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By A. L. Foell

The development of the modern blast furnace began more than one hundred years ago, with the abandonment of the small hillside furnaces. Its development, especially during the past 50 years, has been accomplished through a rapid succession of enlargements and improvements. The remarkable growth in furnace output during this period is a tribute to the engineers and operators who have constantly endeavored to build larger and more efficient blast furnaces. The blast-furnace operators and their mechanical and electrical maintenance staffs have originated most of the furnace improvements as a result of their practical operating experience. Furnace Lines About 50 years ago furnaces consisted of hearths about 11 ft. in diameter, which merged into rather high flat boshes, with no cylindrical section between the bosh and inwall and no cylindrical section at the stock line. Since then the lines of the furnace invariably have included a cylindrical section above the bosh and a cylindrical section at the stock line. Notable increases have been made in both hearth diameters and furnace heights. During the past 10 years hearth diameters in new and replaced furnace stacks have rather consistently fallen within the range of 25 to 28 ft. while their heights have varied be- tween 100 and 106 ft. The lines of most large furnaces using Mesabi ores have followed a fairly uniform pattern (Fig. I) in which the principal dimensions for 25-ft. hearth furnaces are as follows: Hearth diameter............... 25 it. o in. Height of bosh................. 10 ft. o in. Bosh angle.................... 81 1/2º Diameter top of bosh........... 28 ft. 0 in. Inwall batter per foot........... 15/16 Stock-line diameter............. 19 ft. 6 in. Large-bell diameter............. 14ft. 6 in. Height from iron notch to top ring casting...................... 100 ft. o in. In determining the size of a new furnace for the replacement of an existing stack or for an addition to productive capacity, it is not possible to formulate a procedure that can always be followed. Local conditions, requirements as to capacity, available raw materials and prospects for future expansion dictate the size of such proposed improvements or additions. However, where the immediate requirements indicate a stack or furnace of a certain productive capacity, and the future prospects indicate that more capacity can be utilized, it is well to consider building the furnace ior the ultimate capacity rather than to install a smaller hearth with provision for future enlargement. The decision to build the larger hearth and stack for the ultimate capacity probably will require no greater initial investment, since the saving in the cost of brickwork will about offset the greater cost of the hearth jacket, tuyere breast and bosh bands. In the meantime. the furnace of larger hearth dimensions, while operating below its ultimate output, will yield a better coke rate and

Jan 1, 1943

By David A. Rice

This note describes a simple, rapid technique for measuring the apparent volume and density of individual bits of porous materials such as iron ore pellets or pieces of coke. The method consists of determining the weight recorded on a balance when a particle is depressed below the surface of mercury, and calculating the apparent volume from the known density of mercury. The apparent density is calculated after weighing the particle in air. The method is particularly well suited for applications where a great number of determinations are to be made. An additional benefit is the minimal handling of the mercury. In any event, the usual recommended safety precautions should be adhered to.

Jan 1, 1982

By Bryan Denby

The curvilinear nature of shear strength envelopes for rock discontinuities may be simply and precisely represented by a power curve. The development of shear strength criteria applicable to rock discontinuities is reviewed and related to a theoretical basis for curvilinearity. An approach is reported to enable the quantification of the two power curve indices using a nomogram based on empirical studies. Using a knowledge of discontinuity basic friction angle and peak dilation angle the relevant indices ranges may be predicted for mine slope studies.

Jan 1, 1984

By W. T. Lankford, Edward Saibel

During the course of an investigation of the plastic flow of aluminum aircraft sheet under combined loads, several problems arose in which analyses of the conditions leading to unstable plastic flow were needed. In order to provide these analyses, and in the hope of attaining a better understanding of the general problem of unstable plastic flow, the present study was undertaken. It is well known that unstable plastic flow is associated with a form of mechanical instabi!ity frequently observed during the plastic deformation of ductile metals. This instability is characterized by the fact that, at its onset, plastic straining mill proceed at a constant magnitude of the externally applied forces. It is further typical that the resulting unstable flow is generally accompanied by the formation of a neck, a local bulging, or some other form of heterogcneous deformation. Perhaps the most familiar example of unstable plastic flow to the metallurgist is the formation of the neck in the ordinary tension test. It is well known that in this test most metals exhibit a maximum in the externally applied load, followed by the process commonly referred to as "necking down." Instability in the simple tension test has been frequently discussed and numerous investigators1'2'3'12 have derived the criterion for instability in terms of a critical rate of strain hardening. It is the purpose of the present study to extend the criterion for unstable flow to the more general case where the body undergoing flow is subjected to combined loads. It is hoped that the problems considered will provide a more consistent picture of the general features of this important form of mechanical instability. The most practical implications of instability in plastic flow arise in connection with sheet metal forming operations. In the formation of a great many sheet metal parts, the deformations are produced primarily by stretching. If the conditions which lead to unstable flow are fulfilled in such a formation, and if the resultant instability leads to a pronounced localization of flow, then the useful limit of ductility of the material will have been reached. It i; also essential that the effects of instability be taken into consideration in any study of the plastic flow and rupture of metals under combined stresses. In general, when unstable plastic flow is initiated, straining becomes localized, the geometry of the test splecimen changes, and the state of stress in that portion of the specimen undergoing plastic flow is no longer under external control. In many past studies of the effects of combinetl Metals On flow and rupture) account has not been taken of the fact that, although a given test may be started under constant

