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By F. P. Dewey

Recent discussions have furnished to the members of the Institute much information concerning aluminum and its applications. The present paper will be devoted almost entirely to the description of a process by which the metal is produced in the form of alloys. The characters which especially distinguish the Heroult process consist in electrolyzing a mass of molten alumina (Al2O3), and at the same time alloying the separated aluminum with a heavy metal, the heat necessary for the fusion of both the alumina and the alloying metal being supplied by the direct passage through the molten Al2 0, of an electric current of high amperage and low voltage. The process has been in active operation at Neuhausen in Switzerland for about two years. It is also in active operation at Froges in southern France. Both these locations were selected for this purpose on account of the presence of large and desirable water-powers. The apparatus consists of a carbon containing-vessel, which may be a single crucible for small operations, or may be built up of slabs or blocks of carbon for large and industrial operations. When built up of slabs or blocks, the whole is surrounded by an iron casing. In the earlier crucibles this iron casing was cast around the carbon, in order to secure close electrical contact. This, however, has been found unnecessary; and in the later crucibles the casings consist of plates bolted together, while pulverized carbon is packed between the carbon blocks and the iron. Electric conductors are united direct to this iron casing, and the current passes from this through the carbon lining to the interior of the crucible. By this

Jan 1, 1890

By J. F. McDonald

On December 8th of last year, the new St. Clair River tunnel was holed-through to Port Huron, Michigan. The tunnel, commissioned by the Canadian National Railway, was needed to replace an existing tunnel that had been built between 1889 and 1890, and had remained in continuous operation until the new tunnel was opened to traffic in April of this year. The original tunnel, after more than 100 years of service, was still structurally sound, but was too small to accommodate the double stacked container cars and other advances in the railroad's equipment that had developed over the years. Prior to the construction of the first tunnel, all freight was barged across the river. It was a slow, expensive process, which in winter was sometimes impossible. The nineteenth century tunnel was built in twenty months, utilizing two shields that mined to the middle from each end. The lining, which is still in excellent condition, consisted of bolted, cast iron segments, with an O.D. of 6.4 meters. It was the first sub-aqueous tunnel built in North American, and it's use of compressed air under the river and hydraulic power on the shields may also have been firsts. The digging was done by hand, and the muck hauled out by mule drawn wagons. Boulders and methane gas were reported to be a constant problem during the drive, and compressed air sickness was common, but when the two shields came together in August of 1890, it was reported that the alignment was within 6 mm. The new St. Clair River Tunnel was constructed for basically the same reason as the original. The larger equipment which the railroad is using today would not fit through the old tunnel, and once more they were forced to ferry the cars across the river.

Jan 1, 1995

By Robert F. Shurtz

When an ore deposit is evaluated on the basis of core sampling, questions always arise as to how much weight should be given the various sample grades and how the deposit should be divided into specific volumes assigned to corresponding grades. For a tabular deposit it is customary to use the so- called zone-of-influence. This zone is usually de- fined as the polygon in the plane of the deposit having corners halfway between a given core drill intersection and each of the nearest neighboring intersections. The volume of the ore in this polygon is assigned the analysis obtained from the drill core taken at the intersection. In massive or irregular deposits, volumes of various shapes may be defined with respect to the locations of drill core samples. These volumes may be regarded as three-dimensional zones-of-influence; the theory involved in assigning the values of the central analyses to the ore in the volumes is the same as that used in the case of a tabular deposit. The zone-of-influence method was used in evaluating one of the magnesite deposits at Gabbs, Nev.1-3

Jan 10, 1959

AN earthquake caused an upheaval in Japan, started fires which destroyed large parts of Tokio, Yokohama and Hakone, and with tidal waves and other consequences extinguished some 68,000 lives and much property right at the beginning of September." Also on Sept. 1, the Italians, offended by the murder of members of the Albanian frontier commission by Greeks, occupied the Island of Corfu, which was viewed as an act of war by Italy against Greece. An appeal by the Greeks to the League of Nations was flouted by the Italians. One of the consequences of these affairs was to throw discredit upon the League of Nations and to excite doubts whether it would be able to survive. On Sept. 19, Greece made the formal apology to the Allies collectively and following that the Italians with-drew from Corfu. During this month also the embroilment between Italy and Jugoslavia over the matter of Fiume came again into prominence. In Bulgaria there was a communist uprising which was promptly put down by the government. The whole country was put under martial law. On Sept. 13 there began a military revolution at Barcelona, in Spain. On Sept. 14 the king of Spain accepted the revolution and charged the leader with the formation of a new government. Cosgrave was reelected president of the Irish Free State, without there being any disorder. Great Britain paid the remainder of her silver debt to the United States, thus writing finis to the Pitman Act. The position of Germany went from bad to worse during September. The mark has become valueless and the business that is being conducted is largely on a gold basis once more, in terms of dollars and pounds sterling. Chancellor Stresseman announced Sept. 24 that the German government had decided to abandon pas-sive resistance to the French and Belgians immediately and unconditionally.

