The coal washing (coal preparation) process is different, and the raw materials (auxiliaries, additives) used are also different. (1) Heavy medium coal preparation requires the use of weighting agents (heavy medium powder); (2) Flotation requires the use of flotation agents (including frothers, collectors, inhibitors and regulators); (3) Jig selection Coal and shaker coal preparation only use water without any additives.
Among them, heavy medium coal separation is currently the most advanced gravity coal washing method, which is a technology that separates raw coal in a heavy medium with a density (specific gravity) higher than water. There are two types of media used in heavy media coal preparation: heavy liquid and heavy suspension. Heavy liquids are aqueous solutions of various soluble high-density salts (such as zinc chloride solution) or high-density organic liquids (such as bromoform, carbon tetrachloride). The resuspension liquid is made of high-density mineral fine powder (such as magnetite, loess pyrite slag, river sand, barite, gangue, flotation tailings, etc.), and the most commonly used one is magnetite. The heavy medium powder you mentioned refers to the above-mentioned materials, and its function is to increase and adjust the density of the coal washing medium. Heavy liquids are expensive, mostly toxic and corrosive, and difficult to recycle, so they are rarely used in industry. Resuspension is cheap, non-toxic, non-corrosive, easy to recycle, and the prepared suspension has a wide density range. Therefore, resuspension is widely used in industry.