South African gold mines are forcing the boundaries of ultra-depth (>3500 m) for the mining of available gold reserves. Platinum mines are also following in the footsteps of gold mines. Most intermediate- to deep-level (1000 m to 3500 m depth) gold mines are reaching their final stages of life. The availability of locked-in reserves in pillars or remnants provides an opportunity for supplementing the declining production profiles and extending the life of these mines. In this paper, we provide an overview of current remnant mining practices in South African gold mines. The factors that contribute towards the formation of remnants are discussed, and the reasons for the extraction of remnants provided. The details of current support and mining (stoping) practices are discussed for the difficult and challenging case of remnant mining.
The evaluation of remnant mining practices in the gold mining industry is necessary due to the high production tonnages currently sourced from remnant blocks, coupled with the high mining risks associated with remnants. As one progresses from mines in the Far West Rand region to the Klerksdorp and Free State regions, the average production from remnant blocks increases from approximately 5% to a high of 60% for some mines in the Free State (Rangasamy, 2004). Although the work upon which this paper is based was conducted in 2004, the findings are still relevant since the technical aspects related to remnant definition, classification, and mining have remained largely the same for the last 50 years.
In this paper, we provide an in-depth evaluation of remnant mining by establishing current or best practice in selected mines in South Africa. The following methodology was adopted.
