Reduction of the slime contamination on fine coking coal by using the reverse-and-direct flotation process

Abstract

Slime contamination is an urgent problem that should be solved in coal flotation. The adverse effects of slime contamination, by which low-ash clean coal is covered by high-ash fine slime and hence cannot be separated through the direct flotation process, have been recognized for the past decades. In this investigation, to reduce slime contamination, the reverse-and-direct flotation process was proposed. Flotation results indicated that, based on the similar ash content, the concentrate yield increased by 7.36% using the reserve-and-direct flotation process compared with the two-steps direct flotation process. XPS (X-ray Photoelectron Spectroscopy) and SEM (Scanning Electron Microscopy) results verified that the reduction of fine clay minerals coating on the surface of clean coal was achieved and hence the flotation performance was improved with the reverse-and direct flotation process. Therefore, it can be arrived that the reverse-and-direct flotation process is a potential and effective separation method to upgrade the flotation performance of fine coking coal.