Search Documents

By Xiang Zhang, Junjie Liu, Zhibo Tong, Langsha Shao, Guojun Ma

The aqueous mineral carbonation process that leaching alkaline earth metals from industrial residues by ammonium salt and carbonation thereafter is one of the potential technologies for CO2 sequestration. In this paper, the effect of particle size of waste slag on the leaching rate of metals under a microwave field and effect of microwave irradiation on the carbonation process were investigated. It was found that the initial leaching ratio of Ca decline seriously with the particle size of EAF slag increasing, and the Ca leaching ratio is relatively low during 120 min leaching. The lower leaching ratio of Ca with large particle size is due to the existence of a silica product layer produced on the surface of calcium silicates. Moreover, due to the microwave irradiation, the leaching ratio of calcium and the crystallization rate of calcium carbonate increase, though the particle size and distribution range of calcium carbonate reduce.

Mar 1, 2018

By R. M. Larsen

The Rocky Mountain region is defined with some variations for different purposes or by different organizations. For oil and gas development, Wyoming, Montana, Colorado, northwestern New Mexico, and Utah are included in the order of their apparent importance. Portions of adjoining states, such as North and South Dakota, Nebraska, Arizona, Nevada, and Idaho, arc attributary to this region, but have little or no oil or gas production. Nebraska and New Mexico are considered separately (see pp. 412 and 415), and most of the discussion in this report will be confined to Colorado, Montana, and Wyoming. Utah has produced about 200,000 bbl. of oil from the San Juan and Virgin fields, which are isolated and shut in at present. The Clay Basin field in northeastern Utah produces natural gas and distillate, and the Farnham field in central Utah produces carbon dioxide gas. Other Utah areas of some interest are listed in Table I. The Cedar Creek (Baker-Glendive) field in southeastern Montana extends into North Dakota, but is listed under Montana. The other states are in the main wildcat areas, and exploration in 1944 was at a minimum. However, geological and geophysical parties are reviewing them for further testing. Oil production in Colorado, Montana and Wyoming was 459,000 bbl. more than in 1943. Increases of 713,000 bbl. in Colarado and 731,000 bbl. in Montana offset a loss of 985,000 bbl. in Wyoming. This was the first decline in Wyoming since 1938. Field production figures and state totals are given in Table I. Total drilling activities in these three states and Utah increased from 687 wells making 1,442,511 ft. of hole in 1943 to 916 wells making 2,245,803 it. in 1944. Wildcat drilling increased from 163 wells making 331,193 ft. of hole in 1943 to 171 wells making 389,144 it. in 1944. These figures include all drilling wells making footage, not starts or completions, and represent an all-time high in drilling. The year 1944 witnessed the greatest concentration of seismograph activity that the region has had. The Rocky Mountain Oil Scouts Association reported that in 1943, the previous peak year, 91 crew months of work were performed; in 1944, the time was 254 crew months. About 67 per cent of the work was in Wyoming, 18 per cent in Montana, and 12 per cent in Colorado. Twenty-three blocks totaling 400,000 acres were reported assembled in Colorado, and 161 blocks totaling 4,000,000 acres in Wyoming. Information about other states was not given. Fourteen unit agreements were approved by the Department of the Interior, as compared with 13 in 1943. The 1944 agreements were all in Wyoming. In five of the unit areas, oil or gas discoveries were made, four were dry, and five were drilling Or pending' Oil companies find it advantageous to unitize blocks containing any proportion of public domain. Units for

Jan 1, 1945

By YU. F. Vasyuchkov, K. Vasioutchkov, B. M. Vorobjev

Introduction It is now believed that, even with the environmental protection measures now being taken, the further application of traditional coal-mining and electric power-generation technologies will inevitably cause further irreversible damage to the global ecosystem. Further improvements in conventional coal-mining technologies, both surface and underground, are expected to have only limited impacts on the economical, ecological and social aspects of coal mining. In countries with a developed coal industry, coal reserves with favorable conditions at shallow depths are rapidly being depleted. Therefore, in the future, more coal will be mined from deeper levels, resulting in higher operational costs and lower labor productivity. The solution to this problem is to be found in developing, promoting and implementing unconventional coal-mining and advanced clean-coal technologies. This paper presents an unconventional concept that has been suggested by the authors. The basic goal is to achieve coal-methane energy resource conservation and to remove barriers to energy efficiency through the adoption of integrated, ecologically clean, innovative technology. The following principles form the foundation of this concept: Energy resource conservation: This principle concerns the exploitation of actual and potential coal-methane reserves in the most effective way with the lowest possible losses and with the application of the most energy-efficient electric power-generation technology. Energy conversion: Energy conversion means the conversion of solid coal to synthetic fuel gas (in situ or in-cycle), the conversion of methane bounded within the coal matrix to free-flowing drained meth¬ane, the conversion of solid coal in situ to a coal/water mixture (slurry), and the conversion of these gas fuels into electric power. Technological and managerial integration: This prin¬ciple means an integration of coal-gas methane min¬ing operations and electric power generation into one commercial mine-to-product enterprise with electric power as the final product. Thus, coalbed methane drainage and coal gasification (both in situ and in-cycle) integrated with a combined cycle of electric power generation constitutes a highly integrated coal-gas methane energy-generation system. The system can be materialized in the form of a local integrated coal-gas electric power complex (LICGEPC). General features of the new concept The coal-gas-methane electricity concept is actually a synthesis of the following four technological components: Coalbed methane drainage. This technique and its utilization attained recognition after commercial operations were proven successful in the San Juan and Black Worriers coalfields in the United States. Worldwide, extensive field experiments and research-and-development activities are being carried out in the area of coalbed methane exploitation and utilization. Recently, coalbed methane drainage for power generation has been undergoing intensive research and development. At the Harworth Colliery in the United Kingdom, a combinedcycle power plant has been built that uses coalbed methane. The plant has an installed capacity of 15 MW Also, Germany, Australia, the CIS and China have conducted various experiments and industrial tests on the use of coalbed methane power generation. Underground coal gasification. Another unconventional technological approach is underground coal gasification (UCG). A number of semi-commercial, demonstration and pilot projects have been undertaken in Russia, the Ukraine, Uzbekistan, the United States, the United Kingdom, Italy and Belgium to demonstrate the technical and economical viability of coal gasification in situ. In Uzbekistan, the Angren coal-gasification station has been in full-scale commercial operation for two decades. The operation supplies a power plant with synthetic coal gas. Under sponsorship of the US Department of Energy's Morgantown Energy Technology Center, large-scale laboratory tests simulating coal gasification in situ were successfully completed by the

