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By W. Dresler

Since 1900, smelters have produced in Canada over 10 million tonnes of iron silicate waste slag containing significant quantities of nickel, cobalt and copper. The slag is reduced with aluminum and calcium oxide additions to produce a copper, nickel, and cobalt enriched alloy and an obsidian slag. It was found that the obsidian slag contained very low copper, nickel, and cobalt contents, indeed below 0.06% of each the base metals. These metals have been collected in a type of ferroalloy with up to 1.6% Cu, 2.1% Ni, and 0.7% Co. These alloys can be recycled according to standard procedures in base metal smelters. Surprisingly, the obsidian slag was found to display good cementitious and pozzolanic properties, which is a requirement for cement production. The strength producing properties of the obsidian slag are considered to be exceptional at the 28 day standard test age. In most cases, the obsidian concrete is characterized by significantly greater strengths than control concrete tests and concrete containing fly ash or blast furnace slag. Compressive strength data at 365 days for the obsidian concrete is impressive.

Jan 1, 2003

By Thomas Zukovich, Robert Morhard, Thomas Gelormino

The ExploTrack Explosives Tracking System is a sophisticated integration platform designed to track explosive products in both fixed locations and mobile environments globally, in real-time, on a 24/7 basis. The system utilizes active and passive RFID (Radio Frequency Identification Devices) installed within or applied upon explosives materials and explosives articles and incorporated within explosives packaging and logistic transport mechanisms. The system is designed for real-time inventory on an enterprise level and also across the globe providing explosives tracking, monitoring and explosives security from manufacturing throughout the logistics supply chain through use. The system can also track and monitor all known persons coming into contact with RFID enabled explosives materials and articles at the production level, at the magazine level, at the logistics level and to final use enabling a complete and real-time auditable chain-of-custody.

Jan 1, 2007

By Abani R. Samal

The Fe assay values from the diamond drill-holes within a magnetite deposit of magmatic origin are utilized in this study. Only assay data from the unoxidized magnetite mineralization was utilized. The data from the overlying hematite mineralization zone was not used. A threedimensional block model estimated using ordinary kriging (OK) is used for analysis purposes. To estimate the non-linear standard deviations (s) and the confidence intervals (CI) of block estimates a discrete Gaussian variogram model is used in this project. The change-of support coefficient (rv) and the block-support correction are used in the ?block-anamorphosis?. A new calculated value of rv is 0.7283, implies that its influence in the block-anamorphosis is not significant. The CIs are calculated from the block-gaussian variables; then back transformed to the raw values. At 95% probability, the CI for the kriged block estimates of Fe values are calculated using Gaussian kriged estimates of the Fe and the corresponding standard deviations (Gaussian). The results indicate that the block estimates with a high influence from relatively small amount of samples can be identified as high-risk estimates.

Oct 1, 2009

The introduction of legal certification of mine managers is a matter of history. It was introduced as part of legislation for mine safety. It has been said that such legislat- ion was written in blood. Like all legislation this legislation is divided into three sections; commands, obligations and sanctions. While legislation in all States on this subject is similar, the differences are great enough to have prompted the preparation of a Uniform Code by the Annual Conference of Chief Inspectors of Mines. This Uniform Code has not been adopted fully by any State to date. Legal certification of mine managers has made managers more aware of the requirements of the legislation covering their industry, legislation that reads as a summary on past accidents and methods of preventing them. While budding managers spend considerable' time in their early years in the preparation for certification, history has shown that the industry has benefited from their efforts. A better knowledge of the safety acts by the managers has produced safer operations, and a higher standard of management has raised the technical standards of mining operations to a stage where Australia can be proud.

Jan 1, 1980

By T. T. Chen, J. L. Jambor, J. E. Dutrizac

A reconnaissance study of the neutralization potential of 30 diverse minerals, 28 of which are silicates and aluminosilicates, has shown that most of these minerals contribute minimally to the neutralization potential (NP) in standard static tests. Feldspars in particular give low NP values and would not be expected to attenuate the acidity to any significant extent in acid rock drainage settings. The BET-determined surface areas of the minerals vary considerably, and the large surface areas of some of the pulverized samples have clearly affected the NP values even though the standard static-test protocol was used for the preparation of the samples. The low NP values of most silicates and aluminosilicates are in general agreement with the laboratory-determined slow dissolution rates for these minerals. The results suggest that, in the prediction of whether rocks will be acid-producing, the most realistic measure is that of the carbonate content. In mine wastes from metalliferous ore deposits, the contribution to the NP by the non-carbonate gangue assemblage is unlikely to be more than a token amount until well after the establishment of an acid rock drainage situation.

