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In the screening process, used to prepare particles for many applications, shape is known to have a significant effect. The degree of flakiness of construction aggregates has been considered particularly important. The objective of this research was to find values of operating parameters that optimize the separation of flaky from non-flaky particles by slotted screens. Thus an investigation was conducted to experimentally determine the influence of the particle size and thickness on the screening process. The Response surface method was employed for modelling and analysis of the data. Experiments employing a central composite design were performed on a pilot-scale, rectangular-aperture, vibrating screen to examine the effects of the screening variables the mass recovery of flaky and non-flaky particles to the oversize product. The SAS statistics package was used to fit a second-order model to each response and to analyze the fitted surface to determine the optimum levels. The optimization associated with a dual response system was then considered. The results of this study should provide a basis for optimizing screening conditions to obtain maximum recovery of non-flaky particles to the screen oversize while minimizing the recovery of flaky particles, which should be of interest to the aggregate industries.

Jan 1, 1999

By Frank A. Jerabek

Pneumatic stowing was first introduced in longwall mining in the middle twenties. Since that time it has advanced through many stages of development, particularly abroad, which have greatly improved its efficiency and contributed to its growing use. Pneumatic stowing originated in coal mining but has also been adopted in metal mining. This paper discusses the techniques of pneumatic conveying of. stowing material and equipment and applications of pneumatic stowing.

Jan 1, 1966

By Goran Mathisson

In several investigations the correlation has been studied between the fuel consumption and the reducibility of the charged material in the zone of indirect reduction in the blast furnace (1, 2, 3, 4, 5). It has been found that increased reducibility allows greater gas utilization which accordingly lowers the fuel consumption. In direct reduction units this relation has not yet been fully established partly owing to the lack of accurate test methods and experience with different materials as regards reducibility. However, since the production rate in a direct reduction unit is closely related to the time required to reach high degrees of reduction, the reducibility must be regarded as one of the most important properties of the material.

Jan 1, 1979

By M. Ruonala

The Larox Power PF Pressure Filter has been developed to meet the challenges of ever increasing output tonnages demanded by the minerals processing industry. This paper will highlight recent experiences at the Rudna Copper Concentrator in Poland, the Escondida Copper Concentrator in Chile and some large zinc concentrators in Australia. Detailed maintenance and operating cost information will be disclosed. Emphasis will be placed on economics on scale gained from higher machine throughputs.

Jan 1, 1998

By J. Launay

In order to control and dispatch the sewage water coming from 3 tunnels toward 2 downstream sewage tunnels, a large cavern has been excavated in a suburb of PARIS. Located at a depth of 47,00 m, it has been excavated using the NATM procedure through swelling clay, weathered sandstone, and marl and chalk. It is 16,50 m high, 12,40 m wide and 60, 00 m long, with an elliptical cross-section and its two ends are egg-shapped. The final lining of the cavern is composed of 30 to 40 cm of shotcrete, steel ribs and passive anchor bars. The excavation stages and related movements were surveyed by extensometers, pressure cells and convergence devices. The design, method of construction of the cavern and the results of the measurements made are commented.

Jan 1, 1989

By Christopher Newman, Robert Dupuy, David Newman

"The development of a multiple level underground mine is a complex task in which geology, engineering, ground control, and unit operations are integrated into a single mine design. The components are inter-dependent and must function cohesively to ensure a profitable underground mining operation. To optimize reserve recovery, mine planning should begin from the lowest level and progress up. This limits any misjudgments or oversights of a given level affecting the underlying levels and ensures the ability to maximize recovery from each level.Mine planning should start with the exploration and characterization of the geologic setting. Once the reserve geology and quality is well understood, then mine planning can begin with respect to the following:,Orientation of mine works with respect to horizontal stress,,Access to the reserve,,Determination of opening widths,,Selection of back, floor horizons and pillar centers,,Selection of development and secondary mining heights,,Appropriate interburden thicknesses, and,Examine the stability of the multiple level mine through numer¬ical modeling.The multiple level mine design process and decisions are presented through a case history example. The theme is that there is one opportunity to “get it right” as well as many chances to overlook a small aspect within the design that will plague the mine throughout all levels and through the entirety of its operating life.INTRODUCTIONAs surface quarries reach their economic stripping limit and encroach on mineral and/or reserve boundaries, they approach the end of surface mineable reserves. Furthermore, modern urban sprawl has placed previously remote surface quarries within suburban development and neighborhoods, leading to significant increases in noise, dust, and vibration grievances by the community and regulators (Newman, 2017). Many mining operations have begun year-round production of underground reserves to meet growing market demands. This does not permit the typical sequence of stripping overburden in the winter to provide limestone to mine during the construction season. Underground stone mining operations in the United States commonly utilize a room-and-pillar mine layout with drill-and-blast production methodology for the development of the reserve. Within the Midwest and Eastern regions, thick and flat-lying limestone formations lend themselves to the utilization of multiple level mining layouts. While a multiple level mine plan will increase the overall recovery of the reserve, greater overburden depths, multiple level geometry, and the presence of discontinuities all require an emphasis on ground control for the planning and development of a safe and productive multiple level underground stone operation."

