Search Documents

By G. Barrasso, E. Nordheim

"The European aluminium industry, through its member organisation the European Aluminium Association (EAA), initiated a program on sustainable development for the aluminium industry in 2001. The first step involved the development of a set of sustainable development (SD) indicators for the industry, taking into account of the different interests involved and also the different existing conventions. The indicator set was developed during 2001 and 2002 with the assistance of recognised partners, including Wuppertal Institute from Germany and Versailles University from France. As well, both internal and external stakeholder groups were involved in order to validate the indicators. This has resulted in a set of thirty-four indicators used in the first survey exercise. In the survey the EAA, together with the national aluminium associations, attempted to cover all European plants producing alumina, primary aluminium, rolling ingots, extrusion ingots, foil and recycled aluminium -covering approximately 800 plants. The survey used two points in time, 1997 and 2002, in order to start developing a trend for the individual indicators and to measure progress over time. The industry response to the survey was very positive, with a total industry coverage based on tonnage reported of over 80% for 2002 data and 70% for 1997 data. The results also show a solid progress for most indicators and particularly for social indicators such as training performance, community involvement and employees health programmes. The EAA is committed to conducting this as a regular exercise and is engaged in a number of stakeholder workshops in order to present the survey results, to review the indicators used and to also consider adjustments of these based on feedback from stakeholders and experiences from the first data collection."

Jan 1, 2005

By Y. S. Kim, A. Bailey

A feasibility seismic refraction and reflection field survey was conducted at the U. S. Borax Company open-pit mine, Boron, California by the writers during the weekend of March 13 and 14, 1976. This field survey was carried out as a preliminary investigation primarily for the purpose of evaluating and establishing the ability of such geophysical techniques to locate and outline the subsurface openings of the old room-and-pillar mining under the present open-pit. The value of such knowledge about the old underground workings is directly related to the safe and economical operation of the open-pit mine for the company. Although mine maps of the old underground workings are available at the mine, the extent of roof and wall cavings and the present condition of the old underground openings are unknown. Owen and Suhler (2) are the first investigators who used electromagnetic methods, Pulse-Echo System, and electric resistivity measurement to solve the problem without success. A few years later, Herzig and Owen (1) attempted to solve the problem with application of earth resistivity measurement method with unfavorable results. The U. S. Borax Company carried out an extensive study for slope failure problems of the open-pit with application of dipmeter measurements. However, the slope stability study was not correlated to the old underground openings lying under the present open-pit (3).

Jan 1, 1977

By T. W. Martin, T. J. Crocker, J. M. Goris

The current technology of large rock conveyors is reviewed. Based on this investigation two large rock conveyor concepts have been developed and a test facility investigation designed and fabricated. The USBM will test these concepts along with loading and transfer points for handling mine run rock material up to 1.5 m (4.9 ft) in size. An evaluation of open pit mining systems using large rock conveyors documents substantial cost savings when compared to truck haulage.

Jan 1, 1983

By Edwin M. Chance

During the last decade many conditions have been encountered that have materially increased the cost of the production of coal. As in most cases it has not been practicable to increase the selling price of such coal sufficiently to insure the necessary margin of profit, the mine management has been forced to avail itself of what might be termed unusual means that costs might be held at as low a figure as possible. The so-called efficiency engineer has been called upon, costly power plants have been built and machinery has been installed to replace manual labor wherever possible. Another aid used recently to secure economies through the more intelligent production of coal, is the chemist. As the coal industry, barring the production of byproduct coke, does not at once give evidence of its need of the services of the chemist, the writer will endeavor to point out a few of the services that this branch of the staff has been able to render. The preparation of coal in the past has been carried on entirely upon an empirical basis, that is, the criterion adopted has been an ocular inspection. Unfortunately, the appearance of a coal and especially of an anthracite, has but little relation to its fuel value, and as long as coal is purchased for the heat that can be obtained from it by its combustion, the quantity of such heat that is purchased must be one of the principal desiderata in selecting or preparing a coal. Were coals purchased for use as bric-a-brac or for exhibition in museums it might be both wise and just to purchase them upon their appearance. After 4 or 5 years of investigation the fact has been established that coals of very inferior appearance, and I now have special reference to anthracite, might and often did possess heating and burning properties superior to those possessed by bright coals which in the past had commanded considerable and uniform premiums in the market. This being the case the question arose as to whether the trade could be convinced of this fact. While at first some difficulty was experienced in establishing the quality of such dull coals, still it was found that the real obstacle to the sale of these materials in the past had been the fact that the coal producers' own sales departments felt convinced of the inferiority of this type of fuel and when complaints were registered they were given ready credence. Upon convincing the sales department of the quality of this type of fuel, but

