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By E. J. Yoder, N. B. Aughenbaugh, R. B. Johnson

Mineral aggregates experience degradation during field and laboratory compaction. Reduction in the aggregate size is accomplished by abrasion of the particle edges and fracturing of individual pieces which have become overstressed. Little is known of the factors that govern the amount of breakdown experienced for a given situation. A field study was made of the factors affecting aggregate breakdown under compaction using three carbonate aggregates of different physical properties. The preliminary results indicate that rock type, compactive effort, gradation, and thickness of compactive layer are factors which exert the greatest influence. Mineral aggregates experience a mechanical breakdown of some of the aggregate pieces into smaller fragments during any compaction process, whether in the field or laboratory. This phenomenon occurs as abrasion of the sharp edges during movement and reorientation of the particles in densifying and/or as granulation and fracturing of those pieces which have become overstressed. Two types of aggregate breakdown occur in the field. These may be classed in a general category of aggregate degradation.* One occurs during the con- * Aggregate degradation has been defined in many different ways. For this paper it is considered as any breakdown of larger particles into smaller ones, whether mechanical or chemical. struction period and is related to the densification of the aggregate body from a loose state to a relatively dense mass by heavy compaction equipment. This type is almost entirely a mechanical action. The other occurs after the construction period when the roadway has been put into use. This in-service breakdown is; a different phenomenon from the breakdown during construction in the sense that it combines mechanical with chemical changes. Time becomes an important consideration that may cause subordinate factors in construction degradation to develop into principal ones for in-service breakdown. Breakdown of aggregates in service has been extensively studied by investigators from the northwestern

Jan 1, 1962

By Otto H. Henry, Edward L. Badwick

Up to the present time, according to Hansen1 and Haughton,2 the constitution of the bismuth-indium system has not yet been published. The generally accepted value for the melting point of indium, as listed in most scientific journals and textbooks, is 155°C. Recently, however, H. M. Davis3 has determined a new melting point for indium of 257.3°C ± 0.1°C. Since bismuth has been used in preponderance as an alloying element in the majority of low-melting alloys, and indium has been used with considerable success in lowering the melting points of low-melting alloys,4,5 an interest has been developed in the application of these two metals, making a complete knowledge of the constitution of its alloys desirable. In this investigation, the melting point of indium reported by H. M. Davis has been found to be substantially correct. A value of 157.2°C ± 0.5°C was determined. The two eutectic compositions have been placed at 34 and 50 pct bismuth with their respective eutectic temperatures as 72.4'C ± 0.5°C and 90°C ± 0.5°C. The bismuth-indium phase diagram has been determined by thermal and microscopic analysis and is shown in Fig I. THERMAL ANALYSIS Granulated bismuth and indium shot, having a guaranteed purity of 99.99 and 99.95 pct, respectively, were melted in a carbon crucible by means of a laboratory heater. To minimize oxidation of the alloys, a heavy mineral oil (Nujol) having a high flash point was used. A platinum-platinum rhodium thermocouple 0f fine wire encased in a thin-walled Pyrex glass tube, about 1/8 in. in diameter, was connected to a type K potentiometer for temperature measurements. The thermo-couple was calibrated against the melting points of tin, bismuth, and the silver-copper eutectic and the boiling point of water. Since the temperature readings could be reproduced to 0.2°C, and the accuracy of the temperature standards in this range is slightly better than 0.5°C, it seems reasonable to assume that the temperature readings are reliable to approximately 0.5°C. The cooling rate could be controlled by varying the amount of insulation surrounding the crucible. Three or four layers of asbestos paper, 1/16r, in. thick, sufficed to give a cooling rate of from 1° to 2°C per minute. Undercooling was slightly noticeable. This condition was minimized by vigorous stirring, since the advantage of using slower rates was too small to justify the greater expenditure

Jan 1, 1947

The meeting of the Institute at St. Louis brought together many members of the Women's Auxiliary, and Mrs. Philip N. Moore, who was nominated as the Director for the St. Louis Section, took the occasion formally to inaugurate the organization in that district. A meeting was held at the Planters Hotel, anti after discussion as to, the aims and objects of the. Auxiliary, officers were nominated for the' Section; the meeting then adjourned for two days, to he resumed in Joplin.. Here a very successful meeting was held, at which the Vice-Chairman, Secretary, and Treasurer were elected. A great deal of interest was arouse under the able directorship of Mrs. Moore the St. Louis Section is likely to become a large and active organization. The president of the Women's Auxiliary, in opening the meetings, told the ladies present of the inauguration of-the-Society in February, 1917, and of the work which had been accomplished up to date. She told how the Society devotes itself to patriotic and humanitarian work along lines acceptable and interesting to the Mining Engineer, standing always alongside and behind the men of the profession. The Central Welfare Committee of the organization has three Sub-Committees: Foreign Relief, Emergency, and Americanization, and under one or other of those heads most of the work of the' Society has been done. Mr. Hoover was responsible for the inception of the Foreign Relief Committee, as its first work was the collection of funds for the supplementary meals for the Belgian Children. Under the energetic administration of Mrs. H. Knox, this sub-committee raised $12,100 in the period between the February meeting and the Declaration of war by the United States, when our government took over the entire duty of feeding starving Belgium. The organization of the Belgian Relief Committee, as it was styled, still remains, but the members are now asked to take up the question of relief in France. The President, Mrs. S. J. Jennings suggested at the St. Louis meetings that one way of working for the foreign relief alight be that all the members of the Auxiliary should, during the period of the war, forego all giving' and receiving of Christmas presents, except those they have been accustomed to give to the poor or in charity, and those they would give to the men in the services of the United States; that the money usually spent on the Christmas gifts should be put into a fund to be sent abroad for the fatherless children of France, as a gift from the families of the Institute. A good deal of discussion followed this proposal, as some of the ladies felt that children should have their Christmas gifts as usual. The Director of the Section emphasized the truth that the Christmas spirit was the .spirit of giving and sacrifice, and that no sacri-

