Mining and Crushing-Screening Plant Buying Guide: Capacity, Wear Parts and Plant Balance
How to size jaw and cone crushers: feed opening, reduction ratio and tonnes per hour. Manganese jaw life, screening area, mobile versus stationary plant, a new-versus-used comparison, inspection checklists and cost per tonne.
The most common mistake in a crushing and screening investment is judging a single machine on its rated capacity. Real throughput is set by feed size, material abrasiveness, moisture and screening area together. A powerful crusher bought without balancing the plant will run at half its rating because the screen cannot keep up.
Crusher Types and Where They Belong
Jaw crushers are the standard for primary crushing; units with 400-1,200 mm feed openings run at 100-500 tonnes per hour with a typical reduction ratio of 4:1 to 6:1. Cone crushers in the secondary and tertiary stages deliver cubical product and high throughput. Impact crushers give high single-stage reduction on low-abrasion material such as limestone, but hammer life collapses on high-silica rock like basalt and granite. Vertical shaft impactors (VSI) are used for sand production and particle shaping.
Screening Area
Screening capacity is directly proportional to deck area and aperture size. Moist and clay-bearing material sharply reduces screen efficiency, so washing screens or log washers should be planned for such feeds. In practice, undersized screening relative to crusher capacity is the single most common bottleneck.
Capacity and Wear Classes
| Equipment | Capacity | Motor power | Wear part life | Reduction ratio |
|---|---|---|---|---|
| Jaw crusher (900x650) | 100-180 t/h | 75-90 kW | Manganese jaw 300-600 h | 4:1 - 6:1 |
| Jaw crusher (1200x900) | 250-450 t/h | 132-160 kW | Manganese jaw 300-600 h | 4:1 - 6:1 |
| Cone crusher (secondary) | 150-400 t/h | 160-315 kW | Mantle and concave 400-900 h | 3:1 - 5:1 |
| Impact crusher | 100-350 t/h | 110-250 kW | Hammers 150-400 h | 10:1 - 20:1 |
| Vibrating screen (3 deck) | 150-500 t/h | 15-37 kW | Screen mesh 400-1,200 h | - |
Mobile or Stationary Plant?
Tracked or wheeled mobile plants move with the face as the quarry advances, cutting haulage cost, and they can be commissioned in days. Stationary plants give lower cost per tonne and higher throughput in long-life quarries. Below roughly 300,000 tonnes a year, mobile plant is usually the more flexible choice; above that, with continuous production, stationary plant wins. Metso, Sandvik, Terex and Epiroc are the most commonly encountered manufacturers in this segment.
Used Crushing Plant Checklist
- Ask which rock the crusher processed; a machine that worked basalt or granite is far more fatigued than one that ran limestone.
- Look for cracks, old weld repairs and deformation on jaws and frame; frame cracking is the most expensive defect.
- Check eccentric shaft bearing clearance and the lubrication system, and request an oil analysis report.
- On cone crushers, test that the hydraulic setting system and tramp release cylinders hold pressure.
- Inspect screen bodies for weld cracks, worn spring seats and unbalanced vibration.
- Check conveyor pulley lagging, idler rotation and belt splices.
- Measure motor winding resistances and inspect soft starters and the electrical cabinet.
- Confirm wear parts are in stock and available; imported manganese lead times can stop a project.
Cost Per Tonne
Crushing plant economics are measured per tonne. The items are energy (kWh on stationary plant, diesel on mobile), wear parts, oil and grease, maintenance labour, haulage and depreciation. Stationary electric plants are markedly cheaper per tonne than diesel mobile plants, at the price of higher civil works and installation investment. On hard, abrasive material, wear parts alone can reach a quarter of total cost.
Excavation, loading and haulage equipment for the quarry can be found under construction machinery, and haul trucks under trucks and transport vehicles.
