African Mining November 2019 | Page 31

MINE EXCURSION  gangue is mainly iron oxide, which is hematite, and silica. “To increase the temperature, several methods can be used, but all involve energy input. Electricity springs to mind immediately, but electricity is only economical in small amounts. The most effi cient and the most economical way to satisfy the heat requirements is with coal-fi red boilers. To generate enough steam, we require low- pressure boilers,” says Brits. The mine has installed four boilers. Each of the boilers produces about 10 tonnes per hour of steam. The plan is to have three boilers operating at any one time and then have a fourth boiler on standby. Mining two deposits Wagner says that they have started mining both the Outwash Fan and Plattekop deposits. Most of the initial overburden unearthed from the Outwash Fan deposit was used in the construction of the tailings dam. Lower grade ore from the Outwash Fan was put through the plant fi rst before the deposit at Plattekop was exposed, which, according to Wagner, produces a higher-grade ore. All mining currently takes place in the Plattekop pit. Initially, in the fi rst year, mining will focus mainly on the Plattekop orebody with smaller tonnage coming from the Outwash Fan orebody. In the second year, mining on the Outwash Fan deposit will start in earnest and for the next nine years the plant will receive a blended product from both pits. Thereafter for about seven years, the plant will be fed from a higher-grade shallower portion of the Outwash Fan deposit as the Plattekop deposit will be worked out. In the last three to four years, mining will be concentrated in the deeper portion of the Outwash Fan pit. There is a real prospect of extending the life of mine from Wiltin, the third ore body on Nokeng’s license area. Wiltin is only partially explored at this stage. “We do not know too much about Wiltin, but it looks like a large orebody, and it off ers potentially a very viable alternative,” says Wagner. The hills above the processing plant are rich in fl uorspar and at Wiltin, it outcrops in a number of places very close to the surface. “We have done some geophysics, but we still don’t know the full extent of the ore body. However, it does appear to be an extension of the Plattekop ore body and has a similar sort of grade to Plattekop,” says Wagner. The ore is drilled, blasted, loaded, and hauled from the pits to the mineral processing facility. Outwash Fan is about one kilometre from the plant, while Plattekop is just under three kilometres. The open pit mining is done by medium scale mining contractor Andru Mining, which uses two excavators in the pit and four 30 tonne ADTs to haul the material to the primary crusher. Wagner says that the mine is not yet running at full capacity and that there are elements of the plant that are capable of handling a lot more feed. “We believe we can get the plant up to 220 000 to 250 000 tonnes per annum output within two to three years after startup, and then we still need to look at Wiltin as well,” he says. The company plans to continue exploration of the Wiltin deposit over the next two years. “We know that the deposit outcrop, which is between 15m to 20m thick on surface, is a very signifi cant deposit, we just don’t know the extent, Wagner explains. Furthermore, Wagner adds that there could be other substantial deposits in the hills. There are not many other operating fl uorspar mines in South Africa, with Nokeng’s neighbour, Vergenoeg, being the most signifi cant. Vergenoeg is jointly owned by Spanish fl uorspar producer Minerales y Productos Derivados SA (Minersa) with an 85% share, and MEDU Capital (15%). The mine has a production capacity of 240 000 tonnes per annum (tpa). The resources at the Plattekop and Outwash deposits at Nokeng are world-class in terms of grade, low deleterious elements, bulk type deposits as opposed to vein-type deposits and ease of mining. South Africa hosts about 17% of the world’s fl uorspar reserves. Currently the global fl uorspar market is about 6Mt a year.  Nokeng’s concentrator will produce about 180 000t of acid grade fl uorspar (97% pure fl uorspar) and 30 000t of metallurgical grade fl uorspar annually from run-of-mine fl uorspar ore production of 630 000t. www. africanmining.co.za African Mining Publication African Mining African Mining  November 2019  29