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By R. B. Krog

As part of its mining health and safety research program, the National Institute for Occupational Safety and Health (NIOSH) conducted a longwall methane emission and mining time study at a mine operating in the Pittsburgh Coalbed to access the methane emission consequences of mining a longer face. The methane emission contributors from the mining of a longwall face are: 1) gas released from the coal broken by the shearer, 2) gas emitted from the coal on the face conveyor, 3) gas emitted from the coal transported on the belt, and 4) background gas emitted from the coal face and from the adjoining ribs. Based on the results of the study, a set of site-specific mathematical formulas and constants were developed to characterize each of the four longwall emission contributors. The mathematical formulas were then applied to longer longwall face mining scenarios to predict the methane emissions from these faces.

Jan 1, 2006

By S. Narra, M. Nelles, I. Eickhoff, S. Teitge

"The aim of the research is to develop a holistic process flow for the recycling of glass fibres from glass reinforced plastics (GRP) and carbon fibres from carbon fibre reinforced plastics (CFRP), wherein the dissolution of the fibre epoxy resin matrix, separation of fibre fractions and their renewed material use is intended. In clear distinction to the previous research and development projects, the aim here is to recycle complex composite structures such as dismantled/disused wind turbine rotor blades and end-of-life composite wastes. In the course of the study, mechanical, hydrothermal and thermal processes and their combined procedures will be developed. As the fibre length is a decisive quality criterion in the recycling of composite materials, the further focus of the study will be the development of upstream and downstream material processing, in which the fibres are retained in their original form. The evaluation of the recycled fibres obtained is based on the elemental composition, measurement and morphological evaluation of individual filaments by scanning electron microscope (SEM), micro tensile tests on single fibres and their comparison to virgin fibres. The resulting process water is analysed by gas chromatography and mass spectroscopy (GC-MS) and a potential recirculation is determined. In cooperation with companies from the composite processing industry as well as recycling companies, a return of the recycled fibres to the known manufacturing process will be examined and an energetic and economic evaluation of the overall process will be carried out. Ambitious aim of the study is to achieve an actual recycling instead of the present downcycling or the energetic utilization. INTRODUCTION As global warming increases, so does the awareness of consumption and production of energy. To counteract the effects of global warming, renewable energy has been increasingly used during the last two decades, not only in Germany, but worldwide. Both, hydropower and wind energy, hereby play a fundamental role. After the end of their useful life of 20 to 30 years, the wind turbines (WTs) are being dismantled. Due to their foundations and tower segments, their recycling rate hereby exceeds 90% by mass. So far, the resulting rotor blade waste played a minor role accounting for only 2 - 3 weight-% of the total plant. Rotor blades of modern wind turbines are made of glass and carbon fibers, which are embedded in an epoxy or polyester resin matrix, balsa wood, PU or PET foams as fillers as well as various paints and coatings. These wastes currently end up in waste incineration or are sold to non-European countries."

Jan 1, 2018

By Paul S. Goodman

This report examines the feasibility of Employee Assistance Plans for the coal industry. Three issues are examined in detail. First, the prevalence of off-the-job factors such as alcoholism, drug abuse, and marital problems are examined in a sample of miners from the eastern, midwestern, and western underground coal fields. Then data were presented that examined the link between these off-the-job factors and behaviors critical to the mines such as absenteeism and turnover. Lastly, we examined the effectiveness of the major Employee Assistance Program in underground coal mining--the HELP Program. The report contains recommendations on whether coal mining companies should implement these programs and how these programs should be designed.

