Draft:Great Cobar mine

Great Cobar mine was a copper mine, at Cobar, New South Wales, Australia, that also produced significant amounts of gold and silver. It operated between 1871 and 1919. Over that period, it was operated by five entities; Cobar Mine (1871-1875); Great Cobar Copper-Mining Company (1876-1889), Great Cobar Mining Syndicate (1894-1906), Great Cobar Limited (1906-1914), and finally the receiver representing the debentures holders of Great Cobar Limited (1916-1919). Its operations eventually included mines and smelters, at Cobar, an electrolytic copper refinery, coal mine and coke works, at Lithgow, and a coal mine and coke works at Rix's Creek near Singleton.

History

Discovery

In the winter of 1870, three well and bore sinkers, Hartman, Campbell (a.k.a. Kempf) and Gibb, with two Aboriginal guides, 'Boney' and 'Frank', were heading south, following a route between waterholes that were known to the guides. Camping overnight at the Kuppar waterhole, 100 miles south of Bourke, they noticed blue and green streaks in rocks near the waterhole. They took samples, from an outcrop of what was later the Great Cobar lode. At Gilgunnia, they showed those samples to Sidwell Kruge—a woman of Cornish origin, previously residing in the South Australian copper-mining town of Burra—who identified the ores as containing copper. Sidwell's husband Henry Kruge, smelted some of the ore samples in a blacksmith's forge to prove beyond doubt that the ore contained copper.

Cobar Mine (1871-1875)

The first owners of the mine were the three discoverers and four men from Bourke, Joseph Becker, William Bradley, Russell Barton and James Smith.

The owners brought Thomas Lean in to manage the venture. He was an experienced mine captain from South Australia's 'copper triangle'. Impressed with the deposit, he brought experienced copper miners, from South Australia, and sunk two shafts (Becker shaft and Barton shaft, 600 feet to the south). The rich ore (30% copper) was taken to Louth to await transport by riverboat, to smelters in South Australia, when water depth allowed it. Lower grade ore (15% copper) was stockpiled at the mine, pending the erection of smelters. Six reverberatory furnaces were constructed, two in 1875 and another four in 1876.

After the initial discovery, from 1870 to 1873, other prospectors made other discoveries in the area, including those that became the North Cobar and South Cobar mines, as well as the deposit to the north, the C.S.A. mine, and to the south in the area that would later become Wrightville. The township of Cobar began to become a more permanent settlement.

<<<Did they have a business name?>>>>

Great Cobar Copper-Mining Company (1876 - 1889)

At the end of 1875, the Cobar and South Cobar companies were amalgamated into one entity, which was registered as the Great Cobar Copper-Mining Company in January 1876, aiming to expand the mine and lift production. In 1877, James Dunstan was appointed as the manager of the newly amalgamated Great Cobar operation.Two more reverberatory furnaces were erected in 1878.

The difficulties of Cobar's remote location and its semi-arid environment soon became apparent. The furnaces required vast amounts of wood as fuel. The absence of rainfall also meant that residents of Cobar sometimes needed to buy their water, which came from other areas by the tank load. Copper was being shipped from Bourke, only when water levels in the Darling would allow steamboats to come up the Darling River.

In 1879, the mine began to use a narrow-gauge tramway to move ore from the mine to the furnaces. During the early 1880s, a second tramway network was commenced, to bring firewood from further away, but was only officially authorised in 1884. The plants fourteen furnaces consumed 70,000 tons of firewood annually, of which 62,000 tons came via the tramway and the remaining 8,000 tons by bullock drays. By 1889, the tramway extended to the east and south-east, allowing access to large stands of trees.

As the Great Cobar mine followed the copper lodes deeper, it produced more sulphide ore. Dunstan introduced open-air ore roasting, in 1883. The sulphide ore was roasted in open heaps, placed atop a layer of wood that was then fired. The roasting process drove off the sulphur as noxious sulphur dioxide fumes, leaving behind oxides of copper. The roasting heaps were situated south-east of Cobar township, so that the fumes would generally be blown away from the town.

A metallurgical engineer, Claude Vautin, demonstrated a water jacket furnace and convertor to the company, in 1884. Sulphide ores did not need prior roasting, when smelted in such a furnace. However, such furnaces needed coke. With the closest railway being at Nyngan, the road freight cost of moving coke from there to Cobar, made water jacket furnaces uneconomic.

The wild copper price fluctuations of 1887 to 1889.

In 1885, James Dunstan was replaced as manager by R.N. Williams. Copper prices were falling and costs needed to be reigned in to keep the operation profitable. Further, years of firewood harvesting was beginning to denude the plains in a wide area surrounding Cobar. It became clear that Cobar would become non-competitive, if it did not have a railway connection, allowing coke to be brought in economically. The Nyngan to Cobar Railway Bill was passed in 1886, but the railway was still some years away. Another railway act was passed, in 1890, actually authorising work on the railway to commence.

