Lead Accumulator Desulfurization via Carbonation
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Solution Overview
Problem
Current desulfurization processes for lead accumulators are inefficient in removing sulfur from pastel and fine grid fractions, leading to high sulfur emissions, excessive slag formation, and sodium imbalances, which complicates downstream processing and emissions control.
Innovation Solution
A two-phase desulfurization process using Na2CO3 and NaHCO3 reactions to convert PbSO4 into PbCO3, followed by a desodification phase with CO2 to minimize sulfur and sodium content, optimizing reagent use and separating large and fine pastel fractions for targeted treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If method b) (conversion) is used to treat pastel, then sulfur emissions are reduced, but slag formation increases proportionally to the quantity of additives added
Solution Approach 1:
The invention changes the chemical parameters by using a specific dosage of additives (5-15% by weight of carbonate and 2-5% by weight of iron) rather than excess amounts. This optimized parameter range achieves effective sulfur fixation while minimizing slag formation, resolving the contradiction between emission reduction and slag production.
Solution Approach 2:
The invention converts the harmful sulfur into a beneficial product by forming a controlled ternary matte (xNa2S.yFeS.zPbS) that captures sulfur in a manageable form. This controlled conversion allows sulfur to be fixed in the slag without creating excessive slag volumes, transforming the harmful emission problem into a controlled material transformation.
2Object-generated harmful factors
If method b) (conversion) is used to treat pastel, then sulfur emissions are reduced, but energy requirements increase due to higher melting temperature needed for slag
Solution Approach 1:
The invention optimizes the chemical composition parameters of the additives and their dosages to control the melting characteristics of the resulting slag. By using specific ratios of carbonate, iron, and coal (5-15% carbonate, 2-5% iron, with coal as reducing agent), the slag's melting point is adjusted to reduce the energy required for melting while still achieving effective sulfur fixation.
3Quantity of substance
If method a) (desulfurization with alkalis) is used to treat pastel, then sulfur is removed from pastel, but sodium sulfate accumulates in solution requiring additional treatment
Solution Approach 1:
The invention extracts and removes the problematic sodium sulfate from the system by using a controlled desulfurization process that limits sodium sulfate formation. By using moderate amounts of alkalis (5-15% by weight of carbonate) rather than excess amounts, the process removes sulfur while minimizing sodium sulfate accumulation, allowing the solution to be more easily treated and reused.
4Quantity of substance
If excess alkalis are added for desulfurization, then sulfur removal efficiency increases, but sodium balance is disrupted and additional filtration is required
Solution Approach 1:
The invention optimizes the dosage parameters of alkalis to a specific range (5-15% by weight of carbonate) that achieves effective sulfur removal without causing excessive sodium sulfate formation. This parameter optimization maintains sodium balance and avoids the need for additional filtration steps, reducing process complexity while maintaining high sulfur removal efficiency.
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
Achieves nearly complete sulfur removal and sodium recovery, reducing slag formation, energy consumption, and SO2 emissions, with minimal residual sulfur and sodium in the final product, enhancing the efficiency and environmental impact of lead production.
Implementation Method 1
the lead sulfate of the pastel/grids is put in contact with Na2CO3 to react according to the following reactions: 3 PbSO4+3 Na2CO3+H2O→Pb3(CO3)2(OH)2+3 Na2SO4+CO2
Implementation Method 2
the thickened product is put in contact with CO2 according to the following reactions: Pb3(CO3)2(OH)2+CO2→3 PbCO3+H2O; NaPb2(CO3)2OH+CO2→2 PbCO3+NaHCO3
Data Source
AI summary
The present invention relates to a desulfurization process of pastel and grids of lead accumulators comprising a carbonation in two steps, a granulometric separation between the two steps followed by specific desulfurization of the large part, a desodification obtaining the conversion of the PbSO4 contained in the pastel into PbCO3 which can be easily converted into metallic Pb in an oven by the addition of coal. The system used for the desodification of the large part of the pastel can also be used for the desulfurization of the fine part of the grids.