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By R. A. Metz, William H. Breeding

The remarks that follow are based substantially on experience covering 45 years, 80% of which has been in placer work, rather than on a review of available literature. Most commercial placers have been deposited by the action of water. The richer and more difficult-to-mine placers are those in the headwater areas where gradients are steepest. The most lucrative placers are generally in intermediate areas where volumes are greater, fewer boulders are present, and gradients are from 3% to 1-1/2%. The higher volume, lower grade placers are in the lower reaches of river systems where gradients are lower. Where gold-bearing rivers have discharged into the sea, wave action can concentrate values on beaches, past and present. Most of the rich, readily accessible placers were mined by our forefathers. Current opportunities exist: (1) in remote areas where infrastructure has been absent in the past, or development has been prohibited by adverse ownership - political or commercial; (2) in deposits that could not be mined by equipment available to our forefathers; (3) in deposits unidentified by our forefathers; (4) where the-price-of-product/cost ratio is substantially better than in earlier years; or (5) a combination of those factors. When I entered the placer business in the late 1930s, and subsequently, a prevailing opinion believed that glacial deposits should be avoided as irregular in mineral content and composition, and unrewarding to explore and develop; yet an operator has been mining a fluvio-glacial deposit profitably for the past 17 years. Rich buried placer channels, often called paleo-channels were worked in the last century, generally by hand methods, and under conditions that would be unacceptable today. Exploration and mining equipment now available make some of these channels attractive targets. Well-known examples are in California and Australia. The formation of a commercial placer requires a source of valuable minerals. Above primary deposits, there may be eluvial deposits formed by the erosion of gangue minerals and the concentration "in situ" of valuable minerals. Down slope from these deposits are the hillside or colluvial deposits, and below them are the alluvial deposits of redeposited material. Most of the great placer fields of the world are the result of several generations of erosion and deposition. Well-known examples are in California and Colombia. Gold is a very resistant and malleable material, and gold placers may extend for 64 or 80 km (40 or 50 miles) along a river system. Platinum is less malleable, but is very resistant to disintegration. Diamonds are extremely hard, and (especially gem diamonds) may be found over great lengths of a river system. Cassiterite is less resistant to disintegration, and tin placers seldom extend over two miles without resupply from an additional source or sources of mineralizaton. Tungsten minerals are generally more friable, and within a few hundred yards of the source disintegrate to the point that they are uneconomical to recover. Rutile, ilmenite and zircon placers generally result from the weathering of massive deposits, and may be encountered over extensive areas; most are fine grained and durable. What does a geologist or mining engineer look for in placer exploration? The old adage to look for a mine near an existing mine is still valid. You need a source of valuable mineral. Then you require conditions for concentration, which means a satisfactory gradient and/or other conditions that will permit heavy minerals to settle. Nicely riffled gravel, often called a shingling of the bars, is conducive to placer formation. Coarser gravel is logically associated with coarser gold. Excessive clay and/or high stream velocities in narrow channels can carry gold far downstream and distribute it uncommercially over a large area. When material is extremely fine, in situ weathering and concentration become more important. Placers frequently occur distant from lode mines, and one must remember that in a larger watershed the exceptional floods that occur once in a hundred or a thousand years can move great quantities of material long distances. The carrying power of water is said to vary with the fifth or sixth power of its velocity. I am not ready to disagree with Waldemar Lindgren and accept that many commercial placers are substantially enriched by the chemical deposition of gold from solutions; however, I have seen crystalline gold in clayey material quite distant from known sources of primary gold that is dif-

Jan 1, 1992

By Roy M. Fleming

During the decade of the 1970's, a new emphasis was placed on assuring a safe and healthful workplace for all American workers. Much of the basis for this national effort was federal legislation: the Occupational Safety and Health Act of 1970 and the Federal Mine Safety and Health Act of 1977 (amended from the 1969 Coal Mine Act). One of the agencies involved in this protection effort is the National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control (CDC) in the Department of Health and Human Services (DHHS). In fulfilling its mandates under the 1970 and 1977 Acts, NIOSH conducts research, experiments, and demonstrations to support and stimulate advancements in health and safety practices. Priorities for NIOSH research are established primarily through congressional mandates, requests from the Department of Labor, needs as defined by NIOSH researchers, and surveillance information. Emphasis is placed on research in the areas of toxicology, industrial hygiene, physical and chemical sciences, physiology, ergonomics, engineering, psychology (behavior and motivation), and epidemiology (industry-wide studies). The framework of the current Institute program to identify, evaluate, and control occupational hazards includes activities in surveillance, research, evaluation, and training. These activities are planned and evaluated through a system that coordinates the efforts of eight research and scientific divisions. Each division develops projects to address program areas that have been identified by NIOSH management as having highest priority. In surveillance programs, the objectives are to identify substances and agents found in a representative sample of workplaces and to collect and evaluate information on rates of disease and injury in occupational groups. Information is also collected on occupational safety and health programs implemented by industry. Estimates of worker exposures and the potential for adverse health effects are considered in setting priorities for further investigations. A related activity, which also serves to provide technical assistance to industry, is NIOSH's Health Hazard Evaluation program. On-site investigations of workplaces are made in response to worker, employer, or government agency requests. Both industrial hygiene and medical examinations are conducted, and the results contribute to identifying new problems and evaluating their significance which may have public health implications beyond the particular worksites that are investigated. Field and laboratory research projects are performed to meet several objectives: - Characterize the working environment by evaluating current and past exposure levels for workers who are included in epidemiological or medical investigations. - Develop epidemiological information to define the association between the substance or agent under investigation and the acute and chronic health effects on workers. - Determine through animal studies the parameters of an association between exposure and effect. - Investigate the etiology of disease. - Develop sampling and analytical instruments and techniques and demonstrate their application for measuring toxic materials in the workplace. - Formulate sampling strategies that will accurately and precisely indicate exposure levels. - Develop medical procedures to prevent disease and to detect the presence of disease and early indicators of disease. - Assess the technology for control of exposures, including engineering and administrative techniques, personal protective equipment, and work practices. Presently, the research program is focused on reproductive effects, neurotoxic effects, injury/trauma, lung disorders, cutaneous disorders, cardiovascular disorders, cancer, stress-related disorders, effects of physical agents, digestive disorders, and renal and other organic disorders. In studying these issues, priorities are determined by the seriousness of possible adverse health effects resulting from occupational exposures, the feasibility of studying existing records or obtaining new data, and the size of the population which is potentially affected. Where there is low level of suspicion concerning adverse health effects or where an occupational disease occurs in a variety of industrial environments, investigations are limited to gross analyses of health effects such as review of mortality patterns. In such studies, the industrial populations selected are those for which existing data resources can be utilized. Such data consists of records of occupational exposures or health status which have been maintained by the employer, the union, or Government agencies. Where a review of the available information suggests that serious health hazards exist and the existing data resources are inadequate for quantifying the relationship between the specific biological response and type and degree of exposure, prospective studies are initiated. Information derived from such research is essential for the development of sound criteria for control of industrial exposures to noxious agents. Other input to the criteria documentation process comes from searching and evaluating the literature. Criteria documents contain the recommendation of an environmental limit where information is available to support it, as well as the recommendation of work practice controls, medical evaluation, information for workers to recognize and avoid the hazard, and identification of specific research gaps. In some cases, during the criteria document preparation, gaps in knowledge are found which necessitate further research before an occupational standard can be recommended.

