EXTRAORDINARY YIELD OF GOLD BY DENNY AND ROBERTS’ NEW MECHANICAL PROCESS.

Kumara Times, Issue 1090, 29 March 1880, Page 4

EXTRAORDINARY YIELD OF GOLD BY DENNY AND ROBERTS’ NEW MECHANICAL PROCESS.

[BATHURST TIMES, MARCH 6, 1880 ] It has always been understood that gold associated with pyrites was held in chemical union, and that therefore the metal conld not be liberated except by first roasting it. It is well known that the tire process is an expensive way of recovering gold from pyrites, and thac in consequence many good reefs have been abandoned, To extract gold from pyrites by the last named process means a cost of two to three pounds per ton. We have a circular before us announcing that Denny and Roberts, of this city, ° have supplied the School of Mines, Ballarat, with one of their new machines, which will be employed in testing samples for the public. This machine will be worked under the management of the head of the institution, who will assay each sample before being operated upon by the patent machine, in order to give the miner an exact account of the amount of gold his tailings contained per ton ; so that the result obtained by the machine will indicate the exact percentage of gold it recovers when compared with the result by fire Jassay. The School of Mines management have gone to considerable trouble and expense in erecting this machine, because it will be an immense advantage to the mining public. The circular invites miners and mining companies in all parts of the colonies to forward samples of not less than one hundredweight, and not more than one ton, of tailings or blanketings for treatment. The charges will be strictly moderate, the object being to advance the mining interest, not to make a profit out of the trials. The first lot tried at the School of Mines was on Monday last, the result of which was telegraphed to Bathhurst the following day, as under : “One ton of concentrated pyrites from the South Clunes, treated by Denny and Robert’s new process, yielded 4 oz. 15 dwt, 10 gra. of gold.” A sample of this was assayed by the School of Mines before being operated on by the new machine and found to contain just 5 oz. of gold per ton. The machine therefore extracted 95 per cent, of the fire assay by a purely mechanical process, no scientific labor being necessary. It was not expected that a greater yield than from 60 to 70 per cent, would be obtained from the concentrated pyrites, ’ as it is much more difficult to extract gold from it than from ordinary tailings or blanketings ; therefore the extra ordinary result of 95 per cent very much astonished the Ballarat miners. 24 of new machines are now being manufactured at the Union Foundry, Ballarat, to be erected at St. Arnaud in the colony of Victoria. It is supposed that this plant will be completed and at work in five or six weeks from now, and within that it is expected that a number of mining plants will have one or more of the new machines attached to their batteries, A great demand has already set in for them. These machines are manufactured at the Union Foundry, Ballarat, only, where any infer, mation can be obtained respecting them ; or from Mr. Thomas Denny, Bathurst, or School of Mines, Ballarat. This machine will be found to be of immense value to prospectors, as the rotary grinder in the top pan is arranged to crush stone. Prospectors may take one of these machines and a portable engine and set them down to a new reef without going to any expense for foundations, sheds, &a, until after the reef is proved payable. What an amount of money would have been saved if this could have been done when the mining excitement was on ! Mining plants were put up in all parts of of the country at a coat of from five to ten thousand pounds each plant. From one to two years were lost in erecting these immense plants, and in connection with most of them, after working two or three weeks, it was discovered that the would not pay ; in some cases the reason being that the stone did not contain sufficient gold, and in other cases that the gold, being associated with base metals, conld not be extracted by crushing machine process. The prospector who tries his reef with one of Denny and Robert’s machines will not fail through the last mentioned cause : and should he fail from the first, why he has only to shift his machine—like the stem thresher —to the next stack of quartz.