QUARTZ MINING.

Grey River Argus, Volume IX, Issue 721, 1 September 1870, Page 4

QUARTZ MINING.

The following particulars respecting the successful working of a miue in Victoria, with a very low yield per ton of quartz, are interesting, as showing what a small yield can be made to pay under favorable circumstances. As they are the result of the personal experience of a gentleman of high standing in Dnncdin, we can vouch for their accuracy. The economical working of quartz mines is a subject well worthy of study, and of far more importance than the discovery of fresh quartz reefs. We have already plenty of known auriferous leads ; the difficulty is to work them cheaply and efficiently. Several hints are given by our informant which might be useful in some circumstances, such for instance as that about the disposal of tailings ; and the details of the amalgamating process will be found of interest by those who have had little practical exneuiunce in quartz raining. The mine was situated about 15 miles from Ballarat, and was a large hill containing a great number of quartz veins mixed with " mullock ;" it had been very productive in the early days of gold mining, and hai beeu worked in very small claims, the shafts being at one time only a few feet apart on the line of the reef. When the surface veins had been pretty well worked out, the ground became very unsafe to work, and ultimately collapsed, and fell into one mass of quartz, pipelay, sandstone, &c, &c, which would not pay the individual miner to work. I then purchased all the claims at sums varying from LIOO to as high us LllOO in one case ; got proper machinery, and prepared to work the mine on a wholesale scale, taking everything as it came, which was supposed to contain gold. The machinery consisted of a battery of 18 stamps (3 to 6 each), on the patent revolving principle, each stamper weighing about 7 cwt, and making from 65 to 70 blow 3 per minute, with a fall of Gin at first, which gradually increases to about 11 in as the shoes with which the stampers were fitted wore down. The stamper boxes were of solid cast iron, with loose beds inside for the quartz to be crushed on. When those loose beds were worn hollow they were always thrown out, as the crushing surface was materially lessened if allowed to remain ; the same was done with the shoes on the stampers. The old castings were bought readily by the iron founders for re-casting. The motive power was a condensing steam engine of 25 horse power, and the motion was conveyed to the cam shaft direct by ratchet wheel and pinion. The amalgiting process was the most complete known at the time, viz., stationary tables with deep and shallow mercury ripples and copper plates, silvered and rubbed with amalgam, and blanket tables with a mercury trough at the end. Tho deep ripples had a division in the cenfre, which did not reach to the bottom by about two inches. Mercury was poured into those ripples until it reached about half an inch above the bottom of this division, consequently the crushed quartz and water had to force through, this body of mercury. Each table had two of those deep ripples. The blanket tables-were made with slight falls from one to another, each having three rows of green baize, on which any ; very fine gold was caught, which had escaped the tables. As in Victoria water is a very difficult thing to obtain for crushing purposes, the machinery had to be placed at a distance of 600 or 700 yarda from the mine, and about 200 feet below its level. A double line of rails was laid down between tho tnifxe and machinery in such a manner that the full truck pulled up the empty ohe ? the speed being regulated by a man on the top of the hill, who worked a powerful lever brake attached to a large grooved pulley that carried a half-inch wire rope, the ends of which were attached

to the trucks. Each truck contained from 20cwt. to 25cwt., and took three minutes to go down, and emptied itself into the feeding platform at the mill. Fuel for steam, in the shape of firewood, was abundant, and cost only the cutting and stacking. I will now describe the mode of operation, and will begin at the mine. The quartz, mullock, &c, were taken in a face ; a certain number of men were kept constantly breaking down, and another lot filling the trucks, one man and a horse took them to the starting point and let them down the incline, hooking on the empty truck, and bringing it to the face. The mine work occupied about ten men generally. The quartz was shot on to a platform , close to the back of the stamper boxes, and was there shovelled in by a feeder, who also smashed up any lumps of quartz which were too large to enter the boxes. I always considered that an attentive feeder put through much more quartz by keeping a thin layer under the stamps than the ordinary self-feeding process did. It was part of the engine-driver's duty every hour, before greasing the cams, &c, to put a small ladleful of quicksilver (about half a pound) into each stamper box, at the feeding spout ; this settled in the bottom of the box, and retained the gold as it was crushed out of the stone, besides keeping the silvered plates well coated on the tables, by particles of it escaping with the crushed quartz. A man was employed in front of the tables, whose duty it was to see that the ripples worked properly, to give notice if any gratings burst, and to wash blankets— the upper tier every hour, the second tier every two houra, and the third tier every three hours. The washings were collected every twelve hours, and put. into a revolving barrel containing about three hundredweight of mercury, where they remained revolving for nine hours. This mercury was retorted once a week, and usually contained about seven and a half to ten per cent of the finest particles of the gold which had escaped the silvered tables. The contents of the upper ripple on each table were scooped out every twentyfour hours and fresh mercury put ii ; it was then squeezed through a chamois skin, and the amalgam laid past till the end of the week, when the general cleanup took place. On Saturday, at "4 p.m., the batteries were stopped, and cleaning up commenced. The boxfs were first opened in two of the batteries, and the quartz, &c, cleaned out carefully, and put into and crushed in the third battery (each battery contained six stampers); then a gentle

flow of water was passed through all the boxes and over the tables, until the whole were cleanly washed out ; the loose beds were removed, and about 70 or 80 per cent, of the gold was found beaten in around and below them in the form of amalgam, caused by the silver put in every hour by the engine-driver. If the gold was rough, more was retained in the boxe3 ; if fine, -less. About 20 per cent, of the gold was found in the ripples and on the silver plates, and about 10 per cent, in the washing of the blankets. The whole of tho mercury used during the week was then retorted, which made it very pure for next week's work. The tailings —at one time a great nuisance — I managed to get rid of without cost, or much waste of water, by digging two deep pits,' with a sluice at the bottom. These were allowed to fill with the water and crushed quartz, and held about 25 tons of sand each. The water out of these pits passed over the top into large settling pits, and from thence back into the. dam, perfectly pure and clear ; and, when full of saud, the first pits emptied themselves behind the embankment of Ihe dam merely by the small quantity of water, which was held in suspension among the sand, on the sluice being lifted. The machinery being a good deal higher than the dam, enables the sand to have a considei'able fall. I will now give you an idea of the cost of working, &c. — the machinery going night and day — per week : — ■ 2 engine drivers, £4 ... ... £8 0 b 2 men feeding the stamper boxes, 50a ... 5 0 0 2 men at the amalgamating. tables, who relieved the ! others half-an-hour at meals, 45s 4 10 0 Wear and tear of machinery, oil, grease, &c, &c 20 0 0 15 cords firewood, 8s 6 0 0 10 men, at 40s ... 20 0 0 1 man and horse ... .. ... 4 0 0 Wear and tear of trucks, rails, ropes, &c, 4d per tou, 250 tons 4 3 4 Sundry incidental expenses, such as miners' tools, repairing, &c, 6s 5d per ton ... ..." 8 6 0 . , £80 0 4 or, with gold at 77s 6d per ounce, jusTa little over one and a-half pennyweight per ton. This will give you an idea what a small yield will pay under favorable circumstances as regards quantity of stone, and easily procured.