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By James Withers, Dongbo An, Jinhong Zhang

A micro-scale investigation was carried out by applying an atomic force microscope (AFM) and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy to study in situ the adsorption of three different collectors — oleic acid, octanohydroxamic acid (HA) and salicylhydroxamic acid (SHA) — on bastnaesite in aqueous solutions. The results show that all three collectors adsorb on bastnaesite. The hydroxamic acid collectors — HA and SHA — adsorb on bastnaesite mainly in the form of insoluble metal hydroxamate. Their specific adsorption mechanism indicates that high selectivity will be achieved with a hydroxamic acid collector for the flotation of bastnaesite.

By BEN WANG, HAORAN LI, YALI FENG, JINRONG JU

Acidic wastewater is at present directly neutralized with lime or limestone, which wastes resources such as titanium, scandium and iron and generates a great deal of solid waste. This study proposes a novel approach for the separation and recovery of titanium, scandium and iron from acidic wastewater, and utilization of red gypsum. The proposed process not only recovers valuable metals from acidic wastewater but also treats the red gypsum that has previously been dumped.

Aug 1, 2022

By James A. Finch, Xiang Zhou, Yue Hua Tan

Widely used as collectors for nonsulfides, amines also show some frothing properties. Evaluating frother functions of amines and their combination with conventional frothers addresses whether one reagent delivering both collector and frother functions compromises the efficacy of either. From the findings, whether blending with frother confers any benefit requires knowledge of the residual amine concentration. If it is below about 10 ppm, blending eliminated coalescence, but there appears to be no benefit if the concentration is above 15 ppm.

By Earl Parker

The mining/mineral processing industry constantly faces the challenges of handling tons of material in a variety of processes such as crushing, milling, drying, belt transfer and loadout. These processes result in the production of high volumes of dust. A variety of dust detection and collection equipment is needed to properly manage these emissions to remain compliant with stringent air quality and safety requirements. Dust monitoring and bag leak detection can provide ways to reduce air pollutants, make work environments safer and remain compliant with requirements from the U.S. Environmental Protection Agency (EPA), U.S. Mine Safety and Health Administration (MSHA) and U.S. Occupational Safety and Health Administration (OSHA). There are several approaches to monitoring particulate emissions from dust collection equipment. These can include visual inspections, differential pressure gauges or bag leak detection systems. Bag leak detection and monitoring systems can be optical, light based or electrostatic/triboelectric. Recent developments have advanced the efficiency and reliability of electrostatic/triboelectric style monitors. New technological improvements have been developed that are based upon the principal of unifying dc (impaction) and ac (induction) signals and incorporating other proprietary circuit innovations. This higher signal resolution technology results in a more robust and stable measurement for detecting the presence of particulate in a dust collector emission duct or a flow process pipe.

By William Gleason

"Once the primary fuel source for the United States and the economic backbone for communities from Appalachia to Wyoming, coal has been on a steady decline since the mid 1990s, and is now at the center of political debate in the United States.The political spectrum of the United States is divided on the future of coal and its place in the energy sector. The coal mining industry and the communities that rely on coal have increasingly been pitted against forces that wish to regulate coal to the history books.In 2008, President Obama launched what many have called his war on coal, and during his eight years in office, he pushed through numerous pieces of regulations and legislation and that he said were aimed at reducing carbon emissions, but that others viewed as direct assaults on the domestic coal industry. Obama led the United States delegation to Paris to sign the Paris Accord in 2016, a 196-country agreement pledging that the United States would do its part to reduce carbon emissions. His administration also instituted clean air, power and water regulations that added extra environmental burdens to many industries, but perhaps none more so than the coal industry.In this month’s lead feature, “A study of U.S. coal mine closures since 1994” (page 18), the impact of the war on coal, and other factors, can be seen in text and figures. Author Jacob Brinkman and coauthors Jay Schafler and Catherine Johnson scoured the data of the U.S. Energy Information Administration (EIA) and the U.S. Mine Safety and Health Administration (MSHA) to show how coal production and mines have been impacted since 1994 and how the years 1994 to 2000 and 2008 to 2016 were particularly hard on the industry.For example, in 1994 there were 2,354 coal mines in the United States. Currently, there are 1,035 mines in operation.In 2016, then candidate Donald Trump promised to end the war on coal and to put coal miners back to work. In 2017, President Trump has followed up on those promises. He announced plans to withdraw the United States from the Paris Accord, signed an executive order designed to undo the Clean Power Plan put in place by President Obama, halted the research on the health effects of mountaintop removal coal mining, directed the U.S. Environmental Protection Agency (EPA) to revise the guidelines of waste water from power plants and has touted that more than 1,000 coal miners have returned to work since he was elected."

