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Train services through the Channel Tunnel linking Britain and France where scheduled to be fully restored in February 2009 following several months of repairs after a major fire in the tunnel on Sept. 11, 2008. A lorry caught fire on a shuttle train carrying heavy goods vehicles bound for France through the 50-km- (31-mile-) long northern tunnel. The fire, that spread to other vehicles, raged for about 16 hours. The extreme temperatures of up to 1,000º C (1,832° F) caused extensive damage to about 600 m (2,000 ft) of the 7.6-m- (25-ft-) diameter tunnel?s concrete lining, approximately 11 km (7 miles) in from the French entrance. The Channel Tunnel operator, Eurotunnel, awarded the repair con-tract, estimated to be between ?50 to 60 million, to a consortium of Freyssinet, Eurovia Travaux Ferroviaires (ETF) and Vinci Energies. Freyssinet was appointed to look after the civil engineering works, while ETF would be responsible for track and overhead wire restoration and Vinci Energies responsible for other equipment. The technique of hydrodemolition, which uses high-pressure water jets to remove concrete from various structures, was specified as the method to remove the fire damaged concrete. Freyssinet subcontracted the concrete removal to the specialist hydrodemolition and industrial cleaning contractor Philip Lasserat.

Jan 1, 2009

By J. B. Umhau

During 1928 the United States consumed 73,270 long tons of virgin or primary tin, which was approximately 7.5 per cent more than the 68,198 long tons con¬sumed in 1927 and equaled 41 per cent of the world's production in 1928 (approximately 178,000 long tons). Consumers' stocks amounted to 9,268 tons on January 1, 1928, and 8,587 long tons on December 31, 1928, a net reduction of 681 tons. In addition to the virgin tin accounted for above, 12,106 long tons of secondary metallic tin were used by manufacturers of tin products in 1928. These figures are the result of an inquiry addressed by the Bureau of Mines to manufacturers to determine the amount of metallic tin used by them; in reply, 1,307 establishments reported consumption in 1928. The distribution of the amount consumed by various uses, as shown in the allowing tabulation based on Bureau of Mines canvasses for 1927 and 1928 in comparison with consumption by uses reported by the War Industries Board for 1917, emphasizes the fact that new uses for tin have been developed in only minor or insignificant amounts. Furthermore, although the studies for recent years show that some older uses have been discontinued, the amounts involved were all small and insignificant. Variation in consumption from year to year parallels the fluctuations in demand for the already well-established tin products. For example, the manufacture of bearing metals and solders for motor cars and trucks required 19,000 tons in 1928 compared to 16,000 tons in 1927; the canning industry continues to require the greater portion of the tin plate and also much solder. Growth in the electrical and the more recently developed industries (aeroplane, refrigerators, radio, etc.), while affecting total consumption of bearing metals, solders, etc., has made little change in the proportions required for these basic methods of using tin.

Jan 1, 1929

By H. Conrad Meyer

The wizardry of nucleonics has added new and greater dimensions to the almost inseparable "twins"-zirconium and hafnium. So close is their relationship that neither element is found free of the other in any presently known mineral. Although zirconium in the form of its oxide was discovered in 1789 by Klaproth, the metal in an impure, nonductile form was not isolated until 1824 by Berzelius. About 100 years later -1925-van Arkel and deBoer developed and patented a technique for the deposition in vacuo of crystalline, coherent, highly ductile metal of extreme purity on an electrically heated filament through the dissociation of gaseous zirconium tetraiodide. Within the past five years both zirconium and hafnium have been dramatized by the press and in popular science magazines. This has led to the false assumption that practically all of the world consumption of zirconium ores is used in the production of the metals. Recent statistics on the subject show that not over 15 pct of the zirconium ore consumed in 1958 went to ferrosilicon zirconium and zirconium metal. The rest was consumed in refractories, foundry sand and facings and ceramics. The importance of zirconium as a component in compact, relatively lightweight nuclear energy units, such as those now used in the submarine Nautilus,6 is well established. A rival of zirconium metal as a casing for atomic fuels is a newly developed ceramic body. It is claimed to be cheaper than zirconium-to withstand higher temperatures-and to be more resistant to corrosion. Whether such ceramic casings have the required low thermal neutron absorption cross section, high strength and easy formability of zirconium is yet to be demonstrated. Hafnium, because of its low order of abundance and its close chemical relationship to zirconium, was not definitely recognized as a new element until around 1923, despite prior claims. A study of the X-ray spectra of zirconium led to its identification. The circumstances leading to the discovery of hafnium were much less fortuitous than those surrounding zirconium. The more precise tools of arc and X-ray spectrometry lent themselves admirably to the search for elements to fill certain gaps in the periodic table. [ ] Pure, ductile hafnium-a metal similar in appearance to stainless steel-has a specific gravity of 13.3 (zirconium 6.52) and a melting point of 2,200°C. In other respects it closely resembles zirconium except in one important respect which gives it a preeminent position in nuclear energy development, namely, a high thermal-neutron absorption cross section. This explains the necessity of hafnium-free zirconium in atomic piles. The ability of hafnium to capture thermal neutrons makes it an excellent "moderator" of "governor" when used as control rods in nuclear reactors (Table 1).

