A MOUNTAIN OF GOLD.
The Queenslander recently sent a special reporter to examine and report on Mount Morgan and the works — for it apparently cannot be termed gold-mining — being conducted by the lucky company who own this extraordinary mine. We make the following interesting extracts from his report : — As we enter the Company's property the mount is just ahead, and the Dee River is on our left hand. On its banks is a crushing mill, and ne.ar it are various other buildings containing machinery ani other requisites for working the mine. . . In front of the house, and between it and the crushing mill, was a large quantity of auriferous stone stacked ready to be put through. The quantity, Mr Hall, the manager, assures us,- was 25,000 tons, every stone of which had passed over the mine weighbridge. Close by the mill was a large quantity of tailings, estimated at 15,000 tons, for which an offer had just been received based upon a yield of 6oz per ton— this dirt containing, we were assured, just as much gold per ton as the stone stacked in i*s neighborhood. Here there were in all 40,000 tons of auriferous stone and dirt, containing 240,0000z of gold worth the unprecedented ly high value of L 4 4s lOd per ounce at the Sydney Mint. Here then was, in round numbers, just A MILLIOV OF MONEY ONLY "WAITING TO BE EXTRACTED from the stone and earth with which it was both mechanically and chem'cally combined. The stack has, I learn, since been increased to 60,000 tons. But how to extract the metal was the question which for years puzzled its fortunate owners. .They knaw by assay that il averaged 6oz, but by the ordinary crushing mill and tables they could onlyexract about 2oz ; and, as before stated, the tailing?, after crushing and washing, still assayed 6->z. But money, skill, and patience were courageously applied ; and said Mr Hall, "we now can extract over 98 per cent, of the gold in the stone and wasle no water. The water we use comes out, in fact, clear as crystal, much clearer and purer than we get it from our dam reservoir." The distance to the mount from the
mill is nearly a mile, and the reporter continues— "At length we came to the bottom of the shoot under which the drays stood, while their respective loads were shot in without hand labor. Going ft short distance further we reach tho first 'cut.' This was a siding quarried into the mountafn, whence the stone - was thrown into the shoot, and so passed into the dray with the least possible expenditure of human labor. There was no quartz reef here confined within walls, but the material was just quarried out of the mountain side and passed down as before described. About 100 ft higher was another cut, and then still higher was a quarry on the very crown of the mount, a great portion of which has been already removed. Here, too, we saw another heap of stacked stone, which our guide valued.at L 20.000 as it stood. Of course we examined the stone as it was being shovelled out, and saw plenty of color fnit, although; the gold being fine it was less visible than coarser gold is in much poorer stone. But seeing what we did we were quite prepared to accept Mr Hall's assurance that it yielded , from soz to 7oz to the ton.'' The crushing machine before mentioned stands at an elevation of 705 ft above the' sea level ; the dray road ascends some 300 ft, and from thence to the mountain top about 220 ft, or at a height of 1,225 ft above the sea level, the shoots are available. « It was impossible, as we stood on this elevation and watched the ease with which 50 tons of stone a-day waa quarried and passed over the weighbridge, not to contrast the process here with the difficulty and expense of getting loz to 3oz stone up from a depth of 200 ft to I,oooft at Gympie or Charters Towers. On reference to" the report of the Queensland Government surveyor, Mr Robert L. Jack, it will be seen that in the " central portion of the upper cu'ilting is a large mas 3of brown hematite ironstone, generally in great blocks (up to'some tons in weight), with a stalactite structure, as if the iron oxide had gradually filled up cavities left in *he original deposit. . . Gradually to the right and left of the central mass the silica more and more replaces the ironstone. It is a frothy, spongy, or cellular cinter, sometimes so light from the entanglement of air In its pores that it floats on the water-like pumice. Fine gold ia disseminated through this silicious deposit as well, as, in the ironstone. Near the west end ofjthe - cutting is a vertical dyke of kaolin mixed: ' with fine silicious granules, passing into ; \ pure kaolin, with Borne silicates of magnesia, including a fine, variety of French chalk." From this cutting Mr Jack selected some specimens, which being assayed at Brisbane yielded from soz3dwtto lOoz 14dwt of gold per ton, Mr Jack found the lower face to consist of brown hematite, aluminous ironstone, red hematite, etc., four samples of which being assayed yielded from 3oz 6dwt to 6oz 16dwt per ton. The latest development is a drive of 136 ft towards the freehold through soft chalky material formerly sup- % posed- to be almost valueless, but now/j found to contain from soz to 30oz gold t^ the ton. Having "done" the mountain, we de" 1 scended, and were taken through theworks ' Entering a large shed, open at all sides, we were quickly seized with a choking sensa" tion, caused, we learnt, by the inevitable escape of chlorine gas. The effect" of. this' gas is overpowering to the visitor, ami to the workmen, especially those with «eak chest?, it is exceedingly trying, oftettj, in *: fact, causing severe cough with bleedingfct",. the lungs. Iv this shed is a roasting fur- " nace, into which is placed the stone from the mill after being dry crushed. Here, after roasting, thematerial is wheeledacross theshedand then tipped intohoppersplaced above barrels revolving upon a shaft. Of these barrels there were, at the time of my