Jan 9, 2017

By W. F. Visser

The growing availability of information and data analysis capabilities provides new opportunities for improving the performance of operations. By using real-time measurements and artificial intelligence, it is possible to respond faster to changing conditions, while accurate and timely information permits the rapid evaluation of changes and fast business improvement decisions. This paper presents a blueprint for system alignment, organizational design and management practices to leverage these developments in performance-driven operations management in mining and mineral processing.

By Nasser Madani, SULTAN ABULKHAIR

The geological and geostatistical modeling of mineral deposits requires densely sampled drillholes that provide accurate and reliable hard data. Furthermore, quantifying orebody uncertainty through geostatistical simulation can allow mining engineers to assess long-term risk in mine planning. Nevertheless, ore deposits can sometimes lack dense drillhole information, reliable hard data with proper quality assurance/quality control (QA/QC), or sometimes both. This study is based on a coal mine located in the Republic of Kazakhstan, where an iron dataset is based on data from three newly drilled drillholes, and geological information comes from a massive collection of legacy drillhole data with no evidence of proper QA/QC. For this reason, a workflow was introduced to construct a representative training image from legacy data and stochastically model geological domains within these three drillholes using a multiple-point geostatistics technique. Once the geological model was obtained, a two-point geostatistics algorithm was applied to model the iron inside each geological domain. The direct sampling algorithm was chosen for modeling geological domains, and sequential Gaussian simulation for iron grade calculation. Both methods were extensively evaluated using different statistical tools and analyses.

Aug 1, 2022

By S. J. Schatzel, V. Gangrade

A ventilation research study was conducted by the U.S. National Institute for Occupational Safety and Health (NIOSH) and a cooperating longwall trona mine in the Green River basin of Wyoming in the United States. The objective of the study was to evaluate the movement of longwall face air and exchanges between the face and worked-out areas to document the presence or absence of face airflow pathways between these locations. Tracer gas experiments using sulfur hexafluoride (SF6  ) were conducted to describe air movement on the face and in the mined portion of the active panel. Maintaining adequate ventilation air on longwall faces is important for worker safety and for the dilution of gases emitted from the face and caved gob.

By Miguel Reyes, Chenming Zhou, MATTHEW GIRMAN

Electromagnetic energy emitted from electronic devices has been known to interfere with other electronic systems, hindering their ability to function properly. Mines have many electronic devices critical to the health and safety of mine workers that could be negatively affected by electromagnetic interference (EMI). To ensure that devices are electromagnetically compatible, tests must first be conducted to measure emissions and check for immunity. Standards are available across multiple industries that prescribe emission limits and test methods for electronic devices. A literature review was conducted in this study, and an overview of EMI standards in other industries is provided. Also, an example of how a standard can be applied to mining equipment is presented.

Nov 1, 2022

By Gregory M. Rumbaugh, Todd R. Kostecki, Christopher Mark

The paper examines five massive pillar collapses in underground stone mines in the eastern United States from 2015 to 2021. These collapses caused significant airblasts, surface subsidence, and damage to mine infrastructure. The study identifies factors contributing to pillar collapses, such as slender pillars with width-to-height ratios of 0.8 or less, and proposes a framework for evaluating and mitigating collapse risks.

