Xtract Resources plc Bushranger ore pre-concentration study results

RNS Number : 2658H

Xtract Resources plc

08 October 2024

 

 

For immediate release

 

8 October 2024

 

Xtract Resources Plc

("Xtract" or the "Company")

Encouraging Results Obtained from Ore Pre-Concentration Study

for Bushranger Copper-Gold Project

 

The Board of Xtract Resources Plc ("Xtract" or the "Company") is pleased to announce the results of a metallurgical study by Altrius Consulting which investigated three methods to pre-concentrate copper-gold mineralisation from the Racecourse Mineral Resource on the Bushranger Porphyry Copper-Gold Project ("the Project") in central New South Wales, Australia.  The objective of ore pre-concentration is to reduce the operating costs for producing a copper-gold mineral concentrate from the Racecourse Mineral Resource. 

 

Highlights

 

·    An earlier Altrius review (refer to RNS dated 18 June 2024) concluded that Bushranger mineralisation was not amenable to upgrade by the Tomra ore sorting method, but recommended investigation of alternative pre-concentration technologies which could significantly improve project economics.

 

·    Xtract therefore investigated the effectiveness of "Pre-Screening", "Gravity Separation" and "Coarse Particle Flotation" as techniques to pre-concentrate the mineralisation from the Bushranger Mineral Resource.

 

·    Mineralisation from drill holes BRDD21-036, BRDD22-053, BRDD21-022 were combined into two composite samples, with one sample being used for Pre-Screening and Gravity Separation tests, while the second sample was used for the Coarse Particle Flotation ("CPF") test work.

 

·    CPF test work, using the NovaCell^TM Kinetic Test Work, showed encouraging results with 78% of the copper mineralisation recovered into only 5% of the mass, with the head grade of the composite sample of 0.19% Cu being upgraded into a pre-concentrate product of 2.8% Cu.

 

·    NovaCell^TM coarse particle flotation also recovered 30% more copper than conventional flotation.

 

·    By contrast, upgrading of the Racecourse mineralisation by pre-screening and simple dense media separation did not achieve positive results, probably due to the disseminated nature of the chalcopyrite within the host rock.

 

·    In a further positive development, the Company has been advised that EL5574, the main tenement encompassing the Bushranger copper-gold deposits, has been renewed in full for an additional three years until 4 June 2027.

 

Colin Bird, Executive Chairman said: "The pre-concentrate test work on copper-gold mineralisation from the Racecourse deposit on the Bushranger Project has shown encouraging results with coarse particle flotation using NovaCell^TM technology, demonstrating the potential to increase the grade of copper concentrates and recover up to 30% more copper.  The NovaCell^TM process captured 78% of the originally contained copper while rejecting 95% of the original rock mass and this will have significantly positive effects on the costs to process the copper-gold mineralisation from the Racecourse Mineral Resource.  As the average grade of the world's overall copper resources continues to fall, ore pre-concentration will become an increasingly important part of the process to allow copper mineral resources to be economically mined and it is pleasing to see that the copper-gold mineralisation from the Racecourse deposit responds well to ore pre-concentration. We will carry out more detailed test work on the most appropriate methodologies with a low-cost budget and if appropriate introduce the revised technical parameters into the financial model. At current and forecasted copper prices, the project is demonstrating the potential to be one of the next global contributors to the copper deficit. We will keep shareholders informed on the technical and financial results as they progress"

 

Ore Pre-Concentration Test Work Program on Mineralisation from the Racecourse Mineral Resource

From July 2021 until July 2022, Xtract completed a Phase 2 diamond drilling programme at the Racecourse and Ascot prospects on the Bushranger Project in central New South Wales, Australia.  Following conclusion of the Phase 2 drilling program independent consultants, "The Measured Group", based in Brisbane, Australia reported a Mineral Resource of 512Mt @ 0.22% CuEq, at a cut-off of 0.1% CuEq*, and classified as Inferred and Indicated in accordance with JORC (2012) (refer to RNS 23 November 2022), for the Racecourse Prospect.

