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By Dinah O. Shumway

California's annual production of >11 million tons of cement, at a value of over $640 million, comes from eight companies, which operate 11 plants. Cement is California's second most important mineral commodity, representing 25% of its total annual mineral production. Although most of the cement produced is consumed within the state, current export locales include the Pacific Northwest, Nevada, Arizona, Utah, and New Mexico. An enumeration of the components required to produce cement is deceptively simple: calcium oxide (65%), silica (20%), alumina (4-5%), iron (3-4%), and calcium sulfate (4%) as a retardant admixture. The last, and most expensive, ingredient in cement manufacture is energy. Detrimental materials in cement mixes include excess .magnesium, alkalis, heavy metals, sulfur, and other volatiles. Each of the 11 cement plants in California requires a unique chemical solution of combined raw materials to produce a uniform product: portland cement. The geologist proposing solutions for the additive raw materials in cement manufacture must have a thorough knowledge of a particular cement plant's needs. In the California cement market, keeping the costs of additive raw materials down is one way to also stay competitive, and using a combination of natural and waste materials as additive raw materials allows cement producers to stay competitive.

Jan 1, 1999

By G. D. Hood, B. E. Davis

A problem that has continued to plague the Florida phosphate industry is loss of coarse phosphate in the flotation circuit. Attempts to remedy this problem such as floating the coarse material (plus 425 µm) in a separate circuit have resulted in limited success, but recovery is still not optimum. A fundamental examination of the mechanisms involved in the conditioning of the coarse phosphate has led to results that seem to supersede common paradigms. The Bureau of Mines investigated conditioning parameters such as fatty acid/fuel oil dosage, residual clay content in the feed, conditioning time, mixing intensity, and conditioner solids content. The study revealed that the effect of all these parameters was important. However, it was discovered that contrary to common beliefs, the conditioning time affected the grade of the rougher concentrate much more than the recovery. Specifically, the longer the conditioning time, the less quartz that was floated. It was also discovered that high mixing intensity conditioners could lower the conditioning time required for good grade. Many phosphate operators use low intensity drum type conditioners. Optimizing the conditioning time, mixing intensity, and other conditioning parameters resulted in a rougher concentrate grading 30 pct P.2O5, with an attendant recovery of 95 pct.

Jan 1, 1993

By C. McLean, S. G. Kolb, A. J. Erickson, S. C. Moore

The Grossschloppen vein-uranium deposit, Bavaria, West Germany, was examined with underground workings during 1980-82 by Esso Erz GmbH, an affiliate of Exxon Minerals Company (EMC). Geologic evaluation entailed dense drilling of a portion of the deposit from workings constructed specifically for the program. Discovered in 1977, the deposit was initially explored by surface diamond drillholes which allowed definition of a 30-60 m wide vein system discontinuously mineralized along a 1000 m strike length and to at least a 450 m depth. The underground program was conceived as a cost-effective procedure to answer questions on vein correlation, grade continuity and variability. A 1200 m decline allowed access for detailed sampling of approximately 10% of the known area of mineralization. Fanned drillholes, logged by gamma probe, were spaced to provide intersections of veins at 10 to 20 m intervals. Six cross-cuts also penetrate the pitchblende and uranophane mineralization which occurs in 0.1 to 2.5 m thick quartz veins. Detailed cross-sections and level plans were constructed for resource estimates of the intensively studied portion of the vein system. The program resulted in the discovery of local, high grade areas and an average grade in the evaluated area nearly double that expected from surface drilling.

Jan 1, 1992

By Matthew Spedding

The complex nature of the carboniferous measures prevailing in the U.K. has dictated the types of mining required to exploit the coal seams. Most mines in Britain are referred to as deep mines in the sense that they operate at depths of 1800 - 3000 feet. The main system of coal transport to the surface is by vertical shafts which intersect the workable seams which at times number between 4 and 5. As mining has been practiced in most of the major coalfields in the U.K. for well over 100 years, with the initial extraction of the shallower and more profitable seams, the present management have been left a legacy of indiscriminate extraction which severely hampers their efforts to maximise the mine layouts. There is no single standard design of mining layout capable of meeting the wide variety of conditions which exist in the British coalfields. Mining layouts are subject to fixed and variable parameters. In discussing multi-seam working, the main parameter must be the effect of old workings above and below the seam to be extracted. There is a distinct lack of reliable information which would enable layouts to be designed to completely avoid or control these destructive forces. The guidelines are, therefore, mostly empirical.

