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By S. Webster, M. Karmis, C. Haycocks

Mining any seam can seriously affect subsequent operations in coal seams both above and below the one being mined. The effect is often detrimental to the recovery, cost and safety of mining the subsequent seams. This paper describes the ground control mechanisms involved in mining through a passive subsided zone or all actively subsiding trough. Data were extracted from case studies, primarily from the Appalachia region, for construction of empirical models to predict interaction problems that can occur in overlying seams. Inner-burden thickness, innerburden lithology, percentage extraction, lower seam height, time and overburden were analyzed to determine their effect on upper seam damage. Magnitude of upper seam subsidence was incorporated, together with a broad classification of rock types, to predict the type and range of damage that can occur in the upper seam. Results are summarized in graphically and nomogram form for use in. engineering design.

Jan 1, 1984

Would you give us a short biographical sketch including your birthplace, education and current activities? I was born Jan. 16, 1920 in Minneapolis, Minnesota, and lived there the first 22 years of my life. I also spent quite a bit of time on a farm about fifty miles north of Minneapolis owned by relatives. During the Depression, we lived off of ten cows and about fifty chickens. I'm a full-blooded Swede all along the line, and I'll be the last one in my family since my wife is not of Swedish descent. I attended Macalester College, a small school in St. Paul, to study for the ministry originally. However I soon realized that I really didn't have the talents for the ministry and I could probably do as much or more in a field where I did have some talent.

Jan 3, 1974

By F. D. Waltman

Under the hot, baking sun, engineers at the AEC's Nevada Test Site have been busy for several years in the sinking of 48-in. diam shafts to depths varying anywhere from 1800 to 4800 ft below the surface. In so doing these men have evolved several new techniques which should be of interest to the mining industry. Surface Facilities Designed For Speed: "Expediency plus efficiency" is a key phrase at the Site. Because of the relatively short duration of actual mining operations, all equipment has been packaged to decrease time and cost of "set up" and "take down". The headframe, designed specifically for use over 48-in. cased shafts, can be erected or dismantled within 48 hours. The back legs are pinned and hinged to the front legs for ease of installation and, when dismantled, for movement to another site with a minimum of delay.

Jan 6, 1966

By Richard R. Klimpel

This paper takes the liberation model recently developed by Klimpel and Austin for liberation from a binary system and reduces the over-all model form to a number of useful limiting cases. General use of the complete model form, while quite broad in utility, requires a numerical integration computer program for prediction of liberation given a specified minor component grain size distribution coupled with an optimization algorithm such as linear programming in order to back- calculate the associated grain size distribution from experimental data. In this paper, analytical solutions to the model are achieved for various assumed distributions of the minor component. These solutions are algebraic equations capable of predictive use with a hand calculator and back-calculation with very simple trial and error search procedures. The use of these special model solutions is illustrated on several sets of experimental liberation data, and the approach is shown to have practical utility.

Jan 1, 1984

By Robert L. Voss, Richard D. Hagni

Sparry dolomite from all of the operating mines in the Viburnum Trend of Southeast Missouri have been found by cathodoluminescence microscopy to reveal a systematic pattern of banding resulting from a growth zoning within individual dolomite rhombs. Four principal bands have been recognized throughout the entire Trend and each of the major bands contain even finer internal banding. Minor bands a few microns in width can be correlated in specimens collected ten's of kilometers apart along the trend. The first three principal dolomite bands decrease from south to north. This feature, together with the fact that the white sparry dolomite crystals decrease in abundance from south to north in the Trend, suggests that a major source for the fluids was from the south. The application of cathodoluminescence microscopy to crystalline dolomite demonstrates a strong correlation between ore grade and the intensity of internal banding and dissolution textures.

Jan 1, 1985

Prof. Dr. H. Seger and Mr. E. Cramer, Chemisches Laboratorium fur Thonindustrie, Berlin, Prussia (communication to the President)* : We have learned, with much interest, from the pamphlet sent to us, of the work of Messrs. Hofman and Demond, particularly as we observe from their experiments that these gentlemen recognize the usefulness of the Seger cones, and that this method of determining temperatures in the furnaces of the ceramic industry and in the tests of refractory clays is valued, not only in all parts of Germany, but also in other countries. Permit us to say, with reference to the crucibles employed in tests for refractoriness, that we have used of late, besides the magnesia crucibles, also those made of Zettlitz kaolin, with the addition of alumina, previously calcined, with regard to which we beg to refer to our article in the Thonindustrie-Zeitung of December 9, 1893.

Jan 1, 1895

By Guy R. B. Elliott

If chemical mining is to work, it is extremely important to watch heat balances. Some reactions with coal give off heat and others absorb heat. The reactions of coal with oxygen or air give off heat, but the reactions of coal with steam or with carbon dioxide absorb heat. By balancing the proportions of the two types of reactions, the energy of the coal can be almost completely recovered and environmental damage is minimized. The chemical reactions are listed in Table 1 in the usual form with subscripts (s) and (g) indicating solid or gaseous materials. In reaction 1, solid corbon, C(s), reacts with gaseous oxygen, O2(g), to produce gaseous carbon dioxide, CO2 (g). H means enthalpy or available heat in the material; F is free energy, and it measures whether the reaction can go at all, and if so, how much.

