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Jan 1, 1987

By Ting Ren, Lihai Tan, Alex Remennikov, Xiaohan Yang, Xueqiu He

"Due to recent coal bursts in Australian coalmines, research of coal bursts has attracted intensive interest from mining researchers and engineers worldwide. Previous research has shown that the sudden drop of fractal dimension may be a precursor of catastrophic failure of rock. This paper examines the fractal characteristics of temporal-spatial distribution of acoustic emission signals released during the compression loading process of coal. This research suggests the possibility of coal burst forecasting based on acoustic emission data. The concept and calculation equation of fractal dimension is introduced in this paper. Additionally, uniaxial compression experiments of Australian coal samples are conducted, and the acoustic emission waveform and 3D location are recorded simultaneously by eight sensors Express-8 AE monitoring equipment in the loading process. The experimental results indicate that the continued slowdown of fractal dimension in time sequence can be used as a precursory signal of coal sample brittle failure. The fractal dimension of the spatial distribution of acoustic emission events decreases with the evolution of coal fracturing.INTRODUCTIONCoal bursts refer to the catastrophic failure of overstressed coal subject to the dynamic and static loads. In recent years, coal bursts have occurred in major coal mining countries and this phenomenon has attracted the research interests of international mining and geotechnical scholars. A total of five coal burst accidents happened in Australian coalmines since 2014. On October 20, 2018, a coal burst occurred at Longyun Coalmine in China’s Shandong province, which led to 21 fatalities. Unfortunately, even after decades of research, it seems neither more accurate forecasting methods nor comprehensive controlling measures put forward by researchers have solved the problems posed by coal bursts.As an instantons energy releasing process, coal bursts are always associated with energy dissipation in the forms of acoustic emission, micro seismicity, and electromagnetic radiation (Yamada, Masuda, and Mizutani, 1989). It is believed by many researchers that the frequency–magnitude relationship of micro seismicity induced by rock failure satisfies Gutenberg-Richer relationship as well (Feng et al., 2017). Hence, based on the principal and theory of earthquake source locating, micro-seismicity monitoring equipment has been adopted in many coalmines to locate seismic event origins associated with coal and rock failure in an attempt to better forecast coal and rock bursts. Although many parameters such as b value (parameter of Gutenberg and Richter’s law) (Lu et al., 2015) have been adopted as indicators of risk, the forecasting of coal bursts is still of low accuracy. The same is true with earthquake prediction, as it remains as a worldwide problem even after decades of research and practice. Acoustic emission (AE) methods are now widely adopted to detect rock failure processes under an applied stress for application predicting the abrupt failure of rock in the laboratory (Li et al., 2017). Previous studies have found that significant overlap exists between research regarding AE and micro seismicity with respect to generation process (both are concerned with the generation and propagation of elastic wave) and event origin location, as geophysical signals of both are same (Lockner, 1993). That is, the frequency–magnitude relationship and early-warning indicators found by AE research in the laboratory have a potential applicability to in-field micro seismic monitoring of coal bursts. Through experimental study, Feng and Seto found that the temporal distribution of acoustic emission counts of rock have distinct fractal structures during load-increase processes (Feng and Seto, 1999). Landis and Lucie found good correlation between fracture energy and AE energy during testing of mortar specimens as well (Landis and Lucie, 2002). Based on preliminary experimental study, many schol"

Jan 1, 2019

Objective: To identify and evaluate a permanent stopping to direct ventilation airflows in large-opening metal/nonmetal mines.

May 1, 2006

By S. Illendula, B. Q. Li, R. A. Mirshams

"An integrated mathematical model is developed to represent the thermomechanical behavior of the materials and microstructure evolution during metal forging. The model development is based on the finite element solution of the thermoviscoplastic deformation of metals coupled with the internal state variable model describing the microstructure evolution involving work hardening, recovery, recrystallization and grain size distribution. The procedures for the integration of the microstructure model into the macro finite element model are described. Computed results for both macro and micro phenomena during metal forging, such thermomechanical deformation such as velocity field and effective strain rate and materials characteristics such as distribution of grain size and recrystallization volume fraction, are presented.1. IntroductionThermomechanical behavior and material microstructural evolution are two critical, interrelated aspects associated with metal workpiece undergoing large plastic deformations such as encountered in forging processes. In much of the modeling work up to date, these two aspects have been addressed separately. Die designs and forging processes are investigated using finite element based thermomechanical models while material dynamics during forging is studied, more often than not, as a separate subject. For many industrial applications, especially those involving novel, light and high strength materials, it is critical to combine these two aspects into a single, integrated model so that materials dynamics and thermomechanical deformation during forging processes can be considered simultaneously [1], thereby providing required information for intelligent process design and optimal process control."

