Tag Archives: Murray & Roberts Cementation

MURRAY & ROBERTS CEMENTATION MOCK-UP RAISES BAR FOR MECHANISED MINE TRAINING

Known for its extensive mine training offerings and innovative learning approaches, Murray & Roberts Cementation has further raised the bar with a ‘mock-up’ facility for underground mechanised mining. 

Tony Pretorius, Education, Training and Development Executive at Murray & Roberts Cementation, says the new installation is a quantum leap for mining-related training in Africa. Located at the Murray & Roberts Training Academy at the company’s Bentley Park complex near Carletonville in Gauteng, the new facility will give a fully immersive learning experience across the underground mining value chain.

“Our new mock-up facility is as close to a real mine as you can get,” Pretorius says. “Learners experience not only the look and feel of an underground bord-and-pillar mine, but even have the smells and sounds of such an operation.”

He emphasises that this experience is a valuable next step to complement the simulated and virtual reality platforms already provided to learners at the MRTA facility. To build skills, operators need to put their theoretical learning into practice – but the pressurised production environment of a real mine is often not the ideal location.

“Rather, our new facility provides a safe and low-cost learning environment, where learners can practice their skills without hindering production or compromising safety,” he says. “At the same time, they still get the sensory experience for developing the muscle memory they require for the real-life workplace.”

Equipped with essential first-line equipment such as drill rigs and bolters, the facility also has its own machinery for loading, hauling and dumping blasted rock. The realistic environment includes ventilation systems, support structures and blasting systems.

“Learners are taken through the full value chain of mechanised mining activities, from the waiting places, entry exam and safe declaration to the installation of support and cleaning of blasted rock,” says Pretorius. “They conduct marking, drilling and indexing of the face wall, charging up with inert explosives and simulating the blast with a centralised blasting system.”

He explains that MRTA’s extended reality framework follows the situational leadership model, which places considerable value on learner participation in activities – to entrench their applied competence. Built over recent years, the facility is housed in a large covered structure 3,5 metres high and covering some 1,125 m2. Together with its dedicated equipment, it represents an investment of over R35 million, he says.

PIONEERING VENT SHAFT AT PALABORA HOLES OUT SAFELY AT 1200 METRES

Leading underground mining contractor Murray & Roberts Cementation and its client Palabora Mining Company (PMC) celebrated the last blast at the new ventilation shaft, which took its depth to a final 1,200 metres below surface on 9 January 2024. 

The 8.5 metre diameter upcast vent shaft – which holed through to an already developed return air way at depth – is vital to PMC’s Lift II project. Lift II will develop access to ore resources sufficient to extend the life of this copper mine beyond 2040. Murray & Roberts Cementation Senior Project Manager Fred Durand says a key achievement was the project’s fatality free record, earned over more than a million hours worked.

“The achievement of a million fatality free hours – reached in November 2023 – is more than just a number,” says Durand. “It reflects the deep-rooted safety culture that has permeated every aspect of the project.” 

The innovative sinking methods, used for the first time in South Africa, were also carefully focused on achieving zero harm. Murray & Roberts Cementation employed its Canadian shaft sinking methodology, adapted to what became called ‘the PMC way’. This method included an innovative solution to poor ground conditions, where the sidewall of the shaft was closed up within 48 hours by means of the shaft concrete lining after every three metres of advance.

“Among the improvements that this facilitated was the removal of the hazardous work by rock drill operators at the shaft bottom, who would traditionally have to install temporary support,” he explains. “We also decided not to conduct concurrent work in the shaft, so there was no risk of danger to anyone below when work was carried out from the stage.”

He emphasises the close collaboration between Murray & Roberts Cementation and PMC to ensure the success and safety of the shaft sinking. The project was significant insofar as there were many lessons learnt which could be taken forward into future projects, he says, further improving the safety record of shaft sinking practice. 

