Flotation Process Optimization for Fine Coal (<0.5mm) with Enhanced Hydrophobicity and Economic Analysis

Exploration of flotation process and conditions for fine coal with particle size up to 0.5mm was conducted. Infrared spectrum analysis indicated that kerosene was an effective collector, which physically adsorbed onto the surface of fine coal and increased its hydrophobicity. Orthogonal experiments with five factors and five levels revealed that the dosages of kerosene and octanol significantly affected the results of rough selection, and further single-factor and two-factor flotation experiments were conducted after determining the levels of other factors. Eventually, a two-stage flotation process was developed to obtain a yield of 29.47% and an ash content of 9.73% for the clean coal, which met the requirements for coking coal. Disaggregation and reselection processes could remove almost all quartz and part of kaolinite from the clean coal, and profit of 442.38 yuan per ton of coal and a profit margin of 77.81% could be achieved. The analysis of clean coal showed that the effective particle size of the coal samples mainly ranged from 100 to 500um, and the relative size order of effective particle size was rough flotation clean coal < fine coal < flotation tailings. No incomplete crushing or overcrushing was observed.