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By CASSANDRA L. HOEBBEL, PATRICK L. YORIO, Emily J. Haas

This study revealed significantly less favorable perceptions of the existing organizational safety climate among workers in the underground coal-mining sector compared with those in the industrial-minerals and sand, stone and gravel (SSG) sectors. Consequently, it is important to consider pragmatic ways in which health and safety management systems (HSMS) in coal mines can alter processes to improve these perceptions. Given the interdependencies of safety climate factors and HSMS elements, researchers explored mineworker perceptions of the supportiveness of organizational safety climate factors among mineworkers and identified significant differences in perceptions across sectors. In this paper, we suggest that health and safety professionals in underground coal mining and organizations with fewer resources or less mature HSMSs focus on these factors to bolster support for proactive safety performance. Potential barriers to implementing or improving relevant HSMS elements and ideas to help foster more favorable perceptions of organizational safety climate are also discussed.

By James D. Piper

In the summer of 1957,9 the University of California sponsored a World Conference on Prestressed Concrete in San Francisco to which were invited a number of Soviet engineers. While attending the conference, these engineers in turn asked the University to form a delegation of American engineers to visit the Soviet Union the following year for the purpose of studying Soviet advances in concrete technology. A six man delegation was formed, and the dates of the Russian tour fixed for May 10th through May 21st, 1958. Before arriving in the Soviet Union, the American Delegation attended the Third International Congress on Prestressed Concrete in Berlin. While there, we noticed that the delegation from the U. S. S. R. used displays and showed motion pictures of many construction projects which we later were shown in Moscow. Our delegation left East Berlin by Russian aircraft on May 11th, and arrived in Moscow that afternoon. We were met by our Russian engineer hosts from The Academy of Construction' and Architecture who made all subsequent arrangements for our itinerary. This Academy has no counterpart in the United States. It. does 40 per cent of all engineering-and scientific work in the building construction field and coordinates 60 per cent of that done by other Soviet agencies. Due to the prestige of the Academy in Russian affairs, our delegation was able to obtain a surprisingly broad picture of construction activities in Moscow and Leningrad in just ten days time

Jan 1, 1960

By Y. D. Gao

A new technique has been developed for comprehensively recovering tantalum niobium tungsten ore by adoption of stage grinding, stage separation, combination of flotation and gravity separation, gravity separation for coarse particles, flotation for fine ones, combination of ore-dressing and hydrometallurgy. The new type and high efficiency combinative collector mainly composed of benzyl hydroxamic acid is firstly used to treat tantalum niobium and tungsten slime, besides the new type equipment for gravitational separation ?YTF-C shaking table for fine particles is adopted to treat flotation rough concentrate, hence having notably enhanced both recovery and concentrate grade of fine tantalum niobium and tungsten minerals. The commercial test obtains the tantalum concentrate assaying Ta2O5 31.98% with recovery 43.44% and tungsten product assaying WO3 89.40% with recovery 76.02%. The developed technique provides a reliable approach and an effective way for comprehensive utilization of lean fine complex refractory tantalum niobium tungsten ore resource.

Jan 1, 2014

By Bharat B. Dhar, M D. Nabinllah, A J. Prakash

The study is an approach made in simulating air overpressures induced by surface blasting from those produced during gallery blasting in the laboratory, and experiments conducted on a portable window with a view to establish the sound pressure Level (SPL) for cracking of window glasspanes.

Jan 1, 1994

By Gong-yi Guo, Yu-li Chen

"A partially-stabilized zirconia powder was prepared by metalorganic precipitation process from technical-grade zirconium oxychloride and the effluent of an acrylic acid plant. The effluent contained low molecular weight carboxylic acids, i. e., acrylic acid and acetic acid. The· developed process is based on the selective precipitation of acrylic acid at suitable pH values by the addition of zirconium oxychloride to the effluent. The resulting precipitate is a precursor that can yield a pure, ultrafine, and partially-stabilized zirconia powder. The evolution of formation of the partially-stabilized zirconia in the present process was investigated using thermal analysis, infrared spectroscopy, and X-ray diffraction technique. Environmental, technological and cost advantages will make the present process feasible for manufacturing advanced zirconia ceramics.IntroductionIn recent years the superior mechanical, thermal, electrical and chemical properties of stabilized zirconia have become the focus of growing scientific and technological interest, and hence resulted in various structural and functional applications. The great potential of the material has given rise to numerous preparation approaches to obtain the material with the excellent properties; nevertheless, an extensive number of programmes are underway worldwide aimed at understanding and improving both the preparation and behavior of stabilized zirconia ultrafine powders. (1 – 8)."

