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By Godfrey W. McDonald, Dennis E. Fredrickson

"Commercial coal mining has been recorded in Nova Scotia since 1863 and during this period an estimated 60,000,000 short tons of mine discard containing 10 1030% coal has been accumulated, Approximately 70% of these dumps are in the Cape Breton region and most are owned by the Cape Breton Development Corporation (CBDC), formerly DEVCO.The explosion of oil produced energy costs which created an increase in thermal coal demand as well as the desire to rehabilitate abandoned mine dumps encouraged coal reclamation. CBDC was receptive to a proposal from the Selminco Joint Venture and encouraged the building of the Princess Recovery Plant (1980) and The Summit Plant (1982).The mine dump contains scrap, waste rocks, coal and substantial quantities of fine shale. The scrap and oversize are removed and the remaining material slurried with water to a density of 1.45. The slurry is cycloned to separate the saleable thermal coal from the rejects which are returned to designated areas of the dump for contouring and revegetation.BackgroundThe recorded coal production in Nova Scotia from 1863 to 1980 was 390,000,000 short tons. This extraction was associated with an estimated 60,000,000 short tons of discarded material. This mining discard and coal washing plant reject are located in numerous, varying sized dumps throughout the mining areas. Approximately 70% of these dumps are in the Sydney coal field region of Nova Scotia. The coal content of these dumps varies from 10 to 30% coal with an average of 18%.Energy CostsThe explosion o f energy costs in the mid-1970s greatly increased the sale price of thermal coal which made recovery of coal from some of the dumps economical. The environmental benefit of these operations will be the rehabilitation of the dumps upon cessation of the coal reclamation operation."

Jan 1, 1983

By Catia Casagrande

O processo de pelotização foi desenvolvido com a finalidade de aproveitar as partículas finas e ultrafinas geradas nas operações de exploração e beneficiamento do minério de ferro. Entretanto para atender as usinas de pelotização, faz-se necessário utilizar a moagem para adequar as características de granulometria e superfície específica das misturas de minérios de ferro às especificações da produção de pelotas. Porém os moinhos possuem alto consumo de energia elétrica, elevando o custo operacional do processo de pelotização. Frente ao cenário atual, foi realizado o trabalho para estudar a substituição à moagem (área úmida) por processo de multi prensagens. Além disso, foram misturados os minérios de ferro com carvão, a fim de reduzir também o custo da moagem deste insumo. O objetivo principal foi quebrar as partículas de mistura de minérios de ferro e carvão, e avaliar os resultados de superfície específica e granulometria deste produto comparando com o processo padrão (moagem e prensagem). A prensa de rolos de bancada e as análises físicas e químicas foram realizadas para o desenvolvimento do trabalho. Foi concluída a possibilidade de atingir granulometria e superfície específica através de multi prensagens, atendendo o processo de pelotamento.

Aug 16, 2017

By Alcides Meléndez González

La formación profesional del personal minero es importante en tanto mejora su desempeño y responsabilidades con la empresa y actividad minero. En ese sentido, el presente trabajo describe los programas de educación profesional desarrollados por el Estado u organizaciones privadas a través de tres etapas: formación profesional elemental, formación profesional especializada y la formación profesional universitaria. Los principales objetivos son: adquirir los fundamentos técnicos, científicos y tecnológicos de la actividad minera y establecer mejores métodos de trabajo como nuevos procesos tecnológicos.

Nov 1, 1972

By Wright D. J

Successful heap leaching depends on three major factors: 1. Chemical conditions appropriate for the dissolution of the valuable metal; 2. Contact between the leach solution and the valuable metal particles; and 3. Movement of the leach solution through, and out of, the heap. Given that appropriate chemical conditions can be provided, and the individual particles have sufficient permeability to allow solute/solvent contact, the problem of getting the solution to and from the particles remains. Non-uniform percolation of solution throughout the heap, caused by the presence of fines, is a common problem which occurs, to some extent, with all heap leachable ore. The conventional solution to this problem is agglomeration, which involves the attachment of fine particles to larger particles, effectively modifying the size distribution by preventing the fine particles from acting on their own. While agglomeration must be considered as an extremely effective technique with virtually no limit to its application from a technical point of view, its application is limited by economic considerations. A new technique has been developed which is not only a low cost alternative to agglomeration, but also has the potential for enabling the application of low cost heap and vat leach techniques to a significantly wider range of ores than current practice would suggest. The new technique, known as Electrokinetic Leaching, utilises electro-osmotic flow to enhance percolation through the heap. This paper describes and presents results of the laboratory testing, pilot heap operation and commercial application of Electrokinetic Leaching of a low grade gold ore and a tailings deposit. Comparative cost analyses between conventional and the alternative processing techniques are presented.

