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By Raja V. Ramani

In many instances, the actual production from a longwall face does not equal the planned capacity. General problem areas which have been identified include face length and panel depth, face area and gate entry roof support, face conveyor and shearer wear, outby haulage system failures, number of entries in longwall gate development and longwall move time. The performance of a longwall face is totally dependent on the interaction of these and many other factors. To explore fully these interactions, a systems analysis of longwalls has been performed. In this paper, the systems approach, the factors considered in the analysis, and the results of the analysis are presented.

Jan 1, 1983

By R. V. Stewart

This chrysotile asbestos orebody is located near the northern tip of the Province of Quebec, Canada. It is some 1818 km (1130 mi) north of Montreal; 480 km (300 mi) north of the tree line and is situated within the zone of continuous permafrost. The open pit ore zone is approximately 0.4 km (1/4 mi) in length some 61 m (200 ft) in width and plunges at 25-30 below surface to a vertical depth of at least 610 m (2000 ft). The orebody was originally evaluated by programs of surface mapping, diamond drilling and bulk sampling. The fibre is semi-crude, possesses excellent strength, and good fibre length distribution.

Jan 1, 1978

By Mark Van Dyke, Ted Klemetti, Jake Beale, Zoheir Khademian, Joe Wickline

In 2016, a 3.7-ML magnitude event caused by mining activity occurred at a longwall mine in southwestern Virginia which was recorded by the United States Geological Survey (USGS) and felt by local residents. The event was the largest of its kind since a global mine design change by the operator was instituted in 2008 following three large events in 2005, 2006 and 2007 (3.4, 4.3, and 3.4, respectively). Two of the three pre-2008 events (2005 and 2007) damaged ventilation controls in the mine which fueled a mine fire. In 2016 the mine’s management requested researchers from the National Institute for Occupational Safety and Health (NIOSH) to access geological data and determine what parameters could possibly lead to events of a magnitude of 1.0 ML or greater. Evaluation of 2,152 geological data points and modeling revealed three major geological factors in common with the majority

By M. Hepokoski, M. Klein, L. Yan

"NIOSH research has shown that heat/humidity buildup is a major concern within coal mine refuge alternatives (RAs). These high temperature and humidity levels inside an RA may expose occupants to heat stress. Due to the safety risks associated with testing using human subjects, NIOSH partnered with ThermoAnalytics to create detailed thermal simulation models of RAs with human occupants. The objective of this effort was to predict a miner’s core temperature response and moisture loss in environments that may be encountered in a coal mine RA. These parameters were studied across a range of temperatures and relative humidity values to determine if the current 95°F apparent temperature limit for RAs is reasonable. The results indicated that the 95°F apparent temperature limit is protective, provided that miners are supplied with sufficient water. The results also indicated that the body core temperature did not reach dangerous levels even at an apparent temperature of 130°F. However, the results show that moisture loss increases with apparent temperature. Therefore, if the apparent temperature limit were increased, the water provided in an RA would have to be increased to offset moisture loss. INTRODUCTION The purpose of this effort was to predict a miner’s core temperature and moisture loss (sweating and respiration) in environments that are likely to be encountered in a coal mine refuge alternative (RA). A range of temperatures and relative humidity were studied to determine whether the current 95°F Steadman apparent temperature (AT) limit and 2.25 quart/day water requirements for RAs as mandated by the Mine Safety and Health Administration (MSHA) are reasonable [1, 2]. The effects of metabolic heat rate (activity level), miner size (height and weight), and pose (sitting or lying) on core temperature and moisture loss were also studied. MODEL DESCRIPTION TAITherm thermal modeling software (ThermoAnalytics, Inc.) was used to simulate humans in RA-like environments within a range of temperature and relative humidity combinations. The TAITherm Human Thermal Model (HTM) predicts the dynamic thermal response of the simulated miners while accounting for clothing, human tissue thermal properties, and active thermoregulation. The following sections describe the HTM in more detail, the thermal model setup for this analysis, and core temperature and moisture loss metrics found in published literature. Human Thermal Model Overview The TAITherm human thermal model was used to simulate the heat generated by the shelter occupants, and to predict the miners’ skin and core temperatures along with their sweat evaporation rates. The thermoregulation model simulates the process by which the body attempts to maintain a constant core temperature by considering the effects of shivering, sweating, and changes in skin blood flow. This model calculates surface and deep tissue temperatures within the human body as described by a surface mesh."

