The goal of coal mining would be to remove coal from your ground.You can find four main forms of coal mines: shaft mine, slope mine, drift mine, and surface (open-cast) mine. coal mining is need crusher or moible crusher,include some optional equipment including vibrating feeder , vibrating screen , belt conveyors etc in order to complete the coal milling process.
Coal grinding mill
coal mill include ball mill , Raymond mill , vertical mill , MXB Gridning Mill. In coal crushing process, several types of coal crusher are used,such as jaw crusher , impact crusher , cone crusher and mobile crusher . Often a complete coal milling line includes coal mill, impulse dust cleaner, piping device, cyclone collector device, classifier.
Coal Milling Process
Raw coal is fed through a central coal inlet at the top of the pulverizer and falls by gravity to the rotating grinding table, mixing with classifier rejects returned for re-grinding.Centrifugal action forces the coal outward towards the grinding ring where it’s pulverized between the ring and three grinding rollers.
Pulverizing the coal to a fine powder is a crucial function within the operation of the power plant. The important thing input towards the coal fired power plant will be the coal. Coal within the form that is available from your mines just is suited to efficient combustion in the boiler from the power plant. The pulverizing system prepares the coal for combustion.
You can find basically three different types of pulverizing.
1. Attrition Type
The primary characteristics are:
* Lower investment costs than other forms.
* Smaller capacity for each mill means a better amount of combustion flexibility.
* They require periodic roller changes as they wear out during pulverizing, enhancing the maintenance cost.
* Harder coals require this type of pulverizers.
2. Impact and Attrition Type
* This referred to as Tube mill or Ball mill These types of mills have:
* Initial costs which is higher.
* Maintenance that is considerably less.
* As the balls degrade during operation, adding fresh ball charges can be achieved even though the mill is running.
* Can provide a very high fineness coal having a large number of fines.
3. Impact or Hammer Type
The main charectristics are:
* Lower costs.
* Suitable just for softer coals.
* Low fineness output.
Selection of the type of pulverizer is dependent upon
* Grindability of the coal.
* Capital cost and maintenance expense is another criteria.
* Patent rights and licence agreements also choose which type of pulverizer the boiler suppliers recommend.