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By L. E. Beverage, K. L. Johnston

This paper will address methods for minimizing liability and protecting materials from disclosure as result of self- evaluative audits and internal investigations. Specifically, the paper will cover the role of counsel in the investigative process and how best to design and conduct internal investigations to minimize the development of problematic material and disclosure of information. The paper will also address the extent of privileges that may be relied upon to protect materials and information from disclosure. These include the attorney-client privilege, the self-critical analysis privilege, and the attorney work product privilege. These privileges are qualified and understanding the limits of their coverage is essential to minimizing liability.

Jan 1, 2001

By C. R. Hairfield

With ever rising energy costs, it is increasingly important for mines to operate with energy efficiency. As a large portion of a mine?s energy consumption is often attributed to the operation of mine ventilation fans, maintaining an efficient ventilation system is a critical pro-active way for mining companies to reduce power costs. A common way to measure a mine?s ventilation system efficiency is to calculate the volumetric efficiency, which is simply a calculation of the percentage of total mine air that is usefully employed for production. The purpose of this study is to document a nationwide comparison of the volumetric efficiency of U.S. underground coal mining operations. The results will aim to show just how efficient today?s coal mine ventilation systems are and what factors may be causing their various efficiencies and inefficiencies.

Jan 1, 2009

By Marreros D. Oscar

La perforación y la voladura son mecanismos que suministran material adecuadamente roto al equipo de carguío. La efectividad de ambos depende de la evaluación de la perforadora y de los explosivos a utilizar. En esta perspectiva, el presente trabajo describe los parámetros necesarios para evaluar los requerimientos de perforadoras en una mina nueva. El proceso de selección y evaluación conlleva una optimización económica del equipo de perforación para cumplir el plan de minado, asegurando la producción t reduciendo los riesgos financieros. Asimismo, se presenta el análisis de inversión con la técnica de flujo de caja descontado.

Aug 26, 1988

By R. Duncan Gardner

This paper describing the milling practice at the concentrator of the Harmony Mines Co. is one of a series being; prepared by the Bureau of Mines on milling methods and costs in the United States. For the period February 15, 1929, to June 1, 1929, the concentrator treated 200 tons of copper ore per day containing 3.84 per cent copper and recovered 99.2 per cent of the total copper in concentrates averaging 26.61 per cent copper. Milling practice at the Harmony Mines is in most respects similar to the usual practice at the average flotation concentrator producing bulk flotation concentrates. The exceptionally high recovery is due to a number of minor conditions. These minor details will be stressed throughout this paper.

Jan 1, 1930

By D J. Brake

The correct specification and then selection of primary or major fans for an underground mine is a critical decision not only in terms of fan capital and operating costs, but also safety and reliability which usually has a major impact on mine production. In addition, fan manufacturers may spend tens of thousands of dollars preparing proposals for a purchase enquiry for primary fans especially where they have complete responsibility for the installation (turnkey projects). There are many good reasons to thoroughly and fairly adjudicate fan tenders. This paper describes the process to achieve this starting with the initial fan specification through to the final award.CITATION:Brake, D J, 2017. Fan specification and tender adjudication for mine ventilation engineers with particular reference to turnkey projects, in Proceedings Australian Mine Vent Conference 2017, pp 245–252 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By N. Kanari

Chalcopyrite concentrates and their pure constituents were chlorinated by C12+N2 between 25 °C and 750 °C. The reaction products were analyzed by SEM, XRD and chemical analysis. The effect of gas flow rate and chlorine content of the gas mixture on the reaction rate were investigated. At room temperature, these solids start to react with chlorine giving metal and sulfur chlorides. Complete reaction is achieved at about 300 °C and the iron and sulfur chlorides were fully volatilized. The chlorination residue is composed of valuable metals' chlorides. A simplified flow - sheet for the treatment of chalcopyrite concentrates by chlorine was suggested.

