A kind of method that red mud reclaims sodium hydroxide

Abstract

The invention relates to a method for recovering sodium hydroxide from red mud. The method is to mix the red mud with a replacement agent with a mass fraction of 5-20%, and then carry out stirring and leaching in a pressurized heating and stirring device. 2~5:1, the leaching time is 15~45min; after the stirring leaching is completed, the qualified tailings and filtrate are obtained through pressure filtration, and the filtrate is returned as a leaching solvent for recycling to leach new red mud. The number of cycles is 10~12 times, and then The circulating filtrate is heated and evaporated at a temperature of 100-150°C for 60-120 minutes, and then rapidly cooled to crystallize sodium hydroxide. The recovery rate of sodium hydroxide is greater than 97%, and the purity of sodium hydroxide is greater than 99%. The liquid is a qualified tail liquid. The invention has short operation time, high sodium removal rate, low leaching series, high activity of tailing residue and high recovery rate of sodium hydroxide.

Description

technical field [0001] The invention belongs to the technical field of comprehensive treatment of red mud, and in particular relates to a method for recovering sodium hydroxide from red mud. Background technique [0002] Red mud is the tailings produced in the process of alumina production. Its particle size is extremely fine, and it is a source of alkaline pollution. Damming of red mud will not only cause groundwater and soil pollution, but also cause air pollution by flying with the wind. Therefore, it must be Take effective measures to deal with this kind of solid waste. In addition, red mud is a secondary mineral resource containing a variety of valuable metals, rich in titanium, scandium, vanadium, iron, aluminum and rare earth and other valuable metals. The recovery of valuable metals in red mud mainly focuses on rare and precious metals, while for sodium in red mud, most of the research is on the removal, but little attention is paid to recycling. At present, the pr...

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Problems solved by technology

The removal rate of sodium in the carbon dioxide leaching desodium process is low, the activity of the treated red mud is low, and the treated wastewater cannot be recycled (Wang Zhi, Han Minfang, Zhang Yihe, etc. Research on wet carbonization dealkalization process of Bayer red mud. Silicic acid Salt Bulletin, 2013, 32 (9): 1851-1855)

[0003] Therefore, the current red mud desodination process has defects such as long operation time, low desodination rate, many leaching stages, low activity of tailings after desodination, and inability to recover sodium hydroxide and comprehensive utilization of desodination liquid.

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