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By A. S. Hall

Significant pyrite often does not dissolve in the Sobek (1978) nitric acid extraction; therefore, the standard conservative approach is to estimate pyrite using sulfur present in the sum of the nitric acid and residual sulfur fractions. Alunite, when present, appears as residual sulfur. Because alunite does not generate acidic effluents, overestimation of AGP can occur if all residual sulfur is assumed to be undigested pyrite. Evaluation of 16 samples from the Florida Canyon Mine revealed that petrographic examination coupled with a modification of the Sobek method to include a 6 hour hot (250°F) 'nitric acid extraction resulted in a more accurate estimation of AGP.

Jan 1, 1999

By Jan M. Peter

The Early Norian Windy Craggy massive sulfide deposit is within the allochthonous Alexander terrane of the Insular tectonic belt in extreme northwestern British Columbia (Figure 1). Host rocks are the Middle Tats Volcanics, part of an informally-named volcano-sedimentary succession of mixed graphitic argillites and mafic pillowed and massive volcanic flows and sills of Upper Triassic age (Figure 2) that have suffered only lower greeschist-facies metamorphism. The volcanic rocks are light rare earth element (LREE)-enriched and display a variably developed back-arc subduction signature. Major and trace element compositions of the host argillite show that it contains an appreciable hydrothermal component, as evidenced by low high Fe and Mn contents. These sediments therefore record steady, continuous hydrothermal activity punctuated by intermittent turbidity currents sweeping into the basin. The deposit consists of at least two discrete sulfide lenses (the North and South Sulfide Bodies), as shown in Figure 3, a level plan at the elevation of the exploration workings. Published reserves at 0.5% copper cut-off are 297.4 million tonnes grading 1.38% Cu, 0.08% Co, 0.21 g/t Au and 3.9 g/t Ag (as of December 1991). However, the deposit is larger than this and further drilling is required to delineate it completely. Mineralization comprises massive sulfide, stringer/stockwork, and finely bedded to laminated sulfides and exhalites. Stockwork mineralization consists of sulfide-quartz-chlorite veins with attendant chlorite and silica alteration. Mineralization consists predominantly of massive pyrrhotite andlor pyrite with lesser chalcopyrite and magnetite. Figure 4 is an oblique section through the North Sulfide Body, the most northerly sulfide mass shown in Figure 3, which shows the distribution of the pyrite and pynhotite-rich massive mineralization and the stringer zone. The North Sulfide Body contains appreciable sphalerite, whereas the South Sulfide Body contains only trace amounts. Gangue minerals include quartz, chlorite, calcite, siderite, ankerite, stilpnomelane and magnetite. The minor hydrothermal exhalite sediments are comprised of chert, carbonate, and minor

Jan 1, 1993

By M. England

Test equipment has been developed to record automatically both the displacement of the pile head and the load applied during a conventional maintained load pile test. Some systems also have, in addition, been fitted with the facility for maintaining the applied load, as set by the operator, at very constant levels. The advantages are both commercial and technical, but a well trained operator has to be in attendance to control the test. Since typical test specifications in the UK require more than 19 hours to complete, it became inevitable that at least one equipment operator remained on site to expedite the test for its duration. Although electronic measurement and data logging of load tests may be more safe than previous direct observation of dial gauges. A single person remaining on a construction site alone is not to be recommended, even if they are just supervising the test. Further development of the testing system produced equipment which will perform the entire test specification as required without operator intervention. To achieve this, full automation is employed. The patented method particularly addresses the safety requirements and by using additional sensors, detects any uncharacteristic behaviour of the pile under test or of the reaction system and the equipment takes appropriate action in a controlled and safe manner. The quality of test data returned from these automated systems is a key element when analysing pile behaviour with models such as CEMSOLVE? and TIMESETTM. These analysis methods often indicate ground disturbance resulting from installation technique and have allowed pile design to be optimised using actual field data rather than theoretical considerations alone. An additional feature is remote access, this allows the data recorded to be transferred and the progress of the test to be viewed from practically any location. This permits experts to view the data 'live' and allows rapid diagnosis of any problems with the expected pile behaviour.