Jan 1, 2019

By Edward S. Frohling

Va a ser discutida la información que se requiere para un estudio preliminar de viabilidad y la información adicional que se requiere para el estudio final de viabilidad de un nuevo depósito de mineral. El estudio preliminar de viabilidad se realiza con muy poca información y con un mínimo coste para el propietario. Sin embargo, el diseno del informe preliminar es similar al utilizado para el informe final. En este momento, se supone que el resultado del estudio preliminar es favorable y el propietario autoriza el estudio final de viabilidad a una compañía de ingeniería. Se describirá el tipo de organización para completar el estudio final de viabilidad. El informe final incluirá toda la información y datos relativos al nuevo depósito de mineral. La información presentada debe ser entendida lo mismo por el personal financiero que por el técnico.

Jan 1, 1982

By B. R. Pothini, H. von Schonfeldt

In underground coal mining many excavated openings have a relatively short projected life span. To ensure safety for men and materials at a minimum cost over the projected operating life, only pillars for overburden support and roof bolts for support of the openings are used extensively. Mining activity constantly changes the geometry of the mine producing load changes on the structural support members of the openings that often induce unstable deformations which can lead to roof falls or pillar failures. The paper describes how simple deformation measurements can be used to design primary and supplementary roof supports and to predict roof falls and possibly pillar bumps. Specifically, bed separations in the roof measured directly with the help of borescopes and calculated from differential convergence data are used to optimize bolt links or support requirements for chemical stabilization of mine roofs. Roof falls are predicted on the basis of admissible values for cumulative convergence between roof and floor, convergence rate, and the change of the rate of convergence. The pillar extraction operations convergence anomalies detected from contouring identify bump prone pillars, while convergence and pillar dilation determine the yield zone in a pillar to verify pillar softening and de-stressing. Manuscript not received in time for publication.

Jan 1, 1983

By J. Kretschmann, T. Rudolph, L. Michael, P. Goerke-Mallet

The mining value chain plays an important role in our societal development. Even in a circular economy, mining and raw materials are in great demand, and so are skilled engineers. In Germany, many students decide to pursue STEM studies in the tertiary degree. Nevertheless, the OECD reports low completion rates in obtaining the degree of studies [1]. Generally, the dropout rates in STEM education are high [2]. Many students have difficulties with basic subjects such as science and mathematics, in which they lack knowledge they should have acquired in school [2]. With the German STE(A)M project PepperMINT (https://peppermint.thga.de/), the Technische Hochschule Georg Agricola (THGA) offers a digital and open educational platform, as a dynamic, massive open, online course (MOOC) for students and prospective engineers. The project is funded by the RAG-Stiftung (RAG-Foundation; No. 20-0004). Using adaptable MOOC classes and applied examples from the wide-ranging cycle of mining activities, we motivate students to engage in STEM studies. Our adaptive and application-oriented content demonstrates the diversity of jobs and career paths in the mining industry. The integrations of applied examples and research activities of the Technische Hochschule Georg Agricola can increase the curiosity and motivation of learners. In mathematics, mine-surveiying technologies and geomonitoring methods (see figure 1) can be used to teach trigonometry. Additionally the concept of the free open online classes enables students in high school to get insights into the field of engineering before they decide the subject of their studies. For freshmen who already decided to pursue a STEM degree, the PepperMINT courses can help to identify and close knowledge gaps and to align different levels of knowledge within a heterogeneous student body. Empowering students in STEM education and integrating examples from mining research can help us train the mining engineers of the future.

Mar 2, 2022

By S. Guo

In this paper, a model for the resin anchor bolt system is developed in which the smooth bar is modeled by using one-dimensional truss elements and the resin annulus is modeled by using axisymmetric elements. These two submodels are combined together and then incorporated into the' existing computer code ROOFBOLT. After this development, all of the components in the resin anchor bolt system including smooth bar, bearing plate and resin annulus can be correctly modeled.

