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By Allan Sylvester, Paul E. Gabryszak, Diane R. Hirsch, David P. Field

With construction of the first phase of the Automated People Mover (APM) Tunnels nearing completion, this paper will address how knowledge from recent Tunnel Boring Machine (TBM) and New Austrian Tunneling Method (NATM) tunnel construction at the airport was used to refine the methodology for the next phase of tunnels currently in design. The benefits include an enhanced understanding of the ground conditions; allowing optimization of excavation sequences and support requirements; a more effective instrumentation and monitoring program; and improved construction details and related contract provisions.

Jan 1, 2007

By R. J. Kline

Most accidents are the result of risk taking. They can happen anywhere. Our coal industry categorizes accidents by type, occupation, commodity, age, every way you can imagine. We now know, how many were injured and when, for all the different types of accidents. We have ask ourselves many times, why are we having accidents, how can we stop the accidents and fatals in our industry? Present numbers and projections do not show that this will happen. Serious accidents can result in fatalities. Fatal accident can be prevented, and the coal industry can achieve zero fatalities. How soon this happens, depends on a great number of factors. I will discuss accidents and reasons for us having accidents in an attempt to get to the root causes. The historical perspective will be touched on, and the risk and analysis of accidents will be probed.

Jan 1, 2000

By I F. Wood

Planning for flooding and assessment of flood impacts are important requirements for mining projects, as they are also for other types of development. With more intense development and concern from the community, supported by government regulatory requirements, assessment of flood concerns and impacts has become of increasing importance. To ensure that flooding issues are fully understood and results presented in an appropriate format, advanced hydraulic analysis procedures have been developed and are beginning to be applied. These procedures must be rigorous in an engineering context but the results must also be readily understood by the community and government agencies. Advanced two-dimensional hydraulic modelling is becoming accepted as an important means of assessing flooding issues for mining projects. With presentation of results from hydraulic models with Geographic Information Systems (GIS), flood impacts can be analysed rigorously and presented clearly. This paper discusses the application of advanced hydraulic modelling in the planning and impact assessment of a major mining project located on a floodplain where there is extensive inundation. The analysis provides for both input to the planning of the project and for detailed assessment of potential impacts. This case study illustrates some important aspects of the application of hydraulic modelling using a two-dimensional modelling to a critical flood design.

Jan 1, 2003

By Joseph A. Holmes

Although Venezuelan production attained a new peak in 1938, passing the 190 million barrel mark for the first time, there was a distinct flattening of the steep upward trend that marked 1937 and preceding years. The annual total of 190,231,780 bbl. was only 31/3 million barrels above the 1937 figure, an increase of slightly less than 2 per cent, which contrasts sharply with the 20 per cent increase of 1937 over 1936. As in the previous year, the Lake Maracaibo fields supplied approximately 73 per cent of the oil produced, Lagunillas remaining the largest single contributor in spite of a 17 million barrel decrease in its annual output. Tia Juana increased its percentage of the Venezuelan total from 14.1 per cent in 1937 to 23.4 per cent in 1938; La Rosa showed little change with 13.7 per cent; Quiriquire in eastern Venezuela was also little changed with 13.2 per cent; Mene Grande, the only other field of real importance, declined from 7.7 per cent of the total in 1937 to 6.6 per cent for 1938. Two new fields, Temblador and Bachaquero, began actively to ship oil during the year, and by November were averaging 7600 and 10,000 bbl. per day, respectively. The former is in eastern Venezuela, and the latter is the most southern of the proven Lake Maracaibo fields. (A map of Venezuela was published in Volume 127 of the Transactions.) Table 1 gives a complete résumé of Venezuelan production by fields for 1937 and 1938, and shows that 1,685,575,663 bbl. had been produced to Dec. 31, 1938. The percentage contributed by each of the principal fields to this total is shown in Table 3, as well as their trends over the past several years. From these data it is apparent that the Maracaibo Basin is the principal source of Venezuelan production, and will probably continue to hold this position for some years. At the year's end 2657 oil wells were producing, of which 2425 were in western and 232 in eastern Venezuela; 36 per cent were on natural flow, 57 ppr cent were pumping, and 7 per cent were on air or gas lift. Out of 523 wells drilled, 507 producers were completed in 1938, five less than in the previous year and nearly 100 less than in 1929. These