Jan 1, 1917

By I Warren, M P. Simpson

Adularia-sericite epithermal ore deposits have well-documented alteration mineral zonation patterns with distinctive geochemical signatures. Proper use of whole-rock geochemistry can provide useful vectors for exploration and can enhance efforts to characterise and quantify the mineralogy and intensity of hydrothermal alteration.   Analyses of Au and Ag provide the most direct vectors to orebodies, and pathfinder elements such as As, Sb, Hg, Zn, Pb and Se are similarly zoned around at least some orebodies. However, the minerals that contain these elements occur almost exclusively in veins, and therefore identifying geochemical vectors related to wallrock alteration that is zoned outward from orebodies is crucial for effective exploration.   Distal alteration zones contain quartz-illite-chlorite-carbonate-pyrite, whereas samples proximal to veins contain quartz-adularia-pyrite, with lesser though variable illite-chlorite-carbonate. Therefore, adularia-sericite epithermal ore deposits show K alteration in their cores. The resulting K-metasomatism can be evaluated in several ways. Areas that have been most intensely altered are commonly characterised by highest K contents, but these results can be complicated by variations in rock type across the prospective area. Potassium mass balance results provide a robust and rigorous assessment of K-metasomatism, however, knowledge about the composition of fresh rocks and correct identification of fresh precursor compositions of altered rocks are required. Three alteration indices provide effective evaluation of K-metasomatism: 1.   the K number, which is the ratio K/(2Ca+K+Na) (molar); 2.   Barrie values [(K2O * 100) / Sr]; and 3.   the Rb/Sr ratio. In most places these provide similar vectors, although K numbers can be complicated by the appearance of hydrothermal calcite and/or albite.   Plots of K/Al vs (2 Ca + K + Na)/Al (molar) allow estimation of the intensity of K-metasomatism and its mineralogical products, thereby complementing traditional XRD and petrographic studies of alteration minerals.

Jan 1, 2005

By Edwin Anatolio Calderón Vicuña

En la actividad minera, los costos de operación en perforación y voladura son importantes puesto que el logro óptimo de una voladura óptima, no debe afectar la eficiencia física y económica de las demás operaciones (perforación, carguío, transporte, trituración). En este sentido, el presente texto nuevos diseños de perforación y voladura en las vetas angostas donde se elimine la sobreexcavación y el costo de sostenimiento.

Nov 24, 1993

By R. R. Johnson

The Hama Mining Company owns and operates The Groveland Mine near Iron Mountain, in the Upper Peninsula of Michigan. The orebody is part of the Menominee Range of the Lake Superior District. The ore (generally known as Jasper taconite) contains an average of 35% iron ranging from 28% to 39% with an overall split of 60% magnetite and 40% hematite. The variations encountered throughout the orebody require a certain amount of blending to reduce feed changes to the mill. One of the variables which affects the crushers, as well as the mill, is the range of hardness which has a low of 7.9 and a high of 24.6 as measured by the Bond Twin pendulum impact and crushing technique. Reference is made to hardness only to point out its effect on crushing and wear rate variations. Over a period of time, these variables do, of course, average out. Mining of the low grade ore started in 1959 and has operated continuously to date. Preparation of the feed for conventional rod and ball mill grinding is accomplished by three stages of crushing. Reduction of crude ore is first passed through a 54 inch gyratory crusher; then through a secondary crusher; followed by two or three tertiary crushers in closed circuit with screens as production quotas require (Figure 1). Current demand to the crushers is about 5,200,000 tons of crude ore per year.

Jan 1, 1976

By James Sheridan

Risk can generally be defined as the possibility or chance of a loss corresponding to uncertainty. Analysis is the process for examining the components and relationships of a complex system in order to determine the impacts of its variables. Risk analysis is therefore a course of action taken to analyze multiple variables of a system that is subject to speculative outcome. When risk analysis is applied to mine development, it becomes the means for assessing and measuring those parameters that contribute to economic viability. Mining can be a risky business. It is composed of an assortment of factors that contribute to its financial outcome. Of these factors, the most consequential output is the net present value (NPV). Applying risk analysis in mine development can identify those factors having the most significant impacts and applying limits to those impacts. Mathematical computer modeling using Monte Carlo techniques is available and can be customized to suit specific mine development ventures. Essentially, those parameters that are not fixed values can have input variability. Rationally deduced engineering estimates should be the basis for determining the initial values applied as inputs in the models. Risk analysis therefore provides the user a means to identify, rationalize and assess the risks in mine development in an informed, calculated, and unbiased format for making economic decisions.

