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By Pieter-Jan Kleiterp

Highwall mining is a mining method to extract coal from a final boundary in opencut mining, trench mining or contour mining. This boundary may have been reached because of economic constraints (economic strip limit) or geographic constraints, such as spoil heaps and rivers. Coal is mined from visible, horizontal, or near-horizontal coal seams by making rectangular, parallel, unsupported drives with an unmanned cutterhead and coal transport system. This is controlled from a mining unit, or launch frame, positioned outside the drive, in front of the highwall. Removal of overburden is not required or is limited to small quantities only.

Jan 1, 2010

By T. Yue, Z. Gao, X. Tong, R. Liu

"Lead ions (lead nitrate) were introduced to modify the surface properties of scheelite, effectively and selectively improving the flotability of scheelite, with benzohydroxamic acid (BHA) serving as the collector. A series of experiments about the mode of addition and the ratio of lead ion to BHA were conducted and indicated Pb-BHA complexes were the active species responsible for the flotation. And two adsorption models of BHA on the surface of scheelite were established. For both the two adding methods, some kind of complexes formed by lead ions and BHA played a key role in the flotation process. Zeta potential, FTIR, and XPS studies indicated that the adsorption amount and intensity of BHA on the surface of scheetlie were larger by adding the reagents as a mixture. The mixed addition is conducive to form Pb-BHA complexes and improve the adsorption efficiency of BHA on the surface of scheelite, as well as the recovery of scheelite. INTRODUCTION Scheelite, as an important tungsten-bearing mineral, is nowadays utilized mainly by flotation (YIN and WANG, 2014; Sun et al., 2011; Gao et al., 2015; Gao et al., 2015). Flotation separation of scheelite from calcium minerals creates difficulties because of the existence of the same cation in the minerals and similar physico-chemical characteristics such as solubility, hardness, specific gravity, point of zero charge (PZC), etc. (Arnold and Warren, 1974; Deng et al., 2016; Deng et al., 2015; Ozcan and Bulutcu, 1993a; Yongxin and Changgen, 1983). The conventional collectors used in the flotation of scheelite ores are generally fatty acids or fatty acid derivatives (Bo et al., 2015; Oliveira and Sampaio, 1988; Shi et al., 2014; Sivamohan, 1988; Yongxin and Changgen, 1983). It is difficult to separate scheelite, especially from calcite, with these reagents because the adsorption mechanism of these collectors occurs through chemisorption of the oleate ion onto the mineral surface (Atademir et al., 1979; Changgen and Yongxin, 1983; Hiçyìlmaz et al., 1993; Hu et al., 2011). Therefore, it is almost impossible to separate them by fatty acid flotation without using any selective depressant. Although oleoyl sarcosine was used as a selective collector in the flotation of fluorite and siliceous scheelite ores (Ozcan and Bulutcu, 1993b; Ozcan et al., 1994), this selectivity is inadequate for a low-grade calcitic scheelite ore. Unfortunately, reagents such as organic colloids (dextrine, starch), quebracho, sodium phosphates, sodium silicate solutions containing polyvalent cations (hydrosols), etc. (Bo et al., 2015; Schubert et al., 1990; Shi et al., 2014; Yongxin and Changgen, 1983), used for calcite depression also depress scheelite to a large extent. Cationic collectors, such as amine and quarternary ammonium (Yang et al., 2015) and collector mixture (Gao et al., 2015) have been used to improve the scheelite flotation. However they have not been applied in industry due to the poor separation from silicate minerals."

