May 21 2020
Probe Metals Inc., a leading Canadian gold exploration company, is happy to announce the initiation of a state-of-the-art metallurgical program on its Val-d’Or East Project. The company has also announced the latest metallurgical results received from its mineral sorting testwork.
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Past-producing operations within the Val-d’Or East project, such as the Bussiere, Monique, and Beliveau Mines, had identified metallurgical recoveries that have displayed excellent historical recoveries of +93%. Confirmation and potential improvement of these historical outcomes is the main aim of the advanced metallurgical program.
Apart from estimating the metallurgical recoveries, the advanced metallurgical program will also help with the development of a built-in flowsheet for processing deposits present in the Val-d’Or East Project and create data for upcoming mining “trade-off” analyses.
Probe Metals will perform the testing program at Corem facilities located in Quebec City, and the program will be managed by BBA Inc. The results of the program are anticipated in H2 of 2020.
Owing to the rapid growth of our Val-d’Or East gold resources, and the continued success of drilling programs, we will be expanding the scope of our programs to encompass more studies that further de-risk the project and allow us to assess potential development scenarios and economic models.
David Palmer, President and CEO, Probe Metals Inc.
Palmer continued, “The advanced metallurgical program will provide processing options for the Company while we continue to grow the existing resource and delineate new targets and deposits on our Val-d’Or east project.”
Historical Testwork
A considerable number of metallurgical programs were performed on mineralized material from the historic L.C. Beliveau mine, initially by SOQUEM between 1983 and 1985 and later by Cambior between 1986 and 1988.
The mineralized material from the former L.C. Beliveau mine was delivered to the Yvan Vézina mill located about 150 km away, and therefore, the testwork and flowsheet were focused on flotation, gravity separation, and cyanidation of the flotation concentrate.
During the production of the Beliveau mine, the historical gold recovery was 93.1%. Later, numerous tests were carried out during those metallurgical campaigns to test and improve the streamlined and less capital-intensive flowsheet of gravity as well as the leaching of gravity tails.
These tests revealed a relatively better metallurgical response, resulting in a total gold extraction of 95.5% or higher. The historical gold recovery averaged 97.9% with a related cyanide consumption of about 1.0 kg/t NaCN.
At the historic Monique open-pit mine, operations were conducted between 2013 and 2016 inclusively and the mineralized material was sent to the Camflo mill located about 50 km for further processing.
The resultant gold recovery with the Merrill-Crowe based traditional flowsheet was 95.9%. In addition, gold recovery has been referenced for the historic Bussiere mine located on the Courvan Trend, which functioned intermittently between 1932 and 1942.
In 1937, cyanidation was introduced to process the mineralized material and the resultant gold recovery was 98%. No metallurgical data is available for the North and Highway deposits of the Pascalis Trend, or the other deposits of the Courvan Trend.
Metallurgical Testwork Program—Objectives and Details
The aim of the present metallurgical testing program is to enhance the historical recoveries and also determine the recoveries on the deposits, where no data is available. The estimated gold recovery for the Val-d’Or East Project is currently 95% on the basis of the previous testwork and production.
To realize the program objectives, an array of composites will be produced and tested: a pair of composites for the New Beliveau deposit and one each for the Highway, North, Courvan Trend, and Monique deposits.
The first Beliveau composite will be arranged from drill core intervals that were spatially chosen to be indicative of the type of mineralization as well as the average head grade of the resource. The second Beliveau composite will be arranged from mineral sorting concentrates to be indicative of the material that would be leached if pre-concentration was executed.
The host rock and mineralization in the Courvan Trend are analogous over the Trend. Consequently, a composite denoting the entire Courvan Trend mineralization will be produced from drill core intervals. Composites for the Monique, North, and highway deposits will be produced in a similar way.
Tests like gravity separation followed by gravity tails leaching will be performed on all the composites. Varying leaching conditions will be assessed and improved. In addition, communition testing will be carried out on certain composites to help with the design of a grinding and crushing circuit. The program results will be issued in H2 of 2020.
Pre-Concentration (Mineral Sorting) Study
In an independent study, a range of full-scale pre-concentration sorting tests was concluded at TOMRA’s facility based in Wedel, Germany. The tests were performed on a 12-ton representative sample with a back-calculated head grade of 3.5 g/t gold obtained from the New Beliveau deposit.
On the basis of the testwork outcomes presented in the 43-101 Technical Report, a tentative screening, crushing, and sorting flowsheet was developed with three-stage crushing and two sorting circuits—one for the coarse material and one for the mid-size material. In addition, mass balances for 8,000 tpd of mine mineralized material were subsequently computed to size the equipment and predict the capital and operating costs.
The flowsheet containing pre-concentration (that is, crushing, grinding, sorting, and gravity separation followed by leaching of gravity tails) was compared to a more conventional free-milling flowsheet of crushing, grinding, and gravity separation followed by leaching of the gravity tails.
Both Beliveau historical testworks performed in the 1980s and also benchmarks from other analogous deposits were used to supplement the presently missing parameters/properties.
Key highlights of this side-by-side comparison analysis denote that integrating pre-concentration sorting may have positive and considerable effects. These include:
- The mass flow being delivered to the leaching/grinding plant reduced by 44%
- The capital cost for the crushing and processing plant reduced by 22% because of the reduction in the size of the process plant
- The operating cost for each ton of the ROM mineralized material reduced by 33%
- The overall gold recovery reduced by 4.9%
On the whole, the initial mineral sorting results demonstrate considerable potential with a meaningful reduction in the operating and capital costs and massive reduction in the size of the processing plant. Depending on these outcomes, Probe Metals has planned to continue the assessment of the mineral sorting for possible inclusion in the project flowsheet.