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By D. Lansburg

Electronic detonators are increasingly being used in today’s blasting in quarries, seismic, surface and underground mines. Electronic detonators offer several distinctive features over electric and non-el (shock tube) detonators including better timing accuracy resulting in excellent fragmentation and vibration control, field programmability and digital safety means. Because of the prerequisite electrical communications between the electronic detonators and the blasting machine, the layout or hook-up of these detonators can play an important role in obtaining the communication fidelity.

Jan 1, 2011

ALABAMA Alabama City.-Eddy, L. Altoona.-Cain, J. America.-Foreman, J. T. Anniston.-Foster, R. N. Ashland.-Sturdevant, J. C. Bessemer.-Ball, E. M. Calhoun, F. W. Maschmeyer, W. L. McKenzle, W. C., Jr. Birmingham.-Abbott, C. E. Aldrich, T. H. Aldrich, T. H, Jr. Ashton, J J.

Jan 1, 1923

By George. Petersen

"El trabajo refiere algunos aspectos del depósito de estaño en el yacimiento de Condiriquiña (Puno), como en zonas de Apurimac, Lima, Pasco, Ancash, Cajamarca del Perú. Se conoce que los principales depósitos de estaño provienen de los ramales cordilleranos de Bolivia, abarcando una serie de yacimientos. En vista de una posterior demanda del producto, fue necesario que el Perú inicie una exploración de este metal en territorios adyacentes a Bolivia. Sin embargo, las exploraciones no se concretaron más que a las inmrediaciones del lago Titicaca. Posteriormente se descubrió minerales de estaño en diversas partes de nuestro territorio,aunque que ningún depósito explorado tenga un resultado de valor económico-industrial considerable. El aspecto geoquímico del estaño no tiene relaciones con el fierro, cromo, silicio, careciendo de estaño en los depósitos líquidos magmáticos y en las rocas ígneas de naturaleza básica. Durante los procesos metalogenéticos el estaño se concentra y constituye un elemento característico de la cristalización residual; presentándose tanto en el alcance neumatolítico ácidocomo en el hidrotermal. En consecuencia, los depósitos de estaño son de origen neumatólítico, cuyas masas y filones de catiserita están asociados con un batolito de granito, de edad oligocénico. Así, las rocas encajonantes consisten en pizarras y cuarcitas de Ordovicito, se transforman en rocas greisen o ígneas. Finalmente, los depósitos estanníferos se clasifican según sus alcances genéticos en depósitos supergenos e hipogenos, los cuales se dividen en depósitos pegmatítico, neumalotílicos, de transición neumatolíticos-hidrotermales y los depósitos hidrotermales."

Jul 20, 1959

By Drupad B. Desai, Alexander Rosenbaum

In recent years, there has been an increasing use of two-pass tunnel lining system consisting of segmental unbolted expandable precast concrete initial lining and cast-in¬place concrete final lining in the United States. Used so far in soft ground tunneling performed under free air, it often includes a waterproofing or gasproofing membrane placed between the initial and final linings. This paper describes the utilization of this two-pass system for an extension of the Baltimore Metro, constructed in part under compressed air. It offers a description of the extension project, known as Section C; addresses the tunnel lining selection process and the design of the lining elements; examines the effect of the adopted lining system and tunneling technique on the design of the project's major structural components; and describes design modification instructions in order to accommodate constantly changing field conditions.

Jan 1, 1993

By H. McLeod

Introduction In the period from 1939 to the present, Canada has experienced a remarkable industrial expansion, rising to probably seventh in rank amongst world countries. In the early part of this period, the desperate need for military supplies unloosed tremendous amounts of capital for building new factories and for expanding and converting existing facilities. Mines, factories, and other divisions of the industrial economy bent every energy toward greater and greater output. The result was an 80 per cent increase in the volume of the nation's production within a period of four years, a truly remarkable accomplishment and one in which the mining industry had a very vital part. After the critical year, 1944, the tempo of industry eased off a bit, dropping approximately 20 per cent by 1946. At this time the prospects or post-war industry were clouded by monetary and political chaos in overseas countries, by trade restrictions, and by market uncertainties. There was, of course, a pent-up demand, both at home and abroad, for civilian goods that had been curtailed during the war and for capital equipment that had been destroyed. In the midst of this world-wide uncertainty, if anyone had ventured to predict that by the end of 1950 Canada's industrial output would be back to the 1944 level and humming along at nearly twice the best pre-war pace, he would have been considered rash indeed. Yet this has been the case.

