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By Tamara Whitaker, James Gunderson, Ruilin Yang

This paper presents the results of a vibration control project conducted in soft overburden at a surface coal mine located in the western United States. The study uses near-field blast vibration monitoring, analysis and modeling techniques developed in house. Accelerometer-equipped seismographs were utilized for near-field vibration monitoring and analysis. Vibration control was achieved through field data regression as well as vibration modeling using the multiple seed near-field blast vibration model (Yang and Scovira, 2007). The regression was conducted between peak particle vibration parameters and the minimum scaled distance per delay. From the regression analysis, the curves of upper bounds for peak particle vibration parameters and charge weight were developed. The dominant frequencies of the blast vibration were also addressed in this project. The regression curves and near-field vibration model guided the blast design to control blast vibration for maximizing the recovery of coal and maintaining mine productivity.

Jan 1, 2008

By M E. Watson

Minimising dilution and ore loss is an important part of ensuring profitability of a gold mining operation. White Foil open pit gold deposit is a low-grade deposit and therefore managing ore quality is a high priority. Ground movement through blasting can displace ore and waste boundaries up to 10 m from their in situ location and therefore requires stringent ore movement monitoring and adjustment. There are currently only two options for monitoring blast movement – utilising visual targets (commonly lengths of polypipe) but this has widely been replaced by electronic blast movement monitors (or BMM). Regardless of the technology used, the basic principle is to compare the pre- and post-blast locations of the targets to determine the movement of the rock mass during blasting, which is then used to determine the final location of ore and waste boundaries.The Blast Movement Technologies (BMT) BMM system has been used at White Foil since June 2014. The system has been effective and reliable during that time; however, the annual cost of using the BMM system is greater than other monitoring alternatives. As such, the open pit geology team conducted a study comparing the BMM system against the conventional polypipe technique. The objective was to quantify the profit and loss that would occur based on the ore block transformations from both methods. Eight blasts were selected where polypipes were installed in additional holes adjacent to the BMM monitoring holes. The resulting movement vectors from the respective methods were used to create post-blast ore blocks by transforming the in situ ore blocks. While polypipe is a cheaper alternative, the BMM system tracks ore and waste boundaries more effectively resulting in better quality control, enhanced ability to minimise dilution and ore loss thus maximising profit. For these eight blasts, it is calculated that the BMM system resulted in A$664 978 extra profit through a reduction of ore loss. The total cost of a yearly BMM package was recovered in the first two blasts of this study. The primary reason for the difference is that polypipe had a poor recovery rate of 32 per cent compared with 92 per cent for BMM at White Foil. Therefore, the data used to transform the ore blocks was less representative, resulting in inaccurate post-blast ore block boundaries when using polypipe.CITATION:Watson, M E, 2017. Blast movement monitors or polypipe? A study into cost-effective blast movement monitoring at White Foil gold mine, Western Australia, in Proceedings Tenth International Mining Geology Conference 2017, pp 433–440 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By André Luiz Monteiro Martins

O objetivo do projeto foi otimizar a disponibilidade e o tempo de utilização do equipamento responsável pelo refino secundário de aço líquido da CSN, o Desgaseificador a vácuo RH. Esta otimização ocorreu através da monitoração de eventos gerados por sensores instalados no equipamento para verificar quando o mesmo iniciou a operação e qual foi o tempo necessário para completar o processo. O Disponibilidade do Desgaseificador a Vácuo RH se trata de uma ferramenta gerencial que realiza o mapeamento completo da produção no Desgaseificador durante vinte e quatro horas por dia, capaz de mapear o tempo do processo com base no tempo padrão do grau de aço e tempo de parada do equipamento, apontando todos os problemas que afetam a produção.

Aug 16, 2017

By Carlos Filippe de Sousa Morais

O software desenvolvido tem como objetivo, mapear o real tempo de operação do RH da Companhia Siderúrgica Nacional - CSN, identificando os atrasos antes e durante o tratamento de um aço no equipamento. Para isso foi criada uma tela automática que é aberta ao operador toda vez que é identificado atrasos, seja durante a troca de panela (Disponibilidade) ou durante o tratamento do aço (Processo). É possível visualizar em qualquer período desejado o preenchimento dos atrasos através de um relatório e uma interface gráfica interativa gerada pelo software, e com isso tomar medidas capazes de melhorar a produtividade no RH. Os resultados abordados ao longo deste trabalho mostram que a solução de uma pequena parte destes atrasos pode gerar ganhos de produção significativos para a Companhia Siderúrgica Nacional.

