Orezone's 2023 definitive feasibility study for the Bomboré gold mine in Burkina Faso raises total processing to 10.3 Mtpa. A new plant for lower transition and fresh ore shares the existing carbon regeneration kiln and gold room.
The Orezone Gold Corporation Bomboré Phase II Expansion, Burkina Faso, Definitive Feasibility Study National Instrument 43-101 Technical Report has an effective date of 28 March 2023 and a signature date of 24 November 2023. The existing Oxide plant processes oxide and upper transition ore at a nominal 5.9 Mtpa, which is 0.7 Mtpa above its 5.2 Mtpa nameplate. The Phase II Hard Rock plant adds 4.4 Mtpa of lower transition and fresh ore, for a total of 10.3 Mtpa. Design criteria come from metallurgical samples from the five main mining areas: Maga, P8P9, P16, Siga and P17.
Critical Data
| Parameter | Value | Unit | Notes |
|---|---|---|---|
| Report effective date | 28 March 2023 | Not applicable | Definitive feasibility study for Orezone Gold Corporation |
| Total processing capacity | 10.3 | Mtpa | Oxide plant 5.9 plus Hard Rock plant 4.4 |
| Hard Rock plant feed | 85% fresh, 15% lower transition | Not applicable | 12,055 t/d |
| Head grade | 1.90 design, 1.02 LOM | g/t Au | Hard Rock plant |
| Overall gold recovery | 82.4 | % | Hard Rock plant, at LOM grade |
| Availability | Crushing 75, grinding and CIL 91.3 | % | Hard Rock plant |
| Hardness | CWi 16.8, BWi 15.7 | kWh/t | 85th percentile |
| Primary crusher | Single toggle jaw, P80 175 mm | Not applicable | Designed for 5.0 Mtpa |
| SAG mill | Single-stage, 18,000 kW | Not applicable | Closed with cyclones to P80 75 µm |
| Pre-leach thickener | 29 m, to 45% solids | Not applicable | Cyclone overflow at 30% solids |
| Leach | 1 pre-oxidation + 7 CIL tanks, 24 h | Not applicable | Space for an eighth CIL tank |
| Reagents | NaCN 0.69, lime 0.98 | kg/t ore | Testwork and calculation |
| Elution | 12 t pressure Zadra | Not applicable | Shares Oxide plant kiln and gold room |
Overview
The existing Oxide plant receives soft saprolite ore over a static grizzly and passes it through an MMD sizer. A single-stage 3,200 kW ball mill grinds it to P80 125 µm, and one pre-oxidation tank and seven CIL tanks give 21 hours of residence. The new Hard Rock plant has its own jaw crusher, a 15,000 t crushed ore stockpile and a single-stage SAG mill closed with cyclones. A pre-leach thickener, a pre-oxidation tank and seven CIL tanks follow, then acid wash and pressure Zadra elution. Carbon reactivation, the gold room furnace and two new electrowinning cells are in the existing facilities, and the product is doré bars.
Key Process Stages
Ore receiving and crushing. 35 t rear-dump trucks tip back-to-back into a ROM bin with an 800 mm static grizzly and a fixed rock breaker, and fog sprays suppress dust. A variable-speed apron feeder and vibrating grizzly feed the jaw crusher in open circuit. A static magnet removes tramp metal. The crushing equipment treats 4.4 Mtpa nominally and is designed for 5.0 Mtpa.
Stockpile and grinding. The crushed ore stockpile holds 15,000 t live, about 24 hours. Two variable-speed feeders reclaim onto the SAG mill feed conveyor, where lime is added. The single-stage SAG mill discharges over a horizontal vibrating screen, and oversize pebbles return to the mill feed. Provision is made for a future pebble crusher, and space is kept for a future ball mill and gravity circuit.
Thickening and CIL. Cyclone overflow at about 30% solids passes trash screens to a 29 m pre-leach thickener. The thickener raises the slurry to 45% solids, which reduces leach tank volume and reagent use. A pre-oxidation tank and seven CIL tanks give 24 hours, with oxygen addition and liquid cyanide.
Elution and gold recovery. Loaded carbon is acid washed and stripped in a 12 t pressure Zadra circuit. The Oxide plant's carbon regeneration kiln reactivates the carbon. Gold is electrowon in two new cells in the existing gold room and smelted to doré in the existing furnace.
Additional Interesting Data and Summary
Equipment was chosen for suitability, reliability, compatibility with the Oxide plant and ease of maintenance, and only then on price between broadly similar vendors. The layout lets construction proceed in several areas at once with minimum interruption to Oxide plant operation. The 1.02 g/t LOM grade includes 0.021 g/t of CIL solution and carbon fines losses in the recovery basis.
