QUARTZ MINING.

Westport Times, Volume IV, Issue 704, 30 August 1870, Page 2

QUARTZ MINING.

The following particulars respecting the successful working of a mine in Victoria appeared in the " Otago Daily Times" of the 15th, and are interesting as showing what a small yield can be made to pay uudcr favorable circumstances : Several hints are given by our informant which might be useful in some cireumslances, such for instance as that about the disposal of tailings; and the details of the amalgamating process will bo found of interest by those who havo bad little practical experience in quartz mining. The mine was situated about 15 miles from Ballarat, and was a hill containing a great number of quartz veins mixed with " mullock ;" it had been very produclive in the early days of gold mining, and bad been worked in very small claims, the shafts being at one time only a few feet apart on the lino 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, pipeclay, sandstone, &c., &c, which would not pay the individual miner to work. I then purchased all the claims at sums varying from £IOO to as high as £llOO 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 of 6 each), on the patent revolving principle, each stamper weighing about 7 cwt., and making from 65 to 70 blows per minute, with a fall of nine inches at first, which gradually increased to about 11 inches 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 condensed steam engine of 25 horse power, and the motion was conveyed to the cam shaft direct by ratchet wheel and pinion. The amalgamating 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. The deep ripples had a division in the centre, 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 tine 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 yards from the mine, and about 200 ft. below its level. A double line of rails was laid down between the mine and machinery in such a manner that the full truck pulled up the empty one, the speed being regulated by a man on the top of the bill, -who worked a powerful lever brake attached to a larged grooved pulley that carried a half inch wire rope, the ends of which were attached to the trucks. Each truck contained from 20 cwt. to 25 cwt., 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 to 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 thecrushed quartz. A man was employed in front of the tables, whose duty it was to see that the xipples worked properly, to give notice of any gratings burst, and to wash blankets—the upper tier every hour, the second tier every two hours, and the third tier every three hours. The washings were collected every twelve hours, and put into a revolving barrel containing about 3 cwt. mercury, where they remained revolving for nine hours. This mercury was retorted once a week, and usually contained about 7£ to 10 per cent, of the finest particles of gold which had escaped the silvered tables.

The contents of the upper ripple on each table were scooped out every 24 hours and fresh mercury put in ; it was then squeezed through a chamois skin, and the amalgam laid past till the end of the week, when the general clean-up took place. On Saturday, at 4 p.m., the batteries were stopped, and cleaning up commenced. The boxes 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 stamps); 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 to SO per cent, of the gold was found beaten in, around and below tliem in the form of amalgam, caused by the silver put in every hour by the engine-driver. If the gold was rough,

more waß retained in the boxes ; 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 the 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—l managed to get rid of without cost, or much waste of water, by digging two deep pits, with a sluice at 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, aud from thence back into the dam, perfectly pure and clear; and, when full of sand, the first pits emptied themselves behind the embankment of the 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 considerable 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 0 2 men feeding the stamper boxes 50s 5 0 0 2 men at the amalgamating tables ■who relieved the others half-an-hour at meals, 45s ... 410 0 Wear and tear of machinery, oil, grease, &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 ton, 250 tons 4 3 4 Sundry incidental expenses, such, as miners' tools, repairing, &c, 6s 5d per ton 8 6 8 £BO 0 0 or, with gold at 77s 6d per ounce, just a 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.