New Technology at Lesedi Drilling
Technology in the underground exploration environment in South Africa has not progressed significantly since the Second World War. Pneumatic feed screw drill technology has huge limitations when it comes to safety and productivity. The drill has no ability to be automated so the drilling team are always working in close proximity to the rotating rod string and in constant danger of rods descending from a hole in an uncontrolled way. The machine has only one penetration speed so it is generally not possible to really increase the rate of penetration. Without any rod handling capability finger injuries are common. In order to try and eliminate these dangers and constraints Lesedi Drilling engineered the ADDER drill. This drill has the following characteristics:
- The drill is hydraulic which enables the machine to be fitted with semi -automated rod handling and hydraulic chuck technology. This removes the driller from the source of danger when working with the rod string.
- The power pack is powered by compressed air (a 35kw air motor powers the hydraulic pump) OR by electricity (22kw electric motor) depending which power source is required.
- The machine spins the rods at over 2 000rpm which results in high speed cutting by the drill bit.
- The rods are removed from the hole at a rate of 750mm in 2 seconds. This is because of the automated hydraulic chuck being synchronised with the hydraulic rod clamp.
- The drill at 150kg is lighter to mount on the bar when compared to the 250kg Kempe or MetreEater drill.
- The drill is ideal for the South African mining industry which is in transition between using less efficient compressed air to power equipment to electro hydraulic sources of power on machines. The drill can handle both sources of power and is this highly flexible.
COMBO DRILLS: AIR/Electric over hydraulic Drills
This is a photograph of the ADDER “Combo drill” power pack configured with a 35kw air motor to power the hydraulic pump. If the mine has no compressed air then the air motor and its silencer are removed and a 22kw electric motor is installed to power the hydraulic pump.
The ADDER “combo drill” compressed air powered power pack and the drill machine mounted on a bar.
Adder Technical Data
- Feed length: 750mm
- Feedframe overall length: 2038mm
- Drill feed rate: 750mm per minute
- Rod handling speed:750mm in 2 seconds
- Chuck RPM (high gear): 2052rpm
- Chuck Self centring 12 jaw spring open and hydraulic close
- Rod clamp: Hydraulic open and spring close 2 jaw fail safe
- Air motor: 35kw @ 6 bar air pressure , 22kw @ 4 bar pressure
HYDRAULIC DRILLS – The Mamba Drills (22kw or 45kw)
As noted above, feedscrew drills are extremely dangerous and world-wide (with the exception of South Africa) have generally been phased out of the underground diamond drilling environment. The Kempe or MetreEater feedscrew hydraulic drills offer no productivity or safety advantages to the mine or a contractor. Lesedi Drilling operate the MAMBA range of hydraulic drills. These drills offer all the safety and productivity advantages associated with hydraulic automated rod handling and high speed drilling.
The rotation unit and Feedframe are configured to be powered by either the 22kw or 45kw power pack depending on the desired hole depth.
Mamba Technical Data
- Overall Feedframe length: 2 600mm
- Drilling feed rate: 2.6m/minute
- Rod handling speed: 1.5sec/800mm
- Weight 240kg
- Rotation unit RPM 1 700rpm
- Depth rating for the 22kw power pack is 175m