Jan 1, 1999

By M. P. Tixier, K. S. Kunz

A method for the interpretation of temperature curves recorded in gas producing wells is described. One essen-tial feature of the method is a simple graphical construction which conveniently reflects the amount of gas flowing from a given producing formation. This method, applied in conjunction with the Induction Log and radioactivity logs, is valuable to determine the points of entry of gas and to estimate the over-all thickness of the producing zones and their respective contributions to the total production. The method in particular is helpful in evaluating the effect of fracturing operations. An outstanding result of the application of the method is to bring to the light the relative importance of sand-shale interfaces in the production of gas. The paper is illustrated with field examp1es. INTRODUCTION The electrical logging tools involving conventional systems are not applied in wells which do not contain water base mud (empty holes, or wells filled with oil base mud), because of the absence of electrical connection between the electrodes and the surrounding formations. It is, therefore, common practice in this case to use other methods which do not require the presence of a conductive fluid in the borehole: resistivity log with scratcher electrodes, Induction Log, radioactivity logs, temperature log. . . . Such conditions are encountered in some regions, as the San Juan Basin, N. Mex., where a technique of drilling gas wells, using gas as a drilling fluid, has been introduced in the last two years. By the middle of 1953, an appropriate method for the logging of these wells was devised on the basis of field tests and of theoretical studies. It is the purpose of the present paper to give a description of this method. In these wells the logging operations are performed during the process of gas production, so that the temperatures in the boreholes are strongly affected by the cooling due to the expansion of the gas. On the other hand, a special thermometer, with a high sensivity and a short time constant, has been recently made available, which has enabled much more detailed and accurate recordings of the borehole temperatures than with the conventional instruments. As a result of these two circumstances, the temperature log constitutes the essential element of the method, in making possible the detection of the gas producing zones, the definition of their boundaries, and the estimation of the respective contributions of each separate zone to the total production. The method also involves the radioactivity and Induction Logs, as auxiliary documents. These logs in the present instance are helpful in the determination of the reservoirs. However, the information they give in this respect is limited. This comes from the fact that, due to the absence of the MicroLog and/or MicroLaterolog and of the SP log, the estimation of formation factors and connate water salinities is somewhat conjectural. Furthermore, little help is obtained from the Neutron log for the evaluation of porosity and of formation factor because the variations of gas saturation affect the Neutron log in a way similar to the variations of porosity. It should be said also that even an exact knowledge of the gas saturation of the reservoir beds would not

Jan 1, 1956

By H. S. Sichel, W. J. Kleingeld, C. E. Dohm

A model of ore value distributions is presented that is the culmination of a statistical approach rather than simply a model that has been successfully applied to the evaluation of ore reserves. Detailed geological and physical observations based on large sampling data sets have been used to support the statistical modelling. Fundamental to the modelling process is the concept that the occurrence of a given grade value in space is a function not only of the presence of the mineral but also of the fact that it is associated with a specific trapping mechanism. The concepts have been specifically applied to gold mineralisation

Aug 1, 1995

By V Rimal, d M. Tangstad

Multiphase slags form the basis of the reduction pathway for manganese ferroalloy production. The present work aims to understand the flow of slag through the coke bed based on experimentation in controlled conditions. Synthetic slags of different basicities were evaluated for their phase composition, viscosity, and flow. The two-phase slag will have two zones: a liquid slag zone and a multiphase zone. The multiphase zone will consist mostly of a solid phase with some liquid slag between the solid particles. The multiphase part will hence have a high viscosity. The liquid zone will flow into the coke bed while the multiphase area will stay. With increasing reduction, the multiphase area will decrease in size until the solid phase is gone and the whole slag will flow into the coke bed. The effective viscosity of slag will decrease with the lowering of the solid oxide phase. The results from flow experiments confirmed that the segregation of phases occurs when slag flows through the coke bed. It is observed that the flow is dependent both on the size of the void and the viscosity of slag.

