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By Phil Dakin, Rajiv Chandramohan, John Lo Grande, Greg Lane

Crushing and grinding circuit availability is a critical design factor defining the installed equipment selection and the process buffers required to maintain throughput during maintenance. The comminution circuit typically accounts for a process plant’s largest capital expenditure and energy use. Effective process and equipment selection and layout optimization are crucial steps when combining the objectives of cost-effective design and high circuit availability in operation. This paper outlines fit-for-purpose design principles for optimizing process flow, eliminating standby equipment and reducing buffer residence time whilst improving maintainability and operability.

Feb 1, 2025

By Daniel Roy, Danielle Bouffard, Antoine Berton, Simon Gariépy

Commissioning a mineral processing plant has always been a challenging task. The process includes pre- operational verification, dry and wet commissioning, and a gradual ramp-up to full production, all of which must be executed within the shortest possible timeframe, requiring numerous highly interdependent tasks to be conducted concurrently. This phase is under scrutiny by shareholders, corporate management, and other stakeholders who are keen to see a return on investment as the operation starts yielding results. Despite extensive documentation in the literature highlighting its significance, the impact of the commissioning phase remains underestimated in contemporary mining projects. This paper provides an overview of the commissioning process and its associated challenges before focusing on a critical success factor: building a dedicated commissioning team with the required competencies and personality profiles. The roadmap to achieving an efficient plant start-up is outlined. Drawing on over 15 years of experience with more than 20 concentrator commissioning and start-ups, a general framework is presented to maximize success. This method emphasizes the crucial role of the operation and metallurgy team in supporting these projects. Finally, insights from Soutex’s involvement in multiple start-ups are shared, offering lessons learned that emphasize best practices and challenges encountered in expediting the ramp-up process while maintaining high Health, Safety, and Environment (HSE) standards.

Feb 1, 2025

By F. Ysla, M. Mendoza

This proposal, based on the CIEMAN Cajamarca - Hualgayoc initiative, focuses on “Transforming Abandoned Mine Lands’’ We aim to study and assess the feasibility of an innovative rehabilitation method. Contaminated soils will be moved from the upper to the lower site, encapsulated with geosynthetic barriers, and covered with topsoil. The decontaminated upper area will be used for planting trees and large-stemmed plants for hiking and tourism, while the lower encapsulated area will support livestock and short- stemmed crops. This study will evaluate the economic viability and multi-use potential of this technique, promoting sustainable land recovery in Cajamarca, Peru.

Feb 1, 2025

By George Mandarakas, Johan van Zyl, Karl-Heinz Becker

The world’s climate today has changed compared to 10 or 20 years ago. Many countries face water shortages; water sourcing for mining activities has become harder to secure. ESG’s focus on the industry has made us more aware of the need to preserve and responsibly use the water needed for wet processing in our milling and sorting activities. In a recent greenfield project in South Australia, 10 Gigalitres per annum would be required to process 5Mtpa of magnetite [1]. Published information indicates that the mining industry consumes approximately 12 EJ per year—or 3.5% of total global final energy consumption globally [2] or 3.33 trillion kilowatt hrs. This energy consumption is significant, considering the critical role mining plays in extracting and processing essential minerals for economic development and human progress. The perception of the mining industry is that not only does it consume significant power, but it also consumes a lot of the freshwater in the world. In fact, it consumes approximately 5% [3] of the total freshwater demand. According to the Intergovernmental Panel on Climate Change (IPCC), by 2050, 60% of the world’s population will be living in countries that are classed as water-stressed [3]. As more and more emphasis is placed on renewable energy sources, the amount of water used in mineral processing will increase because more and more raw materials require a water-intensive process. This increases the pressure on the mining industry to try and find water-saving initiatives. As part of this review, recent advancements in magnets have enabled magnetite processing facilities to achieve between 30 to 40% dry gangue material rejection before the wet beneficiation process (grinding and sorting). This reduction in energy consumption allows the reduction of energy consumption. Secondly, there is less material ground in the mills, which requires less water for mineral downstream processing.

