Lead Battery Paste Recovery Using Zinc Displacement and Zinc Reuse
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Solution Overview
Problem
The current pyrometallurgical process for recovering lead from lead-acid battery paste is energy-intensive, inefficient, and generates toxic slags and emissions, while electrolysis methods are complex and costly, necessitating a more efficient and environmentally friendly lead recovery process.
Innovation Solution
A process involving direct solid-solid reactions between lead compounds and metallic zinc, with the addition of water and soluble zinc salt-forming substances, followed by electrolytic treatment to recover metallic lead, which also recycles zinc and utilizes sulfuric acid from batteries, reducing energy consumption and waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If pyrometallurgical process is used for lead recovery from paste, then lead can be recovered, but energy consumption is very high and toxic slags are generated
Solution Approach 1:
The invention changes the fundamental parameters of the recovery process by replacing high-temperature pyrometallurgy (over 1000°C) with a wet chemical process operating at ambient or moderate temperatures. This involves changing the chemical environment from oxidizing high-temperature conditions to controlled aqueous chemistry with selective reagents, thereby eliminating energy-intensive heating while preventing toxic slag formation through selective precipitation and dissolution.
Solution Approach 2:
The invention introduces chemical intermediaries (selective reagents, complexing agents, and precipitants) that mediate the recovery process. These intermediaries enable selective dissolution of lead compounds, separation from other battery materials, and controlled precipitation of pure lead products, replacing the direct high-temperature reduction approach that generates toxic slags.
2Ease of manufacture
If pyrometallurgical process is used for lead recovery from paste, then lead can be recovered, but the process is very complex and expensive
Solution Approach 1:
The invention segments the complex pyrometallurgical process into distinct, manageable chemical steps: selective dissolution of lead compounds using aqueous reagents, separation of dissolved lead from undissolved battery materials through filtration or decantation, and precipitation of lead from the filtrate using controlled chemical reactions. Each segment can be performed in simple equipment, avoiding the need for complex high-temperature furnaces and slag management systems.
Solution Approach 2:
The invention replaces the mechanical/thermal system of pyrometallurgy (high-temperature heating, mechanical stirring, slag pouring) with chemical processes operating at ambient or moderate temperatures. This substitution uses chemical reactions and phase changes in aqueous solutions instead of extreme thermal conditions, simplifying the equipment and operational complexity.
3Loss of energy
If electrolysis method is used for lead recovery, then energy consumption is reduced, but the process becomes complex and costly
Solution Approach 1:
The invention employs inexpensive, readily available chemical reagents (acids, bases, salts, complexing agents) that can be used in straightforward batch or continuous processes. These consumable chemicals replace expensive, complex electrolysis equipment and operational requirements, achieving low energy consumption through simple chemical precipitation and dissolution reactions rather than energy-intensive electrochemical cells.
4Manufacturing precision
If desulfation treatment is performed on paste, then lead sulfate is converted, but the reaction is never exhaustive and lead sulfate remains unconverted
Solution Approach 1:
The invention applies excessive or repeated action of selective reagents to ensure complete conversion. By using reagents in excess or applying them in multiple sequential steps, the process drives the dissolution reaction to completion, converting all lead sulfate and other lead compounds. The excess reagent or additional processing steps ensure that no lead sulfate remains unconverted, achieving both high conversion completeness and efficient recovery.
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 efficiently recovers metallic lead in a single step, reduces energy consumption, minimizes toxic waste, and allows for the reuse of sulfuric acid, achieving high current efficiency in zinc recovery and enabling the recycling of lead-acid battery electrolytes.
Implementation Method 1
direct solid-solid reaction with metallic zinc
Implementation Method 2
direct solid-solid reaction between lead compounds and metallic zinc
Implementation Method 3
addition to the mass, during mixing, of water and of an aqueous solution containing a substance capable of forming soluble zinc salts
Implementation Method 4
electrolytic treatment of the separated solution in order to recover metallic zinc
Data Source
AI summary
A process for obtaining metallic lead from its compounds present in an end-of-life lead-acid battery through a direct solid-solid reaction with metallic zinc includes a) dry mixing of the mixture of lead compounds present in an end-of-life lead-acid battery with a metered quantity of metallic zinc powder; b) an addition to the mass, during mixing, of water and of an aqueous solution containing a substance capable of forming soluble zinc salts; c) a separation of the solid, essentially consisting of metallic lead, from the liquid phase in which the soluble zinc salt is present; and d) an electrolytic treatment of the resulting previously separated solution in order to recover metallic zinc suitable for reuse in the dry mixing treatment.