Potash explorer Trigg Mining (ASX: TMG) has announced a helicopter-supported drilling program is now underway at its wholly-owned Lake Throssell sulphate of potash (SOP) project in Western Australia.
The program will follow up the results of an auger sampling program undertaken at the project late last year, in which the new high-grade discovery was made.
Last week, Trigg outlined its 2020 field exploration program, which has been designed in two parts.
This initial program will be the first exploration work to be undertaken at the project since the lifting of COVID-19 travel restrictions and involves a 24-hole shallow rotary drilling campaign covering the salt lake (playa) surface.
Trigg managing director Keren Paterson described the Lake Throssell project as the company’s “jewel in the crown” of its SOP portfolio.
“It’s really exciting to have our teams out in the field progressing this flexible, helicopter-supported program that will generate invaluable data to follow-up the high-grade auger drilling results reported late last year,” she said.
Two-phase drilling program
Trigg’s just-launched rotary drilling campaign is designed to target near-surface brine mineralisation to depths suitable for potential trench-based extraction methods.
The company also plans to test areas of observed high-gypsum content, which it said have the potential to “supply high flow rate due to increased porosity and permeability, as well as elevated SOP content”.
Trigg is anticipating completion of the drilling within two weeks of on-ground activity.
Ms Paterson said an infill gravity survey will be undertaken in parallel to “plug any gaps” in the high-quality gravity data the company announced earlier in the year, which identified several priority paleovalley SOP targets.
“This ground-based program will give us the first comprehensive and accurate picture of the entire tenement, and will help us to refine drilling locations for the off-lake and subsequent on-lake air-core programs that we hope to commence in August,” she said.
Following the helicopter-supported initial drilling campaign, Trigg plans to commence a proposed off-lake air core drilling program with the results expected to feed into the reporting of a potential maiden JORC inferred resource.
Lake Throssell discovery
Lake Throssell lies within Trigg’s larger SOP project portfolio, located 170km east of Laverton, WA.
The projects span 1,500sq km and also include Lake Rason, which has a JORC-compliant mineral resource of 6 million tonnes of drainable SOP grading at 5,080 milligrams per litre of SOP.
In December 2019, hand-auger brine samples from Lake Throssell returned high grades of up to 6,660mg/l potassium, or 14,800mg/l SOP equivalent, with an average grade of 5,296mg/l potassium or 11,800mg/l SOP.
At the time of the discovery, Ms Paterson said the high-grade results across the playa and the potential scale of the underlying paleochannel made Lake Throssell “one of the most important discoveries for Australia’s emerging SOP industry and the nation’s food security”.
SOP is considered a premium-quality potash used for fertiliser. Compared to muriate of potash (MOP), it is chloride-free and provides essential macro nutrients for plant growth.
SOP can also be produced sustainably through the solar evaporation of potassium-rich hypersaline brine water, without the need for large open pits or waste-rock dumps.