Jan 1, 2000

By G. Akdogan, S. M. Bradshaw, A. P. Van Wyk, T. Punt

This study investigated the performance of citric acid as lixiviant for cathode material from end-of-life lithium-ion batteries (LIBs). Black mass containing 84.2 weight percent MNC (LiNi0.45Mn0.4Co0.15O2) and 15.8 weight percent LCO (LiCoO2) material was leached at solid-to-liquid ratios of 20, 50 and 100 g/L. Leaching with 1.5 M citric acid, 2 volume percent H2O2 and a solid-to-liquid ratio of 20 g/L at 95 °C extracted 90 percent Co, 95 percent Li, 94 percent Mn and 94 percent Ni within 20 min. At the highest solid-to-liquid ratio of 100 g/L with 1.5 M citric acid, 10 volume percent H2O2 and 95 °C, 84 percent Al, 84 percent Co, 87 percent Li, 86 percent Mn and 96 percent Ni were leached after 40 min, producing a leach solution containing 0.68 g/L Al, 20.0 g/L Co, 6.0 g/L Li, 13.6 g/L Mn and 19.3 g/L Ni. Using stepwise addition of H2O2, instead of initial bulk addition, did not significantly improve the leaching efficiency but did reduce the required leaching time. Temperature control of the reactor was also more manageable with stepwise addition of H2O2, and evolution of gas was less vigorous. It was observed that the leaching efficiencies of Co, Li and Mn decreased slightly at solid-to-liquid ratios of 50 and 100 g/L, while the leaching of Ni increased slightly. The solution leached at 20 g/L could be stored for six weeks without any spontaneous precipitation. However, solutions leached at 50 and 100 g/L showed changes in concentration after one month of storage, suggesting that processes that have a large material throughput and use high solid-to-liquid ratios around 100 g/L must ensure that the solutions are not stored for extended periods of time.

Apr 1, 2025

By S. W. MILLE

GEORGE F. COMSTOCK,* Niagara Falls, N. Y. (written discussion?).¬I have recently had the pleasure of reading Mr. Miller's interesting paper, and would like to call attention to a reference to this subject which apparently has escaped his notice. It is an abstract of a German research on the subject of nitrogen in steel, and appeared in the Iron Age of Feb. 17, 1916, page 432. Photomicrographs of needles such as Mr. Miller found in his welds are given, and their identity is discussed. The conclusion reached is that the needles are slip lines due to the brittleness of the ferrite crystals caused by their absorption of nitrogen. The deformation necessary to develop the slips is supposed to be accomplished either in cutting or polishing the microsections or by cooling strains after welding. It seems very reasonable to expect that nitrogen would he absorbed by steel in either electric or oxy-acetylene welding, and the reference I have mentioned gives instances of many unusual structures resulting from the presence of considerable nitrogen with carbon in steel. But the nitrogen is .rapidly given off from steel by ordinary annealing in air, hydrogen or vacuum, and this would explain the disappearance of Mr. Miller's needles after annealing. I think the conclusion that the needles are cementite might well be revised in view of this German work on nitrogen.

Jan 5, 1918

By M Ali, E Satriawan, M Napitupulu, A Munandar

The Deep Mill Level Zone (DMLZ) panel cave mine is one of three active caving mines at PT Freeport Indonesia’s Grasberg Underground Mining Complex. The DMLZ mine is located at a depth of approximately 1,500-1800 m below the surface, making it one of the world’s deepest panel cave mining operations. This depth results in both high in-situ and induced stress that acts on the hard and massive rock mass, triggering rockburst conditions. As a result of the bursting conditions, ground support and maintaining the support capacity are an essential part of operating the DMLZ mine in an efficient and safe manner.

