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Calcium oxalate waste residue solid-solid conversion recovery method for oxalic acid

A technology of calcium oxalate and oxalic acid, which is applied in the field of hydrometallurgy, can solve the problems of large residual acid, high recovery cost, and long process flow, and achieve the effects of increasing conversion rate, reducing decomposition, and reducing sulfuric acid consumption

Active Publication Date: 2020-10-30
BAOTOU RES INST OF RARE EARTHS +2
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The technical problem solved by the present invention is to provide a method for recovering oxalic acid through solid-solid conversion of calcium oxalate waste residue. The conversion efficiency of oxalic acid is high, and the consumption of sulfuric acid is small, which overcomes the large amount of residual acid in the traditional process, the long process flow, and the recovery of oxalic acid. Disadvantages such as high cost

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  • Calcium oxalate waste residue solid-solid conversion recovery method for oxalic acid

Examples

Experimental program
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Effect test

Embodiment 1

[0030] Take 100g of calcium oxalate mixed waste residue containing rare earth and magnesium. The waste residue has a moisture content of 28.6% and a REO content of 0.16%. Mix it with 59.9g of concentrated sulfuric acid with a mass percentage concentration of 80%. The exothermic time is 10 minutes, and the conversion rate of calcium oxalate is 62%. After the two phases are solidified, enter the reactor, and undergo solid-solid roasting conversion at 150°C for 40 minutes to obtain a mixed crystal product of calcium sulfate and oxalic acid. Then, under the condition of 90°C, according to the solid-to-liquid weight ratio of water and calcium oxalate (dry weight) of 1:2, the water and the mixed crystal product were slurried, mixed and leached, and filtered to obtain an oxalic acid solution. The total conversion rate of calcium oxalate reached 95.7%. The sulfuric acid concentration of the solution is 1.5%.

Embodiment 2

[0032] Take 500g of calcium oxalate mixed waste residue containing rare earth, manganese, and barium. The waste residue has a moisture content of 30.9%, a calcium oxalate content of 84.7%, and a total oxalate of 97.6%. For the reaction, the reaction temperature is 60-100° C. and the reaction time is 3 minutes, and the conversion rate of calcium oxalate is 65%. After the two phases are solidified, enter the reactor, and undergo solid-solid roasting conversion at 100°C for 60 minutes to obtain a mixed crystal product of calcium sulfate and oxalic acid. Then, under the condition of 50°C, according to the solid-to-liquid weight ratio of water and calcium oxalate (dry weight) of 1:4, the water and the mixed crystal product were slurried, mixed and leached, and filtered to obtain an oxalic acid solution. The total conversion rate of calcium oxalate reached 98.4%. The sulfuric acid concentration of the solution is 5%.

Embodiment 3

[0034] Take 900g of calcium oxalate mixed waste residue containing rare earth and magnesium. The waste residue has a moisture content of 28.6% and a REO content of 0.16%. The exothermic time is 10 minutes, and the conversion rate of calcium oxalate is 62%. After the two phases are solidified, enter the reactor, and undergo solid-solid roasting conversion at 150°C for 20 minutes to obtain a mixed crystal product of calcium sulfate and oxalic acid. Then, under the condition of 60°C, according to the solid-to-liquid weight ratio of water and calcium oxalate (dry weight) of 1:3, the water and the mixed crystal product were slurried, mixed and leached, and filtered to obtain an oxalic acid solution. The total conversion rate of calcium oxalate reached 96.2%. The sulfuric acid concentration of the solution is 3%.

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Abstract

The invention discloses a method for recovering oxalic acid by the solid-solid transformation of calcium oxalate waste residue, which comprises the following steps: mixed waste residue is mixed with concentrated sulfuric acid, and after uniform agitation, curing reaction takes place; after the two phases are cured, solid-solid roasting transformation is carried out in a reactor, so that calcium sulfate and oxalic acid mixed crystals are obtained; water is then used for slurrying the mixed crystal product, and after mixing, extracting and filtration, an oxalic acid solution is obtained. The oxalic acid transformation efficiency of the method is high, the consumption of sulfuric acid is little, and defects existing in conventional processes, such as a large remaining amount of acid, long process flow and high recovery cost, are overcome.

Description

technical field [0001] The invention relates to a hydrometallurgy technology, in particular to a method for recovering oxalic acid through solid-solid conversion of calcium oxalate waste residue. Background technique [0002] In the metallurgical industry, oxalic acid or soluble oxalate precipitation is often used to remove calcium, magnesium, barium and other impurity ions, thereby forming insoluble oxalate precipitation residue. For example, in the high-temperature roasting process of concentrated sulfuric acid mixed rare earth concentrate, the rare earth roasted ore is immersed in water, neutralized by magnesium oxide, and ammonium bicarbonate precipitates to obtain ammonium sulfate wastewater containing magnesium, calcium, and rare earths and mixed rare earth carbonate products. In order to prevent calcium sulfate crystallization during the process of concentrating magnesium ammonium sulfate, it is necessary to remove calcium impurities in the solution with soluble oxala...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C51/02C07C55/06C22B3/46
CPCC07C51/02C22B3/46C07C55/06Y02P10/20
Inventor 崔建国侯睿恩安卫国周建国郝肖丽王哲郝晓燕张丽石鑫高婷
Owner BAOTOU RES INST OF RARE EARTHS