“We are already looking ahead to two more important shaft sinking projects within the South African mining sector, where there is potential for certain of these learnings to be applied,” says Durand. A veteran of over 15 shaft sinking projects around Africa during his career, he admits finding aspects of the PMC way initially quite unusual when he joined the project in 2022. 

“Ultimately, though, we all want to deliver safe projects, so there are many brilliant ideas that we have proven on this project,” he says. “These strategies have been combined with the company’s leading mining and engineering expertise, and made us very excited about the future of shaft sinking and contract mining.”

To facilitate streamlined programming on the project, the work ran on continuous operations with two 12 hour shifts. He notes that this improves on the usual eight hour shift system, which requires three shift changes – each change taking up valuable project time. The two-shift system requires only a morning and evening change.

The vent shaft will replace the two existing vent shafts from the Lift I project, which are likely to be affected as they are in the Lift I zone of influence. In the final stages of the project, Murray & Roberts Cementation will strip out its services from the shaft, lift out the stage and dismantle the headgear. Final demobilisation of the company’s infrastructure will be carried out during the first quarter of 2024, says Durand.

LEADING UNDERGROUND MINING CONTRACTOR SERVES SECTOR ON MULTIPLE FRONTS

Leveraging over a century of experience, Murray & Roberts Cementation is working with some of the world’s most respected mining companies to pave the way for safe and efficient underground mining.

According to Graham Chamberlain, New Business Director at Murray & Roberts Cementation, the busy pipeline of projects demonstrates the mining sector’s faith in the company’s unsurpassed industry knowledge and depth of skills. In southern Africa, the main projects underway are at De Beers’ Venetia Mine, Ivanhoe Mines’ Platreef project and Palabora Mining Company.

At the Venetia Underground Project near Musina, work has been ongoing since 2013 in one of the largest investments in South Africa’s diamond industry in decades. Transitioning from opencast to underground mining will extend the mine’s life until 2046. Murray & Roberts Cementation has been engaged in sinking, lining and equipping of two shafts – the production and service shafts – to a depth of 1,080 metres. The company also developed a decline tunnel and is completing associated surface and underground infrastructure, in a project whose scope included raiseboring work to establish ventilation infrastructure.  

“In this maturing project, the mine is now getting into ore and starting to develop the infrastructure levels,” says Chamberlain. “At the shaft bottom, good progress continues to be made with the construction of workshops, pumping stations, silos and loading arrangements.”

Murray & Roberts Cementation is also conducting all the infrastructure development at Ivanhoe Mines’ Platreef project near Mokopane. This includes the sinking of a 5,1 metre ventilation shaft to meet horizontal development at 950 metres below surface. To achieve the high accuracy levels demanded by the project, the raiseboring equipment was guided by directional drilling technology. 

“A unique aspect of this project is that the shaft will be hoisting ore at that same time as allowing upcast air to reach surface,” he says. 

Another vent shaft by Murray & Roberts Cementation – measuring 8,5 metres in diameter and reaching a depth of 1,200 metres – is nearing completion at Palabora Mining Company near Phalaborwa. Part of the mine’s Lift II expansion, the project has earned an impeccable safety record – being fatality free and achieving 574 days without a Lost Time Injury (LTI) in 2022. Ground conditions were among the reasons why a blind sink was chosen as the optimal method instead of raiseboring, as the side walls needed immediate support to prevent scaling.

“We also have a number of services projects underway related to raiseboring, grout plants and rehabilitation,” he explains. “Much of our work in this field is focused on old infrastructure that requires maintenance, repairs or upgrades; we also conduct extensive vertical work in ore passes and silos.”

The company carries out vital rehabilitation in ore passes where ground conditions have deteriorated to prevent ore from moving smoothly – thereby risking production targets. Innovating safer techniques for this work, it has developed the tube-and-fill method, first applied about seven years ago at an underground platinum mine in South Africa. These installations are also expected to outlast the lifespan of an ore pass rehabilitated with traditional shotcrete.

“On the engineering front, we continue conducting rebuilds of underground mining equipment at our Bentley Park facility near Carletonville,” says Chamberlain. 