Apr 26, 2022

By FRANK COLE

THE territory covered in this discussion includes all the states west of the Mississippi river. Agriculture is expanding each year in this section, but until recent years the application of commercial fertilizers as an aid to crop production was not practised to any great extent. The use of commercial fertilizers has increased somewhat, but is still on a small basis as compared with the tonnages used else- where in the United States. During 1928 these western states used 665,100 tons of all classes of fertilizer as compared 'with 7,933,600 tons used in the whole United States; or this western area, compromising near- ly two-thirds the land area, uses about 5 per cent of the total fertilizer. To show how large a tonnage one state may consume, North Carolina for the year 192s used 1,349,360 tons of commercial fertilizer or about twice the amount used by 22 western states.

Jan 1, 1930

By Carl Zapffe

A Rise in less than ten years from obscurity into great prominence economically, tersely summarizes the history and status of the Cuyuna manganiferous iron ores. The Cuyuna district produces and ships mostly high-phosphorus iron ore, but the annual production of manganiferous iron ore is increasing rapidly and productions from individual mines are becoming more regular and more dependable as to grades and tonnages. This ore bids fair to become, shortly, the principal product of the district and is responsible for its present economic prominence. The iron ores of the district have been described, by the author and others, in many publications and will not be discussed here. Lately the manganiferous iron ores have been given some attention, but the range and variations of chemical composition of the ores, the principal physical characteristics of the ores and their deposits, the relative importance of the different ores and their possibilities in future developments, and the life of the respective reserves have not been discussed. It is impossible to give all of this information with the positiveness necessary for it to constitute a reliable guide for investment or even for future mine development. Each property and each party presents a special case and deserves critical consideration. We are dealing with special ores and always with a set of new conditions. Sufficient information of a general nature can be given, however, to indicate the reason for and the trend of the presently augmented developments in the district. In a great thickness of a big variety of sedimentary rocks, probably of Upper Huronion age, prevailingly of green, schistose phases of slaty and volcanic material intricately intermixed, lies a thin bed containing lenses of iron-bear ing formation. These lenses occur singly or in groups, thus causing the variation in the thickness of the formation; or they are separated at their ends and give rise to discontinuity or they overlap and display continuity with lateral offsets. Intense folding has added to the complications.

Jan 1, 1925

By J. P. Van Kleunen

9.3-1. Introduction. The demands of industry for handling materials at higher rates and at reduced costs have had a very significant effect on belt conveyor technology. Although the general appearance of the belt conveyor today is essentially the same as it has been for the past several decades, the similarity ends there. Each component comprising the conveyor system has been continuously improved through design and materials technology to enable present conveyor systems to operate at ever-increasing rates and reliability. For example, twenty years ago the strongest commercially available, fabric-reinforced conveyor belting had a tension rating of 50 lb per ply-in. Currently, fabric-reinforced belts are available with ratings of 350 lb per ply-in. and steel cable reinforced belting is available with tension ratings of 3000 lb per in. of belt width (3). These technological advances have therefore enabled the belt conveyor to not only attain acceptance as a preferred method for in-plant movement of bulk materials, but also to be used for long distance transportation of bulk materials, particularly in areas of adverse terrain. The information contained in this chapter is intended to assist the reader to make basic decisions regarding the use and application of a conveyor system. The design of an overland conveyor transportation system or an in-plant process conveyor is accordingly beyond the scope of this article. Many comprehensive technical works covering the design of a belt conveyor are currently available from the manufacturers of materials handling equipment (6, 7, 9, 11). The design handbook published by the Conveyor Equipment Manufacturers Association is particularly recommended (2). 9.3-2. Conveyor Capacities. One of the most important factors in determining the proper size of a conveyor system is the rate at which material must be handled. Although tables and charts are available to the conveyor designer to assist him in his selection of conveyor components, only the

Jan 1, 1968

By K. F. Unrug

The method of coal pillar design involves primarily two aspects, the geometry of the pillar and the strength of the coal. However, the strength of the coal has to be emphasized with respect to the entire pillar dimension rather than isolated strength values of coal samples taken and measured from different locations. The presently applied pillar design systems do not specify clearly what the coal sample strength really represents. The intention of this paper is to introduce the concept of seam strength as opposed to the current practice of using coal strength as a prime design criteria in the formulation of pillar calculations. Seams are most of ten composed of multiple layers of coal, partings, and bone in different configurations, changing within the vertical section of the seam even in relatively close locations. The difference in strength between the weakest and strongest component of the coal seam could be as much as five times or more. An experimental approach based on multiple compressive tests performed on coal samples from the Coalburg and the Warfield seams from Eastern Kentucky was undertaken. The analysis of the results lead to the conclusion that for pillar calculations both the weighted mean of the seam strength and the strength of the weakest stratum should be considered rather than the relatively vague aspect of coal strength The design of pillar dimensions based on the above mentioned aspects should assure a more realistic design performance.

