Coal processing unit operations

Mining of Coal

Coal miners use giant machines to remove coal from the ground. They use two methods: surface or underground mining. Modern mining methods allow us to easily reach most of our coal reserves. Due to growth in surface mining and improved mining technology, the amount of coal produced by one miner in one hour has more than tripled since 1978.

Surface mining is used to produce most of the coal in the United States because it is less expensive than underground mining. Surface mining can be used when the coal is buried less than 200 feet underground.

In surface mining, giant machines remove the top soil and layers of rock known as "overburden" to expose the coal seam. Once the mining is finished, the dirt and rock are returned to the pit, the topsoil is replaced, and the area is replanted.

Underground mining, sometimes called deep mining, is used when the coal is buried several hundred feet below the surface. Some underground mines are 1,000 feet deep. To remove coal in these underground mines, miners ride elevators down deep mine shafts where they run machines that dig out the coal.

Coal Crusher, Coal Mill and Coal Pulverizer

Coal powder can improve coal burning efficiency, increase power output and reduce harmful gas emission, etc. As a result, coal mills and coal powder processing technologies are increasingly important in electric power plants, steel plants, cement plants and any other industry using injection type coal furnaces.

There are risks of explosion during coal powder processing, store and transportation. SBM, as a professional coal mill and coal crusher manufacturer in China, is committed to provide totally safecoal mills and coal pulverization technologies to global customers.

To this end, we adopt international-leading production technologies to design and manufacture ourcoal mills and coal crushers. Our years' manufacturing experience further guarantees our Coal Millquality. Due to this, our Coal Mill provides decreased danger, and produced coal powder featuring increased burning efficiency.coal pulverizer design

Coal mill process

Coal is mined by explosion, then crushed by coal crusher into small pieces. In this coal crushing process, several types of coal crusher are used. Jaw crusher, impact crusher, cone crusher can be used as coal pulverizer.

After crushing, crushed coal enter into the coal mill for grinding. Usually a complete coal milling line includes coal mill, impulse dust cleaner, piping device, cyclone collector device, classifier. The stones are squeezed by roller and ring into powder, the powder is collected by cyclone collector. In order to ptotect the environment, we also install the cloth deduster

Coal processing unit operations

For coal mill, you have several types to choose. Ball mill is widely used in cement industry. There are two types: wet ball mill and dry ball mill. Ball mill has simple structure, low cost, high capacity and convenient maintenance. The finished size is not even. Vertical coal mill is also called vertical roller mill, and is also widely used in cement industry.

Vertical coal mill is big in appearance with high capacity. For clinker grinding, we general use this vertical coal mill. The finished size can be upto 0.045mm. Raymond mill is the eary grinding mill, but now is still used widely.

Operation principle of coal mill main unit: Main unit runs with the central shaft that is driven by a decelerator. The top of the shaft is connected with a quincunx stand, on which a grinding roller is installed to form a swing support.

About Coal Beneficiation : Three kinds of processes may be performed at the plants:

(1) sizing, controlled by a crushing and screening process,

(2) increasing heating value, by removing noncombustible ash and rock by gravity separation,

(3) removing or controlling undesirable mineral and chemical components (sulfur, sodium, and trace elements) by a combination of gravity separation and blending. Traditionally, most coal preparation was primarily concerned with sulfur and ash reduction. Today, however, much more sophisticated processes have more narrow and complex physical and chemical requirements for coal stock.coal processing unit operations

Coal Processing Plant

Coal processing goes as follow:
Coal is first crushed by coal crushers to a size of 20 to 25 mm and is then fed to coal bunkers. Coal feeders feed this crushed coal continuously to coal mill as per requirement. Coal gets ground by grinding elements in stages. Coal particles get re-circulated around four times before achieving required fineness. Classifier allows finer particles to escape mill outlet while coarse particles are returned to mill for further grinding. Primary air is supplied by P.A. fan through air pre heaters to coal mill or in some boilers, P.A. fan pressurize hot air received from air pre heaters and then supply to mills. Hot primary air drives moisture from coal and acts as carrier to transport pulverized coal to the boiler through pipes.

Output is pulverized coal having required fineness. For complete combustion coal should have fineness of 75% through 200 mesh and 99.5% through 50 meshes. Primary air + coal mixture flowing through each coal pipes should have minimum velocity of 18 m/sec, Temp. Around 80 degrees C, and air/coal ratio of 1.8 -2. Fuel flow through pipes is balanced within range of +/-10%. Finer is the coal, better is the flow distribution.coal processing plant