Non-ionic polyethylene oxide frothers in graphite flotation

The Kringel Mine (Woxna Graphite AB) in Hälsingland, Sweden, is one of the largest graphite flake deposits in the world with over 10 million tonnes of ore suitable for open cast mining. Concentration of crystalline graphite is carried out through a combination of flotation, gravimetric and magnetic separation. In the present study, several polyethylene oxide type frothers were evaluated as flotation frothers for the graphic ore. From (a) laboratory dynamic and equilibrium surface tension experiments, (b) froth equilibrium height measurements, (c) bench scale flotation tests and (d) plant trials, it was shown that a polyoxypropylene glycol butyl ether (MW 300 and HLB 6.5) was the most effective frother for the graphic particles. The frother was found to produce closed packed, molecular cohesive films at the air/solution interface showing high elasticity at low concentrations, which appeared to prevent bubble coalescence. The plant has been successfully using this frother as a replacement for MIBC since July 1997.