Jan 1, 1951

By Kot F. Unrug

When reading different studies discussing trends in coal mining, it appears that a substantial expansion of output by the year 2000 is predicted, even in the most pessimistic forecasts. Depletion of shallow, easy-to-mine deposits is only a matter of time, and the future average mining depth will increase. The proportion of slope to shaft mines operated during the next decades will change in favor of the shaft mines. Since an increasing amount of shafts in new nine developments seems to be inevitable, it appears appropriate to focus more attention on shaft design criteria. Some valuable papers have recently been published (1) that emphasize geotechnical aspects of shaft design. In the discussion that follows some other aspects of design criteria will be evaluated.

Jan 1, 1984

A review of ground control procedures in Western Australian underground mines is presented. Geotechnical input into initial mine design and methods of ground control is rare. As a result, the frequency of unexpected rockfalls is comparatively high, with over three quarters of the mines adopting non-specialist ground control designs experiencing unexpected falls-of-ground. In contrast, mines that provide some level of specialist input into initial ground control design experience decreased rockfall frequencies.

Jan 1, 1992

By A Kondratiev, A E. Moiseev

Viscosity of oxide melts is one of the fundamental physicochemical properties that plays a crucial role in important technological and natural processes like slag flow, slag/metal separation, volcano eruptions etc. However, many oxides melt at extremely high temperatures and are highly corrosive in the liquid state, which makes experimental measurement of melt viscosity by traditional experimental techniques a difficult and expensive, if not unachievable, task. In this case it might be useful to employ other methods of viscosity determination such as modelling or simulation. In the present paper the shear viscosity coefficients of selected pure refractory oxides (CaO, MgO, Al2O3 and others) have been simulated at temperatures above their melting points via the classical molecular dynamics and compared to the available viscosity data (eg experimental viscosities, other model predictions) collected by the authors. The simulation has been carried out using the noncommercial molecular dynamics simulation package LAMMPS and the Born-Mayer-Huggins potential, which parameters for the selected oxides were taken from the literature. Several viscosity calculation techniques (the Stokes-Einstein and Green-Kubo equations, the so called Einstein relations, and the non-equilibrium molecular dynamics methods) have been applied to ensure a more reliable viscosity calculation. It has been demonstrated that the simulated viscosity of the selected melts agrees with the available experimental data. It has also been shown that the simulated viscosity of a number of the oxide melts investigated is close to that calculated by phenomenological viscosity models, which supports viscosity extrapolation from the corresponding binaries and ternaries, if no experimental data is present for unary systems. In general, it has been demonstrated that the molecular dynamics simulation could provide a reasonable estimation of viscosity if no other viscosity data is available.

Jun 19, 2024

By Rameshwar Sah, PK GHORUI, LR SINGH, SIVALINGARAJU BARISETTY, SHYAM YADAV

Fly ash is a by-product generated by the combustion of coal in thermal power plants. Its disposal is a major environmental concern for these power plants. Though a considerable part of fly ash is used in cement making and brick manufacturing, a substantial quantity remains unutilized. Bentonite is commonly used as binder in the micropelletization of process waste to attain the mechanical strength required for handling and transportation. The present paper deals with the partial replacement of bentonite with fly ash in the micropelletization process without affecting the quality of the micropellets. The mechanisms of both the binders are discussed. The bonding of particles by bentonite is a physical mechanism, while fly-ash bonding is a chemical mechanism. Silica and alumina are the major constituents present in fly ash along with lime. In the presence of water, the alumino-silicates and unhydrated lime present in fly ash undergo a pozzolanic reaction and form cementitious bonds, which hold the particles together. Use of fly ash as alternative binder for bentonite has cost benefits besides providing a better utilization option for fly ash.