Jan 1, 1939

By Joseph A. Holmes

Although Venezuelan production attained a new peak in 1938, passing the 190 million barrel mark for the first time, there was a distinct flattening of the steep upward trend that marked 1937 and preceding years. The annual total of 190,231,780 bbl. was only 31/3 million barrels above the 1937 figure, an increase of slightly less than 2 per cent, which contrasts sharply with the 20 per cent increase of 1937 over 1936. As in the previous year, the Lake Maracaibo fields supplied approximately 73 per cent of the oil produced, Lagunillas remaining the largest single contributor in spite of a 17 million barrel decrease in its annual output. Tia Juana increased its percentage of the Venezuelan total from 14.1 per cent in 1937 to 23.4 per cent in 1938; La Rosa showed little change with 13.7 per cent; Quiriquire in eastern Venezuela was also little changed with 13.2 per cent; Mene Grande, the only other field of real importance, declined from 7.7 per cent of the total in 1937 to 6.6 per cent for 1938. Two new fields, Temblador and Bachaquero, began actively to ship oil during the year, and by November were averaging 7600 and 10,000 bbl. per day, respectively. The former is in eastern Venezuela, and the latter is the most southern of the proven Lake Maracaibo fields. (A map of Venezuela was published in Volume 127 of the Transactions.) Table 1 gives a complete résumé of Venezuelan production by fields for 1937 and 1938, and shows that 1,685,575,663 bbl. had been produced to Dec. 31, 1938. The percentage contributed by each of the principal fields to this total is shown in Table 3, as well as their trends over the past several years. From these data it is apparent that the Maracaibo Basin is the principal source of Venezuelan production, and will probably continue to hold this position for some years. At the year's end 2657 oil wells were producing, of which 2425 were in western and 232 in eastern Venezuela; 36 per cent were on natural flow, 57 ppr cent were pumping, and 7 per cent were on air or gas lift. Out of 523 wells drilled, 507 producers were completed in 1938, five less than in the previous year and nearly 100 less than in 1929. These

Jan 1, 1939

By Homer E. Harris, William C. DeSieghardt, William A. Burgess

Under sponsorship of NIOSH, Eastern Associated Coal Corp., with the Harvard School of Public Health acting as a subcontractor, has determined for the first time the effective protection provided to working underground coal miners wearing approved half-mask dust respirators. This was done by conducting 187 man-shifts of in-mine testing in four different coal mines; included in this testing were 37 different test subjects representing 11 different job classifications and 5 different models of respirators. Presently available respirators on average provided significant protection levels to working miners even though on an intermittent use basis. However, "average" protection values were well below those achieved under laboratory conditions. Protection levels varied from man to man in a given work crew and from day to day for a given man. In addition, some of the factors affecting use and effectiveness of presently used respirators are discussed, as are areas in which improvements are needed, and the need to consider these improvements in context of a systems approach.

Jan 1, 1975

By B. R. MacKay

Introduction During the past six seasons the writer has been engaged in semi-detailed investigations on the coal areas lying along the front of the Rocky mountains between the Brazeau river and the Smoky River Coal Reserve (see Map, Figure 1). The purpose of this paper is to present some observations pertaining to the stratigraphy and structure of the district, touching especially upon the lithological units into which the Lower Cretaceous sediments have been divided, the thicknesses of the formations at different localities, the number, thicknesses and horizons of the principal coal seams, and the structural conditions which exist in the various fields.

Jan 1, 1930

By Feng Yongxuan

Anchored sheep pile is normally used in deep excavations, many of which only require stability in accordance with Terzaghi theory. In this paper, based on the experience, new lateral earth pressure method is adopted taking account into interaction among soil, anchors and sheet piles so that a group for the project under very difficult conditions and very severe requirments, especially, for the displacements are determined according to that mentioned above. During and after construction, displacements monitoring were carried out for about four months, which was proved that there was a little difference between calculation and practice.

