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By Thomas E. Browne

The Electric Power Research Institute Energy Supply Program is developing coal supply forecasts. By coal supply forecasts I mean the future relationships between coal price and production levels. A representative supply curve is shown in Figure l. It will make the rest of my presentation clearer if at this point I give you some background about EPRI and the Energy Supply Program. EPRI is funded by the nation's electric utility industry to develop new technologies for the production and conservation of electricity. Most of the research is conducted by outside contractors. We participate in joint projects with the Department of Energy and other organizations. The Energy Supply Program is one of three "economic" programs. The other two are Energy Demand and Conservation, and Systems. The Systems Program's main function is to provide the means to integrate the output of the other two Programs. The primary function of the "economic" programs is to provide information pertaining to future energy prices, availability, requirements, etc. to the EPRI personnel planning R&D programs. A secondary role that is becoming more and more important is providing information of direct use to the electric utility industry. I should note that the results of all EPRI's contract work are available to the general public. A "Coal Supply Analysis System" is being developed for EPRI by Charles River Associates. To the extent possible it will draw upon existing work, but much additional work needs to be done in the area of coal supply economics.

Jan 1, 1977

By R. Schuerch, C. Cimiotti, M. Piemontese, N. Karlin, P. Perazzelli, P. Halton

The new Los Angeles, California JWPCP effluent outfall tunnel will transport secondary-treated effluent from the Joint Water Pollution Control Plant in Carson to White Point Manifold. The tunnel will be approximately 7 miles (11 km) long with a finished internal diameter of 18 ft (5.5 m). The TBM is designed to cope with high water pressure up to 10 bar. The geotechnical challenges are due to the heterogeneous subsurface conditions: in the first half of the alignment, the tunnel runs through soils with a low overburden under urban areas, and, in the second half, the tunnel runs through extremely weak, intensely faulted rock masses with high overburden. Following an overview of the project, this paper focuses on the northern portion of the alignment and presents a decision-making procedure developed during pre-excavation phase in order to cope with the expected heterogeneous conditions during mining. The risk assessment and the TBM operational design of the southern portion will be dealt with in a future paper.

Jun 13, 2023

By Hazal Melis Aytac, Lana Alagha, Fardis Nakhaei

Gallium (Ga) and Germanium (Ge) are essential strategic elements that are extensively used as semiconductors in many technological fields. Owing to their essential uses and supply disruption, Ga and Ge are deemed critical by the U.S. They are typically found as substitutions or inclusions in zinc minerals. However, their distributions within zinc minerals are not well understood. To address this, trace element and mineralogy analyses of representative samples obtained from an old high-zinc-grade tailing were performed using various qualitative and quantitative techniques. These techniques included Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Tescan Integrated Mineralogical Analysis (TIMA) with Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Moreover, bench-scale froth flotation tests were conducted to enrich zinc minerals, the major hosts of Ga and Ge, using PAX as a collector, Na2S as a sulfidizer, Pb(NO3)2 as an activator, and MIBC as a frother. Comprehensive characterization analyses of the flotation products showed significant enrichment of Zn, Ga and Ge in the flotation concentrates.

Feb 1, 2025

In west-central England, 183 m (600 ft) below the Cheshire Plain, lie the evaporate remains of an ancient sea. Stratified into nine beds of salt separated by marl bands, the deposit stretches roughly 21 x 12 km (13 x 7.5 miles) and contains reserves of rock salt estimated as high as 400 Gt (440 billion st). The Winsford Salt Works, one of England's largest underground mines, extracts the Cheshire salt and sells it for use as animal feed, for application in de-icing programs, and as a key ingredient in sodium fertilizer production and a variety of other industrial processes. Because road de-icing is an important market, demand for Winsford's salt varies with the severity of British winters. Design capacity is 2.25 Mt/a (2.5 million/year). However, production peaked at 2 Mt (2.2 million st) in 1987. Over the past five years, annual production has averaged 1.6 Mt (1.7 million st). Run-of-mine salt averages 92.5% NaCl, mixed with about 5% marl. The marl was formed by deposition of a reddish dust blown into the Cheshire basin from deserts in what is now central Europe. Association with the marl adds color to the salt, producing tea-colored crystals that resemble unrefined sugar. Adaptation of coal mining systems Rock salt mining in the Winsford district began at least as early as 1682. Mining at the current site dates from 1844 but was shut down from 1892 to 1928. In the early 1900s, a series of catastrophic collapses and floods plagued and ultimately shut down then-active Cheshire brine-salt producers. Subsequently, Winsford reopened and began adapting mechanized underground coal mining systems to rock salt extraction.

