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Three separate and unconfined aquifers occur in the Hilton area, named relative to position in relation to ore horizons: Footwall Aquifer in the east; Ore-Zone Aquifer within the ore-bearing Urquhart Shales; and the Hangingwall Aquifer in the west.It is the on-going strategy it Hilton to drain the Ore-Zone Aquifer which occupies structurally- and sulphide-controlled leached zones in the steeply west dipping strata. The aquifer affects considerable ore reserves to 480 m below the surface. Dewatering began in 1976, and is essentially completed to 4 level (240 m below surface). Dewatering efforts are now based on 8 level (480 m below surface).

Jan 1, 1993

By Egons R. Podnieks, Wallace W. Roepke

Mining technology to utilize vital lunar resources will be required for any commitment to permanent lunar basing. Lunar mining must be viewed both as a major supporting element for space resource commercialization and for creation of human settlements on lunar and planetary surfaces to support long-range space exploration. The Apollo missions to the lunar surface and results from fundamental research on analogue lunar rocks by the Bureau of Mines, and others, have provided the initial data for developing lunar mining technology. The multi-disciplinary research projected in this paper outlines the scientific and engineering needs to realize the lunar mining goals.

Jan 1, 1990

By J. L. Tokich, A. R. Troiano

Since 1921, when Hull1 discovered that cobalt can exist in the face-centered cubic and hexagonal close-packed modifications, the transitions that occur in cobalt have been extensively studied. It is generally agreed that on heating the hexagonal lattice changes to the cubic structure at ternperatures ranging from 400° to 500°C although considerable doubt exists as to the exact temperature. Data concerning the temperature of the transformation on cooling are much less concordant and their interpretation has not been satisfactory. The study is further complicated by the fact that many investigators have reported the existence of a high temperature allo-tropic change in the range 850 to 1020°C, at which the cubic lattice reverts to the hexagonal modification. The transition on cooling, which has been reported as Occurring at various temperatures from approximately 400 to 100°C, is of particular interest. Troiano and Greninger2 have recently suggested and considered the possibility Of allotropic transformations occurring in pure metals by a shear-type, diffusionless (martensite) transformation. The case of cobalt was specifically discussed and certain observations of previous investigators evaluated in terms Of this type of Of Table 1 briefly outlines the methods and results Of previous investigators Of the transformation temperatures of cobalt. Materials and Methods The major portion of this investigatioll was performed with cobalt sheet containing a total of 0.2 pet impurities with carbon present to the extent of o,I pct. After melting in an induction furnace under an atmosphere of hydrogen, the carbon con. tent analyzed 0.03 pct. Some observations were repeated with hydrogen reduced cobalt compresses analyzing 99.9 pet pure. No significant variations in results were observed employing the as-received sheet, the remelted stock, or the cobalt compresses. Filings for X ray diffraction analysis were sealed in evacuated glass ampoules. Pyrex glass tubing was used for temperatures below (600°C and for higher temperatures clear fused quartz was satisfactory. After appropriate heat treatment at various ternperatures, the specimen ampoules were furnace cooled, air cooled or quenched by crushing under distilled water. This allowed a range of cooling velocities from less than one degree C per set to greater than 1,0oo°C per sec. X ray diffraction patterns were taken with a Debye camera and filtered characteristic cobalt K-alpha radiation. The of of the existing phases was roughly approximated by visual examina-

Jan 1, 1949

By A. Berry, N. R. Banerjee, C. S. Finnigan, M. Fayek, N. J. Bridge

Lac Cinquante is a mineralogically simple, vein-hosted uranium deposit in Archean basement rocks (Angikuni greenstone belt) that originally were unconformably overlain by Proterozoic sedimentary and volcanic rocks of the Baker Lake Group (BLG). Basement rocks are mainly pillowed and massive tholeiitic lavas (N-MORB) with interbedded tuff; overlying sedimentary rocks comprise a basal talus/fault breccia that grades upward into fluvial sedimentary rocks and subaerial, trachytic volcanic rocks; granite and porphyry dikes (Hudson and/or Nueltin granitoids) intrude the basement rocks. A typical section through the Main Zone comprises 1) laminated ‘tuff’, 2) altered (carbonate-hematite-chlorite) schistose ‘tuff’, 3) a pitchblende-bearing, breccia-vein, 4) altered ‘tuff’, and 5) laminated ‘tuff’. The vein comprises brecciated chlorite, hematite, and pitchblende with carbonate cementing the breccia. Graphitic ‘tuff’ with sulfide-stringer veinlets locally overlies or underlies the vein. Pitchblende also occurs in the altered rocks and in gash veins that cut basement rocks. U-Pb ages on pitchblende fall into two groups: one at 1828 } 29 Ma reflects primary uranium mineralization, and a second at 1437 } 31 Ma represents resetting. Pb-Pb chemical ages show other resetting events at 1260-1321Ma, 895 Ma, 741-813 Ma, and 660-706 Ma. One possible genetic model for the Lac Cinquante deposit involves leaching of uranium from granitoids and the BLG by basinal brines that migrated to depositional sites where graphitic rocks acted as a reductant. A second model requires that uranium was sole-sourced from the BLG and that granitoid rocks provided heat to drive the hydrothermal system, which leached and ultimately precipitated uranium. The deposit has characteristics similar to vein-type uranium deposits in the Beaverlodge District of Saskatchewan

