Lead Oxide Recovery from Battery Paste via Carboxylate Segmentation
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Solution Overview
Problem
Existing methods for recovering lead oxide from spent lead acid battery paste either achieve high yield at the expense of purity or high purity at the expense of yield, failing to simultaneously attain both high yield and high purity.
Innovation Solution
The process involves treating spent lead acid battery paste with an alkaline hydroxide to remove sulfates, followed by reaction with a carboxylic acid and a reducing agent, filtering, and then treating the filtrate with concentrated alkali hydroxide under an inert atmosphere to form pure litharge PbO at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional smelting processes are used to recover lead oxide from spent battery paste, then high yield is achieved, but purity is compromised due to contaminating impurities
Solution Approach 1:
The recovery process is divided into distinct segments: first treating paste with alkaline hydroxide to remove sulfates, then reacting with carboxylic acid and reducing agent to convert lead compounds to soluble carboxylates, filtering to remove insoluble impurities, and finally treating filtrate with concentrated alkali to precipitate pure PbO. This segmentation allows each step to target specific impurities while preserving lead recovery.
Solution Approach 2:
The invention uses carboxylic acid carboxylates as intermediary compounds. The lead compounds in paste are converted to soluble lead carboxylates, which act as intermediaries that can be easily separated from insoluble impurities through filtration, then converted to pure PbO. This intermediary step enables both high recovery and high purity.
2Manufacturing precision
If methods prioritizing purity are used, then high purity lead oxide is obtained, but yield is reduced
Solution Approach 1:
The process utilizes parameter changes in pH and chemical form to control lead recovery. By adjusting pH to alkaline conditions initially to remove sulfates, then converting lead to soluble carboxylate form, filtering, and finally adjusting to precipitate pure PbO, the process achieves both high purity and high yield by optimizing parameters at each stage.
3Manufacturing precision
If high purity lead oxide is produced through multiple processing steps, then purity is improved, but energy consumption increases
Solution Approach 1:
The invention replaces energy-intensive mechanical smelting and high-temperature calcination with chemical processes. By using alkaline treatment, carboxylic acid reactions, and controlled precipitation, pure PbO is obtained without the need for high-temperature furnaces, significantly reducing energy consumption while maintaining high purity.
4Productivity
If traditional processing methods are used, then lead oxide can be recovered, but sulfur emissions and environmental harm occur
Solution Approach 1:
The invention converts the harmful sulfur component into a benefit by using alkaline hydroxide treatment to remove sulfates from the paste in the initial step. This eliminates sulfur emissions that would otherwise occur during smelting, while the removed sulfates can be handled as a separate waste stream, thus protecting the environment while maintaining lead 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 method achieves high yields and high purity of lead monoxide while reducing energy consumption and sulfur emissions, producing a low-cost, high-purity leady oxide with precise composition, which is not achievable through traditional smelting processes.
Implementation Method 1
treating spent lead acid battery paste with an alkaline hydroxide to remove sulfates
Implementation Method 2
reacting the filter cake with a carboxylic acid and a reducing agent
Implementation Method 3
treating the resulting filtrate with concentrated alkali hydroxide at a temperature of 50-100° C. to form pure litharge PbO
Data Source
AI summary
The invention relates to the low temperature recovery of lead oxide (PbO) from lead acid battery paste through the preparation of lead carboxylate from the battery paste and the conversion of the lead carboxylate to PbO.