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By Philip E. J. Green

Two of the cornerstones of total quality management, the use of statistical and problem solving tools, and the involvement of employees, are directly applicable to environmental protection. The reduction in variation decreases the chances of violations and mishaps. Involving employees in minimizing environmental impacts is critical. One mistake, even with the best technology, and your plant can be shut down, customers lost and fines and penalties imposed - your reputation and the environment damaged. Proven strategies for involving employees in environmental protection, and over-coming the frequently strong differences of opinions about what constitutes environmental protection, will be discussed.

Jan 1, 1992

By Charles L. Kimbell

In 1988, the aggregate value of total world international export trade in mineral commodities was estimated at nearly $542 billion in current (1988) dollars, which was about 8.6% above the 1987 level, but still 23.7% below the record high set in 1980. Comparable comprehensive data for 1989 were not available in time for inclusion in this chapter, but 1989 returns for developed market economy countries only were 1 1.8% above those for 1988. These countries accounted for about 50% of the total mineral commodity export trade in 1988. It would be unsound to utilize the overall 11.8% growth rate for mineral commodity export trade for these countries to extrapolate the growth in total world mineral commodity trade because these developed market economy countries account for substantially different shares of the five major mineral commodity groups listed in table 2. Specifically, developed market economy countries in 1988 accounted for 56% of world export of ore, concentrate, and scrap, 74.7% of world exports of iron and steel, 71.7% of world exports of nonferrous metals, and 57.8% of all exports of crude nonmetals, but only 26.6% of world exports of mineral fuels. Moreover, even within each of these groups, the actual product mix included in developed market economy country aggregates differ from that in developing market economy country aggregates and in centrally planned economy country aggregates. Nonetheless, an increase of 9% to 12% in the value of world mineral commodity export trade seems indicated by available returns.

Jan 1, 1992

By Summers D. A.

A mining machine has been designed and fabricated to mine coal from room and pillar operations combining high pressure waterjet cutting and mechanical fragmentation. Waterjets are used to slot the coal face with an advancing plow wedge then breaking out larger coal pieces. The machine has the following advantages: - simply built around a disassembled longwall chock and gathering arm loader apron; - few moving parts which are simply and inexpensively maintained; provides immediate roof support in the face working area; - coal produced is larger, with resulting lower preparation cost; - no dust is generated; - risk of spark generation is virtually eliminated.

Jan 1, 1992

By J. Boitano

This paper discusses the study, design and implementation of the new gas handling system for the Caletones Smelter of Cbdelco..Chile. A discussion on design conditions for a Mure Sulphuric Acid Plant using Teniente Converter.gases.is also included. The old system which started to be modified in 1985 and relied on natural draft and used balloon flues, resulted in a limited .gas handling capacity for operation under Mure process conditions. This system also caused excessive fugitive gases in the smelter working areas. The new system permits handling of process gases from the higher capacity Teniente converters installed in 1987-1989 Improving the gas handling of the reverberatory furnaces and Peirce-Smith converters as well as the environmental conditions of the smelter. This system utilises improved converter gas hoods, evaporative cooling and electrostatic precipitators gas cleaning, and is based on natural draft.

Jan 1, 1992

By Elaine Ellingham, Francis T. Manns

"The Orostar and Scadding were two small gold mines owned and operated by Orofino Resources Limited. Conventional statistical treatment indicates an identical arithmetic mean grade of 0.22 oz/T Au for both mineable reserves. Further, the deposits are both shown to have cut weighted average reserve grade of 0.21 oz/T. Orostar mined out at 0.206 oz/T and Scadding at 0.156 oz/T Au. The combined exploration and development database contained 1394 fire assays, more than enough for statistical confidence in a normal distribution. Therefore this study was initiated to determine, if possible, why the mill head grades were lower than the averages and to experiment with several methods to determine whether a reliable statistical mill head grade estimation method would emerge. Despite the identical reserve grades, distinct differences in the grade distribution histograms are present. By studying the arithmetic and log-normal grade distributions, with some attention to South African practices, this paper reports on those differences which may account for the considerable divergence in the mill head grades. Furthermore, this study casts considerable doubt on the industry standard method of cut weighted averages.The global mill head grades of the two deposits have been derived from the arithmetic average grades by graphic means. This precise method of mill head grade prediction, if applied to complex orebodies, could permit selective grade control and result in direct cost savings by allowing the operator to detect false value stopes, benches or levels and emphasize reliable regions of not only gold mines, but also uranium or base metal deposits."