Jan 1, 1960

By D. H. Gieskieng

THE advent of curved jaw crusher wearing plates made an approach other than segmental layout analysis desirable for prediction of capacities. For some time it had been known that the drawing board capacities of crushers using these plates had to be considerably modified by complicated experience factors to achieve agreement with results. Because these apparent capacities could be readily increased severalfold by minor crushing chamber shape changes, it was necessary that the utmost precaution be taken in predicting capacities of jaw plates modified for nonchoking, special wear characteristics, or any other reason. To this end the laboratory and field tests outlined by the author in a previous paper1 were made on Blake-type jaw crushers. The results of these tests were summarized in a simple first degree equation applicable to crushers using either straight or curved jaw plates. This equation first outlines the maximum capacity potential of a given crusher, then reduces this figure in accordance with installation circumstances by means of a realization factor. It was found subsequently that this equation, with the addition of an eccentric throw factor, is applicable to standard types of single-toggle or overhead eccentric jaw crushers as far as maximum capacity potential is concerned. However, these crushers have realization factor curves somewhat different from those outlined for the Blake type. While this paper is concerned principally with standard type single-toggle crusher capacities, the evaluation of data obtained with these machines is simplified by comparative reduction to the 10 x 7 in. Blake-type equivalents upon which the summary of the preceding paper was made. Convertibility of data from one type of crusher to the other also tends towards confirmation of both. The agreement of these data is sufficient to be considered complimentary. Consequently the feed factors, f, previously reported for Blake crushers are slightly adjusted to an average with the single-toggle crusher results. Blake-type equation: C = f.d.w.y.t.n.a.r [I] Single-toggle type equation: C = f.d.w.y.t.n.a.e.r [21 where C is the capacity in short tons per hour through the crusher, f is a feed factor, dependent upon the presence of fines in the feed, and the surface character of the jaw plates used. Values of f : Smooth Plates Corrugated Plates With normal fines 0.0000414 0.0000319 Fines scalped out 0.0000368 0.0000252 Large pieces only . 0.0000312 0.0000215 d is the apparent density of the broken product in pounds per cubic foot. (If the true specific gravity of the feed is known, 40 pct voids may be assumed and d becomes 37.4 times sp gr). w is the width of crushing chamber in inches. y is the openside setting of the crusher, in inches. In the case of corrugated jaw plates it is measured from the tip of one corrugation to the bottom of the valley opposite. t is the length of jaw stroke in inches at the bottom of the crushing chamber. It is the difference between open and close-side settings. n is rpm, or crushing cycles per minute, a is the nip-angle factor. It is unity for 26" and 3 pct greater for each less nip-angle degree. A nip-angle of 20" has an a value of 1.18, and an angle of 30" has an a value of 0.88, see Fig. 1. r is the realization factor. It is unity for perfectly uniform choke feeding and usually less for actual operating conditions according to the method of feeding used and the probabilities of hang-ups involving the size of feed and crusher opening. Approximate values are given by the curves in Fig. 2. These values are further reduced by intermittent feeding, e is the throw or diameter of gyration of the single-toggle crusher eccentric in inches. As evident in Fig. 1A, variation of feed size will generally have little effect on nip-angle if both jaw plates have flat areas. Jaw plates having continuous curvature, as in Fig. 1B will have different nip-angles, depending upon the size of feed. For test work as described in this paper this effect was accounted. For general compilation of capacities for average feeds it is suggested that the nip-angle be taken at the various settings computed, at an arbitrary level, such as is indicated in Fig. 1C. Data Evaluation To bring the Blake and single-toggle type crusher capacity test results to common terms for evaluation, all data are converted to terms of 10 x 7 in. Blake-type performance at conditions of 100 lb per cu ft, 10 in. chamber width, 250 rpm, 0.65 in. stroke, 3-in. openside setting, and 18° nip-angle. (The nip-angle of the 10x7 in. Blake is 18° at 3-in. setting.) The single-toggle crusher performances are also divided by the eccentric throw to bring this effect to unity. As outlined,' laboratory and field tests made on Blake-type crushers ranging from 10 x 7 in. to 60 x 48 in. were summarized along the foregoing conditions of speed, stroke, etc. This resulted in groups of data which correspond to feeds with fines, feeds

