Lignite cleaning in NaCl solutions by the reverse flotation technique
Haijun Zhang 1  
,   Qingxia Liu 1, 2
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China University of Mining and Technology
University of Alberta
Haijun Zhang   

China University of Mining and Technology, No.1 University Road, xuzhou city, jiangsu province, China, 221116 xuzhou, China
Publication date: 2015-03-26
Physicochem. Probl. Miner. Process. 2015;51(2):695–706
The possibility of cleaning BD lignite (low ash content) and IM lignite (high ash content) in NaCl solutions using a reverse flotation technique was studied. Preliminary test results indicated that BD lignite cannot be cleaned effectively in the traditional manner, gangue was floated first rather than combustible material. Further studies indicated that the lignite cleaning in NaCl solutions using the reverse flotation technique is possible. However, a large quantity of DAH was required. A lower ash content of the concentrate can be obtained by the addition of NaCl. The yield of the concentrate can be improved by the addition of starch at the expense of a small increase in the ash content. Under the test conditions, a concentrate ash content of 11.44% at a 67.38% yield was obtained for a feed ash content of 15.19% for BD lignite. Similarly, a concentrate ash content of 32.90% at a 25.08% yield was obtained for a feed ash content of 57.40% for IM lignite. In addition, the reverse flotation efficiency index and the flotation kinetics were considered to evaluate lignite reverse flotation as a function of NaCl concentration. The results indicated that the addition of NaCl does not significantly increase the efficiency index for IM lignite compared with distilled water. However, for BD lignite, the efficiency index can be increased from 14.71% to 19.75% in 0.6 M NaCl solution. The magnitude of the flotation rate constant k and the maximum ash recovery ε∞ significantly increased with the increase in NaCl concentration.