TSXV-listed Orezone Gold Corporation plans to update the 2018 feasibility study on its 90%-owned Bomboré gold project in Burkina Faso to include a staged higher-grade sulphide expansion (Phase II Sulphide Expansion) to complement the oxide mine plan in the 2018 feasibility study.
Burkina Faso – The Phase II Sulphide Expansion is envisioned as a 3 000 to 3 500 tpd sulphide circuit to process zones of higher-grade sulphide and lower transition oxide resources starting in year 3 of commercial production.
Capital for this expansion is expected to be funded by future operating cash flows.
Roscoe Postle Associates will update the current 5 January 2017 mineral resource estimate to include the oxide material within the previously termed ‘restricted zones’ and the free milling sulphide material at P17S in support of this Phase II Sulphide Expansion study.
This update to the 2018 feasibility will not impact the ongoing development and schedule of the Bomboré project as presented in the 2018 feasibility study.
As stated on 8 November 2018, the current project is being designed as a 5.2 Mtpa operation and is currently advancing through detailed engineering with first gold production scheduled to commence by October 2020.
We are very excited to commence an updated feasibility study to evaluate the potential upside of a sulphide circuit to meaningfully contribute to the project’s future gold production as part of a phased expansion to the 2018 FS oxide mine plan,” says Orezone Gold Corporation President and CEO Patrick Downey.
“Previously, the sulphides at Bomboré were viewed as a large low-grade deposit. However, a recent detailed review of the measured and indicated sulphide resources by the company and our consultants has identified continuous zones of significantly higher grade, near surface mineralisation which warrants a more in-depth analysis. In addition to the higher grade sulphides at P17S, we have successfully identified four additional areas of thick and continuous higher-grade measured and indicated sulphide resources located directly beneath current oxide reserves.
“Historical metallurgical test work together with pit geotechnical evaluations have been previously completed on these sulphides which will allow for rapid advancement of this update to the 2018 feasibility study, which we are targeting for completion by the end of Q2 2019,” says Downey.
Feasibility update for Phase II Sulphide Expansion
Test work and previously released studies indicate that the sulphide process plant extension will consist of a crushing and grinding circuit that feeds into a leaching circuit that will be designed to provide the first the 24 hours of leaching. This partially-leached material will then be fed to the main oxide carbon in-leach circuit where overall leaching of the blended material will be completed, and the gold recovered to the oxide plant carbon elution circuit. Test work to date on sulphide material indicates recoveries ranging from 73% in the north (Maga and P8/P9) to over 90% in the south (Siga and P17S).
The gold recovery, tailings and reagent systems of the oxide plant design in the 2018 feasibility study will remain unchanged as will the main project infrastructure.
The overall plant throughput is currently contemplated to remain at 5.2 Mtpa with these higher-grade sulphides replacing lower-grade oxides.
Over the past quarter, the company, in conjunction with its consultants, has been reviewing the sulphide mineralisation beneath the current oxide reserve pits in the 2018 feasibility study. The 2017 resource statement estimated that the sulphide zones contained 96 Mt of measured and indicated resources at a gold grade of 0.83 g/t (above a lower cut-off grade of 0.38 g/t), including 71 Mt of measured and indicated resources at a gold grade of 0.97 g/t over a higher cut-off grade of 0.5 g/t.
From this review, the company has outlined several higher-grade sulphide zones located within the main measured and indicated sulphide. For the initial review, these zones of higher-grade sulphides have been constrained to a maximum depth of 100 m but the mineralisation remains open at depth.