Abstract: A low yield of clean coal used to be the problem facing Ertang Coal Washery for the reason that the raw coal treated is a kind of extremely hard-to-wash coal in nature and has a high dirt content. To tackle this problem,a new washing system with a designed capacity of 4. 5 Mt/a is added. The system features the use of the superlarge-diameter φ 1500 /1100 gravity-fed 3-product H. M. cyclone as the primary washing equipment. Result of field operation shows that the cyclone works with a remarkable technical performance as follows,which can well meet the demands of the plants: capacity-up to 500-600 t/h,sharpness of separation- E_p1= 0. 022 g/cm³,E_p2= 0. 020 g/cm³,organic efficiency-98. 95% and lower separation size limit-down to 0. 25 mm.