Jan 1, 1992

By Robert D. Gibson, E. Donald McKay, Paul B. DuMontelle

Subsidence of the land surface in some parts of Illinois is caused by underground coal mining. The U.S. Bureau of Mines is backfilling abandoned mines at selected sites in southwestern Illinois in an attempt to support failing mine openings. The Illinois State Geological Survey assists the Bureau by developing geologic and engineering information. As part of this investigation, television probes of fifteen injection borings in Belleville augmented conventional methods of study. The television probes of uncased sections of borings revealed several phenomena. Water erosion caused shale beds to slough, which partially filled some borings. Fractures caused by subsidence were identified, and excellent views of underground mine workings provided documentation of the mining method. The condition of mine timber was evaluated. Pack walls supported some openings. Both floor heave and roof fall were observed to be causes of failure in the mines.

Jan 1, 1982

By Irwin R. Higgins, Joseph C. Milbourne

The selection of a suitable nitrate removal process depends on a variety of site-specific chemical and environmental issues. The dominant technologies for nitrate removal include biological denitrification and continuous countercurrent ion exchange. The decision to apply either of these technologies, or both together, depends on the nature of the waste water to be treated. Factors that affect the selection of the biological system include the feed composition and feed temperature. Ion exchange nitrate removal systems ere less sensitive to the feed composition but require disposal or destruction of the concentrated pregnant eluate. The paper discusses Tetra's continuous countercurrent ion exchange technology (CCIX™) and fixed film biological reactor, Denite®. The treatment of the ion exchange pregnant eluant is also discussed.

Jan 1, 1995

By Sharon Thomson

Since 1977, Amax Coal Co.'s Belle Ayr mine near Gillette, WY, has been the largest producing coal mine in the US. In its 10 years of operation more than 90 Mt (100 million st) of coal have been shipped from the mine's facilities to electric generating plants across the country. It is thought to be the largest amount ever produced in US history from a single coal mine. The railroad is Belle Ayr's lifeline for moving this massive volume from a relatively isolated corner of northeastern Wyoming. There are no waterways for barge traffic, and highway truck hauling would be impractical considering the quantity and distance of coal to be moved. Transportation in the Powder River Basin-at least for the present-is strictly unit trains. An average of four unit trains daily load at Belle Ayr. These trains average 108 cars long, with a capacity of 91 t (100 st) per car. Burlington Northern Railroad serves the Powder River Basin, but locomotives supplied by Union Pacific, Milwaukee Road, and Kansas City Southern are a common site as well, since coal will often travel these lines too on its way to utility plants in Colorado, Kansas, Iowa, Texas, Arkansas, Louisiana, Wisconsin, and Oregon. When Belle Ayr opened transportation in the Powder River Basin was in an early development stage. As the first large-scale coal shipper in the area, Belle Ayr was the only user of a 27-km (17-mile) railroad spur south of Gillette. Other mines, however, were to open soon on the abundant, low-sulfur reserves. Today, less than a decade after Belle Ayr's debut, 13 large-capacity mines operate near Gillette. The 27-km (17-mile) spur that once served only Belle Ayr has been extended 177 km (110 miles) south to service other mines as well, and to tie into a major rail line in central Wyoming. The Powder River Basin is now served by a wishbone-shaped track configuration that allows train movement north into Montana, south into Colorado, and east into Nebraska for connections across the country. Operations at Belle Ayr are closely tied to train arrivals and departures, with coordination essential between mine operations and rail personnel. "Train movement in the Powder River Basin has evolved to the point where we are fine-tuning mining operations to coordinate them with a more dependable transportation system," according to Joe Jefferson, transportation supervisor with Amax Coal's western division. That, however, hasn't always