Jan 1, 1986

By C. H. Larsen

A 9-month study of the uses of wire rope associated with U. S. underground coal mining is reported. Rope applications are broken down into hoisting and nonhoisting applications where "hoisting" refers to transport in vertical and inclined shafts. The former receives the greatest emphasis since it represents the most critical rope application from the stand-point of production and safety. The discussion of hoisting practice includes aspects related to the mine operators as well as those related to the equipment builders and wire rope manufacturers. U. S. state and Federal laws regulating hoisting and wire rope use are also presented and discussed. Canadian and other foreign hoisting practice and laws are included. The state of the art in electromagnetic nondestructive inspection of hoist ropes is presented. Capabilities and use of one Canadian electromagnetic device are discussed in great detail. Conclusions are drawn regarding the present state of wire rope and hoisting technology in U. S. coal mines. Recommendations are made for improving rope practice, in general, and hoisting, in particular, consistent with greater safety.

Jan 1, 1971

By H. C. Fuller, E. L. Anderson, F. S. Wartman, M. A. Cook

"This paper gives an account of the production of ductile-grade titanium powder in 100-pound batches by reduction of purified titanic chloride with magnesium, followed by grinding, leaching, and magnetic separation of the reaction product. Apparatus, technique, and methods of controlling product quality are described, and some data on operating costs are given.Although man has been aware of the existence of the element titanium for over 150 years, only recently has the metal itself been available in a form pure enough, particularly with reference to absorbed gases, to allow an estimate of its physical properties. In comparison with mild steel, the tensile strength of titanium is about the same, the resistance to atmospheric corrosion greater, and the specific gravity much less.These properties suggest the usefulness of titanium as a structural material for applications requiring resistance to atmospheric attack and a good strength-weight ratio. Although known reserves of titanium, high-grade enough to be useful at present are not sufficiently extensive to predicate that titanium might supplant iron, aluminum, and magnesium for structural purposes, the reserves are large enough to make its use as a structural material quite feasible in certain fields in which its unique properties are required.As a result of these considerations, the Bureau of Mines station at Tucson initiated an, investigation into the technology of titanium in 1938. First, a critical survey and small-scale trial of virtually all suggested methods7/ for producing the metal was made. The method devised by Kroll8/ seemed best adapted as a source of metallic titanium for, although the purity of the product was not as high as that of products from some other processes, it seemed that modifications in technique necessary for larger-scale production could be made more easily.Essentially, in applying the Kroll process, titanium tetrachloride was reduced to metallic titanium by adding the chloride slowly to molten magnesium contained in a molybdenum-lined iron reaction chamber filled with a protective atmosphere of argon. After reduction to the state of completion desired, the reduction mass and chamber were allowed to cool. Then the chamber was opened, and the reaction mass, consisting of titanium, magnesium chloride, and some unused magnesium, was removed by suitable means. Most of the magnesium chloride and metallic magnesium were removed by leaching in dilute hydrochloric acid. The leached sponge was then ground wet in a ball mill, releached in strong acid, and dried Removal of free iron by magnetic separation completed the production process.Development of the Kroll process by the Bureau was undertaken first at the station at Salt Lake City, in 1942 and the amount formed per run was increased in several steps from a few grams to pounds.9/ In addition to increasing the size of batch over that used by Kroll, the technique was simplified somewhat by the use of unlined reaction vessels."

Aug 1, 1949

By J. Sikamo, A. Mwanza, C. Mweemba

"The Zambian copper mining industry as we know it today had its genesis in the 1920s. Consistent private sector-driven investment in the industry over a period of over 50 years in exploration, mine development and operation, development of minerals processing facilities, building of infrastructure for pyrometallurgical and hydrometallurgical processing, with attendant support facilities, including building of whole new towns, resulted in copper production rising to a peak of 769 000 t in 1969, providingover 62 000 direct jobs. The industry was nationalized in 1973 and remained in government hands for just over 24 years. During this period, the industry experienced a serious decline in production levels, reaching the lowest level in the year 2000 when production was 250 000 t. An average of just under 2000 jobs were lost every year in the 24-year period, reaching just over 22 000 direct jobs in 2000.Following the return of Zambian politics to pluralism and liberalized economic policies, the government decided to privatize the mining industry. The process started in 1996 and by the year 2000 all the mining assets had been privatized. The new investors embarked on serious investment to upgrade the assets and to develop greenfield mining projects. Fourteen years later and after more than US$12 billion investment, production levels increased year-on-year to a peak of 763 000 t in 2013 with direct jobs reaching 90 000.This paper discusses the impact of the mining industry in Zambia on the economy in areas such as employment, support for other industries, direct contribution to the national gross domestic product (GDP), foreign exchange earnings, and social amenities. The paper also focuses on the performance of the mines during these periods vis-à-vis mineral availability, mineral grades and complexity, new technologies, and human capital. This is looked at particularly in the light of current challenges the industry is facing. Suggestions are proposed on how the industry can be nurtured to continue being a major driver for the Zambian economy and a major player in the international copper mining business."