Jan 1, 1992

By J. C. Cawley

Improvements in today's maintenance practices are mandatory as more complex and productive machines evolve in the mining industry. By keeping machine reliability high through improved maintenance procedures, overall mining costs can be reduced. The Bureau of Mines is investigating diagnostic maintenance systems for underground mining machinery. A hydraulic expert diagnostic system and an electric motor predictive diagnostic system have been designed and installed on a Joy 16CM continuous miner. An electrical diagnostic system has been designed and installed on a Joy 14CM continuous miner. Each system is functionally described and the relative merits of expert diagnostic systems versus algorithmic diagnostic systems are discussed.

Jan 1, 1992

By Gary K. Elliott

Many industrial processes generate hot waste gases which contain particulate pollutants. Conventional clean-up techniques suffer limitations either because collection efficiency is low or because the gas must be cooled before treatment. thereby increasing costs and preventing energy recovery. The application of increasingly stringent environmental legislation to the non-ferrous metallurgical industry is presently illustrating these conventional technology limitations. Low density ceramic media allow filtration to ta,ke place at 'high temperatures and are now rapidly becoming accepted In many industries. This paper reviews experiences with a proprietary low density ceramic filter element. CerafH. It includes consideration of the structure, composition. typical operating and case studies with particular reference to non-ferrous metallurgical furnace applications.

Jan 1, 1992

By J. Hupka

Some aspects of kerosene penetration into tar sand have been investigated. The natural tar sand porosity was measured and used to analyze the performance of the hot water process. Subsequently, pretreatment experiments, using 20 kg tar sand samples (Asphalt Ridge and Whiterocks, Utah), and kerosene as a diluent were carried out at the expected summer temperature (26°C) and the expected winter temperature (-14°C). The natural tar sand porosity accessible by diluent has a crucial impact on the reduction of bitumen viscosity, and influences the penetration time required for successful bitumen separation from tar sand by hot water processing. Thus the tar sand porosity is an important variable which determines appropriate operating conditions. Experimental results indicate that diluent penetration into the Asphalt Ridge tar sand (high porosity) is almost complete after 30 min, whereas for the Whiterocks tar sand (low porosity) the penetration process is much slower, and still not complete after 15 hours regardless of the ambient temperature.

Jan 1, 1992

By Miguel N. Herrera, Abbas H. Mirza, Fiona M. Doyle

The standard test methods used to determine the pyrite content of coal and mineral wastes, and their propensity to release acidic drainage, are critically reviewed. In addition to analysis of total sulfur by combustion, test methods using selective oxidation of pyrite by HNO3 and H2O2 are available. The oxidation kinetics of pyrite vary appreciably from sample to sample, and it is difficult to ascertain whether complete dissolution has occurred in heterogeneous materials. The reliability, reproducibility and suitability of different standard test methods were studied, using well characterized ore and coal pyrite samples. The kinetics of pyrite dissolution were also investigated. The results are discussed in terms of the fundamental chemical and physical characteristics of each sample, and the implications for waste characterization are considered.

Jan 1, 1992

By Richard S. Kunter

Artech Recovery Systems, Inc has developed a low pressure and temperature? leach process called the "Cashman Process" to extract metals from arsenical flue dusts and residues and fix the arsenic in an environmentally stable form as ferric arsenate (scorodite). The process was pilot tested at Hazen Research in an integrated plant including continuous recycle from August 1989 to October 1989 during which several tons of flue dust were processed. Based on this pilot program, the process was deemed technically feasible and produced commercially salable products. Residues from this pilot program were subjected to a long-term stability test jointly designed by PTI environmental services and the USEPA. The process, its versatility, and the nature of the products is discussed in some detail.

