Abstract: The problem confronting the plant′s coking coal washing system is the insufficiency of supply of dilution water to the secondary flotation circuit because of the limited volumes of 1st-stage thickener and circulating water pond.Through technical transformation, the consumption of circulating water of the overall washing system and the density of secondary flotation feed pulp are all reduced, bring about, therefore, a favorable social and economic result for the plant as the flotation concentrate is up to the standard in quality and a higher yield of clean coal can be obtained.