Jan 1, 2016

A numerical method for discriminating between replacement and sedimentary processes is applied to a folded stratiform sulphide occurrence. It is shown that numerical treatment of chemical analyses from a single diamond drill hole allowed a rapid assignment of the ore to the syngenetic sedimentary class and thereby enabled a revision of the evaluation program concerned with consequent reduction in costs.

Jan 1, 1973

By Jr. Gabler

The U.S. Bureau of Mines (USBM) has developed a computerized commodity flow model for strategic and critical materials This flow model is generic and applicable to most commodities and amenable to updating supply, demand, and/or production data change. The original model, with slight modifications, was used to track the flow of chromium. This report follows the flow of chromium through its metallurgical, chemical, and refractory applications, and highlights areas where significant losses occur because of downgrading, export, or disposal. The study indicates that materials containing 451,769 mt of chromium were consumed, including 99,221 mt of chromium from recycling, Chromium losses from all causes in 1989 were estimated to be 345,347 mt from a variety of areas. These areas and their chromium losses are as follows: processing losses, 38,825 mt; processing-downgraded scrap, 18,227 mt; manufacturing losses, 18,128 mt; manufacturing-downgraded scrap, 56,595 mt; prompt scrap exported, 1,531 mt; obsolete scrap exported, 43,443 mt; recovery losses, 155,529 mt; and recycling losses, 13,069 mt. Recycled chromium-containing material accounted for 22 pct of the apparent consumption of chromium in 1989.

Jan 1, 1994

By Xiaodong Wang

A liquid metal flow generated by a magnetic field whose traveling direction is periodically reversed, the Reversed Traveling Magnetic Field (R-TMF) is studied. The modulation frequency ranges from 0 to 6 Hz. Ultrasonic Doppler velocimetry probes the generated fluid flow. Depending on the modulation frequency, a number of characteristic flow features are exhibited. A transition frequency (approximately 4 Hz) exists, above which the flow is no longer sensitive to the force modulation. Below this transition point, the amplitude of the velocity oscillation increases, and then below fm = 0.05 Hz, it saturates around a value close to that observed without any modulation. A theoretical model to obtain an analytical solution of electromagnetic force and to predict flow motion is developed, which is fairly in agreement with the experiments.

Jan 1, 2009

What is a nugget effect? In the early development of geostatistics, the term ?nugget effect? was coined for the apparent discontinuity at the beginning of many semivariogram graphs. This name was chosen to reflect the large differences found between neighbouring samples in ?nuggety? mineralizations such as Wits gold reefs. Geostatistical theory assumes that the difference between a sampled value and a potential repeat sample at the same location is actually zero. Included in this ?nugget effect? would be true variation between contiguous samples due to the nature of the mineralization, micro-fracturing, nugget or crystal size, and so on. Also included in the nugget effect would be any ?random? sampling variation which might occur due to the method in which the sample was taken, the adequacy of the sample size, the assaying process, etc. Arguments were put forward that ?sampling errors? actually exist at zero distance. Some geostatistical schools actually maintain that the ?nugget effect? is all sampling error. This would imply that ?perfect? sampling would eliminate the nugget effect entirely. There is now a dichotomy both in the geostatistical world and in the software packages provided for geostatistical analyses. It may seem academic to argue over whether the semivariogram model should take a value of zero, a value equal to the nugget effect, or a partial value at distance zero. However, the decision can have a profound effect on both the estimated resource and in our confidence on that resource. Whereas most geostatistical texts define the semivariogram model as taking the value of zero at zero distance, others imply that the full nugget effect should be used at zero distance. For example: ?The nugget effect refers to the nonzero intercept of the variogram and is an overall estimate of error caused by measurement inaccuracy and environmental variability occurring at fine enough scales to be unresolved by the sampling interval3 ?Christensen4 has shown that the ?nugget effect?, or non-zero variance at the origin of the sernivariogram, can be reproduced by a measurement error model ?The nugget effect is considered random noise and may represent short-scale variability, measurement error, sample rate, etc.5. In many training texts and Web courses, the definition of the semivariogram is ambiguous as the formulae for semivariogram models is not actually specified at zero distance6,7,8.