Jan 1, 1952

By C. Diaz, S. W. Marcuson, K. I. Burgess

Deep roasting in fluid bed roasters is the first unit operation in Inco&apos;s "roast-reduction smelting" process for the treatment of nickel sulphide concentrates. The roaster product, a low sulphur calcine, is reduction smelted with coke in an electric furnace to yield a sulphur-deficient matte which is then converted to low (<1%) iron matte in Peirce-Smith converters. Due to the deep roasting, a minimal amount of sulphur dioxide is evolved in the smelting and converting stages. Sulphur is eliminated from the concentrate almost exclusively in the roasters in a single, continuous, strong, gas stream suitable for treatment in an acid plant. This paper discusses the commercial scale testing of deep fluid bed roasting of nickel concentrate at Inco&apos;s Thompson Smelter as part of two commercial scale campaigns on roast reduction smelting conducted in 1981-1982. Slurry feeding, practised during the second campaign, permitted excellent control of the air/concentrate ratio in the roaster and, in turn, good control of sulphur elimination (about 80% of input). Smooth autogenous operation with high oxygen efficiencies (about 95%) was promoted by operating at bed temperatures of830°C to 850°C with calcine recycle. High throughputs and the desired metallurgy were achieved. The extensive testwork conducted during the two experimental RRS campaigns demonstrated thot deep fluid bed roasting of nickel concentrate at high oxygen efficiency is a technically viable operation.

Jan 1, 1994

In most mines using presplitting the final excavated wall shows a zone of damage just below the crest and well defined presplit half barrels. The crest damage (surface dilation) zone varies and is added to by subsequent adjacent perimeter blasting operations. Keeping the preconditioning to a minimum is possible using the methods described in this paper, developed on several diverse and geographically distant mining operations to control crest dilation and preconditioning by presplitting in advance - not just laterally but vertically in advance. The first documented case (Delbridge, Marton and McSweeney, 2004) in the development of the concept was undertaken at AngloGold Australia Pty Ltd&apos;s Sunrise Dam Gold Mine (SDGM), located beside Lake Carey, some 730 km northeast of Perth, Western Australia. The mine had been developed in a series of cutbacks to a depth of over 300 m and began underground mining during the latter stages of open cut operations. This mine is fairly unique in that it utilised a single pass vertical presplit which initially extended over three bench heights and after the failure mechanisms were understood, over four benches. The presplit drilling for the three stacked benches started on the floor of the second bench so that any dilation was confined to the surface one bench above the crest and modified perimeter blasting was then developed to curtail damage from blasting adjacent to the new crest. The second case is based on a South African coal mine in the Witbank Coal Measures, 140 km northeast of Johannesburg, Republic of South Africa (RSA). It was important that blasting for optimal wall stability and minimal scaling was developed in advance. A dragline is scheduled to excavate the #2 seam midburden which is the lowest of the economically viable coal seams in the five seam Witbank Coal Measures. Mining of the overburden, coal and partings above the dragline midburden pass are by excavator and truck and each mining layer is individually blasted. The results of presplitting the midburden through the overlying coal seams and partings have provided a presplit with no surface dilation of the midburden crest and ensures any subsequent crest loss is solely due to blasting adjacent to the vertical presplit. Typical of all coal mines in South Africa only vertical presplits are used. Wall control is most commonly delivered by presplit blasting and one common sight after the dust clears is a ridge of broken blocks along the presplit row, usually with a main crack running between the presplit blastholes and often parallel cracks either side of the perimeter line. The surface rock strata or block structures have been dilated by the venting gases and shock waves. Decoupled, fully coupled, single or double deck charges are used depending on a variety of factors, anecdotal practices and perceived benefits. Preconditioning of the crest rock by blasting from above may not be visible to the naked eye (or non-existent in overburden in strip coal mines) but the high speed venting of explosives gases (and often the water in the presplits) preferentially follow existing cracks and structures because there is no developed presplit crack near the surface. This nearly always lifts, shifts and separates the surface structures and geological layers. Stopping the dilation by &apos;sacrificial&apos; or &apos;in advance&apos; presplitting has been shown to reduce the crest loss at both metal and coal mines. Drilling and presplit blasting through an upper level of bench or layer provides a degree of restraint to the target layer where the crest must be maintained and any damage caused by the venting gases will not cause concern as it is removed as planned, leaving a stable crest.