Jan 9, 1973

By Parviz Montazer, Robert King, William Ubbes, Gideon Chitombo

This paper describes the results of a detailed study that was undertaken to define the spatial distribution of permeability within a five meter thick envelope around the CSM/ONWI room. Detailed fracture orientations and distribution were determined through mapping of the walls of the opening, logging of oriented core, and visual examination of borehole walls with a borescope and a T.V. camera. Over 3,500 measurements were made from which the three dimensional distribution of fractures was determined. Two principally different testing equipment designs and various methods of air injection tests were used in all boreholes to identify and characterize conductive fractures. Through analizing the distribution of permeability and fracture index around the room a zone of blast damage of approximately .5 m thickness was delineated. The effect of stress modification seems to extend farther into the host rock to approximately 3.5 m depth.

Jan 1, 1982

By J. S. Smart

The six countries which make up the European Economic Community-Belgium, France, German Federal Republic, Italy, Luxembourg and The Netherlands-are populated by about 170 million consumers. Their economic abilities and their standard of living have increased at a high rate during the past few years. Consequently, the policies and trade practices adopted by the group will have International repercussions within the nonferrous Industry whether or not other nations are eventually admitted to the group. Considering the hopeful prospects of only a few months ago, it is surprising that we must now face up to the fact that Great Britain and Norway, in particular, will achieve membership status only after prolonged and difficult negotiations, if at all. However, this is but one of many factors that should remind us that the Common Market is yet in its formative stage and has by no means reached maturity.

Jan 6, 1963

Fred D. DeVaney (Magnetic Roasting of Iron Ores, P. 1219) has presented several other AIME papers, all of them concerned with grinding and concentrating problems. He is chief metallurgist, Pickands Mather & Co., at Hibbing Minn., after working for the U. S. Bureau of Mines at Tuscaloosa, Ala., and Rolla, Mo., as a junior metallurgist and a metallurgist. DeVaney started as a research metallurgist with Pickands Mather in 1942. He set up the first laboratory in the Lake Superior district devoted to taconite concentra¬ [ ] tion, his major interest. He has been an AIME member since 1923, holding various offices, including the first presidency of the Minnesota Section. DeVaney has a Bachelor's in Mining, and Master of Science earned at the University of Alabama in 1924. He is a member of the Engineers Club of Northern Minnesota and plays golf for relaxation and enjoyment.

Jan 1, 1952

By High Archbald

It is possible to construct a simple diagram of the earnings, or the production, of the men employed at a coal mine that will show not only if the conditions tend toward contentment among the men, but if the operating distribution of the work is correct. As earnings are the greatest cause of discontent, even exceeding all the other causes, if contentment exists in the matter of earnings, the likelihood of other discontents flaring up is greatly lessened. The basis of such a diagram would be the Gaussian curve of the normal variation in human ability. Such a curve has long been recognized. H. L. Moore,' in discussing the quantitative relation between wages and ability says: "It has been pointed out that industrial efficiency is dependent upon physical, mental, and moral qualities, and these qualities . . . there is good reason for regarding as being distributed according to the Gaussian law.

Jan 1, 1925

By I. Stapf

Systematic investigations on silver-rare earth metal systems have been extended on the Ag-Ce system in order to clarify the discrepancies reported in literature. The phase diagram has been reinvestigated on the base of thermal analyses and of microstructure examination on cast and annealed specimen. All intermetallic phases Ag4Ce, Ag3Ce, Ag2Ce and AgCe show no extended range of homogeneity, they melt congruently fm), or decompose peritectically (d) at 815 °C (d), 1030 °C (m), 855 °C (d) and 855 °C (m), respectively. The system shows eutectics at 793 °C/10 at.%, 780 °C/42 at.%, and about 505 °C/81 at.% Ce. d-Ce dissolves up to 2 at .% Ag and decomposes metatectically at 710 °C. Furthermore, the phase transformation of the intermetallics would be clarified. The phases Ag5Ce and Ag51Ce14 reported in literature could not be verified.

Jan 1, 1984

By J. L. Jernegan

IN the summer and fall of 1875, the author was present during a short smelting campaign at the Hall Valley works, and having had occasion to make a number of chemical analyses of the ores, fuel, and fluxes, deems that the results of the same, and also an account of the smelting operations, may be found of interest to members of the Institute. The mines and reduction works of the Hall Valley Silver-Lead Mining and Smelting Company (limited) are situated at Hall Valley, Park County, Colorado. The smelting works are located about half way from the mouth to the head of the above-named valley, and the mines high up on the mountains, near its head. The three principal mines of the company are the Whale, Leftwick, and Cold¬spring. They are all on different veins, running parallel to one another, with a general trend from southwest and northeast. The

Jan 1, 1877

By Henry U. Ross

The behaviour during reduction of iron-ore pellets and sinters was investigated. Several methods for the preparation of agglomerates and their reduction were tried. Commercial agglomerates from world-wide sources as well as experimental samples were tested. The effect of coke additions to pellet and sinter plant feeds was given special consideration. An analysis of the test results has helped to explain many of the phenomena associated with the reduction of iron-ore agglomerates such as swelling, loss in strength and wear resistance, changes in porosity, changes in mineralogy and the formation of metallic iron and slag. A double-layer pellet with all of the coke concentrated in the core proved particularly interesting. Although large quantities of coke showed that partially reduced agglomerates containing metallic iron could be produced in the laboratory, the problem of producing reduced pellets and sinters by the existing agglomerating processes still remains.

