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Method for recovering rare earth, thorium and iron in waste residue of rare earth acid technological process

A recovery method and rare earth technology, applied in the direction of improving process efficiency, etc., to achieve the effect of solving radioactive waste residue

Inactive Publication Date: 2013-07-03
BAOTOU RES INST OF RARE EARTHS +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Zhang Guocheng et al. analyzed the weight loss curve and differential thermal curve of mixed concentrate and concentrated sulfuric acid roasting, and concluded that at 200~300 °C, phosphoric acid dehydrates into pyrophosphoric acid, and pyrophosphoric acid reacts with thorium sulfate to form insoluble thorium pyrophosphate, so No relevant literature has been found for the recovery and utilization of thorium resources in this slag

Method used

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  • Method for recovering rare earth, thorium and iron in waste residue of rare earth acid technological process
  • Method for recovering rare earth, thorium and iron in waste residue of rare earth acid technological process
  • Method for recovering rare earth, thorium and iron in waste residue of rare earth acid technological process

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Embodiment 1: by 0.4:1 acid slag ratio with 20.0g water immersion waste residue and acidity be the HNO of 3.0mol / L 3 The solution was mixed and placed in a beaker, covered with a glass, and kept stirring at 80°C for 1 hour for leaching. Filtrate hot, wash the filter cake three times, and combine the filtrate and washing liquid. The filter cake was dried at 100°C to obtain 9.7g secondary waste residue, ThO 2 Dissolution rate is 95.0%, REO dissolution rate is 51.2%, Fe 2 o 3 The dissolution rate is 86.3%, and the radioactive specific activity of the secondary waste residue is less than 7.4×10 4 Bq / Kg. The combined solution was extracted with primary amine, and back-extracted with nitric acid to form a thorium nitrate solution. The remaining liquid NaOH adjusts the pH to 4.5 to form Fe(OH) 3 By-products, the filtrate is rare earth feed liquid.

Embodiment 2

[0017] Example 2: Mix 20.0 g of water leaching waste residue with HCl solution with an acidity of 2.0 mol / L according to the ratio of 0.8:1 to acid residue, put it in a beaker, cover it with a watch glass, and keep stirring at 95°C for 1 hour for leaching. Filtrate hot, wash the filter cake three times, and combine the filtrate and washing liquid. The filter cake was dried at 100°C to obtain 9.0 g of secondary waste residue, ThO 2 Dissolution rate is 99.1%, REO dissolution rate is 62.1%, Fe 2 o 3 The dissolution rate is 88.0%, and the radioactive specific activity of the secondary waste residue is less than 7.4×10 4 Bq / Kg. The combined solution was extracted with primary amine, and back-extracted with nitric acid to form a thorium nitrate solution. residual liquid NH 3 ﹒ h 2 O adjusts the pH to 5.0 and forms crude Fe(OH) 3 The product, the filtrate is rare earth material liquid.

Embodiment 3~7

[0018] Embodiment 3 ~ 7: according to the ratio of acid slag, waste residue and different concentration of H 2 SO 4 The solutions were mixed, heated and stirred for leaching for 2 hours. Table 2 is ThO under different leaching conditions 2 , REO and Fe dissolution rate results. The leaching solution is extracted with primary amine, and back-extracted with nitric acid to form a thorium nitrate solution. The remaining liquid MgO adjusts the pH to 5.2 to form crude Fe(OH) 3 The product, the filtrate is rare earth material liquid.

[0019] Table 2 Example 3 ~ 7 leaching conditions and results

[0020]

[0021] 8. Leaching liquid circulation leaching: Take about 20.0g of water leaching waste residue sample, add H with an acidity of 2 mol / L according to the acid residue ratio of 0.6:1 2 SO 4 130ml of the solution, covered with a surface dish, leaching at 80°C for 1 hour. Filtration, the filtrate is a pickling solution. Rinse the filter cake three times and discard the wa...

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Abstract

The invention relates to a method for recovering rare earth, thorium and iron in waste residue of a rare earth acid technological process. The method is characterized by comprising the following steps: using the waste residue produced in the rare earth acid technological process as a raw material; according to the ratio of the acid to the residue of (0.2-1.0):1, mixing the waste residue of the rare earth acid technological process with one or more of HCl solution, H2SO4 solution and HNO3 solution with the concentration of 1mol / L-4mol / L; performing agitation leaching at a temperature of 60 DEG C to boiling temperature, wherein a leaching finishing point is determined based on the percentage content of ThO2 less than 0.05% and specific radioactivity small than 7.4*104 Bq / Kg in secondary waste residue; filtering and washing a filter cake to obtain a leaching solution and the secondary waste residue; enabling the leaching solution to be a thorium nitrate solution after being subjected to primary amine extraction and nitric acid reverse extraction; using alkali to adjust the pH value of surplus raffinate to be 4.5-5.5 so as to precipitate Fe(OH)3 by-products; and obtaining filter liquor namely rare feed liquid products. The method has the advantages that dissolving out of REO, ThO2 and Fe in the waster residue by water logging is realized; the amount of the secondary waste residue is reduced below 50 % of the amount of the original residue; and the content of the ThO2 is less than 0.05 percent and the specific radioactivity is small than 7.4*104 Bq / Kg in the secondary waste residue.

Description

Technical field: [0001] The invention relates to a method for recovering rare earth, thorium and iron in the waste residue of the rare earth acid process, and belongs to the technical field of hydrometallurgy and industrial environmental protection. Background technique: [0002] As we all know, Baiyan Obo rare earth mine is a mixed ore of bastnaesite and monazite, and the rare earth concentrate produced by it contains thorium (in ThO 2 Total) content is 0.15~0.25%. In the early 1980s, with the improvement of the grade of rare earth concentrates, in order to prevent impurities such as thorium from entering the water leaching solution, simplify the process and reduce costs, the Beijing General Research Institute of Nonferrous Metals studied the intensive roasting process of concentrated sulfuric acid. When the temperature is raised above 400°C, thorium exists in the waste residue in the form of insoluble thorium pyrophosphate, thereby forming radioactive waste residue. In t...

Claims

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Application Information

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IPC IPC(8): C22B7/04C22B60/02C22B59/00
CPCY02P10/20
Inventor 崔建国马莹张春新琚建勇于晓丽张赟馨曹鸿璋
Owner BAOTOU RES INST OF RARE EARTHS
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