Sodium hydroxide recovery method of red mud

Abstract

The invention relates to a sodium hydroxide recovery method of red mud. The method comprises the steps of mixing the red mud and a displacement agent at a mass percentage of 5-20%, stirring in a pressing and heating stirring device for leaching for 15-45min at leaching temperature of 120-240 DEG C and leaching pressure of 0.5-2Mpa, performing pressure filtration after stirring and leaching to obtain qualified tailings and filtrate, returning the filtrate as a leaching solvent for recycling to leach the new red mud for 10-12 times, heating the recycled filtrate at 100-150 DEG C for evaporation for 60-120min, and rapidly cooling for crystallization of sodium hydroxide, wherein a leaching liquid-solid mass ratio is (2-5):1; a recovery rate of sodium hydroxide is equal to or greater than 97%; the purity of sodium hydroxide is equal to or greater than 99%; tail liquid after the crystallization is qualified. The method is short in operation time, high in sodium removal rate, low in leaching level and high in sodium hydroxide recovery rate, and the tailings are high in activity.

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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