Jan 1, 1991

By Gordon H. Geiger, John M. Svoboda

One mechanism of metal penetration into mold aggregates by cast steels is vapor state mass transport. In order to further understand and quantify this mechanism, the steady-state diffusion of metallic vapors was studied at 1250" to 1600°C in controlled oxygen pressure atmospheres by measuring the weight loss from a metal bath whose vapors were allowed to diffuse through a porous aggregate compact held at constant temperature. Mass transport rates substantially greater than those predicted from the assumption that the vaporizing species was the elemental metal vapor were observed. Vaporization rates were found to increase with an increase in the oxygen partial pressure in the gas atmosphere with maximum vaporization occurring at oxygen partial pressures just below those in equilibrium with a liquid oxide layer at the given temperature. When the liquid oxide layer was present, no vaporization was observed. Metal carbonyls were ruled out as the vapor species involved because of their thermodynamic properties. The species with the enhanced volatility were deduced to be gaseous metal-oxygen molecules, probably the polynuclear oxides (FeO)2 and (Mn0)2. Diffusion followed the ordinary diffusion mode, and Knudsen diffusion is not important in normal foundry molds. The interdiffusivities of the metallic vapors and the mold atmosphere, through the porous aggregates, were measured. The effective interdif-fusivity of the vapor species and mold atmosphere through the aggregate may be expressed as follows: Deff,12 - — where E is the void fraction of the aggregate and 7 is the "tortuosity factor". Aggregate material had no effect on diffusion rates, and the only relevant parameter was the void fraction. Values for 7 ranged from 3 to 6 for normal foundry aggregates with 4 being considered a good representative value. An area of interest in high-temperature metallurgical processes which has received little attention in the past is the diffusion of metal vapor species in porous aggregates. Research into the metal penetration phenomenon' in foundry molds has shown that a major penetration mechanism is the vapor transport of metallic species into the porous foundry sand molds, followed by condensation of metallic films on the sand grains. Considerable study of the vaporization of metallic species has been reported in the literature, and the vapor transport properties of many metallic species have been determined.2'3 Many instances have been observed where the vaporization behavior could only be explained by the existence of a metallic species with a vapor pressure greater than the elemental metallic species. These species were identified or, in some cases, presumed to be carbonyls,4,5 hydroxides,6-9 or vaporous oxides.10-16 The diffusion of gases through porous aggregates has received considerable attention in the literature pertaining to catalysis, although primarily at low temperature, and more recently in the literature concerned with ore reduction.17-22 The following experiments were devised and carried out in order to determine the nature of the metallic species involved in the metal penetration phenomenon, and the effective diffusivities involved. EXPERIMENTAL APPROACH Steady-state diffusion was selected for experimental convenience. The experimental systems used, shown in Figs. 1 and 2, consisted of a porous aggregate specimen contained in an impermeable alumina tube held above, and just separate from a metal bath. The entire system was held at constant temperature and pressure in a furnace with a controlled oxygen partial pressure atmosphere. After a brief period of nonsteady state behavior, a steady flux of metal vapor through the porous aggregate will develop due to the concentration gradient of metallic vapor in the gas phase. The flux of metallic vapor from pressure may be neglected because there is no pressure gradient. There is no flux from convection because there is no net flow of gas within the metal-aggregate system, and thermal diffusion is negligible compared to the flux from ordinary diffusion. If the material being studied is allowed to vaporize until steady-state behavior is attained, the experimental results may be analyzed using Fick's First Law.

Jan 1, 1970

By AIME AIME

N OW THAT the war is over it is possible to release data and correct some erroneous statements and impressions relative to the use of manganese-steel armor and helmets, which heretofore have been carefully guarded. The material of the helmets furnished to the English, American, and Belgian armies was invented by Sir Robert Hadfield, Bart., F.R.S., and was described in a paper read by him at the International Engineering Congress in August, 1893. The French helmet was 2 oz. lighter than the English but had a greatly inferior resistance. Tests showed that it was perforable at as low a velocity as 350 ft.- sec. impact of the standard shrapnel bullets. Helmets made of the Hadfield "Era" manganese steel kept out standard shrapnel bullets of the same quality at no less than from 750 to 950 ft.-sec. impact velocity. The respective energies were, in the case of the French helmet, only 0.021 ft.-tons, 46 ft.-lb., and in the British 0.095 ft.-tons, 213 ft.-lb. The German helmet was made of nickel-chromium steel and, although 12 oz. heavier and 12 per cent. thicker than the Hadfield, was not only perforate

