A kind of method for preparing calcium sulfate dihydrate whisker from phosphogypsum

Abstract

The present invention relates to the technical field of chemical raw material preparation, and particularly to a method for preparing calcium sulfate dihydrate crystal whisker from phosphorus gypsum. The method comprises the following steps: preparing calcium sulfate dihydrate without impurities, preparing a crystal whisker, washing, and drying to obtain the calcium sulfate dihydrate crystal whisker. By preheating hydrochloric acid and matching the hydrochloric acid with phosphorus gypsum at a certain ratio at a constant temperature, the reaction can proceed and the materials is not wasted, the impurities contained in the phosphorus gypsum can be properly removed maximatily, the impact rate of impurities on the generation of calcium sulfate dihydrate crystal whisker is decreased, the content of calcium sulfate component is increased, the production rate of calcium sulfate dihydrate crystal whisker is improved and the production costs of calcium sulfate dihydrate crystal whisker prepared by comprehensively utilizing phosphorus gypsum are reduced.

Description

technical field [0001] The invention relates to the technical field of chemical raw material preparation, in particular to a method for preparing calcium sulfate dihydrate whiskers from phosphogypsum. Background technique [0002] Phosphogypsum is an accompanying substance in the production process of wet-process phosphoric acid, and its main component is calcium sulfate dihydrate. At present, natural stacking is the main treatment method for phosphogypsum. The stock of phosphogypsum in my country is more than 300 million tons, and it is increasing at a scale of 40-50 million tons per year. Stacking, fluoride, free phosphoric acid, P contained in phosphogypsum 2 o 5 , phosphate and other impurities will cause serious harm to the ecological environment; at the same time, the application of phosphogypsum in the fields of building materials, soil amendments and road construction also has problems such as high energy consumption, secondary pollution, and low added value of prod...

AI Technical Summary

Problems solved by technology

[0009] The above methods have their own shortcomings, mainly in the low purity of calcium sulfate whisker product yield, low whiteness, small aspect ratio, and complicated preparation process; specifically reflected in: phosphogypsum is directly used for calcium sulfate without pretreatment The preparation of whiskers or the preparation of calcium sulfate whiskers after pretreatment, but whether it is phosphogypsum without pretreatment or after pretreatment, its impurities are difficult to be fully removed, so that many of the phosphogypsum contained in it Various impurities will affect the quality of whiskers, such as magnesium delays the transformation of gypsum crystal form, iron will widen the crystal, aluminum affects the length and width of calcium sulfate dihydrate crystals, and excessive sulfate radicals will cause strong agglomeration of crystals, etc. At the same time, the purity and whiteness of calcium sulfate whisker products will also be low due to impurities

[0010] Among the various pretreatment methods for preparing calcium sulfate whiskers from phosphogypsum, the whiskers prepared by ball milling have rough surface and low length-to-diameter ratio; the screening conditions are difficult to control, high energy consumption, large investment, and difficult to realize industrial production ;Water washing consumes a lot of water, and sewage treatment is difficult; the phosphogypsum produced by wet-process phosphoric acid has strong acidity, and the cost of neutralization with lime is high. The yield of leaching and removing impurities is low, and the energy consumption per unit mass of calcium sulfate whisker is large

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