Method for preparing mixed rare earth carbonate by using mixed precipitant in sulphuric acid system

Abstract

The invention discloses a method for preparing mixed rare earth carbonate by using a mixed precipitant in a sulphuric acid system. The method comprises the following steps: with continuous stirring, mixing ammonium bicarbonate and industrial-grade ammonia water in the molar ratio of 5.6:4.4-10:1, and adding water at 15-30 DEG C to enable the concentration of the mixed precipitant to be 3 to 7 mol / L; placing the mixed precipitant and a seed crystal into a reaction tank, wherein the seed crystal is the mixed rare earth carbonate which is produced by taking mixed sulphuric acid rare earth solution as a raw material; with continuous stirring, controlling the temperature of the solution in the reaction tank to be 20-50 DEG C, and slowly adding the mixed sulphuric acid rare earth solution into the reaction tank, wherein the adding time is 2 to 6 hours, and the using amount enables the pH of the solution equal to be 6.5-7; after the ending of precipitating, aging for 0.5-2 hours at the temperature of 30-50 DEG C with stirring; filtering and washing a precipitant to obtain the mixed rare earth carbonate and ammonium sulphate-containing precipitation wastewater. According to the method, theoutput quantity of the precipitation wastewater can be reduced.

Description

technical field [0001] The invention relates to a rare earth hydrometallurgy technology, in particular to a method for preparing mixed rare earth carbonate by using a mixed precipitant in a sulfuric acid system. Background technique [0002] At present, concentrated sulfuric acid high-temperature roasting method is mostly used in the decomposition of Baotou rare earth concentrate, and the mixed rare earth sulfuric acid solution produced is purified and precipitated with ammonium bicarbonate solution. The method for industrialized production of mixed rare earth carbonate is to add ammonium bicarbonate solid into water at a temperature of 45-55° C., and prepare a 2.0-2.8mol / L ammonium bicarbonate solution as a precipitant and mixed rare earth sulfate (REO=0.1539-0.2012mol / L) solution reaction. After the reaction is completed, the mixed rare earth carbonate can be obtained after the slurry is filtered and washed, the total amount of rare earths (REO) is between 43% and 46%, a...

AI Technical Summary

Problems solved by technology

During the application of this process, due to the low solubility of ammonium bicarbonate, the concentration of the precipitant prepared is low, so more precipitation wastewater is produced, resulting in higher treatment costs for subsequent precipitation wastewater

The precipitant needs to heat the water during the preparation process, which consumes a lot of heat energy, resulting in high heating costs