Study on the intermediate products of Fischer Tropsch synthesis as a collector for coal flotation: Molecular dynamics and experimental studies

Abstract

As a general coal flotation collector, diesel is often used in the industrial production process, and diesel is not renewable and belongs to the hazardous reagents, so there is an urgent need to find a new type of flotation collector to replace diesel. In this paper, three intermediate products produced by Fischer-Tropsch synthesis technology were used as collector. And five emulsifiers, Span80, Tween80, sodium dodecyl sulfate, betaine, and hexadecyl trimethyl ammonium bromide were used to emulsify 3# synthetic oils to produce emulsion with good stability. The flotation performance of three synthetic oil products as well as emulsified collectors were investigated, and the adsorption capacity of 2# and 3# synthetic oils on the coal surface was studied by molecular dynamics simulation. The results showed that the flotation results of synthetic oil were better than those of diesel, with collector 1# having the best flotation results. The oil in water (O/W) emulsion formulated with Tween80 had the best properties, and remained unstratified in half a month, and there were a large number of 0.1–1 μm oil droplet in the emulsion. Moreover, the emulsified collector of Tween80 with oil-water ratio of 4:6 showed excellent flotation performance, which was nearly 1.5 % higher than that of diesel. The molecular dynamics results are consistent with the synthetic oil flotation results at high concentration dosages, where 3# oil showed better adsorption behavior on the coal surface than 2# oil, but was slightly inferior to diesel adsorption. Therefore, the synthetic oil can be completely used as a substitute for diesel, and the emulsion with oil-water ratio of 4:6 formulated with Tween80 has excellent flotation performance and greatly saves the actual consumption of synthetic oil, which has very high economic and environmental value.