The temporary increase in copper prices in 1888—Pierre-Eugène Secrétan, manager of Société des Métaux attempted to manipulate the international copper market in that year—was not sufficient to keep the mine working, once the copper price collapsed in 1889. The mine was idle from August 1889.

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  Miners working on a 70 foot wide lode.
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  Copper mine and tramway, c.1890.
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  Copper smelter c.1892. The building at the rear contains the reverberatory furnaces.

Great Cobar Mining Syndicate and Growth (1894-1906)

Three of the Great Cobar Mining Syndicate (c.1901). Left to right: William Longworth, Dr Richard Read, and Thomas Longworth

The next phase of the mine's development is associated with two brothers, William Longworth (1846—1928) and Thomas Longworth (1857—1927) and their syndicate partners, in particular Dr Richard Read (c.1848—1920).

After the death of their father in a mining accident, in 1884, the two Longworth brothers became joint owners of a small coal mine at Rix's Creek, near Singleton, in the Upper Hunter Valley. Their neighbour was Dr Richard Read, a Singleton medical practitioner, who also owned another small coal mine. Originally, fierce competitors, they joined forces after Read, won a contract but could not mine enough coal to supply it.

Taking an additional partner, Albert Gould, they expanded their coal mines and built coke ovens, under the business name of the Singleton Coal and Coke Company. Around 1890, the partners became interested in the then idle Great Cobar mine, initially as an outlet for their coke, retaining as their advisor the mine's ex-manager, James Dunstan. Dunstan had been mine manager at the time of the successful demonstration of a water jacket furnace and convertor at Cobar, in 1884.

The completion of a railway line to Cobar in 1892, made it feasible to bring coke from Rix's Creek to Cobar. Coke would allow use of water jacket furnaces, a type of blast furnace used for non-ferrous metal smelting, in place of the less efficient, hitherto wood-fuelled reverberatory furnaces that had been used up to that time at Cobar. The change would reduce costs and be critical to unlocking the potential of the mine, even at lower prevailing copper prices.

The partners began negotiations to operate the mine on tribute and, with Albert Dangar and W. W. Robinson, the Longworths' brother in law, formed the Great Cobar Copper Mining Syndicate in 1894. The syndicate was sometimes referred to as 'the Longworth syndicate' or 'the Read-Longworth syndicate'. Thomas Longworth relocated to Cobar to manage the operations there, which by 1898, included five water jacket furnaces.

The Great Cobar ore included significant amounts of gold and silver. The syndicate established an electrolytic copper refinery at Lithgow, in 1899, which allowed the precious metal content to be recovered, while simultaneously upgrading the crude copper produced at the Cobar smelters. William Longworth took charge of this part of the venture, together with the Great Cobar colliery, which was established to supply the refinery with coal to generate the electricity it needed.

While the mine was being worked on tribute by the syndicate, the Great Cobar Copper Mining Company was receiving a royalty payment, which it used to pay a modest dividend to its shareholders.

By 1900, with copper prices at £70 per ton, and an additional £7 to £20 per ton from the recovered gold, the syndicate was able to buy the mine outright, eliminating the £15 per ton being paid to the original lessees under the tribute mining agreement. From 1900, William and Thomas Longworth alternated as manager at Cobar.

In 1897, a short standard gauge branch line, the Copper Mine Branch, allowed coke to be brought directly to the smelter site, and the crude copper to be loaded for Lithgow. In 1901, a longer branch line was opened, from a junction on the Copper Mine Branch near Cobar to the Occidental Mine at Wrightville. Called the Peak Branch, it would never be extended to the Peak mine, as was originally planned. The branch had sidings at the Great Cobar mine (the rest of the old Copper Mine Branch) and Chesney Mine, allowing ore from the Chesney Mine to be carried to the Great Cobar smelters more readily.

The Federation Drought badly affected Cobar. To prevent the closing of the operations and 600 men losing their jobs, the syndicate persuaded the railway commissioners to supply water by train from Warren, on Macquarie River, during the worst seven months of 1902, and to reduce rail freight rates when copper prices fell in 1903.

In 1904, the syndicate bought the Chesney Mine—initially a gold mine but, as the depth increased, increasingly a copper mine—and they had owned the Nymagee Copper Mine, since 1896, and the Peak Gold Mine, since at latest 1898.

William Longworth retired as the managing director of the syndicate in early 1905, and his replacement in that role was Dr Richard Read.

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  Miners working a 70 foot wide lode, c.1899.
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  Smelter workers at 80 ton water jacket furnace, c.1899.
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  Copper refinery at Lithgow, c.1899.

George Blakemore

In 1901, George Blakemore became mine manager of the Great Cobar Mine, and became its general manager in 1905. He would remain its general manager, until early 1909.

His career began in Broken Hill, in 1888. He was then in charge of the erection and operation of the plant of the Smelting Company of Australia, at Dapto, until 1898. He later was in charge of gold mines at Gundagai, N.S.W., and Einasleigh Copper Mine in Queensland. In 1901, George Blackmore became mine manager of the Great Cobar Mine, later becoming its general manager, in 1905.

