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By S. Kenzap, V. Kazakidis

Risk assessment is an essential component of mine feasibility studies. However, it is often challenging to identify the appropriate analysis and derive the required input data. The uniqueness of a mining project and the associated technical issues require customization of the risk assessment approach to meet both requirements and characteristics. The uncertainty driving the operating risk in mine feasibility studies and its assessment through Monte Carlo simulation as a component of a cash flow analysis are discussed in this paper. The paper introduces the use of the analytic hierarchy process for derivation of qualitative input and conducts quantification of the three main sources of operating performance delays, equipment, ground and schedule problems, in a cash flow simulation. A methodology for the assessment of operating risk in mine feasibility studies is presented.

Jan 1, 2011

By J. Richard Kyle

The Pb-Zn ore bodies in the Pine Point district are localized in paleo-solution structures that developed as the result of post-middle Givetian subaerial exposure of the carbonate barrier complex. Sulfides are concentrated in transgressive pale-solution structures that acted as natural bypasses between aquifers and loci for mixing of fluids of different character, one of which contained metals and the other reduced sulfur. Complex ore textures indicate rapid early sulfide precipitation followed by slower sulfide growth. Evidence for both sulfide-carbonate equilibrium and disequilibrium conditions suggest fluctuations in ore fluid composition. District and ore body metal distribution patterns may reflect the nature and movement of mineralizing fluids.

Jan 1, 1979

By J. C. Weimer

The goal of Bethlehem's mining research program is to improve both the safety and productivity of our mines through the use of new equipment, new technology and new mining methods. Although we can all agree on the value of such goals, achieving them can be a costly, time-consuming and sometimes frustrating experience. However, the potential benefits of lower costs per ton and better safety in an increasingly more stringent and confusing regulatory environment make the expended effort worthwhile. At Bethlehem we feel that the mining companies are in the best position to determine the needs of the industry, and coal companies have the incentive as well as mine sites at their disposal for testing. Therefore, the mining industry should be leading the research effort

Jan 1, 1979

By A. Noble

"A supply of sustainably sourced rare earth elements (REEs) is critical for several high-tech industries, renewable energy technologies, and defense applications. Recent studies have shown that REEs exist in coal and coal combustion byproducts at elevated concentrations and in quantities that could meet domestic demand. Despite these promising findings, declines in rare earth prices, volatile commodity markets, and challenging geo-metallurgical conditions have jeopardized this potentially valuable REE resource. While the dilute REE concentrations inherently necessitate low-cost separation technologies, the ultimately operating cost threshold for economic extraction must be based on commodity price projections and market demand. In this paper, the micro-pricing principle is used to develop a rigorous economic model assessing the inherent value of REEs in coal materials. This model is based upon basket pricing of individual elemental oxides, and elemental distributions of coal samples from various basins. These results may be used to assess the economic viability of potential REE concentration and refining technologies INTRODUCTION Recent efforts by US Department of Energy (DOE) and the National Energy Technology Laboratory (NETL) have suggested that rare earth elements (REEs) may exist in coal and coal byproducts at concentrations suitable for economic extraction and processing. While the knowledge of REE occurrence in coal material dates back over 50 years, recent supply restrictions and material criticality considerations have prompted a national interest to establish a sustainable domestic supply of REEs. REEs are not “rare” in the sense of crustal abundance; however, few natural processes lead to concentrated ore deposits. As a result, the elevated concentrations found in coal material may provide a potentially promising resource for these materials. While the term “rare earths” is often used to describe a singular concept, the 15 rare earth elements actually have varying and sometimes contrasting scarcity and cost profiles. Various authors have proposed classification systems to provide information on REE criticality (e.g. Seredin and Dai, 2012, Zhang et al., 2015). The most straightforward classification is provided on the basis of geochemistry with designations for “light”, “medium” and “heavy” rare earths. Light rare earths (those to the left of the periodic table: Ce, Pr, Nd, and Sm) tend to be more common and less valuable when compared to their medium (Eu, Gd, Tb, Dy, and Y) and heavy (Ho, Er, Tm, Yb, and Lu) counterparts. While light rare earths are often found in traditional ore deposits at economic concentrations, the heavier rare earths are almost exclusively found as ion-absorbed clays (Seredin and Dai, 2012)."

