Reinforcing the Rock Mass

E&MJ looks at advances in ground support components and their installation with six key suppliers

By Carly Leonida, European Editor

As underground mines deplete their richest, shallowest resources, many are delving deeper, following extensions of the orebodies upon which they’re based. While increased depth may equal access to fresh resources, in most cases, it also brings higher rock stresses which can lead to difficult ground conditions. As such, the quantity and complexity of the support systems required to keep operations safe and productive is of increasing concern. Legacy bolting equipment and bolt types can struggle in extreme ground conditions, and this is driving the development of new solutions.

Peter Bray, Global Product Manager for Rock Reinforcement Equipment at Epiroc, spoke to E&MJ about this. “There has been a noticeable increase in demand for dedicated bolting equipment over the past decade,” he said. “This is partially driven by the higher volumes of bolts required underground, but it’s also driven by an industry that’s placing a greater emphasis on safety. These dual factors have had a marked effect on the design and functionality of mechanized bolting equipment.”

Peter Young, Product Manager for Bolting, at Sandvik Mining and Rock Solutions’ Ground Support Division, added: “Deeper mines mean higher rock stress levels, greater seismicity, different rock mass qualities and environmental factors, such as warmer working conditions. Greater reinforcement is required, as well as dynamic ground support and advanced monitoring. These factors all impact rock support and equipment design, requiring different bolt types, mesh installation for the walls, roof and face, increased equipment automation and remote operations, and data collection from the complete bolt installation process.”

High-stress conditions often lead to broken, fractured rock masses. Installation of bolts in these types of ground can be challenging, leading to longer installation times and questionable quality of the installation. As such, rock bolting is a common bottleneck for underground hard-rock mining operations. Balancing productivity and installation quality is a challenge that equipment and consumable suppliers are currently working to solve.

Another major challenge is capital investment. For most mines, ground support systems represent a substantial investment which must be balanced against the life of the system and its individual components, and the overall safety requirements throughout the life of the operation and/or stage of mining.

Renier Koekemoer, Senior Product Manager for Hard Rock Drills at Komatsu, explained: “Due to the cyclical nature of mining where production is dependent on a mining method that’s as continuous as possible, the end goal for suppliers and miners is to install the right ground support system for their application as quickly as possible. This system needs to meet all their requirements which, first and foremost, include ensuring the safe, day-to-day operation of their mine by employees and equipment.”

These factors, alongside a drive for continuous improvement, have helped the industry develop a range of specialized and targeted ground support systems. “It has also stimulated the growth and sharing of ground-support knowledge on an international scale,” said Koekemoer. “We’re seeing broader collaboration from suppliers and miners worldwide to ensure the right ground support system is selected for each application — a selection sometimes based on what works in other segments with similar constraints.”

Rising to the Challenges

A significant portion of the above challenges come from the costs associated with mining practices. As mines get deeper, traditional mining methods are challenged and many operations now lean heavily on innovative technologies to speed the development and reinforcement process.

Paul Stephenson, CEO of DSI Canada’s Ground Support Division, explained: “One example of this is the move towards battery-electric vehicles and the integration of bolting into automated equipment — this is all about the removal of people from the underground environment and also to speed the development of orebodies for recovery.”

Operational challenges combined with inflationary pressures mean that reinforcement practices have had to become more efficient to keep pace. The move towards the mechanization of smaller mining sections has been a key trend. Mechanization can speed up cycle times for ground support installation, but more importantly, it removes the operator from the hazardous space directly below the bolter and places them in a safe operator compartment. Continuous development towards semi and fully-autonomous ground support installations also maintains this.

Today, many mines use ground support systems that have been tailored to their specific requirements and some of these are pushing the envelope for both production and safety. They achieve this through greatly reducing the time that operators are exposed to hazardous conditions and through diversity of ground support, using the latest technologies to meet their individual requirements which could change on a day-by-day or even drift-by-drift basis.

