The Voorspoed mine, owned by De Beers Consolidated, is located 30km north-east of Kroonstad, in the free-state province of South Africa. The tenure of the mine is 12-16 years, including activities such as pre-stripping, ramp-up production and closure.
Construction of the R1.3bn project started in February 2007 and was completed in 2008-09. Production ramp-up activities began in July 2008.
The host rock Kimberlite pipe is low grade due to major internal dilution. The pipeline consists of tuffisitic kimberlite and tuffisitic kimberlite breccia, and is accompanied by various hypabyssal sills and dykes.
Two types of tuffisitic kimberlite breccia, along with seven varieties of hypabyssal facies kimberlite, were identified through early drilling.
The mine is expected to have a full capacity production of 800,000 carats per year. The company ramped up production levels from 60,000 carats in October 2008. Over ten million carats are expected to be generated during the life of the mine.
Mining and processing
Open cut mining is being implemented at the project at a depth of 360-420m. By November 2008 the mine covered a surface expression of 12.5ha at a depth of 47m.
Standard drill and blast techniques have been employed. The crushed material is transferred into haul trucks and transported to the primary crusher system. The initially crushed ore is sent to a secondary crusher and later kept as crushed ore stockpile.
Polysius was commissioned to supply equipment in 2008. The company commissioned a high-pressure grinding roll and a scrubber for disagglomeration at the mine in 2008-09.
The equipment separates diamonds from the Kimberlite through inter-particle crushing.
De Beers bought the mine in 1912 from Voorspoed Diamond Mining. The company did not take up operations at the mine. However, sampling was done in the 1960s and 70s. The company received a new order mining licence in October 2006 and exploration started with advanced diamond processing technology.
With the development of new mining methods, the mine was reopened in 2007. The new mining licence will be valid until October 2023.
The project has been designed to set benchmarks in environmental and social performance.
Over the 18-24 month project phase, around R70m was earned in the region. Over R1bn is expected to be generated during the life of the mine. The mine project will create over 1,200 jobs at peak of the construction and around 40% of the workers will be from the region.
The mine will also use services from local suppliers for non-core activities to support regional Black Economic Empowerment.