vißit, four made of wood in full work, and ten of iron in course of erection. Along with the " dirt " is placed in the barrels chloride of lime, sulphuric acid, and water, which f orm'chlorine gas, and thus, agitated by being slowly revolved for about two hours; separates the gold from the dirt, and puts it into solution in the water. The contents are then run off into the " leeching vats" below, from which the dirt, which now contains less than 2 per cent, of the gold originally in the stone, is thrown away. The water containing the gold in solution, on being run Into a phial, and held up to the light, has a yellowish tinge, but is perfectly clear and transparent. Our guide, to illusstrate the process of precipitation, poured 'into the liquid a few drops of sulphate of iron, which quickly caused the gold to sink, and the water to become colorless and clear as crystal. This precipitation was only an experiment for our benefit, however. In practice the liquid is run Into filter beds formed of charcoal, which arrests the gold and allows the water to pass off in a pure state, and perfectly fit to be used again. The charcoal is next removed to another furnace, where it goes into the smelting pots, whence the gold comes out, as before stated, of the mint value of L 4 4s lOd per ounce. THE CHLORINATION PROCESS adopted at Mount Morgan is a modification of that developed by Mr Cosmo Newbnry and Mr Claude Vautin, of Melbourne. But as used by those gentlemen the process was hardly beyond the experimental stage,- and but for- thejngenuity and perseverance of Mr Wesley Hall it would not have been an unqualified success at Mount Morgan. In proof of this statement it may be mentioned that a new plant, with ten iron barrel?, each of a larger size than the wooden ones in use, was procured at Fulton's foundry, in Victoria, and after occupying a whole year in being fitted up at Mount Morgan was attended with the most disappointing results. Five months ago it was expected that with the aid of this plant the production of gold would be at once trebled ; but - after many triaTs the iron barrels have • proved a failure. The chlorine gas rapicHy corrodes iron and every other metal except lead ; and the experiment has been made of lining the iron barrels with lead, but of necessity there was a solder seam and this the gas quickly penetrated and rendered the barrels useless. A further experiment is now being tried with linings of cast lead, but its success is doubtful, and it is deemed . not at all improbable that wooden barrels will have to be reverted to. But even these have the slight disadvantage that after a few months use the wood becomes permeated with gold, and the barrels have io be destroyed to get the metal out. With these, however, the chlorination system is an undoubted practical success, and there in no longer reason to doubt that the company has at length, utilised a perfect and comparatively inexpensive system of extracting the gold from the stone*
The attainment of thia satisfactory icsult has, however, been a work of yoara, and involved anxious toil and very heavy expense. Tbe company have had all kinds of machinery projects before them for utilising the property, bnt one after another they had to be abandoned. At first the oi linaiy crushing mill with mercury tables was used ; but the scarcity of water and cost of getting rations and supplies over Razorb-ick were so prohibitory that it was determined to construct a railway from the mine to the nearest accessible point of the Central Railway, the idea being to crush the ore at Rockhampton. But the evident loss in the tailings of gold chemically combined with the stone led the company to make experiments with other processes. They got up several Berdan pans, but finding that gold was still lost, thay abandoned these and adopted Wheeler's pans. These did fairly well at first, but were in turn abandoned as defective. Chlorination by means of Lymburner's process with the assistance of Dr Benson, of Gympie, was next tried, but only 60 per cent, of the gold could be recovered by this means. Then resort was had to roasting and chlorinr-iion by the Newberry and Vautin process ; but even that, until Mr Weßley Hall added the air-suction pump and made other improvements in the manipulation, was not a complete succb's. Next came the drought, and the Dee River becamo a dry bed for many months, with not water enough in its bed to work a crashing mill. Then two large concrete dams were made across the river, in one of which a temporary supply of water was first obtained six months ago. So, what with the inaccessibleness of their mine, the enormous expense of getting machinery upon it, the saarcity of water, the refractory nature of the ore, the company have been put to enormous expense and heart-breaking delays. But as throughout the mine has not only paid its own way but also retmaed some handsome dividends notwithstanding all drawbinks, it may be ?«sumed that now all difficulties have been surmounted the most sanguine expectations of its proprietors will soon be realised. The company's plant, when in full work, will be shortly equal to the treatment of 700 tons per week, which, at soz to the ton, means &500oz gold, or a cash yield of L 14.800 per week. Moreover It has been determined to erect a new plant at a cost of L 60.000 In the freehold on the mountain itself, as water- for the chlorination can now be easily pumped up, with the view to treat 2,000 tons of stone per week. These are stupendous figures, but they are given by practical men, and if only onehalf realised will have an amazing effect upon the prosperity of the colony.
(See fourth page.)
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A MOUNTAIN OF GOLD., Grey River Argus, Volume XXXIV, Issue 5790, 11 January 1887
A MOUNTAIN OF GOLD. Grey River Argus, Volume XXXIV, Issue 5790, 11 January 1887
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