Jan 10, 1923

By M. P. Boss

Of the two methods of mechanical reduction—that of percussion and that of abrasion—it is not easy to say which was first employed by primeval man. The stone hammer and the flat or hollowed stone used for grinding are found together in the remains of prehistoric periods. But the use of the maray, or bucking-stone, developed from the hammer, was probably introduced later than that of crude millstones. Diodorus Siculus, the Roman historian of the first century B. c., mentions such millstones as used in the mines of Egypt to pulverize material which had been previously broken in a mortar. The invention of the arrastra for fine grinding is declared by some authorities to have been made by Bartolomeo de Medina, at Pachuca, Mexico, about A. D. 1557—which is quite probable. Being the first to amalgamate silver on anything like a business scale, he must have felt the necessity for oregrinding apparatus of greater capacity than the old primitive millstones; and the arrastra was thus the natural successor of the millstone. It is very unfortunate that the archives of Pachuca, which has made so much history in ore-treatment, were destroyed in some one of the many insurrections for which, also, the place is renowned. The first application of the stamp to the crushing of rock is asserted by some writers to have been the invention of a Saxon nobleman named Von Maltitz, about the year 1505. Better authenticated reference, however, is made to one Paul Gronstetter, a native of Schwarz, and called an ingenious worker, who, in the year 1519, established at Joachimsthal a process of wet stamping and sifting. Two years later, a larger plant was established at the came place. It is said that he had previously introduced the same device at Schneeberg. How much of the invention was due to Gronstetter is not certain;

Jan 1, 1902

By W. C. Phalen

During the search for deposits of soluble potash salts in the United States, carried on by the United States Geological Survey, much information was collected on the salt resources and industry of the United States. The more important features of the information thus gathered, compiled, and digested may be classified under five headings, as follows: 1. Geology of the salt deposits of the United States. 2. Theories relating to the origin and formation of salt deposits. 3. Chemical composition of saline materials in the United States, principally rock salt and natural and artificial brines. 4. Statistics of salt production in the United States. 5. Technology of salt production. The first four items are not discussed in this report, but their treatment will comprise a separate report published by the Geological Survey,a which will supplement this report, relating to salt-making processes, and will describe comprehensively the salt resources of the United States. Persons desiring a copy of that report should apply to the Director of the United States Geological Survey, Washington, D. C.

Jan 1, 1917

By K. C. Sclater

GAS as a factor in the efficiency of oil production, might be a better title for this paper as it deals in general with the significance of the gas-oil ratio as an index of the efficiency of oil production and briefly discusses oil production methods with reference to the gas-oil ratio in wells, particularly during the early life of a field. In the recent hearings held at Washington before the Federal Oil Conservation Board the fuller utilization of the energy contained in the gas occluded in or associated with the oil underground was stressed by some of the speakers when referring to greater ultimate recovery of oil. One speaker commenting on this point said in part, "There is ample evidence indicative that if the gas associated with the petroleum in our fields were conserved and elevated gas pressure maintained in the oil sands during their productive life, the ultimate production of oil could be greatly increased."

Jan 1, 1926

By W Medina, G Angulo, A Anani

A current challenge faced by the mining industry is solving the integrated transition mine problem (TMP) that maximizes the net present value (NPV). This study aims to develop an optimization framework capable of solving the TMP. The problem is NP-hard and therefore computationally intractable. Three ad hoc approaches – Exact solution, Benders’ decomposition, and Benders’ decomposition with Bienstock-Zuckerberg (BZ) algorithm – are compared for different scheduling periods. The TMP is formulated as a mixed integer linear programming model, implemented in Python, and solved with the Gurobi optimizer. The results showed that Bender's decomposition with the BZ algorithm outperforms the other approaches in execution time, computational cost, and feasibility to address large problems in exchange for a marginal cost in the quality of the NPV obtained. In addition, the probability of finding the optimal point of transition is higher regardless of the number of feasible crown pillar locations evaluated. This is achieved through the optimality cuts proposed in the algorithm.