Jan 1, 1977

By John R. Keith

Keith, John R. 1968. Relationships of lead and zinc contents of trees and soils, Upper Mississippi Valley District. Preprint, Fall 1968 Meeting, Soc. Mining Engineers of AIME. Lead and zinc contents of elm, maple, and oak trees and of soils in which the trees grew were determined in samples from the Upper Mississippi Valley mining district, and from an area outside but contiguous to the district. The lead and zinc analyses of plant materials served to differentiate the mineralized and non-mineralized areas. Stems contained about two times as much lead and about 2-5 times as much zinc as did leaves taken from the same stems. Lead and zinc analyses of all soil horizons could be used to differentiate between the two areas. Soils at most sample sites in the mineralized district seemed to be more reliable than plants for geochemical prospecting and are a more practical sampling medium. Soil samples from areas with thick loess cover, however, failed to indicate the presence of mineralized bodies whereas tree samples from the same sites contained anomalous amounts of lead and zinc. It is suggested that in areas of thick loess cover plant samples could be used in prospecting for lead and zinc.

Jan 1, 1968

By C. G. Cunningham

The Marysvale volcanic field of west-central Utah contains large areas of argillically altered rocks (fig. 1) that, in turn, enclose smaller areas of fine-grained, medium-grade, replacement alunite deposits and coarsely crystalline, high-grade vein-type alunite deposits. The largest replacement alunite deposits are [ ] located peripheral to a 23-m.y.-old monzonite stock called the Central Intrusive (fig. 1). The deposits formed in near-surface, highly oxidizing environments at the tops of hydrothermal plumes that were spaced irregularly around the stock. The deposits are horizontally zoned from alunitic cores through kaolinitic to propylitic envelopes. Vertically, characteristic alteration minerals progress from a pyrite-propylitic alteration assemblage at the base, upward through alunitic, jarositic, and hematitic assemblages to a flooded silica cap as shown on figure 2. The silica caps are cut by hydrothermal explosion breccias. d34Sso4 values of + 11.5 to + 15.4 permil indicate that sulfur in the hydrothermal plume was derived from underlying Mesozoic evaporites. The sharp upward transition from pyrite- propylite to alunite probably marks the paleowater table, and the top of the flooded silica cap represents the paleoground surface. Basin-Range extensional tectonism began shortly after alteration, and buried the replacement alunite deposits in basins beneath sediments eroded from uplands. The deposits were only recently exhumed.

Jan 1, 2013

By William A. Kneller

Fifteen samples of chert from seven localities in Ohio were tested for potential durability and reactivity in concrete. The tests determined are porosity, pore-size distribution, relative degree crystallinity, specific surface area, and degree of dissolution according to the ASTM C289-71, Potential Reactivity of Aggregates, Chemical Methods. The results of these tests were compared with petrographic, electron optical, physical-chemical, and engineering properties of the chert samples. Based on these tests, the important properties that affect the durability and reactivity of chert in concrete were observed to be: (1) porosity, (2) pore-size distribution or pore spectra, (3) relative degree of crystallinity, (4) grain size, (5) specific surface area, (6) impurities, and (7) amount and species of quartz present-all of which are functions of original composition, time (geologic age), depth of burial, tectonics, and diagenesis. Preliminary results of this study indicated that the geologic history and physical-chemical properties of chert vary from one sample to another, and any one or combination of these parameters affect the performance of the chert in concrete. These complex interrelationships are difficult to ascertain; if the performance of the chert in concrete is to be predicted, it is necessary to study in detail this enigmatic material.

Jan 1, 1978

By G. Brofas

The reforestation potential of bauxite mining spoils by seeding was examined on this research work. The experimental plot was established on the location Strofi Koukouvista 5, Ghiona Mountain. The experiment consists of 3 species (Pinus nigra, Robinia pseudoacacia, and Spartium junceum) with 4 sowing treatments and 2 sowing seasons (autumn and spring). The treatments were: (1) broadcasting; (2) broadcasting and soil cultivation; (3) broadcasting with straw mulching and straw binding with asphalt emulsion; (4) broadcasting with soil cultivation, straw mulching and straw binding with asphalt emulsion. Third year results show that spring is better than autumn as a sowing season. Only the Spartium junceum species were found to germinate and survive in autumn. The results are better for all the species on the spring seeding. The most effective treatments for Robinia pseudoacacia and Pinus nigra are 3 and 4 while for the Spartium junceum even simple broadcasting shows good results although the best ones are achieved with treatments 2, 3 and 4. The paper?s findings show that reforestation by sowing could be effective for some species but further experimentation with other species is recommended. Concerning Robinia pseudoacacia, testing of different seed preparation treatments is needed in order to maximize the germination of seeds.