Jan 1, 2000

By AIME

DURING the Revolutionary War an iron mining industry was born in the Adirondack region of New York State. New York State ores provided the iron from which were forged the links of the chain that, strung across the Hudson River, successfully kept British vessels from ascending. The industry flourished for a while and then became dormant. For the successful prosecution of World War II, the magnetite mines were revived and given considerable aid in the form of government financial support. The complete story appeared in a special issue Of MINING AND METALLURGY published in November 1943. Now, almost four years later, it is interesting to see that these "war babies" were not really such but are well-established enterprises with a bright future. A ten-day trip through the Adirondack region and to St. Lawrence County dispelled all thoughts that mining in northern New York State is a transitory industry. In addition to substan-

Jan 1, 1947

By Emmanuel N. Zevgolis

In the present work, a reduction roasting experimental study of Greek nickeliferous laterite samples with a gaseous reducing mixture ? CO:N2- is presented. The effect of parameters such as temperature, ore grain size, and composition of the reducing mixture were examined. It is deduced that the reducibility of intermediate type laterite sample, where iron appears mainly in the form of goethite (a-FeOOH), is considerably higher than that of limonitic type laterite samples, where hematite (a-Fe2O3) is the predominant iron mineral phase. The degree of reduction of the limonitic type laterite samples does not exceed 50%, while it reaches 95% in the case of the intermediate-type laterite sample under the same experimental conditions. Increasing the temperature in the range 750-900°C does not considerably favor the reduction of the limonitic type laterites, whereas decrease of ore grain size of the limonitic-type ore samples and more intense reducing conditions increase the reduction. The considerably higher specific surface area values of the intermediate laterite samples, diminishes the effect of the ore grain size and this can be regarded as the critical parameter leading to the higher reducibility of this ore.

Jan 1, 2009

By Charles D. Wood

"Selected Topics,? in reviewing the control of emissions from diesel engine powered equipment used in underground mining, explores these fields of interest: hydrogen as fuel; lubricating oil as a source of particulates; applicability of stationary source scrubbers; worldwide diesel exhaust scrubbers; instrumentation technology for measurement of N02; control of emissions through application of sensors and microprocessors; use of fuel additives; technology transfer of marine diesel practice; technology required to use 4-stroke, aftercooled, turbocharged, direct injection engines; oxidation and reduction catalysts for diesel engine exhausts. "Selected Topics? makes recommendations for research and provides a bibliography and lists of references.

Jan 1, 1979

By Harry: Lobb Verakis

Mining operations have made tremendous strides in improving the safety of blasting as shown by the significant and continual decrease in fatalities and serious injuries. Advances in blasting technology and blasting practices have played a significant role in reducing fatalities and injuries. However, even with the decline of fatalities and injuries blast area security continues to be by far the leading factor in blasting accidents. Even though there continues to be an increase in the use of industrial explosives and blasting agents in the U.S.A., the decline in fatalities and injuries from blasting accidents has persisted.

Jan 1, 2010

By M. H. Pettibone

During the past decade, the size of grin- ding mills has steadily increased. Mills 11 m in diameter with 9 mW motors have been installed with even larger units on the drawing board. The rising costs of energy and labor have spurred interest in improving efficiency while reducing capital investment and operating labor. Autogenous and semiautogenous grinding have experienced renewed interest as efforts to reduce operating and capital costs have increased.

