Cement Crushers: Types, Selection & Operation

The crushers are the first machines of the cement plant and the gateway of the production: they take the blasted quarry rock, the blocks of up to 1,200 millimeters across, and reduce them to the sizes the mills can swallow: the jaw crusher, the gyratory, the cone, the impact and the hammer machines form the complete family of the coarse size reduction, and every cement plant runs at least two of them: the configuration of the crushing plant decides the feed sizes of the mills, the load of the conveyors and the top of the energy diagram: the crushers are the pit stop of the production.

The Complete Cement Technical Package (931 files including the books, the courses, the Excel tools and the presentations: $249.99 one-time: instant download via the PayPal payment) includes this crusher guide with its selection tables, the capacity diagrams, the maintenance schedules and the troubleshooting charts: this article walks the file: the types of the machines, their parameters, the operation, the wear, and the worked example of the sizing: the mud of the crushing department becomes the page of the order.

The crushing departments of the different plants look different because the deposits differ: the hard limestone of one quarry needs the jaw and the gyratory; the soft marl of another is handled by the hammer crusher alone; the clay content, the moisture and the abrasiveness of the rock decide the machine: this guide dissects the decision, so the engineer selects not by the habit but by the numbers: the bonded of the machine and the geology of the feed, the two fixed stars of the crushing design.

1. The Role of the Crushing Department and its Place in the Flowsheet

Crushing is the coarse half of the comminution: the size reduction from the blast size (300-1,200 millimeters) to the mill feed (minus 25 to minus 100 millimeters): the placement of the crusher in the plant usually follows the quarry: the primary crusher sits in the pit or at the edge of the quarry, the secondary and the tertiary stages group with the pre-blending or the mill:

• The balance of the belt: the continuous belt feeding the plant demands the uniform size: the crusher is the homogenizer of the lump size, and the stable setting gives the stable mill feed;
• The mill preconditioning: the smaller the crusher product, the cheaper the grinding: every extra millimeter of the crusher product costs kilowatt-hours in the raw mill: the sum of the sizes;
• The moisture gate: the crusher also dries partly: the impact hammers knock the moisture-bound clay and the sticky fines; the wet material changes the crusher choice completely;
• The surge and the stockpiles: the crusher stands before the prehomogenization piles: its availability is the availability of the entire upstream: the redundant spare of the primary is the doctrine of the large plant;

The crushing chain is the slow part of the plant: the mills can run on the stock, the quarry cannot stop: the crushing boom keeps the piles full and the process calm: the engineers of the plant therefore treat the crusher availability as the number one person of the operation, and the file documents this logic as the chapter of the plant design.

2. The Jaw Crusher: The Workhorse of the Primary Stage

The jaw crusher is the oldest and the most forgiving of the primary machines: a fixed jaw and a moving jaw, hinged at the top or the bottom, squeeze the rock between two steel plates in the alternated strokes: the product passes the closed-side setting at the bottom of the crushing chamber:

• The anatomy: the fixed plate, the movable plate, the toggle mechanism, the pitman and the flywheel: the flywheel stores the kinetic energy of a stroke: the eccentric shaft converts the rotating motion into the crushing stroke of 10-40 millimeters;
• The parameters: the feed opening from 600 by 400 millimeters in the small plants to 1200 by 1500 in the large: the closed-side setting (CSS) 75-200 mm at the primary: the reduction ratio 4:1 to 6:1: the speed of 180-300 revolutions per minute;
• The capacity: from 60 t/h in the laboratory machines up to 1,500 t/h in the monster primaries: the capacity rows in the catalogue of the manufacturer follow the curve of the CSS: the small close, the big open;
• The advantages: the calibrated simplicity, the low operability cost, the tolerant to the slabby rock and the tramp steel: the jaw crusher breaks anything, its power is its stubbornness;
• The disadvantages: the vibration and the shock, the periodic (stroke) production, the heavier foundations and the occasional maintenance of the toggle: the feed is the bottleneck by the lump size;

The jaw crusher serves the plants under about 1,500 tons per hour: it is the machine of the limestone, the basalt and the service life in the moderate range: the file gives the complete calculation of the throughput from the chamber geometry and the CSS, the stroke, the eccentric speed and the material density that the tables of the classic manufactures: the jaw’s simple principle makes its math the most complete of the family.