Jan 1, 2002

By Ronald R. H. Cohen, Margaret W. Staub

Two pilot scale bioreactors designed to treat acid mine drainage primarily using sulfate reducing bacteria were constructed underground at the Eagle Mine Superfund site in Minturn Colorado. The project was designed to test th applicability of microbiological treatment on water with high metals concentration and to test the process in an underground environment. Objectives were, 1) to compare metal removal, pH increase, and sulfate reduction in a single stage reactor with a double stage reactor of equal volume at varying flow rates; 2) to determine where within the substrate treatment occurs· and 3) to examine volume versus surface ara as a design parameter for optimizing metal removal processes. Results from the reactors showed that the single stage reactor and double stage reactor performed equally well for the removal of Cd, Cu, Pb, Fe, Mn, and Zn. pH increased above 6.5 in both reactors. Greater than 97% of metals were removed within the first ten inches of substrate. Volume proved to be a more useful parameter for determining removal rates than area. Using volume as a design parameter rather than surface area enables PMDT systems to be constructed as packed columns rather than broad wetlands, Thus, space requirements are significantly reduced.

Jan 1, 1993

By Raymond E. Krauss

The McLaughlin Mine is based on a world class epithermal gold deposit located in the coastal thrust fault of northern California, about 1 12 air km (70 air miles) north of San Francisco. Owned and operated by Homestake Mining Co., the McLaughlin deposit contains about 18 Mt (20 million st) of gold ore at an average grade of 5.2 g/t (0.152 oz per st), or about 93 t (3 million oz). The area was identified as a gold target by Homestake in early 1978. Drilling confirmed it to be a commercial deposit by 1980. The mine was then planned, engineered, built and brought into production by March of 1985. The deposit was historically a part of the Knoxville District. It was mined for cinnabar, which was used to produce mercury for use in recovering gold and silver in the Mother Lode and Comstock districts. At that time, the mine was called the Manhatten and later the One Shot Mine. It was worked for more than 100 years, producing about 76,000 flasks of mercury without any awareness of the presence of economic concentrations of gold. By 1978, the site was largely disturbed and entirely unreclaimed.

Jan 1, 1990

By I. Fafoutis

Laboratory column studies were conducted in order to assess the effectiveness of slag and red mud reactive barriers for cleaning up leachates generated at mining and waste disposal sites and loaded with copper and manganese. Solutions containing the metals of concern were prepared by dissolving the required quantities of CuSO4?5H2O and MnSO4?H2O in distilled water so that Cu concentration was 100 ppm and Mn 20 ppm. Flow rates of 25 mL.h-1 for Cu solution and 75 mL.h-1 for Mn solution were used in order to simulate aquifer water velocities of 1 ft/d and 3 ft/d respectively. Solutions were pumped upflow, in Plexiglas laboratory columns filled with each reactive medium, using peristaltic pumps. Measurements of middle and outflow column pH, redox potential, conductivity and elements concentration were performed to provide information regarding removal mechanisms for both elements and exhaustion/inactivation rates for each reactive medium. Both reactive media showed fairly good removal efficiency over the period studied. Copper was mainly removed by precipitation and formation of Cu(OH)2 while removal of manganese was due to precipitation of Mn(OH2).

Jan 1, 2006

By Philippe Dumont

Presentation of the project Underground civil works to be performed They include two single track running tunnels and a service tunnel of a length of fifty kilometers . Many cross adits (180 adits) : to link the tunnels (53 cross passages), to relieve air super pressure from one tunnel to the other (87 piston ducts), to install technical adits (40 electrical rooms). Two cross-overs located at one third of the whole length, allow trains to shunt from one tunnel to the other so as to ensure one way traffic in case of emergency. Pumping stations allow water to be collected at the lowest point and pumped out. 1 Main features of the tunnels 1.1 The service tunnel This 4.8 m inner diameter gallery allows During civil works - front probing operations of the geological layers encountered (front and vertical probes). - lateral soil grouting that may be necessary to facilitate the boring of the two running tunnels . During operations - Maintenance and safety vehicles traffic - Fresh air supply to running tunnels - Fire protection and drainage system - Electricity supply and control and communication. The service tunnel has been bored with a 5.72 meter external diameter Robbins TBM for the undersea section, and a MITSUBISHI TBM for the land section.