 

[*CuEq % = (Cu%) + (Au g/t * 0.6577)% + (Ag g/t * 0.008769) %

Cu Price = US$8800/t, Au Price = US$1800/oz, Ag Price = US$24/oz]

 

Mining studies by Optimal Mining on the Bushranger Gold-Copper Project, completed in 2022 and 2023, concluded that a minimum production rate of 20 Mtpa, and copper price in excess of US$10,000/tonne, are required to generate a positive Net Present Value ("NPV") from open pit mining of the Racecourse Mineral Resource (refer to RNS 7 March 2023). To assess the ability of ore pre-concentration to enhance project economics, Xtract contracted Altrius Consulting ("Altrius") to undertake a review of the applicability of ore pre-concentration methods to the Racecourse prospect copper-gold mineralisation (refer to RNS 20 July 2023).  The Altrius review concluded that ore-concentration technologies may benefit processing of the Racecourse copper-gold mineralisation, with a subsequent potential improvement to the overall project NPV.  Altrius recommended that the following pre-concentration techniques had the potential to concentrate the valuable component of the copper-gold mineralisation into a smaller mass for downstream processing (in order of preference):

 

·    Coarse Particle Flotation ("CPF")

·    Gravity Separation via Dense Media Separation ("DMS")

·    Pre-Screening of run-of-mine ore

 

Metallurgical test work samples from drill holes BRDD21-036 (168m @ 0.14% Cu & 0.06g/t Au), BRDD22-053 (320m @ 0.11% Cu & 0.06g/t Au) and BRDD21-022 (144m @ 0.25% Cu & 0.02g/t Au) were combined into two composite samples.  A 94kg composite sample from drill hole BRDD22-053 (309m to 325m and 383m to 457m), with an average copper grade of 0.18% Cu, was used for the Coarse Particle Flotation test work using NovaCell^TM technology.  A composite sample from drill holes BRDD21-036 and BRDD21-022, with an average copper grade of 0.24% Cu and 0.05g/t Au, was used for the Gravity Separation and Pre-Screening test work.

 

Coarse Particle Flotation Using NovaCell^TM Technology

 

To test the applicability of the NovaCell^TM technology to process mineralisation from the Racecourse Mineral Resource, the combined sample with head grade of 0.18% Cu from drill hole BRDD22-053, was subjected to a Coarse Particle Flotation test.  The flotation sample was crushed to achieve a flotation feed of P₁₀₀ of 600µm, following which the pulp was diluted to achieve a pulp density of 32% solids.  A standard flotation scheme was adopted with a PAX collector (80g/t) and MIBC as the frother.  Three concentrates were recovered over a total flotation time of 5 minutes.

 

Using the NovaCell^TM process, Coarse Particle Flotation delivered encouraging results with 80% of the copper in the original combined sample of 0.18% Cu, being recovered into a pre-concentrated product of 2.1% Cu.  The mass yield to concentrate was 11%.  The results of the Coarse Particle Flotation test using NovaCell^TM technology are given in Table One.

 

Table 1 - Coarse Particle Flotation Test using NovaCell^TM technology

 

Sample		Assayed Grade			Recovery (%)		Mass Yield
	Cu (%)	Au (g/t)	S (%)	Cu	Au	S	(%)
Feed	0.18	N/A	0.454	-	-	-	100
Concentrate 1 (Froth)	2.07	N/A	5.19	70.5	N/A	71.7	6.3
Concentrate 2 (Screen)	0.36	N/A	1.09	9.1	N/A	11.1	4.6
Tails	0.04	N/A	0.09	20.4	N/A	17.2	89.1

During the 350μm scoping test, it was observed that an excessively weak concentrate was produced, with this a possible contributor to the reduced copper recovery. Following on from this, a NovaCell^TM kinetic test was implemented, using a marginally finer grind size (P80 of 350μm) with a reduced frother addition, to generate a more consistent froth phase.

This kinetic test yielded no marked improvement in recovery with 78% of the copper in head (0.19%) recovered into a concentrate containing 2.8% copper. The finer grind did however improve liberation and the mass yield to concentrate reduced from 11% to 5%. The finer grind also resulted in an increase in flotation kinetics, with the original scoping test (P₈₀ 470μm) requiring 40 minutes to achieve 80% copper recovery, compared with the 25 minutes required to achieve 78% copper recovery at a P₈₀ 350μm. Results from the repeat coarse particle flotation test are summarised in Table 2.

