Modern Mining June 2024

MINING CONTRACTORS AND ENGINEERS

Redpath Thonket makes history at Obuasi Mine In March 2024, Redpath Thonket (a joint venture between Redpath Africa and Thonket Plant Pool) set a new world record by completing the largest raisebore hole at AngloGold Ashanti’s Obuasi Gold Mine in Ghana. This milestone is part of Phase 3 of the mine’s redevelopment project, aiming to support AngloGold Ashanti’s goal of producing 400 koz annually from the underground mine by delivering 6 000 tonnes per day efficiently.

Guests and crew members gathered on 15 March 2024 to witness the holing of the Kwesi Mensah Ventilation Shaft.

M easuring in at an impressive depth of 944 m and a diameter of 6.3 - 6.5 m, the Kwesi Mensah Ventilation Shaft (KMVS) was drilled by the Redpath Thonket team using a Rotary Vertical Drilling System (RVDS) in conjunction with Redpath’s Redbore 90EX raisedrill. Leveraging the RVDS – a specialised directional drilling technol ogy that allows for drilling in a non-vertical direction – the team attained an accuracy of 0.03% over the length of the hole. Redpath Thonket reached several significant milestones during the implementation of the KMVS project, including the successful completion of the pilot hole in December 2022 and an accident free record since the inception of the project. In November 2022, Redpath Thonket set the world record for the longest run (691 hours) on one RVDS; while in 2009, Redpath set the previous world record for the longest run (641,6 hours) on one RVDS at the Doyon Gold Mine in Québec, Canada. Redpath Thonket’s Environmental, Social and Governance commitments, which are structured around its values and key areas of care for its people, safety, the natural environment and the social environment, were evident at the KMVS project. The Redbore 90EX raisedrill was equipped

The Kwesi Mensah Ventilation Shaft – measuring in at a depth of 944 m and a diameter of 6.3 - 6.5 m. with variable frequency drives to limit power con sumption. Water consumption was limited and recycled during piloting operations through specially designed mobile settling dams to minimise water consumption. Furthermore, the Redpath Thonket team prioritised skills transfer by combining unskilled individuals from the local community with skilled and experienced team members, fostering growth and development. Speaking at the KMVS holing ceremony on 15 March 2024, Vits Maharaj (Project Director, Obuasi Redevelopment Project) emphasised that by improv ing underground ventilation, AngloGold Ashanti will have access to deeper and richer ore bodies, achieve production targets, extend the life of mine, and maximise returns to shareholders and host com munities in which they operate. “This feat is a major milestone in the journey to restore Obuasi Mine as a world-class tier 1 mine. It started some two years ago amidst ground condition challenges and has ended in this global achievement without any reportable safety incident,” says Maharaj. Bennie Burger (General Manager – Raiseboring, Redpath Africa) told Modern Mining that the Redpath Thonket team’s dedi cation and expertise were instrumental in achieving this significant milestone at Obuasi Mine and have set a new standard for raisebore drilling. He reiterated the company’s unwaver ing commitment to excellence and innovation, highlighting its role in supporting AngloGold Ashanti’s vision for sustainable mining opera tions. He expressed immense pride in the team’s accomplishments and eagerly antici pates their continued contributions to Ghana’s mining sector. 

The Redpath Thonket team was made up of crew members from Ghana and South Africa.

36  MODERN MINING  June 2024