A kind of production method of low calcium lanthanum carbonate

Abstract

The invention discloses a method for producing low-calcium lanthanum carbonate, which comprises the following steps: S1, adding dilute sulfuric acid to a mixed rare earth chloride solution for calcium and barium removal treatment; S2, adding barium chloride to the filtrate to remove sulfate radicals, mixing The rare earth chloride solution is extracted and separated to obtain a lanthanum chloride solution; S3, adding lanthanum carbonate seed crystals and carbonate solution to the lanthanum chloride solution, controlling the pH of the solution to be 6-6.6, and performing the first precipitation; S4, adding lanthanum carbonate to the solution Add the soluble salt of bicarbonate to the medium to carry out the second precipitation; S5, filter to get the filter residue, after the filter residue is washed with water, centrifuged and dried, it is packaged and put into storage. Through the method of pre-removing calcium + pH value control + two precipitations, the present invention removes the calcium impurities mixed in lanthanum carbonate, and also recovers unreacted rare earths in the solution, and the calcium content of lanthanum carbonate is reduced to below 500 ppm, which satisfies the The requirements of the market have solved the deficiencies of the existing technology.

Description

technical field [0001] The invention relates to the technical field of rare earth hydrometallurgy, in particular to a production method of low-calcium lanthanum carbonate. Background technique [0002] Now the rare earth market is getting more and more sluggish, so to have a market for rare earth products, the quality of rare earth products must be improved, especially for the more popular lanthanum products, if the quality is not improved, there will be no market. The bastnaesite used now is a product obtained by the combined beneficiation method of magnetic separation and flotation (referred to as rare earth concentrate), which inevitably contains a certain amount of calcium fluoride or calcium carbonate in the beneficiation procedures. Rare earth impurities, about 60% of the non-rare earth impurity calcium in the rare earth concentrate after the acid-base combined method enters the rare earth chloride product, and then after extraction and separation, about 20% of the cal...

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Problems solved by technology

However, this method neither considers the range of calcium content in the initial rare earth feed liquid nor the pH of the solution when the rare earth feed liquid reacts with sodium carbonate, resulting in a higher calcium content in the actually obtained rare earth carbonate product than the theoretical value, especially for rich When the lanthanum chloride feed solution with a large amount of calcium salt is collected, the calcium content in the obtained lanthanum carbonate product is not less than 0.05% as claimed in the patent, but is in the range of 1000-2500ppm. The concentration of rare earth ions is also higher than the declared value, and when precipitating rare earth carbonate, the formation of calcium carbonate precipitation is related to the pH of the solution. If the pH of the solution is not accurately controlled in the early stage of the reaction, in order to suppress the formation of calcium carbonate precipitation as much as possible, Even if sodium bicarbonate is added in the later stage of the reaction, a certain amount of calcium carbonate precipitates will still be mixed in the precipitate, especially when the calcium content in the solution is relatively large (the content is 9-14g / L), the more calcium carbonate precipitates will be mixed in the precipitate , resulting in excessive calcium content in rare earth carbonate products. Therefore, although this method can effectively remove calcium and magnesium impurities in rare earth carbonates, the removal effect is not satisfactory, and the obtained rare earth carbonate products cannot meet market requirements.

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