Jan 1, 2016

By T. P. Meloy

Like our wives, the comminution of brittle solids is easy to recognize but difficult to describe. However, describing it we must. Describing the fracture mechanism of brittle solids permits the eventual mathematical quantification of the results, process optimization and control strategies. This paper presents a physical model of brittle solid comminution that explains why the slope of the log-log size distribution curves have a slope of one or less in the smaller particle sizes. To develop the hypothesis, modifications of the Gaudin Meloy physical model are made. In brittle solids, comminution takes place by cracks propagating through the material. These cracks may bifurcate as they move. Cracks may terminate either on the original surface of the material, or on a secondary crack within the material formed earlier in the comminution process.

Jan 1, 1994

By Christian Maguire

Tunnel contracts in New York have in recent years had few bidders with the bids received being much higher than anticipated. Since 9/11, security has become a key issue in planning key infrastructure projects in New York. This is especially true in the case of large water supply tunnels. Striking the right balance between cost and security was the major factor in determining the best configurationfor the Kensico-City Tunnel. This paper outlines the efforts made to determine realistic probable bid costs for the tunnel contracts, and the innovative approaches taken to deal with security issues.

By McGuirk. C. H.

The Port of Conneaut, long regarded as a leader in advanced bulk material handling technology, recently incorporated into its existing facility a new, multi-million dollar coal transfer-storage system. While the basic principles of conveyorized bulk material handling remain unchanged in the new system, design modifications such as rotary dumping of railroad cars, automated car feed to dumper, belt rip detection for conveyor belting, bucket wheel continuous production, and other innovations make The Pittsburgh and Conneaut Dock Company's complex worthy of classification as the "Port of Tomorrow - Today". The Pittsburgh & Conneaut Dock Company, the "Port of Tomorrow - Today", 1s a bulk materials storage and transfer facility located on Lake Erie, 68 miles east of Cleveland, 30 miles west of Erie, PA., and 138 miles north of Pittsburgh. Figure 1 shows an aerial view of the facility. It is designed to handle over 25 million tons per year of metallurgical and steam coals, direct shipping ore, fine ores, concentrates, pellets, limestone, and dolomite. Inbound shipments of iron ore and limestone are received from Minnesota, Michigan, Labrador, and Quebec. Coal arrives from Pennsylvania, Ohio, Virginia, West Virginia, and Maryland. Rail service is provided by the Bessemer & Lake Erie Railroad Company.

Jan 1, 1980

By George A. Desborough

Marine black shales of Paleozoic age in the Western United States that exceed 10 weight percent organic carbon contain as much as 5,000 ppm vanadium, 1,000 ppm molybdenum, 1,300 ppm nickel, 600 ppm cobalt, 16 ppm silver, 7,000 ppm chromium, 18,000 ppm zinc, 280 ppm cadmium, and 350 ppm selenium. Depositional settings include: (1) continental-rise and marginal-ocean basins, (2) continental-shelf and foreland basins, and (3) cratonic-platform embayments. Most of these metalliferous organic-rich shales have not been examined for resources because of rapid weathering and poor exposures which preclude easy sampling of unoxidized rock necessary to determine actual concentration and residence of indigenous metals. Generally, the marine black shales of Paleozoic age in the Western United States are richer in metals than marine Paleozoic black shales in the Eastern United States.

