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By Cornelius J. Dwyer

It is possible to hold a very optimistic view of the future of the U.S. coal industry, and there are those in the coal industry who generally choose to do so. For example, a major coal company stated recently in its annual report, "Coal's prospects appear brighter today than at any period in the past." In order to continue in this state of euphoria, it is only necessary to remind oneself of the following "facts":

Jan 7, 1967

By William D. Mayercheck

Introduction of continuous mining machines in the late 1940s created a new production bottleneck in room-and-pillar sections-the shuttle car. While continuous miners could cut and load coal at a nearly constant rate, the mining sequence was repeatedly interrupted as fully loaded shuttle cars changed places with empty ones. This wait-for-the-shuttle delay period forced the coal industry to reassess the shuttle's batch-type procedure with an eve toward continuous haulage systems that would allow uninterrupted coal flow from face to portal.

Jan 7, 1979

By C. Treworgy

Geologic and technical factors such as coal seam thickness, stripping ratios, roof conditions, partings, faults, and size and geometry of the reserve block greatly impact the availability of Illinois coal for mining. Residential and commercial developments also restrict access to coal reserves in some areas. Despite the collective effects of these factors, large blocks of bituminous coal reserves suitable for efficient, low-cost underground mining remain available in Illinois.

Jan 1, 1997

By M. R. Barkhudarov

Semi-solid metal can be formed into useful products of near net shape and high quality. Use of this method has been limited, however, because of the difficulty of working with metal in the semi-solid state, which has strong shear rate, temperature and time-dependent properties. In this paper we describe a thixotropic model and apply it to the problem of small metal droplets impacting on a flat plate.

Jan 1, 1997

By C. Gomez, J. Finch, R. Dalhke, J. Torrealba-Vargas

The velocity of gas passing through a flotation cell can be estimated by collecting bubbles by natural buoyancy in a closed tube and measuring the rate of pressure increase. The governing equation is derived and verified. Single- and two-tube gas velocity sensors are described. The latter design permits a correction for bulk density and level change during signal collection.

Jan 1, 2003

By Thomas Hard

A description is given of a new facility processing blast furnace slag into a high quality cementitious material to be used as an ingredient in concrete for general construction purposes. A brief history of the process is given, followed by a detailed discussion of the water granulation system and the methods used to transport and dewater the granulate. Environmental advantages of handling slag away from the blast furnace by water granulation are included.

Jan 1, 1983

By Paul Torrey

THE Northwestern Pennsylvania Oil Producers Association and the United States Geological Survey have cooperated in conducting a pre-liminary study of the character of the flood waters, the relationship of changes in concentration of the salts dissolved in these waters to ultimate flood-oil production, and the original association of oil and water in the Bradford field. Bradford has long been recognized as a dry-sand field. As a matter of fact, there had been little information available on the oil-field waters of northern Pennsylvania until this investigation was undertaken. THE BRADFORD SAND Practically all of the oil produced in the Bradford field comes from one horizon, generally known as the Third, or Bradford, sand. Originally, it was believed that the Bradford sand was equivalent to the Third sand of Venango County, Pennsylvania and the name "Third" unfortunately still persists, although shortly after the discovery of the Bradford pool Carll1 determined that there was a stratigraphic interval of approximately ;000 ft. between the two horizons. The Bradford sand, although varying considerably in thickness and lithology within local areas, is persistent throughout the field. It is of marine origin and, upon both paleontologi-cal and stratigraphic evidence, is regarded as a basal member of the Chemung formation.

Jan 1, 1927

By Earl H. Miller, Henry H. Bruhn

COMMERCIAL beds of sylvite ore were discovered by the Snowden & McSweeney Co. while drilling a wildcat oil well some 25 miles northeast of Carlsbad, N. NI., in 1925. After a preliminary core drilling program the U. S. Potash Co. sank a 1060-ft shaft within 4 miles of the original discovery. This shaft was in an isolated location in a sand desert area with only the roughest of dirt roads connecting it with the neigh- boring town of Carlsbad some 21 ½ miles west.