Jan 1, 1998

By S. L. Barua

An industrial engineering and computer simulation study was conducted on reclamation operations to evaluate the possibility of integrating mining and reclamation operations, and to evaluate the factors which influence the production potential of scrapers. The study was done in a southern Illinois strip coal mine producing approximately 2.27 M metric tons (2.5 million short tons) of clean coal annually. The main outcomes of this study are (a) it is possible to reduce reclamation cost about 20-25 percent by integrating reclamation and mining operations, (b) haul distance has the most significant effect on scraper production, (c) push-pull is the best mode of operation for wheel scrapers for topsoil/subsoil removal, and (d) historical data obtained from the mine for one year show that average dozer productivity in rock grading is about 60 percent lower than the expected production; similar data for scraper is about 25 percent less.

Jan 1, 1981

By Robert D. Thomson

The Bureau of Mines has compiled coal reserve data for the United States as of January I, 1974, for bituminous and anthracite coalbeds 28 inches or more in thickness to a maximum depth of 1,000 feet and for Lignite beds 40 inches thick or greater. These data were organized by State, county, coalbed, and rank. To evaluate the reserve by sulfur content, the reserve and analytical data from the Bureau of Mines energy data bank were synthesized using computer techniques. The reserve base in the Eastern States was determined to be 202.3 billion tons. Bituminous coal accounts for the greatest reserve base: 161.5 billion tons of deep-minable coal, and 32.5 billion tons of strip-minable coal. Virtually all of the anthracite reserve base, 7.3 billion tons, is minable by underground methods. All of the lignite, 1 billion tons, is strip minable. Subbituminous coal is not significant in the Eastern United States, About 14 percent of the bituminous coal reserve base, 26.5 billion tons, contains 1.0 percent or less sulfur. About 87 percent of the anthracite reserve base, 6.3 billion tons, is low-sulfur coal.

Jan 1, 1975

Jan 1, 1966

By William Gleason

"It is safe to say that the coal industry, in the United States and globally, is currently suffering through one of the hardest times in its history.A perfect storm of competition, changing energy demands, politics and public perceptions have collided, inflicting significant harm to the industry that many say is irreparable. This, in turn, has led to massive job losses in some regions, heavy cuts in production and even bankruptcy filings from two of the largest coal mining companies in the nation.Cheaper natural gas can certainly take a large share of the blame for the struggle of coal, as utility companies switch from coal to natural gas for power generation. According to the U.S. Energy Information Administration (EIA) the amount of coal used for electricity generation in the United States is at a 45-year low.November 2015 marked the fifth consecutive month that natural gas was the leading source of power generation in the United States. EIA said generators produced 101,866 thousand megawatt hours (MWh) of electricity with gas in November versus just 87,789 thousand MWh with coal, the lowest monthly level since May 1980 when monthly coal use was 84,884 thousand MWh.According to Robert Godby, director of the Center for Energy Economics and Public Policy at the University of Wyoming, there are a number of factors playing a role in the decline of coal, but he points to the advances in fracking as the tipping point.“A lot of people will argue that regulation is the cause of the decline, and it has played a part, for sure, but the story of the recent past is more about what competition has done to the energy market,” Godby told Mining Engineering. “The war on coal was originally declared by natural gas in 2008.”The price of natural gas, which was at $13 per million Btu before the gas fracking boom, has fallen to as low as $1.68 in December 2015. Likewise, Godby said the cost of wind generation is now lower than the cost of generation from coal and the cost of solar generation is coming down as well. In addition to that, the demand for energy has changed in the past five years with more efficiencies in everything from building design to lightbulbs."

