Method for pre-treating phosphorite by using acidic waste water in the production process of titanium pigment

Abstract

The invention discloses a method for pre-treating phosphorite of wet process phosphoric acid by using acidic waste water in the production process of titanium pigment, which comprises the following steps: (1), collecting the acidic waste water into an acidic waste water storage groove, controlling the acid degree to be 2 to 5 percent and the total iron concentration to be 0.3 to 0.5 percent; (2), adding the acidic waste water and the milled phosphorite in a solid-to-liquid ratio of 2-5:1 into a reaction groove for reaction; and (3), performing solid-liquid separation on the slurry which is obtained in the step (2) to obtain a solid phase, namely the required phosphorite. The content of magnesium in the phosphorite which is treated by the method is reduced by over 70 percent, the loss ratio of the phosphorus is controlled to be within 1 percent; when the phosphorite which is treated by the process is used for producing the phosphoric acid by a wet method, the consumption of the sulfuric acid for mine per ton is reduced by about 10 percent; and the acidic waste water pretreats phosphorite and then is delivered to a sewage station for treatment, the consumption of lime or other alkaline substance is reduced by 60 percent compared with the mode of directly delivering the waste water to the sewage station, so the economical efficiency of the process is high.

Description

technical field [0001] The invention discloses a method for pretreating phosphate rock of wet-process phosphoric acid by using acid waste water in the production process of sulfuric acid titanium dioxide, relates to the integrated technology of waste water treatment in titanium chemical industry and phosphate rock purification in phosphorus chemical industry, and belongs to titanium chemical industry The technical field of comprehensive utilization of waste by-cycle in the phosphorus chemical industry. Background technique [0002] Most of the titanium dioxide enterprises in my country use the sulfuric acid method as the production method. In the sulfuric acid method titanium dioxide production process, the intermediate titanyl sulfate needs to be hydrolyzed into metatitanic acid and sulfuric acid. Every ton of titanium dioxide produced will produce 5-6 tons of 20 %-30% concentration of waste sulfuric acid, and in the subsequent metatitanic acid washing process, about 16-25 t...

AI Technical Summary

Problems solved by technology

For acidic wastewater, due to the low concentration of sulfuric acid in acidic wastewater (concentration 3% to 5%, 4% on average) and more impurities, most of the production processes that require sulfuric acid cannot be directly used, and if sulfuric acid is recovered by concentration, it will be Consumes a lot of energy and has no economic benefit

Chinese patent CN1220970 discloses a process route for producing magnesium sulfate by reacting the acidic waste water with magnesium oxide, etc., which not only solves the environmental protection problem, but also realizes economic benefits. However, the production of magnesium sulfate is a small industry and cannot balance the production of titanium dioxide at all. A large amount of acidic wastewater

However, since the process uses magnesium bisulfate to remove magnesium, there is a same ion effect, and the magnesium removal rate will inevitably decrease.

Regardless of using dilute sulfuric acid to remove magnesium or using magnesium bisulfate to remove magnesium, sulfuric acid will be consumed, which cannot solve the purpose of reducing the acid consumption of wet-process phosphoric acid production

It has practical significance only when the magnesium content in phosphate rock is too high, which seriously affects the operation of wet-process phosphoric acid, and in the process of operation, either the loss of phosphorus is large, or the rate of magnesium removal is low

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