Harmless and resource utilization method of steel industry chromium-containing wastewater

Abstract

The invention discloses a harmless and resource utilization method of steel industry chromium-containing wastewater. The harmless and resource utilization method of the steel industry chromium-containing wastewater comprises the following steps: 1) adding steel rolling system acid-washing waste liquid into the chromium-containing wastewater, reducing Cr<6+> in the chromium-containing wastewater into Cr<3+> by utilizing the acidic environment provided by the acid-washing waste liquid and the Fe<2+> therein, and oxidizing the Fe<2+> into Fe<3+>; 2) adding alkali into the reduced wastewater, neutralizing, enabling the Cr<3+> to generate Cr(OH)3 precipitate and the Fe<3+> to generate Fe(OH)3 precipitate, and performing mud and water separation to obtain sludge containing chromium and iron; 3)performing concentration treatment on the sludge containing chromium and iron to obtain homogenous slurry; and 4) feeding the homogenous slurry into a sintering system, mixing the homogenous slurry and the sintering raw materials according to a certain proportion and sintering to obtain a sintered ore finished product for ironmaking and steelmaking. By the method, up-to-standard discharge of the chromium-containing wastewater is realized and resource utilization of the chromium element in the wastewater is realized.

Description

technical field [0001] The invention relates to a method for treating wastewater in the iron and steel industry, in particular to a method for harmless and resourceful utilization of chromium-containing wastewater in the iron and steel industry. Background technique [0002] In the post-treatment process of galvanized sheet and color-coated sheet products in the iron and steel industry, the mature chromate passivation process is mostly used. This method will produce a certain amount of chromium-containing wastewater, and the chromium in the wastewater mainly exists in the form of high-valence Cr(Ⅵ). Cr(Ⅵ) is highly toxic and belongs to the first category of pollutants. It can accumulate in the environment and the human body for a long time and have long-term adverse effects on the human body. Excessive intake of Cr or long-term exposure to chromium-containing wastewater can cause cancer to the human body. . In industrial wastewater, the state stipulates that the discharge ...

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Problems solved by technology

The advantage of this method is that the amount of chromium ion removed by biomass increases with the increase of biomass. It has the advantages of simple method, low energy consumption and operation cost, and less sludge generated. The disadvantage is that the treatment effect is affected by environmental factors. Large, and because heavy metals are toxic to microorganisms, it is difficult to isolate bacteria suitable for high-concentration environments. Therefore, the biological treatment of chromium-containing wastewater is still in the exploratory stage, and there are few engineering applications

In addition, in addition to the above three methods, there are many other methods for the treatment of chromium-containing wastewater, such as adsorption, ion exchange, and electrodialysis. These methods are all based on the principle of physical separation, and can achieve different degrees of chromium removal. Good effect on the removal of chromium element, but there are problems in the reuse and utilization of chromium element in the follow-up, and the operating cost is high, so it has no advantages in engineering

[0004] In the above method, no matter whether the treated wastewater meets the standard or not, there is still a certain amount of chromium in the wastewater, and the discharge into the water body will still have a certain impact on the water body environment.

In addition, no matter which method is used, there will be chromium-containing sludge after solid-liquid separation. According to the national hazardous waste list, metallurgical chromium-containing sludge is a hazardous waste, and its treatment methods mainly include solidification, landfill, and underground storage. Regardless of solidification, landfill and underground storage, the treatment process is long, it is difficult to achieve complete harmlessness, and the problem of landfill needs to be considered. Due to the complex components of chromium-containing sludge in steel mills, the sludge treatment and disposal process is improper. will cause serious environmental pollution

[0005] To sum up, the above-mentioned methods have various problems such as complicated process, inconvenient operation and management, large process investment, high operating cost, unstable discharge, and easy to cause secondary pollution.

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