By P. L. Ngwenyama, W. W. deGraaf

South Africa is one of the leading producers and exporters of coal globally. A significant amount of the country’s production is obtained from previously mined underground bord and pillar workings. This coal is in the form of pillars and remnants on the roof and floor of the old workings. The good quality coal pillars were left behind as primary support during underground bord and pillar mining operations. Due to the depletion of virgin coal reserves, the pillars and remnant coal are now removed using opencast mining rather than underground methods. However, the secondary extraction of pillars and remnant coal from the old workings using opencast methods entails some serious challenges that have a negative impact on the safety and productivity of the operations, affecting both personnel and machinery. If these risk factors and challenges are managed properly, then the opencast mining operations could remove the pillars safely at recoveries competitive with those of virgin coal operations. In this study we review the recurring challenges affecting opencast pillar mining by means of field investigations and consultations with experts at five opencast pillar mining operations, and evaluate the best practices used to combat these challenges. It was found that each mine has its own unique conditions and challenges.

Dec 1, 2021

By John D. Price

In the constant search for ways and means of improving the quality of coke and thus making its use at the blast-fornace more satisfactory and economical, it has become increasingly evident that the present laboratory tests do not show the full picture of a coke's value as a blast-furnace fuel. This fact was recognized by Dr. A. C. Pieldner thirty-five years ago: (Ref. 1) here is perhaps no phase of fuel technicology which has aroused more discussion or regarding which there is more difference of opinion than the properties of coke which make it most suitable for blast-furnaces and other uses." Dr. Fieldner followed this assertion with a statement to the effect that men who write on this subject today (1923) have, because of conflicting experimental evidence brought forth in recent years, far less positive opinions on the matter than did writers of some years past. One is led to wonder if these statements are not just as true now as they were when first made.

Jan 1, 1959

By E. H. Bentzen

The purpose of this paper is to explain the production of sand for glass manufacturing and the reasoning behind the sand specifications set by the glass industry. In order to discuss the production of glass sand, there is a need to understand what glass is and how it is made. Therefore this paper discusses glass, as well as sand beneficiation.

Jan 1, 1977

By B. M. Larsen

Jan 1, 1965

By W. R. Reed, D. E. Pollock, T. W. Beck, J. A. Organiscak, J. D. Potts

In underground continuous mining operations, ventilation, water sprays and machine-mounted flooded-bed scrubbers are the primary means of controlling respirable dust exposures at the working face. Changes in mining arrangements — such as face ventilation configuration, orientation of crosscuts mined in relation to the section ventilation and equipment operator positioning — can have impacts on the ability of dust controls to reduce occupational respirable dust exposures. This study reports and analyzes dust concentrations measured by the Pittsburgh Mining Research Division for remotecontrolled continuous mining machine operators as well as haulage operators at 10 U.S. underground mines. The results of these respirable dust surveys show that continuous miner exposures varied little with depth of cut but are significantly higher with exhaust ventilation. Haulage operators experienced elevated concentrations with blowing face ventilation. Elevated dust concentrations were observed for both continuous miner operators and haulage operators when working in crosscuts driven into or counter to the section airflow. Individual cuts are highlighted to demonstrate instances of minimal and excessive dust exposures attributable to particular mining configurations. These findings form the basis for recommendations for lowering face worker respirable dust exposures.