Jan 1, 1947

By Edward Saibel, W. T. Lankford

During the course of an investigation of the plastic flow of aluminum aircraft sheet under combined loads, several problems arose in which analyses of the conditions leading to unstable plastic flow were needed. In order to provide these analyses, and in the hope of attaining a better understanding of the general problem of unstable plastic flow, the present study was undertaken. It is well known that unstable plastic flow is associated with a form of mechanical instabi!ity frequently observed during the plastic deformation of ductile metals. This instability is characterized by the fact that, at its onset, plastic straining mill proceed at a constant magnitude of the externally applied forces. It is further typical that the resulting unstable flow is generally accompanied by the formation of a neck, a local bulging, or some other form of heterogcneous deformation. Perhaps the most familiar example of unstable plastic flow to the metallurgist is the formation of the neck in the ordinary tension test. It is well known that in this test most metals exhibit a maximum in the externally applied load, followed by the process commonly referred to as "necking down." Instability in the simple tension test has been frequently discussed and numerous investigators1'2'3'12 have derived the criterion for instability in terms of a critical rate of strain hardening. It is the purpose of the present study to extend the criterion for unstable flow to the more general case where the body undergoing flow is subjected to combined loads. It is hoped that the problems considered will provide a more consistent picture of the general features of this important form of mechanical instability. The most practical implications of instability in plastic flow arise in connection with sheet metal forming operations. In the formation of a great many sheet metal parts, the deformations are produced primarily by stretching. If the conditions which lead to unstable flow are fulfilled in such a formation, and if the resultant instability leads to a pronounced localization of flow, then the useful limit of ductility of the material will have been reached. It i; also essential that the effects of instability be taken into consideration in any study of the plastic flow and rupture of metals under combined stresses. In general, when unstable plastic flow is initiated, straining becomes localized, the geometry of the test splecimen changes, and the state of stress in that portion of the specimen undergoing plastic flow is no longer under external control. In many past studies of the effects of combinetl Metals On flow and rupture) account has not been taken of the fact that, although a given test may be started under constant

Jan 1, 1947

By John C. Smock

While I was engaged in the preparation of a catalogue or list of mineral localities of the United States, east of the one hundredth meridian, for the U. S. Geological Survey, the thought occurred to me that an arrangement or classification of the iron-ore districts of the eastern part of our country according to their geological horizons would be an interesting topic for a paper, and would furnish a basis upon which to arrange many facts brought out by the constant development of our iron-mining districts. Our text-books of mineralogy, geology, and ore-deposits describe the iron-ores and the

Jan 1, 1884

By A. H. Geisler, J. H. Keeler

Preferred orientations in unalloyed zirconium were determined by the Geiger-counter spectrometer X-ray diffraction technique. With increasing P-annealing temperature the following textures were obtained: l—a retained a-annealing texture, 2—additional orientations predictable from the a-p (Burgers) relationship, and 3—a texture derived from a cube texture in the p phase. Earlier work on cold-worked and a-annealed zirconium was reappraised to show a quantitative dependence of rotations on temperature and to identify spurious areas of some of the pole figures. IN a previous paper,' the preferred orientations of high purity zirconium sheet were described for cold-rolled and annealed samples. Annealing temperatures up to 900°C, which is slightly above the allotropic transformation temperature, were explored. Of interest was the observation that the orientation of the hexagonal-close-packed material after annealing in the temperature range of the stable body-centered-cubic phase was similar to that of the material which had been annealed in the a temperature region, although a change in texture would be expected because of the many new orientations based on an orientation relationship between the two forms of zirconium. The reversion to an original orientation after an allotropic transformation cycle is not unusual. It has been found for titanium,"* for thallium," and for cobaltB among the hexagonal metals. Burgers found in his original work7 that, when zirconium was cooled through the allotropic transformation and then reheated, the body-centered-cubic phase reverted to the original orientation. Additional experimental work has been carried out to further explore the textures of zirconium after annealing in the temperature range above the allotropic transformation. In addition, a reappraisal was made of the earlier results for zirconium' in light of recent work on titanium4 which has shown that the texture type depends quantitatively on the temperature of annealing and that spurious areas may be encountered in the pole figures of hexagonal metals determined by the X-ray spectrogoniometer technique of analysis. Experimental Procedure Crystal-bar zirconium prepared by the iodide process was the material used in this investigation. The major impurity was hafnium which was less than 0.3 pct. The composition obtained by spectro-graphic analysis is given in Table I. Cold-rolled specimens were prepared from crystal bar by a series of reductions of approximately 0.010 in. until the sheet reached a thickness of 0.010 in., after which it was cold rolled to 0.001 in. thickness between sheets of alloy steel. The total cold reduction amounted to about 99.8 pct. Specimens were annealed for % hr at 1000" to 1100" to 1200°C or 1 hr at 1400°C in an evacuated Vycor or quartz tube. The transmission pole figures were obtained by

