Facts about Copper
- Is an excellent conductor of electricity
- Is an excellent conductor of heat
- Is resistant to corrosion
- Is an important trace element in human health in areas related to nerve protection, brain and metabolism function, blood vessel strength and as an anti-inflammatory
- Was first discovered in its native form more than 10,000 years ago
- Was used extensively for weapons, tools, art, jewellery and house hold items in ancient civilizations
- Is used today in plumbing, electrical wiring, computer chips, electrical and heating products and appliances, as a fungicide for timber and a fertiliser, to kill algal blooms in water reservoirs, for scientific instruments, ornaments, coins and on water vessels.
- Is the eighth most abundant metal in the Earth’s crust
- The first economic discoveries of copper were in South Australia earning the State the title of ‘Copper Kingdom
- Most copper produced in Australia comes from underground mines.
- The main ore mineral in Australia is chalcopyrite. Other sources of copper around the world are bornite, chalcocite, malachite, azurite, native copper and cuprite.
- Is alloyed with other metals. Bronze is an alloy of tin and copper and brass is an alloy of zinc and copper.
- Copper is mined in all States and the Northern Territory. Olympic Dam in South Australia is one of the largest copper-gold-uranium-silver accumulations in the world. Copper is in the form of chalcopyrite. The Mt Isa Mine in Queensland is one of the largest underground mines in the world mining copper and silver-lead-zinc ores. It produces about 39,000 tonnes of copper ore daily in the form of chalcopyrite, bornite and chalcocite. In Tasmanian copper is mined at the Copper Mines of Tasmania Mt Lyell mine in Queenstown
- Australia has about 6 percent of the world’s copper resources, ranked third in the world after Chile and the USA.
Copper in Tasmania
The winning of copper and gold ore from the Mt Lyell field has been occurring for well over 100 years. Prospectors first arrived in the 1880s in search of gold. As with many mining fields of the time, hundreds of small leases were granted and worked side by side, but few were prosperous. Amalgamation of many of the leases led to the formation of the Mount Lyell Mining and Railway Company Limited (MLMR Company) in 1893. The Company built the famous ‘Abt” Railway to the river port of Teepookana (on the King River) and later to the township of Strahan in 1896. The MLMR Company also built the Lake Margaret hydro power stations on the Yolande River to supply power for the mines, and the smelter.
In competition to the MLMR Company was the North Lyell Mining Company (NLM Company) who mined the very rich Iron Blow deposit on the eastern side of the West Coast Range. The Company built the North Lyell Railway through the King river Valley to supply feed to the smelters at Crotty, as well as to provide access to Macquarie Harbour, at the township of Pillinger. They also built a power station, sampling mill, boiler house, assay office, and workshop.
Pyritic smelting, developed by metallurgist Robert Sticht, later General Manager for the Mt Lyell Mining Railway Company commenced at the Mt Lyell field in the early 1900s.the smelters were closed up in 1969. Sticht developed the pyritic process and designed and erected the smelters, achieving worldwide renown. Unfortunately the sulphurous fumes from the smelting stacks contributed to the environmental degradation of the vegetation, a legacy that the area is only beginning to recover from.
In 1903 both companies amalgamated and continued to mine the open cut Iron Blow until it was exhausted, and then converted to an underground mine. In 1935 another open cut was started at West Lyell. The open cut became the single largest producer of copper in the British Empire, and one of the first open cuts in Australia, and remained so for much of the first half of the 20 th Century. Several thousand workers were employed in the area, 500 alone in the smelters to help supply the burgeoning demand worldwide. A refinery was added in 1928 to allow refined copper to be produced.
Large dump trucks (30 tonnes) and electric shovels were used to move millions of tonnes of overburden and ore. The ore was crushed and loaded on trains for the underground haulage to the processing plant. Extensive use of railway and tunnels in steep terrains connected and moved around the various sources of ore until such time as this method was not profitable. During its lifetime 57 million tones of material was moved. The open cut remained the primary source for the company until 1972 when it became uneconomic. The mine reverted to an underground operation in 1970 primarily winning copper from the The Prince Lyell ore body.During the early 1970s world copper prices fell dramatically and the main developments were put on hold, activities were curtailed and many workers were retrenched. Mining and processing continued however throughout the 1970s and 1980s mainly from Prince Lyell, but also from deposits at Cape Horn, 12 West and Royal Tharsis. The last of the rail haulage ceased in 1987. At that time diesel trucks were used to haul the ore from Prince Lyell up the decline to the surface primary crusher. These trucks, rated at 50 tonnes capacity, were the largest underground truck in operation in Australia at the time, and would still rate as one of the largest, if still in operation today. Shaft hoisting and underground crushing commenced in 1989.
At the end of 1994, after 101 years of continuous operations on the lease, the MLMR Company ceased operations. Operating costs were increasing, the mine was getting deeper, ground conditions were a problem, while on the surface the disposal of tailings in the Queen River could no longer be tolerated. The site needed to be restructured and refurbished.The State Government awarded the leases to another operator, Gold Mines of Australia, who set up the company, Copper Mines of Tasmania Pty Ltd, as the operator on site. Development work commenced in January 1995, as well as refurbishment of the processing plant, rehabilitation of the surface areas and construction of a tailings facility, at Princess Creek, 8 km from the plant. The tailings dam stores run off from the overburden from the old workings and water from the underground operations, dramatically reducing the amount of contaminated water going into the river systems. Another unfortunate legacy from the historical mining practices has resulted in massive deposits of heavy metals flowing from the Queen and King River into Macquarie Harbour. Better practices and improved knowledge is addressing this all the time.The new operator also brought in a change in mining method (sub-level cave), a change in the management of labour (through a mining contractor), as well as changes in work rosters and production rates. A number of studies were undertaken to determine best operating practices for the site, as well as the feasibility of an adjoining ore body.
Production levels were increased, but despite this the Company went into receivership, due to cashflow problems. The operation and the Company itself were sold to an Indian owned and managed group called Sterlite Industries (India) Ltd, who owned a copper rod mill, telecommunications and optic fibre plants and were operating a copper smelter in southern India. The new (and current) owners commenced on site on 1 April 1999. The strategy for the new operator is to supply the high quality copper concentrates to the smelter in India. The Company has spent capital on site to increase production and extend the life of the mine. Capital has included normal production related expense, such as decline and level development, upgrading of the shaft skip capacity, lifting of the tailings dam facility. Capital has been used to increase production rates and upgrade certain sections of the process. Major improvements occurred with installation of a tank cell in the flotation plant, as well as a regrind mill to improve concentrate grade. In the past 2 years, major parts of the operation have been automated.
The strategy for the Mt Lyell site is to continue production of the Prince Lyell orebody, mining and processing at maximum rates. The best performance has been 2.7 million tonnes per annum. This has to be coupled with consistent and low cost performance to allow for a stable operation. The operation is a low grade operation, at an average plant feed grade of 1.25% copper and 0.3 g/t gold. Other deposits in the near area will be assessed for the possibility of extraction. To date, no economically viable solution has been found.
As a long term contributor to the West Coast and the Tasmanian economy, Copper Mines of Tasmania are looking at continuing the improvements on site, particularly in the area of environmental management, and with suppliers to ensure that the history of the Mt Lyell field will continue for a period to come.