Jan 1, 2013

By Yongjie Yang

Experimental study on the strength and deformation characteristics of coal under cyclic loading provides guidance for designing coal pillar which is subjected to repeated mining influence during mining. This paper studies the strength, deformation and fatigue process of No.3 coal from Xinhe Colliery under cyclic loading by the MTS815.03 servo-controlled rock mechanics test system. The results indicate that coal is more susceptible to fatigue damage than other hard rocks. Under uniaxial cyclic loading, the fatigue failure ?threshold value? of coal is smaller than 78% of its uniaxial strength, and there is also some fatigue damage when cyclic loading and unloading experiment is carried out below the fatigue failure ?threshold value?. Axial deformation can be divided into three stages: Initial deformation, steady-state deformation and accelerating deformation. Transverse deformation can be divided into two stages: Stable deformation and accelerating deformation. When the transverse deformation begins to increase rapidly and the deformation recovers only slightly upon unloading, it?s a precursor to failure of coal. Under cyclic loading, fatigue failure develops through a process of compaction, strain hardening, and strain softening.

Jan 1, 2006

By Wilbert J. Huff

The work of the Explosives Division, Bureau of Mines, United States Department of the Interior, for the fiscal year ended June 30, 1939, is described in the following pages. This paper is the fourth of a series of annual reports covering the activities of the division since July 1, 1936. The studies outlined in this and preceding reports of the series have been conducted under the direction of the author and the respective unit leaders to whom specific credit is indicated.

Jan 1, 1940

By P Davidson

For many years, in numerous settings, the need for a language-fair and culture-fair assessment test has been identified as a significant issue for employment and selection for training of remote indigenous community members. Pivotal to the successful implementation and application of such a test is for it to gain the acceptance and trust of the local indigenous communities as a fair assessment and for it to provide organisations with an accurate predictive tool. However, when western tests have been used with indigenous groups, inherent language and cultural bias have had a significant negative impact in terms of community acceptance. These have also affected the accuracy of performance predictability. The Queensland Test was developed to overcome these problems. Originally developed for use in Papua New Guinea, it reduced training failures by 20 per cent. Later refinements were made and it was used with Aboriginal Australians. Since 2002, assessment tests have been used by the Freeport mine in West Papua to support their recruitment, selection and training processes for the local indigenous community, the Seven Suku Tribes. The initial process included the application of standard æwesternÆ assessment tests, which did not provide valid selection predictions, with community members and elders describing these tests as unfair and the organisation being concerned that the results were not accurate. A trial of the Queensland Test was conducted and a high correlation was established between the performance of FreeportÆs current Seven Suku employees as assessed by their managers and their Queensland Test results. Based on the results of this pilot the Queensland Test was successfully implemented as the primary selection tool for potential employees from these local indigenous groups. The testing materials and method gained community trust and support, with tribal elders describing the Queensland Test as a fair and suitable selection tool for their community members. Such results have sparked an interest within the Australian Mining industry, with similar results being reported from a recent trial. The Queensland Test has been implemented at a major site in Queensland and is being investigated for use elsewhere.

Jan 1, 2006

By David L. Veith

As the basis for the State of Minnesota's Regional Copper-Nickel Study environmental evaluation, hypothetical mine models were developed ranging in ore capacity from 5.35 to 20.00 x 106 mtpy. Open pit and underground mining operations were defined utilizing conventional methods of ore extraction. Processing of the copper-nickel sulfide material involved conventional bulk flotation of the valuable minerals, with maximum water recycle And tailing disposal. Flash smelting and electrolytic refining of the concentrate resulted in 0.10 x 106 mtpy copper plus nickel metal, plus associated cobalt and precious metals. Variations in model parameters allowed environmental trade-offs to be identified.

