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THE developments in construction and operation of the basic open-hearth furnace that have taken place in recent years have placed new emphasis on the vital influence played by regulation and control of the combustion system in both furnace production and furnace life. The several factors influencing flame development, such as regulation of fuel supply, air supply, air preheat, furnace draft, and furnace reversal, must be controlled closely if successful furnace performance is to be accomplished. Rugged instrumentation of distinctive design is required to sup- ply dependable information concerning operating conditions, which is requisite to proper regulation of combustion. This chapter attempts to give a practical discussion of the various features of open-hearth practice and instrumentation related to the efficient heating of the furnace, control of temperature, and protection of the furnace structure from accidental overheating. The appended references will be helpful to readers wanting a more detailed treatment of individual topics. OPEN-HEARTH FUELS The most important open-hearth fuels are listed in Table 4-1 together with their compositions and other data useful for combustion calculations. A detailed discussion of open-hearth fuels is not attempted here, but certain factors peculiar to their application to this type of process are briefly indicated on the following pages. Very often an open-hearth shop is forced by economic factors to use a fuel to which its furnaces are not very well adapted, because the general fuel-allocation scheme for the works as a whole seems to demand it. Often a variable marginal supply of coke-oven gas or tar must be consumed by the open hearth, together with another fuel such as producer gas, natural gas, or oil, to fill out total requirements. Most furnaces employ more than one kind of fuel during their useful life; however, the partial redesign

Jan 1, 1964

By J. L. Huitt, B. B. McGlothlin, J. J. Day

Laboratory tests were made with pure minerals and actual reservoir rock samples to study the effects of hydrothermal (steam m hot water) treatments on reservoir rock properties. These tests showed that hydro-thermal treatment of many reservoir rocks can result in significant rock softening. The softening was attributed primarily to the partial destruction of dolomite and kaolinite and the synthesis of montmorillonite in the presence of excess silica. In many cases, the softening was great enough to cause considerable healing of propped fractures; therefore, a serious reduction in welt productivity could result. In other tests it was found that the addition of ammonia to a hydrothermal treating fluid in a concentration as low as 0.013 Ib/lb of water not only could prevent rock softening but could cause rock hardening. The results of X-ray diflraction analyses of rock samples showed that when ammonia was added to the treating fluid, ammonium-mica and analcite were formed instead of montmorillonite. No significant permeability damage was observed in the sandstones that were subjected to the ammonia-hydro-thermal environment; in some sandstones, permeabifity improvements resulted. INTRODUCTION As the use of steam or hot water becomes more prevalent in well stimulation methods. the need for information on the effects of such treatments on reservoir rock properties becomes increasingly apparent. Several works have been published on high-temperature changes in rock properties,',' but these are more applicable to in situ combustion operations than to steam or hot water injection processes. The mineralogical literature contains many publications which report on the changes occurring with various pure minerals in hydrothermal systems. A review of this literature denotes the ease with which entirely new, crystalline mineral phases can be synthesized from other minerals in hydrothermal environments at temperatures, pressures and residence times typical of those encountered in oilfield thermal recovery or stimulation processes. Discussions of many of these experiments are given by Deer et al. Grim,' Roy et al., Zen\ and Hawkins.' One of the most significant of these pure mineral studies is the hydrothermal synthesis work of Levinson and Vian" in which montmorillonite was synthesized from naturally occurring minerals; i.e., kaolinite, quartz and carbonate minerals (particularly dolomite). These reactions occurred at 575F in only 2 days and at 300F in 5 days. These results may be applicable to petroleum reservoir rocks since the minerals studied were those which are commonly found in sandstones. Furthermore, the environmental conditions imposed in the studies were very similar to those involved in thermal stimulation of petroleum reservoirs, e.g., steam or hot water injection. Other studies have suggested that weak rocks could be hardened by "electrochemical induration", a process in which an electric current is applied to a clay-containing rock body. These tests can be regarded as hydrothermal treatments since they were conducted in some instances with aqueous solutions and since clay temperatures during the electrical treatment reached a maximum of about 100C. Although a number of studies of the reaction of pure minerals have been reported, very little has been published on the reactions of petroleum rock-hydrothermal systems. No work has been reported on preventing the more detrimental rock changes in rock softening which might occur during the injection of steam or hot water into reservoirs. The studies described in this paper were conducted to provide such information. EXPERIMENTAL APPROACH The laboratory tests included studies of the effect of hydrothermal treatment on core samples from several different reservoirs. The hydrothermal treatments (simulated steam treatments) were conducted with distilled water at 575F, for the most part, for periods of 2 to 6 days. This temperature level was selected because it represented that temperature which would probably prevail in several cases under consideration for steam injection projects. The core samples, as well as the pure mineral samples, were contained in high-pressure stainless steel, autoclave-type pressure vessels. The effects of the hydrothermal treatments were evaluated by measuring the penetrometer hardness, formation rock embedment strength and permeabilities of the core samples before and after the treatments (Fig. 1)'" In addition, the mineralogical changes in the specimens were studied by X-ray diffraction. Concomitant with the core sample studies, the mineralogical changes were studied in greater detail by conducting hydrothermal synthesis experiments with pure minerals at similar temperature levels and residence times. For the most part, samples of finely-crushed pure dolomite.

