TREATMENT OF GOLD ORES.

Westport Times, Volume VI, Issue 962, 16 April 1872, Page 2

TREATMENT OF GOLD ORES.

Mr E. d'Henrease, of New York City, contributes the subjoined paper on the 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 Califoruian 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 late, that the human mind is apt to follow a well worn track, from which few only deviate. Amalgamation and concentration of the ores has 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 indifferent affinity of quicksilver for gold, secures on 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 10 dollars to 15 dollars per ton in ores yielding but 16 dollars to 25 dollars per ton is by no means rare. This demonstrates, as it has done many years ago to this writer, a Califernian miner of 1849, that we have to look for other means to avoid these losses. Of all substances known, zinc, in a melted state, has the greatest affinity for gold (and silver): instant contact suffices 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 instantly to the zinc, as anybody can easily convince himself. The ore pulverised dry, and the dry (or dried) ore or tailings passed gradually through a bath of melted zinc, yields upon an average, 80 to 90 per cent, of its auriferous contents, without loss of any float gold. All the 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 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' metals are separated from the zinc by retorting, or the known modes of dissolving the zinc by acids. No water, is required in the zinc process above explained, except for the use of the. engine, to reduce the ores, and that much is found even -in the barren Colorado desert without difficulty. This point is well worthy of consideration, for nine out of ten rich gold mines are now lying idle, entirely or part of the time, for want of water I required for the usual battery amalgamation works, while the sagebrush and l mesquite of the desert yield ample fuel j to raise steam aud to keep the «inc up ! to the required temperature—jusfj i above the melting point; and the value of the float gold saved is alone sufficient to cover the whole cost of i extraction by zinc.