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(There are 67 Student Chapters in the United States, 2 in Canada ) University of Alabama-University, Alabama, Mining & Metallurgical Society, James W Stewart University of Alaska-College, Alaska, Mining Society of the University of Alaska, Guinn Metzger University of Arizona-Tucson, Arizona, Miners' Society, A E Gorum Birmingham-Southern College-Birmingham, Alabama, Pick & Hammer Club, Daniel D Arden University of British Columbia-Vancouver, British Columbia, G M Dawson Club, A Gunning University of California-Berkeley, California, Mineral Technology Association, Bernard York Carnegie Institute of Technology-Pittsburgh, Pennsylvania, The Metals Club, Gerhard Derge Case Institute of Technology-Cleveland, Ohio, Pick and Shovel Club, Gerald M Cover City College of New York-New York, New York, CCNY Student Chapter AIME, Daniel T O'Connell

Jan 1, 1954

By Paul M. Tyler

MUCH information concerning pegmatites which was thought to be true a few years ago has been proved false, and what is now actually known about some pegmatites is not true of many others. The erratic and seemingly unpredictable structure and variable composition of this class of mineral deposits has been widely emphasized. Even parts of the same pegmatite body exhibit marked differences in texture, mineral composition, width, and attitude. Constructive geological thinking in respect to pegmatites now aims to establish general laws rather than to stress the confusing diversity of features having no special economic significance.

Jan 9, 1953

By A. D. Hughes

A relatively small area in Malaya, about 200 miles long by 40 miles wide, is the most important source of tin in the world. Some tin is recovered in other parts of the peninsula. Of the tin mined, 98 pct is recovered from alluvial deposits. From 1935 to 1941 the average annual world production of tin was 190,000 tons. The average annual production from Malaya during the same period was 62,000 tons or about one third of the total. Other producing countries, in order of importance, were the Netherlands East Indies 34,000 tons, Bolivia 30,000, Belgian Congo, Nigeria, Siam, Burma, China, and a few others with smaller amounts. The serious shortage of tin during the war period was due to the fact that the Japanese were occupying Malaya, Netherlands East Indies, Siam, Burma, and China which, together, formerly were producing 65 pct of the world supply.

Jan 1, 1949

By Harry K. Ihrig

Jan 1, 1947

By Harry K. Ihrig

Jan 1, 1947

By R. Schuhmann

D. W. Fuerstenau (Associate Professor of Metallurgy, Dept. of Mineral Technology, University of California, Berkeley, Calif.) In his excellent paper, Dr. Schuhmann has proposed a mechanism for conlrninution which can be utilized to explain a number of phenomena which have been observed in the size reduction of solids. The difference between the product obtained from a ball mill and from a rod mill can readily be explained by Dr. Schuhmann's hypothesis. Consider that the size distribution of the product from each comminution event is given by y; - 100 (x/ki) (1) where Yi is the cumulative percent finer than size x, ki is the size modulus, and is the distribution modulus for the single comminution event. The total product from a cornminution operation will be the summation of the products from all of the individual cornrninution events. If the size moduli from the various comminution events range from kl to kn , the size distribution of the total product will be a straight line on a log-log plot only to a particle size equal to k ,. Considering 100 volurnes of feed, the value of y for x equal to kl is Riven by where y is the cumulative percent finer than size kj, z is the number of comminution events of kind i, and vi is the volume of each particle crushed. y=z1 qv1+z2 qv2 (k1/k2) +.............zn qvn (k1/kn) (3) F or particle sizes greater than k1 7 e. 6. x = k3, the value of y will be given by k3 A y = z1 qv1 + z2bv2 + Z3uV3 + zn zn qvn (k3/kn)(4) Only when x is equal to k, will y equal 100. 'Thus, the total product from a comminution operation will be a straight line on a log-log plot strictly up to a particle size equal to kl and above that size the line will curve so that y will equal 100 for the coarsest particle or k, (see Fig. 1). The actual shape of the size of distribution curve will depend upon the relative number of conmninution events of different kinds. In the case of ball milling, the ratio kn/kl may be pite large and there will be considerable deviation at the coarse sizes in a Schuhmann plot. kIowever, the grinding action in a rod mill is such that fine particles are protected from the rods by the coarse particles. Consequently, kn/kl will be quite small and the product from a rod mill will give a straight line Schuhmann plot almost to y equal 100%. In his paper, Dr. Schuhmann also has presented a very straightforward definition of grindability derived from the basic energy equation E = Ak-a (5) where E is the energy required to comminute a material to a size modulus of k and A is a constant. According to Dr. Schuhmann, the grindability of a material is the volume of material comminuted finer than unit size per unit of energy expended, this being 1/A. For comparison of grindabilities at any size two numbers are required, both = and 1/A, and anyone tabulating grindabilities should give both of these numbers. Concerning the experimental determination of grindabilities, if the material being comminuted possesses distinct cleavage, the energy re quired for comminution is given by E = Ak-(a-y) (6) where y is small number less than = . Because of cleavage, less energy will be required for comminution. To be certain that cleavage does not affect the gindability of the material being tested, it is suggested that the method used by Dr. Charles for determining grindability be used to ascertain if the deviation exponent y is zero or finite. R. Schuhmann, Jr. (Author's Reply) Dr. Fuerstenau's interesting comparison of rod milling and ball milling