Jan 1, 1980

By H. P. Greenwald

[In many coal-mining countries, during he pest decade, there have seen made extended studies and accurate measurement of movement of roof strata, tests of the physical properties of specimens cut therefrom, and tests of the strength of end load on artificial supports. Naturally, such studies have been more extensive in European countries, where mining conditions are less favorable than in the United States. As a part of its work in the conservation of coal resource and prevention of accidants in mines, the Bureau of brines began systematic measurements of the movement of roof strata to in coal mines in the fall of 1935. It was decided- that, in the beginning, work on a rapidly retreating rib line in a mechanized mine would give the greatest amount of information in a reasonable time. To this end w cooperative tine agreement was made with the Pittsburgh Coal Co., through Dr. L. E. Young, vice: president in charge of operations, for conduct of work in that company's Montour 10 mine operating in the Pittsburgh coal bed. This paper gives an account of the methods used in the investigation, excerpts from the data obtained, and such generalizations as appear to be justified.]

Jan 1, 1937

By H. P. Greenwald

[In many coal-mining countries, during he pest decade, there have been made extended studies and accurate measurement of movement of roof strata, tests of the physical properties of specimens cut therefrom, and tests of the strength of end load on artificial supports. Naturally, such studies have been more extensive in European countries, where mining conditions are less favorable than in the United States. As a part of its work in the conservation of coal resource and prevention of accidents in mints, the Bureau of Mines began systematic measurement of the movement of roof strata to in coal mines in the fall of 1935. It was decided that, in the beginning, work on a rapidly retreating rib line in a mechanized mine would give the greatest amount of information in a reasonable time. To this end a cooperative agreement was made with the Pittsburgh Coal Co., Dr. L. E. Young, vice president in charge of operations, for conduct of work in that company's Montour 10 mine operating in the Pittsburgh coal bed, This paper gives an account of the methods used in the investigation, excerpts from the date obtained, and such generalizations as appear to be justified.]

Jan 1, 1937

By R. H. Lien

The Bureau of Mines developed a flue gas desulfurization process as part of its goal of minimizing the undesirable environmental impacts associated with energy and mineral-processing plants. The modified citrate process involves absorption of sulfur dioxide (S02) in a buffered citric acid solution. The S02-loaded solution is regenerated by countercurrent contact with steam in a packed tower. The wet S02 product is then dried and can be liquefied or further processed to make sulfuric acid. Test data from process investigation unit studies are presented. Material balances, flowsheets, and cost estimates are given for recovering S02 from copper smelter reverberatory gas, lead smelter sintering machine tail gas, and power-plant stack gas. Operating cost estimates show the process will add $0.04 per pound of copper, $0.01 per pound of lead, and $0.015 per kwhr to the cost of the respective operations. These costs could be substantially reduced if a source of waste heat was avail-able to provide the process steam requirements.

Jan 1, 1982

By M. G. Corson

INFORMATION regarding the use of manganese alloys has hitherto been incomplete and available only from widely scattered sources. This paper attempts a systematic description of properties and uses of alloys other than manganese bronze, manganin and duralumin, which are probably the only non-ferrous alloys associated with manganese in the minds of most metallurgists.1 PROPERTIES OF MANGANESE Manganese can react either acid or basic; it is hard to obtain in the pure state; it has two different crystalline lattice structures, both of the cubic system, one stable above 850° C. and the other below 650° C., both coexisting in the intermediate range. Although the commercial product is hard and brittle, the pure metal seems to be ductile. In fact Zhemchuzhny, in Russia, was able to obtain ductile manganese and draw it to fine wires by the simple expedient of adding about 3 per cent. copper to the alumino-thermic product. Copper most probably brings the sili-cides, aluminides, nitrides and carbides present in the commercial product into a much less harmful form of distribution. One industrial use that can be foreseen for wrought manganese articles is as anodes for electrolytic processes in sulfate and nitrate solutions, particularly with high voltages. A practically insoluble skin of manganese peroxide is likely to form in such cases and an insoluble and strong anode material will be available.

