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By G. Matheron

This paper discusses important aspects, both psychological and methodological, which have delayed the introduction of geostatistics in practice. The evolution of geostatistics is traced through three 'generations', and in conclusion some important questions are raised on the current status of the subject and possible areas of future research.

Jan 1, 1987

By Toshio Suzuki, Machiko Ode, Won Tae Kim, Seong Gyoon Kim

"The Ostwald ripening and growth and coarsening of the secondary dendrite arm are studied using a phase-field model. The phase-field parameters are obtained at a thin interface limit proposed by Kim et al. In Ostwald ripening analysis, the difference of the concentration due ·to· the curvature effect is shown. The third power of the average particle radius Rav is proportional to time and the ripening constant shows a good agreement with the value by Deppers et al. The particle radii distribution shows the transition behavior to attain a self-similar stationary shape. The growth and coarsening behavior of the secondary dendrite arm is also analyzed using a phase-field model. The estimated arm spacing and its dependence on time are in good agreements with experimental data.IntroductionThe ripening or coarsening process controls the microstructure during the late stage of solidification. The ripening phenomena are recognized firstly by the Ostwald [1]. The first quantitative analysis for the Ostwald ripening in the limit of vanishing solid fraction was provided by Lifshitz, Slyozov and Wagner (LSW) [2,3]. In their study, that the mean radius grows proportional to the cubic root of time and the size distribution of precipitations shows a ""self-similar"" shape are shown. Most of the studies for the Ostwald ripening confirm or predict these two general rules above. In case of finite solid fraction, the general rules are observed but the ripening constant is larger and the self-similar shape is wider than the LSW prediction respectively [4-6]. To analyze· the high solid fraction system, the theories that consider the solute field correlation are proposed [4,7-8]. In the theory, however, since the particle is treated as the point, the effect of the concentration field deviation from the monopole field should be taken into account. Recently the numerical simulation, in which not only diffusive transportation of solute but also convection effect is considered, has been done using a phase-field model [9]."

Jan 1, 2000

By John D. Vincent, Howard W. Jacky

This chapter covers the normal problems encountered in the building of an ore concentrating facility. To produce such a facility In today's environment requires correlation by the engineers involved of geologic data, mine planning, scheduling, future planning, water resources, power, land availability, testing, design, start-up and environmental considerations. Of course, the program scheduling and character of the ore will determine the weight given to the above considerations in the final design and construction of the plant.

Jan 1, 1978

By Jean-Michel Rendu

In most mining operations, some degree of selectivity is applied. Whether one deals with surface or underground operation, ore zones, and waste zones are defined not only on the basis of the value of the ore contained, but also taking mining constraints into account. A number of computer techniques are presented which can be used to determine the optimum location of the footwall and hanging wall of ore zones intersected by drill holes. Minimum mining width and minimum internal waste width constraints are taken into account, as well as other economic constraints. The system is presented as an integral part of a larger manumatic ore reserve and mine planning system.

Jan 1, 1982

Jan 1, 1895

By Jos D. Weeks

On the extreme fringe of' the great Appalachian coal-basin is a long narrow detached coal-field, which is, in some respects, one of the most important in the United States. This field, about 90 miles long by 2½ to 16 miles wide, extends from the southwest corner of Somerset county, Pennsylvania, through Allegany and Garrett counties, Maryland, Mineral, Grant and Tucker counties, West Virginia, into Randolph county, West Virginia. In this distance four distinct sub-districts are recognized, the Wellersburg in Pennsylvania, the Cumberland-Georges creek in Maryland, and the Elk Garden and the Upper Potomac in West Virginia. The output of coal from the whole field including steam, domestic, smithing and coking-coal of the best quality, is about 4,500,000 tons annually. It is the nearest to tide-water of all the bituminous coal-fields which supply the great coal-markets of the Northern Atlantic seaboard ;

Jan 1, 1895

By P N. Holtham

As part of a long-term study of titanium minerals processing being undertaken by the Julius Kruttschnitt Mineral Research Centre (JKMRC), techniques have been developed to measure the electrical properties of the various minerals. The measured values will be used to model the behaviour of the various minerals in high-tension roll and electrostatic plate separators. The resistivities of ilmenite, rutile and zircon from a number of Australian producers have been measured by applying a DC voltage across a test sample and measuring the resulting very small current flow. By appropriate design of the measurement cell and attention to the experimental procedure, reproducible resistivity values have been obtained, ranging from 106Ωm for ilmenite to 1013Ωm for zircon. However, the conditions of measurement are radically different from those under which electrical separation takes place. It is not certain that the measured values reflect the resistivities seen under high-tension separation, during which the particles are subject to a high intensity corona field. Consequently, an alternative technique for measurement of resistivity under conditions of corona bombardment has been developed. It is based on the experimental procedure of Castle and Yelle (1979) used to measure the resistivity of fly ash under the conditions occurring in electrostatic precipitators. This paper describes the development of the segmented ground plane measurement surface and a high-voltage switched resistor network which comprises the in situ resistivity apparatus. Results are presented comparing the measurements made under corona bombardment with those made using the DC measurement cell. The equipment has also been used to study the current distribution from a corona wire, as a function of high-tension voltage and wire-to-plane spacing.

Jan 1, 2001

The paper considers Aboriginal responses to large-scale mining, including Indigenous attitudes towards land access for exploration and project development. The core question, in which I have been interested for some time (Trigger 1997a; 2000; 2001), is: what are the significant factors affecting responses among Indigenous communities to mining exploration and development project proposals?

Jan 1, 2002

By N. Ahmed

The collection of hydrophobic particles in the froth phase in flotation has been studied. A continuous flotation cell was developed, in which the froth phase could be isolated from the pulp zone. Hematite particles, d80 = 87 µm, were floated in the pulp, using a conventional oleate collector, while glass spheres of similar diameter, d80 = 82 µm, were introduced in wash water added to the froth. Four samples of glass spheres, with contact angles between 0 and 82 degrees, were used. The results indicate that the efficiency of collection of the hydrophobic particles in the froth can be very high. The process is strongly influenced by the hydrophobicity of the particles and the surface area available for attachment in the froth. Recommendations for the flotation of particles in the froth phase are made, especially regarding the desirable hydrophobicity as reflected in the contact angle, the froth depth, the solids concentration in the feed to the froth, the air rate and the wash water rate.

Jan 1, 2001

Joseph William Richards, was born in Oldbury, Worcestershire, England, on July 28, 1864, of English-Scotch parents, Joseph and Bridget (Harvey) Richards. In 1871, he came to this country with his parents. He attended the public schools of Philadelphia, Pa., where his father was a manufacturing metallurgist, and in 1882, graduated from the Central High School with the degree of A. B. The same year he entered Lehigh University, from which he received the degree of A. C. (Analytical Chemist) in 1886; M. S. in 1891, and Ph. D. in 1893. His connection with the university was continuous from 1887 until his death, and he therefore adds another to the list of names of men Prominent in the A. I. 11. E. who have helped to develop Lehigh University to the important position which it now occupies in mining and metallurgical education in respect of world-wide fame. It is fitting to recall in this connection that, Eckley B. Coxe, a fonnder of the A. I. M. E., four times its vice-president,, and president in 1878-79, was literally a pillar of the university for several years prior to his death; Thomas M. Drown, founder, vice-presi(lent, secretary for 11 years, honorary member, and president in 1897, was president of Lehigh University from 1895 to 1904; and Henry S. Drinker, founder, manager, vice-president, and honorary member, was president of the university from 1905 to 1920. Doctor Richards was no less active in both institutions. With the exception of the years 1886 to 1887, when he was superintendent of the Delaware Metal Refinery of Philadelphia, his professional life was devoted to the upbuilding of the metallurgical department of the university, in part through his continuous services as a member of the teaching staff, and in part through the international renown won for the department by his achievevements as author, investigator, expert and rerognizcd authority in metallurgy, especially the metallurgy of aluminum, metallurgical-chemical calculations, and electrometallurgy. He was assistant instructor in metallurgy and blowpiping in 1887; instructor, 1888-90; instructor in metallurgy, mineralogy and blowpiping, 1890-97; assistant professor, 1897--1903; professor of metallurgy, 1903-1921. He died at his home in Bethlehem, Pa., on Oct. 12, 1921, of heart failure. To the A. I. M. E., for a continuous period of a dozen years, his services were equally loyal and effective. He was vice-president, 1910-11, and 1916-17; councilor, 1912; dirctor, 1913-15; chairman of the Iron and Steel Clommittee, 191-1-21; he was one of the framers of the Insti-

Jan 1, 1922

By H. T. Clark, S. Feigenbaum

THE importance of measuring the temperature of molten steel in the open-hearth furnace has been recognized for many years. Poor temperature control may be costly to steelmaking operations and lead to a lowered quality of the steel. Low or excessive temperatures may shorten the life of the furnace, ladles and molds. Rates of reactions in the furnace and efficiencies of deoxidizers are known to change materially with a change in the temperature of the metal and slag. Ladle skulls and mold and stool stickers cause steel to be scrapped instead of being converted into useful products. Finally, the structure, segregation and surface condition of ingots are affected by the teeming temperature. Mill investigations of the effect of bath temperature upon steelmaking operations have been largely qualitative in character, based upon observations by practical melting men. The physical chemist has used the empirical information available and has reached reasonable and useful conclusions with respect to the various melting processes. The introduction of a reliable direct- reading pyrometer will permit accurate quantitative evaluation of the effects of temperature and should furnish a more rational basis for study of the thermo- chemistry of steelmaking. The problem is not merely one of making a small number of temperature measurements in the open-hearth furnace. This has been done by several methods to a degree of precision that was apparently satisfactory. Considerable effort by a number of investigators has been directed rather to the development of an open- hearth bath pyrometer that would be both accurate and practical for routine measurements. To be practical, the pyrometer should be inexpensive to operate; that is, the installation, operating and maintenance costs should be exceeded by the tangible benefits to the open-hearth operator. Temperatures from 2800° to 3100°F. are encountered in the open-hearth furnace. The surface of the molten metal is covered by several inches of slag, which prevents direct observation of the metal surface for optical or radiation measurements. Both slag and metal are highly reactive at these temperatures and will attack to a greater or lesser extent any material immersed in them. Adequate protection of thermocouples, which of necessity must be brought to the temperature of the bath, has generally resulted in a large, heavy assembly made up of .brittle materials, unsuited for handling on the open-hearth floor. The lie of the equipment was short and maintenance was an important consideration. EARLIER WORK Any one of a number of physical proper- ties of liquid steel could conceivably be used as a basis for temperature measurement. Efforts to the present time, however, have been confined largely to measuring either the thermal electromotive force generated between two dissimilar materials immersed in the steel or the intensity of radiation from the surface of the steel. These

Jan 1, 1946

By E. W. Dewing

The nature of solid solutions of sodium in non-paphitic carbon at temperatures near 1000°C has been investigated by an electrolytic technique. The activity coefficient is found to vary strongly with the heat-treatment temperature of the carbon, and an analysis of the energy terms involved suggests that this is due to variations in the Fermi level. The diffusion coefficient for sodium is in the range implying that the sodium atoms (or ions) are not bound to specific sites on the carbon, in agreement with lack of evidence for specific compounds in the activity -composition curves. In the light of These results phenomena occurring in aluminum reduction cell linings are dis-cussed. It is concluded that sodium migrates by diffusion through the carbon lallice and not the pores, and that A14C9 is formed within the lining hy The excess of NaF invariably found in used linings is formed by this reaction and by air oxidation: There has recently been much interest in the swelling of carbon which occurs when it is made cathodic in an aluminum electrolysis cell, and there is general agreement that the phenomenon is due to the penetration of sodium atoms, derived from the reaction on the carbon lattice. (NaF and AlF3 are constituents of the fused-salt electrolyte.) The low-temperature lamellar compounds of potassium with graphite are well-known, and one compound between sodium and graphite has been reported.4 There is, however, virtually no information on the basic chemistry of the interaction of sodium with nongraphitic carbon at high temperatures, although Dell3 has made some fundamental studies of rates of penetration. At the time the present work was carried out these were not available. Rapoport and samoilenkol had measured rates of physical expansion in a dilatometer, using the fractional increase in length of a carbon specimen after electrolysis in a cryolite bath for 2 hr as an index of susceptibility to cathodic swelling. Work here with a similar apparatus showed that expansion (of a 1.5-in.-diam cylindrical specimen) ceased in less than 20 hr, and that the final expansion was much more reproducible than the value at some intermediate time. This suggested that an equilibrium was being set up, and that a thermodynamic approach was required. The results obtained are not as accurate as had been hoped, but they are the only ones of their type available and have enabled useful conclusions to be drawn. The experimental work was divided into two parts: an investigation of the activity-concentration diagram for sodium in carbon, and a rough determination of the diffusion rate. For the former, most of the experiments were made with petroleum coke even though this is not a form of carbon used in cell linings. It has the advantages, however, that it is a homogeneous material, that it is low in ash, and that its structure is reasonably well understood. Anthracites and coal cokes gave results of the same type as obtained with petroleum coke, but the reprodu-cibility from specimen to specimen was extremely poor. EXPERIMENTAL 1) The Activity-Composition Diagram for Sodium in Carbon. The petroleum coke was ground, pressed at 40,000 psi into plates 19 by 9 by 2 mm without added binder, and heat-treated. The sodium activities were established by an electrolytic technique. The carbon was made anodic in a cryolite bath with an aluminum cathode, and a controlled potential, E, applied so that the sodium activity at the anode was given by ln Na = 1n asa - EF/RT [21 where as, is the sodium activity generated by Reaction [I]. The relative activity is sufficient for many purposes and is simply given by The value of Na not at present known, but when the thermodynamics of the Na-A1 system have been worked out it can be derived from the equilibrium

Jan 1, 1963

By Adolfo Pillihuaman, Javier Montalvo, Adriana Virrueta, Alberto Aguilar

"El presente trabajo estudia la lixiviación de un mineral oxidado de cobre en una solución acuosa de amonio, con el objetivo de obtener las condiciones óptimas de lixiviación del cobre contenido en el mineral malaquita. El mineral de cobre estudiado es proveniente de un yacimiento del sur del Perú y fue caracterizado por difractómetro de rayos-X, ICP-OES y Absorción Atómica."

Sep 1, 2017

By John H. McKillop

Industrial minerals production in Newfoundland in--creased in gross value by a total of 175 per cent during the ten-year period from 1954 to 1964. The Province accounts for all of ?Canada's fluorspar production and contains one of the most important fluorspar districts in North America. It is also the only producer of pyrophyllite in Canada, and quite recently has become an important producer of asbestos fibre. Limestone, gypsum, brick shale, sand and gravel also ?Contribute appreciably to the expanding industrial minerals phase of the Province's rapidly growing mining industry. Geological diversity characterizes Newfoundland's industrial minerals: Pyrophyllite deposits were formed by contact metamorphism of predominantly volcanic Proterozoic rocks. Fluorspar deposits are fissure-filling veins having the characteristics of typical epithermal deposits. Chrysotile asbestos production comes from one of the Island's serpentinized ultrabasic belts. Limestone is produced at three localities; two of them in the extensive carbonate rocks of the west coast. Gypsum production comes from a thick evaporite (gypsum and anhydrite) sequence in the Carboniferous rocks of the St. George's Bay area. Introduction

Jan 1, 1965

In the 1890s, The Goldfields Water Supply Department in Western Australia commissioned the diamond drilling of two deep artesian exploratory water bores near Coolgardie (Blatchford, 1899). At the time, in spite of strongly-worded advice to the contrary from the Government geologists, there was a wide popular belief that you could obtain artesian groundwater virtually anywhere providing you drilled deep enough. The first Coolgardie hole was drilled to over 900 m, despite the fact that the bore penetrated granite from a depth of 5 m below the surface. Drilling proceeded for more than 16 months, between July 1896 and November 1897. A small quantity of salt water was struck at a depth of 36 m. The second bore was mercifully terminated at a depth of 50 m, also in granite, with again only a small inflow of salt water. Such were the desperate lengths that were pursued to obtain a reliable water supply for the influx of people in the Eastern Goldfields gold rush. The WA Goldfields continued to rely on huge condensers for water supply until that great engineering feat, the construction of a water pipeline from Mundaring Weir to Coolgardie, was completed in 1903. An enormous network of rail tracks penetrated outwards from Kalgoorlie and Coolgardie for the collection of timber, principally to feed the condensers. Remnants of the rail network are still visible today. The acute shortage of fresh water led to great deprivation, disease and death among the early miners. Today, the water problems faced by the mining industry are thankfully not as severe, but they are nevertheless no less challenging. The southern part of the WA Goldfields is a notoriously difficult area for finding potable quality groundwater. Even as recently as the 1990s, there were occasional serious efforts to find potable groundwater in that area, some very imaginative and innovative. One mining company, working south of Southern Cross, spent many months experimenting with recovery of potable quality water from a shallow freshwater lens overlying hypersaline water in a low permeability weathered granite aquifer. They used very low capacity pumps manufactured from car windscreen washer pumps powered by solar panels.

Jan 1, 2000

By F. E. Lathe, G. A. Guess

This investigation was started with the idea of determining whether copper-nickel mattes might not have a lower flowing temperature than copper mattes, and thus perhaps aid in accounting for the difficulty so far experienced in attempts at pyritically smelting copper-nickel ores. We have used the term flowing temperature to avoid confusion with the usual melting temperature. The idea at first was that there might be a greater viscosity range in the one matte than in the other. In the early experiments it was in our minds to determine the relative fluidity of the mattes at a given temperature. Looking to this end we tried pouring equal quantities of matte at the same temperature down an inclined graphite slab, and comparing the distances traveled. Results from such experiments were not satisfactory. We next tried pouring equal quantities at the same temperature through a drilled hole in an Acheson graphite crucible, timing the flow with a stop watch, the whole operation being carried out in the muffle. The flowing temperatures of the mattes tried in this way appeared to be about the same, and there was no marked difference in their fluidity when well fused. Oxidation gave some trouble. These experiments finally led to the adoption of the following apparatus which we thought at the time was wholly original with us, but which we have since found was described by W. McA. Johnson.l The tray used was a slab of graphite 8 in. long, 2 in. wide and 1/4 in. thick. It had six holes, into each of which sat a cup of Acheson graphite. Centrally in the bottom of each cup was a vertically drilled hole 3/16 in. in diameter and 1/2 in. long. The mattes to be tested were put into the cups, in a solid piece. The cups were covered with inverted Battersea "A" cups. The tray was put into the muffle of a gas-fired furnace. Supports on each end held the tray about 2 in. from the floor of the muffle. Under

Jan 1, 1917

By Gerald V. Jergensen

Does an idea have merit? What does it cost to implement? Can the concept be implemented successfully? The ultimate proof is to try, then see. However, when there are many millions of dollars at stake, blindly building and trying requires considerable courage. Owners and investors in retrospect might choose other less complimentary words. So we might ask, "How might we establish the feasibility of an idea or concept before committing large sums of money to the ultimate test?" From this basic and prudent question, has evolved the engineering concept of the feasibility study. A feasibility study is simply a systematic evaluation of an idea or concept to determine the prospects for success. In a literal sense, a feasibility study considers an idea in terms of its data base, "builds" the idea on paper, "operates" that idea, calculates the cost and benefits, then measures the probable success in terms of some economic, technical or financial standard. Feasibility studies can be quite modest in scope yet provide useful insights as to the viability of an idea. A study might be initiated only to examine the completeness or validity of the metallurgical data base. Another study could be a search for a workable idea or solution to an already-identified possibly troublesome problem. In this latter case, the question, "Will it work?" may be far more important than, "How much will it cost?" Feasibility studies are sometimes global in scope, involving several dozens of specialists and examining an entire "grass roots" mining complex. Other studies may be less ambitious but equally important in examining an expansion proposal or developing new operating techniques. Studies may be commissioned to remove plant bottle-necks, solve maintenance problems and so on. The terms study and feasibility study are used interchangeably in this chapter. They denote a systematic method to examine a proposed concept or idea. DATA BASE Typically, studies are initiated with a minimum amount of specific information and a maximum number of assumptions. As the work proceeds and the data base expands, assumptions are replaced

Jan 1, 1982

By Alexander May

This report describes a new method of weighing based upon observing the apparent weight of an object ill two separate pure gases. The method is presented in terms of experimental data which prove its soundness, but does not attempt to show the maximum accuracy possible with this technique. The new method incorporates the underlying principle that the apparent weight of an object is a linear function of the density of the atmosphere in which the object is weighed. The coefficients of this linear function are the true mass and volume of the object. From this functional relationship the true mass and volume of the object may be determined.

Jan 1, 1970

By R. Q. Shotts

This paper is a review of recoverable reserves of bituminous coal in the Southern Appalachian area, according to the latest published estimates. A few comparisons are made, some apparent trends are discussed, and some comments are made regarding the limitations of present estimates. The definition of Southern Appalachian area used in this report is somewhat arbitrary. It includes all the bituminous coal deposits of Alabama, Georgia, and Tennessee. All of West Virginia has been excluded. The East Kentucky and Virginia counties included were selected in connection with a literature study the writer made in 1959 of possible coal supply areas for the Tennessee Valley Authority. The selected counties were considered to be the only ones from which TVA might expect to obtain coal. The availability of coal from some of these counties is doubtful, but no other East Kentucky counties were considered more than remote possibilities. With these limitations, the Appalachian area covered is that from which producers of electric power and steel and commercial coal users, located in the Southeastern U. S., may expect to obtain their supplies of coal. Of course, it is recognized that coal from the eastern interior fields is also available to many of these same organizations. RANK AND QUALITY OF THE COALS Practically all the coals in the Southern Appalachian region are of high volatile A bituminous rank. An occasional sample indicates a slightly lower rank, but such samples may be oxidized or otherwise not representative. Some thin beds in Lookout Mountain and Sand Mountain in Alabama and Georgia, are low volatile bituminous coals, but they have not been mined extensively in modern times. There is a possibility that some of the deeper beds along the southeastern edge of the Warrior field of Alabama are near the Low-medium volatile bituminous dividing line. The Sewanee bed and some other minor ones of the Southern Tennessee field, some of the lower beds in Virginia, many beds in Sand and Lookout Mountains in Georgia and Alabama, one or more beds in the Coosa field, possibly some lower beds in the Cahaba field, and most of the beds along the southeastern edge of the Warrior field and the southern end of the Sequatchie anticline of Alabama, are of medium volatile bituminous rank. The quality of the Southern Appalachian coals is highly variable. Some of them, particularly such prevailingly thin ones as the Black Creek bed of Alabama and the Straight Creek bed of Kentucky, are unusually low in mineral matter— probably the lowest in the U. S. With the exception of certain beds and local areas, Alabama and East Kentucky coals probably have as low average ash and sulfur content as can be found in any sizeable coal area in the country. The sulfur content of Southern Appalachian coals is also variable, but few beds are consistently high in sulfur. In Alabama, sulfur generally increases from southeast to northwest across the Warrior field, but this trend is not quite as clear in the other states. A few beds in Northern Tennessee are prevailingly high in sulfur. All Southern Appalachian coals are potential coking coals if they can be prepared to meet chemical requirements. Only a comparatively small part of the medium volatile A bituminous coal, but most of the medium volatile bituminous coal mined is actually used for coking purposes. An estimate of reserves of coking coal under the requirements of present practice, could be compiled comparatively easily, but this probably has never been done. The reserve of coal that can be coked as an ingredient of a suitable blend is probably many times the size of the reserves of coal that will yield suitable blast furnace and foundary coke without blending. WHAT CONSTITUTES ECONOMICALLY RECOVERABLE COAL RESERVES? When one first realizes the vast extent of the coal-bearing rocks in the Southern Appalachian area, (see Fig. 1) the thought is likely to occur that the supply of coal is inexhaustible. This is particularly true on realizing that in some of the basins of thicker coal-

Jan 1, 1962

By Owen F. Devereux

Two discrete types of microstructure me seen in cermets formed by the reaction: 4Al (liquid) + 3SiO2 (glass) — 2A12O3(a) + 3Si (solid) Relatively coarse-grained macroscopically isotropic specimens resulted from reaction with aluminum containing appreciable silicon, while macroscopically anisotropic fine-grained specimens were formed by reaction with aluminum low in silicon. Optical microscopy, electron microscopy, and X-ray diffraction suggest that the anisotropic material contains gross areas in which submicroscopic grains of a A12O3 are oriented along radial lines drawn from the specimen surface. These lines are presumed to originate at defects in an otherwise protecting surface layer. A unique cermet is formed by the reduction of high-silica glass by molten aluminum according to the reaction: 4A1 (liquid) + 3SiO2 (glass) — 2A12O3 (a) + 3Si (solid) The free-energy change accompanying this reaction is -150 kcal at 800°C; the volume change (volume of A12O3 and silicon minus volume of SiO2) is +6 pct. The reaction product, however, contains aluminum metal as well as Al2O3 and silicon because some of the product silicon is dissolved in the aluminum bath and is replaced by aluminum in the structure. The product is a hard gray solid that retains the external dimensions of the original silica article. The system has been studied in the past, the investigations culminating in patents to George1, 2 and Saw-chuk., The former emphasize that this reaction is but one of a relatively broad class of such systems, while the latter demonstrates that a marked improvement in the gross physical properties of the cermet can be obtained by dissolving appreciable quantities of silicon in the aluminum reactant. The system has also been studied by workers at Rolls Royce Ltd.,4-6 who have patented the addition of small quantities of arsenic, antimony, bismuth, or phosphorus to the reactant bath to SO impede the reaction that glass fibers may be metal-coated by immersion in molten aluminum.

Jan 1, 1969