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By William E. Mead

A regional investigation to find large supplies of potable ground water was carried out at elevations exceeding 12,000 feet above sea level on the Bolivian Altiplano. The program marked the first application of modern ground water search and development technology in the region, and ended a history of unsuccessful exploration efforts to locate important supplies of fresh water from underground sources. Oruro, a population center of 90,000 inhabitants, and its primary supporting industry - mining, both derived major direct benefit from the results of this program.

Jan 1, 1970

By Peter I. Brooker

The turning bands method for the simulation of spatially correlated data in two or three dimensions requires that the relation- ship between the covariance obeyed by the realizations first generated on lines, and the covariance of the two or three dimensional process must be solved. In three dimensions the solution is immediate, but in two dimensions the integral equation relating the covariances of the one and two dimensional processes is more complex. This is solved in this paper and is applied to the most common model used in ore deposit description, the spherical covariance.

Jan 1, 1984

By James C. Cobb

Middle Pennsylvanian (Desmoinesian) coals of certain areas of the Illinois and Forest City Basins contain epigenetic sphalerite and associated minerals in veins, clastic dikes, cleat, and other small-scale structural features. The presence of sphalerite in these coals records information about the geology of coals and coal basins, and represents a potential source for zinc as a byproduct of coal production. Origin of Sphalerite in Coal The origin of sphalerite in coal suggested by Cobb (1) involves sphalerite precipitation from zinc-bearing ?Na-Ca-Cl brines upon contact with sources of sulfur in the coal bed, e.g., pyrite, H2S, and organic sulfur. These brines were essentially at the temperature of the host coals as determined by fluid-inclusion thermometry and vitrinite-reflectance studies. The migration of these brines into coal beds may have been caused by compaction of sediments due to continued sediment loading of the coal basins. Zones of high permeability such as sandstones and the coals themselves presumably acted as conduits for the movement of the brines. The open spaces where sphalerite was deposited resulted from minor deformation associated with differential compaction and cleat formation enhanced by volume shrinkage during coalification.

Jan 1, 1982

By Fred Leighton

INTRODUCTION Dynamic (seismic or microseismic) methods of determining the stability of structures in rock are based on detecting and analyzing the characteristics of seismic energy that has originated from or traveled through the rock mass. This seismic energy can be in the form of naturally occurring rock noise energy resulting from structural adjustments within the rock or can be introduced into the structure by physical means, such as by blasting or impact. In either case, the seismic energy radiating through the rock mass can be detected using standard equipment and can be analyzed by established techniques to reveal a wide variety of information concerning the condition and stability of the rock mass through which the energy has traveled. In the following sections, the basic instrumentation required for seismic and microseismic studies is described, and some of the presently used applications of these methods are discussed to exemplify the state of the art. INSTRUMENTATION Seismic disturbances in a rock structure generate two types of seismic wave radiation, body waves and sometimes surface waves, which radiate outward in all direc¬tions from the source of the disturbance. Underground mining applications are generally concerned only with discerning the characteristics of the resulting body waves, i.e., the compressional (p-wave) and the shear (s-wave) energy. As these two forms of energy travel through the rock structure, the particles of the rock mass are caused to vibrate, and the vibration character¬istics resulting from each of the two types of wave are distinct. Some important differences are: 1) Compressional and shear waves travel at different velocities through the rock structure. 2) The frequency at which each wave causes particles to vibrate is different, and may range from about 50 to 100 000 Hz. 3) The amplitude or energy level of each wave is different, with the shear energy usually being the greatest. These differences form the basis for equipment se¬lection for individual studies and for modern data analysis techniques. The following sections describe the basic equipment necessary to detect and record seismic wave energy data and show several examples of analysis procedures and how these procedures have been used. In principle, seismic equipment is very simple. It consists of a geophone (or geophones) to detect the seismic energy vibration and convert that vibration to an electric signal, an amplification system to increase the level of that signal, and a means of monitoring and/or recording the signals detected. Fig. 1 is a block diagram of a typical system. The following sections offer a very brief discussion of system components and their individual functions. A more complete discussion is given by Blake, Leighton, and Duvall (1974). Geophones The function of the geophone is to detect the vibrations caused by the passing of the seismic wave energy and to convert that vibration into an electrical signal that displays both the amplitude and frequency characteristics of the vibration. Particle motion or vibration can be quantified and measured by measuring displacement, velocity, or acceleration of the particles. Thus, there are three types of geophones: displacement gages, velocity gages, and accelerometers. The choice of gage depends on the characteristic frequencies of the seismic energy to be monitored and the sensitivities of each type of geophone. In general, displacement gages are used for low-frequency monitoring (periods to 1.0 Hz), velocity gages for medium-frequency monitoring (1.0 to 250 Hz), and accelerometers for high-frequency monitoring (250 to 10 000+ Hz). Experience has shown that in underground studies, the choice of which gage to use lies between velocity gages and accelerometers. An easy, accurate method for selection of gage type is discussed by Blake, Leighton, and Duvall (1974). Once the type of geophone has been selected for use, it must be properly installed, and in the installation procedure the most important step is insuring that the gage is firmly attached to a competent portion of the rock structure. Poorly mounted geophones may entirely fail to recognize low-level seismic signals and will distort the information from signals they do see. Amplifiers Seismic events associated with mine structures occur over a very broad range of energy which results in a broad range of geophone output levels. In general, geophone output levels occur in the microvolt to low milli-volt range, and it is necessary to amplify these signals in order to drive recording or monitoring equipment. Because either an accelerometer or a velocity gage might be used as the geophone, the amplification system must