Directors of C.S.A. Mines Limited, c.1912. George Blakemore is seated in the centre. From 1905 to 1909, the general manager of Great Cobar; by 1916, he had become its nemesis.

In the last years of the Great Cobar's ownership by the Great Cobar Mining Syndicate, there were reports of attempts to sell the Great Cobar, but no sale was completed. If such a sale were to take place, the rewards for the Great Cobar Mining Syndicate members would be immense. It was well known that the syndicate intended to sell the Great Cobar.

In 1905, Blakemore, probably attempting to emulate the success of the Great Cobar Mining Syndicate, established the C.S.A. Development Syndicate, to take over the then moribund C.S.A. Mine.

Exploration work at the C.S.A. Mine soon revealed a sizable lead-zinc deposit, and a new company C.S.A. Mines Limited was floated. The members of the C.S.A. Development Syndicate, including Blakemore received a large proportion of the shares in the new company. Blakemore was a director of that new company's board, and another member of that first board was Dr Richard Read, a member of the Great Cobar Mining Syndicate.

In late 1910, a large lode of copper ore was identified in the C.S.A. Mine. It joined with the neighbouring Tinto Mine, in 1912, emerging for the first time as a major mine in the Cobar region.

Sale and aftermath

In 1906, the syndicate sold to an English firm, Great Cobar Ltd, for £1,006,000, of which £800,000 was in cash that was divided among the six principals. The sale did not include the Nymagee Copper Mine, which was sold to other English investors in 1907. Also in 1906, the original owner of the Great Cobar, the old Cobar Copper-Mining Company, completed its liquidation and winding up.

The principals of the syndicate then set up Australian Woollen Mills, in 1908, and made a second fortune, especially by making khaki uniforms for the Australian Army during the First World War. Thomas Longworth was the chairman and William Longworth was a director. All the principals became very wealthy by the standards of their day. At their deaths, the estates of both Longworth brothers and of Albert Dangar each were in excess of £300,000, and that of Dr Richard Read over £136,000.

Thomas Longworth bought Woollahrah House, a very large estate on land now comprising some of the most desirable harbourside real estate in Sydney's Eastern Suburbs. He lived there until his death in 1927, after which the house was demolished and the land was sub-divided. The gatehouse of the estate survives, as Rose Bay police station. One of his sons was William (Bill) Longworth (1892–1969), later a prominent businessman, but as a young man a competitive swimmer who completed at the 1912 Olympic Games (qualifying for but missing the 100m final and 1500m semi-finals due to illness). He was an early exponent of the freestyle swimming technique known as the 'Australian crawl'.

Both brothers owned steam yachts. Thomas's was Cobar, and William's was Ena, which survives as a rare example of this type of vessel.

Great Cobar Limited (1906 - 1914)

New owners

In the two decades prior to the outbreak of the First World War, British investors were seeking opportunities, outside the United Kingdom. The purchase of the Great Cobar was one of a number of large investments made in Australia, which involved purchase of existing assets, with the aim of improving or expanding those assets. Such investments, in New South Wales, included British Australian Oil Company, Commonwealth Oil Corporation, Mount Boppy Gold Mine, and the Prince of Wales Mine. A few, such as the Sons of Gwalia mine in Western Australia, were long-lived, fabulous earners, and others like the Mount Boppy were highly remunerative. However, some eventually were unsuccessful, and some were also heavily over-capitalised; both would be the case for the new company, Great Cobar Limited.

The company was registered in England, in 1906, to take over the assets of the Great Cobar Mining Syndicate. 150,000 new £5 shares and £750,000 in 6% debentures were authorised, being new share capital and debenture debt in a capital structure totalling £1,500,000; not all of this amount was issued at the time.

On 15 May 1906, the promoters of the new company bought assets from the Great Cobar Mining Syndicate, for £800,000, in cash. The assets acquired included the refinery at Lithgow, the coal mine and coke works at Rix's Creek (near Singleton), the Chesney Mine (south of Cobar, at Wrightville), the Peak Gold mine (south of Wrightville), and the Conqueror Gold Mine (a small mine, due east of the Peak and south-east from Cobar), but not the Nymagee Copper Mine, which later would be bought by different English investors.

The assets were then sold into the float of Great Cobar, at a valuation of £1,000,000, including a payment to the promoters of £800,000 in cash, with the rest in new shares, resulting in a profit for the company's promoters of £200,000, in just six days. In the early days of the company, effective dilution of value was of no concern to its shareholders, as the share price soon reached £11, and the company briefly had a market value of over £2,000,000. In 1907, the company paid shareholders a 15% dividend totalling £112,000; by the next year, the directors regretted that they had not retained it, as the costs of the new plant began to be incurred. Reportedly, within three months of paying the dividend, the company's balance sheet was in the red, by £24,000. It would be the company's first and last dividend to its shareholders.