Jun 25, 2023

By Rudolph G. Wuerker

The progress made in testing the strength of rocks and minerals as they are encountered in mine operation is reviewed. An attempt is made to correlate these physical measurements with abrasive hardness, grindability, and behavior in comminution on one hand and fracture of rocks in pillars and roof control on the other. THIS paper reviews the progress made in testing the strength of rocks, ores, coal, salts, and other minerals as they are encountered in mine operations. It attempts to correlate the results of these physical measurements with technological properties more useful to the mining engineer: abrasive hardness, grindability, and behavior in comminution on one hand, and roof control, fracture of rocks in pillars, and mining methods with controlled caving on the other. In the following pages, the materials discussed will be referred to as rocks. Basic to rock mechanics and comminution are the problems of strength, elastic behavior, and failure, common to all brittle materials. A distinction will be drawn as to theoretical and applied research, and discussion of the progress made in each field will include test data obtained by the U.S. Bureau of Standards,1-1 the U.S. Bureau of Mines," the Iowa Engineering Experiment Station,"." the Committee on Geophysical Research at Harvard University,'" Basic Industries Research of the Allis-Chalmers Manufacturing Co.,11,12 by Philipps,13 and by Mueller," to name only a few. With refinements of testing methods and increased standardization. more useful and more comparable results have been achieved. This is especially important in testing a material like rock, as the inherent heterogeneity demands careful and exacting procedures. New measuring procedures that appear to supersede well known standard methods have contributed to faster and less costly testing yet have introduced new concepts, with implications as to comparability of results which must be watched. Reference is made to the sonic method for determining elastic properties," to be discussed in detail below. Basic Investigations Historically, all work in the field has started with the simplest determinations such as those for crushing strength, abrasive hardness, and grindability. These serve the limited objectives in the researcher's field of specialization: building construction, road ballast, roof control in mines, comminution, and seismic prospecting. Occasionally, fundamental properties like the modulus of elasticity E and Poisson's ratio v have been determined with the idea that they might have some bearing on the technological properties of the material under investigation. But it was not until the work of Philipps,13 of Harvard University,'" and of the U.S. Bureau of Mines"' that sufficient basic data were collected to allow researchers to go beyond the technological test and find the fundamental laws behind the behavior of rocks in mine and mill operations. The properties to be looked for are those that describe the elastic behavior of any material, the modulus of elasticity E and Poisson's ratio v being the ones determinable with least difficulties. Only two such properties are required to compute any other property such as the shear modulus, the modulus of rigidity, and the bulk modulus, all of which are related to each other according to well known equations of the theory of elasticity." In spite of their heterogeneous character, all rocks tested have possessed elastic properties. This does not mean that rocks of the same type always have the same modulus of elasticity, which varies exactly as the crushing strength or any other physical property of a rock can spread over a wide range. This has been explained by imperfections of the material always found in rocks, but to some extent this scattering of data is caused by inaccuracies inherent in the testing methods. Modulus of Resilience, a Criterion of Failure Increased availability of E values should allow us to test the validity of the quantity of strain energy theory which has been used in the solution of roof control problems by Philipps13 and by Holland.'" Recently Bond and Wang12 have applied this theory to explain the failure of an elastic material in comminution. Actually it is a very old theory, proposed as far back as 1885 by Beltrami.16 By its assumption the condition of yielding is determined by the term S2 M, = — x volume. Here M, is the modulus of 2E resilience, and its dimension is inch-pounds per cubic inch, that is, work per unit volume. Its numerical value is equal to the area under the stress-strain diagram. In the foregoing equation S is the yield stress (in psi) in tension or compression, whatever the case may be. E, the modulus of elasticity, is in psi. The great appeal of Beltrami's concept of stored energy lies in the fact that the two properties which seem to influence failure most, strength and elasticity, occur in the formula for the modulus of resilience. As an illustration of this, the moduli of resilience in compression of some typical materials tested by the U.S. Bureau of Mines" have been plotted in Fig. 1. The sample of concrete of conventional mix is shown only for the sake of comparison. Its determination was made in the Department of Mining and Metallurgical Engineering, University of Illinois. The values of the moduli of resilience of the various specimens in the plot are:

Jan 1, 1954

By R. W. Smashey, B. J. Piearcey

The structure, composition, and morphology of the carbide phases present in the nickel-base superalloy, Mar-M200, hare been determined and three carbide phases observed. The MC carbide is a solidification product, and the M23 Co and M6C carbides are both prod~icts of solid-state precipitation. The identity of each phase usas determined by both X-ray and electron-diffraction techn~ques. Compositions of all three carbides were studied using the electron beam micro-probe analyzer and by unalyszs of electrolytically extracted residues. Optical and electron microscopy were employed in order that the time/temperature -dependent behavior of the carbides might be observed. Supplementary studies were completed on thin foils and oriented single crystals to determine the mor-phology and orientation relationship of each phase with that of the matrix. MAR-M~OO* is a high-temperature, creep-resistant superalloy designed for use in the as-cast condition. The "as-cast" microstructure consists of a solid-solution matrix, referred to as gamma (y), which contains a general, coherent precipitate of the inter-metallic Ni3(A1,Ti) referred to as gamma prime (?). As a result of dendritic segregation during solidification, a degenerate, spherulitic ? -?' eutectic constituent is present at the grain boundaries and the in-terdendritic regions, which is nucleated by the y on the dendrite tips. A primary carbide phase, a solidification product, is also present at the grain boundaries and in the interdendritic areas, and an additional carbide appears at the grain boundaries as a fine discontinuous precipitate. The alloy is particularly susceptible to heat treatment. For example, the mechanical properties of the columnar grained mater- ial are substantially improved by solution heat treatment, followed by an intermediate temperature age. Metallographic examination of heat-treated material reveals, however, that exposure to elevated temperatures has a marked effect on the microstructure of the alloy; in particular, it is observed that precipitation of considerable amounts of various carbide phases occur. The following investigation was carried out to determine the morphology, composition, and behavior of the carbides in Mar-Ma00 as an aid to the determination of their effect on the mechanical properties and stability of the alloy. THE PRIMARY MC CARBIDE The MC carbide phase appears in the interdendritic interstices and the grain boundaries. In directionally solidified Mar-M200 the carbide appears as very small particles in the chilled region, Fig. l(a), whereas in material less affected by the chill, it becomes larger and develops a dendritic morphology, Fig. 1(b). Step polishing of metallographic specimens from this region shows that in directionally solidified material the individual carbide dendrites are connected in a dendritic network within the metallic interdendritic interstices, whereas in material from the chilled region and in conventional Mar-M200 they are discontinuous, isolated dendrites. No orientation relationship exists between the primary carbide and the matrix.

Jan 1, 1968

By P. Talonen

Since the last Iron Control in Hydrometallurgy Symposium in Montreal in 1996, the Kokkola zinc plant has increased its capacity from 175,000 t/y to 280,000 t/y by installing an atmospheric concentrate leaching process, which has also affected iron control in the leaching circuit. Major changes have been made at the jarosite residue pond; a subterranean plastic wall reinforced with bentonite and cement has been built around the pond. A new water collecting system that is used for groundwater level control in the pond area was installed. With these two investments in the pond area, it is now possible to prevent any seepage flow from the pond into the surrounding environment. Water pumped from the residue pond is treated in the water treatment plant. This paper describes the behavior of iron in Kokkola's current leaching processes. The treatment of the jarosite, the improvements to the residue pond and the water treatment process are also described.