Jan 1, 1985

By W. R. Purcell

An apparatus is described whereby capillary pressure curves for porous media may be determined by a technique that involves forcing mercury under pressure into the evacuated pores of solids. The data so obtained are compared with capillary pressure curves determined by the porous diaphragm method, and the advantages of the mercury injection method are stated. Based upon a simplified working hypothesis, an equation is derived to show the relationship of the permeability of a porous medium to its porosity and capillary pressure curve, and experimental data are presented to support its validity. A procedure is outlined whereby an estimate of the permeability of drill cuttings may be made with sufficient acuracy to meet most engineering requirements. INTRODUCTION The nature of capillary pressures and the role they play in reservoir behavior have been lucidly discussed by Lev-rett', Hassler, Brunner, and Deah12, and others. As a result of these publications the value of determining capillary pressure curves for cores has come to be generally recognized within the oil industry. While considerable attention has been directed toward the subject in an effort to provide a reliable method of estimating percentages of connate water, it has been recognized that capillary pressure data may prove of value in other equally important applications. This paper describes a method and procedure for determining capillary pressure curves for porous media wherein mercury is forced under pressure into the evacuated pores of the solids. The pressure-volume relationships ob- tained are reasonably similar to capillary pressure curves determined by the generally accepted porous diaphragm method. The advantages of the method lie in the rapidity with which the experimental data can be obtained and in the fact that small, irregularly shaped samples, e.g., drill cuttings, can be handled in the same manner as larger pieces of regular shape such as cores or permeability plugs. Based upon a simplified working hypothesis, a theoretical equation will be derived which relates the capillary pressure curve to the porosity and permeability of a porous solid, and experimental data will be presented to support its validity. This relationship aplied to capillary pressure data obtained for drill cuttings by the procedure described provides a means for predicting the permeability of drill cuttings. METHODS FOR DETERMINING CAPILLARY PRESSURES Several techniques have so far been employed in determining capillary pressure curves and these fall into two principal categories: (1) Liquid is removed from, or imbibed by, the core through the medium of a high displacement pressure porous diaphragm (2) Liquid is removed from the core which is subjected to high centrifugal forces in a centrifuge4,'. There are? however, certain limitations inherent in both methods. The greatest capillary pressure which can be observed by method (I), above, is determined by the maximum displacement pressure procurable in a permeable diaphragm which at the present time appears to be less than 100 psi. An even more serious limitation of the diaphragm method is imposed hy the fact that several days may be required to reach saturation equilibrium at a given pressure; hence, the time re- quired to obtain a well-defined curve may be measured in terms of weeks. Furthermore, to date, no suitable technique for handling relatively small, irregularly shaped pieces of rock, such as drill cuttings, has been reported and, therefore, measurements must be made, in general, on cores, or portions thereof. The centrifuge method offers the distinct advantage over the porous diaphragm method of arriving at saturation equilibrium in a relatively short time by virtue of the elimination of the transfer medium for the liquid. The calculation of capillary pressures from centrifuge speeds is somewhat tediousa, however, and the equipment required is fairly elaborate. While there exists the possibility that this method might be adaptable to the determination of the capillary pressures of cuttings, this particular ramification has not been investigated, as far as is known. In view of the limitations of the two principal methods for determining capillary pressures, the apparatus described in the following sections has been devised in order that difficulties previously encountered might be circumvented. MERCURY INJECTION METHOD FOR DETERMINING CAPILLARY PRESSURES Theory The methods described above for determining capillary pressures are characterized by the fact that one of the fluids present within the pore spaces of the solid is a liquid which "wets" the solid, i.e., the contact angle which the liquid forms against the solid is less than 90" as measured through that phase. For these "wetting" liquids the action of surface forces is such that the fluid spontaneously fills the voids within the solid. These forces likewise oppose the withdrawal of the fluid from the pores of the solid.