 

Table 2 - NovaCell^TM Kinetic Test Work Summary

 

Sample		Assayed Grade			Recovery (%)		Mass Yield
	Cu (%)	Au (g/t)	S (%)	Cu	Au	S	(%)
Feed	0.19	N/A	0.469	-	-	-	100
Concentrate 1 (Froth)	2.80	N/A	6.94	78.3	N/A	79.1	5.4
Tails	0.04	N/A	0.09	21.7	N/A	20.9	94.6

 

In order to compare the results of the Coase Particle Flotation Test using NovaCell^TM technology to conventional flotation a parallel standard rougher flotation test was conducted, at the same grind size, following which the pulp was diluted to achieve a pulp density of 31% solids. A standard flotation scheme was adopted with a PAX collector (80g/t) and MIBC as the frother.  Three concentrates were recovered over a total flotation time of 5 minutes.

 

The results of the conventional flotation test are given in Table 3.

 

 

 

Table 3 - Conventional Flotation Test

 

Sample		Assayed Grade			Recovery (%)		Mass Yield
	Cu (%)	Au (g/t)	S (%)	Cu	Au	S	(%)
Feed	0.18	N/A	0.426	-	-	-	100
Concentrate 1 (Froth)	4.63	N/A	11.19	50.5	N/A	51.4	2.0
Tails	0.09	N/A	0.211	49.6	N/A	17.2	98.0

 

The coarse particle flotation mechanical test yielded a copper recovery of 51%, from a head grade of 0.18% Cu, into a concentrate of 4.6% Cu.  The mass yield was 2%.

 

In comparison to a conventional mechanical flotation process, Coarse Particle Flotation using the NovaCell^TM technology yielded superior flotation results with overall copper recovery being 30% higher using the NovaCell^TM technology.

 

Pre-Screening

 

Pre-screening is a pre-concentration technique which exploits the natural deportment of mineralisation into finer size fractions following initial crushing in a mineral processing plant.  The objective is to reject course, unmineralized material into oversize waste and concentrate the "enriched" finer sized material.  This technique is most applicable to mineralisation associated with natural fracture patterns or with mineralisation occurring on mineral / waste grain boundaries.

 

To test the applicability of pre-screening to the copper-gold mineralisation of the Racecourse Mineral Resource, a composite 118kg sample (Comp BRDD21) was produced from drill holes BRDD21-022 (290m to 350m) and BRDD21-036 (121m to 169m).  The average copper grade of the composite sample was 0.21% Cu.

 

The composite sample was subjected to simple screen sizing to establish if any upgrading of the sample could be achieved by crushing the sample to a P₁₀₀ of 12mm.  The crushed product was then screened, using a 6mm screen, with the oversize (-12mm to +6mm) and undersize fractions subjected to assaying to determine the deportment of copper and gold into the two size fractions.  The results of the pre-screening test work are given in Table 4.

 

Table 4 - Pre-Screening Test Work Summary of +6mm

 

Sample	Size Fraction	Mass (g)	Assays		Distribution	(%)
			Au (g/t)	Cu (%)	Au	Cu
Comp BRDD21	-12 mm to +6mm	10,362	0.01	0.15	18.3	57.7
Comp BRDD21	-6mm to +3.5mm	1,785	0.12	0.19	37.8	12.4
Comp BRDD21	-3.5mm to +1mm	1,631	0.04	0.23	11.5	13.5
Comp BRDD21	+38µm	1,053	0.08	0.34	14.9	13.1
Comp BRDD21	-39µm	168	0.59	0.54	17.5	3.3

 

Analysis of the pre-screening results shown above in Table 4 concluded that upgrading the copper content into a fines fraction could not be achieved by crushing the sample to 100% passing a size of 12mm.  The +6mm size fraction returned a copper grade of 0.15% whilst the -6mm fraction returned a copper grade of 0.23%, in line with the head sample assay of 0.24% Cu.  Regarding the metal distribution 57.7% of the copper reported to the +6mm size fraction and 42.3% reported to the -6mm size fraction.

