Method for purifying and removing silicon and aluminum from nitric rare earth feed liquid

Abstract

A method for purifying rare earth nitrate feed liquid by removing silicon and aluminum belongs to the field of hydrometallurgy and is characterized in that the method comprises the following steps: pre-treating the rare earth nitrate feed liquid to ensure that the residue of SiO2 is lower than or equal to 30mg / L and the residue of Al2O3 is lower than or equal to 0.3%; adjusting the pH value to 3 to 6; adding the rare earth nitrate feed liquid to a reaction kettle; stirring and heating to the temperature of 70 to 90 DEG C; adding cerium carbonate by the proportion being 1% to 5% of the TREO amount (Total Rare Earth Oxide amount) in the feed liquid; then, slowly adding an oxidizing agent by 0.5% to 2% of the TREO amount; stirring; heating and boiling for more than 30 minutes; standing and settling for more than 12 hours; extracting the supernatant fluid and the feed liquid with residue respectively; and filtering. In the invention, the rare earth nitrate feed liquid with the content of SiO2 being lower than 1mg / L and Al2O3 / TREO being lower than or equal to 100ppm can be obtained through purification and impurity-removal of the invention; and by purifying the feed liquid, not only the final product with high purity can be obtained, but also the layering speed of extraction can be accelerated by applying the method to the pre-treatment for extracting technological feed liquid, and the problems caused by the impurities of silicon and aluminum in the extraction process can be solved.

Description

technical field [0001] The invention belongs to the field of hydrometallurgy and relates to SiO in rare earth nitrate liquid 2 、Al 2 o 3 The method of purification and removal. Background technique [0002] In hydrometallurgy, in addition to the main metal, the feed liquid obtained from the leaching and decomposition of raw materials also contains a large amount of unnecessary harmful impurity elements. These harmful impurities must be separated and removed before precipitation and extraction of the main metal. With the higher and higher requirements for product purity, the requirements for the purification and removal of impurities of feed liquid as intermediates are also higher and higher. In the hydrometallurgy of rare earths, a large amount of silicon and aluminum elements are often associated with raw materials, and it is difficult to separate rare earths due to their similar properties to silicon and aluminum elements. [0003] Various impurity removal methods have...

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Problems solved by technology

[0003] Various impurity removal methods have been proposed in the existing impurity removal process ("Rare Earth" 2001, 122(2): 10-13), but either the process is too complicated or the cost is too high, and the most fundamental thing is that the impurity cannot be completely removed Meet the requirements of high-purity products