Jan 1, 2002

By Dale R. Andrus

Why is there such an increased thrust toward positive multiple use land management and where will it lead? History and purpose of the mining law of 1872. John Marshall discovered gold at Sutter?s mill near Coloma, California, on January 19, 1848, and utter chaos resulted. The great migration of people to the undeveloped western lands had begun. Prior to this discovery, copper, lead, and iron had been the minerals for which the laws were made. With this discovery of gold on the public domain, it became apparent that congressional legislation was necessary. This became even more apparent as each of the numerous mining districts which were springing up in California, and elsewhere in the west adopted local miners' customs to regulate their activities. Although these early miners acted under mining district rules and in some cases state regulations, they were, in reality, appropriating minerals without sanction of federal law.

Jan 1, 1970

By J. M. Rebstock

Recent re-classification of crystalline silica as a potential human carcinogen has resulted in a new limit of 0.1% free silica in bulk powdered minerals. Detection of silica at this level can be expected to severely challenge or exceed the capabilities of existing protocols for x-ray diffraction, the traditional method for free silica determination. Automated SEH-EOS analysis provides an attractive alternative method, with direct analysis of individual particles for the determination of the concentration of free silica, and a direct measurement of silica particle sizes. This paper will discuss automated SEH analytical procedures, sample preparation, and statistical considerations.

Jan 1, 1990

By Charles Barrett

THE copper-silver system presents several points of special interest in the study of segregate structures. The system is simple eutectic, with limited solid solutions terminal with the pure component metals. The extent of solid solubility decreases with decreasing temperature for both the copper-rich and the silver-rich alloys, thus offering a possi-bility for the formation of Widmanstätten figures and also a possibility for aging after quenching. In contrast to the structures studied previ-ously the structures in this system are unique in their; origin, for one terminal solid solution will precipitate the other, and ice versa. In most of the other systems for which crystallographic data on the precipi-tation (or transformation) process are available, either intermetallic compounds or intermediate phases partake in the decomposition process; the absence of such phases thus distinguishes this system. The lattice structures of the two solid solutions are identical in type, differing in lattice spacing by approximately 10 per cent; because of this it seems difficult if not impossible to predict on the basis of present theory either the outward form of the precipitate or the lattice orientation relationships between matrix and precipitate. The eutectic temperature in the copper-silver system1 is 779°C. At this temperature copper -dissolves 4.3 atomic per cent (7.0 weight per

Jan 1, 1935

By A. J. Rambosek

An evaluation of diamond-bit performance data accumulated from core drilling in quartzite shows that core recovery and physical characteristics of drill bits and diamonds have economic significance. Relatively inexpensive, low-quality, small Congo diamonds will perform as well as, or better than, other diamonds used as drill bart. M-type bits set with oriented Congo diamonds provide those engaged in core drilling with near optimum combination. Various factors that affect bit performance, including size of diamonds, size and type of bits, grade or quality of diamonds, and percentage of core recovered, are evaluated by means of tables, charts, and discussion.

Jan 1, 1958

By W. W. Weller

Low-temperature heat capacity measurements were conducted, and entropies at 298.15° K were evaluated for sodium monomolybdate (Na2Mo04), magnesium monomolybdate (MgMo04), and calcium monomolybdate (CaMo04). The 298.15° K entropy values were sodium monomolybdate, 38.1±0.3 cal/deg mole, magnesium monomolybdate, 28.4±0.2 cal/deg mole, and calcium monomolybdate, 29.3±0.2 cal/deg mole.

Jan 1, 1963

PROF RICHARD ÅKERMAN Stockholm, Sweden ANDREW CARNEGIR New York, N.Y. DR. JAMES DOUGLAS New York, N.Y. PROF HATON DE LA GOUPILLIERE Paris, France R.A. HADFIELD Sheffield England PROF HANS HOEFER Leoben, Austria PROF HENRI LOUIS LE CHATELIER Paris France M FLORIS OSMOND Paris, France JOHN E. STEAD Middlesborugh, England PROF DIMITRY CONSTANTIN TSCHERNOFF St Petersburg, Russia CHARLES D WALCOT Washingtion D.C. PROF DR HERMANN WEDDING Berlin, Germany

Jan 1, 1910

By Robert W. Freedman

The Bureau of Mines investigated methods of analysis of free silica in respirable dust, including both work done at the Bureau of Mines and work done elsewhere. The review covers both coal dust and noncoal dust, taking into account both existing and proposed chemical and spectroscopic procedures.