Jan 1, 1981

By John S. Livermore

I feel very privileged to be added to the distinguished group that has received this award since the first recipient, Reno Sales, received it in 1954. If my research is correct, the last geologist to be honored was Bill Callahan in 1982. Perhaps the Awards Committee decided it was about time to select a geologist, and I became the beneficiary. Regarding the discovery of the Carlin ore body, it was the culmination of several studies - one going back as far as 1939 when a US Bureau of Mines engineer named W.O. Vanderberg recognized an unusual type of gold mineralization in sediments in northern Nevada. What was unusual was the fact that the gold was so fine that it would not concentrate in a pan. This, plus the study of the Roberts Mountain thrust by Ralph Roberts (1960) and conversations with Harry Bishop, manager of the Gold Acres Mine, pointed Alan Coope and me in the direction of the Lynn Window and, eventually, the Carlin discovery. There has been a great deal written about this discovery. I thought it would be interesting to discuss the evolution of Carlin gold exploration in Nevada since this time and to discuss the changes in perception of this unique type of mineralization. The method used by Coope and me in following up on Roberts' work was to map geologically the Roberts Mountain thrust and conduct geochemical sampling of favorable outcrops and float. Coope was highly experienced in geochemical exploration, as he had graduated from the Royal School of Mines in London, studying under John S. Webb, one of the pioneers of geochemistry as applied to mineral exploration. We first considered using pathfinder elements, but finally concentrated on gold analyses alone, even though the sensitivity of fire assays used at that time was only about one-half part per million. According to the spatial relationship of the mineralization to the Roberts Mountain thrust, as pointed out by Roberts (1960), we were looking for mineralization within the thrust itself. Our models were the known Gold Acres and Getchell mines, which contained reserves on the order of 0.9 to 1.8 mt (1 to 2 million st). These were not of substantial size, but I had hoped we might find more than one of these tributary to a mill that would justify an operation for our employer, Newmont Mining Corp. What we ended up with was the type of deposit we were looking for - an open pit deposit of micron gold, which the old timers had missed because the gold was not capable of being panned. But never in our wildest dreams did we think there was a chance of finding a body containing 10 mt (11 million st) of ore at 0.30 oz/st (10.3 g/t).The deposit was not in the thrust proper but was found in a favorable horizon of Roberts Mountain siltstone that was below the thrust. This is the first example of how a model should not be followed blindly. Newmont was successful in keeping this discovery quiet for some time. After a considerable amount of drilling, a rumor circulated that they had discovered a large low-grade ore body of around 1.7 to 2.1 g/t (0.05 to 0.06 oz/st), which of course would not have been economic with gold at $1.13/g ($35/oz), which was the fixed price at that time. The company, for obvious reasons, did not discourage the rumor. When, however, the true results came out there was a lot of feverish activity. Because of this new type of so-called "invisible gold," which could have been missed by the old timers, the thought was that other deposits would be discovered very soon. The Carlin and other smaller deposits, including Bootstrap, Blue Star and Gold Quarry, were in windows where the lower plate of the Roberts Mountain formation (below the thrust) had been exposed by erosion. This then became the new

Jan 1, 1997

By S. Hartman

The Escalante Silver Mine in Southwest Utah produces an average of 71.000 kg (2.3 million troy ounces) of silver dore annually. Precipitates from a cyanide leach circuit are treated by either acid leaching prior to fusion or a direct fusion with nitre. Process development, plant experience, and a comparison of both methods will be discussed. Plant experience from the custom treatment of a gold/silver precipitate containing matte producing elements will also be covered.

Jan 1, 1989

By Igor V. Nazarov

INTRODUCTION Tens of deposits in' coal basins of Western and Eastern Siberia are being open-mined with the technology of overburden rehandling into the mined out space of pits by excavators - draglines. This technology is preferred due to the high productive Russian equipment, comparatively low cost, and relatively small Influence exerted on the environment. The basic tendency of the last decades is the aspiration for enlarging the sphere of the' technology application for development of gentle and steeply dipping seams with the use of blast destruction of overburden and with combined winning of loose alluviums and rock partings. Complex technological schemes with multiple rehandling are widely used. In addition to it, stripping workings, intermediate storage of mineral resources, placing of transport dumps, and engineering construction can be realized with the use of draglines. More than ten of dragline faces are simultaneously exploited in some pits, and the rehandling coefficient ranks from 0.1 to 8. Here, conditions of winning and placing (position of a face and existing dump) are varying in space and time; this leads to the necessity of reconsidering the order for conduction of works (schemes) within the current designing. By now, in order to this, it is required to realize complex engineering calculations by graph-analytical methods and definite experience. The need is available for automatization of this process by creation of the corresponding software. The software is to: • Orient on the active pits and use information on the existing geology, equipment, and situation in mine. • Calculate the existing schemes more operative and on a higher qualitative level to model their development in a pit space with parameter optimization. • Predict situations demanding to change the existing technology for mining operations and recommend optimal technological schemes. METHODOLOGICAL FOUNDATIONS FOR MODELING The problem is not new, it has more than fifty year-old history of creating mathematical models algorithms, and programs in Russia, Ukraine, USA, Canada. Australia and other countries with the developed mining branch. Conventionally, all population of programs can be divided into three groups depending on goal and interval of prediction: • Long-term programs used in designing and intended for substantiation of the nine capacity, selection of mining system, establishment of limits for applying the technology of overburden rehandling. Mid-term programs used in current planning for calculation of technological schemes and certificates of face in active mines.INTRODUCTION Tens of deposits in' coal basins of Western and Eastern Siberia are being open-mined with the technology of overburden rehandling into the mined out space of pits by excavators - draglines. This technology is preferred due to the high productive Russian equipment, comparatively low cost, and relatively small Influence exerted on the environment. The basic tendency of the last decades is the aspiration for enlarging the sphere of the' technology application for development of gentle and steeply dipping seams with the use of blast destruction of overburden and with combined winning of loose alluviums and rock partings. Complex technological schemes with multiple rehandling are widely used. In addition to it, stripping workings, intermediate storage of mineral resources, placing of transport dumps, and engineering construction can be realized with the use of draglines. More than ten of dragline faces are simultaneously exploited in some pits, and the rehandling coefficient ranks from 0.1 to 8. Here, conditions of winning and placing (position of a face and existing dump) are varying in space and time; this leads to the necessity of reconsidering the order for conduction of works (schemes) within the current designing. By now, in order to this, it is required to realize complex engineering calculations by graph-analytical methods and definite experience. The need is available for automatization of this process by creation of the corresponding software. The software is to: • Orient on the active pits and use information on the existing geology, equipment, and situation in mine. • Calculate the existing schemes more operative and on a higher qualitative level to model their development in a pit space with parameter optimization. • Predict situations demanding to change the existing technology for mining operations and recommend optimal technological schemes. METHODOLOGICAL FOUNDATIONS FOR MODELING The problem is not new, it has more than fifty year-old history of creating mathematical models algorithms, and programs in Russia, Ukraine, USA, Canada. Australia and other countries with the developed mining branch. Conventionally, all population of programs can be divided into three groups depending on goal and interval of prediction: • Long-term programs used in designing and intended for substantiation of the nine capacity, selection of mining system, establishment of limits for applying the technology of overburden rehandling. • Mid-term programs used in current planning for calculation of technological schemes and certificates of face in active mines.

Jan 1, 2002

By Haydn H. Murray, Fred G. Heivilin

The "Hormite Group" was proposed for palygorskite (attapulgite) and sepiolite for their complex magnesium silicate composition and elongate crystals (Martin-Vivaldi and Robertson, 1971). These minerals occur in close association with each other and more complex structural variations may exist (Bailey, 1972). In 1862 Savchenkov used the name palygorskite to describe a mineral from the Palygorsk locality (Hay, 1975), near the Ural Mountains. Ovecharenko and Kukovsky (1984) mention that when mountain leather deposits were prospected in the Palygorsk Division mine it was assumed this unusual mineral was a variety of asbestos. Early mineralogists used the terms "mountain cork" or "mountain leather" when referring to palygorskite. Robertson (1986) mentions that it appears palygorskite was known since Theophrastus&apos; time, ca. 314 BC. J. de Lapparent used "attapulgite" for clays from Attapulgus, GA, and Mormoiron, France, because he thought them different from palygorskite, but the two types were proved to be the same (Bailey et al., 1971). The name attapulgite is still used for the Florida and Georgia deposits when the crystal length to diameter ratio does not exceed 10:1(Merkl, 1989). Georgia palygorskite clays are of much shorter length compared to classic palygorskite. In 1847 Glocker first used the name sepiolite which was called "Meerschaum" by Werner (1788) and Hauy (1801) namedit "Ecume de Mer." Brochant (1802) described low density and white magnesium silicates adding the name Talcum Plasticum and Ecume de Mer. In the Meigs-Attapulgus-Quincy district palygorskite (attapulgite) commonly occurs in two distinct forms referred to as short length palygorskite (Meigs Member) and long length palygorskite (Dogtown Member) (Merkl, 1989). Long length palygorskite crystals (> 10 pm) are rarely observed in the Meigs and Dogtown Members, but when present are in association with dolomite crystals. The short length form is usually less than 2 pm in length and has a low magnesium content whereas the long length form has a high magnesium content and a length greater than 2 pm. The distinctions in morphology are not only important because of the relationship to the origin of the deposits, but also in relation to activity in causing membranolytic activity related to data on palygorskite samples from 9 locations ranging from relatively inert to active in work reported by Nolan et al. (1989). The > 10 pm lengths amounted to only 51 of 17,401 fibers sized. The shortest lengths (< 0.5 pm) were relatively inert. This study pointed out that surface activity, morphology, and chemical differences may be distinctly different within the definition of palygorskite, or for that matter for any individual mineral so that health and other properties must be measured because the name alone does not necessarily indicate uniformity. Palygorskite (attapulgite) fuller&apos;s earth was first sold for drilling mud in 1941. The market for this use expanded slowly and has maintained a level of 7 to 10% of the total US production during the last few years. Most of the fuller&apos;s earth sold for drilling mud comes from the southern part of the Meigs-Attapulgus-Quincy district of Georgia and Florida. Palygorskite clays produced in this area are superior to most other fuller&apos;s earth for mud used in drilling salt formations, but because of high water loss, they are inferior to bentonite where the rocks drilled contain no saltwater. According to Oulton (1965), more than 90 different grades of fuller&apos;s earth are produced. Some of these grades are used for pharmaceuticals designed to absorb toxins, bacteria, and alkaloids; for treatment of dysentery; for purifying water and dry cleaning fluids, dry cleaning powders and granules; for the manufacture of NCR (no carbon required) multiple copy paper; for the manufacture of wallpaper; and as extenders or fillers for plastic, paint, and putty. Fuller&apos;s earth mined near Ellenton, FL, was used for making lightweight aggregates for the construction of concrete barges during World War I1 (Calver, 1957). Still other uses of fuller&apos;s earth and its suitability for uses in new products are outlined by Haden, Jr., and Schwint (1967), Haden, Jr., (1972), and Haas (1970). One special use of fuller&apos;s earth is as a carrier of platinum catalysts that are made in the United Kingdom from sepiolite clays mined in Spain. Other uses of sepiolite fuller&apos;s earth (Chambers, 1959) are similar to those of the palygorskite (attapulgite) type mined in the United States.

