Research On Adjusting And Controlling Water Quality Of Circulated Coal Slurry And Effect Of Water Quality On Flotation

The coal production of China has exceeded 2.8 billion tons. Separation of one ton of coal will need three tons of water, and two-thirds of China's coal is located in the Northwest dry region, therefore the contradiction between coal development and utilization of water resource is serious. Coal slurry is the waste water of coal separation process, and is also highly concentrated micro-solid-liquid suspension-dispersion system which is mainly consisted of clay minerals. Due to its poor settling property and forced circulation system feature with high concentration, it is difficult to maintain normal operation of coal preparation plant, and massive slime water is lost which causes serious resource waste and environmental pollution.Starting from the nature of coal slime, through experimental and theoretical analysis using various analytical instruments, such as FTIR, X-ray diffraction and so on. The coal quality characteristic research indicated that there have some main reasons that lead difficult settling of xing-tai coal slurry.Those reasons are:mostly gangue mineral the coal contains is kaolinite which frangibility,easy to clay and surface electronegative, and the high content of fine-grade materials. Floatability analysis shows that when the refined coal ash is smaller than 10.2%, this coal slime belongs extremely difficult to float.Research on the effect of compositon of minerals and water quality on settling properties of coal slurry:the basic reason why slime water is difficult to settle is highly concentrated micro-solid-liquid suspension-dispersion system which is mainly consisted of clay minerals and low hardness of coal slurry. The original hardness of coal slurry is determined by the chemical reaction result between mineral composition of slime water and solution, and settling property of coal slurry is determined by the original hardness. The coal slurry which is mainly consisted of clay minerals is difficult to clarify because of its low original hardness; the coal slurry which is mainly consisted of calcium and magnesium mineral salts is easy to clarify because of its high original hardness.Due to the water quality of coal slurry decide settling properties and clarify impact, found the system of adjusting and controlling water quality of circulated coal slurry. This system including four aspects of water quality adjustment agent, detection means, detection indicator and the method of water quality adjustment.Research on the effect of water quality on coal slime flotation. Through man-made add a variety of inorganic salts adjustment water quality, research on the effect of the ion content on flotation, fouces on Ca2+. The experimental results show that:univalent cations don't affect the flotation of coal, and the divalent, trivalent metal ion will increase the yield and ash content of coal flotation concentrate. And analyse the impact mechanism.