Jan 1, 1977

By C. S. Roberts

THE advent of a sensitive X-ray method of analysis recently has allowed the determination of retained austenite in amounts as low as 0.3 pct.' As a result this phase has been found in quenched low carbon steels where its presence has not been generally suspected. In the course of a study of the tempering process,' retained austenite determinations were made by the X-ray method on a series of high purity Fe-C alloys and plain carbon steels. The chemical analyses of these materials and details of the hardening procedure are given in Table I. Results were obtained after quenching to 72°F (22°C) and — 321 °F (—196°C). Austenitizing temperatures were between 100" and 150°F above A, or Acm. All proeutec-toid cementite or ferrite was in solution. The combination of the results with those of Averbach, Castleman, and Cohen,' and earlier results of Esser

Jan 1, 1954

By John S. Brown

AT opposite ends of a mineralized belt of northeast-southwest trend, and ten miles apart, are the Edwards and Balmat zinc minas, in St. Lawrence County, New York, west of the Adirondacks. The principal town is Gouverneur, fifteen miles west of Edwards, eight miles northwest of Balmat, and the area is often referred to as the Gouverneur district. (See Fig. 1.) At various times the district has been noted for its hematite mines, pyrite mines, and marble quarries, all now abandoned. At present, in addition to zinc, it is the country's largest source of industrial talc. A short distance to the east important magnetite mines are operating. Geologically the district lies at the southern margin of the Canadian shield, where this great expanse of Pre-Cambrian igneous and metamorphic rocks merges into the foothills of the Adirondacks. The rock formations in approximate order of areal extent and importance are as follows:

Jan 1, 1947

By Olaf B. Slostad

ONE of the essential functions of any modern community is to provide a fully accredited public school system. The Climax Molybdenum Co. was cognizant of this fact and erected a modern school building in 1937 to meet this need. The building was named after the president of the Company, Max Schott, who was largely instrumental in making it a reality. The building is a two-story brick structure with fourteen rooms, eight of which are regular classrooms. The others consist of a room for industrial arts, two for home economics, one for commercial arts, one for a science laboratory with a dark-loom for photography, and one large room for a combination library, study hall, and assembly room. All these are equipped with the most up-to-date modern equipment. The school is fully accredited by the University of Colorado. Although in a mining camp, it operates as a public

Jan 1, 1946

By J. J. Carrigan

IN all mining operations a considerable portion of the work performed, especially underground; is accomplished under artificial light, yeti this subject is often not given proper attention. Poor illumination decreases mining efficiency, impairs the sorting or grading of ores, and increases the risk of accidents. In the beginning, and for several years afterward in the metal-mining industry of Butte, Montana, candles placed in candlesticks were carried by the men. Sconces or holders for candles were also provided at stations and curves in drifts to furnish better light for men engaged in. hand tramming. It was also common practice to place clusters of candles on the ground, with no provision for guarding against an underground fire other than the exercise of sufficient care by the men themselves. An accumulation of candle grease from this source was the direct result of the first serious fire in the Anaconda mine, in 1889.

Jan 1, 1936

By K. R. Crocker

PRIMARY blasting at the open pit of the Cananea Consolidated Copper Co. has been developed to meet several conditions peculiar to the operation. Mining at Cananea is not confined to the open pit but is in conjunction with the underground mine which has been in operation for many years. Several old stopes included in the pit area were filled with waste obtained in stripping for the pit. The main haulage tunnel for the underground ore passes directly under one section of the pit and at present is but 180 ft below the pit floor. The pit as originally laid out called for an overall final pit limit slope of 60°. However, the upper 275 ft - a fairly soft oxidized capping, was carried at a 50° slope and the lower benches, which constitute 750 ft in combined height, are being mined to an over-all final slope of 60°.

Jan 6, 1950

SHORTLY after Ambrose Swasey suggested the creation of the Engineering Foundation in 1914, the World War broke. upon the scene. Consequently all eyes were soon turned to national security problems. In 1916 the newly-organized Engineering Foundation and the four National Societies joined with the National Academy of Sciences in establishing the National Research Council. From then until 1923 the Engineering Foundation devoted the greater part of its resources to the support of the Research Council and the Council's division of engineering. Since 1923, how-ever, it has turned to the original intention for which it was created, of cooperating with the national societies in proj-ects affecting engineering at large, though it still retains a connection with the Research Council. Mere enumeration and tabulation of work undertaken can of course lend but a vague idea of actual accomplish-ments. The reports of the Foundation give information of its widespread activities.

Jan 2, 1928