Method for treating and recycling rare earth oxalate precipitation mother solution

Abstract

The invention discloses a method for treating and recycling a rare earth oxalate precipitation mother solution. The method comprises the steps of: adding a corresponding high-purity rare earth solution or high-purity rare earth carbonate into the precipitation mother solution to separate oxalic acid out in the form of rare earth oxalate precipitates, wherein the filtered mother solution can be directly used for preparing hydrochloric acid solutions of different concentrations to serve as refluxing acid or washing acid for extraction separation of rare earth elements, so that water and hydrochloric acid in the mother solution can be recycled totally; and returning the filtered rare earth oxalate precipitates to a rare earth precipitation process to serve as crystal seeds which can be added in a refined oxalic acid dissolution process or in a precipitation barrel before precipitation starts respectively, and ageing, washing, filtering and calcining the precipitates to obtain a high-purity rare earth product, thereby recycling originally non-precipitated rare earth and subsequently added rare earth completely. According to the invention, the comprehensive recycling problem of the rare earth oxalate precipitation mother solution of a rare earth separation plant is solved, and the method is simple and feasible, is suitable for recycling all rare earth oxalate precipitation mother solutions, and has a wide application prospect.

Description

technical field [0001] The invention belongs to the field of rare earth hydrometallurgy and industrial wastewater treatment, and mainly solves the problem of recycling rare earth products, especially the rare earth oxalate precipitation mother liquor in the production of high-purity rare earth, and can make the mother liquor absolutely Most of the water, oxalic acid, hydrochloric acid and rare earths are recycled, saving costs and reducing wastewater discharge. technical background [0002] The rare earth feed liquid after rare earth extraction and separation is usually separated from water and a large amount of inorganic salts and acids by precipitation. Oxalic acid precipitation is generally used to precipitate rare earth elements from high-purity single rare earth solutions. In the rare earth oxalate precipitation process, in order to ensure the precipitation rate of rare earth and the separation selectivity of impurity ions, it is necessary to add excess oxalic acid. ...

AI Technical Summary

Problems solved by technology

These methods have their own advantages and disadvantages. For example, although the neutralization method can eliminate the impact of acid on the environment, it consumes alkali and discharges a large amount of saline wastewater.

Using the extraction method, oxalic acid can be extracted, but under acidic conditions, the extraction efficiency of oxalic acid is low, and it is necessary to use appropriate reagents to extract the extracted oxalic acid from the organic phase, the process is more complicated

Distillation or vacuum distillation can recover acid, water and rare earth, but it consumes a lot of energy and requires high equipment

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