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By K. T. Stafford, N. A. Iverson, V. T. McLemore

Southwestern New Mexico is part of a large belt of Late Cretaceous to Eocene copper porphyry deposits found in Arizona, New Mexico, and Mexico. These deposits are the result of arc magmatism that occurred during the Laramide orogeny. Recently, attention has been brought to other commodities that can be extracted as by- and co-products, many of which are critical minerals. A new compilation of the geochronology of these deposits shows two main pulses of magmatism that produced mineralized deposits and, along with new dates by the author, shines new light on the geologic history of these deposits and the role it plays in critical mineral abundance.

Feb 1, 2024

By Erwan Yap, Brian Mangogna, Craig Romrell, Jeff McKay, Weishi Mang, Andrea Deml, Adam Steimel, Justin Dix

The Doe Run Company (Doe Run), a global supplier of lead (Pb), copper (Cu) and zinc (Zn) concentrates, and lead metal alloys, installed an enterprise expert control system— termed as Digital One—on the company’s Pb, Cu and Zn circuits at its Buick Mill in December 2022. Digital One was developed with Metso and deploys Metso’s product, VisioFroth™. This automated system is now running and optimizing the flotation processes for all three circuits (Pb, Zn and Cu), all plant air and methyl isobutyl carbinol (MIBC). In addition, Digital One also controls a second, newly built, modern flotation reagent system. Digital One also paves the way for automation and expert control of the entire mill, integrating grinding, thickening and filtration. Digital One is digitally immersed in a universal distributed control system (DCS); therefore, today’s mineral processing plants may be upgraded to it or designed around it. This presentation will explore the plant design and operation of this technology at the Doe Run Buick Mill.

Feb 1, 2024

By Bruce D. Hebb, Shahin Shadlou

Fiber Reinforced Polymer (FRP) is an excellent material choice for a broad spectrum of corrosive fluids and, in many cases, offers the best value per dollar. FRP Flanges present the greatest design challenge of all standard piping components. The theory underlying the design of flanges is very complex. In addition, due to the nature of FRP material, proper fabrication of the flanges is as critical as the design. In this review, the challenges of making FRP flanges along with the design techniques and best practices of fabrication that will lead to a high-quality flange will be discussed.

Feb 1, 2024

By Karoly (Charles) Kocsis, Jeff Johnson, Felipe Calizaya, Tulio Dias, Natanna Nunes

Two pressure balancing chambers were constructed at a Colorado coal mine to reduce the risk of spontaneous combustion. Each chamber was established by installing a Kennedy stopping at about 10 ft (3 m) in front of an isolation seal, and equipped with two safety doors, a nitrogen injection system, and a set of environmental monitors. Several pressure balancing tests for different ventilation conditions were conducted in these chambers. During each test, pressurized nitrogen was injected into the chamber and the pressure differentials across the stoppings and seals monitored. This study presents a summary of the results achieved, lessons learned, and the basic requirements to operate a pressure chamber effectively.

Feb 1, 2024

By J. H. van Laar, C. S. L. Schutte, M. Le Roux

Highly energy-intensive systems prone to wastage are significant causes of unnecessary energy losses in industry. Deep-level mine chilled water reticulation systems fall within this category of inefficient energy-intensive systems. Some techniques (measured baselining, zero-waste baselining, leak detection, and control valves) exist to identify and reduce wastage in mine water reticulation systems. However, these techniques have not been compared, which begs the question of which is more accurate. A need, therefore, exists to compare these methods to determine the effectiveness of each. This study investigates each method and applies them to a case study mine, providing a platform for comparison. These methods identified wastage ranging between 2 and 20 l/s (3–30% of water consumption). The comparative effectiveness of the methods from best to worst was found to be zero-waste baselining, leak detection, control valves, then measure baselining. This study proposes an application procedure combining the considered methods to identify and eliminate wastage on deep-level mine systems more efficiently.

