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By Staff

The mineral sector is a fundamental part of the U.S. economy. It contributes to the real gross domestic product (GDP) at several stages—basic (mining), intermediate processing, manufacturing of finished goods and construction. The estimated growth rate for the real GDP of the United States for 2006 was 3.2 percent. The nominal GDP was about $13.2 trillion. The value of minerals mined in the United States in 2006 rose significantly because of increased unit price for some metals—particularly copper, zinc and other base metals. There was also a significant reduction in metals stocks. Infrastructure expansion and manufacturing in China and India have been absorbing a significant portion of world output. Domestic production increased for some industrial mineral materials, mainly cement and construction sand and gravel. Production of crushed stone declined less than 1 percent in 2006 compared

Jan 1, 2007

By J. Armstrong, J. Bourgeois, S. Warren

The application of statistical analysis software programs has proven useful for investigation of rockfall runout distance along a designed slope. Rockfall modeling programs are continually being upgraded with more sophisticated analysis tools, such as the use of the rigid body versus lump mass models. Engineers at mine sites utilizing the software may have varied experience related to these models, their associated input parameters, and how to interpret the generated results. To address this concern, researchers at the Spokane Mining Research Division (SMRD) of the U.S. National Institute for Occupational Safety and Health (NIOSH) investigated the influence of slope height, slope angle, slope material, and rock size for both rigid body and lump mass models in a 2-D statistical analysis program. Based on a literature search and industry input, specific ranges common to that of an open pit mining environment were chosen for each of the input parameters to determine 90% rock runout distance as well as their sensitivity to change. Data collected from this numerical analysis and simulation will be compared to empirical rockfall data gathered through the duration of the Highwall Safety project conducted by NIOSH from 2022–2026.

Mar 2, 2022

By Andy Davis

The evolution of pit lake water quality depends on the lithology and hydrologic characteristics of the ultimate pit surface, the availability of buffering capacity in the wall rock vs. oxidizable sulfide content, the alkalinity of recharging groundwater and the evapoconcentrative characteristics of the system. This paper assesses the geochemistry of 11 existing pit lakes, ranging from the acid Red Hill and Berkeley pit lakes (pH 2.6 to 2.8) to the alkaline Yerington pit lake (pH 8.45). Predicted pit lake chemistry is similar to that in existing pits, with long-term chemistry lying on a geochemical continuum between end members that consist of influent calcium bicarbonate groundwater and naturally occurring sulfate-rich evaporate playa lakes.

Jan 1, 1997

By A. Yadav, B. Behera, G. S. P. Singh

The size of chain pillars in the Indian geo-mining conditions is primarily decided in accordance with the regulatory provisions. These provisions are of little help for deep longwall workings, exceeding the cover depth of 360 m. Furthermore, these provisions are primarily meant to support pillars in bord and pillar workings. They may not be suitable for the chain pillars owing to a significant difference in layouts and functional requirements. Hence, it is imperative to develop a method to evaluate the stability of the chain pillar considering the complex loading and geo-mining conditions. To this end, a machine learning-based model was developed in this study to assess the stability of the chain pillars under high depth of cover considering the field-representative conditions. The data for this work was generated by conducting a parametric study using a field-validated numerical model. The strength and deformability parameters of the caved, fractured, and continuous deformation zones were established by calibrating the numerical model outcomes against the site-specific field observations. The developed ML model was used to evaluate the influence of pillar width, pillar height, cover depth, abutment angle, face length, coal strength, moduli ratio of the roof and floor strata to the coal seam, and the elastic modulus and unit weight of the overburden on the chain pillar stability. An interesting finding of this study showed that the factor of safety of the chain pillar increased with the increasing abutment angle, which may be indicative of the confining effect of the abutment angle on the pillar. Eventually, the ML model was verified by comparing its outcomes with the calibrated numerical model for a typical longwall working from Indian geo-mining conditions.

Oct 18, 2023

By Paul Soros

Lord Robens, Chairman of the National Coal Board of England announced recently to the world press plans for construction of the largest bulk terminal in Western Europe. This should result in annual freight savings of 22.4 million dollars and between 150 and 190 million dollars of new export business. These are rather substantial amounts for any mining enterprise. Or to put it another way, opportunities to make substantial savings in the delivered price of a highly competitive commodity such as coal are few and far between. One area where such opportunities still exist is in the economical; movement of bulk materials between producer and consumer.

