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Method for reclaiming waste sulfuric acid in hard anode oxidation process

A technology of hard anodic oxidation and waste sulfuric acid, which is applied in the direction of sulfur trioxide/sulfuric acid, etc., can solve the problems of low value of hard anodic oxidation, loss of additives, high treatment cost, etc., and achieve high added value, low cost of equipment transformation, and treatment low cost effect

Active Publication Date: 2011-05-18
ZHEJIANG SUPOR CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Method 2: Use the high concentration of sodium hydroxide, sodium metaaluminate and waste sulfuric acid in the pre-treated alkali etching tank to neutralize and recrystallize to extract the aluminum sulfate. The hard anodizing industry is less valuable; mainly because hard anodizing often has expensive additives that are lost with processing and there is no caustic etch step in the hard anodizing process
Method 3: Heating and concentrating waste sulfuric acid, adding ammonium sulfate under high temperature conditions, cooling back to room temperature, filtering out the crystallized ammonium aluminum sulfate dodecahydrate, and then reusing sulfuric acid. This method requires a special treatment system, and the treatment Relatively high cost, not widely available in the hard anodizing industry

Method used

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  • Method for reclaiming waste sulfuric acid in hard anode oxidation process

Examples

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Effect test

Embodiment 1

[0036] Take 5 liters of sulfuric acid solution whose aluminum ions have exceeded the standard during the hard anodizing process from the workshop and move it from the hard anodizing tank to the spare tank at a temperature of -5 to 5°C through the cooling pipe. The conditions are as follows:

[0037] Sulfuric acid (H 2 SO 4 ): 150~250g / L

[0038] Aluminum ions (Al 3+ ) 2~15g / L

[0039] Temperature: -5~5℃

[0040] Current density: 2.0~4.0A / dm 2

[0041] Voltage: 0~100V

[0042] Time: 30~40min

[0043] Agitation: Intense agitation with compressed air.

[0044]The concentration of aluminum ions in it was determined to be 15.51g / l through assay. Use a 1-liter volumetric flask to sample 1 liter, weigh 37.9g ​​of ammonium sulfate by calculation and put it into a spare tank, stir to fully dissolve the ammonium sulfate, and then put it into a household freezer to maintain the temperature at -5 to 5°C. 5 hours. The supernatant of the...

Embodiment 2

[0046] Take 5 liters of sulfuric acid solution whose aluminum ions have exceeded the standard during the hard anodizing process from the workshop and move it from the hard anodizing tank to the spare tank at a temperature of -5 to 5°C through the cooling pipe. The conditions are as follows:

[0047] Sulfuric acid (H 2 SO 4 ): 150~250g / L

[0048] Aluminum ions (Al 3+ ) 2~15g / L

[0049] Temperature: -5~5℃

[0050] Current density: 2.0~4.0A / dm 2

[0051] Voltage: 0~100V

[0052] Time: 30~40min

[0053] Agitation: Intense agitation with compressed air.

[0054] The concentration of aluminum ions in it was determined to be 15.51g / l through assay. Use a 1-liter volumetric flask to sample 1 liter, weigh 25g of ammonium sulfate into the spare tank by calculation, stir to fully dissolve the ammonium sulfate, and then put it into a household freezer to maintain a temperature of -5 to 5°C at 0.5 to 5 Hour. The supernatant of the compl...

Embodiment 3

[0056] Take 5 liters of sulfuric acid solution whose aluminum ions have exceeded the standard during the hard anodizing process from the workshop and move it from the hard anodizing tank to the spare tank at a temperature of -5 to 5°C through the cooling pipe. The conditions are as follows:

[0057] Sulfuric acid (H 2 SO 4 ): 150~250g / L

[0058] Aluminum ions (Al 3+ ) 2~15g / L

[0059] Temperature: -5~5℃

[0060] Current density: 2.0~4.0A / dm 2

[0061] Voltage: 0~100V

[0062] Time: 30~40min

[0063] Agitation: Intense agitation with compressed air.

[0064] The concentration of aluminum ions in it was determined to be 15.51g / l through assay. Use a 1-liter volumetric flask to sample 1 liter, weigh 45g of ammonium sulfate by calculation and put it into a spare tank, stir to fully dissolve the ammonium sulfate, and then put it in a household freezer to maintain a temperature of -5 to 5°C at 0.5 to 5 Hour. The supernatant of th...

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Abstract

The invention provides a novel method for recycling waste sulfuric acid in the oxidation process of hard anode using ammonium sulfate at low temperature. The invention resolves the problems of complicated technical process, high cost and relatively bad feasibility, etc., existing in the present waste sulfuric acid recycling method in the oxidation process of hard anode. The novel method comprisesthe following steps: transferring waste sulfuric acid solution, that is to transfer the waste sulfuric acid solution with exceeding aluminum irons in the oxidation treatment process of hard anode from a hard anode oxidation tank to a standby tank with a temperature of -5 DEG C to 5 DEG C; reaction and precipitation, that is to weigh ammonium sulfate solid which is to be added into the standby tank for reacting with aluminum sulfate contained in the waste sulfuric acid at -5 DEG C to 5 DEG C for 0.5 to 5 hours, thus leading to full precipitation of reactant aluminum ammonium sulfate; transferring supernatant and removing precipitates. The invention has the advantages of low treatment cost, simplicity and convenience, relatively high added value of byproducts after treatment, strong feasibility and low modification cost of equipment, etc.

Description

technical field [0001] The invention relates to a method for recovering waste sulfuric acid in the process of anodic oxidation, in particular to a new method for recovering waste sulfuric acid in the process of hard anodic oxidation by using ammonium sulfate under low temperature conditions. Background technique [0002] Anodizing refers to the electrochemical process in which the workpiece hangs on the anode and undergoes a film-forming reaction in a specific electrolyte. Hard anodizing is a kind of anodizing, which makes the oxidized aluminum alloy have a high-thickness and high-hardness oxide film. It uses a sulfuric acid-based electrolyte (sometimes some organic polyacids and polyols are added to improve the performance of the oxide film). However, as the oxidation progresses, the aluminum ions in the sulfuric acid continue to increase due to the continuous dissolution of aluminum. When the aluminum ion reaches 15-20 g / L, the performance of the hard oxide film will oft...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B17/90
Inventor 徐存荣诸葛毅胡雪灵
Owner ZHEJIANG SUPOR CO LTD
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