Jan 1, 1982

By Marc Lonoff

Byproducts are more important to the copper mining companies than to the copper market. Copper ores frequently contain gold, silver, molbydenum and cobalt. With the increase in the prices of these metals copper mining has become more profitable. If byproduct prices remain high, additional firms will be attracted to the copper industry; the increased supply of copper will reduce the long-run copper price. However, this is unlikely to happen because the markets for the copper byproducts, especially molybdenum and cobalt, are small. Increased recovery from copper and other sources will depress the prices of these byproducts before the copper price is significantly affected. Should byproduct prices remain high the copper market will both settle at a lower long-run price and be more unstable in the short run. Since changes in the copper price do not affect the entire earnings of a multi-metal mine, the copper price must fall further before such mines reduce output in the short run. Higher byproduct revenues will make copper supply less responsive to copper price; shifts in copper demand will result in greater copper price fluctuations in the short run than they did before.

Jan 1, 1980

By Marshall D. Himes, Erich U. Petersen

The Sheep Creek deposit near White Sulfur Springs, Montana, is a middle Proterozoic stratabound and strataform sediment- hosted massive sulfide containing 4.5 million tonnes (5.0 million tons) averaging 2.5% copper, and 0.1% cobalt in the upper sulfide zone (USZ) and 1.8 million tonnes (2.0 million tons) averaging 6% copper in the lower sulfide zone (LSZ). Mineralization is hosted in lower Newland shales and debris flow conglomerates in the graben controlled Helena Embayment of the Belt Basin. USZ mineralization is characteristically high in Cu, Co, Ni, Ba, As, Pb, and Ag. Mineralogically it consists of barite, pyrite, chalcopyrite, and tennantite with minor amounts of marcasite and various cobalt minerals. By contrast, the LSZ is higher in Cu, Ni, and Au and lower in Co, As, Pb, and Ag. Mineralogy of the LSZ consists of dolomite, pyrite, and chalcopyrite. In both zones significant amounts of cobalt, nickel, arsenic and copper are incorporated in pyrite rims. Tennantite controls the abundance of numerous trace elements in the ores. Fluid incluison data from hydrothermal USZ barite suggests that mineralization took place at temperatures in excess of 250°C, under relatively oxidizing conditions (f02 = 10-32+1) from moderately saline (1.1-3.5m), metal rich brines. The absence of barite in the LSZ suggests mineralization under more reduced conditions (f02 = 10.38+2). Mineralization was initiated following basin subsidence in excess of 400m. Contemporaneous with movement along a growth fault(s) was upward migration of hot metal-bearing fluids which permeated the loosely consolidated sediments and may have vented on the sea floor. The differences in the two zones may be explained by the effects of variations in local basin morphology and solution chemistry.