3. The Gyratory Crusher: The Continuous Giant of the Primary

Where the tonnage grows beyond the jaw, the gyratory takes the stage: the conical crushing head gyrates inside the flared chamber, compressing the rock continuously around the periphery, so the machine never pauses at the return stroke:

• The construction: the main shaft with the cone, the ring and the bridge spiders, the hydraulic support of the shaft: the crushing head of 900-2,700 millimeters, the feed openings up to 2,000 millimeters wide;
• The capacity: from 500 up to 6,000 tons per hour in the mineral industry records: the continuous action at the 100-600 rotations of the eccentric per minute;
• The parameters: the closed-side setting adjustable from 100 to 300 millimeters in the primary role and the course and fine settings in the secondary: the reduction 4 to 7 per stage;
• The advantages: the highest capacity for the footprint, the continuous discharge, the low vibration (the balanced kinematics), the low specific energy of about 0.4 kWh/t;
• The price: the highest capital cost of the primary family, the deep foundations similar to the silo, and the maintenance requiring the cranes: the gyrator owns the very large and the very rare plants;

The selection between the jaw and the gyr bail is written in the two terms of the file: the capacity and the foundation: under 1,500 t/h the jaw, over it the gyr: besides the economics of the capital and the interlude: the gyr is the longest-lived machine of the crushing department, and the file documents the maintenance of the armored mantle, the spider and the eccentric assembly, the costly parts that the plant budgets years in advance.

4. The Cone Crusher: The Master of the Secondary and the Tertiary

Below the primary, the cone crusher dominates the fine crushing in the hard-rock circuits: the same principle as the gyratory, but the apex of the head points upward and the chamber is shorter, so the machine delivers the fine, uniform products at the high speeds, the 600-900 centrifugal rotations:

• The parameters: the feed 40-300 mm, the product 5-60 mm: the CSS of 6-50 millimeters adjusted hydraulically in seconds: the eccentric throw of 10-40 mm and the speed determine the capacity curve;
• The capacity: from 80 t/h for the small tertiary units to over 1,000 t/h for the large secondary cones: the curves of the capacities are the appendix tables of the file;
• The hydroset: the hydraulic piston holds the spindle: the tramp metal and the unbreakable block push the piston down the sleeve, protect the bowl and the mantle, and the metal is released and the crushing resumes in minutes: the said self-protecting of the family;
• The shape control: the chamber profile (the coarse vs the fine GP) with the cubic product: the delaminated feed the blockie: the product shape is the symmetry of the next stage of the belt and the sealing;
• The role in cement: the cement plant uses the cone less than the aggregate industry: the limestone is mostly crushed by the hammers, but the plants with the basalt or the granite additions and the special aggregates run the cone fleets;

The water-tight physics of the cone: the CSS controls the top size, the eccentric controls the throughput, the shape of the chamber controls the finesse: these three levers are the entire lore of the cone: the file explains the influence of each on the power draw and the product curve, and the troubleshooting logic of the clogged or the hydrated bowls: the cone operator who masters the three levers is the master of the secondary stage.

5. The Impact Crusher: The Power of the Blow and its Limits

The impactor family breaks the rock by the kinetic impact of the rotating blow bars against the aprons: no compression, no jaw: just the violence of the speed: the impact brings the highest reduction ratios of the family per the stage at the cost of the wear:

• The construction: the rotor with the hammers or the blow bars, the two or three impact aprons around the rotor, and the discharge at the bottom: the rock is thrown at 30-50 meters per second against the aprons;
• The reduction: the single-stage impactors reduce the 300 mm feed to the 20-30 mm product: the ratio of 10:1 possible in the one machine, the highest of the traditional crushers;
• The products: the material mutates on the impacts so the product is cubic, cracked and open, ideal for the feeding of the vertical mills and the pre-hydrating;
• The great benefit: the rotor also unlocks the clay: the dry-impact hammer crusher in the cement industry combines the drying of the kiln gas, the 500-1,000 °C gas flow into the crusher, and the crushing in the single stage: the drying-grinding-crushing of the one machine;
• The limit: the abrasive wear: an abrasion index of the feed above 0.1 and the wear plates and the bars must be changed regularly: the chromium cast iron parts of 500-700 Brinell are the standard armor;

The impact family carries the specific energy of 0.5-1.5 kWh/t and the highest cooling: the rotor bars and the trajectory of the rock: the file gives the capacity tables as a function of the rotor diameter (1,000-2,500 mm), the rotor speed and the impact positions: the plant with the damp clay and the soft limestone reads the impact crusher chapter first.

