Lead Recovery via Ammonium Chloride Electroreduction
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Solution Overview
Problem
Current methods for treating lead paste/mud from waste lead batteries, such as fire smelting, result in environmental pollution and high energy consumption, while existing hydrometallurgical processes are not economically viable or environmentally friendly.
Innovation Solution
A hydrometallurgical process using an ammonium chloride aqueous solution as an electrolyte, with a titanium anode and stainless steel or lead cathode, applying a direct-current electric field to reduce lead compounds to metal lead, oxidizing ammonia to nitrogen, and forming ammonium sulfate and chloride, allowing for lead monoxide and dioxide reduction to metal lead without generating harmful gases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fire smelting method is used to treat lead paste/mud, then lead recovery is achieved, but harmful substances such as lead dust, sulfur dioxide, and dioxins are generated causing serious environmental pollution
Solution Approach 1:
The patent changes the fundamental parameter of the treatment process from thermal (fire smelting) to electrochemical (electrolysis). By using electrolysis in an ammonium chloride solution, the process achieves lead recovery without generating harmful emissions, as the electrochemical reduction occurs in a closed aqueous system rather than open combustion
Solution Approach 2:
The patent replaces the mechanical/thermal smelting system with an electrochemical system. Instead of using high-temperature combustion to reduce lead compounds, the invention uses electrical current to drive the reduction reaction at the cathode, substituting thermal energy with electrical energy to achieve the same metallurgical goal without pollution
2Reliability
If fire smelting method is used to treat lead paste/mud, then lead recovery is achieved, but high energy consumption is required
Solution Approach 1:
The patent changes the energy parameter from high-temperature thermal energy to lower-energy electrochemical energy. The electrolysis process operates at ambient or moderate temperatures, using electrical energy directly for the reduction reaction, which is more energy-efficient than the high-temperature combustion required for fire smelting
3Object-generated harmful factors
If existing hydrometallurgical methods are used to treat lead paste/mud, then environmental protection is improved, but economic viability and cost-effectiveness deteriorate
Solution Approach 1:
The patent changes the chemical environment parameter by using ammonium chloride solution as the electrolyte, which allows for direct electrolysis of lead compounds without complex pre-treatment steps. This simplifies the overall process compared to other hydrometallurgical methods, reducing operational complexity and cost while maintaining environmental benefits
Solution Approach 2:
The ammonium chloride electrolyte system enables the lead compounds in the paste/mud to be directly reduced at the cathode without requiring extensive pre-processing or conversion steps. The system uses the existing lead compounds (PbSO4, PbO2, PbO) directly as feedstock, making the process economically viable by eliminating costly intermediate treatment stages
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 eliminates harmful gas emissions, reduces energy consumption, and achieves a high lead recovery rate of over 99%, making it environmentally friendly and economically competitive with traditional fire smelting methods.
Implementation Method 1
a direct-current electric field is applied in an electrolytic bath; the lead compound is reduced to metal lead after obtaining electrons at the cathode
Implementation Method 2
at the anode, ammonia is oxidized to nitrogen for escaping
Implementation Method 3
the lead compound is reduced to metal lead after obtaining electrons at the cathode
Data Source
AI summary
A process for preparing lead by electroreduction with an ammonium chloride and an ammonia is disclosed. In the process, an ammonium chloride aqueous solution is used as an electrolyte, a lead compound is used as a raw material, titanium is used as an anode, stainless steel or lead is used as a cathode, and a direct-current electric field is applied in an electrolytic bath; the lead compound is reduced to metal lead after obtaining electrons at the cathode; and at the anode, ammonia is oxidized to nitrogen for escaping, and H+ ions are generated simultaneously; sulfate radical ions and chloride ions in the lead compound enter the solution to form ammonium sulfate and ammonium chloride; and the lead monoxide and lead dioxide in the lead compound are reduced to a metal lead and OH− ions are simultaneously released to combine with the H+ ions to form water.