Jan 1, 1961

By R. V. Norris

In a former paper on this subject,' I summarized Murgue's theory and experiments, and presented a large number of tests of mine-fans, stating some conclusions, " more or less warranted by the evidence," as to design, capacity and efficiency. Since that time the very valuable report of Mr. M. Walton Brown: Committee on Mechanical Ventikators, Institution of Mining Engineers, has appeared, and I have made additional experiments which tend to clear up some points in connection with this subject. Design and Tests of the Luke-Fidlbr Colliery Fan. The Luke-Fidler fan (see Figs. 1, 2 and 3), built to replace an old wooden fan at a very fiery colliery, presents some pecu-

Jan 1, 1905

By I. R. Taylor

Union Carbide has recently developed two open- pit vanadium mines in the Wilson Srpings area of central Arkansas about five miles southeast of Hot Springs. The ores from these mines, together with those from a larger vanadium deposit at nearby Magnet Cove, are processed at a new 1600- tpd plant built by the company in the immediate vicinity (Fig. 1). The Wilson Springs vanadium deposits are associated with the Potash Sulfur Springs intrusive, a circular igneous complex which is exposed over an area that is somewhat less than a mile in diameter.1 The complex has a crude ring structure similar to that of the larger Magnet Cove instrusive six miles to the east.2

Jan 4, 1969

Jan 1, 1936

Jan 1, 1969

By Chester O. Ensign

Results of the application of geologic knowledge to grade control have been remarkable. Grade reduction from dilution has been diminished from greater than 9% at the time of the program's beginning to about 2% at present. This has resulted in an increase of about 1.8 lb of copper per ton of ore mined and has made a substantial contribution to earnings at White Pine during the past two years. Even more improvement is expected in the future. The White Pine orebody, situated in the southwestern portion of the Keweenaw peninsula of upper Michigan, is a gently dipping stratiform or bedded deposit. Copper distribution is stratigraphically controlled with higher values being confined to specific beds in the ore column. Room-and-pillar mining is practiced. Mining technique and geologic characteristics present a special array of problems in controlling the grade of ore.

Jan 4, 1964

EXECUTIVE COMMITTEE OF THE BOARD OF DIRECTORS W E WRATHER, Chairman A B KINZEL -EARLE E SCHUMACHER DONALD H MCLAUGHLIN - JOHN R SUMAN FINANCE COMMITTEE OF THE BOARD OF DIRECTORS ERLE V DAVELER, Chairman PHILIP KRAFT - CLYDE E WEED

