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By R. E. Mazurak, E. L. Ealy

At the Beckley mine in southern West Virginia, forecasting unstable roof conditions in advance of mining is accomplished by wing a rating system that combines historical information on mine roof failures with known mine geology. Failure frequency rates are derived for each category of roof rock composition, unit thickness, structure, and extraction ratio. In this manner, known geological environments are rated according to instability based on actual experience. Drill hole control and geological interpretation provide the basis for forecasting unstable conditions beyond working faces. The forecasting technique has assisted mine management in reducing fall frequencies by 80% over the past two years compared to the first five years of operation. This reduction in fall frequency was accomplished by modifying the plan of advancing sections to minimize mining exposure to unstable roof conditions.

Jan 1, 1983

By Michel L. Bilodeau

The objective of delineation drilling is to provide a data base for the tonnage and grade estimates required to evaluate the economics of mine development. As drilling information is accumulated, geological risk is reduced and more reliable estimates of tonnage and grade are obtained. Investment in drilling is justified by the benefits which result from improving the reliability of the economic criteria evaluated. These benefits are subject to diminishing returns, i.e. as drilling information is accumulated the reliability of the economic criteria evaluated is improved but at a decreasing rate. At the same time, costs are incurred -- the direct investment cost associated with additional drilling and the time cost of delaying possible production revenues. The economic sampling limit is de- fined by the point at which the marginal benefits from drilling investment just balance the marginal costs. The paper describes the formulation of an economic model to optimize investment in delineation drilling. The model is applied to a simulated mineral deposit to illustrate the economic effects of a sequential drilling program.

Jan 1, 1977

By R. M. Schuller, J. J. Suloway, W. F. Childers, R. A. Griffin, S. J. Russell

Seven solid wastes from coal conversion processes were characterized chemically and mineralogically. The wastes included three Lurgi gasification ashes, two liquefaction residues (SRC and H-coal), a fly ash, and a water-quenched slag. Leachates generated from the solid wastes at various pH levels over the range 2.5 to 11.0 were analyzed for over 40 constituents. Results of the leachate analyses demonstrate the wide variation in constituent solubility for the solid wastes. To help assess the environmental impact of the disposal of these wastes, the leachates were also employed in soil attenuation studies and acute 96-hr static bioassays using young fathead minnows.

Jan 1, 1981

By Luther Wagoner

HAVING given in a former paper1 the results of assays of sea-water, bay-mud, dredgings from San Francisco bay, etc., and' believing it might be interesting to extend the work to include' some deep-sea dredgings, I procured from the Smithsonian Institution six samples taken by the U. S, steamer Albatross, and marked as follows

Jan 9, 1907

By A. J. Naldrett, N. T. Arndt

In Archean greenstone belts, ultramafic lavas occur interbanded with basalts, commonly at the base of volcanic-sedimentary cycles. The lavas form part of a recently recognized extrusive rock series, the magnesian series, in which liquid compositions range from peridotitic (33 wt-% MgO) to basaltic (8 wt-% MgO). Rocks of this series occur as peridote, pyroxenite and magnesian basalt flows, and intrusive/extrusive bodies of dunite (49 wt-% MgO) grading outwards into a peridotitic marginal zone. The nickel sulfide deposits are of two main types: (1) basal accumulations of massive and disseminated pyrrhotite + pentlandite associated with some of the thickest and most magnesian (<40 wt-% MgO) of the peridotite flows, and (2) widespread zones of disseminated sulfides in the dunite lenses. Massive sulfide segregations may occasionally occur within the dunites.

