Arizona republican., 1902-01-03
Mines and Minerals of Arizona

mill on Groom creek, six miles south of Prescott, has reached the acme Of per- lection, and probably eclipses any other plant of its kind in the successful treatment of gold ore. The whole equipment and system is complete in every detail, and after many expert ments and the expenditure of a great deal of money grand results have been attained.
 The mill consists of twenty stamps. Twenty-mesh screens are used and from thirty-fiVe to forty tons of ore are crushed every twenty four hours. An average of 74 per cent of the assay values is saved on the amalgamating plates. The pulp containing the re- mainder of the values IS conducted from the plates to a succession of twenty storage settling tanks, the con tents of the last tank into which 1t is drained being clear water, which is pumped back and reused in the anal gamating process.
 There are four cyanide tanks holding three tons of pulp each, and every two hours one of these is filled from the storage tanks. One-half of one per cent of cyanide is used to put the gold in solution, and the pulp is kept agi- tated by huge beaters, or paddles, which are kept constantly in motion, an eight-horse power electric generator being used for the purpose. As there are four of the cyanide tanks, and one of them charged every two hours, it will be seen that each charge is agi- tated for only eight hours. which is a remarkably short time for precipita- tion of the gold. However. the use of electricity in the precipitation is what accounts for it. The pulp is charged with lime, and salt is added before it is cyanided. The agitators are kept heated by steam and then a charge of electricity with a light voltage (9-75 amperes) is made. which precipitates the gold on amalgamated copper plates that are attached to the bottom of the tanks. Bars of iron form the positive pole of the electric current and the cop per plates on which thes gold is pre- cipitated constitute the negative pole. By ascertaining, through continual ex- pertinent. the amount of salt to be used. the voltage of electricity, and the many other things necessary to perfect the process the mana agement has ob- tained a system which saves 9T per cent of the values in the ore, the bases of which are an iron pyrite, and even lead is sometimes encountered in the ore though not in sufficient quantity to affect this process. The loss in the tailings does not exceed 40 cents a ton.
 A recent clean-up, after run of less than a month on S67 tons of ore result ed in saving of A per cent of the assay values by amalgamation and 2312 per cent by the electrolytic process in the cyanide tanks.
 This is certainly a remarkable show ing and speaks well for the capability Yp.a
 Over on Lynx creek, within two miles of the Empire, the Penn Gold Mining company is operating an extensive plant, but of an entirely different kind than the Empire, as the ore makes it exclusively concentrating proposi- tion. Thus is shown the contrast in the modus operandi of two great proper ties, situated so closely together, and yet the similarity in ultimate results; for both companies have made an un- qualified success, and each saves prac- tically all of the values in the ores, though by an entirely different process.
 Three forty-ton Huntington mills are used by the Penn company, and the ore is concentrated, ten tons r1to one. The concentrates run from $75 to s10C to the ton. and about twelve tons are shipped to the smelter daily. Nearly 95 per cent of the assay values . are saved with this process and plant. The ore from the mines carries sul- l phurets. chalcopyrites, galena, and some zinc. The values are principally in gold, though the ore also carries seven or eight ounces in silver.
 A new working shaft is now being
 sunk to q depth of 1000 feet on the property. About seventy men are en- | ployed by the Penn Gold company I which is composed of the same mer who are operating the now famous Oc- | tave mines, in the southern part of this | county. They are Pennsylvania capi- | talists.
 | J. T. PENDEGAST.