Ghana Gold Fields Limited Obuasi

by Israel Boafo Bansah

AngloGold Ashanti poured its first gold at the Obuasi Gold Mine in December, signaling its successful redevelopment into a modern, mechanized mining operation. The mine has a clear investment framework and supportive environment created by the President of Ghana and his government, and the King of Ashanti. As the second phase of the redevelopment project continues, AngloGold Ashanti estimates mining at a rate of 2,000 tonnes of gold-bearing ore per day from Obuasi during 2020, climbing to 4,000 tonnes per day by year-end.

PROJECT DETAILS

Obuasi, which has been primarily an underground operation, was placed on care and maintenance in 2016 pending the commencement of the redevelopment project. In June 2018, the Parliament of Ghana ratified the regulatory and fiscal agreements that cover the redevelopment of the mine and the Environmental Protection Agency issued environmental permits.

With the key permitting and regulatory processes finalised, the mining services contract could be signed as another key milestone in delivering a modern, mechanised underground mining operation with 5.8Moz of Ore Reserves and 30Moz in Mineral Resource, and a life of mine extending beyond 20 years.

Obuasi has operated at depths of up to 1,500m with a continuous history of mining dating back to 1897. The mining operations are located on a concession of approximately 201km2 (20,100ha) and within a largely forested region occupied by 240,000 people who are mainly subsistence farmers.

Underground access is via two main vertical shafts and a decline access while an additional shaft is used for dewatering the extreme north of the mine. The full extent of the underground operations is 8km.

Mineral extraction, by means of bacterial oxidation of the sulphide ore, is conducted at the South Treatment Plant, which has been in operation since 1993. Tailings are deposited at the South Tailings Storage Facility, located 4km to the northwest of the plant.

IMPLEMENTATION

The Obuasi redevelopment project will be implemented in two distinct phases.
The first blast took place in February 2019.

  • Phase 1 will comprise project establishment, mine rehabilitation and development, as well as plant and infrastructure refurbishment to enable production at a rate of 2,000t per day for the first operating year. Establishment of the project and operating teams have progressed well, and all key roles have been filled:
    • Detailed design has continued, focusing on the processing plant and underground infrastructure
    • Critical long-lead items have been ordered
    • Demolition of redundant processing plant structures has begun
    • Refurbishment planning has been completed
    • Works are set to begin by end March 2019
    • Housing refurbishment programme has begun
    • Expansion of the mining contractor’s camp is well advanced
    • The underground mining fleet has been delivered and commissioned
    • The underground mining contractor has been mobilised
    • Operational readiness activities, including design of the mine operating systems, has progressed to plan
  • Phase 2 will include refurbishment of the underground materials handling system, shafts and ventilation, as well as construction of the primary crusher, the SAG/ball circuit, carbon regeneration, a new gold room and tailings storage facility. This is expected to take a further 12 months and enable the operation to climb to 4,000t per day by the end of 2020. The operation is then expected to ramp up to 5,000t per day over the following three years.

Mine production in the first 10 years will focus on the upper orebodies and is expected to average 350,000oz to 450,000oz annually at an average head grade of 8.1g/t. In the following 10 years, average annual production of 400,000oz to 450,000oz is forecast. Total cash costs are expected to average between $590/oz and $680/oz and all-in sustaining costs between $750/oz and $850/oz.

CONTACTS

AngloGold Ashanti, an international gold mining company with a globally diverse, high-quality portfolio of operations and projects, is headquartered in Johannesburg, South Africa. Measured by production, AngloGold Ashanti is the third-largest gold mining company in the world.

  • HEAD OFFICE
  •  +27 (0)11 637 6000
  • 76 Rahima Moosa Street
    Newtown
    Johannesburg 2001
    South Africa
  • GHANA
  • Eric Asubonteng
  •  easubonteng@anglogoldashanti.com
  • Juliet Manteaw-Kutin
  •  jmanteaw-kutin@anglogoldashanti.com
  • +233 302743465
  • +233 302743400

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