Even at the time of the floating of the new company, the large cash payment to the vendors, the Great Cobar Mining Syndicate, raised concerns. If the mine had such good prospects, it seemed illogical that the syndicate would not retain an interest by taking some of the payment in shares in the new company. The no-risk profits made by the new company's promoters, at the time of the float, were also of concern. However, although it was unforeseen at the time, the large issue of debentures would come to burden the venture and—despite its becoming profitable, in terms of gross profit—would reduce net profits and preclude payment of dividends to shareholders.

Mechanisation, expansion, finances and new capital

Having to pay interest on the debentures, at very least, the new company needed to both increase production and constrain costs; the path to profitability lay through a large expansion in capacity and intensive mechanisation. However, neither could be achieved, without massive capital expenditure. Great Cobar was to become a vast modern industrial undertaking, in a remote location.

The general manager of the mine, under syndicate ownership, George Blakemore, already had ideas about how the mine and smelter should be developed. The company sent out from England its consulting engineer, John Kendall, and he too had ideas on the future expansion.

Great Cobar, smelter (left) and main mine shaft (right), June 1912.

Kendall confirmed the board's confidence in Blakemore, and he remained the general manager under the new ownership, but Kendall would be responsible for the design of the new plant. With shareholders impatient to receive a return, the two would work together, to speedily erect and commission a massive new plant, expected to cost £160,000.

The new works were centred around a new main mine shaft, which Blakemore had already began to have sunk in 1903. In 1907-1908, a huge new steel framed building and a new steel headframe, for the main shaft, were erected. Then there was the rest of the new equipment; winding engines, two gyratory crushers, three water jacket furnaces and three Bessemer convertors, and their blowers, together with two electric locomotives, slag pot wagons, two electric overhead gantry cranes (one 20 ton and one 40 ton), steel plate conveyors, and a massive new power station to supply the site with electricity and compressed air. There was a new system of standard gauge railways in the plant, with overhead wiring for the electric locomotives.

Site of the magazine, after the explosion (Feb. 1908)

While the new plant was under construction, on 25 January 1908, a spectacular explosion destroyed the explosives magazine of the Great Cobar Mine. The total weight of blasting explosives held in the magazine at the time was 2,285 lbs, slightly over a ton. It was first noticed that the magazine was on fire, then a small explosion occurred, lifting off the roof, followed 15 minutes later by an enormous explosion. Fortunately, there had been time to warn most residents of the impending danger; there were no serious injuries and, other than the total destruction of the magazine itself, very little property damage.

When the new plant was completed around September 1908, there were problems bringing it into service, but fortunately the old syndicate-era smelters were able to be kept working. By January 1909, two of the new furnaces were working but had been damaged; the other one was completely out of service. Kendall blamed Blakemore for this situation. Blakemore was dismissed, and replaced with a North American manager, Herman Bellinger, in February 1909. Blakemore contended that Kendall's design had been faulty, and he remained in the district as a consultant to other ventures. Blakemore would later work for the rival C.S.A. mine, something which would have consequences for the Great Cobar, a decade in the future.

By August 1909, one newspaper report subtitled, "Parlous Position of Mine and Finances", reported that after paying the debenture holders, the company had made a net loss of £500. It pointed out that this was in fact an artificially low amount, because in company's accounts, "No provision has been made out of profits, for depreciation, preliminary expenses, underwriting commission, and discount on debentures", and by making a loss there was no contribution to a sinking fund—intended to be £100,000 per annum drawn from profits—for the eventual redemption of the debentures.

The company needed to raise more capital, and in November 1910, its authorised capital was increased to £1,000,000 by the issue of 30,000 new £5 shares. However, the directors also enacted a right to apply any new capital to the sinking fund for the redemption of debentures, which should have been funded from profits.

In 1910, the company bought the Cobar Gold Mine.

Administrative building.

Bellinger came to see that indeed there were many faults in design of the vast but rushed expansion. When there was industrial trouble, Bellinger was in no hurry to resolve the strike, and used the consequent shutdowns for a major reworking of the still new plant. The plant was augmented with new bins, a fourth water jacket furnace and convertor, another electric locomotive and more slag pot wagons, and the three damaged water jacket furnaces were rebuilt. In December 1912, a new flotation process plant entered service, which allowed recovery of copper ore from the tailings of the original concentrator plant.

By the end of this work, as much as £500,000 had been spent on the new plant, which was way in excess of the original budget, but by the end of 1912, the surface plant finally was working properly.

Also in 1912, as if to demonstrate its confidence in the future for the mine, the company opened its grand new administration building.

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  Ore train, c.1913.
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  Pouring molten copper matte from a water jacket furnace, June 1912.
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  Convertor discharging blister copper into ingot moulds, 1911.
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  Dumping slag, June 1912.