Jan 1, 1994

Intrusion related Cu/Au mineralisation is localised in Pacific Rim island arcs by arc parallel, termed accretionary structures; or arc normal, termed transfer structures. In Papua New Guinea, NE trending transfer structures, evident on Landsat imagery, represent deep crustal fractures which have facilitated dextral rotation of the mainland during oblique plate collision. Major structures localise intrusion centres, and by rotation, develop ore hosting dilational environ-ments in subsidiary structures. While transfer structures localise the Porgera, Wafi and Yandera porphyry centres, the Frieda Porphyry and associated Nena high sulphidation Cu/Au mineralisation are localised by accretionary structures. The Bulolo Graben, which hosts the Morobe Goldfield, developed during intra arc rifting aided by movement on transfer structures. Crustal thinning has initiated magmatism with which diatreme breccias and fracture controlled mineralisation are associated.

Jan 1, 1994

By T. A. Rickard

The presentation to the Institute, eight years ago, of the paper of Pogepny on " The Geilesis of Ore-Deposits " has borne fruit in much fresh investigation, as is evidenced, for example, by the group of very valuable papers, by distirlguished members of the United States Geological Survey, read at the Washing-

Jan 1, 1902

By J. Gurland

The wmk is concerned with the estimate of the degee of continuity of a particulate phase dispersed in a matrix. The first section is a verieu: of the parameters nzeasurable by quantitative rnetallogvaphy, namely the contact area and, under certain conditions, the number of contacts between particles of one phase. In the second section, the frequency of particle contacts is related to the degee of continuity of a randomly embedded phase orz the basis of the lattice-percolation model of Hamrnersley and others. THE extent of continuity of the constituent phases may greatly influence the structure-sensitive properties of phase mixtures, particularly if the phase properties differ significantly. An example from the literature1 is shown in Fig. 1. The marked decrease of the electrical resistivity of sintered silver-alumina bodies near 25 pct by volume of silver presumably occurs because the more conductive phase changes from a discontinuous to a continuous structure. Other example of electrical- and thermal-conductivity transitions are cited by kingery In view of these observations, a knowledge and understanding of the connectivity of the microstructure may be of considerable practical importance. This study is concerned with one aspect of the genera1 problem, namely the estimate of the degree of continuity of a particulate phase dispersed in an opaque matrix. The first section reviews the parameters measurable on a polished cross section by auantitative metallography, such as the contact area and under certain conditions, the number of contacts between particles of one phase. In the second section, an attempt is made to relate the frequency of particle contacts to the degree of continuity of a randomly embedded phase. For the purpose of this discussion, the aggregate has two constituents: the particulate phase and the matrix. The latter is considered to be homogeneous. The term "particle" is used with the meaning of "grain", i.e., a minute unit of matter which is usually a single crystal of a readily distinguishable substance within the confines of a simply connected boundary. While many of the concepts which are used here to describe the structural variables characterizing the microstructure of phase mixtures are qualitative and ill-defined, they are presented with the intent of stimulating further work of a more general and rigorous nature. I) PARTICLE CONTACT, CONTIGUITY, AND MEAN FREE PATH 1) Measurement of Contiguity. The fraction of the total internal surface of a phase a shared with particles of that same phase in a two-phase mixture of and $ is indicated by the contiguity ratio:3 whereis the area of the interface between o particles, and Sap is the area of the interface between a particles and matrix P, per unit volume of mixture. The contiguity ratio ranges from 0 to 1 as the distribution of the a phase changes from a completely dispersed to a completely agglomerated structure. The interfacial areas may be obtained from simple intercept measurements on a random plane, after Smith and Guttman where and N are the numbers of intercepts between a random line of unit length on a plane of polish and the interparticle and interphase interfaces, respectively. The equations are valid for any distribution of particle sizes and shapes.

