing would be prohibitive.

Practically any open-pit operation will, over a period of years, justify the installation of a primary crusher of large enough proportions to permit carrying on the quarry operation with no more than a reasonable amount of secondary shooting. Quarrymen know that much can be done to minimize secondary shooting by adjusting primary drilling and blasting methods to suit the nature of the rock, but such expedients always involve an addition to the unit cost of operation; an expense that goes on and on through the life of the operation. The cost of providing an adequate receiving opening is a one-time expenditure, one that pays dividends over and over through the years.

The same argument may be carried on into the crusher house. If it costs $40,000 per year to maintain a man on the feed platform, simple arithmetic indicates that the maintenance of this man for a period of twenty years (a reasonable expectation for a crusher) will cost the operator some $800,000. Usually it will be found that the difference in first cost, between an inadequate and an adequate crusher, will be considerably less than this figure. The well designed modern primary crusher house should run with one man on the feed platform, with possibly a second man available on call to assist in emergencies.