Operational difficulties

In 1912, net profit for the year was £168,617—buoyed by a rise in the copper price from £58 per ton in December 1911 to £79 12s in June 1912—but this profit was not high enough to allow a dividend. Conscious that even this level of profitability was precarious—dependent as it was upon the copper price—above all, the company pushed for higher rates of production, neglecting mine development for short-term high rates of ore extraction. By 1912, a total 2,200 people were employed by the company, with 960 worked at the copper mine and smelter, in Cobar, and it paid wages and salaries of £600,000.<<check ... seems too high, 60K?>>

Although the surface plant was heavily mechanised, the underground mine was not. Rock drills were powered by compressed air, and blasting was used, but otherwise underground mining was an entirely manual process, carried out by a large and expensive workforce. The mine itself became a bottleneck in the vast enterprise, unable to get enough ore to the surface to satisfy the smelting furnaces. In 1910-11, miners raised a total of 298,050 tons of crude ore, while another 6,243 tons came from the old dump at the Cobar Gold Mine; from this ore the company recovered 6,248 tons of copper, 22,048 oz of gold, and 109,421 oz of silver, with a total value of £372,046. But that was not enough.

In the year to 30 June 1912, copper prices the smelter handled a massive 418,318 tons of ore, for an output of 6,736.5 tons of copper, 37,696 ounces of gold, and 178,938 ounces of silver, generating a gross profit of £168,691 5s 9d. But after deducting debenture interest, new construction costs and other expenses, it was still insufficient to pay a dividend. A problem for the new plant was that too much of the copper was being lost; the recovery rate was 1.94% copper per ton of ore, meaning around a quarter of the copper in the ore (assaying 2.6%) was lost during processing, mainly ending up in the slag. Bellinger added a concentration and flotation plant, capable of processing 700 tons per day, to improve recovery.

Even limited success brought its own problems. Mullock was needed for backfilling, to raise the floor level of underground stopes, as miners extracted the ore, and to stabilize worked-out areas. In 1911, work began on an open-cut quarry, intended only as a source of mullock, not mineral ore. At first sight, this may seem a strange and wasteful practice, but in those times, with the ore being smelted in furnaces, much of the gangue material ended up in the form of slag, not mullock or tailings. Even with the qurry, the mullocking of the underground workings was not sufficient to prevent a large ground movement or "creep", in 1913, extending from the mine's No.9 level to the surface, which resulted in the destruction of the workings above No. 9 level, and the inability to access some ore reserves. Ventilation of the workings was also becoming a problem, due to the lack of mine development work; in 1913, the Inspector of Mines issued a compulsory order that the Great Cobar excavate a drive connecting its workings to the neighbouring North Cobar workings, to improve ventilation in the mine. Ground water was also a problem, 40,000 gallons per day of corrosive saline water needed to be pumped out of the workings, using three electric pumps. (light rail p9)

An even more pressing problem for the company was the type of ore that was being mined; 'basic' and 'silicaceous' (or 'acidic') copper ores occurred at Cobar. Both types needed to be blended with the other for smelting, or other fluxes were needed to effectively remove impurities, particularly iron, from the copper matte produced in the water jacket furnaces. As time progressed, and mining went deeper, the ore from the Great Cobar was increasingly 'silicaceous', with a higher iron content. In the absence of a supply of 'basic ore', the smelters needed to bring in more limestone as a flux. In early 1914, the company was planning to open a quarry, at Molong, capable of mining the 100 tons of limestone per day, needed by its smelters.

A possible solution was to stop smelting at Great Cobar. One of the smaller mines in the region, the Queen Bee Mine, at Illewong, eventually stopped its mine site smelting operations altogether, and instead produced copper concentrate, which was shipped to the large E.R.& S copper smelter and electrolytic refinery, at Port Kembla, which had opened in 1908. However, the Great Cobar company had invested in a huge smelter at its remote mine site.

The electrolytic refinery at Lithgow initially remained in operation under Great Cobar Limited, but was closed down in August 1911, retaining only the coal mine and coke works. From then on, Great Cobar sent the blister copper that it smelted at Cobar to America for refining.

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  Great Cobar Mine and Smelter viewed from Cobar, c.1915
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  Furnaces, 1912.
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  Tramways to furnace, 1912.

Financial difficulties

The inability to pay dividends affected the company's ability to raise new share capital. In 1910, the company had put 30,000 new £5 shares up for sale, with the capital raised to be used to redeem debentures, and reduce the crippling interest payments. By the end of 1911, only 15,000 of these new shares had been issued to shareholders; with existing Great Cobar shares trading below their £5 face value, there was no reason for the remaining 15,000 shares to be taken up.

In 1913, the venture made a gross profit of £116,281, but this was netted off against debenture interest payments, redemption of debentures, and expenditure on the new flotation plant, leaving a net loss of £23,210.