Feb 1, 2025

By Aleksandar D. Bugarski, Dylan A. Ritter

The results of laboratory characterization of tailpipe emissions for three “clean” engines that meet U.S. EPA Tier 4 final emissions standards were used to assess the viability and effectiveness of repowering existing engines and powering new mobile equipment with those engines as a control strategy for reducing exposure of underground miners to diesel aerosol and criteria gases. The evaluated engines were representative of those that achieve the emission standards through implementation of various in-cylinder emissions control strategies, use of crankcase filtration, and use of three types of exhaust aftertreatment systems: (1) diesel oxidation catalytic converter (DOC), (2) combination of DOC and the full-flow wall flow monolith diesel particulate filter (DPF), or (3) combination of DOC, diesel exhaust fluid (DEF) based selective catalytic reduction (SCR) system, and ammonia slip catalyst (ASC). The study showed that the highest reductions in concentrations of diesel aerosols in underground workings, in terms of both mass and number, could be achieved if the engines, preferably in all power classes, are fitted with viable DPF systems. The use of U.S. EPA Tier 4 final engines equipped with DOC and DOC/SCR/ASC systems could help operators to considerably reduce mass, but not number concentrations of aerosols. The emissions of two of the evaluated engines, one equipped with DOC and the other equipped with DOC/DPF systems, were characterized by substantial secondary NO2 emissions that would limit the viability of those engines for underground mining applications. It appears that the catalyst formulations used in the exhaust aftertreatment systems of the “clean” engines marketed to the underground mining industry need to be formulated to minimize the potential for generation of secondary NO2 emissions. The results indicate that the engines fitted with viable SCR/ASC systems present a low-NO2 alternative. All three “clean” engines were found to have low CO output. Therefore, due to nuances associated with the use of diesel-powered mobile equipment in underground mines, special attention needs to be paid to the selection and potentially optimization of “clean” engines for underground mining applications.

Feb 1, 2025

By Malte J. M Gurgel

Subsurface spatial planning is becoming increasingly important in view of competing underground applications. This development is influenced by global agreements to reduce greenhouse gas emissions. Therefore, precise knowledge of the underground space is a basic prerequisite for future applications. The three-dimensional registration and reliable georeferencing of underground infrastructures can establish a holistic geodata basis for such tasks. Those tasks are discussed both for the development of energy projects such as deep geothermal energy as well as for storage applications. Research on geothermal energy has been carried out at RWTH Aachen University as part of the SuperC project in a license field in the Aachen area since 2001. Recently, this research has been extended to include monitoring aspects in the overlapping GEObservatorium Aachen field. The documentation and visualization of underground activities using photogrammetric methods like Structure from Motion is discussed based on recent research in sites for the final disposal of radioactive waste. Finally, both applications provide an outlook on supporting underground projects by using high-resolution geodata.

Feb 1, 2025

By Monserrat Rebolledo, John L. Uhrie, Candice Simms

Jetti Resources has developed a catalyst which overcomes the passivation of primary sulfides, enhancing the heap leach recovery of copper from chalcopyrite. It is important to emphasize that heap leaching of copper sulfides, whether with or without the Jetti catalyst, is a biooxidative process. We have demonstrated the efficacy of Jetti’s technology in bioreactors, with a chalcopyrite-dominant porphyry ore. In the presence of Jetti’s technology, optimal bioleaching conditions significantly increase copper extraction by 2.6 times that of the baseline.

Feb 1, 2025

By Key Rosebrook, Jennifer Laggan, Ashley Rivera

Significant quantities of waste rock at abandoned uranium mine (AUM) sites in the western United States require removal from steep slopes exceeding 45 degrees in remote locations. This prevents the use of traditional excavation equipment and poses significant challenges for safe, effective material removal. A pilot study was conducted using a spider excavator to demonstrate the feasibility of removing waste rock and transporting it to areas where conventional equipment could be employed. The spider excavator was evaluated for its effectiveness in excavation, material movement and control, container usage, dust mitigation, and ensuring human health and environmental safety. The study established constructability and engineering parameters for implementing spider excavators in these challenging environments. Key outcomes include the preservation of existing vegetation, improved waste movement control, and enhanced safety measures for workers, nearby residents, and the environment.

Feb 1, 2025

By Franziska Günther, Helmut Mischo

The calculation of costs for an underground mine, as well as the planning of the equipment and materials to be used, is a complex and time-consuming process. The estimation depends on a multitude of parameters, and all mining processes are interconnected. A novel tool has been developed that enables automated calculation of underground mines and allows for the comparison of the effects of changing individual parameters. Previously, changing individual planning parameters often necessitated a complete recalculation of the mine. The newly developed calculation tool provides an innovative planning aid that allows for more efficient and accurate mine planning and cost estimation. The tool enables the user to implement continuously up-to-data costs and prices. This allows for more accurate planning data and results. The underlying concept of the calculation tool, its implementation at a planned quartz porphyry mine in Germany, and the verification of the tool at an existing underground mine will be presented.