Jan 10, 1982

By M. Hepokoski, M. Klein

"Mine refuge shelters are designed to protect mine workers from hazardous environmental conditions after a mine disaster, but high temperature and humidity levels inside these shelters may pose a significant safety risk. Due to the safety risks associated with human testing, detailed thermal models of shelters and human occupants have been developed using TAITherm simulation software. These models are used to predict the temperature and humidity within the shelter resulting from metabolic heating, evaporation due to sweat and respiration, moisture and heat from the shelter’s carbon dioxide scrubbing system, and heat transfer within the shelter. A detailed human thermoregulation model simulates the sensible and latent heat generated by the shelter occupants, and predicts the occupant’s body core temperature and moisture lost due to sweating and respiration. This information is used to assess the safety of the shelter. In this paper we will review technical details of the human thermal model, validation comparing the human model to human subject test data, and results of a mine shelter analysis. INTRODUCTION Portable mine refuge chambers are used in US coal mines to provide protection to mine workers from hazardous conditions following a traumatic event. Although these shelters are designed to supply clean air and sustenance for up to 96 hours, prolonged exposure to the mine shelter environment itself can pose a substantial risk to human safety. Heat generated by the shelter occupants combined with heat from the carbon dioxide (CO2) scrubbing system can raise the shelter interior temperatures and relative humidity to dangerous levels that can lead to heat stress in humans. Unfortunately, the thermal burden associated with mine shelter exposure is not well characterized due to potential hazards associated with underground human subject testing. In order to assess the thermal burden on people within a mine shelter environment, a detailed thermal model was created to accurately predict the temperatures and humidity within the shelter, as well as the impact of these environmental conditions on human occupants. The model consists of a mobile inflatable tent-type mine shelter, 23 humans, and also includes the surrounding mine environment. The thermal simulations were performed using ThermoAnalytics' validated commercial heat transfer prediction code, TAITherm (v12.0). Additionally, TAITherm's Human Thermal Module (HTM) provided the capability to simultaneously model the thermo-physiology of 23 unique humans contained within the mine shelter. The human thermal models accounted for the thermal interaction with the environment and also provided a core temperature response prediction, which can be used to evaluate survivability in heat stress situations [1]."

Jan 1, 2016

By A. E. Michon

My comments today are directed toward western coal and its impact on Burlington Northern. I will be discussing three major topics. These are: location and extent of mining activities, the flows of this coal traffic into the various market territories, and finally the interaction of this western coal with coals found in the balance of the United States. When we at BN speak of western coal, we refer to those substantial deposits lying in southeastern Montana and north-eastern Wyoming. This territory covers many different coal formations. For the sake of simplicity, I will be referring to this general area as the Powder River Basin (or the "western" coal fields). This slide highlights the area overlayed by a map of the BN rail system. The U.S. Bureau of Mines estimates the demonstrated reserve base of Montana and Wyoming to be approximately 176 billion tons. Of this figure, about 73 billion tons is minable by surface methods. This is roughly 72% of the total strippable reserves in the western united states, BN does not have sole access to this coal for there are deposits in southern Wyoming near the union pacific railroad. I will say more about this later.

Jan 1, 1978

By W. de Moura, R. Fueyo, M. M. Botz, J. C. Scola

The Cerro Vanguardia mine is an AngloGold Limited operation in southern Argentina that includes multiple open pits and a hybrid Merrill-Crowe and CIL circuit to recover gold and silver from oxide ore. Operations were commissioned at the site in 1998, which included a plant in the metallurgical circuit to recover cyanide from mill tailings. The cyanide recovery plant was initially configured to process tailings slurry and achieved greater than 90% cyanide recovery from tailings containing about 600 to 800 mg/L WAD cyanide (as CN). The cyanide recovery circuit was operated in this manner for approximately eight months, during which time the consumption of sulphuric acid and sodium hydroxide was relatively high, leading to high rates of scale formation in the acidification tank and stripping towers. In July 1999, several piping changes were made in the cyanide recovery system to permit its operation with clear solution, which reduced the sulphuric acid consumption and eliminated scale formation in process equipment. The cyanide recovery system currently operates with a two-stage counter-current decantation (CCD) circuit which provides clear solution for processing in the cyanide recovery plant. The cyanide recovery efficiency now averages about 90% to 92% from solution containing about 350 mg/L WAD cyanide (as CN). Recovered sodium cyanide now accounts for about two-thirds of the total cyanide added to the leaching circuit. This paper presents a description of the cyanide recovery plant and details regarding its current operating efficiency.