By J. T. Eash, N. B. Pilling

As a group, the alloys of iron, nickel and carbon are, in application, one of the most versatile of the ferrous alloy family, and while many investigations have been made of their properties and structure only a few attempts have been made to show the microstructural relation over a wide range of composition. It is neccssary at once to be clear about the kind of structural relation with which we are concerned. The equilibrium diagram provides quantitative data regarding structural make-up and its variation with temperature, but equilibrium structures often are far different from the technologically significant ones. This is particularly true of steels and cast irons, and some of the most important cornponents of their structure may have no place in the diagram of equilibrium. The fugitive phases that result from transFormation are dealt with in a highly detailed and descriptive manner in. the S-curves originated by Bain. The present effort lies in a still different field, which is to portray the relation between sweeping changes in composition and in resultant structure, under controlled but nonequilib-rium conditions of thermal treatment. The Guilletl diagram presented in 1903 was the initial attempt at such a correlation and frequent references to this diagram can be found in the literature even though later work has shown it to require considerable modification. Kase2 published in 1925 a diagram that was based upon observations of furnace-cooled melts: At low carbon contents this diagram agreed fairly well with experience in showing pearlite to exist in alloys containing up to 6 per cent nickel, and completely austenitic steels at 24 to 28 per cent nickel. At high carbon contents, however, irons were indicated as being martensitic at around 2 per cent nickel and austenitic at 12 per cent nickel; these interpretations are open to serious question. Based upon experience with steels and cast iron, Wickenden3 suggested a diagram that agreed fairly well with Kase's in the steel range but which presented a wide departure from it in the higher-carbon, high-nickel regions. In its broad picture, the Wickenden diagram is an approach to "practical" structures. Reference may be made at this point to the efforts of Marsh5 to construct an iron-nickel-carbon equilibrium diagram by the coordination of scattered data, which are described at length in the monograph cited. None of these preceding attempts has appeared to meet the need for an exposition of the structural sequence that is encountered in traversing the nickel-steel nickel-cast-iron range under what might be called ordinary departures from equilibrium. ExperimentaT. Conditions Since the intent has been to establish structures developed under arbitrary conditions, experimental details have perhaps more than usual importance. Three of these conditions should particularly be noticed: (I) the material was cast and not subjected

