TREATMENT OF GOLD ORES.

Mount Ida Chronicle, Volume III, Issue 176, 19 July 1872, Page 512

TREATMENT OF GOLD ORES.

"jCrflM d'Herirease, of New' York City, - contributes the subjoined paper on ihe. professed improvement in the extraction \ of:-gold from its ores to the 'Scientific American':— , The' numerous discussions, on the imperfect manner in which quicksilver amalgamation performs the gold extraction of Colorado ores (and, for;.that matter, of CaHfornian and other gold ores in general), and the desire to discover means by which the amalgamation may; be improved, are but another illustration of the observation, frequently noticed in your pages'of that the human mind is apt to follow a well-worn track,' from which few only deviate. Amalgamation and concentration of the ores ha* been practised with gold ores for centuries, and it is erroneously taken for granted that these two modes should form the basis of operations, which ingenuity is taxed to. improve. It has been shown that amalgamation, by the in- . different, affinity of quicksilver for gold, secures on ah average,; only a little over, if at all, one-half of the gold contained in the ore. It is also proved that in the process of concentration the fine particles , of gold, flattened out exceedingly thin in the act of crushing the ores, are carried off in a large„ proportion as float gold by the stream of water used in concentration, as well as in battery amalgamation, and a proportion sometimes approaching nearly that secured by amalgamation ; for a float loss of "lOdols. to lodols. per ton in ores .yielding but 16dols. to 25d015. per ton'is by no means rare. This demonstrates, as it has done many "years ago to' this writer, a Californian miner of 1849, that we have % look tor other means to avoid these - .losses.- '■ ..Of all substances known, zinc, in a . state, has the greatest affinity for gold (and silver) : instant Contact suffices 1 -to" -dissolve even heavy particles of gold by forming an alloy. , Zinc does not combine directly with sulphur, but gold particles, covered with gold sulphuret and inert to the action of quicksilver, yield into the zinc, as anybody can easily IT- convffiee iXmself. The ere pulverised.dry, m and the ■ passed gradually th^i^h T i^4|^elted ■ zinc, yields upon aj^j3§mi'^«Snß& ■ ninety per cent. I without loss of any float" gold. I debris, even the iron sulphuret of the ore? [ is specifically lighter than the zinc : and ' the ore, introduced at the bottom of a deep . and narrow trough of melted.zinc, rises to tHe surface to be removed, leaving in its r passage the gold behind as an alloy, which can be tested at any time, and the amount .of gold in it determined with accuracy. When sufficiently rich, the precious inetais are separated from the zinc by retorting, or .the known, modes of dissolving the zinc by acids. "• No water is required in the fsineprdcess above explained, except for the use.of the engine,, to reduce the ores, .- and that much is: found even in the. barren Colorado, desertwithout difficulty. Tliis : P°^?^ w e]l worthy of consideration, for -■ i ni ?? 0 ?.° f . t^n nbhgold mines are now entirely or part of the-time, for ■- waniqf water required for the usual bat-tery-amalgamation- works; while thesagebrash. * aridj'mesquite of the desert yield «vl an sS'l f °?^l to *? ise st ? am and to keep the ~ B R *9 * ne required temperature—just ; abpye-the-melting point; and the value of the-float.gold saved, is alcne sufficient ~to coyer the whole cost of extraction bv * zinc. ■ * y) - i—-—L-L—, *