Method for recovering rare earth from rare earth-containing wastewater

Abstract

The invention provides a method for recovering rare earth from rare earth-containing wastewater. The method comprises the following steps: 1, allowing the rare earth-containing wastewater to contact with an alkaline precipitating agent capable of precipitating rare earth metal elements, and carrying out solid-liquid separation after settlement to obtain a first solution and a rare earth precipitate; and 2, allowing the rare earth precipitate to contact with an aqueous solution containing hydrofluoric acid, and carrying out solid-liquid separation after settlement to obtain a second solution and rare earth fluoride. The method allows the rare earth metal elements to be effectively recovered, the recovery rate of the rare earth metal elements to be high and rare earth and fluoride in a raffinate obtained after recovery to reach environmental protection standard requirements, and the final raffinate subjected to an acid-base neutralization reaction is basically neutral and basically has no pollution to environment; and the rare earth fluoride obtained after recovery through the method is purified rare earth, can be used for molecular sieve modification, and can also be used in production of arc carbon rods and special steel alloys as an additive.

Description

technical field [0001] The invention belongs to the field of recovery and treatment of valuable metals, and in particular relates to a method for recovering rare earths from rare earth-containing wastewater produced in the production process of catalytic cracking catalysts. Background technique [0002] In the molecular sieve production process, it is processed by adding rare earth chloride (mainly composed of chlorides containing rare earth metal elements such as La, Ce, Pr, Nd and Sm, among which the content of rare earth metal elements La+Ce exceeds 80%) Modification, therefore, the molecular sieve production wastewater contains a large amount of pollutants, and its main discharge point is the wastewater discharged from the gelation of the molecular sieve production process and the filtration process of the washing unit. Among them, the main pollutant is suspended solids; and the direct discharge of wastewater Not only pollute the environment, but also cause the loss of r...

AI Technical Summary

Problems solved by technology

Domestic catalyst factories generally use the ammonia precipitation method to recover rare earths in the filtrate, but the concentration of the rare earth solution recovered by this method is low, the content of impurities is high, the exchange rate of rare earths is low when the rare earths are reused, and the thermal stability of the catalytic cracking catalyst obtained is deteriorated. When using catalysts, the ratio of the added amount of recovered rare earths to the amount of fresh rare earths needs to be less than 15%. Compared with the ammonia water method, the recovery of rare earths in the filtrate by the extraction method has the advantages of high recovery rate, good quality, simple recovery process, less pollution, and low production costs. Low advantages, but the extraction method has defects such as high investment cost and high content of organic matter in the generated wastewater