Jan 1, 1949

By W. R. Purcell

An apparatus is described whereby capillary pressure curves for porous media may be determined by a technique that involves forcing mercury under pressure into the evacuated pores of solids. The data so obtained are compared with capillary pressure curves determined by the porous diaphragm method, and the advantages of the mercury injection method are stated. Based upon a simplified working hypothesis, an equation is derived to show the relationship of the permeability of a porous medium to its porosity and capillary pressure curve, and experimental data are presented to support its validity. A procedure is outlined whereby an estimate of the permeability of drill cuttings may be made with sufficient acuracy to meet most engineering requirements. INTRODUCTION The nature of capillary pressures and the role they play in reservoir behavior have been lucidly discussed by Lev-rett', Hassler, Brunner, and Deah12, and others. As a result of these publications the value of determining capillary pressure curves for cores has come to be generally recognized within the oil industry. While considerable attention has been directed toward the subject in an effort to provide a reliable method of estimating percentages of connate water, it has been recognized that capillary pressure data may prove of value in other equally important applications. This paper describes a method and procedure for determining capillary pressure curves for porous media wherein mercury is forced under pressure into the evacuated pores of the solids. The pressure-volume relationships ob- tained are reasonably similar to capillary pressure curves determined by the generally accepted porous diaphragm method. The advantages of the method lie in the rapidity with which the experimental data can be obtained and in the fact that small, irregularly shaped samples, e.g., drill cuttings, can be handled in the same manner as larger pieces of regular shape such as cores or permeability plugs. Based upon a simplified working hypothesis, a theoretical equation will be derived which relates the capillary pressure curve to the porosity and permeability of a porous solid, and experimental data will be presented to support its validity. This relationship aplied to capillary pressure data obtained for drill cuttings by the procedure described provides a means for predicting the permeability of drill cuttings. METHODS FOR DETERMINING CAPILLARY PRESSURES Several techniques have so far been employed in determining capillary pressure curves and these fall into two principal categories: (1) Liquid is removed from, or imbibed by, the core through the medium of a high displacement pressure porous diaphragm (2) Liquid is removed from the core which is subjected to high centrifugal forces in a centrifuge4,'. There are? however, certain limitations inherent in both methods. The greatest capillary pressure which can be observed by method (I), above, is determined by the maximum displacement pressure procurable in a permeable diaphragm which at the present time appears to be less than 100 psi. An even more serious limitation of the diaphragm method is imposed hy the fact that several days may be required to reach saturation equilibrium at a given pressure; hence, the time re- quired to obtain a well-defined curve may be measured in terms of weeks. Furthermore, to date, no suitable technique for handling relatively small, irregularly shaped pieces of rock, such as drill cuttings, has been reported and, therefore, measurements must be made, in general, on cores, or portions thereof. The centrifuge method offers the distinct advantage over the porous diaphragm method of arriving at saturation equilibrium in a relatively short time by virtue of the elimination of the transfer medium for the liquid. The calculation of capillary pressures from centrifuge speeds is somewhat tediousa, however, and the equipment required is fairly elaborate. While there exists the possibility that this method might be adaptable to the determination of the capillary pressures of cuttings, this particular ramification has not been investigated, as far as is known. In view of the limitations of the two principal methods for determining capillary pressures, the apparatus described in the following sections has been devised in order that difficulties previously encountered might be circumvented. MERCURY INJECTION METHOD FOR DETERMINING CAPILLARY PRESSURES Theory The methods described above for determining capillary pressures are characterized by the fact that one of the fluids present within the pore spaces of the solid is a liquid which "wets" the solid, i.e., the contact angle which the liquid forms against the solid is less than 90" as measured through that phase. For these "wetting" liquids the action of surface forces is such that the fluid spontaneously fills the voids within the solid. These forces likewise oppose the withdrawal of the fluid from the pores of the solid.

Jan 1, 1949

By Philip Thompson

The Bureau of Mines investigated a selective flocculation-flotation technique to remove insoluble slimes from low-grade potash ore in a continous 45-kilogram-per-hour (100-pound-per-hour) process investigation unit (PIU). This research is part of the Bureau's program to improve resource recovery from low-grade ores. Results showed that 84 percent of the insoluble slimes were removed from an ore containing 5.5 percent water-insolubles and 14 percent K20 using a Bureau-developed, cationic flocculant-glycol ester-diesel oil reagent. Subsequent potash flotation recovered 75 percent of the potash in a cleaner concentrate assaying 56 percent K20. Concentrate leaching upgraded the product to market specifications of 60 percent K2O. An economic evaluation by the Bureau suggested that the rate of return on investment, after taxes, should be about 20 percent for such an enterprise.

