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By A. M. Olivarez

The elucidation of the theory of plate tectonics has provided a conceptual framework for understanding the formation and distribution of different types of ore deposits. For example, we now recognize that certain kinds of mineral deposits are generally associated with a particular type of plate boundary (i.e., massive sulfides often occur along divergent plate boundaries, whereas porphyry copper deposits are typically found along convergent boundaries). During certain geologic time periods, plate reorganization events have changed the relative proportion of different types of plate boundaries. Corresponding changes have been observed in the abundance and distribution of ores deposited during these times. The present study examines the temporal aspects of this relationship; i.e., do plate reorganization events play an active or passive role in ore formation? In other words, do plate reorganizations simply provide a more favorable tectonic setting in which ore formation can occur over significant time periods, or are they directly linked to the mineralization process? We have examined this question by comparing regional tectonic histories with the ages of known massive sulfide and porphyry copper deposits. Because these deposits, in particular massive sulfides, form as a result of hydrothermal activity, we have also compared regional tectonic histories with proxy indicators of this process in the marine sedimentary record. These indicators include increased mass accumulation rates of Ca, Fe, Mn, and opal, characteristic changes in the Sr/Ca and Mg/Ca ratios of biogenous carbonates, and shoaling of the carbonate compenstion

Jan 1, 1988

This paper presents the water management plan of the Mae Moh Project in the North of Thailand, which includes a large lignite opencast mine and thermal power plants. Lignite production will increase from the present 5.5 million tons per annum to approximately 20 million tons per annum by 1995 when the pit area will be about 20 sq.km. and the depth at over 300 meters. Seven power plants are proposed of which two are under construction. The total capacity to be installed is 2,925 MW. The principles considered for water management are firstly flood protection, including drainage of the mining pit and diversion of the Mae Moh stream away from proposed future mining areas; and secondly, a plan to meet the water requirement of the thermal power plants, while maintaining downstream supplies for irrigation and other purposes. The limited annual run-off of Mae Moh and Mae Chang watershed basins are inadequate for the proposed power plants. A study has been prepared to compare two approaches, namely conveying water from remote watersheds to meet the water requirement of the power plants up to total installed capacity; or by limiting future total generation, at the existing site, to only 2025 MV.

Jan 1, 1988

By J. E. Spencer

Mesozoic and Tertiary mineral deposits in west-central Arizona are commonly associated with Mesozoic thrust faults and Tertiary detachment faults, respectively. Quartz-kyanite rocks and pyritic quartz-sericite schists with local anomalous gold are the product of probable Jurassic argillic alteration of Jurassic volcanic, sedimentary, and plutonic rocks followed by Cretaceous thrust burial and associated metamorphism. Slivers and sheets of Paleozoic carbonates along Mesozoic thrust faults were locally sites of syn-and post-thrust mineralization. Widespread brecciation along Tertiary detachment faults resulted in increased permeability along fault zones. Elevated thermal gradients also resulted from detachment faulting and apparently caused convective aqueous-fluid circulation along detachment faults and associated Fe+Cu±Au mineralization.

Jan 1, 1988

By R. Jin

Fine coal flotation using gaseous carbon dioxide has demonstrated the potential for producing superclean coal. The success of this new flotation .procedure is attributed to the coal's high adsorption potential for CO2. To understand the nature of gas-phase CO2 adsorption at the coal surface, in-situ FTIR spectroscopy in a controlled-environment chamber with an ultravacuum sys-tem has been used and the results are discussed in view of other experimental results from differential scanning calorimetry. It has been found that specifically adsorbed CO2 molecules at the coal surface are polarized and have a characteristic doublet at 2336 and 2361 cm-1. Two adsorption states have been proposed to account for the doublet observed from in-situ FTIR spectroscopy measurements. It is believed that the band at 2336 cm-1 originates from the activated site adsorption of CO2 and that the band at 2361 cm-1 arises due to the molecular aggregation of CO2 within the coal pores.

Jan 1, 1988

By G. L. Merritt

The implementation of the Surface Mining Control and Reclamation Act of 1977 (SMCRA) has evolved into one of the most complex environmental protection programs to come out of the late 1970's. The level of detail in the statute and the regulations have resulted in a rigid and complex set of requirements for the administration, permit-ting, inspection and enforcement of the program. In addition, the constant change of the federal program caused by regulatory changes, reorganization of the Office of Sur-face Mining Reclamation and Enforcement (OSMRE), ongoing litigation involving OSMRE, and the use of the budget to establish additional mandates on OSMRE and the State Regulatory Authorities have resulted in an unstable program. The instability of the program makes it extremely difficult for the States to implement their programs and to achieve the goals of SMCRA.