Jan 1, 2017

By K. N. Han

Coal is becoming increasingly important as a major energy source in the face of the world's depleting energy mainly based on oil reserves. Coal is by far the most abundant fossil fuel both in the United States and abroad. Currently, because of increased mine mechanization, the fineness of preparation plant feed is increasing. Further, in the future as the grade of coal diminishes and the sulfur content increases, upgrading preparation of coal is very important. Because the density of coal is less than that of rock materials that occur as impurities, coal is separated from such waste largely by gravity-controlled processes for particle size between 5 inches and 28 mesh. If the size of coal particles is below 28 mesh, froth flotation is a good method for upgrading fine coal. Previously, numerous investigators have tried to upgrade coal values by froth flotation(1-16) and have achieved moderate success. However, the recovery and grade of coals in the concentrates are not always satisfactory, especially when the particle size is small. In general, when the size of coal is below 100 mesh, the above methods suffer from poor grade and low recovery. The reason for this is that as size decreases, the effects of gravity diminish, and other forces take effect.

Jan 1, 1985

Sandvik built its first stone crusher in 1896 and has since grown to become a world leader in mining equipment. ?We are the best in the world, and we can now be even better at making our cone and jaw crushers in different models,? Olle Lundberg, production engineer at the Sandvik Mining factory in Svedala, Sweden told freelance journalist U. Samuelsson, of mekpoint.com. As a specialty manufacturing business under the umbrella of the Sandvik Group, Sandvik Mining is a leading global supplier of equipment, tools, services and technical solutions for the mining industry. Its expertise covers the areas of rock drilling, cutting and crushing, as well as loading, hauling and the handling of materials. Lundberg, along with five colleagues, will write CNC programs for the lathes and machining centers that manufacture Sandvik?s specially constructed casting. In 1999, Sandvik chose ESPRIT computer-aided-manufacturing (CAM) software by DP Technology to program its array of machine tools, and has worked with ESPRIT reseller Holotech, based in Örebro, since 2003.

Jan 1, 2014

By Tom Learmont

The importance of coal in solving our energy problems has been widely discussed; the world demand for food requires increased fertilizer production and the minerals to produce fertilizer must be mined. We have seen an explosive increase in the demand for large stripping equipment. It is appropriate that we review this equipment and determine what can be done to improve productivity. While we have used coal mining as an example in the study, much of the discussion will apply equally to other forms of stripping.

Jan 1, 1975

By Koichi Nishimura

Japan's coal reserves are estimated at 8,583 million tons (according to the materials on X World Energy Conference,. 1976). Japan is a long island country in the shape of an elongated cashew nut whose top is pointing to the north and its lower tip is pointing to the west. And her major coal fields are located in the two extreme far parts of Hokkaido in the north and Kyushu in the south. On the other hand, Japan's major industrial center are located in the central part of the country far from either coal-producing areas. This fact places coal a great geographical disadvantage in comparison with petroleum whose refining bases are concentrated on the coastal regions virtually next to major industrial centers.

Jan 1, 1982

By C. Roos

Tradicionalmente en la industria minera, el flujo principal del proceso funcional para la evaluación de recursos y reservas procede de geólogos que elaboran el modelo geológico, de allí a los geólogos que hacen la estimación de los recursos (los modeladores) quienes estiman los grados, y a los ingenieros de mina que desarrollan el diseño de la mina y su calendario. La interfaz entre estas tres disciplinas no está siempre exenta de baches. Las presunciones hechas durante una etapa del proceso no siempre son comunicadas a los demás, a pesar que la mayoría de las empresas mineras tienen procedimientos y protocolos establecidos para promover la comunicación a lo largo de las distintas disciplinas. Estos procedimientos no siempre logran su propósito debido a una variedad de razones que incluyen restricciones de tiempo, no tener disponible a las personas apropiadas, o a una falta de entendimiento de lo que las otras disciplinas requieren, y el proceso de traspaso puede degenerar en el envío de archivos a la siguiente disciplina en el flujo de proceso. Este artículo se ocupa de la interfaz entre la estimación del recurso y las disciplinas de la ingeniería de minas y el esquema de algunas de las presunciones comunes hechas al generar un modelo del recurso y los riesgos que los ingenieros podrían correr al elevar los grados de corte, optimizar calendarios o realizar predicciones. Los casos de estudio presentados se centran en depósitos de oro a cielo abierto, pero los conceptos deben ser aplicables a toda la industria. Aquí también proveemos un resumen de preguntas clave y recomendaciones.

