Horisontal Raise Boring
100m – 200m
Phase A - length 52m x ø4.5m completed
Phase B - Length 106m x ø4.5 in progress
Horizontal Raise Boring (HRB)
Master Drilling has pioneered HRB drilling technology and applications both in Africa and worldwide with an undercut level tunnel cut through a Kimberlite pipe in an underground diamond mine. A typical tunnel may be 4.3m x 4.3m diameter and 200m long.
HRB is similar to traditional raise boring where a pilot hole is drilled in a horizontal position. The rig that drills the pilot hole may be different to the raise boring rig that will drill the reamer hole, depending on whether the hole can be drilled with drilling mud or by means of air vacuum. In certain areas the hole will need to be drilled by vacuum due to deterioration when the rock comes into contact with water.
Mining sector: HRB is used where a horizontal excavation is required and a chamber is available at both ends. Typically such tunnels are bored in a block cave mining layout, or
on a undercut or production level where the ring tunnel
is first established.
Civil sector: In urban infrastructure, HRB is used for excavating tunnels through mountains/hills, also for connecting parallel metro or railway tunnels, as well as tunnels required to run underneath roads.
Energy sector: HRB is used in the energy industry, for nuclear storage tunnels or short tail races in hydro-electric plants.
· Similar to that of traditional Raise Boring it shows potential for lower support requirements than tunnels excavated by means of conventional drill and blasting methods.
· The continuous excavating cycle, and the circular structure of the excavation leaves a stronger profile tunnel.
· In certain locations it is impossible to assemble a TBM due to its length and size. Under these circumstances establishing a plant for HRB operations is quicker and easier to implement.
· HRB technology is more cost effective, and in some cases a more reliable system, when compared to a TBM system.
Master Drilling rolls out cutting-edge mining technology
Horizontal raise boring technology to double mining productivity in kimberlite
Master Drilling today announced its Horizontal Raise Boring (HRB) technology is ready for international roll-out after the successful pilot test at the Cullinan Mine. HRB can replace conventional drill-and-blast mining and promise to increase mining productivity thanks to its continuous process of rock boring, and in addition offers significant safety benefits. This will enable more mining construction projects to meet the required hurdle and feasibility rates towards becoming producing mines. Projects with less safe access, such as deeper mining operations and higher stress zones, is also more likely to pass feasibility tests thanks to the safety improvements that HRB brings.
The latest version of the Master Drilling HRB was officially unveiled at the Investing in Africa Mining Indaba 2017, held in Cape Town.
Master Drilling is a South African based JSE-listed drilling solutions provider with over 160 drills across 17 countries. HRB is an entirely new rock boring solution and can be offered to Master Drillings’ existing client base of existing multinational mining concerns, as well open the door to approaching new clients in mining and civil construction. The technology is expected to offer support to Master Drilling revenue growth over the medium to long term, and thereby provide further income diversification.
“HRB is a locally developed, world-first technology that promises to change the very fundamentals of the global mining industry,” said Danie Pretorius, CEO of Master Drilling. “The feedback from our multinational business partners from Southern Africa and Latin America on visits to the actual technology has been highly encouraging.”
HRB will provide the mining industry with an excavation and construction tunnelling tool for the mechanical excavation of a tunnel between two existing access points, very similar to the standard form of raise boring. The steady progress of the reamer is able to excavate an average 6 meters per day, compared to 2 meters in conventional drill-and-blast cycles.
The technology offers the much-needed mechanisation to reduce the number of workers who are exposed to dangerous underground conditions.
The benefits extend across the project-chain and include amongst others:
- No need to use explosives
- No blast effected damage inflicted to the tunnel sidewalls
- The structure of the tunnel is stronger due to the circular profile of the tunnel
- Reduced rock support costs
- Improved tunnel construction accuracy
- Lower excavation costs
- Continuous operations not effected by blast re-entry
- Greater remote operated possibilities
- In certain locations it is impossible to assemble a tunnel boring machine (TBM) due to its length and size. In these locations the plant for raise boring is smaller and easier to transport
The pilot project at the Cullinan Mine of Petra Diamond Mines involved boring and excavating a 180 meter horizontal tunnel with 4.5 meter diameter through the kimberlite ore, i.e. diamond deposits. The construction method entails first drilling a smaller pilot hole through the kimberlite, which was challenging as no water can be used for flushing. The pilot hole also needed to be near perfectly straight. For these reasons Master Drilling pioneered using vacuum air suction and laser assisted directional steering in collaboration with a US-based company, which is typically used in civil construction.
“The HRB technology has the potential to become the new normal for underground diamond mining, if not mining in general, thanks to the benefits it brings in terms of safety, lower costs and a faster advance rate,” said Johan Dippenaar, CEO of Petra Diamonds Limited. “We plan to continue using HRB at the Cullinan mine and is assessing the potential of deploying it at our other sites as well.”
Master Drilling was established in 1986 and listed on the JSE in 2012 and operates in the mining, underground and open pit business. The business model is that of a contractor who designs and manufactures its own drilling equipment to provide complete drilling service solutions, and does not sell any of it’s machines. Master Drilling recorded revenue of USD 58.3 million in the six months ended June 2016, and net profit of USD 9.6million for the period and market capitalisation of R2.5 billion, with a $209 million order book excluding HRB.
“Master Drilling is about selling a solution and not a product. Our technologies is the result of identifying and responding to needs in the market - ahead of the curve,” said Danie Pretorius.
Over the years Master Drilling has developed new technologies including the Remotely Operated Shaft Inspection Unit (ROSI), amongst others. Currently Master Drilling is developing the Blind Shaft Boring System (BSBS), a mechanised system for boring a vertical shaft to a depth of 2 000 meter with finished diameters ranging from 10 meter to 13 meter. No underground access is required for the BSBS to start boring operations as a shaft sinking method.