6. The Hammer Crusher: The Single Stage of the Soft Stone

The hammer crusher is the cement industry’s favorite for the limestone: the single-machine reduction from the raw quarry rock to the finished mill feed in one pass, often with the integrated drying and blending circuits:

• The construction: the rotor with the free-hanging hammer rows, the crushing grating (the grid) below the rotor, the crushing plates at the sides: the rock smashed between the hammers and the aprons, the fines pass the grate;
• The parameters: the rotor widths of 1,000-2,500 mm, the capacities of 50-1,000 t/h, the feed of up to 1,000-1,500 mm, the product set by the grate openings of 20-80 mm;
• The energy: 0.3-1.2 kWh/t for the single-pass drying: the finest energy of the whole crusher family with the high reduction in the one machine;
• The single-shaft vs the double: the double-rotor hammers double the capacity and the nominal power: the single-shaft machine is the standard for the cement raw;
• The drying: the kiln and the dedusting gas through the crusher dries the feed from 8-15% moisture to below 5% in the same shell: the dryer-crusher of the modern flows.

The hammers wear the arc like the saw blade: the rotation of the hammers (the refreshing of the working edge) extends the service life between the changeovers: the file carries the wear norms of the chromium steels and the budgets of the replacement: the hammer crusher is the most common individual crusher in the cement plant, so the file devotes its largest chapter to the rotor balancing, the anchor bolts and the replaceable tips.

7. The Roll Crushers and the Sizers: The Niche of the Stick

When the feed is wet, sticky and clay-dressed, the classic machines clog and the plant reaches for the low-speed roll crusher and the sizer family: the toothed rolls crawl at 0.5-2 meters per second and tear the material between the rolls, not crush it:

• The principle: the slow-turning rolls with the welded teeth: the rock enters the inter-roll gap and is forced down by the shear and the tensile, the cracks valued by the size of the teeth: sticky clay shreds instead of the chokes;
• The parameters: the roll diameters 500-2,000 mm, the widths to match the tonnage, the speed the lowest of the crushers (10-50 rpm), the product the same as the gap, the energy of 0.1-0.4 kWh/t;
• The advantages: the materials that want the iron frames of the APRON points, the excellent handling of the wet feed for the cement’s damming days, the compact drivetrains;
• The constraints: the small and medium reduction ratios, the uniform mistakes, the teeth wear in the soft rock: the primary-ish the sizers: the secondary

The roll-sizer family is the answer to the statistical question of the “What happens in the rainy season?”: the pit queue and the stockpile feed the plant on the sizer line while the hammer line rests: the file covers the selection between the conventional duty and the apron the sizers bring to the dry-process flowsheet, with the design example of the clay-heavy deposit.

8. The Selection Criteria: The Matrix of the Decision

The file that carries over 20 pages of the selection matrix distills its logic in the six rows, the order of importance:

• The feed size: the P80 of the quarry after the blasting: the largest block commands the crusher feed opening: the rule: the feed opening = 0.85 × the maximum lump: the belt disasters of the oversized;
• The tonnage: the designed t/h with the 1.15-1.25 safety factor: the capacity must rest the surge, else the pile empties and the kiln complains;
• The abrasiveness: the Bond abrasion index and the Bond work index: the abrasion above 0.1-0.15 prefers the compression machines (jaw, cone, gyr), the low values open the door to the impact and the hammer;
• The moisture and the clay: above 10% moisture with the clay fouls the jaw and the cone: the solver crushers or the dryer-hammers: the gate of the process climate;
• The product spec: the target product size and the cubic capacity: the cone turf and the impact cube; the binder: the mill types read the particle shape as the feed stability;
• The total cost: the capital, the energy (kWh/t), the wear and the maintenance: the sum of the plant period of the file: the matrix of the 4 columns and the 300 rows;

The decision matrix of the file puts the seven criteria side by side and scores the candidate machines: the jaw vs the gyr vs the hammer vs the sizer: the consultant answer the full-length spreadsheet with the scoring and the annualized cost: the September-long that the plants lease from the package in their project season, the same matrix the tender committee uses for the vendor description.