Jan 1, 1998

By A. J. Stapleton

"The Copper Mountain mine of Gaspe Copper Mines, Limited was brought into production in January, 1968.This paper describes the organization, scheduling and control of maintenance of large open-pit equipment, including 8-cu.yd shovels and 85-ton electric-wheel haulage units. The facilities for repair as well as maintenance are also described, including repair shops and field repair equipment. Maintenance costs are discussed and particular reference is made to tire inspection, records and costs."

Jan 1, 1969

By Joseph M. Pugliese

The Bureau of Mines through its contract research program recently analyzed the mining and environmental requirements in the premining stage for copper mining in the northern highland of Wisconsin. The Critical-Path-Method (CPM) was used in this research. However, a step-by-step derivation of the CPM Diagram was beyond the scope of this effort. The Bureau of Mines objective now is to show, step by step, how the original hand-computed CPM Diagram was constructed. The streamlining (restructuring) of this diagram from the original effort is also summarized. The critical path time (longest time) through the original CPM Diagram was 25.12 yr, excluding public liaison effort. This diagram showed the involvement of the regulatory agency, mining applicant and public in the premining stage. Analysis of this diagram produced a streamlined version which reduced the critical path time by nearly 7 yr. The CPM construction methodology offered here may be applied to mine planning for any mining operation.

Jan 1, 1983

By P. Somasundaran, Tarun Bhambhani, S. Murthy Khandrika, Partha Patra, D. Nagaraj

Fine and ultrafine mineral particles, particularly if, altered mineralogically, can have detrimental effects on selective separation of minerals. Behaviour of altered mineral fines has been investigated in this work by studying the effects of weathered silicate slimes on the selective separation of copper minerals, particularly with focues on effect of the pulp rheological behaviour, which plays a governing role in the process. Physicochemical properties of these altered silicates fines such as morphology and surface charge are proposed to be responsible for the adverse rheological effects and resultant selective separation. Here, the effect of a number of problematic aspects such as water chemistry, froth stability, physicochemical aspects of gangue mineral aggregates on flotation sub-processes has been studied. Processing problems owing to the physical aspects of the gangue minerals, shape and morphology, are primarily due to uncharacteristic increase in the pulp viscosity. While problematic aspects other than impact of pulp rheological behaviour can interfere with each other in their contributions to how they affect the sub-processes, effects owing to pulp rheological behaviour have a direct impact on the flotation performance. Subtle increase in pulp viscosity can interfere with sub-processes in flotation leading to decrease in recovery and grade, and it is difficult to assess the effects due to such subtle changes. Reagent based strategies to overcome the problematic aspects has been explored here.

Jan 1, 2014

By D. R. Hanson

This Bureau of Mines study examines the acoustic vibrational spectra of rock slabs in the range of 0 to 5,000 Hz. The power spectra of so-called drummy rocks were found to be diagnostically enhanced in the range of 200 to 1,000 Hz. Comparison of the power in this band with that in a band from 3,000 to 3,500 Hz provides a quantitative measure of rock stability. A prototype field instrument was designed, constructed, and field-tested. This battery-powered instrument computes the power contained in the two frequency bands mentioned, compares the magnitude of these two quantities, and displays a number that is related to the detachment of the block tested. Field tests show that this instrument is capable of giving reliable measurements of block stability under conditions of noise and dust that would seriously degrade the accuracy of normal sounding techniques.

Jan 1, 1985

By R. E. Eyre, L. P. Landucci

C URRENT practice in the zinc concentrate roasting plant of The Consolidated Mining arid Smelting Company of Canada Limited, at Trail, B.C., involves passing the furnace effluent gases through an electrostatic precipitator for the recovery of dust. After removal of the dust the gas is treated for recovery of sulphur dioxide by conversion into sulphuric acid ( 1). However. as roasting techniques improved, and furnace productivity in-creased, the rated capacity of the precipitator was exceeded and it was necessary to consider various means of improving the dust recovery. A study of methods indicated that a baghouse using silicone-treated glass fabric, might be suitable for this particular application. Glass fabric was chosen because the temperature of the roaster effluent gases would range from 450°F to 500°F and tempering air was undesirable to avoid dilution of the sulphur dioxide gas.