Jan 1, 1980

By Joseph L. Uraco, Harry C. Verakis

The use of explosives in underground coal mines presents a potential risk for serious injuries and death to miners. Widespread disasters have occurred from the explosion of methane and/or coal dust initiated by blasting with explosives. Many of these disasters took place in the early 1900's when the use of black powder for blasting was prevalent. Historically, the investigations in the U.S.A. to develop and test safer explosives for blasting coal began in 1908 when a testing station was established in Pittsburgh, Pennsylvania. Since that time, great strides have been taken in the development of safer explosives. The use of safer explosives has significantly reduced blasting accidents in coal mines. Enactment of legislation, such as the Federal Coal Mine Health and Safety Act of 1969 and enforcement of regulations has also improved blasting safety. More recently, MSHA began a major revision of its regulations for blasting in coal mines. In 1988, MSHA published final rules for the approval and use of permissible explosives in coal mines. The approval requirements for explosives address testing and evaluation. The requirements include tests for sheathed explosives which represent a new technology. The use regulations provide increased safety protection for miners by including standards to address identified hazards. Major aspects of these standards, such as qualifications for blasters, multiple-shot blasting and the use of sheathed explosives are discussed.

Jan 1, 1992

By Nelson Rivera

El presente texto analiza la crisis económica y su relación con el Banco Minero. Para ello, se revisa las dos últimas recesiones económicas que tuvo el Banco entre 1975 y 1982, donde la crisis se agudizó por una caída en los precios de los metales y una inflación de costos que no pudo ser transmitida al precio de venta. Como consecuencia de ello, las empresas mineras que tuvieron préstamos, acusaron pérdidas en sus ejercicios e incumplieron en el pago de sus obligaciones. Como medida anti-crisis, el Banco Minero estableció comisiones de alto nivel para evaluar las situaciones y recomendar la dación de dispositivos legales que permitieron asistir a los Pequeños y Medianos mineros en la restitución de liquidez mediante préstamos sobre liquidaciones a precios deprimidos, Asimismo, generó la consolidación, refinanciación y moratoria de los clientes que estaban en suspensión de pagos de las obligaciones contraídas con el Banco Minero y la creación de líneas de crédito especiales para la Pequeña Minería.

Mar 1, 1985

By W. H. Emmons

ALTHOUGH gold is one of the rarer metals, it is widely distributed; it is found on all of the continents and in each of the grand metallogenic provinces of the earth. It is prominent particularly in the shield areas of the earth; these areas have produced a large part of the world's lode gold and in most of them gold lodes are more important than the lodes of other metals. The Scandinavian shield is the only one that has not produced much gold. Nearly all of the world's gold has been derived from lodes and from sands and gravels where gold placers formed by the destruction of lodes. The gold derived from magmatic segregations, from pegmatites and from contact metamorphic deposits is quite subordinate to that derived from auriferous lodes. The lodes include all veins and related deposits that are formed by hot waters that move along fissures or other openings and that deposit vein matter in the fissures and by replacement of the country rocks along the fissures. All of the shield areas of the earth are characterized by large areas of granitic rocks including granitic gneisses, granodiorites and other acid intrusives which here are included in the general term "granite." The granites are intruded into schists, ancient lavas and other rocks which here are designated as the "invaded" rocks. The granites are parts of what once were great batholiths: that is, they are the remaining portions of great deep-seated bodies that slope outward, have very irregular roofs and so far as known have no floors but extend downward to great though unknown depths. Some of them are scores or hundreds of miles across and contain islands or "roof pendants" of the invaded rocks at places where the roofs of the batholiths were low-that is, where erosion has not yet completely unroofed the batholiths.