Jan 1, 2015

Waihi Gold Mining Company Limited, a wholly owned subsidiary of Normandy Mining Limited, operates the Martha gold mine, located in the township of Waihi, New Zealand. The operation, an unincorporated joint venture, comprises Normandy Mining Limited (67.070/0) and Otter Gold Mines (32.94%). Since gold was first discovered at Waihi in 1878, it has formed a key part of the region's economy. In 1909 the Waihi mine was described in a report to Parliament as æthe most important gold mine in Australasia and one of the greatest in the world.Æ That was a record year for production, with 416,813 tons of ore mined and some 1,120 men employed. Today the mine produces up to 1,250,000 tonnes of ore annually, and the project employs some 234 men and women. In 1999 the value of the gold and silver produced ($59 million) made up 47% of Waihi's estimated GDP. Waihi Gold has made significant contributions to the Waihi economy, community and the Hauraki region as a whole. Since the mine was re-opened in 1987, thousands of local people have benefited from the mine. In 1999, consents were granted allowing an extension to the mine life (the Extended Project) and this will result in a further seven years of economic benefits resulting from mining activity. The Company has undertaken extensive consultation throughout project planning, construction, operations and rehabilitation. Ongoing liaison and involvement with all community sectors, including Tangata Whenua and Iwi, local residents, recreational groups and schools remains an integral part of the operation. Throughout the life of the modern Martha Mine, the Company has actively supported the local community in the form of donations, sponsorships, the provision of amenities, and by participating in community events. A well established environmental team exists at the site. Environmental and community performance is measured by an independent five-assessment process, and the Company is committed to achieving excellence through ongoing improvement programmes and staff awareness. When the mine is closed, the open pit area will be transformed into a recreational lake, and the tailings storage facilities will be rehabilitated to become a combination of wetlands, grassed areas and ponds. Resources will be provided by the Mine to ensure the rehabilitated site remains in a safe and self-sustaining, stable condition in perpetuity. The mine is regarded as a showcase on a world standard of how a modem mining operation can successfully coexist with the nearby community.

Jan 1, 2000

By Michael J. Beus, Stephen Iverson

BACKGROUND A mine shaft is the lifeline to underground mines. Mine operators depend on safe, uninterrupted, and efficient movement of workers and materials. The shaft and hoisting system provides access to the network of openings used to recover the underground resource, provides vertical transport of miners and materials, and serves as an escapeway in case of an emergency. Accidents involving hoisting can be catastrophic. Such was the case in 1973 at the Markham Colliery in Derbyshire, UK when the conveyance overwound and fell to the shaft bottom, resulting in 17 deaths. Hoist and elevator machinery must meet the requirements specified in the Code of Federal Regulations (CFR), Parts 57 and 75. According to the Mine Safety and Health Administration (MSHA) data, many shaft-related accidents in the United States are associated with the hoisting cycle. MSHA statistics show that there were about 1500 shaft- related accidents in the 5-year period between 1992-1996. Most of these accidents resulted from the action, motion, or failure of the hoisting equipment or mechanism and involved movement of the conveyance which includes cages, skips, ore buckets, and elevators. A hoisting hazard may be characterized as an "unsafe hoist operating condition caused by insufficient or inaccurate information available to the hoist operator" (authors' quote). Earlier investigators have defined safety features and operating and maintenance standards for hoists, and reported on monitoring and control systems and sensors for hoists and conveyances [Farley, 1983; Ward, 19931. However, despite the considerable technological progress and hoisting control improvements in recent years, safety- related issues that require further investigation still remain. The hoist operator must constantly be aware of two important hoist-operating conditions: the position of the conveyance and the tension in the hoist rope. If this information is not available or is inaccurate, the hoist becomes unsafe. Current technology provides this information indirectly from sensors and indicators in the hoist room. However, unlike a building elevator hoistway, mine shaft hoistway problems often include: 1. poor ground conditions and excessive shaft wall and guide displacement; 2. rock bursts in deep mines (resulting in large rock movements and fragments blocking the hoist way); 3. water, ice, and salt buildup (impeding the smooth flow of the conveyance); 4. severe vibration from hoisting (resulting in loose guide support brackets, broken welds, or other alignment and conveyance mechanism malfunctions). The second issue relates to dynamic rope loads applied during normal winding, particularly during loading, acceleration, and stopping. Safety factors on wire rope are based on static load. They are artificially high to account for all cases of dynamic loads, even though the total load history on the rope (static and dynamic) during service is unknown. Therefore the tension, and thus the compliance with wire rope load safety factors, is unknown to the hoistman.