Jan 1, 1966

By A. W. Khair

In 1985, an extensive longwall mining research project was initiated by the West Virginia University Research Center entitled "An Improved Longwall Mining Technique" with the purpose of providing operational guidelines for the mining industry to enable efficient operation of its existing and projected longwall installations. One task involved in this extensive research project was monitoring ground movements due to longwall mining and evaluating their impact on surface and subsurface structures. This paper presents an analysis of the effects of topography on quasi-static and dynamic ground movements and the severity of damage inflicted on surface structures. The site was chosen for the study with an attempt to obtain a representative account of the topography experienced in the Northern Appalachian region, and more importantly to contain a substantial number of varying topographical features i.e., mountains, hillsides, valleys, and flat bottom land. The study was made possible by typical subsidence monitoring technqiues, however subsidence monuments were surveyed on a frequent basis, intermittently during face advancement. Ground movements were investigated under both quasi-static and dynamic conditions. This provided insight into the propagation of subsidence and the dynamic affects it has upon surface structures.

Jan 1, 1987

By D. C. Torre

The need for a successful, efficient and reliable continuous face- haulage .system for use with continuous mining machines has been apparent since the first continuous miners were introduced some twenty-five years ago. Some thought and effort were given to the development of continuous haulage over the last twenty years or so. Some initial success was experienced in this area by The Long Company with a system involving bridge conveyors, as far back as the late 1950's. However, extensive success with continuous face haulage for use behind modern, high product¬ion, continuous miners escaped the industry until the early 1970's. It is true that continuous face haulage was successfully introduced into low seam mining, generally in seams ranging under 1.07 m (42") in height, in the 1960's, for use with relatively low production, low seam, auger type continuous miners. However, those available systems which have achieved success in the lower seams, where relatively low capacities are adequate, are not directly applicable for use with today's medium and high seam miners with their standard production capacity of 9.1 - 10.9 mtpm (10 - 12 tpm). Since the late 1960's and early 1970's, several machinery manufacturers, and at least two major coal companies, have devoted considerable expense, time and effort to developing truly successful continuous face haulage for use in coal seams ranging upward from 1.2 m (4') in height. Continuous face haulage equipment has been developed in the last five years employing a variety of transportation media and design concepts, including some which have received wide publicity such as those employing hydraulics, and pleated belt. The truth of the matter is, however, that the only universally applicable and widely successful continuous face haulage equipment introduced to date has been that employing a combination of bridge conveyors and mobile, self-propelled, bridge carriers, connected at the inby end to the tail of the high production continuous miner, and at the outby end attached directly to the panel conveyor (Fig. 1 & Fig. 2) or, on occasion, to a short, self-contained conveyor which, in turn, empties directly onto the panel conveyor. While these bridge type continuous haulage systems are available with both belt and chain conveyor components, the most widely applied and successful system in seams above 1.07 m (42") in height is that offered by The Long-Airdox Company. The standard unit for use with 9.1 - 10.9 mtpm (10 - 12 tpm) continuous miners is normally equipped with belt. However, they have built, and successfully applied, versions of this system employing chain conveyors, (Fig. 3), mainly for operators having extremely difficult mining conditions, including excessive amounts of water

Jan 1, 1977

By Pier Francesco Paglini, Gian Luca Menchini, Pier Francesco Boschi

"PROJECTThe “Caltanissetta” Tunnel is part of the ANAS S.p.A (National Autonomous Roads Corporation) $ 1.3 Billion Highway 640 Caltanissetta-Agrigento (Sicily, Italy) Rehabilitation Project, consisting in upgrading of 62 km (40 miles) of highway. The Italian multinational construction company Cooperativa Muratori & Cementisti di Ravenna, is the General Contractor for the design and build contract. The highway S.S. 640 starts from Porto Empedocle, to the intersection with the Motorway A 19 Catania-Palermo.The entire project, double carriageway designed for speed 70-120 km/h and maximum longitudinal slope of 4.2%, is divided into two sections. First Section: just finished and opened to traffic. Second Section: mainly involving the province of Caltanissetta, length about 28 km (18 miles), works started in 2013. This second section includes the most challenging work of all the project, the “Caltanissetta” tunnel consisting of two separate tubes, each with 3.9 km length and inside diameter of 13.50 m, in order to host 2 traffic lines and an emergency line. HORIZONTAL AND VERTICAL ALIGNMENT - GEOLOGY AND HYDROGEOLOGYThe plan alignment of “Caltanissetta” tunnel is formed by two tubes which are located at a minimum mutual distance of 22 m to a maximum of 63 m, with n. 9 pedestrian and n. 4 road cross passages; ventilation shafts are not provided. Overburden over portals area is about 5 m till a maximum of 120 m. Tunnel sections have variable longitudinal slope from 2.6% to 0.5%, transversal slope of about 3.5%. Right tube length is 3,992 m, left tube length is 3,877 m."