Jan 1, 2014

By Bryan Ulrich

Knight Piésold and Co. hosted its annual roundtable discussion on March 17, 2011 at the Stockman Hotel and Casino in Elko, NV. The theme for Roundtable 2011 was, ?High density tailings, paste, and filtered tailings,? although the topic may well have been subtitled, ?Don?t prematurely rule out any technologies before they are given their day in court.? Bryan Ulrich, Knight Piésold?s local representative, as well as Tom Kerr from Knight Piésold?s office in Denver, CO, were on hand to help facilitate the discussion. Ulrich and Kerr are senior vice president and president of Knight Piésold?s U.S. practice, respectively. The event played host to more than 30 attendees from several western states. Attendees included personnel from a dozen mining properties and various corporate offices. There were also attendees from manufacturing and specialist consulting firms who have been providing services to various high-density tailings, paste and filtered tailings operations worldwide. It may be noted that the term ?filtered tailings? is used in this discussion. Alternative terms, such as ?dry stack? or ?dewatered tailings,? should be avoided whenever possible, as such terms tend to give a false sense about the nature of the material since these materials typically still retain a significant amount of moisture.

Jan 1, 2011

By M. D. Chatham

Revolutionary electronic monitoring and control systems provide a gold mine of diagnostic and prognostic information. Lower cost per ton results from timely operator action, increased visibility of information to production and maintenance personnel, and better fleet management. When information is effectively integrated into fleet management systems lower costs result from higher availability, longer component life and reduced repair cost. This paper will present the objectives of the Caterpillar Vital Information Management System (VIMS) and provide actual examples of successful use.

Jan 1, 1995

By C. Roos

Traditionally within the mining industry, the main functional process flow for resource and reserve evaluation proceeds from geologists who build the geological model, to resource estimation geologists (modelers) who estimate the grades, to mining engineers who develop the mine design and schedule. The interface between these three disciplines is not always seamless. Assumptions made during one stage of the process are not always communicated down the line, even though most mining companies have procedures in place to encourage communication across the various disciplines. These procedures do not always achieve their aim due to a variety of reasons including time constraints, appropriate people not being available, or a lack of understanding of what other disciplines require, and the handover process can degenerate into one of sending computer files on to the next discipline in the process flow. This paper focuses on the interface between the resource estimation and mine engineering disciplines, and outlines some of the common assumptions made when generating a resource model and the risks that engineers may be taking when elevating cutoff grades, optimizing schedules or generating forecasts. The case studies presented focus on openpit gold deposits, but the concepts should be applicable throughout the industry. A summary of key questions and recommendations is provided.

Jan 1, 2014

By O. A. Bascur

In recent years, metal-producing companies have increased their investment in automation and technological innovation, embracing new opportunities to enable transformational change. Transformation to a digital plant can fundamentally revolutionize how industrial complexes operate. The abundant and growing quantity of real-time data and events collected in the grinding and flotation circuits in a mineral processing plant can be used to solve operational issues and optimize plant performance. A grade recovery model is used to identify the best operating conditions in real time. The strategy for increasing the value of instrumentation in current plants is reviewed. An optimal Gaudin size distribution model provides augmented information from traditional sensors to find the optimal grind cut size to reduce metal losses in the flotation circuits. Sensors in flotation circuits enable an estimate of the recovery and determination of the optimal froth depth and aeration using an air hold up flotation model. A strategy of classifying data for on-line generation of insights to using operational intelligence tools is described. The implementation of a recovery/grind strategy with industrial examples in non-ferrous mineral processing is presented.