Jan 1, 1994

By W. E. L. Minter

Discussion by R.W. Hutchinson Minter&apos;s excellent recent paper (1990) on the great paleoplacer gold deposits of the Witwatersrand and its subsequent discussion (Cheney, 1991) and reply (Minter, 1991) provide an informative, interesting and up-to-date review of the geology of these unique ores and some long enigmatic questions regarding their origin. Clearly summarized by Minter (1990) are the compelling sedimentologic and stratigraphic relationships indicating that the Central Rand Group conglomerates are ancient placers and documenting the fluvio-deltaic conditions of their transport and deposition. As Minter (1991) indicates, Cheney&apos;s discussion broadens Minter&apos;s 1990 coverage of the subject by considering higher and lower stratigraphic units and by adding detailed comments concerning recently published information about metamorphic and age relationships. Cheney&apos;s discussion and Minter&apos;s reply also readdress the old controversy of epigenetic hydrothermal vs. syndepositional placer origin for these deposits. This controversy has been resurrected by: • recent recognition of hydrothermally-altered granites (HAGS) in the older Archean basement rocks that lie unconformably beneath the Dominion Group rocks north and west of the Witwatersrand depository; • recognition of greenschist metamorphic assemblages in the Witwatersrand strata; and • the presence of interpreted epigenetic mineral assemblages and textures in some of the deposits. These relationships are briefly discussed by Cheney who suggests they may result from later, superimposed metamorphism and deformation and do not prove that the gold was introduced by epigenetic/metamorphogenic processes. In his paper, Minter (1990) cited the 1986 abstract of a subsequently published paper by Hutchinson and Viljoen (1988) who also considered many of these aspects and attempted to integrate them all in abroad genetic hypothesis. In addition, they emphasized the additional important problem of determining the source for the Witwatersrand gold. Although this issue was partially addressed by Reimer (1984), Mossman and Dyer (1985) and Reimer and Mossman (1990), the question has been generally under emphasized in earlier work and was, therefore, not stressed by Minter and Cheney. Reimer (1985) also emphasized the importance of weathering of the basin&apos;s Archean hinterland and its affects on Witwatersrand sedimentation. Since the epigenetic hydrothermal hypothesis was essentially discarded in favor of placerist origin, the gold source for these great deposits has generally been attributed to the weathering of lodes in greenstones or granites of the uplifted, older Archean hinterland to the north and west. However, Hutchinson & Viljoen (1988) present evidence that this explanation is inadequate, as well as data in support of an alternative explanation. They suggest that the gold and accompanying abundant, clearly detrital and auriferous pyrite in the conglomerate reefs were derived by erosional degradation of auriferous-pyritic exhalite previously deposited, by shallow marine discharge of hydrothermal fluids, along the fault-bound northwestern margins of the Witwatersrand depository. The auriferous-pyritic exhalites were generated by fluid-rock reactions in the subsurface, particularly in the highly-altered lavas of the Dominion Group but also in adjacent basement granitic rocks. The process envisaged is comparable to that observed in sea floor hydrothermal systems today, although, in this case, it occurred at the margin of a rapidly subsiding, shallow marine or continental basin. Important evidence for this explanation is the anomalous gold content of the ferruginous, shaley strata occurring throughout the Witwatersrand Supergroup and including the distinctive contorted bed that is an iron formation. These layers have been interpreted (Hutchinson and Viljoen, 1988 and 1990) to represent the more distal, finer-grained, mixed chemical/clastic sedimentary strata. Thus, they are the basinal equivalents of the proximal, auriferous-pyritic exhalites that were deposited along the basin&apos;s margin and subsequently reworked by sedimentary processes. This gold source explanation resolves many of the enigmatic questions regarding Witwatersrand geology and the reawakened controversy between proponents of hydrothermal and placerist genetic hypotheses. The theory invokes a hydrothermal origin for the gold in the basin-margin pyritic exhalites, thus explaining the visible hydrothermal characteristics (Figs. 1 and 2). It also provides compelling evidence for placer origin by encompassing all of the fluvio-deltaic processes of clastic sedimentary transport and deposition that are clearly summarized by Minter. These characteristics result from the degradational reworking of the pyritic exhalites along the depository&apos;s margins. Fluvial reworking, transport and deltaic redeposition of this detritus, along with additional detritus carried into the depository from the hinterland, then formed the conglomerate reefs. Other enigmatic aspects of Witwatersrand geology include: • the rarity of magnetite and ilmenite (the two most common heavy minerals in placer deposits) and the contrary abundance of leucoxene in the conglomerate reefs; • the presence of differing varieties of pyrite (authigenic, allogenic, compact and porous) all of which are auriferous; and • the presence of well-rounded pebbles, even cobbles, of pyrite that, in view of the brittleness of the mineral, could not have been transported great distances from a hinterland.

Jan 1, 1993

By Wade E. Cooper

INTRODUCTION How accurate are past and present employee radondaughter exposure records of underground uranium miners employed in the United States? This often-debated question is essential for future substantiation of safe exposure limits. An apparent discrepancy between company-reported exposures and Mining Enforcement and Safety Administration (MESA) projected exposures was detected in 1977. For these reasons a need for an updated comparison of these exposure data was indicated. This paper gives some of the conclusions of the earlier study and compares more recent exposure records compiled by the Atomic Industrial Forum, Inc., with projected exposures based on sampling by Federal mine inspectors. EARLIER STUDY In its 1977 Annual Report (U.S. Department of the Interior, 1978), MSHA&apos;s predecessor, the Mining Enforcement and Safety Administration (MESA), reported that there was "an apparent discrepancy between Federal inspection results and company records." Both company records and MESA&apos;s projections from samples taken during routine Federal inspections indicated reductions in the average exposure of underground uranium miners from 1975 to 1977, but the MESA projections were over 4 times higher than the company-reported averages. This apparent discrepancy however, was based on a comparison of exposure data reported for all U.S. underground uranium miners. This projection more closely represented the average exposure of U.S. underground uranium mine production workers who worked 1,500 hours or more during the year. Exposures of such workers are reported each year by the Atomic Industrial Forum, Inc. (AIF) in summaries of exposure data reported to the AIF by uranium mining companies throughout the United States. (The AIF exposure summary for 1979 appears as tables A-1 and A-2 in the appendix of this paper.) Assuming that the average exposure for each exposure range category is the midpoint of each exposure range category, table 1 compares the estimated average exposures for U.S. underground uranium mine production workers who worked underground 1,500 hours or more each year in 1975 through 1977 with the exposures projected by MESA for those years. [Table 1. - Average Exposure and Projected Average Exposure for U.S. Underground Mine Production Workers Who Worked Underground 1,500 Hours or More During the Year. Company, MESA?&apos; Reported- Projected Year (WLM) (WLM) 1975 1.59 5.68 1976 1.84 4.64 1977 1.68 4.08 1 Atomic Industrial Forum, 1976, 1977, 1978. 2 U.S. Dept. of the Interior, 1978.] Table 1 indicates that, even after adjustment to ensure better comparability an apparent discrepancy between Federal inspection results and company reported exposures for 1975-1977 exists; however, the apparent discrepancy diminished over the 3 years. Slade, 1977, explained some of the discrepancy between company records and MESA projections of miners&apos; average radon-daughter exposures as follows: 1) Concentrations of radon daughters in some work areas can vary greatly during any one day. A variation from 0.3 WL to 17.0 WL has been measured in the same stope on the same day. 2) Seemingly simple abatement problems indicated by the regular Federal and State inspections were solved simply by manipulating the mine ventilation. 3) The methods used by mine operators to compute cumulative exposures were such that high radiation readings were seldom or never reflected in the records. For example, a work area sampled on Monday indicated a radon-daughter level equal to 0.2 WL and this was recorded. It was sampled again on Wednesday of the following week and the level was 2.2 WL. The miners were withdrawn or told to fix the ventilation, and when this was accomplished the area was sampled and found to be at 0.2 WL again. Although the miners could have been working in the higher concentration up to 6 days, this reading might never be reflected in their records. If it was recorded, only a fraction of the day on which it was discovered would be entered into the cumulative exposure calculation (time-weighted average). 4) Some of the mines visited used a mine average radiation concentration, and every employee working underground was given the same exposure per unit of time spent underground. As a result of the 1977 study, more stringent sampling and recordkeeping standards were proposed and public hearings held in 1977. The resulting new and revised health standards on radon-daughter sampling and exposure recordkeeping became effective August 30, 1979 (Mine Safety and Health Administration, 1979). Prior to these new regulations, radondaughter sampling requirements were on an "as often as necessary" basis (Code of Federal Regulations, 1978). The new regulations required practically all active work areas in underground mines to be sampled at least once every 2 weeks, with many areas requiring weekly sampling. They also required calendar-year exposure records of all underground