Aug 21, 2024

By R. C. Jr. Babcock, V. S. Znamensky

The Pyke asbestos deposits were discovered by Kennecott Explorations (Australia) Pty. Ltd. in 1969 during the course of base metal exploration on the South Island of New Zealand. Extensive occurrences of chrysotile asbestos were found associated with the Red Mountain ultramafics in the headwaters of the Pyke River, and to the north and south along the ultramafic belt for a distance of 70 km. Surface evaluation and drilling by Kennecott in 1970 and 1971 identified numerous small deposits of good grade fiber in the Little Red Hills between the Pyke and Barrier Rivers. Additional drilling and three adits have been completed by other companies since that time. The property is presently held by Lime and Marble, Ltd., of Nelson, New Zealand, and Kennecott Explorations (Australia) Pty. Ltd. This chapter presents the regional and local setting of the asbestos deposits, including the geology and nature of mineralization. In addition, the exploration methods used by Kennecott in the discovery and evaluation of these deposits are outlined. Subsequent work by other companies is mentioned, but not de- scribed in detail. This subsequent work did not alter Kennecott's conclusions or produce any serious changes in the interpretation of geology and mineralization. The author acknowledges the contribution of the many employees of Kennecott Explorations (Australia) Pty. Ltd. who have been involved in the project. In particular, thanks go to Ramon Farmer, N.G. Corner, and A.W. McConie, who were responsible for completion of field work and reporting on the project. The responsibility for the conclusions and interpretations of this chapter are solely that of the author and result from his involvement in the discovery of the deposits and management of the exploration program. REGIONAL SETTING Ultramafic rocks on the South Island of New Zealand are thought to be Permian in age and occur between crystaIline and metamorphic continental rocks of Precambrian through Cretaceous age in the west, are thought to have once been part of the Antarctic subcontinent, and the extensive geosynclinal graywacke deposits of the Mesozoic New Zealand geosyncline in the east. They consist of the Dun Mountain ultramafics, a 130 km long segment of ultramafic rocks located at the north end of the South Island, and the Red Mountain ul- tramafics that occur in a zone 200 km long in the south half of the South Island as shown in Fig. 1. These two belts, once contiguous, have been offset a distance of 560 km by the still active Al- pine fault, which is analogous in character and offset to the San Andreas fault of the United States. The ultramafic rocks occur within a sequence of Permotriassic volcanic and sedimentary rocks that probably formed at the eastern margin of the continental plate. The ultramafics appear to be tectonically emplaced between Permian lithologies in the Dun Mountain belt (Coleman, 1966), and at the base of or between Permian volcanics and sediments in the Red Mountain belt. The Permotriassic ultramafic volcanic sequence of the Red Mountain ultramafic belt appears to be a typical ophiolite sequence. Ultramafic rocks, mixed mafic intrusive rocks and volcanics, volcanic rocks, and volcanoclastic sediments occur in apparent superposition from east to west in the area of Red Mountain. Farther south, ultramafic rocks are associated with basaltic volcanic rocks and some sediments, and still farther south are emplaced entirely in sediments. These structural compIications of the normal ophiolite sequence have resulted from the coincidence of Permian subduction, early Mesozoic extension and sedimentation, and Cretaceous subduction along the same plate margin (Landis and Bishop, 1972). The general geology in the area of the Red

Jan 1, 1986

By W. C. Yates

Lack of visibility from large, open-pit haulage truck cabs has become a serious safety problem. Anaconda conducted a research program to develop a low cost system to alert haulage truck operators to small vehicles present in blind areas. Several systems were developed and tested. As open-pit haulage truck size has increased, so has the size of the blind areas. Mine utility vehicles, pickup trucks, and cars are concealed within these blind areas and become safety hazards. Figure 1 shows the typical blind areas of a 136 t (150-ton) haulage truck. The areas of greatest concern are at the rear center and front right corner of the truck. In these "no visibility" areas many small vehicles have been crushed by large haulage trucks at various mine sites. In most instances, the occupants escaped the vehicle before it was destroyed. But injuries and death have occurred. In most cases, the accidents were attributed to negligence or carelessness by the small vehicle driver. The limited visibility problem still exists, though, and a solution is needed. Initial Solution The usual plane mirror on the driver's side and the convex mirror on the right front of the haulage truck allow only limited rear visibility. The typical, right side convex mirror is generally small and difficult to locate at a glance. This convex mirror also presents an image that distorts distance perception. These mirrors are of¬ten broken and immediate replacement not demanded or made. The US Bureau of Mines, in a contract with M.B. Associates, San Ramon, CA, developed an improved visibility system. It consisted of a larger, left view mirror and unique, blind area viewer. The large 230 x 690 mm (9 x 27 in.) left mirror has a small convex spot mirror near the bottom. The entire unit can be quickly replaced if broken. The large size provides a full view of driver orientation features such as the rear tire and the top of the load bed. The right 300 x 410 mm (12 x 16 in.) mirror has a convex surface and is quite rugged. The 510 mm (20 in.) spherical radius presents the operator with some distance distortion, but objects in its view are easily seen. The "blind area viewer" consists of a modified fresnel lens that allows the driver to "look around the corner." Installation of three of these lenses on the front of each haulage truck is rec¬ommended for adequate blind area coverage. This system significantly increases an operator's field of view and allows viewing of objects within about 3 m (9.8 ft of the truck. Many open-pit mines are nor mounting on smaller vehicles a long whip with a flag and lamp or both. This increases vehicle visibility to haulage truck operators. The whip is permanently attached to the mine vehicle. It can also be magnetically attached to transient vehicles. The whip system. though, is inadequate for visibility in the critical rear and right front blind areas. Alternate Solutions All of these visibility aids as¬sume an attentive driver. In addi¬tion, areas such as the rear blinc, area are not covered. Based on the inadequacy of existing visibility systems, Anaconda made a com mitment to further the truck de¬tection technology. The best ap¬proach was considered to be ar active system. It would notify the haulage truck operator that an en¬croaching vehicle is present. Sev¬eral systems were considered, in¬cluding ultrasonics and elec¬tromagnetics. For the ultrasonic system, com mercial and in-house design were looked at. Designing an( building transducers with the spe cific beam shape to match the haulage truck blind spots re¬quired a major technological breakthrough. False alarms ap¬peared difficult to prevent en¬tirely. They were caused by pass¬ing, trailing, or leading vehicles a., well as nonthreatening objects. As a result of these problems, the ul¬trasonic technique was not pur sued. An alternative, an electro

