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By John L. Hill

Cutter roof failure is a specific type of ground control problem which frequently results in massive roof failure. It is a common occurrence in coal mines of the Northern Appalachian Coal Basin, causing delays in production and posing a safety hazard to mine personnel. The Bureau of Mines is conducting research on the causes of cutter roof failure to gain a basis from which to prevent its occurrence and to support such roof when failure does occur. Research conducted in a coal mine of central Pennsylvania has revealed a correlation between the occurrence of clastic dikes and formation of cutter roof failure. In-mine mapping of ground conditions showed an increase in roof failure in areas of high frequencies of clastic dikes. Rock pressure monitoring around clastic dikes registered the greatest amount of roof loading near the intersection of dikes with the rib. Load cells measuring horizontal pressure changes in the roof indicated that the greatest pressure changes were occurring perpendicular to entry headings when clastic dikes were present. Analysis of rock pressure monitoring shows that the roof behaved as two cantilever beams when severed by a clastic dike. Additional roof supports such as trusses and cribbing were found to effectively support the roof in areas of clastic dikes and prevent cutter roof failure. However, these methods were only successful when employed shortly after mining.

Jan 1, 1984

By L. J. Howell, H. H. Kellogg

AN a previous paper' the phase diagram and vapor pressure of melts in the systems NaC1-ZrCl,, KC1-ZrCl,, and NaC1-KC1 (1:1 molar)-ZrC1, were reported. This note supplements the earlier paper with the results of electrical conductivity measurements on NaC1-ZrC1,and NaC1-KC1 (1:l molar)-ZrC1, melts. The design of the conductivity cell is shown in Fig. 1. Tungsten electrodes, A, were sealed into the Pyrex cell, C. That portion of the electrodes in contact with the melt was covered with a tight-fitting platinum cap. The electrodes were sur-

Jan 1, 1960

To Install Waste Heat Boiler at White Pine White Pine Copper Co.'s smelter 18 miles southwest of Ontonagon, Mich., will have a six story high boiler utilizing what otherwise would be waste heat from a copper reverberatory furnace. Designed and under construction by the Babcock & Wilcox Co., the boiler will supply steam to a turbo-generator furnishing power for the projected development. The boiler will be in line with and following the reverberatory furnace. Using waste heat from the furnace in place of fuel for steam generation, about 50 pct of heat in the fuel originally supplied to the furnace will be recovered by the waste heat boiler. Exploration conducted over the past 15 years at White Pine, wholly owned subsidiary of Copper Range Co., has disclosed reserves of 309 million tons averaging 21.3 lb of copper per ton. Ore mineral is chiefly chalcocite (Cu2s).

Jan 5, 1953

By W. A. Van Voast, J. J. McDermott, R. B. Hedges

Many coal beds that will be mined in southeastern Montana are aquifers that provide essential local water supplies. Mine cuts along aquifer outcrops create almost imperceptible piezometric changes. Monitoring near such operations at Colstrip has detected almost no water-level declines in observation wells. Mine cuts between outcrops induce rapid storage depletion and associated piezometric depressions. One such cut near Decker induced 12.50 mj/day of flow from storage and created a piezometric depression of 3 m or more as far as 1500 m from the mine. No wells have yet become nonproductive but losses of some are inevitable as operations expand. Alternative supplies are available from aquifers stratigraphically below the disturbed materials. Effluents from active mines are chemically similar to other area waters because they are mixtures of ground waters entering the mine cuts. Occasional high concentrations of nitrate do occur, however, as residuals from explosives. Spoils generally consist of confined aquifers of wasted coal and coarse rubble at their bases, overlain by finer-grained sand,

Jan 1, 1980

By J. E. Spurr

The region here discussed is that part of Western Nevada in which. during the last few years. discoveries of rich gold- and

Jan 1, 1906

By Arthur V. Abbott

TO rightly use materials, two kinds of knowledge are essential: first, the actual strength of the substance; and secondly, the forces to which, in the structure, it may be subjected. Nearly all of the data which we have at the present time have been obtained from the experiments made on the materials used in Europe, and by foreign investigators. The materials commonly used in this country, es-

