Copper Mines of Tasmania (CMT), a subsidiary of Vedanta Resources, owns the historic Mt Lyell copper Mine in Western Tasmania.
The mine is located on the rugged west coast of Tasmania near to the township of Queenstown. Up to the suspension of operations in July 2014 it was one of the oldest continually operated mining fields in Australia. With a history spanning more than a century, the Mt Lyell Mine has taken its place in mining folklore alongside Broken Hill, Coober Pedy and Mount Morgan. The mine is currently in care and maintenance awaiting change of owners in the near future.
Gold first discovered in 1883
Gold was first discovered in the 1880’s in the Mt Lyell area during the first wave of mineral exploration in Western Tasmania. It took more than ten years for the copper potential to be realised. After many failed attempts at gold and tin mining, with prospectors battling the harsh conditions, commercial copper production commenced in 1896 by the Mt Lyell Mining Company . Early mining focused on open cut production from the Iron Blow orebody and soon after from North Lyell. The North Lyell orebodies, rich in copper and silver, brought rapid development of the area after the amalgamation in 1903 of the Mt Lyell Company and the North Lyell companies to form the Mount Lyell Mining and Railway Company. Full scale copper mining began with the mining of the five main clusters of copper rich ore bodies and continued right up to the closure of 1994.
New pyritic smelting process 1896 – 1969
Mt Lyell ores were ideal for a new pyritic smelting process developed by Robert Carl Sticht, utilising the pyrite in the ore as a fuel for smelting and this was used from 1896 until 1969. The undesirable side effect of this smelting process was the discharge of large amounts of sulphur dioxide which, combined with wood cutting, bushfires and the wet environment, resulted in extensive damage to the local environment, including destroying the local vegetation leaving the hills almost completely bare for many decades to follow.
Remote location and access in early 1900’s
Being remotely located, the new mine had to be largely self-sufficient with only rail and ship transport available until the first road reached the site in 1932, connecting Queenstown and Hobart. The road to Burnie was not completed until 1963. Of necessity the mine became largely self-sufficient in the early days with extensive foundry, metal works, carpentry shops and a brickworks on site. In the early 1900’s the Mt Lyell Mining and Railway Company employed over 3,000 people who lived in the myriad of small townships and settlements throughout the region.
Early adoption of technology in 1916
The early adoption of flotation technology in 1916 enabled the mining of lower grade ores and in 1935 open cut mining commenced with the large, low grade, West Lyell ore body, which repeatedly broke industry records. Exploration during the 1960’s and 70’s proved that the West Lyell ore body continued at depth. To extract the depth extension of the West Lyell open cut The Prince Lyell underground mine was opened in 1972 which successfully mined low grade ore using a sublevel stoping method.
Closure announced December 1994
Many had proclaimed the “end of an era” when the Mt Lyell Mining and Railway Company announced its closure in December 1994, during a period of low metal prices.
The Tasmanian State Government wanted mining to continue at Mt Lyell which still had significant mineral resources, and searched the world for expressions of interest, eventually selecting Gold Mines of Australia. GMA then formed the wholly owned subsidiary, Copper Mines of Tasmania to take up the task and early exploration results showed that ore deep in the old mine could keep the mine going for another 10 years.
Care and maintenance mid 2014
From 1995 up to the mine suspension, and move to care and maintenance in mid 2014, the mine was a highly successful sub level caving operation.
Following the acquisition of the mine through CMT by Indian company Sterlite / Vedanta Resources in 1999 this method was continued, and as the mine progressed deeper following the Prince Lyell Ore Body, more efficient, larger capacity loaders and trucks were introduced to maintain production rates. Underground stockpiles were constructed, and hoisting capacity was increased with the modification of the winder and lighter skip tubs.
Mine upgrades and new tailings storage facility
Upgrades of the existing concentrator plant infrastructure were also undertaken to increase throughputs and recoveries. Two additional crushers and screens were installed to reduce mill feed size and the flotation circuit was upgraded with two new tank cells to improve copper recovery and a Knelson concentrator installed to improve gold recovery. These were good times for the mine and the company.
Copper concentrate was thickened then dried and stored prior to trucking to Melba Flats rail siding. Concentrate was rail-transported to the port of Burnie for export shipping to Vedanta’s smelter in southern India.
Prior to 1994 the Mount Lyell Mining and Railway Company disposed of the mine tailings and slag waste into Haulage Creek which joins to the Queen River near the mine site. This practice ended with the Government requiring the new owner to undertake the construction of a tailings dam facility before re-commencing production.
After the reopening in 1995 all mine tailings were thickened and pumped to the purpose built tailings storage facility.
Significant environmental legacy pollution
CMT, then and now, operates on a site with significant environmental legacy pollution and environmental damage through an agreement with the Tasmanian Government, ratified by an Act Of Parliament: the Copper Mines of Tasmania Agreement Act 1999. CMT promote the recovery of inappropriate past practices and encourages and protects stabilisation and revegetation of disturbed areas.
Looking towards a more prosperous future
In 2009 CMT commenced a feasibility study to expand the operation and extend the life of the mine. In 2010 exploration activity was increased across the mining lease targeting unexplored areas as well as deposits that had been mined in the past. Further drilling has taken place in more recent times in these areas to sure up the mine’s future, possibly with new owners.
Current copper resources in the ground are almost as much as has been mined in the past century of operation.