Jan 7, 1982

By A. Bascetin

One very important aspect of mining is deciding what material in a deposit is worth mining and processing, versus what material should be considered waste. This decision is summarized by the cut-off grade policy. The cut-off grade strategy for an open pit mine influences the annual cash flows and affects the net present value of a project. The optimization of cut-off grade strategy requires the knowledge of detailed operational costs, mining sequence, mining operation, processing, and product constraints, as well as the grade distribution of a given deposit defined by pit, phase, and different material types. Cut-off grade optimization algorithms have been developed in the past. The most common criteria used in cut-off grade optimization is to maximize the net present value (NPV). This paper describes the determination of a cut-off grade strategy based on Lane?s algorithm adding an optimization factor based on the generalized reduced gradient (GRG) algorithm to maximize the project?s NPV. The introduced algorithm is a windows based program developed at Virginia Tech that is based on a series of Visual Basic routines within a spreadsheet environment (Excel).The benefits of the methodology are demonstrated using a hypothetical case study. Keywords: Cut-off grade optimization, net present value maximization, generalized reduced gradient algorithm method.

Jan 1, 2007

By Wayne E. Kilker, Michael J. McBride, William P. Levy, Thomas J. Lamb

Between 1989 and 2004 the Massachusetts Water Resources Authority (MWRA)constructed several major wastewater and water tunnels associated with three major projects in the Boston area of eastern Massachusetts. There were many similarities and differences in the bedrock conditions encountered and among the contractual approaches for these independent projects. Through a clarification of the approach similarities and analysis of the contract differences, this paper addresses and presents what are considered to be valuable lessons learned. In doing so, the paper follows the evolution of such disparate issues as contract conditions, baseline reports and dispute review boards. The authors believe that the lessons learned even represent what, in certain cases, could be referred to as “universal truths” that are intended to have application to the next generation of tunneling contracts.

Jan 1, 2005

By Robert L. Lagace

This report presents a mathematical model for the propagation of UHF radio waves in the large cross-section tunnels of a room and pillar limestone mine, and describes the analysis of a small amount of propagation data obtained in a limestone mine. The model and analysis is based on the waveguide mode theory developed earlier for the transmission of UHF waves in coal mine tunnels, with allowance for propagation losses due to refraction into the tunnel walls, to scattering by wall roughness, and to long range random tilt of the walls. Propagation around corners and through pillars is also examined based on a ray theory approach, together with the beneficial effects of placing reflectors at intersections to significantly reduce corner losses. The theory is found to be in fair agreement with the data; however, additional in-mine measurements are needed to provide a more conclusive test of the model.

Jan 1, 1979

By Nelson Sánchez

The Los Bronces Development Project (LBDP) was approved in October 2007 by the Anglo American plc Board at a capital cost of some US$1.74B, and is scheduled to be completed by the end of 2010. The project represents a big step forward for the Los Bronces mine since it will increase the treatment rate by 140%, the mining rate by 64% and almost double copper production during the first four years of the project. This economy of scale will also position Los Bronces as a much bigger and efficient mining operation, better prepared to face adverse market scenarios and allowing Anglo to consolidate its position in base metals. The project addressed numerous scope alternatives such as plant capacity vs mine capacity, cut-off grade strategy to maximise value based on the existing flotation and leaching process, cutback strategy, etc. Main infrastructure aspects of the project are as follows: ?Dump area with 2400Mt capacity for waste and low grade material ?Mining equipment: 1 x electric shovel, 12 x 300t trucks, 1 x drill ?Primary crusher: 60? x 89? ?Three new power lines (144MW capacity) ?Grinding plant at 87kt/day nominal capacity (includes a 4.3km tunnel with a regenerative conveyor belt) ?Grinding plant: 1 SAG mill 40? x 25?, 2 ball mills ?Slurry pipeline (52 km from grinding to flotation plant) with five choke stations ?Flotation plant (rougher, cleaning, regrinding circuits and molybdenum flotation). The history of Los Bronces started in 1867 when it was discovered. In 1978 ENAMI (Government company) sold Los Bronces to Exxon for US$112M. The same year a snow avalanche destroyed San Francisco Flotation Plant. In 1979 the plant was rebuilt at 4.9kt/day and from 1979 to 2002 several plant expansions were made up to 54kt/day capacity. In 2002 Anglo acquired Los Bronces for US$1.3B. The 2002 resource and reserve statement showed reserves at 459Mt at 1.02%CuT and resources at 780Mt at 0.80%CuT. The 2007 statement shows reserves at 1,480Mt at 0.67%CuT and resources at 1,644Mt at 0.45%CuT. Defining the size of a plant expansion is the key challenge that any expansionary project faces. The scope of this paper is a general review of the project, describing all the mining techniques that were used to define the best options that maximise value. In this context, a range of plant capacities (from 58 to 230kt/day) combined with a range of mining capacities (from 83 to 166Mt/a) were evaluated in detail, defining for each option a mine plan, Capex and Opex, and cut-off grade strategy for flotation and leaching processes and the associated Net Present Value (NPV) that was used as the selection criteria. The Los Bronces mineral resources potential provides good growth opportunities for the mine beyond LBDP implementation, offering an exciting invitation to continue studying new initiatives that maximise the value of this deposit.