Jan 1, 1981

By Martha E. Smith

INTRODUCTION Radiation is one of the many agents occurring in our environment that is capable of causing cancers. We are all unavoidably exposed to natural background radiation. If we wish to exploit the beneficial uses of radiation in medicine, industry, and for the production of electricity, some further exposures to radiation are almost inevitable. One needs to ensure therefore, that the standards of radiation protection are safely derived and one would want to understand the mechanism by which radiation might cause cancer and genetic defects. In order to study the effects of radiation one can: (1) analyze human data, (2) perform animal experiments, and (3) do molecular level experiments. Indeed all three kinds of information are needed. This paper will concentrate on the steps required to obtain some of the necessary human data regarding health effects, where the concern is about the impact and consequences of long-term low-level exposures to an agent. Such investigations require some knowledge of work histories, dose histories, health "outcomes", and the personal identification of the individual involved. Three inter-related computer systems have been developed at Statistics Canada which have been designed to permit optimal use of a number of different records for our entire country for such health related research. The development of the Canadian Mortality Data Base, the initiation of the National Cancer Incidence Reporting System, and the development of new computer linkage techniques have helped reduce the cost and increase the scale and efficiency of automated follow-up to produce statistics of sickness or death associated with radiation and other carcinogenic agents in mines. These computer systems have already been implemented, and references will be made to studies currently being conducted using these files and facilities (e.g. a study of all Ontario miners, plus various Canadian uranium, fluorospar, salt and nickel miners). We will also look at the kinds of data that need to be collected now, to improve such studies in the future. DELAYED RISKS - THE STUDY SIZE AND COST Delayed effects on human health, as for example industrially caused cancer, can in general only be detected and measured by following-up the individuals to see what eventually becomes of them. What is not generally recognized is that the relatively low levels of individual risk, about which the public is often concerned, usually requires for their detection that very large numbers of "exposed" and "control" individuals (e.g. 10,000 to 100,000 or more) be followed over a period of two or three decades to determine when they die, what they die of, and whether they contracted cancer or some other disease of special concern. Thus, it is frequently exceedingly difficult to make such investigations cost-effective so that they will be undertaken at all, and as a result very real risks to health can remain undetected or unquantified. THE MANUAL PROCEDURES Follow-up of individuals by epidemiologists has until recently been a largely manual and clerical operation. It has used a diversity of source record files; local, regional, and national. Often the tracing of people has involved letters sent through the mails and visits to institutions, physicians, municipal offices, and former neighbours. Only thus could one find out whether the individuals were dead or alive. Such studies were necessarily small, or else very expensive. Death registrations have, by tradition, provided a valuable tool for the identification of harmful influences in the environment. However, with the increasing mobility in the population, death may often occur far away from the place of exposure to such an influence. Thus, no longer will simple manual searches in a single registry office suffice to inform the investigator concerning the deaths that may have occurred in a study population, especially when that population is large. In the past, manual follow-up to locate the relevant death registration normally required some prior knowledge of the province and year of death in question, so that the alphabetic indexes could he used to direct researchers to the appropriate bound volumes of registration forms. To search manually in this fashion for any large number of death registrations, without knowing in which year or province the deaths had taken place, or even whether they had yet occurred, would be impractical, since each year in Canada there are about 170,000 deaths. DEATH AND CANCER AS SPECIAL ENDPOINTS Much of recent effort has been focused on the organization of the "endpoint" files required to do long-term follow-up studies on a national scale, because that is a function which other institutions are unable to perform due to the confidentiality laws governing the use of such information. Outside organizations generally come to us with detailed "starting" point records which relate to some specific group requiring study. We carry out these epidemiological searches on a cost-recovery basis. The analytical interpretation of results is normally

Jan 1, 1981

By Jon A. Hummer, Aleksandar D. Bugarski, Shawn Vanderslice, Teresa Barone

A study was conducted to examine the potential of diesel emissions control strategies based on retrofitting existing power packages with exhaust aftertreatment devices and repowering with advanced power packages. The retrofit systems, a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF), were evaluated individually using a US EPA tier 2 (ter 2) engine operated under four steady-state conditions and one transient cycle. The DOC effectively curtailed emissions of CO, and to some extent organic carbon (OC), elemental carbon (EC), and aerosol number concentration. The DPF system offered substantially higher reductions in OC and EC mass and aerosol number concentrations. Both, the DOC and DPF achieved reductions in the aforementioned emissions without adversely affecting emissions of NO2 and nano-sized aerosols. The strategy of repowering with an advanced system was examined using a US EPA tier 4 final (tier 4f) engine equipped with a cooled exhaust gas recirculation system and diesel exhaust fluid-based selective catalytic reduction system, but not with a DPF system. The tier 4f engine contributed substantially less than the tier 2 engine to the EC and OC mass, aerosol number, and CO, NO, and NO2 concentrations. The tier 4f engine was very effective in reducing aerosol mass, NO, and NO2 concentrations, but it was not equally effective in reducing aerosol number concentrations. The implementation of viable exhaust after treatment systems and advanced diesel power packages could be instrumental to the underground mining industry to secure a clean, economical, and dependable source of power for mobile equipment.

By Gregory M. Rumbaugh, Christopher Mark

"The proliferation of unconventional gas well development in the Northern Appalachian coalfields has raised a number of mine safety concerns. Unconventional wells, which extract gas from deep shale formations, are characterized by gas volumes and pressures that are significantly higher than those observed at many conventional wells. The gas is composed largely of methane as well as other hydrocarbons. Hundreds of planned and actively producing wells penetrate protective coal pillars or barriers within active mine boundaries, including chain pillars located between longwall panels. Gas released from a well damaged by mining-induced ground movements could pose a risk to miners by flowing into the mine atmosphere. The mining-induced ground movements that may cause well damage include conventional subsidence, non-conventional subsidence (e.g., bedding plane slip), pillar failure, and floor instability. This paper describes the known risk factors for each of the four failure mechanisms. It includes a framework that can guide the risk assessment process when mining takes place near gas or oil wells.INTRODUCTIONSouthwestern Pennsylvania has served for centuries as a producer of coal, oil, and natural gas. Coal mines were first developed in the Pittsburgh Coal Seam in the 1760s, with the first recorded mine in 1761 being the Fort Pitt Mine (Edmunds, 2002). Natural gas was introduced to the region when the Haymaker Well in Murrysville, Pennsylvania experienced a blowout on November 3, 1878. Although it was originally drilled prospecting for oil, it produced an estimated 30 million cubic feet per day of natural gas. Without well controls or pipeline infrastructure in place, it burst into flames and lit the night sky for over a year. Soon after, the Penn Fuel Company continued development of the Murrysville gas field and is credited with making Pittsburgh, Pennsylvania the first major city in the U.S. to have natural gas supplied for home and industrial uses. “Natural gas is king in Pittsburgh,” proclaimed an October 18, 1885, article in the New York Times headlined “Value of Natural Gas, Its Use Clarifies the Atmosphere at Pittsburgh” (AOGHS, 2018). By the early 1900s, coal, oil, and natural gas production had reached the southern extents of Pennsylvania in Greene County. The county had first produced oil in 1886, and shortly after began producing natural gas in 1890. By 1906, over 1,300 wells had been drilled (Stone and Clapp, 1906)."

