Vancouver, British Columbia--(Newsfile Corp. - December 18, 2017) - Los Andes Copper Ltd. (TSXV: LA) ("Los Andes", or the "Company") is pleased to announce the results of the metallurgical testwork performed by SGS and coordinated and supervised by Empirica Consultores on the Company's 100% owned Vizcachitas copper—molybdenum porphyry project in Central Chile.
Key findings:
- Overall copper recoveries remain at over 90% using a coarser grind size when compared to historical test work
- Rock competence (hardness) and resulting energy consumption is in line with similar deposits in Chile
- Coarser grind size reduces power requirements, improves water recovery, and increases throughput in the mills — the optimization will be captured in the Company's anticipated Q1 2018 preliminary economic assessment ("PEA")
Antony Amberg, President & CEO of Los Andes, commented:
"We are delighted with the results of our recent metallurgical test work. The Company has been able to show that given the nature of the deposit, we are able to recover over 90% of contained copper at significantly coarser grinding levels.
"This reduction in grinding for the rougher flotation stage would result in a decrease in the power and water consumption of the project. These reductions could have significant effects in mill throughput and operating costs, as well as help reduce the environmental footprint of the project.
"We look forward to providing further information in our forthcoming Q1 2018 updated PEA following our expected 43-101 resource update in January 2018 as we continue to progress the Vizcachitas project."
Metallurgical Test work
Sample Selection/Head Characterization
Forty samples were selected from the 2015/2016 and 2017 drilling campaigns, from an area of 676 metres East-West x 682 metres North-South with an elevation ranging between 1176 and 1994 metres. Head grades for the samples averaged 0.48% Cu and 0.022% Mo. Four predominant rock types were identified (Andesite, Breccia, Diorite and Tonalite) in combination with five alteration types (Biotite, Chloritic, Qtz-Ser, Ser-Cl and Si-Ser).
The predominant copper bearing sulfide species is chalcopyrite although a minor presence of bornite, covellite and chalcocite was observed in samples located in the andesitic/surface zone of the orebody.
Grindability
SAG mill and ball mill grindability tests showed relatively competent andesitic and dioritic samples, whereas the tonalitic and breccia samples require less energy. The tonalitic mineralization is relatively abrasive with respect to the other three rock types.
Bond mill work index averages 12.0 kWh/st for the 40 samples, and the Starkey SAG mill grindability test gave an average result of 67 minutes. Hardness for SAG grinding is comparable to similar orebodies in Chile, whereas ball mill hardness is slightly lower.
Flotation
Rougher stage recoveries were determined for a grind size (P80) that ranged from 150 to 240 microns, consistent with recommendations and observations from the previous PEA in 2014. Individual rougher stage recoveries for Cu show a minor decrease from 98% at 150 microns to 95% at 240 microns. For the cleaner flotation stage, three composite samples were used representing different sections of the deposit.
Overall (rougher + cleaner) Cu recovery was determined in locked cycle tests at a rougher grind size (P80) of 240 microns. All three composite samples achieved an overall Cu recovery over 94%.
The relatively small decrease in recovery that is observed when comparing finer with coarser grind size in the rougher stage, warrants further test work with an even coarser grind up to 300 microns. It should be noted that several existing mills currently operate in this range and it is expected that this reduction in grinding for the rougher flotation stage would result in a decrease in the power and water consumption of the project. These reductions could have significant effects in mill throughput and operating costs, as well as help reduce the environmental footprint of the project.
Additional tests are currently underway with the objective of confirming final product grade and recovery for both Cu and Mo.
Resource update and PEA
The Company has been working with its consultants to collate the results of its recent drilling programmes into an updated 43-101 resource estimate. The Company anticipates publishing this in January 2018 which will allow the Company to rapidly advance work on a revised PEA for the project. The PEA is expected to be published in Q1 2018.
Ms. Romke Kuyvenhoven MSc MBA is the Qualified Person under NI 43-101 who supervised and approved the scientific and technical disclosure in this news release. Ms. Kuyvenhoven is a mining engineer with a master's degree in mining and petroleum engineering with specialization in extractive metallurgy from Delft University of Technology, the Netherlands. She also has an MBA from Universidad de Chile & Tulane University (double degree). Ms. Kuyvenhoven has almost 20 years of experience in metallurgy; working in engineering, consulting and research for projects in Chile, Peru, Brazil, South Africa, Zambia and Canada. She began her career in 1998, working for Hatch as project metallurgist. In 2001 she joined SGS Lakefield as metallurgy manager. She later worked for Aminpro and Gecamin before before becoming an independent consultant in 2013 working with Empirica Consultores. In addition to the consulting work, over the last seven years Ms. Kuyvenhoven has been a professor of mineral processing for metallurgical and chemical engineering students at the Universidad Tecnica Federico Santa Maria.