Jan 1, 2006

By W. A. Backofen

THE preferred orientations, or textures, resulting from many of the various methods for testing and forming metals have been the subject of numerous investigations.1,2* Despite this large amount of work, however, only a few limited studies have been made of the texture that is developed by torsional deformation. Ono3 found that in severely twisted wires of copper and aluminum a [Ill] direction lies parallel and a [1101 direction perpendicular to the longitudinal axis of the wire. Sachs and Schiebold4 have reported that a double-fiber texture exists in a twisted aluminum wire with both the [Ill] and [loo] directions parallel to the axis of the wire. Twisted iron wires have also been examined by Ono.8 Both the [1101 and [1121 directions were reported as parallel to the axis of the wire. Goss5 concluded from a study of twisted rods of a low-carbon steel that the preferred orientation existing at fracture is quite complex, but that many grains have a [1101 direction parallel to the axis of the wire. In addition to the earlier experimental work, some suggestions have been made about the possible nature of the torsion texture. These suggestions are based on the results of many experiments which indicate that the cold-working texture of a particular metal is largely determined by the geometrical change in shape that the metal undergoes during plastic deformation.1,6 Hibbard and Yen7 have considered the problem of deformation textures and have presented an analysis which is able to explain why equivalent changes in shape should yield similar textures. Therefore, a knowledge of the principal strains associated with torsional deformation would seem helpful in the interpretation of the torsion texture. The necessary analysis has been made of the state of strain in an element of metal lying in the surface of a cylindrical rod or tube that has been subjected to pure torsion.8,9 This analysis shows that the directions of the principal normal strains rotate continuously within a torsion specimen while it is being twisted. After the first infinitesimal amount of twisting, these directions make angles of 45" with the longitudinal axis of the bar. They rotate from this position as twisting proceeds, and after an infinite amount of twisting, the direction of the principal tensile strain is perpendicular, and the direction

Jan 1, 1951

By D. Johansson, C. San Miguel, U. Stenman, N. Petropoulos

Blasting is a commonly utilized method in civil engineering projects and mining operations. Ammonium nitrate-based (AN-based) explosives are the most efficient explosives today in terms of handling and performance. However, a side effect is the production of gases. The reduction of these gases plays an important role in the safety and environmental aspects in the working place. Therefore, optimizing the recipes of explosives is vital for minimizing the environmental impact and increasing performance. The aim of the project is to provide results and recommendations on the use of emulsion commercial explosives to support the Swedish mining industry and tunnel-contractors as well as the explosives manufactures. The approach was to test various recipes of civil emulsion explosives to investigate the generation of toxic fumes (CO, CO2, NO, NO2 and NOx) during their detonation. To further increase the knowledge of the influence of different additives, ammonium nitrate prills were added in various percentages. The experimental configuration consisted of magnetite mortar cylindrical specimens with a 50 mm borehole at their center, filled with emulsion explosive. Several tests with different emulsion compositions regarding ammonium nitrate additives (10%, 20%, 25%, 30% and 35%) were carried out in a blasting chamber. The measurement equipment was composed of a flue gas analyzer. The instrument was meticulously cleaned after every test, as well as before and during the tests due to condensation (high humidity and dust) at the inlet of the instrument. The emulsion was manually sensitized with microballons and pumped into the cylinders to ensure lack of bubbles, which could introduce inhomogeneities. The acquired gas concentration data was complemented with temperature, humidity, and VoD measurements. The results showed a linear increase of nitrogen gases as the percentage of ammonium nitrate prills increased. On the other hand, carbon gases had a relatively low coefficient of determination. The VoD data showed a behavior that can be described with a simple quadratic equation.

Jan 1, 2024

By M. Rosales

By a physical and mathematical modeling, the behavior of the tri-dimensional waving, and the movement of the gases at the Teniente Converter was studied. The mathematical model considers the condensed phases of white metal and slag, along the gas phase, and includes the k-e model for the turbulence description. Both the physical model and the mathematical model allow to conclude that from a fluidynamic stand point the Teniente Converter clearly can melt 3000 tpd of concentrates. Also, both models are suitable to predict the slag fluidynamics and its spacial distribution inside the Teniente Converter, and the splashing in the tuyere zone as well.

Jan 1, 2006

By Oda Y, Hashiuchi M

In the smelting section, flexible fuels such as coal or coke are used in place of heavy fuel oil in order to utilize energy sources more efficiently. Heat recovered from the off gas of the furnace has been converted by the waste heat boiler into steam, which is used for self power generation and for heating or maintaining various temperatures. The amount of the recovered steam in the smelter is currently increasing due to maximum utilization of powdered cokes. The heat source required to maintain the temperature of the electrolyte in the tank house is electric power and steam. However until recent year this steam was provided by its own heavy oil combustion type boiler in the tank house since the amount of steam consumed in heating the electrolyte is large. Though experimental work over the last few years has shown the advantages of reducing steam in the tank house by fully covering the cell, the implementation of the full cover can lead to other operating problems. However various improvements, mainly the covering of the cell with a simple device, have led to greatly reduced steam consumption. As a result, steam for the tank house is now provided by the waste heat boiler only bringing more efficient energy usage.