May 1, 2010

By E. G. Banks

THIS paper is presented in the belief that metallurgists and chemists will be interested in the practice of grinding in tube-mills in connection with stamps, especially since the records of working here given extend over a lengthy period of time (since May, 1905). The ore from the Waihi mine-more especially that produced in the upper levels-contains a large proportion of hard, chalcedonic quartz, and the gold exists in an exceedingly fine state, conditions which necessitate very fine crushing in order to ob¬tain a high extraction of the precious metal. Before the introduction of tube-mills at the 90-stamp Waihi mill, it was found necessary to stamp through 40-mesh (1,600 holes per sq. in.) woven wire-screens, having a fairly high discharge. The pulp then graded

Jan 1, 1907

By F. A. Gates, Bengt Samuelson, James E. Edmunds, S. McCune, Neil Hario, Norman L. Weiss, J. M. Bertram, A. M. Cavaliere, F. M. Jr. Stephens, D. D. Chiang

DESIGN BASIS Size of Project The size of the project generally is expressed in tons of ore milled per day, but company policies differ widely in this respect with a few adhering to this set figure but many expecting the design capacity to be liberal. To some companies that follow the latter practice a 25,000-tpd milling plant that cannot reach 30,000 or 35,000 tpd with¬out major additions is a disappointment. The engineers responsible for planning the operation must know what is intended. Other projects are sized according to the tonnage of product rather than of mine ore; examples are iron ore mills that express size in terms of tons per year of pellets or high-grade concentrates, heavy minerals plants in tons per year of rutile or ilmenite, cement plants in barrels per year, potash in tons per year of muriate, phosphate in tons per year of washer rock and flotation concentrate, and others. However, tons per day milling rate is also the common denominator in most of those instances because the major equipment has to be selected on that criterion. Equally important are operating schedules, particularly the number of operating days per week and shifts per day for ore delivery, crushing, grinding, and processing. Hours per shift also are an impor¬tant factor in design, particularly in the case of ore delivery, and the lost time expected for maintenance, cleanup, inspection, preventive maintenance shutdowns, and many others, has to be taken into ac¬count. Frequently, the ore deposit will vary in hardness and grade to such a degree that the capacity of the mill will vary widely from year to year and cannot be expressed as a fixed figure, but rather as an average over a calculable period, such as ten years, or as a specific daily capacity over the first two years, next four years, etc., or some similar projection. A good example of this kind of situation is Asarco&apos;s Mission operation 15 miles southwest of Tucson, Ariz., described by Weiss and Vincent,1 where the major rock types differed widely in hardness, so that a change in the proportion of these types in the mill feed could have imposed difficult design problems if a constant tonnage rate had been expected. Expected Life The life of a mining operation depends upon the size of the deposit and the rate of mining. The latter is a policy decision based on an economic analysis2 which, in turn, is based on many factors. From the point of view of mill planning, the estimated life of the operation determines many criteria and affects many decisions on strength of structures and degree of protection of men and materials, the quality of the materials-handling and process machinery, the type of delivery systems for ore to the mill and concentrates to the smelter or market, environmental considerations, and many others. Costly installations that may be excellent investments for a 20-year project may be waste¬ful for a 5-year operation. An example is the comparison of different methods of crushing or grinding. Take single- vs. multiple-stage grind¬ing-the former may be found more economical for a 5-year operation, and the other, more costly method more economical for a 15- to 20-year life. Mining and Ore Transportation The mining method and the means of transportation of the ore to the first crushing stage have far-reaching effects upon mill design, particularly the crushing sections, and upon site selection (see Chapter 2, Situation of Mill). Consequently, mill design cannot advance until the mine planning has reached at least tentative decisions concerning these important matters, or reach the final stages until much is known about the ore that may be expected month by month and year by year for a reasonable period. Methods of ore transportation used in over 90 underground and open-pit mines are listed briefly in Section 32 (Table 1), and more detail is found later in this section and in Section 10, Storage and Transport. These methods include surface railroad, trucks, conveyors, surface skips, underground skips, and tramming from hoist or tunnel. In surface mining, transportation of the uncrushed ore by rail or truck to the primary crushing plant-conveniently located for lowest overall cost-is most common. Rail transportation provides low perton-mile costs. Truck transportation, though in some cases less eco¬nomical, is more flexible and more adaptable to mountainous terrain; furthermore, recent improvements have reduced the operating costs to keep trucks competitive on low-grade ores. The design of the primary crushing plant will be essentially the same whether delivery is by truck or rail, but the location of the plant is subject to more rigid restrictions in the latter case because of grade limitations, and these in turn may adversely affect the selec¬tion of the mill site as well. The influence of truck haulage in reducing the stripping ratio in open-pit mines is an added reason for predicting a minor role for rail transportation in the future. The use of conveyors to transport ore from the pit to the milling plant involves (in most cases) crushing the ore to a reasonable size (10 to 20 in. maximum with today&apos;s crushers) before conveying. The Twin Buttes system3 which went into operation in late 1969, utilizes primary crushers (two) and conveyors to receive rock waste, ore, and low-grade stockpile material from trucks, then transport them to the appropriate destination. Flexibility is dependent upon the porta¬bility of the primary crushers. In the face of this development, inclined skip hoists are no longer important to the mill designers. Underground mines generally pose fewer problems of design; these will be discussed in Chapter 2. Character of Deposit The degree of homogeneity of the ore in various parts of the mine is an important factor. The characteristics that concern the millman (approximately in order of importance) are: hardness, assay, metallurgical response, size distribution,4 and moisture content. Under metallurgical response may be included degree of oxidation, mineral¬ogy, clay content, and reagent consumption, as well as process re¬sponse in general. Short-term variations-hour-to-hour, day-to-day, or even week-to-week-make operation of the plant more difficult, require greater flexibility of process design and, perhaps, also require more instrumentation and manpower. Uniformity of the ore in the characteristics noted previously and