Jan 1, 1977

EXECUTIVE COMMITTEE OF THE BOARD OF DIRECTORS W M Peirce, Chairman Philip Kraft, Vice-Chairman Francis B Foley Hjalmar W Johnson Thomas G Moore ENDOWMENT Cleveland E Dodge, Chairman C F Kelley John D Bradley Harvey S Mudd J Coulter W A Sinsheimer N Eavenson Wilfred Sykes C Jackling Clyde E Weed

Jan 1, 1951

By H. Rosenthal, A. L. Jamieson

The action of mercury on stressed brass to produce cracks was known before Moore, Beckinsale and Mallinson1 showed that actual season cracking did not occur spontaneously but could be induced by ammonia. These investigators studied other substances, including diphenylamine, without finding that anything other than ammonia could cause season cracking Grimston2 reported season cracking in cartridge cases stored in wooden boxes wetted with dilute sulphuric acid pickling solution. Season cracking associated with sulphur dioxide, water vapor and air has been reported by Johnston,3 although he reported that trimethylamine and pyridine did not cause cracking. Jevons4 has ascribed season cracking of brass in certain instances to trimethylamine, "aldehyde amine," "ketone amine" and pyridine, but no experimental work was done evidently to prove this definitely. Pyridine was investigated by Morris,5 who found it to have considerable cracking power. In the present investigation, the object was a qualitative evaluation of a number of representative amines with respect to their ability to cause season cracking. Thus it was desired only that an appreciable vapor pressure of each amine be obtained in order to make the test as severe as possible, without attempting to test equivalent concentrations for comparative purposes. MEthods Specimens TWO types of specimen were used: 1. Unannealed 70-30 brass CUPs formed from 0.040-in. thick sheet. Height of cup Was 13/8 in. and diameter was 17/8 inches. 2. First draw pieces of caliber .50 cartridge cases in the unannealed condition (70-30 brass)- The cups were representative of a thin wall and thin base specimen, whereas the draw pieces have a thick base (1/4 in.) and a thick wall (approximately 3/32 in.). Both types of specimens contained high residual stress and cracked in less than one minute in a solution of I per cent mercurous nitrate and I per cent nitric acid provided that this was receded by a 30-sec. pickle in 40 per cent nitric acid. Specimens were prepared as follows: (1) degreased in trichlorethylene, (2) rinsed in H2O, (3) pickled 5 min. in 10 per cent by volume H2SO4 (1.84 SP. gr.), (4) rinsed in H2O, and (5) dried. Amirtes Tested In selecting the amines, representatives of the three series of amines, and one series of substituted amines were chosen. The aliphatic series was represented by the methyl and ethyl primary, secondary and tertiary amines. These are the simplest aliphatic amines. For the aromatic series, the phenyl primary, secondary and tertiary amines were selected as being the simplest. The heterocyclic series was represented by pyridine, which is a simple heterocyclic base (tertiary amine).

Jan 1, 1944

By Bertrand Robinson

Epitomized, there have been no innovations recently in crushing, but in grinding the trend has been towards larger units under more automatic control with an increased use of autogenous grinding. Crushing Portability of primary crushers to "follow the face" reduces material handling costs. The top size of crusher feed still establishes the size of the crusher; the feed opening should be 1 1/2 times the size of the largest feed. The maximum size of crusher product is 1 ½ times the open scale setting of a jaw or gyratory crusher. Practice dictates use of scalping screens ahead of any type of crusher when the feed contains 25% or more of product size. If required capacity is under 600-700 tph economics favor a double toggle crusher or an impactor. For larger capacities the gyratory crusher is favored.

Jan 1, 1970

By Charles Malcolmson

AN elaborate series of experiments has been conducted during the past three years at Irvington, N. J., which has resulted in the perfection of a process for the manufacture of smokeless fuel from high-volatile coals, and for the recovery and refinement of the coal-tar products derived therefrom. These experiments have been financed by Messrs. Blair Co., of New York, and were conducted under the direction of Charles H. Smith, a member of this Institute, and the inventor of the process. The low-temperature distillation of coal has interested investigators for many years. Sporadic attempts have been made to solve the mechanical problems, but until the Smith process. was developed, they were not carried to conclusions of economic value. The present coal shortage and the increasing demand for smokeless fuels make this subject one of timely interest.