Jan 6, 1954

By David Mandolesi

An examination has been made of the structures of strand cast blooms and the rails rolled from them; this paper details the characteristics of these typical structures. Results of mechanical testing data show that this product compares with rails processed from conventional ingot steel. Improvement in processing yields and surface quality standards are also briefly discussed.

Jan 1, 1972

By Lu S, Jiang Y

The conventional transportation system in open pit, a to u.* itc:,~> truck., to carry the ore along the ramps. Normally, the transportation distance increases greatly as mining progresses deeper. A new approach to overcome the above disadvantage is to adopt a buried roadway by which ores is transported by conveyors from the mining area to the outside dump in the shortest distance so that the production efficiency is greatly increased. Maintenance of the buried roadway in a good working condition is the key factor that determines the success or failure of the proposed approach. This includes the determination of support load, types and structures of support and other related supporting measures. The crucial problem here is to effectively control the load applied on the buried roadway in a certain range that the ordinary support can stand. Based on the theoretical analysis, numerical modelling and physical simulation testing using equivalent material, this paper studies effects on control of the support load by adopting certain measures, for instance reinforcing the surrounding rock and placing the extendable layer between the support and a rock mass. Furthermore, the influence of the dynamic load induced by the movement of heavy vehicles on the stability of the buried roadway is also investigated.

Jan 1, 1995

By A. H. Jones

(San Francisco Meeting, September, 1915). THE Belmont mill at Tonopah, Nev., was designed and constructed by the Belmont staff. Ground was broken in August, 1911, and milling operation started July 25, 1912. The metallurgical flow sheet, and the machinery adapted to carrying out operations in accordance with this plan, were decided upon from experience gained in the treatment of Belmont mine ores at the old Belmont mill at Millers, Nev. The detail drawings were made by the-engineering staff of the Tonopah-Belmont Development Co., under the supervision of Otto Wartenweiler, who also .had direct charge of the construction, consulting with the General Superintendent of the company, Frederick Bradshaw, and the writer.

Jan 8, 1915

Minimize failures or inefficiency in the operation of in situ mining wells. Approach The proper design, construction and development of wells are important to any in situ leaching operation. To permit cost-effective production from an underground ore body by leaching it in place, many wells are normally installed. Construction and maintenance costs increase with the number of wells, and poor construction and maintenance procedures result in production losses and negative environmental impacts, To minimize these losses and impacts, the Bureau of Mines conducted an investigation to determine the optimum in situ well construction and operating procedures for the minerals industry. Factors considered during the investigation included drilling equipment and procedures; types of well casing and grouting; completion methods, e.g, screening or perforation; and system maintenance. The data collected were used to prepare a manual that offers guidelines

Jan 1, 1984

By Gerald H. Luttrell, Jaisen N. Kohmuench, Michael J. Mankosa

A new separator, known as the Hydrofloat cell, has been developed to overcome limitations of traditional flotation cells in recovering coarse particles. In this process, small air bubbles are introduced into a hindered "teeter" bed of fluidized solids to create light bubble-particle aggregates that can be separated based on differences in density. Laboratory tests conducted with coarse phosphate feeds indicate that the Hydrofloat cell is capable of increasing BPL recoveries by nearly 20% over conventional flotation methods. Based on these encouraging results, a pilot-scale Hydrofloat cell was fabricated and installed at a central Florida phosphate plant. Test data collected using the pilot-scale unit suggest that the BPL recovery of the plus 35 mesh plant feed can be increased by more than 40% through the application of this new technology. This improvement is particularly beneficial due to the very high grade (-73% BPL) of the plus 16 mesh particles in the Hydrofloat concentrate. This article describes the theoretical basis for the development of the Hydrofloat cell and provides an overview of recent laboratory and pilot-scale test results.