Jan 1, 1920

By E. J. Roberts, E. B. Fitch

Most classifiers in use today are, in function, settling pools. A fluid suspension of particles is passed through a pool at such a rate that only a fraction of the particles-the coarser fraction-has time to settle out of suspension. The rest are carried on out of the pool as overflow. The most fundamental way in which such classifiers differ is in the mechanism used to remove the settled particles from the pool. The particles may gravitate from the pool, as in the various sand cones, or they may be conveyed mechanically from the pool by drags, spirals, or reciprocating rakes. The mechanism of settling pool classification and its limitations are discussed. A method for calculating countercurrent classifications is presented. The practical validity of the calculation method has been confirmed through 20 years of use within The Dorr Co. During this time it has been used on diverse feeds and has been checked against many types of settling pool classifiers, with close agreement in nearly every case. Excellent elimination of third critical mesh particles and finer ones may be obtained in a countercurrent classifications series where all stages separate at the same mesh, but elimination of first and second criticals is inherently limited. Spectacular elimination of all criticals may be obtained by arranging successive stages to classify at successively coarser mesh. Improvement in elimination is obtained at the cost of an increased internal recirculation, but this may be tolerable in many cases.

Nov 1, 1956

Average annual growth in consumption of primary energy in Australia over the past ten years has been 5.5% compared to a world average of 4.1%. Over the next ten years growth rate is expected to increase to 6% per annum due largely to the rapid development in the mineral processing industry. By the end of the 1970's natural gas is expected to supply more than 9% of Australia's, primary energy market. Coal will supply 40% and petroleum products 47%. Nuclear energy will make its appearance but-will only make a small contribution in the period. Australia has adequate reserves of natural gas and coal to supply its needs in the 1970's and beyond. However the newly developed reserves of crude, while supplying 60-70% of requirements-in the initial years; will need regular and sizable additions if they are to .keep pace with the expanding consumption. For Australia to become self sufficient in the period 1970-1990 it is estimated *that new discoveries-will need to approximate. ten times the volume of recoverable reserves found in Australia to date. .

Jan 1, 1970

By E. W. Shilling Harwick Johnson

The separation of hematite by hysteretic repulsion was first brought to the attention of the public in 1922, by W. M. Mordeyl. Three years later another paper2 was published and after another four years a third paper3 appeared in the South African publications. Certain data were lacking in these papers. In order to continue the work intelligently a knowledge of the shapes of the hysteresis curves for certain minerals was very necessary. This information was not available until the present year4. It was known that reduction of certain ores rendered them amenable to this process of separation but definite data in the form of curves showing exactly the effect of such treatment were lacking. Probably our best source of information on the separation of minerals by the use of alternating-current magnetic fields today is the reports from the U. S. Bureau of Mines5"7. It is not the purpose of this paper to tell the reader in detail how to make a commercial separator. Experimental models have recently been made? and the results obtained have been so good that it is the opinion of the authors that the public will soon take an active interest in the subject and its development. The writers have constructed a separator that is considerably different in construction and operation from the two types described by Mr. Davis. This will be described, but the real purpose of this paper is to outline certain experiments and give curves showing data that have a fundamental bearing upon the practical construction of a separator of this type. Specular hematite is usually considered nonmagnetic; that is, it is very feebly magnetic as compared to some other minerals. If specular hematite is placed in a steady magnetic field there is no apparent attraction. At the moment of closing the switch, however, some particles may be seen to move. If the field is alternating, the particles are con-

