Lead Recycling via pH-Controlled Salt Precipitation
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Solution Overview
Problem
Existing methods for purifying lead from spent lead-acid batteries rely heavily on pyrometallurgical smelting, which is costly, complex, and generates environmentally harmful byproducts.
Innovation Solution
A solution-based method involving the formation of a mixture with a carboxylate source and a lead-bearing material, followed by pH adjustments to precipitate and isolate lead salts, effectively removing impurities without combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyrometallurgical smelting is used to purify lead from spent lead-acid batteries, then lead can be recovered, but the process generates environmentally harmful byproducts and requires specialized equipment
Solution Approach 1:
The patent replaces the thermal/mechanical pyrometallurgical smelting system with a chemical precipitation system. Instead of using high-temperature combustion to separate lead from impurities, the invention uses controlled chemical reactions in aqueous solution where lead ions are precipitated as lead salts (e.g., lead carbonate, lead sulfate) by adding reagents like sodium carbonate or sulfuric acid. This substitution eliminates the need for specialized high-temperature equipment and prevents the formation of harmful combustion byproducts while achieving effective lead recovery.
Solution Approach 2:
The patent changes the operational parameters from high-temperature pyrometallurgical conditions to ambient or moderate temperature chemical precipitation conditions. By controlling parameters such as pH, reagent concentration, and precipitation conditions, the process achieves selective lead recovery without generating environmentally harmful byproducts. The liquid component can be neutralized and recycled, further reducing environmental impact.
2Manufacturing precision
If multi-stage pyrometallurgical smelting is used, then lead purification can be achieved, but the process complexity and operational costs increase
Solution Approach 1:
The patent replaces complex multi-stage pyrometallurgical refining operations with a single-stage or multi-stage chemical precipitation process. The chemical method achieves comparable or superior lead purity through selective precipitation reactions, eliminating the need for multiple sequential refining steps required in traditional smelting. This substitution dramatically reduces equipment complexity and operational complexity while maintaining high lead purity.
Solution Approach 2:
The patent achieves high lead purity by controlling chemical parameters such as pH, reagent dosage, and precipitation conditions rather than through multiple thermal processing stages. By optimizing these chemical parameters, the process achieves effective impurity separation in fewer steps, reducing overall process complexity while maintaining manufacturing precision.
3Quantity of substance
If pyrometallurgical smelting is used, then lead can be extracted from spent batteries, but specialized equipment and consumables are required
Solution Approach 1:
The patent replaces specialized pyrometallurgical equipment (furnaces, smelting reactors, gas treatment systems) with conventional chemical processing equipment such as mixing tanks, filtration systems, and neutralization vessels. This substitution maintains effective lead extraction capability while using readily available, easier-to-manufacture equipment that does not require specialized high-temperature processing capabilities.
Solution Approach 2:
The patent employs consumable chemical reagents (precipitating agents like sodium carbonate, sulfuric acid, and neutralizing agents) that are inexpensive and easily replenished compared to specialized pyrometallurgical consumables. These chemical consumables can be readily purchased and replaced without requiring specialized supply chains, making the process easier to manufacture and operate.
4Quantity of substance
If existing purification methods are used, then lead can be recovered, but operational costs increase due to consumables and specialized operations
Solution Approach 1:
The patent replaces energy-intensive pyrometallurgical operations with low-energy chemical precipitation processes. The chemical method operates at ambient or moderate temperatures without requiring continuous high-energy input for heating and maintenance, significantly reducing operational energy costs while achieving effective lead recovery.
Solution Approach 2:
The patent changes operational conditions from high-energy thermal processes to low-energy chemical processes by controlling parameters such as pH and reagent concentration. This parameter change enables lead recovery at lower operational costs by eliminating the need for continuous energy input required by pyrometallurgical systems.
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 method enables the efficient extraction, purification, and recycling of lead from spent batteries, reducing environmental impact and operational costs while producing high-purity leady oxide for new batteries.
Implementation Method 1
generating a first lead salt precipitate in the mixture as the carboxylate source reacts with the lead-bearing material
Implementation Method 2
increasing the pH of the mixture to dissolve the first lead salt precipitate
Implementation Method 3
decreasing the pH of the liquid component of the mixture to generate a second lead salt precipitate
Data Source
AI summary
The present disclosure relates to methods by which lead from spent lead-acid batteries may be extracted, purified, and used in the construction of new lead-acid batteries. A method includes: (A) forming a mixture including a carboxylate source and a lead-bearing material; (B) generating a first lead salt precipitate in the mixture as the carboxylate source reacts with the lead-bearing material; (C) increasing the pH of the mixture to dissolve the first lead salt precipitate; (D) isolating a liquid component of the mixture from one or more insoluble components of the mixture; (E) decreasing the pH of the liquid component of the mixture to generate a second lead salt precipitate; and (F) isolating the second lead salt precipitate from the liquid component of the mixture. Thereafter, the isolated lead salt precipitate may be converted to leady oxide for use in the manufacture of new lead-acid batteries.