“With mining conditions becoming more challenging, there is a need for more mine-specific ground support products,” said Derek Hird, CEO of DSI Australia’s Ground Support Division. “It’s no longer about one product for all applications. Rock reinforcement needs to be adapted to the mine’s conditions to achieve the desired performance.”

Given the increased depth of mines and their susceptibility to both natural and induced seismicity, many recent design improvements for bolts have focused on dynamic performance. Others provide additional value through increased load capacity which lessens the requirement for support. A simplistic installation process also speeds up development rates, and there has been a greater focus on single-pass bolting technology in harsh environments in recent years. Sustainability is another growing trend, with some manufacturers looking to incorporate recycled packaging materials, while others are looking to longer-term items, like green steel.

Let’s look at some of the latest solutions available on the market… 

Epiroc’s Auto-Bolt Reload Gains Traction

Epiroc has been collaborating with key industry partners in recent years to develop a bolting system that utilizes Self Drilling Anchors (SDA) and pumpable resins. SDA bolts are not as sensitive to variable ground conditions as some other bolt types and offer consistently fast installation regardless of the rock conditions.

Bray explained: “When the SDA bolts are combined with pumpable resin, we can achieve fast setting times, as well as the ability to fill cracks and voids within the rock mass. This helps to consolidate the ground, arrest ground movement quickly and ensure full encapsulation of the bolt. With a fully encapsulated bolt, the bolt is protected from corrosion, and this also allows load transfer over its full length. Another benefit is that pumpable resin is not sensitive to wet ground conditions, which can be an issue for some underground operations. SDA bolts are also easy to install in combination with mesh.”

The SDA/pumpable resin solution has become a welcome new tool for geotechnical engineers. Epiroc launched the first Boltec rig with a pumpable resin system in 2018. Since then, it has delivered dozens of machines to mining operations globally.

Bray said that, since its launch in September 2022, Epiroc’s new Boltec rig with Auto-Bolt Reload (ABR) functionality has seen strong market interest. The main design feature of the Boltec ABR is the fully mechanized bolt reloading system. This means that the system automatically feeds bolts from a large carrier magazine to the feed magazine while the operator remains safe inside the cabin. This innovation removes the need for manually reloading the feed magazine, thereby protecting the operator from potential trip hazards or falls of ground.

“This is a huge step forward in improving operator safety,” Bray told E&MJ. “Epiroc is in discussions with several customers who are interested in taking up the new functionalities and capabilities that the ABR system provides. The next steps in the development of the ABR system are in line with autonomous functionalities and these will be a significant step forward on the rock reinforcement automation journey.”

He added that Epiroc is soon to deliver a prototype Boltec E10 S ABR machine to a customer for a field test. This will explore autonomous functionalities that will reduce the need for operators to be physically onboard the bolting machine.

“Automation, information sharing, smart bolts, and guidance systems are just some of the industry trends and technologies that are being worked into our development plans for rock reinforcement equipment,” said Bray. “It’s a very dynamic environment at the moment, which keeps Epiroc’s R&D department busy. There is never a dull day when working with bolting equipment!”

Komatsu’s ZB21 Goes from Strength to Strength

Komatsu has been engaged in ground support in a variety of ways for a long time, including in both hard rock and coal/industrial minerals applications. The company’s latest product for ground support is the ZB21 bolter which was launched, along with the ZJ21 jumbo drill, in November 2020. The ZB21 is designed specifically for bolting in hard-rock mines with restrictive tunnel sizes. It delivers long-lasting and continuous ground support installations in challenging conditions.

Koekemoer explained: “The ZB21 can achieve this largely due to the innovative design that allows the bolter to be extremely flexible and versatile while maintaining the high degree of reliability and ruggedness required from a hydraulically operated, mechanized bolter. One of its features is a patented screen handling system that is part of the bolting head itself, thus eliminating the need for additional booms or damage-prone attachments. These features, coupled with an agnostic approach to matching the Komatsu ZB21 with a variety of both ground support and drilling consumables, further extends the flexibility of this machine.”