Jan 1, 1988

By Michael S. Miller

In 1986 and 1987, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the nine separate parcels that comprise the 4,330-acre South Warner Contiguous Wilderness Study Area in order to evaluate their identified mineral resources. The nine parcels are along the east side of the South Warner Wilderness. They are, from north to south, the Granger, Milk, Cottonwood, Owl, Hornback, Eagle, Emerson, Barber, and Van Riper parcels. The Wilderness Study Area is underlain by basaltic, andesitic, and rhyolitic volcanic rocks and by sand and gravel deposits. Low-grade metamorphism is widespread in the volcanic rocks, with quartz, zeolites, datolite, chlorite, and calcite locally abundant in veins and amygdules. The rocks have been displaced by the mountain-front Surprise Valley fault and by crosscutting high-angle faults.

Jan 1, 1988

By J. D. Shenk

The White Cliffs diatomite deposit occurs in a lacustrine facies of the Quiburis Formation, an Upper Miocene to Pliocene basin-fill sediment of the lower San Pedro Valley. On-going geo-logic mapping has defined an 2.5-3.0 m (8-10 ft) thick ore zone near the mill site, several marker beds, a NNW-trending high-angle normal fault, and a NW-trending syncline. The diatomite has an average loose-weight dry bulk density of 130 kg/m3 (8 lbs/ft3) and is presently marketed outside Arizona for asphalt filler. Current development is projected to yield 3500 mt (4000 st) of finished product, with an estimated 91,000 mt (100,000 st) of finished product obtain-able from several other nearby sites.

Jan 1, 1988

By Arthur S. Klein, Hugh R. Lowry

"The Levitation Casting Process is a new continuous casting method that uses an electromagnetic levitation field, instead of a mold, to support and contain a column of solidifying metal. By counteracting gravitational forces and hydrostatic pressure on the metal column, this process eliminates friction and adhesion at the interface between the solidifying metal and the cooled walls of the casting chamber. The process inherently provides high casting speeds, excellent dimensional control and smooth, continuous emergence of solidified product from the top of the casting chamber.Of major importance is that the electromagnetic field produces an intense stirring of the liquid metal both before and during solidification. As a result of this stirring, the cast product has a homogeneous, equiaxed, fine grain structure generally suitable for immediate drawing or other forming operations without the need for hot rolling or other expensive additional processing.This paper reviews the fundamentals of the Levitation Casting Process, results obtained in casting various pure metals and alloys, and the production sized system at Lowell, MA, that uses this process. IntroductionThe Levitation Casting process was specifically developed to meet several requirements including:• Economic at low casting rates• Usable with pure metals and alloys• High, uniform product quality suitable for fine wire drawing or cold rolling into flat strip and tape• Easy cast product shape and size changes• Process inherently stable and easily automatedIn meeting these criteria it was also desired to retain the advantages of General Electric's well known Dip Forming continuous casting process; namely the inherent ""fail-safe"" properties of upward casting, solidifying metal by means other than pressure contact with a cooled mold, and use of a sealed furnace, casting chamber and cooling tower, filled with a protective atmosphere, to prevent oxidation of the molten metal or cast product."

Jan 1, 1988

Chief Geologist, Groundwater and Engineering Geology Branch South Australian Department of Mines and Energy The six papers submitted for consideration during this session include two dealing with techniques for measing rock mass behaviour, including permeability, in boreholes, one describing the use of surface geophysical methods to delineate pollution plumes in groundwater together with analytical modelling of the plume, and one presenting a biological tracer technique applied to the determination of the origin of water entering underground mine workings. A paper describing dewatering at a base metal mine in Queensland includes an account of the investigation techniques employed to establish a conceptual model as a basis for the evaluation of various dewatering strategies. Of considerable interest is the use of a field gravity survey to delineate a zone of highly weathered rock which forms the major aquifer at the site.

Jan 1, 1988

By J. Allan Tice

In the past fifteen to twenty years, the use of drilled piers to support high capacities in coastal plain deposits has become more and more common. With improved construction techniques and better understanding of pier behavior, drilled shafts with capacities of 200 to 500 tons are not unusual. The purpose of this presentation is to review several drilled pier installations from North Carolina to north-east Florida as a means of illustrating the different types of design concepts and installation techniques which are presently being used. ACKNOWLEDGEMENTS The information in this presentation was obtained from work performed by many individuals and companies. The section on limestone socket caissons in South Carolina is an abridged version of a paper prepared by Rob Smith and Neil Gilbert of Law Engineering's Charlotte, North Carolina office, and is used with permission. The section on pier installation in northeast Florida is an abridged version of a paper prepared by Kirk Mcintosh, Tom McDaniel, and Randy Knott of Law Engineering's Jacksonville, Florida office, reprinted here with permission. Additional data discussed in this presentation has been obtained from Farr Foundation Company, McKinney Drilling Company, and Peterson Drilling Company.

