Production method of calcium sulphate dehydrate and production device thereof

Abstract

The invention relates to a production method and device of calcium sulphate dehydrate. The method comprises the following steps: mixing an acid solution containing waste sulfuric acid with alkaline liquor containing calcium hydroxide, and adding to a neutralization pond; carrying out neutralization crystallization under full agitation of a propeller; controlling the concentration of the sulfuric acid added to the acid solution and the concentration of the calcium hydroxide added to the alkaline liquor within the range of 0.05-0.4mol / L; simultaneously, controlling the pH value of the mixed solution in the neutralization pond to be neutral, and controlling the detention pond time of the mixed solution in the neutralization pond for 20 minutes to 2 hours; outputting the mixed solution after neutralization crystallization through a liquid outlet formed at the lower part of the rear section of the neutralization tank as filtered water. By adopting the production method, flake crystal which is more beneficial to subsequent filtering is generated by a neutralization condition of controlling the acid and base of the liquid phase, and growth of the crystal in a flake form is kept, so that lamellar crystal capable of effectively reducing the moisture content after being filtered is provided for subsequent filtering, the filtering efficiency can be improved, the baking cost is reduced, and the transportation cost also can be further reduced, the transportation efficiency is improved, and recycling of renewable resources is powerfully facilitated.

Description

technical field [0001] The invention relates to a recycling method and equipment for industrial waste sulfuric acid liquid, more specifically, the present invention especially relates to a method and equipment for recycling industrial waste sulfuric acid liquid by adopting a neutralization crystallization process. Background technique [0002] Some production enterprises will discharge waste liquid containing higher concentration of sulfuric acid and lower concentration of hydrochloric acid and metal ions. Similar to the process of treating waste acid from a phosphoric acid plant to produce waste residue, industrial waste sulfuric acid liquid is neutralized to produce a large amount of calcium sulfate (gypsum) waste residue. With the deepening of the country's national policy of sustainable development, the awareness of environmental protection has attracted great attention among the general public. Issues such as environmental protection, resource regeneration, and recyclin...

AI Technical Summary

Problems solved by technology

[0003] Similar to the by-product gypsum residue of phosphoric acid plant, the gypsum obtained by the traditional neutralization treatment of industrial waste sulfuric acid liquid basically contains water, the water content can be as high as 40%, and the crystals are small, which is not conducive to drying

Due to the low value of by-products, the high moisture content before leaving the factory leads to low purity of gypsum and high transportation costs. In the absence of low-cost waste heat for drying treatment, the above problems directly affect the effective recycling of renewable resources. It is difficult to solve the problem of environmental pollution

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