Jan 1, 2004

By James E. Brewer

Procedure for approval by the U. S. Army Corps of Engineers of a new source of aggregate is in three phases. Phase 1 consists of an investigation of a quarry or proposed quarry by district geologist and laboratory geologist and/or petrographer. The quarry face or suitable outcrop is logged in detail or, if exposures are poor, cores may be taken to determine whether further investigations are warranted. Phase 2 consists of thorough laboratory testing. Cores and crushed material are subjected to a number of acceptance and quality tests for soundness, absorption, abrasion, reactivity, and other properties. Petrographic analysis is also made. Phase 3 is a physical and economic study of the site and involves determining quantity of stone avail- available, amount-and character of overburden, condition of haul roads and distance to rail shipping point, plant flow sheets and capacity, aggregate sizes produced, and approximate price of material at plant.

Jan 1, 1966

By Paul C. Miclea

Hanford Reservation, in the State of Washington, with its deep basalt formations, is one of the three sites recommended by the Department of Energy for detailed investigations in order to select the first nuclear waste repository in the United States. Information obtained from several deep bore-holes drilled at Hanford indicates that the underground facility can be developed in one of the major basalt flows belonging to the Grande Ronde Formation in the Columbia Plateau, at depths greater than 3200 ft. One of the main concerns in the underground repository design is the achievement of acceptable environmental conditions during the development and the operation of the repository. For this, ventilation and air-conditioning are of prime importance and should be fully addressed. Besides the factors that determine the airflow requirements to meet the personnel and equipment operation needs, there are two major concerns that impact on the ventilation system design: the temperature of the in situ virgin basalt rock and the influx of groundwater. These two factors are related by the fact that the groundwater has the same temperature as the rock itself and they both constitute main sources of heat underground. Current information indicates that the temperature of the virgin rock at a depth of around 990 m (3250 ft) is 52°C (12S°F). However, there are some indications that the rock temperature at the selected horizon might be higher. This paper addresses the impact of the virgin rock temperature on the ventilation system and air-cooling requirements. Graphs with heat loads and cooling required for different rock temperatures have been prepared for a given model and network, using computer techniques for simulating the climatic parameters.

Jan 1, 1987

By R. Q. Phillips

INTRODUCTION Since Canada commenced sulphur exports in the early 1960's, the volume of exports has grown steadily and by 1984 Canadian sulphur accounted for 45% of internationally traded sulphur. In 1984 a total of 7.6 million tonnes of Canadian sulphur was shipped to offshore markets and the U.S.A. Total shipments, including domestic sales, were 8.3 million tonnes. With a production of some 5.6 million tonnes, inventory was drawn down by nearly 3 million tonnes in order to keep pace with demand. Since 1979, world consumption has exceeded total world production and Canadian sulphur inventory has played a truly crucial role in balancing world supply and demand. Consequently, by the end of 1984 the Canadian inventory, which stood at 21 million tonnes in 1978, had been almost halved to 12 million tonnes. This inventory, however, is still by far the largest in the world and will continue to play a vital role in the world supply until expected depletion around 1990. Canada is the world's second largest producer of sulphur following the U.S.A.. The Current production level of between 5 and 6 million tonnes per annum is forecast to be maintained to 1990 with only a marginal fall in that production level in the following decade to the year 2000. This will ensure that Canada retains its position as one of the largest producers and most important suppliers of sulphur in the world market well into the future. CANADA AS WORLD SUPPLIER OF SULPHUR Since Canada commenced sulphur exports in the early 19601s, exports have grown steadily. (Figure 1) The rate of growth accelerated in recent years and in 1984 a total of 7.6 million tonnes was sold for export, compared to 3.0 million tonnes in 1975 and less than 1 million tonnes in 1964. World trade in sulphur also increased during this period, from 11 million tonnes in 1975 to 17.0 million tonnes in 1984 (Figure 2). Most of this increase in volume was accounted for by Canada and Poland. As a result, the importance of Canada as world supplier expanded from 28% in 1975 to 45% in 1984. The markets for Canadian sulphur can be divided into two broad categories, i.e., solid and liquid (Figure 3). The solid market is the largest, taking about 70% of Canadian output, virtually all of which is sold offshore. The U.S.A. and the Canadian domestic market take about 20% and 10% respectively, in liquid form. In 1984, (figure 4) total Canadian sulphur sales exceeded 8 million tonnes with offshore export sales at a record 5.8 million tonnes and sales to the U.S. of 1.8 million tonnes. Domestic sales accounted for only 0.7 million tonnes. The general trend for offshore export sales has been upward whereas there has been relative stability in domestic sales. The exceptional growth in offshore sales in the 1970's necessitated considerable capital investments by the industry in order to establish a logistics system capable of handling increasing offshore tonnages. Over 50 sulphur plants are currently operating in Alberta and British Columbia. Some of these are connected by rail, (Figure 5) the balance being generally connected by road. There are currently fourteen of the larger rail-connected plants designated as export plants, and these are equipped with sulphur forming facilities. The long distances between these plants and tidewater terminals in Vancouver is a very significant factor in complex logistics of Canadian offshore sulphur exports (Figure 6). Alberta and B.C. plants are located an average of 1,400 kilometers from tidewater.