Jan 1, 2002

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Jan 1, 1938

By T. Bhambhani

Research at Cytec over the past two decades has shown that the traditional approach for ore metallurgical characterization (typically conducted via laboratory-scale batch flotation tests), which involves changing reagents and conditions one-factor-at-a-time, leads to several pitfalls. The chemical solution thus selected has a narrow un-optimized window of performance and will likely fail in the plant. A holistic approach, called the Flotation Matrix 100? process for ore metallurgical characterization, was developed at Cytec about a decade ago and has been successfully used to develop robust reagent solutions for several operations around the world. The premise for the approach is that flotation outcome from ores is variable and is determined by complex interactions between various physical, chemical and operational factors. A key component of the process is the use of efficient multivariate designs focused on the chemistry aspects (reagents and pulp chemistry), which helps identify the best processing conditions for each ore type, as well as the conditions resulting in poor performance. It also includes advanced statistical methods for dealing with the complexity and variability of experimental data. The holistic approach is illustrated in this paper with a case study on Pb/Zn ores. Using just 18 carefully designed batch tests, it is possible to partially simulate the behavior of each ore type in the plant. The best conditions for each ore type, along with the conditions to avoid, are identified. Along with this, insights are obtained into the reasons for high reagent dosages for certain ore types, and interactions between variables. Keywords: flotation, holistic approach, metallurgical characterization, multivariate experimental designs, base and precious metals recovery, sulfide collectors and modifiers, Pb/Zn sequential flotation

Sep 1, 2012

By Burkhard Seeger et al.

The oxidation of copper sulfides can be highly accelerated in the presence of nitrous gases (NOx) as reaction catalysts. Sulfur and sulfate are simultaneously produced in this highly exothermic reaction. This process, carried out in sulfuric acid medium, is performed at an approximately normal pressure and at a temperature of around 110 °C, in a closed container, adding either oxygen or air. The oxidation is automatically controlled through a computer. The process covers the following steps: Catalytic oxidation, filtration and crystallisation of the hot concentrated liquid, electrowinning, mother liquor treatment through jarosite formation, recovery of dissolved copper and zinc and regeneration of industrial water, and non-soluble residue treatment with extraction of sulfur and recovery of silver and gold. No combustibles are needed. No air is contaminated, and no waste water is produced. Solid residues are in a stable, non-toxic and non-corrosive state of equilibrium. Risk of accident is low. Investment costs are small compared to those of the comparable pyrometallurgical process, and production costs are competitive.

Jan 1, 1999

By J. S. Limb

Actual issues which arose during the discovery process or subsequent court testimony are presented. While most of these issues relate to the author’s specialty of mineral appraisal some are more general in nature and could be of interest to those who may be involved in current or future court testimony. Several important areas to be reviewed and agreed upon with the client and their legal counsel are discussed. General observations on litigation, the discovery process, testimony and some repercussion’s are also given.

Jan 1, 2001

Types of structure found in 'Jest Australian beach sands are described. Their recognition by geostatistical methods follows nth a discussion of the effectiveness of sampling patterns. Examples of structures are given, and an account of their effect on valuation procedures.

Jan 1, 1977

By I. C. Edwards, E. O. Lilge, H. H. Mccreedy

"Introductory and GeneralTHE DRIESSEN CONE bas been used fairly extensively commercially as a classifier. Its use as a concentrator in the upgrading of ores at a fairly high ratio of concentration with concomitant recoveries has been almost negligible. Certain known features about the cone, however, such as its high throughput capacity, cheapness of construction and operation, and simplicity of design have attracted the attention of mill men. An inadequate knowledge of the operating characteristics of the cone when used as a concentrator seems to have been the main reason for its lack of use. It was for this reason that the present investigations§ were undertaken to determine the operating characteristics of the cone and its application to the concentration of uranium ores, with particular emphasis being placed on the concentration of low-grade uranium ores.The investigations were started in December, 1951, and have continued uninterrupted to the present. The initial work was confined chiefly to investigating the operating characteristics of the cone in order to establish the trends that certain variables would exert on the general metallurgy of uranium concentration. Optimum metallurgy was therefore not the prime initial objective."

