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By J. W. Mausteller

Chemical oxygen supplies have been used for nearly 60 years, with their greatest application during the last 25 years. They are of two types, the superoxides and chlorate "candles", The superoxides are demand chemicals, responding to the needs of the user and to supply oxygen and remove carbon dioxide. Chlorate candles are formed solid element which furnish oxygen only and do not remove carbon dioxide. Properties of these materials will be described, with comments on the respiratory requirements of a man under various workloads, types of equipment which use chemical oxygen, comparison with other systems and potential application to an underground mine survival system.

Jan 1, 1971

By Carl G. Hogberg

To the casual observer there is probably no simpler appearing operation in the mineral industry than a limestone quarry. It might seem that the entire operation - from the drilling, blasting, and loading of the stone, its transport to a mill for crushing, washing and sizing, to loading into boats, railroad cars, or trucks for delivery to customers - can be comprehended at a glance. But no first impression could be more misleading. It is one of the purposes of this presentation to sketch the broad outlines of the extensive limestone industry in the United States which, measured in terms of volume of production since the end of World War II, has grown almost 300 per cent to a national level in 1957 of 384 million net tons.1 Another objective will be to discuss in more detail this industry in the State of Michigan. For this latter purpose, the Michigan Limestone Division plants at Calcite and at Cedarville will be used as examples. These descriptions will, we believe, show that the limestone business has complexities to match its size.

Jan 1, 1962

By R. J. Mirville

Flocculation is an important step in the treatment of coal preparation waste waters. The effects of polymer charge and molecular weight and solution pH and ionic strength on the adsorption and flocculation characteristics of a series of polymeric flocculants on some typical waste water constituents have been studied experimentally. The results indicate that the nature and extent of flocculation are strongly system-dependent. For the case of coal, both adsorption and flocculation behavior can be correlated with the polymer conformation in solution. For the mineral constituents, on the other hand, adsorption and flocculation depend also on the surface properties of the solid.

Jan 1, 1979

By K. K. Kohli

Since the adoption of the Surface Mining Reclamation and Control Act of 1977, which mandates that surface subsidence be an intergral part of the underground coal mine design, there has been a sudden rise of demand on guidelines for minimizing surface subsidence and its associated structural damages. Unfortunately there is no sufficient amount of systematic subsidence data to fill such a gap, although considerable research has been devoted to the subsidence-induced damages of surface structures in the past. However, it was said that many surface subsidence surveys have been performed and monitored by coal companies during the past twenty years, and that it will be a great source of information for subsidence engineering design if they can be collected and assembled together. An effort was therefore initiated in the Department of Mining Engineering, West Virginia University, under contract with the U. S. Bureau of Mines in December 1978 to contact each individual coal company in the Northern Appalachian Coal Field for any surface subsidence survey data. After 10 months' survey, the data collected include 17 longwall panels and 2 room and pillar sections. The data in-each panel and section cover the complete set of subsidence survey raw data, underground mine layout maps, surface topo maps, geological loggings showing the stratigraphic sequences and thickness of the overburden, and if available, locations and types of surface structures. On-site visits were followed to study the surface terraines and structures. Interviews were conducted with the owners of the surface structures in most cases about, if any, the history and characteristics of damages.

Jan 1, 1980

By L. P. Johnson

Longwall mining has gained acceptance as a safe method of maintaining coal production where conventional systems were unsuccessful or uneconomic due to bad roof conditions (Kuti8). One of the major problems confronting American operators involves the correct choice of equipment which should be selected to suit the local mining and geologic conditions for optimum productivity. To achieve this, factors such as rock strengths, local geology, panel geometry, and panel orientation must be examined to optimize production and minimize down time due to ground control problems. Little quantitative information is available in the literature regarding the effects of geologic conditions on American longwall operations, and past implementations of longwall systems appear to have been based largely on experience. When mining engineers are able to assess the geologic conditions both quantitatively and qualitatively, they can more fully optimize equipment selection and panel design.