Jan 5, 1927

By John H. Bassarear, A. A. Dor

INTRODUCTION Primary grinding mills as defined in this paper, are autogenous or semi-autogenous rotating, tumbling mills having a coarse feed with a top size usually varying from 150 to 300 mm (6 to 12 inches). Most frequently, the feed to these mills is the product of primary crushing plants but in some cases run of mine ore is used as feed such as at Benguet, McDermitt, L-Bar Sohio, Bear Creek and others. The size of the largest lumps in the mill feed is principally determined by limits set by the mill feed trunnion diameter and by the type and size of conveying equipment used for handling and of bins and stockpiles used for storage. The use of primary mills in mineral processing plants has expanded very significantly in the last twenty years, and they have been successfully applied to the treatment of a wide variety of ores in both wet and dry grinding applications. In the present state of technological development for primary grinding mills, there is a wide choice of acceptable options with respect to type and size, grinding flowsheet and grinding media. The choice of the optimum combination which would result in the most satisfactory condition of operation, from the standpoint of both metallurgical results and costs, depends on the nature of the ore, the required characteristics of the grinding products and on various geographic and economic circumstances. The effects of such factors and considerations on the choice and sizing of primary grinding mills and flowsheets are reviewed and discussed in the following pages. PRIMARY MILLS SELECTION Inherent Characteristics of Primary Grinding Primary grinding is complex because it involves several comminution mechanisms which occur simultaneously and to some degree interfere with one another. These mechanisms of impact, attrition and abrasion have been described earlier. The relative importance of these three main grinding actions and their mutual balance resulting in a continuous uniform operation of the mill depend to a very large extent on the nature of the ore and its physical properties. Homogenous, single mineral ores will behave quite differently from heterogenous ores consisting of different minerals bound together along defined

Jan 1, 1982

By W. H. Bassett, C. H. Davis

ALTHOUGH brasses and bronzes have been made for ages, a systematic study of their physical properties has been carried out only during the years of the present century. Among these properties may be included those which are to be detected by means of microscopic examination; in other. words by the science of metallography. The earlier workers in this field, both in this country and abroad, gave their attention to steel. When the senior author explored the situation in 1902, there was little encouragement to be found in undertaking the study of the non-ferrous alloys. A start was made, and the metallography of the brasses and bronzes, as well as of the copper-nickel-zinc alloys developed materially under his direction. Annealing experiments were begun in 1902, and in the succeeding years the effect of temperature, and the influence of previous working, on the grain size of brass were studied. The conclusions so well known and widely published today were largely reached during those earlier years. . In 1905 the first complete annealing series were made. By this it is meant that brass and copper sheet, 5 B & S Nos. hard, was machined into tensile test specimens, then annealed under accurate control for 30 min. at temperatures up to the melting point of the material. Various determinations were made, including tensile strength and elongation in 2 in. There rapidly followed similar series on all of the copper-zinc alloys from 100 to 60 per cent. copper, on the bronzes, cupronickels, and on copper-zinc-nickel alloys. At this point there was published by Grard, in October, 1909,1 the very comprehensive and complete work on the tensile properties of cartridge brass, 90-10 copper-zinc, and electrolytic copper. The excellent photomicrographs in that paper illustrated the changes in structure produced by cold rolling as well as by annealing at different temperatures, but where Grard's work was confined to copper and to two alloys, the investigations in this laboratory have been over the entire fields of the commercial copper-zinc alloys, copper-tin alloys, representative copper-nickel and copper-nickel-zinc alloys as well as aluminum bronzes and others of a more special nature.

Jan 1, 1928

By D. J. McAdam

As shown in three recent papers by the author, in two papers by McAdam and Mebs, and in a paper by McAdam, Mebs, and Geil," the technical cohesive strength of a metal, in any particular state as regards mechanical treatment and heat-treatment, cannot be represented by a single stress value, but must be represented by a diagram with the principal stressest as coordinates. Each point on the boundary of such a diagram represents a technical cohesion limit. The technical cohesive strength thus comprises an infinite number of technical cohesion limits, each representing fracture under a specific stress combination. Moreover, neither the yield strength1 nor the ultimate strength can be represented completely by a single stress value, but must be represented by a diagram with the principal stresses as coordinates. All combinations of the principal stresses may be classified in three groups as illustrated by Fig. I. Fig. Ia shows three typical stress combinations with no two principal stresses equal. The magnitude of each principal stress is indicated qualitatively by the length of the arrow. Arrows pointing away from the cube indicate tensile stresses; arrows pointing toward the cube indicate compressive stresses. Typical stress combinations with two principal stresses equal are illustrated in Figs. rb and Ic. Such stress combinations would be produced by subjecting a cylinder to combinations of uniform axial and radial stresses. The uniform radial stress may be resolved into two equal principal stresses. with the mutually perpendicular directions rotatable around the axis of the cylinder. Fig. ib shows stress combinations with Sz equal to The greatest principal stress is in the axial direction, and the stress combination tends to cause either absolute or relative increase in length.* Fig. u shows stress combinations with S2 equal to St. The greatest principal stress is in the radial direction, and the combination tends to cause either absolute or relative decrease in length. The complete representation of either technical cohesive strength, yield strength, or ultimate strength generally requires a three-dimensional diagram. When two of the principal stresses are kept equal, however, the strength of a metal may be represented by a two-dimensional diagram with the coordinates representing the axial and radial stresses.6-II In this paper, attention will be confined almost entirely to stress combinations with two of the prin-