By J. A. Herbst

In spite of potential theoretical and economic advantages of large-diameter ball mills, many manufacturers elect not to build these mills owing to what is perceived as an excessively large design risk. This risk results from the fact that traditional predictions for mill-scale-up to large diameters are not always accurate. It is apparent that alternative methods of analysis and scale-up are required. Recent studies have shown that detailed population balance models which account for important grinding subprocesses, i.e., grinding kinetics, material transport, and classification, are capable of predicting the performance of small- and intermediate diameter mills (up to 4.3 m (14 ft)) from small-scale batch tests. These same models are used in the current study to predict the performance of a "borderline" large ball mill (4.7x5.5 m) at Asarco's Sacaton operation, a ball mill (5.0x5.8 m) at Kennecott's Chino operation, and one of the world's largest ball mills (5.5x6.1 m), at Cities Service Pinto Valley operation. Model parameters required for scale-up have been estimated in a 380-mm diameter batch mill. Predictions are compared with the results of detailed plant sampling in the three plants. For the Sacaton and Chino operations, the error of the predictions was found to be less than 2.5%, while the corresponding error for the Pinto Valley operation was less than 2.7%. It is concluded that proper representation of the major subprocesses of grinding in the model equation is the key to achieving accurate scale-up. Of special importance is the need to account for the size distribution of the grinding media and the influence of the size distribution environment in the mill on grinding kinetics.

Jan 1, 1983

By George J. Skoronski

The economics of pellet plant operation, in terms of fuel and power consumption, flexibility in the selection of the cheapest fuel source, system availability, maintenance costs, and the simplicity of process design, contribute to the determination of building and profitably operating a pellet plant. Design innovations, sup- ported by actual field data, have been initiated into the GRATE-KILN System design to positively address these factors. This paper presents the recent state of the art design concepts which have helped the GRATE- KILN System assume worldwide acceptance status.

Jan 1, 1983

By Steven J. Page

Researchers have developed a model to describe airborne respirable dust (ARD) generation on surface coal mine drills. By measuring a few basic parameters and using a graph, a drill operator or engi­neer can estimate the relative severity of drill dust emissions as well as how much of a reduction in ARD can be obtained by changing any given parameter. Geometric parameters include: drill deck cross-sectional area, shroud leakage associated with the deck shroud as well as the operational parameters of bailing air­flow, and dust collector airflow. The rela­tionships yield predictive ARD values which fall in the range measured on oper­ating drills for collector/bailing air flow ratios greater than 2. Overexposure to airborne respirable crystalline silica dust can cause serious or fatal respiratory disease. Exposures of sur­face coal mine rock drillers to respirable crystalline silica are of particular concern. In a 1992 alert on silicosis in rock drillers, the National Institute for Occupational Safety and Health (NIOSH) reported on 23 cases of advanced silicosis (acute, acceler­ated, and chronic) ranging in ages from 25 to 60 with drilling tenures ranging between three and 20 years.1 Most of the cases involved drill operators in their 30?s and 40?s, indicating high silica exposure levels are associated with their occupation. A more recent lung x-ray surveillance study of a 664 volunteer population of surface coal miners showed that the prevalence of silicosis-like abnormalities was 9%.2 The two most significant factors associated with these abnormalities were increasing age and years of drilling experience.

Jan 1, 2008

By Robert M. Matyas, P. E. Sperry, Robert J. Smith, A. A. Mathews

INTRODUCTION The first Dispute Review Board (DRB) was utilized on a tunnel project 20 years ago. Increasingly utilized on a wide range of construction projects, DRB's are becoming the norm on tunnel and underground projects. This paper summarizes the growth in this usage, uses observations and experience to establish that barriers to the utilization of DRB's are more perceived than real and that many arguments against the DRB concept are not valid, and notes some of the salient elements that should be considered in practice to optimize DRB effectiveness. The purpose of the paper is to provide an annotated checklist for current and prospective users. The basic concept, structure, and operation of DRB's are described elsewhere and will not be repeated here (ASCE, 1991). DISPUTE REVIEW BOARD USAGE A compilation of Dispute Review Board usage for tunnel and underground projects to January 1994 indicated use on 63 contracts with a cumulative construction value of $3.8 billion and a total of 60 disputes settled. As of that same date, DRB's were planned for another 63 contracts with an estimated construction value of $4.7 billion. (A listing of these 126 projects is available from the authors.) This success and popularity have spread to other civil projects as well as process and building construction. The increase in DRB usage has been exponential. See Figure 1.