Jan 5, 1918

By L. T. Hiaains

EVEN before the surrender of Germany, a gradual reduction in output of many of the small mining iseswises in the different countries of South America had occurred. Part of this was due to restricted purchases of strategic mineral supplies, and part to economic conditions. Inflationary tendencies have keen increasing since the war started; out in the past three years they have become serious. The difficulty in obtaining supplies, and labor troubles, has also combined to reduce production in many circumstances. British Guiana The Cuyuni Goldfields, Ltd., operating he Aleck Hill mine, is increasing their yanked mill to 500 tons. This appears be one of the few important new developments in South America during recent years. Brazil The big Volta Redonda steel plant was sported as being ready to start operations. Argentina Political troubles have restricted activities during the past year, and fuel short. ges have been so acute that surplus corn as burned in some instances. Practically all the tungsten producers ther closed down entirely or reduced

Jan 1, 1946

By Milton H. Fies

THE Alabama Power Co. operates its Gorgas mine in Walker County, Ala., immediately adjacent to its steam plant. The coal mine property consists of some 19,000 acres of fee and mineral ownership lands, and all of the production from the mine-approximately 2500 tons per day-is utilized at the company&apos;s adjoining steam plant. The company is presently considering the purchase of additional acreage adjoining its present holdings which acquisition will almost double its reserves. The coal is transported from the mine over a short railroad spur in the company&apos;s own equipment, either directly to one of the large plants at Gorgas or to a storage pile. The longest haul is about 1 1/4 miles.

Jan 12, 1950

By T. F. Petty

During 1935 there were drilled in North Central Texas 1071 wells, of which 565 were dry holes, 469 were oil wells with an initial production of 43,766 bbl. and 37 were gas wells with an initial production of 129,332,000 cu. ft. Production has been 14,180,042 bbl., or a daily average of 38,849 bbl. In Table 1 are listed the various pools of the district. Most of the smaller pools are of minor importance and are merely productive spots. Numerous other similar spots might have been listed as pools but their production is included in other fields. There are a few flowing wells but practically all of the wells are being pumped. The estimated potential is about 50,000 bbl. and the allowable production is based on the Texas Marginal Well Law. In Table 2, wildcat wells that have resulted in the discovery of pools or important extensions to old pools or that have contributed to the geological information of the area are listed.

Jan 1, 1936

By T. F. Petty

During 1935 there were drilled in North Central Texas 1071 wells, of which 565 were dry holes, 469 were oil wells with an initial production of 43,766 bbl. and 37 were gas wells with an initial production of 129,332,000 cu. ft. Production has been 14,180,042 bbl., or a daily average of 38,849 bbl. In Table 1 are listed the various pools of the district. Most of the smaller pools are of minor importance and are merely productive spots. Numerous other similar spots might have been listed as pools but their production is included in other fields. There are a few flowing wells but practically all of the wells are being pumped. The estimated potential is about 50,000 bbl. and the allowable production is based on the Texas Marginal Well Law. In Table 2, wildcat wells that have resulted in the discovery of pools or important extensions to old pools or that have contributed to the geological information of the area are listed.

Jan 1, 1936

The. Library of the above-named Societies is open from 9 A. M. to 10 P. M. except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and, photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 3, 1919

By Richard P. Rothwell

THOUGH coal has been mined in this country for more than a century, no systematic effort was ever successfully made to ascertain the total amount produced. The production of the Cumberland Basin, Md., and the shipments from the anthracite fields of Pennsylvania, have been placed upon record, thanks to the intelligence sand foresight of Mr. C. Slack in the former case, and to the late Mr. B. Bannan in the latter. For some of the years between 1822 and 1842, the production of the Richmond Basin was reported by Mr. R. C. Taylor, but since that date till the author undertook this work it was impossible to obtain any statement of the production of this field. A few of the newer fields, such as that of Mt. Diablo, Cal., have been fully reported, and a few of the newer States have also had this service performed by some intelligent private individuals.; but no statistics of coal production have ever been collected either by the State or General Government, if we except the returns for the years 1869-70 of the census report. During the year 1875, by great exertions, I succeeded in obtaining, and July 3d, 1875, gave in the Engineering and Mining Journal what, "though not an accurate statement of our coal production," was " by far the most full and reliable that had ever been published." Though that report showed the production of bituminous coal to be 23,630,094 gross tons, or about six million tons more than had ever before been reported, it was in reality two and a half million tons below the actual output. The more full returns I obtained for 1875 gave many figures for 1874