Jan 1, 1981

By Charles L. Guettel

The temperature coefficients of electrical resistance of 31 alloys in the nickel-rich corner of the Ni-Cr-Fe system were determined. The results indicate that a range of binary Ni-Cr alloys has lower temperature coefficients than a specific region of Ni-Cr-Fe alloys which has been reported and quoted by others as providing the lowest coefficients in the ternary system. DESIRABLE properties of resistivity and temperature coefficients of resistance have been the basis for the successful commercial application of various Ni-Cr and Ni-Cr-Fe alloys. In particular, low or negligible temperature coefficients of resistance are necessary for wire used in precision wire wound resistors and potentiometers involved in closely controlled electrical and electronic circuitry. Alloys most successfully applied to this purpose basically have not been ternary Ni-Cr-Fe alloys but rather heat-treated Ni-Cr alloys in the region of approximately 73 to 79 pct Ni and 20 pct Cr with significant additions of other elements such as aluminum, silicon, iron, copper, manganese, and cobalt. While the addition elements play a vital role in the nature and control of the temperature-resistance curve of any one of these alloys, the inherent relatively low temperature coefficient of the binary Ni-Cr base composition itself in the approximate region of 80 pct Ni and 20 pct Cr contributes fundamentally to the eventual negligible temperature coefficient obtained with the applied alloys. W. A. Dean 1 has reported mean temperature coefficients (20' to 100oC) of as-cast samples for the Ni-Cr-Fe system, the nickel corner of which is given in Fig. 1. Dean had to use as-cast samples because alloys from a considerable region of the system were unworkable. Dean refers to the work of Hunter and sebast2 who used annealed wire samples to show that, for chromium contents of 10 to 25 pct, the temperature coefficient increases as the iron content is increased at the expense of nickel. Although the data of Hunter and Sebast were limited in the nickel-rich areas to eight samples of 60 to 91 pct Ni with only four samples containing iron, the possibility that no Ni-Cr-Fe alloy has a lower temperature coefficient than certain binary Ni-Cr alloys should have been given serious consideration. However, Dean's work has been referred to by J. S. Marsh,3 who, quoting Dean, states that for the temperature coefficients "the smallest values-about 0.0001 per oC (100 ppm)—were found for alloys containing about 55 pct Ni and 20 pct Cr" (balance iron). A region such as that reported by Dean would be significant to those trying to develop alloys for the applications described. Therefore, a series of three-pound laboratory open-air induction melts of Ni-Cr and Ni-Cr-Fe alloys were melted, conventionally processed to 0.005 in. diam wire, and continuously strand annealed at 1900° F. The basic Ni-Cr compositions, with balances essentially iron other than usual minor impurities, and the corresponding temperature coefficients of resistance and resistivities are given in Table I. The resistivities are approximate and are not to be considered as a basis for relating them to their position of composition in the ternary system. The wire diameters were determined with a micrometer, and not by weight and density measurements which would be required for accurate resistivity values. However,

Jan 1, 1963

By A. Exikis

Simulating a ventilation network of an underground mine can help in solving complex ventilation systems with many features, selecting proper fan specifications, location and settings. Early computer systems running simple network simulations were able to provide solutions to the most common and immediate problems regarding underground mine airflow. The more advanced systems available today can perform more sophisticated modeling and simulation of a mine?s ventilation network and present their results in a more understandable and easy to communicate form. This paper presents a ventilation network case study from an underground mine. All aspects of mine ventilation network modeling and simulation are discussed as well as the results from the simulation process. The algorithms and techniques used are thoroughly explained. Some useful guidelines for the application of ventilation network software are also provided in the text.

Jan 1, 2006

By Mona M. Fawzy, Ahmed A. Eliwa, Ahmed H. Orabi, Amal E. Mubark, Ebrahim A. Gawad

