Lead Silver Recovery from Hydrometallurgical Residues
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Solution Overview
Problem
Current methods for recovering lead and silver from hydrometallurgical residues are inefficient, as they either fail to recover silver effectively, produce high energy consumption and emissions, or require costly equipment, and often result in products with high chloride content that are not acceptable to conventional smelters.
Innovation Solution
A process involving oxidative leaching of hydrometallurgical residues with a chloride brine solution followed by precipitation with a carbonate compound, and subsequent purification, to produce a lead and silver carbonate concentrate with low chloride content, allowing for simultaneous recovery and purification of both metals in a single, marketable product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pyrometallurgical processing is used to recover metals from residues, then metal recovery is achieved, but energy consumption is high and emissions are produced
Solution Approach 1:
The patent changes the fundamental processing parameters from high-temperature pyrometallurgical conditions to ambient or moderate temperature hydrometallurgical conditions. This is achieved by using aqueous leaching solutions with controlled pH, redox potential, and composition to dissolve target metals from residues, thereby recovering metals without the high energy consumption and emissions associated with smelting operations
Solution Approach 2:
The patent replaces the mechanical/thermal energy-intensive pyrometallurgical system with a chemical-based hydrometallurgical system. Instead of using heat and mechanical agitation at high temperatures to extract metals, the process uses chemical reactions in aqueous solutions to selectively dissolve and recover metals, substituting one energy-intensive mechanical system with a chemically-driven process that operates at lower energy levels
2Productivity
If conventional lead smelter feed is produced through existing methods, then lead recovery is achieved, but chloride content is high making the product unacceptable to smelters
Solution Approach 1:
The patent selectively extracts lead from the residue matrix using controlled leaching conditions, then separately removes chloride impurities through washing and purification steps. This two-stage approach first isolates the target metal and then removes unwanted contaminants, achieving both high lead recovery and low chloride content in the final concentrate product
Solution Approach 2:
The patent performs preliminary leaching and separation steps before final product formation, allowing chloride content to be controlled and minimized during the concentration process. By establishing the correct chemical environment early in the process and controlling precipitation conditions, the final concentrate achieves smelter-acceptable low chloride levels while maintaining high lead content
3Productivity
If hydrometallurgical processing is used to recover lead, then lead extraction efficiency is improved, but silver cannot be recovered
Solution Approach 1:
The patent designs a universal leaching system that can simultaneously dissolve multiple metals (lead, silver, and other valuable components) from the residue using the same aqueous solution and processing conditions. The leaching solution composition and parameters are optimized to extract multiple target metals concurrently, making a single process applicable for recovering various metal values from complex residues
Solution Approach 2:
The patent merges the recovery of lead and silver into a single integrated process flow. Both metals are leached simultaneously in the same solution, then separated and concentrated together through coordinated precipitation and solid-liquid separation steps, achieving combined recovery of multiple metals that would otherwise require separate processing lines
4Productivity
If electrowinning is used to extract lead, then lead recovery is achieved, but capital cost is high compared to market price
Solution Approach 1:
The patent replaces expensive, capital-intensive electrowinning equipment with simpler, lower-cost hydrometallurgical processing equipment. The process uses conventional leaching tanks, filtration systems, and precipitation vessels that are far less expensive than electrolytic cells and associated power infrastructure, making the process economically viable at current lead prices
Solution Approach 2:
The patent changes the extraction mechanism from electrochemical (electrowinning) to chemical (hydrometallurgical leaching and precipitation). This parameter change fundamentally alters the equipment requirements and capital costs, replacing high-voltage electrical systems with moderate-temperature chemical processing systems that have lower capital expenditure and operating cost profiles
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 achieves high yields of lead and silver recovery in a single concentrate with low chloride content, making it economically viable and suitable for conventional smelters, reducing environmental impact and operational costs.
Implementation Method 1
subjecting a hydrometallurgical residue comprising at least lead and silver to an oxidative leaching in the presence of a chloride brine solution and an oxidizing agent, thus selectively solubilizing lead and silver as chloride soluble compounds
Implementation Method 2
reacting the pregnant leaching solution obtained in step a) with a carbonate compound which acts as precipitating agent, thus jointly precipitating lead and silver as a carbonate concentrate
Data Source
Figure 1
AI summary
The present invention relates to a process for the selective and ecoefficient recovery of lead and silver jointly as a concentrate product from hydrometallurgical residues.