Jan 1, 1988

By E. S. Geskin, W. L. Chen, A. Vora

"This paper is concerned with the application of an abrasive waterjet for metal shaping. The waterjet cutting technology uses water compressed to the pressure up to 55,000 psia which is accelerated in a cylindric nozzle. Abrasive particles are then supplied into the water stream and accelerated by the water. Cutting occurs via the interaction between the water-particles stream and a workpiece that causes material erosion at the impingement zone. The mechanism of this interaction enables shaping of practically any material with a minimal effect on the metallurgy of subsurface. The motion of the jet penetrating through a material body is guided by a robotic arm. A waterjet cutter is becoming one of the principal tools for shaping titanium, super-alloys and other hard-to-machine metals and composites. The shaping, resulting from the waterjet cutter, is very similar to laser beam cutting. However, unlike laser processing, there is no damage to the subsurface structure.The presented work discusses the experimental study of cutting of titanium plates. The results of these experiments demonstrate the potential of the abrasive waterjet as a shaping tool. IntroductionOne of the main avenues in the development of metal shaping is the use of high energy beams as cutting tools (1,2). There are a number of advanced beam oriented material removal technologies, such as laser, electron beam, plasma and abrasive waterjet (AWJ) cutting. The advantages of AWJ cutting are well understood and documented (3-14). This technology has the potential of becoming the principal tool for netshaping and netsurfacing of parts. However, the use of AWJ is currently limited to cutting of hard-to-machine materials such as titanium, superalloys, glass, composites, etc. The cost of A W J cutting is much higher and the productivity is much lower than those of the thermal cutting. At the same time abrasive waterjet can be used for shaping any existing technological material from fabrics, plastics, aluminum to glass, composites, and diamonds. The material losses during AWJ shaping are minimal. The roughness and waveness of the surfaces generated during AWJ cutting are substantially less than those of the thermal cutting. Due to the size of the jet cross-section total force exerted by the jet on a workpiece does not exceed 30-50 newtons. This terminates the need in the use of complex fixture for material holding. Low applied forces and low surface temperature prevent the damage of metal subsurface in the course of cutting. The small size of the impingement area will determine the limited width of the kerf. Due to the size of kerf and unidirectional character of the water jet the formation of practically any metal contour is possible."

Jan 1, 1988

By S. J. Hogan, T. William

"By the year 2000, the steel industry, not only in the United States but in the rest of the world, will undergo significant changes. On the other hand, there will be a number of areas in which change will be minimal.The current capacity of the industry worldwide is approximately 800-810 million metric tons. This may grow to some extent, as Third World countries install capacity. However, much of it will be neutralized as the industrialized countries shrink their current capacities.There will be several breakthroughs in terms of technology, some of which deal with the production of iron outside of the blast furnace. However, these processes will not be far enough advanced by that time to replace the blast furnace, rather they will supplement it.In terms of steelmaking and the subsequent rolling process, there should be a number of basic improvements. The strip mills will roll sheets with a very slight variance in gauge, which will give the customers a better product for automatic stamping machines. Ordinary carbon steel, in a number of instances, will be replaced by high-strength, low-alloy steel, which will reduce the tonnage necessary for present-day applications, such as construction.The corporate organization will be significantly changed as joint ventures and mergers will reduce the number of companies, as well as facilities in operation. This will enable the industry to reduce its capital investment and improve operating costs, so that it will be able more effectively to compete with other materials, such as plastics, cement, aluminum, etc."

Jan 1, 1988

By John D. Nelson, Clint L. Strachan

Drainage of tailings impoundments is a key issue for impoundment stability, water control, seepage control, and reclamation. Drainage control is an established operating practice where climate and site conditions permit, such as in South Africa and various mines in North America. In these areas, drainage control is primarily used to maximize tailings densities and to provide adequate impoundment stability. Drainage practices during operation also become an important issue when tailings impoundments are reclaimed. Time required for cover placement and post- reclamation seepage control depends greatly on the ability for tailings to drain and consolidate. This paper discusses drainage issues associated with gold tailings impoundments in terms of mechanics of saturated and unsaturated flow and experience with design and reclamation of tailings impoundments.