Feb 1, 2025

By C. J. Greet

Grinding with an electrochemically inert grinding media (i.e., high chrome white iron) shifts the pulp potentials to more oxidising conditions, increases the dissolved oxygen content and reduces the EDTA extractable iron concentration when compared with milling with electrochemically active grinding media (forged steel). These changes in pulp chemistry produce cleaner particle surfaces, reduce reagent consumption, and increase concentrate grades and recoveries. This paper presents a robust laboratory test program that not only demonstrates the changes in the pulp chemistry, but also provide an indication of the magnitude of the metallurgical improvements that are possible. While laboratory studies are interesting, the proof is in the pudding! So, the paper provides an overview of plant trials conducted at several porphyry copper operations around the world: Newmont’s Cadia and Red Chris Operations, as well as Evolution Mining’s Northparkes Operation. These successful plant trials clearly demonstrate that selection of the right grinding media alloy will yield savings in grinding media consumption and reagent consumption as well as increases in revenue through improved copper and gold recoveries. However, many of the porphyry copper mines on the Eastern Pacific are copper-molybdenum deposits. The paper presents laboratory test results for typical copper-molybdenum operations and extrapolate these numbers to what might be expected should a plant trial occur.

Feb 1, 2025

By Gamal Rashed, Tim Miller, Nicole Evanek

High horizontal stress has been identified as a critical factor affecting roof stability in underground mines, particularly when the immediate roof consists of weak or laminated rock. Numerical models were employed to better understand the influence of caprock thickness, cutting sequences, and the orientation of driving direction relative to maximum horizontal stress on roof stability in underground stone mines. These models were calibrated based on field observations of roof falls from the study mine. The findings of this study enhance our understanding of roof stability under high horizontal stress and contribute to reducing the risk of roof falls in underground stone mines.

Feb 1, 2025

By Hazal Melis Aytac, Lana Alagha, Fardis Nakhaei

Gallium (Ga) and Germanium (Ge) are essential strategic elements that are extensively used as semiconductors in many technological fields. Owing to their essential uses and supply disruption, Ga and Ge are deemed critical by the U.S. They are typically found as substitutions or inclusions in zinc minerals. However, their distributions within zinc minerals are not well understood. To address this, trace element and mineralogy analyses of representative samples obtained from an old high-zinc-grade tailing were performed using various qualitative and quantitative techniques. These techniques included Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Tescan Integrated Mineralogical Analysis (TIMA) with Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Moreover, bench-scale froth flotation tests were conducted to enrich zinc minerals, the major hosts of Ga and Ge, using PAX as a collector, Na2S as a sulfidizer, Pb(NO3)2 as an activator, and MIBC as a frother. Comprehensive characterization analyses of the flotation products showed significant enrichment of Zn, Ga and Ge in the flotation concentrates.

Feb 1, 2025

By D. Scott Scovira, Thomas Gustavsson

Exiting WW2, the potential of nitrates and hydrogen peroxide for application as industrial explosives both became known. The technology stream advanced the development and uptake of nitrate-based explosives to the point that they are the current global standard for blasting. Recently environmental issues are influencing the strategic agenda of extractive industries. The mid-2010s saw renewed interest in hydrogen peroxide explosives to eliminate NOx fume. Carbon reduction initiatives in the 2020s provided additional impetus to investigate hydrogen peroxide-based explosives. Hypex Bio is at the forefront of developing and delivering bulk gas sensitized Hydrogen Peroxide Emulsion (HPE) for blasting. HPE consists of hydrogen peroxide along with smaller amounts of fuel and emulsifier. The consistency of HPE is similar to industry- standard nitrate-based emulsions. It is compatible with existing priming and initiation systems. HPE does not contain nitrates and thereby does not produce post blast nitrous oxide fumes nor discharge of nitrates or ammonia to mine water. Importantly, HPE contributes to reduction in total carbon emissions as compared to nitrate-based explosives.

Feb 1, 2025

By V. Claremboux

The transformation of raw iron ore into high quality steel can take place via several processes. A general consistent theme involves the upgrading of the iron ores via methods such as flotation and magnetic separation, the preparation of an agglomerate such as via pelletization or sintering, the smelting of the agglomerate into a high grade iron product, and the further refining of iron into specific steel alloys. Each of these steps admit potential for optimizations and alternatives, and the process overall is critical to meeting the world’s continuing iron demands.