Jan 1, 1877

By J. L. Weeks

THERMAL conductivities of several samples of uranium and uranium alloys were determined using an apparatus previously described.&apos; The value previously reported for uranium,&apos; 0.035 cal per sec per cm per "C at 70°C, is in error due to the failure of a thermocouple during the determination on uranium. The defective thermocouple was detected after a reanalysis of the data obtained during the run and since has been replaced. Subsequently, runs on several samples of uranium show the thermal conductivity of uranium to be 0.069 cal per sec per cm per &apos;C at 70°C. The accuracy of the determinations was checked by measuring a sample of synthetic sapphire whose thermal conductivity was previously reported and found to be in agreement with other values."-" The values given in Table I are believed correct to % 3 pct or 0.003 cal per sec per cm per "C, whichever is larger. The samples were provided by J. H. Kittel of the Argonne National Laboratory, Metallurgy Div. References J. L. Weeks and R. L. Seifert: Apparatus for the Measurement of the Thermal Conductivity of Solids. Review of Scientific Instruments (1953) 24, pp. 1054-1057. J. L. Weeks and R. L. Seifert: Note Regarding the Thermal Conductivity of Synthetic Sapphire. Journal American Ceramic Society (1952) 35, p. 15. :&apos; J. Francl and W. D. Kingery: Thermal Conductivity: IV, Apparatus for Determining Thermal Conductivity by a Comparative Method; Data for Pb, Al2O3, BeO, and MgO. Journal American Ceramic Society (1954) 37, No. 2, Part 11, pp. 80-84. (Part 11: special issue on thermal conductivity.) &apos; W. D. Kingery, J. Francl, R. L. Coble. and T. Vasilos: Thermal Conductivity: X, Data for Several Pure Oxide Materials Corrected to Zero Porosity. Journal American Ceramic Society (1954) 37, No. 2, Part II, pp. 107-110. (Part 11: special issue on thermal conductivity.) Edwin Ruh: New Jersey Ceramic Research Station, Rutgers University. Private communication.

Jan 1, 1956

The Library of the above-named Societies is open from 9 A.M. to 10 P.M., except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information&apos; will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should be made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 2, 1918

By G. K. Zaharlev

With a productive output growing at an annual rate of 8%, the Soviet mining industry should emerge as the world&apos;s leader in total mineral output during the 1980&apos;s. (The Soviet Union&apos;s share in the world&apos;s total mineral output in 1973 was estimated at 22 to 23%.) According to estimates by Soviet mining experts, the mineral potential of the Soviet Union will sustain the current 8% annual growth rate in the future.

Jan 12, 1974

By T. B. Counselman

WHEN one thinks of Minnesota iron ore, one thinks of big open pits, where high- grade ore is simply scooped up with a power shovel, loaded into cars, and hauled away for shipment to the blast furnace. On the western end of the Mesabi range, however, are large tonnages of iron ore which contain too much silica to be used directly in the blast furnace, and these ores must first be concentrated to a purer form. The Mesabi range is about 100 miles long and a maximum of 3 miles wide. The iron formation, which in its unaltered form is called taconite: consists of a banded iron- bearing chert. Where the high-grade ore bodies occur, these have resulted from folding and cracking with sub- sequent leaching out of the silica, leaving the iron oxide behind. The big open pits and the underground mines are situated in these concentrations.

Jan 1, 1941

D. K. CRAMPTON, Chairman EDMUND M. WISE, Past-Chairman CYRIL S. SMITH, Vice-Chairman CARL E. SWARTZ, Vice-Chairman H. A. MALONEY, Treasurer Executive Committee 1942 1943 FRANCES H. CLARK ERIC R. JETTE W. L. FINK LOUIS W. KEMPF J. T. NORTON GEORGE SACHS 1944 WILLIAM C. ELLIS ALAN MORRIS KENT R. VAN HORN Finance JOHN L. CHRISTIE, Chairman J. R. FREEMAN, JR. H. M. ST. JOHN W. M. PEIRCE JEROME STRAUSS

Jan 1, 1941