Jan 1, 1884

By B. M. Andreas

PRIOR to 1934 all haulage of ore and stripping on the Mesabi Range was by rail. Early rail systems had small narrow-gage locomotives with correspondingly small dump cars. These trains were replaced with larger standard gage rail systems powered by steam locomotives ranging up to 224 tons in weight, which have in turn been replaced by diesel electric locomotives. Along with this development cars have been increased to 30-cu yd capacity. Improvement of cars includes alloy steel construction for lower over-all weight and use of roller bearings to decrease rolling resistance. Despite all of these developments, the total material hauled by rail on the Mesabi Range has decreased every year. Yet, this is no reason to believe that rail haulage is becoming obsolete. Its adaptation to small mine operation has become impractical, but in large mines where normal railroad grades are possible or where hauls to plants or dumps are long, rail haulage is still one of the most economical methods of transporting large quantities of material.

Jan 1, 1954

Visitors frequently put the question to Kalgoorlie gold miners; "Why don't you concentrate your mining operations?" A mine may be drawing ore from over a hundred different working places which are spread out over several thousand feet of strike and on many different levels. The answer to this question is that "finished" can rarely be written for a section of the mine. The intricate web of mineralization in faults, shears and fractures is an endless puzzle, each solution opens up new avenues to be explored. After the last ore is taken from a stope, a program of drilling may continue for several weeks on different possibilities. Perhaps no ore is discovered and drilling is abandoned, but it is not unusual for another search to begin later in that same area on a new theory with successful results. Wherever a slightly richer mineralization is found, it is needed to "sweeten" the mill heads. Over seventy years ago gold was discovered in the dry wastes of Western Australia. Rich deposits of alluvial gold were found at first and as these were worked out they led to the discovery of the lode ores, which were leaner and harder to extract.

Jan 10, 1964

By Robert C. Bolger, John H. Weitz

REFRACTORY clay, one of Pennsylvania's important nonmetallic mineral resources, occurs at several horizons in beds of Pennsylvanian age. The Mercer fireclay, of Pottsville age (Table 1), is the most important of these clays. A study of this fireclay has been conducted by the Pennsylvania Geologic Survey discontinuously over a period of seven years. The work has included field mapping of a rather large area, as well as petrographic, differen¬tial thermal, and X-ray studies of the fireclay. A comprehensive report on the project is now in preparation.

Jan 1, 1952

By M. E. Volin, F. H. Erbisch, G. M. Wenberg

Bacterial leaching of copper and uranium is practiced under acidic conditions in environments furnishing sulfur and iron. However, many mineral deposits do not have these conditions; the chalcocite and native copper deposits in Michigan's Upper Peninsula are examples. Species of bacteria and fungi isolated previously from samples taken at the White Pine Copper Co. tailings pond and mine, were screened for solubilization of copper from chalcocite ore and flotation concentrate and from native copper jig concentrate. Certain Penicillium species solubilized significant amounts of copper under neutral to slightly acidic conditions in a carbon and nitrogen-enriched medium. Leaching apparently was accomplished by release of metabolites which chelated with the copper. The copper yield was highly dependent upon the medium composition and the concentration of copper in the source material. The standardized procedures which were developed in an attempt to maximize copper yield in leaching times of three to five days are described. This preliminary research indicates a biological leaching process for copper which is different from those in use, but whether it can be applied economically remains to be determined.

Jan 1, 1972

By H. N. Lawrie

This study was undertaken on account of the lack of definite knowledge concerning the influence of bismuth on wire-bar copper, and the small elimination of bismuth from copper-matte during the smelting-operations. The early workers who studied the influence of bismuth on copper confined their investigations to malleability and ductility—two physical properties which are related to the others so intimately that their determination is of primary importance. Karsten and Levo1,² using bending- and mealleability-tests, seem to have been the first to take up the subject, and while their results are incomplete, they agree in the main with the later work of Hampe.3 The bending-tests used by the first investigators consisted in bending the specimen until it failed. The malleability-tests were made by beating the material to a knife-edge with a hammer. Hampe not only determined the percentage of bismuth which would cause red-shortness and cold-shortness of the alloy, together with other influences of bismuth on the malleability and ductility of copper, but also took up the influence of the bismuth protoxide, BiO, on copper, and of bismuth sesquioxide, Bi,O,, on the copper protoxide, CuO. Hampe's conclusioris of the influences of these two latter compounds of bismuth on copper are as follows : "If the protoxide of bismnth be alloyed with metallic copper, it is not changed to metallic bismuth, but remains mechanically distributed throughout the copper.