Feb 1, 2025

By Y. Zhang, C. Zhou, M. Girman

Wireless technologies are increasingly being implemented in underground mines for various purposes such as communications, tracking, remote control, remote sensing, and environmental monitoring. However, the adoption comes with risks as common wireless systems, such as WiFi, Bluetooth, IWT (Innovative Wireless Technologies) wireless system, often operate in the unlicensed ISM (industrial, scientific, and medical) band. The shared nature of the ISM band can lead to interference among devices and consequently cause performance degradation and reliability issues. In this study, we developed two wireless communication evaluation boards as a tool to evaluate the performance and reliability of a wireless system with the presence of electromagnetic interferences (EMI) from other wireless systems in underground environments. We adjusted various parameters including signal power from adjacent frequency channels, noise power within the same channel, the movement of personnel, and communication packet size. Our findings indicate that, while the power of the EMI source plays a key role, the motion of personnel in the tunnel also has a strong impact on performance, and this impact increases as the power of EMI sources increases. In noisy environments, smaller packet sizes are preferable as they enhance the likelihood of successful transmission. High levels of interference or noise can lead to increased packet loss or error rates, potentially causing communication links to fail completely or become ineffective. The evaluation boards utilized in this study are based on a practical wireless transmission system deployed in a remote controller for a heavy mining machinery used in underground coal mines. The results and findings presented in this paper can aid in the design of wireless systems that are resilient to EMI in underground mining environments.

Feb 1, 2025

By Nico Sutmoller, Rich Palladino

Underground voids present a unique geotechnical engineering challenge. This paper will address materials and transportation mediums that are typically used for backfilling underground voids with native material. After reviewing traditional backfill and transportation methods, this paper will explore the advancing technology of foam transportation and the advantages of using this technology for transporting fill materials into underground voids to backfill them with Liquid-Sand. The paper will also review the benefits that Liquid-Sand brings to these applications and highlight specific case studies in which foam transportation has proven effective and provided cost-effective, environmental benefits.

Feb 1, 2025

By Jed Greenwood, Lyall Workman, Michael Haggerty, Russell Sheets

Draglines often work from a position on the active highwall or spoil side bench to remove undisturbed waste material and spoil in the previously mined pit. To protect the dragline crew members and the machine, it is necessary that the highwall remain stable while the dragline is present on the bench. In the past several years, we have been involved in determining the causes for highwall failures that included the dragline. While there have been no injuries and limited dragline damage with these incidents, the potential certainly exists for a more serious outcome. In all cases, the operation had completed a geotechnical study to support the ground control plan and pit designs. However, all these incidents included aspects that would not likely have been identified in studies to determine highwall and spoil designs to support ground control procedures. In general, these events included aspects that were localized and would have been difficult to identify in initial slope stability studies either observationally or during the soil testing and modelling efforts. Although the authors do not have quantitative evidence of this, it does seem there has been an increased number of events in recent years. This may be due to loss of institutional knowledge, mining in more challenging areas, or simply an increase in localized variation. This paper will describe some of the issues we have seen and what the causes of failure were. It becomes clear that avoiding similar incidents in the future requires on-going observation and inspection of active highwalls and spoil benches to try and identify local variability and impact on mining. The information can proactively be used to update stability modeling of any concerning issues to determine likelihood of problems and to develop solutions.

Feb 1, 2025

By Marcos de Paiva Bueno, Leonardo Ribeiro Lara, Rajiv Chandramohan, Thiago de Almeida, Greg Lane

This paper explores the impact of the significant difference between the number of geochemical assays conducted for grade estimation and the number of comminution tests performed for throughput and performance forecasting. Both grade and throughput are key factors in determining the project. We analysed 154 feasibility study reports to assess the impact of sample frequency for comminution test work on project revenue. This disparity in size between assay and comminution data arises because geological and resource-grade risks cannot be managed without extensive geochemical testing, whereas comminution risks are traditionally mitigated through design methods and the use of contingencies. This approach is partly due to the relatively high cost and large sample requirements associated with traditional comminution tests. Our analysis demonstrates that insufficient comminution sampling and testing leads to uncertainties in throughput forecasts, creating significant financial risks. Data from the feasibility studies show that a 1% change in mill throughput can result in up to a 5% variation in Net Present Value (NPV), underscoring the sensitivity of project economics to operational performance. Building on previous work, we reference studies that reveal how low frequency of comminution testing can increase uncertainty in mill throughput forecasts and increase financial risks. We propose an approach that optimises the number of comminution samples tested to enhance forecast accuracy and reduce NPV variance. By adopting this approach, mining projects can improve financial reliability and mitigate risks associated with underperformance in SAG and AG mill-based operations.

