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Method for rapidly recycling chrome from chroming waste liquor by alkali precipitation

A technology of waste liquid and chrome tanning, which is applied in chemical instruments and methods, flocculation/sedimentation water/sewage treatment, chromium oxide/hydrate, etc. It can solve the problems of high equipment investment, slow sedimentation, and high labor intensity, and achieve hydrophobicity Good durability, convenient recycling, and good leather quality

Inactive Publication Date: 2009-04-15
WENZHOU UNIVERSITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method requires the use of plate and frame filter press, which requires high equipment investment and high labor intensity.
In addition, due to this method, the precipitated particles of chromium hydroxide are very small, which belong to flocculent colloidal precipitates, and the sedimentation is very slow, with poor hydrophobicity and strong adhesion ability. Washing is easy to cause secondary pollution
And there is the problem of unstable quality of recovered chrome tanning liquor

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0018] A method for rapid precipitation and recovery of chromium from chrome tanning waste liquor, comprising the following steps, wherein the raw materials used are by weight:

[0019] (1) Removal of solid impurities: After the chrome tanning waste liquid is collected, it first enters the grid pool to remove solid impurities. It is required that the mesh of the coarse filter is 1cm, and the mesh of the fine filter is 1mm;

[0020] (2) Alkalinization treatment: Put the waste chromium liquid into the alkalization device, use steam to heat the waste liquid to 30°C, add 2.0 kg of alkaline substances such as magnesium oxide per cubic meter of waste liquid, and fully stir and alkalize for 120 minutes;

[0021] (3) Rapid precipitation: the waste chromium liquid is mixed with a small amount of polyacrylamide and other flocculants through a pipeline mixer, and enters the sedimentation tank, and the sediment settles rapidly within 20 minutes, and the sedimentation volume is less than 15...

Embodiment 2

[0024] A method for rapid precipitation and recovery of chromium from chrome tanning waste liquor, comprising the following steps, wherein the raw materials used are by weight:

[0025] (1) Removal of solid impurities: After the chrome tanning waste liquid is collected, it first enters the grid pool to remove solid impurities. It is required that the mesh of the coarse filter is 1cm, and the mesh of the fine filter is 1mm;

[0026] (2) Alkalinization treatment: Put the waste chromium liquid into the alkalization device, use steam to heat the waste liquid to 35°C, add 1.8 kg of alkaline substances such as magnesium oxide per cubic meter of waste liquid, and fully stir and alkalize for 90 minutes;

[0027] (3) Rapid precipitation: the waste chromium liquid is mixed with a small amount of polyacrylamide and other flocculants through a pipeline mixer, and enters the sedimentation tank, and the sediment settles rapidly within 20 minutes, and the sedimentation volume is less than 15%...

Embodiment 3

[0030] A method for rapid precipitation and recovery of chromium from chrome tanning waste liquor, comprising the following steps, wherein the raw materials used are by weight:

[0031] (1) Removal of solid impurities: After the chrome tanning waste liquid is collected, it first enters the grid pool to remove solid impurities. It is required that the mesh of the coarse filter is 1cm, and the mesh of the fine filter is 1mm;

[0032] (2) Alkalinization treatment: Put the waste chromium liquid into the alkalization device, use steam to heat the waste liquid to 40°C, add 1.5 kg of alkaline substances such as magnesium oxide per cubic meter of waste liquid, and fully stir and alkalize for 60 minutes;

[0033] (3) Rapid precipitation: the waste chromium liquid is mixed with a small amount of polyacrylamide and other flocculants through a pipeline mixer, and enters the sedimentation tank, and the sediment settles rapidly within 20 minutes, and the sedimentation volume is less than 15%...

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PUM

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Abstract

The invention discloses a method for recovering chrome by the fast alkali precipitation of chrome tannage waste fluid, belonging to the clean production technology and recycling technology in the technical field of leather production. After the collection of chrome tannage waste fluid in the invention, the solid impurities are removed by filtering, with the temperature adjusted, magnesium oxide or other alkali matters are added; and after the full stirring and alkalization, little polyacrylamide or other flocculants are added for fast precipitation to remove supernatant liquor; and chromic hydroxide precipitate is obtained after further removing the water of the underlayer flocculent precipitate with a centrifuger. With the adoption of the method, the concentration of dichromium trioxide in the waste fluid can reduce to below 0.05g / l from 2-4g / l, the removal rate reaches over 97 percent, and the addition of the flocculants can realize the fast precipitation of chromic hydroxide in 20 minutes, the precipitation volume is lower than 15 percent of the total volume, and the precipitate has good hydrophobic nature and can be recovered conveniently. The method provides a new way for the precipitation and recycling of waste chrome liquor in a tanyard.

Description

technical field [0001] The invention belongs to the clean production technology and recycling technology in the technical field of leather production, and in particular relates to a method for rapidly precipitating and recovering chromium from chrome tanning waste liquid. Background technique [0002] Chrome tanning, which has a history of more than 100 years, has been the mainstream technology of leather tanning because it can impart excellent performance to leather, and it is almost unshakable. In the actual tanning process, the utilization rate of the chrome tanning agent is only about 70%, and the remaining 30% of the chrome tanning agent is not utilized and enters the waste water. However, chrome tanning wastewater is a kind of wastewater that is difficult to treat in the leather industry, and the content of chromium trioxide is as high as 1-5g / l. If this high-concentration chromium-containing wastewater is discharged directly, it will not only pollute the water body, b...

Claims

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Application Information

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IPC IPC(8): C02F9/04C02F1/52C01G37/02C02F103/24
Inventor 周建飞兰云军许晓红程天行刘建国
Owner WENZHOU UNIVERSITY
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