Jan 1, 1955

By A. E. Bibb, F. W. Kunz

A platelet form of zirconium hydride was found in zirconium and ZY-1 wt pct U single crystals containing hydvogen in the range of 50 to 100 ppm. The habit planes for the hydride plateletg in the zirconium crystals were found to be {1012}, {1121}, and (1122) while the habit planes in the ZY-1 wt pct U crystals were {1121), {1123}, and (1.231). With the exception of the {1231} plane, these have been identified as the twin planes in zirconium. The different effect of hydridc on the mechanical puoperlies of zirconium at high and low strain rates has been explained in terms of the defornzation mechanism and the habit planes of the hydride. ZIRCONIUM and zirconium-base alloys are considered for many nuclear reactor applications, where the pick-up of hydrogen is a distinct possibility, if not an unavoidable occurrence. An excellent example of this is the absorption of hydrogen by zirconium and its alloys during aqueous corrosion, where as much as 30 pct of the hydrogen produced by the corrosion reaction is picked up by the metal. Under the proper conditions, the absorbed hydrogen would precipitate as zirconium hydride and consequently alter the mechanical and physical properties of the zirconium-base alloys. The knowledge obtained from a study of the crystallographic aspects of the hydride precipitation is necessary for the interpretation of the observed changes in the mechanical and physical properties. The deleterious effect of hydrogen on zirconium-base materials is not always observed in normal slow tensile loadings at or above room temperature, but becomes immediately obvious under impact loading, where the energy absorbed decreases with increasing hydrogen content,' and in notched specimens where triaxial loadings are attained.2 This effect is of serious consequence in the applications of Zr where shock loads or high strain rates are experienced. The purpose of this investigation was to determine the crystallographic planes of the Zr and Zr-1 wt pct U matrices upon which zirconium hydride will precipitate and to correlate these with the observed mechanical property data. PROCEDURE Crystal Growth—Single crystals of Zr and Zr-1 wt pct U alloy were used in this investigation. The Zr crystals were made from sponge that had a typical analysis as shown in Table I. Large grains were grown in this material by rapid cooling an arc-melted charge in a button furnace. This operation undoubtedly lowered the volatile impurity concentration below those listed in Table I. Back-reflection Laue patterns of these large grains showed the presence of considerable substructure and lattice distortion within each grain. It was found that an 18-day anneal in an argon atmosphere at 840°C (a high a heat-treatment) followed by furnace cooling, resulted in the further growth of the large grains and removed the detectable substructure ana lattice distortion. Equiaxed crystals with a cube edge of approximately 1/4 in. were produced in this manner. Large crystals of Zircaloy-2 (1.5 wt pct Sn, 0.15 wt pct Fe, 0.1 wt pct Cr, 0.05 wt pct Ni) also were produced by this technique but the large amount of substructure formed could not be removed by annealing. The Zr-1 wt pct U solid solution crystals were produced from an alloy rod consisting of Westing-house-Foote hafnium-free crystal bar zirconium and depleted uranium. The chemical analysis of the alloy is also given in Table I. Three-inch sections were cut from an 0.120-in.-diameter alloy rod and tapered to a fine point on each end. The samples were sealed in evacuated Vycor tubes, homogenized for 5 hr at 1000°C in the ß-phase field, and slowly lowered in a gradient furnace into the a phase (800°C), annealed for 60 hr at this temperature to produce grain growth and furnace cooled. This technique produced large grains approximately 1/2 to 3/4 in. long over the entire cross section of the rod, which were free of observable substructure. Metallographic examination up to X1000 did not show the existence of any second phase in these grains. Crystal Orientation—All crystals were abraded on fine emery paper to produce two flat surfaces 90 deg to each other. The crystals were analyzed by the standard Back-Reflection Laue technique to obtain the crystal orientation with respect to the abraded surfaces. The Back-Reflection Laue Photograms of all crystals used were clear and sharp indicating that the crystals were free from any substructure that could be detected by these means. Hydriding—Only samples containing four to five grains were used for hydriding. Samples that exhibited fine grained patches were discarded. The samples were hydrided using the following technique. After etching in 48 vol. pct HNO3, 48 vol. pct H2O, and 4 vol. pct HF (48 pct) solution, the specimens

