Canyon Coal officially opened its Khanye mine in November last year. Since then development at the mine has progressed according to plan. Leon Louw visited the site recently.
Khanye Colliery is the third mine in the developing Bronkhorstspruit coal belt of Gauteng, and part of the growing list of assets owned by Canyon Coal. Under the steady hand of executive chairman Vuslat Bayoglu, the company has gone from strength to strength, and brought Khanye into production in only 11 months.
Through continued exploration and strategic acquisitions, Bayoglu has been able to build up an impressive pipeline of projects that will ensure Canyon Coal continues to deliver coal to a growing market for at least the next 50 years.
Despite its growing list of assets, Canyon Coal has retained the ability to make quick decisions and execute them rapidly. Bayoglu has also been able to attract and keep some of the best skills in the coal mining sector, which has been one of the reasons Khanye is performing in line with expectations.
The Bronkhorstspruit geology is different to other coal mining regions in the country, and in a way Khanye is a test run for what might follow in an area desperately in need of development and employment opportunities.
In the pit
Khanye Colliery is an open cast strip mining operation and consists of three pits: North A, North B and South Pit. Guy Thompson, general manager at Khanye, explains that North A and North B pits will eventually merge to become one pit. “There is an area devoid of coal between the two pits, but they will still join up within the next year,” he says.
The mine operates two processing plants, but the smaller plant that was erected to handle the initial Run of Mine (ROM) will eventually make way for the much bigger and complex plant. Construction on the second plant is complete and is in the process of ramping up to full production. The smaller plant processes about 100 tonnes of coal per hour, or 50 000 tonnes of coal per month, while the bigger plant’s full capacity is 400 tonnes per hour (7000 tonnes of coal per day).
The first excavation at Khanye took place in December 2017 when the trenching got underway. The first box cut, in North A pit, was started in January 2018. Contractor Koza Mining takes care of mining operations in North A pit and North B pit, while Canyon Mining Services (CMS), another arm of Canyon Coal, does all the mining in the South Pit.
Koza Mining uses six Liugong 650 excavators, and they operate a mixed fleet of Bell and Volvo B40 and A40 Articulated Dump Truck (ADTs). In addition, six Chinese manufactured LCMG M85 Rigid Dump Trucks (RDTs) traverse the two pits.
In the South Pit CMS uses two 750 Volvo excavators and a brand-new fleet of seven A40 Volvo ADTs. A 950 Volvo excavator and three A60 Articulated Dump Trucks (ADTs) were delivered to CMS during the last week of April.
Thompson explains that CMS has historically purchased Bell ADTs, Hitachi excavators and Komatsu dozers. “However, we recently decided to standardise our fleet at Khanye with Volvo equipment,” says Thompson.
Accessing the seams
CMS uses sequential strip-mining methods to unearth the three coal seams at South Pit. “The three main seams that we mine are 2 Upper Seam, 2 Lower Seam and 1 Seam. Whenever we do mine a patch of 3 Seam it is sent to the plant separately and blended with the other coal in the processing operation,” he says.
The overburden consists of a soft sub-soil clay, which occurs on top of a two- to eight-metre-thick sandstone layer. The first coal seam (2 Upper Seam) is encountered at the bottom of the sandstone, about nine metres from surface, but it dips and the sandstone seems to disappear halfway through the pit. There is a thin shale band on top of 2 Upper Seam. The strip ratio is on average about 2:1 in this area.
Underlying the shale is 2 Lower Seam, followed by a parting which is about one-and-a-half to four metres thick, before 1 Seam is accessed. As soon as the coal has been removed, sequential roll-over rehabilitation takes place. “We will be opening three benches at a time, so we will be mining one of the seams at all times. In other words, there will always be coal available. With three excavators, our target is to mine about 10 500 cubic metres per day in two 12-hour shifts. Khanye currently operates until six on a Saturday morning on the mining operations, but we’ve applied for a continuous mining permit to enable us to mine on Sundays if required.
