Silver Recovery from Waste IC Chips via Soluble Starch Hydrothermal Separation
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Solution Overview
Problem
Current silver recycling methods from waste IC chips face issues such as incomplete metal separation, high energy consumption, poor adaptability to fluctuating waste compositions, and environmental concerns, particularly in pyrometallurgical and wet processes, while biological treatments face challenges in industrialization due to stringent environmental requirements.
Innovation Solution
A directional stepwise recycling method involving pre-treatment of IC chips, metal leaching with nitric acid, selective separation of iron and silver using soluble starch in hydrothermal reactions, and recycling of copper, which allows for efficient separation and purification of precious metals with minimal waste and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If pyrometallurgical process is used to recycle silver from waste IC chips, then metal separation can be achieved, but energy consumption is high and metal separation is incomplete
Solution Approach 1:
The patent changes the chemical parameters of the leaching solution by using nitric acid instead of traditional strong acids, and controls the hydrothermal reaction temperature (130-175°C for iron removal, 160-230°C for silver recovery) to achieve complete metal separation with significantly reduced energy consumption compared to pyrometallurgical processes
Solution Approach 2:
The patent introduces soluble starch as an intermediary substance that selectively reacts with iron ions to form precipitates, enabling selective iron removal without affecting silver recovery. This intermediary approach allows for complete separation of different metals while maintaining low energy consumption
2Ease of operation
If wet process is used to leach valuable metals, then process flow is simple and operation is convenient, but adaptability to fluctuation in waste composition is poor and recycling rate of precious metals is low
Solution Approach 1:
The patent implements a dynamic two-stage hydrothermal reaction process where the first stage (130-175°C) selectively removes iron and the second stage (160-230°C) recovers silver. This dynamic approach with adjustable temperature parameters enables the process to adapt to fluctuations in waste IC chip composition while maintaining simple operation and high precious metal recycling rates
3Object-generated harmful factors
If wet process is used for metal leaching, then low waste discharge is achieved, but large amounts of acidic and alkaline waste liquid are generated
Solution Approach 1:
The patent converts the potentially harmful nitric acid leaching process into a beneficial one by using the nitric acid solution as the leaching agent that dissolves metals, then using hydrothermal reactions to precipitate and recover the metals. This approach generates minimal waste liquid and eliminates the need for additional alkaline neutralization steps, transforming a potentially harmful process into an environmentally friendly one
4Object-affected harmful factors
If biological treatment process is used to leach metals, then process flow is short and environmental friendliness is improved, but industrial application is difficult due to strict environmental requirements
Solution Approach 1:
The patent replaces complex living biological systems with simple, inexpensive, and easily disposable chemical reagents (nitric acid and soluble starch). These chemical agents can be easily handled, stored, and disposed of, making the process environmentally friendly while simultaneously enabling straightforward industrial application without the stringent environmental controls required for biological treatments
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 method achieves high silver recycling rates with up to 98% purity and selective separation of metals, reducing waste and energy usage, making it a more resource-efficient and eco-friendly process compared to conventional methods.
Implementation Method 1
adding the powders to a nitric acid solution, heating, centrifuging and collecting a first filtrate; where, the operation transferring target components from a solid phase to a liquid phase is conducive to the recycling of heavy metal
Implementation Method 2
adding soluble starch to the first filtrate obtained in 2), where a mass concentration ratio of the soluble starch to Fe in the first filtrate is 5.20-7.30; heating a resulting mixture to 130-175° C. for a first hydrothermal reaction, separating a precipitate (a by-product of hematite) from the first hydrothermal reaction
Implementation Method 3
heating the second filtrate to 160-230° C. for a second hydrothermal reaction, separating a solid from the second hydrothermal reaction
Implementation Method 4
heating, centrifuging and collecting a first filtrate
Data Source
AI summary
A method for recycling silver from a waste IC chip include: heating to disassemble an IC chip, and crushing the IC chip into powders; adding the powders to a nitric acid solution, heating, centrifuging and collecting a first filtrate; adding soluble starch to the first filtrate, where a mass concentration ratio of the soluble starch to Fe in the first filtrate is 5.20-7.30; heating a resulting mixture to 130-175° C. for a first hydrothermal reaction, separating a precipitate from the first hydrothermal reaction and collecting a second filtrate; heating the second filtrate to 160-230° C. for a second hydrothermal reaction, separating a solid from the second hydrothermal reaction and collecting a third filtrate; drying, grinding, and sieving the solid to obtain silver powders; and adding alkali to the third filtrate to form a precipitate of Cu, and separating the precipitate to yield copper hydroxide.