Jan 1, 1991

By Al Sylvester

The drill-and-shoot excavation of the two underground Pumphouses for the Metropolitan Sanitary District of Greater Chicago's Mainstream Pumping Station is described. The construction sequence involved the concurrent excavation and support of the two 19.2 m (63 feet) wide by 83.6 m (274 feet) long by 29.3 m (96 feet) high caverns. Excavation was interrupted after taking the 6.1 m (20 feet) high top heading in order to cast-in-place a 0.2 m (8 inch) thick by 19.2 m (63 feet) wide concrete arch. The remaining 23.3 m (76 feet) of rock was then excavated in benches below the concrete arch. PROJECT DESCRIPTION Twenty-four kilometers (15 miles) southwest of the city of Chicago, Peter Kiewit Sons' Co., in a joint venture with John F. Shea Co., and Kenny Construction Co., has successfully completed the construction of the Mainstream Pumping Station for the Metropolitan Sanitary District of Greater Chicago. The five year, 169 millon dollar project is a vital component in Chicago's Deep Tunnel and Reservoir Plan in that its function is to lift the sanitary/ storm sewage back up to grade from 107 m (350 feet) below ground, and pump it to the treatment facilities 8 km (5 miles) away.

Jan 1, 1985

By William M. PhD. Schafer

The net acid generation (NAG) pH method is an important analytical tool that supplements static and kinetic tests for assessment of the acid generation risk of rock samples. This method is useful because it is simple, rapid and cost-effective; it combines features of the static and kinetic tests; and it can be conducted at mine assay labs. The NAG pH test is particularly effective for operational testing programs used to classify, selectively handle, and route potentially acid-generating waste rock. The NAG pH procedure is based on a 24 hour oxidation of a pulverized rock sample with hydrogen peroxide and subsequent measurement of the sample's pH. If the NAG pH is below a critical value, determined empirically, then the sample has the potential to generate acid in the field. The critical NAG pH value is typically within the range of 3 to 4.5, but the exact relationship between NAG pH and potential acid generation should be determined individually for each mine site, based on comparison with results of acid base accounting, humidity cell tests, and mineralogical analyses. Calibration and use of the NAG test for predicting ARD risk at several mines are described in this paper.

Jan 1, 2000

By F. D. Mendes, A. H. Martins

The high copper grade in the Igarapé Bahia (Brazil) gold-copper ore restricts the direct application of the classical cyanidation process. Copper oxide and sulfide minerals react with cyanides in solution, causing high leach-reagent consumption, raising processing costs and decreasing gold recovery. According to studies, a feasible solution would be to pretreat the ore to remove copper minerals prior to cyanidation. The goal of this experimental work was to study the conditions for the removal of copper from the Igarapé Bahia gold-copper ore by sulfuric acid leaching, applying a statistical approach to the experimental design. By using the Plackett Burman method, it was possible to select the variables that exhibited the largest influence on copper extraction at the sulfuric acid leaching stage. These variables were leach solution temperature, stirring speed, sulfuric acid concentration in the leach solution and ore particle size. The individual effect of these variables and their interaction influences on the experimental response were analyzed by applying the replicated full-factorial design method. Finally, the selected variables were optimized by the ascending-path statistical method, which determined the best leach experimental conditions for maximum copper extraction. The optimized leaching conditions resulted in a copper extraction of 75.5%. Keywords: Copper, Gold, Extraction, Sulfuric leaching, Optimization

Jan 1, 2003

By J. M. Dean, R. L. Grayson, N. P. Reddy, Y. J. Wang

This 1988 survey provided a cross section of computer software use by the US coal industry. From 1250 mailed questionnaires, 171 responses were received, representing a 4.9% sampling of the 3496 US coal mines. Since the distribution of responses by regional stratum matched well with the distribution of mines by stratum, the survey was given statistical validity. A statistical description details the computer use by region, mining type, organizational size, the level of application within the organization, the type of software application used, the variety of computers on which the software was used and the percent of users within engineering, management and general applications categories. Overall, 63.5% of the respondents use computers at some level in their organizations. All of the mines producing more than 454 kt/a (500,000 stpy) used computers. However, for those producing more than 9 kt/a (10,000 stpy) but less than 91 kt/a (100,000stpy), only 44% used computers. Generally, the software applications were still data-processing oriented. The application sophistication grew with increasing mine size. Computer system models and configurations for different sized organizations are recommended based on the configurations used in the industry at the time of the survey.