Jan 1, 1990

By T. C. Page, P. C. Gibson, M. A. Miller, J. D. Sell

[The Yarnell gold deposit in the Weaver mining district, Yavapai County, Arizona, occurs in a structurally controlled, hydrothermally altered zone in a 1700 Ma granodioritic intrusive. Both potassic and sericitically altered rocks around and above the low-angle, northeast striking Yarnell fault are known to host economic gold mineralization. A wider envelope of weakly-propylitic altered rock also occurs in this area. During mineralization, strong sericitization accompanied several stages of quartz (±adularia) veining, stockwork formation, localized silicification and potassic replacement, in association with deposition of specularite, pyrite (now oxidized) and gold. The footwall of the fault is also sericitically altered but poorly mineralized. Mineralization along the Yarnell fault continues both northeast and southwest from the main deposit, although the thickness of the zone and associated alter avian envelope diminish away from the orebody A sample of undo formed illite taken from the Yarnell fault zone was K/Ar dated at 69 + 1.6 Ma. This date reflects a minimum age for both mineralization and latest movement on the fault. Gold mineralization is accompanied by modest increases in Ag, As. Cu and Mo content. Both CO2- and H2O- rich fluid inclusions were studied and suggest mesothermal pressures and temperatures of formation for the deposit. Ninety-six reverse circulation holes and four diamond drill holes outline a bulk-minable mineral reserve of'4.1 million tons at 0.051 oz of Au per ton. An additional 2.7 million tons at 0.017 oz of Au per ton occurs in a low-grade zone above and subparallel to the main mineralized zone. Total calculated mineral inventory stands at 6.8 million tons at a grade of 0.038 oz of Au per ton, with a waste-to-ore ratio of 1.45:1. Column leach tests indicate that cyanide heap leach gold recoveries should exceed 70%.]

Jan 1, 1994

By Lawrence W. Teufel

Knowledge of in situ stress and natural fracture distribution at depth improves our ability to stimulate and produce low permeability reservoirs. The focus of this study is three closely spaced, 2.5 km deep vertical wells in the Piceance Basin of Colorado. The wells were completed through the tight lenticular and blanket gas sands of the Mesaverde Group. In situ stress directions and magnitudes were determined from hydraulic fracture tests and anelastic strain recovery measurements of oriented core. The distribution, orientation, and characteristics of natural fractures in the subsurface were determined from detailed observations of over 1300 m of core, of which 400 m was oriented. Stress measurements clearly show that horizontal stresses are strongly influenced by lithology. In a sandstone/shale sequence at a depth of about 2.0 km in situ stresses in sandstone formations are anisotropic, with the average ratios of the minimum and maximum horizontal stresses to the overburden stress being 0.82 and 0.96, respectively. In sharp contrast bounding shale formations are lithostatic. This stress contrast between sandstones and bounding shale formations could act as a barrier to hydraulic fracture propagation during stimulation and impede vertical fracture growth. Natural calcite-filled fractures are present in over 7 percent of the core, with several horizons having a much higher frequency of fractures. Fractures are found primarily in sandstone. The fractures have a strong preferred orientation of N 1060E[+]110, which is aligned with the maximum horizontal stress and direction of hydraulic fracture propagation. The interaction between a well developed fracture fabric and anisotropic stresses in sandstone formations produces a permeability anisotropy, with the maximum permeability aligned with the fracture fabric and maximum horizontal stress.

Jan 1, 1986

By Gürkan Bacak

Study area is located on the NorthWestern of Yatagan-Yenikoy and placed in the units of the crystaline Menderes massif of Eagen, Turkey. Stratigraphically gneissic, migmatitic and metagranitic rocks are found at the base. Garnet schists, phyllitic rocks lie unconfirmitelly upon the basement rocks. Permian aged marbles can be observed as diferrent sized lenses within the schists. Triassic, Jurassic and Cretaceous aged gray colored dolomites and pure crystaline calcite bearing marbles lie upon the Permian aged schists. Neogen series, mainly composed of conglomerates, claystones, marl and limestones unconformly cover the other basement series, mentioned above. Pure calcite bearing marble occurances are found at 2 locations in the study area. These are known as Berber Quarry and Kavuk Quarry. Samples numbered as N7, N8, NA from the Berber Quarry, mineralogically composed of Calcite (97-99%)+iron oxide (1-3%) and chemically contain CaCO3 (97,98%), Fe2O3 (0.5-1%), SiO2 (0.025%) N9 and N10, sampled from the Kavuk Quarry-mineralogically composed of Calcite (94,95%)+iron oxide (2-3%)+albite-Quartz (1-2%) and chemically contain CaCO3 (92-93%), SiO2 1.49%, Fe2O3 0.42%. Especially in plastic and paint sector albite and quartz are unwilling minerals due to their hardness. Approximatelly 1/20 of the study area (87.500 km2) contains industrial calcite occurances. Moreover about 100 billion Tons geological, 1.86 billion tons runable (possible) calcite reserve calculated. It can be expected the calcite quality will be increased with depth. During the running stage of the quarries over burden removel and hand sorting processes will positive affect of the quality.

