Automation moves mill reline crews out of harm’s way and delivers opportunities to boost throughput
Mill maintenance downtime directly affects production. For SAG, AG, and ball mills, this necessary maintenance window also poses safety risks for personnel relining the mill.
Australian OEM and global leader in fast, reliable and safe mill relining systems, RUSSELL MINERAL EQUIPMENT (RME) has materialised its future-state vision where liner exchange can be performed faster and without crews inside. This paradigm shift improves safety and commercial performance for mineral concentrators. As the industry faces increasing ore grade variability and pressure to increase mineral supply for the energy transition, this capability offers a timely and valuable solution.
At SAG 2023 in Vancouver, RME demonstrated that one of its copper-producing customers has successfully relocated reline crews outside the mill during liner exchange, eliminating many of the remaining risks traditionally associated with this critical-path task. This system is nearing business-as-usual operational status across this site’s three SAG mills.
This article explores the engineering approach behind automated mill relining, its commercial progress, and its potential for industry-wide adoption for a safer, more efficient future.
Innovating for a safer, more efficient future
Comminution is the process of reducing particle size and is a critical step in the liberation of metal from hard rock. While various new grinding methodologies have emerged, SAG mills remain the preferred technology due to their robustness, simplicity, effectiveness, efficiency at scale and process flexibility.1
The aggressive mill environment wears the mill’s liners out, necessitating regular replacement at considerable labour and lost production costs during shutdown. RME’s filmed studies have found that relining can account for anywhere between 2-5% of lost annual mill availability, and in some cases, even up to 10%, affecting overall production.
Relining poses risks for some reline crews, with hazards comparable to those seen in underground mining. Mechanisation has mitigated many, but not all, occupational safety issues; crews still encounter confined spaces, working at-height and under multi-ton suspended loads, and proximity to heavy mobile machinery.
Figure 1: Examples of safety hazards and risk that reline crews can still encounter during grinding mill relining.
For four decades, RME has collaborated with customers to identify areas where innovative engineering solutions can create economic and safety benefits. These efforts have culminated in the ‘RME Mill Relining System’, a suite of technologies for every relining step – knock-in, muck-out, removal and placement – that have transformed industry safety and performance.
The introduction of the first RUSSELL Mill Relining Machines marked a significant breakthrough, overcoming manual handling limitations and enabling larger liners, fewer change-outs and faster reline times. This innovation also paved the way for the larger SAG mills used today. RME has played a pivotal role in elevating the standard of mill relining as a profession through its accredited training programs.
RME understood from its work with mill operators and reline crews that some risks remained in certain parts of the process. ‘Liners For Profit and Performance’ also emerged in the company’s research, that is, the potential for higher throughput with thinner liners, rather than the common practice of using thicker ones optimised for longer life. This approach aims to eliminate lower throughput periods at the start and end of liner life. However, it knew that mill operators would only consider more frequent change-outs if shutdowns became even safer and faster.
So, the goal became clear: the industry had to move reline crews out of the line of fire and create opportunities for greater throughput and concentrator performance.
Engineering the risk out of mill relining
Leveraging its global OEM knowledge and extensive site experience, RME embarked on a mission to engineer the risk out of relining, utilising automation and innovative ‘INSIDEOUT’ tooling to eliminate or substitute hazardous and manually repetitive tasks. R&D has occurred in collaboration with early adopter customers, liner suppliers, and reline crews.
RME applied ‘systems engineering’ principles, recognising that safe automation required a holistic approach because any change to external processes had to consider corresponding activities within the mill, and vice versa. Safe automation also demanded complete removal of crews from the mill due to confined space and human-robot interaction risks.
Automating proven, familiar methods
RME long observed the mining sector’s justifiable caution towards new technologies, including concerns about technical integration challenges and production risk. For some mill operators, even one hour of extra downtime can cost upwards of US$200,000 in lost throughput.
The company’s solution automates well-established, confidently used and trusted technologies. By roboticising proven systems which crews are well-versed in, sites can mitigate the disruptions typically associated with the introduction of completely unfamiliar processes and technologies.