Jan 1, 1994

By R. C. Oberth, C. F. Lee, E. M. Taylor

INTRODUCTION Underground siting of nuclear power stations is drawing increasing attention in various parts of the world. Scandinavian countries took the early lead in this field because of their experience in the design and construction of underground hydroelectric stations and industrial plants, and because they have near-surface rock formations which are ideally suited for hosting large underground caverns. The world's first underground nuclear facilities were built in Norway (Halden) and Sweden (Agesta) and were commissioned in 1959 and 1963 respectively. Figure 1 summarizes the main features of these and two other small-scale European facilities. (1-4) American utilities and regulators are also for a variety of reasons assessing the benefits and penalties of underground siting. A recent study by Sandia Laboratories (contracted by the Nuclear Regulatory Commission (NRC) focussed on identifying potential safety benefits of underground siting. (5) Although the study concluded that underground plants would have improved containment for some accidents, as well as better external protection, NRC, in assessing the overall benefits and penalties, decided not to impose mandatory underground siting for nuclear stations. In June 1976, the California Legislature enacted a law which directed the California Energy Commission (CEC) to examine the issues concerned with underground siting of

Jan 1, 1979

By Richard E. Ray

INTRODUCTION Main mine fan installations at underground coal mines must be designed to comply with the requirements outlined in 30 CFR (Code of Federal Regulations) Part 75. However, very little emphasis is typically placed on the aerodynamic optimization of shaft collar designs, ductwork configurations, and the selection of a fan isolation, or "closing door," system. Field testing has shown that poorly designed systems may produce large pressure losses between the shaft and fan inlet, as well as air turbulence problems which adversely impact fan efficiency and sometimes fan structural integrity. This paper analyzes each component of a surface exhaust fan system for an underground coal mine: • The shaft collar arrangement, • The 45 or 90-degree turning duct that isolates the fan motor from the return airstream, • Alternative ductwork arrangements for parallel fan installations, • The self-closing doors or dampers that are required for multiple fans, and • Horizontal and vertical evas6 arrangements on the discharge side of the fan. While discussion is limited to axial fan installations at shaft mines, most of the recommendations would also apply to centrifugal fan installations and to main mine fans for drift mines. FEDERAL REGULATIONS The mandatory safety standards for underground coal mines that apply to the installation of main mine fans are listed in 30 CFR Part 75.310. Stipulations which impact the design of the fan sys- tem arrangement are contained in paragraphs (a)(l), (a)(5), (a)(6),(d), and (1) of 75.31 0: • Each main mine fan shall be installed on the surface in an incombustible housing; • Each main mine fan shall be protected by weak walls or explosion doors in direct line with possible explosive forces; • Explosion doors or weak walls shall have a cross-sectional area at least equal to the area of the return air shaft or drift opening through which the pressure from an underground explosion would be relieved; • Each main mine fan shall be offset by at least 4.57 m (15 feet) from the nearest side of the mine or shaft opening; • Automatic closing doors shall be provided to prevent possible air reversals through the fans in mines ventilated by multiple main mine fans. The installation of main mine fans underground is prohibited by 30 CFR Part 75.310, (a)(l). Providing explosion doors or weak walls in line with a possible underground explosion and offsetting the fan 4.57 m (1 5 feet) from the edge of the shaft preclude the installation of the fan directly over the shaft. In addition, 30 CFR Part 75.507-1 specifies that all electrical equipment used in return air courses be permissible, which requires locating the fan motor outside of the airstream exhausted through the fan. To comply with the Part 75.310 regulations, explosion doors are typically located directly over the shaft as part of the shaft cover or 'bonnet." A sufficiently long section of ductwork placed between the shaft enclosure and fan, equipped with a 45 or 90- degree turn, enables the fan to be offset at least 4.57 m (1 5 feet) from the shaft and the motor to be isolated from the airstream. The need for the turn in the ductwork can be eliminated by driving the fan from the discharge side, instead of from the inlet side, and providing for a 90-degree bend in the evas6. For multiple main mine fan systems, self-closing doors can be located on the inlet or discharge side of the fan. FAN SYSTEM COMPONENTS A poorly designed exhaust fan arrangement will produce turbulent conditions at the fan inlet and significant pressure losses between the shaft and fan. Field tests have shown that pressure losses through inlet ductwork at some installations may constitute as much as 30 percent of the total mine head. Unfavorable flow conditions may cause a change in the operating point on the fan performance curve, resulting in reduced fan efficiency and pres- sure generation capability. In some instances, poor airflow distribution through the fan may create mechanical stresses that lead to fan blade or fan housing fatigue failures. The objective in designing an air duct arrangement for a fan system is to provide a low cost duct that will move the air from the shaft to the fan in a uniform air distribution and with minimum energy requirements. The optimum solution is a compromise between technical and economic factors. Aerodynamic design considerations for the shaft collar and cover, fan inlet ductwork for both single and parallel fans, self-closing doors, and evas6 are discussed in the sections below. Shaft Collar/Cover To prevent excessive turbulence and non-uniform air distribution through the fan, a smooth transition for the change in direction of airflow at the top of the shaft must be provided. However, the concrete lining of the shaft is abruptly terminated at the surface at many coal mine installations (see Figure I), creating a sharp 90-degree bend. The airflow exiting the shaft becomes heavily concentrated in the upper portion of the horizontal fan in-

