Comprehensive processing utilizing method for chromium-containing waste acid

A comprehensive treatment, chromium waste technology, applied in filtration treatment, water/sewage treatment, chemical instruments and methods, etc., can solve the problems of cumbersome operation, high cost of filter cake reprocessing, and more sediments, etc., to improve economic value, The effect of reducing waste and reducing disposal costs

Active Publication Date: 2019-04-16
CHANGZHOU WUJIN YOUBANG WATER PURIFICATION MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The existing method for removing chromium from waste acid is mainly to neutralize with alkali (caustic soda or lime), press filter after precipitation of iron and chromium, and incinerate hazardous waste filter cake. The disadvantage of this method is that a large amount of lime is required for neutralization And caustic soda, more precipitates are formed, the cost of filter cake reprocessing is higher, and effective components are not well utilized
Another way to remove chromium in waste acid is to directly incinerate and dispose of it. Direct incineration will cause a lot of waste of resources and energy. The treatment cost is too high, which is not conducive to the actual hazardous waste treatment, and it is easy to cause secondary secondary hazardous waste
In the prior art, there is also a method for disclosing related precipitation. The prior art CN106865729A discloses a method for treating chromium-containing heavy metal wastewater by using molten iron to pretreat desulfurization slag. , use magnetic substances to reduce hexavalent chromium to trivalent chromium, and then use iron tailings to remove the reduced trivalent chromium by chemical precipitation. The operation of this method is cumbersome and not suitable for actual production and treatment

Method used

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  • Comprehensive processing utilizing method for chromium-containing waste acid
  • Comprehensive processing utilizing method for chromium-containing waste acid
  • Comprehensive processing utilizing method for chromium-containing waste acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] A comprehensive treatment and utilization method for chromium-containing waste acid, such as figure 1 shown, including the following steps:

[0033] S1. Adjust the pH value of the chromium-containing waste acid to 1.5, add acid to cause precipitation reaction with iron ions, add acid and then stir for 20 minutes, filter and separate to obtain ferrous precipitate and filtrate, maintain the pH value of the system at 1.5 during the acid addition process, the acid The addition amount is 1.1 times of iron ion in waste acid, and acid is the mixed acid of citric acid, oxalic acid, acetic acid and EDTA, and wherein the mass ratio of citric acid, oxalic acid, acetic acid and EDTA is 5:2:1:1;

[0034] S2. The above separated filtrate is cooled and precipitated to crystallize, filtered twice, and the filter cake is dried in the shade to obtain crystalline sodium sulfate Na 2 SO 4 .10H 2 O and secondary filtrate;

[0035] S3. The above-mentioned secondary filtrate is evaporated...

Embodiment 2

[0037] A method for comprehensive treatment and utilization of chromium-containing waste acid, comprising the following steps:

[0038] S1. Adjust the pH value of chromium-containing waste acid to 1, add acid to cause precipitation reaction with iron ions, add acid and then stir for 20 minutes, filter and separate to obtain ferrous precipitate and filtrate, maintain the system pH value at 1 during the acid addition process, acid The addition amount of the acid is 1.1 times of the iron ion in the waste acid, and the addition speed of the acid is controlled so that the pH value of the system after the addition is ≥0.5, and the acid is a mixed acid of citric acid, oxalic acid, acetic acid and EDTA, wherein citric acid, oxalic acid, acetic acid and EDTA The amount ratio of substances is 4.5:2:1:1;

[0039] S2. The above separated filtrate is cooled and precipitated to crystallize, filtered twice, and the filter cake is dried in the shade to obtain crystalline sodium sulfate Na 2 ...

Embodiment 3

[0042] A method for comprehensive treatment and utilization of chromium-containing waste acid, comprising the following steps:

[0043] S1. Adjust the pH value of the chromium-containing waste acid to 3, add acid to cause precipitation reaction with iron ions, add acid and then stir for 20 minutes, filter and separate to obtain ferrous precipitate and filtrate, maintain the pH value of the system at 3 during the acid addition process, acid The addition amount of the acid is 1.1 times of the iron ion in the waste acid, and the addition speed of the acid is controlled so that the pH value of the system after the addition is ≥0.5, and the acid is a mixed acid of citric acid, oxalic acid, acetic acid and EDTA, wherein citric acid, oxalic acid, acetic acid and EDTA The molar ratio of substances is 5:2.5:1:1;

[0044] S2. The above separated filtrate is cooled and precipitated to crystallize, filtered twice, and the filter cake is dried in the shade to obtain crystalline sodium sulf...

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PUM

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Abstract

The invention discloses a comprehensive processing utilizing method for chromium-containing waste acid. Waste acid processed through the method contains sulfate radicals and iron ions. The method comprises the following steps that the pH value of the chromium-containing waste acid is regulated to 1-3, acid is added to be subjected to a settling reaction with the iron ions, ferrous sediments and afiltrate are obtained through separation, and in the acid adding process, the pH value of the system is maintained to be 1-3; the filtrate is separated, cooling sedimentation and crystallization are performed, and crystal sodium sulfate and a secondary filtrate are obtained through filtering; the secondary filtrate is evaporated and condensed to obtain chromium sulfate. According to the processingmethod, acid, iron and chromium grading recycling is achieved through step-by-step grading processing, the problem that according to an existing processing method, after sedimentation preliminary chromium, secondary danger and waste caused by incineration are generated, and the resource recycling value is not high are avoided, the chromium-containing waste acid is comprehensively recycled, the iron recycling rate can reach up to 95.0%, the acid recycling rate can reach up to 80.0%, the chromium recycling rate can reach up to 90.5%, and the method can be widely applied to chromium-containing waste acid recycling.

Description

technical field [0001] The invention relates to the technical field of cold rolling or electroplating, and more specifically relates to a method for comprehensive treatment and utilization of chromium-containing waste acid. Background technique [0002] In the cold rolling industry and other pickling industries, a large amount of stainless steel needs to be pickled. The steel contains different amounts of chromium and enters the pickling waste liquid after pickling. If these waste acids are to be comprehensively utilized, the chromium in them must be Chromium is separated, otherwise it will seriously affect the subsequent use. The existing method for removing chromium from waste acid is mainly to neutralize with alkali (caustic soda or lime), press filter after precipitation of iron and chromium, and incinerate hazardous waste filter cake. The disadvantage of this method is that a large amount of lime is required for neutralization And caustic soda, more precipitates are fo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01G37/08C02F9/10C21B15/00C01D5/00
CPCC01D5/00C01G37/08C01P2006/80C02F1/001C02F1/04C02F1/5236C02F9/00C21B15/00
Inventor 刘巍斌居银栋孙戎斐
Owner CHANGZHOU WUJIN YOUBANG WATER PURIFICATION MATERIALS
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