COPPER MINING

Wairarapa Times-Age, 24 February 1939, Page 9

COPPER MINING

IMPRESSIONS OF AUSTRALIAN INDUSTRY RECENT VISIT TO COBAR. AREA SUBJECT TO DROUGHT. An interesting survey of the famous copper mining district of Cobar. New South Wales, was given to a "TimesAge” representative by Mr A. McGregor.'of Tararua Street, Masterton. an ex-pupil of Wairarapa High School. Mr McGregor recently returned from Australia where he visited the mineral producing centres of New South Wales. Cobar, a small town of about 1500 population, said Mr McGregor, was situated 500 miles north-west of Sydney and formerly boasted a population of 10,000. No appreciable rainfall had been registered there for a period of three years. Water for general community purposes arrived daily by a special water train, which left Narrowmine, a distance of 160 miles away. Bourke, a town on the banks of the Darling River, was the only source now left from which the precious elixir could be obtained within a radius of 150 miles. On leaving Bourke, not a blade of grass could be seen for a distance of-100 miles. The vegetation was principally pepper trees and stunted desert shrubs. A frequent occurrence was to see stock collapse from lack of water and feed. On one occasion a cow was seen to eat newspapers and a discarded leg of mutton. Such a pitiful sight could only be seen to be credited. The hospital at Cobar. with an average of 35 patients, consumed and used for general-purposes water to the value of £2 per week, computed on the basis of 10s per 400 gallons freight charged by the railways. The temperatures during the year ranged from 90 degrees (in winter) to 125 degrees in the shade during mid-summer. This terrific heat was endured by the population without a murmur, and when a frost of 2 degrees occurred in winter the inhabitants complained of the intense cold. Although such places as Bourke, Wilcannia, White Cliffs and Nymagee were much further inland than Cobar, the conditions were not as severe, owing to the proximity of the Darling River. DUST EVERYWHERE. The geological strata of the country was most interesting, said Mr McGregor, and a variety of brick-reddish sandstone proved invaluable for paving purposes. A fine layer of rubble created fearful dust-storms, and at times the light of day was blotted out with swirling grains of red dust. After such an occurrence the housekeeper found a layer of dust everywhere to a depth of three inches or more. The dust, finding its way into the water tanks, was an almost intolerable burden until Condy’s crystals were used to clarify the water. The resultant flavour of the water did not leave a great deal to the imagination. Every summer trouble was experienced with snakes, and a fine skin of a length of 5 feet 6 inches was shown by Mr McGregor. When going out in rough ground, a razor and Condy’s crystals . were.. taken, and in the event of a snake bite, the wound is opened and washed with a solution before obtaining medical assistance. The health of the community in general was influenced by the prevailing conditions. High wages did not compensate for what was endured. Miners’ phthisis was a corrfmon complaint. Children usually suffered from an opthaelmic disorder, and cases of total blindness had been recorded. The terrific strain on the eyes, caused by the flat, reddish sand wastes and a scorching sun, day in and day out, were the contributory causes. The eyes seemed to have a marked difficulty in becoming acclimatised to the conditions. The excesses of the weather were remarkable, a feature being the beautiful but awe-inspiring lightning, which seemed to be attracted by the immense deposits of minerals. LOW LAND VALUES. The value of the country could be judged when a tract of 33,000 acres of land was offered recently for £lOOO, the lease extending over 42 years. The land averaged about 9d per acre and carried one sheep to 25 acres. Houses which rose with the “mushroom” growth towns were sold at ridiculous prices, often ranging from £l5 for a five-roomed house. Kangaroo skins were valuable products of this barren land, fetching up to 6s per skin. The skins were of a beautiful appearance, and were hard to identify when made up into coats, etc. METHODS OF PRODUCTION. Mr McGrego' brought back with him a fine collection of minerals from several mines. Last year, said Mr McGregor, the miscellaneous mines in Cobar were amalgamated by a firm controlling the New Occidental Gold Mine, and the mines were being closed down and worked systematically in single units. The methods of production in each of the mines controlled by the company were identical. The system used was‘known as the cyanide process. The depth between each level in the mines was 100 feet, to ensure safety against blasting repercussions. While working No. 2 level the ex- ; hausted No. 1 level was filled with debris, this being rammed in by a special machine. A huge shaft was sunk into the depths of the deposits, akin to a deep cutting in a hillside. Workmen were engaged in breaking off large deposits of rock, etc., which were used to replace the excavated levels. The filling-in method was continued when a new level was reached. At the present time the Fort Bourke mine was working at No. 6 level, and the New Occidental at No. 14 level. In the future the space between the levels would be worked. The ore was brought to the surface by ton cradles, and taken by railway to the crushing plant. Here it was crushed to a fine powder-like consistency, weighed and mixed with water. The muddy water ran along troughs past a machine which poured in specified quantities of cyanide crystals. This solution entered a tank, with a capacity of 1000 gallons, and was agitated for 36 hours, a chemical action taking place, thereby dissolving the gold into a liquid. The water was then filtered and sent to tanks in the gold room. Here the assaycr and his assistants treated the water with zinc, which turned the gold into a solid. The zinc and gold was then collected and separated. Under no circumstances were members of the staff or visitors permitted to enter the room. The powdered debris was tested time and again before being discarded. The yield of gold per ton averaged 30ozs. At the present time the net turnover of one of the mines was £40.000 for 28 days, representing over 50 per cent of the gold output for New South Wales. The fact that the

Broken Hill Proprietaries were reported to be closing down on March 14 would considerably affect the Cobar mines, which had now installed machinery capable of doubling the present output. It was estimated that the one at Cobar, worked at double the present man power, would last seven years. COPPER ORE ABUNDANT. Copper abounded in Cobar, said Mr McGregor. One very rich copper mine, the Gladstone, was at present closed down owing to the prohibitive costs of purifying the ore, which worked out at £45 to £5O per ton. Unfortunately the ruling market value of copper was at present only £34 per ton. An interesting point might be mentioned regarding a copper mine in Cobar known as the Great Cobar. The Great Cobar was one of the greatest mines Australia had ever known. The mine commenced operations in the early sixties as a copper mine, the ore being partially smelted on the premises. It was then shipped to Germany for final processing. The German firm was only too willing to undertake this work and re-exported the copper to the markets. After a period of 40 years a new assayer made the discovery that the semi-purified copper contained over lOozs of gold to the ton. The German firm thus accumulated an inestimable amount of bullion. Tests early last year revealed valuable gold deposits in the old mine, and operations would again commence this year. Wages were high, as surface labourers were paid £9 per fortnight, winchmen and engineers £23, miners £3O to £35, and "open cut” miners £45 to £5O. The mines were working 24 hours a day and seven days a week, by three shifts of eight hours each daily. Some miles away a miniature Rotorua was to be seen. Twenty-one years ago, a rich copper mine known as the A.V.C. caught fire in the smelting department, and the sulphur in the ore created an underground inferno. Samples of burnt ore taken from burnt-out sections showed the copper to be decomposed and nearly all the ! smelting process done by nature. j A sample of this ore, besides many interesting photographs, was exhibited at the Wairarapa College when an interesting talk was given on Wednesday by Mr McGregor to the more advanced pupils in chemistry.