Jan 1, 2017

By M. F. Werneke

Flotation of the carbonate, oxide and silicate minerals of copper (malachite, azurite, chrysocolla) has been the subject of much research in recent years, but few effective solutions to this problem have been found. With decreasing reserves of sulfide minerals, the economic recovery of these "oxides" appears to be an important source of copper for the future. Xanthates have been known for many years to be malachite collectors (1), but only at very high dosages, or at lower dosages following activation of the mineral by sulfide ion. Dewitt and Batchelder (2, 3) found that chelating agents such as certain oximes were collectors for malachite and azurite, but also required high reagent dosages. Fuerstenau (4) has suggested, for example, that potassium octylhydroxamate may be an effective collector for malachite, On the other hand, Balberyszski (5) has found that oxide minerals may be completely sulfidized at high temperatures with gaseous sulfur or H2S, and then floated with conventional collectors. None of the above approaches appear to offer an economically effective method for the direct flotation of these oxide minerals.

Jan 1, 1977

By Ali Ahmadi, Andreas Rausch, Angela Binder, Stefan von der Mark, Dhananjeyan Jeyaraj, Jana Thomas, Nils Nöther, Stefan Wittek, Thomas Ulrich, Eleni Gerolymatou, Mario Kolling, Helmut Mischo, Michael D. Martin, Tugba Sen, Jens-André Paffenholz, Erik Farys, Oliver Langefeld, Wilfried Ließmann

This paper outlines the MOVIE project, which is dedicated to the development of a digital twin for an underground laboratory at the research and education mine “Forschungs- und Lehrbergwerk Reiche Zeche” in Freiberg (Germany). Data from induced rock deformations and temperature fluctuations is collected using fiber-optic sensors. The objective of the project is to establish a virtual laboratory for real-time analysis of the interactions between geology, geomechanics, geometry and ventilation. This will be achieved by integrating models from these disciplines with artificial intelligence, creating a sophisticated hybrid model. The insights gained will enhance safety and efficiency in mining through improved digital planning options, ultimately contributing to more effective resource management and operational decision-making in different mining environments.

Feb 1, 2025

By M. M. Veras, C. H. Sampaio, A. S. Young, D. Neto, C. O. Petter

"Due to new technological developments, automatic sensor based sorting has made progress within industrial minerals, precious metals, diamond, and coal mining in recent years (Lessard et. al. 2016). In order to re-introduce the technology to other mining sectors, this research discusses its application to iron, manganese, and zinc ores through test works performed by the authors. These test works were performed using Dual Energy X-ray Transmission (DE-XRT) sensor technology. In each case, pre-concentrations of the ore were created demonstrating the possibility to reduce waste material, energy costs, and water consumption while improving product quality of the ores. INTRODUCTION Sorting of mining ores is as old as mining itself (Salter, 1991). Sensor based sorting applications in coal mining began as early as the late 19th century (Louis 1928). New sensor technologies were developed and implemented sequentially for uranium, nickel, coal, and gold mining (Refining, 1949, Rose et al, 1950, Bloomfield et al, 1966, Clayton et al, 1987, Robben and Mosser, 2014). While these sensor technologies were developed decades ago, computational capacity to keep pace with the vast amount of information required utilizing the sensor technology did not arrive until recently (Lessard et. al., 2016). The sensor based sorting (SBS) process was effectively described by Salter and Wyatt in Minerals Engineering in 1991, and Wotruba and Harbeck in 2010 in the Ullmann’s Encyclopedia of Industrial Chemistry under Sensor Based Sorting. Both descriptions include the following key steps: 1. Presentation of the material or particles. 2. Examination or detection of the material or particles. 3. Processing or analysis of the data generated. 4. Physical separation of the material or particles by external means. Effective presentation of the material or particles is achieved when the sensor is capable of identifying each particle individually. This step requires that each fragment of the material be isolated, and it often involves acceleration of the material fragments by chute or mechanical means, as well as the spreading of particles by vibratory feeders (Salter and Wyatt, 1991, and Wotruba and Harbeck, 2010). The isolated particles typically are conveyed into an area wherein they are subjected to electromagnetic irradiation (except in cases of some radioactive ores), either in the form of x-ray, visible light, infrared, or other energies. A wide range of applications for sensor based sorting exists in the literature. The majority of applications fall into one of two camps, (1) pre-concentration of mineral ores, or (2) characterization of the material during processing (Buxton and Benndorf 2013). While there is much to be gained from in-line material characterization and the resulting control both of quality and processing, this article focuses primarily on the camp of pre-concentration of mineral ores."

