15 Aug Bushranger results of metallurgical test work
(“Xtract” or the “Company”)
Bushranger Project – Results of Scoping Metallurgical Test Work Programme
The Board of Xtract Resources Plc (“Xtract” or the “Company”) is pleased to report the results of a scoping metallurgical test work programme carried out on four samples from the Racecourse and Ascot deposits at Bushranger.
· Altrius Consulting (‘ACPL’) developed and managed a scoping metallurgical test work programme to assess the metallurgical response of the copper-gold mineralisation from the Bushranger Project on behalf of the Company
· Four master composite samples of quartered drill core were prepared, based upon a geographic location within the Racecourse and Ascot deposits, namely Racecourse Central, Racecourse North-West, Racecourse South-East and Ascot
· The samples were representative of the anticipated average copper grade of the deposit, ranging from 0.33-0.48% Cu, with minor silver (1.1g/t to 3.3g/t) and trace gold (0.007g/t to 0.04g/t), other than the more gold-rich Ascot sample which assayed 0.30g/t Au
· The test work completed to date has yielded encouraging copper recovery results generally running at 89-90%, other than for the Racecourse North-West sample (76% recovery) where further work is recommended to better understand the different metallurgical response from this area
· Initial test work was focussed on copper recovery not gold, however, the Ascot sample also yielded payable gold and silver in the Cu concentrate
· At Racecourse, sampled intervals were not from areas where gold grade was relatively high, however it was considered that due to the metallurgical performance observed in these areas, that payable gold would probably be achieved with additional optimisation of the recovery circuit and/or in areas where gold grade was slightly higher. Further sampling and test work needs to be completed to confirm this hypothesis
· All concentrates produced payable silver grades. Further work was also recommended targeted at recovering molybdenum
· Test work indicates that the concentrates produced contained no significant penalty elements, with these concentrates considered “clean” and therefore should be readily saleable
Colin Bird, Executive Chairman said: “The results of the test work are considered typical of metal recoveries for deposits on the Lachlan Fold Belt. The Ascot overall gold grade has yet to be determined, so metallurgical work here is still at an early stage. The new report will be used to update the Bushranger concept study and was necessary to further advance the Racecourse project. We are pleased to note that there are no significant penalty elements and concentrate is regarded as clean and saleable.No test work has been directed specifically at molybdenum recovery. Some nearby mines on the Lachlan Fold Belt are recovering molybdenum and, in one case a new circuit has been installed specifically for recovery of the metal. At Bushranger, molybdenum recovery will be disregarded for the concept study for now but could make a contribution to a future mining operation.”
Test Work Details
Samples for the Bushranger Project sighter metallurgical test work programme were selected and sampled (¼ core) from the remaining drill core from the Phase II drilling campaign, conducted within the Racecourse and Ascot deposits. The samples were selected (Table 1), such that four master composite samples were formed, based upon a geographic location within the deposits and representative of the anticipated average copper resource grades, as detailed below:
Table 1 – Core Sample Selection Summary
|(m)||(m)||Cu (%)||Au (g/t)||Ag (g/t)||(kg)|
The weighted mean assay results for the sampled intervals indicate the presence of predominantly copper (0.33% to 0.48%) with minor silver (1.1g/t to 3.3g/t) and trace gold (0.007g/t to 0.04g/t), with the exception of the Ascot sample which returned a gold grade of 0.30g/t. A sequential copper analysis on the Bushranger samples concluded that for all the samples tested, the predominant copper mineral is chalcopyrite.
Key components of the sighter metallurgical test work programme included:
· Comprehensive head analysis of each master composite sample
· Comminution test work to assess ore hardness (Bond Ball Mill Work Index)
· Sequential copper speciation to provide an indication of copper mineralogy
· Rougher flotation test work at a pre-determined primary grind size, to assess rougher copper recovery
· Rougher flotation test work at two different reagent suites, aiming to maximise rougher copper recovery
· Bulk rougher flotation to generate concentrate for cleaner flotation test work, with and without concentrate regrind
· Mineralogical evaluation of flotation tails – diagnostic assessment to assess nature and occurrence of gold losses
Ore hardness assessments, utilising Bond Ball Mill Work Index testing, concluded that the samples are of an extreme hardness with an average work index of 23.35 kWh/t. Abrasion index testing classifies the ore as moderately abrasive, with an average abrasiveness of 0.2985.
Table 2 – Cleaner Flotation Regrind Test Work Summary
|Sample||Cumulative Conc. Grade||Recovery (%)||Tails Grade||Mass Yield
|Au (g/t)||Ag (g/t)||Cu (%)||As (ppm)||Au||Ag||Cu||Au (g/t)||Ag (g/t)||As (ppm)||Cu (%)|
*Ascot requires no regrind
The regrind-cleaner flotation test work (coarse flotation followed by regrind of coarse rougher concentrate and selective flotation or cleaning) indicated that the average final copper concentrate grades would vary between 19% copper and 27% copper, with a corresponding final copper recovery of between 78% and 89%.
When normalising the cleaner flotation results to produce a concentrate with a 20% copper grade, typical for saleable concentrates, the following copper recovery is predicted:
o Ascot – 90% (no regrind, three stages cleaner flotation)
o BR_Centre – 90% (15µm regrind, three stage cleaner flotation)
o BR_SE – 89% (15µm regrind, pH 10.5, three stage cleaner flotation)
o BR_NW – 76% (15µm regrind, pH 10.5, three stage cleaner flotation)
Silver recovery to copper concentrates averaged 58%
These results are considered encouraging, with further study required on the Racecourse North-West sample to understand the reason for the lower copper recovery in this sample.
Regarding gold recovery, this initial test work was focussed on copper not gold. No optimisation work was included to increase gold recovery at this stage. However, the Ascot sample yielded payable gold in the Cu concentrate. At Racecourse, even though these samples were not selected from relatively high gold grade areas, it was considered that payable gold would probably be achieved with additional optimisation of the recovery circuit and/or in areas where gold grade was slightly higher. However, further sampling and test work needs to be completed to confirm this hypothesis.
Similarly with molybdenum, the content of the cleaner was generally low, however further investigation is considered warranted in subsequent test programmes given that molybdenum recovery was not specifically targeted.
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, Director.
|Xtract Resources Plc||Colin Bird,
|+44 (0)20 3416 6471|
|Beaumont Cornish Limited
Nominated Adviser and Joint Broker
|+44 (0)207628 3369|
Novum Securities Limited
+44 (0)207 399 9427
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.
Marius Phillips, Engineering Director of Altrius Consulting, is a Chartered Professional Engineer with over 25 years’ experience. Mr Phillips has developed a strong operational, managerial and technical base in minerals processing and the extractive metallurgy of base metals, precious metals and PGMs. Mr Phillips has reviewed and approved this announcement as a 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:
|“Chalcopyrite”||A copper-iron sulphide mineral, CuFeS2, often found in copper ores|
|“Comminution”||Grinding of the rock|
|“Flotation”||The separation of small particles of a solid by their different capacities to float
|“kWh/t”||Kilowatt hours per tonne|
|“Mineralisation”||Process of formation and concentration of elements and their chemical compounds within a mass or body of rock
|“Molybdenum”||Ore mineral, MoS2|
|“Rougher flotation”||Flotation designed to remove the maximum amount of the valuable mineral at as coarse a particle size as practical|