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MEI Online: Hydrometallurgy: Latest News: January 15th 2004


:: Glow Discharge Plasma Technology  

Irving Blackman and Associates has announced a breakthrough technology, which they claim will purify mine waters, reduce or eliminate cyanide to recover gold or silver, eliminate the use of cyanide, roasters or autoclaves for refractory ores, and achieve recoveries of 95-99.5% while reducing processing costs.

For over 15 years scientists and research organisations throughout the world, including the US Department of Energy, have attempted to apply a 'Glow Discharge Plasma' technology to treat toxic or contaminated waters in order to destroy organic contaminants, and hopefully also separate out inorganic contaminants, such as heavy metals and radionuclides. The former Soviet Union was a leader in this research effort but with its break up, all government programmes in this area of research were left unfunded, and were thus abandoned.

Irving Backman reports that using the technology, contaminated water is treated in a reactor at ambient temperatures by a series of carefully timed, high voltage, electric discharges initiated above the fluid. A strong electric field is developed between unlike electrodes, some within the fluid phase and some within a gas phase. The electric field accelerates electrons in the non-thermal plasma, which is an electrically neutral gas that has very energetic electrons. The contaminated water is circulated in a falling film within the reactor. The fast moving electrons in the plasma collide with molecules in the gas above the water and on the water's surface. This activity breaks the molecules apart, forming reactive radicals and ions that destroy the organic contaminants and separate the inorganic.

Variations in the electric field generate 'Activated Water' a form of water that contains high energy and chemical effects, which can dramatically enhance other chemical reactions, or create its own chemical activity.

The 'Activated Water' is a catalyst that can enhance many chemical reactions by a factor of 40-50 times. Further, it can be continuously reused for at least 20 to 25 cycles without any loss of strength. As an example, a cyanide leaching process might require 72-82 hours for a 65% to 85% recovery of gold or silver. However, this same leaching process might be accomplished in three to four hours if Activated Water were substituted for river or rain water. Further, recoveries have been found to be in the 95% to 99.5% range when the leaching was performed with Activated Water.

However, of greater importance, similar gold recoveries of 95% to 99.5% were achieved from ore samples from Canada or the Western US with Activated Water alone, and without using any cyanide in the entire process. Of even greater importance, a refractory ore was also processed without cyanide but with a preliminary two-hour leach of Activated Water at ambient temperatures. Here too, the final recovery of precious metals from all ore samples was]in the area of 95% to 99.5%, and no cyanide, roasters or auroclaves were used to obtain such recoveries.

Although tests on copper, nickel, or other ores are not scheduled, Irving Backman and Associates believe similar high yield results with Activated Water will also soon follow.

Mr Backman says his firm is looking for an affiliation with a major mining or engineering company who could recognise the potential of this breakthrough technology to enable the mining industry to move into the 21st century, and enjoy the economic and environmental benefits that the Torch Technology might provide.




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