Effect of conditioning on selective flocculation with polyacrylamide in the coal reverse flotation

An attractive process of coal reverse flotation could become a viable option only if the huge consumption of quaternary amine collector could be significantly reduced. In the present search for the ways of reducing the collector dosage in this process the authors turned out their attention to polymers used as blinders in potash flotation. The batch flotation tests carried out using mechanical cells confirmed that some polyacrylamides worked very well as blinders in the coal reverse flotation process. At the same time, the standard flocculation tests were showing that the polyacrylamides acted as total non-selective flocculants. This obvious discrepancy revealed the importance of conditioning in the selective flocculation. The reverse flotation with a simultaneous use of the polyacrylamide, which significantly reduced consumption of amine collector, can be selective only after sufficient conditioning. It was found that the polyacrylamides with a different degree of anionicity responded differently to conditioning. Only the addition of the polymers with a lower degree of anionicity promoted the gangue flotation. The quality of the clean coal improved with conditioning by breaking up the totally flocculated larger flocs into selectively flocculated material that could then be floated with quaternary amine.