During the last decades, the growing demand for rare earth elements (REEs) has led to numerous recent studies to recover these elements from various bearing ores and wastes. Therefore, the recovery of REEs from Ras Baroud polymetallic concentrate has been investigated in the current study. Physical beneficiation for the Ras Baroud pegmatite sample was carried out, yielding a concentrate for euxenite (Y), fergusonite (Y), xenotime (Y), monazite (Ce), allanite, thorite, uranothorite, and Hf-zircon, which resulted in raising the concentrations of rare earth elements, Th, Zr, U, and Ti in the sample. Fusion digestion processes with sodium hydroxide were studied using the Conceived Predictive Diagonal (CPD) technique. The three experimental digestion groups proved the dissolution of 99.9, 95.6, 99.9, 52.5, and 0.47% for REEs, Th, U, Ti, and Zr, respectively, under fusion conditions of 723 K, 120 min, 1/1.5 ore/alkali ratio, and − 100-μm particle sizes. Fusion kinetics, isotherms, and thermodynamics were investigated using several suggested models, namely, pseudo reversible first order, uptake general model, and shrinking core model which matched well with the experimental digestion results. Selective recovery of actinide content from REE content of the digested concentrate chloride solutions was accomplished using solvent extraction with di-2-ethyl hexyl phosphoric acid. About 99.9, 99.9, and 4.2% extraction efficiencies for Th, U, and REEs were performed, respectively, using 0.3 mol/L solvent concentration in kerosene as a diluent, 1/2 organic to aqueous ratio, an aqueous pH of 0.2, and 15-min contact time. Thorium and uranium ions were stripped with sulfuric acid solution 2.5 mol/L with 94 and 98% stripping efficiency, respectively. A highly purified REE precipitate was obtained from the raffinate solutions. Zircon mineralization tailings were obtained as a by-product through the alkaline digestion process.

May 4, 2024

By C. E. Lesher

THE Disco* process for the production of low temperature coke and its immediate predecessor, the Wisner or Carbocite process have been described in the voluminous literature of low temperature carbonization.1 This paper will describe the development of the process from the first attempt at commercial operation by the American Gas and Electric Co. at Philo, Ohio, Yn the 1920's to the successful operation in 1949 by the Disco Co., a division of the Pittsburgh Consolidation Coal Co., of the 1000-ton per day Disco plant near Pittsburgh, see Figs. 1-2. In the 1924 coal industry depression following the hectic post World War I expansion, the northern Appalachian, unionized bituminous coal fields were affected first and foremost, and Western Pennsylvania as hard as any. Competitive market pressure was heaviest on the lower grades of steam coals, notably the from the Panhandle district where ash and sulphur are inherently higher than in the same Pittsburgh coal bed to the east along the rivers. The firm structure of Panhandle coal while favoring the prepared sizes, depressed the usefulness and value of the finer sizes. Panhandle slack and nut slack were marketed with difficulty at consistent, and at times considerable, loss. Many solutions were suggested, and the Pittsburgh Coal Co. investigated all. Lower delivered prices through lower mine costs and more advantageous freight rates were obvious goals, but equally obvious were the difficulties of self attainment of either in any substantial measure. Selling Btu's in pipes was abandoned as an idea after a thorough study of the economics of distribution of what was then, and is even now, the only developed continuous process of complete gasification of bituminous coal-producer gas. Although the coal company purchased huge blocks of electric power, it sold not a car of coal to the central power stations. Public utilities controlled the markets for electric current, and it was found that no matter at how low a cost current might be put on the bus bars by the coal company, distribution to its widely scattered coal mines made such an enterprise practically impossible. Consolidation of underground operations and a huge modernization program of mining operations in the 1920's were but preparation for the introduction of mechanical cleaning of the coal for market, particularly the smaller sizes of steam, gas, and by-

Jan 1, 1953

By C. E. Lesher

THE Disco* process for the production of low temperature coke and its immediate predecessor, the Wisner or Carbocite process have been described in the voluminous literature of low temperature carbonization.1 This paper will describe the development of the process from the first attempt at commercial operation by the American Gas and Electric Co. at Philo, Ohio, Yn the 1920's to the successful operation in 1949 by the Disco Co., a division of the Pittsburgh Consolidation Coal Co., of the 1000-ton per day Disco plant near Pittsburgh, see Figs. 1-2. In the 1924 coal industry depression following the hectic post World War I expansion, the northern Appalachian, unionized bituminous coal fields were affected first and foremost, and Western Pennsylvania as hard as any. Competitive market pressure was heaviest on the lower grades of steam coals, notably the from the Panhandle district where ash and sulphur are inherently higher than in the same Pittsburgh coal bed to the east along the rivers. The firm structure of Panhandle coal while favoring the prepared sizes, depressed the usefulness and value of the finer sizes. Panhandle slack and nut slack were marketed with difficulty at consistent, and at times considerable, loss. Many solutions were suggested, and the Pittsburgh Coal Co. investigated all. Lower delivered prices through lower mine costs and more advantageous freight rates were obvious goals, but equally obvious were the difficulties of self attainment of either in any substantial measure. Selling Btu's in pipes was abandoned as an idea after a thorough study of the economics of distribution of what was then, and is even now, the only developed continuous process of complete gasification of bituminous coal-producer gas. Although the coal company purchased huge blocks of electric power, it sold not a car of coal to the central power stations. Public utilities controlled the markets for electric current, and it was found that no matter at how low a cost current might be put on the bus bars by the coal company, distribution to its widely scattered coal mines made such an enterprise practically impossible. Consolidation of underground operations and a huge modernization program of mining operations in the 1920's were but preparation for the introduction of mechanical cleaning of the coal for market, particularly the smaller sizes of steam, gas, and by-

