The Chemical Precipitation on Mercury of the Gilmour – Young Process is a method that has been employed at the Santa Francisca Mine, Nicaragua. The ore contains a very large percentage of clay, the slimes amounting to 70 per cent, of the ore. The ore is crushed by a No. 5 Krupp ball mill through a 30-mesh sieve, and is charged into Boss pans, 4 feet in diameter, in 2-ton lots, with 100 gallons of water, so as to form a thick pulp. From two to six bottles of mercury are added, and circulation continued until the globules can be seen dispersed through the pulp, and then the required amount of cyanide. After running for two hours, 10 lbs. weight of mixed copper and zinc amalgam are added, and the pan run for four hours more. The gold is dissolved in the cyanide and precipitated by the zinc and copper, only 10 grains of gold per ton remaining in solution.
The pulp and solution are then discharged into a settler and diluted, and the mercury recovered in the ordinary way. The amalgam is used over again, and eventually a bullion 800 fine is obtained by retorting.
The power required for treating 50 tons per ….Read more