Jan 1, 1971

By S. M. Copley, M. Yankova, E. Y. Yankov, J. A. Todd

"Nanophased coupled growth structures, with spacings of -10 nm, have been observed in banded microstructures produced by laser melting hypoeutectic Ag-Cu alloys. These coupled growth structures comprised a Cu-rich phase of width - 1 nm and a Ag-rich phase of width - 9 nm. In this paper, microstructural observations of nanophased coupled growth structures in hypo eutectic AgCu alloys are presented. Laser beam velocities for the transition from banded to microsegregation free microstructures are modelled and compared with experimental values. Models are presented to show that, at a critical undercooling, initial growth of a Ag-rich, metastable, extended solid solution is rapid but slows to a halt as copper is partitioned into the liquid at the solid/liquid interface. Following nucleation, the coupled growth structure then grows until the partitioned copper is consumed, at which point growth of the Ag-rich solid solution is again accelerated. This cycle then repeats resulting in banded microstructures comprised of 750 nm of the Ag-rich extended, metastable solid solution, followed by 250 nm of the coupled growth structure.1. Structural Studies of Laser Melted and Resolidified TrailsPresented here are observations of laser melted and resolidified trails in Ag-Cu alloys obtained at beam velocities ranging from 0.7 to 34 cm S·I. When the laser beam is scanned along the surface (positive x-direction) with a velocity Vb a melt pool with the shape given in Fig. 1a moves with the beam. The isotherms move with the velocity, Vi,. = Vb cos.p. Calculations employing the thermal analysis of Kou, Hsu and Mehrabian [1] for the beam velocities of this investigation and for the thermal properties of AgCu alloys, indicated that, .p, the angle between the isotherm velocity and beam velocity should be small at the surface where microstructural studies were made. This prediction was supported by observations of trail cross-sections. Based on these observations, and the calculations which include latent heat effects, the isotherm velocity for observations near the surface in our investigation was taken to be 27 cm S-I."

Jan 1, 1994

By H. E. Rorschach

Activity in Oklahoma oil fields made 1937 one of the best years since 1926. During the year, 3454 wells were completed, an increase of about 25 per cent over the year 1936. Purchasers reports filed with the Corporation Commission of the State of Oklahoma showed a total of 221,842,-788 bbl. of oil purchased from leases in 1937, an increase of about 10 per cent over 1936. The assembly of a complete table of all of the oil fields in Oklahoma has not yet been achieved. Many of the early records of operators and pipe-line companies are incomplete. Table 1 includes all of the new fields, and this year there has been added work done covering pools discovered in previous years, so that most of the important fields in the state of Oklahoma are included therein. The outstanding development of the year was the discovery of the producing horizon classified as the Wilcox in western Payne County by the Mid-Continent Petroleum Corporation on a unitized block in sec. 18, Tp. 18 N., R. 2 E. This block is operated hy the Mid-Continent and owned in conjunction with the Carter Oil Co., Transwestern Oil Co. and Sinclair-Prairie Oil Co. Another important development of the year was the extension of the deep zone in the old Fox-Milroy area of Carter and Stephens Counties. Some of the other discoveries made during the year 1937 are South Cromwell, discovered by Sinclair-Prairie Oil Co.; Cromwell extension of the Fitts pool in Pontotoc County; discovery of the Langston area in Logan County; discovery of the Sporn area in Lincoln County by Skelly Oil Co. and the discovery of the North Wellston area in Lincoln County by Standard Oil & Gas Co. Table 2 shows the new oil areas discovered in Oklahoma during the year 1937 and areas that were discovered in 1936 but developed in 1937. Fox-Milroy Area.—Three wells were completed to the deep producing zone during the year. One of the wells completed in the early part of the year uas the Carter Oil Company's No. 1 Harley in sec. 24, Tp. 2 S., R. 4 W., 3 1/2 miles northwest of the original discovery well, the Ruth