Jan 1, 1992

By David J. Dunn

Materials related problems at mines can be big ones - like a newly completed 1 -m (3.5ft) water pipeline burst during initial filling, grinding ball consumption at double the typical norms on startup of a new semiautogenous grinding (SAG) mill circuit or 30 open-pit haul trucks in the shop for new bed liners after less than a year’s service. Materials engineering provides solutions to these kinds of equipment problems by selecting good materials and designs, by trouble-shooting service failures and by maintaining high quality in vendor-furnished materials and components. Materials with good properties, correctly made and fabricated, correctly installed in mining and processing equipment, produce ore and final products reliably and efficiently. Materials engineering, applied during design phases, specification writing, and receipt and installation of materials, ensures that equipment will have the best possible shot at performing up to expectations. Good calls on materials properties - specifying state-of-art materials produced by competent manufacturers - help mine managers to reduce downtime and mining and processing costs. Materials that are improperly made or specified can make a mining operation less efficient or, possibly, uneconomical.

Jan 1, 1992

By Hendon G. W, Carr F, Jiang Y

A vast majority of the operating longwall sections use shield-type face supports to provide ground control in the United States. As a co-operative research program between the University of Alabama (UA) and Jim Walter Resources, Inc.(JWR), a joint research program is underway to study interaction of shields with surrounding rock masses. A series of analyses on the response of shields are performed using monitored data at a longwall face in a deep coal mine. In this paper, various effects of parameters, such as leg pressure, setting load, developing load, maximum loading rate, pressure in capsule, and convergence between canopy and base, are discussed and recommended as stability indices. A microcomputer program is being developed for instantaneous interpretation of the shield monitored data, and for giving warnings of potential problems. The preliminary results define the effects of the setting load, developing load, and rate of developing load or leg closure rate. The objective of the study is to understand the shield characteristics and their interaction with surrounding strata in real time, then develop a reliable program for maintaining longwall stability.

Jan 1, 1992

By Kenneth L. Driggs

The Environmental Protection Agency's Clean Air Act of .1970 provided the driving force for the current Magma Smelter configuration. The historical and technical perspectives of those process developments are reviewed. Innovations in procedures and equipment have allowed compliance with the requirements of the regulating authorities. The wet scrubbing of converter gasses and the monitoring of converter operations by a controlling foreman are two of the major contributors to these successes. The Clean Air Act Amendments of 1990 have posed many new concerns for all U.S. industry, including the few (seven) primary copper smelters remaining. Future concerns include tightening the sulfur dioxide ambient standard from the current three-hour averaging period to one hour"