Jan 1, 2019

By Arnolfo A. Valdivia

Prior to 1971, there were several clinical trials to evaluate programs for early detection of lung cancer. Among these, the Philadelphia Pulmonary Neoplasm Research Project,(3) the Veterans Administration Study published by Lilienfeld,(7) and the controlled trial of the Kaiser Foundation Health Plan showed an overall five year survival rate of 8% for newly detected cases (the same as the national statistic for unscreened patients). In 1971, the National Cancer Institute initiated three randomized, controlled mortality studies using lung cancer screening of persons at high risk (male smokers over 45 years old). The studies are being conducted at the Johns Hopkins University Hospital, the Mayo Clinic, and the Memorial Sloan-Kettering Cancer Center. The studies have slightly different designs in the combination of sputum cytology and chest x-rays. At the Mayo Clinic the study group is offered screening with sputum cytology and chest x-rays every four months, whereas the control group is advised to have an x-ray and cytology every year. No reminders are sent, and it is believed that only about 20% of the control group is screened. At Johns Hopkins and Memorial, both experimental and control groups are offered annual chest x-rays. The experimental group is additionally offered sputum cytology every four months.(5) At present all of the programs show that screening can detect cancers that are undetectible by other means. However, at this time mortality rates in the control and experimental groups are not significantly different in any of the three studies. OUR PROGRAM Our clinic is located in Grants, New Mexico and we provide most of the pre-employment physical examinations for the mines operating in the Grants area (Kerr McGee Nuclear, Homestake Mining, United Nuclear, Western Nuclear, and Ranchers). In the examinations, we obtain the previous mining history of the worker, a chest x-ray, a sample of sputum for cytological examination, and a blood sample. We also provide routine annual physical examinations of the workers, with special interest in the detection of bronchogenic carcinoma. In the early seventies, we did not have a definite surveillance program. We did not know whether we should have a program like the one started at Memorial or like the one started at the Mayo Clinic. After long consideration, we decided to have a program that does not demand a sputum cytology and chest x-ray every four months, but that allows as many chest x-rays and sputum cytologies as needed to diagnose lung cancer as early as possible. We believe that, if a screening method for cancer is to be optimally effective, it must detect the process at stages early enough for curative therapy. We order a test depending on the age of the miner, the race, the mining history, the smoking history, the radiation exposure levels, and the results of the previous chest x-ray and sputum cytology. With the help of the computer, we have a list of all the miners who should be watched closely because of age, race, mining history, smoking history, radiation exposure, etc. Examination of the miners is performed at our clinic, where all the records are kept. The sputum is collected there but examined in Grand Junction, Colorado, by Dr. Geno Saccomanno. There are two ways to collect sputum. The best way is to collect three consecutive morning samples. For this, we need the cooperation of the miners. They have to follow these instructions and mail the bottle containing the sample to Grand Junction. "Instructions for obtaining a good cough specimen" The enclosed plastic bottle contains a preservative solution, so do not empty out the liquid in it. When you go to bed, place the plastic bottle at your bedside where it will be handy in the morning. When you first get up in the morning (before breakfast) try to cough up some "phlegm" from deep in your chest, and spit it into the liquid in the bottle. Try coughing several times. If you have difficulty coughing, try inhaling deeply the steam from a teakettle (or home-type inhalator). Keep the amount of saliva (ordinary spit) that you put into the bottle along with the cough specimen as small as possible. Do not collect the "phlegm" or mucous that comes from the back of your nose. Put the cap back on the bottle, and shake it vigorously for two minutes. If the amount of material you have coughed up is quite small, then keep the bottle at your bedside for three or four days, and each morning try to add another cough specimen. After obtaining your cough specimen, repack the bottle in the mailing container, and attach the enclosed mailing label. It does not require any postage stamps. Unfortunately, some miners "forget" to mail the sample and end up with an incomplete physical examination. To avoid this some companies, like Homestake, request that we obtain the sample in our clinic by forcing cough and expectorant with a nebulizer machine. This method does not give as good a sputum sample as the previous one, but we do get a sputum sample for every miner. The policies of different companies, in regard to annual physical examinations are different. All

Jan 1, 1981

By Scott D. Thayer, George H. Milly

INTRODUCTION Ambient concentrations of radon and its daughter products have been measured and analyzed by a number of investigators for a variety of purposes. Principal among these purposes have been: (1) descriptive, to characterize the distribution and changes in concentrations under various conditions; (2) research in the use of radon as a tracer gas in the study of atmospheric characteristics and motions, such as eddy mass transfer, diffusivity profiles, large scale circulations, and the like; and (3) the use of radon as an atmospheric tracer in exploration for uranium deposits.* This information forms the basic data for this paper and for its placing the ambient natural, or non-anthropogenic, radon concentrations into the perspective of ambient radon health standards and lung cancer risk calculations. To enable better understanding of some aspects of the ambient radon data, review and analysis is also performed on selected measurements of radon emanation or flux from the surface of the earth into the atmosphere. These measurements have generally been made for purposes similar to those for ambient radon, i.e., (1) description of radon emanation characteristics; or (2) to support and justify the use of ambient concentration measurements in atmospheric research; or (3) in exploration for uranium. Interest is also developing in the use of such measurements for earthquake prediction. In addition, to complete the perspective, brief examination is given to anthropogenic ambient and flux radon measurements related to the mining and milling of uranium, so that comparison can he made with the values from natural sources. As a frame of reference we cite here previous summaries of studies which have presented representative values and ranges of ambient concentrations and emanation rates. H. Israel, in the Compendium of Meterorology (1951), cites eight studies of ambient radon concentrations which we have selected as representative of non-anomalous continental values. Their means generally range from [0.06 to 0.15 pCi lit-1 with the smallest reported minimum of zero and the largest maximum 0.53 pCi lit-1. The overall mean is 0.10 with a standard deviation of 0.03 pCi lit-1. Means over oceans are much smaller, and the data scarcer, with only three values ranging from 0.0004 to 0.003 pCi lit-1 and a mean of 0.0016 pCi lit-1.] Thirteen studies from Israel&apos;s list were selected as representative of mountainous terrain. These data, except for the cases of higher elevations, frequently show significantly higher values than the average cases in non-mountainous terrain described-above. The averages range from 0.10 to 0.59 pCi lit-l; the smallest minimum is zero and the largest maximum is 9.2 pCi lit-1. The overall mean is 0.30 with a standard deviation of 0.17 pCi lit-1. Israel also cites five studies of radon emanation (flux) from the earth&apos;s surface. These show a mean of 0.40 pCi-2m-2 sec-1 and a range of from 0.21 to 0.74 pCi m-2 sec-1. Data on flux are naturally scarcer in the literature than data on ambient concentrations, because of the greater interest in and utility of the ambient information. In this paper we also give special consideration to observations of the variability in time and space of radon flux rates, and to the impact of these phenomena on the use of such data for a variety of purposes. NATURAL(NON-ANTHROPOGENIC)AMBIENT RADON CONCENTRATIONS We have examined the following reports for the data selected for this category; these studies were generally intended to describe radon characteristics in the atmosphere. Jonassen and Wilkening (1970); Bradley and Pearson (1970); Wilkening (1970); Lambert, et al (1970); Pearson and Moses (1966); and DickPeddie, et al (1974). Another set of studies which was reviewed was selected because the investigators made ambient radon measurements in the course of examining the use of radon as a tracer in atmospheric research. This set consists of: Israel and Horbert (1970); Carlson and Prospero (1972); Subramanian, et al (1977); Larson (1978); Cohen, et al (1972); Hosler (1966); and Shaffer and Cohen (1972). Finally, unpublished data from uranium exploration activities (Milly and Thayer, 1976) was analyzed. [Treating the ocean cases first, the mean values are generally consistent with those quoted earlier from Israel (0.0004 to 0.003 pCi lit-1); they range from 0.001 to 0.011 pCi lit-1, with 0.003 the most frequently reported value. Continental values, from eight studies, range in means from 0.07 to 0.41 pCi lit-1 (not including mineralized areas, or "uranium country", discussed later), with maxima as high as 2.4 pCi lit -l. For comparison, the means from Israel are 0.06 to 0.15 pCi lit-1, with a maximum of 0.53 pCi lit-1. Some of these studies also present the typical decrease of-1 concentration with height to 0.01 to 0.04 pCi lit at 5 to 7 km. The vast numbers of uranium prospecting radon data of]