Since 2021, Komatsu has been working with J-LOK Co, an affiliate of Pittsburgh-based JENNMAR, to develop pumpable resin solutions for underground hard-rock mining customers. Koekemoer told E&MJ that the companies have recently entered the final round of validation tests for an onboard, self-contained bulk resin system that features all the trademark benefits of the Jennmar J-LOK products combined with the innovative capabilities of the ZB21 mechanized bolter.

This development will be available through the Komatsu drilling solutions group to allow for the conversion of nearly any host unit, further extending the ZB21’s application across almost the entire market.

“The ZB21 continues to go from strength to strength as we see it being adopted in various markets ranging from Canada to remote and distant applications in Southern America,” said Koekemoer. “This will continue to expand, as the ZB21 also meets the requirements of mines in Africa and beyond. Although the machine launched with some unique challenges, the feedback and acceptance has been fantastic and definitely lays the foundation for the continuous development of this and other products designed to meet customers’ needs and requirements.”

Normet: Creating Perfect Product Pairings

Rock bolts and cables are just two components of a larger system used to secure the rock mass which also encompasses grout. These three elements are inseparable. Normet has seen great success over the years with its D-bolt, but Martin Petranek, Director for Products and Production in Rock Reinforcement, said the company has much more to offer.

“In rock reinforcement, Normet is known as the D-bolt, supplier and many customers were putting us in a ‘one dynamic bolt specialty class’ supplier box,” he said. “While Normet still mostly specializes in rock reinforcement for challenging environments, we have much more to offer.

“In the past five years, we’ve developed new bolts designed for unstable, fractured ground or ground under high stress. We’ve also developed matching grouts to create a complete solution for almost any challenging condition. For example, our Locally Anchored Self-drilling Hollow Rock Bolts and RBG Thixotropic resin grout are the perfect combination; the grout not only matches the performance of the steel used for bolt production, it actually enhances the performance of the steel.”

In June 2022, Normet announced its acquisition of Garock Pty Ltd, a leading manufacturer and supplier of ground support systems for the mining and civil industries in Australia. This move not only strengthened the company’s portfolio in dynamic ground support for underground mining — specifically with cable bolts and dynamic cables — it also extended its reach into the Asia-Pacific market. Garock’s Australian facility is now Normet’s Global Centre for Rock Reinforcement research and development (R&D).

“Our R&D activities are heavily influenced by high-performance equipment for underground mining,” said Petranek. “Productivity is continuously increasing, and we need our productivity — in other words safety — to be ahead of them otherwise operations have to slow down. Other major influences come from Mother Nature; underground mines are getting deeper with faster developments. Our rock reinforcement systems provide a means for re-directing rock forces to help
stabilize the rock mass instead of it doing damage. This is a never-ending battle and it brings the joy of challenge to this business.”

Sandvik and DSI Join Forces

The integration of DSI Underground into Sandvik Mining and Rock Solutions’ Ground Support division in 2021 positions the company as a leading provider of equipment and consumables for underground hard-rock mining and tunneling.

Peter Young, Product Manager for Bolting in Sandvik Mining and Rock Solutions’ Ground Support Division, explained: “Customers benefit from the additional value and expertise of these equipment and consumables suppliers working together to better understand their requirements. The Sandvik and DSI offerings are available separately or as a combined package, allowing customers to customize their fleet to support their operational needs.”

The i-series are Sandvik’s latest bolters. The range includes the DS412i, DS412iE, DS422i and DS512i models. The i platform offers various levels of automation for rock support drilling. The high level of data collection during bolting allows operators to tell how well drifts and tunnels are supported with the possibility to document this information. The i-series also allows for off-grid drilling and bolting, and Sandvik’s patented Charging While Drilling technology means the DS412iE doesn’t need to draw from mine power network. It also offers a reduced charging time of less than 30 minutes per cycle.

