Crushing and Disintegration Characteristics of Middling Coal: A Study on Optimal Particle Size for Flotation

Exploring the crushing and disintegration rules of middling coal, the following results were obtained: the sink-float test showed that the smaller the crushing particle size, the less middling coal content in the intermediate density grade, and the more complete the disintegration between coal and mineral. The middling coal density grade content and ash content were stable when crushed to 0.3-0.5mm, considering factors such as industrial crushing cost, water absorption, and subsequent sorting difficulty, the subsequent sorting test crushed the coal to 0.5mm. From the selectivity curve of the +0.5mm particle size, it can be seen that it is extremely difficult to select coarse particles when the middling coal is crushed to 1.5mm and 1mm; from the flotation results of the -0.5mm particle size, the theoretical yield of middling coal changes as the crushing particle size decreases and the disintegration continues, and the stepwise release diagram of 0.5mm coal slurry shows that the slope of the clean coal yield and ash content curve is larger at the 10%-20% ash content stage, therefore, the difficulty in sorting middling coal lies in reducing the ash content of clean coal, and it is necessary to explore suitable flotation process conditions and procedures to achieve better re-selection results.