Jan 1, 1995

By Matthew Grzelak, Gulsah Erinc, David R. Chapman

"The third phase of the Bagram Drainage System project at Bagram Air Force Base in Afghanistan included construction of a shallow, 540-m long, 1.8-m inside diameter drainage tunnel. The tunnel penetrated mostly stiff to hard clayey and silty soils. The contractor’s Value Engineering Change Proposal (VECP) to use pipe-jacking with a microtunnel boring machine (MTBM) instead of the specified two-pass Earth Pressure Balance method was evaluated and supported using hand calculations. Contractor support was provided throughout the project by providing design reviews and instrumentation monitoring during construction. This paper compares the value-engineering proposal to the specified method and describes the construction conditions encountered. INTRODUCTION As part of a larger improvement project at the Bagram Air Force Base in Afghanistan, a shallow, 540-m long, 1.8-m inside diameter drainage tunnel was constructed to provide additional capacity for Coyote Creek to pass below several critical structures, including taxiways and the main runway, for mitigation of recurring flooding (see Figures 1 and 2). Overburden over the tunnel crown ranged from about 3 m to 5.5 m. An existing cast-in-place twin barrel concrete culvert runs approximately parallel to the new tunnel and is within about 8 m at its closest point. The contractor’s Value Engineering Change Proposal (VECP) to the specified two-pass Earth Pressure Balance (EPB) method (steel ribs and lagging or steel liner plate with a carrier pipe later grouted in-place) called for installation of the required drainage pipe by pipe-jacking (one-pass installation) using a slurry microtunnel boring machine (MTBM). The critical nature of the operations at the air base resulted in significant construction coordination challenges and a greater than usual need to avoid excessive settlements. Substantial restrictions were placed on drilling of investigative borings and installing instrumentation near runways and taxiways due to drill mast height. The prime contractor was SERKA TAAHHUT INSAAT A. S. (SERKA), the microtunneling subcontractor was Ludwig Pfeiffer Microtunnel GmbH & Co.KG (Pfeiffer), the jacking pipe designer was Gollwitzer Pipe and Shaft Technology GmbH (Gollwitzer), and the contractor’s tunnel engineer was Lachel & Associates, Inc. (Lachel). Lachel provided contractor support throughout the project including preparation of a VECP/Design Summary (including interpretation of existing and new geotechnical information), design reviews for jacking pipe, estimating settlement of an existing drainage structure above the new tunnel, and instrumentation planning, monitoring, and analysis during construction."

Jan 1, 2016

By P. F. Ziemkiewicz, A. S. Knox

Large-scale use of CCBs in mine environments involves filling surface and underground coal mines with ash to address hydraulic problems, AMD, backfilling and subsidence. The environmental risk of land filling CCBs is generally evaluated by the Toxic Characteristics Leaching Procedure (TCLP) or the Synthetic Precipitation Leaching Procedure (SPLP). However, there is doubt regarding the applicability of these tests to long-term CCBs leaching behavior in groundwater associated with coal mines. The Mine Water Leaching Procedure (MWLP) was developed to provide a site specific risk assessment tool. The MWL Pprocedure is presented in this paper and compared with TCLP as a study.

Jan 1, 2003

By A. M. Wala

It is common practice in Appalachia, when extending the life of an existing mine, to acquire the adjacent reserves and extend the existing mine into it. Also, often the existing mine is renovated to accommodate the new conditions. The existing mining system and the track and belt haulage systems may be modified while the new property is integrated into the old one. All of these changes create new constraints for the mine ventilation system (M.V.S.) that require proper planning and control procedures. The authors describe and present the study that was carried out for the ventilation system of a newly expanded underground coal mine located in the Appalachian coal region. Discussed first is the process of correcting the ventilation system of the existing mine. Then, some of the stages of controlling the expanded system are discussed. Finally, numerical data for these steps are presented.

Jan 1, 1992

By P. Somasundaran, H. S. Hanna

The separation of minerals such as apatite and scheelite by flotation from other salt-type minerals such as calcite is extremely complex owing to the close similarity between their physicochemical properties. In this paper, properties relevant to flotation such as crystal structure, solubility, surface charge and adsorption behavior of important salt-type minerals are examined along with the role of inorganic modifying agents such as silicates and polyphosphates and organic modifying agents such as starch and tannin. Flotation characteristics of these minerals are then reviewed and selected separation problems involving salt-type minerals are discussed.