Jan 1, 1995

ENGINEERS AVAILABLE (Under this heading will be published notes sent to the Secretary of the Institute by members or other persons introduced by members.) Member, technical graduate, aged 36. Experienced copper metallurgist and mining geologist. Familiar also, through 15 years' broad practical experience, with mining, cyanidation, concentration (including oil flotation), metallurgical accounting, and mine and plant management. Best references. No. 237. Member, graduate engineer with 10 years' experience in malleable, gray -Iron, and steel, as chemist., metallographist, and metallurgist. Researches and investigations by laboratory methods and under works conditions. No objection to some routine. No. 243. Member, technical graduate, broad experience in coal, oil, and clay. Will go anywhere as mining geologist after Sept. 1, 1915. No. 244. Member, technical graduate, aged 30, married, with over 10 years' experience as chemist, engineer on construction, superintendent and general superintendent of bituminous coal and coke plants. SpeaksSpanish. References. No. 245. Member, open for engagement as mine safety inspector or as superintendent of bituminous coal mine. No. 246. Member, graduate mining engineer, with five years' experience in coal mining as mining engineer, construction engineer, pit boss, and superintendent, open for engagement. Best references. No. 247.

Jan 9, 1915

By Joan Weinberg

Real gross national product (GNP) grew at a seasonally adjusted annual rate of 2.2% in the third quarter, down from a revised 3.0% in the second quarter, according to preliminary data from the U.S. Department of Commerce (table 1). The slowdown in the rate of growth was attributed to the summer drought, a larger trade deficit, and a decline in Federal spending for defense. Exports slowed from the second quarter, as the dollar, compared with other industrial country currencies, edged up. Imports of both consumer goods and capital goods rose sharply, with consumers buying more foreign cars, computers, and electrical machinery. Although net exports of goods and services deteriorated slightly from the second quarter, the U.S. trade position continues to be much improved from 1987 and first quarter, 1988. Business spending for new plant and equipment rose at a 4.6% pace, well below that recorded earlier in the year. The 3.5% increase in consumer expenditure was accounted for mainly by nondurable goods and services; expenditure for durable goods--those products lasting more than 3 years--rose only 0.4%. Inflation, as measured by the fixed-weighted GNP price index, rose at an annual rate of 4.9% in the third quarter. Prices rose slightly less than they had in the second quarter, when inflation reached a 6-year high. In September, 1988, the President signed a U.S.-Canada free trade agreement (FTA) which will eliminate all tariffs and most nontariff barriers between the two countries by 1999, thereby creating the world's largest open market. In 1987, U.S.-Canadian bilateral trade totaled $161 billion. The expansion of trade is expected to generate 5% higher growth for Canada and up to 1 % higher growth for the United States by the end of the century. The higher growth for the United States translates into an estimated 750,000 jobs, and $2.4 billion in exports. Canadian parliamentary approval of the agreement is still required before the treaty can take effect. The debate in Parliament is continuing, and the issue is not expected to be resolved until after the November 21 election.

Jan 1, 1988

By D. G. Tisdale

A pilot plant was installed and operated at the Xstrata Nickel Sudbury Smelter 10 demonstrate the CANSOLV SO2 Scrubbing System. A 350 m3/h slipstream (through a 10cm pipe) was drawn from two different industrial gas streams to test the performance and robustness of the scrubbing system. The system achieved high sulphur capture, typically above 99%, and proved tolerant 10 varying gas strength and dust content in the feed gas.

Jan 1, 2009

By P. Sharma, J. C. W. Fowler

This paper discusses the wind blast / air blast phenomenon, how it is managed in coal mines and how it might best be managed in other underground mines. L'article qui suit a pour objets de décrire le phénomène de tir a l'air comprimé et les méthodes de modération de celui-ci dans les mines de houille, et d'indiquer de quelle manière il pourrait être surmonté dans d'autres mines souterraines. Dieses Seminararbeit diskutiert die Windexplosion / Luftexplosion Phänomen, wie es in Kohlenberg-werken geleitet wird, und wie es am besten in anderen untertage Bergwerken geleitet werden könnte.

Jan 1, 2003