Mine excursion
Technology adds value
Berger adds that instead of a drum spiral cyclone module typically used in coal processing plants , the plant at Khanye will make use of large coal dense medium separators ( Larcodems ). Larcodems are cylinder cyclones designed to beneficiate feed material sized from 0.5mm to a top size of 150mm . The Larcodems are gravity fed and , unlike cyclones , introduce the medium and the coal separately . “ That enables us to dry transport the coal to the top with a conveyor into a bin and , in turn , into the Larcodems , which treats all the different size fractions ,” says Berger . This is unlike a typical plant where a certain size fraction has to be put through the drum , a certain fraction through the cyclone , and the fines through the spirals . In the Larcodems , it is split at once and then screened into the different size fractions at the other side .
“ The coal at Khanye is slightly more brittle than usual and we need to reduce the handling that results in unnecessary breakage . Trying to put coal through a pump and then get it up to a cyclone will result in fracturing , and the Larcodems process eliminates that risk . In the design we have also allowed for a second Larcodems that will be able to split smaller fractions ,” says Berger .
To keep the revenue flowing , some of the run of mine ( ROM ) being stockpiled at Khanye before the processing plants are commissioned ( first the interim and then the main plant ), will be transported to the Phalanndwa plant near Delmas , where it will be washed . The construction of the two plants will take , according to Mabbett , at least another three to four months to complete .
A unique partnership
Although Isimilo can be regarded as a contractor , the company is really part of the Canyon Coal stable . However , Berger says that in a unique partnership , Isimilo can also undertake contract work at other mining sites . The long-term vision at Canyon Coal is that they will eventually undertake all work in-house , although they are still using Koza as a mining contractor at Khanye . “ At Khanye , we need six teams of equipment — a team meaning an excavator , articulated dump trucks ( ADTs ), and all the other equipment associated with it . Four teams are Canyon ’ s own teams and two will be
Khoza ’ s teams ,” says Mabbett . A team consists of a supervisor and a number of operators .
In total , there will be six excavators , three or four ADTs per excavator ( thus 24 ADTs ), and several pieces of ancillary equipment like dozers and graders . Currently , the mine is using an 870 Hitachi excavator , Bell B40 ADTs , Komatsu dozers , a Bell 770 grader , and two 23 000-litre Bell water bowsers .
Geology presents challenges
Hallatt says the three seams at Khanye differ in quality and , depending on the customer requirements , the product will have to be a blend of all three seams . “ The upper seam disappears in certain areas , which then leaves us with only the middle and lower seams ( or 1 and 2 seams ),” says Hallatt .
The deepest part of the opencast mine at Kanye will be about 76m ; however , due to the seam thickness , it will still be mined economically . “ Where we have started mining now , the pit will only be about 45m deep , with an extremely low stripping ratio . The overall project strip ratio is 2:1 . However , there are a few areas in the pit where the seam dips down to about 70m , and that will naturally increase the stripping ratio ,” says Hallatt . When the mine reaches full production , there will be two pits , namely a northern and a southern pit . The northern pit currently consists of two box cuts . These two box cuts will eventually merge into one big pit .
Hallatt mentions that there are a few geological challenges in the pit , but nothing that cannot be overcome . “ For example , there is a geological occurrence ( basement high ) between the northern and southern pits where the coal was never formed . We have done extensive drilling and determined that the middle section ( the dead spot ) is a geological anomaly , so we have delineated the potential problem areas adequately ,” says Mabbett . The other challenge will be to control the strip ratio where the seams dip to 70m below surface .
Canyon Coal has firmly established itself as a significant mid-tier player in the coal mining industry of South Africa and is set to make further inroads in the future . Be sure to scribble down the name as competition in the South African coal sector heats up . b
[ 14 ] MINING MIRROR MAY 2018