Jan 1, 1985

The research project on size reduction, sponsored by the mining industry through financial support from individual companies, is now embarking on a second three-year program. The first 3-year program had as its objectives assimilation of the literature on comminution and development of simulation programs encompassing the basic mechanisms of grinding. This involved investigating conditions under which a particle in a mill is captured, the stress to which it is subjected, its break probability, and the resulting particle size distributions. The results were used to obtain the most representative simulation models based on current knowledge of mechanisms. As part of this work a set of computer programs has been developed for the following cases: . Batch mill, by numerical integration for completely general selection and breakage functions. . Continuous open-circuit mill by same method as above. . Continuous open-circuit mill by general numerical integration method, including transient behavior

Jan 1, 1969

By F. W. Petersen

Slurry reactors are being used extensively throughout the chemical, biochemical and mineral processing industries. This paper describes the interaction between fine ore particles and granular porous adsorbents such as activated carbon and ion-exchange resins in a stirred tank reactor. Gold and silver cyanides were used as adsorbates to detect changes in the mass transfer characteristics of the adsorbents, which were ashed to determine the loading of ore particles. A simple kinetic model incorporating film diffusion, intrapanicle diffusion ~d the adsorption equilibrium, was used to interpret kinetic data and to estimate the effect of slurry conditions on the diffusion parameters. It was observed that the equilibrium loading of fines in the adsorbents was independent of their concentration in the slurry. Furthermore, the presence of these panicles inside an adsorbent decreases the effective diffusion of gold or silver cyanides into the adsorbent matrix. When fine suspended solids are present in the reactor, a decrease in the effective availability of the superficial surface of the pre-saturated adsorbent panicles for mass transfer from the liquid phase was observed. This newly defined surface availability factor was dependent on the concentration, panicle size, and the zeta potential of the fine particles in suspension.

Jan 1, 1993

By J. C. Franklin

The U.S. Department of the Interior, Bureau of Mines, has developed a data acquisition system to continuously monitor radon, working level, absolute pressure, temperature, relative humidity, and air velocity. Data have been taken in intake and exhaust drifts, working stopes, and sealed-off areas of positive and negative ventilated uranium mines. Radon emanation rates, ranging from 1.7- to 12.2 x 2 10-l4 Ci/cm /sec were determined in four mines. The ratios of short duration, primary fan shutdown time to radon normalization time were 1 to 2 and 1 to 4, respectively, for-negatively and positively ventilated mines. Blasting and slushing caused radon increases of 160 and 67 percent, respectively.

Jan 1, 1980

By José Gonçalves Pacheco Júnior

A caldeira de recuperação de calor de gás de coqueria, denominada caldeira 22, foi submetida à inspeção e reparo conforme os dispostos na NR13 em função de falhas repetitivas que levaram a uma perda repentina de nível de água no tubulão de vapor da Caldeira. O equipamento foi inspecionado levando em consideração técnicas qualitativas e quantitativas de inspeção de equipamento, o que gerou a possibilidade de especificar o reparo. Através do reparo foi possível liberar a caldeira para produção de vapor. Com os dados da inspeção foi realizada uma análise de falha por um grupo multidisciplinar com objetivo de determinar a causa raiz dos modos de falhas detectados durante a inspeção do equipamento: espessura de isolamento térmico inadequado e operação inadequada após detecção de vazamento de água no equipamento. Ações de controle foram definidas e replicadas para as outras caldeiras dessa coqueria. Assim sendo a caldeira 22 está operando em segurança conforme especificação do projeto e com os reparos preventivos já determinados.