Jan 1, 1938

By G. E. Steudel

The study of the possibility of effecting a lower cost in the manufacture of pig iron reveals the importance of the ever present question of slag chemistry and volume. Factors that determine slag chemistry and volume are the impurities in the ore available, the ash-sulphur content of the coke, and a flux material necessary to promote removal of sulphur. Of these, the ores present by far the major source of impurities and what may prove to be the lowest practical slag volume with desired chemistry in one locality may be considered low or high in some other center of iron manufacture. The Chicago district is not only blessed with ores of high quality, but with excellent coke and flux materials as well. It is the intent of this paper to discuss slag problems at the South Works only, where burdens consist of Mesabi ores, Michigan stone, and coke ranging from 7 to 9 per cent ash and containing an average of 0.57 per cent sulphur. Early in the development of modern blast-furnace practice, the consideration of slags was secondary to the many adjustments of mechanical difficulties, such as furnace lines, stock distribution, stove design for obtaining higher blast temperatures, improved chemical segregation and size of raw materials. Furnace operators, after making these improvements, turned their attention to the study of other refinements in practice, of which slag chemistry appeared to be the most important. It is only within the last two decades that operators have become familiar with the various aspects of slag compositions. The industry, while rather slow in its recognition, is indebted to such investigators as Rankin,1 Wright,1 Feild,2 Royster,2 McCaffery,3 Kinney,4 Holbrook,5 and Joseph,5 whose researches concerning the elimination of sulphur within the blast furnace and the effect of slag composition upon melting point, viscosity, and desulphurizing power have established criteria for the selection of slags of the requisite quality. Large slag volumes result in higher coke consumption and cost of disposal. Any attempt to lower slag quantity must be accomplished

Jan 1, 1940

By Keith Leonard Sutherland

AEROFLOAT 25 is a complex mixture of free cresylic acid with aryl substituted dithiophosphoric acids, sulphides, disulphides, etc. Its complete composition has not been published by the makers or patentees. It is prepared1 by the reaction between phosphorus pentasulphide and carefully selected cresylic acid. We have been informed that this acid contains no phenol and very little cresol, and that it is rich in the higher alkyl phenols, particularly the xylenols. The reaction between a phenol ROH and phosphorus pentasulphide may produce compounds of the following type:2 [ ] Except for the simplest type, the thiophenols (ii), the boiling points of these compounds lie above 300" C. The amounts of the thianthren compounds formed from the five xylenols (if all these are present) will vary according to the position of the substituents. In an attempt to ascertain something of the nature of the reagent, fractional distillation under atmospheric pressure was undertaken. At the outset, hydrogen sulphide was freely evolved, and-particularly below 200°, C.-the fractions had the strong odor characteristic of the

Jan 1, 1939

By N. S. Dalal, Xianglin Shi

"Electron spin resonance (ESR) spin trapping experiments have been carried out to investigate the mechanism of sulfite oxidation em¬ploying 5,5-dimethyl-l-pyrroline-1-oxide (DMPO) as a spin trap. The results show that sulfite autoxidation, catalyzed by Mn(II), involves not only the SO-3 radicals but also the •OH radicals. An addition of H2 02 to the sulfite aqueous medium significantly increases the •OH radical formation. This result provides new clues to the chemical mechanism of the sulfite oxidation and the sulfite toxicity.INTRODUCTIONStudies of the oxidation of the sulfite (SO 2-/3) ions under various conditions are of high current interest because excessive exposure to sulfite is toxic and the origin of this toxicity seems to involve sulfite oxidative pathways [1]. An important fact is that human exposure to sulfite is on the increase [1,2]. Some of the increase in the sulfite exposure is linked to the fact that SO2 is a major air pollutant [2] and in aqueous media SO2 exists in equilibrium with SO2-/3. In addition, beverages and foods are common sources of sulfite intake. For example, sulfite is used extensively in the wine industry as an inhibitor of yeasts and bacteria and is present in finished wines in concentrations up to 6 mM [1]. Sulfite is also often added to dehydrated fruits, vegetables and soups, as well as fruit juices and beer [1,3,4]. Because of these, the mean daily intake of sulfite from diet (in the United States) has been estimated to be between 0.0014 and 0.14 mM/kg body weight [1]. At such high levels, sulfite exposure can have toxic effects, such as the induction of an acute asthmatic state [5,6]. Sulfite also appears to have adverse genetic effects [7] and can act as a mutagen or comutagen [8] and a cocarcinogen [5,7-9]."

Jan 1, 1990