Jan 1, 1986

By S. Hodgson

The Red Dog zinc/lead deposit in northwest Alaska is the second largest zinc deposit ever discovered. Being developed by Cominco Alaska with startup scheduled for early 1990, it will ultimately be the largest zinc mine in the Western World. Table 1 illustrates the reserves of the deposit.

Jan 1, 1988

By R. C. Ford, J. Kelsey, S. A. Pierce, M. D. Ankeny

Evaluation of acid drainage risk from spent (leached) ore in arid climatic zones consists of two components: (1) whether residual and secondary minerals will release acid and metals when exposed to rainfall, and (2) whether ambient rainfall is likely to infiltrate, and eventually impact surface or ground water resources. The risk of acid drainage from spent ore at the El Abra on-off copper leach pad operation was evaluated using conventional geochemical methods and unsaturated flow models. Although geochemical testing indicated poor quality water would result from any seepage, unsaturated flow modeling demonstrated that infiltration and seepage were unlikely given the arid climatic conditions. Modeling further demonstrated that the residual moisture content of the spent ore when it is removed from the leach pad controls the risk of seepage. To further reduce the risk of seepage, operational controls were developed and implemented at the El Abra site.

Jan 1, 2000

The United States is being invaded... by foreign capital: marks, francs, pounds, yen, lire, riyals, you name it: On almost any given day the Wall Street Journal will contain a new report on a department store, newspaper, bank, hotel, agricultural land, supermarket chain, et a1 being bought into by overseas investment. Xenophobic reaction to this revised national condition has begun to set in. Several farming states have and are introducing legislation to monitor foreign land buying. In Congress a mandatory reporting requirement for foreign purchasing is currently under study. In a relatively short period the country has reverted from world leader- ship in overseas acquisition and involvement to become itself one of the prime investment opportunities in existence. Interestingly enough, one of the industries where this changed status has become most apparent and pronounced is within that small/regional/segmented/low value-to-weight bulk commodity enterprise ranked as the backbone of the nation's construction activity. U.S. cement making is not only undergoing internationalization in its ownership, but also in its product, equipment, and engineering expertise.

Jan 1, 1979

By J. Partyka, Trevor R. J. Kelly

This paper presents the results on noise testing of a fan only, as well as the results of a steel silencer and of flexible silencers that were connected directly to a fan. On-site facilities and free-field method set by the British Standards Institution were used to measure and then compare the fan only and different practical silencer configuration setups. In order to determine the fan-silencer combination that would give the maximum noise attenuation, total noise intensity, noise contributed to by the fan motor only, as well as aerodynamical noise created through air interacting with the fan parts were considered to obtain decibel readings for the octave bands. Subsequently, the optimal configuration found was the setup with flexible silencers on the fan inlet and the fan outlet. If only one silencer is used, it should be installed on the fan inlet. The aerodynamic noise affects the low frequencies. The flow noise is then overtaken at 1 kHz by the mechanical noise.

