Southern African diamond development and exploration company DiamondCorp has proudly achieved the two major milestones that it had set for 2015 at its 74%-owned Lace diamond mine in the Free State province of South Africa. Chantelle Kotze visited CEO Paul Loudon on site.
At full production, the high grade Upper K4 block will be mined at a rate of 30 000 tpm, producing carat grades of between 50 cpht and 60 cpht at a cost of R200/t.
While still in the process of steadily ramping up to achieve commercial production in the fi rst half of next year at the fi rst mining block at Lace – the high-grade Upper K4 (UK4) block, DiamondCorp has been able to simultaneously commission a 400 tph underground conveyor system from the fi rst production level – the 310 m level – to surface.
Loudon says that the commissioning of the 1.6 km long conveyor system is a game changer with respect to the development of the Lace mine, as it will enable an eff ective ten-fold increase in the capacity to haul ore out from the mine – a task previously undertaken by fi ve dump trucks hauling only 15 t of ore on a two hour round trip.
He says that the conveyor belt capacity has been sized at double the current front end capacity of the processing plant. This means that future opportunities for increasing the underground mining rate are not constrained by an inability to transport ore to surface. It also provides an ability to handle both kimberlite and development waste.
“Not only does the conveyor belt enable Lace to increase development rates but also the cost of future development will decrease in the absence of the need for trucks for waste hauling. The underground loaders will now empty their buckets directly onto the end of the conveyor belt,” Loudon explains. Loudon says that conveyor will continue to be extended as the development gets deeper. All the required conveyor belt steelwork, drive motors and conveyor belting for the continued extension down to the block cave level are on site, protecting the company against future price increases and further weakening in the value of the rand.
The next production level to be established – the 470 m level – will also be serviced by the conveyor, which will be installed when needed. At this point, the conveyor will be about 2.7 km long from the underground tipping arrangement to the surface.
This means that until the block cave is established at the 470 m level in 2018 and production from it commences, the use of trucks will be confined to hauling kimberlite from the UK4 Block production level to the tipping point on the conveyor belt.
No trucks will be used for the continued decline development in waste rock down to the block cave level as the conveyor belt will be extended as the decline progresses….