Jan 1, 1967

By William L. Fink, H. R. Freche

This is the thirteenth paper of a series from the laboratories of the Aluminurrl Company of America presenting the results of investigations of equilibrium relations in aluminum-base alloys prepared from electro-lytically refined aluminum. The ninth paper, on The Constitution of High-purity Aluminum-titanium Alloys,' presented a type of system that had not previously been encountered in aluminum alloys. Subsequent work has shown that there are several similar binary aluminum diagrams including that of aluminum and chromium. The present investigation was limited to the cxtreme alnminum end of the aluminum-chromium system. The first systematic investigation of the aluminum-chromium equilibrium diagram was carried out by Hindrichs.? The resulting equilibrium diagram with some imaginary additions suggested by Guillet3 is shown in Fig. 1. Recently Goto and D6gane4 investigated the constitution of aluminum alloys containing up to 32 per cent chromium, and presented the diagram that is reproduced in Fig. 2. Wide discrepancies in the two diagrams are evident. The following intermetallic compounds have been reported in the literature: A1Crl5,6 AlloCrlzSi,5 AlCr4,6 AlCr3,7 AlaCr.8 Preparation of Alloys and Chemical Analyses With the exception of sample Y4206, which will be described under Determination of Hyperperitectic Liquidus, the alloys were prepared from electrolytically refined alurninum% Of which the analysis is given in

Jan 1, 1933

By K. Kavouridis

Coal is broadly recognized as sure, competitive, diversified, not vulnerable and predictable in price energy resource. In power generation coal is playing a dominant role in the EU-27 with 25% of installed capacity and almost one third of the power generation. The role played by the domestic resources and especially by coal are increasingly becoming the focus of the EU energy strategy. There is a strong pressure for the decarbonization of the energy mix. The Emission Trading system (ETs) can have an impact on the shift to lower carbon-intensity fuels. The impact of ETs on coal can be important, because it is very short sighted and only defines the period up to 2008-2012. The ETs CO2 regime must ensure that investment in coal-fired plants in the long term are supported. EU Research Institutes and Coal Industry identified an important CO2 reduction potential by improving the efficiency of the conversion of solid fuels into electricity. Highly efficient clean coal technologies can contribute to reasonable costs and challenge the issue of climate change. It must be pointed out that the EU Energy policy should now concentrate on the necessity to effectively support demonstration projects and to create the legal framework for the integrated approach of efficiency enhancement and CCS. It is not a right approach to implement CCS before the technology is demonstrated and before it is clear that it will be commercially viable.

Jan 1, 2007

By D. M. McFarland

A FEW years ago a novel electric detonator known as the split-second or millisecond delay electric blasting cap was introduced for use in quarry blasting. Regular electric blasting caps fired in series may be depended upon to fire within a millisecond or so from the first to the last in a series. Regular delay electric blasting caps are provided that fire one period after the other period in intervals of 1/2 to possibly 11/2 sec. Most split-second or millisecond delays are designed to fire one period after the other period in possibly 25 to 50 millisecond intervals. The ear is not capable of detecting time intervals of this magnitude. The primary thought at the time millisecond delays were introduced was to investigate the results on rock breakage by firing a line of holes in a quarry face so that charges in adjacent holes would not be detonated simultaneously. This could not be accomplished satisfactorily with regular delays. The time interval between successive periods of 1/2 to 1 sec was sufficient to permit considerable movement of the burden. If the burden of one hole was reduced to a great extent by the firing of an adjacent hole, the firing of the hole with the reduced burden would likely reveal this lack of confinement by a terrific report and wild throw of rock. In the early blasts with millisecond delays it was observed that instead of the usual sharp report, the blast had a muffled sound and vibration was not as perceptible as when simultaneous firing was used. Because many quarry operators were being threatened with injunctions or suits for damages by neighbors who claimed structural damage to their buildings, millisecond delays were tried extensively in quarries. In the majority of these trials, the results were very satisfactory. The seismologists recorded the ground movement created by many blasts and verified the initial observations that millisecond delays could be used to reduce vibrations appreciably. In the past few years the advantages of this principle of nonsimultaneous firing of the charges in blasts has become generally accepted. Today the quarry operator who has vibration troubles, inadequate breakage, and excessive backbreak and has not investigated the possibilities of millisecond delay blasting is ignoring a remedy that has proved satisfactory for many. His complacency may be costing him money. Because of the results attained in quarry blasting, it was logical that millisecond delays should be tried in construction work such as in road cuts. As formations in this type of work are likely to change rapidly with advance of the cut, it is more difficult to evaluate results than in quarry blasting. However, this improved control over timing has been beneficial in limiting throw, promoting fragmentation, and reducing overbreak. In blasting near buildings the reduction in vibration and in throw has been especially helpful. As blasters employed in construction work learn what may be accomplished by closer control over the time of firing of explosives charges, more and more millisecond delays are being used to supplant instantaneous electric blasting caps. Improved Fragmentation Underground With this background of promising results, it was not surprising that millisecond delays should go underground. In limestone mining use of millisecond delays as compared with use of cap and fuse or electric blasting caps showed improved fragmentation in stopes and in slabbing operations. Then an opportunity developed to use millisecond delays in some tunnels being driven in a limestone mine (fig. 1). Using the normal charge employed and merely substituting three millisecond delay periods for three regular delay periods, there was a noticeable difference in the appearance and the position of the pile of rock after a blast. A greater portion of the face was exposed, the crest of the pile was farther from the face, and the pile was heaped high along the center line of the tunnel leaving room to walk along the ribs to the face. Fragmentation was appreciably increased. It gave the impression that the slabs had been thrown against each other with tremendous force, promoting the movement of the broken rock along the center line of the tunnel away from the face. Because the drilling and the charge weights were unchanged, the evidence was convincing that the difference in timing was responsible for the difference in results. Probably a greater portion of the energy from the explosives had been expended in doing useful work on the rock. Zeros followed by two periods of millisecond delays were used in the V cut and in two slabs to either side of the cut in this simple round. When millisecond delays, substituted period for period for regular delays, are first tried in a drift round in a mine, and the usual charge of explosives