Jan 1, 1997

By A. S. Paschoa, A. W. Nóbrega

INTRODUCTION There are now over twenty years since the radiological characteristics of the brazilian regions of Araxá, Tapira and Barreiros, three locations adjacent to each other, in the state of Minas Gerais, Brazil, started being surveyed by investigators from the Instituto de Biofísica da Universidade Federal do Rio de Janeiro (IB/UFRJ), Pontifícia Universidade Católica do Rio de Janeiro (PUC/RJ), and New York University (NYU) (Roser and Cullen, 1958; Cullen et al, 1980). The importance of the Araxá apatite – Ca5,(P04)3(OH, F, Cl) - and pyrochlore - NaCaNB206F - for the production of large quantities of fertilizers and niobium was early recognized (Roser and Cullen, 1958). Interesting data have been gathered and published throughout the years on the contents of naturally occurring radionuclides in geologic materials, soils, grass, foods and waters of the Araxá region (Eisenbud, et al., 1964; Penna Franca, et al., 1965a, b; Roser et al., 1966; Penna Franca et al., 1970; Cullen, 1977; Penna Franca, 1977; Cullen and Paschoa, 1978; and Cullen et al., 1980). The radioactivity of the Araxá region is associated with mineral deposits of niobium rich pyrochlore and phosphate rich apatite. There are in this region mineral ores with 3 to 5% pyrochlore with 2 to 2.5% Th as Th02 and 50 to 150 ppm U308 in the matrix, while the apatite deposits contain up to 150 ppm U308 and a thorium concentration similar to that of the pyrochlore deposits (Paschoa and Palacios, 1981). As an indication of the high thorium content of the Araxá soils the 228Ra and 224Ra activity concentrations were reported to range from 10.6±0.2 to 62.4±0.7 pCi228Ra/g soil in 7 samples and 2.1±0.1 to 104±1 pCi224Ra/g soil in 19 samples (Cullen, et al., 1966). The uptake of radium isotopes by edible roots vegatables and fruits growing in the soils of the Araxá region can be illustrated by the data listed in Table I. The biological availability of natural radium isotopes in some segments of the Araxá soil allows a large variation in the 228Ra, 224Ra and 226Ra concentrations in vegetables and edible roots, as can be seen in Table I. This fact makes quite difficult a quantitative local assessment of the radiological implications of mining the Araxá mineral deposits of pyrochlore and apatite for production of niobium and phosphate fertilizers, respectively; since one cannot easily separate the naturally occurring from the technogically enhanced radionuclide contents of foods. The position of the city of Araxá inside the contour of the state of Minas Gerais appears in the upper part of Figure 1, which shows the outlined map of Brazil with the positions of the cities Brasilia and Rio de Janeiro also indicated. The lower part of Figure 1 is a representation of the Araxá region in an expanded scale, which indicates the locations of the pyrochlore and apatite deposits in relation to the city of Araxá, as well as the nearby hydrographic basins. The distance between the city of Araxá and the pyrochlore deposit is about 8 km, and between the pyrochlore and apatite deposits is 4 km. This paper deals tentatively with the radiological implications of the industrial operations taking place in the Araxá region for the exploration of the pyrochlore and apatite deposits. However, one must bear in mind, firstly, that the radiological implications of these industrial activities are by far too complex to be covered adequately by the limited amount of data to be presented in this paper, and secondly, that such implications cannot be considered of local character only. INDUSTRIAL OPERATIONS The commercial exploration of the Araxá deposits of pyrochlore and apatite started only few years ago, motivated by the increasing demand of niobium and phosphate fertilizers in Brazil and the world. As a consequence of the industrial operations in Araxá, a redistribution of the uranium, thorium, and radium originally present in the local deposits of pyrochlore and apatite started occurring in the seventies, with possible radiological implications for the Araxá region and its immediate surroundings, not to mention the destinations of the end products of such industrial operations. A literature review on the radioactivity associated with the extration industries of selected minerals was made by the USEPA (Bliss, 1978). The low level radioactive wastes of the industries for copper ore mining and rare metals processing have been object of particular attention (Fitzgerald, Jr., 1976; Eng, et al., 1979), but the short and long term implications of the radioactivity associated with the niobium industry were also subjects of concern (Knight and Makepeace, 1978). Recently, high 232Th and 226Ra concentrations in samples from the tin mining industry in West Malaysia were reported (Hu et al., 1981). A great deal of attention has been dedicated to the implications of the redistribution of radionuclides originally present in the mineral ores used by the phosphate fertilizer industry (Moore, 1967; Menzel, 1968; Spalding and Sackett, 1972; Eisenbud, 1973; Guimond and Windham, 1975; Guimond, 1976; Roessler,