Jan 1, 2005

By Frederick S. Fisher

Three spatially separate porphyry copper/molybdenum deposits are associated with the Tertiary Needle Creek igneous center in the southern Absaroka Mountains, Wyoming. In all three deposits a central zone containing disseminated copper and molybdenum is surrounded by a halo of small, discontinuous base and precious metal veins. Propylitically and phyllically altered rocks are common in all three mineralized areas, and potassically altered rocks are locally present. Fission- track age data from apatite and zircon indicate that mineralization occurred about 32-40 m.y. ago. Limited data suggest that the lead isotopes are nonradiogenic, similar to porphyry copper deposits elsewhere in the western United States. The complex igneous history of the Needle Creek center has involved several periods of intrusive and probably extrusive activity. lntrusive rocks are calc-alkalic and include andesite, granodiorite, diorite, quartz monzonite, dacite, and rhyodacite. Stocks (1-30 kmz in exposed area), radial dike swarms, and sills make up the presently exposed plutonic masses and constitute lower-level vent fillings in an old stratovolcano. The Needle Creek igneous center is located approximately midway along a northwest-trending belt of intrusive rocks extending more than 100 km along the central axis of the Absaroka volcanic field. The igneous and mineralized centers within this belt were probably localized at the intersections of northwest- trending Laramide and possibly Tertiary fracture systems and earlier northeast-trending Precambrian structures in the underlying basement rocks.

Jan 1, 2013

By William L. Carter

Through your presence here this morning and your membership in the Society of Mining Engineers, you have shown that you are interested in keeping abreast of the latest technology and mining procedures, want to be part of the continuing progress made by those in your profession, and are looking for ways to participate in expanding your professional and personal experiences and skills. All of these factors are part of your continuing education, the need for peer identification or recognition, and the desire to make a specific contribution to strengthening your profession. However, you may be here with or without your company support and financial backing, unless you are self-employed. Whether you are here for the above reasons, or for many others, your presence reflects a recognition of the importance of participating in the organizational structure of your profession.

Jan 1, 1981

By David Hatem, Paul Madsen, Daniel Adams, James Morrison, Randall Essex

Managing commercial risks associated with subsurface construction may be the greatest challenge the underground industry faces. The Geotechnical Baseline Report (GBR) was developed in the U.S. to help manage those commercial risks, and to stem increasing litigation in the industry. A guidelines document by the American Society of Civil Engineers was published in 1997 and was updated in 2007. This paper provides an historical perspective, overviews the main objectives of a GBR, presents issues and trends that instigated the need to update the 2007 publication, and describes the process that will lead to a new GBR guidelines publication in 2022