Jan 31, 2024

By Rongjie Kong, Shiwei Wang, Dongjiao Gui

Metal cations have significant effects on the flotation of coal and minerals. In this study, the effects of monovalent cations ( Na+ and K+) on the flotation of low-rank coal (LRC) were investigated using flotation and particle–bubble attachment experiments and through X-ray photoelectron spectroscopy (XPS) and molecular dynamics simulations. Oleic acid (OA), methyl linoleate (ML), hexadecyltrimethylammonium chloride (CTAC), ricinoleic acid (RA), and kerosene were used as flotation collectors. The flotation experiments revealed that the flotation yields of LRC improved when OA, ML, RA, CTAC, and kerosene were used in pure deionized water. However, flotation was suppressed for these collectors in the presence of K+ and Na+ ions. In contrast, when using CTAC, the flotation yield increased in the presence of these ions. Specifically, the flotation yield increased from 41.24 to 87.03% when 2.0 kg/t CTAC was used in 10 mmol/L NaCl solution. Particle–bubble adhesion experiments and XPS revealed that the hydrophilic groups of CTAC were adsorbed on the LRC surfaces by electrostatic forces, whereas the oxygen-containing functional groups of OA, ML, and RA formed hydrogen bonds with the LRC surface in pure water. Finally, the simulating result revealed that the hydrophobic ends of the OA, ML, and RA collectors hinder the flotation of LRC by adsorbing monovalent cations, whereas the adsorption of monovalent cations on the hydrophobic end of the cationic surfactant (CTAC) promotes flotation via strong electrostatic interactions.

Jan 31, 2024

By V. M. S. R. Murthy, Biswaraj Dash, Somnath Chattopadhyaya

Tunnel boring machine (TBM) has been in focus for the last few decades and is currently the most preferred excavation method for metro, hydro and irrigation tunnels. Tunnelling in hard and abrasive rock conditions, in particular, is adversely affected by a very low advance rate coupled with increased TBM disc cutter failures and cutterhead jamming, seeking an in-depth understanding of the design and operational processes of the boring components of the TBM. The cutterhead and disc cutter are the critical boring components of the machine, influencing the boring process significantly. These components directly interact with the rock and hugely influence the machine’s efficiency. This paper encapsulates a review of prior studies related to disc cutter design and the cutterhead design for hard rock TBM tunnelling. A design methodology for designing and selecting a disc cutter and a cutterhead is suggested. The design methodology has been applied for a hard rock tunnelling case, and suitable design specifications for the boring components were arrived at. The disc cutter and cutterhead specifications designed based on the suggested methodology closely match with that of deployed TBM specifications. It may be observed that except for the case of high-strength and high-abrasive rock (greyish quartzite), for the rest of the rocks, the suggested design can meet the desired advance rates.

Jan 31, 2024

By NARAYAN K. BHAGAT, ARVIND K. MISHRA, C. Sawmliana, Rakesh Kumar Singh, Panchanan Hembram

Mining operations in close proximity to dwellings and sensitive structures present challenges in terms of mitigating the undesirable effects of blasting while maintaining productivity and ensuring the safety of surrounding communities. This paper explores the application of advanced blasting techniques, including the use of electronic detonators and the splitting of total explosive charges, to address these challenges. A series of experimental blasts were conducted, comparing blasts conducted with and without splitting of holes, to assess the impact on ground vibrations. The results demonstrated significant reductions in vibration magnitudes when implementing controlled blasting practices with splitting techniques. The findings highlight the importance of total explosive charge in determining ground vibration magnitudes within the danger zone of mine workings. The use of electronic detonators provided precise control over blast sequencing, contributing to safer and more efficient mining practices. These advanced blasting methods offer a practical and innovative solution for conducting safe mining operations near dwellings and sensitive structures, ensuring compliance with safety regulations while sustaining productivity.