Jan 1, 2017

By T. Cienski

The paper presents and discusses the results of a detailed study conducted on the subject of energy consumption in the comminution of industrial minerals. The study was based on pilot circuit testing, plant operating data collection, detailed equipment data and literature research. The areas covered by investigations include: high efficiency classification; air classifiers for cement grinding circuits; grinding aids in dry grinding: dry grinding circuit, control based on particle size measurement. Results obtained indicate a large potential for the reduction of energy consumption, in particular in the traditionally high cement clinker grinding circuits. Better classification techniques and correct application of grinding additives can significantly reduce power used per ton of product and also substantially increase grinding circuit output.

Jan 1, 1990

By J. Kemeny, K. M. Kim

A site-specific blasting model has been developed for the Asarco Mission mine. The main inputs to the model are the in situ block size (F80), the post-blast fragmentation (P80) and the intact tensile strength (To). The output from the model is the specific blast energy (ESE). Modern techniques are being used to obtain the input parameters for the site-specific blast fragmentation model. In particular, image processing software is used to obtain both the in situ block size and the post-blast fragmentation, and the Schmidt hammer is used to obtain the tensile strength at numerous locations throughout the rock mass. An initial model was developed using five test shots in an area of the mine that contains argillite and is relatively homogeneous. This process also included calibrating Schmidt hammer readings against actual Brazilian tensile measurements. The model for argillite will be updated as more tests are conducted, and the model will be extended to the four other primary rock types at the Asarco Mission mine.

Jan 1, 2011

By Howard M. Wells

Portfolio theory and the Capital Asset Pricing Model (Modigliani and Pogue, 1974) provides an investment decision rationale which takes account of the benefits of diversification in reducing effective risk, but this theory does not consider the financial capability of the firm to survive large losses if they should occur. The LL-curve theory (Wells, 1976) takes the latter consideration into account, but it does not provide for the effects of diversification. This paper pro- poses a general theory to account for both diversification and the financial capacity of the firm to underwrite the investment risks.

Jan 1, 1983

By M. Noppé

"Dilution in underground coal operations can be underestimated by up to five times during Feasibility Studies, with disastrous economic consequences. Every 1% of stone waste introduced can reduce an in situ specific energy of 11,000 BTU/lb (25 MJ/kg) by some 110 BTU/lb (0.25 MJ/kg) and increases the abrasiveness of the run-of-mine coal. Where a wash plant is not in place, penalties imposed for not meeting contractual specifications alone can amount to some AU$1 million per year.This paper presents a method for monitoring, reporting and ultimately controlling dilution in an underground coal mining operation. The dilution trends before and after introducing the recommended controls in a continuous miner/longwall mine are presented over an eight year period. The additional information from such a dilution monitoring program can also be used to control mining horizons and plan longwall extraction heights across the face proactively, on a short-term scale with resulting improvements in productivity. INTRODUCTION Grade control, as practiced on any mine, is concerned with predicting routine quality and tonnage values for short- to medium-term mining operations, and the reconciliation of these predictions against “actual” results. For a longwall mine supplying steam coal, such routine parameters may include the proximate analyses, specific energy (SE), abrasiveness and sulphur, as well as float and sink analyses if the coal is beneficiated. In addition, grade control is concerned with identifying the mineable horizon (or horizons) in a selective-mining operation, together with monitoring how well these horizons have been extracted or adhered to. Close-spaced surface drilling can be costly for any mining venture, particularly for longwall mines operating in the deeper seams. For this reason, much of the data for short-term grade control requirements are acquired during actual bord-and-pillar development. The underground data are derived from so-called “channel” samples. These samples are cut or chipped from the coal seam, perpendicular to the mining horizon, with dimensions suitable for obtaining sufficient “representative” sample for analyses. For a 2m thick mining horizon, a channel sample 300 mm wide and 50 mm deep over the thickness of the horizon would provide some 4.5 kg of sample, sufficient for most of the necessary tests. To allow the information to be computer recorded, additional information such as seam thickness, sample co-ordinates, and the elevation of the seam (or horizon) roof or floor, may be required."

