Potash

Yanis Miezitis (yanis.miezitis@ga.gov.au)

The term potash refers to potassic fertilisers, which are potassium chloride (KCl or sylvite), potassium sulphate (K2SO4 or sulphate of potash (SOP), which is usually a manufactured product), and potassium-magnesium sulphate (K2SO4–2MgSO4 or either langbeinite or double sulphate of potash magnesia (SOPM or K-Mag)). Muriate of potash (MOP) is an agriculturally acceptable mix of KCl (95% pure or greater) and sodium chloride (halite) for fertiliser use, which includes minor amounts of other nontoxic minerals from the mined ore and is neither the crude ore sylvinite nor pure sylvite.

Resources

Historically, Australia has always been deficient in known resources of potash but ongoing exploration has led to recent published resources for some deposits such as the Lake Disappointment, Lake Chandler and Dandaragan Trough/Dinner Hill deposits in Western Australia (WA), in the WA/Northern Territory (NT) portion of Lake MacKay, and in the Karinga Creek Salt Lakes area in southern NT.

JORC Reserves

Currently there are no Joint Ore Reserve Committee (JORC) Code reserves for potash resources.

Exploration

Interest in exploration for potash continued in 2011 in Lake Disappointment, Lake MacKay, south Carnarvon Basin, Perth Basin and Canning Basin in WA as well as the Adavale Basin in Queensland (Qld), in the Barrow Creek area in the NT and in Ceduna area in South Australia (SA).

Production

According to the United States Geological Survey (USGS), about 90% of the world potash production in 2010 was consumed by the fertiliser industry. Potassium chloride is the main fertiliser product, containing an average 61% of K2O equivalent. In 2011, the main producers of potash were Canada with 11.2 million tonnes (Mt) followed by Russia (7.4 Mt) and Belarus (5.5 Mt). The three accounted for about 65% of the world production of 37 Mt, which was up from 33.7 Mt in 2010.

In Australia, some minor historic production of potash include an operation at Buladelah Mountain, New South Wales, where alunite KAl3(SO4)2(OH)6, was mined between 1890 and 1926 and again from 1935 to 1952, for a total production of 75 000 tonnes. Crude potash in form of the soluble salt glaserite (K,Na)2SO4, was produced from Lake Chandler (WA) during 1943 to 1950 for a total of 9218 tonnes.

In 1973, Geoscience Australia's predecessor, the Bureau of Mineral Resources, reported that Texada Mines Pty Ltd was working towards becoming Australia's first local potash producer in the form of langbeinite K2Mg2(SO4)3 at Lake Macleod in northwest WA. The planned capacity of the proposed plant was variously reported to be from 80 000 to 200 000 tonnes per annum (tpa). There is no record of production of potash from the proposed operation.

Australia imports all its potash requirements and according to the Australian Bureau of Agriculture and Resource Economics and Sciences (ABARES) Australian Commodity Statistics 2010, the imports of potassium fertiliser amounted to 210.6 kilotonne (kt) in 2007-08 and 339.8 kt in 2008-09.

World Ranking

According to the United States Geological Survey, the countries with the largest economic resources of potash (K2O) in 2011 were Canada 4.4 gigatonnes (Gt), which represents about 46% of the total world resource, followed by Russia with 3.3 Gt (35%) and Belarus with 0.75 Gt (8%).

Industry Developments

Lake Disappointment (WA): Located in the Gibson Desert of WA about 320 kilometres (km) east of Newman, Lake Disappointment is a modern playa lake covering approximately 1600 square kilometres. Potash mineralisation occurs in lacustrine sediments of the lake and in the entrained brine.

