Pilbara alliances and project –
Lithium Australia NL (‘LIT’) has established a regional footprint in Western Australia’s rapidly emerging, world-class lithium province in the Pilbara (see Figure 1), as follows.
- LIT and Pilbara Minerals Limited (‘PLS’) have entered into an agreement to establish the SiLeach® joint venture on a 50:50 basis, with the aim of producing lithium carbonate or lithium hydroxide from a SiLeach® processing plant fed by PLS’s spodumene concentrate.
- LIT has made application for four exploration licences in prospective geological terrain – the Hillside project.
- LIT’s Moolyella project near Marble Bar and adjacent to the historic Moolyella tin field host lithium micas in pegmatite veins.
LIT/PLS technology alliance
Worldwide, the Pilgangoora lithium-tantalum project of PLS is one of the larger of the new lithium ore (spodumene) deposits, with a globally significant hard-rock spodumene resource. It has long been recognised that lithium micas, principally lepidolite, are associated with the spodumene mineralisation at Pilgangoora. Lithium hosted by lepidolite is largely ignored through the conventional spodumene treatment process and reports to the waste stream. LIT’s memorandum of understanding (‘MoU’) with PLS allows LIT to evaluate the Pilgangoora deposit for lepidolite mineralisation and its potential as a value-add opportunity to the project.
Using technologies developed in-house for detecting lithium in soils, LIT has delineated a large lithium anomalous area – the Triple Creek anomaly – separate to the main zone of spodumene mineralisation at Pilgangoora. LIT plans to further define the extent of the anomaly and its mineralogy.
Terms of the MoU
In November 2014, LIT announced the execution of an MoU with PLS to test the lepidolite potential of the PLS-owned Pilgangoora project, located in the Pilbara region of Western Australia, which is southeast of Port Hedland. The aim of the collaboration was to evaluate the potential of lithium mica mineralisation at Pilgangoora to produce high-grade lithium carbonate for use in advanced hi-tech batteries.
Under the terms of the agreement, LIT will report on the ways in which the combined expertise of both companies can be optimised. The aim is to enable more complete exploitation of Pilgangoora’s lepidolite mineralised areas by providing feed to produce lithium carbonate for the rapidly expanding global lithium battery industry.
PLS’s 100%-owned Pilgangoora lithium-tantalum project is located 120 kilometres (‘km’) from Port Hedland in the resource-rich Pilbara region. As noted, it is one of the largest new lithium ore (spodumene) deposits in the world, with a globally significant hard-rock spodumene reserve with further exploration potential.
A 2 Mtpa Definitive Feasibility Study (‘DFS’) completed in September 2016 demonstrated the technical and financial viability of progressing the Pilgangoora development. The first direct shipping ore from the mine was exported through Port Hedland in June 2018. Plant commissioning also commenced in early June, with first concentrates produced later in the month.
Exploration by LIT
In January 2016, LIT announced the results from a high-resolution, soil geochemical survey targeting the pathfinder elements indicative of lithium micas, or their derivatives, present in the soil profile. A significant geochemical anomaly defined in the northwest of the project area had a chemical signature typical of lithium micas (see Figure 2). Importantly, the anomaly is separate to the spodumene-bearing lithium mineralisation.
Known as the Triple Creek Zone, this unique high response is more indicative of lithium micas than the more generalised geochemical response over the main pegmatite zone. It is now a major target for further evaluation. In general, such occurrences are close to the lithium pegmatites and have resulted from weathering and dispersion in the soil profile. LIT will now focus on determining the mineralogy and extent of these deposits.
SiLeach® development programme
LIT developed SiLeach® – a universal process for the recovery of metals from silicates – with the assistance of Australian federal government grants and a Western Australian government grant, as well as the technical assistance of ANSTO Minerals (‘ANSTO’), a division of the Australian Nuclear Science and Technology Organisation.
Pilot testing of spodumene concentrates from PLS’s Pilgangoora deposit was completed in early 2017 at ANSTO. The test run produced the following outcomes.
- Pilot SiLeach® operations successfully recovered lithium from Pilgangoora spodumene concentrates without the requirement for roasting.
- Despite operations suffering mechanical disruptions, lithium extractions into pregnant liquor solution of up to 73% were achieved.
- Sufficient pregnant liquor was recovered to continue with lithium carbonate refining tests.
- Data valuable for improving plant viability was generated.
Lithium was successfully recovered from refractory alpha-spodumene (that is, unroasted spodumene) throughout the pilot run. This resulted in extractions – based on pregnant liquor solution analyses – that ranged from 62% up to 73%. It is expected that elimination of mechanical and material handling interruptions to plant throughput will have a significant positive impact on future lithium recoveries. LIT and ANSTO will now review pilot plant designs ahead of follow-up pilot studies of SiLeach® on spodumene later in 2017.
The Hillside project comprises four contiguous exploration licence applications with a combined area of 102 km2, located 80 km southwest of Marble Bar (see Figure 3). There, tin and tantalite minerals were mined previously from pegmatites reported to contain the lithium micas lepidolite and zinnwaldite.
Regionally, the project is located within the East Pilbara granite-greenstone terrain, which is characterised by granitic rocks of the Shaw Batholith. Metamorphosed granitic rocks of the Archean Tambina, Split Rock and Callina Supersuites in the centre and southeast of the project area dominate the local geology The granites have intruded older Archean rocks of the Pilbara Supergroup, composed of mafic and felsic volcanic rocks, with minor sedimentary and intrusive rocks. These units underlie much of the western and northern parts of the tenure. The granitic rocks contain extensive swarms of late-stage pegmatites, the source of the tin and tantalum mineralisation in the area.
The Hillside tenure is located adjacent to several tin and tantalum deposits known collectively as the Shaw River mining area. Historically, one of the larger historical operations was the Cooglegong mining centre. Mining commenced in the Shaw River field in 1893, with sporadic operations producing from alluvial and elluvial deposits. Later, Greenbushes Tin Ltd consolidated the area’s holdings, undertaking extensive sampling programmes from 1978 to ’82. However, uncertainty and fluctuations in metal prices prevented further development of the tin occurrences in the area.
In 1980-81, workings at Trigg Hill – located in the centre of the Hillside project area – were exploited in a small-scale alluvial operation that produced tantalite and cassiterite concentrates. The mineralisation there is associated with pegmatite intrusions, which in some cases form up to 5% of the outcrop pattern. The pegmatites at Trigg Hill are reported to contain not only tin and tantalum but also the lithium minerals lepidolite, zinnwaldite and spodumene. Despite this, no focused exploration to evaluate the lithium potential of the ground has ever been undertaken.
LIT will begin by undertaking desktop studies and compiling a database using open-file data and company reports. On grant of the tenure, LIT will commence field mapping and sampling, to evaluate the lithium potential of the numerous pegmatites in the area. Soil geochemical surveys will be undertaken, using cutting-edge technology (laser-induced breakdown spectroscopy or LIBS), to provide real-time lithium assays that will help delineate concealed mineralisation. Open-file geophysical surveys will also be acquired and processed, to provide a better understanding of structural controls on pegmatite emplacement.
LIT has also acquired Exploration Licence 45/4766, adjacent to the historic Moolyella tin field in the Pilbara region of Western Australia (ASX: LIT 20 April 2018). The Moolyella project, which lies 160 km southeast of Port Hedland and 20 km east-southeast of Marble Bar, has an area of 3 km2. Tin-mining operations at Moolyella were mostly continuous from its discovery in 1898 until 1986.