Jan 1, 1936

By E. W. Shilling Harwick Johnson

The separation of hematite by hysteretic repulsion was first brought to the attention of the public in 1922, by W. M. Mordeyl. Three years later another paper2 was published and after another four years a third paper3 appeared in the South African publications. Certain data were lacking in these papers. In order to continue the work intelligently a knowledge of the shapes of the hysteresis curves for certain minerals was very necessary. This information was not available until the present year4. It was known that reduction of certain ores rendered them amenable to this process of separation but definite data in the form of curves showing exactly the effect of such treatment were lacking. Probably our best source of information on the separation of minerals by the use of alternating-current magnetic fields today is the reports from the U. S. Bureau of Mines5"7. It is not the purpose of this paper to tell the reader in detail how to make a commercial separator. Experimental models have recently been made? and the results obtained have been so good that it is the opinion of the authors that the public will soon take an active interest in the subject and its development. The writers have constructed a separator that is considerably different in construction and operation from the two types described by Mr. Davis. This will be described, but the real purpose of this paper is to outline certain experiments and give curves showing data that have a fundamental bearing upon the practical construction of a separator of this type. Specular hematite is usually considered nonmagnetic; that is, it is very feebly magnetic as compared to some other minerals. If specular hematite is placed in a steady magnetic field there is no apparent attraction. At the moment of closing the switch, however, some particles may be seen to move. If the field is alternating, the particles are con-

Jan 1, 1936

By J. B. Bassett, E. S. Rowland

The experimental work reported herein firas inspired by the publication of a paper by Grange and stewart, in which it was suggested that at low chromium contents the effect of this element on the Ma point was greater than at higher chromium contents, It was argued that, if a small increase of chromium in solution in austenite caused a sharp lowering of the M, point, it might lead to an explanation of occasional unsolved stress cracking of SAE 52100 during heat treatment. Commercial hardening is carried out at temperatures of incomplete solution, leaving carbides available to enrich the austenite during any inadvertent increase in temperature, such enrichment of the austenite in chromium content would lower the M, point nearer room temperature where cracking is more likely to occur. According, it was decided to investigate the effect of chromium, in quantities between o and 2 pet, on the M, point of commercial steels. Fig I summarizes the data available on chromium steels. For purposes of comparison, the M, temperature values were corrected by means of the Grange and Stewart formulas to (I) Hypoeutectoid compositions: 0.50 pct carbon and 0.80 pct manganese (z) Hsereutectoid compos-sition': 1." pet carbon and O.35 pct manganese. Only the steels having compositions reasonably close to these corrected values were included, because large adjustments inevitably introduce increased error such as are experienced in using the formula. The straight lines of Fig I were drawn by the authors. These data obviously do not settle the question Of the effect Of chromium On the Md Oint, particularly at low chromium contents. While it is fairly well established that chromium causes the M, to be lowered when present in quantities of I pet Or more, Grange and Stewart1 have suggested that in small amounts (less than 1 pet) it is more effective in lowering the Ma point, while Klier and Troiano2 have suggested that in small amounts it is less effective in lowering the Ma point. Payson and Savage3 concur with Klier and Troiano and further suggest that the effect is not linear at these concentrations. Rose and Fischer4 report that small amounts of chromium actually raise the Ma point of a 0.20 carbon steel. Material Two series of 35 Ib induction heats were melted for this work, the analyses of which are given in Table I. One series was aimed at 0.50 pct carbon and 0.80 pct manganese with chromium additions in 0,25 pet increments from o to 1.5 pct with a single heat at 2.0 pct Cr. This series was considered necessary because the commercial heat treatment of SAE 52100 does not generally introduce more than about 0.60 pct carbon in solution in the austenite. The high

