ONTARIO – Gowest Gold of Toronto has completed testing of commercial scale, dual energy x-ray transmission (DEXRT) ore sorting equipment on ore from the Frankfield gold project 42 km northeast of Timmins and says this type of pre-treatment works well on mineralization from Frankfield East, and it has the potential to reduce both capital and operating costs at the project.
Reduced costs would be possible through mining lower cut-off grades, thus increasing overall ounces in the ground; using cheaper bulk mining methods; reduced haulage costs between the mine and mill; and capital and operating costs for ore sorting is cheaper than the alternatives.
Gowest said the DEXRT equipment effectively separates waste rock that makes up 50% or more of the total tonnage in crushed ore from the gold bearing materials. Head grades could effectively doubled from 6 g/t Au to 12 or 15 g/t Au. Gold losses will be minimal during sorting because the equipment has proven itself extremely effective.
The company explained the process thus: “Metallurgical testing has shown that the gold in the Frankfield East deposit is closely associated with arsenopyrite (FeAsS). During ore sorting, the crushed material is transferred at high speeds along a conveyor belt in front of an x-ray sensor that analyzes the signatures of individual rocks to detect the FeAsS content in the crushed ore. The sensors then trigger a series of individually controlled air jets to separate the barren rocks from the gold bearing material. Work to date has shown that the equipment used in Germany was able to detect arsenopyrite contents down to as little as 0.1-0.2%, a sufficiently low level to provide reliable operational control and ensure that as little of the economic gold as possible is sent to the waste stream. In essence, any rocks containing in excess of 0.3 g/t Au can be effectively recovered and sent for downstream processing while the remaining material remains at the mine as waste rock.”
For more information about the Frankfield project, see GowestGold.com.
Gus Van Weert
This sounds promising. Assume the mining cost of the ROM ore to be $60/ton, sorting costs at $15/ton, and one needs two tons head grade to produce one ton of “super” grade – into a truck or railway car – than that could be shipped to an arsenopyrite processor,say in Red Lake, say for $100/ton. Total delivered cost at Red Lake: $250/ton, contained value 12g gold at $50/g = $600/ton. With minimal environmental problems in such a scheme, I wonder what the capital cost of a DEXRT sorting plant might be?