Jan 1, 1918

By R. A. Breitrick, J. N. Swinderman, J. J. Cooper, H. L. Bauer Jr.

The Robinson Mining District, near Ely, Nev., is one of the major porphyry copper districts in the world. Within the district is an eight mile long east-trending zone of altered porphyry, metamorphosed sedimentary rocks, and sulphide mineralization surrounded by Paleozoic limestone, dolomite, shale and sandstone, Tertiary volcanics, and Quaternary alluvium. Six major disseminated ore deposits have been exploited in this zone. About 20% of the district production has come from disseminated ore in metamorphosed sedimentary rocks found adjacent to altered quartz-monzonite porphyry. The following brief statements summarize some of the relations between porphyry alteration, metamor-phism, and mineralization: 1) Disseminated copper ore does not occur in unaltered porphyry or in m-metamorphosed sedimentary rocks. 2) Sedimentary rocks have been only weakly metamorphosed where intruded by unaltered porphyry. 3) Intensely metamorphosed sedimentary rocks are found only adjacent to altered porphyry. 4) Many hydrothermal minerals are common to both altered porphyry and adjacent metamorphosed sediments. 5) Disseminated ore is found in altered porphyry and adjacent metamorphosed sedimentary rocks. 6) In general, there is a direct correlation between grade of ore in porphyry and copper content in the adjacent rocks. 7) Chemical changes in the altered porphyry and metamorphosed rocks appear to be related. The foregoing relations support a hypothesis that the porphyry alteration, the metamorphism of the sedimentary rocks, and the ore deposition were all part of a continuous hydrothermal process which probably closely attended the porphyry intrusion. The Robinson Mining District, most often referred to as the Ruth or Ely District, is located in eastern Nev. and is one of the major porphyry copper districts of the world. Production from 1908 through 1962 was nearly 250 million tons of ore averaging a little over one percent copper with a total metal value of nearly one billion dollars. The ore has been produced from six major disseminated-type deposits with the Liberty Pit deposit accounting for 70% of the total district production. Less than one million tons of base metal and gold ores have been produced from the replacement-type deposits of the district. Approximately 20% of the district production has come from underground mining operations; the pit ore has been mined with shovels and removed by train haulage, truck-train haulage combinations, truck haulage, and presently by a combination truck-skip system. Many of the ore deposits formerly worked by underground methods have been and are being exploited by open pit methods. (See Fig. I.) Two co.'s have accounted for virtually the entire production from the district. In 1958 Kennecott Copper Corp. acquired the district assets of Consolidated Coppermines Corp. and is now the sole ore producer in the district. Present operations are confined to the Liberty Pit where 22,500 tons of ore averaging a little less than 0.8% copper is mined per day. Cutoff grade is 0.4% copper, and the stripping ratio is three to one. The ore is hauled by rail 23 miles to the McGill Reduction Plant where it is concentrated to about 20% copper. Molybdenite is recovered as a by-product in the mill. The copper concentrates are smelted in McGill, and the blister copper is shipped for refining to Balt. where gold, silver, platinum and palladium are recovered. The Robinson Mining District has been well known as a porphyry copper district for the past fifty years, but many geologists are unaware of the fact that a large portion of the production has come from disseminated ore found in metamorphosed sedimentary rocks. The scope of this paper describes the occurrences of disseminated ore in the various metamorphosed sedimentary rocks, and presents evidence for the hypothesis that these ores are genetically, spacially, and coevally related to the disseminated ore in the porphyry rocks. Publication of this paper was granted by the management of Kennecott Copper Corp. A. H. James suggested and encouraged the writing of the manuscript. Special mineralogical and spectrographic analyses were performed by the Kennecott Research Center. The deposits of the district have been studied by many geologists since the turn of the century, and

