Metallurgy and Processing
Gold mineralization of the Duparquet Project is associated with disseminated sulphides, mostly pyrite and lesser arsenopyrite. As the material is refractory, the selection of an oxidation method before the cyanidation of a flotation concentrate became necessary to improve and optimize the level of gold recovery. The consistency of the results obtained, combined with historical use of this technology elsewhere in the world over the last 30 years, led to the selection of the conventional pressure oxidation (POX) technology utilizing an autoclave as the preferred method of oxidation for the Duparquet Project.
This process uses sulphide oxidation at high pressure and temperatures, thereby speeding up the kinetics and allowing the reaction to be self-sustaining. The processing facilities will be located at Duparquet and include: crushing, grinding, gravity, flotation, pressure oxidation and carbon-in-pulp leaching (CIP). Metallurgical test work performed by SGS Lakefield indicates that the use of the pressure oxidation circuit prior to leaching improves the projected overall gold recoveries to 93.9 % for the mineralized material and 83.9 % for the tailings.
The PEA Study includes two distinct tailings impoundments. The preliminary designs for the tailings impoundments were prepared by Stavibel. (Click here to See Figure 1) Eighty two percent (82%) of the tailings containing low sulphide, low arsenic and no cyanide will be stored in a flotation thickened tailings pond that will ultimately represent an area of 340 hectares. The remaining 18% of the tailings, coming from the autoclave circuit, and containing a higher concentration of arsenic and sulphides, will be stored in a specifically designed impoundment, which will ultimately cover 107 hectares.
Additional Technical Information Related to the PEA Study
The Duparquet Property is comprised of the Beattie, Donchester, Central Duparquet and Dumico properties. The historic Beattie and Donchester underground production totalled 1.5M ounces of gold. The historical Beattie Mine site surface area will be cleaned up and the current buildings demolished and removed prior to the development of the open pit mining. The cost estimation of this work was estimated at $13M by Stavibel, and is part of the environmental capital costs.
Proposed Surface Infrastructure
The proposed mine infrastructure incorporates the following: (Click here to See Figure 1)
-- Crusher and mill complex, including a crushing, grinding, gravity, flotation, pressure oxidation, leaching circuit (CIP) and a refinery;-- Office and garage and associated services buildings;-- New electrical main line from the Hydro Quebec grid, site substation and site electrical distribution installations;-- Pit dewatering system, surface water management and water treatment plant;-- Access roads to the site and on site;
The waste rock dump will cover 160 hectares and reach a maximum height of 140 metres. The waste rock is not considered to be acid-generating or potentially metal leaching.
The low grade pile will cover 18 ha of land and will be built on impervious ground cover, and will be surrounded by a collection ditch to recover run-off water and to treat the water, if needed.