Nov 1, 2023

By MEHMET ALI RECAI ONAL, MAHMUT CAMALAN

The key motivation of this study is to evaluate the potential of well-known hazardous gases—carbon dioxide (CO2), hydrogen (H2) and oxygen (O2)—as grinding aids for mineral liberation in ball milling. The results show that exposure of chromite ore particles to CO2 flow will promote chromite liberation at breakage and, therefore, using CO2 as a grinding aid may partially reduce the carbon footprint of the mining industry. For that purpose, the use of two-phase (gas–solid) or three-phase (gas–solid–water) moving-bed mixers are recommended for the pretreatment of mill feed before ball milling.

By FHATUWANI SENGANI

The understanding of yielding pillar behavior has been well documented in terms of pillar strength using numerical simulations and empirical formulas, but the understanding of how fracture propagates in a matured yielding pillar is not well established. A new empirical summation chart of fracture distribution along the matured yielding pillar is presented in this paper. The chart was developed using ground penetrating radar (GPR) supported by borescope observations, focusing on monitoring the distribution of extension fracture.

By S. S. SHINDE, P. C. JIKAR, N. B. DHOKEY

Mill scale is an oxide waste product of steel mills, containing around 70 percent iron and other allied impurities. In the present context, a dynamic prototype counter-current reactor (CCR) was used for the experimentation and simulation of a particle bed using the discrete element method (DEM). Mill scale was pulverized to ASTM mesh range 140 (106 μm)/+ 270 (53 μm) and oxidized in a CCR to make a single oxide Fe2O3 phase by maintaining the required thermodynamic conditions, such as pure oxygen at 1,100 °C. This oxidized powder was then subjected to a reduction reaction in the CCR, with gas mixture (H2:N2) ratio of 1:4 at 875±5 °C for filling degree, fd , and reactor revolution, ω, ranging from 5.38 to 16.14 percent and 2 to 5 rpm, respectively. A creeping fluid flow condition (Re < 1) and natural heat convection (Gr/Re2 >> 1) were maintained during the solid–gas reaction, and the particle-bed behavior was quantified by Froude number for the optimum operating window. The simulation was validated with the experimental results of reactor reaction product by X-ray diffraction (XRD) and scanning electron microscope (SEM) images.

By D. PATIL, B. K. Parekh

Water is the mainstay for the beneficiation of fine-size coal and minerals, but it is also the least desirable constituent of the final product. The basic concept of the novel process described in this paper is based on the differential surface heat absorption capacity of the individual particles. When a differentially heated solid mixture is placed on a moving belt that has been coated with low-temperature melting resin, the hotter component of the mixture will stick to the belt while the relatively cooler component will stay free on the belt and fall off at the end of the belt run. Experiments were conducted with pyrite, coal and quartz particles of 6 × 18 mesh size. The goal of the test program was to find the optimum conditions at which there exists a required temperature difference between minerals and coal particles by controlling the operating and system variables. Preliminary test results show that there is a potential for separating mineral matter from coal using the thermo-adhesive separation technique.

By Turan Uysal, Thierno Saidou Barry, MURAT ERDEMOGLU, Mustafa Birinci

Nonbauxite ores such as aluminum silicate clays and coal fly ashes have been widely considered as potential resources of alumina (Al2O3). The interest focused on these ores is due to their high alumina content. Over the years, in countries where there are little or no bauxite reserves or where the recovery of existing bauxite ores to produce alumina with the Bayer process is not economical, alternative processes have been explored. Among these processes, acid leaching is seen as the most attractive process. In the acid leaching process, heat treatment for thermal activation to destruct the refractory structure of the minerals in the ores is generally recommended as a pretreatment method. Recently, the applicability of high energy ball mills, which are useful for mechanical activation as a pretreatment method before leaching, has attracted much attention. This is a short summary of our previous review [1], giving the details of alumina manufacturing from thermally and mechanically activated clays and coal fly ashes by acid leaching.

By H. M. Park

Risk is a major factor in all mining activities, arising from many internal and external variables. The authors? research has resulted in a systematic method for the quantification of risk in mining projects (Park, 2012), and this research is being presented in a series of papers. The first paper (Park and Nelson, 2013a) identified the variables associated with risk in mining projects, and their effects and was published in the October issue of Mining Engineering magazine. The second (Park and Nelson, 2013b) discussed methods of assessing the overall risk associated with those variables (published at www.me.smenet.org), and presented a statistical model based on a survey of 31 experts. This paper will present an evaluation of the statistical model, using data from previous mining investment decisions in which the authors have been involved.