Jan 1, 1953

By Peter Ryan

A patented process for agglomeration of Smelter ESP dusts is described. Addition of suitable binders followed by compaction, transforms fine, difficult to handle material into a dry, flowable agglomerate suitable for plant reentry. Details for the agglomeration process metallurgy and laboratory pilot plant testing are discussed. An example of full scale plant operations is described.

Jan 1, 1999

By N. A. Eilertsen, Rolf S. Paine

The Bureau of Mines studied the presplitting technique used for controlling overbreakage in the walls of a vertical shaft at the U.S. Army Corps of Engineers Littleville Dam project near Huntington, Mass. The periphery of the shaft, the dimensions of which were 16-1/2 feet wide by 21 feet long and 52 feet deep, was presplit (cracked) in the solid to a depth of 48 feet prior to full-depth sinking. Presplitting prevented overbreak in a fairly soft schist and provided sound self-supporting walls which required very little scaling.

Jan 1, 1965

By Carlos A. Jaramillo, Seng Hing Ngu

"The Murum Hydroelectric Project is a 944-MW development consisting of a 145 meter high RCC dam, two 2660 meter long, 9 meter excavated diameter upper pressure tunnels, surge shafts, two 950 meter long 7 even meter OD penstock tunnels and a surface powerhouse. The project is located in the eastern section of the State of Sarawak, Malaysia, about 200 kilometer from Bintulu, in the Rajang Fold-Thrust Belt, an Upper Cretaceous to Upper Eocene fold and thrust belt that extends under most of Sarawak. The Belaga Formation consists of a thick sequence of deep marine sediments currently appearing as steeply dipping strata of thin to thick bedded, fine to medium grained sandstone interbedded with argillaceous rocks, resulting on a “Flysch” type geologic environment. The project pressure tunnels were excavated perpendicularly to these strata resulting on frequent change on rock conditions and behavior, and required rock support. This paper describes the characterization of the rock mass, design of rock support, and incidents during construction. Particularly interesting were convergence issues in Tunnel 1 resulting from Tunnel 2 excavation. INTRODUCTION The Murum Hydroelectric Project is located in the eastern section of the State of Sarawak, Malaysia, about 200 kilometers from Bintulu, and upstream of the Bakun Hydroelectric Project. The project consists of a 145 meter high RCC dam, a 50 meter high intake tower, two nine meter OD and 2660 meter long upper pressure tunnels, two nine meter OD and 175 meter long vertical shafts, two 25 meter diameter and 80 meter deep surge tanks, two seven meter OD and 950 meter long penstock tunnels and four seven meter OD and 50 meter long branch tunnels, two 8 meter diameter to 3.4 meter diameter and 1400 meter long penstocks installed within the shafts, penstock tunnels and branch tunnels ending in a powerhouse with 944 MW installed capacity. LAYOUT OF THE WATERWAY TUNNELS The two waterways tunnels are basically parallel as shown in Figure 1, with each tunnel supplying water to two units in the powerhouse. The tunnels start separated 25 meters center to center, but 250 meter from the intake the separation increases to 35 meters. The tunnels are lined with reinforced concrete until they reach the surge shafts and steel lined from there to the powerhouse. The tunnel profile is shown in Figure 2."