Jan 1, 1977

By L. S. Harris

The application of briquetting in various chemical, mineral, mining and metallurgical processes has been rapidly increasing in the past two decades. This is, in part, due to the development of new, more economical and higher performance briquetting equipment. Some of these developments, which have reduced the operating and maintenance costs,, include anti-friction bearings, hydraulically applied pressure enclosed and sealed gearing and bearings, tapered predensification feed screws, water cooling and materials of construction capable of operating at temperatures up to 18000F, and control systems capable of maintaining optimum briquette quality control. The briquets can be formed into almost any desired size and shape, To date, with present rotary briquetting presses in the 25 to 500 ton force range, briquets from 1/4" to 6" length are presently being used, some of which are illustrated in Figure No. 1. In force fed rotary briquet machines, these shapes are produced by feeding the material in between a pair of counter rotating rolls, as illustrated in Figure No. 2. The rolls have forming dies indented into their circumferential surface, as illustrated in Figure No. 3.

Jan 1, 1973

By J. Paraszczak

Metal mining at great depths presents a number of serious challenges for mine operators. Among them is the high demand for fresh air required to cool down mine openings, evacuate noxious gases and contaminants and provide sufficient amounts of oxygen for miners. At the same time, modern mechanized mines extensively use diesel-powered load-haul-dump (LHD) machines, trucks and other mobile equipment. These vehicles not only emit exhaust gases and diesel particulate matter (DPM), but constitute an additional source of heat. As mine regulations get steadily more stringent with regard to air quality, the use of diesel engines has an additional adverse impact on ventilation costs. In this context, the present paper examines possible alternatives for diesel power trains, both those commercially available and those in development. They are reviewed with regard to their principles, required infrastructure, stage of technology development and progress. The questions of their flexibility, practicality and economic viability are also addressed. Finally, their possible benefits and potential for implementation in the conditions of deep metal mines are discussed. The paper concludes with short- to medium-term predictions concerning promising drive alternatives for vehicles destined to operate in deep metal mines.

Jan 1, 2009

By A. Habibi

The ventilation survey was conducted in an underground longwall trona mine. The mine is relatively shallow and categorized as a gassy mine. The ventilation system consists of nine shafts (three intakes and six exhausts). Three surface based axial fans ventilate the mine configured in a blowing arrangement. Following the ventilation survey airflow quantity, frictional pressure losses and air psychrometric characteristics have been quantified. An accurate resistance survey has been conducted to calculate the pressure drop with regard to moving cages and skips in the shafts. This paper discusses the benefits of utilizing high accuracy digital pressure transducers and psychrometers in a ?leapfrogging? survey to gather data needed to build the computer ventilation model. Two underground booster fans with VFD are currently idle but available at the mine. The ventilation model has been used to determine the optimal booster fan locations to decrease the overall operating cost by reducing the load carried by the main fans. A leakage study has been conducted to evaluate the effects on the system of additional pressure from a booster fan. The study finally prepares a future ventilation model for the next fifteen years of mine operation and investigates the effect of proposed scenarios.

Feb 27, 2013

By Don Rose

INTRODUCTION A number of tunnels supported and permanently lined by steel-fiber-reinforced shotcrete (SFRS) have been built in North America in the 1980s. The material is more economical than, and technically equal or superior to, conventional shotcrete using wire mesh. The design and construction of SFRS-lined tunnels is straightforward, and only a few new design principles, laboratory tests or construction equipment modifications appear necessary in order to use this material. Modern tunnel Contractors may use cyclic drill-and-blast methods on some tunnels, with intermittent shotcreting as part of an orderly cycle. The Dry Mix method is most suitable for cyclic, intermittent, relatively small-scale shotcreting. However, modern Contractors excavating tunnels continuously using large long Tunnel Boring Machines (TBMs) or Roadheaders may prefer Wet Mix shotcreting on a mass production basis. In either case, the use of steel-fiber-rein¬forced shotcrete (SFRS) promotes the rapid and economical excavation of tunnels. The addition of microsilica will improve SFRS properties and reduce rebound, and is expected to become standard practice with SFRS in North America, as it now is in Scandinavia. HISTORICAL REVIEW Steel-fiber-reinforced shotcrete (SFRS) at the present time (1985) is essentially conventional shotcrete with straight or deformed steel fibers added, and in general SFRS for tunnel linings encounters the same problems that conventional shotcrete does. Shotcrete history is well known. The use of sprayed plaster on wire frames for mounting animal skins by Carl Akeley of the Smithsonian