Jan 1, 1964

By H. A. Fisch, A. J. Opinsky, J. L. Bartos

Fort?-six- two-grain bounduries were studied in doped tungsten 1amp wire that had been heated to 3450°K very vapidly. Back-reflection Laue photograms were taken of the grain boundary partners and solved, using a computer. The resulting distribution of large-grain orientations was analyzed. Rotational axes were calculatedfor each grain boundary pair. The axes of least rotation show an anisotropy of rolalional angle. WhILE the orientations of large grains in straight doped tungsten wire have been studied extensively, little has been done to characterize the boundary that separates them. Rosi.1 upon seeing the jagged interlocking boundary in doped tungsten wire. inferred that the grains should have a preferred orientation, and proved it. He interprets his data as indicative of a single ideal orientation—(531)— being parallel to the wire axis. Rieck2, 3 and Mannerkoski' have essentially confirmed this finding. Opinsky, Orehotsky, and Siegle argue that the data suggest that (211)—a plane-is parallel to the wire axis instead. This (211 ) contains the (531). and hence would appear to be a more general case.5 Ahlborn and wasserman6 report that their orientation data stretch from (110) through (531) to (311). This path is the locus of {211 Recently. Opinsky has suggested that the data can be interpreted as a series of ideal orientations that can be related by coincidence relationships to the (110) fiber texture. All these investigators have determined the orientations of the large grains by the back-reflection Laue technique, and they have all obtained similar results. Only Rieck5 as methodically looked at the large grains along a wire. He was apparently not concerned with the relationships of the large grains across their common boundary, but only with their individual orientations. This research was undertaken to fill this gap in the under standing of the mechanical properties of tungsten wire. Only the crystallographic aspects of the problem will be reported here. In addition, the large number of large-grain orientations, which was accumulated in this study. will also be analyzed. EXPERIMENTAL MATERIAL AND TECHNIQUES All of the data were obtained from four pieces of the same 7-mil-diam General Electric tungsten lamp wire. Twelve-inch lengths of the cleaned wire were heated in vacuum by the flick of a switch to 90 pct of the amperes necessary for fusion (a temperature of approximately 3450°K) and held for 1 min. On the basis of other data. it is estimated that the rise time is of the order of 0.5 sec. The four pieces of wire could have come from anywhere within about 18 ft of wire. Consecutive segments of each piece of wire were mounted in bakelite and polished metallographically The polishing procedure followed that described by woods. "nly boundaries between two grains that each occupied the entire cross section of the wire were photographed and X-rayed. The metallographic sample was mounted accurately with respect to the X-ray unit. Steps were taken to read the films as accurately as possible with the conventional Greninger net. The data were then entered into computer programs that solve the Laue film by precisely the same techniques that are used in the solution of the film by means of the stereographic projection. The use of the computer has probably shifted the main source of error from the stereographic plot to the reading of the film. On the basis of several experiments, it is thought that the error associated with the entire process, from mounting the sample through the computer solution, is of the order of about one-half degree. The output of the computer is the direction cosines of the fiducial direction (the wire axis) and the locations of the three cube axes. The former data were used to calculate the differences in orientation between the two grain boundary partners, and the latter were used in the calculation of the rotational axes that could bring the two grains

Jan 1, 1970

By L. H. Robinson

Triaxial compression tests have been performed to determine the strength characteristics of limestone, sand-stone and shale rocks subjected to controlled stress conditions. This control tuns exercised by varying the liquid pressures within and around a plastic-encased rock specimen. The pressure in the pores of the rock was varied throughout the range from atmospheric to 15,000 psig; the external pressure was changed over the same range with various positive pressure differences between is and the intertnal pressure. The data show that the rock strength increased and the mode of failure changed as the pressuire. surrounding the rock became greater than the pressure in the pores of the rock. These observations and the resu1ts of microbit drilling experiments indicate that the increased rock strength under pressure may bc an important effect in reducing drilling rare, but that other factors are probably of even greater importance. INTRODUCTION A large part of the research conductcd to reducc thc cost of drilling is directed toward improving present drilling technology and dcveloping new drilling methods. In spite of the fact that drilling is essentiaIly the act of making rocks fail, many details of the mechanism of failure are not known. It seems probable, therefore, that continuing studies of the fundamentals of rock failure can lay a foundation for future improvements in drilling technology. One of the factors which affects rock failure is the stress applied to the rock. This effect has been known for many years.'.'.; As an example, stress studics have been published by engineers' concerned with the strength characteristics of concrete in large dams. More recently, a number of investigators4-12 have explored the effects of stress on the strength of geologic formations and the geologic implications of their findings. During the last few years some research'" on rock strengths has also been conductcd in an attempt to gain additional insight into the factors which affeet rock drillability. In detcrmining the strength characteristics of rocks under different stress conditions, investigators have conventionally used triaxial compression equipment. wherein a jacketed rock cylinder is uniformly loaded from all directions and then compressed longitudinally. The results of this work have demonstrated that the mode of failure (brittle or malleable) is dependent upon the loading pressure, and that the strength of the rock increases as the loading pressure increases. These results clearly manifest that the stress, which is determined by the loading pressure, affects rock strength, and this implies that rocks under stress should be stronger and hence harder to drill. During the drilling of a porous rock the stress conditions are determined not only by the pressure surrounding the portion of the rock undergoing failure (confining pressure) but also by the pressure of the interstitial fluids within the rock (pore pressure). The importancc of both these pressures on the drilling rate of rocks has already been demonstrated by a number of investigators. Murray and Cunningham" found in microbit drilling expcriments that at constant pore pressures the drilling ratc decreased as the hydrostatic pressure surrounding an unjacketed, impermeable rock increased. Later Eckel" found that for jacketed Iimestone specimens the differcnce between hydrostatic (wellbore) pressure and formation (pore) pressure had an important effect on drilling rate. These observations of the effect of pressure on drilling rate emphasize that for drilling studies triaxial compression tests should be conducted under conditions of confining and pore pressure which simulate conditions underground. In the past, triaxial tests have been made under conditions which do not reproduce those underground. In particular, most of the tests on porous materials have keen made at varying confining pressures but with atmospheric pore pressures. In only one group of tests' was any data on the effect of pore pressurc reported, and these few data were on materials not representiltive of those encountered in drilling earth formations. The research described herein was initiated to deter-mine the importance of both internal pore pressure and confining pressure on failure characteristics of limestone. sandstone and shales. Triaxial loading equipment was used to obtain strength data at pressures up to 15,000 psig. An additional objective of this research was to apply these results to drilling rate studies by comparing them with the previously published drilling data of Murray and Cunningham" and of Eckel12. The work reported here is but one step in determining and evaluating the fundamental mechanisms which control drilling rate. Additional research is needed to clarify other aspects of the drilling process. The better