 

In an attempt to improve pre-concentration of copper by pre-screening, finer crush sizes were tested.  The composite sample was crushed to P₁₀₀ of 6mm and screened at 3mm and also to P₁₀₀ of 3mm and screened at 1mm.  Neither of the two finer crush sizes resulted in any improvement in the copper deportment to the finer size fraction.  Therefore, it is concluded that simple pre-screening is not a technique appropriate for pre-concentrating the copper-gold mineralisation from the Racecourse Mineral Resource.

 

Dense Media Separation

 

Dense media separation (DMS), is a gravity separation process whereby particles are sorted primarily according to their densities, by introducing particles to a heavy liquid.  Particles which are lighter than the density of the heavy liquid rise and a referred to as "floats".  Particles heavier than the density of the heavy liquid fall and a referred to as "sinks".  Particles of sulphide mineralisation are usually more dense than the surrounding barren host rock and hence should preferentially report to the "sinks" fraction, allowing the mineralisation to be pre-concentrated.

 

To test the applicability of DMS to pre-concentrating the copper-gold mineralisation from the Racecourse Mineral Resource, the -3.35mm size fraction originating from the pre-screening test work was subjected to heavy liquid DMS separation using a heavy liquid of density 3.3 t/m³.  The results are summarised in Table 5.

 

Table 5 - Dense Media Separation Pre-Concentration Results Summary

 

Sample	Size Fraction		Mass (g)		Distribution	(%)
		Feed	Sinks	Floats	Sinks	Floats
Comp BRDD21	-3.35mm to +1.0mm	485.5	1.4	484.1	0.3	99.7
Comp BRDD21	-1.0mm to +38µm	236.7	3.1	233.6	1.3	98.7

 

 

Using a heavy liquid of density 3.3 t/m³, only 0.3% of the rock mass reported to the "sinks" fraction indicating that DMS is not a technique appropriate to pre-concentrating the copper-gold mineralisation from the Racecourse Mineral Resource.

 

Conclusions

 

Coarse Particle Flotation test work, using the NovaCell^TM technology, showed encouraging results in pre-concentrating the copper-gold mineralisation from the Racecourse Mineral Resource.  80% of the head grade of the composite sample of 0.18% Cu was recovered into a pre-concentrated product of 2.1% Cu.  Furthermore, NovaCell^TM Coarse Particle Flotation delivered superior results in comparison to conventional floatation, recovering 30% more copper. Hence, the use of NovaCell^TM Coarse Particle Flotation should have a positive effect on the economics of open pit mining the Racecourse Mineral Resource.

 

Simple pre-screening and Dense Media Separation do not appear to be techniques effective at pre-concentrating the copper-gold mineralisation from the Racecourse Mineral Resource.

 

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.

 

Enquiries:

 

Xtract Resources Plc	Colin Bird, Executive Chairman	[phone] www.xtractresources.com
Beaumont Cornish Limited Nominated Adviser and Joint Broker	Roland Cornish Michael Cornish Felicity Geidt	[phone] www.beaumontcornish.co.uk
Novum Securities Limited Joint Broker	Jon Belliss Colin Rowbury	[phone] www.novumsecurities.com

 

 

 

 

Qualified Person

Information in this announcement relating to the exploration works has been reviewed by Edward (Ed) Slowey, BSc, PGeo, a consultant to Xtract. Mr Slowey is a graduate geologist with more than 40 years' relevant experience in mineral exploration and mining, a founder member of the Institute of Geologists of Ireland and is a Qualified Person under the AIM rules. Mr Slowey has reviewed and approved the geological content of this announcement.

 

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.

 

Mineral Reserves and Resources

The Company estimates and discloses mineral reserves and resources using the definitions adopted by JORC.  Further details are available at www.jorc.org.  See the "Glossary of Geological and Mining Terms" for complete definitions of mineral reserves and mineral resources.