He highlights the work of the company’s design department, which remains extremely busy with feasibility studies associated with vertical work. With the renewed interest in commodity segments like copper, there is also previous work that customers are asking Murray & Roberts Cementation to review and update. 

Training in underground mining and related skills at the company’s world class Training Academy on Carletonville continues to empower many thousands of learners each year, he points out. This skills development is done on behalf of clients, as well as for the company’s own requirements.

“At any one time, we can host about 420 learners, and we are generally at full capacity,” he says. “We have just recently upgraded these facilities to further enhance training technologies that allows learning to take place safely but in a realistic environment.”

In compliance with many African countries’ localisation regulations, Murray & Roberts Cementation has registered companies in eight countries in the Southern African Development Community – most of which have seen the company active with raiseboring. Chamberlain notes that there are specific opportunities in Zambia that the company hopes to capitalise upon in the near future, and is encouraged by the mining sector’s progress in countries like Namibia and Botswana. 

MURRAY & ROBERTS CEMENTATION ACHIEVES 1 MILLION FATALITY FREE HOURS ON PMC VENT SHAFT

Murray & Roberts Cementation, a leader in underground mining contracting, recently marked a significant milestone in its vent shaft contract which forms part of the Palabora Mining Company (PMC) Lift II expansion project. On 2 November 2023, the company celebrated 1 Million Fatality Free hours, a testament to its unwavering commitment to safety and operational excellence.

This impressive achievement at the PMC Lift II expansion project is not just a numerical milestone but a testament to the shared commitment to safety and operational excellence by both Murray & Roberts Cementation and PMC. Crucial to PMC, the project will extend the life of operations to beyond 2040 with the 8.5 metre diameter ventilation shaft being integral to the Lift II block cave as part of its overall mining infrastructure. 

The vent shaft project’s complexity and technical challenges highlight the expertise and experience of all parties involved. Under the leadership of Fred Durand, Senior Project Manager at Murray & Roberts Cementation, the project team has consistently emphasised safe execution. Durand notes that the company’s stringent safety protocols have been pivotal in reaching this milestone.

“The achievement of 1 Million Fatality Free hours is more than just a number; it’s a reflection of the deep-rooted safety culture that permeates every aspect of the project,” Durand says. “From planning stages to daily operations, safety is the cornerstone of the project’s success, demonstrating that even in the most technically challenging environments, prioritising safety is key to achieving remarkable outcomes.”

Aidan Schoonbee, Senior Manager for PMC’s Lift II Construction, Concentrator and Vent Shaft, says that as the PMC Lift II project continues to progress, this milestone serves as a reminder of the importance of safety in the mining industry. “It is a shining example of how collaboration, expertise and a steadfast commitment to safety can lead to extraordinary achievements.”

DUAL-PURPOSE VENT SHAFT AT PLATREEF WILL ALSO HOIST ORE

In a project innovation that will allow early hoisting of ore at Ivanhoe Mines’ Platreef project, Murray & Roberts Cementation will be repurposing its 3 Shaft – a ventilation shaft – to serve a dual function.

“This is a unique project in many respects, as the shaft will be hoisting ore at that same time as allowing upcast air to reach surface,” explains Graham Chamberlain, New Business Director at Murray & Roberts Cementation. “We were able to bring our well experienced experts into the planning process to develop a safe and effective solution.”

The project has followed the sinking of the vent shaft by Murray & Roberts Cementation, which had required very accurate drilling, using raiseboring equipment guided by directional drilling technology. The 5,1 metre diameter shaft meets horizontal development at a depth of 950 metres below surface.

“During this process, Ivanhoe looked at bringing forward some of their ore generation activities, and this required adding hoisting capacity,” he explains. “The timeline for their main shaft meant that it would not be able to contribute to this capacity, so a team was established to consider how to retrofit the vent shaft into an early hoisting shaft.”