Jan 1, 2008

By O. J. Huber, P. D. Frost, H. A. Robinson

URANIUM is a (ß-stabilizing, eutectoid-forming element when alloyed with titanium. Udy and Boulger1 have reported that an alloy of 48.6 pet uranium in titanium retains ß-phase when quenched from the ß-region, while compositions of approximately 30 pet uranium transform to martensite during such quenching. Since the eutectoid reaction is rather sluggish, titanium-uranium alloys should be capable of being strengthened by the ß — a trans-

Jan 1, 1959

Preparation of MgO Nano-Particles with Magnesite

Sep 13, 2010

By Charles E. Lundin

Pressure-temperature-composition data were obtainedfor the Er-H system. Measurements werecar-ried out in the temperature range of 473° to 1223°K, the composition range of erbium to ErH,, and the pressure range of 10-5 to 760 Torr. Solubility relationships were established from these data throughout the system. Three solid-solution phases were delineated: metal solid solution, dihydride phase, and trihydride phase. The trihydride Phase decomposes at about 656°K and 1 atm pressure. The dihydride phase is stable to about 1023°K, but becomes more deficient in hydrogen above this temperature. The equilibrium decomposition pressure-temperature relationships in the two-phase regions, erbium solid solution plus dihydride and dihydride plus trihydride, were deter- The differential heats of reaction in these two regions are AH = - 52.6 * 0.3 and - 19.8 i 0.2 kcal per mole of Hz, respectively. The differential entropies of reaction are AS = - 35.2 * 0.3 and - 30.1 * 0.4 cal per mole HZ.deg, respectively. Relative partial molal and integral thermodynamic quuntities were calculated in the system to the dihydride phase. RARE earth metal-hydrogen systems have been the subject of general survey,1"4 and all have been found to form hydride phases. The heavy rare earths, of which erbium is a member, form dihydride and trihydride phases with different crystal structures, whereas the light rare earths form only a single-phase dihydride which expands without structure change, as hydrogen is added, to the trihydride composition. These materials are of interest primarily because of their theoretical properties, such as bonding, defect structure, and thermodynamic and electronic characteristics. Erbium has been studied in several previous investigations.5, 6 It was deemed desirable to more thoroughly and accurately define the system, both for the phase equilibria and the thermodynamic properties. I) EXPERIMENTAL PROCEDURE A Sieverts&apos; apparatus was employed to conduct the experimental measurements. Briefly, it consisted of a source of pure hydrogen, a precision gas-measuring buret, a heated reaction chamber, a mercury manometer, and two McLeod gages (a CVC, GM 100A and CVC, GM 110). Pure hydrogen was obtained by passing hydrogen through a heated Pd-Ag thimble. The hydrogen was analyzed and found to have only a trace of oxygen and nitrogen. A 100-ml precision gas buret graduated to 0.1-ml divisions was used to measure and admit hydrogen to the reaction chamber. The reaction unit consisted of a quartz tube surrounded by a nichrome-wound furnace. The furnace temperature was controlled by a recorder-controller to ±1°K. An independent measurement of the sample temperature in the quartz tube was made by means of a chromel-alumel thermocouple situated outside, but adjacent to, the quartz tube near the specimen. Pressure in the manometer range was measured to ±0.5 Torr and in the McLeod range (10-4 to 10 Torr) to ±3 pct. The hydrogen compositions in erbium were calculated in terms of hydrogen-to-erbium atomic ratio. These compositions were estimated to be ±0.01 H/Er. The erbium metal was obtained from the Lunex Co. in the form of sponge. The metal was nuclear grade with a purity of 99.9 pct +. The oxygen content was reported to be 340 ppm and the nitrogen not detectable. Metallographically the structure was almost free of second phase (<1 vol pct). A quantity of sponge was arc-melted for use as charge material. The solid material was compared with the sponge in the pressure-temperature-composition relationships. They were found to be identical. Therefore, sponge material was used henceforth, so that equilibrium could be attained more rapidly. The specimen size was about 0.2 grain for each loading of the reaction chamber. The procedure employed to obtain the pressure-temperature-composition data was to develop experimentally a family of isothermal curves of composition vs pressure. First, a specimen of erbium was wrapped in a tungsten foil capsule to prevent contact with the quartz tube. After loading the specimen, the system was evacuated to less than l0-6 Torr, flushed several times with high-purity hydrogen, and evacuated again ready for the start of the experiment. The furnace was then brought to the desired temperature. A measured amount of hydrogen was admitted into the chamber. Equilibrium was allowed to be attained, the pressure read, and the process then repeated many times until 1 atm of gas pressure was finally reached. Other isotherms were then developed in the same manner. The partial pressure plateaus were determined by another manner. In the solid solution-dihydride region a composition of approximately 1.0 H/Er was selected on the plateau. The temperature was varied throughout the range of interest. At each temperature level, equilibrium was achieved, the pressure read, and the next temperature attained. The temperature was cycled both up and down. In the dihydride-trihy-dride region, the plateaus were determined in the 473" to 651°K range only by heating to the desired temperature and not by both heating and cooling. The data were much more reproducible in this manner. Equilibrium required long periods of time. Specimens were initially hydrided to 2.8 H/Er, so that at the higher