Jan 1, 1962

By R. M. Santmyers

The chief compounds of boron are borax and boric acid, both of which have important applications in industry. At present the United States furnishes more than half of the world's requirements of borate materials, practically all from California. Nearly the entire production of borax in this country is under the control of four companies: The American Potash and Chemical Corporation, the Pacific Coast Borax Co., the West End Chemical Co., and the Western Borax Co.

Jan 1, 1931

By Gray Mullins

This paper presents results from model and full-scale tests to assess the interface bond between a cast-in-place concrete seal slab and steel H-piles in cofferdams. Three different seal slab placement conditions - fresh water, salt water and bentonite slurry - were evaluated and the results compared against controls where no fluid was displaced by the concrete. Normal pile surfaces were investigated. Additionally, the situation of ?soil caked? piles was also tested. In the model tests, eight 15 cm deep, W6 x 15 sections were used for two different embedment depths of 1.5d and 2d, d being the depth of the section. In the full-scale tests, 16 specimens 35 cm deep (W14 x 90 sections) were tested with the embedment varied between 0.5d-2d. The results show that significant bond stresses developed even in the worst placement condition. Recommendations made for revising current values in specifications have already been implemented by the Florida Department of Transportation.

Jan 1, 2013

By Michael A. Piepenburg

The East Side Access (ESA) Project will extend Long Island Rail Road (LIRR) into midtown Manhattan via 11 km of tunnels, a new terminal station and associated support facilities. In addition to the hard-rock tunneling currently underway in Manhattan, soft-ground tunnels in Queens will traverse beneath Amtrak?s Sunnyside Yard and Harold Interlocking, the busiest rail interlocking in North America. This paper details ESA?s coordinated approach to interfacing with both Amtrak and LIRR with regard to the planned tunnels, shafts and related construction beneath or adjacent to the operating railroads. This interface includes integration of railroad staff, extensive presentations, reviews and agreements with the railroads regarding settlement mitigation, real-time automated geo-instrumentation monitoring, ground improvement, and geotechnical/environmental controls.

By R Zhou, B J. Monaghan, S J Chew, R J. Longbottom, D J. Pinson, H Li, P Zulli, G Zhang, L Lu

Steelmakers are increasingly motivated to use iron ore resources with a wider range of grades and mineral types that were previously considered unsuitable or uneconomical for sintering. In this respect, specific issues, which now require further investigation and understanding, include the sintering of ore types with:- overall higher gangue content- elements that cause problems in the steel manufacturing operations- distinctive sintering performance compared with traditional hematite-rich iron ores. Laboratory-based investigations of the sintering performance and the behaviour of gangue impurities during sintering is an important step towards the successful utilisation of these resources in steelmaking.In terms of laboratory-based sintering investigations, there are two generally accepted experimental scales utilised prior to undertaking industrial-scale trials, which include: bench-scale tablet (compact) testing and pilot-scale pot testing. The former has the advantages of flexibility and more precise control of sintering conditions; but it is difficult to simulate the heterogeneity of a sinter bed. The latter, which is carried out in pots with diameters between 150–500 mm, simulate the commercial sintering process and conditions quite well, but is time-consuming and labour-intensive due to operational complexity. It is therefore desirable to establish a smaller scale pot testing facility that avoids the disadvantages of the normal sintering pot but can provide comparable information.To explore the feasibility of small-scale pot testing, a ‘millipot’ facility was established to examine the sintering performance of iron ores and other non-traditional ferrous materials. The millipot has a diameter of 53 mm and height of 400 mm. The facility has the capability to monitor the sintering temperature at a number of locations (axial, radial) within the sinter bed and to adjust the suction (‘windbox’) pressure. This paper describes the development of the millipot facility and operational procedures, together with initial tests undertaken in order to match its performance with industrial sintering performance.CITATION:Li, H, Zhou, R, Pinson, D J, Zulli, P, Lu, L, Longbottom, R J, Chew, S J, Monaghan, B J and Zhang, G, 2017. A millipot set-up for sintering investigation of iron ores, in Proceedings Iron Ore 2017, pp 85–90 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Louis A. Panek, John A. Stock