Jan 1, 1995

By R. Zhang, S. Azam, S. Liu, J. H. Golbeck, V. Kurashov, S. Bhattacharyya

Free radicals (FRs) present in coal dust directly influence the interaction behavior between lung cells and dust particles. FRs are atoms or groups containing unpaired electrons, with strong chemical reactivity and a short lifespan. FRs which are quite persistent in natural environments, termed environmentally persistent free radicals (EPFRs), have recently received much attention as new environmentally hazardous substances. EPFRs present on coal dust serves as an active intermediary to catalyze reactive oxygen species (ROS) production by oxygen molecules endangering mine workers’ health. Many EPFR species may be bonded to the particle surface or trapped within the particle during coalification and can be modified with progressive size reduction through cutting at the mining face or crushing/pulverization in the plant. This study measured EPFRs for lignite, sub-bituminous, and anthracite coal dust at various sizes. We especially focused on EPFRs for submicron coal dust prepared by cryogenic methods. The outcome of this study will directly improve the free radical-dependent toxicity quantification and ultimately contribute to the size-dependent coal dust toxicity quantification.

Mar 2, 2022

By Eleanor Kentish, Edward Batty, Alan Skarda

"The design of the tunnels at Bond Street Station includes a final sprayed concrete fireproofing layer. The performance of this layer was verified by a program of testing to Crossrail’s KT24 specification, which proved that a dosage of 1kg/m³ polypropylene fibers and a layer thickness of 50mm would be sufficient to limit spalling in the event of a fire. Application of this thin layer was achieved using a state of the art spraying robot, with the ability to scan the profile and automatically apply a uniform layer of concrete. To provide assurance and calibrate this spraying robot, BFK developed a bespoke survey system for checking SCL thicknesses in the field. This provided an instant independent check of the spraying robot and allowed areas of inadequate thickness to be rectified without risk of cold joints. This paper describes the practical application of the fireproofing layer and how design compliance was ensured. INTRODUCTION Fire is one of the most serious risks to a tunnel. The nature of tunnels — being long enclosed spaces — can increase the intensity of a fire, and make fire-fighting and rescue operations difficult. The damage that can be caused has been demonstrated by a number of historic tunnel fires, such as the Channel Tunnel fires of 1996 and 2008, and the Mont Blanc Tunnel fire in 1999. Without any intervention, the high temperatures in a fire create thermal stresses and a build-up of vapor pressure within the pores of concrete, which eventually exceed the tensile strength and trigger explosive spalling. Spalling exposes the core of the section to severe temperatures, leading to a loss of concrete and steel reinforcement strength or further spalling of successive layers. The concrete used in tunnel linings is particularly susceptible to explosive spalling, due to its low permeability achieved by the addition of microsilica (Bailey 2011). The sprayed concrete lined (SCL) tunnels on Crossrail have been designed to resist the worst anticipated fire in operation, in order to prevent collapse and minimize damage to the structure. The design called for a system of passive fire protection, the efficacy of which was validated by the contractor through a testing regime. It was critical that the application on site reflected the test conditions, which demanded special control of the profile and thickness of the lining. In order to meet these constraints on tolerances and quality, BAM Ferrovial Kier joint venture (BFK) developed a reliable method of working with the Meyco Logica spraying robot, and a bespoke survey system for accurately checking thicknesses in the field. These innovations are the focus of this paper."

Jan 1, 2016

By Diler Katircioglu-Bayel

This study aims to investigate the effect of combined mechanical and ultrasonic milling on the size reduction of talc. Firstly, the talc sample was wet ground in a stirred media mill for five different times (30, 60, 90, 120, and 150 min), and the optimum result was subsequently achieved with treatment by ultrasonication. The effects of amplitude (20, 35, and 50 μm), solid content (2.5, 5, 7.5, and 10%), and sonication time (60, 120, and 240 min) on the sizes of the final product were investigated. The pre-milling by wet grinding caused a decrease in the grinding resistance of talc. Sequential ultrasonic treatment, which was applied to the talc sample, generated smaller particles in comparison to those acquired by stirred media milling alone. Experimental results were assessed based on the product particle size (d10, d50), reduction ratio, and specific energy consumption. Submicron particles prepared by ultrasonic treatment were perfectly stable compared to stirred media milling alone as investigated in terms of particle size. In addition, the effects of mechanical and ultrasonic milling on structural properties of talc particles were characterized by XRD analysis.