Jan 1, 1982

By R. A. Pimentel

Many longwall operators experience difficulty complying with the federal regulation limiting average dust exposure. Others are currently in compliance, but the dust exposure limit keeps then from increasing their production. Spray water is a major means of dust control. Excess water can cause problems in the transportation system and the cleaning plant, and reduces the Btu value of the run of mine coal. Thus, the dust exposure reduction per unit of water sprayed must be maximized. This paper discusses underground tests recently completed as part of a Bureau of Mines research program to determine the effects of variations in spray water flow rate, pressure, proportioning and spray orientation on longwall shearers.

Jan 1, 1984

By William D. Mayercheck

The introduction of continuous mining machines in the late 1940's prompted the mining industry to reassess shuttle car batch-type haulage. Between place changes, the continuous miner could cut and load coal on a nearly continuous basis, but after loading a shuttle car, the high-capacity machine had to wait until the second shuttle car came inby and spotted itself under the miner tail boom. Thus, the wait-for-shuttle-car delay periods became the new bottleneck for increased coal production from the mine section. Recent studies have shown that nearly 25 pct of the continuous miner cycle time is consumed by delays in the haulage system, usually waiting for shuttle cars. Computer simulations of a face operation indicate that up to a 45 pct increase in coal production may be realized through the use of a continuous haulage system, assuming of course that the outby haulage system can handle this increased capacity. Coincidently, there are recent claims by some mines using continuous face haulage of a production increase of 45 pct compared with shuttle car haulage. These documented production records, computer simulations, and common sense indicate the potential of continuous face haulage in underground coal. The late 1960's and early 1970's saw several mining machinery manufacturers market mobile bridge carrier and piggyback bridge conveyor continuous haulage systems for use in underground coal mines. These systems have shown limited potential in some mines and outstanding success in others. It appears that no one system can be universally applicable to all underground mining conditions; thus, the Bureau of Mines has conducted extensive research over the last few years to investigate different types of continuous haulage systems for use in high and low coal seams that will advance the state of the art.

Jan 1, 1977

By SONGHE WANG, YI XUE, PENG HOU, CAIHUI ZHU, XUANYE JIAO, Feng Gao

The abstract discusses the challenges of coalbed methane development in China due to low coal seam permeability. It highlights protective layer mining as a method to reduce in-situ stress and enhance permeability for improved gas drainage and disaster prevention. The study involves experimental and numerical simulations to analyze gas migration and permeability changes during stress release. It includes a stress-strain-seepage coupled test on coal, development of a mathematical model for coal seepage under mining unloading, and a numerical model based on the Wulan coal mine to explore in-situ stress release, permeability evolution, and gas drainage in an unloaded coal seam. The aim is to demonstrate the effectiveness of combining protective layer mining and gas drainage technology for gas outburst risk elimination.

Mar 14, 2022

By S. Natansohn

A prevalent technique for the recovery of silver from wastes generated in silver-tungsten electrical contact fabrication is electrowinning. Such scrap is placed in a permeable plastic basket which constitutes the anode compartment and this basket is suspended in a larger cell in which the cathode is mounted. A silver nitrate solution is used as the electrolyte and, upon application of an electric field, the silver migrates to the cathode where it deposits out. At times, there is tungsten migration to the cathode compartment and consequent co-deposition with the silver. This W contamination, which may amount to several thousand ppm, necessitates additional purification of the deposited Ag and its removal would therefore be advantageous. The elimination of the W impurity would also extend the operating period of the cell with corresponding increase in the Ag output and savings in labor costs.

Jan 1, 1982

By C. M. McCulloch

More and more mining underground is being conducted using the longwall method. Likewise, many new surface mines use area or mountaintop removal methods. These methods can have a significant impact on surface and groundwater resources. The overall study of the effects on surface and groundwater from mining is referred to as the probable hydrologic consequences (PHC) determination of mining and reclamation. Collection and interpretation of information concerning groundwater and surface water quality and quantity, as well as detailed geologic analysis, is required to adequately define the impacts of mining. This paper discusses the present day requirements and methodology of preparing a PHC for a large mining operation in the eastern coalfields.

