Ore properties

The main component of limestone is calcium carbonate (CaCO3), which can be directly crushed into crushed stone aggregates for the production of building materials, or fired into quicklime through specific equipment. Quicklime can be used in large quantities for desulfurization in power plants, while quicklime absorbs moisture or adds water. It will become slaked lime in the future. The main component of slaked lime is calcium hydroxide (Ca(OH)2), which can be made into limestone slurry, lime plaster, etc. after a certain proportion of other materials. Important raw material for many industrial production.

limestone

Processing

Vibrating feeder + jaw crusher (stone crusher) + impact crusher + circular vibrating screen, jaw crusher and impact crusher is a classic limestone crushing combination, which has a good reputation in the field of stone crushing in sand and gravel plants. processing effect. The specific crushing method is to crush, classify and separate the white stone containing more than 90% of CaCO3 with a Raymond mill or a high-pressure mill to obtain a finished product.

Processing process

Stage 1: Coarse Crushing

The large limestone material is evenly fed to the jaw crusher by the vibrating feeder through the silo for coarse crushing, and the coarsely crushed material is screened by the vibrating screen, and then conveyed to the impact crusher by the belt conveyor;

Jaw Crusher

Stage 2: medium and fine crushing

After the materials to be processed conveyed to the impact crusher are crushed by the impact crusher, a circular vibrating screen is used to screen the materials after the impact crusher, and the larger particles are returned to the impact crusher for re-crushing; if finer products or shaping are required, Then the crushed materials are sent to the sand making machine for further crushing and shaping;

Impact Crusher

Stage 3: Grinding

The crushed limestone small pieces are sent to the silo by the elevator, and then sent to the grinding chamber of the mill evenly and quantitatively by the vibrating feeder for grinding.

vibrating-feeder

The main three processing technology:

Sand and gravel materials

For building aggregates: generally processed to 1-2cm.

Production of sand: Feeder-sand-making machine-conveyor-sand washing machine, used for sand and gravel aggregates.

Casting sand: The particle size of limestone production sand is 28-75 mesh. This kind of sand has better performance than quartz sand, good collapsibility, easy to clean out sand, improve the surface quality of castings, and increase the surface finish of castings.

processing flow

Production of quicklime

(limestone -> calcination (rotary kiln) -> calcium oxide (generally block after calcination))

Rotary kiln production process of lime:

(1) Limestone → vibrating feeder → belt conveyor, from the raw material silo to the screening equipment, the limestone of appropriate particle size enters the preheater, and the kiln tail is preheated at a high temperature of 1000 °C, and 20%-25% of the limestone is decomposed → propelled and rotated kiln.

(2) Further calcined in the rotary kiln and completely decomposed at 1300 ℃.

(3) When entering the cooler, its temperature is 1100°C, and the lime is cooled to 70-100°C by the blower at the bottom of the cooler.

Then, there is a vibrating feeder in the lower part of the cooler, which is discharged to the conveyor, and then sent to the finished product warehouse through conveying, screening and lifting equipment, which is the final active lime product

processing flow

Grinding powder as chemical filler

The main grinding products are: light calcium powder, heavy calcium powder, gray calcium powder.

① Ash calcium powder

Processing technology: limestone --> calcination --> calcium oxide --> selection + partial digestion --> ash calcium machine -->

Uses: Putty powder, latex paint, thermal insulation mortar, architectural coatings, wire and cable, plastic steel doors and windows, also used for flue gas desulfurization, sewage treatment, etc.

latex paint

② Light calcium powder

Processing technology: limestone - calcination - carbonization - crushing.

Uses: Mainly used in chemical industries such as rubber, plastics, papermaking, coatings, etc.

rubber

③ Heavy calcium:

1. Dry production process:

Raw material → gangue removal → jaw crusher → impact hammer crusher → Raymond mill → superfine ball mill → classification system → packaging → product.

First, the calcite, limestone, chalk, shells, etc. transported from the quarry are selected by hand to remove the gangue; then the limestone is roughly crushed with a crusher, and then crushed with a Raymond (pendulum) mill to obtain fine calcite powder. Use a classifier to classify the milled powder, and the powder that meets the particle size requirements is packaged and stored as a product, otherwise it will be returned to the mill to grind again.

2. Wet production process:

Raw ore → jaw crusher → Raymond mill → wet stirring mill or peeling machine (intermittent, multi-stage or circulating) → wet classifier → sieving → drying → activation → packaging → product (coating grade heavy calcium).

The wet superfine grading is added to the process flow, which can separate qualified products in time and improve the efficiency. Wet superfine classification equipment mainly includes small diameter cyclone, horizontal spiral classifier and disc classifier.

Uses: Heavy calcium is usually used as a filler, and is widely used in artificial floor tiles, rubber, plastics, papermaking, coatings, paints, inks, cables, building supplies, food, medicine, textiles, feed, toothpaste and other daily chemical industries.

artificial floor tiles

Points to Note

Ensuring grinding efficiency and reducing dust pollution are the two most important aspects of limestone grinding.

The former is the main factor in obtaining the expected economic benefits. The latter is an important measure to protect the environment and achieve sustainable development.

Ensure grinding efficiency

Grinder capacity is a very important factor that affects profits. How to ensure the grinding efficiency of the grinding machine during the grinding process?

control spindle speed

When the working power is insufficient or the belt is worn, the spindle speed will be reduced, resulting in a decrease in the grinding speed.

Therefore, in the process of powder processing, it is necessary to pay attention to whether the pulverizer has sufficient operating power, and replace the worn transmission belt in time.

Check wearing parts

The wear of consumable parts such as mill blades, grinding rollers, and grinding rings will also reduce the powder extraction rate. Therefore, checking and replacing wearing parts is also an important part of ensuring grinding efficiency.

Check the pipes

Check the pipes

Poor sealing will block the air duct and cause dust to increase. Therefore, the tightness of the grinder needs to be carefully checked before work.

Once the air duct is blocked, the operation should be stopped immediately and the pipeline should be cleared in time.

Reduce dust pollution

As one of the most common and difficult problems in grinding, dust pollution can be reduced from the following aspects:

Reducing dust pollution

Adding an aerosol dust removal system at the inlet of the pulverizer is an important way to reduce dust pollution. The amount of water needs to be strictly controlled, because the moisture content of the material exceeds 10%, which will block the pulverizer.

Pay attention to the sealing between all parts of the grinding line to prevent the leakage of dust.

Choose a quality dust collector. Dust collectors directly affect dust emissions.

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