Jan 1, 1949

By J. B. Bassett, E. S. Rowland

INTRODUCTION THE experimental work reported herein was inspired by the publication of a paper by Grange and Stewart,1 in which it was suggested that at low chromium contents the effect of this element on the [M,] point was greater than at higher chromium contents. It was argued that, if a small increase of chromium in solution in austenite caused a sharp lowering of the [M,] point, it might lead to an explanation of occasional unsolved stress cracking of SAE 52100 during heat treatment. Commercial hardening is carried out at temperatures of incomplete solution, leaving carbides available to enrich the austenite during any inadvertent increase in temperature. Such enrichment of the austenite in chromium content would lower the [ M,] point nearer room temperature where cracking is more likely to occur. Accordingly, it was decided to investigate the effect of chromium, in quantities between o and 2 pct, on the[ M,] point of commercial steels. Fig I summarizes the data available on chromium steels. For purposes of comparison, the [M, ] temperature values were corrected by means of the Grange and Stewart formula§ to (I) Hypoeutectoid compositions: 0.50 pct carbon and 0.80 pct manganese (2) Hypereutectoid compositions: 1.00 pct carbon and 0.35 pct manganese. Only the steels having compositions reasonably close to these corrected values were included, because large adjustments inevitably introduce increased errors such as are experienced in using the formula. The straight lines of Fig I were drawn by the authors. These data obviously do not settle the question of the effect of chromium on the [M,] point, particularly at low chromium contents. While it is fairly well established that chromium causes the [M,] to be lowered when present in quantities of I pct or more, Grange and Stewart1 have suggested that in small amounts (less than I. pct) it is more effective in lowering the[ M,] point, while Klier and Troiano2 have suggested that in small amounts it is less effective in lowering the []M,] point. Payson and Savage3 concur with Klier and Troiano and further suggest that the effect is not linear at these concentrations. Rose and Fischer4 report that small amounts of chromium actually raise the-[M,] point of a 0.20 carbon steel. MATERIAL Two series of 35 lb induction heats were melted for this work, the analyses of which are given in Table I. One series was aimed at 0.50 pct carbon and 0.80 pct manganese with chromium additions in 0.25 pct increments from o to 1.5 pct with a single heat at 2.0 pct Cr. This series was considered necessary because the commercial heat treatment of SAE 52100 does not generally introduce more than about 0.60 pct carbon in solution in the austenite. The high

Jan 1, 1948

By I. Anazia

Selective fatty acid flotation of carbonate gangue from sedimentary apatites was achieved under acidic pH's without a specific apatite depressant and without conditioning the pulp with the collector. Concentrates (35-38% P205, 0.8-1% MgO) with high recoveries (80-85%) were produced from Indian and Chinese dolomitic ores. The calcareous and/or dolomitic-siliceous phosphate ores of South Florida and Utah required two flotation stages: one for carbonate removal, as mentioned above, and the other for phosphate recovery from siliceous gangue. Preliminary tests on the South Florida ore gave concentrates analyzing 29% P205 and 0.8% MgO with a P205 recovery of 76%. Data are also included showing the applicability of the process to the dolomitic-calcareous-siliceous Western U.S. phosphate ore from Utah. A concentrate obtained from this ore assayed 30% P205 and about 1% MaO.

Jan 1, 1987

By J. A. Caceres

Mining planning and mineral processing are almost two unconnected areas. The mining area builds its economical models considering the plant like a constant parameter: a constant throughput, an average recovery and a unitary cost. On the other hand, the mineral processing area assumes a mine plan with grades, ore type, work index, estimating the performances in an independent way. Previous researches have evaluated the advantage for increasing throughput by increasing the liberation size, thus sacrificing recovery. These valuables approaches have left behind the work index factor, critical variable for Recovery-Throughput capacity estimation. This study describes a method combining mineral processing and mining planning. This method incorporates the grinding and flotation performances into the mining economic models optimizing simultaneously the Throughput- Wi(Work index)- Recovery relations with mining sequence, cut-off strategies, and reserve schedules. This method has been used at Andina Mine Chile, showing 18% net present value increasing with minimum investment associated.

May 1, 2003

By C. E. Wood

[Because of the renewed i~,ortanc of the strate ic netal ~ngane8e the Bureau of Mines is conductin further ro~aarch on pyrometallurgica1 ~ethods of boneficiating 0 ngani.foro'l iron ores nnn lo\,f-~~r de oanganesc ores. Published data on .the l2~roI'let llurgica.l treatnent of tl::1.nganse8 ores have been revi .. \-'en by Jose-ph ? .2]

Jan 1, 1940

By M. M. Makhofane

Anhydrous zirconium tetrafluoride can be used as a precursor for the manufacturing of nuclear-grade zirconium metal. This can be done by fluorinating plasma-dissociated zircon with ammonium bifluoride in a batch reactor. This paper describes the batch process. It was proved that anhydrous zirconium tetrafluoride can be manufactured by this route as confirmed by X-ray diffraction. The process shows potential for scaling up to the kilogram scale and possibly the tonnage scale.

Jan 1, 2012