A decrease in the price of copper to a range of £65 to £70 during 1913 led to further financial difficulties and a drop in share price to only 6s 3d by January 1914. Bellinger resigned on 10 November 1913, following a visit to Cobar, by one of the company's English directors. (light rail)

In January 1914, George Blakemore, by then the managing director of the rival C.S.A Mine, was stating publicly that the Great Cobar was in financial strife. He saw the huge plant at Cobar as "largely a lamentable waste of money"—by his calculation £470,000—and he opined that the production cost of copper from Great Cobar's operations was then more than double what it had been in 1905, under the syndicate's management. He foresaw a company reconstruction based on some kind of joint operation of the C.S.A. and Great Cobar Mines as a solution to what he saw as the otherwise intractable problems of the Great Cobar's smelting operations, particularly the imbalance between 'basic' and 'silicaceous' ores. The general manager of the company, George Baker, rebutted Blakemore's claims, pointing to a 25% increase in labour costs, poor relations between management and labour—implicitly blaming the previous general manager, Herman Bellinger, for that problem—and lower efficiency of labour due to the greater depth of the mining operations. In the end, the precise reasons did not matter, the financial bottom line did.

Receivership and aftermath

On 7 April 1914, it was reported in London that the debenture holders had appointed a receiver, Arthur J Whims. Mr Klug, representing the firm of Bewick, Moreing, and Co.—a firm of consulting mining engineers and mine managers—would be the new manager of the Great Cobar. There would be a complete, and indefinite, cessation of all operations, including even the company's bakery and butchers, throwing about 1,000 men out of work at Cobar. Initially, 80 men were kept on for care and maintenance.

The mine's main shaft was 1,500 feet deep. Once mining ceased, the mine's new managers failed to keep the pumps running, and the workings rapidly filled with saline corrosive water.

Great material here http://media.lrrsa.org.au/unit159/Light_Railways_159.pdf

Reopening, contention with C.S.A. Limited, and final closure (1916-1919)

Following the outbreak of the First World War, vast quantities of copper were needed for brass bullet and shell cartridge casings. The price of copper rose in response to the demand, and the British Government sought to control supplies of the metal in its colonies and the Dominions. Reopening Great Cobar would not only have the potential for profitable operation but also had a patriotic dimension, in support of the war effort.

A consultant, Mr Pellew-Harvey, visited the mine and identified that £102,000 was needed to restart operations. A meeting of the debenture holders, in May 1915, carried a resolution authorising the receiver to take the necessary steps to reopen the Great Cobar operations. The receiver attempted to raise the full amount, at 6% interest, from the debentures holders, but only £62,000 was raised. At the instigation of the local representative of the receiver, David Fell, the remaining £40,000 was allocated to the New South Wales Government, which agreed to similar terms as the participating debenture holders. At this lower level of capitalisation, it was estimated that the mine would provide a 23% return.

With the finance in place, the receivers of the company, in early November 1915, gave instructions to recommence operation, with the plan to be smelting ore again by the beginning of February 1916. The Great Cobar and Chesney mines had already been pumped out, then repairs to the Great Cobar's main shaft were made, and gradually operations restarted. The first blister copper was produced in early February 1916.

High copper prices assisted the reopened Great Cobar, but none of the operation's earlier difficulties had been resolved. The imbalance of 'basic' and 'silicaceous' ore, in particular, became ever more acute. The mining was by then occurring at the lower levels of the mine, increasing the difficulties of bringing it to the surface.

In its heyday, the Great Cobar was the dominant copper mine of the Cobar field, but that status was no longer uncontested, by 1916. In 1910, the C.S.A. Mine—until then a modest silver-lead mine—identified a large copper resource.The chairman of its board was the ex-general manager of the Great Cobar, George Blakemore, and he aggressively pursued a policy to make the expanded C.S.A the dominant mine on the field.

An extension of the railway line from Cobar to the C.S.A. Mine, at Elouera to the north of Cobar, was under construction during 1917, and it opened in January 1918. One of the reasons that had been used to justify the railway extension was to ship low-grade 'basic' ore from the C.S.A. to the smelters of the Great Cobar Mine; it would be mixed with Great Cobar's 'silicaceous' ore, mainly as a flux for smelting, replacing limestone brought from much further away by rail. Such an arrangement held out a lifeline to the Great Cobar, but was never begun.

In 1917, the C.S.A. started using the first of its own water-jacket blast furnaces at its mine site. Some observers saw this as an illogical move—the huge Great Cobar smelters already existed and would soon have a rail connection to the C.S.A—and not the best outcome, considering the Cobar region as a whole. At latest by early 1919, there was an acrimonious disagreement, between the managements of the two companies, probably motivated by the underlying unresolved contention over which company would dominate copper production on the Cobar mining field. The outcomes were that Great Cobar did not take any of C.S.A.'s low-grade ore as flux, Great Cobar still needed to source limestone, and the new railway was under-utilised, although it was still of great benefit, but to C.S.A. only.

In the end, the final and existential threat to the Great Cobar came from the falling price of copper, after the end of the First World War in 1918. During the war, copper was £135 per ton, falling to £122 after the Armistice, and by March 1919 to £78, with the prospect of a further decline. At the prevailing copper prices, the Great Cobar's vast operations were no longer profitable. In March 1919, the Great Cobar mine and its smelters closed, throwing hundreds of men out of work in Cobar.