Jan 1, 1942

By J. T. Eash, N. B. Pilling

As a group, the alloys of iron, nickel and carbon are, in application, one of the most versatile of the ferrous alloy family, and while many investigations have been made of their properties and structure only a few attempts have been made to show the microstructural relation over a wide range of composition. It is neccssary at once to be clear about the kind of structural relation with which we are concerned. The equilibrium diagram provides quantitative data regarding structural make-up and its variation with temperature, but equilibrium structures often are far different from the technologically significant ones. This is particularly true of steels and cast irons, and some of the most important cornponents of their structure may have no place in the diagram of equilibrium. The fugitive phases that result from transFormation are dealt with in a highly detailed and descriptive manner in. the S-curves originated by Bain. The present effort lies in a still different field, which is to portray the relation between sweeping changes in composition and in resultant structure, under controlled but nonequilib-rium conditions of thermal treatment. The Guilletl diagram presented in 1903 was the initial attempt at such a correlation and frequent references to this diagram can be found in the literature even though later work has shown it to require considerable modification. Kase2 published in 1925 a diagram that was based upon observations of furnace-cooled melts: At low carbon contents this diagram agreed fairly well with experience in showing pearlite to exist in alloys containing up to 6 per cent nickel, and completely austenitic steels at 24 to 28 per cent nickel. At high carbon contents, however, irons were indicated as being martensitic at around 2 per cent nickel and austenitic at 12 per cent nickel; these interpretations are open to serious question. Based upon experience with steels and cast iron, Wickenden3 suggested a diagram that agreed fairly well with Kase's in the steel range but which presented a wide departure from it in the higher-carbon, high-nickel regions. In its broad picture, the Wickenden diagram is an approach to "practical" structures. Reference may be made at this point to the efforts of Marsh5 to construct an iron-nickel-carbon equilibrium diagram by the coordination of scattered data, which are described at length in the monograph cited. None of these preceding attempts has appeared to meet the need for an exposition of the structural sequence that is encountered in traversing the nickel-steel nickel-cast-iron range under what might be called ordinary departures from equilibrium. ExperimentaT. Conditions Since the intent has been to establish structures developed under arbitrary conditions, experimental details have perhaps more than usual importance. Three of these conditions should particularly be noticed: (I) the material was cast and not subjected

Jan 1, 1942

By J. B. Morgan

The mechanical behavior of MgCu2 from 20 o to 725°C has been determined by "brittle-ring" tensite-test techniques, axial compression, and bending experiments. Compressive ductility begins at 450°C (0.65 T/Tm) and slowly increases with increasing temperature white the tensile ductility is characterized by an abrupt brittle-ductile transition at 600°C (0.8T/Tm). The compressive strength increases eightfold from room temperature to 400°C with a "normal" decrease as the temperature is further increased. The tensile strength goes through a rather abrupt threefold increase above 600°C with a subsequent decrease at higher temperatures. The slip system is (111)[110] and the twinning system is (111)[112]. At high temperatures MgCu2 is quite rate-sensitive, and dynamic yield points are observed that are extremely orientation-dependent. The high-temperature creep behavior under constant load is characterized by an increasing strain-rate with time. The general characteristics of the mechanical behavior make it possible to classify MgCu2 with those materials in which initial mobile dislocation density and the dislocation velocity-stress dependence are significant in determining mechanical response. Mgcu2 is the C15 prototype of the cubic Laves phase. Its range of homogeneity extends from 32.8 to 35.5 at. pct Mg at 500°C and narrows at lower temperatures. The lattice parameter is reported to vary from 7.02 to 7.05A,1 and the compound is completely ordered to the melting point of 819°C. MgCu2 has a brassy metallic appearance, is extremely brittle, and many of its physical properties are intermediate between those of the constituent elements: the electrical resistivity is 3.5 x 10-6 ohm-cm, Young's modulus is 10x 106 psi, the shear modulus is 6 x l06 psi, and the thermal coefficient of expansion is 18.7 x 10-6 cm per cm per "C from 20" to 250°C. Usually, properties of intermetallic compounds as functions of temperature have been determined by hardness, compression, or impact behavior, and almost all of these experiments have been performed on polycrystalline materials. Tammann and Dahl,2 for instance, determined the onset of ductility in a series of binary intermetallics by ball-hardness measurements and found the onset to range between 0.71 and 0.96 T/T,. Lowrie's3 investigations included some tensile properties, and he found ductility beginning around 0.65 T/Tm for most materials examined. His work did include some data on polycrystalline, nonstoichiometric MgCu2, however. The present work is an attempt to extend the examination of the particular compound MgCu2 in single-crystal form in order to aid the formation of general concepts about mechanical be-

Jan 1, 1965

By James Johnston

Synopsis.-A description of the working of the mills of this company and the metallurgical practice in vogue, by which a remarkably. complex silver ore, averaging 54 oz. of silver per ton (run-of-mine ore), is treated to give a 95.66 per cent. extraction. The main features of the, processes are: The cyanide amalgamation of the high-grade ore. The cyanide treatment of the low-grade ore, after extremely fine grinding and close classification, in a caustic soda solution. The use of a wet desulphurizing process to break up refractory silver minerals. The substitution of aluminum dust for zinc dust as a precipitant. The recovery and shipment of over 13,000,000 oz. of silver in bullion at. 997 to 999 fine since this metallurgy was inaugurated, about 2.5 years ago. On the completion and successful operation of the mill to treat their . high-grade ore,1 the Nipissing Mining Co., under the general management of R. B. Watson, started a series of investigations of the possible treatment of the low-grade ore by the cyanide process, so that they would be in a position to market only silver bullion. These tests were run in July, 1911, on a large scale, by G. H. Clevenger, on an average mixture of Nipissing ore. The results obtained by a partial amalgamation followed by cyanide treatment gave an extraction varying from 90 to 93 per cent. and were sufficiently encouraging to warrant Charles Butters, the company's Consulting Metallurgist, in recommending that the new low-grade ore mill under contemplation should be a cyanide mill, instead of a concentrator. The cost of such a mill, capable of treating 200 tons per day, to obtain a 90 per cent. extraction at a working cost of $3 per ton of ore treated, was estimated at $250,000.

Jan 1, 1914

By A. A. Dor

Out of nine new major iron ore concentrators put in operation during the last three years, or expected to be commissioned in 1968, seven incorporate primary grinding mills and have a total design capacity of 13,150,000 ltpy of pellets, while only two include conventional rod and ball mill grinding circuits for a total design capacity of about 6,100,000 ltpy (Table I). This evolution in the application of primary grinding to hard, fine grained magnetite ores represents an important development in the technology of mineral processing. It has been the outcome of comprehensive testwork in the laboratory and in pilot plants.

Jan 11, 1968

By Juanito C. Fernandez

INTRODUCTION The Philippines is endowed with mineral resources, much of which still remains unexploited. The country's known reserves, at least for the major mineral commodities, have increased every decade since the first major discoveries more than 80 years ago. Mining, therefore, naturally evolved as one of the pioneer industries and has ever since been a major factor in economic development. The Philippines has entered a new era in mineral resources development and management. One significant feature of this era is the degree to which the government is involved with the industry. In recent years, the state has increasingly encouraged the private sector to carry out detailed exploration aided by governmental contributions through extensive geological and geophysical surveys, fundamental researches and even indirect financial assistance in some specific areas. Significant changes in mineral resources development policies were brought about with the promulgation of Presidential Decree 463 or the Mineral Resources Development Decree of 1974. The Decree provides for a more rational system of administration and disposition of mineral lands to promote mineral resource exploration and exploitation. Various forms of incentives are provided. Foreign entities are allowed to participate in development through service contracts with leaseholders or with the government in the case of reserved areas. The thrust in mineral resources development has been focused on the base metals which as envisioned would provide the foundation for sound economic development. In recent years, however, major strides have been made to promote the exploitation of the non-traditionally produced commodities especially the non-metals. Development likewise point to the growing determination of the government and the private sector to expand benefits from mining. This is evident in efforts to promote downstream processing operations and to encourage investments in exploration, exploitation and mineral processing ventures. The integrated mineral resources development plan, therefore, proposes the vertical integration of mining extraction activities with the processing requirements of the metal-based manufacturing industries. While mining activities shall continue to be carved out by the private sector, the government shall influence the industry's direction by establishing legitimate goals to maximize benefits through an integrated approach giving due consideration to environmental protection and resource needs of future generations. STATUS OF MINERAL RESOURCES DEVELOPMENT Extent of Exploration Application of modem exploration tools and concepts complemented by intense infusion of foreign technology and rapid development of indigenous expertise have enabled the government jointly with the private sector to geologically explore vast grounds and to expand the country's known mineral resources. Approximately 93% of the country's total land area of 30 million hectares have been geologically mapped on at least 1:250,000 scale. Of the 93% total coverage, roughly 37.54% or 11.07 million hectares have been done on scales of 1:10,000 to 1:50,000 as shown in Figure I. Only 3.07% of the total coverage have been surveyed in detail. Land gravity surveys have been undertaken on over 45% of the total, while some 77,300 line km. of aeromagnetic surveys have been flown over 110,000 sq. km. of land area. Processing of data is almost complete. Total magnetic intensity and IGRF-corrected maps are available. Geological interpretation utilizing Landsat MSS imagery and low altitude aerial photography augmented by ground truthing have been undertaken in several large areas with very encouraging results. Beach and offshore mineral surveys were initiated in 1977 and have covered substantial areas in northwest and southeast Luzon and northeastern Mindanao. Highly promising areas for detrital magnetite, chromite, gold and some heavy minerals including ilmenite and titanium have been identified. In the petroleum sector, two offshore oilfields are currently producing from Miocene limestone reefs in Northwestern Palawan. Another field from the same area will be on stream in mid-1982.

Jan 1, 1982

By R. B. Hoy, Stanley J. LeFond, K. Reckling

World production of natural diamonds prob¬ably exceeds 50,000,000 carats a year. The Republic of Zaire is the leading producer, with an output which is primarily industrial rather than gem grade. The USSR ranks second, and the Republic of South Africa third. Diamonds are also mined in South-West Africa, Angola, Ghana, Sierra Leone, and other African coun¬tries. In the western hemisphere, Brazil and Venezuela are the principal producers (Fig. 1). A very small output of diamonds is mined today in India, which was the first source of commercial production. In the U.S., efforts at commercial diamond mining have been con¬fined to a small area near Murfreesboro, Ark. The first diamond was found in a kimberlite pipe there in 1906. Small-scale trial mining has not, however, proved economical. Since diamonds were first discovered over 2000 years ago, only about 130 tons have been mined. In order to obtain 1 g (5 carats) of diamonds, it is necessary to remove and process approximately 25 tons of rock. Recovering this small percentage involves a combination of highly developed techniques in mining, quarrying, and earth-moving, and extremely sophisticated recovery processes. End Uses Diamonds are used for two unrelated end uses; gem diamonds are jewels of great beauty while industrial diamonds are essential ma¬terials of modern industry. Although imitation stones are substituted for the gem diamond, none of these matches its properties sufficiently well to offer real competition. Synthetic indus¬trial diamonds are now of a quality that per¬mits wide substitution in the fine-grained sizes. Gem Diamonds A diamond is a natural prism. It has the ability to bounce light rays (reflection), to bend them (refraction), and to break them into all colors of the rainbow (dispersion). This ability to "modify" light gives the diamond three characteristics for providing beauty. First is brilliance, the reflection of light back to the eye. Second is fire, dispersion of light into the colors of the spectrum. Third is scintillation, the "twinkling" that occurs when the diamond is moved (Bauer, 1969). The skill of the diamond cutter is required to unlock the brilliant, fiery beauty of a gem dia¬mond (Fisher, 1966). Diamond-cutting skills have gradually developed over the centuries. The first cutters, in India, learned how to grind one rough diamond against another to remove their "skins" and to give them various shapes. This revealed some fire and beauty, but little compared to that of the diamonds that are cut today. About 1475, a Flemish cutter named Van Gerquem discovered that diamond dust on an iron wheel would polish facets on a diamond to provide more brilliance and fire. Cutters continued to experiment with facets, and shortly before 1700 a Venetian cutter named Peruzzi developed the 58-facet brilliant cut. With the development of the science of optics, cutters have learned more about the behavior of light within the diamond. Early in the 20th century, they learned how to angle Peruzzi's

