EFFECTS RULE and MECHANISM of WATER HARDNESS on COAL FLOTATION

摘要

Laboratory experiments and industrial scale tests were designed to study the effect of water hardness on coal slurry flotation.The results show that the ash content and the yield of flotation clean coal both increase gradually at the beginning and then tend to a constant as the water hardness increases,the yield reaches its maximum ahead of the ash content and their increment rate both are about 1％-2 ％.The interaction energies between the particles in coal-kaolinite suspensions were calculated using extended DLVO (Derjaguin-Landau-Verwey-Overbeek) theory.The results indicate that as water hardness increases, coal particles coagulate each other at first; then coal particles coagulate with kaolinite particles; however,no coagulation occurs between redundant kaolinite particles, so they still suspend in water.The coagulation rule can explain the change of yield and the ash content of clean coal as water hardness.