By Richard Giffen, Michael Trabold, Pablo Lemus

"As part of the new 2nd Ave Subway Project, an existing tunnel constructed in the 1970’s will be connected to the new subway and used as new running tunnels. The existing tunnel had to be modified to comply with newer structural and fire life safety codes and to be connected to the new cut and cover station at 96th St. This paper will discuss the complexities of tying an existing tunnel constructed over 40 years ago into the new station and allowing for movements due to the unloading of the existing tunnel and the differential settlement of the two structures during both the construction and permanent condition. Topics that will be discussed include structural analysis, ground improvement techniques, selection of support of excavation walls, working in contaminated soil and instrumentation and monitoring of the structures. It will also cover retrofitting the tunnel to comply with updated Fire/Life/Safety requirements. PROJECT OVERVIEW The Second Avenue Subway (SAS) will be the first major expansion of New York’s subway system in over 50 years. To be constructed in four phases, it will run from 125th St. in Harlem to Hanover Square in the Financial District (see Figure 1). For most of its length, the alignment is directly under the Second Avenue roadway."

Jan 1, 2016

By M. Li, W. R. Reed, J. P. Rider, J. D. Potts

"The National Institute for Occupational Safety and Health (NIOSH) recently developed a series of validated models utilizing computational fluid dynamics (CFD) to study the effects of air-blocking shelves on airflows and respirable dust distribution associated with mediumsized surface blasthole drill shrouds as part of a dry dust collector system. Using validated CFD models, three different air-blocking shelves were included in the present study: a 15.2-cm (6-in.)-wide shelf; a 7.6-cm (3-in.)-wide shelf; and a 7.6-cm (3-in.)-wide shelf at four different shelf heights. In addition, the dust-collector-to-bailing airflow ratios of 1.75:1, 1.5:1, 1.25:1 and 1:1 were evaluated for the 15.2-cm (6-in.)-wide air-blocking shelf. This paper describes the methodology used to develop the CFD models. The effects of air-blocking shelves and dust collector-to-bailing airflow ratios were identified by the study, and problem regions were revealed under certain conditions. IntroductionSurface blasthole drilling can generate considerable amounts of respirable silica dust. These high dust concentrations can be exacerbated by the high silica content as drilling cuts through silica-bearing materials such as sandstone and shale, causing overexposures for miners to respirable silica dust. These overexposures can lead to silicosis, an occupational lung disease that has no cure and is often fatal. A review of the Mine Safety and Health Administration (MSHA) respirable silica dust sample database from 2010 to 2016 for metal/nonmetal mining shows the following overexposure rates for occupations related to blasthole drilling: • 14.1 percent of rotary air drillers were overexposed to respirable silica dust (22 out of 156 samples).• 5.8 percent of rotary drillers were overexposed to respirable silica dust (nine out of 155 samples).• 7.3 percent of drill helpers were overexposed to respirable silica dust (three out of 41 samples).• 7.5 percent of blasters/shotfirers were overexposed to respirable silica dust (three out of 40 samples)."

