Key technology and equipment of gravity separation and clean coal recovery from refractory coarse coal slime

In the process of crude coal recovery, effective separation particle size is greater than 2 mm with dense-medium cyclone and effective separation particle size is less than 0.25 mm with flotation method.Thereby, -0.25 mm and 2 mm particles are cannot effectively separated.This paper proposed recovery technology of “slime centrifugal separator + high frequency frequency conversion grading screen” in order to solve the problem of clean coal loss because the separation technology and equipment are not perfect.Slime centrifugal separator is composed of two stage cyclones.This process was used to conduct an industrial validation for coarse slime recovery in a coal preparation plant.This technological methods effectively solves the fine coal loss problems in slime separation and obtain clean coal (ash content< 10%) , and production ratio is improved by 12.5%.The study results create considerable economic and social benefit for the industries.