Jan 1, 2016

By Michael J. Rinker, P. A. Tibble, M. Wiseman, R. V. Nicholson

Tailings, from an active copper-zinc operation, containing about 10% sulphur were investigated to assess the onset of acid production and potential lime requirements for treatment of drainage. Oxygen consumption rates were measured over two years to verify spatial and seasonal variations in sulphide oxidation rates. Shallow cores were collected to assess the quality of tailings porewater and to characterize solids that had been subjected to oxidation and depletion of neutralization potential (NP) for several years. Oxygen consumption data were used to quantify rates of NP depletion and onset of acid drainage from the near- surface tailings. Based on measured oxygen consumption rates and identification of NP remaining in the tailings, future lime use in the treatment plant was expected to rise significantly without mitigation. Geochemical modeling calculations were calibrated with observed oxygen consumption rates and the model results agreed well with actual lime use in the waste water treatment plant during operations. The modeling also demonstrated the benefits of lower lime demands and treatment costs after closure as a result of construction a soil cover on the acid generating tailings.

Jan 1, 2000

By A. M. Gaudin

In the first place, let me thank you for inviting me to appear before you today to speak to you on "Mineral Industry Problems - Present and Future". It is a distinguished honor for me to have this opportunity, and I am highly appreciative of this distinction. The beautiful surroundings of Gatlinburg and the pleasantness of a summer occasion are a wonderful tonic for all of us, yet they should not blind us to the seriousness of our Industry's problems No doubt, because of my past appearances before members of the Society of Mining Engineers, at which I discussed wholly scientific topics, or research in the Applied Sciences, you may be expecting me to revert to these subjects. But I intend to venture in a field that is new to me, yet old to all of us, the field of Economics.

Jan 1, 1962

By Peter Haller

Introduction The impact of the Comprehensive Environmental Response, Compensation, and Liability Act, or Superfund, as well as the Resource Conservation and Recovery Act (RCRA) and their state counterparts underscore the intention of the nation's lawmakers to reduce the risk from hazardous substance to American society. The promises and requirements embodied in these laws, together with their prospects for liability, will continue to have a very substantial impact on decision making in the mining industry. These laws present the prospects for staggering liabilities, often of an unquantifiable nature in terms of time and amount. It is therefore necessary to keep them in clear focus. This is particularly true in light of President Reagan's signing into law the Superfund amendments on Oct. 17, 1986, and in light of the Environmental Protection Agency's (EPA) major policy pronouncement of July 3, 1986, regarding solid wastes from extraction of ores and minerals. This article examines the general trends as well as the specific provisions of these laws in an effort to assess the prospects of liability for the mining industry of releases of hazardous substances into the environment. Hazardous substances vs. hazardous wastes The distinction between the terms "hazardous substances" and "hazardous wastes" is important to appreciate for the purposes of assessing the potential for liability for a mining operation. Hazardous substance is a term that appears in and is defined in the Superfund Act. In Superfund, it is defined by reference to other substances that have been declared to be hazardous under other federal environmental statutes, such as RCRA, the Clean Air Act, and the Clean Water Act. Hazardous waste is a term that is less all-encompassing than hazardous substance, as that term is defined by RCRA. Hazardous substances do not need to be wastes to be considered hazardous for the purpose of Superfund liability. A "release" of a hazardous substance into the environment can bring about potential liability under Superfund. Many mining wastes, even though they are not considered hazardous wastes by EPA under RCRA, have been determined by that agency to be capable of bringing about liability under Superfund if they contain chemical substances, such as the heavy metals copper, lead, mercury, zinc, silver, and others. Therefore, it is not sufficient for the mining industry to be able to answer whether one has hazardous waste at a mining site. That question only goes partway in addressing the potential for liability. The next question is, do one's solid or liquid mining wastes contain hazardous substances that could bring about liability under Superfund? Superfund 1980 law: A review Some provisions of Superfund as it existed before its recent amendments must be considered. The law provides that the owners and operators of mining sites, together with those who transport hazardous substances to such sites, can be held jointly and severally liable for the cost of cleaning up the site. The concept of joint and several liability means that one party, as among many, can be held totally responsible for the costs of cleanup. This is particularly true where the harm done by many parties to the envi-