Jan 1, 1976

By T. E. Mccandless

Detrital minerals of mantle origin have been found in the Green River Basin of Southwestern Wyoming (Figure 1). Pyrope, pyrope-almandine, and chrome-bearing clinopyroxene and orthopyroxene occur on the antmounds of Pogonomyrmex Occidentalis. These antmounds are a common sight throughout the western U.S., and were used by early paleontologists as fossil mammal collection sites. The mound is composed of two types of material; (1) soil excavated during the digging of the nest below the surface (maximum depth 3 meters) and (2) larger grains collected from the surface and placed on the mound, probably to prevent erosion. The selection of grains to armor the mound seems to be based largely on the mean diameter of the grain, with other factors such as weight, sphericity, roundness and composition in decreasing order of importance (Wheeler and Wheeler, 1963). The minerals of this study happen to fall within that mean diameter range. The garnets are found on the mounds as 3-6 mm diameter subrounded to subangular grains. The pyroxenes are also 3-6 mm in diameter and are most commonly subangular laths. The minerals themselves show evidence of abrasion, such as frosted surfaces and rounded edges. Orange peel texture is present on some of the grains, which suggests that kelyphitic rims were once present, but have been removed. Also, no similar minerals were found in sieved soil auger samples to depths of 2 to 6 meters taken near the antmounds. These observations imply a distal rather than proximal source for the minerals. Lamproitic rocks of upper mantle origin are found bordering the "Green River Basin. The best known are the Leucite Hills, a series of ultrapotassic volcanics found on the north flank of the Rock Springs Uplift (Carmichael, 1967). Minor occurrences of mica peridotite and ultrapotassic volcanics are also found on the western end of the Uinta Mountains in Utah (Best, et al, 1968). None of these rocks are known to contain minerals like those on the antmounds. The garnets are comprised of purple chrome pyrope, red chrome pyrope-almandine, and pink to orange low chrome pyrope/pyrope-almandine. Oxide statistics for these groups are summarized in Table 1. These three groups are distinct when their Cr203 values are plotted against magnesium number (Figure 2). The chrome pyropes are highest in Cr203 (1.28-2.66%) and have high, restricted Mg number values (0.781-0.826). The chrome pyrope almandines have similarly high Cr203 (1.29-2.62%) but a lower Mg number range. The low chrome pyrope/pyrope-almandines have the lowest Cr203 content (0.09-0.73) and the widest Mg number range (0.534-0.836). Using the classification scheme of Dawson and Stephens (1975) the chrome pyropes are most similar to garnets derived from kimberlite and from garnet lherzolite, websterite, and harzburgite xenoliths in kimberlite. The chrome pyrope-almandines and the low chrome pyrope/ pyrope almandines are similar to garnets derived from eclogite nodules (Figure 3).

Jan 1, 1984

By V. D. Hanson

When maintenance of a plant or operation is under discussion immediately three "M's", all in short supply, are brought to mind - money, men and markets. This paper will present what currently is being done at our plants and its effect on the 3 "M's". Examination of coal realization figures (F.O.B. Mine) from 1945 to the present reveals the fact that open and free competition can and will meet market conditions. The industry, without benefit of advantages afforded tax and transportation wise to oil and gas, remains the backbone of the energy market of United States. Figure No. 1 shows the realization figures from 1945 through 1962 compared to the hourly earnings. Note that through 1945 to 1948 F.O.B. prices increased $1.93 per ton while hourly earnings increased $.66 per hour. Since 1948 (with the ex¬ception of 1957) F.O.B. prices have declined $.45/ton, while hourly earnings have increased $1.23 per hour. Basically the maintenance men possibly represent the highest increment rate in the overall hourly earning.

Jan 1, 1963

By Michael J. Hannan, Thomas F. Torries

The nature of industry structure is examined and the structure of the aluminum, copper, lead and zinc industries are described by the use of factor analysis. Capacity is defined and the relationship between industry structure and capacity utilization is examined. It is demonstrated that excess capacity is possible in industries with competitive or monopolistic characteristics, but the effects of the overcapacity are vastly different in the two cases. In a competitive industry, cycles of overcapacity with attendant fluctuating prices are expected. A change in industry structure from monopolistic to competitive characteristics over time causes profits and economic rents to be transferred from the producer to consumers of the mineral.

