In regards to the Arsenic contentN.A. Gem identifies new Louise Lake refining processes
2006-12-05 13:51 ET - News Release
Mr. Charles Desjardins reports
POTENTIAL ALTERNATIVE REFINING PROCESSES, MARKETS IDENTIFIED
FOR CONCENTRATE, LOUISE LAKE PROJECT
North American Gem Inc.'s independently retained consultants and related experts in the
field of base metal refining have identified numerous extraction techniques potentially
employable as alternatives to standard smelting techniques for concentrate from North
American Gem's Louise Lake deposit. This investigation was performed following results
of a metallurgical study completed by G&T Metallurgical Services of Kamloops, B.C.,
Canada.
North American Gem felt verification of the existence of potentially viable techniques
was necessary for recommencement of exploration on the Louise Lake copper-goldmolybdenum-
silver deposit, due to challenges provided by arsenic grades of 11.4 per cent
in concentrate. The road-accessible Louise Lake property is located 35 kilometres west of
Smithers, B.C., Canada, a full-service community with excellent access to highway, rail
and electrical power infrastructure.
One of the most promising extraction techniques is the CESL copper-gold extraction
process, developed by Cominco Engineering Services Ltd. Advantages of this process
include on-site processing, eliminating transportation charges, and modification of
arsenic to environmentally stable ferric arsenate (CESL website, 2006). Acceptable feed
ore minerals include chalcopyrite and enargite, the two copper minerals comprising
almost all copper mineralization at Louise Lake, as determined by G&T Metallurgical
Services.
Another potential technique is the Biocop bioleaching process developed by BHP Billiton
to treat ore containing chalcopyrite and enargite. The process has been shown to be
effective, with high copper recoveries.
A third potential treatment is total pressure oxidation, involving chemical oxidation of the
concentrate. The residue fixes arsenic as an iron-arsenic precipitate. A fourth technique
involves leaching of arsenic and antimony using high pH (strongly alkaline) solutions
which can selectively remove arsenic and antimony. The cost of reagents for this
particular process is very high; therefore viability will depend on metal value within the
deposit.
Various other copper leaching processes also exist, which deal with concentrates
containing chalcopyrite that may also be amenable to extraction of copper from enargite.
Viability of these will depend on rates of precious metal recoveries and quality of
residues. At least two standard smelters may also be amenable to concentrate from Louise
Lake, depending on volume submitted.
The findings of these investigations indicate that extraction techniques for high-arsenicbearing
ores exist, together with acceptable disposability of arsenic. Economic viability
will depend on costs of extraction and treatment, as well as typical mining, processing
and shipping expenditures.