Search Documents

Not quite a year ago, during a speech to a group of mining professionals in Washington, DC, the subject centered around the long-range importance of conducting research projects and how much that research needs to specifically apply to health and safety matters in our industry. The point was made about the critical need to work together with government, private industry, labor organizations and academia speaking with a unified voice as we all march into the future together. The fundamental benefits of competitive research were mentioned --to improve our quality of life, to develop our energy resources, to achieve a safe and healthy environment and to ensure long-term economic growth. Very importantly, emphasis was given to the natural link that makes my agency, the Mine Safety and Health Administration, and the National Institute for Occupational Safety and Health --NIOSH --the beneficiaries of each other's findings. Unquestionably, there are lines of separation. The main responsibility of the agency I represent, MSHA, is enforcement of the nation's mine safety and health laws. But we also have an additional responsibility and that is to coordinate and give priority to research in a never-ending hunt for answers.

Jan 1, 1999

By Nobuharu Isago, Atsushi Kusaka, Kosuke Kawata

"Rock tunnels suffered severe damage from recent large earthquakes in Japan, despite the empirical knowledge that tunnels tolerate earthquakes better than surface structures. Seismic design for rock tunnels have therefore become a fascinating subject for many tunnel engineers. However, even basic behavior, including deformation mode and loading magnitude for hard-rock TBM tunnels and conventional ones during earthquake, has not been fully understood due to lack of actual seismic data; while EPB and slurry TBM tunnels take account of seismic design in Japan if needed. This study conducted a dynamic measurement in an actual road tunnel constructed in rock. The strongest aftershock of “the 2011 off the Pacific coast of Tohoku Earthquake” (Mw = 7.1) occurred during the measurement, providing precious data to examine deformation mode of the tunnel. Considering the acquired data, numerical analysis was also performed to calculate loading magnitude to cause fatal fracture of tunnel lining during earthquake.INTRODUCTIONLarge earthquakes can pose serious risks even for rock tunnels, as evidenced by large earthquakes in the past. In the large earthquake in Japan in 2004 (Mw = 6.6), some tunnels suffered severe damage including collapse of their permanent lining (Mashimo 2005), even though the tunnels were constructed in ordinary ground conditions except for fault, fracture zone, portal area, etc. To mitigate such risks, mechanical behavior of tunnel lining during earthquake should be clarified; however, even basic mechanical behavior including load-bearing capacity of the tunnel lining against earthquake is not fully understood.Numerous damage modes were actually observed due to various ground conditions (eg. Wang et al. 2001; Mashimo 2005). Among them, major tunnel damage caused by earthquakes can be grouped into three main modes as shown in Figure 1, excluding extremely unusual conditions such as a tunnel located on a stratum boundary where the stratum stiffness varies significantly. TYPE-I shows flexural failure or crack by bending moment at shoulders; TYPE-II indicates compression failure or flexural compression failure at crown; and TYPE-III illustrates compression failure at sidewall, mainly observed on tunnel that was constructed using steel ribs and lagging method. These damage modes, Type-I, II and III, are predominantly caused by shearing, horizontal compressing and vertical compressing deformations of the surrounding ground, respectively (Kusaka et al. 2011; Asakura et al. 2001)."

Jan 1, 2016

By Kirk Carlton

The Athabasca tar sands of Alberta are an increasingly important source of crude oil for the North American continent. Published figures indicate estimates of recoverable resources in the tar sands at some 300 billion barrels of synthetic crude of which some 86 billion barrels can be recovered by surface mining techniques. At the present time, two commercial plants are in operation, Great Canadian Oil Sands Limited and Syncrude Canada Ltd. Their present combined capacity is approximately 150,000 barrels per day. Some of the factors which will make this oil expensive will be noted here. The location of the present producing plants is 500 kilometres north of Edmonton at an elevation of approximately 320 metres. Recorded temperatures range from +38 to -55 degrees Celsius. Wind velocities are not high but the chill factor with even a slight breeze and minus 40 degrees is very uncomfortable.