Jan 1, 1985

By Robin J. Hickson

The Ortiz Mine is operated by Gold Fields Mining Corporation, a subsidiary of Consolidated Gold Fields Ltd., one of the world's major gold producers. The Ortiz Mine is Gold Fields only heap leaching facility as well as being their first operating mine in the U.S.A. The hydrometallurgical processes utilized for recovery of gold and silver at Ortiz are discussed along with the several practical changes in operation adopted since start-up. Included are heap leaching by cyanidation, concentration of values on activated carbon, desorption, and the final electrowinning steps prior to shipment. Construction costs and pertinent technical data are shown.

Jan 1, 1981

By Jürg Schlumpf

Concrete is one of the decisive construction materials, also for the AlpTransit Gotthard Tunnel. The client has many requirements, and many are the solution possibilities that concrete systems can offer. Cement producers and concrete admixture manufacturers have been challenged to design and test jointly concrete systems for cast and sprayed concrete. The testing operation followed the scenario laid out by the Gotthard AlpTransit Project management?s instructions ?Testing system for concrete mixes.? Various supplier teams have applied for the concrete systems for sections Amsteg/Erstfeld, section Sedrun and/or sections Bodio/Faido and have also followed through with the tests. As was to be expected, the rate of failed mixes matched the level of the requirements. Thanks to this system, it was nevertheless possible to test complete concrete systems for all sections and to get them approved. The joint ventures tendering for the contracts were allowed to include only approved mix designs in their bids. Workability and durability are of paramount importance for cast and sprayed concrete mixes. Durability is influenced by the chosen mix design where binder concept and well-defined water content, i.e., impermeability, are determinant. Aggregates for AlpTransit are to be considered as given. The concrete mix design also determines workability. Because ambient conditions and also requirements with respect to workability are subjected to change, it is necessary that the mix designs include control measures. The choice and number of components for the concrete systems (cement, additives and admixtures) allow adaptation to changing conditions. For AlpTransit such adaptive measures must meet very strict requirements.

Jan 1, 2008

By C. L. Lin

Linear grade distribution measurements determined from polished sections of randomly oriented particles can be used to estimate the extent of liberation for multiphase particles of specified size. Two techniques, optical image analysis and microprobe analysis, have been used to establish linear grade distributions. Both techniques were evaluated and compared using variable grade samples of products from a copper porphyry flotation circuit. The statistical significance of the linear grade distribution data obtained by optical image analysis was assessed. The average chalcopyrite content of these samples, as determined by chemical assay was used to estimate the variance of the experimental procedure. For a given accuracy, the number of particles required to obtain an unbiased representation of the sample was determined.

Jan 1, 1985

By E. Watkins, M. B. Daza

Although there have been great advances regarding the understanding of mine fires in underground mines in the last century, fires remain high risk incidents. During fire scenarios, many crucial decisions and actions can be made that greatly influence the outcomes of these scenarios. Underground worker decisions are mainly based on training and experience, which in some cases can be complemented with previous analysis of fire effects. In order to review the guidelines that should be taken into account for this kind of examination, a numerical analysis of effects produced by a shuttle car fire under five different ventilation conditions was carried out. The analysis provides some insightful recommendations for firefighting personnel such as time for direct attack and best attack position for first responders and fire brigade groups. Also, the most critical parameters for each scenario were determined. Finally, all results were systematically organized and a first approximation of a fire classification based on the tenability limits was provided for first responder and fire brigade groups. The methodology used in this study for the fire classification could allow for the most appropriate decisions by firefighting personnel increasing the probability to put fires out without compromising their health and safety. INTRODUCTION While there have been great advances regarding the causes of mine fires in underground mines in the last century “small fires have occurred and always will occur in underground mines” (Conti, Chasko, Wiehagen, & Lazzara, 2005). The response time and decisions made during an underground mine fire are critical elements that have direct influence on the event outcome. Mine fires can grow in size quickly causing catastrophic consequences, thus rapid and suitable response actions can result in the difference between an minor emergency situation and a disaster. Upon the confirmation of a fire, a decision must be made regarding whether to fight the fire or evacuate the mine. Even though all underground coal mines possess emergency response plans and firefighting personnel are highly trained, decisions can be complemented with previous numerical analyses. Such analyses could contribute with the knowledge of potential fire effects and consequently with fire preparedness in the mine. Preparedness in underground mines is an important element to reduce the probability of the negative consequences of a mine fire. The time elapsed between the detection of the fire and response in the early stage is a serious component since small fires can produce larger and more serious consequences. If a mine fire cannot be put out within the short time after discovery, the chance of getting the system back in balanced or the success of safely controlling and extinguishing a mine fire is reduced (Conti et al., 2005, Conti, Chasko, Wiehagen, & Lazzara, 2000, Trevits, Yuan, Teacoach, Valoski, & Urosek, 2009, Brake, 2013). As confirmed by Conti and others, if a mine fire cannot be controlled by direct firefighting methods the probability of extinguishing the fire, without sealing is greatly reduced (Conti et al., 2005). However, response actions such as direct extinguishment must be carried out without compromising the health and safety of the firefighting personnel (Kim, Lönnermark, & Ingason, 2010).