9. The Parameters of the Operation: The Closed-Side Setting and the Current

The daily control of the crusher happens in two numbers: the closed-side setting (CSS) and the motor current: and the file explains each lever:

• The CSS: the narrowest gap between the head and the bowl low: it defines the top size of the product: the smaller the CSS, the finer the product, the lower the capacity and the higher the power: the quadratic exchange;
• The motor current: the load feedback: the choke feeding (the crushing chamber full) gives the optimum of the power utilization and the least wear: the empty chamber clatters and wastes the power;
• The speed of the rotor (impactors): the peripheral speed of 25-50 meters/second sets the breakage of the rock and the wear rate of the bars: the speed down saves the wear, raises the top size: the premium of the sacrifice;
• The stroke and the throw (cones): the maximum stroke and the throw, the setting in the machine: the crushing chamber geometry tells the shape: 2-4 times the CSS is the thickness of the bed;

The CSS is measured with the lead the block dropped into the closed chamber, or by the modern level of the oil displacement in the hydraulic machines: the file records the CSS check as the weekly duty of the operator, because the drift of the kind of the CSS is the silent producer of the mill complaints: the calibration of the measuring device and the logbook of the setting: the discipline loop that gives the plant the stable pellet.

10. The Wear Parts and the Metallurgy: The Economy of the Steel

The crushers convert the rock into the smaller rock, and the wear parts pay for the privilege: the file documents the steel grades and their economics:

• The jaw liners: the manganese steels of the 12-14% Mn: the work-hardening of the working surface: the life 4-8 months at 200 t/h continuous: the flipping of the plates extends the life by the 30-60%;
• The cones: the manganese steel mantles and the Concaves: the choke zone is the wear hotspot: the replacement pattern of the pairs: the lifting the tromp; the hydraulic-nut crews the hour;
• The impact bars: the chromium alloy cast iron (the martensitic white iron) of the 600-800 HB: the reversible rotor takes the two uses of the wear: the hammer bar life of 300-2,000 hours depending on the rock;
• The monitoring: the wear profile gauges and the ultrasonic thickness: the liner changes at the planned tonnages: the maintenance budget of the crushing is 15-30 watts per ton when the blast from the steel

The manufacturer patterns its liners as the sacrificial steel: the correct balance of the cost between the cheap manganese and the expensive chromium-iron is the eternal decision of the machine: the file’s maintenance chapter itemizes the interval: the daily visual, the weekly wear gauges, the monthly temperature guns and the annual change-outs: the uptime of the crushing chain rests on this drumbeat of the inspections.

11. The Wet Feed, the Clay and the Surge: The Practical Hazards

Real limestone carries the weather, and the crusher department is the first victim of the storms and the sticky hillside:

• The blinding: the wet fine particles stick and pack the chamber, the grate and the deflector: the jams that stop the crusher at the worst time: the antidotes: the drying, the bypass flaps, the sizer alternative;
• The bridging: the balls of the wet clay wedge the feed chute: the hydraulic cleaners and the vibrating guns: the operators know the prechamber the plate: the safety: nobody enters the chamber without the lock-out;
• The frosted and the frozen: the sub-zero seasons freeze the moist aggregates in the box cars: the sledge or the heating: the plant winterizes the chutes with the closed loops;
• The blockages of the apron: the mart-scale rock blocks the load box and the jams the apron: the excavator resets the course: the operators log the stop time, the planners mine the mine pattern;

The file’s “wet season protocol” is famous among its users: the priority actions, the chute liners, the bin cleanup and the stockpile strategy for the inclement windows: the plant dismantles its “the pit is closed” days with the protocol, and the protocol is the practical transaction between the crushing engineers and the climate.