Jan 1, 1979

By Timothy J. Matthews, Ted Klemetti, Timothy J. Batchler, Daniel J. McElhinney

Unplanned tailgate collapses and difficult mining conditions in U.S. longwalls have necessitated the use of innovative tailgate support systems. Severe ground movement induced by longwall loading has caused operators to utilize secondary support systems that can match yield and strength requirements with expected ground reactions. Standing support performance requirements depend on the nature of the ground deformation behavior, and therefore require a good understanding of the interaction between the support and ground to achieve an optimum roof support system. Mining operations often employ standing support strategies that are unique to their mine. A support system that functions successfully in one situation could fail in another situation. It is important that the design and installation of the standing support systems provide the highest probability of preventing roof falls. Pumpable roof supports are currently being used to provide a safe working environment for longwall mining. A full understanding of the impact of these performance characteristics is necessary to optimize the support application and to provide a foundation for making further improvements in the support performance. Optimization of roof support applications helps to ensure the protection of mine workers by preventing roof falls due to inadequate support design. The load capacity and stiffness characteristics of a 27-in.-diameter pumpable support system was evaluated using the National Institute of Occupational Safety and Health (NIOSH) Mine Roof Simulator (MRS). Previously, tests to evaluate the performance characteristics were performed on a single pumpable support. The goal of this new research is to evaluate the performance characteristic effects of the pumpable support system and compare it to an individual pumpable test examination. This research of a pumpable support system configuration simulates the current installation practices in U.S. coal mines.

Jul 1, 2023

By S. Partney

Waste clay ponds are a necessary part of the phosphate rock beneficiation process. They are large, averaging a square mile in size; unsightly, in that they protrude 20 to 50 feet (6 -15 meters) above natural grade; stabilization and reclamation is slow; and they have had a history of catastrophic failure. The State of Florida has never published a specific rule regarding the configuration or height of these ponds, but has enforced numerous policies along these lines. The current rules are given and interpreted, along with the reasoning for current policy. In addition, an overview of the history of the policies, and an attempt at explaining the reasons for the changes that have occurred is given. The industry has been forced to make major monetary decisions, having effect for decades on mine economics, in a constantly changing regulatory environment. The Bureau of Mine Reclamation is confident that a direction of regulation has been solidified, but changes are still to be anticipated.

Jan 1, 1998

By Hayward B. Oblad, Anthony G. Fonseca

Coal flotation has been practiced since about 1920 in Europe and since about 1926 in the U.S. Over 200 U.S. coal preparation plants now use the process to recover coal. Over the 60 year period, the fundamental principles upon which flotation is based have been enumerated, but the interaction between the parameters that affect flotation has not been quantified and a useful model which accounts for these parameters has not yet been developed. A comprehensive and user friendly kinetic model coupled with better process monitoring and control instrumentation would allow plant operating personnel to better predict flotation performance and better control the flotation process in coal preparation plants.

Jan 1, 1989

By W. H. Langer

Around the beginning of the 20th Century, annual aggregate production in the United States amounted to about 50 million short tons. Today annual aggregate production is nearly 2.5 billion tons. Over a third of the States in the country produce more aggregate than the Nation did at the turn of the century. I would like to describe some of the historical events that allowed this nearly 50 fold increase in aggregate production. You might wonder why I want to talk about history. Some of our best ideas lie buried in the past, waiting to be rediscovered in the present. Almost every issue that the aggregate industry experiences today has been recognized for at least a decade; many of those issues have been recognized for a half a century; and a few of them have been recognized for nearly a century. The main reason for this article is to save the past from the forgetful indifference of the present-to faithfully preserve the past, to illustrate the insights of our predecessors, and to demonstrate how little of what we know today is really new.

Jan 1, 1998

By Erland A. Tillman

The U.S. National Committee on Tunneling Technology under the aegis of the National Academy of Sciences has long recognized that productivity in major underground construction projects could be increased through better contracting practices and better management. Between 1974 and 1978, this Committee has prepared three reports on these subjects. This paper reviews these reports and their recommendations. It covers the extensive actions by the U.S. National Committee on Tunneling Technology to bring the recommendations to the attention of leaders in the underground construction industry and thus further their adoption and implementation. These activities are continuing. Visibility in this session will give these reports and recommendations increased exposure.

Jan 1, 1981

By D. J. Shields

The Sustainable Minerals Roundtable was established in 1999 to develop a set of national level indicators to measure the contributions of mineral and energy systems to sustainable development in the USA. The U.S. Forest Service and the U.S. Geological Survey are sponsors of the Sustainable Minerals Roundtable, with meetings convened by the University of Nevada, Reno. Eighteen meetings have been held in various regions of the United States to receive input from different communities of interest. Indicators are being prepared under four criteria: legal and institutional, productive capacity, environmental impact, and socio-economic. This paper reviews the process followed by the Sustainable Minerals Roundtable, and presents the priority indicators.

