Method for recycling nitric acid and copper from waste water generated in production of printed circuit board

Abstract

The invention discloses a method for recycling nitric acid and copper from waste water generated in production of a printed circuit board. The method comprises the following steps that: (1) waste water generated in production of the printed circuit board and water flow through an inner cavity of an anion-exchange membrane diffusion dialysis apparatus at the same time, the flow speed of the waste water and the water is controlled, so that the waste water flowing out of the anion-exchange membrane diffusion dialysis apparatus is turned into raffinate with 0.05-0.2mol/L of nitric acid, the water flowing out of the anion-exchange membrane diffusion dialysis apparatus is turned into recycled liquid with a large quantity of nitric acid and little copper ions, and the recycled liquid returns back to a step of copper peeling in the production of the printed circuit board to be recycled; and (2) the raffinate is guided into an electrolytic cell for electrolysis, so that the copper in waste water is recycled. According to the method, the nitric acid is recycled, and the electrolysis recovery efficiency of copper is improved; and the discharged waste water contaminating the environment is reduced, the resource is recycled and the energy consumption is also lowered.

Description

technical field [0001] The invention relates to a method for recovering nitric acid and copper from printed circuit board production wastewater. Background technique [0002] Printed circuit board (PCB) produces a large amount of wastewater containing copper and nitric acid in the production process. The direct discharge of wastewater will seriously pollute the environment, and the high concentration of copper and nitric acid in wastewater has high recycling value. [0003] At present, the treatment methods for such wastewater mainly include chemical precipitation, electrolysis, solvent extraction, adsorption, organic flocculation, ion exchange, and biological treatment. Judging from the current application situation, the chemical sedimentation method and electrolysis method with relatively low cost and relatively mature technology are the main methods for wastewater treatment. When the chemical sedimentation method is used to treat wastewater, a large amount of copper-cont...

AI Technical Summary

Problems solved by technology

[0005] The first method requires the initial concentration of copper nitrate electrolyte to be 120g / L, and the concentration of supplementary solution to be 210g / L. The process flow and equipment operation are relatively complicated, and the copper content in copper nitrate wastewater in the PCB industry is generally 80~100g. In the range of / L, if this method is to be used for treatment, it is necessary to concentrate the copper nitrate wastewater, resulting in increased energy consumption and increased operating costs.

[0006] The second method adopts the method of directly passing nitric acid and waste water into the electrolytic cell for electrolysis, and the operation is relatively simple, but it has lower requirements for the initial concentration of nitric acid in the copper nitrate electrolyte, which is less than 0.1mol / L, while PCB The content of nitric acid in copper nitrate wastewater in the industry is about 4.5mol / L. If it is directly fed into the electrolytic cell for electrolysis, the high acid concentration will cause corrosion of the electrode and decrease the current efficiency.