Aug 16, 2017

By S. Ubaldini

Acid mine drainage (AMD) is a common problem in different areas with a past history of mining activities, which is characterized by low pH (2-4.5) and significant toxic metals concentration. The main aim of the present work was to perform a process feasibility analysis in order to remove heavy metals (Cd, Zn, Ni, Mn, Cu) from AMD (Acid Mine Drainage) in a relatively cheap and environmentally friendly way, by means of electrowinning and biosorption. A first characterization of an Italian AMD sample was performed evidencing a zinc concentration around 2 g/L, cadmium and nickel content of about 4 mg/L, manganese of 85 mg/L and iron 190 mg/L. Electrowinning tests lead to the following metal removal after three hours treatment: Zn 99%, Ni 99.9%, Cd 99.9%, Cu 99%, Mn 87%, Fe 96%. Moreover, an high grade of purity of the metal deposit has been achieved (Zn>95%), as observed by X-ray diffraction analysis. Considering that metals concentration in the effluent was still above legal limits (in particular for Zn, Mn and Fe), a further biosorption treatment was planned in order to produce an effluent fitting environmental limits. Experimental electrowinning tests and literature multimetal column biosorption data have been used in order to perform a preliminary techno-economic feasibility analysis of the process aimed at metal removal from AMD. A treatment cost of about 6.5 ?/m3 AMD has been estimated, for a plant capacity of 10 m3/h AMD inlet flow rate.

Jan 1, 2006

By Rainer Hüsken

Over the last decades long BOF campaign lives have successfully been established due to improved quality of the refractory material and due to intensive use of slag splashing. On the other hand, steelmakers are more and more faced with elevated phosphorous contents in the hot metal. This phenomenon is a global tendency caused by the increasing pressure to utilize cheaper iron ore sources. In India, iron ore sources have traditionally elevated phosphorous contents. The phosphorous removal challenge calls for using bottom stirring at the BOF converters, as these combined technology of top oxygen blowing and inert gas stirring through the bottom, helps significantly to improve bath mixing and thus in shifting the process towards the optimum metallurgical equilibrium conditions. All this is common knowledge and daily business in the steelmaking shops all over world. Unfortunately, focusing on a long BOF refractory campaign by means of slag splashing and maintaining optimum conditions for high efficient bottom stirring are naturally conflictive aims. Applying slag splashing causes unavoidable bottom built-up which in turn covers or even blocks the bottom tuyeres. Most of the steelmaking shops today are either operating slag splashing without bottom stirring or bottom stirring without slag splashing. Some are trying slag splashing with bottom stirring but mostly only for a certain short period of the whole campaign. Baoshan Meishan Steel is an integrated steel plant, located in Nanjing (China). The plant is operating two BOF shops (3x 150t and 2x 250t), producing various steel grades. Because of the iron ore source used, the hot metal phosphorous content is rather high with up to 2,000 ppm. In order to achieve low phosphorous contents in the molten steel below 200 ppm, Meishan uses the TBM (Thyssen Bottom Metallurgy) bottom stirring technology in both of their steel plants, successfully applying slag splashing and efficient bottom stirring for campaigns up to 10,000 heats. This paper describes the operation procedures, strategies, and the maintenance concept established at Meishan Steel which is suitable to meet both conflicting targets at the same time.

Jul 30, 2018

By M. P. Board, J. K. Whyatt, T. J. Williams

The U.S. Bureau of Mines has been conducting a series of rock mechanics investigations at the Lucky Friday Mime in the Coeur d'Alene Mining District of northern Idaho. In the present study, the energy release rate (ERR) index was used to evaluate three underhand stope backfill parameters--cement content, density, and placement gap-to determine their influence on rock bursts. This index provides a relative measure of the likelihood of rock bursting for a given rock mass. It is known that the elastic idealization of the rock mass inherent in this method causes underestimation of stope closure and hence underestimation of the influence of backfill on rock bursting. However, this evaluation still showed that (1) changing from present practice to one in which backfill was omitted altogether would increase the ERR by 42 pct and (2) perfect placement of backfill would reduce the ERR below present practice levels by 28 pct. The easiest step toward perfect placement would be elimination of the placement gap, which accounted for half of the difference in ERR between present practice and ideal placement conditions. There was no indication that increasing initial fill strength through increased cement content would affect the ERR.