Jan 2, 1987

By William J. Almas

Operating uranium mill tailings containment and mill decommissioning activities are regulated by the Nuclear Regulatory Commission (NRC) and the Environmental Protection Agency (EPA) through numerous regulatory mechanisms. Reduction of radon emissions from tailings disposal areas, remedial actions to return groundwater to baseline constituent concentrations, and 200-to 1,000-year stabilization of tailings are major focus areas of regulation. The cumulative economic impact and uncertainty associated with regulation are very significant and will hinder future development of uranium milling facilities.

Jan 1, 1991

By P. M. Hawley

In April 1975 Kaiser Steel Corporation and the United States' Department of Energy entered into a cost-sharing agreement for the demonstration of shield-type longwall supports on three consecutive longwall panels at Kaiser's York Canyon' Mine in New Mexico. Under this agreement the Department of Energy supplied 117 Hemscheidt 320 HSL caliper-type shield supports and hydraulic pumps for the duration of the demonstration. The purpose of the demonstration was to educate the U.S. coal mining industry as to the benefits in production, productivity, health and safety, and increased coal extraction afforded by shield-type longwall mining systems and to provide the industry with a working model. A detailed description of this demonstration is given in U.S. Department of Energy Publication No. DOE/ET/12530-T1, entitled "Demonstration of Shield-Type Longwall Supports at York Canyon Mine of Kaiser Steel Corporation," hereafter referred to as the York Canyon Report.

Jan 1, 1984

By E. R. Bauer

The ground control aspects and occupational safety concerns of extended depth-of-cut mining are presented in this U.S. Bureau of Mines (USBM) report. The scope of extended cut use and typical face operations while extracting extended cuts is reported. A comparative review of roof fall fatalities and a statistical analysis of accidents and injuries for both extended and nonextended cut mining is included. The views and opinions on extended cutting from a series of interviews with mine workers in five states are summarized. In addition, some of the problems and safety concerns of this extraction system are mentioned.

Jan 1, 1995

By W. M. Cross

The use of fillers and reinforcements for plastics has increased considerably over the past few decades. For example, in the 1980's the average growth rate of filler use was 5.8%. [Katz and Milewski, 1987] Similar filler use growth rates occurred in the 1970's due largely to the increase in price of petrochemical starting materials for plastics. While filler use is still sometimes predicated on the cost benefits associated with their addition to the plastic, other mechanical and performance advantages associated with filler addition are being realized, and account for most of the increased usage. Plastic filler types are many and varied, and include both inorganic minerals/metals and organic compounds, with the former type being, by far, the more common. Common mineral fillers include oxides, including both natural and synthetic silica; carbonates, particularly calcium carbonate; clays such as kaolin; and silicates like mica and talc. It has been recognized that a number of factors influence filler performance, including particle size, shape, surface area, and hardness to name a few. In addition, the interaction between the filler and the plastic is of paramount importance as this interaction will determine the wettability, bonding and the adhesion between the two materials, and ultimately, the mechanical properties of the composite. Froth flotation has long been recognized as a viable process to separate different mineral types. [Leja, 1982] Prior to flotation the minerals are liberated from the ore by comminution. The mineral particle size range produced by this comminution process is typically between 300 and 10 microns. This size range is also typical of mineral fillers for plastics. The size similarity between mineral fillers and minerals concentrated by froth flotation is only one of many similarities that can be found.