About Mineral Resources

Mineral resources are not mineral reserves and do not have demonstrated economic viability but do have reasonable prospect for economic extraction.  They fall into three categories: measured, indicated, and inferred. The reported mineral resources are stated inclusive of mineral reserves.  Measured and indicated mineral resources are sufficiently well-defined to allow geological and grade continuity to be reasonably assumed and permit the application of technical and economic parameters in assessing the economic viability of the mineral resource. Inferred mineral resources are estimated on limited information not sufficient to verify geological and grade continuity or to allow technical and economic parameters to be applied.  Inferred mineral resources are too speculative geologically to have economic considerations applied to them. There is no certainty that mineral resources of any category will be upgraded to mineral reserves.

Important Information about Mineral Reserve and Resource Estimates

Whilst the Company takes all reasonable care in the preparation and verification of the mineral reserve and resource figures. the figures are estimates based in part on forward-looking information. Estimates are based on management's knowledge, mining experience, analysis of drilling results, the quality of available data and management's best judgment. They are, however, imprecise by nature, may change over time, and include many variables and assumptions including geological interpretation, commodity prices and currency exchange rates, recovery rates, and operating and capital costs. There is no assurance that the indicated levels of metal will be produced, and the Company may have to re-estimate the mineral reserves based on actual production experience. Changes in the metal price, production costs or recovery rates could make it unprofitable to operate or develop a particular deposit for a period of time.

Forward Looking Statements

Certain statements in this announcement, are, or may be deemed to be, forward looking statements. Forward looking statements are identified by their use of terms and phrases such as ''believe'', ''could'', "should" ''envisage'', ''estimate'', ''intend'', ''may'', ''plan'', ''will'' or the negative of those, variations or comparable expressions, including references to assumptions. These forward-looking statements are not based on historical facts but rather on the Directors' current expectations and assumptions regarding the Company's future growth, results of operations, performance, future capital and other expenditures (including the amount, nature and sources of funding thereof), competitive advantages, business prospects and opportunities. Such forward looking statements reflect the Directors' current beliefs and assumptions and are based on information currently available to the Directors. A number of factors could cause actual results to differ materially from the results discussed in the forward-looking statements including risks associated with vulnerability to general economic and business conditions, competition, environmental and other regulatory changes, actions by governmental authorities, the availability of capital markets, reliance on key personnel, uninsured and underinsured losses and other factors, many of which are beyond the control of the Company. Although any forward-looking statements contained in this announcement are based upon what the Directors believe to be reasonable assumptions, the Company cannot assure investors that actual results will be consistent with such forward looking statements.

 

Beaumont Cornish Limited ("Beaumont Cornish") is the Company's Nominated Adviser and is authorised and regulated by the FCA. Beaumont Cornish's responsibilities as the Company's Nominated Adviser, including a responsibility to advise and guide the Company on its responsibilities under the AIM Rules for Companies and AIM Rules for Nominated Advisers, are owed solely to the London Stock Exchange. Beaumont Cornish is not acting for and will not be responsible to any other persons for providing protections afforded to customers of Beaumont Cornish nor for advising them in relation to the proposed arrangements described in this announcement or any matter referred to in it.

TECHNICAL GLOSSARY

The following is a summary of technical terms:

 

"Ag"	Silver
"Au"	Gold
"Cu"	Copper
"CuEq"	Copper equivalent grade, calculated using assumed metal prices for copper, gold and other metals
"Indicated Mineral Resource"	That part of a Mineral Resource for which quantity, grade (or quality), densities, shape and physical characteristics are estimated with sufficient confidence to allow the application of Modifying Factors in sufficient detail to support mine planning and evaluation of the economic viability of the deposit. Geological evidence is derived from adequately detailed and reliable exploration, sampling and testing gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes, and is sufficient to assume geological and grade (or quality) continuity between points of observation where data and samples are gathered. (JORC 2012)
"Inferred Mineral Resource"	That part of a Mineral Resource for which quantity and grade (or quality) are estimated on the basis of limited geological evidence and sampling. Geological evidence is sufficient to imply but not verify geological and grade (or quality) continuity. It is based on exploration, sampling and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes. (JORC 2012)
"MIBC"	Methyl isobutyl carbinol
"mineralisation"     "µm"	Process of formation and concentration of elements and their chemical compounds within a mass or body of rock   Microns
"PAX"	Potassium amyl xanthate
"porphyry"	A deposit of disseminated copper minerals in or around a large body of intrusive rock
"Mtpa"	Million tonnes per annum

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