Bushranger Pre-Concentration Test Results

RNS Number : 6536G
Xtract Resources plc
20 July 2023
Xtract Resources Plc
(“Xtract” or the “Company”)

Bushranger Pre-Concentration Test Results  


The Board of Xtract Resources Plc (“Xtract” or the “Company”) is pleased to announce the results from a study to determine the applicability of the “TOMRA” method to pre-concentrate copper-gold mineralisation from the Racecourse Mineral Resource on the Bushranger Copper-Gold Project (“Project”) in central New South Wales, Australia.


·    Completion of initial metallurgical test work with pre-concentration ore sorting of Racecourse samples using “TOMRA” ore sorting technology involving X-Ray Transmission and machine learning to sort mineralisation into a pre-concentrated ore product and waste.

·    All samples processed with TOMRA achieved upgrades to the copper content of the pre-concentrated material, with results in recovery varying depending on the quantity of sulphide in each sample.

·    A higher-grade sample assaying 0.56% Cu upgraded well with TOMRA treatment however with low metal recovery due to higher metals content in waste fractions, suggesting that pre-concentration may not be beneficial for higher-grade ore.

·    Excluding the higher-grade sample, the average input grade of typical grade copper-gold mineralisation was 0.23% Cu, which was upgraded to 0.35% Cu, giving a grade uplift of 52%. 

·    The average mass yield was 36%, indicating that 64% of the original mass of the samples was rejected into the waste product, suggesting that ore sorting has the ability to increase the ore grade whilst reducing the mass to be treated.

·    Pre-concentration results for gold also showed a grade uplift using the TOMRA system, however the results are of limited significance to the overall project.

·    TOMRA recommended additional testing on different sample material, particularly higher-grade material to gauge amenability to ore sorting.

·    Xtract has engaged Optimal Mining Solutions (Pty) Ltd of Australia (“Optimal Mining”) to incorporate the most recent TOMRA results into an updated economic model for the overall Bushranger Project. 

Colin Bird, Executive Chairman said: “We are pleased with the results from the TOMRA pre-concentration study which demonstrate that we could achieve significant upgrades to copper mineralisation in the pre-concentrated product, while rejecting a lot of the initial material into waste. The higher-grade sample did not benefit from ore sorting suggesting that the first 4 to 5 years of open pit development when grades are significantly higher than the Project average grade may not require pre-concentration.

The continuing economic study by independent consultants Optimal Mining will model the impact of TOMRA pre-concentration on the overall economics of the Project, while we also consider other pre-concentration routes for Bushranger ore and we look forward to releasing an updated economic model for the Bushranger Project.”

Bushranger Project TOMRA Pre-Concentration Study

Following conclusion of the Phase 2 drilling programme on the Bushranger Copper-Gold Project in central New South Wales, Australia, and the finalisation of the upgraded Mineral Resource for the Racecourse Prospect, Xtract undertook pre-concentration test work on five composite samples from four drill holes. Pre-concentration of mineralisation reduces the amount of material needed to be milled and placed through a flotation processing plan, which in turn can reduce pre-production capital and operating costs, with subsequent improvements in the overall economic performance of a project.

Xtract engaged TOMRA Sorting Solutions (“TOMRA”) of Sydney, Australia, to undertake the pre-concentration test work on the five samples. Data was collecting using TOMRA’s COM X-Ray Transmission (“XRT”) system. The COM XRT system detects mineralised particles and then sorts the material into a pre-concentrated product and waste using amplified mechanical, hydraulic or pneumatic processes. The sorter is set up / trained using images taken of the samples.  The images are then analysed using proprietary TOMRA image processing software. Based upon the images sorting task specific algorithms are then developed and applied to sorting the mineralised material.

The Racecourse Prospect samples were submitted for TOMRA pre-concentration test work as detailed in Table 1.

Table 1 – Bushranger Prospect Drill Samples Submitted for TOMRA Analysis

Run Drill Hole From (m) To (m) Interval (m) Cu%
1 BRDD_21_036 61.00 89.00 28.00 0.20
2 BRDD_21_010 180.00 198.00 18.00 0.24
3 BRDD_21_022 290.00 308.00 18.00 0.25
4 BRDD_21_021_B 227.00 243.00 16.00 0.56
5 BRDD_21_021_A 173.00 187.00 14.00 0.21


For the training of the XRT sorter, samples were exposed to high energy X-rays, which project an image onto a sensor. The X-ray sensor signal depends on atomic density and material thickness and gives information on the inner composition of the particles. By combining two energy levels simultaneously, it is possible to differentiate particles by their atomic densities and then separate material into a pre-concentrated product and waste.

The results of the TOMRA pre-concentration are given in Table 2.

