Process Proposal: Integrated EW System
Our comprehensive solution integrates an Electrowinning (EW) System for Germanium, Indium, Tellurium, Antimony, and recovery of Gallium and Hafnium. This proposal includes a cleaner circuit for zinc sulfate, leaching of 8 tons/hour cake, a solar steam dryer, and cyclone EW cells.
This integrated approach maximizes efficiency while recovering valuable critical metals from process streams. The system is designed to be modular, environmentally sustainable, and economically advantageous.
Input Materials and Process Rates
The process handles substantial volumes of zinc sulfate solution while continuously processing 8 tons per hour of metal-rich cake. The specialized composition of the feedstock contains valuable elements including silver, gold, germanium, tellurium, copper, indium, hafnium, and gallium.
Process Flow Overview
Pre-treatment (Cleaner Circuit)
Remove Pb, Co, Cd, Ni from zinc sulfate using lime neutralization, sulfide precipitation, and polishing filtration
Leaching System
Nitric acid leaching of solid cake at 60-80°C using solar-assisted steam heating to solubilize target elements
Steam Dryer System
Solar thermal parabolic trough system with molten salt or sand bed thermal storage for 24-hour operation
Electrowinning and Recovery
Cyclone cells (250mm x 2000mm) with improved electrolyte circulation, arranged in 2 banks of 12 cells
Steam Dryer System (Solar Heated)
Solar Type
Parabolic trough concentrators that efficiently capture and focus solar energy for steam generation
Thermal Storage
Sand bed providing approximately 10-12 hours of operation buffer
Heat Capacity
System designed to maintain steam temperatures of 150-200°C for continuous operation
Purpose
Dry leached cake and supply consistent heat to reactors, reducing conventional energy costs
Full Integrated Flow Diagram
1
Solid Cake Feed
Initial input of 8 tons/hour of metal-rich cake material
2
Nitric Leach Reactor (Solar Heated)
Dissolution of target metals using nitric acid at controlled temperatures
3
Filtration & Solar Drying
Separation of solids and solution, with residue sent to solar dryer for moisture removal
4
Selective Extraction/Electrowinning
Recovery of Ge, In, Te, Sb, Ga, and Hf using specialized cyclone cells
5
Solution Recycling
Purified solution returned to zinc sulfate circuit or prepared for disposal
Electrowinning Cell System Details
Physical Specifications
  • Cyclone Cell Diameter: 250mm
  • Cyclone Cell Height: 2000mm
  • Electrodes: Titanium Cathode / Inert Anode (Ti/Ir coated)
  • Cell Bank Configuration: 2 x 12 cell arrays
Operational Parameters
  • Electrolyte Temperature: 45-65°C
  • Current Density: 100-150 A/m²
  • Power Supply: 6-12V, 300-500A per cell
  • Cooling: Natural convection or optional air-cooled jackets
Advantages of Cyclone Cells
Enhanced Turbulence
The cyclonic flow pattern creates higher turbulence within the cell, resulting in better deposit quality and more uniform metal recovery compared to traditional flat plate designs.
Compact Footprint
Vertical orientation and efficient design means cyclone cells require significantly less floor space than conventional flat plate electrowinning tanks for the same production capacity.
Reduced Maintenance
The self-cleaning nature of the cyclonic flow reduces scaling and buildup, leading to lower maintenance requirements and less downtime for cleaning operations.
Modular Scalability
The system can be easily expanded by adding additional cell modules, allowing for flexible capacity increases without major redesign or construction.
Estimated System Sizing
24
Cyclone Cells
Total units required for full operation
400m²
Solar Collectors
Mirror surface area for parabolic troughs
30m³
Thermal Storage
Molten salt tank or sand thermal bed volume
2-3
Leach Reactors
Continuous stirred reactors for nitric leaching
The system also includes one steam boiler with solar integration, capable of producing 2-3 tons per hour of steam. All components are sized to handle the 8 tons per hour throughput while maintaining operational flexibility.
Key Notes
Modular Design
The system can scale by adding 12-cell cyclone banks, allowing for phased implementation and capacity expansion as needed without complete redesign.
Solar-Powered Efficiency
Solar-powered drying significantly reduces operational costs by minimizing diesel and electricity expenses while providing sustainable energy for continuous operation.
Strategic Value
Recovery of Ge, In, Te, Sb, Ga, and Hf provides access to critical metals with high market premiums, substantially improving project economics.
Cleaner Solution
The improved zinc sulfate solution reduces penalties when selling ZnSO₄ solution or cathodes, creating additional value beyond the recovered specialty metals.