Global corporate engineering and consulting group DMT has released the new-generation Slim Borehole Scanner (SBS) technology for imaging extra-slim drillholes with a diameter of 23 mm, with keen interest from local mining companies, says DMT director Sodhie Naicker.
One of the SBS’s primary tasks is the imaging and consequently logging of rock- or roof-bolt boreholes. Rock- or roof-bolting (RB) is a common technology used to stabilise underground mine workings, tunnels or cliffs. Many types of rock bolts have been designed with variable lengths, materials and methods to ensure contact to the rock.
Naicker explains that, depending on the rock deformation and shape of the mine workings or tunnels, a pattern using suitable rock bolts is designed, although “changing ground conditions may force a change in the design pattern”, he notes.
Further, more stable conditions will enable the mine operator to lower the density and the type of rock bolt, while less stable conditions may initiate a shift to a denser pattern and/or different rock bolt.
He points out that RB adds significant costs to underground operations, but it is crucial for the safety of workers and production. Owing to costs, rock bolts are typically slim – less than 25 mm in diameter, which has previously forced geotechnical staff to inspect ground conditions in RB boreholes using an endoscope. This method resulted in staff making a verbal description of observations.
Despite efforts to standardise this method, the subjectivity or personal impression of the description creates much uncertainty. Therefore, repetition and transparency are compromised, and companies are often reluctant to shift to more cost-saving RB patterns.
DMT developed the first SBS in 2004, together with the German coal mining industry, in response to these constraints, Naicker states. Owing to this cooperation, the tool is rated intrinsically for use in coal mines or, for example, in explosive environments.
Naicker highlights that the new generation SBS, which was released in January, enhances more informed planning of roof bolts, owing to features such as the 360° optical scanner. The scanner provides scaled images of the complete borehole wall as opposed to videos, which can be a tedious piece of data to work with during interpretation, he notes.
Moreover, the SBS enables mining companies to obtain geological and structural information, as well as the orientation of joints and bedding planes, the provision of geotechnical rock mass conditions, as well as rock mass to be imaged and compared over time for monitoring the roof.
Further, the SBS is especially designed to fit miniscule boreholes. It has a diameter of only 23 mm, compared with other optical scanners that often require a minimum 50 mm borehole diameter, Naicker points out. The self-sufficient wireless tool is lightweight, easy to mobilise and use, operates independently of the borehole conditions and has no limitations to borehole lengths and inclinations.
“With regard to applications in South African coal mines, the SBS is certified flameproof. All these technical features make it absolutely exceptional on the market,” he highlights.
Internationally, the SBS is used in zinc, lead, copper and gold mines in Kazakhstan and Sweden; manganese mines in Brazil; and coal mines in Australia, Germany, Poland, the Czech Republic, China, India and Indonesia. It is also being used in demonstration projects in salt mining in Germany, as well as by civil engineering and geotechnical companies in Spain and South Korea.
“As an introduction to South Africa, our target market was initially coal mines. We are now extending into various other commodities,” Naicker states.
He advances that there has been keen interest locally from potential clients in chrome and gold mining, as well as engineering. DMT has sold one SBS in South Africa and is processing an order for a second one.
Upon buying an SBS, clients receive a training session from DMT. The company also offers demonstrations prior to purchase, which enables clients to see and understand the outputs and benefits of the SBS.
“This is an essential service we offer because it is a new technology and the client needs to understand its application at the respective mines,” Naicker concludes.