Over the life of Great Cobar Limited, the company had paid only one dividend of 15 shillings on its £5 shares, but had paid interest to the 6% debentures holders, up to the time of the appointment of the receiver in 1914. After 1914, the shareholders were no longer involved, having lost both all their money and control of the company. The debentures holders were also repaid the £62,000 that they had advanced in 1916. Also repaid, with 6% interest and a bonus, was the £40,000 loan from the NSW Government made in the same year.

Aftermath (1919 - 1965)

For a short time, hopes were held that the mine would reopen. Any expectations of reopening of the Great Cobar furnaces were doomed. A report by the NSW Mines Department concluded that the mine was unprofitable, highlighting yet again the lack of basic ore. The C.S.A. Mine, once seen as key to solving the lack of 'basic ore', was itself facing difficulties due to low copper prices, and remained closed until September 1919; in the end, it could never supply the much-needed 'basic ore', or be operated jointly with the Great Cobar, because by mid 1920, it too was totally closed.

David Fell formulated a plan to start a limited operation to produce copper concentrate, by the flotation process, at another mine owned by Great Cobar Limited, the Cobar Gold Mine (Fort Bourke Mine). It would need £100,000 in new capital. The limited operation was envisaged as just the first step in a larger initiative to link the mines in the area by light railways, and operate the mines in the Cobar area as one joint operation, eventually perhaps resulting in mining resuming at the Great Cobar. Fell's plan did not win support of the debentures holders.

In May 1919, the manager of the mine announced that the equipment in the mine, up to No. 10 level, had been removed, and that the pumps were being stopped, leaving about six months duration before water would reach that level of the mine. In June 1920, the receiver in London issued an order that the assets of the Great Cobar be realised. The Great Cobar was to remain closed, permanently.

In August 1921, the Great Cobar assets were purchased by A.A. Goninan, a Newcastle-based engineering company, who only wanted to dismantle some large industrial buildings and relocate them to its site, at Broadmeadow, and sell off or scrap the rest. The electrolytic refinery at Lithgow had also closed, and parts of its equipment were sold and relocated to the C.S.A.'s new electrolytic refinery at Kandos.

The closure of the Great Cobar was just the first in the Cobar region, taking with it the Chesney Mine, at Wrightville, which it owned and which depended upon its smelter, and the Cobar Gold Mine. In 1920, the C.S.A mine at Elouera closed unexpectedly due to an underground fire, as did the Gladstone Mine, at Wrightville, which used that mine's smelter. In July 1921, the Occidental Gold Mine at Wrightville closed, and the widespread expectations that it would reopen were dashed in July 1922. After the Mount Boppy Gold Mine, at Canbelego, finally closed, in 1922, there were no longer any large mines working in the Cobar region, and there would not be until work resumed at the Occidental Mine, subsequently the New Occidental Mine, in 1933. Many miners and their families left the district altogether.

What was left of the Great Cobar, c.1934. The tallest of its chimneys had been toppled in 1921.

In September 1933, a huge fire ripped through what remained of the Great Cobar. The fire was deliberately lit, with the ore bins and poppet head being set on fire. Burning debris fell down the main shaft, setting fire to underground timbers. The town was enveloped in dense, choking, sulphurous smoke, from burning timber and ore. It was expected that the fire would burn for a week—there being no means to suppress the fire—until there was nothing combustible left above the waterline.

Later in the 1930s, two of the mines once owned by Great Cobar Limited, the Chesney Mine and the Cobar Gold Mine, were reopened, by the New Occidental company, and both worked until 1952. The rival C.S.A. mine was reopened in the 1960s, and continues in operation.

Processes and technology

The process and technology described below is that used by Great Cobar Limited.

Ores and reserves

At 30 June 1912, the estimated ore reserves of the Great Cobar mine were 1,813,087 tons, assaying 2.6% copper. At the same date, the mine was working down to the 13th level and the main shaft was at 1,419 feet down. To that could be added 302,174 tons at the Cobar Gold Mine and 663,349 tons from the Chesney Mine, totalling 2,777,610 tons, with another 350,000 that were viable to mine at Great Cobar at a suitably high copper price.

Mining techniques and equipment

Main shaft

The new main shaft had a rectangular cross-section, 15 feet by 8 feet, divided into three compartments; two carried cages and the other contained pipes, cables and a ladderway. (light railways 159, p7) By the time the mine first closed in 1914, the main shaft was 1500 feet deep, providing access to 14 levels in the mine.