By James A. Beck

Phosphorus is essential to all life processes and therefore to the existence of man. In this role, there are no substitutes for phosphorus. In a commercial sense, phosphorus and its compounds are important to our entire economy, both in agricultural and in nonagricultural applications. The world's phosphate requirements are met by mining phosphate rock. Two general types of phosphate ore deposits are commercially important-igneous and sedimentary. Igneous deposits generally are more difficult and more expensive to mine than sedimentary deposits and are of importance mainly in the USSR, North Vietnam, and South Africa. Approximately 15% of current world production comes from these deposits. Over 80% of world production is from the pellet sedimentary deposits of Florida, North Africa, and elsewhere. Guano, the second type of sedimentary deposit, is produced in South America but is declining in world importance. Production Production of phosphate rock was reported in 31 countries during 1972. However, about 80% of world output is produced in three countries: the United States, the USSR, and Morocco (Table 15.2A.1). Throughout the past 20 years, between 75% and 80% of world output has been produced by these three leading countries. Between 1948 and 1972 world production increased at an average rate of 10% per year, from 21.5 to 103.9 million tons. Growth was quite steady at 6% per year through 1963, but in the 5 years from 1963 to 1968 production increased 11 1/2% per year. Since 1968 production has increased about 91/2 % annually. Since 1948 several new phosphate mining ventures have been developed in Senegal, Togo, Israel, and North Vietnam. In the same period, only one important phosphate deposit, on Makatea Island, has been mined out and closed. A number of other phosphate mining ventures are in various stages of planning and development. The most important new venture in phosphate mining is in the Spanish Sahara. New mining capacity is expected also in Syria, and serious investigation is in progress in Peru, India, Turkey, and Australia. Major expansion of existing operations is expected in Morocco, Russia, Tunisia, Israel, and Jordan. Consumption Historical data on world consumption of phosphate rock are not available in detail, but world consumption of phosphate has closely paralleled world production in the past two decades. The United States is the world's largest user of phosphate rock, accounting for 30%

Jan 1, 1976

By D. J. Barrett, M. A. Sochocky

INTRODUCTION Summary of Factors Influencing Comminution Circuit Design The selection of an appropriate comminution circuit for a specific ore is one of the most important decisions in the design of a processing plant. The importance is related to the fact that the capital and operating costs for crushing and grinding plant generally represent, as is well known, the major portion of the plant costs. This chapter will, therefore, identify as many as possible of the factors which influence the selection of a comminution circuit. The number of factors which will have to be considered for any comminution project will depend, among other things, on the type of project. If, for example, the project is an entirely new mining development, then most, if not all, the factors identified will have to be analyzed. If the project is an expansion of a developed mining operation or if the new orebody is adjacent to a viable operation, then the existing operation will influence the choice of factors or design constraints which need to be considered. The existing infrastructure or supporting systems may be quite adequate to accommodate the requirements of any expansion or new development. Hence, those factors may not have to be considered. To cover, however, the widest spectrum of projects, the factors which have been identified in this chapter are those which will have to be considered for the most complex of projects, that of developing an entirely new mining operation. The range of factors is as broad as the range of different ore types. Thus, each development must be treated with individualized care. The most important step in the development is the analysis and understanding of the ore characteristics. The hardness of the ore, its abrasiveness, friability, moisture content, grade, mineralization including gangue mineralization, liberation size, chemistry, and other characteristics should be the first to be analyzed in the investigation. The next should be the determination of factors such as plant size, throughput, location, climate, accessibility, and availability of water. The selection of samples for initial bench scale work and bulk sampling (when needed) for further

Jan 1, 1982

By G. G. Luther, C. E. Jackson

THE relationship between hardenability and weldability has been mentioned many times. The ease of making a hardness survey has led to its wide use as a criterion [ ] of weldability and with a given class or series of steels for which the ductility under weld heat-treatment is known the test is entirely suitable. However, in studying a new steel the hardness survey is of less value, since it is based on the assumption that there is a correlation between hardness and ductility. Several attempts have been made to derive indices for weldabilityl and hardenability from the chemical analysis. In most of these proposals the effects of the different elements were considered to be additive, but recently Grossmami2 proposed a novel method of calculating the hardenability of a steel from its chemical composition. In the [ ] method proposed, a steel is considered as having a base hardenability due to its carbon content and grain size, and this base hardenability is multiplied by a factor for each chemical element present, The final product is the hardenability. The purpose of the present study is to point out the possible relationship between hardenability and the effect of welding on hardness and ductility for a number of plain carbon and low-alloy steels. The composition of the 25 steels reported in this paper as determined by chemical analysis is given in Table I. To eliminate the effect of variations in finishing temperatures, the 1/2-in. plates were normalized after heating for one hour at 1650°F. in a controlled-atmosphere furnace.

Jan 1, 1942

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 thermochemistry of steelmaking. The problem is not merely one of making a small numbcr of temperature measurements in the open-hearth furnace. This has been done by several methods to a * Assistant Manager, Research and Development, Jones and Laughlin Steel Corporation, Pittsburgh, Pennsylvania. Issued as T.P. 2031 in MEtals Technology, June 1946; also in Open Hearth Proc., 1946. † Open-hearth Metallurgist, Jones and 1aughlin Steel Corporation, Aliquippa. Pennsylvania. 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 protectioil 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 life of the equipment was short and maintenance was an important consideration. Earlier Work Any of a number of Physical Properties of liquid steel could conceivably be used a 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, 1947

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 thermochemistry of steelmaking. The problem is not merely one of making a small numbcr of temperature measurements in the open-hearth furnace. This has been done by several methods to a * Assistant Manager, Research and Development, Jones and Laughlin Steel Corporation, Pittsburgh, Pennsylvania. Issued as T.P. 2031 in MEtals Technology, June 1946; also in Open Hearth Proc., 1946. † Open-hearth Metallurgist, Jones and 1aughlin Steel Corporation, Aliquippa. Pennsylvania. 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 protectioil 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 life of the equipment was short and maintenance was an important consideration. Earlier Work Any of a number of Physical Properties of liquid steel could conceivably be used a 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, 1947

By Henry M. Howe

The data which are collected in Table 1 show that the ferrite of low-carbon steel and of electrolytic iron, like the network of hypo- and hyper-eutectoid carbon steel, inherits, either absolutely or relatively, the grain size of the mother austenite from which it is born in cooling through the transformation range. This evidence is so abundant and concordant as to cast doubt on Prof. Jeffries'l hypothesis of what might be called reversed inheritance, by which he explains Mr. Ruder's observation2 that a grain in a "slug of pressed pure electrolytic iron powder" was coarser, perhaps 1,500,000p2, aftcr a 3-hr. exposure to 1000" C. than after a 3-hr. exposure to 1250-1300°, when the grain size was about 35,000µ2. His explanation implies a natural tendency of coarser austenite grains to yield finer ferrite ones than spring from finer austenite grains, so that the inheritance is reversed. What seems to me a simpler explanation is that the enormous grains which followed the 1000" heating were not inherited from the mother austenite, but were formed by the process of natal coarsening, by means of which Stead and Carpenter developed grains of this same order of magnitude in this same kind of material, on heating to 950" or to 1000°, the temperature used by Mr. Ruder, provided the exposure was not unduly prolonged, and it does not seem to have been in Mr. Ruder's case. That their coarsening was natal and not through inheritance is shown first by the fact that their grain coarseness was out of all proportion to their relatively low temperatures and short periods, and hence was very far in excess of the grain size which the mother austenite must have had, and second and more cogently by the fact that the shape of these coarsened grains was evidently determined by the temperature distribution which existed during and immediately after the Ar3 transformation, that during the passage from the gamma to the non-gamma state. In discussing this subject, we must remember that coarse ferrite grains, whether those formed in cooling from the molten or those induced by

Jan 1, 1918

By T. A. Rickard

INTRODUCTORY. THE presentation to the Institute, eight years ago, of the paper of Pošepny on " The Genesis of Ore-Deposits " has borne fruit in much fresh: investigation, as is evidenced, for example, by the group of very valuable papers, by distinguished members" of the United States Geological Survey, read at the Washington meeting-discussions of general principles particularly suggestive to those who are engaged in mining. Pošepny, in the discussion of his famous treatise, said that the present writer seemed to look at every new conception in ore-deposition" from the sole standpoint of its immediate usefulness in mining."* Protesting mildly against " sole " and "immediate," I accept the impeachment. It calls for no defence. THE DEVELOPMENT OF RECENT THEORIES. Given the idea of an underground water-circulation as the chief factor in the deposition of ore, the next step in the inquiry as to the genesis of such deposits is, the endeavor to determine which particular part of the general water-circulation is responsible for the results. Around this question have centered the controversies of a generation, and to these controversies we owe the gradual clarification of our ideas upon the processes of ore-formation. It is unnecessary to sketch here their progress from Werner to Le Conte, who combated in 1883 the extreme views of the lateral-seeretionists, and in 1893 opposed the narrow interpretation of the ascensionist-theory. The generally accepted opinions of to-day are a well-deserved tribute to his philosophic discrimination. Thanks to Prof. Van Hise and Mr. Slichter, whose work he utilizes, we have now arrived at a comprehensive conception

Jan 1, 1902

By R. P. Carreker, R. W. Guard

True stress-true strain data are given for nominally pure molybdenum (99.95 pct) over the temperature range -196° to 1540°C (0.027 to 0.63 T/T). Strain rate sensitivity was determined by rate change tests and stress relaxation tests. Inhomogeneous yielding and strain aging effects were observed. The yield stress and tensile strength depend markedly on temperature below 400°C and are insensitive to temperature in the range 400' to 800°C. The ductile to brittle transition range is +25O to -25OC. Strain rate sensitivity and stress relaxation effects are very large near room temperature. THIS report presents data which were obtained as a part of a continuing program designed to document the deformation behavior of nominally pure metals over a wide temperature range.'" This research program is rooted in the conviction that sufficient tensile and creep data of appropriate quality and detail does not exist to provide precise phe-nomenological descriptions of the deformation behavior of pure metals as a function of temperature, strain rate, and grain size. Such knowledge is needed to provide a firm base for alloy design and an experimental framework to which theories of deformation must conform. These data also complement a parallel exploratory program investigating the properties of refractory metals, including molybdenum, and their alloys. Several important reviews and research reports dealing with the tensile properties of molybdenum as a function of temperature have appeared."-lo To a great extent the work to be reported in the present paper parallels that of Bechtold and of Pugh. The authors' results are in general agreement with those of Bechtold and Pugh. The principle differences be- tween the present experiments and those published previously are as follows: 1—Wire specimens prepared from arc cast molybdenum were used in the present experiments, bar specimens were used by others. Pugh used arc cast material while Bechtold's most extensive results" were obtained on powder metallurgy specimens. 2—Several different grain sizes were tested in the present experiments. 3—The testing range was extended to cover from -196°C to 1570°C (0.027 to 0.63 T/Tm). 4—The combination of wire specimens, high speed autographic recording, and a stiff testing machine permitted more detailed study of initial yielding. The principle contribution of the present paper is the demonstration of the relatively consistent mechanical properties of nominally pure arc cast molybdenum specimens of differing metallurgical history. Bechtold and Scotts have shown that arc cast and powder metallurgy molybdenum samples have comparable tensile properties in the range —75" to 200°C when processed to have the same re-crystallized grain size. Material The molybdenum used in this investigation was supplied by the Climax Molybdenum CO. Its metallurgical history is outlined in Table I; the final products were 0,030 in, diam wire specimens annealed at 1100' and 1375°C and 0.060 in. diam wire

Jan 1, 1957

By C. S. Roberts, S. L. Couling

PLASTIC strain in polycrystalline metal as a result of bulk movement of one grain with respect to another along grain boundaries is not new. Rosenhain and Humphrey observed such effects shortly after the turn of the century.' Since then, observations of grain boundary deformation have been made on several metals. In recent years, intensive studies of the deformation at grain boundaries have been performed on polycrystalline metal and bicrystals.14-20 Aluminum or its alloys have been used in these latter studies. The subjects of controversy at present appear to be not whether grain boundary deformation exists, but 1) how quantitatively important it can be in polycrystalline metal, and 2) what its detailed mechanism is. Some investigators have concluded that such de- formation is minor in importance while others have concluded that it is a major consideration. Some have concluded that it involves shear of one grain over another at the interface while others have concluded that it operates by crystallographic deformation within the grains near ,the boundary. A categorical statement for electrolytic magnesium cannot be made on either of -these points. When polycrystalline magnesium is deformed in creep under conditions of high strain rate and low temperature, grain boundary deformation is relatively slight." Under these conditions, much deformation occurs within the grains and boundary contours change to a higher-energy jagged form. The result is shown in Fig. 1, where boundary jaggedness is pronounced upon polishing and etching after a plastic strain of approximately 6 .pct at 300°F and 3000 psi. No migration of the boundaries has been detected in this process. When the same metal is deformed the same amount at 600°F and 300 psi, resulting in a much lower strain rate, the boundaries migrate toward a lower energy configuration, where

Jan 1, 1958

By Charles Fulton

This paper describes experiments carried on at the Case School of Applied Science, together with their results. Their success led to the design of the larger furnace herein described, but which has not been built. A PREVIOUS article' by the authors contained a general description of the new roasting furnace herein described but it did not go into detail as to the metallurgical behavior or the results obtained. Believing that such information would be of great value, they have elaborated on the subject and have given many unpublished details. The furnace described applies the principle of roasting finely divided zinc-sulfide ores, now produced in large quantity by the flotation process, in gaseous suspension; that is, the ore particles are carried, in suspension, in a current of air and gaseous products of the roast. The relatively great fineness of flotation concentrate presents difficulties and problems of roasting in furnaces of the ordinary type; the fine ore is forwarded through the furnace in the form of a shallow bed and its very fineness leads to dense impervious bedding which prevents oxygen from reaching the interior of the bed, thus unduly lengthening the time of roasting and preventing the elimination of the last of the sulfur. The fineness of the concentrate, normally, should lead to a rapid and complete roast, for the speed of roasting is a function of the surface exposed to oxygen, which surface is greatest, per unit of weight, in very fine material. The difficulty in bed roasting is to get the oxygen to the particle. If the fine ore, during the roasting, could be freely suspended in oxidizing gases, full advantage could be taken of the great surface conferred by its fineness. This fundamental idea, of course, is not new, for the Stedtefelt furnace, familiar to the older metallurgists, is an example of it; but the manner in which this is accomplished may be new.

