Limestone is the backbone of construction. It is used in cement, concrete and road base. But, processing it requires specific gear. You cannot just use any crusher. Limestone is soft but can be sticky. If you choose wrong, you lose money. We will break down the exact equipment needed. This guide covers principles, data and real cases.
Before buying, look at the rock. Limestone has a Mohs hardness of 3 to 4. It is not very hard. However, it can have high moisture. High silicon content is bad for wear parts.
Key Parameters:
Why this matters: You do not need expensive Cone Crushers. They cost too much per ton for soft rock. Impact crushers are better here. They give better particle shape. This saves capital investment.
The first stage is big rock reduction. We use a Jaw Crusher here. It is rugged and simple. It handles big blasting stones. The ratio of reduction is about 4:1 to 6:1.
Working Principle:
A moving jaw plate presses rock against a fixed plate. The motor drives a belt. This turns an eccentric shaft. The jaw moves up and down. This motion crushes the stone.
Technical Focus – CSS:
CSS stands for Closed Side Setting. This is the smallest gap at the bottom. It decides the output size. For limestone, a CSS of 100mm-150mm is common. This prepares the stone for the next machine.
| Model | Feed Opening (mm) | Max Feed Size (mm) | Capacity (t/h) |
|---|---|---|---|
| PE-600×900 | 600×900 | 500 | 50-160 |
| PE-750×1060 | 750×1060 | 630 | 110-320 |
| PE-900×1200 | 900×1200 | 750 | 220-450 |
This is the heart of a limestone plant. The Impact Crusher (PF Series) is essential. Why? Because it shapes the stone. Concrete needs cube shapes, not flakes.
How it works:
A heavy rotor spins fast. Blow bars are on the rotor. Rock falls in. The bars hit the rock. The rock flies against impact plates. It breaks along natural lines. This repeats until size is reached.
Critical Data:
Benefit: It handles “soft” rock effectively. It creates less needle-like particles. SBM impact crushers use a unique heavy rotor. This adds inertia. It lowers energy use by 15%.
Crushing is useless without sizing. The Vibrating Screen separates the piles. It sorts stone by size. Usually, we use circular vibrating screens.
The Setup:
Screens are tilted (about 20 degrees). A motor shakes the box. Small stones fall through mesh. Big stones stay on top. They go back to the crusher.
Selection Tip:
Check the “Screening Efficiency”. It should be over 85%. If it is low, you recirculate too much. This wastes power. Also check the amplitude. For limestone, 8-11mm amplitude is good. It prevents clogging.
Limestone creates dust. Lots of it. Environmental laws are strict now. If you make dust, you get fined.
The Solution:
We install Pulse Bag Dust Collectors. They suck dust from leak points. Points like the conveyor drop. The efficiency is 99%. Or, use water sprays. But water is bad if the screen mesh is small. It causes blocking.
Why bother?
Clean air means no shutdowns. Government inspectors love clean plants. It keeps the plant running.
Let’s look at a real job. A client in Vietnam needed high-quality aggregate. They supply a concrete batching plant.
Project Background:
The SBM Solution:
We replaced the cone crusher. We installed a PFW Hydraulic Impact Crusher. We adjusted the third impact curtain.
Results:
Flaky particles dropped to 8%. The cement plant was happy. The wear cost was low. The blow bars lasted 4 months. The customer said “The shape is perfect now”. This proves impact crushing is best for limestone.
This is a common headache. You set the machine. But the pile size changes. Why?
The Cause:
Wear is the enemy. The blow bars wear down. The gap opens up. This is the OSS (Open Side Setting). When bars get round, they grind less.
The Fix:
Check the gap weekly. SBM crushers have hydraulic assist. You push a button. The frame opens. You adjust shims. Keep the gap tight. Consistency returns.
Good gear needs a good foundation. Do not skimp on concrete. Vibration kills weak bases.
Installation Tips:
Leave space around the crusher. You need room to change liners. If space is tight, workers hate it. Maintenance gets skipped. Then the machine breaks.
Maintenance Cycle:
Why? Unplanned downtime costs $1000s per hour. Planned stops cost little.
Stationary plants are cheap. Mobile plants are pricey. But, mobile plants move.
Scenario:
If your quarry face moves fast, trucks drive far. Trucking costs diesel. A mobile crusher follows the blast. It eliminates trucking. SBM mobile stations are flexible. You park, unfold and run.
Decision Tree:
Is the project > 3 years? Buy Stationary. Is it < 1 year? Buy Mobile. The ROI makes sense on short jobs. Fuel savings pay for the chassis.
We cannot give a dollar price here. Steel prices change. But we can talk about ratios. The main cost is not the machine. It is electricity and wear parts.
The Math:
Energy is 40% of OpEx. Impact crushers use energy well. But if feed is too big, amps spike. SBM designs the flow to balance the load. We feed the crusher what it likes.
ROI Time:
A well-designed 200tph plant pays back in 8-12 months. This assumes steady sales. Bad design takes 2 years. Efficiency is cash.
Q1: Can I use a Cone Crusher for limestone?
Yes, but why? Cone crushers are for hard rock (granite). They cost more to buy. They make poor shapes in soft rock. Stick to Impact crushers for limestone.
Q2: How often do I change blow bars?
It depends on silica. If silica < 5%, maybe 6 months. If silica > 10%, maybe 2 months. Always test your rock first.
Q3: My screens are blinding (clogging). Why?
Is the rock wet? If moisture > 6%, mesh clogs. Use “harp wire” or “piano wire” screens. They self-clean. Or add a washing stage.
Limestone crushing is simple if you follow rules. Do not oversize the feed. Use a Jaw for primary. Use an Impact for secondary. Watch the wear.
Final Checklist:
We build lines that run. We do not just sell iron. We sell capacity. If you need a layout, ask us. Let’s get the stones rolling.
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