Feeding, Conveyors and Dust Control
The least visible but most decisive part of a crushing plant is feeding and conveying. The grizzly spacing on a vibrating feeder scalps fines away from the primary crusher, reducing its load and often adding 10-20 percent capacity. If feeder capacity is specified below the crusher, the plant never reaches its rated output.
On belt conveyors, width, speed and incline are calculated together. With dry, angular material, slip-back starts above about 18 degrees of incline, and the limit is lower for wet feed. Excessive belt speed causes material segregation and shortens belt life.
Dust control matters for both environmental compliance and equipment life. Plan spray nozzles at transfer points, enclosed chutes and, where required, a bag filter. Bearings and electric motors working in dusty air have markedly shorter lives, so dust control should be treated as a maintenance saving rather than a cost.
Finally, plant layout and stockyard planning decide whether rated capacity is ever used. Product bins should hold at least half a shift of production, and truck loading points must work without stopping the line. Plants with cramped stockyards stop frequently even when crusher capacity is more than adequate.
New or Used?
In crushing and screening, quarry life and annual tonnage decide. For long-life, high-tonnage sites, a new plant lowers cost per tonne through automation and energy efficiency; for short projects and seasonal production, a used plant is commissioned far faster.
| Criterion | New machine | Used machine |
|---|---|---|
| Initial investment | High | Substantially lower |
| Lead time | 8-30 weeks after order | Usually 1-3 weeks |
| Warranty and service | Manufacturer warranty, commissioning included | Limited or dealer warranty |
| Technology and efficiency | Automatic setting, load optimisation, remote monitoring | One or two generations behind |
| Spare parts | Secured for many years | Depends on model age |
| Depreciation | Steep loss in the first years | Much slower value loss |
| Finance and leasing | Suits leasing and incentives | Limited, needs appraisal |
A new crusher holds capacity and particle shape when the feed changes, thanks to automatic setting control, which also stabilises wear part consumption. Remote monitoring logs hourly tonnage, load and vibration and warns of failures in advance. Modern electrically driven plants deliver markedly lower energy cost per tonne than diesel mobile solutions.
What to ask when buying new matters just as much as the used checklist:
- Lead time: the schedule from order confirmation to commissioning must be in writing.
- Warranty scope: duration, excluded parts and response time should be stated clearly.
- Service network: ask the distance to the nearest authorised service and its response time.
- Parts commitment: stock status and lead time for critical parts belong in the contract.
- Training and commissioning: confirm operator training and acceptance tests are included in the price.
Frequently Asked Questions
How do I calculate the crusher capacity I need?
Divide annual target production by annual operating hours and add a 20-25 percent margin. A plant targeting 500,000 tonnes a year over 2,000 operating hours needs roughly 300-315 tonnes per hour of nominal capacity.
How long does a manganese jaw last?
Typically 300-600 operating hours depending on abrasiveness. On high-silica granite it can drop to 200 hours; on soft limestone it can exceed 800. Reversing the jaw plate roughly doubles usable life.
Is mobile plant cheaper?
Mobile plant is cheaper for short projects, multi-site work and quarries with long internal haul distances. For high-tonnage production on a single site over many years, stationary electric plant gives a lower cost per tonne.
How do I recognise a screening bottleneck?
If material builds up on the deck while the crusher runs at full feed and product fractions start to contaminate each other, the screen is undersized. The fix is more deck area, a different screen angle, or a washing system for moist feed.
What is the riskiest item in a used plant?
Fatigue cracks in the crusher frame and worn eccentric shaft bearings. Repairing either can cost close to the market value of the machine, so frame welds must be examined in detail during inspection.
Should a short project buy a new plant?
On a one or two year project, depreciation on a new plant is heavy, and a used mobile plant or rental fits better. With a quarry life beyond ten years and production above 500,000 tonnes a year, a new stationary plant gives the lowest cost per tonne.
To review new and used jaw crushers, cone crushers, vibrating screens, conveyors and complete crushing plants, browse the mining and crushing-screening machinery category.