Jan 1, 1981

By P. T. Bissert, T. J. Lutz, J. A. Yonkey, G. T. Homce

"Underground refuge alternatives (RAs) require an air source to supply breathable air to the occupants. This requires pressure relief valves (PRVs) to prevent unsafe pressures from building up within the RA. The Mine Safety and Health Administration (MSHA) mandates that PRVs prevent pressure from exceeding 1.25 kPa (0.18 psi or 5 in H2O), or as specified by the manufacturer, above mine atmospheric pressure when a fan or compressor is used for the air supply. Research to date by the National Institute for Occupational Safety and Health (NIOSH) suggests that the design and implementation of PRVs used in RAs has not yet had sufficient performance analysis or technical development. In response to this need, NIOSH tested a variety of PRVs using an instrumented test fixture consisting of data acquisition equipment, a centrifugal blower, ductwork, and various sensors to determine if subject PRVs meet the MSHA requirement. Relief pressures and flow characteristics including opening pressure and flow rate were measured for five different PRVs under a variety of conditions. Subject PRVs included two off-the-shelf modified check valves, two check valves used in MSHA-approved built-in-place (BIP) RAs, and a commercially available valve that was designed for a steel RA and is currently being used in some BIP RAs. The test results showed relief pressures ranging from 0.20 to 1.53 kPa (0.8 to 6.1 in H2O) and flow rates up to 19.3 m3/min (683 SCFM). INTRODUCTION The Mine Improvement and New Emergency Response Act of 2006 (MINER Act) was enacted in the wake of three mine explosions/fires that claimed 19 lives that year. Intended to help improve underground coal mine accident preparedness, the MINER Act includes provisions that target mine safety issues in areas such as emergency response planning, adoption of new technology, training and education, and mine safety standards enforcement [1]. Section 13 of the MINER Act specifically directed NIOSH to provide for research into the effectiveness and viability of refuge alternatives (RAs) for underground coal mines. This mandate culminated in the 2009 adoption of changes to 30 CFR mining health and safety regulations, requiring underground coal mines to provide mine emergency RAs and associated components, to provide a life-sustaining environment for persons trapped underground. Such RAs can be either self-contained mobile units or built-in-place (BIP) facilities. The regulatory changes also include provisions establishing requirements for Mine Safety and Health Administration (MSHA) approval of RAs and their components, and among these provisions are numerous criteria for providing a safe breathable atmosphere under positive pressure within the RAs. One specific criterion for maintaining a safe RA atmosphere requires the inclusion of an air pressure relief valve that will activate at a maximum of 1.25 kPa (0.18 psi or 5.0 in. H2O), or at a pressure above mine atmospheric pressure in the RA as specified by the manufacturer when the breathable air is supplied by a fan or compressor [2]."

Jan 1, 2017