Table 2 – Bushranger Prospect Drill Samples Results of TOMRA Analysis

Run Number 1 2 3 4 5 Avg. Avg. (excl. high grade run 4)
Cu Grade of Original Sample (Cu%) 0.20 0.24 0.25 0.56 0.21 0.29 0.23
Back Calc. Original Grade (Cu%)* 0.15 0.26 0.32 0.52 0.20 0.29 0.23
Product Grade (Cu%) following Pre-Conc. 0.35 0.35 0.41 0.94 0.30 0.47 0.35
Waste Grade (Cu%) 0.067 0.20 0.23 0.50 0.16 0.23 0.16
Original Mass (Kg) 22.5 32.7 10.5 13.7 11.9 18.3 19.4
Pre-Conc. Product Mass (Kg) 7.1 12.2 5.1 0.7 3.3 5.68 6.9
Waste Mass (Kg) 15.4 20.5 5.4 13 8.6 12.6 12.5
Original Contained Cu (kg) 3.4 8.5 3.4 7.1 2.4 5.0 4.4
Pre-Conc. Product Contained Cu (kg) 2.4 4.2 2.1 0.66 1.0 2.1 2.4
Mass Yield (%) 31.6 37.3 48.6 5.1 27.7 30.0 36.3
Metal Recovery (%) 72.6 49.6 62.1 9.3 32 45.1 54


*Back calculation of initial Cu grade from final product for mass balance purposes                                                             

Table 2 details the masses and Cu assays for the pre-concentrated materials produced from this set of test work, as well as the back-calculated initial sample copper grades. The back-calculated copper grades are slightly different to the original copper grades as detailed in Table 1, due to the natural variability of the copper mineralisation.

The primary sorting task was to produce a high-grade product fraction by way of sulphide classification and ejection in a single stage for each sample. All runs conducted for this set of test work were “Dual-Energy” XRT runs. This form of processing is designed to classify and eject relatively high-density sulphides away from the relatively low-density host-rock. All samples were screened to a 20-40mm particle size with the exception of Run 1 (BRDD21_010_Comp) which was run at 25-75mm.

All five samples processed with TOMRA achieved upgrades to the copper and gold content of the pre-concentrated ore, while rejecting significant volumes of waste material, with one higher grade sample (Run 4) being an outlier. Excluding the outlier, the average original grade of the four samples of copper-gold mineralisation was 0.23% Cu, while the average grade of the pre-concentrated mineralisation was 0.35% Cu, which shows a grade uplift of 52%.  The average mass yield was 36%, meaning that 64% of the original mass of the sample was rejected into the waste product, suggesting that it will be possible to greatly reduce the volume of material needed to be processed through the milling and floatation circuits of a processing plant.

The TOMRA pre-concentration results do exhibit a significant amount of variability depending on the quantity of sulphides in the original composite drill core samples. The outlier was Run 4, which had the highest original feed grade material (0.52% Cu), achieved the highest sorted product grade (0.94% Cu), but in a very low mass (mass yield of 5.1%). This suggests that higher-grade material may not benefit from ore sorting to the same extent as the more typical deposit grades and would be more suited to direct processing.

The results overall show the potential of the TOMRA system to significantly increase the copper grade into a pre-concentrated product while rejecting potentially over 50% of the original rock mass into waste. The variability of the results indicate that more samples would need to be tested in order to determine an accurate average overall effect for TOMRA pre-concentration. 

The pre-concentration results are sufficiently positive for the effects of TOMRA pre-concentration to be incorporated into the overall financial model for the Bushranger Project.  Consequently, Xtract has engaged Optimal Mining Solutions (Pty) Ltd of Australia (“Optimal Mining”) to incorporate the TOMRA results into an updated economic model for the overall Bushranger Project.


Further information is available from the Company’s website which details the company’s project portfolio as well as a copy of this announcement: www.xtractresources.com


The information contained within this announcement is deemed by the Company to constitute inside information as stipulated under the Market Abuse Regulations (EU) No. 596/2014 as it forms part of UK Domestic Law by virtue of the European Union (Withdrawal) Act 2018 (“UK MAR”).

The person who arranged for the release of this announcement on behalf of the Company was Colin Bird, Executive Chairman and Director.


Xtract Resources Plc Colin Bird,

Executive Chairman


+44 (0)20 3416 6471


Beaumont Cornish Limited

Nominated Adviser and Joint Broker

Roland Cornish

Michael Cornish

Felicity Geidt

+44 (0)207628 3369



Novum Securities Limited

Joint Broker                  


Jon Belliss

Colin Rowbury 


+44 (0)207 399 9427



Qualified Person

In accordance with AIM Note for Mining and Oil & Gas Companies, June 2009 (“Guidance Note”), Colin Bird, CC.ENG, FIMMM, South African and UK Certified Mine Manager and Director of Xtract Resources plc, with more than 40 years’ experience mainly in hard rock mining, is the qualified person as defined in the Guidance Note of the London Stock Exchange, who has reviewed the technical information contained in this press release.


The following is a summary of technical terms:

“Cu” Copper
“mineralisation” Process of formation and concentration of elements and their chemical compounds within a mass or body of rock




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