Jan 1, 1952

By D. Harrington

WHEN the word gas is mentioned in connection with mining, almost invariably it is inferred that the explosive gas, methane, is in mind and that it must refer to coal mining. While it is true that methane occurs, or is likely to occur, in almost any or all coal mines, it is also a fact that the metal mines of the world have in them by far a greater variety of gases than have the coal mines. In many cases the gases in metal mines are as dangerous to individuals as the gases likely to be found in coal mines; in some instances the metal mine gases are even more deadly. The coal mine is more likely to have methane than the metal mine, in rare instances it may have high percentages of nitrogen or high carbon dioxide, or there may be a deficiency of oxygen where the air is confined in a blind end or in a sealed region; much more rarely there are found in coal mines in relatively small percentages, ethane, or other hydrocarbons with odor of ether, gasoline or kerosene, or there may be minute percentages of hydrogen sulfide. In time of coal mine fire or explosion, there is likely to be high carbon monoxide (4 per cent. or over in some cases) and if the coal contains much sulfur, there may be some sulfur dioxide in the fire fumes. In metal mines there are a number of cases of occurrence of methane and attendant explosions; some metal mines have appreciable percentages of the decidedly explosive hydrogen; in some metal-mining regions carbon dioxide flows into the mine, fills the workings and overflows just like water. In other regions, at many working faces there are high-temperature gases containing a mixture of gases of sulfur (sulfur dioxide, hydrogen sulfide and possibly SO3 in some cases) together with carbon dioxide and nitrogen, and the deadly hydrogen sulfide in lethal proportions is found in some high-sulfide metal mines at blasting time. Carbon monoxide constitutes a decidedly dangerous day by day hazard in connection with metal-mine blasting, because of the heavy charges of dynamite that are used and the use of fuse, which in burning gives off much carbon monoxide. The poisonous gas hazard is accentuated because of the relatively small openings where metal-mine blasting is done and to the inefficient ventilation of the usual metal mine.

Jan 1, 1930

By W. Joseph Schlitt

The types of copper leaching and recovery operations in the United States are reviewed, along with characteristics and trends in the industry. The contribution of the various leach operations to total mine output is discussed in order to provide a perspective on the relative importance of copper leaching as a method of production.

Jan 1, 1980

The following is an incomplete list of members and guests who called at Institute headquarters during the period Feb. 10, 1919, to Mar. 10, 1919. R. H. Allport, Cleveland, Ohio. R. R. Landon, Philippine Islands. I. H. Bergstein, New York. Alfred 0. Law, Cambridge, Mass. Capt. R. S. Burdette, San Antonio, Tex. James M. Little, Towanda, Pa. William R. Chedsey, State College, Pa. F. E. Marcy, Salt Lake City, Utah. L. R. Clapp, Philadelphia, Pa. H. F. Nash, Bartlesville, Okla. J. Murray Clark. L. S. Panyity, Columbus, Ohio. E. H. Claussen, San Francisco, Calif. W. C. Ralston, Reno, Nev. George E. Collins, -Denver, Colo. T. A. Rickard, San Francisco, Calif. George L. Collord, Sharpsville, Pa.. W. A. Rigby, Mt, Vernon, Iowa. William M. Corse, Mansfield, Ohio. H. H. Rowatt, Ottawa. Frank R. Crampton, Los Angeles, Calif. P. H. Royster, Pittsburgh, Pa. Capt. E. 0. Daue. Alan B. Sanger, Dorchester, Mass. A. E. Eddy, Butte, Mont. J. S. Shaw, Pittsburgh, Pa. N. H. Emmons, 2d, Lynchburg, Va. S. B. Shutts, Lynchburg, Va. E. W. Engelmann, Hayden, Ariz. Henry B. Smith, New Britain, Conn. F. A. Fahrenwald, Cleveland, Ohio. W. C. Smith, Roselle, N. J. 0. S. Finnie, Ottawa. Harry M. Spoor. John T. Fuller, Honesdale, Pa. D. M. Stackhouse, Johnstown, Pa. Major C. C. Griggs, Eureka, Utah. F. D. Stay,. Cleveland, Ohio. H. F. E. Gamm, Rutherford, N. J. D. B. Sterrett, St. Cyr, Que. A. W. Hackwood, Butte, Mont. R. H. Thayer, Yonkers, N. Y. C. L. Horne, Roanoke, Va. Kirby Thomas,. New York. B. B. Hood, Chrome, N. J. Henry Traphagen, Toledo, Ohio. R. E. Hore, Toronto Ont. H. D. Trounce, San Diego, Calif. Ross B. Hoffmann, Oakland, Calif. Henry J. Volkin, Ossining, N. Y. G. A. Joslin, Salt Lake City, Utah.. A. T. Ward, Bellefonte, Pa. John Johnston, Washington, D. C. Major L. W. Wickes. Paul S. King, Wilmington, Del. Horace V. Winchell, Minneapolis, Minn. E. William Kohl, Jr., Philadelphia, Pa. Fred L. Wolf, Mansfield, Ohio. W. H. Landers, San Francisco; Calif. J. Carson Adkerson, of the Stockwood Realty Corpn., Inc., of Woodstock, Va., writes that they are discontinuing their operations in Virginia on account of the conditions in the manganese market following the end of the war.