Jan 1, 1951

By D. M. McFarland

A FEW years ago a novel electric detonator known as the split-second or millisecond delay electric blasting cap was introduced for use in quarry blasting. Regular electric blasting caps fired in series may be depended upon to fire within a millisecond or so from the first to the last in a series. Regular delay electric blasting caps are provided that fire one period after the other period in intervals of 1/2 to possibly 11/2 sec. Most split-second or millisecond delays are designed to fire one period after the other period in possibly 25 to 50 millisecond intervals. The ear is not capable of detecting time intervals of this magnitude. The primary thought at the time millisecond delays were introduced was to investigate the results on rock breakage by firing a line of holes in a quarry face so that charges in adjacent holes would not be detonated simultaneously. This could not be accomplished satisfactorily with regular delays. The time interval between successive periods of 1/2 to 1 sec was sufficient to permit considerable movement of the burden. If the burden of one hole was reduced to a great extent by the firing of an adjacent hole, the firing of the hole with the reduced burden would likely reveal this lack of confinement by a terrific report and wild throw of rock. In the early blasts with millisecond delays it was observed that instead of the usual sharp report, the blast had a muffled sound and vibration was not as perceptible as when simultaneous firing was used. Because many quarry operators were being threatened with injunctions or suits for damages by neighbors who claimed structural damage to their buildings, millisecond delays were tried extensively in quarries. In the majority of these trials, the results were very satisfactory. The seismologists recorded the ground movement created by many blasts and verified the initial observations that millisecond delays could be used to reduce vibrations appreciably. In the past few years the advantages of this principle of nonsimultaneous firing of the charges in blasts has become generally accepted. Today the quarry operator who has vibration troubles, inadequate breakage, and excessive backbreak and has not investigated the possibilities of millisecond delay blasting is ignoring a remedy that has proved satisfactory for many. His complacency may be costing him money. Because of the results attained in quarry blasting, it was logical that millisecond delays should be tried in construction work such as in road cuts. As formations in this type of work are likely to change rapidly with advance of the cut, it is more difficult to evaluate results than in quarry blasting. However, this improved control over timing has been beneficial in limiting throw, promoting fragmentation, and reducing overbreak. In blasting near buildings the reduction in vibration and in throw has been especially helpful. As blasters employed in construction work learn what may be accomplished by closer control over the time of firing of explosives charges, more and more millisecond delays are being used to supplant instantaneous electric blasting caps. Improved Fragmentation Underground With this background of promising results, it was not surprising that millisecond delays should go underground. In limestone mining use of millisecond delays as compared with use of cap and fuse or electric blasting caps showed improved fragmentation in stopes and in slabbing operations. Then an opportunity developed to use millisecond delays in some tunnels being driven in a limestone mine (fig. 1). Using the normal charge employed and merely substituting three millisecond delay periods for three regular delay periods, there was a noticeable difference in the appearance and the position of the pile of rock after a blast. A greater portion of the face was exposed, the crest of the pile was farther from the face, and the pile was heaped high along the center line of the tunnel leaving room to walk along the ribs to the face. Fragmentation was appreciably increased. It gave the impression that the slabs had been thrown against each other with tremendous force, promoting the movement of the broken rock along the center line of the tunnel away from the face. Because the drilling and the charge weights were unchanged, the evidence was convincing that the difference in timing was responsible for the difference in results. Probably a greater portion of the energy from the explosives had been expended in doing useful work on the rock. Zeros followed by two periods of millisecond delays were used in the V cut and in two slabs to either side of the cut in this simple round. When millisecond delays, substituted period for period for regular delays, are first tried in a drift round in a mine, and the usual charge of explosives