Dec 1, 2022

By Steven J. Luzik

Introduction From 1973 through 1986, a total of 12 fires involving oil-flooded rotary screw compressors (OFRSC) were reported to the Mine Safety and Health Administration (MSHA). Most of these incidents were attributed to faulty or by-passed safeguards, or improper maintenance. The cause of a fire in an OFRSC is unique when compared to other types of compressors. A compressor inspection checklist is provided here that can be referenced when conducting regularly scheduled maintenance operations. This checklist and a well-planned program of periodic training and maintenance should help minimize the probability of fires and explosions in OFRSC's. Operation A rotary screw compressor operates on the principle of positive displacement of air. Compressed air in this type of compressor is produced by the meshing of two helical rotors, or screws, as they rotate within a steel housing called a stator. The male rotor normally has four lobes and is driven either directly or indirectly - through a gear assembly - by a motor. It intermeshes with a female rotor having six cavities. Figure 1 explains the compression mechanism: (1) Atmospheric air is drawn into the stator by the suction action of the two rapidly rotating rotors. (2) As the rotors rotate past the intake port, air is trapped in the stator and in the cavities between the rotors. (3) Further movement of the rotors causes an increased reduction in volume, compressing the entrapped air. (4) Compressed air is expelled at the discharge port in the bottom of the stator at a pressure and quantity determined by the particular compressor rotor design parameters, such as length, diameter, and speed. Radial bearings on the male and female rotors compensate for radial loading on the shaft and position the rotors within the stator. Thrust bearings on the discharge end of the compressor prevent rotor misalignment due to thrust developed during the compression cycle. This design prevents the male and female rotors from making contact with each other or the stator. A clearance of 0.07 to 0.1 mm (0.003 to 0.005 in.) exists between the two rotors and the stator. For this reason, there is virtually no wear on the rotors or stator, and the unit is relatively maintenance-free. Oil is injected into the compressor and serves to cool, seal, and lubricate. When air is compressed from atmospheric pressure to some higher discharge pressure, a specific amount of heat is produced. This heat is sometimes referred to as the adiabatic heat of compression. It is partially removed by injecting oil into the compression chamber. Premachined strips - a raised surface on the male rotor and a

Jan 9, 1988

By Annan Cook

J.R. Atkinson, office engineer to Kennecott Copper Corp., summarized data on the Mineral Park area [Wallapai (Chloride) Mining District, Mohave County, Arizona, Fig. 1] and submitted it to the New York office in 1950. He recommended an examination. Weston Bourret, a Kennecott geologist, accompanied by B.S. Butler, the well known former US Geological Survey geologist, examined the larger of two hydrothermally altered areas in Mineral Park that same year. Bourret recommended that the property be optioned and mapped. Georges Ordonez, Kennecott's chief geologist, after a field examination, agreed with Bourret's conclusions At the end of the summer of 1951, Annan Cook (another Kennecott geologist) accompanied Ordonez to the property prior to starting a mapping program. At Ithaca Peak, the structure, alteration, and reddish-brown coloring in leached cavities-hematite, jarosite, and goethite with minor copper staining - made an interesting target. The Peak, which has since been mined, was a Laramide quartz monzonite porphyry grading into quartz porphyry, penetrating Precambrian rocks. Turquoise had been mined from several workings on the Peak. Surrounding the central area of alteration, but mainly to the northwest, there were many long-abandoned underground workings mined for zinc, lead, gold, silver, and copper. To the west of Ithaca Peak within the main area of alteration, surface evidence of a chum drill hole suggested interest in the disseminated mineralization probably prior to World War II. A topographic and geologic survey of the altered Ithaca Peak area was initiated by Cook in September 1951. He was assisted by Richard Vosburgh, field engineer, and by four geologists: Charles Goddard, III, Donlon LoBionda, Keith Martin, and A.T. Stone. When Cook returned to New York, Vosburgh was left in charge. Mapping continued and diamond drilling took place during the winter of 1951-1952. Drill sites were selected entirely on the basis of surface geology. Five drill holes, including a flat hole, located around the flanks of Ithaca Peak, averaged about 183 m (600 ft) in length. A sixth hole caved at less than 60 m (200 ft). The best values obtained were in the first hole (-45°): 90 m (300 ft) averaged 0.62% copper and 103 m (337 ft) averaged 0.041% molybdenum. In another hole, 43 m (142 ft) averaged 1.09% copper and 0:023% molybdenum. The values of copper and molybdenum in these two holes were generally higher than in the remaining holes, although molybdenum values were always around 0.024% or better. The New York office decided, however, to abandon the project even though the remaining field crew of three had recommended more drilling.