Jan 1, 1995

By Rolando Gonzalez

Mexico’s role in the world economic community continues to grow. And it is important that the country makes use of its natural wealth, including its large underground deposits of minerals and metals. With that in mind, Industrias Peñoles S.A. de C.V.(Peñoles), a mining, smelting and refining company, began mining lead, zinc and other metals from the Francisco I. Madero Project (FIM). The mine is located about 600 km (370 miles) northwest of Mexico City in the state of Zacatecas. Peñoles plans to remove about 3 Mt/a (3.3 million stpy) of ore from FIM. To achieve this goal, the company needs to optimize its processing, to maximize the amount of metal it extracts through FIM’s large flotation lead-zinc concentrator. To ensure high productivity, Peñoles and its contract engineering firm, M3 Engineering and Technology, of Tucson, AZ, have implemented anore processing system.

Jan 1, 2003

By H. Wesley Peirce

Although not generally recognized, Arizona has rock salt deposits unique in the United States. This uniqueness stems from a combination of two factors: (1) relatively youthful geologic age and (2) nonmarine origin. Although Arizona shares one deposit with Nevada (Figure 1, No. I) there are three others within the State (Nos. 2, 4, 5) that are believed to be both late Cenozoic in age (less than 15 million years) and nonmarine in origin. The only other recognized nonmarine salt deposits in the U.S. are much older, being in the early Cenozoic (Eocene) Green River Formation of Colorado and Wyoming. According to Johnson and Gonzales (1), the remaining rock salt deposits in the United States are marine and either Paleozoic or Mesozoic in age. Of the seven localities shown in Figure 1, six in the Basin and Range geologic province are believed to represent nomarine late Cenozoic phenomena and one (No. 7) in the Colorado Plateau geologic province is Paleozoic (Permian) in age and marine in origin. The following comments are intended to update the general geologic highlights of these deposits and to summarize the nature of their present utilization.

Jan 1, 1979

By James E. Breland

Society's growing concern over the number of deaths and serious injuries occurring in coal mines, coupled with a growing sentiment to develop and promulgate improved mandatory health or safety standards, was no doubt the basis for passage by Congress of the Federal Coal Mine Health and Safety Act of 1969, being Public Law 91-173 approved December 30, 1969. Even prior to passage of the Act, strong reaction was quick to arise concerning the effect of such legislation upon the coal mining industry. Initial response varied from mild forms of criticism to' the expressed fear of complete suspension of operations and mine closings. Primarily responsible for these early forms of skepticism were speculative or fanciful cost estimates which led operators to contemplate a less than prosperous existence. However, in spite of this unfavorable outlook, the majority of the operators have faced up to the situation and have been striving to comply with the Act and the regulations issued thereunder. While encouraging strides have been made toward implementation of the Act, it must be recognized that noticeable results have been attained only through many months of determined effort and, as anticipated, at quite heavy expense to the operator.

Jan 1, 1973

By R. A. Wyman

What unusual features are there about finding, winning, and using the industrial minerals of Canada which may be of interest and yet not widely known. Have you, for example, ever wondered where the raw material for those distinctive greenish grey statuettes, so readily recognizable as Eskimo carvings, comes from? Although stone suitable for carving is obtained at several northern locations, in recent years the Federal government, the Quebec government, and one or two private companies have shipped supplies of various rock types from other sources to central distribution points in the Canadian north for the express purpose of providing Eskimo artists with raw materials for carving. Canada is well endowed with industrial minerals, the extent and variety of which may be observed by a perusal of Table 1. In this table, materials currently produced are shown in the left-hand column; materials which are bordering upon economic viability are listed in the middle column; and materials which have been found in Canada in possible exploitable quantity, but for which [ ]

Jan 1, 1970

By H. B. Charmbury

In Pennsylvania there are two distinct coal regions, bituminous and anthracite, in which the mining conditions and production trends are different. Bituminous mining is more mechanized, and production is increasing. This report is concerned specifically with the bituminous area. The bituminous coal industry apparently is facing a shortage of miners and mine officials which may become acute by 1970. Since 1949, when Pennsylvania had more than 100,000 bituminous coal miners, the number has steadily decreased. There are two principal reasons for the decrease of certified miners and mine officials. These reasons are the fact that apprentices are almost a thing of the past and the fact that the image of the coal miner is a poor one to people in general and to parents in particular. This has contributed greatly to the high average age of our miners today. The average age of all those employed in the mines is 50. Yet it is known that the progress in mine mechanization requires younger and more alert men to operate the newer type equipment.