Jan 1, 1956

By Charles F. Johnson

A pulse technique is described for the measurement of bar velocity. A low frequency sine wave pulse is used which allows the wave-length to become much larger than the lateral dimensions of the test specimen. The low frequency pulse method has been tested and compared with the resonant frequency method and the results show that both methods give, on the average, equivalent velocities.

Jan 1, 1971

By S. E. Bretherton

Mr. AllaW Gibb, of Mount Perry, Queensland, Australia, in an interesting and instructive paper,* describes fully the great difficulties metallurgists encounter in seeking to produce marketable copper by smelting refractory ores containing arsenic, antimony and bismuth. After reading this description, I prepared a paper for the Institute, which was, however, through a misunderstanding on my part, published in the San Francisco Mining and S'cie~ztiJic Press of April 4, 1903, after its acceptance by the Council, and without credit to the Institute. Consequently, it cannot be reprinted for the Transactions of the Institute; and I can only here summarize its contents and conclusions, referring the reader to the article above named for further particulars. In that article I omitted the col~sideration of bismuth, which we do not encounter in our smelting at Val Verde, and added lead and zinc, which Mr. Gibb had not discussed; and I undertook to shorn, by the record of a year's practice of the Val Verde Copper Co., Arizona, that copper-ores containing arsenic, antimony, lead and zinc may be successfully smelted, without preliminary roasting, in an ordinary blast-furnace with hotblast, making a normal slag, such as one would aim to make under ordinary conditions with cold-blast, so as to produce a marketable matte, containing not less than 45 per cent. of copper, free from arsenic and antimony, and below the limit in lead and zinc penalized by the refineries.

Jan 1, 1904

By Lawrence H. Van Vlack

DISCUSSION, H. L. Burghoff presiding C. S. Smith (University of Chicago, Chicago)—The author is to be congratulated on his valuable contribution to the extremely meager absolute data on interface energies in metallic systems. It is interesting to note that the ratio between a and r iron boundary energies is approximately the same in the quaternary alloy with silicon, carbon, and sulphur as in the binary Cu-Fe alloy. A value for the copper grain boundary energy can be obtained from the author's data, Tables IV and VI, by utilizing the energy ratios of the following pairs of interfaces: copper-sulphide/copper, copper y iron, y iron/y iron, y iron/ copper, and copper/copper. This gives a value of 595 erg per sq cm for the free energy of the copper grain boundary. Despite this circuitous route and the assumption that the y iron boundary is identical in alloys with and without sulphur and does not change between 1105" and 100O°C, this figure is in remarkably close agreement with other values of the copper boundary energy, obtained by equilibration against lead and against the free copper surface. It therefore appears either that impurities do not greatly affect the grain boundary energies or that boundaries in even nominally pure metals are already sufficiently contaminated so that further change has little effect.

Jan 1, 1952

By Roy R. Weil, John A. Dziubek

This paper discusses the use of computer modeling, data manipulation, and mapping of three multi-seam coal properties in the Appalachian coal basin. Each case history represents a slightly different application of computer usage for estimation of reserves and planning surface mine sequencing. This practical use of computers demonstrates the suitability of data processing for normal evaluation of coal properties.

Jan 1, 1983

During the year 1915 the Committee received 161 manuscripts, which were treated as follows: 3 accepted for. New York Meeting (110th) . 64 accepted for San Francisco Meeting (111th) 49 accepted for New York Meeting (112th) 3 accepted for Arizona Meeting (113th) 29 rejected 4 returned to authors for revision and not yet accepted 9 in committee. 161 Every paper which was presented at the San Francisco Meeting was published in advance in the Bulletin with one exception. The work of the Committee has been systematized and. the Executive Committee of the Committee on Papers and Publications has given prompt attention to all manuscripts, with the result that every paper received by the Committee on Papers and Publications is in the hands of the, printer within 30 days thereafter, unless delays occur owing to questions as to acceptability, in obtaining from the author permission for revision, or other like causes.

Jan 2, 1916

As desirable as it may be to a geologist to have maximum detail in any geological report, the task of doing so for an area as vast as British Columbia within six average size magazine pages is clearly impossible. As a result, it has been necessary to draw a fairly broad picture of the geology on the following pages, but it is one which should be adequate to give the reader a concept of what rock is where in the Province. In preparing this horseback ride over the strata of the Province, much reliance has been placed on various reports appearing in trade and Canadian Government journals. Of these, one in particular stands out. Entitled "The Cordilleran Region", this report has been authored in three parts by H. S. Bostock, R. Mulligan and R. J. W. Douglas, respectively, and is included as a major chapter of the book Geology and Economic Minerals of Canada. Published in 1957 by the Department of Mines and Technical Surveys, the book has provided the extensive quotes, taken from each of the three authors, which appear on the following pages.

Jan 12, 1963

By Alfredo O. Del Campo

Copper concentrate smelting has been the subject of significant improvements during the last three decades. Several new processes are being successfully applied at industrial scale, and probably no new copper smelter will be built with the old-fashioned reverberatory furnace. However, because of financial reasons, the existing reverberatory furnaces, which smelt a significant part of the copper produced worldwide, are likely to last at least another decade. Some improvements have been introduced in reverberatory smelting practice, the best known being the use of oxyfuel burners. However, efforts to optimize the reverberatory furnace operation through automatic control have not been reported. The complex and semi-continuous nature of the process makes it dificult to find a suitable strategy for its automatic control. Many factors, like fuel economy, productivity, boiler capacity, refractory wear, converter slag return, copper losses in discard slag, etc. are interconnected. The chosen control strategy should take into account all these factors to achieve good economic results. A detailed discussion of these problems is presented.

Jan 1, 1984

By M. E. Gershon

The development of long-term plans and schedules for strip mines now faces many companies, especially those developing large properties in the West. The rule of mining the lowest strip ratios first, while delaying equipment acquisitions and recouping investment the fastest, sometimes creates the situation where stripping ratios are too high in the latter years of mining operations. A program concept taking life of mine return on investment into account is developed in this paper to optimize mine scheduling and equipment acquisition. In addition, quality considerations (heat content, ash, sulfur, and washability) can be considered by including the appropriate blending constraints to meet contract requirements.

Jan 1, 1984

By C. E. Mendenhall

FOR the purpose in hand, pyrometry may be taken to include all temperature measurements from, say, 200° C. to the highest attainable, especially when considered from the technical or applied side. It will be convenient first to consider the entire content of a course of study grouped under the headings of the various methods of measurement, which are quite distinct in principle and involve different equipment. Brief suggestions will be given under each heading, and the summary will be followed by comments on the purpose of such a course and methods of conducting it. 1. Expansion and pressure methods: mercury thermometers (glass and quartz), liquid, gas, and vapor-pressure thermometers, especially recording instruments. Especial attention should be given to the limitations of these methods, which, particularly in high-temperature mercury thermometry, are often overlooked. Range approximately to 700° C. 2. Resistance thermometers: both bridge and potentiometer methods, of indicating and recording. Calibration; lead compensation; design of thermometers for special purposes. Range to 1200° C. 3. Thermoelectric pyrometers: potentiometer and deflection methods indicating and recording. Calibration, leakage errors, contamination errors, base and noble couples. Range to 1500° C. 4. Total radiation methods: thermoelectric, resistance, and expansion indicators, mirror and lens collectors, calibration, permanence of characteristics, absorption errors. Range, to highest attainable temperatures. Methods of producing perfect radiators-true, and virtual or "black body" temperatures. 5. Partial radiation methods: absorption and spectroscopic methods of getting partial radiation, various comparison sources, polarization, electric, sector, and absorption methods of controlling intensity (Morse, Lummer, and Wanner types). Calibration, permanence of calibration, absorption errors. Methods of producing perfect radiators -improvised methods; true, and virtual or black-body temperatures.