Jan 1, 2010

By L. E. Eary

Many of the major international gold mining companies provide data on rates of greenhouse gas (GHG) emissions as part of their environmental reporting commitments. These data are evaluated by an index defined as the annual GHG emission rate in metric tons, divided by the annual amount of gold produced in grams, and referred to as GHGgold. This paper examines ranges of GHGgold values for a cross section of gold mines as a function of mining method (openpit, underground and combined operation) and ore-processing method (mill, heap leach and combined methods) for reported ranges of operational data, including annual total tons mined, ore processed and gold grade. The evaluation shows that ranges and distributions of rates of GHG emission are approximately similar across different mining methods and ore-processing methods. The data presented in this paper provide the context needed to make comparisons of GHG emissions reported in companies’ annual reports to the ranges reported for the overall gold mining industry.

Jan 1, 2009

I would like to thank The Australasian Institute of Mining and Metallurgy for inviting us to share with you some of our experiences in the handling, storage, and transportation of industrial minerals in North America. Cometals, Inc. is a wholly-owned subsidiary of Commercial Metals Company, headquartered in Dallas, a public corporation whose shares are traded on the New York Stock Exchange. Sales exceed one billion dollars. Cometals, Inc. is located in New York and specializes in marketing of chemicals as well as raw materials used in the manufacture of steel, refractories, abrasives, glass and ceramics. This makes us one of the larger regular shippers of industrial minerals. Many people are aware that industrial minerals need to be viewed and judged on the merits of their chemical and physical characteristics. In addition you are surely aware that close attention must be paid to the economics of these minerals to determine the appropriate value and competitiveness of the minerals or products delivered at the doorsteps of the consuming work. You may, however, not be aware that the handling and transportation of the mineral is of crucial importance, in fact, the transportation and handling costs of industrial minerals frequently are a major component of the value of the ores marketed and, therefore, it is only natural that close attention should be paid to them. Many of the industrial minerals require special handling to assure that the material reaches the consumer without being contaminated and without getting wet. I invite you to accompany me through the various steps involved in "delivering the goods" to the consumer.

