Low-Alpha Tin Purification by Lead Sulfate Precipitation
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Solution Overview
Problem
Current methods for producing tin with low α-ray emission struggle to maintain the emission at 0.002 cph/cm² or less, especially when exposed to high-temperature environments, and are inefficient due to the need for thermal fusion and limited Pb impurity reduction.
Innovation Solution
A liquid phase method involving dissolving tin and lead in a sulfuric acid solution, followed by filtration and electrowinning, using a lead nitrate solution to precipitate lead sulfate and reduce 210Pb concentration, ensuring the α-ray emission remains low even after heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermal fusion method is used to produce tin with low α-ray emission, then Pb impurity can be removed, but the process is inefficient and cannot maintain emission at 0.002 cph/cm² or less after high-temperature exposure
Solution Approach 1:
The patent changes the fundamental parameter of the purification approach from thermal fusion to liquid-phase electrochemical method. By dissolving tin in sulfuric acid to form tin sulfate solution and using electrowinning, the process achieves both high efficiency and reliable low α-ray emission stability after heating, eliminating the contradiction between productivity and reliability.
Solution Approach 2:
The patent replaces the thermal fusion mechanical/thermal process with an electrochemical system. Instead of using high-temperature fusion and evaporation, the invention uses electrochemical dissolution and electrowinning in liquid phase, substituting thermal mechanics with electrochemical reactions to achieve better control over Pb removal and emission stability.
2Reliability
If conventional purification methods are used, then some Pb can be removed, but the α-ray emission cannot be maintained at 0.002 cph/cm² or less after heating
Solution Approach 1:
The patent changes the chemical environment parameter from solid-state thermal processing to liquid-phase electrochemical processing. By using sulfuric acid solution and controlling electrowinning parameters, the process achieves reliable α-ray emission maintenance while the added liquid-phase steps are offset by eliminating complex thermal fusion equipment and procedures.
Solution Approach 2:
The patent introduces sulfuric acid solution as an intermediary medium to facilitate Pb removal. The acid dissolves tin to form tin sulfate, allowing Pb to be selectively removed during electrawinning, and the solution acts as a mediator that enables controlled purification without direct high-temperature thermal contact.
3Reliability
If more Pb is removed to maintain lower α-ray emission, then emission level improves, but production cost and process complexity increase
Solution Approach 1:
The patent changes the purification mechanism from thermal evaporation to electrochemical separation, allowing for more effective and selective Pb removal. The electrowinning process enables greater Pb elimination efficiency through controlled electrodeposition, achieving lower α-ray emission levels while the liquid-phase process remains simpler than thermal fusion infrastructure.
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 effectively maintains α-ray emission at 0.002 cph/cm² or less, both initially and after heating, and can handle high Pb concentrations, providing a more efficient and reliable production process compared to existing thermal fusion methods.
Implementation Method 1
a liquid phase method involving dissolving tin and lead in a sulfuric acid solution, followed by filtration and electrowinning, using a lead nitrate solution to precipitate lead sulfate
Implementation Method 2
followed by filtration and electrawinning
Data Source
AI summary
Any metal having a low α-ray emission, the metal being any one of tin, silver, copper, zinc, or indium, wherein an emission of an α-ray after heating the metal at 100° C. in an atmosphere for six hours is 0.002 cph/cm2 or less. Any metal of tin, silver, copper, zinc and indium each including lead as an impurity is dissolved to prepare a hydrosulfate aqueous solution of the metal and lead sulfate is precipitated and removed in the solution. The lead sulfate is precipitated in the hydrosulfate aqueous solution by adding a lead nitrate aqueous solution including lead having an α-ray emission of 10 cph/cm2 or less to the hydrosulfate aqueous solution, from which the lead sulfate has been removed, and, at the same time, the solution is circulated while removing the lead sulfate to electrowinning the metal using the hydrosulfate aqueous solution as an electrolytic solution.