Jan 1, 1945

Jan 1, 1915

By Richard E. Gray

Virtually all structures show some signs of distress due to deterioration of the building components, to changed loads, or to changed support conditions. Changed support conditions result from ground movements. In mining regions many cases of structural distress are attributed to mining without considering alternative causes. This is particularly true of coal mining since it occurs under extensive areas. Coal mining is estimated to have already undermined more than eight million acres and may eventually undermine 40 million acres in the United States (HRB Singer, Inc., 1977). Other nonmetal and metal underground mines impact much smaller areas. Although it is sometimes difficult, even with careful study, to identify the actual cause of damage, persons responsible for underground coal mining should at least be aware of possible causes of building stress other than mine subsidence. This paper presents information on distress to structures and briefly reviews a number of causes of ground movements other than subsidence: Mass movements, dissolution, erosion, frost action, shrinking and swelling, yield into excavations and compressibility

Jan 1, 1986

By Alan Morris

Brass rod for use in automatic screw machines is one of the major products of the brass mills. A large tonnage is consumed each year in the manufacture of an endless variety of finished articles and parts for assembly into other products. The machines that do this work have been developed to a high degree of efficiency, and their manufacturers are still striving for higher production speeds. This development has brought with it a demand for brass rod to meet the increasingly difficult machining conditions. This paper is a report of the results of tests undertaken in an effort to obtain a measure of the effects of such variables as lead content, microstructure and cold work on the machinability of brass rod. It is realized that the term "machinability" has never been well defined. Power, finish and tool life all should have a place in such a definition. In practice it is sometimes found necessary to sacrifice some of these in order to obtain a rod that will not tend to throw up a burr, or will give a burr which is easily tumbled off. Again a specially stiff rod may be necessary because of long overhang from the chuck or a rod of special characteristics is needed to take a given broaching operation without chattering. It is only through an understanding of the effect of basic mill operations on the machinability of the rod that such problems as these may be solved most economically. It is hoped that this paper, together with the discussion it may evoke, will prove to be a basis for such an understanding. Testing Apparatus The testing apparatus used was of the single-tooth milling cutter type, in all respects sirnilar to that first used and described by Airey and Oxford1 and again by Boston. The machine used in the present test is shown in Fig. 1. It is an ordinary milling machine in which a heavy pendulum has been substituted for the pulley on the arbor. If the pendulum is raised

Jan 1, 1932

By Kot F. Unrug

Since the introduction of longwall systems, the prediction of roof behavior and support requirements have become the major issue referring directly to safety as well as productivity. In more recent times, and especially in the USA where longwalls are exclusively equipped with costly hydraulic self- propelled support systems, a decision whether a longwall is applicable in a given condition, and when so, what kind of equipment should be selected, is of primary importance. There are numerous examples where lack of experience, and subsequently wrong selection of supports or winning machines, resulted in considerable losses. It should be emphasized that careful studies of prevailing geological and mining conditions, especially in a new area, are required to assure a successful operation. An evaluation of the conditions can be carried out in different ways utilizing such methods as: - Theoretical approach. applicable when geological conditions comply with the theoretical assumptions. - Empirical relationship which gives satisfactory results where the coefficients could be adequately determined. - Structural geological studies which must be undertaken in all cases, since the frequency of fractures and their orientation have a prevailing influence on roof behavior. - Scale model study on equivalent material for determination of failure conditions in the roof and mechanism of movement (flow) of broken rock matter. Coefficients for empirical formulas can be determined by these types of studies, as can boundary limits for mathematical modeling. - Mathematical modeling, e.g., finite element analysis. - Measurements and observations taken underground during the development period end utilization of experience for previous longwall panels in the area. Usually it is the most practical method where mining and geological conditions are comparable. An application of me or more of the above approaches remains to be a matter of judgement for particular conditions, however, the utilization of a practical experience, when available, is usually the safest way for planning a successful longwall operation.

Jan 1, 1982

By d&apos, Kathleen J. Amico

THIS SUMMARY is identical to the summary given in volume III of this series of mineral production in the United States (including Alaska and Hawaii), its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico and of the principal minerals imported into and exported from the United States. For further details on production see commodity and area chapters. A summary table comparing world and United States mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers [ ]

Jan 1, 1958