As an integral part of that multidisciplinary team, Murray & Roberts Cementation conducted a feasibility study on the options, allowing for the selection of the most suitable methodology. The company also carried out the necessary designs, including winders and headgear as well as hoisting and tipping arrangements. In September 2023, the project was awarded to Murray & Roberts Cementation to implement, and is scheduled to take about two years. 

“This project stands out in terms of innovation, adaptability, teamwork and design,” he says. “With our many decades in the sector, we were able to draw on hundreds of years of experience in mining – and leverage this in our design team.”

Among the range of technical challenges is the need to work within the vent shaft while it is performing its function of channelling an upcast current of air to surface. Any blockage of the air current in the shaft would affect the development operation of the mine, so this is critical to avoid.

“There needs to be periods during which we can reduce the ventilation, but we will have to ensure that air flow is always adequate,” he says. Another vent shaft is planned to add ventilation capacity for the future. 

Chamberlain points out that it will be necessary to deal with the slight deviations in the shaft; while accurately drilled, vent shafts are not designed to the same tolerances as hoist shafts. An important aspect of the design was the steelwork required to accommodate those deviations.

“The work will be conducted by a relatively small team of our highly skilled people,” he says. “This will include the installation of a compact headgear using refurbished winders from our strategic stockholding.”

The infrastructure will employ technology that will allow man-less operation to enhance safety, using automated processes in loading and measuring functions, for instance. The project will require specialised subcontractors on much of the equipment employed, but the more day-to-day consumables are procured locally to support local businesses. 

“In the absence of a supplier, we would then develop their capability through our procurement system and enterprise development commitment,” he says. “In this way, we foster small businesses and help to nurture them until they are self-sustaining.”

SAFETY TRAINING MUST KEEP UP WITH CHANGING TECHNOLOGIES

Training within the mining sector is a fast-changing field, driven by technological advancements, evolving safety standards and the need for a more skilled workforce. 

Keeping up with these demands has been the focus of the Murray & Roberts Cementation Training Academy near Carletonville, combined with ongoing attention on raising safety levels in pursuit of Zero Harm. According to Tony Pretorius, Education, Training and Development (ETD) Executive at Murray & Roberts Cementation, this has meant constantly pioneering effective strategies that build excellence and discipline in the workplace.

“An important foundation for us has been the integration of technology in our training programmes, incorporating tools such as virtual and augmented reality, e-learning, and online resources,” says Pretorius. “These technologies enhance the learning experience, improve knowledge retention, and facilitate the development of digital skills essential for working with advanced mining equipment and systems.”

At the same time, he highlights the promotion of a safety culture in mining. To achieve this, the academy places a strong emphasis on cultivating a safety-first mindset among trainees. By prioritising safety in all aspects of training, the academy helps instil a culture of vigilance, risk assessment and continuous learning – aligning with best practices for workplace safety in the mining industry.

“We also ensure that our training programmes align with relevant mining regulations,” says Pretorius. “This equips workers with the knowledge and skills to adhere to the latest safety guidelines while keeping their workplace compliant with regulatory requirements.”

An example of how digital technology has been leveraged in the learning space, he points to the academy’s use of virtual and augmented reality in the training process. These immersive technologies allow trainees to experience realistic, risk-free simulations of mining environments and scenarios. 

“This approach not only improves knowledge retention but also enables the identification and correction of potential mistakes before they occur in real-world situations,” he explains. 

Another important aspect of the modern training approach has been towards competency-based training. Here, the focus has shifted away from the mere completion of training programmes, to the more detailed assessment of competence of workers in their specific roles. The focus, therefore, is on the development of practical skills, knowledge and attitudes that lead to improved job performance and overall safety. Pretorius also points to the vital role of what were previously referred to as ‘soft skills’ – competencies which are today proving to be as important as technical skills. 

“In addition to technical skills, the mining industry recognises the importance of developing skills such as communication, leadership, teamwork and problem-solving,” he says. “These skills are vital for maintaining a safe working environment, especially in high risk situations where effective collaboration and decision-making can prevent accidents and save lives.”

