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Method for recovering ferric oxide from red mud by leaching-photocatalysis by oxalic acid

An iron oxide and red mud technology, applied in chemical instruments and methods, organic chemistry, cement production, etc., can solve the problems of red mud stacking pollution and alkalinity reduction.

Inactive Publication Date: 2012-09-19
BEIJING UNIV OF CHEM TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the current problem of red mud stacking pollution in the alumina industry, and to provide a method of using oxalic acid solution to treat red mud to reduce the alkalinity and recover iron oxide, so that the treated red mud can be used as raw materials for making refractory bricks, cement, etc.

Method used

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  • Method for recovering ferric oxide from red mud by leaching-photocatalysis by oxalic acid
  • Method for recovering ferric oxide from red mud by leaching-photocatalysis by oxalic acid
  • Method for recovering ferric oxide from red mud by leaching-photocatalysis by oxalic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] Take 10g of air-dried red mud and add it to 100ml of 1mol / L oxalic acid solution, carry out stirring and leaching at 60°C for 2h, and then filter. The chemical analysis of red mud and filter residue was carried out respectively, and the results are shown in Table 1.

[0024] Table 1 Chemical analysis results before and after treatment of red mud with oxalic acid solution

[0025]

[0026] The iron oxide content in the treated red mud is only 0.6%, which is suitable for use as raw materials for refractory bricks and cement. The oxalate concentration in the leach solution is 0.95mol / L, and the iron content is 9.8g / L (as Fe 2 o 3 count). Put the leaching solution under ultraviolet light irradiation, and stir it properly, a large amount of light yellow precipitate will appear in 0.5h, and the amount of precipitation will not continue to increase after 2h. Stop the irradiation. In the filtrate after separating ferrous oxalate precipitation, oxalate content is 0.65mol / ...

Embodiment 2

[0028] Take 15g of dry red mud and add it to 180ml of 0.8mol / L oxalic acid solution, carry out stirring and leaching at 70°C for 1h, and conduct chemical analysis on red mud and filter residue respectively, the results are shown in Table 2.

[0029] Table 2 Chemical analysis results before and after red mud treatment with oxalic acid solution

[0030]

[0031] The content of iron oxide in the treated red mud is 0.56%, which is suitable for use as raw materials for refractory bricks, cement and the like. The oxalate concentration in the leach solution is 0.72mol / L, and the iron content is 7.7g / L (as Fe 2 o 3 count). Put the leaching solution under ultraviolet light irradiation, and stir it properly, a large amount of light yellow precipitate will appear in 0.5h, and the amount of precipitation will not continue to increase after 3h. Stop the irradiation. Separating the oxalate content in the filtrate after ferrous oxalate precipitation is 0.46mol / L, and iron content is 0....

Embodiment 3

[0033] Take 10g of dry red mud and add it to 200ml of 0.5mol / L oxalic acid solution, carry out stirring and leaching at 80°C for 2h, and then filter. The chemical analysis of red mud and filter residue was carried out respectively, and the results are shown in Table 3.

[0034] Table 3 Chemical analysis results before and after red mud treatment with oxalic acid solution

[0035]

[0036] The iron oxide content in the treated red mud is 0.71%, which is suitable for use as raw materials for refractory bricks and cement. The oxalate concentration in the leach solution is 0.47mol / L, and the iron content is 4.3g / L (as Fe 2 o 3count). At 12:00 noon, put the leach solution under sunlight and stir it properly. A large amount of light yellow precipitates appeared in 0.5 hours, and the amount of precipitates did not continue to increase after 2 hours. Separating the oxalate content in the filtrate after ferrous oxalate precipitation is 0.3mol / L, and iron content is 0.34g / L (as F...

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Abstract

A method for treating red mud by utilizing oxalic acid solution comprises the steps of taking 0.5-1mol / L oxalic acid solution as a leaching agent, mixing air-dried red mud with the oxalic acid solution according to a proportion of 80-120g / L, stirring at 60-90 DEG C for 0.5-4h, and conducting solid-liquid separation to obtain the treated red mud and ferrum-containing oxalic acid solution. The ferric oxide content in the treated red mud is smaller than 1 percent, so that the red mud is applicable to manufacturing of refractory bricks, cement and the like. The ferrum-containing oxalic acid solution is subjected to photochemical reaction under irradiation of ultraviolet light or sunshine, thus being capable of forming ferrous oxalate sedimentation with better crystal. Ferric oxide content of filtrate after being separated from ferrous oxalate sedimentation is smaller than 1g / L, and the filtrate solution is continuously used for treating the red mud as supplement liquid of the leaching agent after being added with proper oxalic acid or being directly used.

Description

technical field [0001] The invention belongs to a method for recycling red mud which is a waste produced by alumina, in particular using oxalic acid solution to leach iron oxide in the red mud, and using photocatalytic reaction to transform it into ferrous oxalate precipitate for recycling. technical background [0002] Red mud is a solid waste from the alumina production industry. It is called red mud because of its high iron oxide content and red color. In 2009, the world's alumina output was as high as 50 million tons, and the discharge of red mud was as high as 60 million tons. The treatment and storage of red mud has become a worldwide problem. Since the red mud is the residue filtered from the high-concentration sodium hydroxide leaching solution, it is still alkaline even after washing with a lot of water. This strong alkalinity not only damages cultivated land, but also seriously pollutes water sources when it seeps into the ground or enters surface water. Therefor...

Claims

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Application Information

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IPC IPC(8): C02F11/00C07C55/07C07C51/41C04B7/147
CPCY02P40/10
Inventor 万平玉余章龙陈咏梅钮因健顾青松
Owner BEIJING UNIV OF CHEM TECH
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