Jan 1, 2015

By Robert C. Freas

The Northeastern United States is the most highly urbanized region in North America. It is also an area with a tremendous appetite for stone products. Within this context limestone has truely become an "urban ore". Its uses extend from traditional aggregate markets to lawn and garden, archetectual, chemical, agricultural, industrial, and environmental applications. This paper looks at both the occurance and uses of limestone in the northeast, and briefly examines changing patterns in consumptive use.

Jan 1, 1985

By R. N. Gow

Acidic treatment of enargite (Cu3AsS4) dissolves both arsenic and copper from the mineral and then attempts to separate them in the leach solution. The reactivity of enargite was examined in acidic solutions, over the pH range 1-7, to determine a potential range for co-dissolution.. Enargite mineral samples from Butte, MT and Quirivilca, Peru were used as working electrodes in a cyclic voltammetry corrosion cell setup, which were then cycled multiple times over -1000 to 1000 mV. Surface reactions and transitions were characterized using in-situ Raman spectroscopy, which were then compared to updated predominance diagrams for the copper-arsenic-sulfur system from a previous study done under alkaline conditions. The region of co-dissolution is limited to > 600 mV vs. SHE and pH < 1 under the proposed diagram.

Feb 23, 2014

By James S. Browning

The Mineral Resources Institute of The University of Alabama conducted research on the removal of sulfur from coal using a combination of gravity concentration and flotation methods. The research utilized the gravity and centrifugal force capabilities of the Humphreys spiral to remove part of the pyritic sulfur and ash. Flotation of the Humphreys spiral coal concentrate removed additional sulfur and ash to yield products that conform to Federal air quality standards for sulfur oxide emissions. The clean coal products recovered by the combined process contained 7.7 to 8.0 percent ash, 0.12 to 0.16 percent pyritic sulfur, and 0.78 to 0.96 percent total sulfur. Pyritic sulfur rejection by the process was about 95 percent. In addition to obtaining good recoveries of high quality coal the tests demonstrated that the pyrite in the wastes could be isolated as enriched flotation products by the combined gravity - flotation apporach. Pyrite concentrates analyzing 25 to 33 percent sulfur were recovered. Potential benefits of the pyrite flotation step are recovery of a product of possible market value and the elimination of the pyrite from the waste ash which could be a potential acid water problem when impounded.

Jan 1, 1981

By G. Wang, L. R. Moore, Y. Xiong, J. Gu

"Quartz is the second most abundant mineral in the earth’s crust. Not only does quartz have many valuable industrial applications, it is also one of the most concentrated gangue minerals encountered in the processing of other minerals. Minerals such as hematite, apatite, calcite, feldspar, barite, and many more. Numerous applications of industrial minerals are sensitive to the hardness and abrasiveness encountered with quartz minerals, while other applications may lead to processing challenges for the end user. Therefore, process and chemistry optimization must be applied to ensure optimal grade is obtained for these valued industrial minerals. Extensive studies have been conducted in processing various industrial minerals, thus achieving a range of quality specifications, which entailed the application of ArrMaz’s CustoFloat and CustAmine collectors towards the separation of quartz from other minerals. INTRODUCTION Industrial minerals often have the misfortune of the gangue mineral being very similar in surface charge, and coordination properties, to that of the mineral of interest. An example is seen in phosphate beneficiation, when dolomite can be a gangue minerals (Table 1). Therefore, the development of processing reagents are quite complicated. Some minerals, like clays, may be washed away. However, most require the manipulation of the pH, in efforts to fine tune the system to the narrow difference in isoelectric points of the different minerals, as well as the knowledge, and resources that are necessary to exploit the differences to yield and an optimal grade/recovery. In some cases, the application of a depressant may be required, such as the phosphoric acid commonly applied to achieve the optimal balance of grade/recovery for phosphate from a mineral with elevated concentrations of dolomite (Wang, 2016), or the application of hydrofluoric acid to assist in producing feldspar product from a mineral rich in quartz (Heyes, 2012).ArrMaz's CustoFloat and CustAmine product lines have successfully been applied to the processing of industrial minerals for more than 50 years. Applications include, but not limited to phosphate, sand (glass, foundry & high purity quartz), clays (feldspar, kaolin, etc.), and many carbonaceous and sulfate minerals. The successes of these 50 years are largely due to ArrMaz's ability to tailor make the processing chemistries to fit the ever changing and declining mineral feed grade and variations in water quality (Moore, 2015; Moore, 2016). This technical knowledge of mineral processing is strongly complimented by the intimate service programs in place at many of the beneficiation plants."

