Method for extracting rare earth from precipitation sludge of rare earth wastewater pool

A sedimentation slag and wastewater tank technology, applied in the direction of improving process efficiency, etc., can solve the problems of organic phase emulsification, fine sedimentation particles, and difficulties in sedimentation enrichment, and achieve the effects of low cost, efficient recovery, and easy operation

Active Publication Date: 2017-05-10
JIANGXI UNIV OF SCI & TECH
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Problems solved by technology

The precipitation method is relatively simple. Usually, by adjusting the pH, the rare earth is precipitated with rare earth hydroxide and separated from water. However, when the pH is not controlled properly, impurity metal ions such as Ca 2+ 、Al 3+ , Fe 3+ Co-precipitation of hydroxides will also be generated; and the formed precipitate particles are relatively small, even in a colloidal state, making it difficult to enrich the precipitate
When oxalic acid is used to precipitate rare earth, since the solubility of aluminum oxalate and iron oxalate is much greater than that of rare earth oxalate, the separation of rare earth from iron and aluminum can be realized, but the calcium ion in the solution is also easy to react with oxalic acid to form a precipitate, which is not conducive to the separation of rare earth and calcium. separate
The extraction method has a large enrichment factor and high efficiency, and can realize multi-stage series connection and automatic continuous operation. However, when the content of calcium, iron, and iron impurities exceeds the standard, it is easy to cause emulsification of the organic phase and difficulty in phase separation of the extraction system. After back extraction by special means, The content of impurity ions in the stripping solution is still difficult to reach the standard
Studies have shown that the rare earths in the sediment residue of the rare earth wastewater tank mainly exist in the form of oxalate and carbonate; and the sediment particles are small and densely packed, which makes acid leaching very difficult

Method used

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  • Method for extracting rare earth from precipitation sludge of rare earth wastewater pool

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Take 10g of the sediment residue from the rare earth wastewater pool, in which the content of REO is 30.66 wt.%, and the content of CaO is 29.72 wt.%. It is roasted at 850°C for 1.5h and taken out. The roasted product is further ground, water-soluble, filtered and dried. The dried roasted product was leached for 1.0 h under the conditions of hydrochloric acid concentration of 3 mol / L, liquid-solid ratio of 6:1 mL / g, and reaction temperature of 80°C, and filtered to obtain 130 ml of a leaching solution containing 23.03 g / L of rare earths, of which The leaching rate is 97.65%. At 30°C, add 10.4g of ammonium sulfate to the rare earth leaching solution, stir well to dissolve, stop stirring, then add 1.2 times the theoretical amount of oxalic acid, adjust the pH of the solution to 1.5~2, stand at 80°C for 6h, filter and wash 7.07g of precipitated slag was obtained by drying. The rare earth content in the precipitated slag was 41.97wt.%, and the calcium content was 0.2 wt.%. ...

Embodiment 2

[0024] Take 50g of the sediment residue from the rare earth wastewater pool, in which the content of REO is 27.55 wt.%, and the content of CaO is 26.54 wt.%. After roasting at 900°C for 2 hours, the roasted product is further ground, dissolved in water, filtered and dried, and dried The final roasted product was leached for 1.0 h under the conditions of nitric acid concentration of 4 mol / L, liquid-solid ratio of 7:1 mL / g, and reaction temperature of 70°C to obtain 580 ml of leaching solution containing 23.70 g / L of rare earth, and the leaching rate of rare earth was 99.79% %. At 50°C, add 17.4g of ammonium sulfate to the leaching solution, stir to dissolve, stop stirring, then add 1.5 times the theoretical amount of oxalic acid, adjust the pH of the solution to 1.5~2, let stand at 90°C for 4 hours, filter, wash, After drying, 37.81g of precipitated slag was obtained. The rare earth content in the precipitated slag was 28.77wt.%, and the calcium content was 5.23wt.%. The recove...

Embodiment 3

[0026] Take 25g of the sediment residue from the rare earth wastewater pool, in which the content of REO is 31.68 wt.%, and the content of CaO is 28.53 wt.%. After roasting at 800°C for 2 hours, the roasted product is further ground, dissolved in water, filtered and dried, and dried The final roasted product was leached for 1.5h under the conditions of sulfuric acid concentration of 3mol / L, liquid-solid ratio of 8:1mL / g, and reaction temperature of 60°C to obtain 310ml of leaching solution containing 23.10g / L of rare earth, wherein the leaching rate of rare earth was 90.33 %. Add 26.35g of ammonium sulfate to the leaching solution, stir well to dissolve, stop stirring, then add 1.3 times the theoretical amount of oxalic acid, adjust the pH of the solution to 1.5~2, stand at 50°C for 8 hours, filter, wash, and dry to obtain 17.58g of precipitate The rare earth content in the precipitated slag is 41.10 wt.%, and the calcium content is 0.18 wt.%. The recovery rate of rare earth i...

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Abstract

The invention discloses a method for recovering rare earth from precipitation sludge of a rare earth wastewater pool, comprising the main steps: firstly, preroasting the precipitation sludge of the rare earth wastewater pool, then leaching the roasted product with mineral acid to obtain a leach solution containing rare earth, and sequentially adding ammonium sulfate and oxalic acid to the leach solution so the rare earth is separated from soluble impurities in a manner of solid phase precipitation. The method has a simple process, convenient operation and low cost, solves the problem of difficult complete separation in a condition of coexistence of rare earth and calcium in a solution, can efficiently recover the rare earth in the precipitation sludge of the rare earth wastewater pool, and realizes separation of rare earth from calcium, aluminum and iron; the recovery rate of rare earth reaches above 99%; and the recovered rare earth oxide can be returned to a production main flow of a rare earth smeltery.

Description

technical field [0001] The invention relates to the technical field of industrial waste residue treatment, in particular to a method for recovering rare earths from sedimentation residues in rare earth wastewater pools. Background technique [0002] Rare earth is a non-renewable important strategic resource, and its consumption is increasing day by day. A large amount of wastewater is generated in the rare earth smelting and production process. Smelting enterprises usually need to be equipped with special wastewater pools for collection. There are many types of anions and cations in wastewater, and they are easy to combine to produce precipitation. Over time, a large amount of solid sediment residue will accumulate in the wastewater pool. The rare earth content in the slag can reach about 30%, accompanied by calcium, iron, aluminum and other metals. If it is not treated in time and effectively, it will not only cause a waste of precious rare earth resources, but also if the...

Claims

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Application Information

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IPC IPC(8): C22B59/00C22B7/00
CPCC22B7/007C22B59/00Y02P10/20
Inventor 梁勇黎永康邹瑜温葆林肖燕飞李飞
Owner JIANGXI UNIV OF SCI & TECH
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