Abstract: The coarse-grained slime recovered from middling and refuse magnetic tailings through classification and thickening processes has an ash content ranging from 60% to 72%. If all the product is mixed with the middling product of heavy medium separation system, the composite middling product is rendered unsaleable due to its low calorific value. Mixing of the product partly with middling and refuse would cause a waste of coal resource. To tackle this issue, an analysis is made of the size composition of the middling and refuse magnetic tailigns as well as the density composition of the > 0.125 mm size in tailings. Based on results of analysis, the scheme for treating the tailing through classification with cyclone and separation with spiral separator is finally opted for use. Through the technical transformation, the classification efficiency is seen to go up to 73.78% with the proportion of total misplaced materials dropped to merely 5.92% and the through size and mean partition error lowered respectively to 0.13 mm and 2.51, well reflecting the high classification accuracy. The spiral separator works remarkably well with an organic efficiency reaching 90.56%, and a greatly lowered imperfection of 0.109. The calorific value of combined middling product is increased from 12.25 MJ/kg to 15.07 MJ/kg, and the tailing product of spiral separator is rejected as its calorific value is reduced down to 1.50 MJ/kg. The transformation work allows Ronghui Plant to gain an additional sales revenue of 3.1686 million yuan a year, bringing about a remarkable economic benefit for the plant.