Lead Acid Battery Paste Recovery via Electrochemical Dewatering

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Solution Overview

Problem

Existing lead recycling processes face challenges with electrolyte management, lead dioxide accumulation, and contamination, particularly in smelterless recycling of lead acid battery paste, which leads to inefficiencies and increased costs due to water dilution and fluorine-containing electrolyte issues.

Innovation Solution

A method involving washing and heating desulfurized lead paste to reduce residual water and convert lead dioxide to lead oxide, followed by combining it with a recycled electrolyte for electrochemical lead recovery, thereby reducing electrolyte loss and contamination, and using alkane sulfonic acid like methane sulfonic acid for improved lead ion enrichment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If lead paste is leached with aqueous solutions (ammonium chloride, hydrogen peroxide) to reduce lead dioxide, then lead dioxide quantities are substantially reduced, but water requirement is not insignificant and the presence of water dilutes the electrolyte, thereby increasing the need for and cost of electrolyte

Engineering Contradiction:

Improvelead dioxide quantityVSAvoidelectrolyte dilution

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

The patent extracts and removes water from the system by using filter pressing to dewater the lead paste before electrochemical processing. This separation removes the harmful aqueous phase that would otherwise dilute the electrolyte, while retaining the solid lead-containing material for subsequent processing.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary dewatering and desulfurization of the lead paste before it enters the electrochemical recovery process. By removing water and sulfate contaminants in advance, the electrolyte is protected from dilution and contamination during the main processing operation.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If desulfurized lead paste is processed without dewatering, then processing is simpler, but residual water and sulfate contaminate and dilute the downstream electrolyte

Engineering Contradiction:

Improveprocessing simplicityVSAvoidelectrolyte quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent introduces filter pressing as an intermediary step between desulfurization and electrochemical processing. This intermediate operation removes water and sulfate contaminants, acting as a buffer that protects the electrolyte quality without requiring complex modifications to the overall process flow.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If fluorine containing electrolyte (fluoboric or fluosilic acid) is used for lead recovery, then lead can be recovered in metal form from desulfurized paste, but the process becomes problematic due to electrolyte management issues

Engineering Contradiction:

Improvelead recovery efficiencyVSAvoidelectrolyte management problems

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the electrolyte composition parameters by using non-fluorine containing electrolytes (such as sulfuric acid or organic acids) instead of traditional fluoboric or fluosilic acid. This parameter change eliminates the harmful effects associated with fluorine-containing electrolytes while maintaining effective lead recovery capability.

Inventive Principle:

Principle #35Parameter changes

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 approach effectively minimizes electrolyte dilution, reduces lead dioxide build-up, and achieves high-purity metallic lead recovery with reduced water consumption and minimal environmental impact, enhancing the efficiency and sustainability of lead recycling processes.

Implementation Method 1

heating the washed desulfurized lead paste to reduce the residual water to equal or less than 10 wt % and to reduce at least 50% of the lead dioxide to lead oxide

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

heating the washed desulfurized lead paste to reduce the residual water to equal or less than 10 wt % and to reduce at least 50% of the lead dioxide to lead oxide

Methodology Applied

Scientific EffectThermal decomposition: Decomposition (biological)

Implementation Method 3

the lead ion enriched electrolyte is subjected to an electrochemical lead recovery operation to thereby recover metallic lead on a cathode

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Data Source

PatentUS11708640B2Systems and methods for aqueous recovery of lead from lead acid batteries with reduced electrolyte demand

Publication Date: 2023.07.25 AQUA METALS INC

AI summary

Lead is recovered from lead paste of a lead acid battery in a continuous and electrochemical lead recovery process. In especially preferred aspects, lead paste is processed to remove residual sulfates, and the so treated lead paste is subjected to a thermal treatment step that removes residual moisture and reduces lead dioxide to lead oxide. Advantageously, such pretreatment will avoid lead dioxide accumulation and electrolyte dilution.