Method for recovering rare earths from vacuum-calcium-thermic-reduction rare-earth slag

Abstract

The invention particularly relates to a method for recovering rare earths from vacuum-calcium-thermic-reduction rare-earth slag. The method comprises the following steps: (1) uniformly mixing sodium silicate and vacuum-calcium-thermic-reduction rare-earth slag powder; (2) roasting the mixture obtained in the step (1) in a high-temperature furnace; (3) leaching the roasting slag obtained in the step (2) with water, and then, carrying out filtrating and baking; and (4) putting the baked roasting slag in a hydrochloric solution, and carrying out filtrating, thereby obtaining a rare earth containing filtrate. By adopting the sodium silicate roasting-acid dipping method, the rare earths are efficiently and thoroughly extracted from the calcium-thermic-reduction rare-earth slag, the maximum leaching rate exceeds 99% and is greatly superior to treatment effects of the current processes, the process is simple, and operation is facilitated.

Description

technical field [0001] The invention belongs to the technical field of industrial waste residue treatment, and in particular relates to a method for recovering rare earth from industrial waste residue. Background technique [0002] The vacuum thermal reduction process is a common method for the production of rare earth metals. Generally speaking, metal calcium is often used as a reducing agent in the production of high melting point rare earth metals (such as Ga, Tb, Dy, Ho, Er, Y, Lu metals, Tb-Dy alloys, etc.), and the raw material is mainly rare earth fluorides, resulting in The main component of the reduced slag is CaF 2 , and it contains 5% to 8% of rare earths (REO), which are mainly rare earth metals, rare earth oxides and rare earth fluorides. These reduced slags have always been treated as industrial waste or waste, which seriously wastes rare earth resources. Therefore, carrying out research on recovery of rare earths from calcareous rare earth slag, turning was...

AI Technical Summary

Problems solved by technology

According to the existing research, rare earth metals and rare earth oxides in calcithermic reduction rare earth slag are easier to extract, such as Chen Dongying et al. .Jiangxi Nonferrous Metals, 2004,03:27-30.) Using mixed acid leaching for calcithermally reduced rare earth slag containing 5% to 7% of rare earth, the recovery rate of rare earth was 65.41%, but the acid leaching residue still contained 2.28 % of rare earths, the main reason is that the rare earths in the form of fluoride in calcithermal reduction slag are difficult to be leached by acid

Images