Jan 1, 1992

By W Curlewis, D Hake, Z Cuthbert

The South Island Line (East) will be a medium-capacity railway covering approximately 7 km from Admiralty Station to South Horizons Station on the south side of Aberdeen Harbour in Hong Kong, with intermediate stations at Ocean Park, Wong Chuk Hang and Lei Tung.South Island Line (East) Contract 904 project is located on the island of Ap Lei Chau at the southern side of Hong Kong island and requires extensive construction works to be completed in close proximity to the existing residential estates of South Horizons and Lei Tung. The project also has areas of significant cultural heritage, including 18th and 19th century temples and historical gravesites. Owing to the site access constraints and location for the project, detailed planning and methodology innovations have been required to ensure the most effective and responsible means of delivering the project works. To excavate the tunnels using drill-and-blast techniques in these restricted locations, the maximum instantaneous charge weight that could be fired while blasting was severely limited. To overcome these restrictions, the project team developed and pioneered the use of ‘deck loading’ in Hong Kong to minimise the impact of blasting operations and has successfully implemented double- and triple-deck blasting operations during the completion of tunnel excavation works.Upon completion of the drill-and-blast excavation, the tunnel lining works were completed using both in situ concrete lining with travelling forms and permanent shotcrete works.CITATION:Curlewis, W, Cuthbert, Z and Hake, D, 2014. SIL904 Hong Kong – Drill and Blast Tunnels, station blasting innovations (double- and triple-deck blasting) and lining solutions, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 21–28 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By Jack E. Bailey

From a start in 1957, milling 3,000 TPD of copper ore, the Cyprus Pima Mining Company, which is located 20 miles south of Tucson, has expanded its operations four times, and is currently treating over 55,000 TPD of ore.1 The most recent expansion added a 14,000 TPD semi-autogenous concentrator to the operation. Shortly after startup in January, 1972, the semi -autogenous plant exceeded the designed tonnage rate.2 Ore from the mine is delivered to a 54 inch gyratory crusher and is reduced to a minus 8 inch product. From the crusher the ore is stacked on a surge pile and then reclaimed and fed to the two parallel grinding circuits. A 28 ft. diameter by 12 ft. long semi-autogenous mill and a 16.5 ft. diameter by 19 ft. long ball mill make up each grinding circuit. The semi-autogenous mills are in closed circuit with screens and the ball mill circuits are closed with hydro- cyclones. Rougher flotation follows the grinding operation. Concentrate regrinding and cleaner flotation is performed in Mill I, the older mill. The generalized flowsheet is shown in Figure 1.

Jan 1, 1975

By Timothy P. Smirnoff, Anthony Stirbys, Amanda Elioff

The construction of the continuing expansion of the Los Angeles Metro System has required the construction of eight new station structures. One contractor proposed, as a construction alternative for the support of excavation of the Hollywood/Vine Station, the use of soil-mix walls instead of the conventional soldier piles and wood lagging. Soldier piles and shotcrete or wood lagging support systems had been generally used on the other sub-way station excavations constructed to date throughout the system. Immediately east of that station and in almost exactly the same geology, the Hollywood/Western Station was being excavated at the same time using a conventional support system. This paper com-pares the performance of these two support systems in the alluvial soils of the Los Angeles Basin.

Jan 1, 1997

By Rene Guilherme Lopes

A refrigeração necessária a separação e liquefação dos gases do ar em uma planta de separação de ar do tipo PL de fabricação Praxair, é produzida em um equipamento denominado “Bridge Machine”. Foi identificada a oportunidade de operar este equipamento acima da capacidade nominal, porém havia algumas restrições para atingir a pressão necessária, tais como: a linha de descarga, a calibração da PSV, a MAWP (pressão máxima te trabalho admissível) do aftercooler e PHX (trocador de calor principal da Planta) e de outras linhas no processo. Para aumentar a produção na Bridge Machine, fez-se necessário requalificar a MAWP do aftercooler e do PHX, além de substituir as linhas de descarga e recalibrar a PSV, assim podendo trabalhar com a pressão máxima possível.

