cmr/aru lookalikes-mary kathleen
Probably more similarities to cmr than aru.
Mary Kathleen is a former uranium mine operated between 1958 and 1963, producing 4080 tonnes of uranium oxides. CWG gives a cheap entry into this araa in their jv with gse.
Mary Kathleen is about half way between Mount Isa and Cloncurry, in far north west Queensland. The deposit was discovered in 1954 by prospectors from nearby Mount Isa. In 1955 Mary Kathleen Uranium Ltd (MKU) was formed, with a majority of the shares held by the Rio Tinto Mining Company of Australia Limited.
A sales contract with the United Kingdom Atomic Energy Authority was signed in 1956. Mining commenced at the end of 1956 and the treatment plant was commissioned in June 1958. The project was developed by MKU at a cost of A $24 million.
Beyond ascertaining that sufficient ore (at a grade of 0.16% ) was available to meet obligations under the UK contract, the orebody was not fully proved up at this stage. (Initial reserves were later quoted at 7 million tonnes of 0.12% ore containing 12,000 tonnes of U3O8.) However it was evident that the mineralisation (3.0% rare earth oxides and 0.025% thorium oxide) really comprised a rare earths orebody containing uranium, and over the years various attempts were made to find markets for the rare earths as a co-product, to no avail.
In this first phase of operation from 1958 to 1963 Mary Kathleen treated 2.9 million tonnes of ore at an average grade of 0.13% to yield 4082 t (4500 short tons or 9 million pounds weight of U3O8) of uranium concentrate (then actually yellowcake - ammonium diuranate) containing 3460 tonnes of uranium.
Initially the process was the conventional sequence of crushing, grinding, leaching with sulfuric acid, counter-current decantation, followed by ion exchange and extraction and drying. In 1960 electronic radiometric ore sorting was introduced to concentrate ore prior to crushing, with the result that the head grade feed increased from 0.17% to 0.24%.
Tailings were emplaced in a 12 hectare tailings dam in a small valley west of the plant. This overflowed into an evaporation pond of some 60 hectares.
With improvements in the treatment plant the contract was filled faster than the nine years originally envisaged, and hence in October 1963 the mine closed and the plant was put on care and maintenance. Some 2.8 million tonnes of 0.148% ore was identified then as remaining accessible by open pit mining, containing 4246 tonnes of uranium oxide.
In the event, the mine remained closed for more than a decade. New contracts with utilities in Japan, Germany and USA for 4740 tonnes of uranium oxide were negotiated early in the 1970s and recommissioning began in 1974. The company made a share issue to raise capital, and the Commonwealth Government, through the Australian Atomic Energy Commission underwrote this, thereby obtaining a 42% holding in the company. Conzinc Riotinto of Australia Limited, a successor of Rio Tinto Mining, held 51%, and the public 7%.
In the plant the ion exchange section was replaced with a more effective solvent extraction process and the mine and mill reopened in February 1976. The cost of refurbishment was A $26 million.
At the end of 1982 the mine was depleted and finally closed down after 4802 tonnes of uranium oxide concentrate had been produced in its second phase of operation. During the 12 years of operations about 31 million tonnes of material was mined, including 7 million tonnes of ore.
Notwithstanding the minimal conditions imposed in relation to the 1954 leases, the company took the view that it should conform to relevant current environmental and occupational health standards. Consequently, before the recommissioning in 1976 a full environmental impact study was undertaken and this incorporated a rehabilitation plan for the 64 hectares of waste dumps, 29 hectares of tailings dam and 60 hectares of evaporation ponds. Mary Kathleen then became the site of Australia's first major rehabilitation project of a uranium mine, which was completed at the end of 1985 at a cost of some A$ 19 million. In 1986 this work won an award from the Institution of Engineers Australia for environmental excellence.
In the late 1980s, following relinquishment of the Mary Kathleen leases, MKU was liquidated.
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