Jan 1, 1999

By John Stankus

Regional high horizontal stress has long been recognized as an important factor affecting roof stability However, localized high horizontal stress, although causing many ground control problems, has not received due attention, Through many ground control studies and underground experiences, it has been round that localized horizontal stress can be created by abrupt changes of overburden and stream valleys. The magnitude of localized horizontal stress depends on the valley configuration and overburden depth. Utilizing the Jennmar Finite Element Analysis System (JFEA), this paper analyzes the mechanism of the localized horizontal stress concentration based on two cast studies.

Jan 1, 1999

This paper describes how Western Mining Corporation uses sophisticated diesel equipment in mining of shallow flat dipping narrow ore- bodies in the Otter Juan area. Though in most cases the stoping method chosen relies on hand held conventional equip- ment, the 'ore handling systems have been designed to allow for a relatively high degree of mechanization. The use of diesel loaders, trucks along with three boom jumbos is described. A single one in nine decline driven as the means of access to the various ore surfaces at Otter/Juan resulted in the first ore being produced first 15 weeks after the first round was fired in the Ore-Decline. Now, three years later, the.mine is in full production, and in 1971/72 produced 392,000 dry tonnes of high grade Nickel Ore.

Jan 1, 1973

By Smith KS

Mineral-deposit geology, geochemical processes, and biogeochemical processes are fundamental controls on the environmental conditions that exist naturally in mineralized areas prior to mining, and that result from mining and mineral processing. Input from economic geologists and geochemists is therefore crucial to effectively predict, assess, mitigate, and remediate the environmental effects of mineral-resource development. Recent open pit gold mining at Summitville, Colorado, has received intense public scrutiny for a variety of environmental problems, most important of which has been extreme acid drainage. Now a Superfund environmental cleanup site, Summitville exemplifies how economic geology and geochemistry principles (1) could have been better utilized to first predict and minimize the environmental problems, and (2) can now be used to optimize the environmental cleanup.

Jan 1, 1995

By W. P. Sykes

In an earlier paper1 the composition-temperature limits of the gamma iron phase in the iron-tungsten system were reported as approximated by thermal analyses. At that time no attempt was made to develop metallographic evidence of the coexistence of two phases in the iron-rich solid solution at temperatures between 900" C. and 1400" C.

Jan 1, 1931

By J. Y. Oldshue

INTRODUCTION The field of fluid mixing involves many different kinds of process objectives. In order to classify these objectives, Table 1 gives a listing of five basic application categories, gas-liquid, liquid-solid, liquid-liquid, miscible liquids, and fluid motion. However, each of these areas can be broken up into two different concepts one involved with uniformity of solids or liquids as a criteria, and the other involved with chemical reactions or mass transfer. The things that we would do to design a fluid mixing for solid suspension are quite different from things that we would do to design a mixer for heat transfer or gas-liquid mass transfer. Therefore, there are really ten separate mixing technologies. Each of these areas has its [ ] own principles of fluid mechanics, scale-up techniques and application experience. We will take a look at each of these areas and look at some of the ways that we can handle fluid mixing applications which.

Jan 1, 1979

By Scott Stebbins

Cost estimating and economic evaluation software provide evaluators with the ability to predict the profit potentials associated with mine design alternatives even during project exploration and prefeasibility. Examining a multitude of development alternatives early on serves to identify aspects critical to profitability and to increase the reliability of economic projections. A case history illustrates how Sherpa Cost Estimating Software, when used in conjunction with Apex Software for Economic Evaluation, significantly enhances an evaluator's ability to examine design alternatives in a timely and reliable manner. The costs and economic impacts associated with various access routes, production rates, equipment mixes, and stoping methods are projected.

Jan 1, 2002

By Alan R. Gadberry

To resolve drilling and blasting problems, rather than treating symptoms and allowing problems to grow, the mine operator needs to change the way he operates. When a mine operator discovers a drilling and blasting result that he doesn't like, it is easy for him to think of that disappointing result as a problem. More often than not, however, that result is only a symptom of a problem, and the real, underlying problem cause can be seen when the operator looks in the mirror. Symptoms and problems relating to drilling and blasting are resolved when the mine operator makes appropriate changes in the way he manages his operations.

Jan 1, 1985