Jan 1, 1961

By Carlos Virrueta

"El presente texto señala la importancia del comportamiento seguro en el sistema de riesgos aplicados al comportamiento de los trabajadores, salud y medio ambiente para así establecer los lineamientos yresponsabilidades requeridos para realizar el programa de Auditorías de Comportamiento Seguro, fortalecer el compromiso visible de liderazgo de los equipos de trabajo, así como crear y fortalecer en las personas el hábito de la prevención de los riesgos."

Oct 21, 2015

By Fjeldstad Karin Jusnes

Two quartz types used in the silicon and ferrosilicon industry were heated to temperatures of 1600 and 1700 °C. The parameters varied were the temperature and the holding time at maximum temperature. The amount of quartz, cristobalite and intermediate amorphous phase were measured using XRD and the internal standard method. Type P showed a much larger ability to transform to cristobalite at lower temperatures than type A. Type P had a larger amount of alkali and alkaline earth impurities. This could have enhanced the transformation to cristobalite. For quartz type A the amount of cristobalite was larger at 1600 °C than 1700 °C. This can also be seen for some of the samples of type P at shorter holding times.

By Bill Morgan

This paper discusses the economic zones of application for several different types of earthmoving equipment: dozers, wheel loaders in load-and-carry applications, wheel tractor scrapers, articulated trucks, rigid-frame trucks and wagons. Only the medium to large pieces of equipment were considered. From this chart (Figure 1), you can see the size range, in tons of carrying capacity, of Caterpillar equipment and the specific models analyzed.

Jan 1, 1994

By Marshall B, Gee R. D

Geological data processing by machine enables'an increased rate of coverage, better supervision and control of field programmes, increased effectiveness of field operators, and vastly improved access to old and new field data. Even a system of restricted felxibility enables a mapping programme to be organ- ized and conducted independent of personnel changes, whilst elimination of much compilation time increases the rate of cover- age such that it relates to mode of transport and geological complexity rather than to personality factors. A machine is useful only if applied to tasks suited to its capabilities, and must be aimed at those types of mapping in which a limited number of attributes adequately define the problem, and the data is of a form suited to coding and is normally collected in sufficient abundance to make compilation wearisome. Machine systems are therefore unsuited to most types of lithological mapping and to most types of exploration in new areas, but have proved useful in many branched of cartographic geophysics (e.g. gravity and magnetics), and in cartographic Geochemistry.