Oct 1, 2013

By Arman Hazrathosseini, Ali Moradi Afrapoli

Fleet management systems (FMSs), as a pivotal part of any surface mining operation, need to evolve from conventional to intelligent systems because of both Mining 4.0 requirements and some shortcomings inherent in conventional methods. However, this novel transformation needs to be investigated technically and strategically. To this end, previously published research works on intelligent FMSs are explored to track the latest status of these third-generation frameworks within the surface mining context. Their underlying models are then compared in terms of five categories of allocation and dispatching features to pinpoint the technical gaps ignored. Having drawn the future lines of research, the present work then leverages the popular SWOT analysis method to outline the strengths, weaknesses, opportunities, and threats associated with the advent of these intelligent FMSs in mines of future. By and large, the analysis indicates that advantages outweigh disadvantages. Solutions are offered to address the existing weaknesses and threats.

Apr 1, 2024

By GRANT COLLIGAN, BROCK O’KELLEY, Corby Anderson

With the world’s ever-growing push to expand technological capabilities, the need for specialized materials including rare earth elements has exploded. One source of rare earths found in the United States is bastnaesite, a rare-earth-bearing fluorocarbonate, mined at the Mountain Pass Mine in California. To increase production, it has been essential to optimize existing processes and create new ones to capture current reserves. This paper presents the results of a research program conducted to expand the understanding of the bastnaesite leaching system. With the help of prior knowledge and thermodynamic calculations, a novel single-stage hydrochloric acid leach system was created to optimize the extraction of rare earths from bastnaesite. Historically, this extraction has entailed the use of a two-stage leach system involving a high-temperature hydrochloric acid leach followed by a caustic crack. We ran a series of single-stage leach experiments by reacting locked-cycle flotation concentrate with hydrochloric acid to test common leaching parameters. The results of these single-stage tests showed significantly higher rare-earth recoveries than the reported recoveries of the historic two-stage caustic crack processes, all while decreasing the number and amount of reagents needed.

Feb 1, 2023

By Biswajit Samanta, Pranjal Pathak

A multimine mineral value chain (MVC) consists of multiple mines in the upstream supplying raw materials to multiple destinations in the downstream. The short-term mine production scheduling problem of a multimine MVC aims to determine the optimal extraction sequence and destination allocation of blocks from all the mines collaboratively to meet the quality and quantity requirements of all the processing plants in each period, subject to all relevant technical and operational constraints of the mining system. It is carried out at shorter scales of days/weeks/months under the purview of long-term production scheduling. An optimal short-term production schedule for MVC involving multiple mines that share the same infrastructure (processing units, stockpiles and waste dumps) requires coordination across the network of mines. Optimizing the short-term production schedules independently at each mine fails to capture the benefit of collaboratively generating schedules for all the mines, resulting in suboptimal schedules. Additionally, in short-term production scheduling, the operations are modeled in greater detail with additional decision variables and constraints to model the more complex multimine MVC situations. This makes the large-scale instances of the problem computationally intractable for standard mixed-integer programming (MIP) solvers. This work presents a customized genetic algorithm (GA)-based heuristic approach to obtain near-optimal solutions to the industrial-scale instances of the short-term production scheduling problem of multimine MVC within a reasonable computation time.

Oct 1, 2022

By MUSTAFA ERKAYAOGLU, ENVER YILMAZ

Coal mining is likely to sustain its critical role as energy requirements are increasing. While surface mining exploits coal seams near the surface, underground mining techniques are crucial for extracting deep coal reserves. Longwall mining is one of the most common methods used in underground coal mining operations. This paper introduces a data-based framework — including data collection, data analysis and the interpretation of operational data — for understanding the system efficiency of a longwall shearer. Operational performance is evaluated by the time between arrivals (TBA) and duration of the shearer stoppages, shearer drums’ reversal time, cutting speed and flit speed on daily production in a longwall top coal caving (LTCC) mine. A discrete event simulation model is developed to represent the bidirectional cutting sequence of a longwall shearer.