Beyond the daily work tasks, workers are also having to become more aware of sustainability and environmental issues. This is inevitable, as the mining industry faces increased scrutiny regarding its environmental impact.

“Training programmes now include modules on sustainable mining practices, resource conservation and waste management,” he says. “This helps ensure that workers are aware of their responsibilities and the role they play in minimising the industry’s environmental footprint.”

MURRAY & ROBERTS CEMENTATION TAKES CENTRE STAGE AT CE SAFETY AWARDS

Murray & Roberts Cementation emerged as a shining beacon of commitment to safety at the annual Murray & Roberts Group’s CE Safety Recognition awards in June. These awards, which spotlight various operations across group companies, recognised Murray & Roberts Cementation for its exceptional safety  performance. As a leading underground mining contractor, the company has several projects under its belt that affirm its dedication to safety and the ultimate goal of achieving Zero Harm.

One of its standout projects is the Venetia Underground Project (VUP). Collaborating with De Beers Group, Murray & Roberts Cementation played a pivotal role in developing and equipping this underground mine which has seen the transition of Venetia Mine from an open pit operation to an underground mine. Hard work and emphasis on safety by the VUP team earned the project the accolade of ‘Best Employee Participation Programme (Leading Indicator Reporting)’. 

Trevor Schultz, Risk Executive at Murray & Roberts Cementation, explained the significance of leading indicators. “These are proactive and preventive measures that grant crucial insights into the safety performance of a project. They also act as an early warning system, shedding light on potential issues in a given work environment.”

In another feather in Murray & Roberts Cementation’s cap, the Palabora Mining Company Lift II project was awarded with the ‘Best Major Incidents Prevention Programme’. This was in acknowledgment of their exceptional work in both sub-categories being Critical Control Verifications and Critical Control  Assurance Audits. “Significantly, this project recently made headlines when, at the end of July 2023, it achieved a monumental feat by reaching the 1000-metre mark in its assignment to sink a 1200-metre ventilation shaft at PMC,” Schultz says. 

The accolades didn’t stop there. The Matla Mine Relocation Project was lauded with the ‘Best Safety Performance at Project Level’ award, thanks to its stellar 12 months rolling TRCR performance. 

In addition to this award, this project had zero work related injuries during its 22-month duration.

Schultz was proud to announce that a whopping 14 of the company’s projects were bestowed the title of Zero Harm Projects, meaning they had zero recordable cases. Such an impressive statistic doesn’t come easy. Schultz believes it’s the unwavering commitment from every single individual, from the full workforce on the ground to management, that has made this possible.

In conclusion Schultz emphasises the company’s resolute focus on training and developing its workforce. This is rooted in the belief that to truly embed safety and Zero Harm principles, it should become an integral part of everyone’s daily tasks on site. The recent recognitions stand as a testament to the company’s success in this endeavour.

ORE PASS REHAB TECHNOLOGY ADVANCES TO KEEP MINES PRODUCING

If the lifeblood of underground mines is the ore that must find its way to surface, then it is no exaggeration to describe the ore passes as the mines’ arteries – and the innovative tube-and-fill method of rehabilitating ore passes from Murray & Roberts Cementation is proving itself safer and more durable.

When the ground condition of an ore pass deteriorates and prevents ore from moving smoothly, production invariably comes to a halt, explains Pieter Oosthuysen, Senior Project Manager Mining Services at Murray & Roberts Cementation. Ore flow within a typical underground mine is managed through an extensive system of passes, which allows ore to drop to the bottom of the mine – from where it can be transported to the surface and processed. Over time, these passes deteriorate through a combination of normal wear and tear, abrasive wear due to rock flow, changes in the stresses upon them and the quality of surrounding geology.

“Current rehabilitation methods used in the market have variable levels of effectiveness and application, but the ultimate goal is to remove people from these hazardous environments and find more innovative ways of rehabilitating these excavations,” he says.