Unearthing the coal
CMS will use excavators and ADTs to load the coal, thus about three to four trucks per excavator, depending on the haul distance and turnaround time. “Because all three excavators are working close to each other you can swop trucks. Operators are trained to identify where they are needed the most when they arrive at the face. Our control room system allows the operator to report on an hourly basis what they have loaded (topsoil, shale, clay or coal). The system works well because South Pit is small. However, if there are 60 trucks and more excavators, you do need a more fixed and rigid system,” Thompson adds.
Canyon Coal does all the blasting at Khanye in-house, but the drilling is done by a contractor called MEM. The company uses BME’s electronic blasting system. At the moment, they are drilling up to 13 000m per month including overburden, parting and coal. Thompson says that there is a lot of clay in the area and they have historically only been able to drill about 3000m to 5000m per month. “In the South Pit, however, there is a thick sandstone band, so our drilling increased more than three times last month,” he says.
When I visited the site, the mine had blasted through the sandstone belt to expose 2 Seam coal. The sandstone material is used to build the mine’s haul roads. Blasting takes place as and when needed, but on average once or twice a week. Mining in the soft clay material in all three pits has limited the number of blasts required, but the clay also provides a challenge.
Thompson says the clay causes what the miners refer to as “carry back” in the haul trucks. In other words, the clay gets stuck in the bin and needs to be cleaned out on a regular basis. “We have dedicated TLBs in the pits that clean the back of the trucks on a regular basis. If they don’t, the trucks deliver half loads,” explains Thompson.
Processing the material
The distance from the South Pit to the main processing plant is about 1.6km, which will be the longest haul, but the team is mining progressively towards the plant, which means the hauling distance will be reduced over time. There is a ROM tip area between the two plants from which both plants are fed. The bigger plant is a lot more advanced than the small modular plant, which produces an RB3 product of zero by 50mm.The new plant will normally target a 25.5 CV, but that will change to a 27 CV at certain times, as some coal seams are of a better quality than others, which means the products will be blended to produce a high quality export coal.
Khanye’s new plant is the first of Canyon Coal’s larcodem plants built by contractor Obsideo and operated by Isimilo DBO, which consists of larcodems instead of the traditional drum plant, and a filter press to process the slurry. The coal mined in the pit is fed into the ROM feed bin. From there it goes through a primary crusher, then into a secondary crusher before it splits off into the larcodem that produces large and small nuts. After that the material enters a cyclone that handles the peas and the duff. Thompson explains that a secondary stage wash capacity is planned to be built within the main plant to wash the discard and produce a middling’s product. The final products and discard are stockpiled in an area measuring almost 36 hectares.
Khanye has two pollution control dams. At the moment there are two slurry cells and filter presses in both plants to handle the slurry. According to Thompson, the mine is in the process of installing another two slurry cells soon which will increase the capacity and enable the plant to pump slurry into the slurry cells in case of a breakdown on the filter press plants. The processing plant and stockyard areas are surrounded by concrete lined V drains which feed into the pollution control dams. All dirty water from the plant operations or storm water runoff of the stockyards wash into the V drains and then into the pollution control dams. The same water is recirculated back to the plant for re-use.
The mine is not connected to the Eskom grid yet, but Canyon Coal has recently completed a substation on the mine which will come online soon. The substation was built by private contractors. The processing plants were, until now, powered by two generators at the big plant and one at the small plant.
Transport and risks
Washed coal products from Khanye are transported to the Bronkhorstspruit Siding, which was constructed by Canyon Coal. The siding is only 8km from the mine and from there the coal will be railed to Richards Bay Coal Terminal.
Thompson regards coal theft as one of the major challenges and risks for coal mines in South Africa. “Coal theft is big business in South Africa. There are illegal coal blending yards in the coalfields of Mpumalanga. Truck drivers allegedly get paid up to R3000 per load and they offload good quality coal at illegal “blending yards”. Sometimes good quality coal is replaced with inferior quality coal and then delivered to a customer.” says Thompson. This was also recently highlighted by the television programme, Carte Blanche.
Khanye is expected to deliver coal for the next 16 years and forms an important part of Canyon Coal’s pipeline of projects, making the company one of the prime movers in the mid-tier coal mining space of South Africa.