Obuasi, Ghana

Obuasi is an underground operation with the main accesses into the mine consisting of shafts and a single access decline with interlevel development of between 15 and 30m. The Obuasi Deeps Decline, which is situated at the southern end of the mine, is designed to extend to a depth of about 1,500m.

Existing infrastructure includes a 2.4Mtpa processing plant with flotation and bacterial oxidation (BIOX), underground development, hoisting shafts and associated infrastructure, power and water reticulation, office complexes, workshops and company housing estates. Power is supplied to the mine by the Volta River Authority and GridCo.

Phase 3 of the redevelopment project begun in 2019 and is currently underway.

A brief history

• Production at Obuasi started in 1897 and stopped in the last quarter of 2014. Some aspects of the mine continued under limited operational conditions, including the development of the underground decline
• A favourable feasibility study was completed in 2017 and indicated a strong technical and economic case with an anticipated 20-year LOM
• In 2018, approval was received from the AngloGold Ashanti Board to proceed with the project.
• The redevelopment project began in early 2019 and first gold was poured during the fourth quarter of that year:
  • Phase 1 of the redevelopment project was completed by end September 2020 and began commercial production on 1 October 2020
  • Phase 2, construction and mine development, was completed in 2021 – together with phase 1 this brought capacity to 4,000t a day
  • Phase 3 is currently underway to develop the infrastructure necessary to support the planned ramp up in production to 5,000tpd – this is scheduled for completion by end 2024 following delays caused by the need to clear mud encountered at the lower levels
• A trial of underhand drift and fill mining in high-grade areas was initiated in 2023 as this method is better suited to the challenging ground conditions often associated with higher grades at Obuasi.