Jan 1, 2018

By Peter G. Dunn

Geologic studies during development at Copper Flat were directed at acquiring the information necessary in evaluating a low-grade porphyry copper deposit. In addition to the geologic mapping and core-logging of a typical exploration project, these studies included the following : (1) careful checks on the sampling and assaying (2) selection of representative samples used to establish the recoverable amounts of precious metals in the ore (3) examination of underground workings driven to provide samples both for metallurgical testing and for assay comparisons (4) evaluation of plant site and waste dump areas as non-mineral, including a placer examination of the taillngs disposal area (5) location of an adequate water supply. All these investigations were carefully documented to provide the necessary data both for the engineering design and, more importantly, for the feasibility studies required for successfully financing the project.

Jan 1, 1981

By B. Barry, M. S. Klima

"Testing was conducted to evaluate the effects of hydroacoustic cavitation (HAC) treatment on two bituminous coal slurries and the subsequent separation of each slurry in a classifying hydrocyclone. HAC treatment was performed using a pilot-scale circuit fabricated by Furness-Newburge Inc. The circuit was designed to induce cavitation by means of flow through an ultrasonic resonator chamber or enhanced cavitation by initial flow through a cavitation chamber followed by flow through the ultrasonic chamber. The test materials were nominal -1,500-micron and -150-micron Illinois-basin bituminous coal slurries, which were obtained from an operating coal preparation facility. After 5 sec of HAC treatment, the median size of the -1,500-micron material was reduced, with ash values for certain size fractions decreasing more than 5 percent compared with untreated samples. Extending treatment time led to greater degradation of the +1,180-micron material and an increase in the -25-micron material, with ash reductions occurring for material in the -850+150-micron size range. Size degradation was less for the -150-micron material. Subsequent separation of the treated slurries was carried out in a hydrocyclone with diameter of 102 mm. HAC treatment led to a decrease in the ash value and an increase in the heating value of the underflow stream compared with the feed material. For example, the ash value was reduced by about 16 percent for the -1,500-micron material and 25 percent for the -150-micron material with heating value increases of 7 and 33 percent, respectively, after HAC treatment. Overall, HAC treatment appeared to have a slight effect on the size selectivity curves.IntroductionUltrasound in the range of 20 to 1,000 kHz, referred to as power ultrasound, consists of high energy waves that can create zones of compression and expansion when used to irradiate liquids (Frederick, 1965; Leighton, 1994; Mason and Lorimer, 1988). This action generates varying pressure regions leading to cavitation or the formation, growth and near-immediate collapse of microscopic voids or bubbles (Frederick 1965; Leighton 1994; Mason and Lorimer 1988). Collapse occurs when the bubble reaches critical size and cannot absorb additional sound field energy, and the critical size is governed by the ultrasound frequency (Shchukin et al., 2011)."

