Three-stage negative pressure evaporation crystallization treatment process and device for titanium dioxide waste sulfuric acid

Abstract

The invention discloses a three-stage negative pressure evaporation crystallization treatment process and a device for titanium dioxide waste sulfuric acid. The process comprises the following steps:crystallizing and separating of ferrous sulfate in a titanium dioxide waste sulfuric acid stock solution by using a stock solution crystallization system is carried out, and centrifugally separating are carried out to obtain a ferrous sulfate heptahydrate solid and mother liquor; through the cooperative cooperation of a double-effect evaporation system, a single-effect evaporation system and a concentration and crystallization system, the possibility of crystallization and blockage of materials in the evaporator is eliminated, and the stable operation of the device is ensured; centrifugate from the stock solution crystallization system is evaporated and concentrated in the double-effect evaporation system to improve acidity and then is introduced into a front section of the concentration and crystallization system; cooling, crystallizing and filter pressing are carried out to obtain a large amount of sulfate solids; wherein the mass concentration of sulfuric acid in filtrate reaches 50%, the filtrate is continuously introduced into the single-effect evaporation system for forced circulation, the concentration of waste sulfuric acid is increased to the maximum extent, the concentrated waste sulfuric acid solution is introduced into the rear section of the concentration and crystallization system, cooling crystallization is performed, a large amount of sulfate solids are obtained through filter pressing, and a regenerated sulfuric acid solution with the mass concentration larger than or equal to 70% is obtained.

Description

technical field [0001] The invention relates to the technical field of waste sulfuric acid treatment, in particular to a three-stage negative pressure evaporation and crystallization treatment process and device for titanium dioxide waste sulfuric acid. Background technique [0002] Sulfuric acid is widely used in chemical, steel and other industries. In many production processes, the utilization rate of sulfuric acid is very low, and a large amount of sulfuric acid is discharged along with acid-containing wastewater. If the waste water is discharged into the environment without treatment, it will not only acidify the water body or soil, cause harm to the ecological environment, but also waste a lot of resources. [0003] The waste sulfuric acid discharged from the iron and steel industry or other industries has the characteristics of high metal ion concentration and high sulfuric acid concentration, and has been managed as hazardous waste by various countries. The United ...

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Problems solved by technology

[0008] The purpose of the present invention is to overcome the problem that the evaporator of titanium dioxide waste sulfuric acid is easily blocked during the evaporation process of the existing two-stage evaporation crystallization process for waste sulfuric acid treatment, and the two-stage evaporation crystallization process causes a large amount of waste of sulfuric acid and ferrous sulfate resources. , providing a three-stage negative pressure evaporation crystallization process and device for titanium dioxide waste sulfuric acid, adopting the technical scheme of the present invention, first adopting the stock solution crystallization system to separate the ferrous sulfate crystals in the titanium dioxide waste sulfuric acid stock solution and centrifuge to obtain seven Ferrous sulfate water solid and titanium dioxide waste sulfuric acid centrifugal liquid, and then the titanium dioxide waste sulfuric acid centrifugal liquid is completely processed through the cooperation of the second-effect evaporation system, single-effect evaporation system and concentrated crystallization system. The evaporation temperature required by this device is low, and it can Ensure continuous and stable production while reducing engineering investment, and both the two-effect evaporation system and the single-effect evaporation system adopt forced circulation to eliminate the possibility of material crystallization and blockage in the evaporator and ensure the stable operation of the device; from the raw liquid crystallization system Titanium dioxide waste sulfuric acid centrifugal liquid is evaporated and concentrated in the two-effect evaporation system to increase the acidity, and then enters the front section of the concentrated crystallization system, cools and crystallizes, and press-filters a large amount of sulfate solids, and the mass concentration of sulfuric acid in the filtrate reaches 50%, and the filtrate continues to enter the single-stage Continue the forced circulation in the high-efficiency evaporation system to increase the concentration of titanium dioxide waste sulfuric acid to the greatest extent. The concentrated titanium dioxide waste sulfuric acid liquid enters the rear section of the concentration crystallization system, cools and crystallizes, and press-filters a large amount of sulfate solids to obtain a mass concentration of ≥70 %, metal ion content ≤ 40g / L regenerated sulfuric acid solution; this device effectively utilizes waste heat to reduce operating costs, and at the same time improves the recovery rate of sulfuric acid and ferrous sulfate. The whole system makes full use of wet and latent heat, saving raw steam consumption, Reduced operating costs

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