Jan 1, 2019

By P. O. Ripley

Into this tumultuous twentieth century, every second, two new babies are born. This is 5,412 per hour, and 130,000 per day. Relentlessly, consistently, alarmingly, they add to the more than three billion human beings who already inhabit the earth. Every tick of tier clock brings with it a problem child, the problem of another mouth to feed, another body to clothe, another human being for whom to provide. On the other hand, medical science has achieved a postponement of death, considerably past the period of a few years ago. Thus, life expectancy has been increased and world population has increased accordingly. Darwin (4) writing in 1962, suggests "It is curious how long the world is taking to perceive that we are living in what is a fantastically abnormal period of history, and one which must inevitably end soon, The first warning note of a possible population explosion was given by Malthus in 1799". He suggested that population increases geometrical while production increases only arithmetically and that soon we would not be able to feed the rapidly increasing population.

Jan 1, 1966

By S. Angioletti

This paper addresses strategic investment decisions when they are nested in a project development format where each project is implemented in phases and each phase is approved to move on to the next phase only if certain technical and economic requirements are met. This configuration is sometimes referred to as a ?Project Portfolio?. Mining companies maintain project portfolios in their exploration investment plan. This study proposes a procedure to best manage an exploration project portfolio including technical and economic uncertainties. The procedure may support decision makers in a simple and intuitive way, while maintaining the rigor and precision required by the rather large amount of financial resources typically called for by mining projects. The procedure was tested in a real case study of a gold mining company and its exploration projects portfolio. The procedure uses the following approaches: i) investment valuation methods under technical and market uncertainties based on Option Pricing Model, Real Option Theory and Option Space; ii) portfolio management and Stage Gate®1 method; iii) Monte Carlo simulation.

Jan 1, 2010

By Justin Srednicki, Chenming Zhou

Ambient electromagnetic (EM) noise (natural or manmade) is a major limiting factor for the design and operation of many electronic devices, including through-the-earth (TTE) communications and tracking systems. Extensive studies on EM noise were conducted by the US Bureau of Mines in the 1970s and 1980s. Changes in the design and operation of electrical equipment since then, however, have resulted in changes in the EM noise environment. This paper reviews past research on surveying EM noise in the extremely low-frequency (ELF) and very-low-frequency (VLF) bands, which are the operating bands for TTE systems, and introduces a new battery-powered, rugged, portable measurement system for surveying EM noise in mining environments. Examples of surveyed EM noise measurement results in and above an active underground coal mine, using the new system, are presented in terms of absolute magnetic field strength levels. A new metric, average noise level (ANL), is introduced to characterize the noise level relative to a particular frequency band for a specific location. It is found that EM noise in mining environments varies significantly with time and location. EM noise levels at frequencies of 30 Hz that shifted from power harmonics (e.g., 90, 150, 210, 270 Hz) are relatively low and their variation with time can be statistically modeled by a Gaussian distribution. The conclusions and findings presented in this paper can help better design and operate TTE communications and tracking systems in underground mines.

