Comminution and Ash Reduction of Coal Particles
In the mineral processing industry, there are two purposes in crushing and grinding operation. Namely one is reduction of the particle size and the other is liberation of the target minerals from locked particles prior to their recovery. To predict the particle size distribution in such process, the population balance method composed of the selective and breakage functions is very useful.
In this study, Japanese coals were ground in a vibrating ball mill and the distributions of ash and combustibles as well as the size distribution were analyzed. In grinding these coals, combustibles were concentrated in the fine products, and then ash content of the fine products was lower than that of the coarse ones. A new breakage function for ash distribution in coal grinding process was proposed to interprete the concentration of ash into the coarse products, and solved simultaneously with the well-known selection and breakage functions which had been established to calculate the time-dependent size distribution of particles.
In addition the effect of ammonia treatment on coal comminution rate was tested and the effectiveness was observed in the initial stage of comminution.
KeywordsSteel Ball Coal Particle Alumina Ball Ammonia Treatment Population Balance Equation
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