Jul 31, 2018

By Yinan Zhang, Yi Luo

The widely used R70 method is modified to measure the self-heating propensity of low-rank coals. This modified R70 method enables the introduction of controlled amount of moist oxygen into the reaction vessel. Three coal lumps were collected from three different locations in a surface mine in the Powder River Basin. The coal samples were tested in oxygen flow with controlled moisture content under adiabatic condition. By measuring the relative humidity at the exhaust exit point of the testing setup, the flux and cumulative wetting heat that is consumed by coal samples can be determined. Through a better way of determining the coal’s specific heat, the total heat, including heat of wetting and coal’s oxidation heat, required to raise coal to a given temperature can be determined. Then, the contribution of heat of wetting at the different stages of the testing is quantified. The effects of evaporative heat through a group of tests have also been quantified. From this research, a better understanding of the effect of wetting heat on inducing low-rank coal’s spontaneous combustion can be acquired.

Nov 30, 2022

By Bernard K. Asdell

Georgia, a state seldom considered to be an important mineral producer, has one surprising feature-it is the nation's largest producer of kaolin. Kaolin is a highly important raw material in the paper, rubber, ceramic whiteware, paint and chemical industries. In 1965, more than 2.7 million tons of kaolin were produced in this state, a 150,000-ton increase over the preceding year, and production continues to climb. Strictly defined, the term "kaolin" applies to a group of hydrous aluminum silicates in which kaolinite is the predominant mineral. Kaolinite is inherently white, non-abrasive, chemically inert, and of a very fine particle size, ranging from sub-micron to 40-microns equivalent spherical diameter. An electron-micrograph of kaolinite is shown in Fig. 1. The particles finer than about 2 microns are thin, elongated plates, hexagonal in outline. The larger particles, coarser than 2 microns, are predominantly vermicular in outline with a foliated structure. Table I shows a typical chemical analysis of commercial, wet-processed kaolin compared to pure kaolinite.

Jan 11, 1967

By Jack A. Crichton, Henry J. Gruy

This paper discusses methods used in the estimation of natural gas reserves and the general conditions under which the various methods are applicable. The factors used in estimating natural gas reserves are reviewed. Errors which have been found to occur frequently are listed. Introduction The estimation of natural gas reserves has become of paramount interest because of the increasing importance of gas in the nation's economy. Gas is a most desirable fuel, a fact substantiated by the continued rise in the market demand. In addition, new uses for gas are being developed by the chemical, plastic, and associated industries, and plants are being built to make gasoline from natural gas. These are a few of the factors contributing to the importance of the nation's natural gas reserves. With the increased importance of gas there is an increase in the need for reliable estimates of the magnitude and availability of natural gas reserves. These estimates are being used currently: (I) to determine which fields contain sufficient available reserves to justify the construction of pipe-line outlets to serve particular markets; (2) to design pipe lines necessary to serve those fields adequately;] (3) to determine the location of industrial and chemical plants; (4) to finance the development of gas properties, and the construction of gas pipe lines; (5) to determine fair and adequate depletion allowances and depreciation rates; (6) to justify applications for gas pipe lines before various regulatory bodies; (7) to determine the number of wells required to exploit the reserves most economically; (8) to aid in establishing values for the purchase or sale of gas properties, and for purposes of inheritance taxes; (9) to determine equities under unitized operations; (10) to provide a basis for calculating the economics of gas-cycling operations. History or Estimation of Natural Gas Reserves The natural gas industry in the United States had its beginning during 1826 when natural gas was used for lighting the city of Fredonia, N. Y. The first natural gas pipe line was a 25-mi]le wooden line constructed from hollowed logs, connecting West Bloomfield and Rochester, N. Y. There is no record of an attempt to estimate the gas reserve at West Bloomfield but an attempt was made to determine the capacity of the well by measuring the time required to 611 a large balloon. One of the earlier publications concerning estimation of natural gas reserves is the "Manual for the Oil and Gas Industry," published by the Treasury Department, United States Internal Revenue, in i9i9. The following methods of computing "gas depletion" are listed: (I) production decline of the gas well or property; (2) decline in open-flow capacity; (3) comparison with the life history of similar wells or properties, particularly those exhausted Art