Jan 1, 1969

By Michel Dagbert, Mohammed Harfi

"Abstract - The Draa Sfar polymetallic deposit, at about 16 km NW of Marrakech in Morocco, is a massive sulfide zone at the contact between an underlying volcanic and an overlying clastics sequence. The mineralized body is a flat lens with schistosity and "boudinage," tilted to the west and with a strong dip to the east. The lens extends over a strike length of about 2 km and from surface to a depth of about 1 km, with thickness varying from 1 m to almost 30 m. It has been intersected by about one hundred surface drill holes and, in its south part, by about thirty underground fan holes from two exploration levels at depths of 300 m and 400 m. On these two levels, the massive sulfide zone has been channel sampled over a cumulative length of about 0.7 km. Results from drill and channel samples are used to estimate the resources of the orebody according to several methods: sections, polygons around intercepts on a longitudinal plan, grids on the same longitudinal plan with various distance weighting methods including kriging and, finally, a 3D grid with the same range of interpolators. A comparison of the various estimates delineates the important factors in deriving resources for this type of deposit. Those factors are mostly geological and related to the interpretation of the geometry of the two limiting surfaces of the zone. For the 3D gridding, the authors have devised a new and original method that constrains the interpolation of blocks from samples to a geometry of limiting surfaces. The resulting model shows internal grade variations that parallel fluctuations of zone thickness and orientation without having to re-orientate the search window in each block. Résumé - Le gisement polymétallique de Draa Sfar, situé à environ 16 km au NW de Marrakech est un horizon de sulfure massif au contact d’une formation volcano-sédimentaire de base et d’une formation détritique sur-jacente. Le corps minéralisé se présente sous forme d’une méga-lentille aplatie, schistosée, boudinée et déversée vers l’ouest avec un fort pendage vers l’est s’étendant sur une longueur de 2 km et une profondeur de près de 1 km avec une épaisseur variant de moins d’un mètre à près de 30 m. Il a été reconnu par plus d’une centaine de sondages de surface et, dans sa partie sud, par une trentaine de trous souterrains en éventail à partir de deux niveaux à des profondeurs respectives de 300 m et 400 m. Sur ces mêmes niveaux, des traçages ont permis de rainurer le minerai sur une longueur cumulée de 0.7 km. Les données de sondage et de rainurage ont servi à estimer les ressources du gisement selon plusieurs méthodes : sections, polygones sur longitudinale, grille sur longitudinale avec différentes pondérations en fonction des distances incluant le krigeage et enfin grille tridimensionnelle avec le même éventail de pondérateurs. La comparaison des estimés obtenus permet de mettre en évidence les facteurs importants dans l’estimation des ressources de ce type de gisement. Ces facteurs sont essentiellement géologiques et relatifs à l’interprétation de la géométrie des limites des corps minéralisés. Pour l’estimation sur grille tridimensionnelle, on a mis au point une technique originale qui calque l’interpolation des blocs à partir des échantillons sur cette géométrie des surfaces de contact. Le modèle résultant montre des variations internes de teneurs qui épousent les fluctuations d’épaisseur et d’orientation de la zone sans qu’il soit nécessaire de ré-orienter les fenêtres de recherche dans chaque bloc."