On 13 March 2007, Reward Minerals Ltd published a lower estimate of 7705 Mt Indicated Resource at 3.17 kilograms per tonne (kg/t) K2SO4 containing 24 Mt K2SO4 and an upper estimate of 8635 Mt at 3.17 kg/t K2SO4 containing 27.37 Mt K2SO4. The difference between the upper and lower figure is the result of assumptions about the depth and area for the lake margins. On 30 October 2012, Reward Minerals lodged the Lake Disappointment Project Mining and Indigenous Land Use Agreement with the Native Title Tribunal for registration as an indigenous land use agreement (ILUA) between the Martu representative body Western Desert Lands Aboriginal Corporation (Jamukurnu-Yapalikunu), Holocene Pty Ltd and Reward Minerals Ltd. Reward Minerals has been granted a Mining Lease and a Miscellaneous Licence and is seeking to advance the next phase of the Lake Disappointment project through exploration and feasibility stages.

Lake Chandler (WA): On 29 January 2009, ActivEX Limited announced a JORC Code compliant Inferred Resource of 5 779 025 tonnes at 5.73% K2O at its Lake Chandler potash deposit 45 km north of Merredin and 300 km east of Perth in WA. The company stated in its 2010 annual report that it carried out a scoping study on a nominal throughput of 200 000 tpa to give the project a mine life of 25 years. The company concluded that the study showed that, with the softness of the potash market, the project would be only marginal under current economic conditions.

Lake MacKay (WA,NT): Situated in the Gibson Desert and straddling the WA/NT border 50 km north of the Tropic of Capricorn, Lake MacKay is a modern, playa lake with a surface area of more than 2250 square kilometres. Reward Minerals reported in its 2009 annual report that it has delineated a JORC Code compliant Inferred Resource at Lake MacKay of 4780.4 million bench cubic metres (BCM) at 4.3 kilograms (kg) of K2SO4 (SOP) per BCM for a total of 20.56 Mt of K2SO4.

The resource estimate was calculated on the basis of lake bed sediment volume of BCM to a depth of two metres and the water soluble potassium sulphate content of the sediments that lie within the company's tenement holdings.

The company reported in its annual report for 2011 that the next stage of development at Lake MacKay will involve infill drilling, construction of pilot ponds and pump testing as well as flow sheet development for the preparation of a project feasibility study.

Prior to committing to this phase the company has engaged in discussions with the Tjamu Tjamu people and other traditional owner groups aimed at reaching agreement on terms that would be acceptable for development to proceed at Lake Mackay in the event feasibility analysis proved favourable39.

Dandaragan Greensands Project (WA): Potash West NL is exploring the potential for producing potash from greensand deposits in the Perth Basin, located between 50 and 230 km north of Perth40. The company is investigating the possibility of using conventional magnetic separation techniques to separate glauconite from greensands and is conducting laboratory-scale testing to produce marketable potash products from glauconite concentrate41. On 11 October 2012, Potash West announced an initial Indicated and Inferred Resource of 244 Mt at 3% K2O and 1.6% P2O5 for the Dinner Hill deposit containing the Molecap Greensand and the Poison Hill Greensand stratigraphic greensand units. On 16 November 2012, the company reported that a scoping study for the project was planned to be completed by the end of 2012 and a bankable feasibility study was to be completed by the end of 2013.

Karinga Creek Project (NT): Rum Jungle Resources Ltd, in a joint venture with Reward Minerals Ltd, was analysing potassium, magnesium and sulphate levels in aquifers surrounding Karinga Creek Lakes, about 225 km southwest of Alice Springs in the NT42. On 5 November 2012, Rum Jungle Resources announced an Inferred Resource of 5.5 Mt of sulphate of potash (K2SO4) for the Karinga Creek potash deposit43.

Endnotes

39 Reward Minerals Ltd, 2012. Reward Minerals Ltd annual report 2011. 64pp.

40 Potash West NL, 2010. Prospectus, 96 pp.

41 Potash West NL, 2012. Potash West succeeds in producing potash from WA glauconite deposits. Announcement to the Australian Securities Exchange, 23 January 2012, 3 pp.

42 Rum Jungle Resources Ltd, 2011. Karinga Creek potash update. Announcement to the Australian Securities Exchange 20 December, 2010. 6 pp.

43 Rum Jungle Resources Ltd, 2012. Upgraded Karinga Creek Potash brine resource estimate. 6pp.