Jan 1, 1981

By Warfield Garson

Few, if any, of the non-ionizing radiation health hazards to be found in either surface or underground coal mining are uniquely different because of their being found in the work environment. Hence, they can be considered generally for their bio-effects on the worker when found in the mining work environment. The same may not be said, however, for the lack of non-ionizing radiation and its bio-effects, particularly as it relates to underground coal mining. The term "non-ionizing radiation" refers to various forms of electromagnetic radiation of wavelengths longer than those of ionizing radiation. As the wavelength gets longer the energy of electromagnetic radiation decreases. Therefore, all non-ionizing forms of radiation have less energy than cosmic, gamma, and X-radiation. In order of increasing wavelength, non-ionizing radiation includes ultraviolet, visible light, infrared, microwave, and radiofrequency radiations. The energy frequency and wavelength range of both the ionizing and non-ionizing electromagnetic forces are shown in Table I. To convert the wavelengths of various radiations to Ångström units, one multiplies millimicrons by ten. In a vacuum, all electromagnetic radiation has the same velocity, namely 3 x 1010 centimeters per second. The natural source of radiant energy here on earth is our sun which emits radiation continuously over a wide spectrum. This radiation on average reaching earth ranges from 290 nm in the ultraviolet range to over 2,000 nm in the infrared range with a maximum intensity of about 480 nm in the visual range. You will note this falls into the visible blue wavelength and accounts for our blue sky and blue ocean and deep water effects. We are all familiar with the fact that the passage of solar radiation through the atmosphere to the earth changes the spectrum considerably because the atmosphere absorbs and scatters many of the sun&apos;s rays. The ozone in the upper atmosphere absorbs the shorter ultraviolet wavelengths and water vapor absorbs some of the infrared wavelengths. Smoke, dust particles, gas molecules and water droplets scatter the rays, especially those of shorter wavelengths. In addition to the sun, every gas, liquid or solid object at a temperature above absolute 0° radiates energy. Solid objects emit almost continuous spectra. At low temperatures only radiation of the longer wavelengths in the infrared range is emitted, but as the temperature of the object is increased, more and more of the shorter wavelengths are added. This fact is most readily demonstrated by heating a piece of steel. When a piece of steel reaches a temperature of about 1,700° Fahrenheit, it gives off radiation at the red end of the visible spectrum and appears dull red. As the temperature is further increased, the shorter rays are also emitted, until at about 2,100°F, the metal appears white, due to the emission of wavelengths throughout the entire visible range. Gasses, on the other hand, when heated emit radiant energy only at certain wavelengths, which are characteristic of their chemical structure. This latter fact is of importance in underground coal mining as high intensity gas and vapor lamps are becoming more and more utilized for illumination in underground coal mining. The biologic effect of non-ionizing radiation exposure depends upon the type and duration of exposure and on the amount of absorption by the miner. The effects of this radiant energy on the miner fall into four distinct types: (1) the heating effect of infrared radiation, (2) the effect on the eye of visible radiation, (3) the effects of ultraviolet radiation, and (4) the growing potential effects of the misuse of microwave radiation. Each non-ionizing type of radiation will be considered individually. ULTRAVIOLET RADIATION The sun is the major source of ultraviolet radiation, which is of concern in open pit and surface mining at certain seasons and in certain climes necessitating protection for the surface miners under those conditions; nonetheless, there are some man-made sources such as electric arc lights, welding arcs, plasma jets, and special ultraviolet bulbs for illumination underground that demand surveillance in the underground environment to be aware of whether the miners are at risk above the threshold limit values allowable. Since ultraviolet radiation has little penetrating power, the organs that are affected are the skin and the eyes. Ultraviolet radiation is strongly absorbed by nucleic acids and proteins, and the effects in man are largely chemical rather than thermal. Short-term effects on miners include acute changes in the skin. These are of four types: (a) darkening of pigment, (b) erythema (sunburn), (c) increase in pigmentation (tanning) and (d) changes in cell growth. Ultraviolet radiation also causes acute effects on the tissues of the eye. Overexposure can lead to keratitis, inflammation of the cornea, and conjunctivitis. Long-term effects of ultraviolet exposure include an increase in the rate of ageing of the skin with degeneration of skin tissue and a decrease in elasticity. Late effects of ultraviolet on the eye include the development of cataracts. The most serious chronic effect of ultraviolet exposure is skin cancer. Ultraviolet radiation effects are increased by some industrial materials and drugs. After exposure to such compounds as cresols, the skin is exceptionally sensitive to ultraviolet radiation. Photosensitivity reactions occur after exposure to a variety of other chemicals and drugs including dyes, phenothiazines, sulfonamides, and sulfanylureas. On the other hand, we must remember that ultraviolet radiation has an important role in the prevention of rickets. Vitamin D is produced by the action of

Jan 1, 1981

By H. P. van Ormer

The objective of this paper and the developed personal computer program is not to identify or try to identify the actual total drilling cost in any Rotary Drilled Blast Bole Program. The ideas put forth here and in the computer program developed are a very accurate way to measure what is often very hard to identify and interpret -The actual direct operating cost of various drilling package combinations including comparing with available blast hole sizes and patterns

Jan 1, 1988

By R. H. Busch, S. M. Loscutoff, F. T. Cross, R. E. Filipy, P. J. Mihalko, R. F. Palmer

INTRODUCTION During the last decade, several studies in France (e.g., Perraud et al. , 1970; Chameaud et al., 1974, 1979 and 1980) and the United States (e.g., Stuart et al., 1978; Cross et al., 1978, 1980 and 1981) have demonstrated the systematic production of emphysema, fibrosis and tumors in the lungs of animals exposed to radon daughters alone or to mixtures of uranium-mine air contaminants. The studies in beagle dogs have been particularly interesting because of the uncertain etiology of the disease and the (apparently) diverse results of the studies at the University of Rochester and the Pacific Northwest Laboratory (PNL). In the Rochester studies, reported by Morken (1973), beagle dogs were exposed to "normal" room air dust loads and radon daughters from 200 to 10,000 WLM*, delivered in 1 to 50 days (rate of delivery, about 200 WLM per day of exposure). Histological examination of tissues was conducted at 1, 2 and 3 years after exposure for all exposure levels. No cancers were noted in these dogs that received estimated alveolar doses of 34 to 1700 rad (0.34 to 17 Gy). Pathologic changes were found only in the alveolar and bronchiolar regions of the lung. These changes were small, subtle, variable, and widely separated, involving only a very small fraction of lung tissue. Lesions appeared as focal thickening of alveolar septa, with some metaplasia of alveolar cells and some hyperplasia of bronchial epithelium. In the PNL experiments reported by Cross et al. (1978), beagle dogs were exposed in lifespan studies to mixtures of radon daughters (rate of delivery, about 14 WLM per day of exposure), uranium ore dust and cigarette smoke. One group of dogs was exposed to cigarette smoke alone. Except in control and smoke-only groups, the dogs died within 4&apos; years of the first radon daughter exposure, or were killed when death appeared imminent because of pulmonary insufficiency (characterized by rapid, shallow breathing). Control and smoke-only animals were killed at periods corresponding to highmortality periods in the groups exposed to radon daughters and mixtures of uranium ore dust and cigarette smoke. Emphysema and fibrosis were much more prevalent and severe in the lungs of dogs exposed to the mixtures. These dogs also had adenomatous lesions, which progressed to squamous metaplasia of alveolar epithelium, epidermoid carcinoma and bronchioloalveolar carcinoma. Pathologic changes in the upper airways of these dogs were most prominent in the nasal mucosa, and included a few squamous carcinomas in the nasal cavity. Respiratory tract neoplasia was noted after ~4 years exposure and at cumulative exposures exceeding approximately 12,000 WLM. Apart from differences in associated carrier aerosol (room air dust vs. uranium ore dust) and radon-daughter exposure rate (200 WLM/day, shortduration exposure vs. 14 WLM/day, long-duration exposure), the most obvious difference in the Rochester and PNL studies was the observation time following exposure (3 years maximum vs. >4 years). Although neoplasia may not have been observed in the Rochester animals because of the earlier termination of the experiments, it is surprising that other lesions, such as prominent fibrosis and emphysema, were not reported. A follow-up study (reported here) is currently in progress at PNL to determine the pathogenic role of uranium ore dust alone and, in particular, to clarify the role of the ore dust in the production of the massive pulmonary fibrosis observed in the earlier study. Pulmonary function testing (a recently acquired capability) was included in the follow-up study as an indicator of progressive change in lung tissue. MATERIALS AND METHODS Chronic (4 hr/day, 5 days/week) exposures began when the dogs were about 2 1/2 years old. Two identical exposure chambers provided space for simultaneous, head-only exposure of 24 dogs to ~l5 mg/m3 carnotite uranium ore dust. An aerosol diffusion system was incorporated in each chamber in order to channel fresh aerosol past each dog&apos;s head; uranium ore dust was added to the inlet room air with Wright Dust Feed Mechanisms* (WDFM). Uranium ore dust and condensation nuclei concentrations were measured daily; chamber aerosols were monitored occasionally for particle-size distributions as described for previous hamster experiments (Cross et al., 1981). The carnotite ore used in these experiments, from the Mitten mine in Utah, was furnished in 1970 through the Grand Junction, CO Office of the (then) U.S. Atomic Energy Commission (now the Department

