There has arguably never been a more eventful year in Australia's uranium history than that to mid 2014. While low prices were directly or indirectly the cause of some events, exploration, innovation and determination dictated some of the script, writes Ian Hore-Lacy.
Olympic Dam provided the only stability in Australia's uranium mining picture over the country's reporting year, July 2013 to June 2014, contributing 72% of the country's production from its deep copper mine, where uranium is simply a by-product (ahead of gold). At ERA's Ranger mine in the Northern Territory, operating since 1980, a failed leaching tank resulted in no production for the last six months to June. The mine is now back in operation.
Late in 2013 Uranium One's Honeymoon ISL mine shut down to await improved uranium prices for its Russian owners, and at ISL operations controlled by US General Atomics' Heathgate Resources there were other changes. First, production at the main Beverley field, which had been declining markedly, was suspended in December. Then production from Beverley North was suspended in January, to enable concentration on bringing the adjacent Four Mile ISL mine into production. First Four Mile production occurred from the east orebody in April. Heathgate, through a subsidiary Quasar, has farmed in to Alliance Resources' Four Mile project, leaving it as a minor partner as the ore resource grows spectacularly with ongoing exploration drilling. Uranium recovery is through a satellite plant on the Beverley North lease 2.5 km away, with loaded resin being trucked 10 km to the main Beverley plant for elution and drumming. Alliance is seeking to sell its 25% share of the project which it initiated.
In Western Australia, Toro Energy is progressing towards production from is Wiluna project, now comprising a bunch of shallow calcrete deposits. Centipede-Millipede will be mined first to give the project legs, then Lake Maitland, then Lake Way. The priority will be mining the high-grade parts of the deposits, giving a feed grade of 0.088% U3O8. Production of 770 tU/yr over some 16 years is planned and Toro anticipates first production from the Wiluna mine in 2016.
And good news in July from Queensland: it is now ready to accept applications for mining uranium there, following announcement of a new regulatory framework. Couched in the necessary reassuring verbiage, the government reversed the ban imposed by a previous Labor government on purely ideological grounds some 25 years ago. However, exploration was allowed to continue, and during this time Paladin paid over $1 billion for 82% of the Valhalla deposit near Mount Isa and Mary Kathleen. The state government estimates that over 90,000 tU can be exploited from the state, mostly in that northwest region.
However, reflecting part of the new profile of uranium resources worldwide, the first call from the Queensland government was for tenders to recover rare earths from the old Mary Kathleen Uranium tailings dam. This was essentially a rare earths orebody with 0.10% U3O8 in it, and it yielded 7531 tU over 1958-82, with a 17-year gap in the middle. At the time the rare earths were unsalable.
Another harbinger of change is at the Olympic Dam mine in central South Australia. Having baulked at the AUS28 billion ($26 billion) cost of a major development of the mine two years ago, BHP Billiton has applied for government approval to build and operate a demonstration-scale heap leaching plant, as the company looks for more economical ways of expanding this key South Australian project. Heap leaching has not previously been used for uranium ore in Australia (that at Rum Jungle over 1965-71 was for copper), though it is increasingly favoured for low-grade hard-rock uranium ores overseas. (BHP Billiton uses it on a large scale at its Spence mine in Chile, but only for copper.) Laboratory and pilot scale trials of the technique using run of mill ore from the existing operations have shown promising results to date. The company expects to start construction of the demonstration plant in the second half of 2015, with a three-year trial period starting in late 2016.
The ore will be crushed, placed on an impermeable leach pad and treated with sulphuric acid for 300 days. This is expected to recover most of the uranium, and with major help from bacteria, around half of the copper. The uranium would then be removed from the pregnant liquor by solvent extraction, after which the copper would be removed electrolytically. This essentially reverses the present sequence where most of the uranium is recovered by acid leaching the mill tailings after copper sulphide flotation. Following the heap leaching, the depleted ore remaining will be further crushed, ground and put through a new flotation plant on site to recover the rest of the copper as sulphide, which would then be smelted as at present for all production.
Elsewhere in the country, other uranium projects proceed slowly in the present world of low uranium prices. One of these, the Mulga Rock deposits in Western Australia, will introduce another novelty for Australia: uranium recovery from lignite. Another, the ex-Rio Kintyre project was given EPA approval for its new Cameco-Mitsubishi owners.
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Ian Hore-Lacy is a Senior Research Analyst with the World Nuclear Association. One of the WNA's longest serving staffers, Ian is the author of the organisation's Information Library.