Mullock shaft

There was a separate mullock shaft down which mullock was dropped, until the 300 foot level, from where it was distributed as fill to raise the floor level of stopes as these were mined out. (light railways 159, p7)

Copper extraction process

Location and scale of operations

In the late 19th Century and first decade of the 20th Century, most non-ferrous metal mines in Australia had local smelters. In New South Wales alone, there were examples of mine site smelters at Burraga, Sunny Corner, Bobadah, Nymagee, Mount Hope, Girilambone, Illewong, and Shuttleton. However, some of the larger miners stopped smelting at their mines and established smelting works on or near the coast. Examples were the Broken Hill smelters at Port Pyrie, the Electrolytic Smelting and Refining operation at Port Kembla, and the Cockle Creek Smelter. Smelting away from the mine had several advantages, including better seaport access, easier access to coal, coke, and limestone, the ability of more than one mine or mining company to make use of the one smelter. It had other advantages, stemming from a location that is not as physically remote from larger population centres and needing to be largely self-sufficient. The trend to off-mine smelting was made more feasible by the use of the froth flotation process, at the mine site, which separated an ore concentrate from the gangue material, so that only the concentrate was shipped from the mine site to the smelter.

While in 1906 the trend to off-mine smelting was relatively new, with hindsight, the Great Cobar's choice to locate its vast copper smelter, at Cobar, seems like a mistake. Perhaps its timing was just bad; Delprat's process of froth flotation was still newly-invented. The apparent success of the previous smelting operations of the Great Cobar Mining Syndicate was probably also a factor, but Great Cobar Limited would attempt to operate their mine and new smelter, on a far greater scale than the previous owners.

When designing their new plant at Cobar, Kendall and Blakemore based it upon daily production rates of 45 XXXXX tons of copper, needing as feedstock for the furnaces, 1,500 tons of 3% XXXX (XXXX concentrated %) copper ore (how much gangue needed to be removed in concentrator?), 130 tons of coke, ultimately 100 tons of limestone. 900 tons of slag would also be produced, and need to dumped on the site. (light rail p9) (what was burned off in the concentrator).

Great Cobar also inherited the still fairly new electrolytic refinery at Lithgow, which would refine blister copper from the Cobar smelter, until 1911.

Concentration

Need for concentration, gangue is useless.

Some flotation, after 1912 , what else? Gravity concentratoe, picking tables?

Smelting

Production of copper matte using concentrated ore, coke and flux as the feedstock.

Molten copper matte was tapped into ladels, which were carried by overhead travelling gantry cranes, to the convertors. Low-grade copper matte was taken to what was known as the 'matte ring' where it was cooled and later used as smelter feedstock (like ore).

Molten slag was tapped into slag wagons and towed by an electric locomotive to be dumped.

Gases given off by the smelter passed through a filter house that recovered dust, which was then fed back into the furnaces, because the dust contained metals. After removal of dust, the gases passed to the smelter chimney.

Visible for miles around Cobar, the smelter chimney was the highest on the site, at 206 feet high. It was 25 feet in diameter at its base and 7 feet at its top. It contained 250,000 bricks, surrounded by 200 tons of steel plates, secured with a million rivets.

Conversion

Conversion involved the production of blister copper also known as Bessemer copper ( xxx purity) using molten copper matte as the feedstock.

Refining

Information on refining 1907 (Redo citation as news later)

Ancillaries

Electrical power

250Vdc was consumed by the overhead cranes at the smelter, the convertor tilt mechanism, and the electric locomotives of the railway, all fed from two Siemens 260 kW motor-generator sets. (light rail, p10)

Compressors and blowers

There were blowers for the

Surface transport

The standard gauge railway inside the plant was electrified at 250 Volts d.c. using overhead wiring. Locomotives used either a type of rigid bow collector (photos) or a pantograph, (light rail p10), to obtain power from the overhead line.

A vestige of the narrow gauge tramway that had been used under the syndicate remained in use. It was used to convey wagons containing molten low-grade copper matte, drawn by horses, to an outside area, known as 'the matte ring', where it was cast in moulds. It was then fed back, in solid form, into the water jacket furnaces.

Remnants

The administration offices of the Great Cobar mine have become the Great Cobar Museum and Visitor Information Centre. Over a century after the closure of the mine, the remainder of the Great Cobar mine site is fenced off and off limits to the public, for reasons of safety.

Behind and to the south of the museum is a large piece of land which was once the mine and smelter site, and still has some ruins and remnants. The open-cut mullock quarry is now a lake on the site. At the southern and eastern ends of the site, is the vast black-coloured slag dump. In the north-eastern corner of the site, the concrete structure supporting the huge 'Cobar' sign, at the entrance to the town, is a relic of the Great Cobar mine.

Some convertors from the Great Cobar have been recovered and provided to the heritage centre.

The ornately engraved share warrants of Great Cobar Limited, are still traded, sometimes at prices higher than their £5 per share face value, but only as collectables. The Great Cobar Mine itself never reopened.

• 
  Great Cobar Museum & Cobar Visitors' Centre, the former administration offices.
• 
  Part of the vast slag dump, viewed from Kidman Way (Aug 2024)
• 
  Great Cobar Ltd share warrant. This one was issued after more capital was authorised, in late 1910 (note red-coloured overprinting).

<<Drafting notes: Suggested categories: Cobar, Mines in New South Wales>>