Jan 1, 2015

By Akram Marseet, Andrew J. Petruska, Rik Banerjee

Underground mine roof bolting is a crucial operation for miners’ safety and mine sustainability. Since roof bolting is a manual or human-supervised operation, miners’ safety is at risk due to dust or rock falls. Traditional machine learning algorithms have shown limitations to detecting drillable areas, mainly due to harsh lighting conditions. The authors propose an adaptive deep-learning framework for autonomous roof bolting. The proposed framework is based on implementing a binary semantic segmentation algorithm on color images to classify pixels that belong to rock from those that belong to non-rock. Significantly, the proposed framework implements deep learning semantic segmentation on images from traditional and neuromorphic vision sensors in underground mines. The performance of the proposed model shows an impressive accuracy level of at least 98% at a low number of training epochs with smooth learning curves. The high accuracy enables the implementation of autonomous roof bolting, greatly improving miners’ safety and operational efficiency while reducing human exposure to safety hazards. This research will advance the use of deep learning in mining automation and has the potential to revolutionize the traditional mining industry.

Feb 1, 2024

By Jr. Smith

Borates have been mined in the desert areas of California and Nevada for more than 100 years. To about 1890, playa surface mining provided the chief sources of boron minerals. Underground mining of colemanite and later of borax and kernite was predominate until about twenty years ago. Open pit mining of the large deposits of borax and kernite near Boron, California has been most significant for the past twenty years. Mining of colemanite in the Ryan, California area, near Death Valley, began in 1907. Following the discovery of the large deposits in the Boron area (about 1957), mining in the Death Valley area became nearly nonexistent. Only small tonnages were mined for special uses. Little mining was done in the Boraxo area near Ryan. The first claim was made in about 1915 In 1960 the area became the property of the Kern County Land Company, which was acquired by Tenneco Oil Company in 1967. In 1976 the various borate properties and claims in this region were acquired by American Borate Corporation. The open pit mine is now approximately 400 feet (121.9 m) deep, 3000 feet (914.4 m) long and 1000 feet (304.8 m) wide. The borates in the Boraxo pit consist primarily of three minerals. These are about 50% coiemanite (C2B6O11&apos; 5H2O), about 40% probertite (NaCaB5O9.5H2O), and 10% ulexite (NaCaBcO9.8H2O). The colemanite, along with boric acid and high-grade coiemanite ore from Turkey provide the only sodium-free borates for production of textile grade fiberglas. When heated to its decomposition temperature, colemanite decrepitates to a fine powder. This provides the basis for the concentration process. The gangue minerals in this deposit are primarily calcite and clays, including bentonite. The ore body has a very low arsenic content.which is a desirable feature. Test work had been done with samples prior to the results discussed herein. This paper will discuss results of test work which were the basis for erection of a plant, and the subsequent plant operations.

Jan 1, 1978

By Menglong Bian, Xiaotong Dong

Thermal damage is an urgent problem faced by deep mining. High-temperature rock mass, hot water and electromechanical equipment are the sources of the thermal damage. The increase in air temperature in mine tunnel is the result of fluid–solid coupling heat transfer from various heat sources. This paper takes a roadway with hot water and a mine car as the research object. Based on the Fluent, Static Structural and Steady-State Thermal modules in ANSYS, the thermal-fluid–structure coupling analysis in the roadway is carried out. It is found that the hot water has a significant effect on the thermal environment of the mine. Under the experimental parameters, the maximum heat flux density and equivalent elastic strain at the interface between the hot water and the rock are 9789.3 W/m2 and 0.00054532 m/m, respectively. The heat flux distribution in the rock area near the mine car does not change much, and the equivalent elastic strain value in this area is high. After the air is heated in the hot water area, the temperature curve changes gradually and then rises steadily. By changing the inlet air temperature parameter, it is found that the lower the inlet air temperature, the better the cooling effect, and the change of the inlet air temperature can change the air temperature field in the roadway as a whole. By changing the parameter of inlet air speed, it is found that higher wind speed brings better cooling effect, but with the increase in wind speed, the cooling effect of roadway thermal environment is very limited. When the wind speed increases from 5 m/s to 10 m/s, the air temperature of most measuring points drops by more than 2℃; when the wind speed increases from 15 m/s to 20 m/s, the air temperature of most measuring points drops below 0.7℃. After the wind speed reaches a certain value, the cooling effect of ventilation is very limited.

May 5, 2022