Jan 23, 2024

By Liangguo Kang

Coal, as one of the vital sources of energy in China, has raised widespread concerns regarding its safety issues amidst the country’s economic growth driven by coal. To address this concern, this study employed the Kuznets curve, multiple linear regression, and data envelopment analysis models to investigate the impact of Chinese coal economic development on coal mine deaths from 1992 to 2021. The findings revealed a clear correlation between the Chinese coal economy and coal mine deaths. Specifically, per capita coal output, the death rate per million coal tons, and the death rate per hundred thousand persons exhibited positive, negative, and negative correlations, respectively, with the growth of coal income over the past three decades. Moreover, when the coal workers and coal output factors remained unchanged, the income of coal demonstrated a negative correlation with future changes in coal mine deaths. Notably, with three decades of coal economy development, substantial improvements in coal mine safety have been observed in China. Consequently, this research provides valuable insights for formulating safety measures and policies in coal mines across different economic levels, as well as a useful framework for assessing safety development in the coal industry.

Jan 20, 2024

By SANJIT KUMAR PAL, Sarvesh Kumar, Arindam Guha

The integrated geophysical study around pipe 1 and pipe 2 in Wjarakarur Kimberlite Field (WKF) assisted in comprehending the response of pipes. In the present study, we have attempted a combined analysis of very low-frequency electromagnetic (VLF-EM), electrical resistivity tomography (ERT), and magnetic methods to analyze the response from pipe 1 and pipe 2. A comparative analysis along all the profiles revealed the extension, depth, and geometry of the pipes. The results of VLF data and ERT data have been compared for two profiles of pipe 1 and pipe 2. Fraser-filtered grid map generated from all profiles of pipe 1 proficiently demarcated the trend of kimberlite pipe extension with high Fraser filter value associated with kimberlite. The ground-based magnetic data around pipe 1, pipe 2, and pipe 6 have been processed to analyze the magnetic behavior and subsurface structure based on the susceptibility contrasts. Analytical signal (AS) map revealed the extension of pipes, which was validated with the Fraser-filtered grid map. Analytical signal anomaly pattern reveals that pipe 1, pipe 2, and pipe 6 are trending in SW-NE, NE-SW, and NE-SW, respectively. Based on this study, the results indicate the conducting nature of pipe 1, whereas pipe 2 is resistive in nature. Further, the Euler deconvolution technique has been applied to calculate the possible depth of pipes from magnetic data. The comparisons of calculated depth ranges obtained from all geophysical techniques correlate well and validate the result (Table 1). The geological borehole data at pipe 1 and pipe 2 reported by the Geological Survey of India are well corroborated with our combined geophysical study.

Jan 17, 2024

By Lana Alagha, Ashraf Alsafasfeh, Amal Al‑Hanaktah

As freshwater resources are becoming scarce, the use of seawater as replacement of fresh water is appealing in order to make mineral processing operations more sustainable. Since froth stability plays a critical role in determining the performance of flotation operations, there is an urgent need to study the effect of frother dosage and seawater on froth stability. In this study, flotation tests in seawater were conducted to examine the effect of frother’s dosage (MIBC) on the froth stability and flotation performance of low-grade phosphate ore. The stability of the froth layer was assessed by measuring the froth growth velocity and the froth maximum height at equilibrium. Results indicated that the best flotation performance was obtained at 75 g/ton of MIBC where ~ 90% of phosphate minerals were recovered. At this recovery value, the concentrate grade was determined to be ~ 70%. Results from froth stability experiments showed that the stability of the froth layer increased by increasing MIBC dosage. At MIBC dosage of 75g/ton, the calculated values of dynamic froth stability and the froth height were ~ 0.4 cm/sec and 16 cm, respectively.

Jan 17, 2024

By Han Zhao, FENGLIANG WU, Tong Wang

Calibrating an entire mine ventilation network model from survey data has long been considered a challenging and sometimes impractical task. This paper proposes a solution to this issue with the development of a quadratic programming optimization model. The optimization model takes the minimum modification of input resistances as the objective function, uses the mesh pressure equations as equality constraints, and incorporates the lower limits of airway resistances as inequality constraints. A two-step method is developed to solve the model, which includes finding an initial feasible solution and iteratively solving the final solution using the active set method. A computer program has been developed to implement the optimization model. To demonstrate its practicality, a study case using a 35-branch ventilation network is presented, which indicates that the solution process converges after only 57 iterations, a significant improvement over the times of trial and error, which could reach 3.4 × 1010 for the worst-case scenario. Additionally, it is shown that considering only the equality constraints results in negative resistances, while incorporating the lower limits of resistance ensures that the corrected resistances are within a reasonable range. Using the resistance corrected by the optimal model to simulate the ventilation system via traditional methods generates quantities and fan pressures that perfectly match the measured values, eliminating the tedious process of manually adjusting airway resistances repeatedly.

