EXTRACTION OF GOLD BY ZINC.

Westport Times, Volume III, Issue 445, 4 January 1869, Page 3

EXTRACTION OF GOLD BY ZINC.

(From the San Francisco Bulletin.) R. D'Heureuse of this city has just patented a process of extracting gold with zinc. His circulars, which are extensively circulated at the Fair, contain the following statements concerning his invention. He says :—" When we fairly examine the retentive faculty of quicksilver for gc d, we find it very limited indeed; that the affinity acts only on perfectly pure surface of both —a minority of cases, in reality—and that a reduction in temperature so greatly reduce* the affinity that it hardly exists below a temperature of of 45deg. Fahr. The result is that, on an average, only one - half, or thereabouts, of the gold is extracted by quicksilver from the ore; the rest is either carried away as float gold by the water required for the batteries, or remains in the tailings. This fact, known to every intelligent operator, should alone be sufficient to point out the imperative necessity of devising other extracting agents for that great majority of ore, containing more than 20 or 25 dols per ton ; but not rich enough to leave a profit by direct chlorination. Concentration of the sulphurets for chloiination involves a great loss in float gokL Many localities with rich quartz veins have

insufficient water for batteries within convenient distance, and for the greater part of the year the ore has to be hauled long distances, with a heavy expenditure, to a mill-site with water, or the mine must be abandoned and lie idle. Therefore, what is required is an extracting agent that does the work complete, cheaper than chlorine, and requiring no water to reduce the ore, except such as is needed for the engine. Zinc, of all substances in existence —cblorine not excepted —has the greatest affinity to gold. Its action, a melted state, on gold, is to instantaneously dissolve the same in any proportion. Its specific gravity (about 7) is sufficiently high to float all debris, not excepting sulphurets of iron, the companion of gold. It melts at a comparatively low temperature and requires but little heat to retain its melted state. It is sufficiently volatile to permit of retorting, as in the use of quicksilver, but by a covered surface and a temperature below a dark red heat, the loss by volafcisation and burning is hardly appreciable, while the metal is obtained at a low price and in any quantity required. Thuswehavein zinc a material manageable and the conditions required of a gold-extracting agent in a high degree—higher than any other known.

The process invented by him consists simply in gradually introducing the gold-bearing pulverised substance, below the surface, iuto a bath of meited zinc, which will immediately attack and dissolve nearly or every particle of gold, while the debris rises to the surface to be taken off. The mechanism is very simple and durable. Should sulphurets, in which particles of gold are so firmly imbedded as not to offer any contact even on the smallest point, prevent the extraction to such a degree that it will pay to work it over by concentration, roasting and chlorination, it may be done. But all gold lost in another manner, as float gold and much more, is certainb T alrea^"* 7 onvpi/l by the zinc. Dry crushers are to be used in preference.