Jan 1, 1981

By M. R. Yalamanchili, J. D. Miller

Discussion by M.R. Yalamanchili and J.D. Miller The authors, M. S. Celik et al., should be recognized for their efforts to describe the flotation behavior of boron minerals. In the case of borax and other soluble salt minerals, analysis of the flotation chemistry has been difficult because of the high ionic strengths associated with these soluble salt systems. However, considerable progress has been made in this area, and recently a surface charge/collector colloid adsorption model was proposed by Miller and his coworkers to explain the collector adsorption phenomena observed in soluble salt flotation systems (Milleret al, 1992; Yalamanchili et al., 1993; Miller and Yalamanchili, 1994; Yalamanchili and Miller, 1994a: Yalamanchili and Miller, 1994b). In this work, the sign of the surface charge of alkali halides in their saturated brines was established on the basis of nonequilibrium electrophoretic mobility measurements by laser-Doppler electrophoresis (Miller et al., 1992). Generally, these results are what would be expected from the simplified lattice-ionhydration theory. This electrokinetic information coupled with the stability and prevalence of collector colloids in such soluble salt flotation systems indicates that the selective flotation of alkali halides is due to the adsorption of oppositely charged collector colloids by heterocoagulation. Experimental flotation/bubble attachment results for 21 different alkali halides (Yalamanchili et al., 1993; Yalamanchili and Miller, I994b) confirmed that the flotation response of soluble salt minerals with weak electrolyte collectors can best be explained by the adsorption of oppositely charged collector colloids rather than by the adsorption collector ions and/or neutral molecular dipoles as originally suggested by many researchers (Fuerstenau and Fuerstenau, 1957; Schubert, 1967; Roman et al., 1968). In addition, the flotation of certain alkali oxyanions (Pizarro et al., 1993) and double salts such as schoenite and kainite can be explained by the same collector colloid adsorption mechanism (Miller and Yalamanchili, 1994). The borax flotation results reported by Celik et al. need to be examined in terms of the above mentioned surface charge/ collector colloid adsorption model. Unfortunately, the authors seem to be unaware of this recent work that nicely describes soluble salt flotation with weak electrolyte type collectors such as amines and carboxylates. In view of our past work, the flotation characteristics of borax were of particular interest, and, in this regard, the results of dodecyl amine flotation of borax reported by Celik et al. have been examined in further detail in the light of experimental results from our laboratory. In our research, a vacuum flotation technique was used to study the flotation response of borax (Na2B407.10H20), which has a solubility of 39 g/L at 25 °C) with dodecyl amine hydrochloride as collector. These chemicals were purchased from Eastman Kodak and used as received. Saturated solutions of borax at desired pH values were prepared by continuously stirring the salt solutions over a period of about 10 hrs. It should be mentioned that the conditioning time to achieve equilibrium is an important variable and can significantly change the flotation response of some soluble salts (Yalamanchili et al., 1993). Collector was added to the saturated borax solutions containing about one gram of 100x 150 mesh borax particles, and conditioning was done for about 20 minutes prior to flotation. The borax flotation recoveries from saturated brine are presented in Fig. 1 as a function of collector addition at the natural pH of 9.3, as reported both by Celik et al. and as measured in our laboratory. In addition, the region of precipitation for the dodecyl amine hydroborate is included in Fig. 1. It can be seen in Fig. 1 that the flotation response curves are separated by about one order of magnitude in R12NH3CI collector addition. The flotation results of Celik et al. show that the maximum borax recoveries can be obtained below the solubility limit of the dodecyl amine hydroborate collector. However, in our experiments borax flotation seems to occur only after the precipitation of the dodecyl amine hydroborate collector as might be expected from the collector colloid adsorption model (Yalamanchili et al., 1993) if borax were negatively charged. Further analysis by nonequilibrium and equilibrium electrophoretic mobility measurements for borax indicates that borax is negatively charged at the natural pH of 9.3, as discussed below. The reliability of the nonequilibrium electrophoretic measurements has been demonstrated previously for alkali halides and alkali oxyanions (Miller et al., 1992; Miller and Yalamanchili, 1994). The equilibrium and nonequlibrium electrophoretic measurements for borax were found to be consistent and are presented in Table 1. These results provide clear evidence that borax carries a negative surface charge in its saturated brine (pH 9.3), and the sign of the surface charge of borax reverses and becomes positive if the pH is reduced to 8.6. The equilibrium between borax and its saturated brine can be described by the following reaction: [2Na2B407.1OH2O-4Na++B407=+HB4O7 +OH+19H20] It appears that the oxyanions of the borax lattice provide

Jan 1, 1995

By David Wilson, T. V. Rao

INTRODUCTION The Alchem trona mine, owned and operated by Allied Chemical Corp., is located approximately 32 km (20 miles) west of the town of Green River, and 8 km (5 miles) north of Interstate 80 in southwest Wyoming. Trona, a naturally occuring sodium sesquicarbonate (NaCO3 • NaHCO3 • 2H2O), is used for the production of sodium carbonate (Na2CO3), commonly known as soda ash. Present annual US consumption of soda ash is approximately 9.07 Mt (10 million st), out of which approximately 7.3 Mt (8 million st) is produced from the Wyoming trona mines. About 44% of soda ash is consumed by the glass industry; 3 % by exports; and the remaining portion by paper, chemical, soap, textile, and nonferrous industries. Allied Chemical operates an underground mine at an average depth of about 488 m (1600 ft). There are three other trona mines in the area operated by FMC Corp., Stauffer Chemical Corp., and Texasgulf Inc. (see Fig. 1). Allied Chemical became interested in southwest Wyoming trona deposits in the early 1940s. Explora¬tion work was begun in 1959 with the acquisition of federal leases. Exploitation of the reserves began in 1968. Two shafts, one 6.1 m (20 ft) and another 3.7 m (12 ft), were completed prior to 1968. The 6.1-m (20-ft) diam service shaft is divided in half by a cur¬tain wall, with one half used for men and material and the other for ventilation as a return air shaft. During the period from 1968 to 1974, the 3.7-m (12-ft) shaft was used as production shaft with two 7.3-t (8-st) skips. Due to the increased demand for soda ash, plant and mine expansions were completed during 1974. Under this expansion, the material handling system capacity was increased by constructing a new 2721-t (3000-st) capacity ore bin, sinking a 6.1-m (20-ft) diam produc¬tion shaft, and installing a friction hoist with two 22.7-t (25-st) skips. The Alchem mine manpower is 484 employees and about 2.3 Mt (2.5 million st) of trona was produced during 1976. Three different mining systems are used at the Alchem mine: conventional, continuous, and longwall. Allied Chemical introduced its first longwall unit in 1973, which was also the first longwall system introduced in the Wyoming trona district. At present, four conventional, seven continuous, and two longwall units are in operation. This equipment is operated in ten production areas. GEOLOGY The bedded trona and trona-halite in the Green River basin of southwestern Wyoming is a major re¬source for the nation. There are 25 beds that exceed 0.9 m (3 ft) in thickness and underlie areas of about 2590 km2 (1000 sq miles). There are other minor beds that range in thickness from 0.3 to 1.2 m (1 to 4 ft). Allied Chemical&apos;s Alchem mine is located in bed 17. The trona bed numbering system starts at the lowest elevation and increases upwards. The trona beds are in the Wilkens Peak member of the Green River formation. The Green River formation was deposited in a lake that began in early Eocene as a large body of fresh water, shrank in size and became saline, and then became fresh water again. The sedi¬ment during the saline phase of the lake, which includes the trona beds, is called the Wilkens Peak member. The underlying freshwater lake deposit is called the Tipton member and includes a 25.9-m (85-ft) sand unit which is a high pressure, low permeability aquifer. The over¬lying sediment is called the Laney shale. The Green River formation is underlaid by the Wasatch formation and overlaid by the Bridger formation (see Fig. 2). The structure of the beds in the area of the Allied Chemical mine is mostly postdepositional asymmetrical folds of small amplitude. These folds range in size of 3 to 6.1 m (10 to 20 ft) to as much as 45.7 m (150 ft). The trend of the folds is northwesterly with the north¬east flank of the anticlines having a steep dip and the southwest having gentle dips. Trona bed 17 varies in thickness from 2.4 to 3.4 m (8 to 11 ft) over the 93.2 km2 (36 sq miles) holdings of Allied Chemical and is flat lying except for the rela¬tively minor folding and a negligible regional dip of about 0.017 rad (1°). Trona occurs naturally in several physical forms in the Green River basin, being both massive and crystal¬line. The trona ore in the Alchem mine is a fine-grained massive ore with a compressive strength of approxi-