Oct 30, 2017

By Jayme Alex Marques da Silva

A utilização de carvão vegetal na fabricação do ferro-gusa tem ganhado destaque devido a suas vantagens ambientais em comparação ao coque. A necessidade de suprir a demanda de consumo de carvão vegetal pelas siderurgias faz com que os produtores busquem maior produtividade e qualidade através da busca constante na redução do tempo de produção do carvão. O presente trabalho apresenta o desenvolvimento de um modelo matemático tri-dimensional transiente, para simulação da secagem, carbonização e resfriamento no interior de um forno retangular de alvenaria. Foi desenvolvido um modelo acoplado baseado na solução das equações de conservação da quantidade de movimento, energia e espécies químicas. As soluções das equações diferenciais que representam os fenômenos são obtidas através da técnica de volumes finitos. Ao longo do processo de carvoejamento, o modelo considera a transferência de massa e calor associada à cinética de reação de cada componente. O modelo é tridimensional e transiente, sendo capaz de prever detalhes dos fenômenos no interior do forno e sua evolução temporal o que possibilita o controle das fases de fabricação do carvão vegetal.

Aug 1, 2018

Pictured on these pages are seven of the eight RMCMI Scholarship Award Winners for the 1993- 94 year followed by a brief profile. Seven of the eight winners were present as guests of the Institute at the June convention in Snowmass Village, Colorado to receive recognition at the Institute Awards Luncheon Monday, June 27, 1994. Due to another conflict. Jason T. Dale of Wyoming was unable to attend. Each state vice president sewed as the host for the collegiate winner. In addition to receiving a plaque from the Scholarship Chairman. Alan Czarnowsky, each winner receives $750 tuition credit for the coming academic year, as well as transportation, hotel lodging and meals at convention as guests of the Institute. Because this is a continuing award, the winners from the previous year will receive another $750 for tuition credit in their senior year if they have maintained good academic standing and are recommended by their university. A resident from each of the eight RMCMI member states is selected from among Board approved institutions. Criteria for these awards to be made in the spring annually is (1) That the award be made to a sophomore student and used as tuition during the junior year. (2) That the recipient be both a U.S. citizen and a resident of the member state. (3) That the recipient have good academic standing, be pursing a degree in a mining related field and have an expressed interest in Western coal as a possible career path. The scholarship program includes curricula other than those in the mining departments, but in engineering disciplines, such as geology, mineral processing and metallurgy. Contributions to this worthy project are tax deductible to each individual RMCMI member or his firm. Through annual donations of $100 or more, the Patrons of the Institute fund the scholarship program and the various vice presidents contribute the travel expenses to convention for these outstanding young collegiates. Donations to this worthwhile program may be made payable to RMCMI Scholarship and mailed to the RMCMI Office. 3000 Youngfield Street, Suite 324, Lakewood, CO 80215. Profiles of the 1994 Scholarship Winners follow. [ ] ARIZONA WINNER Christy L. Brandt University of Arizona Tucson. Arizona Christy Brandt is the 1994 RMCMI scholarship winner from Arizona. She is majoring in Mining Engineering at the University of Arizona in Tucson, Arizona, but recently is considering switching to Environmental Engineering with emphasis on mining. She told the Scholarship Chairman that if she wasn&apos;t part of the solution, she was part of the problem. Christy has received numerous awards during school including being on the honor roll and university chapters of Society of Mining Engineers. Besides her academic activities, which includes being a member of Student Council, Christy is quite an athlete and enjoys basketball, softball, tennis, golf, and soccer. Last summer, she worked as a safety assistant/laborer for the Magma Copper Company. This summer, Christy is working in the safety department at Magma Copper Company&apos;s Pinto Valley Mine in Arizona. [ ] COLORADO WINNER Jason P. Markle Colorado School of Mines Golden, Colorado Jason Markle is the 1994 RMCMI

Jan 1, 1994

By M. A. Vos

"Aggregates are the low-cost mineral raw material of building construction. Large volumes of aggregate are consumed each year. The availability of aggregates in southern Ontario is discussed in the context of the geological formations in which they occur. Sand and gravel are abundant in glacial deposits and in recent sediments. A knowledge of the glacial history is important for their discovery. Bedrock formations provide a variety of aggregates in Ontario. Knowledge of the rock types involved and of the depth of overburden are important for evaluation of the aggregate potential of bedrock resources in an area. Utilization of available resources intensifies as the population increases. Urban development makes it progressively more difficult to satisfy the demands of the construction industry. The effects of urban development on the aggregate resource base of an area are illustrated by developments and consumption statistics in the Toronto- centred region. There is an obvious need for a comprehensive survey of available resources in urban areas to serve as a guide in land-use planning. To fill this need, staff members of the Industrial Minerals Section, Geological Branch, Ontario Department of Mines and Northern Affairs, are engaged in mapping projects and mineral resource studies in southern Ontario as well as in some urban areas of northern Ontario."

