Draft:Vortex electrowinning

Vortex electrowinning is an electrowinning technology developed by one of the founders of Electrometals Mining (later to become emew Corporation) trying to develop an efficient copper powder production method.  It was discovered that there were very significant improvements in metal recovery rates and selectivity as a result of the high flow rate and vortex design enhancing mass transfer in the cell. In contrast, traditional electrowinning involves placing an anode and cathode in a bath of slowly circulating or stagnant electrolyte, where metal ions gradually diffuse to the cathode surface for plating.

History

In 1992 Neil Barr, Robert Dedenus, and Patrick Treasure pioneered the vortex electrowinning technology and registered the world's first patent on the process. One of the original inventors (Patrick Treasure) founded Euralba Mining which was later to become Electrometals Mining and after that emew Clean Technologies  in order to develop and commercialize the technology. Over the next decade, there were technological innovations, including nickel recovery and metal powder production, leading to the establishment of commercial plants in the U.S. and Chile.

During this period, the company developed new technologies for metal recovery, including innovative solutions for silver recovery from cyanide and next-generation copper plants, establishing itself as an industry leader.

In 2000, a patent was issued for powder extraction from metal-rich solutions using an electrowinning cell. The first fully automated silver electrowinning cells were based on this patent which uses the electrolyte to flush high purity silver crystals from the cell at regular intervals.

Application

The technology was patented in China by Ke Fei in 2009 and has been adopted by others such as Electramet in the USA as a highly effective method to recover copper and other metals from solution as a high-quality metallic product.

There are now many established applications for the technology for producing copper, silver, tin, nickel, gold, and other metals efficiently and safely with no toxic gases or mists in the working environment.

Copper Recovery

Vortex electrowinning technology has advanced the process of copper electrowinning by enhancing traditional methods used to recover copper from acidic solutions.

Typically, copper is recovered by applying an electric current to plate the metal onto a cathode from a slowly moving or stagnant electrolyte tank. In comparison, vortex electrowinning uses high flowrate to improve mass transfer rates, allowing for the efficient recovery of high-purity copper, even from low-concentration solutions (<5 g/L) and feeds containing mixed metals and contaminants.

This technology also assists in copper concentration control and electrolyte purification in copper refineries. As copper dissolves at the anode faster than it deposits onto the cathode, electrowinning cells play a crucial role in maintaining copper levels and removing impurities in a copper refinery tankhouse. The improved cell design in vortex electrowinning reduces working capital requirements, eliminates hazardous gas formation, and enhances impurity management, as seen in operations like those at Hindustan Copper Limited.

Precious Metal Recovery

High mass tansfer flow cells can also produce high-purity metal powders at high efficiceny for precious metals such as silver, gold, and palladium. These systems, designed for the recovery of metals from solutions with low metal concentrations, employ higher current densities and lower flow rates. Metal powders are automatically harvested through a flush process, optimizing recovery efficiency.

The closed design of these systems ensures greater security in precious metal recovery applications, reduces losses, and improves metallurgical accounting. In addition to precious metals, this technology is also employed for the production of specialty powders, including electrolytic copper and copper arsenide.

Nickel Recovery

Vortex electrowinning technology has also been applied in the recovery of high-purity nickel cathodes from various feed sources, including wastewater treatment sludges and spent nickel solutions. This method ensures high efficiency and purity in nickel recovery, making it suitable for multiple industrial applications. The enclosed design of the cell eliminates the formation of acid and nickel mist, contributing to safer working conditions.

In many cases, vortex electrowinning is combined with Ion Exchange (IX) or Solvent Extraction (SX) techniques to allow for the selective removal of nickel from different solutions or sludges. The nickel is then recovered as a high-purity cathode that may be sold commercially or recycled without additional refining. The process can be customized based on the feed stream’s composition and volume, offering flexibility in nickel recovery operations.

Summary

Vortex electrowinning technology provides advanced metal recovery solutions for a range of applications, including copper, silver, tin, nickel, and precious metal extraction. Key features of the technology include enhanced mass transfer rates and modular cell designs, which enable efficient recovery from low-concentration solutions. These systems offer an environmentally friendly and cost-effective option for industries seeking sustainable metal recovery methods.