Jan 1, 1949

By W. A. Backofen, D. Lee, F. S. Jabara

THE empirical character of plasticity analysis insures a continuing need for measurements of the yield surfaces of anisotropic materials. Recently, Wheeler and Ireland (W-I) proposed that an octahedral yield locus could be constructed on the basis of six Knoop hardness indentations. Such simplicity would have obvious appeal, if it led to consistently dependable results. In other recent work, a much more straightforward (and more tedious) method of measurement was used to establish all quadrants of the plane-stress yield loci for two substantially anisotropic titanium alloys.2,3 The same materials have since been reex-amined by the W-I method with results being reported here. A full description of the stress state under a Knoop indentor would be complex. In principle, however, this can be avoided in relating the hardness number to a plane-stress yield locus, by the expedient of superimposing the appropriate hydrostatic component on that state of stress. Six possible orientations of in-dentor on orthogonal (symmetry) planes, along (principal) coordinate directions, are illustrated in Fig. 1(0). Pictured in Fig. l(b) are normal-stress components nominally associated with indentation n: o2(H), directly proportional to the Khn in this case, together with By overlaying a hydrostatic tension, ah, that in general is equal to the stress state around the indentation is reduced to one of plane stress in the x-y plane for which the stress ratio is a The key step in the W-I yield-locus construction is to represent the Khn for any indentor orientation as a vector quantity on the octahedral plane. In the plotting, the vector is given as deviatoric stress components along the principal axes in the ratio , where represents the direction of the minor (width) diagonal and 1 that of the major (length) diagonal. There is no attempt by W-I to justify the 7/1, although it might be supposed that the value originates in the usual ratio of major to minor diagonals in a Knoop indentation of about 7/1. If that were its origin, the link to the deviatoric stress ratio would presumably be made by first taking 7/1 and then turning to the Levy-Mises equation for isotropic material: Interpreted in this way, the W-1 approach seems arbitrary and even contradictory. Yet it would still be favored by two circumstances: the deformation under a Knoop indentor approaches plane strain: when dcw/del =a; and the shape of the locus where plane strain is represented is not overly sensitive either to the exact value of dc,/dcl or to the degree of anisotropy, within a rather wide range of both variables. The second point is illustrated below, after a few additional comments on applying hardness

Jan 1, 1968

By J. R. Low, M. B. Reynolds, L. O. Sullivan

The effect of neutron bombardment upon the stability of type 347 austenitic stainless steel has been investigated by a magnetic technique. The relation of the ferrite content of a stainless steel to its magnetic properties is given, and an apparatus suitable for the measurement of the ferromagnetic saturation induction of small specimens is described. Results of measurements on irradiated specimens are tabulated. Exposure to a neutron flux was found to cause a slight increase in the ferrite content of type 347 stainless steel, the change increasing with increasing length of exposure and with increasing initial ferrite content. The similarity of the effect of irradiation to the effect of annealing is pointed out. Possible effect of irradiation upon density of austenitic stainless steel is discussed. COMMERCIAL austenitic stainless steels are alloys of iron, chromium, and nickel, plus small quantities of other elements. Although these alloys are normally used in the austenitic condition, this state is thermodynamically metastable at ordinary temperatures and transformation to a more stable state takes place under favorable conditions. In the austenitic state, these stainless steels have the face-centered-cubic crystal structure characteristic of y iron, but the stable state at room temperature is a mixture of austenite and body-centered-cubic ferrite. The transformation from the pure austenitic condition may be brought about by cold working the alloy at a temperature below that at which the aus- tenite becomes thermodynamically unstable (about 400°C), the completeness of transformation increasing with increasing severity of cold work and decreasing temperature. The behavior of the austenitic stainless steels under ordinary conditions of use is rather well known. However, use of these alloys in a nuclear reactor introduces a new variable: the effect of neutron bombardment upon the transformation from the austenitic to the ferritic state. It was with this in mind that a study of the radiation stability of austenitic type 347 stainless steel was undertaken. Magnetic Technique for Ferrite Determination Commercial austenitic stainless steels such as type 347 undergo little transformation under normal conditions of fabrication and use. In view of this fact, it seemed likely that neutron irradiation would change the ferrite content of the alloy but little. The method chosen for measurement of the effect of neutron irradiation was thus limited to one which would be quite sensitive to small changes in the ferrite content of the alloy. Of the properties of the stainless steel which can be measured, the magnetic characteristics are most sensitive to the quantity of ferrite present.