A flat slot is created in rock to cause stress relief effects in a pair of hydraulic borehole pressure cells (previously installed in drill holes above and below the slot ) , which act as sensing devices . This relief is annulled by repressuring the slot by means of a flat hydraulic cell . The slot pressure at annulment is taken to be the existing ground stress at right angles to the plane of the slot . A number of trial installations in the rib of a mine drift showed that for a valid determination of ground stress the sensing devices that respond to relief and repressuring must be within a specified zone close to the pressure transmitter ; otherwise the indicated ground stress may be excessive . By using an additional pair of borehole pressure cells , installed a few feet away , the existing rock stress can be redetermined at intervals , irrespective of a change of stress intensity subsequent to the initial installation . Based on these findings , equipment and procedures have been developed that make possible the installation and operation of a permanent rock stress monitoring station for observing mining - induced stress changes . The station consists of a 12 - in - wide hydraulic pressure cell cemented in a flat slot and four 2- by 8 - in flat hydraulic pressure cells in nearby drill holes . All drilling for the installation can be done with an air leg drill and conventional bits . Once the installation is completed , all required information is obtained by Bourdon pressure gage readings . The apparatus is simple , relatively inexpensive , and reliable under operating conditions in a wet mine . Unlike most methods of rock stress determination , this scheme permits periodic remeasurement of absolute rock pressure over several years , without additional drilling or instrumentation . Similar to other flat slot procedures , stress measurements are obtained without making auxiliary tests to determine elastic

Jan 1, 1964

By K M. P Singh, K M. K Sinha, G S. Jha, T Gouricharan, K K. Sharma

The majority of the powerplants in India are fed with non-coking coals, with the coals dispatched from their respective mines via wagons loaded by a rapid loading system or pay loader. The usual top size of coal is 200 mm and sampling is carried out manually from wagons. The manual method of wagon top sampling of large size raw coal is not only difficult, but also violates some of the fundamental principles of sampling. As per sampling requirements, samples are to be drawn from the full depth of the wagons, which is impossible to be done manually. Since the ash distribution in the different size fractions is not homogeneous, the results from the samples, which do not reflect the true size distribution of the lot, are likely to be biased. More importantly, sample collection by shovel from the top is a function of human discretion and not governed by the equiprobability rule. In another case, the sample has been collected by a cross belt-type auto mechanical sampler for 200 mm size coal at one of the super thermal power stations. Test analysis shows that coal collected using a cross belt-type mechanical sampler also has significant deviations from stopped belt coal samples of 200 mm size due to size segregation. Studies carried out on wagon top sampling through specially designed experiments reveal some interesting features. The presence of bias in wagon top sampling is apparent when compared with the ‘stopped belt’ sample. In this paper, a comparative study between manual wagon top sampling/auto mechanical sampling with respect to stopped belt sampling has been conducted for coal of size 200 mm. In addition, precision studies have been performed for wagon top sampling/mechanical sampling for Indian thermal powerplants.CITATION:Sinha, K M K, Sharma, K K, Jha, G S, Singh, K M P and Gouricharan, T, 2014. A comparative study of manual wagon top sampling and auto mechanical sampling of 200 mm size coal with respect to stopped belt sampling of thermal coal at Indian super thermal powerplants, in Proceedings Sampling 2014 , pp 43–48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By J. W. Thompson

BURYING DEAD MINERS. BURYING BODIES OF DEAD MINERS. REVISED STATUTES (HURD) 1874, P. 263. SEC. 22. LIABILITY OF RAILROADS, ETC., FOR BURIAL EXPENSES.-When any railroad company, stage or any steamboat, propeller, or other vessel engaged in whole or in part in carrying passengers for hire, brings the dead body of any person into this State, or any person dies upon any railroad car or in such stage, steamboat, propeller or other vessel in this State, or any person is killed by cars, or machinery of any railroad company or by accident thereto or by accident to or upon any such stage, steamboat, propeller, or other vessel, or by accident to or in or about any mine, mill or manufactory,* the company or person owning or operating such cars, inachinery, stage, steamboat, propeller, or other vessel, mine, mill or manufactory shall be liable to pay the expenses of the coroner's inquest upon and burial of the deceased and the same may be recovered in the name of the County in any court of competent Jurisdiction. NOTE--The original Act of February 15, 1855 (Laws 1855, p. 170), makes no reference to the dead bodies of persons killed" by accident to, in or about any mine."