Jan 1, 1987

By V. V. Trusova, Shiyrav Gandandorzh, K. V. Fedotov, V. A. Domracheva

"In Russia, 1.1 million tons of mercury-containing waste are stored. The amount of mercury in soils and heaps of industrial enterprises is estimated at 3000 tons; in dumps, concentration tailings, sludge dumps of the gold mining industry up to 6000 tons have been accumulated. Mining is one of the main sources of mercury emissions in the natural environment that poses a real threat to the natural environment. At present, the process of amalgamation is prohibited and not applied in gold extraction. The application of amalgam technology in gold mining led to the accumulation of highly toxic products in the form of gold-bearing amalgam and metallic mercury, with a mercury content of dozens and even hundreds of times greater than the maximum permissible concentration for soil (1). Therefore, mercury-containing tailings constitute an ecological hazard to the environment. According to published data, at waste storage sites of industrial enterprises, up to 50 tons of mercury enter soil annually, and up to 3.5 tons pollute the air. At the same time, mercury-containing waste due to the reduction of the country's mineral resources is an additional source of mercury. Therefore, it is necessary to recycle mercury-containing waste. INTRODUCTION Paperobjective: demercurization of technogenic raw materials (amalgamation tails, discharge outlets of tailing dumps) to be recycled. Under natural conditions, the mercury usually migrates in the form of three most common compounds: elementary mercury (Hg); mercuric mercury ion (Hg+2); methylmercuryion (Hg (CH3) +. Chemical compounds Hg (II) are found in natural conditions much more often than Hg (I).The authors propose to conduct demercurization of technogenic raw materials (mercurial tailings) in two stages. At the first stage, the mercury in the form of small balls, the finest particles (drip mercury) can be extracted by applying the gravitational method. We propose a method for centrifugal processing of crushed waste in the apparatus of Itomak company, Novosibirsk, as the basis of the technological process for mercury recycling. The extraction of metallic mercury out of mercury-containing waste into commercial products, according to the technological characteristics of the Itomak apparatus, reaches 86.0% (2, 3). At the second stage, the extraction of mercury out of technogenic raw materials is performed applying a sorption method and using carbon sorbents based on fossil coals. Hard coal of the Kuznetsk Basin has been already used for industrial production of active carbons (carbon sorbents) of the KAD-iodine type, which is one of the prerequisites that determine the choice to use it for the aims of this study."

Jan 1, 2018

By H. D. B. Wilson, W C. Brisbin

The Thompson-Moak Lake nickel belt lies along the root of a Precambrian mountain range of the island-arc or alpine type. This range coin-. cides with the boundary between the Superior and Churchill blocks of the Canadian Precambrian shield. The nickeliferous peridotites and nickel ores occur along a negative gravity strip, which also coincides with strong thrust faulting and the axis of greatest deformation of the mountain range. Similar structures and highly nickeliferous peridotites occur in present-day island arcs. Much of the belt is covered by Paleozoic rocks, but a length of 270 miles may be explored by present-day methods. Nickel deposits have been located along 60 miles of the belt. The length of the favorable structure and the size of the known deposits suggest that this will be one of the world's major nickel regions. The regional gravity anomalies, which consist of a branching negative strip bordered by two positive strips, are best explained by major warps of a crust consisting of a granitic and basaltic layer. The ore deposit

Jan 1, 1961

By Árpád B. Palotás, Adel F. Sarofim, John B. Vander Sande, Paolo Ciambelli, Lenore Rainey

