Process for preparing high-strength gypsum from salt chemical wastes

Abstract

The invention belongs to the technical field of reusing of salt chemical wastes, and discloses a process for preparing high-strength gypsum from salt chemical wastes. The process for preparing the high-strength gypsum from salt chemical wastes comprises the following steps: step 1, mixing a calcium chloride solution with old brine and stirring to obtain mixed slurry of sodium chloride and dihydrate gypsum; step 2, desalting and washing the mixed slurry to obtain purified dihydrate gypsum slurry; step 3, regulating the dihydrate gypsum slurry to be acidic, adding an activity agent and a crystalmodifier, and preparing alpha-hemihydrate gypsum by a normal-pressure hydrothermal method; step 4, carrying out solid-liquid separation; step 5, carrying out desalting, acid removal and washing; andstep 6, drying to obtain the high-strength gypsum finished product. The process for preparing the high-strength gypsum from the salt chemical wastes has the beneficial effects that active growth of the intermediate dihydrate gypsum crystals is controlled effectively, and the strength of the high-strength gypsum is improved; the normal-pressure hydrothermal method is adopted, energy consumption islow, investments are low, and a crystal form is easy to control; and the problem of solid wastes is solved effectively, and the requirements of industrial and green sustainable development are met.

Description

technical field [0001] The invention relates to the technical field of salinization industrial waste reuse, in particular to a process for preparing high-strength gypsum from salt chemical waste. Background technique [0002] Whether the raw salt in the chlor-alkali industry is solid salt or liquid salt, there is a problem of removing sulfate radicals. At present, there are traditional barium chloride method or newly-built membrane method for removing sulfate radicals. Among them, barium sulfate precipitated by barium chloride method is treated as solid waste, which pollutes the environment and wastes resources. At the same time, barium chloride is harmful to the human body; membrane The method is to enrich the sulfate ion to obtain Glauber's salt decahydrate, which has excess production capacity. [0003] However, using the calcium chloride waste liquid produced by the ammonia-soda method soda ash plant as a raw material, the sulfate radical is converted into calcium sulfa...

AI Technical Summary

Problems solved by technology

[0004] The high-strength gypsum prepared by the existing technology is small in size and low in strength. The main reason is that the intermediate calcium sulfate dihydrate used to prepare high-strength gypsum has many internal structural defects, and the crystal morphology cannot be accurately controlled.

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