Name
Bibiani mine.

Location
The Bibiani gold mine is located 250 km north-west of Accra, in western Ghana.

Mine Owner/s
Asante Gold. The Ghanaian government holds a 10% non equity free carry interest and a 5% net smelter royalty in the Bibiani mining lease.

Brief Description
Bibiani is an historically significant gold mine in Ghana.

Brief History
Operations started in 1902 and closed in 1913, after having recovered an estimated 70 000 oz of gold. In 1927, mining activities restarted and ownership has changed hands several times.

The mine was nationalised in 1958 and operated by the State Gold Mining Corporation until it was closed again in 1968. In the period before nationalisation, from 1902 to 1957, the mine produced about 2.2-million ounces of gold.

The mine was sold to Ghana Libyan Arab Mining, or Glamco, in the 1980s, before being bought by Ashanti Goldfields in the mid-90s.

Ashanti Goldfields constructed a 2.7-million-tonne-a-year carbon-in-leach plant and started openpit mining in 1997. By late 2003, it started underground development to Level 9, in addition to mining low-grade satellite deposits.

From 1997 to 2005, the mine produced about 1.8-million ounces of gold, bringing cumulative production to about four-million ounces.

However, following the merger between AngloGold and Ashanti Goldfields, the Bibiani mine was sold to Central African Gold (CAG) in 2006.

A wholly owned CAG subsidiary operated the mine until January 2009, but operational difficulties, exacerbated by the global financial crisis, resulted in Investec’s taking control of the asset.

In December 2009, Noble Mineral Resources acquired 100% of the CAG subsidiary, and Bibiani owner, from Investec. Noble achieved first gold pour in March 2012.

Resolute Mining invested in Noble in 2012 and became the operator in 2014.

Asante Gold acquired Bibiani in the third quarter of 2021, and started mining in first quarter of 2022. First gold was poured on July 7, 2022.  

Primary Metals/Minerals
Gold.

Secondary Metals/Minerals
None stated.

Geology and Mineralisation
The majority of significant gold deposits in the West Africa craton are hosted in shear-fault-vein structures, situated in or adjacent to the Ashanti, Sefwi and Asankrangwa belts. The Bibiani deposits are hosted in the Bibiani shear zone, on the eastern margin of the Sefwi belt.

The gold deposits at Bibiani are structurally controlled mesothermal lode-type deposits. Mineralisation is associated with quartz veins and quartz stockworks, which are hosted within a sequence of lower Birimian fine- to medium-grained turbiditic sandstones.

The sedimentary turbidite sequence is tightly folded, with west-dipping axial planes and localised development of steep west-northwest-dipping shear zones, which have acted as conduits for the initial gold mineralisation.

Gold is closely associated with arsenopyrite and pyrite. Sericite alteration is also commonly observed, along mineralised structures, and associated with the felsic intrusives. High-grade veins often occur within graphitic shales that generally contain significant sedimentary/metamorphic pyrite.

Reserves
As at February 28, 2022, the Bibiani mine had a total mineral reserve of 28.4-million tonnes grading 2.14 g/t gold and containing 1.95-million ounces of gold.

Resources
As at February 28, 2022, the Bibiani mine had a measured and indicated resource of 31.57-million tonnes grading at 2.24 g/t of gold and containing an estimated 2.29-million ounces of gold.

Type of Mine
Openpit.

Mining Method
Asante decided to adopt a different mine plan to the original underground approach and redeveloped the openpit operations using conventional openpit methods.

Major Infrastructure/Equipment
The openpit operations are supported by existing infrastructure, such as the refurbished three-million-tonne-a-year milling circuit and upgraded processing plant, tailings storage facility, explosives magazine and other ancillary infrastructure.

The processing plant has been subjected to a full refurbishment and upgrade exercise and will be expanded, with more improvements – to four-million-tonnes-a-year throughput by 2025 – to meet the remaining life-of-mine (LoM) plan.

Prospects
Gold production ramp-up is progressing, with the openpit mining contractor expected to deliver more than three-million tonnes a year of ore to the process plant from the openpit mines. This is expected to increase to four-million tonnes a year in 2024.

The company is exploring various underground mining methods at Bibiani to transition to a combined openpit-underground operation next year. This will increase the profile from 400 000 oz in 2023 to more than 550 000 oz by 2026.

Asante expects to be a million-ounce producer by 2028 and is on track to achieve that objective, Asante CEO Dave Anthony told Mining Weekly in March.

Exploration around the Bibiani mine continues, with Asante considering developing satellite deposits and extending openpit mining beyond the initial ten-year LoM projection.

In November 2023, Asante extended the mineral resource estimate for the Grasshopper pit, where mining had started in quarter two of 2023. The pit is on the Bibiani mining lease and is less than 2 km from the processing plant.

Asante reported a constrained indicated resource of 1.88-million tonnes at 1.04 g/t gold for 56 500 oz of contained gold for the Grasshopper pit.

In a statement, released at the time, Anthony noted: “With [the] successful [start] of the starter pit and mining activities in the quarter two of 2023, we look forward to further strengthening our position in the market and delivering exceptional value for our shareholders and stakeholders.”

The tailings dam is fully reconditioned and has more than 12 months’ storage capacity. A lift to provide an additional four years of storage capacity will start in the first quarter of 2024.

Contact Details
Asante Gold Corporation
Tel +1 604 661 9400 or +233 303 972 147
Email info@asantegold.com

Sources
Asante Gold Corporation. Website https://asantegold.com
Asante Gold Corporation. Bibiani Gold Mine.
Asante Gold Corporation. NI 43-101 Technical Report (July 2022).
Asante Gold Corporation. Corporate Update Presentation (October 2023).

Mining Weekly. Website https://www.miningweekly.com
Mining Weekly. Miner soars past hurdles, aims to expand in 2023 (March 03, 2023).
Mining Weekly. Asante extends Grasshopper resource at Bibiani (November 07, 2023).