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Method for recovering iron sludge from stainless steel scraps recovered with chromium and nickel

A technology of stainless steel and iron recovery, which is applied in chemical instruments and methods, water/sludge/sewage treatment, metallurgical wastewater treatment, etc., can solve the problems of increasing treatment costs and wasting iron resources, achieving obvious economic effects and saving countless The effect of hazardous disposal fees

Inactive Publication Date: 2013-08-14
陈宇青
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

If these iron components are not recycled, the harmless treatment of the sludge in the next step will increase the treatment cost and waste iron resources

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] In a stainless steel production enterprise in Songyang, Zhejiang Province, the waste sludge after reclaiming chromium and nickel from stainless steel sludge was used in the embodiment of the present invention for application. The pH of a certain waste sludge was measured to be 2.4, and the solid content was 10%. Iron is about 7% (dry basis, the same below), and it also contains 0.7% chromium and 0.4% nickel.

[0021] First, the waste sludge with a solid content of 10% is adjusted to pH 1.8 by adding hydrochloric acid, and extracted for 90 minutes; %; and add polyacrylamide, add polyacrylamide to 13ppm, filter after standing; carry out harmless treatment on the filtered filter cake, then add alkali to the filtrate, and adjust the pH to 2.8, then add polyacrylamide 2ppm; the alkali added is milk of lime; the above mixed solution is filtered, and the filter cake obtained by filtering is iron sludge, which is iron fine powder after medium temperature reduction, which can be...

Embodiment 2

[0023] Using the same raw materials as in Example 1, that is, the pH of the leftovers is 2.4, the solid content is 10%, and the iron content is about 7% (dry basis, the same below), and it also contains 0.7% chromium and 0.4% nickel.

[0024] Firstly, the waste sludge with a solid content of 10% is adjusted to pH 1.8 by adding hydrochloric acid, and extracted for 90 minutes; %; and add polyacrylamide, add polyacrylamide to 15ppm, filter after standing; carry out harmless treatment on the filtered filter cake, then add alkali to the filtrate, and adjust the pH to 2.8, then add polyacrylamide 3ppm; the alkali added is lime milk; the above mixed solution is filtered, and the filter cake obtained by filtering is iron sludge, which is iron fine powder after medium temperature reduction, which can be recycled; the filtrate is returned to the wastewater adjustment tank for reprocessing.

[0025] In the above embodiment, iron resources can be effectively recovered; and the subsequent ...

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Abstract

The invention discloses a method for sludge treatment, and particularly relates to a method for recovering iron sludge from stainless steel scraps recovered with chromium and nickel. The method comprises the following steps: adding acid in the scrap with the solid content of 10 percent to adjust the pH value to 1.8 for lixiviation; adding a defluorinating dehydrating agent and polyacrylamide in the scrap, and then carrying out filtering after standing; performing harmless treatment to a filtered filter cake, adding a base in filtrate to adjust the pH value to 2.8, and then adding polyacrylamide; finally, filtering the mixed liquor, a filter cake obtained after the filtering is iron sludge, the iron sludge is reduced at the medium temperature to form powdered iron, and the powdered iron can be recycled; and the filtrate is transferred in the waste water equalization pond for retreatment. The method has the advantages that the recovery ratio of iron can be up to 88 percent, the content of powdered iron after reduction can be up to 61 percent to 68 percent, meanwhile, the sludge is reduced by 40 percent, and the corresponding harmless treatment cost is saved; and the recovery ratio of chromium and nickel is improved, and the obvious economic effect is achieved.

Description

technical field [0001] The invention relates to a sludge treatment method, in particular to a method for recovering iron sludge from stainless steel waste sludge from which chromium and nickel have been recovered. Background technique [0002] The treatment of existing stainless steel waste sludge basically adopts the methods of aeration, neutralization, and sedimentation. Since the traditional method does not consider the recovery of heavy metals in wastewater, but only considers the treatment of up-to-standard discharge, the overall operating cost is too high, and the dried sludge Often due to improper disposal, it is easy to cause secondary pollution of heavy metals, and more importantly, it will cause waste of resources. A large amount of iron, chromium and nickel salts are contained in stainless steel acid wastewater. At present, enterprises generally treat acid wastewater to meet the discharge standards, and then discharge it. However, such discharge still has a lot o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C02F9/04C02F103/16
Inventor 陈启松周才用叶根基陈宇青于晨
Owner 陈宇青