In February 2023, Sandvik launched xCell Cyclops, a convergence system for ground support in underground mining that provides wireless, continuous, remote and real-time measurement of ground movements. It features built-in notifications and alarms to support a safer and more sustainable work environment.

xCell Cyclops enables remote assessment of rock mass behavior, which leads to safer, more efficient and cost-effective ground support and optimized ground rehabilitation. Through wireless, connected devices and a user-friendly online platform, customers can adapt their individual setup and track any changes in the mine’s ground conditions.

The retrofittable design of the sensors makes them easy to install directly onto existing rock bolts. They are battery-powered and operate with highly accurate laser measurements, and can be connected via both Wi-Fi and Bluetooth, providing operators with real-time access to data, built-in notifications and alarms. This setup reduces the need for manual work and inspections in the mine, reducing costs and improving safety.

The xCell Cyclops system is available as a subscription service with three levels: Basic, Silver and Gold depending on the number of users at a site and devices in remote mode. Young said that interest in the system is so strong that a second intrinsically safe version for soft rock and coal mines is already under development.

In terms of rock bolts, Sandvik and DSI have been working to expand their range of solutions for hard-rock mining. The companies’ most important dynamic anchors include: the POSIMIX Resin Bolt, Combination Bolt, the OneStep Bolt (a patent DSI bought from Hilti), KINLOC and the KINLOC Indie Bolt, the Inflatable OMEGA-BOLT and the MD / MDX Bolt which was originally developed by Sandvik Australia and has now been integrated into DSI’s product portfolio.

At the bauma 2022 exhibition in Munich last October, DSI showcased two dynamic bolts. The KINLOC Indie is a premium point-anchored friction bolt that offers high-capacity performance to 250 kN. Point anchoring is independent of the friction bolt body providing stable anchoring during ground movement and shock loads. The Mechanical Dynamic Extra — or MDX — bolt was also on display. This offers extra expansion and anchoring capabilities thanks to a unique wedge design that allows it to expand by up to 60mm. While the MDX provides good support in squeezing ground, the way in which the shell, the wedges and the rebar interact also makes it perfect for use in seismic ground conditions.

In addition, DSI and Sandvik are expanding their range of injection chemicals, for instance, for use with DSI’s Mineral Bolt. DSI recently expanded its production capacity for injection resins and foams to over 20,000 t/y, and the production of FASLOC resin capsules to over 60,000,000 per year. These are produced locally in Brazil, Canada, Poland, South Africa, and Australia using a just-in-time supply system for greater efficiency.

SSAB: Quality, Safety and Sustainability

SSAB’s inflatable rock bolt provides instant support and a quick installation process. Sara Valentin Eklöw, Site Manager and Sales Director at the Virsbo mill where the inflatable rock bolts are produced, spoke to E&MJ about this.

“The main challenge for rock reinforcement remains finding the best possible product given the prerequisites of the rock, especially as mines go deeper and rock movements increase,” she said. “At the same time, bolting is a time consuming activity and needs to be kept at a high pace, which is why we believe inflatable bolts fit well into solving many miners rock reinforcement challenges. They meet the requirements for safety and productivity as well as sustainability, using only high-pressure water to be installed.”

Eklöw added: “We are further developing the coated version of this product to prolong the life of the bolts in corrosive environments. We also see possibilities in creating stronger inflatable products than those that are available on the market today, which could reduce both steel needs and costs.”

SSAB is known globally for its high-quality steel as well as its rock bolts and Eklöw said that, next to safety, quality is the most important area for the company’s R&D efforts.

“We are always striving to improve on quality,” she said. “Also, with using only SSAB steel, we know the complete history of the material properties from the steel mill to the finished product, which helps us in producing the best possible inflatable bolt.

“Developing products that increase the speed of installation with higher corrosion resistance have been key development activities during the past decade, but there are still improvements to be made in terms of more efficient products. I also believe that lots of product development can still be made within rock reinforcement around softer parameters, such as environmental impact and quality. SSAB is leading the development of fossil-free steel, which will bring sustainable solutions to the mining industry in the coming years. Sustainability trends are yet to come into rock reinforcement, but the impact could be significant.”