This independent technical report provides an updated mineral resource estimate for the Buckreef Gold Project based on exploration drilling completed through February 2020.
Report context
This independent technical report, effective May 15, 2020, was prepared by Virimai Projects for Tanzanian Gold Corporation (TRX) to update the mineral resource estimates for the Buckreef Gold Project located in the Geita District of north-central Tanzania. The project comprises four gold prospects: Buckreef, Eastern Porphyry, Tembo, and Bingwa, held under Special Mining License SML04/1992 and 12 Prospecting Licenses. The update is based on exploration and drilling data collected by TRX during the period January 2019 to February 2020, totaling 17,650 m of drilling, which brings the total meterage drilled on the project to approximately 125,750 m.
Processing route
Metallurgical testwork history
No detailed metallurgical testwork was completed as part of this mineral resource update study. Assumptions on economic recoveries are based on several previous testwork programs carried out and reported in prior SEDAR filings.
Testwork conducted by MPC and SGS demonstrated that more than 90% of the gold can be recovered by a combination of gravity concentration and leaching of the tails. MMSA testwork established that 93% of the gold from oxide ore can be recovered without gravity concentration by carbon-in-pulp leaching, and that 85% of the gold from sulphide ore can be recovered in a similar manner.
Previous testwork programs
Key results from Geita Gold testwork are documented in the report. Gallery Gold conducted scoping and diagnostic testwork. IAMGOLD completed Phase 2 metallurgical testwork including grinding testwork and process selection testwork. Heap leaching testwork included simulated heap tests by SGS in 2009 and heap leaching amenability testwork by SGS in 2016.
Current testwork program
The purpose of the current testwork was to inform the processing strategy for the prefeasibility study. Samples originated from oxide and sulphide ore materials from the Buckreef deposit. Bond mill indices were determined for both oxide and sulphide ore materials. Pilot milling was conducted using the EDS multi-shaft mill.
Head grade and deportment
Head analysis for gold was completed. Gold deportment in the milled material was examined by size fraction for both ore types. For the oxide ore, gold deportment is higher in the fine fraction. For the sulphide ore, gold is not concentrated in any one size fraction.
Gravity concentration and cyanidation
Gravity concentration testwork was performed using a Falcon L40 concentrator, with grade and recovery curves against mass pull generated for both oxide and sulphide ores. Cyanidation results were reported for both oxide and sulphide ores. Cyanide and lime consumption were summarized.
Design processing route
The processing strategy is described for a proposed plant. The process description and design criteria include: ore receipt and scrubbing, crushing and milling, gravity concentration, thickening plant, carbon-in-leach plant, carbon acid wash and elution, carbon regeneration, and tailings treatment. The design incorporates an EDS mill for the milling circuit.
Overall design criteria
The overall design criteria are specified in Table 17.2 of the report. Design head grades for oxide and sulphide ores are defined. Mass balance information is provided.
Design criteria by area
Design criteria are presented for the scrubber/screen, jaw crusher, EDS mill and classification circuit, gravity concentrators, shaking table, dewatering cyclone, thickener, carbon-in-leach section, tails screening, carbon elution, and tailings detoxification.
Reagents and utilities
Reagent requirements are documented. Utility requirements including power consumption are reported.
Key reported parameters
| Parameter | Value | Units | Basis |
|---|---|---|---|
| Gold recovery – oxide ore (gravity + CIL) | >90 | % | Testwork (MPC, SGS) |
| Gold recovery – sulphide ore (gravity + CIL) | >90 | % | Testwork (MPC, SGS) |
| Gold recovery – oxide ore (CIP only) | 93 | % | Testwork (MMSA) |
| Gold recovery – sulphide ore (CIP only) | 85 | % | Testwork (MMSA) |
| Bond mill index – oxide ore | Reported | kWh/t | Testwork |
| Bond mill index – sulphide ore | Reported | kWh/t | Testwork |
| Design head grade – oxide ore | As specified | g/t Au | Design |
| Design head grade – sulphide ore | As specified | g/t Au | Design |
| Mineral Resource – Measured | 20.99 Mt at 2.03 g/t Au | Mt, g/t | Estimate (March 2020) |
| Mineral Resource – Indicated | 17.59 Mt at 1.46 g/t Au | Mt, g/t | Estimate (March 2020) |
| Mineral Resource – Inferred | 19.55 Mt at 1.14 g/t Au | Mt, g/t | Estimate (March 2020) |
| Mineral Resource – M+I total | 38.57 Mt at 1.77 g/t Au | Mt, g/t | Estimate (March 2020) |
| Mineral Resource – M+I gold content | 2,194,510 | oz | Estimate (March 2020) |
| Mineral Reserve – Proven (June 2018) | 9,352,183 t at 1.72 g/t Au | t, g/t | Design (2018 study) |
| Mineral Reserve – Probable (June 2018) | 9,730,764 t at 1.36 g/t Au | t, g/t | Design (2018 study) |
| Mineral Reserve – P+P total (June 2018) | 19,082,947 t at 1.54 g/t Au | t, g/t | Design (2018 study) |
| Gold price for pit design | 1,300 | US$/oz | Design assumption |
| Cut-off grade – oxides/transition | 0.38 | g/t Au | Design calculation |
| Cut-off grade – fresh rock | 0.41 | g/t Au | Design calculation |
Project website: https://trxgold.com/project/buckreef/buckreef-gold-overview/
Technical qualifications
This report is an update of mineral resource estimates only. No detailed metallurgical testwork was completed as part of this current mineral resource update study. The mineral reserves reported are from the June 2018 technical report and have not been updated. A new pit optimisation taking into account the current mineral resources update and current prevailing economic factors is still to be completed. Inferred mineral resources are considered geologically speculative and are not used in project economics, nor are they considered for mining plans. The study is restricted to open pit mining at this stage.
*Source: NATIONAL INSTRUMENT 43-101 Independent Technical Report – Updated Mineral Resource Estimate for the Buckreef Gold Mine Project, Tanzania, East Africa, effective May 15, 2020.*