Jan 1, 1966

By Xinzhi (Thomas) Du

"A longwall mining method is a productive mining method of coal extraction that involves the complete removal of large, rectangular panels of coal. Since this method causes deformations through the overlying strata to the ground surface, the surface- and ground-water regime above the longwall panels may be adversely affected and drained into the lower strata. The purpose of this study is to determine the effects of longwall mining subsidence on surface- and ground-water systems.This study is a site-specific hydrogeologic analysis conducted before, during, and after panel retreat at a site located over two selected longwall panels in the Pittsburgh coal seam in Greene County of Pennsylvania. Mine subsidence causes fractures in the overlying strata and enlarges bedding plane separations, increasing the effective porosity and storativity of the overlying strata. Generally, the water in deeper aquifers located in the lower fractured zone drains into the mine void due to the vertical fractures. Moreover, the water level does not recover after longwall mining (but may recover when the mine is flooded). The upper aquifers over the thick aquitard layers may maintain the water level or drop slightly during longwall mining and recover very quickly. The reason is that the underlying aquiclude layer has less change in porosity and permeability after longwall mining (Carver, 1994).A groundwater flow model-MODFLOW was used to predict the water table contours for the periods of pre- and post-mining conditions. The hydraulic gradients of post-subsidence became larger outside the panels and smaller inside the panels than that of the pre-subsidence. The groundwater hydraulic heads above the longwall panel dropped a maximum 50 ft in the study panels. The shallows monitoring wells that were less than 50 ft deep from the surface were deeply affected by longwall mining subsidence. For the intermediate wells that were more than 85 ft deep from the surface, where strata movement acted as a unit during longwall mining subsidence, there were little impacts of longwall mining on the intermediate wells in the study area. For the deep wells that were located below the Waynesburg sandstone, the water was drained to the underlying strata or even into the mine gob."

Jan 1, 2019

By V. R. Burkhart

Pennsylvania Power & Light Company is an investor-owned public utility which was incorporated under the laws of the Commonwealth of Pennsylvania on June 4, 1920, with general offices at 901 Hamilton Street, Allentown, Pennsylvania. At the present time PP&L is operating five coal-fired steam electric stations, two hydroelectric stations and one steam heat plant which is being converted from anthracite to oil fired. In addition, PP&L is a partner in both the Keystone and Conemaugh mine mouth bituminous coal-fired steam electric stations in Central Pennsylvania and also part owner of a company which operates another hydroelectric station. PP&L plants, other than the two mine mouth stations, are located in Central Eastern Pennsylvania. (Figure 1) The company derives about 99% of its operating revenues from supplying electric service, while the balance is from the one steam heat plant serving the city of Harrisburg. The entire service area covering 10,000 square miles in 29 counties, has a population of approximately 2,300,000 people. The area served is mostly suburban. It includes 109 communities each having a population in excess of 5,000 people. The largest cities served are Allentown, Bethlehem, Harrisburg, Hazleton, Lancaster, Scranton, Wilkes-Barre, and Williamsport which range from 50,000 - 120,000 in population. So you see our service area does not include any major cities. The area has industrial, commercial, residential, agricultural and recreational activities that are linked with the Eastern Megalopolis by an extensive interstate limited-access highway system and railroad networks. We consider this Central Eastern Pennsylvania area we serve as the "heart of the market" -- an area with great growth potential.

Jan 1, 1973