Jan 1, 1951

Aamot, Olav Crone, Chem. Engr., Norsk Elektrokemisk, Kongensgt. 18, Oslo, Norway. '29 Abbott, Clarence E., V.P., Charge of Raw Materials, Tennessee Coal, Iron & R. R. Co., 1242 Brown-Marx Bldg., Birmingham, Ala. '04 Abel, Raymond L., Prof., Dept. of Pet. Refin., Univ. of Pittsburgh ..Pittsburgh, Pa. '28 Abel, Walter D., Cons. Engr 364 S. Cloverdale Ave., Los Angeles, Calif. '32 Abele, Louis T R.F.D. 1, Adamsville, Ohio. '31 Abell, Leo M., Ore Dressing Investigator, School of Mines Adelaide, S. Australia. '31 Abenius, Hakan V., Mine Supt., Bolidens Gruvaktiebolag Boliden, Sweden. '37 Aborn, Robert H., Asst. Met., Research Lab., U. S. Steel Corp., Lincoln Highway, Kearny, N. J. '19 Abraham, W. E. V., East India United Service Club, 16 St. James' Sq., London, S.W. 1,, England. '28

Jan 1, 1937

By Sturgul J. R

A major electricity generating authority have a proposal to construct a Power Station. An understanding of the operation of the bunker system is of importance to the designers and a computer simulation model of the operation was constructed. The computer language used was GPSS/PC which is a recent form of the language designed for the per- sonal computer. The model simulated trains arriving at the power sta- tion and unloading onto conveyors which carry coal to the power station bunker. Coal was drawn from the bunker at a specified feed rate to the power station. Numerous restrictions were placed on the model, if the bunker level got too high dozers would pull coal out of the bunker onto the stockpile, and if the level got too low the dozers would push coal back into the bunker. The conveyors and dozers were unavailable due to breakdown'at various times and trains would arrive randomly about a mean interarrival time. The system was simulated for 30 years of oper- ation and the model used a basic time unit of 30 minutes so that the system was updated 525,600 times during the simulation. The results of the simu- lation gave the designers a greater understanding of the critical factors in the operation, which may now be engineered to minimise adverse Effects.

Jan 1, 1988

By George E. Cole

While many parts of Canada's pre-Cambrian shield are well served by railway, it is frequently necessary for prospecting purposes to proceed farther into areas inaccessible by rail. To such areas in summer the canoe was at one time the accepted means of travel for the prospector while the dog team was much used in winter. Although summer travel was much improved by the development of the outboard motor, the lack of facilities for cheap transportation has been a serious hindrance to the employment of capital in opening up the distant fields. The pre-Cambrian surface of Manitoba, like that of Ontario, is hummocky, with rounded hills and ridges of rock alternating with basinlike depressions and valleys occupied by lakes and rivers Or by many low-lying portions covered with muskeg' Routes to the mines have not usually been direct or easy and seasonal vagaries have presented problems in themselves. In summer, water transportation may be the cheapest method for the longer distances but it is not every water route that will satisfy the conditions of loading freight on to a boat or scow and of conveying it without interruption to its destination. By its location, a mine may require a large program of boat transportation in summer Over part of its route, to be followed by winter freighting for the remainder. In order to carry on development and produc- tion over a long period, it may be necessary to haul large quantities of supplies during the winter. This seasonal problem, particularly for the out-of-the-way properties, is SO important and demanding as to make it a major operation in the life of the mine. The -use of the tractor during winter months for heavy machinery and bulk supplies, and the use of the airplane throughout the year for the transportation of personnel and for emergency requirements, have greatly improved transportation to places that are inaccessible by rail. Canada has pioneered in both these methods. Development oF Transportation Twenty-two years have seen a marked change in transportation methods in Canada's mining country. Horse-drawn sleighs have given way to the tractor and that to some extent has been supplanted by the airplane. One of the earliest ventures involving transportation of considerable magnitude was that of the Mandy mine, on Schist at in northern Manitoba. According to accounts of early mining activities in Manitoba, the Mandy mine, beginning December 1916, had 3300 tons of ore hauled 40 miles by sleigh to Saskatchewan River and in summer this was conveyed by barge to The Pas, 130 miles, and then by railroad to Trail, British Columbia, 1200 miles. The mine shipped 6000 tons of ore in 1918 and 15,000 tons in 1919. In winter of the latter year, as many as 300 teams of horses were used on the 40-mile stretch to

