lobal Securities News
Analysis: what a proof-of-concept sort settles, and what it leaves open
The test answers a narrow question well. Sulphide at Orient is coarse enough and dense enough that a density-based sorter can find it, and that is not a given at every silver-lead-zinc deposit. Fine-grained or disseminated mineralisation defeats XRT because the individual particles do not differ enough from the host rock. The images and assays here show the opposite case.
The harder question is what fraction of a real plant feed the sorter would ever see. Iltani states plainly that the samples were RC chips, that crushing chips generates a large fines fraction, and that the below 6 mm material was excluded from the tests. A 58 per cent mass rejection on the coarse fraction therefore does not translate into a 58 per cent reduction in mill throughput. It sets an upper bound on what sorting could do to one size fraction, and leaves the plant-level number to be determined once whole PQ core, which crushes with fewer fines, has been through the same equipment.
The two runs also pull in different directions commercially. The high-grade run rejected mass while roughly doubling grade, which is a throughput story: less rock through the mill for the same contained metal. The low-grade run rejected almost everything and lifted grade by an order of magnitude, which is a different proposition, namely whether material that would otherwise sit in a waste dump can be turned into plant feed. Garner referred to exactly that possibility, describing the potential to upgrade mineralised waste to higher-grade feed. The economics of the two cases are not interchangeable, and neither has been costed. No metallurgical recovery, production target or capital estimate has been published off the back of this work.
A careful reader looking for the next check would watch three things. Whether the PQ core results, run on roughly 700 kg of material at TOMRA’s Sydney facility, reproduce the upgrade factors once the fines are counted. Whether downstream comminution and flotation tests show that sorted product still floats to a saleable concentrate, given the company’s historical test work points to separate lead-silver and zinc-indium-silver concentrates. And whether sorting assumptions turn up in the resource update Iltani expects in the fourth quarter of 2026 and in the scoping study it has flagged for 2027, which is where any of this would first carry a number attached to money.
What the documents say
Iltani Resources Limited (ASX: ILT) told the market on 17 July 2026 that TOMRA had finished first-pass X-ray transmission sorting tests on drill chips from the Orient Silver-Indium Project at Herberton in North Queensland. The company put the work forward as proof of concept rather than a process design, and it said so in the announcement itself: every mass rejection and upgrade figure quoted is measured against the screened 6 to 25 mm feed that TOMRA actually sorted, not against run-of-mine ore.
That qualification matters more than usual here, because the headline numbers are large. Two samples went to TOMRA, a high-grade parcel weighing 13.5 kg and a low-grade parcel weighing 22.5 kg, both of them reverse circulation chips. Screening split each into a 6 to 25 mm fraction and a fraction below 6 mm. Only the coarse fraction was sorted. The fines were set aside and, as the company acknowledged, their contribution will not be known until later test work.
What the sorter produced
XRT sorting separates particles by atomic density. At Orient the target minerals are galena and sphalerite, both of which absorb X-rays far more strongly than the siliceous rhyolite hosting them, and Iltani attributed the result to that density contrast combined with a coarse distribution of sulphide grains in the tested material.
On the high-grade sample, a single sorting stage sent 42 per cent of the feed mass to product and rejected 58 per cent as waste. Silver in the product rose to 265 g/t from 130 g/t in the feed. Indium went to 427 g/t from 199 g/t. Lead doubled to 3.6 per cent from 1.8 per cent and zinc to 9.1 per cent from 4.3 per cent. The average upgrade factor across the four metals was 2.1.
The low-grade sample behaved differently. Only 4 per cent of the feed mass reported to product, with 96 per cent rejected, and the resulting concentrate carried 325 g/t silver against 26 g/t in the feed, 437 g/t indium against 27 g/t, 7.3 per cent lead against 0.6 per cent and 9.3 per cent zinc against 0.8 per cent. Individual upgrade factors ranged from 11.5 for zinc to 16.1 for indium, averaging 13.2. Managing director Donald Garner singled those out, saying the results “clearly demonstrate that ore sorting works, and works well.”
The reported waste fractions are the other half of the picture. On the high-grade run the reject assayed 33 g/t silver, 35 g/t indium, 0.5 per cent lead and 0.9 per cent zinc. On the low-grade run it assayed 13 g/t silver, 9 g/t indium, 0.3 per cent lead and 0.4 per cent zinc. Both are low relative to their feeds, which is what tells the company that most of the sulphide reported to the product rather than being thrown away.
The deposit the sorting would serve
Orient sits about 120 km south-west of Cairns and forms part of a Herberton tenement package of roughly 370 sq km. Iltani has published a resource estimate for the combined Orient East and Orient West deposits of 62.5 Mt at 81.5 g/t silver equivalent using a 30 g/t silver equivalent cut-off, with a higher-grade core of 34.2 Mt at 31.3 g/t silver, 16.9 g/t indium, 0.74 per cent lead and 0.90 per cent zinc, or 110.4 g/t silver equivalent, at a 60 g/t cut-off. Within that higher-grade core, 21.5 Mt is classified Indicated and 12.7 Mt Inferred. The company describes Orient as the largest known silver-indium deposit in Australia.
Drilling has continued through the year. The June quarter report records two RC rigs mobilised for an infill and expansion program of 115 holes for 16,000 m, of which 67 holes for 12,761 m had been drilled by 30 June, with a cash balance of $7.52 million at quarter end. On 11 August the company reported assays from a further 13 holes, including 2 m at 1,456 g/t silver equivalent from 84 m in ORR170 and 42 m at 140 g/t silver equivalent from 120 m in ORR178.
Next steps the company has set out
Iltani has begun planning a seven-hole PQ diamond program, using 85 mm diameter core, to generate representative sample. That feeds bulk sorting test work of about 700 kg at TOMRA’s Sydney facility, evaluation of performance across multiple size fractions and mineralisation styles, and comminution and flotation work on both sorted product and reject. The company says the outcome will be folded into flowsheet development and later economic studies. Drilling on the initial 110-hole program was, as at 11 August, expected to finish in about five weeks.