12. The Worked Example: The Sizing of a 2,000-Ton-Per-Hour Limestone Station

The final chapter of the guide walks the complete sizing, and the abbreviated version runs here:

• The requirements: 2,000 t/h of the 800-mm carbonate (P80 650) with 8% moisture and a moderate abrasion of 0.05: to the mill feed of minus 80 mm;
• The primary: the single-toggle jaw with the feed opening 1,100 × 1,500 mm, CSS of 250, the product 80% at 350 mm: 900 kWh; the installed 560 kW, the belt to the surge;
• The secondary: the heavy hammer crusher with the rotor of 2,000 by 2,200 millimeters at 950 rpm: the product passes the minus 80: meanwhile the neutral kiln gas dries the feed inside the same shell: the installed power of 800-1,200 kilowatts;
• The surges: the bin of 600 t before the primary and the storage silo of 3,000 t between the crushing and the raw mill: the isolation of the two maintenances;
• The totals: the crushing investment share of the plant, the annual wear fleet of the jaw plates and the hammer tips, the planned 2-week shutdown and the fill of the hammer Gantt: the availability target of the 92%;

The example shows how the numbers enter the decision: the hammer (not the cone) because the abrasion is low and the drying is needed; the jaw because the tonnage is ordinary; the two-stage (not the three) because the target of the 80 mm sits in the hammer’s range: the sizing is listening to the material, and the material always answers.

13. The Safety and the Emergency of the Crushing Department

The crushers are the machines with the highest kinetic energy of the plant, and the package’s safety files are the company policy of many customers:

• The lock-out/tag-out: the isolation of the breaker and the rotating, the amputation protection at the jaws every day has a step: the elephants have periods: the procedures comply with the strictest codes;
• The rock ejection: the foreign block bursts through the door cracks: the peak shields and the perimeter fencing: the observers never inside the radius of the orbit: the speed of the bars at 40 m/s;
• The confined spaces: the crushing chamber and the chutes are the confined: the gas test, the rescue plan, the man is never alone: the permit of the entry;
• The dust: the dust extraction at the transfer points and the baghouse: the exposure limits: the operators with the dust masks: the sytemet of the CCR of the guaranteed;

The statistics of the industry are unforgiving: the crushing departments produce the lion’s share of the loss-time injuries in the abrasive operations: the file implores: the safer the department, the longer its life: the procedures of the file are the printable posters, and the managers run them as the morning drill and the toolbox talks of the shift.

14. The Energy and the Economics of the Crushing Department

The crushing is often dismissed as the cheap stage, and the dismissal is half true: the specific energy of the crushers is small, but the department spends its money in the steel, the power and the truck cycles, and the file adds the full ledger:

• The electrical side: the crushers draw 0.3-1.2 kWh/t against the 15-40 kWh/t of the mills: the crusher energy is 2-5% of the plant’s bill, and the savings come from the choke feeding, the correct CSS and the automation of the feeder;
• The wear side: the liner and the bar steel typically cost 0.05-0.30 US dollars per ton of crushed material: the jaw plate life 4-8 months, the hammer bars 300-2,000 hours: the annual wear budget of a 1,000-t/h station reaches the hundreds of thousands;
• The haulage side: the in-pit trucks cost 0.8-2.5 US dollars per ton of hauled material: the mobile crushers and the conveyors cut the haulage by half: the crusher location decision is a logistics decision first;
• The availability side: the 90-95% availability of the crusher line protects the kiln: the lost production day of a 3,000-tpd plant is a six-figure loss: the redundancy and the stockpiles are the insurance the file budgets;
• The upgrade side: the automation of the feeder-CSS loop recovers 3-8% capacity: the speed control of the impactor saves the wear: the 2-5-year paybacks of the modernizations: the Excel of the package prices the options;

The message of the ledger: the crushing department is not the cheap corner of the plant, it is the lever where the tonnage is made and the kilowatts are spent in small, visible, fixable amounts: the engineer with the file’s tables argues the modernization with the board in the language of the payback, and the payback of the crushing upgrades is among the shortest in the cement industry.

