Coal washing | Coal preparation | Coal washing plant pcocess

What is coal washing?

Coal washing is actually the important step of coal preparation. when washing the coal, non-coal materials and undesirable material from the run-of-mine is washed or cleaned. Through the coal washing plants, a qualified product will be achieved.

Why is coal washed (The importance of coal washing)?

The raw coal is mixed with many impurities during the mining process, moreover, the quality of coal is also different, and the small internal ash and big internal ash of coal are mixed. The products produced after coal washing process are generally divided into meteorite, medium coal, grade B clean coal, and grade A clean coal.

By washing coal, can reduce the cost of coal transportation and increase the utilization rate of coal. Clean coal is an energy that can generally be used as fuel, the fine coal of bituminous coal is generally used for coking.

The main reasons of washing coal are as bellow:

1. Improve coal quality and reduce emissions of coal-fired pollutants

Coal washing can remove 50%-80% of ash and 30%-40% of total sulfur (or 60%~80% of inorganic sulfur) in coal. Burning coal can effectively reduce soot, SO2 and NOx.

Emissions, washing 100 million tons of thermal coal can generally reduce 600,000 to 700,000 tSO2, remove 16Mt of meteorites.

2. Improve coal utilization efficiency and save energy

The improvement of coal quality will significantly improve coal utilization efficiency.

Some studies have shown that: the ash content of coking coal is reduced by 1%, the coke consumption of ironmaking is reduced by 2.66%, the utilization factor of ironmaking blast furnace can be increased by 3.99%; the production of ammonia using washing anthracite can be saved by 20%;

the coal ash for power generation For every 1% increase, the calorific value is reduced by 200~360J/g, and the standard coal consumption per kWh is increased by 2~5g; for industrial boilers and kiln burning washing coal, the thermal efficiency can be increased by 3%~8%.

3. Optimize product structure and improve product competitiveness

The development of coal washing is conducive to the transformation of coal products from single structure, low quality to multiple varieties and high quality, to achieve high quality products.

There are many users of coal consumption in China, and the requirements for coal quality and variety are constantly improving. In some cities, coal sulfur content is less than 0.5% and ash content is less than 10%.

If the coal is not developed, it will not meet the market requirements.

4. Reduce capacity waste

Because the coal-producing areas are far away from the economically developed areas with more coal, the coal transportation volume is large and the transportation distance is long.

The average coal transportation distance is about 600 kilometers. After washing, the coal can remove a lot of impurities and wash 100Mt of raw coal. , can save 9600Mt-km capacity.

LZZG washing solutions for Coal washing plant process

LZZG Coal washing plants are mainly used to remove impurities from raw coal or to classify high quality coal and low quality coal. Before clean coal used, it must first to be crushed, graded, washed, dewatered and fines recovered to meet the standards for coking.

The amount of water per ton of coal used in wet coal washing plant is 2-8 m3. The generated wastewater mainly contains suspended solids with a particle size of less than 50 μm.

The washing process are as below:

1. Coal blending

Coal blending is to set up a coal hopper with a certain capacity near the wellhead to accept the coal that is raised to ground, to ensure the continuously produced.

2. Coal screening

In coal washing plants, screening operations are widely used in raw coal preparation and washing. According to different screening methods, it is divided into dry screening and wet screening.

3. Coal crushing

In coal preparation plants, the crushing operation should be adapted to the requirements of the selected particles; in order to select the fine baking from the coal, the crushed coal should be broken into smaller particles to separate the coal and meter; to meet the user’s particle requirements, the product or coal is quickly pulverized to a certain particle size.

4. Coal washing

Coal washing utilizes different physical and physical-chemical properties to remove impurities mixed in raw coal by mechanical means in the coal washing plants, and divides it into products with different quality and specifications to meet the needs of different users.

LZZG dewatering vibrating screen is mainly used for coal grading, de-sludge, dewatering and de-intermediation. It is also suitable for the screening of other minerals. The dewatering vibrating screen is a washing and dewatering equipment specially designed for tailings.

When working, the coal is fully washed under the flushing action of water stream, and then enters the dewatering  vibrating screen. Under the action of vibration, the clean coal and mud water are separated, and the clean coal water content is controlled within 10%-15%, thereby achieving the transportation or dry stack.

LZZG have successfully provide washery capacities ranging from 100 tons/h to 600 tons/h. Our coal washing plants including a raw coal preparation modular, a coal feed and washing module and a dewatering module. we also provides high quality equipments for coal washing plants such as vibrating screens, vibrating feeders, fine coal slurry separators, magnetic separators, cyclones, coal filter press and heavy media containers.

We aims to help clients ensure their coal washing process efficiency and maximize profit.