Project Background
A fixed crushing plant in West Java, Indonesia, processes limestone from a local quarry. The owner runs one stationary line rated at 300 tons per hour, making four sizes - 0-5, 5-10, 10-20 and 20-30 mm - for nearby cement plants and road construction. The feed is quarried limestone: Mohs 3-4, medium-hard, low-abrasion, high in CaCO3, with a little surface mud. The line follows the classic limestone circuit: feed - pre-screen - jaw - impact - screen - closed-circuit return. Below we walk through the project background, what the customer required, the material behaviour, the process logic, the equipment list, how it performs in service, and what the field taught us.
Customer Requirements
The owner's hard specs were clear: - Feed: limestone (quarried, light surface mud) - Capacity: 300 TPH - Products: 0-5 / 5-10 / 10-20 / 20-30 mm, continuous gradation, low flakiness (0-5 mm runs as filler/sand, 5-30 mm as three aggregate grades) - Form: fixed (stable material source, long-term run)
| Product | Size | Screen split (mm) | Typical use |
| Fines | 0-5 mm | below 5 mm deck | cement filler / manufactured sand |
| Fine | 5-10 mm | 5-10 mm deck | asphalt / concrete fine agg |
| Mid | 10-20 mm | 10-20 mm deck | ready-mix concrete agg |
| Coarse | 20-30 mm | 20-30 mm deck | road base / coarse agg |
Material Analysis
This limestone runs Mohs 3-4, medium-hard, low-abrasion, high in CaCO3, with compressive strength around 120 MPa. It is a typical mid-soft rock - it does not eat wear parts the way river stone does, so crushing it is comparatively gentle.
- Surface mud: quarried limestone carries a little clay and weathered skin; let it reach the crushers and the product turns dirty and the screen blinds. - Feed up to 500 mm: the blasted rock comes in big lumps, so primary crushing has to swallow them first. - Four sizes with strict gradation: 0-5 up to 20-30 mm, with a hard 30 mm top-size limit - an open circuit cannot deliver on-spec material, oversize must be caught and returned. - Long wet season: West Java gets heavy rain and the muddy feed runs wet, so pre-screening and drainage have to be planned up front.
Process Design
The line follows a proven limestone circuit: feed - pre-screen - jaw - impact - screen - (return oversize) - product.
Limestone is low-abrasion, so an impact crusher's blow bars last 3-6 months on this rock - wear cost stays under control. The bigger win is shape: the impact stage reshapes the material by striking, giving a high cubic rate and few flat, elongated pieces, which sells at a premium over the "sliver" shape a cone tends to make. A cone is tougher on wear but on limestone it is overkill - you pay more and get a worse shape. Flip the feed to high-silica river stone and the impact bars die in days; then a cone is the only honest option.
With feed up to 500 mm, the 6CX110's feed opening and discharge setting drop the big lumps to a size the impact crusher can take, protecting the impact chamber from oversize.
The 3YA2870 vibrating screen splits the four sizes and sends everything above 30 mm back to the impact crusher. That return loop pins the top size and keeps every fraction on spec. Drop it and the oversize ends up in the product pile.
Equipment Configuration
The four core machines run in sequence: ZSW600x130 vibrating feeder -> 6CX110 jaw crusher -> PF-1520 impact crusher -> 3YA2870 vibrating screen, with belt conveyors linking them. The feeder's grizzly bar pre-screen pulls the mud and fines out before they reach the crushers, which is what keeps the screen from blinding in the wet season.
| Stage | Equipment | Model | Role |
| Feeding | Vibrating feeder | ZSW600x130 | Even feed + grizzly pre-screen to drop mud |
| Primary | Jaw crusher | 6CX110 | Breaks big limestone to a size the impact can take |
| Secondary | Impact crusher | PF-1520 | Impact shaping, controls gradation, low wear |
| Sizing | Vibrating screen | 3YA2870 | Splits 0-5 / 5-10 / 10-20 / 20-30 mm + return |
| Linking | Belt conveyors | several | Carry material between stages |
Production Performance
With the return circuit, the top size stays under 30 mm and the four fractions stay continuous. No off-spec oversize in the pile; the 0-5 mm fines stay clean for the cement plant.
The impact stage throws a high cubic rate with few flat pieces, so road and ready-mix buyers pay more than they would for cone-made slivers.
On limestone the PF-1520's blow bars run 3-6 months, so wear cost per ton is a fixed, predictable number. The jaw plates last even longer.
Grizzly pre-screening at the feeder keeps clay and fine material out of crushing and screening, so clogging stays rare even in the wet season.
Lessons Learned
The trap on limestone is the reflex to fit a cone "because cones last longer". On limestone an impact crusher is both cheaper and better-shaped; the blow bars run 3-6 months and the cost per ton sits below a cone's while the sell price is higher. A jaw plus an impact crusher, with a screen return, is the combination that actually runs long-term and pays. This layout is also Vanguard Machinery's standard playbook for limestone jobs across Southeast Asia. Two more things: pull the mud out up front so the back end clogs less and the rainy season stays calm; and feed it steady - a starved impact makes powder, an overloaded one chokes the return circuit, so keep it steady to get the output. Flip the feed to high-silica river stone and the blow bars die in days; then a cone is the only honest choice, so do not fight the material.
FAQ
Limestone is low-abrasion, so impact blow bars run 3-6 months here and wear cost stays controlled. More importantly the shape: impact output is highly cubic and sells above cone-made slivers.
It takes the up-to-500 mm lumps and breaks them to a size the PF-1520 can accept, protecting the impact chamber from oversize.
On low-abrasion limestone, yes - that is the normal range. Switch to high-silica river stone and they can fail in days; the rock sets the life, not the machine.
It runs decks set to 5, 10 and 20 mm (plus a 30 mm top deck for return), splitting the feed into 0-5, 5-10, 10-20 and 20-30 mm, sending oversize back.
Oversize above 30 mm goes back to the impact crusher instead of the pile. Without it the top size drifts and the whole batch can be rejected.
The screen's top deck catches everything above 30 mm and the return loop sends it back to the impact crusher until it passes.
The ZSW600x130 feeder's grizzly pre-screens the mud and fines before crushing, so the crushers and screen stay clean and the wet-season clogging stays rare.
It is the line's design capacity, set by the feeder, jaw and impact sizes and a steady feed. Size the plant to the real feed rate, not the brochure maximum.
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