Jan 1, 1989

By T. J. Lutz, J. L. Carr, J. A. Yonkey, C. C. Jobes

"Since 1984, the date of the first recorded fatality involving a remote controlled continuous mining machine, 38 miners in the United States have been killed when they were struck by a continuous mining machine. Proximity detection is a valuable tool for preventing fatalities, and the use of these systems is expected to significantly improve safety. Proximity detection provides a means to prevent accidents like these. Researchers at the National Institute for Occupational Safety and Health (NIOSH) conducted a series of underground tests to evaluate the accuracy and repeatability of proximity detection systems under a number of conditions such as varying the orientation and height of the personal wearable device (PWD), moving the PWD close to the trailing cable, and activating the machine’s mining mode. At the 2014 SME Annual Meeting, results from tests on first-generation proximity detection systems were presented. This paper will provide results from the similar tests performed with second-generation systems. The results show that performance has improved. For example, the negative impact of PWD orientation and the trailing cable has been reduced. However, some inconsistencies remain. Notably, performance changes dramatically when mining mode is activated. INTRODUCTION Since 1984 there have been 38 fatalities involving striking and pinning of the operator and other workers by the continuous mining machine (CMM) [1]. In August 2011, the Mine Safety and Health Administration (MSHA) published a proposed regulation that would require proximity detection systems on all continuous mining machines except full-face machines [2]. Proximity detection systems are designed to stop machine motion to protect miners from striking/pinning hazards. Several MSHA-approved proximity detection systems are commercially available. MSHA estimates that of the 38 fatal striking and pinning accidents that have occurred since 1984 involving CMMs, the use of proximity detection could have been a preventative factor in at least 28 cases [1]. Furthermore, MSHA estimates that proximity detection could prevent 20% of all deaths throughout the industry [3]. NIOSH researchers have been involved in the development and testing of proximity detection technology since creating the HASARD system [4] and have recently conducted research intended to develop more advanced proximity detection technology for CMMs [5,6,7,8]. In addition, NIOSH has also conducted research investigating how the signals of a proximity detection system propagate [9,10] and have developed a novel method for determining the location of a personal wearable device (PWD) relative to the magnetic field generators [11,12]."

Jan 1, 2015

By H. Shafick Hanna

The major problems are identified the high phosphorus content and the fine dissemination or encapsulation of mineral impurities, in, ,the iron bearing minerals, A process which combined extreme fine grinding techniques with magnetizing roasting or flotation separation methods, is suggested. By these methods concentrates assaying 60-61 percent Fe exceeding the widely accepted upper limit of 56 percent Fe set for these ores, were produced with 75-90 percent iron recovery. Moreover it was shown that the phosphorus content of these concentrates could be reduced from 0.25 to 0.03 percent phosphorus by acid leaching. A brief discussion on production costs based on current and future developments in iron ore processing is given.

Jan 1, 1980

By R. R. Klimpel

The process of flotation is an extremely important solids separation technique employed in a wide variety of industrial process applications. Froth flotation is practiced in the coal industry to recover fines produced during the mining and cleaning of coal. A recent review article by Aplan (1) covers the processing variables encountered in the flotation of coal and the variety of chemicals and operating conditions which affect recovery. Numerous engineering and scientific studies have been performed with the goal of providing semifundamental laws of flotation behavior for improved screening of flotation chemicals, better equipment scale-up factors, etc. Often the results of such work are expressed in the form of mathematical models (e.g. 2, 3, 4, 5, 6) which are potentially useful for evaluating (simulating) on paper such alternatives as possibles process operating or configuration changes, the effects of ore and reagent changes, etc. It appears to be commonly accepted that a complete scientific/engineering characterization of flotation is immensely complicated and not sufficiently developed at the present to accurately predict (or understand) many important industrial facets of flotation. Thus, one is often reduced to detailed experimental characterization in both the laboratory and plant in order to fully evaluate flotation changes or alternatives. It is the purpose of this paper to describe a method of batch laboratory data characterization that is useful in evaluating flotation chemical reagents including froth flotation of coal. The approach consists of running a series of time-recovery curves in a batch float cell followed by the computer curve fitting of this data to a series of mathematical models based on semi-physical reasoning. The unknowns or parameters of these models are then optimally chosen so as to best fit the experimental data. It has been found in both coal and mineral systems that changes in reagent type, concentration, system pH, grind, etc. cause very consistent and logical changes to

Jan 1, 1979