In summary, the 2023 Bomboré Phase II study keeps the operating oxide circuit and adds a 4.4 Mtpa hard rock line. The new line has jaw crushing, a single-stage 18 MW SAG mill to 75 µm, pre-leach thickening and 24-hour CIL, and it shares the existing kiln and gold room.
Key Processes
- Jaw crushing and crushed ore stockpile
- Single-stage SAG milling to P80 75 µm (Hard Rock plant)
- MMD sizing and single-stage ball milling to P80 125 µm (Oxide plant)
- Pre-leach thickening
- Pre-oxidation and carbon-in-leach
- Acid wash and pressure Zadra elution
- Carbon regeneration, electrowinning and smelting to doré
Source: Orezone Gold Corporation, Bomboré Phase II Expansion, Burkina Faso, West Africa, Definitive Feasibility Study, National Instrument 43-101 Technical Report, effective date 28 March 2023.
Technical report and processing history
The following archived source profiles have been consolidated here to preserve the project’s processing history and study context.
Bomboré Gold Project — 2014 Preliminary Economic Assessment
Bomboré Gold Project — 2014 Preliminary Economic Assessment
| Company | Orezone Gold Corporation |
| Date | March 2014 |
| Commodities | Gold |
| Mine Type | Open Pit |
| Throughput | 15,000 tpd |
| Mine Life | 8 years |
| Annual Production | 5,475,000 t |
| Status | Development |
Executive Summary
This 2014 Preliminary Economic Assessment outlines the proposed development of the Bomboré Gold Project by Orezone Gold Corporation. The project is designed as an open-pit mine targeting two distinct ore types: saprolite (oxide) and sap-rock (transition). The processing strategy relies on a heap leach circuit capable of treating approximately 15,000 tonnes per day, with an estimated mine life of 8 years based on a total ore reserve of 45 million tonnes.
The processing plant design includes a three-stage crushing circuit to prepare the ore for leaching, followed by agglomeration using lime and cement to improve permeability. The heap leach system utilizes a cyanide solution applied at a rate of 8 L/h/m², with a designed leach time of 75 days. Gold recovery is achieved through a carbon adsorption circuit, followed by desorption, electrowinning, and smelting to produce doré bullion.
The report details the engineering basis for the crushing, leaching, and recovery systems, including stability analyses for the leach pad and water balance modeling for a zero-discharge operation. Preliminary engineering was conducted by Kappes Cassidy and Associates, with design criteria established for crushing product sizes, reagent consumption, and power requirements across two phases of heap expansion.
Website: https://orezone.com/press-releases/orezone-reports-first-gold-from-bombore-hard-rock-expansion/
Report Date: March 2014
Project Status: Development
Commodity: Gold
Throughput: 15,000 tpd
Mine Life: 8 years
Mine Type: Open Pit
Bomboré Phase II Expansion — 2023 Technical Report
Bomboré Phase II Expansion — 2023 Technical Report
| Company | Bomboré |
| Mine | Bomboré |
| Region | Nobsin River Area |
| Commodities | Gold |
Executive Summary
This report details the Recovery Methods for the Bomboré Phase II Expansion Definitive Feasibility Study, focusing on the integration of a new Hard Rock plant with the existing Oxide plant. The total processing capacity is designed to reach 10.3 Mtpa, with the Oxide plant handling 5.9 Mtpa of Oxide and Upper Transition ores, and the new Hard Rock plant processing 4.4 Mtpa of Lower Transition and Fresh ores.
The Hard Rock plant utilizes a conventional unit operations flowsheet including crushing, grinding, pre-oxidation, and Carbon-in-Leach (CIL) circuits to maximize gold recovery while minimizing capital and operating costs. Key equipment includes a primary jaw crusher, an 18,000 kW SAG mill, and a CIL circuit with seven tanks and a pre-oxidation tank. Gold is recovered via Zadra elution, electrowinning, and smelting into doré bullion bars.
The existing Oxide plant continues to process softer saprolite ore using an MMD sizer and ball mill circuit. Both plants share carbon regeneration and gold room facilities, ensuring operational synergy. The design emphasizes reliability, maintenance access, and automation to support the Life of Mine (LOM) schedule.
Reports
- entities/Bombore_Mine
Website: https://orezone.com/operations-overview/bombore/
Report Date:
Region: Nobsin River Area
Project Status:
Commodity: Gold
Throughput:
Mine Life:
Mine Type:
Ore type:
