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By Alden Greninger

MANY recent contributions in the field of theoretical metallography have been concerned with crystallographic definitions or descriptions of various phenomena. The lattice orientation of the crystal being studied must be known before such definitions can be made. Practically all the metallic crystals used do not have crystal faces-other than the unknown "plane of polish"; hence resort must be had to other means of determin-ing orientations. Some use has been made of etch-figures, slip bands, optical properties, etc., for this purpose; but for. accurate results, and because of the fewer restrictions to their use, the various X-ray methods have been the most satisfactory.1 The methods that, have been used may be divided into two general classes: (1) oscillation methods, and (2) transmission Laue methods-2

Jan 1, 1934

By Colin G. Fink, Leslie G. Jenness

Tantalum and columbium occur together in tantalite and columbite ores, which may be considered as ferrotantalate (FeTaz06), with part of the iron and tantalum replaced by manganese and columbium respectively, the general formula, therefore,becoming (Pe, Mn)O.(Ta, Cb)2Os. The ratio of tantalum to columbium is not fixed; the amount of tantalum may vary from one-third to three times that of columbium. Minerals having a high content of tantalum are called tantalite, while those possessing larger amounts of columbium are classified as columbite ores. These minerals are found in pegmatites and often occur in veins associated with cassiterite and wolframite, and may contain small amounts of tin, tungsten, titanium and si1ica. l Methods of Extraction Several methods have been proposed for the extraction of tantalum and columbium from their ores, among them being: 1. Fusion with Potassium or Sodium Bisu1fate.—The finely ground ore is fused with potassium bisulfate, after which the mass is boiled with water and the fusion repeated several times. The residue finally resulting is digested with ammonium sulfide to remove traces of tin and tungsten, boiled with hydrochloric acid, filtered and washed. These oxides are then dissolved in hydrofluoric acid, the silica evolved as silicon tetra-fluoride and the hydrofluoric acid solution used for the potassium double fluoride separation of tantalum. 2. Fusion with Sodium Carbonate and Sodium Nitrate.2—This fusion renders the tantalum and columbium soluble, and they are extracted

Jan 1, 1931

By Arthur H. Wilson

INTRODUCTION The stratified deposits of the coal measures are strongly laminated and exhibit a high degree of anisotropy. The stronger rocks in the sequence possess joints and shear planes, the coal itself has a closely spaced cleat pattern, and the softer rocks are capable of flowage. To calculate the general distribution of stress in such a medium by analytical means based on the theories of elasticity is difficult, and has not yet been satisfactorily achieved. Nevertheless, some estimate is required to aid the design of supporting pillars and permit the correct siting of main roadways. This is important when laying out districts for longwall extraction, particularly if the results of previous experience are not available in the area to be exploited. Although elastic stress analyses, including finite element analysis, may not be very appropriate, the basic equilibrium conditions will apply. These, combined with logical deductions based on observed fact, can be used to give appropriate solutions which experience has shown to be capable of giving acceptable results in the design of pillars associated with longwall workings. Constancy of cover load is one of the fundamental equilibrium conditions. When mining below ground, the cover is not removed, therefore the average vertical load after mining must equal the initial cover load. If mining produces a local decrease in load in any particular area, it must be balanced by an equivalent increase in load nearby. Bending moments in the strata above are capable of compensating for the turning moments which this redistribution of load may produce, and the existence of a "rear abutment", much discussed between 1950 and 1960, is not an essential equilibrium requirement. If the distribution of vertical stress is plotted three-dimensionally, then the load on any small element of area 6S will be o.6S, where o is the average stress. This also represents the volume of the "stress envelope" which lies above 6s. By making the individual areas very small and summing together, it is possible to show that the total load on any particular area can be found by calculating the volume of the stress distribution envelope which lies above it. A similar consideration applies to the stress distribution in a two-dimensional situation. If the stress distribution curve is drawn, then the area below any portion will represent the load per unit depth of section. For example, Figure 1 represents the possible stress distribution across a caved waste and associated ribside. If AW is the load deficiency [ ] These loads must balance, therefore area AW = AS, and if one can be deduced, the other will then be known. Attempts have been made to measure stress distributions in the ribside and in the waste. Stress meters in soft rocks such as the coal measures have not proved very effective. Those based on the measurement of strain have experienced difficulty in strata capable of flowage, high modulus stress meters suffer from cross sensitivity, and overcoming to obtain absolute stress is almost impossible. Load measuring instruments left in the waste have also proved largely ineffective, mainly as a result of the difficulties of protecting the leads in a caving environment. Certain logical deductions, however, can be made about the conditions in the waste. CONDITIONS IN THE WASTE Over the area of the waste the surface trough which develops is remarkably consistent, despite the geological variations which occur from coalfield to coalfield. In Britain, an accuracy of 210% is claimed for subsidence prediction based on width of extraction and depth of cover (National Coal Board, 1975). The subsidence in the USA is more variable (Adamek and Jeran, 1981), particularly with respect to the point of inflexion, but the same general pattern occurs. At the shallower depths the somewhat harder roof strata involved in the caving in the USA may suffer less compaction, giving reduced values of subsidence. Subsidence at intermediate horizons below the surface

Jan 1, 1982

By C. F. Kaiser, T. J. Roberts, I. A. Thomson

The Broken Hill Pty. Co. Ltd. grate-kiln pelletizing plant located at Whyalla, South Australia, produced a total of 250,000 tons of fluxed pellets during 1970. More than 180,000 tons were exported to Japan, while the remainder was used in B.H.P. Co. blast furnaces. The pellet plant treats high grade hematite ore fines and has a nominal capacity of 1.5 million tpy. The induration equipment includes a grate 12-ft 2-in. wide by 164-ft 1-in. long, a kiln 18-ft 6-in. diam by 118-ft 8-in. long, and a rotary cooler 50-ft mean diam by 7 ft wide. Operating problems encountered in the production of fluxed pellets are detailed. The most significant aspect of the trial was the increased production, from about 5100 tpd up to a maximum of 7100, brought about by the addition of artificial magnetite to the plant feed. Laboratory evaluation of fluxed pellets showed that pellets having a basicity ratio (CaO to SiO2) in excess of 1.2 have excellent physical qualities. Reducibility and compressive strength after reduction were both higher for these fluxed pellets than for normal acid pellets. Although it was not possible to publish blast furnace operating data, blast furnace trials on fluxed pellets indicated that production was higher and dust losses substantially lower, compared with similar operations on acid pellets.

Jan 1, 1973

By B. B. Sandiford

It has been known for many years that the efficiency of a water flood can be improved by lowering the water-oil mobility ratio in the system. Such a change leads to better sweep efficiency and also to more efficient oil displacement in the swept zone. Data from our laboratory water-flood tests of both small cores and long sand packs are presented which show that water mobility can be reduced and oil recovery increased by the addition of certain polymer solutions to flood water. The reduction in mobility, in many cases, is greater than would be expected from conventional viscosity measurements. These solutions, however, do not cause significant reductions in oil mobility. The over-all effect of these mobility changes is increased waterflood oil recovery. Encouraged by results of our laboratory work, we expanded our study to include pilot field tests of floods with such solutions. One such test, made in the West Cat Canyon field, Santa Barbara County, Calif., is described in detail in this paper. Three other field tests are also discussed. INTRODUCTION Oil production from most reservoirs following primary depletion and/or water flooding is often less than 50 per cent of the original oil in place. Heavy oil reservoirs seldom yield over 15 per cent of their original oil. With new reservoirs becoming harder to find, the improvement of oil recovery efficiency is one of our very important problems. We describe here some of our attempts to increase the efficiency of oil displacement by adding a water-soluble polymer, partially hydrolyzed polyacrylamide, to flood water. This technique will be termed "polymer solution flooding". The concept of using high-viscosity water to increase the efficiency of water flooding is not new. In 1944 Detling (Shell Development Co.) obtained a patent covering the use of several additives for viscous water flooding.' His objective was to improve water-oil mobility ratios by increasing the viscosity of the flood water. Other patents2-27 have been granted covering specific water-SO~LIble polymers or specific conditions of viscous water flooding. Barnes'" described his laboratory model study of the injection of a viscous water slug into a reservoir which had been partially invaded by bottom water. He concluded that, for this type of reservoir, "the cost of viscous water should not exceed a few cents per barrel for viscous water slug injection to be economically feasible" Our studies have led us to a somewhat different conclusion in a number of cases where hydrolyzed polyacrylamide solutions have been injected into reservoir models or actual reservoirs. Possible reasons for this difference are discussed in this paper. Our studies have shown that polymer solutions may lead to an increase in oil recovery over that from an ordinary water flood by (1) improving sweep efficiency, (2) improving microscopic displacement efficiency, or (3) a combination of these mechanisms. In the work of Barnes, only the benefit of improved sweep efficiency was considered. Also, our work has shown that there are marked differences in the effectiveness of different water-soluble polymers as flood water additives. Partially hydrolyzed polyacrylamide is better than many other water-soluble polymers we have tested because, even in very low concentrations, it can lead to increased oil recovery. This is an important advantage when either a dilute polymer solution is injected continuously or a relatively concentrated slug is injected followed by water. In the latter case! portions of the slug become diluted and function in the formation as very dilute solutions. As dilution takes place the effective slug size will increase which, in turn, will reduce the cost per barrel of the effective flooding medium. The reason that partially hydrolyzed polyacrylamide solutions are more efficient at low concentrations than certain other polymer solutions of equivalent viscosity (when measured in conventional viscometers) is not fully understood. We do know that the shapes and sizes of macro-molecules dissolved or suspended in liquids influence the flow properties of their solutions or suspensions. Solutions of partially hydrolyzed polyacrylamide cause greater reductions in water mobility than would be expected from conventional viscosity measurements. LABORATORY STUDIES Laboratory water floods were run in linear and radial systems with different water-soluble polymers and under varying conditions of flow. including reservoir conditions of temperature, pressure and fluid composition. Some of these runs are considered in this section. OIL DISPLACEMENT IN LINEAR MODELS In this group of runs the sweep efficiency approached 100 per cent because the linear sand packs used were as nearly uniform as possible. Results reflect primarily the micro-scopic displacement efficiencies. The laboratory models were unconsolidat-ed sand packs the lengths of which varied from about 4 in, to 40 ft. Further information on the flow models used is listed in Table 1. Using conventional procedures, water floods were run on sand packs containing either refined or crude oil at restored state. Frequently, a repeat run, similar to the first, was made as a check. Then a third run was made on the restored-state model using either polymer solution or a combination of polymer solution (slug) and water. Details of these runs are also reported in Table 1. In Figs. 1 and 2 results of two different groups of runs are shown in which the oil used was a 62-cp refined oil and the flooding medium

Jan 1, 1965

By H. I. Aaronson, C. Laird

Although the past results of X-ray experiments indicate that the broad faces of 0' plates are coherent with their matrix, dislocations lying in arrays have frequently been observed at these boundaries by transmission electron microscopy. Critical experiments employing the latter technique have been carried out in order to determine the origin of these dislocations. It is concluded that 8' plates are essentially coherent with the matrix at their broad faces throughout the aging temperature/time envelope studied. Virtually all of the dislocation arrays observed are deduced to have been formed by plastic deformation accompanying transformation. The proportion of dislocations arising from convexity of the plates is shown to be negligible by comparison with that from plastic deformation. At the higher aging temperatures, a[001] dislocations appeared in moderate numbers. These dislocations were traced directly, however, to the ledgewise dissolution of 0' occasioned by the formation nearby of 0 crystals. On the other hand, since there is a parametric difference normal to the broad faces of the ?' plates, mismatch dislocations do form at their edges. A previous conclusion that these dislocations have Burgers vectors of type a[001] was confirmed directly. The edges of 0' plates were observed to develop octagonal shapes when growing, but circular shapes during dissolution. 1 HIS paper presents the results of an investigation of the interfacial structures of plates of the transitional phase, 8', formed in an A1-4 pct Cu alloy. In a companion paper, Part 11, the effects of these structures upon the migration kinetics of a:?f boundaries are reported. This work is pa.rt of a general program designed to establish the basis of precipitate morphology. The present authors in Al-Ag,1 and whitton2 previously in U-C alloys, have used transmission electron microscopy to examine directly the vander Merwe3-6 networks of dislocations anticipated7 to compensate the small amount of lattice misfit normally founda at the broad faces of Widmanstatten plates. Since the broad faces of 0' plates are considered to be perfectly coherent with the corresponding habit planes in the a matrix,' no dislocations should be present at these faces. Many reports have been published, however, giving evidence to the contrary.10-18 The primary objective of this investigation was therefore to ascertain the nature of these dislocation structures. An attempt to do this is described in the first three sections of this paper. Inspection of the matching of the a and 8 ' lattices at the orientations of the 0:0' boundary corresponding to the edges of 0' plates raises the possibility that these edges may be made up of rather closely spaced edge- type misfit dislocations oriented so as to be sessile with respect to the lengthening or shortening of the plates. Since this structure should severely inhibit migration of the plate edges (Ref. 7, Part II), a situation not originally anticipated,' an experimental determination of the interfacial structure of the edges of 8' plates was clearly in order, and is reported in Section III. Those aspects of the experimental procedure applicable to both Parts I and I1 are presented in the next section. Specific procedures applicable to individual aspects of each investigation, and also the relevant surveys of the literature, are then individually reported in the appropriate sections. I) GENERAL EXPERIMENTAL PROCEDURE The material used in both parts of these studies was the same as that of a previous investigation:" strips of A1-3.93 pct Cu, 0.009 in. thick, prepared as before, solution-annealed at 548°C for 6 hr, and quenched. Details of subsequent aging, and in some cases deformation treatments, are given in the Experimental Procedure sections of the individual parts of both papers. Specimens of the heat-treated strips were electro-thinned as beforeLg and examined in a Philips EM 200 microscope equipped with a goniometer stage. A commercial hot stage, of the grid-heater type and capable of * 30-deg tilt about one axis in the plane of the specimen, was also used for kinetic studies. The usual precaution of calibrating for the additional heat supplied by the electron beam was taken.19 A 16-mm cine cam-I era mounted outside the viewing window was frequently used to record the transformations. Conventional selected-area diffraction and dark-field viewing techniques were used to identify the precipitates in the foils. Normal bright-field images corresponding to two-beam diffracting conditions or dark-field images were employed to characterize the dislocations observed at the interfaces of the precipitates. The application of these techniques to the study of an interphase boundary, and the interpretation of the images,20'21 has been fully described in a previous paper.'

Jan 1, 1969

By Francis R. Conley, John A. Sievert, John N. Dew

A brief review is presented of the past performance of a number of large, thin, highly permeable reservoirs with low dips in the Bolivar Coastal fields of Venezuela. The performance of these reservoirs indicates that the fluids are segregated vertically within the sand section by gravity. With this assumption, equations are developed which describe the performance under pressure maintenance operations. Methods of solving these equations and results of simple example calculations are presented. Example calculations indicate that under pressure maintenance conditions injected gas tends to {tow preferentially along the top of the sands and that encroaching water has a tendency to flow preferentially along the bottom. The expected performance of segregated fluids is discussed and compared with that of fluids which are uniformly distributed in any sand section. INTRODUCTION The field performance of a number of reservoirs described herein indicates that the fluids are segregated vertically within the sand section by the force of gravity. Thus, it was felt that any method used to predict the future performance of these reservoirs should consider the effects of segregation in the sand sections. A study of the available information on some of the reservoirs suggests that increased recoveries may be expected if the reservoir pressure is maintained by either crestal gas injection or flank water injection. To predict future performance of reservoirs under pressure maintenance operations, a method of analysis was needed which would account for segregation of fluids in the sand sections. Several methods of analysis have been developed to take into account the segregation of fluids in the reservoir as a whole1,3 To our knowledge no method considers segregation of the fluids within sand sections in the manner indicated by the past performance of several reservoirs in the Mara-caibo Basin. This paper outlines part of the work done in studying some of these reservoirs and contains a description of their performance characteristics. The analysis presented is restricted to pressure maintenance conditions, since space limitations prevent a full discus- sion of the development of the mathematical relations and the various methods of solving them. Only a sketch of the development of the mathematical relations is given. The various methods of solving these relations are pointed out, but the actual determination of solutions to various problems are omitted except for one example. It is felt that these results may aid in the study of reservoirs outside the Maracaibo Basin. Some concepts on which the present analysis is based are outlined by D. N. Dietz. However, the analysis presented herein includes several factors not considered by Dietz: (1) variations in permeability and in the cross section, (2) various shapes of the cross section, and (3) the production of fluids. Also, the mathematical development presented by Dietz differs considerably from our corresponding analysis. RESERVOIR CHARACTERISTICS The reservoirs under consideration, large and thin, with low dip and high permeability, are large to the extent that they contain from 0.5 to over four billion bbl of oil initially in place. The section thicknesses vary from 100 to 400 ft and the lengths from 10,000 to 40,000 ft. Thus, a length-wise cross section of the producing formation appears to be long and thin. The dip angles vary from 0 to 6 degrees and the average permeabilities vary from 0.5 to over three darcies. The reservoirs contain from 20 to 50 per cent shale inter-laminated with the productive sands. Most shale breaks within the major sands do not correlate from one well to the next, and correlation is often difficult, even between wells drilled from the same location. However, it is often possible to correlate the shale breaks between major sands for some distance. Herein we are concerned with the performance of reservoirs containing oil of gravities over 20" API. Past reservoir performance indicates good pressure communication and, in cases where pressure sinks have developed, large amounts of fluid migration have occurred. Few of the reservoirs have had initial gas caps, but also, few have been found to be highly under-saturated. Due to gravity segregation, secondary gas caps usually form before the pressure has been reduced more than 25 per cent of its initial value. The effect of gravity has not only been apparent on a reservoir-wide basis, but has also caused segregation of the reservoir fluids in productive sections. Proof of this is found from the results of selective well tests, workovers, and electric and various other types of logs. Evidence that

By G. E. Perry, J. F. Bruskotter, D. G. Russell, J. H. Goodrich

The depletion performance of gas wells has been investigated by mathematical simulation techniques. The gas well model which was studied consisted of a single well located in the center of a bounded, cylindrical, homogeneous reservoir. Dependency of gas compressibility and viscosity on pressure was considered in studies of well performance at both constant mass flow rate and constant flowing pressure conditions. To carry out the investigation, the nonlinear, second-order, partial differential equation which describes Darcy flow of a nonideal gas through porous media was solved numerically. Some of the previous investigations of gas well performance have been of limited general use, because assumptions were introduced to simplify either the gas properties or the basic differential equation. Other studies have been rigorous in these respects but have presented a very limited set of calculated results. The present study was attempted to present a rigorous theoretical model and sufficient numerical results to permit meaningful conclusions to be drawn. It was found that all terms must be retained in the partial differential equation to make accurate predictions. The neglect of higher-order terms, e.g., terms of the order of the "gradient squared", leads to serious material balance errors at large times and to conservative estimates of gas well performance. The higher the gas flow rate and/or the lower the permeability-thickness product of the formation, the more pronounced are these deviations. For example, in a well draining 640 acres in a 25-md-ft formation (8,120 MMcf gas in place) at a constant rate of 993 Mcf/D, the rigorous solution predicts a bottom-hole pressure decline from 4,000 to 1,000 psia in 8.7 years. If higher-order terms are neglected in the differential equation, this decline in pressure is predicted to occur in 5.3 years. With the results of the numerical solution of the differential equation as a basis, simple, easy-to-use approximations for predicting gas well performance for Darcy flow conditions have been developed. These simple approximations are based on the familiar equations for flow of a single, slightly compressible fluid. The approximate methods possess a high degree of accuracy and enable the prediction of long-term gas well performance to be made quickly and accurately without the use of a digital computer. Both transient and stable flow period approximations were developed. INTRODUCTION In recent years income from the sale of natural gas and associated products has represented an ever-incre as ing fraction of the industry's total revenue from operations. To meet the surge in demand for natural gas, the industry has depended heavily upon established reserves and has actively pursued development of new reserves. The search has progressively led to reservoirs which yesterday were too tight and/or deep to yield the desired return on invested capital. More than ever before, evaluation accuracy is now required to forecast the criteria upon which engineering recommendations and management decisions are based. Considerable effort has been expended by both research and operations personnel on the development and application of methods for analyzing and predicting the performance of gas wells. Fundamentally, the problem is the familiar one of extracting data during the drilling, testing and early production life of a well and applying these data within an accurate simulation model to predict long-term behavior. During the past 30 or more years a voluminous literature dealing specifically with gas field problems has been generated. A recent book' lists a comprehensive bibliography of published material through 1959. Over 1,200 references are cited. Since then 39 additional articles on natural gas technology have been published in Transactions volumes of the Society of Petroleum Engineers of AIME. Most existing theory for predicting gas well performance requires that one or more idealizations (e.g., steady-state flow, ideal gas of constant viscosity, small and constant compressibility and constant-viscosity fluid) be applied. Although existing theory may apply directly or be adapted by various artifices to describe specific gas well and reservoir behavior, no widely applicable method is available, and existing methods appear to be subject to appreciable error unless better limits of applicability are defined. The objectives of this paper are (1) to present numerical solutions to the partial differential equation describing gas flow under conditions of general interest in gas well performance prediction work, (2) to present solutions which possess a high order of accuracy for both transient and stabilized flow periods of a well producing at constant rate or constant pressure, and (3) to develop and present simplified relationships which can be used as high-order approximations to the exact numerical results for fast and accurate predictions of gas well performance at the operating level. Combined, these objectives are designed gen-

Jan 1, 1967

By R. G. Agarwal, Ramey Jr. H. J., Al-Hussainy R.

Although it has long been realized that gas recovery from a water-drive gas reservoir may be poor because of high residual saturations under water drive, it appears that only limited infomlation on the subject has been available until recently. This study was performed to show the qiiantitative potential importance of water influx. Results indicate that gas recovery may be very low in some cases: perhaps as low as 45 per cent of the initial gas in place. Gas recovery under water drive appear to depend in an important was on: (I) the prodirction rate and manner of production; (2) the residual gas saturation; (3) aquifer propertie.); and (4) the volumetric displacement effciency of water invading the gas reservoir. The manner of estimating water-drive gas reservoir recovery can vary considerably. Examples are: the steady-state tnethorl. the Hurst modified steady-state method, and various unsteady-state methods such ac. those of van Ever-dingen-Hurst, Hurst, and Carter-Tracy. The Carter-Tracy water influx expression was used in this study. In certain cases, it appears that gas recovery can be increased significantly by controlling the production rate and manner of production. For this reason, the potential importance of water influx in particular gas reservoirs should he investigated early to permit adequtrtr planning lo optirtize the pay reserves. INTRODUCTION In recent years, the economic importance of natural gas production has become increasingly apparent. This has been evidenced by more intensive exploration efforts aimed at gas production, and exploitation of both deep, as well as low-permeability gas reservoirs. Technical developments such as deep-penetration fracturing have made development of such formations economically feasible. Unfortunately, water influx has forced abandonment of a number of gas reservoirs at extraordinarily high pressures. Although reservoir engineering methods for estimating water influx have long been available, it appears that application of these methods to the water-drive gas reservoir has been sporadic.'a Available methods for estimating water influx which can be applied to the water-drive gas reservoir problem include the steady-state method,1 the Hurst modified steady-state method and various unsteady-state methods such as those of van Everdingen-Hurst. Hurst, and Carter-Tracy. Interesting applications of these solu- tions to gas reservoir and the aquifer gas-storage problems have appeared recently.3,12,14 The experimental study of residual gas saturations under water drive by Geffen et al. in 1952 indicated that residual gas saturations could be extremely high. A value of 35 per cent of pore volume is often used in field practice when specific information is not available. The study of Geffen et al. showed that residual gas saturation might be much higher in some cases. Naar and Henderson concluded that the residual non-wetting phase saturation under imbibition should be about half of the initial non-wetting phase saturation. The Naar and Henderson result that residual gas saturation under water influx should be about half the original gas saturation is recommended as an estimate if laboratory measurements are not available. Thus, it is clear that a considerable portion of the initial gas in place might be trapped in a water-drive gas reservoir as residual gas at high pressure. A full water-drive would result in loss of residual gas trapped at initial reser.voir pressure. Consideration of transient aquifer behavior leads to the conclusion that high-rate production of water-drive gas reservoirs could result in improved gas recovery by reduction of the abandonment pressure. However, there appears to be little quantitative information on this possibility. One of the few advantages of water-drive gas production appears to be improved deliverability through water-drive support of the reservoir pressure. There may also be an advantage in higher condensate recovery caused by pressure maintenance for gas-condensate water-drive reservoirs. In view of the preceding, this study was made to assess the potential importance of water-drive in gas reservoir engineering. The Carter-Tracy approximate water-influx expression was used because this equation offers some advantages in hand-calculation which do not appear to have been generally recognized.' However, calculations were performed in the main with a high-speed digital computer to permit evaluation of the effect of water-drive under a large variety of conditions. CALCULATION METHOD Water-drive gas reservoir performance can be estimated in a manner completely analogous to oil reservoir calculations: a materials balance is written for the reservoir, and a water influx equation is written for the aquifer. Siniltaneous solution provides the cun~ulative water influx and the reservoir pressure. When reservoir performance data (gas produced and reservoir pressures) are available, it is usually possible to match performance data to determine the initial gas in place and the water influx parameters —

Jan 1, 1966

By Fred B. Brost

In 1976, a decision was made to install a conveying system to transport ore 10.3 km (6.4 miles) from the new Eisenhower mine to Twin Buttes. The system, supplied and installed by Cable Belt Ltd., of England, represents a radical departure from conventional conveyor systems. The driving tension is applied through two endless wire ropes while the belt acts only as the carrying medium. Features of the system are a single 2240-kW (3000-hp) drive and a 60° angle bend. Construction was completed in two years and full production was attained alter several mouths operation.

Jan 12, 1979

By H. Conrad, V. V. Damiano, G. J. London

The slip mode activated during the c axis compression of single crystals of commercial-purity ingot SR beryllium, high-purity (twelve-zone-pass) beryllium, and Be-4.4 wt pct Cu and Be-5.2 wt pct Ni alloys in the temperature range of 25° to 364°C was determined using two-surface slip trace analysis, slip-step height analysis, and electron transmission microscopy. All three techniques indicated the occurrence of copious pyramidal {1 122) (1123) slip in the alloys over the entire temperature range, the amount increasing with temperature. Pyramidal slip was also indicated in the high-purity beryllium by slip trace analysis and electron transmission microscopy, but the amount was somewhat less than in the alloys. For the commercial-purity ingot crystals, only a very small number of pyramidal slip lines were observed, and these were in the immediate vicinity of the fracture surface. No pyramidal dislocations could be detected by electron transmission microscopy in this material. Dislocatransmissiontions with Burgers vectors [0001] and +(ll20) were identified by electron transmission microscopy inthe (1122) slip bands, as well as those with the j (1123) vector. This was interpreted to indicate that the edge components of the 3(1123) vector dislocations activated during c axis compression dissociate upon unloading according to the reaction i (1123) — [0001] + 3(1120) THE microstrain c axis compression of single crystals of commercial-purity ingot SR beryllium (99.6 pct), high-purity twelve-zone-pass beryllium (99.98 pct), Be-5.24 pct Ni and Be-4.37 pct Cu alloys was described in a previous paper.1 This paper covers in detail the analysis of slip traces observed on two mutually perpendicular lateral surfaces of these specimens, and a detailed description of transmission electron microscopy studies performed on foils cut from the bulk crystals after they had been deformed to fracture in the c axis compression. Observation of slip traces on single surfaces of deformed single crystals are generally insufficient to positively identify slip or twinning modes. The use of two carefully cut and oriented perpendicular surfaces can greatly aid in the positive identification and index- ing of slip traces, although even this technique may be quite inadequate if more than one type of slip system operates and if an insufficient number of traces are observed on the surfaces. The problem is greatly simplified for symmetric cases like that for c axis compression of an hep crystal such as beryllium, in which the operating slip systems are all equally inclined to the direction of the applied stress, and each slip system of a given slip mode has an equal chance of operating. For such cases, the traces of any given slip mode observed on the surfaces cut parallel to the c axis are symmetrically tilted about the c axis. It is therefore possible to quickly determine whether one or more slip modes are operating. Confirmatory evidence in support of the observations made on the external surfaces can be obtained from foils cut from the deformed crystals and examined by transmission electron microscopy. This latter technique serves to identify not only the operating slip plane but also the Burgers vector of the dislocations which participate in the slip. For this purpose, a simplified technique based upon a double tetrahedron notation is used in the present paper. The planes and directions in the hep lattice are all designated by letters rather than indices and extinction conditions are easily determined if the Burgers vector lies in the plane contributing to the diffraction. RESULTS 1) Slip Trace Analysis. The standard (0001) stereo-graphic projection of beryllium is shown in Fig. 1. The two mutually perpendicular, lateral surfaces of the compression specimen are represented by the diametrical planes AA' and BB', also referred to as surface A and surface B. For the specific case represented (a Be-5.24 pct Ni specimen deformed by c axis compression at room temperature), the A surface is tilted 5 deg to the (10i0') plane and the B surface is tilted 5 deg to the (1120) plane. Two surface trace analyses may be facilitated by examining in turn the intersection of various great circle traces of specific pyramidal planes with two surfaces and comparing the angles made with the (0001) plane with those actually observed on the two surfaces. One then identifies the slip traces by trial and error on a best-fit basis. The (1122) type planes (it was found that slip occurred on these planes) are shown plotted on the stereographic projection in Fig. 1. One obtains directly the angles between the (0001) plane and the {1122) traces by measuring the angle from the periphery to the point of intersection along the lines

Jan 1, 1969

By Richard Hodgson

FMC Corporation, at their mine and soda ash refinery near Green River, Wyoming, currently mines in excess of 3 million tons per year of trona. Upon completion of the current expansion, the mine will be producing in excess of 4.0 million tons per year. The single level mine, approximately 1,500 feet in depth, is currently serviced by five (5) concrete lined circular shafts varying in diameter from 12 ft. to 24 ft. A sixth shaft is complete, but not yet operational and the seventh is currently being sunk. Two of the shafts are equipped with single drum hoists. The original production shaft is equipped with a double drum hoist. The newest production shaft and the main service shaft are both equipped with ground mounted friction hoists. These friction hoists have given excellent service and another will soon be installed as a man and material hoist at No. 7 Shaft. There are a number of advantages that the ground mounted hoist has over a tower mounted hoist. There are also operating problems common to both. FMC's original experience with ground mounted friction hoists began in 1962 with the conversion of a single drum hoist to a friction hoist. The converted hoist was an Ottumwa with a 5 ft. diameter drum and a 4 ft. face. This hoist had been installed at the No. 3 Shaft for some years prior to its conversion to a friction hoist. At the time the conversion of this hoist was made, there were no friction hoists in service in Wyoming. Wyoming mining laws required that all conveyances carrying men be equipped with safety dogs. Since it was desired that wire rope guides be used, safety dogs were impractical. Agreement was reached with the State Mine Inspectors that safety dogs would not be necessary provided that recommended rope safety factors for hoisting men would still be maintained if one hoisting rope was broken. Since-the shaft is approximately 1,500 ft. deep, the recommended safety factor is 6.0 so that this installation has a safety factor in excess of 8.0 for hoisting men when new ropes have been installed. The hoist conversion was engineered by Lake Shore, Incorporated. The friction ring was made in halves and bolted over the original drum face which had been machined to remove the grooves. The ring provided for four 3/4 in. diameter ropes on 8 inch center to center spacing. The pitch diameter of the modified drum was 72 inches. The grove liners are hald in place by hard-wood wedges bolted to the drum. The other modification required by the conversion was an increase in size of bearing caps and the hold-down bolts because of the increased force tending to lift the drum.

Jan 1, 1975

By R. P. Carreker, R. L. Fullman, J. C. Fisher

THE existence of the phase TiAg has not been reported previously. Other investigators have denied the existence of compounds in the Ti-Ag system.13' However, phases of equi-atomic proportion have been reported by Raub, et al.' in the (similar) systems of titanium with gold and copper and zir- conium with silver. Raub's work indicated that titanium and silver are immiscible in the liquid state. No evidence of this was found although a very wide melting range exists which makes the preparation of homogeneous alloys difficult. TiAg is apparently formed by a peritectic reaction between /3

Jan 1, 1954

By W. E. Bonini, E. A. Hickok

IN the course of an investigation directed toward expanding ground-water facilities in Essex and Morris counties, New Jersey, the Board of Water Commissioners of the city of East Orange authorized a seismic-refraction survey' for the purpose of de-lineating bedrock topography below unconsolidated overburden. Results of the survey were highly satisfactory and led to the preparation of a comparatively detailed bedrock contour map. Knowledge of the bedrock depth and configuration was an important aid in selection of sites for test drilling. The portion of the East Orange Water Reserve under consideration is in the flood plain of the Pas-saic River about 10 miles west of Newark, N. J. The flood plain is about 175 ft above mean sea level and is bordered by low hills rising to elevations of approximately 250 ft. The bedrock underlying the Water Reserve consists of sandstone and shale of the Triassic Brunswick formation and is covered everywhere by deposits of unconsolidated glacial outwash sand and gravel, lacustrine clay, and recent river silt as much as 150 ft thick. Yield of wells in the sandstone and shale averages 100 to 200 gpm. Since production wells constructed in the sand and gravel aquifer in the buried river valley shown on the contour map (Fig. 1) yield 300 to 1400 gpm, it was proposed to locate additional production wells in this buried valley, where the yields per well would be maximum. In 1939 and 1946 the East Orange Water Dept. had electrical-resistivity surveys made to determine depths to bedrock. From the resistivity data the exploration company prepared a bedrock contour map. A well field expansion program begun in 1955 utilized this information to locate sites for test wells along a predicted northward extension of the buried valley in which existing production wells are located. After several test wells (wells 201-205) had been drilled, it became apparent that the resistivity information was unreliable." For example, test well 201 recorded bedrock at a depth of 72 ft, whereas the resistivity depth determination was 130 ft. As a consequence, the test drilling program was temporarily suspended and a seismic survey was under- taken to determine the topography and extent of the buried valley known from well records to underlie the existing well field. In the first phase of this study, several seismic shot point locations were placed at sites where well logs had been obtained previously. This procedure is necessary in a new area to determine whether the seismic method is applicable and what degree of accuracy is to be expected. At the East Orange Water Reserve, depths obtained from the shot points near test wells 202, 203, and 204 were within 8 to 11 pct of the depths logged (Table I). With this assurance that accurate results could be obtained, additional seismic spreads were located on the Water Reserve. Using a portable refraction seismograph, in the fall of 1955 a crew of four men shot a total of 29 reversed seismic spreads in a period equivalent to six field days. Charges as heavy as 3 1b of 40 pct dynamite were necessary at a few places to overcome ground vibrations caused by traffic on nearby highways. At most other sites, a 1-1b charge was sufficient. Travel-time plots were made for all spreads, and depths and true velocities were calculated according to formulas for multiple sloping layers by Ewing, Woollard, and Vine.' The plot of spread 7 (Fig. 2) is typical of the short spreads in which bedrock was shallow—about 50 ft in this case. Where there were not enough arrivals through the bedrock to define the high velocity bedrock line, the spreads were lengthened. This was done by placing shots on line several hundred feet away from each end of the line of geophones. It was then possible to construct complete reverse plots for both short and extended shot points (see spread 27, Fig. 3). Four individual depths were calculated from each extended spread. Three and in some cases four seismic layers were observed. The surficial layer had a velocity range of 900 to 1200 fps, the lowest velocity recorded. This seismic layer is above the water table and is interpreted as recent river silt. The bedrock had the highest velocities, which ranged from 10,600 to 16,400 fps. Intermediate velocities ranged from 4500 to 6800 fps. In every case the intermediate layer was within

Jan 1, 1959

By Arthur R. MacPherson

The development of a simple method to predict the autogenous grinding possibilities of new ore deposits is attained. This method employs a 45-cm (18-in.) dry grinding Aerofall mill to grind small quantities of core or crushed samples in the top size range of 2 to 5 cm (1 to 2 in.). An extensive program has been carried out to correlate the data obtained in the 45-cm (18- in.) test mill with the actual results obtained in large commercial plants or autogenous test plants. Enough evidence now exists from these correlation programs that the 45-cm (18-in.) mill can be used to grind small samples from a new deposit and correctly predict the autogenous grinding mill requirements of a commercial plant to treat this ore.

Jan 1, 1978

By L. V. Gregor, C. F. Aliotta, P. Balk

The structure of silicon surfaces, thermally oxi&zed in dry oxygen and in steam, was studied using the electron microscope. It was found that the structure on the original (etched) surface is retained at the outer surface of the oxide, whereas the oxide-silicon interface is smoothed out considerably. This supports the idea that, both in oxygen and in steam, the oxidation reaction occurs at the oxide-silicon interface. Mechanical damage of the original silicon surface affects the rate of oxidation. It also changes the chemical properties of the oxide, as shown by the enhanced rate of etching in buffered HF at the locations of damage. However, the oxide at the originally damaged surfaces still exhibits a high electrical breakdown strength. Exposure of thermal oxides to P205 or BzOs vapor, which will yieldphospho- or borosilicate layers, results in complete annihilation of all fine structure on the surface. Reaction of silicon with C02 gives a surface film which probably does not consist of pure SiO,. THERMAL oxidation of silicon yields uniform and strongly adhering oxide films which are normally amorphous and continuous. Contamination and surface imperfections have been reported to cause local crystallization and the formation of pinholes."' The parabolic-rate law of film growth observed by several workers for the oxidation both in steam and in dry oxygen at higher temperatures suggests that diffusion of one or more reactants through the oxide is the rate-deter mining step. One of the dif-fusants is an oxygen species and oxide is continuously formed at the oxide-silicon interface. This was concluded for high-pressure steam oxidation by Ligenza and spitzer5 from an infrared-absorption study of the isotopic exchange of oxygen. Jorgensen arrived at the same conclusion for the oxidation in dry oxygen by measuring during oxidation the resistance change between silicon and a porous platinum marker electrode in the oxide. Recently, Pliskin and Gnall' reported similar conclusions concerning the growth mechanism from controlled etch studies using a phosphosilicate marker. The work communicated in the present paper was aimed at studying oxide growth on locally damaged silicon substrates and relating it to the chemical behavior and electrical breakdown properties of the films. Since etched and oxidized silicon surfaces normally appear to be very smooth when examined by optical microscopy except for some occasional pits, it was decided to use the electron microscope as a tool. In this way, the detection of surface roughness and damage on a scale comparable to or smaller than the thickness of the film is possible. Also, the microstructure of the original substrate surface constitutes a built-in marker which represents a minimum of perturbation to the growing oxide layer, and no foreign material is introduced. Thus information on surface reactions and additional evidence on the location of oxide formation in steam and in oxygen could be obtained. EXPERIMENTAL Electron micrographs7 were obtained using a Philips EM100 electron microscope. Collodion surface replication was used since this is a nondestructive technique and thus permits replicating the same surface at different stages of processing. In order to establish the effect of different treatments it was found essential to make successive observations of the same area by using a reference point. Reference points were conveniently provided by scribing a small v mark on the original surface with a silicon carbide tip. This procedure yields damaged and damage-free areas near the reference point. Upon replication, the samples were thoroughly cleaned before subjecting them to the next process step. Mechanically lapped silicon wafers (Dow-Corning, 100 ohm-cm p-type, cut perpendicular to the (111) direction) were chemically polished in a rotating beaker with a mixture of 1 part HF (48 pct), 2 parts glacial acetic acid, and 3 parts HNO3 (70 pct) by volume. This procedure yields a smooth surface with a faint "orange peel'' structure due to a "ripple" less than 20002i deep. Oxidation in steam or oxygen was carried out in an Electroglas tube furnace. Steam oxidations were always preceded and followed by a brief exposure to oxygen at the same temperattre. The thicknesses of the oxide films under 3000A were determined with a Rudolph Model 436-2003 ellipsometer,' whereas those over 3000A were measured using the VAMFO technique. In the present study, a solution of 300 g of N&F in 25 ml HF (48 pct) and 450 ml water was used to detect areas of increased chemical reactivity in the

Jan 1, 1965

By M. E. Shank, J. Wulff

At the present time, the designer of dies for metal powder pressing is handicapped by relative ignorance of stress distribution and frictional effects at the interior surface of the die. Unckell was the first to develop a method for the study of wall friction. He used three Brinell balls on which the die rested during pressing. The total frictional wall force was determined by the size of impression these balls left on a soft metal plate. Since the method does not give radial pressures, or distribution of such pressures, coefficients of friction could not be determined. Although Unckel measured density distribution, he was not able to determine radial or shear stresses. Shaler2 has proposed theoretical expressions for the stress and density distribution within cylindrical compacts during pressing, in accordance with the experimental results of Kamm, Steinberg, and Wulff.3 By application of Siebel's method,4 Kamm et a13 plotted stress trajectories for two compacts. From the stress trajectories they calculated coefficients of friction from point to point along the die wall. As pointed out by Shaler in the discussion of Ref. 3, these values are based on progressive point-to-point calculations on finite size grid squares across the compact. In the region of the die wall such calculated values may therefore have considerable cumulative error. The purpose of the present paper is to develop an experimental method by which the nonhydrostatic pressures and shears acting on the interior wall of a cylindrical die can be measured. Such measurements can then he correlated with existing data to aid in the explanation of the pressing process. The method used is based on the elastic: properties of the thick-walled tube used as the die. The principle of super-position of force systems on an elastic body is assumed to hold. Electric strain gauges were mounted in adjacent positions on the exterior die wall in order to get an exact measurement of the variation of tangential strain over the length of the die during pressing. While in this paper, measurements in terms of only tangential strains are considered, it is well to note that similar calculations may be set up for axial strains. The latter are not preferred, since they tend to be smaller than the tangential strains and therefore permit less sensitive measurements. Discussion in this work is restricted to compacts pressed from both ends, since the elastic deformation of the die is then more amenable to analysis. Before choosing the electric strain gauge method, a more direct line of attack was considered and discarded. The discarded idea was the insertion of a pressure gauge through a hole in the die wall.* The gauge would have been in the form of a small piston. If pressure were exerted against such a gauge, it would move outward along a radius of the die. One disadvantage of the scheme is its inability to measure shears along the die wall. Another more serious disadvantage is the disturbance caused by the device itself. It would serve to change the forces it was designed to measure. No matter how small the movement of the gauge, when pressure is applied a discontinuity would exist in the wall surface at that point. Due to the stress concentration caused by the hole, abnormal deflections of the die wall would occur around the gauge. During pressing, powder would be forced into the resulting depression. The depression would then become larger with increasing compacting pressure. Powder, not being a fluid, is capable of supporting shear. The ease with which it would flow into the die wall depression to further move the piston is an indication, not of the radial pressure at that point, but of the state of shear retarding the movement. Thus the "pressure" gauge is really a criterion of flowability, and of the capability of the powder to support shear. For these reasons, it was decided that the electric strain method, herein employed, was more reliable, if more indirect. The gauges and lead wires, mounted on the external die wall do not in any way affect the behavior of the metal powder or the die during pressing. Theory of the Method THE EFFECT OF RADIAL PRESSURE ON THE DIE WALL Effect of a Single Small Band of Hydrostatic Pressure Consider a die which is a thick-walled cylinder of outer radius R. and inner radius Ri. If over a small finite length L there is a normal pressure P, a tangential strain distribution at the outer wall results. This is shown schematically in Fig 1. The exact shape of the curve may he predicted by an extension of the theory of a semi-infinite beam on an elastic foundation.6 This

Jan 1, 1950

By R. H. Walpole, J. M. Kane

IN all probability the mining and metallurgical industry as a whole can demonstrate a larger ecorlomic return from installation of dust-control equipment than any other major industrial group. This fact has partially accounted for the marked increase of dust-control installations made during the past decade. While the primary objectives for installation of dust-collecting systems are improved working and operating conditions for men and equipment, the fact that an economic return can be anticipated on salvageable materials is an added advantage which shows in partial or complete equipment write-off. The conditions apply to most phases of the mining, milling, and smelting industry, both non-metallic and metallic. As with any mechanical devices, selection of suitable dust collector equipment involves evaluation of available products with characteristics most nearly meeting conditions of the application at hand. When there is valuable product to be collected, and/or when there are possibilities of air pollution or public nuisance, collector selection is often guided by the maxim of "highest available collection efficiency at reasonable cost and reasonable maintenance." A brief review of dust collector designs will permit outlining of major characteristics of each group. Final selection will involve detailed data against a background of the problem under consideration. The dry centrifugal collectors, see Fig. 1, represent a group of low cost units with minimum maintenance. They are subject to abrasion under heavy abrasive dust loads and to plugging with moist materials. Efficiency drops off rapidly on particle sizes below the 10 to 20 micron group. Because of the large amounts of —10 micron particles in most mining dust problems, they will normally be used as primary collectors and will be followed by high efficiency units. This combination is cspecially popular where the bulk of material is desired in a dry state with wet collection indicated for the final cleanup portion. In remote plant locations, dry centrifugal~ can be used alone if product in dust form has no value or if dust loading is light enough to eliminate a nuisance in the plant area. Where high efficiency dust colleotion equipment must be selected, choice will normally involve fabric arresters, wet collectors, or high voltage Electro-Static precip-itators. Fabric arresters, see Fig. 2, rely on the passing of dust-laden air at low velocity through filter fabric. Velocity ranges from 1 to 3 fpm for the usual installation and may be as high as 10 to 20 fpm in arrangements where automatic frequent vibration or continuous cleaning of the filter media is employed. Fabric is normally suspended in either stocking type or in an enlvelope shape. Collection efficiency is excellent even on sub-micron particle sizes. Equipment is bulky, must be vibrated to remove the collected dust load, and is restricted in applications from temperature and moisture standpoints. Condensation of moisture on the fabric filter mcdia causes plugging of the passages with great reduction in air flow. Temperatures for the usual medias of cotton or wool are 180" and 200°F maximum, although the introduction of synthetic materials such as nylon, orlon, and glass cloth have increased the possibilities of this type of collector for higher temperature applications. The wet-type collector may employ a number of different principles so that entering dust particles in the gas stream are wetted and removed. Principles usually include impingement on collector surface or water droplets, often in combination with centrifugal forces. Variety of wet collector designs is indicated by typical collectors illustrated in Figs. 3 and 4. Collection efficiency is a function of the particular design, although the better collectors will have high collection efficiency on particles in the 1-micron range. Wet collectors have the advantage of handling hot or moist gases, take up small space, and eliminate secondary dust problems during the disposal of the material. At times collection of the material wet is a disadvantage. Wet collectors may also be subject to corrosion and freezing factors. The high voltage Electro-Static precipitator, see Fig. 5, is probably the most expensive type of high efficiency collector. It finds its applications generally in problems in which collectors previously discussed cannot be employed. Its collection efficiency is based on its design features and can be excellent on the finest of fume particles. Material is normally collected dry. Gas temperatures are of no great concern as long as condensation does not occur within the dry type of precipitator and the temperatures do not exceed the limits for materials used in its construction. As with the fabric arrester, provisions

Jan 1, 1954

By B. J. Kochanowsky

The idea of a portable crusher is not new. Many such crushers are available but they are small and designed for construction work. For many years the author has suggested, both in this country and in Europe, the building of larger portable crushers intended expressly for use in quarries or open pits. Although not applicable under all conditions, there are mining operations where a mobile crusher arrangement could be more profitable than the facilities now used. The primary use of a portable crusher, i.e., a crusher mounted on crawlers or tires, in the rock and mining industries is to reduce costs by permitting the substitution of conveyor belt haulage for truck or track haulage. The usual sequence of operations in surface mining is drilling, blasting, loading, haulage, and crushing. Haulage is normally accomplished by truck or track-mounted cars, the latter method being used for the longer distances. However, by using a portable crusher in the pit, the sequence of operations would be changed so that the crushing stage would occur before haulage (Fig. 1). Such a sequence would permit the use of conveyors to replace the more expensive truck or track haulage methods. Since most quarry and open pit operations normally require a crushing stage, the only additional costs incurred will be due to the investment required to purchase or construct a mobile arrangement for a crusher. But this factor has to be weighed against the advantages to be gained by conveyor haulage. As shown in Fig. 2, transportation of material by belt conveyor over short distances is less expensive than by truck. The inclination of the belt has no effect on belt speed; consequently, the hourly tonnage moved remains the same. Conversely, the output rate of trucks as expressed in tons or ton-miles per shift decreases proportionally to the haulage speed, which is considerably slowed by the steepness of the road (Fig. 3, left). Although maximum possible grades and maximum economic grades of haulage are greater for a belt than for a truck (over the same total lift), the longer haulage distances favor the use of trucks. Although power consumption for hauling on a grade increases for both conveyances, the rate of power consumption increases faster for trucks than for conveyor belts (Fig. 3, right). Since the output rate and related fixed costs are affected by the travel speed, total haulage costs with trucks would increase with the grade more rapidly than the similar costs of conveyor belts (Fig. 4). Travel distance, road grade, speed, size and number of pieces of equipment, efficiency of operation, and many other factors affect such haulage costs. In general terms it can be said that the shorter the distance, the steeper the grade, and the greater the output, the more advantageous the belt becomes in comparison to truck or track haulage. In addition to potential cost savings in haulage procedures, a portable crusher would allow better utilization and performance of shovels. Loading operations would not be interrupted as often by the necessity of waiting for cars or trucks. Unfortunately, the application of belts in open pits for haulage from bench sites is generally not practical under existing conditions because a belt fed directly by a mechanical shovel can be torn, damaged, or worn out quickly by the large rock fragments falling on it during loading. However, by using a mobile crusher this situation can be avoided. As shown in Fig. 1 (b), the shovel feeds rock into the crusher located behind it. The crushed material is initially transported by an extensible and/or movable belt, thence by a longer stationary conveyor to the plant where the material is subjected to further treatment by secondary crushing, screening, etc. The first-mentioned conveyor, needed to bridge the distance between the shovel and the stationary conveyor, is necessarily variable in length owing to the continuous movement of the shovel and the desire to keep the stationary belt at a safe distance from the bench during blasting operations. The remarkable part of mobile crusher operations is the extra-ordinarily high output per man-shift, the low maintenance and power requirements for haulage, and the increased output of the loading shovel. A cement quarry which has been using a portable crusher and conveyor since 1956 requires only three men to operate the shovel and crusher and to transport the crushed rock by belt from the quarry face to the screening plant. If truck haulage

Jan 1, 1961

By D. Kunstelj, M. Stubicar, A. Tonejc, A. Bonefacic

A. Bonefafcic, D. Kunsfeli, M. Stubicar, and A. Tonejc The present communication is concerned with the variation of the texture in aluminum wires with die angle and temperature, at constant speed of extrusion. Experiments were carried out concurrently on refined samples, with a stated purity of 99.997 pct pure A1 and commercial samples of 99.5 pct Al. Ingots of refined aluminum samples were machined to 30-mm-diam by 150-mm-long billets. These billets were transformed to 5-mm-diam wires by drawing. The final form, suitable for examination, was obtained by extrusion through conical-face dies with a 1-mm hole diam and extrusion ratio 5:l in diam. The initial form of the commercial aluminum samples was drawn wire 5 mm in diam. These samples showed a poorly defined texture with (111) as a major and (001) as a minor component. A similar defined texture appeared in the refined aluminum samples after drawing to 5 mm diam. Conical-face dies with different angles (defined by the axis and the generating line of the cone) were used in our experiments. The values of the angles were 27, 35, 45, 57, 63, and 90 deg. The extrusion container was fitted with a heating element and controller permitting temperatures up to 600°C to be maintained within i5"C. Extrusion was performed at 250°, 300°, 350°, 400°, and 500°C at constant speed (approximately 1 mm per sec) and constant die reduction. The extrusion product was a wire 1 mm in diam and approximately 20 cm long. In order to remove the surface layer with the "conical" texture and to reduce the absorption by the X-ray examination of the samples, the extruded wire was etched to 0.22 mm in diam. Experiments were performed in the middle sections of the 20-cm-long wires. In addition to the die of l-mm hole diam, dies with a 1.5-, 0.7-, 0.6-, 0.5-, and 0.4-mm hole diam and 63-deg die angle were constructed. In our experiments we did not find in these ranges any important difference concerning the texture of the extruded wires and we continued our work solely on the 1.0-mm die. The diffracted X-rays (Cu K radiation) were recorded photographically. Diffracted intensities were measured on the (111) reflection with a microphotometer. The relative amounts of texture components were determined from the areas under the diffracted maxima. We found the texture of extruded aluminum wires to be strongly influenced not only by the temperature of extrusion and the purity of the sample but also by the form of the die. It is generally admitted that cold-drawn aluminum wires have mainly a (111) texture with a small amount of (001) component, Table I of Ref. 1. In our experiments with wires extruded in conditions represented by Fig. 1, in some cases a single (001) texture was obtained. If these wires were drawn repeatedly at room temperature, X-ray measurements revealed a duplex (001)-(111) fiber texture. Further drawings increased the (111) and decreased the (001) texture component. In Fig. 1 the percentage of material oriented with (001) parallel to the extrusion direction is represented as a function of the temperature and the die angle (a), for commercial and refined aluminum samples, respectively. From these diagrams we may draw the following conclusions. The slope of the die (a) influenced more strongly the texture at the lower rather than the higher temperatures. Again, a stronger influence was found in the case of the commercial in comparison with refined aluminum samples. In the case of the commercial aluminum samples the amount of material with (001) texture increases with increasing wire temperature in an approximately linear manner. This effect is less pronounced in the pure aluminum samples, with the exception of the die with a = 45 deg. In this case the (001) texture decreases with increasing temperature, as shown in Fig. 1. Component (001) is more pronounced in higher-purity aluminum samples. Our experiments led to the conclusion that both (001) and (111) components are essentially stable in extruded aluminum wires. As we obtained a single (001) texture starting with a sample of drawn wire in which the (001) component was very weak, our experiments revealed that the (001) component is not a remnant of the initial texture; this is in disagreement with the findings of Vandermeer and McHargue.1 We gratefully acknowledge discussions with Professor M. Paic. 1 R. A. Vandermeer and C. J. McHargue: Trans. 7MS-AME, 1964, vol. 230, p. 667.

Jan 1, 1969