Study and application of the characteristic flotation process at Qinxin Coal Preparation Plant

Following a brief account of the work made by some plants on improvement and optimization of flotation process over the recent years, the paper presents a detailed introduction to the course of the development in this respect at Qinxin Coal Preparation Plant. The improvement of the flotation process has gone through several stages starting from one flotation process to one roughing + one cleaning process, one roughing + one scavenging process to finally the process of one roughing + one scavenging plus staged recovery of concentrate through scavenging of tailing which is in current use at Qinxin Plant — a process that is suited to the property of the easily floatable coal treated by the plant. Field application shows that a significant reduction of circulating water can be expected; for treating low-sulfur coal, the ash of concentrate can be lowered to 7.21% while the ash of tailing can be increased from 74.09% to 82.51%, and for treating high-sulfur coal, the ash of concentrate can be further reduced to 6.78% and the ash of final tailing product can be increased from 57.93% to 82.37%; and though scavenging of tailing, a middling product with a calorific value of 19.25 MJ/kg can be obtained, adding a daily output of middling product of 200 tons. Through analysis of the concentrate products of different cells obtained through scavenging process, the ash of the concentrate product of the fist cell is 16.18% which is lower than the boundary ash value of the gravity separated product, making it possible for the concentrate product to blend with the final clean coal product to increase the daily output of clean coal product by 120 tons. The operation of the characteristic flotation process currently applied at Qinxin Plant has yield a good result, providing a new approach for high-efficiency flotation and high-value utilization of easy-to-float fine coal.