Method for extracting rare earth in ammonium-free rare earth mother liquor by precipitation, impurity removal, middle ore return

Abstract

The invention relates to a method for extracting rare earth in an ammonium-free rare earth mother liquor by precipitation, impurity removal and return of middlings. Calcium oxide or magnesium oxide serving as an ammonium-free precipitating agent is adopted for impurity removal and precipitation, co-precipitating is preferentially conducted on aluminum and rare earth, a sodium hydroxide solution isadded into an obtained co-precipitated solid to convert aluminum hydroxide into metaaluminate for dissolving, and a high-purity rare earth solid product is obtained. The method solves the problem ofammonia nitrogen pollution in a rare earth mine, and the intermediate solid is returned to a previous operation section at the same time so that not only can sufficient recovery of rare earth be ensured, but also an alkaline substance can be provided for the previous operation section, the use amount of calcium oxide or magnesium oxide serving as the precipitating agent in the whole operation is decreased, and the production cost is reduced.

Description

technical field [0001] The invention relates to a method for recovering rare earths from an ammonium-free rare earth mother liquor by adopting processes of precipitation, impurity removal and middle ore return, which is suitable for the recovery of rare earth mother liquors in the in-situ leaching process of ionic rare earth mines, and belongs to the field of hydrometallurgy. Background technique [0002] Due to their special properties, ionic rare earth ores cannot be obtained by physical beneficiation methods such as gravity separation, magnetic separation, and electric separation, and can only be obtained by chemical leaching. The development of ore leaching agent has gone through the process of developing from sodium chloride to ammonium sulfate. However, with the large-scale use of ammonium sulfate, researchers have found that a large amount of ammonium salt will cause eutrophic pollution of rare earth mines and surrounding water bodies. At present, new ammonium-free le...

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