Jan 1, 2002

Profiled here are the eight RMCMI 2000 Scholarship Award winners. Six of the eight attended the 96&apos;&apos; Regular Meeting and convention at the Sheraton Tamarron Resort in Durango, Colorado in late Tune. Each spoke during the Scholarship Awards Monday luncheon and shared their goals with attendees. In addition to receiving a 52,000 tuition credit, thanks to the Patrons of the Institute annual funding of scholarships, each received recognition at the luncheon with a brass plaque signifying this honor. The winners arc guests of the Institute Sunday through Tuesday noon and have an outstanding opportunity to meet many in the coat industry who could be potential employers. The state vice presidents host the winners and pay for their travel and hotel expenses. This is a continuing scholarship and may be renewed for tuition credit again in the senior year it the winner is a full time student and is recommended by the dean of the college or university. A resident from each of the eight member RMCMI states is selected by the Scholarship committee from Board approved institutions. Criteria for these annual awards is that the recipient (1) is a full time sophomore student who will use the tuition credit the junior year. (2) Be both a U. S. citizen and a legal resident of the member state. (3) Maintain good academic standing, be pursuing a degree in a mining related field and have an expressed interest in western coal as a possible career path. Contributions to this worthwhile project are tax deductible to each individual RMCMI member or his company. Through donations of $100 or more to the Patrons of the Institute, each Patron receives a plaque and a year bar for each additional year contributions arc made. There may be directed to RMCMI Patrons, 3000 Youngfield Street, #324, Lakewood, CO 50215. [ ]ARIZONA WINNER David L. Vatterrodt University of Arizona The son of Charlene and Larry Vatterrodt, David graduated from Marana High School, Tucson, Arizona where he attained a 3.6 GPA. In his second year at the University of Arizona he has a 3.4 GPA and is pursuing a Bachelor of Science in Mining Engineering. He is a member of SME and enjoys playing tennis and riding his motorcycle. He is the recipient of a $1,000 Tradition of Excellence scholarship. David volunteers every Saturday morning during the academic year at the U of A. San Xavier Mining Laboratory. His tasks there include work area inspections, jack-leg drilling, scaling, roof bolting, operating an LHD and overshot mocker, track laying and other general maintenance. COLORADO WINNER [ ]Jonathan B. Casten Colorado School of Mine. Graduating with high honors and a 3.99 GPA from Windsor High School, Colorado, Jon is well prepared for the rigors of academia. In high school he was on the Dean&apos;s list, Salutorian of the Senior Class, member of National Honor Society, Colorado Boys State delegate and lettered in varsity golf.At Mines, Jon belongs to SME and Work Study and maintains a 3.75 GPA. He enjoys golf, hiking and weight lifting. His parents are Katherine and Fred Casten of indsor. Jon has chosen Mining Engineering as a career as he plans to improve the nation&apos;s efficiency of extracting natural resources.

Jan 1, 2000

By HASAN SERKAN GOKCEN, SERKAN CAYIRLI

The purpose of this study was to investigate the dry grindability of calcite powders in a vertically and horizontally orientable laboratory batch type stirred mill. The experimental results were evaluated using stress intensity analysis. The performance was also compared in terms of mill orientation. The results showed that the d50 values decreased with increasing stress energy down to a certain point and then increased for both milling orientations. Even though the optimum stress energies for both vertical and horizontal orientations were in the range of 1*10−3 to 5*10−3 Nm at 750 and 1500 kJ/kg energy consumption, the product size was finer for the horizontal orientation at the same stress energy value. Additionally, to the best of the authors’ knowledge, this is the first study to compare mill orientation (vertical vs. horizontal) for the same mill and under the same test conditions.

Apr 21, 2021

By S. L. Lopata, E. B. Kula

A variation of yield and tensile strength with direction has been noted in heat-treated 4340 steel which had been warn-worked by rolling in the austenitic condition prior to quenching. Measurements by X-rays showed a preferred orientation of martensite crystals. Various ideal preferred orientations of martensite were calculated by assuming a preferred orientation for austenite and transforming this to martensite by the Kurdjumov -Sachs and Nishiyama relationships. Comparison with the measured preferred orientation showed that the ideal rolling texture for austenite in 4340 steel could be expressed as a (112) [111] texture with a component of (110) [112]. No evidence was found for any fiber axis in the rolling direction, or fop- a (123) [412] texture. The observed martensite pole figures can be adequately accounted for by these ideal austenite textures and by the Kurdjumou-Sachs or Nishiyama transformation relationships between austenite and martensite. ALTHOUGH preferred orientations are found in cold-rolled steel sheet and in many nonferrous metals, they are not generally encountered in wrought, heat-treated high-strength steels, since such steels are generally not cold worked sufficiently to develop a strong texture, and any texture that is present is removed during heat treatment by the phase transformations taking place. This report gives details on a preferred orientation found in warm-rolled and hardened 4340 steel. In a recent study, a special combination heat-treating and working technique was used in which 4340 steel was deformed in the austenitic condition, and before re crystallization of the austenite could occur, quenched to form martensite.&apos; Since the austenite was unrecrystallized, it was cold worked and hence could have contained a preferred orientation which could be transmitted to the martensite on quenching, and this in turn could be manifested as a directionality of mechanical properties. Such a directionality of properties was found as a result of working, and this prompted an X-ray study of the preferred orientation. Literature Survey— Rolling Texture in Face-Cen-tered-Cubic Austenite—M a preferred orientation is found in a rolled and hardened steel, it is first appropriate to consider what texture existed in the austenite as a result of the rolling but prior to the transformation to martensite. The changes taking place as a result of the austenite-martensite transformation are then considered. In view of the instability of austenite in 4340 steel at low temperatures, no direct determination of the austenite texture was made. However, an estimate of the texture for austenite in 4340 steel may be made by considering the textures found for other face-centered-cubic metals. Barrett&apos; has reviewed the rolling textures for many materials. The most common orientation in face-centered-cubic metals has the (110) planes parallel to the rolling plane and the [112] directions parallel to the rolling direction, or (110) [112]. Other orientations found are (112) [111], as well as (100) [001], (110) [001], and others. Beck and his co-workers, using quantitative pole figures, report that (123) [121],3 later corrected to (123) [412],4 better describes the ideal orientation. smallman5 reported that the ideal preferred orientation for high-purity face-centered-cubic metals is (123) [121], but that there is a transition to (110) [112] as solid solution elements are added. The latter texture tends to occur more readily at lower temperatures. This transition between the two textures was explained by differences in the slip characteristics with concentration or temperature. More recently, Jones and Fell6 concluded that the (123) [412] texture for face-centered-cubic metals could equally well be represented by a mixture of (110) [112] and (112) [111] textures, and hence it had no physical reality. From the above results it can be seen that there is no agreement on the "ideal" texture for fcc metals and, hence, no firm basis for assuming a texture for austenite in 4340 steel. Therefore, the orientations (110) [112], (123) [412], and (112) [111] have been considered in the following.* *The (123) [4121 is identical to the (123) [121] rotated 90 deg. Orientation Relationship between Austenite and Martensite—When martensite forms from austenite, certain crystallographic planes of the martensite are parallel to planes in the austenite. This orientation relationship was first determined by Kurdjumov and