Jan 1, 1910

By James E. Jopling

The county of Marquette, Michigan, includes nearly all the iron-mines that have been worked on the Marquette range, which stretches in a generally western direction from the mines at Negaunee, 10 miles from Lake Superior, to those beyond Michigamme, some thirty miles further. The geographical position of this range, nearer to eastern ports than the other iron-ranges, and its ready access from the lake, gave it for a long time a controlling advantage. The country in which the mines are situated is from 800 to 1000 feet above the level of the lake, and is for the most part broken by steep hills, which rise from 100 to 200 feet; between these the land is rolling or

Jan 1, 1898

By Lester Woolsey

THE State Department can be of assistance to Americans in the petroleum business directly and indirectly. During the past few months, at the Arms Conference, it had a large hand in dealing with affairs indirectly affecting the oil problem. The conference has somewhat relieved the emphasis on naval strategy in relation to oil supply by limiting the number of naval vessels or the fleets of the Great Powers and in maintaining the "open door" in the Far East in respect of the development of the natural resources of that region by defining that policy in a nine-power treaty. The largest competitors of the. United States in the petroleum field are parties to that treaty. The Department of State also has stood steadfastly for the principle of equal opportunity in the Dutch East Indies, Mesopotamia, and Persia. The Department of State has been of indirect assistance in connection with oil problems by insisting on the recognition of treaty rights and other guar-antees, such as most-favored-nation clauses, and mandate provisions. I am not speaking as a representative of the Depart-ment of State, as L now have no connection with that institution, but my experience of several years as a member of the department and my practice since my resignation have given me opportunity to see the department from both the inside and the outside, and to measure its limitations as well as its resources.

Jan 7, 1922

By Franklin Bache

It is appropriate to the place of meeting, and of interest to those members of the Institute whose attention has been more or less directed to Virginia during the past eleven years, to know the result of recent developments of the Virginia coal-field. While, during the late " boom," the attention of the industrial pioneers of Virginia was mainly directed to iron-ore deposits and manufacture, it is safe to say that the coal to which, at that time, comparatively little attention was turned, and which did not directly foster a growth of " boom " towns, will prove the most reliable source of mineral wealth in the State. At the time of the last Virginia meeting of the Institute, held at Roanoke, in 1883, the Wise county coal-field was untouched by a railroad, and its economic existence was scarcely considered. Although, in the meantime, a number of reconnaissances had been made, and a fair estimate of the value of the field formed, it was not until 1891, when the Norfolk and Western and the Louisville and Nashville railroads, respectively, completed their Clinch Valley and Norton extensions to a junction at Norton, Wise county, that any development took place, and not until 1892 were shipments of any importance made. The coal-measures of Virginia are confined to the seven counties of Buchanan, Tazewell, Dickenson, Russell, Scott, Wise, and Lee,

Jan 1, 1895

J. L. McK. YARDLEY,* Pittsburgh, Pa. (written dlscussion ?) .-It is interesting to observe how closely Mr. Hansen agrees with other investigators to the effect that the art of electrolytic zinc has left the realm of mystery. In his introduction, lie has said practically what Thomas French said in his paper "The Future of Electrolytic Zinc. "1 The successful electrolysis of zinc from sulphate solutions has not been an easy matter, and it is only within recent years that the difficult problem of depositing high-grade zinc has been satisfactorily: accomplished on a commercial basis. The principal requisite is. that the electrolyte shall be quite free from certain impurities. The methods by which freedom from these impurities is assured are now very well understood, and with experienced superintendents there is little difficulty in obtaining a high efficiency in that part of the process. When certain underlying principles are recognized, the difficulty encountered in dealing with the filtration of the acid and slimy solutions also largely disappears, although it has been a very serious one to the uninitiated. In the dissolving of the zinc from the roasted ore, there is nothing which any competent chemical' engineer cannot undertake, and any other operations connected with the electrolytic process are either of little or no difficulty, or are common to the retort process. Mr. Hansen also agrees with R. G. Hall's statement in " Some Economic Factors in the Production of Electrolytic Zinc:"2