Jan 1, 1992

By S. L. Bessinger

Introduction Extensive testing in the past ten years has shown that where a uniform natural gamma background is present in the strata bordering a seam, the thickness of the boundary coal left in place after mining can be determined by measuring the attenuation of that radiation (Nelson and Bessinger, 1989). Measurements made by the authors in underground mines in Pennsylvania, West Virginia, Ohio, Illinois and Kentucky and by others in Wyoming and New Mexico have shown the presence of such a gamma background (Nelson. 1989). Natural gamma coal-thickness sensors of several configurations have been tested in mines owned and operated by the Consolidation Coal Company (Consol) in Pennsylvania and West Virginia (Nelson and Bessinger, 1988). This paper describes the installation of a natural gamma coal-thickness sensor on an operating continuous miner. Previous tests had shown that the NGB-1000 coal-thickness sensor manufactured by American Mining Electronics, Inc., of Huntsville. AL, is an accurate, mine-worthy instrument. This large gamma detector consists of a sensing head and a control panel. The sensing head contains thallium-doped, sodium iodide scintillating crystal, which is coupled to a photomultiplier tube. The control panel contains the electronic components required for calibration, count conversion and display to the operator. Methods Conditions at a Consol mine in northern West Virginia require that 10 to 15 cm (4 to 6 in.) of coal be left at the roof boundary of continuous miner development sections. This roof coal is required because the shale of the immediate roof is friable and unstable. In the past, operators have used a dirt band that is usually visible near the top of the seam as a guide in maintaining the proper cutting horizon. However, this is not always reliable. Earlier observation showed that the actual thickness of the coal left on the roof varied widely; further, it was noted that occasional, accidental excursions into the immediate roof required supplementary roof control measures, such as installation of planks or center bolts. Thus, it was concluded that operators needed a better source of guidance for control of the cutting horizon, and a roof-coal thickness sensor was scheduled for installation. The NGB-1000 sensor was installed on a Joy 12CM10 continuous miner in June 1988. The sensing head was mounted on the cutter boom of the miner, and the control panel was mounted in the operator's cab. Power for the sensor was initially derived from an intrinsically safe battery power supply. Initial measurements with the sensor showed that the calibration was the same as that used in earlier tests at two other mines, indicating the uniformity of the natural gamma background above the Pittsburgh seam. Operating personnel were initially skeptical of the instrument's accuracy, and were hesitant to use its readings as a guide in maintaining a proper cutting horizon. Because gamma attenuation, the instrument's operating principle, is somewhat abstract, attempts to demonstrate the instrument's accuracy by explaining that principle were generally ineffective. It was found, however, that an operator could usually be convinced of the usefulness of the instrument by placing a large piece of coal of fairly uniform thickness over the instrument's sensing head and allowing the operator to see that the instrument reading increased by an amount very near his estimate of the thickness of the piece. The mine was provided with seven battery power supplies and a charging station. The charging station was kept in the lampman's office, and the mechanic on each shift was instructed that he was responsible for two battery power supplies each day: a freshly charged one to be taken in at the beginning of his shift and a depleted one to be brought out at the end. This system worked well for a few weeks, but eventually some battery power supplies were left in use so long that their batteries were discharged too deeply to allow recharging. In addition, transport and recharging of the batteries represented an additional task for the mechanics, who were already very busy. Consequently, a request was filed with MSHA to allow the sensor to be powered through intrinsic safety barriers by an electronic power supply connected to machine power. The permit was granted, and the sensor was connected to machine power. After the sensor was connected to machine power, the only operating problem experienced was occasional failure of cables. A supply of the required cables was made and delivered to the mine so damaged cables could be quickly replaced. Much of the cable damage could be eliminated by slight modifications to the miner during a rebuild, so that cables could be installed in more protected locations. After the sensor had been in operation for about two months, a survey was made to determine its effect on continuous miner operations. In previous research, coal thickness measurements made in 88 locations by the natural gamma method were compared to measurements made in the same locations by observing drill cuttings and by inspections of drill holes with a borescope. That research showed that the gamma method is at least as accurate as the other two methods (Nelson and Bessinger, 1989) and is also much easier to use. The object of the survey described here was not to assess the accuracy of the natural gamma measurements. but rather to determine the effectiveness of the sensor output as a guide for the operator in maintaining control of the cutting horizon. Thus a smaller, hand-held gamma detector

Jan 1, 1992

By Art Johnston

Gas handling at Magma Copper company's, San Manuel smelter receives process gas from a flash .smelting furnace and four copper converters. The major gas handling equip11lent consists of four electrostatic precipitators and a sulfuric acid plant. Process ,vessels in gas handling are, typically confined, spaces. Lethal gases, mechanical and chemical hazards, and the difficulty of rescue, should an accident occur, makes this area a must in the safety plan. The presence': of hazardous chemicals and explosive gases in process' vessels and piping are of major concern when repairs' are required. Proper job procedures are critical to prevent injury during repairs. This includes plant employees and contractors who are likely to be unfamiliar with the hazards ,involved. The safe operation of a gas handling operation must include the functions of operations employees on a daily basis. This includes a safe working environment and involvement of all employees in the safety program. If an injury does occur quick medical response is critical to prevent serious injury. Medical responders must be adequately trained and prepared to treat the injured person without becoming victims' themselves. The methods used at Magma Copper Company to deal with these safety problems are the focus of this presentation.