Feb 1, 2025

By John J. Simmons

There is considerable interest in the iron and steel industry in the development of technologies that can reduce carbon dioxide emissions, as the iron and steel industry is the third largest producer of carbon emissions in the world, after automobiles and the power generation industry. The E-Iron Iron Nugget Making Process, invented by Dr. Komar Kawatra and Dr. Tim Eisele, provided a major breakthrough in the iron making process as the process uses biomass in the form of hard wood or soft wood as the reductant in the place of coal. Dr. Kawatra recognized that biomass is rich in both carbon monoxide and hydrogen, two important reducing agents. This resulted in initial experiments conducted by Dr. Kawatra and Dr. Eisele in the laboratories of the Chemical Engineering Department of Michigan Technological University (Michigan Tech) that prepared self-reducing pellets with wheat flour as the reductant and limestone/dolomite as the flux. Initial results were encouraging so they extended their work to include hardwood, which is in huge supply in the forests of Michigan and Minnesota, as the reductant. Dr. Kawatra has also applied the E-Iron Technology to other iron bearing minerals to produce pig iron grade iron nuggets. He used the E-Iron Process to convert red mud, a high iron waste product of the aluminum industry, into pig iron nuggets with the rare earth elements reporting to the slag. This work resulted in a patent with Dr. Kawatra and Dr. Michael Archambeau named as the inventors. Dr. Kawatra then extracted the rare earth elements as a separate high value bi-product using oxalic acid, which he produced from carbon dioxide. Dr. Kawatra also conducted a test program that produced pig iron nuggets from New Zealand beach sands. The vanadium in the beach sands was retained in the iron nuggets, recoverable as a valuable bi- product in a separate process. The titanium dioxide in the beach sands reported to the slag. This demonstrates the potential use of the E-Iron Process to convert the large ilmenite reserves in Northern Minnesota into pig iron and titanium dioxide. Another use of the E-Iron Process discovered by Dr. Kawatra was its ability to produce iron nuggets from manganiferous ores. Dr. Kawatra was able to direct the manganese into either the metal or slag by adjusting process temperature. The above discoveries are included in several patents that were assigned to Carbontec Energy. This presentation will only address the use of the E-Iron Process to produce pig iron nuggets from steel mill waste and un-pelletized, mid-grade iron ore. Carbontec Energy Corporation agreed to sponsor additional research directed at improving this new technology that would later be trade named, The E-Iron Process. Carbontec Energy conducted further work that proved that the E-Iron technology could also convert steel mill waste into metallurgically acceptable iron nuggets. Carbontec also collaborated with the Lawrence Livermore National Laboratory and Purdue University Northwest to conduct a Department of Energy (DOE) sponsored program that would use their high performance computer capability to both verify and model the E-Iron Process. Purdue University Northwest reported that the E-Iron Process can produce pig iron nuggets with 85% less carbon emissions than a blast furnace. The E-Iron Process is similar to the ITmK3 process, developed by Kobe Steel, that also produces iron nuggets but uses coal as the reductant.

Feb 1, 2025

By Devin Burns, Saima Ghazal, Michael Owusu-Tweneboah, Kwame Awuah-Offei

Trust in AI systems and the nature and amount of information about the system can influence decision-making. It is, therefore, crucial to understand how AI-powered monitoring systems (e.g., gas monitoring systems) influence miners’ trust and decision-making in emergency evacuation. This work focused on measuring the differences between how participants respond to a simulated underground mine emergency evacuation situation when warnings are represented as coming from a human or AI-based monitoring system. We also manipulated the amount of information participants received about the system, yielding a 2×2 between-participants survey design. The participants received an alert message about rising gas levels in a mine and provided a response on how they would react and reported their perceived safety. We also asked questions to assess their trust in, preference for AI over human-based gas monitoring systems, and whether they are willing to delegate the duties of underground gas monitoring to AI systems. The experiment results show the amount of information had a significant influence on miners’ trust and decision-making. The safety perception of participants based on age, number of children and ethnicity was significantly different from one category to another. This work provides valuable insights as the mining industry deploys AI systems to aid mine safety.

Feb 1, 2025