Ore Dressing.

Te Aroha News, Volume VII, Issue 406, 28 September 1889, Page 2

Ore Dressing.

Ikqreased attention is being given ta the ntilsation of the lower class of ore* by means of the application of concentrating machinery to get rid of the Hxrey, material and bringing the metalliccontents into, a, stata in which ijhey can be smelted ov otherwise treated to a. profitable result. In all or nearly all mine 3, however good the bulk of the ore may be, there is a considerable, proportion which is of too low a grade to be either smelted on the. spot or exported to a profitable account. Indeed in most of -the mines in Europe, the. pro§,t coraeS: from tiie careful rea.iaation by dressing processes oF the. very least fraction, of valuable metal that can, be obtained from. • the second class ores.. N.o amount of attention, therefore. -' is too great to" ' bestow on the study of machinery suited, to effect the desired result. The large plants now at work on the. Proprietary mine, Block 14, and the Junction are evidences that the importance of th« subject is fully realised by the able gentlemen entrusted with the managempnt of these propei tics. The general principle adopted in all the abovementioned plants is approximately the pame, but there are differences in detail between the machinery at work on the Proprietary and Block 14, and that worked by the Ban-;- Concentrating Compaiy on the Junction mine property, and that at Thackaringa. Xn the big mine and Block ]4, the crushing (the first process) is effected by means of powerful stampers, of one head each, whilst in the other company's mine, the ore is first broken by a stone-breaker and then passed through several pairs of diagon^'V fluted rollers. This last system is supposed to produce a smalleramount of slimes, which are difficult to treat, consequently the smaller proportion of them produced so much the better. Affcer be : ; properly reduced by either of t'jea! xive systems the ore is submitted to the action of jiggers, in which, by* gravitation, the barren, silicious, or stony particles aie separated from the heavier metallic parts. After this comes in, another difference of treatment for the more slimy j crtions of the ore. In the Propriety and Block J4 a mode of treatment by buddies is adopted, whilst in the Barrici Company's works Frue, vanners are u~ed. At> to the results, obtained by t!."> dressing processes theynecessarily vaiy, to some extent, with* the nature of the oie, but they may be. given, roundly, that 3 tons of crude ore produce about one ton of concentrates., whilst, unl(»*s in the case of complicated, ores, the crude grades of lead and silverare increased to three times. For^ example, ] Ooz to 11 r>2 of silver in the. ciude oie will give 12 to 35 in the concen hates, and lend 16 to 17 per cent. in. the crude will be found to be 48 to 50, per cent in the concentrates. The importance of the process wili thus he seen, and it must be borne in mind that without the application of the dressing the low-c)as« stuff would be useless. In, such large mines us those on the Broken Hill there will be, when they are more fully developed, thousands of tons oJ ore per week which would be waste were it not for the dressing, and as such ore. must necessarily be raised along with the better class, it practically costs nothing «s a raw tuatenal, and all that is got out of it, less expense of dressing, is profit, and will make a substantial addition to the divi lends coming and to come from, the mines. — Silver Age,