Jan 1, 1991

By Ralph J. Anctil, James E. Palmer

According to relatively recent estimates by the US Geological Survey and the US Bureau of Mines, there are more than 0.9 Tt (one trillion tons) of remaining identified coal resources in the seven major western US coal-producing states and about 200 Gt (220 billion tons) in the demonstrated reserve base. Considering coal's current national production level of 0.7 Gt/a (0.8 billion tpy), these US reserve and resource figures are reassuring. Given here is a preliminary analysis of geologic constraints and an estimate of their effects on mining and recoverability of western coal. Mining Constraints USGS and USBM coal figures incorporate only thickness and depth, and are "blind" to many other major geologic constraints on mining and recoverability. The most important of these geologic constraints include: • coal seams too thin or too thick for conventional mining methods; • coal seams that cannot be mined due to insufficient separation from underlying or overlying previously-mined beds; • unstable or otherwise unfavorable roof strata; • soft or heaving floor strata; • coal seams that are too lenticular or discontinuous for conventional mining methods; • coal seams in intensely faulted areas; • coal seams having high angles of dip precluding the use of conventional coal mining methods; • coal seams that cannot be mined due to proximity of water-bearing strata; and • coal quality problems such as excessive ash, sulfur, chlorine, or sodium. Coal Thickness Present USGS-USBM classification for reserve base includes bituminous coal beds more than 0.7 m (28 in.) thick and subbituminous beds more than 5 m (60 in.) thick to depths of 305 m (1,000 ft). Both of these thicknesses are less than the thicknesses now considered mineable in the western US. The lower limit for bituminous steam coal in deep mines is about 1.5 m (5 ft). For subbituminous coal, a thickness of at least 2.4 m (8 ft) is generally required. Accordingly, the Bureau of Mines reserve base includes many thinner coal seams that will not be mined in the foreseeable future. Within the Powder River Basin of Wyoming and Montana many seams-Wall, Upper Pawnee, Lower Pawnee, Cache, Manning-range in thickness from 7.6 m (25 ft) to more than 30 m (100 ft) and occur at depths to 305 m (1,000 ft). These have been included in the Bureau of Mines reserve base. However, the mining technology required to mine these thick seams does not now exist. It will require many years for development. The ultimate recoverability from these thick seams is unknown, but could be as low as 25%.

Jan 8, 1982

By R. Q. Phillips

INTRODUCTION Since Canada commenced sulphur exports in the early 1960's, the volume of exports has grown steadily and by 1984 Canadian sulphur accounted for 45% of internationally traded sulphur. In 1984 a total of 7.6 million tonnes of Canadian sulphur was shipped to offshore markets and the U.S.A. Total shipments, including domestic sales, were 8.3 million tonnes. With a production of some 5.6 million tonnes, inventory was drawn down by nearly 3 million tonnes in order to keep pace with demand. Since 1979, world consumption has exceeded total world production and Canadian sulphur inventory has played a truly crucial role in balancing world supply and demand. Consequently, by the end of 1984 the Canadian inventory, which stood at 21 million tonnes in 1978, had been almost halved to 12 million tonnes. This inventory, however, is still by far the largest in the world and will continue to play a vital role in the world supply until expected depletion around 1990. Canada is the world's second largest producer of sulphur following the U.S.A.. The Current production level of between 5 and 6 million tonnes per annum is forecast to be maintained to 1990 with only a marginal fall in that production level in the following decade to the year 2000. This will ensure that Canada retains its position as one of the largest producers and most important suppliers of sulphur in the world market well into the future. CANADA AS WORLD SUPPLIER OF SULPHUR Since Canada commenced sulphur exports in the early 19601s, exports have grown steadily. (Figure 1) The rate of growth accelerated in recent years and in 1984 a total of 7.6 million tonnes was sold for export, compared to 3.0 million tonnes in 1975 and less than 1 million tonnes in 1964. World trade in sulphur also increased during this period, from 11 million tonnes in 1975 to 17.0 million tonnes in 1984 (Figure 2). Most of this increase in volume was accounted for by Canada and Poland. As a result, the importance of Canada as world supplier expanded from 28% in 1975 to 45% in 1984. The markets for Canadian sulphur can be divided into two broad categories, i.e., solid and liquid (Figure 3). The solid market is the largest, taking about 70% of Canadian output, virtually all of which is sold offshore. The U.S.A. and the Canadian domestic market take about 20% and 10% respectively, in liquid form. In 1984, (figure 4) total Canadian sulphur sales exceeded 8 million tonnes with offshore export sales at a record 5.8 million tonnes and sales to the U.S. of 1.8 million tonnes. Domestic sales accounted for only 0.7 million tonnes. The general trend for offshore export sales has been upward whereas there has been relative stability in domestic sales. The exceptional growth in offshore sales in the 1970's necessitated considerable capital investments by the industry in order to establish a logistics system capable of handling increasing offshore tonnages. Over 50 sulphur plants are currently operating in Alberta and British Columbia. Some of these are connected by rail, (Figure 5) the balance being generally connected by road. There are currently fourteen of the larger rail-connected plants designated as export plants, and these are equipped with sulphur forming facilities. The long distances between these plants and tidewater terminals in Vancouver is a very significant factor in complex logistics of Canadian offshore sulphur exports (Figure 6). Alberta and B.C. plants are located an average of 1,400 kilometers from tidewater.

