The draft environmental report on the expansion of the Olympic Dam mine has been made public. The project could boost the mine's uranium output to 19,000 tonnes per year.
Olympic Dam is primarily a copper mine that produces 200,000 tonnes of the metal annually while by-products include up to 4000 tonnes of uranium per year as well as gold and silver. The figures make Olympic Dam the third biggest producer of uranium, with about 8% of the world's supply.
Owner BHP Billiton plans to roughly triple the size of the mine in a progressive manner over 11 years from 2010 and today made public the draft of its environmental impact statement for comment.
Current excavation goes on underground, but the expansion would see a large open pit developed, taking about five years to remove surface rock to expose the first section of the ore body. Over 40 years, BHP Billiton said, the pit would grow to be 4.1 km long, 3.5 km wide and 1 km deep.
|Olympic Dam plant buildings, left, are above tunnels that mine only
a fraction of the Olympic Dam resource (Image: BHP Billiton)
Major considerations in the project are water supplies, which must increase from 37 megalitres to 216 megalitres per day, and power which must go from 125 MWe to 775 MWe - representing about 10% of South Australia's current baseload demand.
According to preliminary schedules, the main increase in power use would come in around 2013. Most of the power will come from the grid, using Australia's fossil-heavy generation mix, but BHP Billiton is to supplement this with a 250 MWe co-generation plant using heat from the burning of sulphur that takes place when manufacturing acid for the mine's metallurgical plant.
A seawater desalination plant will require 35 MWe and this is to be powered by renewable power purchased through the National Electricity Market. BHP Billiton said that "At present, no commercially viable solar or wind energy solution has been identified at the baseload scale required [for the main parts of the mine]. A concentrated solar thermal study for a supplemental supply of up to 150 MW is ongoing."
Subject to public comments, a revised and finalised environmental impact statement and government approval, Olympic Dam's uranium oxide production would gradually increase to 17,000 tonnes per year, with a further 2000 tonnes per year extracted from copper concentrate product by BHP Billiton's customers.