Jan 1, 1988

By C. S. Simons

This paper presents a review of the extractive processes used in the production of nickel, with emphasis on developments since the beginning of the Second World War. Attention is given to the factors, many outside the nickel industry itself, which determined the direction of process research and strongly influenced the ultimate commitments to industrialize the resulting developments. An example of such a factor is the sudden surge in demand, far exceeding the then available nickel production capacity, that was caused by the advent of World War II; the result was the first serious consideration ever given to low- grade laterites as a viable source of primary nickel. Other factors discussed include such items as process development in the extraction of other metals - particularly copper; the availability of increasingly sophisticated materials of const- ruction; the advent of the "environmentalist" and related political developments; the massive escalation in the price of energy - particularly oil. The paper concludes with an attempt to forecast the nature of the most effective nickel process of the future, based on extrapolation from the economic and political situation that exists today.

Jan 1, 1988

By Michael S. Miller

In 1986 and 1987, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 550-acre Carson-Iceberg Wilderness Study Area (NV-030-532), in order to evaluate its identified mineral resources. The Wilderness Study Area is located in Alpine County, CA, 11 mi southeast of Markleeville, CA. Tertiary volcanic and granitic rocks, as well as alluvium, underlie the area. Hydrothermal alteration and faulting have affected some rocks; argillic, silicic, and limonitic alteration are found, particularly near faults. No mineral resources were identified in the Wilderness Study Area. The area has one small pit and no mines or claims. Samples from the Wilderness Study Area and vicinity contained uneconomic amounts of gold, silver, copper, lead, zinc, mercury, arsenic, and molybdenum. Mineral occurrences are too small and low grade to be of interest within the foreseeable future.

Jan 1, 1988

By R. V. Ramani, R. Bhaskar

"The National Academy of Sciences (1) recognized the importance of studying the spatial and temporal characteristics of respirable coal mine dust atmospheres. In this paper, the progress to date of a research project on dust transportation and deposition in mine airways is presented. A mathematical model is proposed for studying the transport of dust. A source representative of dust generation in underground coal mining is defined. The influence and applicability of surface roughness, dispersivities, coagulation and reentrainment to vine dust flow arc examined. A convective-diffusion model is proposed for the transport and deposition of dust in mine airways. Using the model, the spatial and temporal characteristics can be evaluated in terms of dust concentrations in the mine atmospheres.INTRODUCTIONThe prediction of the behavior of fine particles Is Important in many fields of science and engi¬neering including physics, chemistry, mining, mineral processing, and atmospheric science. In mining from the health point of view, fine coal dust is associated with the appearance of pneumoconiosis in miners exposed to the dust. Also, in addition to being a nuisance factor obscuring visibility and general mobility of miners, it can lead to sudden catastrophic incidences of explosions. This paper outlines the progress to date of a research project on dust transportation and deposition in mine airways. A mathematical model is proposed for studying the transport of dust for the various mechanisms. The dust dispersion is defined in terms of a dispersion term determined from experimental data by Skubunov (23). Coagulation is considered as one of the mechanisms that can lead to changes in the particle size distribution. Reentrainment as a possible secondary source of dust was examined during model development but was not included in the final model."

Jan 1, 1988

By N. Greninger

The Bureau of Mines conducted a laboratory study of the measurement of the water and rock dust (RD) contents of synthetic mine-type coal dust (CD) mixtures using a commercial unit for measuring water content and several prototype radiometric units for measuring the RD content. The RD content ranged from 50 to 100 wt pct and the added water (AW) ranged from 0 to 15 wt pct. The total water (TW) content (intrinsic (IW) and AW) of a small dust sample could be readily measured automatically by essentially untrained personnel using a commercial unit. The RD content of a sample containing only IW could readily be measured by moderately trained personnel using several radiometric units. With gamma-ray devices, about 300 g of sample is needed. With the improved beta-ray device, about 25 g of sample is needed. With dry mine dust samples, the estimated RD error range for gamma-ray devices is 0.8 to 2.3 pct and 0.5 to 1.0 pct for beta-ray devices. However, the radiometric measurement of RD content was questionable if the dust mixture also contained AW or if it was uncertain whether the dust mixture contained AW.