"The evolution during oxidation of the internal structure of soot and carbon black particles was studied using high-resolution transmission electron microscopy (HRTEM) and an image analysis system. Increasing ordering to the carbon structure with increasing oxidation is observed. Measures of the increased order are increases in the fractional coverage of a cross section of the particles with a layered structure, a decrease in the mean interlayer spacing, and a decrease in the spread of the interlayer spacing. The changing structure of the carbon black impacts its properties, such as the rate of oxidation.There is considerable interest in the study of the structural changes of carbonaceous materials as a function of oxidation. Davis et al.1 measured the variation of carbon dioxide surface area of various coals as a function of residence time in a flow reactor. HRTEM measurements revealed that crystallite dimensions and interlayer spacings are altered by combustion. Ishiguro et al.2 showed that oxidation alters the structure of diesel soot. The aim of our current research is to develop a better understanding of the microstructural reordering of carbon blacks with implications to their properties. The carbon blacks used in this research have already been studied and their reactivities as a function of oxidation measured.3The methodology used in this work has already been described in detail elsewhere.4 This paper presents an application to quantify the structural changes of carbon black particles as a function of oxidation and graphitization. The technique used is based on the use of HRTEM (high-resolution transmission electron microscopy) and computational image analysis.It is well-known that carbonaceous materials like graphite, soots, coals, chars, etc., possess characteristic structural appearances which can vary from mostly random or amorphous to a perfectly ordered graphitic crystalline structure. The carbon structure has been variously described as turbostratic5 or as crumpled sheets6 to indicate that parallel layering, reminiscent of graphite, is observed over dimensions of nanometers but that these planes or crystallites show disorder over larger scales. The degree of order of such structures is strongly dependent on the thermal treatment of the material as well as the composition of the source of the carbonaceous material. The value of electron micros¬copy in studying the morphology of such materials has been well established,2,7,8 although only a few attempts toward quantification have been made.The sample observed was carbon black CB330 from De¬gussa. One set of carbon black samples were oxidized in a thermo-gravimetric analyzer (TGA) in air at 575 0C, so that the conversion varied from 0 to 96%. Another set of carbon black samples were graphitized (Graphpac-GB by ALLTECH) and then oxidized in the TGA at 680 °C until 92% burnout was reached. The latter samples are called GB 0% and GB 92%, respectively.For the HRTEM observation a small portion of each sample was ultrasonically dispersed in ethanol. The suspension was deposited dropwise on a copper TEM grid coated with a lacey carbon film. The examination of the samples was carried out on areas that extend over the holes in the supporting film in order to avoid interference from the amorphous carbon background film An oriented gold crystal was used as a calibration standard and subjected to the same techniques as the carbon black samples."

Jan 1, 1998

The Northside Storage Tunnel Project in Sydney includes over 20 km of TBM driven tunnels, over three km of declines and major caverns and pump rooms. The paper describes methods used for design on the project. Emphasis is given to the refinement of the use of empirical rock mass classifications, and to the use of discontinuum numerical methods. The use of empirical rock mass classifications in Sydney sandstone has usually led to conservative design because the systems are based on a random orientation of joints in the rockmass. Because the joint sets are usually oriented in a way that is beneficial for tunnelling, limits must be placed on the parameters used in the classifications system. The paper discusses these limits and the derivation of the parameters. The use of numerical methods in Sydney sandstone is discussed. Continuum methods have their uses, but discontinuum methods are preferred. The use of UDEC has been validated against a previous project, the New Southern Railway. Recommendations are given for UDEC models. In Sydney's geology, so advantageous for tunnelling, the challenges of this project have been to make the best use of the good conditions, while maintaining safety for the workforce and the future operators of the project.

Jan 1, 1999

By P. Mousset-Jones

The USBH Mining Systems and Ground Control Generic Research Center funded a project leading to the improved planning of airflow and refrigeration in underground mines experiencing hot working conditions. The project was broken down into approximately five phases: 1. Visiting some of the known hot mines in the U.S. and sending out a questionnaire to determine other mines which might be experiencing hot working conditions in the future. 2. Choosing two mines in which to conduct measurements to determine the insitu rock thermal conductivity and diffusivity, and comparing these values with laboratory determined values. 3. Investigating computer programs available for mine climate simulation, and testing these programs with case study examples from the two mines where the rock thermal properties were measured. 4. Considering improved ways of estimating the wetness factor and experimenting with the use of heat flux meters to more directly measure the rock heat inflow into the airstream. 5. Applying the results of these investigations to simulating the climate for future mine development and production areas at the two- mines. The project is approximately two thirds completed. At the time of writing, the insitu measurements at one of the mines are still being recorded. This paper will be describing the procedures and results of the insitu rock thermal property measurements, and give a brief description of some of the simulated results obtained for a mechanised cut and fill stope case study from the Homestake Gold Hine in South Dakota.

Jan 1, 1985