Jan 1, 1969

By E. Martinez

Samples of chrysocolla, a hydrated copper silicate, from several sources were submitted to differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). Pure samples of chrysocolla are difficult to obtain, but comparison of the thermograms revealed that certain reactions occurred in all the samples and it is believed that these are due to chrysocolla. Endothermic reactions occurred at 50' to 175°C, 350° to 650°C, and 980° to 1100°C each of which caused a weight loss. The first was due to loss of absorbed water, the second to a dehydroxyla-tion, and the last to conversion of cupric oxide to cuprous oxide. In addition, two exotherms were detected at 685° to 695°C and 935° to 950°C. Infrared spectra of heated samples indicated the exotherms were due to changes in the Si-O bonds leading to the formation of cristobalite. The results suggest that thermoanalysis may be a more sensitive and reliable method for detection and identification of chrysocolla than X-ray diffraction, infrared spectroscopy, or optical techniques. The recovery of copper from oxide ores has been the subject of much research in recent years. One of the principal oxide copper minerals is chrysocolla, a hydrated copper silicate. The information available indicates that it has widely varying properties depending on the origin of the sample. Chrysocolla usually is found associated with cuprite, malachite, azurite, and native copper. Most of these other minerals are recoverable by present day flotation practice, but chrysocolla is lost in the tailings.1,2 Reagent combinations that are successful in laboratory chrysocolla flotation with ore from one source have been found to be ineffective with another. 3 The copper segregation process offers an altemative to beneficiation of oxide copper ores.4'5 The process is of particular interest in processing ores that cannot be treated by conventional hydrometal-lurgical methods because of high acid consumption.6 Fuller understanding of the properties of chryso- colla may prove of value in the search for improvements in both the flotation and segregation processes. Chrysocolla samples from Arizona, Nevada, Chile, Australia, and South Africa were studied by differential thermal analysis (DTA) and thermal gravimetric analysis (TGA). In addition, a sample from Miami, Ariz., was submitted to X-ray diffraction, infrared spectrophotometry, and surface area determination. EQUlPMENT Differential thermal analysis (DTA) detects, amplifies, and records exothermic-endothermic reactions occurring in a sample as its temperature is raised at a constant rate, usually 10°C per minute. A unit made by the Robert L. Stone Co. was used in this study. The tests can be run if desired with a gas streaming through the sample. A thermobalance records weight losses or gains in a sample as its temperature is raised at a uniform rate. The gravimetric analyses (TGA) were run on a Chevenard thermobalance converted electronically for graphic recording. A heating rate of 5°C per minute up to 1100°C was used in these tests. A Perkin Elmer Infrared Spectrophotometer, Model 221, was used with sodium chloride optics obtaining IR spectra in the 2 to 15 region. A pressed pellet technique with potassium bromide was used in preparing the samples. DESCRIPTION OF SAMPLES Chrysocolla is found in the oxidation zones of copper deposits commonly associated with malachite, azurite, and limonite. It is described as varying in composition and in color from bluish green to brown or black. Inclusions of other minerals are usual so chemical analysis of chrysocolla samples may be suspect. However, it is considered by many to be a solid solution of CuO, SiO2 and H2O with a general formula of CuO.SiO2.2H2O or 2CuO.2SiO2. 3H20. Chukhrov7 has described a sample from the Urals as CU3,5(OH)2 (A1Si3) O10.nH2O and stated that chrysocolla is a montmorillonite-type mineral. On the basis of X-ray analyses, DTA, and infrared spectra of chrysocolla from the Inspiration Mine, Ariz., Sun8 concluded that there was no substantial evidence to classify it as a montmorillonite mineral. Chrysocolla samples from many sources throughout the world were used in this investigation. The following is a brief description of each:

Jan 1, 1963

By H. P. van Ormer

The objective of this paper and the developed personal computer program is not to identify or try to identify the actual total drilling cost in any Rotary Drilled Blast Bole Program. The ideas put forth here and in the computer program developed are a very accurate way to measure what is often very hard to identify and interpret -The actual direct operating cost of various drilling package combinations including comparing with available blast hole sizes and patterns