Jan 1, 2003

By Duluth Engineers' Club, Engineers' Club of Northern Minnesota

"The early mining of iron ore in Minnesota was carried on with the most primitive kind of tools. The pioneers used only such equipment as could be packed from Duluth through one hundred miles of forest to the first mines on the Vermilion Range and the operations were carried on with picks, shovels, hand drills and wheelbarrows, the ore being hoisted in buckets with a horse winch and carted in horse drawn wagons to the stockpile. This was about the extent of the mechanical equipment of the Minnesota iron mines in the early eighties.As soon as a railroad was pushed through from Two Harbors to the Vermilion Range the equipment began to be improved upon; wood burning steam boilers were installed and small steam puffers displaced the horse-winches, wheelbarrows were aban¬doned and small cars were introduced. Hauling the hoisted ore in wagons was discontinued and trestles were built so that the ore could be stockpiled more cheaply through the use of cars and high piles. These same stockpiles were loaded by hand into the 10 and 15 ton capacity railroad ore cars.Within a few years a marked change took place—the hand drill gave place to the air drill, such as No. 3 Rands, Ingersolls, Sargents and some Sullivans. Tramming was done by mules, the ore hoisted in. self-dumping skips, hoisting engines were intro¬duced and it seemed as though mining as a business in Minnesota had come to stay. At this stage someone conceived the idea of making the stockpile floor about three feet above the top of the ore cars to facilitate the hand loading of stockpile ore for trans¬portation. This was done through the use of wheelbarrows at first and later by using I-ton cars running on tracks laid on the stockpile floor."

Jan 1, 1920

By Williams R. Reynolds

Studies of the northeastern Mississippi bauxites were initiated primarily for the purpose of ascertaining the quality and quantity of the ore. Subsequently, this ore was found to have a rather dubious economic value as was previously suspected but never established in earlier economic reports (1, 2, 3). However, the quality of ore was found to be higher than previously thought. Even though the ore bodies were determined during the early stages of this study to be too thin, small and widespread for commercial production a continuation of the study was not abandoned. On the contrary, the present investigation was intensified concentrating less on the economic application and more on stratigraphy and genesis. Considering the ever increasing demand for aluminum products the northeastern Mississippi bauxite district which includes portions of Tippah, Benton, Pontotoc, and Union Counties may soon become, in spite of inferior quantities of ore, an attractive area for bauxite production. Presently, however, the meager quantity of ore discourages exploitation. On the other hand, these northeastern district bauxites are facies of more extensive units of lignite bearing high aluminum clays, and considering the advances in aluminum extraction from clay these clays may in the future beckon mining interest. The bauxite of the northeastern Mississippi district, mapped as a part of the Betheden Formation (4). has an outcrop trend along the county lines of Tippah and Benton Counties and the extreme western portion of Union and Pontotoc Counties. Studies of exposures and cores stratigraphically positions the outcrop between the middle Midway Porters Creek Clay and the lower Eocene Wilcox sands and

Jan 1, 1977

By William Kohan

The industrial grinding process has undergone changes to better address the market and economic needs. Fine grinding of dry materials has developed to the point where classifying linings and fine ball charges improve mill efficiencies. Roller mills as well have wide acceptance due to their power efficiencies. The mill, by its nature, cannot provide the specific particle size or range of sizes which are required for further processing or final use. Therefore, various separators are operated in conjunction with the mill to control particle size. The sizing device helps minimize over grinding and control top size. Rising energy costs combined with increasingly tighter quality specifications have led to increasing study of the grinding and separation process.

Jan 1, 1985

By Weiguo Xie, MARK LAPUTKA

The pyrometallurgical industry plays a vital role in producing metals for our modern life. With growing demand for metals and declining grade of mineable ore, innovations become critical for many mining companies. This has given rise to the need for a review of recent improvements to the pyrometallurgical industry in terms of analytical measurement techniques, process and equipment improvements, and computer-based modeling/simulations. Because many of these innovations tend to be applied to a wider scope of metals, not restricted to a specific metal, we studied the broad applications of many improvements to a wide range of metals. We found that the challenge of a lack of robust measurement techniques under high-temperature conditions within a furnace hinders optimization of a pyrometallurgical process. Some future opportunities in the pyrometallurgical industry on analytical measurement techniques, computer modeling, and processes and equipment were also outlined and discussed.

