InyoAg — 5N Silver Refining Facility
Darwin, California
Avimetal's Cyclone Electrowinning and Cyclone Electrorefining technology licensed to InyoAg for recovery and ultra-high-purity refining of silver by-product from tungsten ore processing — the first 5N silver refinery in California's historic Inyo mining district.
Project Overview
The InyoAg 5N Silver Refining Facility is located in Darwin, California — a historic mining community in Inyo County long known for its silver, lead, and tungsten deposits. InyoAg Company has entered into a technology license agreement with Avimetal for the Cyclone Electrowinning and Cyclone Electrorefining systems to recover and refine silver produced as a by-product of tungsten (W) ore processing.
Darwin's tungsten ore carries meaningful quantities of silver that conventional processing circuits have historically left underutilized. InyoAg's facility is designed to capture this value stream — converting what was previously a secondary by-product into 5N-grade silver (99.999% purity) suitable for aerospace, defense, semiconductor, and advanced electronics markets.
Background — Darwin & Tungsten-Silver Co-Recovery
The Darwin Mining District has produced silver, lead, zinc, and tungsten since the 1870s. The region's tungsten ore deposits — primarily scheelite and wolframite — carry silver values that are released during the acid leach and concentration stages of tungsten processing. These silver-bearing solutions have historically been treated as a waste stream or low-value by-product.
InyoAg recognized that with the right electrochemical technology, this silver stream could be converted into a premium-grade product commanding significant market premiums over standard commercial silver. Avimetal's Cyclone EW/ER system was selected after a competitive evaluation based on its demonstrated ability to achieve 5N purity in a compact, scalable configuration.
Technology — Cyclone EW & ER Process
The refining process at Darwin follows Avimetal's proven 5N silver production flow:
Silver-Bearing Solution Capture
Silver-bearing leachate from tungsten ore processing is collected, filtered, and conditioned. Silver concentration and pH are adjusted to optimal electrowinning parameters before entering the cell circuit.
Cyclone Electrowinning — Initial Recovery
Silver ions are deposited from solution onto titanium cathodes using Avimetal's cyclone vortex-flow cells. Controlled electrolyte circulation maximizes mass transfer and current efficiency, producing high-yield silver deposits in a fraction of conventional cell time.
Granulation & Dissolution
Harvested silver is melted, granulated in cold water to increase surface area, then dissolved in nitric acid to produce a high-purity silver nitrate electrolyte for the final refining stage.
Cyclone Electrorefining — 5N Purification
The silver nitrate electrolyte feeds the Cyclone ER cells where impure silver anodes dissolve and ultra-pure silver re-deposits on the cathode. Vortex circulation eliminates concentration polarization, producing uniform crystal growth at 99.999% purity.
Crystal Harvest & Final Casting
5N silver crystals are harvested, washed, dried, and remelted in a vacuum furnace to produce finished 5N silver bars — suitable for aerospace, defense, semiconductor, and photovoltaic applications.
Avimetal Technology Licensed
Cyclone Electrowinning System
High-efficiency vortex-flow cells recover dissolved silver from tungsten process leachate. Iridium-coated MMC anodes with titanium cathodes. Scalable from pilot to 300-cell commercial configuration.
View Product →Cyclone Electrorefining System
Final-stage purification to 5N (99.999%) silver specification. Continuous vortex electrolyte circulation produces consistent crystal quality and eliminates impurity entrapment common in static cells.
View Product →Pilot Results & Scale-Up Plan
The initial pilot system was commissioned at the Darwin facility and operated successfully, producing silver meeting 5N (99.999%) purity specification consistently across multiple production runs. Key pilot outcomes included:
| Silver Purity Achieved | 99.999% (5N) ✓ |
| Current Efficiency | Above target threshold ✓ |
| Crystal Quality | Uniform, impurity-free ✓ |
| Pilot Status | Successfully Completed ✓ |
| Scale-Up Decision | Approved — 300 cells |
Scale-Up Roadmap — Cell Deployment
Market Application — 5N Silver
Ultra-high-purity 5N silver (99.999%) commands a significant premium over commercial-grade silver due to its unique electrical, thermal, and chemical properties. InyoAg's production will target the following high-value markets:
Aerospace & Defense — Precision electrical contacts, satellite systems, and defense electronics requiring certified ultra-pure metal.
Semiconductor Manufacturing — Silver bonding wires, conductive pastes, and die-attach materials for IC production.
Advanced Photovoltaics — High-efficiency solar cell metallization requiring consistent 5N-grade silver paste feedstock.
Medical Devices — Implantable electronics and biosensor components requiring biocompatible, ultra-pure silver.
Have a Similar Silver Recovery Challenge?
Avimetal's Cyclone EW and ER technology is available for licensing or direct equipment supply. We work with mine operators, refiners, and processing facilities globally to unlock silver and precious metal value streams.