Why we need to wash the coal?
As we know, the raw coal is mixed with many impure substances, after the coal washing in coal preparation plants, which can be divided into coal gangue, medium coal, grade B clean coal, and grade A clean coal, then used in various industrial usages.

But why we need to do this work?

The main reasons as following:
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), which can reduce soot, SO2 and NOx efficiently when coal burning, so reduced much pressure for the pollution controlling works.

2. Improve coal utilization efficiency and save energy
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 thermal power plants, 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
According to the development of the coal preparation technology, coal products from single structure low quality changed to multiple structure and high quality so as to meet the requirement from different clients due to the environmental protection policy is tougher and tougher, in some areas, coal sulfur content is less than 0.5% and ash content is less than 10%.
If the coal is not washed, sure it won't meet the market requirements.

4. save much transportation cost
As we know, the coal mines always far away from the end users, after washing, much impure substances are picked out, and volume will reduce much, which will save much transportation cost of course.