The cyanide is usually dissolved in a little water before being added to the stock solution, as the amount of KCy present is more easily determined in a strong solution than in any other form. A special dissolving vat of small size is often provided and is placed at a higher level than the large … Read more
Various gold bullion making methods have been suggested for effecting the elimination of the zinc and other base metals. The chief ones are: Direct fusion with fluxes. Roasting, followed by fusion. Treatment with sulphuric acid, followed by fusion. Lead fusion and cupellation (Tavener process). Volatilisation of the zinc, followed by fusion. Direct Fusion The method … Read more
There is one precipitation house and refinery common to all the leaching buildings. The method of precipitation is by zinc shavings, which, with slight modifications, answers admirably for all strengths of solution, the strong solutions ranging from .70 per cent. KCy to .25 per cent. KCy; the weak from .25 per cent. KCy to .10 … Read more
The strength of the cyanide solutions is tested by silver nitrate, using 10 c.c. of the strong and weak solutions respectively (diluted to about 100 c.c. with water) and taking 100 c.c. of wash-water undiluted. In each case a few drops of a 5 per cent, solution of potassium iodide are added. When the titration … Read more
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 … Read more
In the Siemens-Halske Electrical Precipitation process, the gold is deposited from solution by the passage through the liquid of a current of electricity. Moreover, as the precipitation is as readily obtained in extremely dilute cyanide solutions as in those containing 0.1 per cent, or more, very weak solutions are used in dissolving the gold from … Read more
Use of Cyanide in the Stamp Battery to treat the ore direct from the stamp milling battery instead of first passing it over amalgamated plates. Ore can be crushed with cyanide solution instead of water, and led at once into the filtering tanks. The results are stated to have shown that the coarse gold resisted the attack … Read more
Among other suggestions for rendering the presence of oxygen in cyanide solutions unnecessary, the most striking was The Sulman-Teed Process, who use cyanogen bromide, CNBr. The addition of this substance to a solution of potassium cyanide makes it much more rapid in dissolving gold. They put forward the equation: CyBr + 3KCy + 2Au = … Read more
The Merrill System or method or Zinc Dust Precipitation was introduced in 1897 at Marysville, Montana; in the plant of the Montana Mining Co., and subsequently at the Homestake Mine in South Dakota, where 130,000 tons of ore are treated per month and 4000 tons of solution precipitated every 24 hours. With very few exceptions this process … Read more
The Munktell Chlorination Process This method was devised by W. Munktell, who seems to have worked it out without having visited either the vat or the barrel chlorination works already established in other parts of the world. The process enjoys the distinction, according to the published accounts, of having been worked at a profit. It … Read more