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Mr. Jas. J. Shedlock, with the assistance of Mr. T. Denny, of Australia, has constructed on behalf of the Metallurgical Syndicate, of 105 Gresham House, London, an apparatus on a commercial scale, which, it is said, effects at the smallest expense, and with the best economical results, the entire separation of metals from their ores. In treating ores by this process, the stone is crushed in the usual way, either by rolls or stamps, the crushed ore being conveyed into an apparatus, where each atom is subjected to the action of gases under pressure, whereby the whole of the sulphur and other materials which render the ore refractory are separated. The ore is then conveyed into a vessel containing an absorbing fluid metal, so constructed that every particle of the ore is brought into contact with the metal. For the production of reducing gases, steam and air are passed through highly heated materials, having an affinity for oxygen, and the gases so produced are utilized for raising the ore to a high temperature. By this means the sulphur and other metalloids and base metals are volatilized and eliminated, and the gold in the ore is then in such a condition as to alloy itself or become amalgamated with the fluid metal with which it is brought into close contact. The tailings passing off, worthless, are conveyed to the dump.
The apparatus in the background is that in which the steam is generated, and which, in combination with the due proportion of atmospheric air, is first superheated in passing through the hearth or bed on which the fire is supported. The superheated steam and air under pressure are then forced through the fire, which is automatically maintained at a considerable depth, by which means the products of combustion are mainly hydrogen and carbonic oxide. These gases are then conveyed by means of the main and branch pipes to the cylindrical apparatus in the foreground, into which the ore to be acted upon is driven under pressure by means of the gases, which, being ignited, raise the ore to a high temperature. The ore is maintained in a state of violent agitation. Each particle being kept separate from its fellows is consequently very rapidly acted upon by the gases. The ore freed from its refractory constituents is then fed into a vessel containing the fluid metal, in which each particle of ore is separated from the others, and being acted upon by the fluid metal is absorbed into it, the tailings or refuse passing off freed from any gold which may have been in the ore.
[Illustration: APPARATUS FOR THE TREATMENT OF REFRACTORY ORES.]