The Eagle Mountain Gold Project in Guyana would process saprolite and fresh rock through a two-phase gravity and carbon-in-leach flowsheet, with design and costs supported by 2022 SGS testwork and historical metallurgical programs.
Report context
The Preliminary Economic Assessment for the Eagle Mountain Gold Project, Guyana, is a National Instrument 43-101 technical report prepared for Goldsource Mines Inc. The report is dated March 1, 2024, with an effective date of January 16, 2024. It describes a proposed open-pit mining and processing operation at the Eagle Mountain and Salbora deposits in Guyana, comprising a Phase 1 saprolite ore processing plant and a Phase 2 expansion to fresh rock processing.
Processing route
Testwork basis
Metallurgical testwork history includes programs by Golden Star Resources, testing during 2009–2010, gravity testing during 2013–2014, gravity pilot plant testing during 2016–2017, and further testwork in 2018. A comprehensive 2022 test program was conducted at SGS. The 2022 program included material characterization, comminution testwork, gravity concentration, and leach/CIL testwork on fresh rock and saprolite samples.
Comminution
Bond work index testing on fresh rock and saprolite samples was completed during the 2022 SGS program, with results compared against a reference database. Bond abrasion testing was also completed. These data formed the design basis for the comminution circuit.
Gravity concentration and leaching
Gravity separation testing was completed for fresh rock and saprolite samples in the 2022 SGS program. Whole ore cyanidation tests were completed on saprolite samples, and gravity tailings cyanidation tests were completed on both saprolite and fresh rock samples. The combined gravity and cyanide leach flowsheet shows historical testing outcomes and the 2022 SGS results.
Phase 1 flowsheet (saprolite)
The proposed Phase 1 processing plant is designed to treat saprolite ore through a flowsheet using gravity concentration followed by carbon-in-leach (CIL), with cyanidation of the gravity tailings. Process design criteria are presented in the report for Phase 1.
Phase 2 flowsheet (fresh rock)
The proposed Phase 2 expansion adds fresh rock processing capacity to the flowsheet, with the overall circuit retaining the gravity and CIL configuration. Process design criteria are presented separately for Phase 2.
Description of processing plant , Phase 1
The Phase 1 processing plant description covers the overall process flowsheet and the individual processing steps. The flowsheet includes crushing and grinding, gravity concentration, leaching, and carbon-in-leach recovery.
Description of processing plant , Phase 2
The Phase 2 processing plant description covers the expanded flowsheet and processing steps for fresh rock feed, retaining the gravity and CIL process configuration.
Key reported parameters
| Parameter | Value | Basis |
|---|---|---|
| Phase 1 feed type | Saprolite | Proposed design |
| Phase 2 feed type | Fresh rock | Proposed design |
| Gravity concentration | Included in flowsheet | Proposed design |
| Cyanidation | Whole ore and gravity tailings tested | 2022 SGS testwork and historical testwork |
| Bond work index | Fresh rock and saprolite tested | 2022 SGS testwork |
| Bond abrasion index | Tested | 2022 SGS testwork |
| Resource cut-off grade sensitivity | 0.5 g/t Au shown in global change of support analysis | Mineral resource estimation |
| Gold price for PEA economic analysis | US$1,850/oz | PEA base case assumption |
Project website: https://www.makominingcorp.com/projects/guyana/development/eagle-mountain/
Technical qualifications
The report is a Preliminary Economic Assessment and is preliminary in nature. It includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves. There is no certainty that the preliminary economic assessment will be realized. Mineral resources are not mineral reserves and do not have demonstrated economic viability.
The report states that the PEA includes a phased development approach, with a Phase 1 saprolite processing plant and a Phase 2 expansion for fresh rock, and that the design criteria for both phases are provided in the report. The process design is based on the 2022 SGS testwork program and historical metallurgical testing, and the report recommends additional testwork for a pre-feasibility study, including sample characterization, gravity testing, leaching tests, drop weight testing, crushability testing, rheology testing, static and dynamic thickening tests, and cyanide destruction testwork.
Source: Preliminary Economic Assessment for the Eagle Mountain Gold Project, Guyana, NI 43-101 Technical Report for Goldsource Mines Inc., report date March 1, 2024, effective date January 16, 2024, sections 13 (Mineral Processing and Metallurgical Testing) and 17 (Recovery Methods), and Section 25 (Interpretation and Conclusions).
