Method for removing zirconium, zinc and chromium in red mud

Abstract

The invention discloses a method for removing zirconium, zinc and chromium in red mud. The method includes the steps that malic acid and acetic acid are mixed at first to be prepared into mixed organic acid, and then the mixed acid and the red mud are mixed and stirred; qualified tailings and waste liquor are obtained after filter pressing; and when heavy metal of the waste liquor is removed through recycle leaching until the pH value of the liquor is larger than 6, quick lime is added into the waste liquor for stirring, and a qualified solution can be obtained after filtering. The zirconium content in the qualified tailings is lower than 10 mg/kg, the chromium content is smaller than 5 mg/kg, the zinc content is smaller than 1 mg/kg, the residual organic acid can achieve biodegradation, harm to people, livestock and plants is avoided, and thus the qualified tailings can be used as a modifying agent for alkaline soil. The pH value of the qualified solution is 7-8.5, and the concentration of the zirconium, chromium and zinc is lower than 0.02 mg/L. The mixed organic acid is used for removing heavy metal in the red mud, and hence the method has the characteristics that chemical consumption is small, the removal rate of the heavy metal is high, the tailings can be used directly after treatment, the waste liquor can be recycled, the pH value of the waste liquor is high, the heavy metal content of the waste liquor is high and treatment and recycling of the waste liquor are easy.

Description

technical field [0001] The invention relates to the technical field of red mud comprehensive treatment, in particular to a method for removing zirconium, zinc and chromium in red mud. Background technique [0002] Bayer process red mud is the tailings produced during the process of smelting alumina from bauxite using the Bayer process. It is a strong alkaline solid pollutant containing various heavy metals such as zirconium, zinc and chromium. body and soil pollution. In addition, Bayer process red mud can be used as raw materials for extracting rare and precious metals and preparing building materials and environmental adsorption materials (Zhu Guohai, Wang Keqin, Wang Hao, et al. Research on the recovery of titanium dioxide from sulfuric acid leaching red mud slag[J]. Nonferrous Metals (Smelting Part), 2012, 7: 23-26; Nan Xiangli, Zhang Tingan, Liu Yan, etc. Analysis of Comprehensive Utilization of Red Mud in my country [J]. Journal of Process Engineering, 2010, 10(S1): 23...

AI Technical Summary

Problems solved by technology

However, the heavy metals in it restrict its efficient and comprehensive utilization, so it is necessary to remove heavy metals

[0003] At present, there is no research specifically on the removal of heavy metals from red mud. The research on the removal of heavy metals from other soils or solid wastes mostly uses hydrochloric acid, sulfuric acid, oxalic acid, and citric acid as leaching solvents (Huang Chuan, Li Liu, Huang Shan, et al. et al. Study on mixed leaching of heavy metal contaminated soil with oxalic acid and EDTA[J]. Journal of Environmental Engineering, 2014, 8(8): 3480-3486; Research on the effect of lifting [J]. Journal of Environmental Science, 2015, 35(8): 2573-2581; Zhao Youcai, Xie Tian, ​​Gao Xiaofeng, etc. A method to stabilize construction waste polluted by various heavy metals. Chinese invention patent: CN 104190692 A; Zhao Youcai, Gao Xiaofeng, Xie Tian, ​​etc. A treatment method for high-concentration heavy metal polluted construction waste. Chinese invention patent: CN 103978013 A)

Using inorganic acids such as hydrochloric acid to remove heavy metals has the characteristics of high removal efficiency, but the tailings after treatment are highly acidic, and subsequent treatment of waste liquid is difficult

Using oxalic acid and EDTA to remove heavy metals has problems such as low heavy metal removal rate, poor selectivity, low concentration of heavy metals in the removal solution and low pH value of the solution, difficult treatment of the removal solution, and difficulty in the treatment of organic matter such as EDTA remaining in the tailings.

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