Jan 1, 1992

By Jr. Denton

This U.S. Bureau of Mines report presents the documentation for HEAPREC, a methodology for calculating reclamation performance bonds for cyanide heap leach operations. HEAPREC is a template developed for use with Lotus 1-2-33 release 2.01 or newer software. The report is presented in step-by-step "user's manual" format. Appendices contain detailed background and reference material on performance bonding, cyanide detoxification regulation, cyanide detoxification methods, general mine reclamation procedures, and an example bond calculation.

Jan 1, 1992

Although not immune from the problems affecting the U.S. economy generally, the mineral industry in 1991 contributed nearly $300 billion in the value of processed materials of mineral origin. Supporting this contribution, the Bureau of Mines continued the research and analytical programs highlighted in this annual review. Featured in 1991 were such relatively new programs as minewide monitoring applications in ground control and advances in processing of ceramics and composites, along with more traditional research into health, safety, and mining technology, minerals and materials science, and environmental technology. Under Bureau sponsorship, a National Minerals Policy Forum brought together some 200 executives from industry and Government concerned with minerals policy to begin a dialogue on developipng a policy statement on current minerals issues. A major feature of the forum was the keynote address by Secretary of the Interior Manuel Lujan, Jr.

Jan 1, 1992

The value of processed materials of mineral origin was estimated to have exceeded $297 billion in 1991. U.S. raw non fuel minerals production in 1991 was estimated at $30.8 billion, a 5.8% decline from that in 1990. This estimate was based on data for the first quarter of 1991 (in some cases two quarters) for most of the 21 minerals that for many years have accounted for more than 95% of the industry's production value. The value of minerals production has increased in all but 4 of the last 30 years. The metals component of production value has fluctuated much more than the industrial minerals component, reflecting the greater volatility of metal prices. Employment in metal mining rose slightly in 1991, but this gain was more than offset by a decline in employment in industrial mineral mining, resulting in an overall decline of 3.0% to 164,600 workers in 1991. Prices of several major metals declined during 1991, reflecting weakness in the economy, causing some metal mines to shut down or reduce operations.

Jan 1, 1992

By Staff

The goal of the U.S. Bureau of Mines diesel engine research program is to reduce exhaust emissions from diesel-powered equipment used in underground mines. This research has led to significant advances in aerosol measurement and to the development of more effective emission controls. This Information Circular contains reports of some of the presentations made at the Bureau's Information and Technology Transfer Seminar on Diesels in Underground Mines given in Minneapolis, MN, on September 29-30, 1992. The seminar emphasized the measurement and control of diesel particulate matter emissions. Topics covered include a discussion of the health issues associated with the use of diesel equipment underground, an overview of regulations, measurement techniques for diesel exhaust aerosol, levels of diesel exhaust pollutants found in mines, and modern emission controls. An appendix is included that contains a report describing the capabilities of the Bureau's diesel emissions research laboratory, two papers describing the effects of engine maintenance or: emissions, a paper describing the monitoring of carbon dioxide in mine air as an indicator of air quality, a glossary, and a list of abbreviations and acronyms.

Jan 1, 1992

By J. E. Hamak

This publication contains analyses and related source data for 266 natural gas samples from 20 States and 2 foreign countries. None of the analyses have been previously published in annual reports. All samples were obtained and analyzed as part of the U.S. Bureau of Mines investigations of the occurrences of helium in natural gases of countries with free market economies. This survey has been conducted since 1917. The analyses published herein were made by mass spectrometer and chromatograph.

Jan 1, 1992