Jan 10, 1924

By John V. Beall

Many months ago, the ME staff began thinking about what to put on the February cover of the Centennial Commemorative issue. We have considered photographs of mines, equipment, symbolic artwork and various collages. Our theme is "the next 100 years in mining" and the cover ideally should convey a related message or idea. All of us are convinced that there are many exciting technical changes that will be coming. But even so, we decided that, in our opinion, the engineer is the most vital factor. For this reason we chose to put a man on the cover of this issue. At first it was going to be the face of a man with whom each member could conceivably identify himself. It was one of the Bobs on our staff (we have four) who came up with the thought that since it's the future we are talking about, we should have a young man's or a student's face. Of course we firmed up our idea at the ninth hour, and it was too late to canvass the mining schools. However, by a stroke of luck, we were rapping with a group of University of Arizona students on the terrace of the Pioneer Hotel on December 7, 1970, and met Dave Bolles.

Jan 1, 1971

By H. M. Cyr, T. F. Steele, C. W. Siller

The development of a new metallurgical roasting device is described. It consists of a refractory column into which air is injected at various levels, forming several superimposed fluidized beds with no supporting grates. When pelleted zinc sulphide concentrates are charged, the roasted product needs no further sintering before reduction to metal. WHEN a gas such as air is blown upward with increasing velocities through a loose mass of solid particles, marked changes in the physical behavior of the particles are noted. At first, when the velocity of the gas is insufficient to support any of the solid, the mass constitutes a "fixed bed." As the gas velocity increases until the pressure drop through the bed approaches the effective weight of the bed per unit area, the bed expands until the solid particles are supported by the air rather than by the lower particles. Some vibration of the particles becomes apparent, but little mixing occurs. This condition is called a "quiescent fluid bed." A further increase in gas velocity imparts more separation and more motion to the individual particles until a condition of turbulence is reached. This "turbulent fluid bed" resembles a rapidly boiling liquid with the characteristic highly agitated diffuse surface and many small eruptions of the boiling mass. Different degrees of turbulence can be generated and all produce excellent mixing. The final stage occurs when the gas velocity becomes so great as to create a "dispersed suspension." Here no surface of the mass is defined and the gas carries solid particles out of their original positions. These changing conditions of fluidization have been studied carefully and pertinent nomenclature standardized by a committee of the American Institute of Chemical Engineers.' Many mathematical analyses2-3 have been made of the forces acting in a fluid bed. These analyses are invaluable, especially for the design of column sizes and selection of equipment. However, in a metallurgical process involving solids of many sizes with changing densities, varying temperatures, and changing gas compositions within the bed, calculations based on theory become approximate. Optimum operating conditions then are best determined experimentally. Many applications have been made of the principles of fluid-bed action by mechanical, chemical, and metallurgical engineers. Especially when good con- tact between reacting solids and gases is desired, very effective results are obtained from fluid beds. They permit excellent temperature control and uniformity throughout a mass of solids in fluid action. Heat transfer to walls and any coolers is high, and fast reaction rates are attained because the solid surfaces are continuously swept clean. The main disadvantages of fluid-bed operations are the danger of short-circuiting in a single bed, danger of incipient sintering which stops action, the necessity of avoiding large changes in particle size or density during roasting, and dust losses when particles of the charge are carried out with exit gases. In the metallurgical field the roasting of sulphide ores to form oxides and sulphur dioxide appears to combine several operating conditions which can be achieved to advantage in a fluid bed. Roasting involves a solid-gas reaction where a high reaction rate is necessary for high capacity, where good temperature control is important in order to prevent sintering, where good heat transfer is needed, and where the density of the solids, when changing from sulphides to oxides, is not largely changed. Short-circuiting, however, constitutes a major problem when a single fluid bed is used. Because of the turbulence of the bed, an entering particle may be in the region of the discharge before it is roasted. Hence, to attain a satisfactorily low sulphur in the calcine, a long average residence time with correspondingly low capacity is required. The solution to this difficulty is the use of multiple stages, which in the conventional fluid-bed design requires separate hearths with feed and discharge mechanisms for each stage. A further practical difficulty in fluid-bed roasting of flotation zinc concentrates is their fine particle size which makes a true fluid action without excessive carry-over of dust very difficult to attain, especially when the large air volumes necessary for high capacity are used. A New Design After considerable experimentation in the laboratory and on a semipilot-plant scale, a new method and equipment for roasting were devised which provided a unique solution to these problems. A detailed account of this development appears in the patent literature," and many of the variations of this development reported herein are the subject of

