EXTRACTION of GOLD from QUARTZ.

Cromwell Argus, Volume III, Issue 143, 6 August 1872, Page 5

EXTRACTION of GOLD from QUARTZ.

To Ihr F lltor of the. C’iiom wm.i, A nous. Sir, “Crusher” having completed his letters on the Management of Quartz Mines, —the arguments and s atements in which are for the most part incontrovertible,—has, in your issue of the 4!h June, given some of his ideas on gold-saving and quartz-crushing. W ith your permission, 1 will aider with him on some points. In the first place, during a lengthened experience, 1 never heard a quartz miner or crusher, when speaking of the paint gold alluded to by “ Crusher,” say it cannot be saved. Igo still further, and contend it can, and is, in as great a proportion as larger gold that can pass through the gratings. Some of the reasons why gold is lost from crushing-mills are the following ;—The gold, crush the ore tine as you will, is not all freed : that which is not freed, when it leaves the stamp-box, is inevitably lost ; if freed, it stands a chance of amalgamating on its passage over plates and ripples,—for lam of opinion it is next to an impossibility to pass over plates and ripples without coming into contact with mercury. When “Crasher” wrote that tiro gold was not able to sink through the water and pulverised quartz, he must have had a sluice-box, instead a ripple-table in his mind’s eye. Should the gold escape the ripple-table, the blankets still may pick it up. Fagged gold, outside the stamp-box, stands the leant chance of being saved. 1 think it scarcely necessary to point out the fact of water having far greater power over such gold than that which is smooth, even when thin : if gold is round, and freed from quartz, be it ever so true, it is safe. Tue use of sulphur, or anything of which sulphur is the principal constituent, is another great reason why gold is lost, —as this substance coats the gold, prevents amalgamation, and occasions extensive sickening of qn'cksilver. Could this be overcome, a large saving of gold would be the result. Calcining the quartz, as usually done in Victoria, is a benefit, as it destroys the sulphur ; and, if well burnt, renders ragged gold shotty, which, with all due deference to “Crusher,” makes it far easier saved.

Jt is, I believe, impossible, by any method of crushing where mercury is used to collect the gold, to save all, or nearly till. The different methods of applying the Chilian mill principle are undoubtedly the best that have yet been used ; but they are comparatively slow m their operation, require great power to Work them, and the expense 111 wear and tear is very considerable. Yet, with all tin se drawbacks, the Chilian mill could in mane instances be profitably employed. The berdan is also a good amalgamator, when the basin and balls are true ; but is st 11 slower, and requires the quartz to bo broken small, before putting it into the basin. Thearastra is another method; also good,— but yet slower : for this reason, that the quartz muse he pulverised. The amalgam-barrel is excellent, —but the slowest of all, and most troublesome. There arc, iu tins Province alone, millions of tons of material that would pay handsomely if operated on in the barrel.

Smelting tho quartz is most clfectnal, but the expense is considerable, not only for fuel and ilux, (quartz requiring its own weight of soda, or, if lime is used, a still greater quantity,) but a large amount of lime is required for a solvent, to collect the gold. Then comes the expense of cnpcllation. All these things considered, this process evidently would not answer for poor reefs. Where “ Crusher - ’ could have derived the notion of great loss of gold through evaporation is a mystery,— the evaporation of gold being hardly perceptible in the hottest furnace. I will mention a case of evaporation (I) that took place at Bendigo some fifteen or sixteen years ago. A storekeeper took a cake of amalgamated

gold to a well-known gold-melter on Sandh irst, leaving it with him to melt while ho tr >,nsac+ed his business. On calling back, he lo tad the loss something emmm us. Upon asking where »as the rest of the told, he was coo.iy iiiiormed txiat it went up the chimney. Piio s'.oivkcqer, noth ing a oehevtr in t..0 theory of gold evaporation on so extensive a scale, was incredulous ; so the affair end al in a lawsuit, the result of which I have forgotten. This is, 1 believe, the only instance of gold evaporation on record. “ Crusher” draws a comparison between the attraction of a magnet for iron, and of quicksilver for gold. In the one case, there is a positive force, calh.d magne tic attraction ; in the other, a chemical attraction or affinity, which is simply the tendency of one element to combine with another. “Crusher” speaks of a new era of prosperity being initiated if twenty per cent, mote gold comd be saved ; he should have added, at little or no greater cost (loss if possible) than the present system involves. It could hardly be considered an advantage, if, as at the Wicklow gold mines, it cost a pound to get nineteen shillings’ worth of gold. “ Crusher” has also made the startling announcement, tiiat water in a mine worked from a tunnel is an advantage ; as, quoting from his letter in j our issue of 2nd .1 uly, the cost of raising quartz in a dry claim, by such a method of working, is reduced to one half, —and if only a small trickle of water exists, yon can safely deduct another half. I believe, Mr Editor, two halves nuke one whole : consequently, in a Wet claim, worked from a tunnel, the cost of raising stone would be nil. He also states, that when he left Victoria, the idea of the capability of a Pleasant Creek in in to manage a qiurtz mine would be laughed at in such places as Ballarat, dunes, Bendigo, (tc. May 1 ask why I There are, and have been for'years, in that locality, as qnaljiiid miners and crushers as any in Victoria ; and the district, so far from being what he represents, has for several years, and until the late reefing revival at Sandhurst, b ‘“n the first quartz reefing district in that Column One claim alone paid in dividends, during a period of little over two years, the enornnns sum ox £103,212 Is. Od. 1 am, See., Stawell.