Jan 13, 2024

By NILAMADHABA SAHU, Gajanan U. Kapure, Pankaj Kumar, Sunil Kumar Tripathy

Chromite ore processing tailings and low-grade manganese ores are typically considered waste due to their limited or negligible utility, leading to environmental and storage concerns. Researchers globally have explored various methods to utilize or upgrade these wastes, particularly because dumping chromite ore has been linked to severe health issues through Cr(VI) leaching. Individually, these ores lack economic value, and there has not been research on simultaneously reducing both low-grade ores. In this study, the focus lies on smelting these ores together, aiming to create a precursor alloy for 200 series stainless steel scrap. Initial research indicated the potential for scrap formation, validated through lab experiments with varying coke rate, basicity, and holding time. The investigation discovered that smelting this combination could yield a metal product comprising 59% Fe, 24.93% Cr, 7.56% Mn, 0.62% Ni, and 0.93% Si. The optimum basicity was found to be 0.6 with 80% recovery. Notably, this process eliminates intermediate steps in 200 series stainless steel production, potentially reducing overall CO2 emissions. This proposed method represents a cleaner, sustainable approach to repurpose these two waste ores, projecting a net profit of USD 330 per ton.

Jan 10, 2024

By Ricardo Oliveira Gallart de Menezes, Claudio Gerheim Porto, Reiner Neumann

This study presents the results of the mineralogical characterization of Ti-Zr ore from the Jiboia deposit, located in the municipality of Brejo Grande, Sergipe State, Brazil. The goal is to identify the main Ti, Zr, and REE carrier phases in the different particle size fractions in order to subsidize the development of a cost-effective processing route for the production of heavy minerals concentrate. The mineral resources are estimated at 31.5Mt @ 3.5% of total heavy minerals (THM) for the Jiboia Ti-Zr deposit, of which 5 Mt @ 3.39% THM were classified as measured and indicated. The mineralogy of the heavy mineral concentrate recalculated to 100% is represented by 22% pseudorutile, 20% ilmenite, 15% zircon, 5% rutile, 2% monazite, and 36% gangue. The ore minerals are preferably concentrated in the 150 × 53-μm granulometric fractions, which represents 80% of the THM and only 27% of the ROM (Run-of-Mine) ore. Therefore, by cutting the ore to 150 μm, it is possible to discard 73% of the ROM mass and recover 80% of the THM, including 100% of the zircon and monazite which are the most valuable minerals present in the heavy mineral concentrate. The global recovery of THM starts to decline rapidly in the fractions finer than 106 μm and the mass disposal (tailing) does not follow in the same proportion. Higher zircon contents in the concentrates of the fractions finer than 150 μm imply a significantly lower recovery of heavy minerals like ilmenite, pseudorutile, and rutile that make the fractions coarser than 150 μm.

Jan 9, 2024

By S. Afrouz, C. Keles, W. R. Reed, E. Sarver, T. Akinseye, A. Greth, L. Pan, F. Animah

