Experimental study on enhancement of low-rank coal flotation with compound frother

In order to explore the effects of compound frother for enhancement of flotation of low-rank coal, dynamics test is conducted with n-amy lalcohol, BIBC, octanol and polyethylene glycol(PEG)along with the tests on surface tension and foam stability, so as to reveal the enhancing mechanism of frother in flotation of such coal.Result of flotation test indicates that when each of the frother is used alone, a highest concentrate yield and a highest flotation rate can be achieved with the use of PEG while pentanol proves to be the least effective among the four frothing agents selected for use; when three kinds of short-chain alcohols are used in combination with PEG, the yield of flotation concentrate tends to increase with the increase of the proportion of PEG, and is noticeably higher compared with the use of short-chain alcohole alone; and the combined use of n-amyl alcohole and PEG can produce the best flotation result.It can be seen from the results of test on surface tension and foam stability of different frothing agents, the surface tension of compound frother is closer to that of PEG, indicating that PEG plays a dominant role in performance in the mixed solution; and with the combined use of n-amyl alcohole and PEG, the solution surface tension reduction and foaming capacities and foam stability can all reach the highest level in this case.This is attributed to the fact that the presence of a closely bonded layer at the gas-liquid interface formed by synergistic adsorption of long and short chains helps enhance the Gibbs-Marangoni effect and hence the foam stability.