Murray & Roberts Cementation has been doing this vital rehabilitation work for decades, all the while developing better and safer technologies. Among its most exciting innovations has been Its tube-and-fill method, first applied about seven years ago at an underground platinum mine in South Africa. The early installations have proved so successful that they are expected to outlast the normal five to 10 year lifespan of an ore pass rehabilitated in the traditional way with shotcrete.

“With a well-established legacy as an underground mining contractor, we rehabilitate a wide range of underground mining infrastructure – and ore pass rehabilitation is an essential aspect of this,” says Oosthuysen. “The work is not only challenging but can be hazardous, so we approach this work with stringent safety systems in place, while also continuously looking for ways to avoid people having to be in potentially dangerous environments in the first place.”

In the tube-and-fill method of rehabilitation, a fibreglass tube is lowered down the ore pass once the pass is drained and cleared of all obstructions. A specialised mix of self-levelling concrete is then poured in from the top. This concrete – which is high strength and resistant to shear wear – fills the outside area between the tube and sidewall, creating a new lining of the ore pass system.

“The tube is essentially a sacrificial shutter that can be lowered down  the ore pass,” he explains. “This can be done without anyone having to climb down the ore pass, so using this methodology has a significant safety advantage.”

This is an important advance on the traditional method which requires people and material to enter the system every day – leading to relatively high exposure to hazardous areas. In addition to being labour intensive, it also requires a rock engineer to inspect regularly and frequently – to give recommendations and approve the installed support.

At the heart of the tube-and-fill method are reinforced rings of special  fibreglass,   with varying diameters up to a maximum of 3.5 m. The use of relatively light fibreglass – instead of much heavier material like steel – makes it possible to easily transport the tube segments and to assemble them underground. With a tube segment weighing just 80 kg, this means that a tube for a 60 m ore pass will weigh only around 5 t.

At the same time, the reinforced design enables the fibreglass to withstand considerable hydrostatic pressure from the concrete being pumped on the outside. The concrete mix – designed in collaboration with concrete and admixture producers – is able to achieve final UCS strengths of up to 70 MPa.

“When replacing the original rock into which an ore pass has been created, we attempt to get our linings as close as possible to that rock strength,” he says. “This specialised concrete mix design allows us to achieve close to 50% of the original rock strength.”

He notes that the mass fill product also creates a more abrasive  lining when compared to the shotcrete sprayed lining.

Fanie van Emmenes, Project Manager Mining Services at Murray & Roberts Cementation highlights that the early tube-and-fill installations are proving more durable than the traditional shotcreting approach. This, points out Van Emmenes, also demonstrates that it is more cost effective over the life of the mine.

Murray & Roberts Cementation considers a range of options for customers when proposing solutions for underground rehabilitation. Another method that is used for ore pass rehabilitation is to lower a specialised robotic shotcrete unit into the ore pass, where it applies the concrete to the sidewall without the need for personnel to enter this hazardous zone. One of the limitations, however, is that the level of scaling cannot be too advanced, and this method is used for preconditioning of the ore passes immediately after being developed

The mass fill and redrilling of the ore pass is yet another option. Here, the whole ore pass is filled with low-strength concrete, and a raisebore machine redrills through the mass fill to create a new ore pass system. Irrespective of the method, he says, safety remains the priority – with Murray & Roberts Cementation’s comprehensive and proven protocols earning the company an enviable safety record.

“This includes proper ventilation systems, monitoring for hazardous gases, personal protective equipment (PPE), and emergency response plans,” he says. “We also ensure adequate training and supervision, which are essential to mitigate safety risks.” Oosthuysen concludes that the success of the tube-and-fill method would make it the company’s first choice for most applications. He argues that this approach is likely to see increased uptake as the durability of the initial installations become well known.

MURRAY & ROBERTS CEMENTATION REACHES MONUMENTAL MILESTONE ON PMC VENT SHAFT

Leading underground mining contracting company, Murray & Roberts Cementation achieved a remarkable milestone at the end of July 2023 when it successfully reached the 1000 metre mark on its contract to sink the 1200 metre ventilation shaft at PMC’s Lift II expansion. This significant feat stands as a testament to the company’s exceptional capabilities and dedication to safety.