Jan 1, 1919

By K. L. Paciorek

The aim of this program was to develop a reliable and meaning-ful basis for assessing certain safety aspects, namely fire and, in particular, toxicity hazards of articles employed in underground coal mining operations. The present investigation was concentrated on the thermal oxidative degradation of representative hydraulic fluids. To achieve this goal all products formed on thermal oxidative degradation of the fluids studied were analyzed, identified I and the amount of each individual species present was determined quantitatively on a weight of product per weight of material basis. The weight/weight data thus obtained can then be factorized to reflect the relative toxicity of each individual species present, using for example the Threshold Limit Values adopted by the American Conference of Governmental and Industrial Hygienists, whereby an overall "toxicity index" can be arrived at which makes it possible to compare the different fluids and/or classes of fluids in a quantitative manner insofar as their toxicity is concerned.

Jan 1, 1976

By Ana Carolina Martins Silva

Os aços inoxidáveis dúplex ferríticos-austeníticos fazem parte de uma classe de materiais com microestrutura bifásica, composta por uma matriz ferrítica e ilhas de austenita, com frações volumétricas aproximadamente iguais dessas fases. Essa classe de materiais é caracterizada por apresentar interessante combinação de elevadas propriedades mecânicas e de resistência à corrosão e, por isso, é considerada bastante versátil, sendo utilizados nas indústrias química e petroquímica, de papel e celulose, siderúrgicas, alimentícias e de geração de energia. Este trabalho objetiva caracterizar as microestruturas do Aço Inoxidável Duplex SAF 2205, revelando as fases que se apresentam após tratamento térmico a 800ºC, em diferentes tempos, estudar a relação entre a dureza do material e a precipitação da fase sigma, além de determinar a cinética de precipitação dessa fase. Após obtidos os dados experimentais, dados de VV e composição de equilíbrio da fase sigma foram obtidos via Thermo-Calc. Ao final do trabalho, os resultados experimentais e de simulação são comparados e conclui-se que a nucleação da fase sigma é por difusão de Cromo na matriz.

Oct 30, 2017

By Joseph M. Pugliese

This work was done by the Bureau of Mines to provide quarry operators with an uncomplicated, first-approximation method for designing blast patterns, considering geologic structure, and to show the valid use of the technique by comparing drill and blast pattern dimensions used in the quarry with those determined by the presented method. The author visited 12 limestone and dolomite quarries in Ohio (Adam, Crawford, and Highland Counties), Wisconsin (Milwaukee, Racine, and Waukesha Counties), and Minnesota (Fillmore, Olmsted, and Wabasha Counties); observed the blasting practices; studied the major geologic features; and after discussion with the quarry managers, foremen, and blasters, compared the quarry blasting patterns with those as calculated by the empirical formulas (after R. L. Ash), with geologic structural considerations. When geologic structure such as bedding, jointing, folding, and caves, as well as explosive properties and field performance characteristics are accounted for in a manner suggested by the research, the presented empirical formulas may be used as a good first approximation. The included steps in planning a blast design and generalized blast patterns should be of help to the quarry operator. Design changes are recommended for those quarries where problems are occurring.

Jan 1, 1972

By D. W. Loucks

There is plenty of evidence to indicate that at least one of man's chief interests in life is to make himself as comfortable as possible. If you doubt this, just watch the fellow next to you for the next half hour trying to find the most comfortable position that a hard chair has to offer. Comfort, however, does not always mean an easy chair. To some, it may mean a wealth of money: to another, freedom from worry. But to most of us, it means first of all a comfortable atmosphere in which to live, and to a great many of us it probably also means freedom from that annoying task of firing the furnace. Today more than ever before, automatic heat is one improvement that is placed high on everyone's list. Perhaps this is because automatic heating is becoming relatively cheaper. Perhaps it is because of a good publicity campaign on the part of the oil and gas men or maybe it is just that we are getting lazier day by day. At any rate, almost every issue of Better Homes and Gardens, House Beautiful, or your other favorite home magazine carries an article extolling the virtues of this or that automatic heating system.

Jan 1, 1949