15. The Automation and the Control of the Crushing Plant

The modern crushing department is not a row of machines but a control loop, and the file’s automation chapter explains what the operators and the engineers see on the screen:

• The feeder regulation: the belt weigh-feeders and the variable-speed drives hold the crusher load at the set point: the choke-feeding algorithm maintains the chamber full while the motor current stays in the 85-95% band: the recovery of 3-8% of the throughput against the manual operation;
• The CSS automation: the hydraulic setting changes from the control room: the weekly check becomes the daily calibration: the interlock of the setting and the current protects the machine from the over-torque and the bridging;
• The metal detection: the belt magnets and the metal detectors above the feed belts pull the tramp iron before the chamber: the detector stops the belt, the magnet extracts, the jaw never eats the excavator tooth;
• The alarming and the trend: the vibration sensors, the bearing temperatures and the motor currents trend in the historian: the predictive maintenance flags the liner failure weeks before the breakdown: the CMMS issues the work orders;
• The remote and the camera: the crushing station runs with the one operator in the control room, the cameras over the bin, the crusher and the belts: the two-man shift of the past becomes the half-shift of the present: the file documents the philosophy of the personnel economy;

The automation of the crushing is the highest-return investment of the department: the sensors are cheap, the algorithms are proven, and the machine utilization, the liner life and the safety all improve together: the file includes the control schematics, the instrument list and the sequence logic of the start-up and the shutdown, the documents the project teams adapt to their own machines: the control room of the modern plant, documented page by page.

16. The Frequently Asked Questions

What is the difference between the jaw and the impact crusher for the primary?

For the limestone the impact (hammer) crushers achieve the reduction of one pass with 0.4-0.8 kWh/t and the cubic products; the jaw products require the secondary stage: but the absence of the abrasion index > 0.1 or the sticky feed pushes the selection to the jaw-cone: the file conducts the full comparison with the numbers of the maintenance, the capital and the energy favor of the impactor at the low-abrasion hours: the two-door answer.

Can the cement plant run with only one crusher?

The small plants of 300-600 t/d sometimes operate on the single hammer line with a large surge capacity: over about 3,000 t/d the industry installs the parallel lines (the redundancy) or the mobile/by-pass of the primary service: the plant without the backup double the chance of a full kiln stop on a shaft failure: the file scoring: the classic economics of the redundancy.

How should the CSS be corrected for the wear?

The CSS initially exerts the gap with the new liners: the liners wear, the gap enlarges: the weekly check with the lead block: the compensation by the hydraulic adjustment cycle: the wear rate of the jaw slows to about 1 mm per 1,000 tons of the primary: the record in the logbook: the CSS table must be the same answer:

What is the effect of the abrasive feed on the hammer crusher choice?

An abrasion index above 0.1-0.15 doubles the bar and the hammer wear: the impactor of the hard rock becomes a money-loser: the compression machines (cone/gyr/roller) dominate the hard service: the file carries the wear tests, the meaning of the index for the selection and the tables of the replacement costs for the two families.

Are the mobile crushers a good alternative for the cement quarry?

Yes, increasingly: the mobile jaw + the mobile cone follow the progressing face and halve the in-pit hauling: the energy and the labor drop, the capital per t/h rises: for the small and the fast-developing quarries the mobile is formally the living option: the file includes the case of the 900-t/h commission screens.

Does the file include the crusher capacity spreadsheet?

The 931-file package contains the capacity and the power Excel: the inputs: the feed size, the CSS, the rotor data, the rock properties: the return: the t/h, the kW and the product curve: the tool is the same one the package’ authors use in the projects, with the example files already filled in.

17. Conclusion

From the jagged quarry to the hammer’s flight: the crusher department is the first act of the cement process, cheap in the energy and the decisive in the size: the jaw for the huge blocks, the cone and the gyr for the dense, the hammer for the limestone’s speed, the sizer for the sticky and the mobile for the flexible: the four machines are the four answers the engineer keeps in the pocket.

The Complete Cement Technical Package includes this crushers guide with the selection matrices, the capacity curves, the wear and maintenance tables and the Excel sizing tool: the one-time 249.99: the instant download: the knowledge of the crushing department from the pit to the pile: order the package, and let the crushers of your plant work the way the books say they can.

This file is part of the Complete Cement Technical Package (931 files) available from cementequipment.org. Respective rights holders; library copy for the licensed single user.