Crystallization method of ferrous sulfate heptahydrate in sulfuric acid method titanium dioxide production process

A technology of ferrous sulfate and titanium dioxide, which is applied to ferric sulfate, separation methods, crystallization and separation, etc., can solve the problems of lengthy freeze crystallization and vacuum crystallization processes, high supersaturation of crystallization feed liquid, complex equipment, etc. Effect of exchange time, elimination of steam and power consumption, and prevention of scale deposition

Pending Publication Date: 2021-02-12
CHENGDU QIANLIJIN TECHCAL INNOVATION CO LTD
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  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In order to save and utilize the energy consumption required for cooling crystallization of ferrous sulfate heptahydrate in the production process of sulfuric acid titanium dioxide, improve the efficiency of cooling crystallization, and meet the kinetic needs of cooling crystallization of mixed titanium liquid; overcome the existing method of mixing titanium liquid in the freeze crystallization method The high-level enthalpy is not utilized by evaporation, while the low-level enthalpy in the vacuum crystallization method depends on the surface adiabatic evaporation cooling steam injection and improved compressors and cooling fluids, etc., with high energy consumption, long time, and high supersaturation of the crystallization feed liquid. Deficiencies; Simplify the shortcomings of the existing freeze crystallization and vacuum crystallization process lengthy, complex equipment, cumbersome operation

Method used

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  • Crystallization method of ferrous sulfate heptahydrate in sulfuric acid method titanium dioxide production process
  • Crystallization method of ferrous sulfate heptahydrate in sulfuric acid method titanium dioxide production process
  • Crystallization method of ferrous sulfate heptahydrate in sulfuric acid method titanium dioxide production process

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Experimental program
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Effect test

Embodiment 1

[0037] Such as Figure 4 As shown, the mixed titanium liquid from the production process of sulfuric acid titanium dioxide at a temperature of 55°C is continuously fed into a 30 cubic vacuum crystallizer. After adding about 20 cubic meters of the liquid, the vacuum crystallizer is turned on to stir, and the water ring vacuum pump is started. At the same time, start circulating cooling water until the volume of the feed liquid reaches 30 cubic meters. After the overflow of the vacuum crystallizer begins to overflow, stop feeding, and the equipment continues to operate until the temperature of the material in the vacuum crystallizer drops to 35°C and the absolute pressure is 10KPa. .

[0038] Then continuously add 60 cubic meters of material liquid per hour to the vacuum crystallizer, and continuously discharge 56.8 cubic meters per hour from the overflow port of the vacuum crystallizer. Bypass, directly overflow to the circulation crystallization, until the material in the cir...

Embodiment 2

[0044] Such as Figure 4 As shown, the mixed titanium liquid from the production process of sulfuric acid titanium dioxide at a temperature of 60°C is continuously fed into a 30 cubic vacuum crystallizer. After about 20 cubic meters of the liquid is added, the vacuum crystallizer is turned on to stir, and the water ring vacuum pump is started. At the same time, start circulating cooling water until the volume of the feed liquid reaches 30 cubic meters. After the overflow of the vacuum crystallizer begins to overflow, stop feeding, and the equipment continues to operate until the temperature of the material in the vacuum crystallizer drops to 40°C and the absolute pressure is 10KPa. .

[0045] Then continuously add 60 cubic meters of feed liquid per hour to the vacuum crystallizer, and continuously discharge 55.6 cubic meters per hour from the overflow port of the vacuum crystallizer. Bypass, directly overflow to the circulation crystallization, until the material in the circu...

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Abstract

The invention discloses a crystallization method of ferrous sulfate heptahydrate in a sulfuric acid method titanium dioxide production process, which comprises the following steps: continuously addinga mixed titanium solution into a vacuum crystallizer, carrying out adiabatic evaporation by using vacuum formed by a water ring vacuum pump, removing heat with high enthalpy of heat, and carrying outfirst-step cooling; after cooling in the first step, continuously feeding into a circulating crystallization mixing tank to be mixed with circulating crystallization slurry returned by freezing crystallization, carrying out cooling and crystallization in the second step, and forcibly feeding into a freezing heat exchanger through a circulating pump to carry out heat exchange; cooling to the finalrequired crystallization temperature in the third step; and continuously sending one part of the crystallized slurry to the next process for solid-liquid separation to obtain ferrous sulfate heptahydrate. According to the method disclosed by the invention, a large amount of steam consumption for removing heat by low-level enthalpy of heat in the existing vacuum crystallization is saved, and the defects of concentration effect and low scaling efficiency of a freezing heat exchanger due to the fact that the existing freezing crystallization does not utilize the high-level enthalpy of heat of the mixed titaniferous solution for adiabatic evaporation are overcome.

Description

technical field [0001] The invention relates to a crystallization method of ferrous sulfate heptahydrate, in particular to a crystallization method of ferrous sulfate heptahydrate in the production process of sulfuric acid titanium dioxide. Background technique [0002] When the sulfuric acid method is used as the production of titanium dioxide, the titanium raw material is decomposed by sulfuric acid into a mixed solution containing titanyl sulfate, ferrous sulfate, part of free sulfuric acid and acid insoluble impurities. Acid hydrolysis mixed titanium solution at -65°C; in order to meet the requirements of subsequent processing and hydrolysis and precipitation of titanium dioxide, it is necessary to remove part of the ferrous sulfate in the mixed titanium solution; the removal method is to crystallize the mixed titanium solution in the form of cooling to precipitate sulfuric acid heptahydrate Ferrous crystals and then solid-liquid separation to reduce the content of ferro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G49/14B01D9/00B01D9/02C01G23/053
CPCC01G49/14B01D9/0022B01D9/0004C01G23/0532Y02P20/10
Inventor 龚家竹
Owner CHENGDU QIANLIJIN TECHCAL INNOVATION CO LTD
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