Figure 2: An overview of the engineering controls developed by RME to ‘engineer the risk out of relining’ for mill operators and reline crews.
RME’s approach also applied sound change management principles enabled by modular platform engineering which facilitates the gradual introduction of safer methodologies during normal maintenance windows. This incremental approach fosters cultural adoption for reline crews, who can be trained concurrently as new processes are introduced, delivering a successful transition to safer and faster relining practices.
Sites demonstrate compelling benefits from automation
Automation delivers a threefold advantage. Firstly, it eliminates human-machine interaction. Secondly, it reduces skill-variability associated with manual machine operation, leading to more predictable reline durations. Thirdly, it enables accelerated machine movements, consistently and repeatedly, resulting in shorter shutdowns and higher mill availability.
These automation benefits are evident in RME’s early adopter site data. With RME's Indonesian customer, automating the liner removal phase alone delivered a 56% reduction in risk exposure inside the mill and a 29% reduction in liner replacement time, compared to conventional relining. Reline crew size has also been reduced by 32%, with personnel redeployed to other shutdown activities.²
Figure 3: Real-world mill relining performance data for a 38’ SAG Mill site in Indonesia using products from RME’s Advanced Technology suite. (2)(3)
With additional automation and process improvements planned, RME and this site are targeting and overall 85% risk exposure reduction and 50%+ reduction in reline time compared to historical performance. RME believes this demonstrates that mill relining will soon no longer be the critical-path shutdown activity.³
An engagement model for improving industry safety and concentrator performance
Over 30 relines globally have now used RME’s Advanced Technology Mill Relining System, demonstrating its broad applicability. The numbers of liners handled by the company’s automation-enabling technologies is growing at a rate of approximately 20% a year, and studies from these relines demonstrate that these methodologies are safer and faster. Early adopters tend to be larger mills, longer-life mines, and high-altitude sites facing operator fatigue concerns.
Figure 4: The RME Advanced Technology Mill Relining System is a suite of products engineered to enable safer and faster relining from outside the mill.
Mill operators appreciate that RME's incremental adoption approach offers commercial and implementation flexibility, as this platform has been purpose-engineered to allow mill operators to deploy a base system and optimise over time. It enables most sites to adopt best practices and achieve significant risk reduction within their economic and operational constraints. Some RME INSIDEOUT Technology tooling, such as the grapple device used during ‘muck-out’ to eliminate liner slinging and the presence of reline crews on the charge, does not require automation technology. This optionality will foster wider adoption of safer mill relining practises across mills of all sizes, and set new standards for industry safety.
Figure 5: The RUSSELL Claw reduces crew inside the mill during ‘muck-out’ and eliminates hazardous manual slinging. It does not require automation and can be retrofitted to most RUSSELL 7-axis and 8-axis Mill Relining Machines.
RME's goal is for reline crews to champion safer, faster relining, recognising the career and well-being benefits of expanding their skill-set to utilise automation for enhancing safety and productivity. At the customer site in Indonesia, the progressive introduction of automation, coupled with evident safety and speed benefits, has seen crews take full ownership of the process.
Figure 6: RME’s modular platform engineering and staged implementation program ensures faster and safer relining methods are readily accessible to all grinding mills.
As the mining sector strives to meet rising global demand for minerals needed for the energy transition, mill relining automation can play its part in this new era for safety and mill availability.
Learn more
Join the mill relining automation conversation at the 2024 Mill Operators Conference on Day 3, Session 11. RME’s session will walk through the specific methodologies that enable crews to reline from outside the mill, share valuable lessons learned from customer implementations, and present the latest site data on the commercial impact of mill relining automation.
References:
(1) Copper to the World 2024: ‘Engineering the Next Innovations in Copper Processing’ by J. Pease
(2) SAG 2023: ‘PTFI & RME Collaboration: Technology Makes Mill Relines Safer and More Efficient’ by A. Raharjo, J. Wilmot, A. Manuel, S. Suhono, S. Smith, W. Herbertson, & J. Bohorquez
(3) Comprehensive mill relining performance data is captured with video and measured by RME's MILL RELINE DIRECTOR (MRD) Discrete Event Simulation platform.