Jan 1, 1956

Surface subsidence that results from longwall mining can be large magnitude and can affect significant areas. Conventional methods for subsidence monitoring include leveling, global positioning system (GPS), and photogrammetric surveys. Remote sensing techniques, including aerial LiDAR, terrestrial laser scanning, and satellite-based differential interferometric synthetic aperture radar (DInSAR), are also used to measure deformation associated with subsidence. DInSAR data are different than data from conventional subsidence surveys. Images capture data over large areas (hundreds of kilometers), and each pixel (data point) in an image quantifies the average displacement over an area of square meters. DInSAR data can have fairly high time resolution; imaging periods typically range from weeks to months.

Jan 7, 2020

By Kevin Saeler, Patrick Willaman

Utilizing automation is one way to improve competitiveness. Roof and rib bolting in underground coal mines has not changed significantly for more than 40 years. Most roof bolting is still a largely manual process involving high levels of staff carrying out repetitive work. Roof bolting statistically has one of the highest levels of underground accidents, including finger, hand, and arm injuries. Operators are exposed to falling objects and becoming entangled in roof bolting apparatus while roughly moving awkward 6-ft drill steels and roof bolts. It is estimated that over 25 million roof bolts are installed annually in the U.S. underground coal market with well over 1,500 operators involved in roof bolting on a day-to-day basis. Recently electrohydraulic roof bolting rigs have been installed to offer partial automation of the drilling cycle and the bolting cycle. The next stage is to provide a storage and loading system to allow full automation of fullcolumn resin roof bolts. This paper reviews the latest electrohydraulic roof bolting equipment and discusses the testing of a fully automated drill rig. Full electronic control allows each step of the roof bolting process to be recorded, providing a digital record of each installation, including hole depth, spin time, gel time, torque, and cycle time. Other benefits include monitoring of water pressure and flow, used to prevent blocked drill steels as well as digital fault finding. A fully automated roof bolting machine greatly improves operator safety and gives high-quality repeatable roof bolting with reduced cycle times.

Jul 1, 2023

By Jim Richards, Eli Choueiry, Brett Robinson, Amanda Elioff

The Los Angeles Metro Gold Line Eastside Extension (MGLEE) extends Metro’s light rail system to the densely populated and growing East Los Angeles communities. Much of the 6 mile alignment consists of at-grade track, but the project also features a1.7 mile underground segment in cut-and-cover and twin-bored tunnel structures. In light of past experiences with open shield construction, The Metropolitan Transportation Authority (Metro) specified, for the first time, use of Pressure Face Tunnel Boring Machines (TBM’s) to advance tunnels through soft ground. This paper describes the history of the tunnel design, construction management, and construction methods adopted that resulted in successfully completing the tunneling segment.

Jan 1, 2007

By F. Pagliacci

Retaining walls for the construction of underground urban infrastructures have to be executed considering the impact of a deep foundation job-site within an urban network. Traditional excavation systems, based on the use of grabs and bentonite mud, involve serious problems such as: the opening of trenches adjacent to existing buildings; the cleaning of the working area; the site installation for the production and storage of the bentonite mud; the transport and disposal of soil contaminated with bentonite mud. Alternative solutions have therefore been developed in order to overcome these problems. For temporary works soil consolidation methods, combined with the use of sheet piles, have been implemented, by a combination of traditional mixing methods and jet grouting systems to speed up the operations, consequently reducing the construction time. For permanent works two new techniques named respectively CSP (Cased Secant Piles) and CDW (Continuous Diaphragm Walls) have been studied, applied and tested.

Jan 1, 2000