NEW BRUNSWICK — Ores from the Mount Pleasant mine belonging to Toronto-based Adex Mining respond well to gravity pre-concentration in metallurgical tests. The former mine 80 km south of Fredericton has two distance ore types: tungsten-molybdenum mineralization in the Fire Tower zone and tin-indium-zinc mineralization in the North zone.
The results of bench-scale gravity and flotation tests were used in the design of the proposed flowsheet. Batch tests combined with computer modeling indicated that a 25.6% WO3 concentrate can be made with a tungsten recovery rate of 83.3%. The findings also indicated that modifications to the flowsheet will be needed for the optimum production of tin concentrate.
Separately, Adex commissioned leaching tests on the tungsten gravity concentrate. In bench tests employing a bake/leach/single-stage autoclave process, tungsten recovery was in the range of 95% to 99%. The results will be used to assess the possibility of producing ammonium paratungstate, used in the production of tungsten carbide.
For three years in the mid-1980s, Billiton (now part of BHP Billiton) produced tungsten at Mount Pleasant. A few photos are posted at www.AdexMining.com.