Jan 5, 2018

By D. F. Doerr, E. Blalock, D. R. Bush, K. D. Cohen

"INTRODUCTION The design, development, fabrication, and test of cryogenic breathing apparatus is part of a much larger effort funded by the National Institute for Occupational Safety and Health (NIOSH) and managed through a Space Act Agreement with the National Aeronautics and Space Administration (NASA) at the Kennedy Space Center (KSC) in Florida. This effort is designed to create cryogenically based life support equipment that is responsive to the needs of miners as required by the Miner Act of 2006. Our goal was to design and build a liquid air based self-contained breathing apparatus (SCBA) that lasted 2 hours and would be used for the egress of miners during a mining accident and be refillable while worn. Therefore, the current report describes tests of an Advanced Cryogenic Breathing Apparatus (termed the ACryoBA) designed to provide miners egressing an emergency situation with a two-hour open-circuit SCBA. The ACryoBA utilizes low pressure cryogenic liquid air instead of high pressure compressed air commonly used in most commercially available SCBA. The ACryoBA can also be self-filled from strategically placed Cryogenic Air Supply and Fill Stations (CryoASFS) initially, and thereafter on the egress route approximately every 1 hour and 30 minutes with a 30 minute air reserve. The ACryoBA evolved originally from a one hour Liquid Air Pack (LAP) developed in the 1980’s for Space Shuttle Rescue forces allowing for longer duration and cool air (Figure 1). It was used successfully for many years, through the end of the Space Shuttle Program. The first attempt at a mine egress pack was the Cryogenic Breathing Apparatus (Figure 2). It was to have a low profile, two hours of breathing, attitude independence, and a simple rapid refill while in use. The CryoBA met the two hour criteria, but with difficulty due to excessive heat leakage caused by the dual 4 liter Dewar design. Much of the stored air was lost as it vaporized faster than it could be used. However, the pack was successful in demonstrating both attitude independence and a simple rapid refill capability. The ACryoBA project was designed to continue the progression and address the deficiencies in the CryoBA. The ACryoBA pack was designed to last 2 hours. It minimizes the heat leakage with a single Dewar and thereby requires less liquid air. The single Dewar design also minimizes weight, making it much more manageable by the user (Figure 3). The ACryoBA complies with 42 CFR part 84 NIOSH certification test requirements. One critical requirement for the ACryoBA is operation in positions other than vertical for periods up to 1/4 (i.e. 30 minutes) of the rated service life of 2 hours; this was accomplished by use of new technology called the “attitude independent pickup” which is abbreviated “AIP.” The AIP, developed by BCS Life Support LLC (patent #8,899,226), has a tube going from the top flange down through the center of the Dewar. At the end it has a flexible bellows and a weighted end. Due to the flexible nature of the bellows, the pickup at the end is free to rotate and follow the liquid level around within +/- 90o of vertical."

Jan 1, 2016

By Claudia Castillo, Katja Freitag, Jan Cilliers, Diana Drinkwater, Robert Seitz

The talent gap in mining is not a new challenge. Mining companies continue to seek innovative ways to attract, develop and retain talent, and younger workers are looking for opportunities to develop their professional careers. Training provides a key value proposition for both employees and employers as it helps build a talent pipeline while offering opportunities for learning and growth and value creation. In 2020, Metcelerate launched its 20-month program for early career mineral processing engineers. The program helps develop critical technical skills in the workplace and is a tool to identify motivated engineers and change culture within teams. Learners cap their skills development by executing a technical investigation. This generates immediate value—a win-win outcome for learner and company.

Feb 1, 2025

By D. Murray

"The Mine Improvement and New Emergency Response (MINER) Act included the need for improved chemical technologies to address respiratory protective device inadequacies and refuge alternative development. The National Institute for Occupational Safety and Health’s (NIOSH) National Personal Protective Technology Laboratory (NPPTL) invests in research and development to improve the carbon dioxide (CO2) scrubbing technologies built into these mine safety systems. Testing at NIOSH NPPTL is performed using a custom-designed test system containing a chemical reactor and sensors in a constant flow of simulated expired breath to evaluate chemical performance for the scrubber materials. Current testing procedures focus on device duration or capacity, but do not report criteria needed to effectively optimize chemical performance. In this presentation, testing results which identify the chemical performance roles for CO2 scrubber components will be reported, and specific component chemical activities will be linked to both duration and CO2 absorption capacities. Chemical components being evaluated include hydroxyl, superoxides, metal, and amine active sites, distributed in salts, zeolites, metal-organic frameworks, and microporous materials. INTRODUCTION CO2 absorbents and oxygen sources are at the heart of closed circuit breathing air supply systems used in mining escape and rescue operations. CO2 absorbent technology was first developed for diving rebreathers and has been in use for over a century. Typically these devices include a soda lime formulation of pellets in the 8-12 mesh range. Larger 4-8 mesh particles are used in medical grade “low-flow” applications, since these particles present a lower flow resistance regime more amenable for use with resting individuals. Potassium superoxide and lithium hydroxide formulations are also used, where in each case the formulations involve bulk solid pellets or materials affixed to surfaces. CO2 capture technologies are now under intensive study in the energy and automotive industries, where the pursuit of optimal combustion processes has led to the development of new materials to capture, convert and store CO2, oxygen and carbon monoxide gases. Recent advances in nano-structured and high surface area catalysis have produced novel materials demonstrating chemical performance improvements in these industries, and these improvements may now also be adapted to enhance chemical efficiency and performance in escape and rescue devices. Higher surface area materials offer promise for improving the efficiency, or decreasing the burdens associated with the use of closed circuit respiratory protective devices containing CO2 absorbents. Novel chemicals that display advantages in chemical performance or decreased burden will be examined for inclusion in developing systems such as the next-generation closed-circuit mining escape respirator or refuge alternatives."