Jan 1, 1975

Ore deposits of commercial grade are local concentrations of great rarity when considered in relation to the area of unmineralized land surfaces, and they must therefore be considered as the products of exceptional and complex conditions. The data collected from a great number of individual deposits are sufficient to permit certain broad generalizations in regard to the conditions favorable to ore deposition which even numerous exceptions do not invalidate. The broadest general relation of ore deposits is with intrusive rocks, and while there are notable exceptions, the great majority of ore deposits have a visible or closely inferred connection with intrusive rock masses. Conditions that permit the dissipation of the ore-bearing vehicles do not permit the concentration of metals in deposits; the prime factor to consider in this connection is that structural conditions must be such as tend to concentrate and not to dissipate the ore-bearing solutions. The disadvantage of extrusive rocks is at once apparent; any metals the magma may have contained are dissipated at the surface and are lost; with the exception of tiny vugs and cracks in quickly cooled flows, no concentrations of metals are known in extrusive rocks, and the lack of confinement and quick cooling apparently do not permit extrusives to exert mineralizing effect upon the rocks with which they come in contact. The close mineralogical similarity between extrusives and intrusives, and the great difference in mineralizing power is a proof of the ease with which magmas part with their metallic content, and of the mobility of the ore-bearing vehicles in comparison with the parent magma.

Jan 1, 1932

By Clarence Thom

This chapter presents, in summarized form, standard procedures for making separations of minerals from their ores by the froth flotation process to produce marketable concentrates. These are typical mineral separations which are being made commercially with the reagents and conditions generally used in the mining industry. Typical separations are presented for 17 metallic and 11 nonmetallic ores. The review of each includes a brief description of the mineral and the particular problem presented, general market specifications for its concentrates, an outline of treatment method, and kinds and quantities of reagents usually employed. This chapter does not include de- tails about ore preparation (crushing, grinding, and classification), elements of ore and pulp transportation (conveying and pumping), or concentrate preparation for market (thickening, filtering, and drying). In each presentation it is assumed, if not detailed further, that the ore is ground to the economical point of liberation of the minerals to be separated. Specific information, such as ratio of concentration and recovery, that depends upon the grade of ore being treated is considered beyond the scope of this chapter. Effective flotation separations that produce marketable concentrates may produce widely varying results in terms of percent recovery and still be economically profitable operations. Details of plant practice on specific ores are presented in Chapters 16 and 17. In this chapter the chemical names of the reagents are given. The extent to which different reagents are used in flotation plants in the U. S. is presented in Chapter 4. A compilation of the various flotation reagents, their trade names, manufacturers, and use has been prepared by H. T. Spedden. ANTIMONY The principal ore mineral of antimony, stibnite (Sb2 S3), is generally found in the U. S. in ore bodies in association with other valuable minerals such as galena (Pbs), sphalerite (ZnS), chalcopyrite (CuFeS2), or tetrahedrite (3Cu2 S – Sb2 S3), The sulfo-salt minerals of antimony, such as tetrahedrite or pyrargyrite, are often associated with high silver values, so that the presence of antimony may indicate economic importance even though the actual antimony content is low. Antimony is also significant to the mineral economy because of its occurrence in some ores where lead, gold, and silver are the

Jan 1, 1962

Jan 1, 1924

By S. R. Gilbert, B. W. Burdett, L. B. Hales

A brief review of grinding control systems is given with a review of the most popularly reported control loops. The trend toward more sophisticated control systems in terms of control strategies and control equipment is discussed, and the reasons for the popularity of distributed control equipment are outlined. The evolution of the interface between the operator and the process and its importance in plant control is described. Finally, the authors' view is given as to the future of grinding control.

Jan 1, 1984

By A. A. Janke, G. J. Vogel, W. M. Swift

The combustion of fossil fuels in a fluidized bed of calcined limestone particles is a potentially efficient and economically attractive process for the generation of steam for electric power production and other uses. The process results in greatly reduced emissions of both sulfur oxide and nitrogen oxide pollutants. Development work, evaluations, and design studies are being carried out by various organizations under contract with the Department of Interior (Office of Coal Research, OCR) and with the U.S. Environmental Protection Agency, (EPA). The Atomic Energy Commission's Argonne National Laboratory is one of the principal participants in the development program under interagency agreements with EPA and OCR. The principal reasons for developing fluidized-bed combustion, its advantages and disadvantages over conventional combustion methods, and some of the potential applications of the process are covered in this paper. The participants in the multiorganizational program, the sponsoring agencies, the general status of development of the overall project, and the chief program areas that still require resolution are discussed. The main features of the program of work at Argonne National Laboratory and the results achieved so far are also included.

Jan 1, 1976

By David W. Wisecarver, James F. Reynolds

INTRODUCTION The Department of Energy is cooperating with Snowmass Coal Company near Carbondale, Colorado to introduce the longwall mining method in moderate to steeply pitching coal seams in the United States. This venture is part of a coal mining research program directed toward development, trial, and analysis of mining technique8 to improve production and recovery in the more difficult mining conditions such as thick, multiple, and steeply pitchly seams found in the Western U.S. The project at Snowmass is the first attempt in the United States to operate a longwall in a steep coal seam. Plans are to mine three adjacent, successively downslope panels in the eight foot thick seam which varies in pitch from 27 to 33 degrees. During this work, researchers and mine engineers are expected to obtain answers to many engineering questions relative to panel design and development, selection of face equipment and beet operating techniques and procedures. They are also committed to obtaining hard data on costs, recovery, production, safety, and behavior of underground mine structure as the three panels are mined. This information is essential to future mine engineering and profitable mining of pitching Western coal reserves. Development of the first trial panel was begun in 1979 and completed in June 1981. The longwall mining equipment was then installed in the starting room and retreat mining begun on August 11, 1981. Project duration is expected to be about five years during which over tm million tons of coal will be produced. TRAINING The longwall mining method is new to Snowmass. For years the mine produced coal by room and pillar methods using conventional techniques to mine upslope rooms and Alpine F6A miners to cut entries and rooms on strike. Miners were experienced in room and - pillar mining from other mines. News of the longwall demonstration was received enthusiastically by Snowmass miners. Employee interest in the project was 100%. However, there was minimal longwall experience on site. In fact, most of the work force had not even seen a longwall. Mine and company management were well aware of the immediate need to develop trained longwall face mining crews and maintenance people qualified to work on longwall equipment and also expertise in longwall planning, equipment selection, power distribution design, ventilation requirements and panel development. The first approach to answer this huge deficiency in longwall mining experience was obviously training. Hence a training program directed toward those mining specifics most urgent to the beginning mining phases was initiated in mid-1980. Classroom lectures and hands on training, using instructors from equipment suppliers and available company longwall expertise, was conducted in longwall subjects to include face mining procedures, panel development, operation of equipment, equipment assembly and maintenance, electrical circuitry and controls, ventilation, move of longwall equipment, and safety procedures. At the same time, responsible engineers and foremen were sent on a tour of European pitching longwalls to see first hand how other mines working under similar seam conditions conducted their operations. Development techniques, types of equipment, methods for transport of men and materials, and ground control techniques were discussed with engineers, foremen and officials at each mine. This look at European longwall mining operations gave Snowmass good insight into the unique problems associated with longwall mining on 30' pitch. Mining considerations such as face conveyor/ support system slippage downslope, panel development, maintenance, safety considerations, manpower requirements, and haulage methods were covered with European experts

Jan 1, 1982

By Virgil R. D. Kirkham

NoRth America has for many years led the world in phosphate production, but with development of African deposits and their marketing conditions with respect to European countries, this leadership will shortly pass to Africa. Algeria, Egypt, Tunis, and Morocco have large phosphate reserves and a correspondingly large production because of easy mining and a ready European market, which was developed during the war. An increase in home consumption is destined to develop for the eastern American fields, and the countries of the Pacific will provide a market for the western producers. New processes indicate a decrease in fertilizer costs, which will encourage a more widespread domestic use and assure better marketing conditions. The African deposits, although benefited by a water haul, have the disadvantage of being isolated from a source of acid so that the crude rock is shipped from Africa to its destination, whereas in the United States the chief product shipped is acidulated rock or various types of superphosphatic fertilizers, The principal types of phosphate deposits used in the manufacture of fertilizers are guanos, apatite, phosphatic marl, phosphatic limestone, phosphatic shale, and phosphate rock which is also known as phosphorite. Some of these deposits are found on each of the continents; Table 1 gives their occurrence, age, location, character, extent, etc. Most of the information found in this table represents a compilation of information published elsewhere in a different form and widely scattered.