Jan 1, 2016

By Oswald J. Heinrich

(Read at the Philadelphia Meeting, February, 1878.) DURING the last twenty years much has been done to investigate and define the Mesozoic formation of the United States along the Atlantic States, as well as in the Territories. The investigations of Professors Hitchcock, Emmons, Hayden, H. D. Rogers, and those now in progress in connection with the geological surveys of Penn-

Jan 1, 1878

The building is a lofty, well-ventilated one of hardwood frame, with galvanized-iron walls and roof, and consists of five spans running north and south, covering a total length of 236 ft. Each span is composed of nine bays of 1:3-ft. centres, making the total width of the building 117 ft. The refinery is situated conveniently at a distance of 100 yds from the smelters. Through the third span of the building runs a 5-ton electric overhead travelling crane, of a 3-motor type, with a span of 29 ft. The crane runway extends over a railway line, which connects the smelters to the refinery. This crane is llsed for handling bullion, coal, melting kettles, lead pumps, &c. A 3-ton crane of similar type, but with a 50-ft. span, runs through the fifth span of the building and also extends over the railwav line alreadv mentioned. This crane is used to load the soft lead into railway trucks, or to stack lead awaiting shipment in the area covered by the crane's operations.

Jan 1, 1918

By Alejandro Delgado

El propósito de este trabajo técnico consiste en explicar cómo el modelamiento de dispersión atmosférica ayuda a identificar las áreas de influencia (directa e indirecta) y a establecer una red de monitoreo como parte de los Estudios de Impacto Ambiental (EIA) para proyectos mineros. Esta metodología fue utilizada en EIA elaborados por Knight Piésold y posteriormente aprobados por autoridades nacionales de Perú y Guinea-Bissau.

Sep 1, 2017

By J. Q. Ehrgott

INTRODUCTION The U. S. Army Engineer Waterways Experiment Station (WES), under sponsorship of the Defense Atomic Support Agency, has recently developed a unique dynamic high-pressure triaxial testing device (DHT). The device permits acquisition of both axial and lateral deformation data while undisturbed soil and/or rock specimens are subjected to various states of controlled impulsive-type stresses produced by varying both the axial stress and the radial stress rapidly with time. The device is used to develop controlled dynamic pressure pulses within the triaxial chamber fluid on soil or rock test specimens to 3 inches in diameter. Controlled dynamic axial pulse loads are delivered to the specimen by a piston driven by an existing pneumatic ram loader (SECO). The DHT consists of a triaxial cell and a pressure supply and decay system which permits the chamber pressure to be varied with time. Together the DHT and SECO operate in a testing program so as to provide time varying confining pressures and axial loads to test specimens at independently controlled but synchronized programmed rise, hold, and decay times. Rise time is defined as the time from zero load or pressure to peak load or pressure; hold time is the time of constant peak load or pressure; and the decay time is the time from peak load or pressure to zero load or pressure. The maximum dynamic confining pressure attainable is approximately 15,000 psi and the fastest rise and decay times are 3 millisecond (msec) and 20 msec, respectively. This paper presents a description of the DHT, the necessary support equipment, and details of the measurement system. Performance evaluation tests conducted on clay siltstone and a Cretaceous sandstone are presented since the results demonstrate some of the capabilities of the device and show some of its characteristics.

Jan 1, 1971

Blasting is a common practice in mining whereby solid rock is fractured, using explosives, to a more manageable size. The effectiveness of blasting influences a number of downstream activities such as shovel digability, crusher throughput and mill throughput. As the cost of explosives is relatively low compared to milling costs (mainly due to power consumption), blasting practices can be optimised so that the downstream processes are made more efficient, and an overall cost saving made. This is the basis of the Mine to Mill approach. The effectiveness of the blasting is influenced by two main factors, the blasting practices used (eg explosive amount and type) and the geology of the area. As the geology cannot be altered, the blasting practices must be refined to create optimum blasting. Kalgoorlie Consolidated Gold Mines (KCGM) Fimiston operation, located in the heart of the Kalgoorlie Goldfields is the largest gold mine in Australia. Mine to Mill at KCGM has had varied success, with initial positive indications being lessened by a number of factors, including the increase in the amount of voids.

Jan 1, 2003