Jan 4, 1919

By Roger M. Zimmerman

The G-Tunnel heated block experiment is being conducted on the Nevada Test Site (NTS) as part of the Nevada Nuclear Waste Storage Investigations project (NNWSI). The purpose of the ambient temperature testing ph se is to evaluate rock-mass mechanical properties of a block (- 8 m3) under biaxial stress changes up to 7.5 MPa above an initialization in situ value of 3.1 MPa. Results indicate that the modulus of deformation ranges from 9.7 to 17.0 GPa and Poisson's ratio ranges from 0.21 to 0.33. In general, the higher values of the modulus and Poisson' s ratio were influenced by fracture propagations parallel to the compressive stress field. Other measurements indicated that cross-hole compression (p) wave velocities and single fracture permeability values were relatively insensitive to stress changes above the in situ value.

Jan 1, 1984

By Robert W. Bergmann

Twenty years ago, the standard voltage for stripping machines was 4160 v and few people even thought of using a higher voltage. It was adequate for the machines of the day, which seldom exceeded 2500 hp, and higher voltages were considered to be too expensive and even dangerous. Then, in 1956, a 4500-hp machine was placed in operation and it was determined, with some reluctance, that it should operate on 7200 v. The next step, to 14,400 v, was taken in 1964 and the latest, but perhaps not final, step was made in 1967, when voltage was increased to 25,000 v. Today, 4160 v is considered almost obsolete and 7200 v is generally considered standard. However, a few mines are using 14,400 v and some eight machines soon will be operating on 25 KV, indicating that the technical and safety problems have been solved and that there must be some merit to the higher voltages. Thus, it is logical to question, "How do I determine the best voltage for my operation?"

Jan 12, 1972

The General Electric Co., in cooperation with the Montana School of Mines and under a research grant from the Anaconda Co., is presently experimenting on a new non-explosive method of breaking rock with radio-frequency electrical power. The method is known as electrothermal forcing. It must be understood that present equipment has not been designed to perform primary blasting functions. Its conceived use will be restricted to small pieces of rock too large to pass through a chute or grizzly. However, even this use is still far in the future. Experiments to date have been limited mostly to rock smaller than 18 in.

Jan 11, 1961

By W. R. Johnson

In the spring of 1935 the writers undertook to compare the geomagnetic and direct-current earth-resistivity methods of tracing a concealed dike along its strike. As far as they are aware no such direct test has been attempted.# The area surveyed lies along United States Highway number 15 about one and one-half miles east of Chapel Hill, North Carolina, and northeast of Bolin Creek (Fig, 1). To the south of the highway is the flood plain of Bolin Crook, and to the north is a hill that rises almost to the elevation of Chapel Hill. A diabase dike, which strikes slightly west of north, out-crops in a. gully just south of the highway. Southward it has been covered by alluvium but northward outcrops again on the southeastern slope of the hill north of the highway. South of the highway the country rock is Triassic shale and sandstone, the northern limit of which is slightly north of the road. On the Geological Map of the United States I the pre-Triassic formations are shown as lower Glenarm and assigned a pre-Cambrian age. Since the ago of the Glenarm has been called into question in Pennsylvania 2, the writers prefer not to commit themselves as to the ago of these rocks further than to say that they are definitely pre-Triassic.

Jan 1, 1937

By Edwin B. Johnson

The success of self-fluxed sinter in enhancing the operation of the blast furnace during the past few years has reasonably led to the assumption that the use of self-fluxed pellets might result in even greater furnace efficiencies. A great share of development work in agglomeration has been directed towards techniques related to the production of self-fluxed pellets, but no appreciable tonnage of self-fluxed pellets had been produced on a commercial scale until this past year when The Cleveland-Cliffs Iron Co. produced 35,000 tons of such pellets by the grate kiln system at the Republic mine during the period May 21-June 5, 1962.

Jan 3, 1963