Jan 1, 1932

By A. K. Debnath

Coal is the mainstay of Indian energy supplies. The many-fold increase in demand for coal puts a huge pressure on augmenting production, primarily from opencast mines. The increase in production necessitates heavy blasting in overburden and coal benches of opencast mines, which poses numerous challenges in carrying out blasting operations techno-economically. Presently, the consumption of industrial explosives and accessories in Coal India Limited (CIL) has touched a whopping figure of $350 million USD per annum and CIL will be spending approximately $1 billion USD between 2012?2013 to 2014?2015 for procuring explosives and accessories. This paper discusses some of key challenges faced in various mines of CIL during blasting, where blast instrumentation at the mine level will prove to a harbinger for practicing blasting engineers. Presently, the problem of scattering in surface detonators and down-the-hole detonators affects the blast performance significantly by increased blast induced ground vibration and reduced fragmentation. The paper discusses a case study carried out at Umrer opencast project of CIL to investigate the effect of scattering by using blast simulation techniques (i.e., JKSimblast) and observing the actual blast results with the help of a high-speed camera and multi-channel high frequency data acquisition systems. The fragmentation assessment was carried out by adopting Digital Image Analysis techniques and using the granularity software viz. Wipfrag. The blast instrumentation in the case study mine resulted in improvement in fragmentation of 12.76% and a direct savings in explosives cost of 28%. Geophysical techniques such as the seismic survey method have been used at Umrer Project, CIL to characterize the rock mass using the Multi Channel Analysis of Surface Waves system for selecting the explosives technoeconomically. The minimum deck thickness for mines of CIL using drill cuttings as decking materials should be 10 D, where D is the drill diameter. The estimation of blast performance on the basis of prescribed Powder Factor (i.e., kg of explosives per m3 of rock) is technically unscientific as the criterion of a good blast depends on many factors (i.e., good heave, loose muck, muck profile angle, ease of digging, uniform fragmentation). The present paper proposes a new methodology for techno-economic evaluation of blast performance. The new methodology involves four significant factors viz. specific energy consumed by the loading equipment, charge factor, productive yield and diggability index for assessing blast performance. The use of user-friendly, accurate, reliable, rugged and handy instruments in blasting will significantly improve mine productivity, equipment efficiency and economics. The improvement in blast performance, even by 1%, will provide a significant savings of $3.5 million USD per annum to CIL. It may be concluded with high degree of confidence that blast instrumentation at the mine level will influence the mine productivity and economics.

Aug 1, 2013

By James K. Stanley

PREFERRED orientation, particularly in irons and low-carbon steel, is a phenomenon that is both of considerable importance and theoretical interest. At times it is a liability and at other times an asset. In deep-drawing operations, preferred orientation is extremely undesirable because it necessitates trimming operations and increases scrap loss. Furthermore, oriented metals are likely to crack more easily than randomly oriented material because the forming of symmetrical and unsymmetrical shapes out of preferentially oriented metals and alloys increases the probability of rupture in regions of high stress, owing to differential ductility.1 In the electrical industry, on the other hand, preferentially oriented silicon irons are in demand for transformer application because of the improved magnetic permeabilities in the rolling direction.2 This phenomenon of preferred orientation in soft magnetic materials has been responsible for the tremendous improvement in transformer design and construction in recent years. Directional properties in metals have received a great deal of attention in the metallurgical literature,3-9 in which much of the information reported about orientation has been obtained by conventional methods, mechanical properties and X-rays. A wealth of data has been obtained and often at a great expenditure of time. The recent introduction of the magnetic torque measurements on ferromagnetic materials provides a very simple and rapid method of evaluating orientation. The judicious use of the method can supply important in- formation, but it should be borne in mind that such studies must be supplemented by X-rays, optical methods,10 and etch and pressure figures" to get a rational under- standing of the orientation phenomena. No claims are made that the magnetic torque of evaluating orientation will reveal the behavior of the metal in deep drawing. For this purpose the accepted tests for deep-drawing quality must be used. For a good drawing 'stock, which must have low impurities, desirable grain size, ductility, strength, hardness, good surface, random orientation, and good recrystallization behavior, it cannot be expected that any simple test will be satisfactory for appraising all the factors. The only factor on which the magnetic method can be used is orientation, which is, of course, of considerable importance. When directionality can cause a 10 to 15 per cent change in tensile strength and a IOO to 300 per cent change in tear length,12 it goes without saying that a reliable as well as rapid method for detecting these changes would be desirable. There are certain inherent advantages in testing orientation by the torque method: The method is rapid with the proper type of equipment; no elaborate preparation of specimens is required-it is only necessary punch or machine a disk of the sheet material and insert it into the testing device.

Jan 1, 1943