PCB Copper Chloride Etching Waste Recycling via Precipitation
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Solution Overview
Problem
Current methods for recycling PCB copper chloride etching waste solutions are inefficient, leading to environmental pollution, high energy consumption, and significant equipment investment costs. Existing methods struggle with the recycling of ammonium and ammonia-containing waste solutions, resulting in incomplete material recovery and safety concerns due to the production of nitrogen trichloride.
Innovation Solution
A method for recycling PCB copper chloride etching waste solutions through precipitation treatment, which involves mixing the waste solution with a pH adjusting agent to precipitate copper salts, followed by solid-liquid separation and ammonia nitrogen removal treatment. This process allows for the recovery of copper products and the reuse of the remaining liquid as a regenerated etching solution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If acidification method is used to recover copper from alkaline cupric chloride ammonia etching waste solution, then copper can be recovered through electrochemical reduction, but the remaining salt solution cannot be recycled due to large amount of ammonium sulfate
Solution Approach 1:
The patent changes the chemical parameters of the waste solution by controlling pH adjustment and adding specific reagents (sodium hydroxide, sodium carbonate, or ammonium carbonate) to precipitate copper as hydroxide or carbonate. This parameter change enables both copper recovery and makes the remaining solution recyclable by converting ammonium sulfate into recyclable ammonium hydroxide or carbonate solutions.
2Loss of substance
If extraction method is used with strong organic chelating agent, then copper ions can be extracted and production raw materials recycled, but large amount of free ammonia is produced and organic chelating agent impurities affect etching efficiency
Solution Approach 1:
The patent replaces expensive organic chelating agents with simple, inexpensive inorganic reagents (sodium hydroxide, sodium carbonate, or ammonium carbonate) for copper precipitation. These inexpensive reagents achieve copper recovery without producing harmful organic impurities or excessive ammonia gas, eliminating the need for complex extraction equipment and reducing operational costs.
3Loss of substance
If electrolysis method is used on alkaline cupric chloride ammonia etching waste solution, then copper can be obtained, but copper-ammonia complex is destroyed releasing free ammonia and nitrogen trichloride may be produced
Solution Approach 1:
The patent performs preliminary chemical precipitation of copper before any potential electrolysis or disposal. By adjusting pH and adding reagents to precipitate copper as hydroxide or carbonate, the copper is recovered in a stable, non-volatile form. This preliminary action prevents the formation of copper-ammonia complexes that would otherwise decompose during electrolysis to release harmful ammonia gas and potentially form explosive nitrogen trichloride.
4Loss of substance
If conventional recycling methods are used, then copper recovery is achieved, but equipment investment costs are significant and energy consumption is high
Solution Approach 1:
The patent replaces complex mechanical and electrochemical systems (extraction equipment, electrolysis cells, filtration systems) with simple chemical precipitation using inexpensive reagents. This substitution of complex mechanical/electrical systems with simple chemical reactions dramatically reduces equipment investment costs and energy consumption while achieving effective copper recovery.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed method achieves efficient copper recovery with low environmental pollution and minimal equipment investment. It enables 100% recycling of copper chloride etching waste solutions, improving production income while meeting environmental protection regulations.
Implementation Method 1
mixing the waste solution with a pH adjusting agent to precipitate copper salts
Implementation Method 2
followed by solid-liquid separation
Data Source
AI summary
The present disclosure discloses a method for recycling of PCB copper chloride etching waste solution through precipitation treatment and an apparatus applicable thereto, including mixing a PCB copper chloride etching waste solution with a pH value adjusting agent for reaction, so that copper salt precipitates in the solution, and at least one of the PCB copper chloride etching waste solution and the pH value adjusting agent contains a PCB copper chloride etching waste solution containing ammonium and/or ammonia; and, subjecting a solid-liquid mixture obtained in step (1) to SLS to obtain filtrate A and filter residue C; and carrying out ammonia nitrogen removal treatment on the filter residue C to generate recovered copper products; and finally, reusing all or part of the filtrate A directly or after composition adjustment to the PCB copper chloride etching system as a regenerated etching replenishment solution and/or an etching oxidant solution.