Flotation methods and machines

摘要

Flotation for gold in carbon fines~1 and some equipment developments.Commercial production at the Fort Knox mine near Fairbanks in Alaska commenced in the first quarter of 1997. Based on proven and probable reserves of 147 Mt of ore, averaging 0.85 g/t the mill is operated at 36,000 t/d, 365 days a year, with approximately 94 percent availability. The Fort Knox gold deposit is hosted by a multi-phase granitic body with an elongated surface exposure and extends to depths of over 300 m. The gold is contained in milky-white quartz stockwork veins and veinlets, as well as along shears and fractures, within the granites. The quartz-filled shears contains evenly distributed gold, generally less than 100 microns in size, while the gold in milky-white stockwork veins and veinlets is similar in size, but has a more erratic occurrence.The run-of-mine ore from open pit operation is crushed to minus 20 cm in a primary gyratory crusher near the pit before being conveyed for 0.9 km to a coarse ore stockpile at the mill site. The coarse ore is reclaimed from the stockpile and conveyed to a 10 m X 4.5 m SAG mill. The +12.5 mm SAG mill discharge fraction is crushed in a 2 m cone crusher and returned to the SAG mill. The -12.5 mm fraction proceeds to two, dosed circuit 6 m X 9 m ball mills operated in parallel. The final product from the grinding circuit is approximately 65 percent passing 0.15 mm.