Developments In Drill & Blast Technology

Louise Davis

The Centre for Applied Dynamics Research (CADR) at the University of Aberdeen is about to take advantage of original research started in 1999. A new spin-out company, iVDrill, has been created to commercialise the resonance enhanced drilling (RED) technology. 

What Is Resonance Enhanced Drilling Technology

RED, a transformational drilling technology, applies a controllable high-frequency dynamic stress to a drilled formation, which is induced by axial oscillations of a drill-bit at the resonance frequency. The resonance is maintained for varying drilling conditions by adjusting the frequency and amplitude of the dynamic load to produce a steadily propagating fracture zone. This leads to a considerable drilling cost reduction and a smaller environmental footprint. The RED technology is particularly well suited for hard rocks.

What Is The Difference Between RED and Percussive Drilling

Professor Marian Wiercigroch, the RED inventor from the university, explains: “The most important difference between RED and percussive drilling is that RED generates dynamic loading of low amplitude and high frequency, which is contrary to percussive drilling operating with high amplitude and low frequency. RED has been developed and tested extensively in the CADR laboratories and now we are aiming to commercialise it. This technology can be used in many areas, such as downhole drilling, drilling interventions, mining, drilling in geothermal wells, coring and others. We have developed and tested two different types of RED modules: a fully controllable but expensive magnetostrictive and a simple but cost-effective mechanical exciter.”

The Results Of RED Tests

Recently the CADR tested the RED technology for coring applications in collaboration with Volcanic Basin Petroleum Research (VBPR) and the Oil & Gas Innovation Centre (OGIC). Dr John Millett, VBPR director says: “The results are very positive and form a strong foundation from which to make potentially major steps forward in future coring capabilities, reducing costs and improving recovery. The project has special relevance for hard-rock coring scenarios such as through volcanic sequences and may help answer questions resulting from limited or poor core recovery in such scenarios.”

In addition to this, there are other ongoing research projects including a collaboration with Varel International, which aims to gain a better understanding of the mechanics of force generation and its relationship with the drilling parameters. In addition, the team is developing and testing the new hybrid polycrystalline diamond compact (PDC) bit with cutting elements combining shearing and gouging actions. During this project, new bit/rock interaction models of a single cutter/blade PDC will be developed. Professor Wiercigroch elaborates, “These models will be calibrated and validated by extensive experimental tests, to optimise the design of the new hybrid drill-bit with cutting structure combining shearing and gouging actions, having much greater longevity and efficiency when drilling through chert and fractured granite.”

3D Printing To Produce Drill Parts

Caterpillar’s latest rotary blasthole drill, MD6200, went into production earlier this year.

The company is calling it its “most transportable rotary drill yet,” with a model 336 excavator-style undercarriage and small shipping envelope. It’s powered by a Cat C18 engine rated at US EPA Tier 4 Final or US EPA Tier 2 equivalent, depending on the local regulations where it’s sold. It is designed for holes of 127 to 200mm in diameter.

It complements the MD6250 and MD6310, which went into production last year, adding to the two larger drills, the diesel-powered MD6540C and the electric (line power) MD6640 for drilling holes up to 406mm in diameter. This is most commonly used in mines with power distribution systems for electric shovels and/or draglines.

Behind the scenes, the company has embraced new technology for development, with extensive 3D printing facilities to rapidly produce parts during product development and for testing design concepts, creating cost-effective manufacturing tools and printing low-volume service parts, precision models, training aids and even sales tools. Virtual reality is increasingly being used for maintenance.

Starting with the drill bit, Caterpillar introduced its latest line of rotary drill bits in 2018 and recently announced a new line of down-the-hole hammers and bits. Several options are offered, with configurations of 171mm with a variety of carbide shapes (spherical, ballistic) and face shapes (concave, flat, convex).

Greg Scott, a rotary drills product consultant at Cat explains how the lubrication works: “The drilling machine powertrain is cooled using Cat coolers with variable speed fans that adjust fan speed based on operating temperatures. This helps make the hydraulic system as efficient as possible and lowers overall load on the engine to boost fuel efficiency.

“The rock tools, tricone bits for example, are run more efficiently using Cat Auto Drill/Drill-Assist as feed force, torque and RPM are modulated so the cutting tool is not overworked, yet maintains optimal advance per revolution based on the ground conditions it works through.”

Staying Safe

Safety is always a key design consideration for drills. Scott continues, “Our new generation of rotary blasthole drill rigs have more than 40 hard and conditional interlocks to ensure the safety of drillers and to protect the machine from damage. Conditional interlocks ensure safe and efficient operation and adherence to recommended best practices. Our focus on ergonomics, safety and ‘smart design’ ensure that Cat drills are fit for duty and create synergy between the driller, drill rig and cutting tools.

“Additionally, remote control operations remove the operator from potentially hazardous conditions. Caterpillar offers these capabilities through Command for drilling, part of Cat MineStar Solutions.”

MineStar development is ongoing. The system builds on automated functions – Auto Mast, Auto Level and Auto Drill – and is designed to reduce drilling variability between operators and to provide more consistency. For drill guidance, the system builds on Cat Terrain for drilling, which incorporates satellite positioning technology to show the operator the locations of the holes to be drilled. It helps to drill a precise pattern as a result of precise positioning.

The next step up in drill automation is the semi-autonomous system. This allows the operator to position the drill at the beginning of a row of holes and then to set up the machine to drill the entire row autonomously. As it does this, the operator can tend to other tasks or set up another drill to drill a row autonomously.

An optional arrangement includes a remote operator station that can be located near the bench or in a remote location. This allows the operator to position the drill at the beginning of the next row and start a new cycle again, or to manually drill holes from a remote location. The autonomous technology is evolving to feature Auto-Multi-Pass drilling and multiple row autonomy.

In conjunction with local dealer WesTrac, the company is trialling four autonomous blast drills at Rio Tinto’s Koodaideri iron ore mine in the Pilbara, Western Australia. It’s part of a study to examine the possibility of increased automation, and a fleet of 20 autonomous 793F trucks are also on site.

It forms part of Rio Tinto’s ‘Mine of the Future’ programme, which aims to digitally link all aspects of mining.

It’s an ambitious project, with plans to basically automate everything, even the workshop, as well as the creation of a digital model of the processing plant which staff can access in real-time.

The owners are hoping for an output of 43 million tonnes per year, scheduled to be up and running at the end of 2021.

Scott concludes, “Modern rotary blasthole drills are designed for precision, using state-of-the-art technology such as high-precision GNSS to locate the machine accurately over the target hole and to monitor bit advance while drilling so that holes are drilled to the required depth. Computer-aided functions such as Auto Drill/Drill-Assist control the rig’s feed, rotation, air and water injection to improve operator performance, maximise production efficiency and cutting tool service life.”

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