The Palabora Mining Company Lift II expansion project is a crucial endeavour for PMC, aimed at enhancing the efficiency and capacity of their operations. The 8.5 metre diameter ventilation shaft will serve the Lift II block cave and plays a pivotal role in the overall mining infrastructure.

Some of the Murray & Roberts Cementation team celebrating reaching the 1000 metres mark on the ventilation shaft sink at PMC.
Some of the Murray & Roberts Cementation team celebrating reaching the 1000 metres mark on the ventilation shaft sink at PMC.

Reaching a depth of 1000 metres in the ventilation shaft is a major accomplishment, highlighting the expertise and commitment of Murray & Roberts Cementation in tackling complex mining projects. The company’s ability to execute such a technically challenging task underscores their reputation as a reliable and competent partner in the mining industry.

Fred Durand, Murray & Roberts Cementation’s Senior Project Manager, says one of the most remarkable aspects of this project is the unwavering focus on safety. “Despite the immense challenges involved in underground mining and especially blind sinking, we have maintained an impeccable safety record throughout the Lift II expansion project. The team’s relentless dedication to safety protocols and best practices resulted in an impressive milestone earlier this year of 574 consecutive days without a Lost Time Injury (LTI).”

He says that the achievement of this remarkable safety milestone showcases the company’s commitment to ensuring the wellbeing and safety of its workforce. It demonstrates that, alongside its technical competency, Murray & Roberts Cementation prioritises the welfare of its employees and strives for a Zero Harm work environment.

“As the ventilation shaft project enters its final stages, the excitement and anticipation among all stakeholders, including PMC and Murray & Roberts Cementation, are palpable. The successful completion of this project will not only mark a significant engineering feat but will also have a profound impact on PMC’s mining capabilities,” Durand concludes.

Aidan Schoonbee, Senior Manager for PMC’s Lift II Construction, Concentrator and Vent Shaft congratulated the Murray & Roberts Cementation team and praised the collaboration that had been achieved between employer and contractor. Murray & Roberts Cementation has aligned with the owner’s team to display technical excellence, professional management and passionate safety leadership from the day site establishment commenced in October 2019, he says.

PALABORA’S VENT SHAFT A TRIUMPH OF COLLABORATION

The sinking of a 1,200 metre ventilation shaft as part of the Palabora Mining Company (PMC) Lift 2 expansion is proving to be a partnership success story, based on an unshakeable commitment to safety.

PMC commissioned this new ventilation shaft – which measures 8,5 metres in diameter – to service its Lift 2 block cave, awarding the project to Murray & Roberts Cementation in February 2019. Now in its final phases, the project has earned an impeccable safety record; it has been fatality-free, and last year achieved 574 days without a Lost Time Injury (LTI).

An excavator busy lashing at the shaft bottom with shaft lining being carried out on the face.
An excavator busy lashing at the shaft bottom with shaft lining being carried out on the face.

“Feasibility studies indicated that a blind sink was the optimal method, despite its higher cost and longer timeframe,” says Jas Malherbe, Murray & Roberts Cementation’s Project Manager. “Ground conditions were among the reasons why raiseboring was not an option, as the side walls needed immediate support to prevent scaling.”

Traditionally, the shaft would be lined to within 12 metres to 18 metres of the shaft bottom, with the sidewalls being temporarily supported with split sets and mesh. However, the difficult ground conditions led to high levels of scaling that made this practice unviable.

Murray & Roberts Cementation was awarded the contract to sink and line a ventilation shaft at PMC.
Murray & Roberts Cementation was awarded the contract to sink and line a ventilation shaft at PMC.

“With ground conditions being such a key challenge on the project, we responded in an innovative way by taking the shaft lining right down to the blasted face,” he says. “The shaft sinking methodology in this project is therefore based on the Canadian shaft sinking method pioneered by Murray & Roberts Cementation – but has been adapted to ‘the PMC way’. This has involved lining the shaft to within 1,5 metres of the shaft bottom, after mucking out the waste.”