Jan 1, 1997

Kidd Mine in Northern Ontario is now producing from Stage 1 of the Mine D expansion project ? mining between 2100 m and 2700 m below surface. Planning for Stage 2 of the Mine D project is already well advanced and will see the mine extended potentially to 3100 m below the surface. To ensure adequate ventilation is maintained at such depths, two large axial fans have been installed on the 6000 Level (1800 m below surface) as exhaust booster fans to operate in series with the surface exhaust fans. The Kidd Mine 6000 Level Booster Fans are a unique installation with unique and often unexpected challenges. These challenges have been met and attacked through the combined efforts of mine and fan manufacturer personnel with a common focus.

Jan 1, 2009

By William J. Wiehagen

The training of mining personnel is a large and continuing activity for the mineral industries. Although safety and skills training has long been recognized as an essential element for reducing injuries and improving productivity, the research literature lacks definitive reports documenting the specific value of such training. The training literature presents a variety of testimonials as to the "benefits of training," but lacks data that specifically tie that training to the performance of the worker.

Jan 1, 1983

By Zach Ahinga, Mike McRae, Dave Hopkins, Steve Klein

The San Vicente Pipeline project involves the construction of an 8-1/2 foot diameter water pipeline in an 11 mile long tunnel in San Diego, California. The tunnel will be excavated in extremely variable geologic conditions consisting of strong granitic and metamorphic rocks, weak sedimentary rocks, abrasive conglomerates, and mixed face conditions. This paper discusses the challenging geologic conditions and some of the key design evaluations for the project. Currently design work for the project has been completed and construction will be underway by mid-2005.

Jan 1, 2005

By A. J. S. Spearing, T. Kostecki, D. Benton

The use of paste backfill in room-and-pillar coal mines in the United States needs to be fully investigated. This paper discusses a series of physical tests that were conducted to examine the support benefits of theoretical paste backfill regimens in Illinois Basin room-and-pillar coal mines, which necessarily included consideration of weak floor conditions. The series of tests included those simulating strong floor conditions, weak floor conditions, under-confined scenarios, and testing of actual coal-based paste backfill samples. The testing indicated that a paste backfill regimen utilizing a minimum backfill strength of 22 psi at a minimum fill height of 50% of pillar height could significantly increase the longterm stability of coal pillars in the Illinois Basin. Considering typical coal wash plant recoveries, 50% fill would be feasible.

Jan 1, 2014

By Éder Domingos Oliveira, Carlos Antonio Morais, Ruberlan Gomes Silva

The objective of this study is to assess the impact of different reagents, such as limestone, lime, magnesium oxide, and sodium hydroxide, in experiments carried out in the single purification step and in two consecutive purification steps by raising the pH of a rare earth sulfuric liquor with the aim to remove or reduce the impurity concentrations in the rare earth sulfuric liquor. The choice for the best purification condition was made based on the minimum loss of rare earth elements (REEs), reagent consumption, and residue generation. The exploratory experiments show that it takes place in the two consecutive purification steps, the first one consists in dosing the limestone pulp until it reaches a pH of 3.5 followed by an addition of a lime pulp reaching a pH of 5.0. Under this condition, the results were a total removal of Fe3+, PO4 3− , and Th4+ ions and a reduction of 99%, 87%, and 37% w/w in the Al3+, UO2 2+, and SO4 2− concentrations, respectively, in the purified rare earth liquor. Furthermore, the lowest REE losses (8.3% w/w) and reagent consumption (4.3 kg/m3 ) and also a low residue generation (7.5 kg/m3 ) were observed in this condition. Despite reaching similar results regarding impurity removal, the experiments done with the addition of limestone, lime, magnesium oxide pulps, and sodium hydroxide solution in the single purification step, where the pH was raised to 5.0, presented higher REE losses (64.9%, 42.5%, 44.8%, and 60.9% w/w, respectively) and a higher residue generation (43.2, 25.1, 11.1, and 13.6 kg/m3 , respectively). This occurred due to the co-precipitation of salts containing rare earth elements in their composition. The experiments conducted with limestone, lime, and MgO resulted in a higher consumption of reagents, while the same result was observed when NaOH was used (4.3 kg/m3 ). In the experiments carried out with the addition of magnesium oxide and sodium hydroxide, the respective purified rare earth liquors presented a high concentration of magnesium, sulfate, or sodium, which could impact the quality of the marketable rare earth salts, whereas the salts obtained under the best condition observed in this study seem to be amenable for use as raw material in an attempt to obtain rare earth products with an acceptable chemical quality.