By Simon D. Strauss

The recession that began in late 1980 has proved to be not only prolonged and severe, but in certain ways unique in its effect on the mineral industries among the periods of economic slowdown experienced in the Western world since the end of World War II. This time almost all minerals have been affected. In previous business turndowns, by contrast, some mineral sectors have with-stood economic adversity well. They experienced little or no adverse effect-thanks either to a strong secular expansion in the markets for their particular product or to specific factors that caused demand to be well maintained. For example, aluminum, molybdenum, and nickel are three metals that enjoyed extraordinary growth in applications during the years 1946-1973. These metals were little affected during the recessions that occurred in that era. Similarly, coal did not suffer a pronounced drop in sales in the 1974-75 turndown because, with the price of oil rising sharply, a switch away from oil and back to coal was clearly indicated for some energy-intensive applications. Oil itself was largely impervious to the ups and downs of the business cycle until very recently. And the precious metals, gold and silver, have often been regarded as benefiting from reduced economic activity because labor becomes more available, productivity rises, and operating costs diminish. In the current recession, however, no major mineral has escaped the broad trend. The secular growth factors that were previously so evident for aluminum, molybdenum, and nickel have disappeared, at least temporarily. The stable pricing behavior that previously characterized all three of these commodities has been replaced by extreme price weakness and apparent inability of the major producers to continue their roles as market leaders. Coal and oil both have suffered from a sharp drop in energy requirements. There are those who now anticipate a collapse of the market control over oil prices so clearly exercised by OPEC since 1973. If oil prices are no longer effectively controlled by the governments of the exporting countries, then coal prices are also certain to be affected. And the combination of high interest rates, tight money, and a change in public perceptions of precious metals put the skid under gold and silver quotations in 1981 and early 1982. Although inflation has been viewed as the scourge of most Western countries ever since the oil crises of 1973-74, prices-in constant dollars-of most minerals have not risen. On the contrary, with the exception of the precious metals and oil, for most minerals the prices that prevailed at the end of 1982 were close to the levels of the Great Depression of the 1930s in constant dollar terms. Table 1 compares prices for copper, lead, zinc, and aluminum at the end of 1982 with the average prices in 1934, stated in constant 1967 dollars. This emphasis on prices for mineral commodities reflects the fact that profits of mining enterprises vary directly with the level of prices. Manufacturing and retailing enterprises march to a different tune. They establish sales prices based on costs. Their profits tend to vary with volume. Commodities are for all practical purposes fungible, that is the advantages of known brands in marketing manufactured goods have little application in a commodity market. Thus the individual seller of minerals is unable to establish his sales prices. Except where a monopoly is present, he must sell at the going market. His option is to abstain from selling if he finds the price unremunerative. In past recessions, some mineral producers chose to do precisely that-either accumulating a substantial share of their output in inventory or, in prolonged downturns, abstaining from production. During the current recession, however, private-sector mining companies did not have the option of accumulating inventories to any great extent. Capital costs for new mineral projects or for expansion of existing facilities have escalated at an alarming rate since the early 1970s. Added to this has been the heavy cost of installing pollution control or safety equipment to comply with the regulations adopted in most industrialized countries (and particularly the United States) since 1968. The consequence has been that the financial position of most major mineral enterprises in mid-1980 was already strained. To finance increased inventories meant incurring additional funded debt at high interest costs, thus impairing the concern's credit rating. Management Choices Private-sector managements have had to face up to the alternative of either continuing to produce at an unchanged rate and marketing output at unremunerative prices or reducing output. The latter has meant either operating at a curtailed rate, with con-

Jan 3, 1983

By T. Mudder

The objectives for closure of a hard rock mine include minimizing long term environmental liability, attaining regulatory compliance, and maintaining geotechnical stability, while closing as cost-effectively as possible. Proper planning for closure should come during the feasibility study, design and permitting phases, and during operations as updates. The lack of a proper or updated closure plan can result in severe environmental and economic consequences. Effective mine closure is the result of a combination of innovative concepts, long-term commitments, and multi-party cooperation. The purpose of this paper is to discuss concepts, commitments, and cooperation as they relate to an effective closure plan.