Jan 1, 2018

By M. Adnan Goksel

The hydrothermal agglomerating process described (U.S. Pat. 3,235,371, (1966)) is different from the conventional high temperature processes. Green pellets or briquettes made with mixtures of moist iron ore concentrates and burned or hydrated lime fines are hardened in an autoclave at 198°C and under steam pressure for 1/2 to 5 hours, with or without previous drying. Under the neutral conditions, oxidation of magnetite does not occur as in the conventional processes. The resulting agglomerates are hard and resistant to abrasion and weathering, and they do not disintegrate in the Linder test. The equipment required for the process is not complicated, and favorable operating costs are projected because of the low temperature and efficient heat recuperation. A low capital investment makes the process attractive even when the annual pellet production is below a million tons.

Jan 1, 1968

By James E. Myers

This study is a survey of the current "state-of-the-art" of commercially-available sonar tools to monitor the true shape of man-made cavities within the Hutchinson Salt of south-central Kansas. The work entailed ferreting out the available information, most of which is proprietary in nature; then examining actual existing conditions and arriving at a reasonable scientific evaluation of the method. Our studies were confined to one LPG field and two brine well operations in south-central Kansas. No field testing of any devices was performed, only questioning user firms, and studying cores, logs, and sonar surveys graciously made available by the companies we have contacted. Since these data are still somewhat proprietary, the company participants have asked that their company names be omitted from this presentation.

Jan 1, 1973

By R. K. Mehta

Conventional triboelectrification based dry coal beneficiation methods require ground coal as a prerequisite feed material, energy intensive static-in-line mixer or cyclonic tribocharger configuration, and transport and/or improvement in the design of free-fall separators to improve the separation efficiency of [me pyrite/mineral matter from coal. The proposed paper illustrates the two concepts. First, the use of ceramic media in a polyurethane lined attitor in achieving simultaneous grinding and differential charging. Second, the use of an electrocentrifuge to selectively separate coal from mineral matter present in the triboelectrified mixture. It is of interest to note that some ceramic media can satisfy the requirements of both desired density and work function to achieve grinding and differential charging.

Jan 1, 1996

By Bryan Ulrich

On March 15, 2012, about 24 attendees from several western states attended Roundtable 2012, hosted by Knight Piésold and Co. at the Red Lion Hotel and Casino in Elko, NV. The focus of this year?s discussion was ?Acid Rock Drainage for Engineers and Environmental Scientists.? Other names may have been more suitable for the event, perhaps combining geochemistry, with air and water quality and their long-term effects on soil and rock mechanics. Bryan Ulrich (senior vice president, Knight Piésold?s Nevada operations) and Steve Lange (senior geochemist, Knight Piésold, Denver, CO), helped facilitate the discussion. Attendees included personnel from a dozen mining properties, various corporate offices and academia. There were also attendees from a geochemical testing laboratory to help respond to specific questions pertaining to testing protocol and procedures.

Jan 1, 2012