Waste PCB Carbonization with Calcium Compound
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Solution Overview
Problem
Current methods for treating waste printed circuit boards fail to effectively remove halogens and combustibles without generating harmful gases, leading to environmental pollution and interfering with copper refining processes due to the presence of metals like aluminum and stainless steel.
Innovation Solution
A method involving carbonization of waste printed circuit boards with a calcium compound at 400° C. to 600° C. in a non-oxidizing atmosphere to fix halogens as calcium halides, allowing for easy separation of mounted parts, followed by sieving and physical sorting to recover metals, which are then reused or used as copper feed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If waste printed circuit board is heated in an oxidizing atmosphere, then combustibles are removed, but harmful dioxin is generated and halogen-containing gas corrodes device materials
Solution Approach 1:
The patent applies inert atmosphere by conducting carbonization in a non-oxidizing atmosphere (nitrogen or vacuum environment). This prevents the formation of dioxin and reduces halogen gas generation while still enabling effective removal of combustibles from the waste printed circuit board through thermal decomposition without oxidation.
2Object-generated harmful factors
If waste printed circuit board is carbonized at high temperature to remove halogens, then halogen gas generation is reduced, but aluminum mounted parts melt and sorting becomes difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the carbonization temperature range between 400-600°C. This temperature optimization achieves effective halogen fixation through calcium compound reaction while staying below aluminum's melting point (660°C), thus preventing mounted parts from melting and maintaining their structural integrity for subsequent sorting operations.
3Object-generated harmful factors
If conventional carbonization is performed without calcium compound, then halogen gas is generated, but effective halogen removal and environmental protection are achieved by adding calcium compound
Solution Approach 1:
The patent applies the blessing in disguise principle by converting harmful halogen gas into beneficial calcium halide solid through reaction with calcium compound. The halogen that would otherwise be released as harmful gas is transformed into a stable, non-volatile solid compound that can be easily removed and disposed of, achieving effective halogen removal and environmental protection.
4Ease of operation
If mounted parts are separated before carbonization, then sorting is easier, but metal portions are scraped together with board portion during crushing
Solution Approach 1:
The patent applies preliminary action by performing carbonization before crushing and sorting. The carbonization process creates a brittle carbonized layer on the board that facilitates clean separation during subsequent crushing, while mounted parts remain intact and can be effectively sorted by density and size differences, achieving both ease of operation and high separation quality.
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
Significantly reduces halogen gas generation, prevents dioxin formation, and enhances metal recovery rates by allowing for efficient separation and reuse of calcium compounds, thereby minimizing environmental impact and optimizing copper refining inputs.
Implementation Method 1
carbonizing waste printed circuit board together with a calcium compound at 400° C. to 600° C. in a non-oxidizing atmosphere to fix a halogen contained in the board as calcium halide
Implementation Method 2
carbonizing waste printed circuit board together with a calcium compound at 400° C. to 600° C. in a non-oxidizing atmosphere
Implementation Method 3
melt a solder of the board to allow mounted parts to be easily separated from the board
Data Source
AI summary
A method for treating waste printed circuit board includes carbonizing waste printed circuit board together with a calcium compound at 400° C. to 600° C. in a non-oxidizing atmosphere to fix a halogen contained in the board as calcium halide and to melt a solder of the board to allow mounted parts to be easily separated from the board, performing crushing after the carbonizing, and sieving crushed materials into fine particles of less than 0.5 mm containing the calcium compounds, medium particles containing the mounted parts, and coarse particles containing board pieces such that the crushed materials are sorted into the calcium compounds, the mounted parts, and the board pieces.