Jan 1, 1988

By P. D. Gorsuch, I. R. Kramer, D. L. Newhouse

Although many methods have been suggested for the calculation of tensile strength and yield point from chemical composition, their usefulness has been limited to a particular cooling rate or section size. Further limitations have been imposed by failure to take into account many of the alloying elements that exert a considerable influence on the tensile strength or yield point. These systems, nevertheless, have filled an important need in many instances. The value of a system for the calculation of the tensile properties from the chemical composition and cooling rate is that it permits the prediction of the effect of alloying elements and heat-treatment on the mechanical properties, so that more efficient use of alloying elements may be made. Furthermore, it aids in the choice of steel for a given application aid tends to decrease the number of steels that otherwise would have to be tested. It is the purpose of this work to present a method of calculating tensile strength and yield point from the chemical composition and to suggest a method of correlating the tensile-strength and yield-point factors and cooling rate. Steelmakers have been interested for many years in the calculation of the tensile strength of hot-rolled steels. Quest and Washburn' summarize several of the attempts that have been made to devise formulas. They show the inadequacy of each of these formulas and present one of their own. It is apparent from their work that a simple additive equation of the type TS = A + BX + Cy + DZ + . . . , where A, B, C, D, etc. are experimentally determined constants and x, y, z, etc., are the percentages of alloying elements present in the steel, is not adequate to analyze fully the situation encountered in the calculation of tensile strength. For example, it was found that the difference between the calculated and observed values became progressively greater as the carbon and manganese contents were increased. Therefore, the effect of manganese was given as a function of the carbon content. Grossmann, in his work on the harden-ability of quenched steels, and Walter, in his method of calculation of tensile strength of normalized steels, present two cases in which multiplying factors were successfully used to express the combined effect of alloying elements. The factors in both cases were obtained from the fractional increase in hardenability or tensile strength with increase of alloy content. Yield point often is more important in design than tensile strength. For quenched and tempered steels a linear correlation exists between yield 2nd tensile strength.4 This is not true, however, for normalized

Jan 1, 1948

By Derek J. Barratt

The specification of the prime mover of an autogenous/semi-autogenous mill involves an analysis of the likely operating conditions within the mill and the choice of a nominal operating speed. For variable speed mills, the operating range for mill speed has to be defined so that mill power/torque requirement can be matched by the motor power/torque capability. This paper will describe how this relationship can be influenced by ore grindability.

Jan 1, 1993

By David T. Kao

The energy situation the world faced during the decade of the Seventies resulted in actions throughout the free world to reduce its dependence on OPEC oil. Many nations heeded the indicators early in that decade and commenced efforts to reduce their oil requirements. Those nations which did not heed these warnings had the message brought to them more emphatically in the last portion of the decade with the further rapid and continuing rise in prices of OPEC oil. Furthermore, the demonstrated unstable nature of large oil-producing countries has made it clear to all free world nations that their energy demands of the future must be provided for by some more stable and assured supply. Now, early in the decade of the Eighties, we see the need for expanded use of coal as an energy supply to be essential. The result in 1980 and 1981 has been a great increase in demand for steam coal worldwide. In essence, a new business for the United States has developed in steam coal export. In the United States, the large growth in foreign demand for our steam coal is now well recognized and documented. A major impediment in meeting this growing demand became abundantly clear in 1980. This impediment is the congestion existing at U.S. coal export ports. With the recognition of this constraint, a plethora of activity has been observed in announcements for alleviating the problem by improving and expanding current export port facilities. In addition to improvement and expansion, an abundance of totally new facilities has been announced in an effort to find ways to meet this large demand in the new business of steam coal export. This is needed; and hopefully, many of these plans will be translated into action. While total implementation of all stated plans is not expected, much of the implementation depends upon large- scale dredging, large waterside ground storage sites, and improved handling equipments in the conventional type of export ports. The time and capital required for implementation is great, and environmental problems associated with dredging are substantial. Host significantly, and unfortunately, implementation that does include dredging our ports will still not permit use of the truly large colliers of 140,000 DWT and greater, which are evolving as the "state of the art" in long-distance sea transport.

Jan 1, 1981

By Alfred E. Hunt

Professor EGGERTZ first published a method based upon the fact that, when steel is dissolved in dilute nitric acid, and heated until the separated flocculent carbonaceous matter goes into the solution, the liquid assomed a brown color proportionate in intensity to the amount of the combined carbon in the steel. This method has been so variously modified that at present but few chemists use exactly the same procedure. It is the object of this paper to present

Jan 1, 1884