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Process of recycling oxalic acid from rare earth wet-method smelting oxalic acid precipitation waste water

A technology of wet smelting and grass precipitation, which is applied in the preparation of carboxylate, chemical instruments and methods, and the preparation of organic compounds, etc., can solve the problems of difficult treatment, waste of resources, and harsh working environment, and achieve low processing cost and high process efficiency. simple effect

Inactive Publication Date: 2015-07-08
NANJING GW ENVIRONMENT ENG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the lime neutralization method is mainly used to treat this kind of wastewater in China. Although this method is simple to operate and low in cost, the working environment is harsh, the amount of slag is large, and it is difficult to handle. At the same time, the oxalic acid in the wastewater has not been recovered, resulting in a great waste of resources.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Collect a large amount of precipitation mother liquor and washing precipitation wastewater produced in the precipitation process of rare earth wet smelting, add calcium oxide to the rare earth grass precipitation wastewater, adjust the pH to 8~9, when it is observed that no precipitation is produced, filter and collect the solid part. Then, add dilute sulfuric acid with 1~2 times the mass of calcium oxalate to the solid part of calcium oxalate, heat it to 70~90℃, stir well, and separate the solid and liquid when no precipitation occurs. Take the liquid part and remove this liquid. The temperature of the part is cooled to 0-15°C, and it is observed that after no more crystals are precipitated, the solid and liquid are separated, and the solid part is taken and dried to obtain high-purity oxalic acid.

[0024] The recovered oxalic acid can be reused in the precipitation process of rare earth hydrometallurgy.

[0025] In order to realize resource recycling, we add fresh dilute ...

Embodiment 2

[0027] Grass sedimentation wastewater: pH value 1.23, conductivity 35.8ms / cm, oxalic acid content 1%,

[0028] Add calcium oxide to 500 mL of straw sedimentation wastewater and adjust the pH to 8.5. When no precipitation is observed, filter and collect the solid part of calcium oxalate. The wet weight of calcium oxalate is 19.6g, and then add to the solid part of calcium oxalate. 30 mL of dilute sulfuric acid with a mass fraction of 35%, heat to 82°C and stir well until no precipitation occurs, separate the solid from the liquid, take the liquid part, cool the liquid part to 5°C, observe that there are no more crystals After precipitation, solid-liquid separation is performed, and the solid part is taken and dried to obtain high-purity oxalic acid. The recovered oxalic acid has a mass of 2.59 g and a purity of 95.6%.

[0029] The recovered oxalic acid can be reused in the precipitation process of rare earth hydrometallurgy.

[0030] In order to realize resource recycling, we add fre...

Embodiment 3

[0032] Grass sinking wastewater in a factory: flow rate is 12m 3 / h, pH value 1.1, conductivity 35.8ms / cm, oxalic acid content 0.92%.

[0033] Grass sedimentation wastewater enters the collection tank, pumps it into the reaction tank, adds calcium oxide to adjust the pH to 9.0, stirs for 30 minutes, enters the sedimentation tank for sedimentation, the sedimented calcium oxalate is separated by a plate and frame filter press for solid-liquid separation. The obtained solid wet weight of calcium oxalate is 0.48t / h, the calcium oxalate enters the acid bath, and 0.7m sulfuric acid with a mass fraction of 30% is added. 3 / h, heated to 80℃, fully stirred for 30min, solid-liquid separation is carried out through a plate and frame filter press, the separated liquid enters the cooling crystallization tank and the temperature is reduced to 5℃, until no more crystals precipitate, the precipitated oxalic acid crystals undergo solid-liquid separation , And conduct low-temperature drying treatme...

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Abstract

The invention relates to the field of recycle treatment of rare earth wet-method smelting waste water, and especially relates to a process of recycling oxalic acid from rare earth wet-method smelting oxalic acid precipitation waste water. The process disclosed in the invention comprises following steps: adding alkaline calcium ion to the rare earth oxalic acid precipitation waste water, performing solid-liquid separation to collect the solid calcium oxalate, adding dilute sulfuric acid to the solid calcium oxalate, performing solid-liquid separation to obtain a liquid, decreasing the liquid to 0-15 DEG C and performing crystallization to obtain high-purity oxalic acid. The method can effectively recycle the oxalic acid from the rare earth wet-method smelting oxalic acid precipitation waste water with the recycle rate being not less than 50% and the purity of the recycled oxalic acid being not less than 95%. Meanwhile, the method is free of products such as ion exchange resin and the like and is also free of a complex column chromatographic process, so that the method is low in treatment cost, is simple and reliable and is suitable for industrial popularization.

Description

Technical field [0001] The invention relates to the field of rare earth hydrometallurgical wastewater treatment and resource management, in particular to a process for recovering oxalic acid from rare earth hydrometallurgical straw sedimentation wastewater. Background technique [0002] Rare earth hydrometallurgy has the characteristics of large amount of waste water, serious pollution and difficult treatment. The production process of hydrometallurgy of rare earth mainly includes dissolution, extraction, back extraction and precipitation. The precipitation process uses oxalic acid to precipitate the back extracted rare earth chloride. The chemical reaction formula is as follows: 2RECl 3 + 3 H 2 C 2 O 4 →RE 2 (C2O 4 ) 3 + 6HCl. [0003] The precipitation process produces a large amount of sedimentation mother liquor and washing and sedimentation wastewater. This type of wastewater is collectively referred to as rare earth straw sedimentation wastewater. Its main components are a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/487C07C55/06
CPCC07C51/487
Inventor 韩正昌王志磊马军军高亚娟张亮凌玲
Owner NANJING GW ENVIRONMENT ENG
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