Hunter Bay Minerals has declared that the alluvial tailings bulk sampling program has been completed. The tailings location is in the Puruni and Mazaruni Mining Districts of Guyana within 14 scale mining and prospecting permits.
Gold produced from Hunter Bays alluvial tailings operations
At the Sourie permit, 4400 t of mineral from two tailing fans were processed in a wash plant, designed and built in-house. The produced quantity was 156 g of gold, which is equal to 0.1 g/m3 recovered grade
The wash plant has a design capability of 35m3/hr with 96% operational availability. A superior grade gold concentrate was obtained by the wash plant, which included neatly classified magnetite sand, gold grains, lesser ilmenite, minor quartz and a range of heavy minerals. Microscope analysis and bench-scale gravity tests of primary tailings material when compared to material obtained from the wash plant shows recovery of around 85% to 90% of gold grains more than 75µm was possible. A considerable percentage of gold grains between 50 and 75 µm were also obtained. It was not possible however, to recover famboidal pyrite coated-gold grains.
The wash plant concentrate was cleaned with the use of a spiral helix system as well as a magnetic separator in order to obtain an extremely high grade concentrate that was formed into a gold bar with more than 99% purity. It was noted from microscopic analysis of the tailings obtained during the concentrate cleaning process that less than 2% gold is lost.
The recovered grade of the large sample was lower than anticipated. Microscope study of the primary fan material indicates that framboidal pyrite forms widespread coatings surrounding the gold grains from samples obtained beneath the water table.
Since pyrite is extremely light (S.G.5.01) and gold is heavy (S.G. 19.35), pyrite-coated gold grains will have a specific gravity that cannot be made concentrated using gravity procedures.
Out of the 14 permits, Hunter Bay has finished bulk sampling within one permit on two fans. Hunter Bay is presently checking mining options for superior grade primary alluvial deposits that may be operated by the company alone or as a retained interest or joint venture.