Litharge Recovery from Lead Acid Battery Paste
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Solution Overview
Problem
Current methods for recovering highly pure litharge (PbO) from spent lead acid battery paste are costly, energy-intensive, and generate pollution, with the presence of massicot leading to slower electrode formation and reduced purity in lead acid batteries.
Innovation Solution
A low-temperature process involving the conversion of lead acetate to high purity litharge using a strong base, which includes treating lead acid battery paste with a reducing agent, filtering, and combining with an organic acid to form a concentrated lead salt solution, followed by reaction with a second base at elevated temperature to produce litharge, and subsequent heating to form red lead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional smelting methods are used to recover lead from battery paste, then lead metal can be obtained, but the process generates sulfur dioxide pollution, requires high energy input, and produces hazardous dust
Solution Approach 1:
The patent extracts and removes sulfur from the battery paste through chemical treatment with sodium hydroxide, converting lead sulfate to soluble lead compounds while eliminating sulfur as sodium sulfate. This extraction of the harmful sulfur component prevents its conversion to sulfur dioxide during subsequent processing, directly resolving the pollution issue while maintaining lead recovery
Solution Approach 2:
The patent changes the chemical parameters of the paste by converting it from insoluble lead sulfate to soluble lead acetate through controlled chemical reactions. This parameter change allows the lead to be processed in solution phase at lower temperatures, eliminating the need for high-temperature smelting that generates sulfur dioxide, while still achieving complete lead recovery
2Quantity of substance
If conventional smelting methods are used to recover lead from battery paste, then lead metal can be obtained, but the process is highly energy intensive
Solution Approach 1:
The patent replaces the mechanical/thermal smelting process with a chemical solution-based process. Instead of using high-temperature furnaces to melt and separate lead, the invention uses chemical reactions to dissolve lead in controlled steps, allowing separation and recovery at much lower temperatures. This substitution of chemical processes for thermal processes dramatically reduces energy consumption while maintaining lead recovery efficiency
3Quantity of substance
If conventional oxidation of molten lead is used to produce litharge, then litharge can be obtained, but the process is time consuming and produces massicot which slows electrode formation
Solution Approach 1:
The patent performs preliminary purification of the lead compound throughout the process, particularly removing impurities during the solution and precipitation steps. By preparing high-purity lead acetate before converting to litharge, the resulting litharge is free from contaminants that would form massicot. This preliminary action ensures the litharge produced promotes fast electrode formation without requiring additional purification steps
Solution Approach 2:
The patent changes the crystallization parameters during litharge formation by controlling pH, temperature, and addition rate of precipitating agents. These parameter changes promote the formation of pure tetragonal litharge crystals rather than orthorhombic massicot, which has slower reaction kinetics. The controlled precipitation ensures rapid electrode formation while maintaining high litharge purity
4Manufacturing precision
If conventional smelting and purification methods are used, then lead metal purity can be achieved, but the process leads to further contamination and losses
Solution Approach 1:
The patent extracts impurities selectively at each processing stage: sulfur is removed as sodium sulfate, other metal impurities are separated during selective precipitation, and the final litharge is obtained in high purity. This stepwise extraction of impurities avoids the need for repeated sparging and fluxing operations that cause lead losses, achieving high purity with minimal material loss
Solution Approach 2:
The patent uses soluble lead compounds (lead acetate) as an intermediary form during processing. This intermediary allows the lead to be manipulated in solution phase where impurities can be selectively removed without losing lead material. The soluble intermediate form enables precise control over purity while minimizing losses that occur in conventional smelting and sparging processes
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
This process achieves high purity litharge (>95%) quickly and economically, reducing electrode formation time by 50% or more and allowing further oxidation to higher purity red lead, thereby improving battery performance and efficiency.
Implementation Method 1
treating lead acid battery paste with a reducing agent in an acid medium to form an aqueous slurry
Implementation Method 2
combining a base with the solution at an elevated temperature to form high purity litharge
Implementation Method 3
heating the recovered litharge at about 450° C.-500° C. in air for about three hours to form red lead Pb3O4
Data Source
AI summary
The present invention relates to the recovery of high purity litharge from spent lead acid battery paste at a low temperature which does not produce sulfur dioxide. In the process lead acetate or other lead salt is produced which is converted to high purity litharge by precipitation with a base.