Jan 10, 1918

By hydrometamorphism is meant the alteration of rocks, ores and minerals by atmospheric waters. In its broadest sense, it includes the varied processes of weathering, oxidation, hydration, the leaching of rocks and ores, and the solution, migration and enrichment of metals. Rain water, as it strikes the earth, is practically pure water, except for small quantities of dissolved atmospheric gases; upon coming in contact with ore minerals, especially sulphides, however, it is transformed into solutions of great chemical activity, which attack, transform and rearrange the minerals of ore- bodies, and so effect enrichments of the greatest economic importance. Primary deposits so low in grade as to be without commercial value are frequently thus transformed into deposits of commercial importance. It is necessary in the examination of any orebody, therefore, to determine whether the valuable ore is of primary or of secondary origin; if primary, its value may be expected to continue indefinitely in depth to the zone of primary impoverishment; if secondary, the ore deposition is known to be controlled by surface agencies, and the valuable ore may be expected to continue to such depths only as have been reached by surface waters. The decomposition and weathering of rocks, unlike the changes undergone by orebodies, are accomplished by water carrying as dissolved constituents chiefly atmospheric oxygen and carbon dioxide, together with vegetable acids. The chemical changes wrought are principally hydration, oxidation and the formation of carbonates. The tendency is toward the solution of the more easily dissolved minerals, which is attended by the formation and a surface concentration of the more resistant minerals,

Jan 1, 1932

By G. Herget

Finite-element analysis of slopes and a field trial of a slope support system have shown that a considerable potential for excavation reduction exists if slopes are designed with variable slope angles with depth, and if artificial support systems are made an integral part of the slope design. A cost analysis has shown that the savings for a straight 500 ft. high slope with artificial support can amount up to $900 per foot of horizontal pit extension. Horizontal stresses and displacements can be overestimated by up to 100% by employing a two-dimensional finite-element analysis instead of a three-dimensional one. Stress magnitudes differ considerably when comparing results from slope models subjected to a gravity stress field with slope models subjected to high horizontal stresses. Because the latter case appears to be predominant for open pits, slope stability analyses have to be adjusted accordingly. A field trial measuring peak accelerations and displacements has shown that the use of pre- shearing for termination bench blasts, in cases of already heavily fractured ground, can be more detrimental than beneficial.

Jan 1, 1972

By Ian M. Thomson, Robert W. Greene

To move 7 million tons annually from their new inland coal mines at Camp Breckenridge, Ky., TVA selected a transportation package proposed by American Commercial Barge Line. The land portion includes two cable-driven conveyors covering 12.7 miles; a 260,000-ton storage area on a man-made island with a stacking-reclaiming bucket wheel; and a barge-loading system of 5500-tph capacity. The 183mile river portion will utilize three unit-tows with towboats and barges specially designed to carry the maximum tonnage allowed by locks and channel depth. The system has two noteworthy features. The first is a single-flight cable belt conveyor over nine miles long. The other is a high capacity twin belt conveyor using the principal of two separate belts supported in 60° troughing idlers. This conveyor exhibits a high carrying capacity combined with accurate tracking and lack of spillage. A description is given of the mechanical problems and solutions to the design, construction, and operation of the conveyor system which provides the link between the coal mine and the barge loading dock.

Jan 1, 1974

By J. J. De Witte, J. G. Cazort

The Paranam plant in Surinam (formerly Dutch Guiana) was built during 1939-40 to supply crushed and dried bauxite for the growing U.S. aluminum industry, supplementing production from the Suriname Aluminum Co.'s Moengo works, which began operation in 1922. A subsidiary of Aluminum Company of America, Suralco's total annual production from these two plants averages 2.55 million dry metric tons of various grades of bauxite. Starting in 1941 with bauxite from mines on the west side of the Suriname River, annual production at the Paranam plant has varied from a low of approximately 450,000 tons to more than 1 million tons in 1949. High production rates during World War II and the late 1940's rapidly depleted these reserves, and in 1950 plans were made to mine the known deposits on the east bank of the river, about five miles downstream from the original Paranam plant.

Jan 11, 1960

By Francis T. Freeland

The deeper workings of the Leadville mines show refractory ores, consisting principally of sulphides of iron, lead, and zinc, carrying silver, in place of the easily reduced carbonate ores lying nearer the surface. The largest and most extensively developed deposit is that of South Iron Hill.* It lies on the north side of California Gulch,

Jan 1, 1886