Jan 1, 1989

By J. Hu, F. Lin, R. Chen, F Peng, S. Yang, W. Yu

"Microseismic monitoring technology has become one of the most effective method of mine ground pressure monitoring after decades of development. But safety assessment of mine ground pressure by using microseismic monitoring is still in the development stage, it needs to be perfected continuously in practice, and choose the optimal assessment indexes and methods. The definitions and physical meanings of wave velocity, b value, and EI-VA value are introduced in this paper. Statistical calculation of the microseismic events in Luomu Mine is finished by using these indexes, then the functions and calculation results of V, b value, and EI-VA value with the variable of time are also given in the paper. The preliminary safety assessment method is established in Luomu Mine, and it has achieved good results in practical application.1.1 Engineering background The Luomu Mine is a super large molybdenum and tungsten production base in China, ore reserves is up to 2 billion tons, first in Asia and third in the world. It begins mining since the 1960. and bases on underground mining until 2002. In order to recover resources more effectively, it began to use opencast mining method and formed a production of 30000t/d in the early 1990. After about 30 years of underground mining, a large mined out spaces was formed under open pit mine, up to area of 1.2 million m2 and volume of 18 million m3, as shown in figure 1. The large number of mined out spaces seriously affects the normal production, mining and handling of mined out spaces are in the high risk. In the past years, several rock mass collapsions happened, and it caused a serious security threat to persons and equipments. According to the distribution characteristics of mined out spaces, Luomu Mine is divided into A, B, C, D and E mining area. The stability of D mining area is studied in this article. D mining area mainly includes 1376,1350,1340,1317 mined out spaces and 1280 deep large mined out area, as shown in figure 2. The mined out spaces of D mining area is extremely complex and high-risk. Therefore, a microseismic monitoring system was built to monitor the stability of D mining area, a large number of valuable datum has been obtained, and it has a striking effect (Cheng & Peng, 2013; Peng et al., 2013)."

Jan 1, 2015

By Joseph Grumer

About a century ago Bunsen and his associates invented the famous burner that bears his name and was to become the ancestor of today's gas appliances. Over the years, Bunsen's invention became the starting point of a highly developed, practical technology that culminated in the gas industry as we now know it. However, it did not occur to the early workers to investigate the scientific potentialities of the new device, and as a result the science of gas-burner performance did not keep pace with the growing industry. It was with the objective of closing the rapidly widening gap between science and technology that the present research was undertaken Its immediate purpose was to provide basic information on the combustion characteristics of .fuel gases, in particular as they affect flashback, blowoff, and yellow tipping. Information obtained in the present research and contained within this report consists of the following: (1) Fundamental flashback and blowoff characteristics have been determined, it is believed, for all fuel-gas mixtures in which the gas industry may be interested. These are critical boundary velocity gradients for flames in free air, on burners with ports at room temperature and pressure. Burner aeration is characterized by the parameter, fraction of stoichiometric. These basic limits are explained, values are presented, and calculation procedure is given for deriving corresponding values of port loading and percent primary air (chs. I and II).

Jan 1, 1956

By M. E. Alam

In the present study, 1.1 volume percent of nano size copper was incorporated into pure tin using hybrid microwave sintering assisted powder metallurgy route. Microwave sintered samples were extruded both at room temperature and at 230 °C. Microstructural characterization studies were conducted on the extruded samples to investigate the distribution characteristics of secondary phase and grain morphology. Room temperature tensile test results revealed that hot extruded Sn-Cu samples exhibited higher strengths (~ 41%, in case of 0.2% yield strength and ~ 38%, in case of ultimate tensile strength) and ductility (~ 15%) when compared to room temperature extruded samples. On the contrary, the tensile properties of pure tin remained independent of extrusion temperature. An attempt is made in this study to correlate the effect of extrusion temperature on the microstructural evolution and tensile properties of Sn-Cu solder.