Jan 1, 1988

By N. S. Dalal, V. Castranova, X. Shi, W. Wrr, V. Vallyathan

"SUMMARY Data presented here indicate that freshly fractured silica exhibits surface characteristics and biologic reactivity distinct from aged silica, and on this basis we propose that these surface features may lead to enhanced manifestations of lung Injury. Grinding of silica produces ~10"" Si and SI-O (silicon-based) radicals per gram of dust on the particulate surface which are characterized by an electron spin resonance (ESR) spectrum centered around g = 2.0015. These silicon-based radicals react with aqueous media to produce OH radicals, which are demonstrable using a DMPO spin trap. The concentration of silicon-based radicals in silica decreases with aging in air and exhibits a half-life of ~30 h, whereas its ability to generate OH radicals in aqueous solution decreases with a half-life of ~20 h. However, on storage in aqueous media, the concentration of silicon-based radicals end the dust's ability to generate OH radicals decrease significantly within a few minutes. Freshly ground silica is also more biologically reactive than aged silica, because freshly crushed silica activates a greater respiratory burst In alveolar macrophages than aged silica, i.e., storage of ground dust in air decreases silica-Induced superoxide anion secretion, hydrogen peroxide release, and NBT reduction by 25%, 68%, and 43%, respectively. Furthermore, compared to aged silica, freshly ground silica exhibits a greater cytotoxic effect on cellular membrane Integrity, i.e., a 1.5-fold increase in LDH release from macrophages, a 36-fold increase in hemolytic activity, and a three-fold increase in the ability to induce lipid peroxidation. Because acute silicosis is frequently associated with occupations in which freshly fractured crystalline silica of respirable size is generated, the present study suggests that fracture-generated silicon-based radicals may play a significant role in the pathogenesis of this disease. AM REV RESPIR DIS 1955; 133:1213-1218IntroductionOccupational exposure to crystalline silica can be associated with either chronic or acute pulmonary disease. Chronic silicosis becomes manifest 20 to 40 years after first exposure and is characterized by development of concentric hyalinized nodular lesions in the lung with the de-velopment of dyspnea over a period of several decades. Acute silicosis, on the other hand, is manifested by a rapid on-set after exposure and is characterized by the accumulation of an amorphous granular lipoprotein exudate in the airspaces and rapid development of respiratory disability within a few years (1-3).Information is growing concerning the etiology of chronic silicosis. Studies sug-gest that several mechanisms may be in-volved in the development of fibrosis. Lung injury may result from silica-induced release of lysosomal enzymes from alveolar macrophages (4, 5). In ad-dition, silica-induced activation of su-peroxide anion and hydrogen peroxide release from alveolar macrophages may result in oxidant-induced damage to lung parenchyma (6). Silica exposure can also result in the release of mediators from alveolar macrophages which enhance the proliferation of fibroblasts and the syn-thesis of collagen by these pneumocytes (7, 8)."

Jan 1, 1988

AND INTRODUCTION The Lochiel coal deposit, a large Tertiary soft brown coal deposit in the mid north of South Australia, is currently being investigated by the Electricity Trust of South Australia (ETSA) as a potential source of fuel for a base load power station. Feasibility studies indicated that the proposed dragline method of overburden removal was viable but economically sensitive to both highwail and dump batter angles. The unusual properties of the unconsolidated overburden sediments and the groundwater regime posed a number of intimately related hydrogeological and geotechnical questions which were addressed before and during the excavation of a trial pit. All strata at Lochiel are of soil strength, and artesian aquifers occur above and below the coal. From the initial evaluation of the deposit a number of hydrogeological questions were defined. These related to the rate at which the pore pressure in the silts is reduced by dewatering, the extent of the reduction in pore pressure due to prestripping, and the feasibility of dewatering and depressurising carbonaceous silty sand sequences. The site of the trial pit was selected to answer these and other questions from the basis of a detailed geological, hydrogeological and geotechnical understanding. The trial pit dewatering system simulated a full scale mine dewatering system and included ten pumped wells, twenty drainage wells, and nearly 400 monitoring instruments. It operated from September 1986 to June 1987. The excavation was carried out between February and May 1987.

Jan 1, 1988

By Thomas J. Peters

In 1987, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied the 15,174-acre Sleeping Giant study area, including the 6,112-acre Wilderness Study Area (MT-075-111), in order to evaluate its identified mineral resources. The study area is located in Lewis and Clark County, MT, about 30 miles north of Helena. Sleeping Giant Mountain trends west-northwest from the Missouri to the eastern crest of Little Prickly Pear Canyon (the route of Interstate 15), and has several summits over 6,000 ft. Geologically, the area is in the Disturbed Belt, and a large block of Middle Precambrian metasedimentary siltstone and underlying shale has been thrust northeast over younger, sedimentdry volcanic and intrusive rocks.

Jan 1, 1988