Jan 1, 1943

By George E. Cole

While many parts of Canada's pre-Cambrian shield are well served by railway, it is frequently necessary for prospecting purposes to proceed farther into areas inaccessible by rail. To such areas in summer the canoe was at one time the accepted means of travel for the prospector while the dog team was much used in winter. Although summer travel was much improved by the development of the outboard motor, the lack of facilities for cheap transportation has been a serious hindrance to the employment of capital in opening up the distant fields. The pre-Cambrian surface of Manitoba, like that of Ontario, is hummocky, with rounded hills and ridges of rock alternating with basinlike depressions and valleys occupied by lakes and rivers Or by many low-lying portions covered with muskeg' Routes to the mines have not usually been direct or easy and seasonal vagaries have presented problems in themselves. In summer, water transportation may be the cheapest method for the longer distances but it is not every water route that will satisfy the conditions of loading freight on to a boat or scow and of conveying it without interruption to its destination. By its location, a mine may require a large program of boat transportation in summer Over part of its route, to be followed by winter freighting for the remainder. In order to carry on development and produc- tion over a long period, it may be necessary to haul large quantities of supplies during the winter. This seasonal problem, particularly for the out-of-the-way properties, is SO important and demanding as to make it a major operation in the life of the mine. The -use of the tractor during winter months for heavy machinery and bulk supplies, and the use of the airplane throughout the year for the transportation of personnel and for emergency requirements, have greatly improved transportation to places that are inaccessible by rail. Canada has pioneered in both these methods. Development oF Transportation Twenty-two years have seen a marked change in transportation methods in Canada's mining country. Horse-drawn sleighs have given way to the tractor and that to some extent has been supplanted by the airplane. One of the earliest ventures involving transportation of considerable magnitude was that of the Mandy mine, on Schist at in northern Manitoba. According to accounts of early mining activities in Manitoba, the Mandy mine, beginning December 1916, had 3300 tons of ore hauled 40 miles by sleigh to Saskatchewan River and in summer this was conveyed by barge to The Pas, 130 miles, and then by railroad to Trail, British Columbia, 1200 miles. The mine shipped 6000 tons of ore in 1918 and 15,000 tons in 1919. In winter of the latter year, as many as 300 teams of horses were used on the 40-mile stretch to

Jan 1, 1943

By W. D. Robertson, H. H. Uhlig

INTRODUCTION THE intermetallic compounds Mg2Sn and Mg2Pb are two of the important series of stoichiometric compounds pounds which magnesium forms with elements of the fourth group of the periodic system, Since there is a complete series, of compounds, all possessing the same comparatively simple structure, a unique opportunity is presented to study their properties with respect to increasing atomic number of the anion as it varies from silicon and germanium, through tin and lead. The present work deals with the two lower members of this group, and it is hoped eventually that additional data regarding the silicide and germanide will be obtained. The results of such a complete study provide part of the essential basis for the empirical correlation and theoretical treatment which, in other systems, has contributed to an understanding of intermetallic compounds and the metallic state in general. Some experimental data are already available in the literature, However, they re fragmentary and limited in significance owing to the methods of preparation employed and the impure materials available at the time, It was our objective, therefore, using pure metals and improved metallurgical methods of preparation, to produce stoichiometric compounds of high purity for the study of their electrical and chemical properties. We felt that a detailed investigation of chemical properties, about which relatively little is known, combined with electrical properties, would be a significant contribution to the understanding of these compounds and in particular to the mechanism of corrosion associated with types of bonding in alloy systems. The chemical studies are reported elsewhere. PREVIOUS INVESTIGATIONS Previous work concerning the electrical properties of these compounds was undertaken in connection with the establishment of the two phase diagrams which are available in Hansen1 and Beck,2 The first comprehensive investigation of the electrical conductivity of magnesium-tin and magnesium-lead alloys was made by Kurnakov and Stepanov.3 This was followed by Grube and Vosskühler4 who studied electrical conductivity and thermal expansion over a wide range of temperature and who, unlike Stepanov, appreciated the significance of the large solid solubility of tin in magnesium and took some precautions to obtain an equilibrium state. However, at the time these investigations were made, neither pure magnesium nor