Among underground coal miners, roof bolter operators are generally considered to have some of the highest risks for hazardous respirable dust exposure. This is because bolting requires drilling into roof strata that can often be a source of silica and silicate dust, which are associated with occupational lung diseases. However, little is known about the variability of dust characteristics (e.g., mineralogy constituents, particle size) in the vicinity of the bolter—or when specific dust controls are applied. As part of a prior NIOSH study, respirable dust samples were collected during several different events in standardized locations around an active roof bolter, and personal samples were also collected from the operator during the cleanout of the bolter’s dust collection system when it was equipped with a novel wet dust box versus a traditional dry box. Those samples were made available for follow-up analysis by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDX), as well as direct-on-filter Fourier transform infrared spectroscopy (FTIR). Results showed variability in dust constituents and particle sizes at locations around the roof bolter, and indicated some event-to-event differences in dust sources. Additionally, compared to the dry dust box, the wet dust box appeared to reduce (by 41–82%) the relative silica and silicate content in the respirable dust to which the operator was exposed during cleanout. Furthermore, an inter-laboratory comparison demonstrated the reproducibility of a standardized direct-on-filter FTIR method for estimating quartz mass (i.e., the predominant form of crystalline silica) in respirable coal mine dust samples. However, for constituent analysis by SEM–EDX, differences observed between results from two independent labs indicate that standardization of the analytical protocol is necessary to enable comparability of results.

Jan 5, 2024

By Jian Zhou, Shuai Huang, Wenqin Xi, Kun Du

The deep oceans harbor a wide variety of mineral resources that are characterized by their abundance and high quality. Nations worldwide are actively pursuing the exploration and extraction of these resources. This paper provides a concise overview of the mineral resources found in the deep sea, highlighting the challenges associated with their exploitation. Furthermore, it presents a comprehensive analysis of the historical development of deep-sea mining technology and equipment, offering valuable insights into this field. By examining the current issues and obstacles faced in deep-sea mineral extraction, this study concludes that the future of deep-sea mining lies in the direction of automation, intelligence, and standardization. Additionally, it identifies the key technological advancements that need to be achieved in order to overcome the challenges associated with deep-sea mining.

Jan 5, 2024

By D. S. Scovira, T. Gustavsson

Exiting WW2 (mid-1940s), the potential of nitrates (ammonium nitrate, calcium nitrate, sodium nitrate) and hydrogen peroxide for application as a commercial explosives for mining, construction, and other industrial purposes 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. Today, environmental issues are shaping the strategic agenda across various industries. Most global mineral resource, construction houses, and explosive manufacturers have publicly announced ESG carbon reduction commitments in support of COP26 Net Zero 2050. The mid-2010s saw a renewed interest in hydrogen peroxide explosives to eliminate NOx fume. Carbon reduction initiatives in the early 2020s provided additional impetus to investigate hydrogen peroxide based explosives for industrial use. Hypex Bio has recently pioneered the formulation, manufacture, and end-use delivery of a Hydrogen Peroxide Emulsion (HPE) on an industrial scale. The HPE is composed primarily of hydrogen peroxide (H2O2) plus a lesser amount of fuel and emulsifier phase. The base HPE is produced in a low energy intensity modular plant using industry proven mixing techniques. The base HPE is a white, highly viscous emulsion that is similar in consistency to base nitrate emulsions. To enable end blasting use, a mobile charging unit gases the base HPE to a detonable density. The HPE is compatible with current priming and initiation systems. Hydrogen peroxide explosives offer a significant reduction in total carbon emission as compared to nitrate based explosives. The production of ammonium nitrate (AN) emulsion is energy-intensive and not carbon neutral. Based on the EU Average and for the oxidizer phase only, 1 kg [2.2 lb] of AN emulsion emits 2.3 kg [5.1 lb] of CO2 as compared to the production of hydrogen peroxide emulsion that results in 0.23 kg [0.5 lb] of CO2. This is a difference of 90%. HPE contains no nitrates and does not generate post blast nitrous oxides (NOx). HPE generates no aqueous nitrate or ammonia pollution and is a solution to meeting increasingly regulated mine site water discharge limits. Hypex Bio recently conducted a successful underground HPE evaluation with a major mining company in Sweden. HPE blast designs were the same as those done with nitrate based emulsions. Rock breakage, advance, muck displacement, and excavator performance were equivalent. Ventilation and re-entry times were reduced. The mining company has expressed further interest in assessing HPE and is demonstrating industrial leadership by exploring this transformative explosive technology

