Olympic Dam is an underground copper-uranium mine and plant located in South Australia about 560 km northwest of Adelaide. The mine is accessible by public road.
WMC Resources discovered the deposit in 1975 and opened the mine in 1988. Olympic Dam is was acquired by BHP Billiton in 2005.
Olympic Dam is the world's fourth-largest copper deposit and the largest uranium deposit and the fifth largest gold deposit. It also contains significant quantities of silver.
The underground mine extracts copper uranium ore and hauls the ore by an automated train and trucking network feeding underground crushing, storage and ore hoisting facilities. The processing plant consists of two grinding circuits in which high-quality copper concentrate is extracted from sulphide ore through a flotation extraction process. The operation includes a fully-integrated metallurgical complex with a grinding and concentrating circuit, hydrometallurgical plant incorporating solvent extraction circuits for copper and uranium, a copper smelter, copper refinery and a recovery circuit for precious metals. The primary method of ore extraction is long hole open stoping with cemented aggregate fill. Olympic Dam is Australia's largest underground mine.
As of 2010, BHP Billiton is seeking the approval of the Australian, South Australian and Northern Territory governments for a A$6-7 billion expansion of its existing mining and processing operation. The proposed expansion is centred on the creation of a new open pit mine that would operate simultaneously with the existing underground mine and lift ore production six-fold to the levels shown below. The existing smelter would be expanded and new concentrator and hydrometallurgical plants would be built to process the additional ore, and generate additional concentrate for transport. The combined operations (existing and proposed expansion) would mine 72 Mt ore per year and would produce 750,000 tonnes refined copper, 19,000 tonnes uranium oxide, 800,000 gold ounces and 2.9 Moz of silver per year.
The mine is located approximately 26 km west of Andamooka in South Australia and 560 km northwest of Adelaide. Most mine workers live in the town of Roxby Downs, about 16 km south of the mine with a population of about 4,000. The mine and Roxby Downs connect to the Stuart Highway by paved roads. There are daily flights between Olympic Dam and Adelaide.
The Olympic Dam mine lease is 17,788.11 hectares on arid zone land. The property has a large number of discrete ore zones throughout an area of several square kilometres ranging in depth from 350 metres to approximately one kilometre. The deposit occurs in the basement rocks of the Stuart Shelf geological province in the north of South Australia, west of Lake Torrens.
Mineralization consists of medium-grained chalcopyrite, bornite and chalcocite, fine-grained disseminated pitchblende, gold, silver and rare earth minerals that occur in a magnetic hydrothermal breccia complex beneath 350m of overburden. The ore occurs in distinct zones that determine the mine access and layout
Mining & Operations
Three vertical shafts and a decline access the orebody, which is worked using a variation of sublevel open stoping. Stopes are backfilled with cemented aggregate of crushed waste rock, deslimed mill tailings, cement and pulverised fuel ash.
The mine capacity is 235,000t/y of refined copper and 4,500t/y of high-grade uranium oxide, plus 100,000 oz gold and 800,000 oz silver per year.
Processing facilities consist of a copper concentrator, hydrometallurgical plant, copper smelter, sulphuric acid plant, copper and gold/silver refineries. Recent expansions included a Svedala autogenous mill, additions to the flotation sections, two counter-current decantation thickeners, an electric slag-cleaning furnace, a new anode furnace gas-cleaning plant and additional electro-refining cells.
Copper is recovered primarily by copper sulphide flotation from slurry before the copper concentrate is smelted and electro-refined to high-purity copper. Wastes generated during electro-refining are treated to recover gold and silver. After treatment by flotation, the finely-crushed ore is leached with sulphuric acid to dissolve uranium and any remaining copper. The leach liquor is processed in the solvent extraction plant to separate the residual copper and uranium streams. Copper is recovered by electrowinning and uranium converted to yellowcake and calcined uranium oxide.
Installation of two pulsed columns has increased uranium recovery from solution from 90% to about 97%. These columns use an air pulse to mix the acidic and organic solutions, providing better contact for the chemical reaction involved in transferring the uranium from one to the other.
Environment and Community
Olympic Dam has provided annual funding to indigenous groups in the region to support community development and heritage management programs. Olympic Dam also provides funds to other regional stakeholders for health, environmental and economic development programs.
In February 2005, Olympic Dam achieved ISO 14001 certification for environmental aspects of Olympic Dam Operations. The area covered includes the Special Mine Lease, associated borefields and the aerodrome. Auditors indicated that environmental issues were generally managed well but for two major non-conformances and six minor ones. An action plan to address the non-conformances was developed and submitted to the auditors.
Olympic Dam maintains storage facilities for all waste products. The plant has been designed so that any spillage of ore, concentrate or process slurries can readily be returned to the process circuit. The plant also includes comprehensive air pollution control equipment and both air emissions and noise are monitored. Extensive radiation monitoring of personnel and the environment is ongoing.
The arid recovery reserve is an ecosystem restoration initiative working to restore Australia's arid lands. It is located partly on the Olympic Dam Mine Lease (7km2) and partly on adjoining pastoral properties.