Mount Ridley Mines has achieved outstanding beneficiation results from samples at its namesake rare earths project near Esperance, with simple screening techniques lifting grades by up to 202 per cent.
Management has described the results as an important breakthrough in identifying the company’s ability to substantially improve the grade of rare earths mineralisation at the project through an inexpensive, simple and broadly adopted processing technique.
Beneficiation is a process known to remove barren minerals from mineralisation to achieve an improvement in grade.
Testing at the Mount Ridley project has shown that 80 per cent of the total rare earth oxides (TREO) at the operation are contained within 50 per cent of the sample mass. The company says the barren portion of the sample can be rejected using simple screening techniques at 75 microns.
Results show an average grade increase of 164 per cent using samples from its Mia and Jody prospects while samples from Mount Ridley’s Vincent target returned a maximum upgrade of 202 per cent.
The company engaged Simulus Group to conduct the beneficiation testwork on 19 samples from 15 drill holes. A total of six prospects were tested with its Fabienne, Winston and Butch targets showing average increases of 158 per cent, 131 per cent and 118 per cent respectively.
Simulus Group used a range of screens with apertures between 500 and 25 microns with the optimum results achieved by screening at 75 microns.
The Company believes that targeted drilling throughout the central zone of the Mia Prospect can generate intersections at grades high enough to ultimately beneficiate above 2,000ppm TREO, which will have a very positive impact on project economics. Mount Ridley Mines chairman Peter Christie
The Mount Ridley project sits about 50 kilometres north of the deep-water port of Esperance in Western Australia and covers a total of 3400 square kilometres.
The explorer recently completed a resource drilling program of 81 air-core holes over 4083m at its Mia prospect where previous exploration identified thick higher-grade mineralisation above 1000 parts per million TREO. All samples are currently being analysed at the laboratory with results expected in late July and early August.
The Mia prospect has produced some impressive results in recent months with a record 36m at 4398ppm TREO including 6m grading 9523ppm TREO reported in May. The latest numbers eclipse earlier Mia results revealed in March of 6m at 6648ppm TREO. Other headline results include an end-of-hole reading of 9m at 3159ppm TREO and 8m grading 3022ppm TREO.
The Mount Ridley project was initially acquired by the company for its nickel and copper sulphide potential. However, that all changed when it re-analysed 1108 samples from previous air core work and found over half the samples contained significantly elevated levels of clay based rare earths that are considered critical to the low carbon energy movement.
Clay based rare earths as opposed to “hard rock” based rare earths have rapidly become a thing over the last two years – largely led by a small army of explorers around the Esperance region that have unearthed massive scale rare earths deposits in clays.
The general view is that clay based rare earths can be mined on very low grades, with many WA company’s tabling grades of between 800ppm and 1200 ppm. In the hard rock world these grades would not fly as they only equate to around 0.1 per cent at 1000 ppm and the market starts to get interested at around 1 per cent in hard rock.
Unlike hard rock however, clays are much softer and considerably easier to mine and so there is now a general embrace of grades of around 1000ppm if it is in clay.
Mount Ridley is starting with grades higher than that in most cases and if it can beneficiate up again for relatively little cost it may well be onto something more interesting than most.
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