Jan 1, 1972

This paper deals with the extension of Post Office telecommunications (telephone, data, leased private lines etc.) network to mining communities in remote areas of Australia. The evolution of the "Spur Line" policy and its application is referred to together with comments on the engineering of telecommunication Facilities.

Jan 1, 1973

By J. S. Miller

This report presents a complete coverage of results from Bureau of Mines preliminary research and the field application of explosive fracturing techniques to prepare oil shale for in situ recovery of shale oil. Small-scale surface tests were conducted to determine the feasibility of using a nitroglycerin-base explosive for creating rock fractures. Prior to underground testing, surface and near-surface tests with liquid explosives showed that explosions in sheetlike layers simulating underground fractures would propagate effectively. Successful surface experiments were conducted using layers of explosive placed between glass plates and explosive-saturated sand confined in small-diameter metal tubes. The tests in glass-plate reservoirs and metal tubes demonstrated that nitroglycerin would detonate and the explosion would propagate in cracks as thin as 1/32 inch and through distances up to 12 feet. In a shallow field test, nitroglycerin was detonated in a vertical crack in limestone and produced extensive fracturing. Explosive fracturing tests were performed in oil shale formations on seven sites near Rock Springs, Wyo. The procedures included (1) displacing and detonating nitroglycerin in natural or hydraulically induced fracture systems; (2) detonating nitroglycerin in wellbore shots; (3) displacing and detonating nitroglycerin in induced fractures followed by wellbore shots using pelletized TNT; and (4) detonating wellbore charges using pelletized TNT. The research on oil shale formations demonstrated that nitroglycerin displaced in a natural or hydraulically induced fracture would detonate, and the explosion would propagate through the explosive-filled fracture. Shooting a pattern of wells in oil shale at 100-foot depth with wellbore charges of pelletized TNT developed a satisfactory interwell fragmented zone. Tests performed on other sites at depths to 385 feet caused fragmentation of rock around the wellbore and provided interwell communication. Fourteen methods used to evaluate the extent and degree of fragmentation in the explosive fractured oil shale are discussed.

Jan 1, 1974

By N. B. Pilling, R. E. Bedworth

The corrosion of metals is one problem on which time and thought have been expended for many years. In the effort to avert the destructive action of a hostile environment, attention has been directed almost entirely to the conditions under which most metallic structures are called upon to perform, and the extensive and complicated phenomena attending the corrosive action of atmospheric agencies, acting at the ordinary atmospheric temperatures, have been studied, but there is unanimity of opinion regarding many fundamental facts. One neglected phase is the corrosive action of various gases upon metals exposed to temperatures considerably higher than the atmospheric range, and more especially the attack of atmospheric oxygen upon exposed metallic surfaces. That the problem is difficult is connoted by the practical dominance of industrial electric heating by alloys of one type (nickel-chromium). Proprietary interest may account, in part, for the paucity of information available upon even the most general factors determining the behavior of metals and alloys when exposed to such exacting conditions. The present paper gives some conclusions reached as the result of experimental work, extending over several years, on the mechanism and contributory factors of the high-temperature oxidation of a number of simple unalloyed metals; it is free from experimental detail and proof. High-temperature metallic oxidation may be considered as a phase of metallic corrosion. The scheme outlined below, in which corrosive agent and environment are the principal criteria, is one way of analyzing the several groups of corrosion phenomena. Erosion.—Disintegrating or destructive action by physical causes. Corrosion.—Disintegrating or destructive action by chemical causes. Low-temperature Corrosion.—Solid participating phases essentially immobile: (a) Gaseous agent; (b) liquid agent: action electrolytic and action non-electrolytic. High-temperature Corrosion.—Solid participating phases possess diffusive mobility: (a) Liquid agent; (b) gaseous agent: reducing gases, oxidizing gases. (1) Water; (2) miscellaneous elemental and combined oxygen.

