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Grade engineering at Gramalote gold deposit, Colombia: an example of industry research collaboration, Part 1


Clarke, N and Barros, A and Hunt, J and Keeney, L, Grade engineering at Gramalote gold deposit, Colombia: an example of industry - research collaboration, Part 1, Proceeedings of the Preconcentration Digital Conference 2020, 10-11, 17-18 November 2020, Virtual Conference, Online (Australia), pp. 383-396. ISBN 978-1-925100-93-8 (2020) [Refereed Conference Paper]

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The Gramalote orebody is a large low-grade gold deposit situated in the San Roque municipality, 124 km north-east of Medellin in Antioquia, Colombia. It is jointly owned by AngloGold Ashanti (AGA) and B2Gold and is currently in Feasibility Study phase.

In 2013 AGA requested CRCORE to undertake a preliminary study of the potential application at Gramalote of pre-concentration by screening, part of the Grade Engineering suite. 160 samples of coarse assay rejects (-3 mm) were tested and showed one of the strongest responses seen worldwide to that time, suggesting that about 70% of the gold could be recovered into 40% of the mass. This was seen as potentially markedly improving the Gramalote economics.

A large-scale testing program was implemented on site to follow up these results. A total of 18 samples of 17 t each were mined along a pre-existing exploration adit. A complex test flowsheet allowed size fractions to be generated from the as-received material as well as after crushing to 53, 23 and 3 mm, all from the same head sample. The procedures were designed after carrying out a heterogeneity study to measure sampling errors. The coarser size fractions were designed to study the effect of crushing on upgrade response and predict the response on open-pit run-of-mine ore. The finer size fractions were designed to investigate means of predicting the upgrade response across the orebody.

The large-scale testing closely confirmed the average upgrade response as predicted from drill core assay rejects but found that only the -53 mm crushed material accurately predicted the upgrade response of individual samples. Ore geochemistry was able to usefully distinguish samples with good and poor response. A small study on drill core suggested that, for Gramalote, fine crushed material distinguishes vein associated and disseminated values but not other factors that control actual outcomes.

Item Details

Item Type:Refereed Conference Paper
Keywords:geometallurgy, grade engineering
Research Division:Earth Sciences
Research Group:Geology
Research Field:Resource geoscience
Objective Division:Mineral Resources (Excl. Energy Resources)
Objective Group:Environmentally sustainable mineral resource activities
Objective Field:Environmentally sustainable mineral resource activities not elsewhere classified
UTAS Author:Hunt, J (Dr Julie Hunt)
ID Code:143960
Year Published:2020
Deposited By:CODES ARC
Deposited On:2021-04-12
Last Modified:2021-09-27

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