Jan 1, 2016

By A. Delgado-Jimenez, O. J. Restrepo-Baena

"Sustainability is a concept that involves several aspects like social, economy and environment. For the concept of sustainable mining is an action that involves to do more in social acceptance, distribution of welfare, an stable economy and the environment. Understanding the mining operation that creates a new state that is necessary to prepare and conduct searching for the best results in sustainability. The results of sustainable mining could be directed to achieve less net environmental impacts, more economic development through the transformation of the natural capital and the social acceptance as the result of good negotiations with the communities in the surroundings. To do that, one option is to create frameworks to planning the regional mining developments that allows the stakeholders to decide and develop different strategies to addresses the sustainability in a mining environment. Strategies based on the understanding of the whole mining business, the environment in which it operates, composed for a natural resources network that interact in a complex system, social system composed by different groups, communities and economies that could be subject to big transformations. INTRODUCTION The mining sector represents one of the most significant challenges for sustainable development, given the magnitude of the impacts that it has on the social and natural systems and the potential to generate welfare associated with its exploitation. Some of the main challenges of mining to contribute to sustainable development are the reduction of the environmental and social impacts of mining operations, to advance in the distribution of benefits in the community and the investing in the development of substitutes. To help in this direction it is necessary to integrate more actors than those who have been considered traditionally in the development of the mining business, and consider the natural environment, communities and the several dynamics generated by the interaction of these elements that contribute to sustainable development. This work provides some useful considerations for sustainable development of mining operations in regions with mining vocation, through the convergence of objectives and the finding of synergies between the existing conditions in the territories and the potential conditions that are generated by new mining developments. A DEFINITION FOR SUSTAINABILITY IN MINING The definition of the Brundtland Commission in 1987 established that sustainable development is ""the ability to ensure that it meets the needs of the present generations without compromising the ability of future generations to meet their own needs""."

Jan 1, 2015

By L. J. M. Smits

A theoretical equation is developed describing membrane potentials of shaly sands as a function of the cation-exchange capacity per unit pore volume of the rock and saturating water salinity. This equation is based on the same simple physical model as that employed earlier7 describing the electrical conductivity of shaly sands. Experiments conducted with NaCl solutions showed that the equation is obeyed, except in the case of saturated salt solutions where minor deviations were observed. A possible explanation is given for this discrepancy. As the clay content and the porosity of shales may vary appreciably, shale membrane potentials also vary. It was found that membrane potentials of shales can be calculated accurately with the aid of the same theory. Consequently, changes in membrane potentials can be accounted for by simple measurement of cation-exchange capacities per unit pore volume of both shales and shaly sands. Charts are given to facilitate interpretation of the electrochemical part of the SP in terms of cation-exchange capacities and the salinities of mud filtrate and formation water. INTRODUCTION A spontaneous potential (SP) log is a record of the way in which the electrical potential of a sonde varies as it passes down a borehole. Such variations frequently reflect rock texture, e.g., permeable beds intercalated in an impermeable series often are indicated by a sharp change in potential. Nowadays it is recognized that SP logs may be interpreted in terms of formation-water salinity and formation shaliness. The four sources of the SP are illustrated in Fig. 1. El and E4 represent streaming potentials generated by the flow of mud filtrate through mud cake opposite permeable formations and through shale, respectively. An extensive review of the literature on the evaluation of these streaming potentials is given by Lynchl and will not be discussed here. The remaining part of the SP generally is called the electrochemical potential, which is divided into two parts: a membrane potential across the shale (E3, Fig. 1) and a membrane potential in the permeable sand at the diffusion boundary between formation water and mud filtrate (E2, Fig. 1). It was found by wyllie2 that the membrane potential across the shale, E3, is the most important contribution to the electrochemical potential, the shale acting as a semi permeable membrane. When the sand is clean it does not influence the diffusion process, so E2 equals the value of the so-called liquid-liquid junction potential observed when the two solutions diffuse freely into each other. When the sand contains clay, however, this interferes with the diffusion process and affects the diffusion potential generated. The greater the proportion of clay, the stronger this effect will be. Wyllie,3 Doll4 and Poupon et al.5 took this effect into account theoretically, starting from a physical

Jan 1, 1969