Below is a typical example of a mining method used to excavate Bentonite from a farm in the Kinderwys block.
Securing the mining rights lead to the mining activities that commenced on August,12th 2011.
The area has been classified as the best Bentonite development in the Southern hemisphere.
Due to the uniqueness and the thickness of the clay at this location, an area of 4900 square meters was identified for the new mining area. We estimate that approximately 27 200 tons (16 000 cubic meters) of Bentonite will be produced from the first 4.5 meters.
– Hitachi Zaxis 400 LCH Hydraulic Excavator
– 3 x 10m³ Dump Trucks
We employ the services of a subcontractor who provides the necessary equipment. The operators are well trained and excavations and loading the dump trucks are done at optimum efficiency.
An excavator and 3 dump trucks conduct the open cast mining operation.
A conveniently located stock piling area approximately 200m from the mining site (quarry) was scraped with a scraper.
The different layers of Bentonite mined are stockpiled here by the dump trucks from where it will eventually be transported to the customers premises.
Removal of +/- 600mm of overburden
The excavator carefully removes and stockpiles the dark and grey overburden of 600mm separately until the first grey bentonite is exposed. This is called the first commercial zone suitable for the sealing slimes dump floor and for the A.M.D activities and the first sale able collection of bentonite mined.
Excavation of +/- 1m greyish clay
The Mining of Bentonite on Mooiplaats
After the overburden has been removed by the excavator, the fist zone of grey bentonite (average layer thickness of 1m) is mined. Each dump truck carries approximately 10 cubic meters of bentonite. A competent driver of the excavator is of vital importance as he has to have the ability to distinguish and excavate the different layers of bentonite separately. This ensures that the different zones are stockpiled correctly.
Yellow clay of +/- 2m excavated
The second zone is distinctly yellow in colour. The layer is on average 2m thick (total depth of 3.6m from surface including overburden). Once again, this zone gets stockpiled individually.
Safety has to be considered with open cast mining and the different depths of mining is clearly visible from the ‘steps’ created by the excavator. This minimizes the risk of injury and the collapse of the side walls in the quarry.
Excavation of +/- 1m greenish grey clay
The third layer has a greenish grey colour with an average thickness of 1m (second and third zone) referred to as the ‘Main Zone’, followed by the fourth zone (yellow with increased brightness) with a thickness of 2.8 meters.
Excavator loading dump truck
Safety steps and evacuation
Excavator and dump trucks in operation
Rehabilitation in process (backfilling method)
Portable diesel cart
Portable fresh water cart (500 litres)
Container for housing
2 Site supervisors
Staff welfare (food operators)
1 Project manager
Total mining and rehab days used = 40 days
Summary of excavations and loading capacities
Excavator: 1 scoop = 2 cubic meters
Dump Trucks: capacity of 5 scoops (10 cubic meters = 16 tons)
Loads Per Hour: 8 (80 cubic meters per truck per hour)
1 Dump Truck Per 9 Hour Day: 720 cubic meters (1152 tons with SG of 1,6)
Total Tons Per Day For Three Trucks: 3456 tons