Oct 14, 2022

By Robert M. Lewis

Chemically, mica is a complex silicate of sodium, potassium and aluminum. There are no important uses of mica where the chemical analysis is important, except that in some uses of ground mica, the content of iron oxide present as an impurity must be kept to a very low limit. Muscovite mica is frequently found containing black and red "stain" as a homogeneous part of the books or sheets. In most cases this stain or impurity is magnetite or hematite. Some mica contains impurities deposited by infiltration. This is commonly a red stain, less often brown or white. The best mica is free from all such impurities, and the greater their content, the less value does the mica have.(1) It is because of these undesirable impurities that a large segment of the fine ground mica industry relies on weathered pegmatites and alaskite ores as a source of raw material. The mica concentrates obtained from these ores are relatively clean and require moderate beneficiation to meet color and density specifications. One need only to observe the stained and decrepitated condition of the mica recovered from mica schist to appreciate the challenge that processing this material presents. Despite these adversities there are several advantages to be gained by mining and processing mica schist ores. The mica content of these ores are considerably higher than the pegmatites and alaskite ores now being mined, often containing in excess of forty percent mica. This-higher grade mica feed should promote a lower mining and milling cost with its resulting competative advantage. With more rigid government

Jan 1, 1969

By G. A. Rosario, G. Peach

Twin 8.5 m diameter, 10 km long headrace tunnels under overburdens of up to 1870 m were excavated for the neelum jhelum hydroelectric project in north-eastern pakistan using two main beam gripper tunnel boring machines (tbms). Rock bursts were encountered and presented a significant danger to personnel and equipment. Micro seismic monitoring was installed to analyze rock burst characteristics and to create a database for future reference. Correlation of rock burst characteristics improved the ability to predict the likelihood, location, severity, and number of rock burst events. This paper presents the analysis of the micro seismic data

Dec 1, 2022

By R. Kealey, D. Huo, Q. Zhang, Y. A. Sari

Greenhouse gas (GHG) emissions from primary mineral and metal production account for ~10% of global GHG emissions. One of the main sources of GHG emissions in mining operations is fuel consumption by haul trucks. Given their size and carrying capacity, the fuel consumption of haul trucks can approach 250 liters per hour. An average of 30% of the idle time of the trucks is spent while waiting in the queue. Inefficient truck dispatch planning can waste resources, cause dilution and elevate GHG emissions. In this research, a machine learning based truck dispatch approach was developed to dynamically route the haul trucks based on the loaded material, the road traffic, the estimated wait time, and the maintenance needs of the trucks. The GHG reduction potential of this smart fleet management approach was estimated by calculating and comparing the related carbon emissions versus scenarios using traditional fleet allocation approaches. Results suggest that this dynamic fleet allocation approach can significantly reduce GHG emissions at mineral production sites by optimizing waiting times and the overall distance travelled while achieving the same production levels.

Mar 2, 2022

By KOKOWSKI J., RUDZIŃSKI Ł.

The LUMINEOS network was established in 2013 to monitor mining-induced seismicity in Legnica-Głogów Copper District (LGCD), located in south-western Poland. Since the starting time, the network was improved and today consists of 17 seismometers and 10 accelerometers. Up to now, the strongest recorded earthquake in the region had Mw4.0. Both raw seismic data and earthquakes catalog for events recorded by the LUMINEOS network are fully open and available on the EPISODES platform (https://tcs.ah-epos.eu/#episode:LGCD). During the last 7 years, the network improvements gave us a possibility to increase location accuracy for shallow mining events. This accuracy is influenced by factors such as the configuration of seismic stations, noise level at seismic stations, and the influence of the velocity model. Here we encountered two main issues which are worth to discuss. The first one is the low detection threshold of two seismic stations and their significant impact on the location errors. The second one is the large uncertainty in the S-wave picking. Even though S-waves are not so clearly visible on seismograms, they are very helpful in the estimation of source location and strength of seismic events in the region. In our work, we present the history of LUMINEOS network and corresponding improvement on location accuracy as well as the influence of noisy stations on the error distribution and how it is connected with location results. We also investigate the effect of the S-wave phases and how they are related to the accuracy of the earthquakes locations in the network.

Apr 26, 2022