Jan 1, 2009

By Juan B. Yianatos

"After almost 100 years, since the first commercial application began in Australia, flotation has shown an extraordinary growth and nearly 2 billion tons of ore per year are presently treated by flotation processes. During this time flotation has promoted a wide scope of research activities ranging from fundamental chemistry and hydrodynamic studies to studies of industrial operations. In general, fundamental studies have been mainly related to ideal situations. In recent years, however, large efforts have been focusing on achieving a better insight into the actual sub-processes provided by the development of new and more sophisticated instrumentation. Since the massive incorporation of flotation columns, around 15 years ago, a renewed interest in flotation fundamental studies, process modelling and new cell designs have been observed worldwide. The key role of the froth has been recognized as an independent and sometimes rate limiting process step. Thus, separation of pulp and froth process stages seems the most appropriate in terms of process modelling, diagnostic, design and scale-up purposes.In relation to flotation equipment development, until the middle of the 1970?s, only the sub-aeration mechanical cells were dominant. Since the 1980?s, the use of pneumatic cells and forced air mechanical cells has emerged strongly. Also, in the last decade, flotation equipment has shown a dramatic increase in size, reaching values of 200m3 in unitary mechanical cells and more than 300m3 in columns. The general feeling, however, is that, despite the great advance observed in terms of process knowledge, the mechanisms and principles of industrial flotation cells design and scale-up are still not fully understood.Advances in process instrumentation and control now in use allow for more efficient operations, both in metallurgical performance and savings in operating costs.INTRODUCTIONFlotation is a widely used process within the minerals processing industry, as well as being used for water treatment and de-inking of recycled paper. Froth flotation started in Australia at the beginning of the 20th century and since then flotation technology has made significant advances. Flotation was firstly applied to sulfide ores. The largest tonnages treated by flotation are copper and copper/molybdenum ores, handling about 50% of the total ore processed. Also significant are phosphate, iron ore and coal treatments. At present, Chile is the foremost copper producer in the world with around 35% of the world?s production. Figure 1(a) shows the evolution of copper production in Chile over the last decade. The total amount of fine copper produced in year 2001 was 4.7 million tons, from which 3.2 million tons was processed by flotation while 1.5 million tons went through LIX-SX-EW processes, which also showed significant development during the same period (Anon, 2001). The total flotation treatment of copper ores in Chile is about 325 million tons per year (Anon, 2002), so the world treatment of copper ore by flotation can be estimated at about 1 billion tons per year. Consequently a total of nearly 2 billion tons of ore per year is presently processed worldwide by flotation (Fuerstenau, 2001). In order to handle the higher tonnage of low-grade ore, a worldwide trend towards the development and use of larger flotation machines began in the 1960?s. Figure 1(b) shows that the trend became extremely marked from the beginning of the 1990?s, which is consistent with the strong increase in copper production during the same period."

Jan 1, 2003

By L. D. Tracy

This is the third of the series of reports on coal-mine royalties and leasing conditions in Illinois. The results of the study of District VI were published as Serial No. 2726, January, 1926, and those of District VIII as Serial No. 2745, April, 1926, of the Bureau of mines. The counties of Macoupin, Sangamon, and Montgomery, which are three of the principal coal-producing areas in the northern part of District VII, have been chosen for this report because these counties cover an entirely different part of the State than do the two districts already covered. Some leases in, Randolph and Washington counties are included as they are in the southern part of the district, and the data happened to be readily available.

Jan 1, 1926

By E. H. BURROUCHS

This bulletin is the third of the series of yearly petroleum bibliographies being published by the Bureau of Mines. The two preceding, Bulletin 149 and Bulletin 165, were for the years 1915 and 1916, respectively. In arranging the references the same general scheme has been followed, but as in those bulletins, several changes and additions have been made in the classifica.tion, the more important being in the classes " Development and production " and "Refining and refineries." German periodicals for 1917 were not procurable and references to articles in those and in other foreign journals that were not available have been credited to the sources from which they were procured.

Jan 1, 1920

By H. M. Thurgood, F. A. Godfrey, F. W. Gilbert

This is a detailed presentation of the ancillary facilities, including power production, water supply, shiploading facilities, fire-fighting equipment, housing and community services. Additional subjects discussed include construction problems, townsite philosophy and staff organization.

Jan 1, 1968

By H. B. Sahu, N. M. Mishra, D. C. Panigrahi

The paper presents the development of a spontaneous heating liability index (SHLI) of coal based on a mathematical approach. The parameters for the calculation of this index have been determined by differential scanning calorimetric studies. Thirty-one coal samples representing both fiery and non-fiery coal seams of different ranks have been collected from different Indian coalfields and their SHLI values have been determined. In addition, the susceptibility of these samples to spontaneous combustion has been ascertained by standard crossing-point temperature measurement. The moisture percentage of all the samples has been obtained by proximate analysis. A comparative study between SHLI and crossing-point temperature, along with moisture percentage, indicates that SHLI predicts the proneness of coal to spontaneous heating more accurately.

Jan 1, 2008