Jan 1, 1960

By J. J. Jonas, G. Gagnon

SHG zinc was extruded in the temperature range 110" to 350°C and the strain rate range 0.05 to 5 sec-1 The strain rate/flow stress/temperature results were analyzed using a power sinh stress relationship. When temperature changes due to the heat of deformation and to heat losses are neglected, the exponent of the sinh function of the stress is 5.6, and the apparent activation energy of deformation is 28 kcal per mole. When these changes are taken into account, the exponent decreases to 4.7 and the activation energy to 23 + 2 kcal per mole. The corrected stress exponent and activation energy are in very good agreement with published values obtained from creep experiments, and suggest that the hot extrusion of zinc is controlled by a mechanism involving self-diffusion. When the extrusion and creep data are compared using a Zener-Hollomon parameter and either a sinh or an exponential stress term, an appreciable offset is observed, which may be due to the difference in impurity content. For a given set of extrusion conditions the ram speed, maximum pressure, and initial temperature can also be correlated using a Zener-Hollomon parameter and a sinh pressure term. THE deformation of metals at temperatures over about one-half the absolute melting temperature has been extensively studied at creep strain rates. By contrast, relatively little work has been carried out on the behavior of metals at hot working strain rates. Most of the latter investigations have been performed using simulative methods, such as hot torsion and hot compression, in which the friction conditions and temperature rise during deformation may differ appreciably from those existing under industrial conditions. Recently, however, Wong and Jonas1 used a scaled-down industrial process to determine the stress and temperature dependence of the strain rate during the extrusion of aluminum. In such tests, the effects of friction and adiabatic heating are closer to those produced in industrial operations. Also, with regard to the testing of materials of limited ductility such as zinc, hot compression and hot torsion do not permit the attainment of true strains as large as the deformations usually applied commercially. The present study was undertaken to investigate the extrusion behavior of Special High Grade (SHG) zinc. The detailed objectives were: 1) to establish the stress and temperature dependence of the strain rate with and without a consideration of adiabatic heating, 2) to study the pressure and temperature dependence of the ram speed, and 3) to investigate the microstruc- tural changes occurring during the deformation. The last aspect of the investigation will be covered in a separate paper. The treatment described below differs from that of Wong and Jonas in that the adiabatic temperature rise during deformation is taken into account, and the calculation of the mean equivalent strain rate is based on the redundant as well as on the homogeneous work. EXPERIMENTAL PROCEDURE Rods from two shipments of continuously cast SHG zinc* were used in the investigation. The composition *Supplied by courtesy of Cominco Ltd. range of the impurities present, as given by the supplier, was: Pb: 0.0013 to 0.0023 pct, Fe: 0.001 pct max Cd: 0.0001 to 0.0006 pct, Cu: 0.0002 to 0.0005 pct, Ti: 0.0001 pct max; thus, by balance, zinc valued from 99.9963 to 99.9966 pct. The as-received rods were machined into billets having a nominal diameter of 1.56 in. and a nominal length of 1½ in.; longer billets up to 4 in. in length, were also used to investigate special aspects. The as-machined rods were annealed at 400°C for 24 hr and slowly cooled. This treatment produced a columnar grain structure, with a grain size of about $ by 2½ cm which was appreciably larger than the as-cast one. A 150-ton, direct extrusion, vertical press was used. Ram displacement and force were recorded continuously against time. A constant flow control valve permitted the maintenance of a range of preselected ram speeds up to in. per sec. The selected speed was held constant, irrespective of the required force, as long as the load developed was below the maximum available. Strain gages were used to determine the force; the gages were calibrated before and after each testing period with a 200,000-lb capacity load cell. Further details of the experimental equipment can be found in Ref. 2. The billets were preheated for 90 min in the extrusion container, which was well insulated so as to minimize temperature gradients. This period was sufficient for the billet to reach a uniform temperature at all temperatures between 110" and 350°C. A square-shoulder die having a 0.290-in. diam central hole was used. The extrusion ratio was 30 to 1. This is equivalent to a reduction in area of 96.7 pct, an elongation of 2900 pct, and a true strain of 3.4. The ram speed was varied over two orders of magnitude from 0.0027 to 0.26 in. per sec. The ram was water-cooled during most of the tests, although some experiments were conducted with a preheated, uncooled ram. All extrusions were run without lubricant, which resulted in conditions of sticking friction. EXPERIMENTAL RESULTS Stress Dependence of the Strain Rate Neglecting Adiabatic Heating. The maximum force required to extrude is given in Table 1 for each of the five initial

Jan 1, 1970