Lead Oxide Recovery from Spent Battery Paste
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Solution Overview
Problem
Existing methods for recovering lead oxides from exhausted lead-acid batteries produce impure lead oxides, requiring further conversion to metallic lead and subsequent oxide formation, which is inefficient and costly.
Innovation Solution
A process involving treatment of spent paste from lead-acid batteries with an alkali hydroxide solution, followed by heating and filtration to produce substantially pure lead oxides (PbO, PbO2, or Pb3O4) through calcination at specific temperatures, effectively removing sulfate ions and achieving high-purity lead oxides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional calcination and desulfurization methods are used to recover lead from exhausted batteries, then lead oxides can be produced, but the purity of the lead oxides is insufficient
Solution Approach 1:
The patent applies preliminary action by treating the spent paste with alkali hydroxide solution before calcination to remove sulfate ions. This pre-treatment step prepares the material in advance, ensuring that when calcination occurs, the lead oxides formed are of high purity without requiring additional complex purification steps afterward.
Solution Approach 2:
The patent extracts the harmful sulfate ions from the spent paste by treating it with alkali hydroxide solution, which converts sulfates to soluble salts that can be washed away. This extraction of the contaminant before the main conversion process ensures high purity lead oxide production.
2Manufacturing precision
If multiple processing steps including conversion to metallic lead and subsequent oxide formation are used, then high-purity lead oxides can be achieved, but the process becomes inefficient and costly
Solution Approach 1:
The patent merges the desulfurization and oxide formation steps into a single integrated process. By treating spent paste with alkali hydroxide to remove sulfates, then directly calcining to form lead oxides in one continuous sequence, the process eliminates intermediate steps such as conversion to metallic lead and subsequent re-oxidation, thereby improving efficiency while maintaining high purity.
Solution Approach 2:
The preliminary removal of sulfate ions through alkali treatment ensures that when calcination occurs, high-purity lead oxides are formed directly without requiring subsequent purification or reprocessing steps, thus achieving both high purity and process efficiency.
3Ease of manufacture
If spent paste is directly calcined without prior treatment, then the process is simple, but sulfate ions remain in the product reducing purity
Solution Approach 1:
The patent extracts sulfate ions from the spent paste by treating it with alkali hydroxide solution, which converts insoluble sulfates to soluble salts that can be easily washed away. This extraction step is simple to implement but effectively removes contaminants, achieving high purity without complex subsequent processing.
Solution Approach 2:
The alkali hydroxide solution acts as an intermediary substance that facilitates the removal of sulfate ions. It temporarily binds with sulfates to form soluble salts, enabling easy separation, and then can be washed away, leaving pure lead oxides after calcination.
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 yields high-purity lead oxides that can be directly used in lead acid batteries, reducing the need for additional processing steps and enhancing the economic viability of lead recovery.
Implementation Method 1
treating the spent paste obtained from exhausted lead acid batteries with an alkali hydroxide solution
Implementation Method 2
heating the filter cake from step 'C' to 350-500° C. to form red lead (Pb3O4), or optionally heating the filter cake from step 'C' at a temperature between 650° and 750° C. to obtain substantially pure lead monoxide (PbO)
Implementation Method 3
filtering the mixture of step 'B' and washing the filter cake formed
Data Source
AI summary
A process for recovering lead oxides from the spent paste of exhausted lead acid batteries. The process provides heating the spent paste with an alkali hydroxide solution at elevated temperatures prior to calcinations. Calcination is at various temperatures so that either lead mono-oxide, lead dioxide or red lead is obtained as the principal product. There is also provided the use of the lead oxide to prepare the paste for positive and negative electrodes or other lead compounds.