Jan 1, 1948

By George Bain

METHODS of mining building stone of any sort are planned to pro-duce as few fractures as possible, and present a strong contrast to methods of mining metallic ores, which must be crushed eventually and have fractures produced in as great profusion as possible. Shocks transmitted to a stone invariably make it more porous and more permeable and reduce its effective life, therefore methods of mining building stone involve as FIG. 1. THE SUPREME COURT BUILDING, WASHINGTON, D. C. This building illustrates the fine detail of workmanship, unprotected sharp corners and thin edges, and tall narrow columns characteristic of marble structures. These features require exceedingly coherent stone, and preservation of these features for decades or centuries demands many special quarrying precautions to keep absorption to 0.14 per cent or less, a detail not essential to stone for coarser architectural types. few shocks as possible. This is singularly true for marble because marble structures are intended to have long life, greater delicacy of line, more gracefulness and fineness of sculpture than those made from any other structural material (Fig. 1). So that delicate lines may remain in almost perfect preservation for decades, or even centuries, it is important

Jan 1, 1935

This brief introduction tries to introduce delegates to this conference to the almost unbelievable attributes possessed by many microbes which might be relevant to geomicrobiology, and how most of these remain unexploited by us. It introduces some of the terminology which will be used and tries to suggest that there are rewarding times for those who set out to discover the natural biodiversity of bacteria in nature. Although we have exploited microbes, usually unwittingly, and suffered at their hands for millennia, it is only recently that we have begun to become aware of how they dominate our planet (most of the earthÆs biomass is bacterial) and are responsible consequently for most of what happens here. A few can cause us harm and occasionally kill us, but most bacteria are beneficial, impacting positively for example on how we grow our food and in cleaning up the pollution we create. They are simply indispensable to how we live. They have been responsible for many of the geochemical changes which have taken place on this planet and play major roles in the transformation of elements so essential to our existence (Newman and Banfield, 2002). No one should dismiss them as minor players in our game of life.

Jan 1, 2004

By Michael C. Stanley

The set of discoveries for a mining district or camp is a reflection of the exploration history. In the western Abitibi greenstone belt of Ontario, future exploration can be guided by a study of statistical trends of known gold deposits. In this area simple trends indicate a strong decrease in the contained quantity of gold discovered through time. Much of this decrease is attributed not to falling mining grades but to smaller tonnages of ore. A plot of the largest discovery in each ten year time period suggests that deposit discoverability is following a size-biased sampling model. Cumulative ounces of discovered gold indicate that an asymptotic value has been reached where exploration is not expected to add significantly to known reserves. This is substantiated by a downward trend in the exploration success ratio of the number of new deposits discovered versus the number of new mineral prospects. The set of discovered deposits reflects a non-random sampling process where size- biased modeling suggests that the largest deposits will be discovered early in the exploration effort. It is the exceptionally large deposit contributing to the observed size-biased distribution. Although this pattern is observed for the western Abitibi the model is complicated by recent, large reserve additions that are attributed to the original discovery. There is present in this area a subtle learning process in exploration leading up to the largest discovery. For comparison a learning model was estimated using cumulative size of discovery per unit of time. This model yielded results consistent with the statistical trends and is thought to be a superior forecast of future discoveries in this region.

Jan 1, 1992

By T Galvin

Drilling and blasting at Westside Mine near Wallsend, NSW, has presented a challenge for Orica Explosives, Australia. The colliery produces 600 000 tonnes of steaming coal per year from two seams using surface mining techniques. Tapping into underlying coal will greatly improve the yield, but there are many issues which make this an enormous challenge. Hunter Valley Earthmoving engaged Orica Explosives to supply the explosives products and to provide much of the blasting expertise that is needed on the minesite. Hunter Valley Earthmoving and Orica Explosives have proven to be an outstanding, unified technical team on this project. The success of the team is based on good communication, progressive attitudes, extensive expertise in blast design and most importantly, care and accuracy in implementing the agreed upon designs.

Jan 1, 1999