On the basis of intensive investigation the process of sludge draw off from clarifiers, a better method for sludge withdrawal monitoring and controlling was pressented and an automatic sludge withdrawal device was developed.

The paper introduces analysis about mud pump characteristic, diesel engine characteristic, piping system characteristic, working point and working range of mud pump device .

As a method widely used in separation coal, jigging technology has direct and important influence on the quality and output of coal product Emphasising on discharging of light product, we develop a new type discharging device which act on the discharging part of jigger and can follow the pulse of the separation line of density.