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Recycling method of circuit board tin stripping wastewater

A technology for stripping tin waste water and circuit boards, applied in chemical instruments and methods, tin compounds, multi-stage treatment of water/sewage, etc. High processing efficiency and good processing effect

Inactive Publication Date: 2011-06-08
HUIZHOU DAYAWAN HUILU ENVIRONMENT PROTECTION SERVICE +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] The tin stripping wastewater produced by the printed circuit board industry is a kind of highly polluting industrial waste produced by removing the tin coating with nitric acid during the production process of the circuit board. Its composition is a mixture of nitric acid and β-stannic acid precipitation and colloid. If it is not treated as a resource, it will inevitably cause environmental pollution and waste of resources.
At present, most domestic manufacturers engaged in the treatment of tin-removing wastewater from circuit board factories are divided into sulfuric acid method and caustic soda method. Separation of tin from the medium, this method causes a large secondary pollution, and the resource utilization is not complete, and the tin can not be completely precipitated
The latter method is mainly to add caustic soda to alkalinize the solution so that the β-stannic acid colloid is precipitated to separate tin from the wastewater. This method will pay a higher cost in order to achieve better resource utilization and harmlessness. Disposal costs and thus limited economics

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] The tin stripping wastewater of a circuit board factory contains 2% tin and 3% nitric acid. The treatment process is as follows:

[0020] 1. Under the condition of full stirring, add the refined lime slurry to the tin stripping wastewater, control the pH value of the end point to be 4, and the stirring time is 2 hours.

[0021] 2. In the case of full stirring, add lime water, control the pH value of the end point to 9, and stir for 1 hour.

[0022] 3. Under the condition of full stirring, add tin stripping wastewater, control the pH value of the end point to be 6.5-7, and stir for 1 hour.

[0023] 4. Use a filter press for solid-liquid separation, and at the same time add clean water with a solid-liquid ratio of 1:1 to wash the solid phase in the filter press.

[0024] 5. Mix the liquid phase after solid-liquid separation and the washing liquid phase, evaporate and concentrate, crystallize calcium nitrate tetrahydrate, and obtain qualified products after recrystallizat...

Embodiment 2

[0027] The tin stripping wastewater from a circuit board factory contains 5% copper and 4% nitric acid. The treatment process is as follows:

[0028] 1. Under the condition of full stirring, add the refined lime slurry to the tin stripping wastewater, control the pH value of the end point to be 4.3, and the stirring time is 3 hours.

[0029] 2. In the case of full stirring, add lime water to control the pH value of the end point to 9.2, and stir for 1.5 hours.

[0030] 3. Under the condition of full stirring, add tin stripping wastewater, control the pH value of the end point to be 6.5-7, and stir for 1 hour.

[0031] 4. Use a filter press for solid-liquid separation, and at the same time add clean water with a solid-liquid ratio of 1:1 to wash the solid phase in the filter press.

[0032] 5. Mix the liquid phase after solid-liquid separation and the washing liquid phase, evaporate and concentrate, crystallize calcium nitrate tetrahydrate, and obtain qualified products after ...

Embodiment 3

[0035] The tin stripping wastewater from a circuit board factory contains 6% copper and 5% nitric acid. The treatment process is as follows:

[0036] 1. Under the condition of full stirring, add the refined lime slurry to the tin stripping wastewater, control the pH value of the end point to be 4.5, and the stirring time is 3.5 hours.

[0037] 2. In the case of full stirring, add lime water, control the pH value of the end point to 9.5, and stir for 2 hours.

[0038] 3. Under the condition of full stirring, add tin stripping wastewater, control the pH value of the end point to be 6.5-7, and stir for 1 hour.

[0039] 4. Use a filter press for solid-liquid separation, and at the same time add clean water with a solid-liquid ratio of 1:1 to wash the solid phase in the filter press.

[0040] 5. Mix the liquid phase after solid-liquid separation and the washing liquid phase, evaporate and concentrate, crystallize calcium nitrate tetrahydrate, and obtain qualified products after re...

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Abstract

The invention provides a recycling method of circuit board tin stripping wastewater and the method can be used in the resource treatment of the tin stripping wastewater of the circuit board factory, belonging to the technical field of environmental protection. The method has the following process flows: adding refined lime slurry in the tin stripping wastewater to adjust the pH value to be alkaline and ensure that a part of beta-stannic acid sol with positive charges is coagulated, another part of beta-stannic acid sol is converted to beta-stannic acid sol with negative charges, and adding the tin stripping wastewater to adjust the pH value to be neutral and ensure that the beta-stannic acid sol with negative charges performs charge neutralization with the beta-stannic acid sol particles with positive charges and is completely coagulated, performing solid-liquid separation, and rinsing to obtain solid beta-stannic acid precipitate which is used as the raw material of tin smelting to produce metal tin. The separated solution is mixed with the same rinse water and then the mixture is evaporated and concentrated to obtain a calcium nitrate tetrahydrate product. The recycling method is characterized by low treatment cost, simple treatment process, good treatment effect, high treatment efficiency, total recycling, zero emission and the like and is suitable for the resource treatment of the tin stripping wastewater of the circuit board factory.

Description

technical field [0001] The invention relates to a process for recycling tin stripping wastewater from circuit boards, which can be used for recycling tin stripping wastewater from circuit board factories, and belongs to the technical field of environmental protection. Background technique [0002] The tin stripping wastewater produced in the printed circuit board industry is a kind of industrial waste with large pollution produced by removing the tin plating layer with nitric acid in the production process of the circuit board. Its composition is a mixture of nitric acid and beta-stannic acid precipitation and colloid. If it is not treated as a resource, it will inevitably cause environmental pollution and waste of resources. At present, most domestic manufacturers engaged in the treatment of tin stripping wastewater from circuit board factories use two processes: sulfuric acid method and caustic soda method. The tin is separated from the tin, this method causes a large sec...

Claims

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Application Information

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IPC IPC(8): C02F9/10C01G19/00C01F11/38
Inventor 谢逢春
Owner HUIZHOU DAYAWAN HUILU ENVIRONMENT PROTECTION SERVICE
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