High Purity Tin Refining via Two-Stage Electrolysis and Smoothing Agents
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Solution Overview
Problem
High purity tin produced by existing methods contains particles that cause clogging in ultrafine processing apparatuses, hindering micro-fine wiring and other applications due to contaminants like tin oxide, tin sulfide, and silicon dioxide.
Innovation Solution
A two-stage refining process using sulfuric acid and hydrochloric acid baths, with a diaphragm to separate anode and cathode chambers, and the addition of a smoothing agent to reduce surface area and prevent particle formation, followed by melting and casting in a reducing atmosphere to minimize oxides and nonmetallic inclusions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electrolytic methods are used to produce high purity tin, then the tin achieves high purity (99.999% or 5N), but particles (tin oxide, tin sulfide, silicon dioxide) remain present causing clogging in ultrafine processing
Solution Approach 1:
The patent divides the refining process into two distinct stages: first electrolytic refining in sulfuric acid bath, then secondary electrolytic refining in hydrochloric acid bath. This segmentation allows each stage to target different impurities, with the second stage specifically removing particles that survived the first stage, thereby resolving the contradiction between achieving high purity and eliminating clogging particles.
Solution Approach 2:
The patent changes the chemical environment parameters between refining stages by switching from sulfuric acid electrolyte to hydrochloric acid electrolyte. This parameter change enables the second stage to dissolve and remove specific particle types (oxides, sulfides, silicates) that are not effectively removed in the first stage, thus eliminating clogging issues while maintaining high purity.
2Manufacturing precision
If a diaphragm is introduced to separate anode and cathode chambers, then lead removal efficiency is improved, but device complexity increases
Solution Approach 1:
The patent introduces a diaphragm as an intermediary component between the anode and cathode chambers. This diaphragm acts as a physical barrier that prevents lead ions and other impurities from migrating to the cathode side while still allowing ionic conduction for the electrolysis process to proceed, thus improving lead removal efficiency without completely disrupting the electrolytic cell operation.
3Object-affected harmful factors
If smoothing agent is added to reduce surface area of electrodeposited tin, then particle formation is prevented, but additional processing steps are required
Solution Approach 1:
The patent applies smoothing agents to the electrolytic solution before the electrodeposition process begins. This preliminary action modifies the electrolyte composition in advance, which then controls the morphology of the deposited tin during electrolysis, resulting in a compact, low-surface-area structure that resists particle formation without requiring additional post-processing steps.
Solution Approach 2:
The smoothing agent acts as an intermediary substance between the electrolyte and the deposited tin. It modifies the interface properties during electrodeposition, controlling the growth morphology of the tin to be compact and smooth, thereby preventing particle formation while integrating seamlessly into the electrolytic process.
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 process significantly reduces the number of particles larger than 0.5 μm per gram of tin, preventing clogging and improving the purity and usability of high purity tin in ultrafine processing.
Implementation Method 1
carrying out electrolysis in an electrolytic bath comprising 99.95% by weight or more of tin as an anode
Implementation Method 2
withdrawing an electrolytic solution present on an anode side in the electrolytic bath partitioned by a diaphragm between an anode and a cathode
Implementation Method 3
adding a smoothing agent to the electrolytic solution to form electrodeposited tin in the form of plate
Implementation Method 4
melting and casting the needle-like electrodeposited tin in a reducing gas atmosphere
Data Source
AI summary
Provided is high purity tin having purity of 5N (99.999% by mass), which can suppress generation of particles. According to the high purity tin, the number of particles each having a particle diameter of 0.5 μm or more is 50,000 or less per a gram.