Murray & Roberts Cementation use a specialised concrete mix for rapid setting and early strength which hardens to 3 MPa within four hours – and this would be in place for at least eight hours before blasting. This solution requires that the blast is conducted while the shutters are still in place – so the shutters are strengthened and a toe added that would better handle the blast. The exposed concrete above the shutter is able to withstand the blast, as it has already cured for 48 hours.

PMC took a deliberate decision to prioritise safety in the sinking of the ventilation shaft.
PMC took a deliberate decision to prioritise safety in the sinking of the ventilation shaft.

Malherbe explains that drilling is undertaken by two twin-boom electro-hydraulic jumbo drill rigs. These are slung down the shaft from surface and nested in the four-deck stage for drilling the shaft bottom, a procedure which is repeated for each 48 hour blast-to-blast cycle. Waste rock is lashed using an excavator with a 0,36 cubic metre bucket, which is lowered from surface through the stage to shaft bottom.

After blasting, an excavator is used for loading rock from the shaft bottom, which is safer than the conventional cactus grab. Ground conditions lend themselves to the generation of large rocks during blasting, which can be difficult to handle. These are broken up using an hydraulic breaker, which can be coupled to the excavator. An 11-tonne kibble transports the waste rock to surface.

“Lashing a shaft with an excavator is not a new idea, but it is usually a back-up method to the cactus grab,” he says. “In this project, we decided that the excavator would be the primary lashing method, to further enhance safety on site.”

Steps have also been taken towards automating the headgear, to avoid the safety hazards of manually hooking the kibble to tip out the waste rock. This includes the winding engine driver being able to use a camera to check for correct hooking.

“We also opted to use electric actuators in this project, rather than the traditional pneumatic and hydraulic cylinders on equipment such as the bank doors, swing chutes and tipping chutes,” he continues. “This has allowed us to mitigate the risks such as hearing loss from the noise of certain actuators, and contamination from oil leaks.”

According to Sechaba Letaba, PMC’s Package Manager on the project, PMC took a deliberate decision to prioritise safety in the sinking of this ventilation shaft.

“By taking the PMC way, we have accepted that the pace of sinking would have to be compromised,” says Letaba. “This has proved to be a positive approach, as we have an outstanding safety record on the project. This is in stark contrast to the history of shaft sinking, which would often claim lives and cause injuries. We are therefore very proud of what we have achieved to date.”

He highlights the pivotal roles played by Sam Ngidi, PMC Senior Manager Operation & Lift 2 Project, and Aidan Schoonbee, Senior Project Manager Construction – in driving the project and ensuring its success.

Fred Durand, Murray & Roberts Cementation’s Senior Project Manager, points out that unexpected challenges tend to have an impact on scheduling, so the strong relationship of trust with PMC was vital to solving any issues as they arose.

“Our approach has always been to work closely with customers on solutions, and to ensure they are regularly updated on progress,” says Durand. “As a team, for instance, we decided that the rock breaker was the right solution for the issue of oversized rocks, and it was accepted that this would have an impact on the cycle times.”

Similarly, encountering more challenging ground conditions than expected required a significant mind-set change about how the team approached the project.

“With the supportive relationship between PMC and Murray & Roberts Cementation, we were able to agree on the necessary remedies and adjust the timeframe to suit our priority – which was safety,” he says.

Letaba emphasises that relationships between the client, the contractor, suppliers, employees and surrounding communities are vital to success. This project is testament to this fact, he says, and to the professionalism of Murray & Roberts Cementation.

“It is a pleasure to be serviced by a company like this, who proactively put world class safety measures in place,” he says. “We look forward to completing the final phases of the shaft in the same safe manner.”

Malherbe concludes that, for Murray & Roberts Cementation, the lessons learnt on this project have shown the industry a viable alternative method of shaft sinking that takes safety to a new level.