Jan 1, 1925

By B. Egeberg, H. B. Smith

Britannia metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375" I?., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later. The approximate analysis of the metal we investigated was 91 Sn, 7 Sb, 2 Cu, and the molten metal was bottom-poured into an iron mold yielding an ingot 7 3/4 in. wide by 11 in. long and % in. thick, the casting temperature being 800" F. The ingot was cold-rolled to a sheet 0.032 in. thick, sufficiently large samples for experimental purposes being cut from the sheet at intermediate stages. The samples were all tested for hardness with scleroscope and Brine11 machine, then heated to 212" F. for 30 min., and again tested after cooling to room temperature. The same samples were heated successively at 300°, 400°, and 440" F., followed

Jan 1, 1929

By H. B. Smith, B. Egeberg

Britannia metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375" I?., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later. The approximate analysis of the metal we investigated was 91 Sn, 7 Sb, 2 Cu, and the molten metal was bottom-poured into an iron mold yielding an ingot 7 3/4 in. wide by 11 in. long and % in. thick, the casting temperature being 800" F. The ingot was cold-rolled to a sheet 0.032 in. thick, sufficiently large samples for experimental purposes being cut from the sheet at intermediate stages. The samples were all tested for hardness with scleroscope and Brine11 machine, then heated to 212" F. for 30 min., and again tested after cooling to room temperature. The same samples were heated successively at 300°, 400°, and 440" F., followed

Jan 1, 1929

By Chas. Y. Clayton, Francis B. Foley, W. E. Remmers

DuRing the summer of 1919, the late Dr. Henry M. Howe, then Chairman of the Division of Engineering of the National Research Council, organized a committee to obtain a better insight into the behavior of carbon steels under the influence of various treatments by a proper control of the time and temperature factors. During part of 1919 and 1920, work in connection with this investigation was carried on at Dr. Howe's laboratory at Bedford Hills, N. Y. During 1921 there was an enforced hiatus in the work, occasioned by the illness which resulted in Dr. Howe's death in 1922. At that time one of the present authors compiled the results of the work which had been done and this was published in 1923.' Following the publication of this work, it seemed desirable to carry on in the same manner an investigation of steel of C 0.75 per cent., which steel had not been as fully treated as had the other steels of C 0.34 and 0.52 per cent., used in the published work. Furthermore, certain unusual results have been obtained in the treatment of C 0.52 per cent. steel by quenching and drawing, and repetition of this part of the work seemed advisable. This has been done during the past year at the School of Mines and Metallurgy of the University of Missouri at Rolla, Mo., by a cooperative undertaking of the School and the Bureau of Mines, working in conjunction with the Committee on Heat Treatment of Carbon Steels of the National Research Council. The present paper is a report of the results obtained in this work.

Jan 1, 1926

By Marcus A. Grossmann

This paper offers for consideration certain somewhat radical modifications in the iron-carbon diagram, these modifications being the result of the presence of notable amounts of alloying elements. When only small amounts of alloys are present, the standard iron-carbon diagram (Fig. 1) can be used with but insignificant changes; when larger amounts of alloys are present, however, it assumes a distinctly altered appearance. No comment is offered for the present except to call attention to the delta area, A4BM, which represents a region of mixtures of austenite and delta iron, just as area A3SP represents mixtures of austenite and alpha iron. Absence of Carbon We may turn at once to the effect of the presence of alloys. It has been found that in the complete absence of carbon, the gamma change will sometimes disappear entirely when sufficient alloying element is

Jan 1, 1927