Jan 1, 1999

By Franc Runovc

The service hoisting plant in the mining transportation is an installation serving for the vertical transport of material and persons. An adequate mathematical model is presented for simple evaluation of the project parameters where different plant designs and the ways of transport are take into consideration. The technical and economical optimization procedure is added to the basic mathematical model of the project. This approach enables on one hand the optimization of the reconstruction of the multi-purpose hoisting plants in order to suppress possible bottle necks, while on the other hand it enables the determination of such values of the parameters of the choice and of the operation that the sum of total expenses per a transport unit' becomes the lowest. The optimization procedure is designed in such a way that all numerical data of the optimum hoisting plant are printed out together with the graphical representation of dependencies of the fundamental parameters in broader optimization region.

Jan 1, 1992

By Wescomb R. Jones

The United States is the world's largest producer of hydrofluoric acid (HF), with its 1971 output of 317,000 short tons representing about 40 percent of the estimated Free World production. U. S. production has increased over five fold in the past 20 years, with a growth rate of about 7 percent per year between 1960 and 1970. However, the growth rate to 1977 is expected to be less than 5 percent per year, due primarily to a reduced rate of growth in requirements by the aluminum industry and an expected increase in imports from Canada and Mexico. This discussion will include our analyses of the consumption pattern for HF in 1972 and the factors influencing the demand forecast for 1977.

Jan 1, 1973

By T. Reed Scollon

Before we can attempt to answer the question of what can be expected from coal research, let us examine why research is done in other fields and what others expect for the money they spend on research and development. Up to 1900 almost all organized research was carried out at universities. Most of the support came from the university, and by present standards the amount of research was extremely small. The motivation for university research was basically discovery of new phenomena, with the objective of advancing knowledge. Side by, side with this organized effort was that of individual inventors who were primarily responsible for applying this new-found knowledge to useful purposes. During this period inventors were rarely supported by anyone, and experimentation was carried out either in their spare time or at the expense of earning a living. Men like Edison, I believe, were the first to demonstrate on a large scale that one could systematically apply newly discovered scientific principles to inventions that would serve useful purposes and would return a profit to those engaged in the effort. The tremendous expansion in research therefore began with the realization and demonstration that the scientific discovered could be applied in such a way as to return a' handsome profit to those who invested in it. The motivation of many of the research personnel however, remained the satisfaction associated with new discoveries, The money to support their efforts came from those interested in a return on their investments. Since the First World War and a rapidly accelerating rate since the Second World War another important motive for supporting research has appeared--the needs associated with national defense; this type of research has been supported almost exclusively by the Government.

Jan 1, 1959

By Theodore H. Eyde

In the southwest porphyry copper province, the virgin prospect with good copper mineralization cropping out has disappeared. Future discoveries will require an increasingly sophisticated arsenal of exploration techniques and concepts. One of the latter, stratigraphic analysis, is a technique which is often overlooked. A surprising number of exploration geologists still think of porphyry copper deposits as occurring wholly within intrusive bodies such as quartz monzonite or granodiorite. Disseminated copper mineralization, though genetically related to intrusive rocks, can occur within both the intrusive and the intruded rocks. At present, as much as 30% of the total copper produced from disseminated copper deposits in the Southwest originate from the intruded rocks rather than the intrusive. George M. Schwartz, in "Geology of the Porphyry Copper Deposits of Southwestern North America" points out that the host rocks at porphyry copper deposits include such diverse rock types as diabase, granite, limestone, dolomite, quartzite, skern, sericite schista, and others in addition to the more common monzonite, quartz-monzonite, and diorite porphyrys. Therefore, a porphyry copper can be defined as a disseminated copper deposit occurring either in or adjacent to a granitic-monzonitic-dioritic intrusive which can be exploited using bulk. mining techniques. The original definition of porphyry was originally applied to the early producers, such as Inspiration, Bingham, and Ajo, in which the copper mineralization occurred principally within the intrusive. A review of the geologic literature describing the porphyry geologic

Jan 1, 1971

By A. M. Raichur

The selective adhesion of hydrophobic Mycobacterium phlei to coal particles is responsible for flocculation of fine coal from associated ash forming minerals. The driving force for the differential adhesion is the hydrophobic interactions between the fatty acid surface of the organism and hydrophobic nature of coal. The effect of Mycobacterium phlei on surface hydrophobicity, surface charge and mechanism of adhesion on coal and associated minerals are controlled by several factors including hydrophobicity and surface and solution chemistry of the system. Adhesion measurements indicate that maximum adhesion occurs below the isoelectric point (IEP) of the coal particles. While massive adhesion of Mycobacterium phlei is observed on coal, however, negligible amount of Mycobacterium phlei attaches to mineral pyrite and quartz.

Jan 1, 1995