Jan 9, 1919

By Clifford J. Lewis, James L. Drobnick

Vexed with competition from relatively high grade foreign orebodies, perplexed by marginal, low grade domestic orebodies, and ironically faced with the fact that practically every metal needed in our economy is available domestically in ample quantity in the ground, our mining industry awaits the advancements in beneficiation technology that will bridge the gap between the ground and the market place for our presently unexploited mineral reserves. Among the vast number of research and development projects underway in the metals mining industry, there are a few chemical techniques in metals winning that, with further development or wider application, could have a profound effect on the industry. These techniques include the Imperial Smelting and Refining Process for complex lead-zinc ores, chlorination and fused salt procedures, the liquid ion exchange process, and the field of non-aqueous leaching. IMPERIAL SMELTING PROCESS The Imperial Smelting and Refining Process is of interest because it offers a possible economic route for the processing of complex zinc-lead-copper ores. The process represents the outcome of the combined efforts of metallurgists and engineers of Imperial Smelting Corporation. Ltd., the United Kingdom Subsidiary of the Consolidated Zinc Corporation, Ltd., and is the subject of patents throughout the world. This process is essentially the employment of the blast furnace for the production of zinc. Zinc has always resisted blast furnace technology, primarily because of the difficulty of condensing zinc vapor from dilute gases. The Imperial Smelting Process employs a blast furnace working at ordinary pressures and in a system which is able to con- dense a blast furnace gas of a very low zinc content.

Jan 11, 1963

By Joel J. Lloyd

The storage and retrieval of geological information is represented by a "Babel" of systems. If the energy and expense that is being expended is to be fully exploited by the earth science community, a common language and common practise is required. Interfacing, applicable in the crossover of scientific disciplines and of polyglot data collections, is neither practical nor economic in the handling of English language information. Whether a single input/output center or a locus of interlocking subcenters is established, is irrelevant. The capture of fugitive information and recapture of lost data is paramount. Existing national committees and international commissions are cognizant of the problem and are engaged with it. The time required to reach agreement may merely complicate the problem. It may prove necessary for a group of individuals to face up to the situation and take the indicated action -- facing the criticism that will probably fall on their heads. The cost of rectifying immediate mistakes may be far less than the delayed execution of a long studied plan. System designs are considered in terms of input elements and output products, various mechanical operating modes are presented, and the economics of organization and maintenance are discussed.

Jan 1, 1969

By James M. Schopf

Coal petrology is the study of the lithologic composition and texture of coal and includes megascopic as well as microscopic differentiation. Coal petrography is a quantitative study, principally (but not exclusively) microscopical in nature. The distinction between coal petrologic and coal petrographic studies usually is not important, but it is important to recognize that these studies differ materially from other types of petrology that deal primarily with minerals. The petrologic entities of coal are less clearly distinguished than most minerals and the basis of distinction is not always clearly expressed. The relation of coal petrology to geologic, mining, and technologic problems is most evident when results of coal petrologic studies can be stated quantitatively. The chemical and physical composition of coal and the determination of its quality and properties are continuing problems. The source of these problems lies in the heterogeneity of coal and in its almost complete insolubility in ordinary solvents at normal temperatures.

Jun 1, 1956

By D. W. Jessup

ONLY during the past few years, have the old-fashioned methods for treating ores and byproducts progressed to any marked degree. The advent of multiple-hearth roasting, blast roasting, the baghouse, and the Cottrell plant indicate this change. It is the ability to roast and smelt sulfide ores and concentrates that gave this later advance. Further investigations that will solve the problem of efficient handling of flotation concentrates and their attendant ills are of the utmost importance. With future developments, the metallurgist will be able to smelt more economically and to treat still more refractory ores, making the early methods appear small by comparison. GROWTH OF SMELTING Well within the memory of pioneer smeltermen, the ore was charged directly into the blast furnace as it came from the mine;, only the richer, ores were smelted, the lower grade and sulfide ores were undesirable. Matte was, at first, thrown away and only two products) were desired-slag and lead bullion. Scores of the early smelting companies failed because of improper reduction of ores, high costs, short- furnace campaigns, inability to treat sulfide ores, and ores containing-zinc. With the failure of weaker companies, consolidation eliminated many others, until today the field is dominated by a comparatively few organizations, each strong financially. Formerly, a few thousand dollars would erect a small plant, whereas the modern smelter costs over a million dollars. Ore and products to which formerly no attention was paid are now treated with comparative ease and at a good profit. Mechanical improvements have modernized smelting, furnace tonnages show an increase, and metal recoveries have made enormous strides. Even though costs have decreased, they have not dropped in proportion to the improvements, because of the higher wages, greater costs of fluxes and coke, more undesirable ores smelted, etc.

Jan 8, 1925