Jan 1, 1923

By R. E. Bedworth, N. B. Pilling

The corrosion of metals is one problem on which time and thought have been expended for many years. In the effort to avert the destructive action of a hostile environment, attention has been directed almost entirely to the conditions under which most metallic structures are called upon to perform, and the extensive and complicated phenomena attending the corrosive action of atmospheric agencies, acting at the ordinary atmospheric temperatures, have been studied, but there is unanimity of opinion regarding many fundamental facts. One neglected phase is the corrosive action of various gases upon metals exposed to temperatures considerably higher than the atmospheric range, and more especially the attack of atmospheric oxygen upon exposed metallic surfaces. That the problem is difficult is connoted by the practical dominance of industrial electric heating by alloys of one type (nickel-chromium). Proprietary interest may account, in part, for the paucity of information available upon even the most general factors determining the behavior of metals and alloys when exposed to such exacting conditions. The present paper gives some conclusions reached as the result of experimental work, extending over several years, on the mechanism and contributory factors of the high-temperature oxidation of a number of simple unalloyed metals; it is free from experimental detail and proof. High-temperature metallic oxidation may be considered as a phase of metallic corrosion. The scheme outlined below, in which corrosive agent and environment are the principal criteria, is one way of analyzing the several groups of corrosion phenomena. Erosion.—Disintegrating or destructive action by physical causes. Corrosion.—Disintegrating or destructive action by chemical causes. Low-temperature Corrosion.—Solid participating phases essentially immobile: (a) Gaseous agent; (b) liquid agent: action electrolytic and action non-electrolytic. High-temperature Corrosion.—Solid participating phases possess diffusive mobility: (a) Liquid agent; (b) gaseous agent: reducing gases, oxidizing gases. (1) Water; (2) miscellaneous elemental and combined oxygen.

Jan 1, 1923

By A. K. Mukherjee, John E. Dorn

The effects of strain rate and temperature on the critical resolved shear stress for (321)[111] slip were determined for the silver-rich CsCl type of intermetallic compound AgMg. The flow stress increased only slightly as the test temperature was first decreased below room temperature; a rapid increase in the flow stress was obtained with yet further decrease in temperature from about 250&apos; to 4OK. The effect of both the temperature and strain rate on the flow stress over the low-temperature range could be rationalized satisfactorily in terms of the Peiwls mechanism when the deformation was controlled by rate of nucleation of pairs of kinks. IN spite of the well-documented interest of metallurgists and engineers concerning the mechanical behavior of intermediate phases and intermetallic compounds, very little definitive information is available on this important subject. As recently summarized by westbrook,1 only limited and modest progress has been made thus far in elucidating the details of the mechanism of plastic deformation for the intermetallic compounds; the available information largely concerns phenom-enological descriptions of empirical observations and experimental facts, principally with reference to poly crystalline aggregates. The present report on the elucidation of the rate-controlling mechanism for slip in the bcc structure of AgMg is part of the comprehensive program of a systematic investigation on the mechanical behavior of intermetallic compounds. The intermetallic compound AgMg has a CsCl type of lattice structureZ and is completely ordered up to its melting point of 820c3 This material was selected for our present investigation because of its simple crystal structure, moderate and congruent melting point, ordered structure persisting up to the melting point, and some solubilities of the constituent elements, which could be expected to help in the growing of single-crystal specimens. Whereas previous investigations on the properties of AgMg include hardness,*"6 slip systems,7 tensile flow stress of polycrystalline specimens,&apos; and electrical resistivity,4 the current investigation will be directed principally at elucidating the rate-controlling dislocation mechanism responsible for slip in single crystals at low temperatures. It will be shown that the strain rate is consistent with a model involving the rate of nucleation of pairs of kinks by the Peierls mechanism for plastic deformation. EXPERIMENTAL TECHNIQUES Single-crystal specimens of the AgMg intermetallic compound were prepared and tested as follows: 1) A master alloy ingot of AgMg was produced by melting and chill casting the high-purity silver (99.995 wt pct) and high-purity magnesium (99.997 wt pct) in an induction furnace under a helium atmosphere. 2) Sections of the above-mentioned ingot were placed in a graphite mold containing a spherical cavity in which a single-crystal sphere of 1 in. diam was grown under helium by the Bridgman technique. 3) The operative slip systems were investigated at room temperature on a singlecrystal of AgMg, from measurements of the angles made by the slip traces on the two surfaces of the specimen, which were at 90 deg to each other. The investigation confirmed that the AgMg compound undergoes slip primarily in the (321) plane and in the [Ill] direction, but a small amount of secondary slip was also noticed in the (112) (111) system. No slip was observed in the (110) planes. 4) The single-crystal sphere, mentioned earlier, was oriented in a graphite mold containing a cylindrical cavity of 3/8 in. diam above the spherical receptable to give the angle xo = 45 deg between the axis of the cylindrical bar and the normal to the slip plane (321), and the angle AO = 45 deg between the slip direction [Ill] and the axis of the bar. Oriented single-crystal bar seeds were produced by melting, under a helium atmosphere, a polycrystalline bar in the cylindrical cavity above the oriented spherical seed and by growing an oriented single-crystal bar from the seed. 5) Finally, oriented single-crystal specimens were grown from these cylindrical seeds. 6) The cylindrical specimens were machined in a High-Tension Spark Cutting unit to give a 2-in. gage length. The spark-machined gage section was elec-tropolished in a bath containing 200 ml of H3PO4,

Jan 1, 1964