Jan 1, 2024

By E. Líder, J. Pavez, J. Rivera

The application of new technologies, methodologies, and the use of new products in mining operations is a practice that is becoming more common in the industry every day, added to the new challenges and restrictions found in the operation. In the city of Tierra Amarilla, the interaction between mining operations and the community presents a constant challenge given the proximity to the community and the limitations that this presents. Explosive charge mass, in conventional blasting using traditional explosives (ANFOs, packaged explosives for example) limits the explosive charge lengths (they are reduced), impacting the explosive charge productivity. To improve the productivity of explosive charge and fragmentation, the use of low-density explosives was proposed, allowing the increase of the explosive charge length, trying to maintain the vibration levels within the established limits (2mm/s), preserving the fragmentation of the rock in the required sizes. The present study shows the results obtained from the application of low-density bulk emulsion for production blasting charges using upward and downward fan drillings. During this process, 18 blasting events were carried out, of which 8 were Up-hole loading (average density of 0.75 gr/cc) and 10 with Down-Hole loading (average density of 0.95 gr/cc). In summary, a total of 110,760 tons of ore have been broken, using low density emulsion, meeting the proposed objectives such as: 33% reduction of vibrations, 12% overbreak (within the theoretical design), P80 of 11in and 4.6% in fines.

Jan 1, 2024

By J. Sanchidrián, A. Fernández, P. Segarra

The combination of chemical analysis techniques as XRF and measurement-while-drilling (MWD) technology in underground mining is a novel approach to gather comprehensive on-line information about physical and mineralogical data. In this work their integration is investigated aiming to delineate the ore/waste boundary. The input data analyzed come from a narrow vein underground mine, where the ore correspond to fluorite, and gathered in two production levels with complex mineralogical characteristics. Two approaches are followed to build a generalizable classification methodology and a site-specific model: a k-means clustering heuristic algorithm to define rock classes based on their physicochemical features, and a machine learning (ML) ensemble model trained with drilling parameters. For an imbalance class problem, a good recognition is obtained for the ore when is related to a high content of silica and for the waste. To predict the ore with low silica content it is necessary to integrate an analysis-while-drilling method to recognize the fluorite content when this mineral is embedded in different rocks. MWD can be employing for the lithologies recognition when representing different structural and mechanical properties between them.

Jan 1, 2024

By P. Lozada

The objective currently demanded from controlled blasting techniques is to minimize damage to the remaining rock mass while protecting the integrity of mine walls and ensuring the quality of the fragmented material for easier extraction. Finding this balance represents one of the three main challenges faced by large open-pit mines. They must achieve mine stability by complying with slope designs while also maintaining good results in terms of fragmentation and equipment productivity. The main constraints are related to unfavorable geological conditions, water presence, limited drilling diameters and available explosive products, as well as managing drilling times and blast scheduling, among others. For slope control, in addition to presplitting, blasting designs generally include buffered rows, drilled with smaller diameters, and loaded with fewer kilograms of explosives than production holes. The objective is to reduce the powder factor (kg/t) to minimize the energetic influence on the walls and attenuate damage. However, this often requires using very short charge lengths compared to the bench height (one-third or less) and reducing the pattern geometry, which increases the number of holes per ton and drilling costs. This traditional technique of reducing powder factor in the buffered rows has the main limitation of not being able to distribute the explosive energy throughout the entire column, leading to fragmentation issues mainly in the steaming area. Measurements conducted by Orica in their operations indicate at least a 30% increase in P80 particle size in the buffer zone associated with this condition. To improve energy distribution, techniques such as decking, or vertically decoupled charges can be employed. However, these techniques cannot be applied under wet conditions, and strict control over implementation quality is required to avoid deviations, which increases loading operational times and resource required. In this sense, the use of less energetic and lower-density explosives is a better alternative. On one hand, they allow for complete charge columns in the buffered rows, ensuring homogeneous fragmentation, and on the other hand, they reduce the energetic influence on the slopes, significantly decreasing vibration levels. With less energy per kilogram of explosive (MJ/kg) and less charge per linear meter (kg/m), it becomes possible to handle higher specific charges and longer explosive columns, providing flexibility in drilling and loading design options without compromising slope stability.

Jan 1, 2024