Jan 1, 1986

By Gilbert C. Robinson

Manufacturers of brick and tile are showing growing interest in the possibility of manufacture of a clay bonded block. The block would have the shape of concrete block, but would be made without the use of Portland cement, Instead, the block would be made' from mixtures' of an aggregate and the present raw materials of the brick industry. The finished units would weigh 20 to 30 pounds and meet the specifications for Grade A concrete block. The present status of the clay block development shows one manufacturer actually in production of these units$, two additional manufacturers are attempting production and many manufacturers are actively engaged in development work. At least four major research laboratories are engaged in the development program. There are several different processes available for clay block production. These processes differ primarily in the type of aggregate used or in the type of forming operation selected. I would like summarize these possible methods.

Jan 1, 1960

By Wayne S. Cavender

The geochemical association of arsenic and gold in epithermal precious metal deposits of the Basin and Range province is well documented, and in this paper I wish to discuss the evaluation and utilization of this element association for geochemical gold exploration. In 1961-62, I conducted an exploration program on lands controlled by Getchell Mine, Inc, and centered about the Getchell gold mine itself, Besides exploring for new gold deposits, the program was to evaluate these lands for potential deposits of any type; thus, a multi-phase program encompassing a number of exploration methods was conducted. I shall not elaborate on the process of designing the program or of integrating the various methods, but for gold exploration, geochemical methods were determined to have the best potential. This paper is based on that effort. Figure 1 shows the exploration area, which covers the northern half of the Osgood Mountains in eastern Humboldt County, Nevada. The Getchell $line is on the east flank of the range and is about 40 miles northeast of Winnemucca.

Jan 1, 1964

By S. Chander

The formation of surface films on pyrite has been studied through electrochemical techniques of cyclic voltametry and AC impedance measurements. The characteristics of the surface films depend upon the conditions of oxidation and the source of pyrite. At potentials near 0.0 V, some pyrites have large values of polarization resistance showing a certain degree of passivity. Some pyrites show more passivation than the others, however. On oxidation, metastable phases of Fe(OH2) and Fe(OH3) form which transform to more stable 3 phases on aging. The growth of surface films near the corrosion potential of pyrite follows a linear kinetics which is attributed to a chemical (or an electrochemical) reaction as the rate determining step. The surface film is considered to be a hydroxide or an oxide rather than sulfur because the later is expected to be limited to a monolayer in alkaline solutions. This study has also demonstrated that AC impedance measurements can be used to study the growth characteristics of films at mineral/ solution interfaces.

Jan 1, 1987

By Terrence J. Stobbe

On the job injuries to the musculoskeletal system are probably the oldest of the industrial safety problems. Long before we had pinchpoints to guard, chemical vapors to ventilate, and noise to enclose, people were getting strains, sprains, and sore backs from their work activities. In spite of the age of the problem, it remains a long way from being solved. The past ten years have seen a significant commitment by the sci¬entific community to understanding the problem. Engineers, scientists, doctors, and epidemi¬ologists have been involved, and as a result, today we have a much better understanding of the problem. The first step in understanding a problem such as this is to explore its history and epidemiology. The research done by Chaffin (1977), Snook (1970), Ayoub (1978), the ILO (1962), and others, led NIOSH to publish its Work Practices Guide for Manual Lifting in 1981. The guide was based on research carried out in general industry, but subsequent research by Stobbe (1983) and Peters (1983) has suggested that the nature of the problems producing injuries in underground mining is the same as in general industry. The problems are more intense in the mining environment.

Jan 1, 1984