Jan 1, 1982

By George S. Austin

Mud is one of the oldest building materials used by man, but it is not only of historic interest. Even today in many parts of the world, particularly lightly forested areas, it is the chief building material. Many authorities believe that at least 30% and perhaps 50% of the world&apos;s present population lives in earthen dwellings (Dethier, 1985, Coffman et al., 1990). Not all of these people are members of primitive societies or live in third world countries. European, African, Asian, and both North and South American countries contain a large number of such structures. In the United States, the American West, and particularly the Southwest, is known for this type of construction. Some of the earliest remains of adobe structures are those discovered in the ruins of Neolithic farming villages in Mesopo¬tamia dating as far back as 7000 BC (Steen, 1972). The word adobe has its roots in Egyptian hieroglyphs denoting brick and evolved to its present form through Arabic and Spanish (Lumpkins, 1977). The Spanish conquest of the New World spread the use of wooden molds to produce a standard adobe brick. Today, the word adobe is used to describe various earth building materials and techniques, usually referring to sun-dried adobe brick now used in the United States, but is also applied to puddled adobe structures, mud-plastered logs or branches (Jacal or waddle-and-daub), pressed-earth blocks, and rammed-earth walls or pisé (Smith and Austin, 1989, Ferm, 1985). Modern mud construction is used in many countries in various parts of the world. In the United States, the states from Texas to California are perhaps best known for this type of construction. Of these states, New Mexico has the dominant reputation for adobe use. Indeed, in New Mexico the Santa Fe style (Fig. 1) has made adobe not only acceptable, but preferred. RAW MATERIALS Adobe soil used by present day adobe producers, and probably past adobe producers as well, is principally sandy loam (50% clay and silt), although clayey silts are used in some areas (Coffman et al., 1990). In New Mexico, the best adobe soils are those developed on stream deposits, particularly Holocene (Recent) terrace deposits and older, loosely compacted geologic formations, such as the Santa Fe Group (Tertiary) located in the Rio Grande Valley. Some modern adobe producers use a mixture of materials from the screened fines of aggregate operations and mud from irrigation ditches in the river valleys combined with varying amounts of sand to produce the proper blend. Mineralogy Bulk Mineralogy: X-ray diffraction analyses of whole rock samples from many parts of the world where adobe is the dominant construction material show the major constituents of adobe are quartz and feldspar, with lesser amounts (in order of abundance) of calcite, clay minerals, and gypsum (Coffman et al., 1990). Adobes from and climates contain considerable calcite; in some cases calcite is second only to quartz in volume. Quartz, feldspar, most of the clay minerals, and some calcite commonly are derived from the mechanical/chemical breakdown of older rocks units. Some of the clay minerals, much of the calcite and perhaps all of the gypsum are precipitated from evaporating water. Clay Mineralogy: Clay-size minerals consist dominantly of clay minerals, but nearly clay-size fractions contain minor amounts of quartz and calcite, and occasionally other nonclay minerals. In earth construction materials from New Mexico, clay-size particles are the most compositionally variable in commercial adobe soils. However, the clay mineral groups in this size fraction consist of about equal parts of expandable clay minerals (smectite and mixed¬layer illite/smectite or I/S) and non-expandable clay minerals (ka¬olinite, illite, and chlorite), with minor quartz, calcite, and feldspar (Smith and Austin, 1989, Austin, 1990). In the and American Southwest, smectite is commonly calcium-rich and the I/S is dis¬organized and randomly interstratified. In a study of 42 New Mex¬ican commercial adobe soils, only two contained chlorite, and vermiculite, sepiolite, and palygorskite were not found. Soils in temperate climates, as are found in the midwestern and northeastern United States, contain an abundance of illite (Potter et al., 1975). The clay minerals in earthen structures of that region and in Europe commonly contain illite with less amounts of kaolinite, smectite, I/S, chlorite, and vermiculite. In contrast, the clay-size fractions of soils of humid tropical areas are typically acid, with kaolinite as the dominant clay mineral and lesser amounts of I/S, illite, smectite, and others (Chamley, 1989).

Jan 1, 1994

By Ian M. Loomis, Keith G. Wallace

The Waste Isolation Pilot Plant (WIPP) is a U.S. Department of Energy research and development facility designed to demonstrate the permanent, safe disposal of U.S. defense-generated transuranic waste. The waste storage horizon is 655 m (2150 ft) below surface in bedded salt. To date the WIPP project has not emplaced any waste. There are three intake shafts used to supply air to the underground. All air is exhausted though a single return shaft. The total design airflow during normal operations is 200 m3/s (424,000 cfm). The ventilation system is designed to provide separate air splits to construction, experimental, and storage activities. Separation is achieved by isolating the storage circuit from the construction or experimental circuits with bulkheads. Any air leakage must be towards the storage area of the facility. Field studies have shown that the pressure differential necessary to maintain the correct leakage direction is susceptible to the effects of natural ventilation; therefore, extensive studies and analyses have been conducted to quantity the natural ventilation effects on the WIPP underground airflow system. A component of this work is a monitoring system designed to measure the air properties necessary for calculation of the natural ventilation pressure (NVP). This monitoring system consists of measuring dry bulb temperature, relative humidity, and barometric pressure at strategic locations on surface and underground. The psychrometric parameters of the air are measured every fifteen minutes. From these data, trends can be determined showing the impact of NVP on the ventilation system during diurnal variations in surface climate. Both summer and winter conditions have been studied. To the author&apos;s knowledge this is the first reported instance of automatic and continuous production of time and temperature variant NVPs. This paper describes the results of the initial monitoring study. INTRODUCTION The ventilation system at the Waste Isolation Pilot Plant (WIPP) in Carlsbad, New Mexico, is designed to perform two distinct functions. First, it supports normal mine ventilation requirements complying with all state and federal mine regulations. Second, the system is designed to prevent an uncontrolled release of radioactive contaminants from the storage and transportation areas of the facility. Although a nuclear radiation release in the facility is considered unlikely, many special features are implemented in the ventilation system to prevent the possible spread of contamination. The facility is constructed with the waste transportation and storage areas separated from the mining and non-radioactive experimental areas. The ventilation system is designed such that air leakage is from the mining and experimental areas to the storage areas. Furthermore, radiation detectors are located throughout the storage and waste transportation areas underground and an exhaust filtration building is installed on surface to prevent the possible release of radiation to the environment. For over two years the underground ventilation system has been rigorously tested and balanced. It was during this period that the adverse effects of NVP were noticed and subsequently quantified. From extensive field studies and computer models, several mitigating features were designed and constructed and special operational procedures were implemented to control the impacts of NVP. To quantify more accurately the NVP at the WIPP, a continuous monitoring system was installed. This monitoring system consists of measuring dry bulb temperature, relative humidity, and barometric pressure every fifteen minutes at strategic locations on surface and underground. From this psychrometric data, the NVP is calculated. Fan operating pressures and flows and strategic differential pressures are recorded from the site Continuous Monitoring System (CMS). The monitoring system provides a means of evaluating how the ventilation system behaves in regard to climatic conditions and to judge the efficacy of the mitigating features and operational procedures. To the author&apos;s knowledge, continuous calculation of NVP as a function of time and surface temperature has not been previously reported. Overview of the Waste Isolation Pilot Plant The U.S. Department of Energy determined that the plastic nature of bedded salt may provide the best solution to isolate transuranic (TRU) waste from the biosphere. Initial evaluations at the WIPP site began in 1974. In 1979, the United States Congress enacted Public Law 96-164 for the construction and development of the WIPP project. The mission of the WIPP is to demonstrate the safe, long-term disposal of TRU waste generated by the national defense programs of the United States. TRU waste is classified as a low to medium level waste. The waste is stored in drums and does not produce significant heat (not greater than 1 W per drum). The WIPP site is located approximately 47 km (29 miles) east of Carlsbad, New Mexico in the Chihuahuan Desert. The repository is located in the 630 m (2000 ft) thick Salado Formation. This Permian Basin salt deposit is about 225 million years old and appears to have been minimally disturbed by earthquake, faulting, and ground water activity since it was deposited. The underground facility is 660 m

Jan 1, 1993