Jan 1, 1955

By D. R. Parrish, K. W. Beaver, H. W. Wood, R. W. Rausch

A pilot test of forward combustion in the Shannon pool, Salt Creek field, Wyo., is described. The Shannon sand, 950-ft deep, contains a heavy (25" API), viscous (76 cp) oil. Natural reservoir energy is limited. Primary production, intermittent since 1889, recovered only about 2 per cent of the oil in place. The field is operated by Pan American Petroleum Corp. for the Midwest Oil Corp., the owner. The original pilot was a 1.32-acre five-spot. The expanded pilot has eight producing wells surrounding a roughly triangular area of about five acres with the injection well near the center. A control or comparison well was also recompleted in another part of the field. Operation of the pilot has been little different front an ordinary gas drive. Little special equipment was found to be absolutely necessary. Except for some use of a temperature-resistant cement, all wells were conventionally completed. In spite of poor oxygen consumption, the over-all performance of the pilot has been good. Total oil recovery to June 1, 1961, was 73,971 bbl. The wells of the original pilot alone had produced about 24,000 bbl, equivalent to 50 per cent of the oil in place, when fire breakthrough at the first well occurred. These wells have now produced oil equivalent to more than 74 per cent of the oil in place in the original pilot area and production is continuing. It appears that ultimate recovery will approach theoretical maximums before the wells must be abandoned. Performance of the pilot has been encouraging, and expansion to a fieldwide combustion operation is being investigated. INTRODUCTION The results of both laboratory investigations and field tests of underground combustion have been reported previously.' However, most of the field tests were primarily experimental. More information and experience are needed before forward-combustion operations can be engineered with confidence. The purpose of this paper is to present the results of a successful pilot test of forward combustion. These re- sults should increase confidence in forward combustion as a practical method for commercial oil recovery. HISTORY OF THE SHANNON POOL The Shannon pool is located on the north end of the Salt Creek field in Natrona County, Wyo. It is approximately 50-miles north of the city of Casper. The Shannon pool's3 discovery well was completed in 1889, making this one of the oldest oil fields in the Rocky Mountain region. Three more wells were drilled in 1890. First production was hauled in wooden barrels by horse and wagon to the railroad in Casper. In 1894 a small refinery, the first in Wyoming, was built in Casper to process the Shannon crude. In the following years the field changed hands several times. It appears that each new owner did some development drilling as several wells were completed in each of the years 1895, 1902, 1905 and 1912, with negligible development in the intervening years. Forty-eight wells were drilled in this period, but many were later abandoned. Discovery of the more prolific Salt Creek field proper ultimately forced suspension of operations at the Shannon pool. After 1915 there was only sporadic production, mostly to supply cheap boiler fuel to drilling rigs in the Salt Creek field. But even this was discontinued in 1931. Since then the pool had been dormant until the recent operations, which are the subject of this paper. The Shannon pool is now owned by the Midwest Oil Corp. Field operations are conducted for Midwest by Pan American Petroleum Corp. THE RESERVOIR Fig. 1 is a map showing subsurface contours of the Shannon pool. The reservoir is on a nose of the Salt Creek anticline dipping to the north at about 500 ft/mile. The trap is provided by a shallow fault on the updip side of the productive area. The downdip limits are bounded by water, but this water has not provided an effective source of reservoir energy. The Shannon sand outcrops at many places in the immediate vicinity, providing good surface indications of the Salt Creek anticline. At the Shannon pool the sand has been lowered by faulting and is overlain by about 900 ft of shale and other sands. The Shannon sand consists of two members. The upper, a water sand, is about 40-ft thick and is separated from the lower member by several feet of sandy shale. The oil pay occurs in the lower mem-

By John Drew Ridge

For the early conservationists before the first decade of the twentieth century, conservation meant largely the planned preservation of water, forest, soil, and wildlife resources-renewable natural resources-through efficient use. Water was primarily thought of as a resource that must be kept available for humans to enjoy in a recreational sense and as a habitat for wild animals, birds, and fish. Little thought was given to conserving water for actual human or industrial needs. If industry entered the picture it was as an actual or potential polluter of water, which was the basic necessity for drinking and bathing and for outdoor recreation. Even the forests were only held worthy of conservation largely because they were areas in which wildlife could, or should, abound and in which human beings might find relief from the cares and problems of everyday life. Finally, the soil was to be preserved in its natural fertility through proper fertilization, cultivation, and crop rotation; in this the conservation program did enter the realm of the practical. For through soil conservation, the world was to be able to raise increasingly large crops of constantly improved organic foods which the steadily growing population of the earth was to need to survive and improve. Relatively little time, however, was spent on considering what profit the farmers of the world were to make from the scientific farming on which they were to embark. In short, the appeal of the early conservationist program was much the same as that of the entire era of Theodore Roosevelt of which it was a part; it was to the heart rather than to the mind; it was to emotion rather than to reason. Because of the way in which the problem was approached, conservation took on the character of a crusade rather than that of a practical plan for the betterment of man through economically sound methods of improving his environment and the uses he makes of it. Conservation had, then, all the advantages of a stirring appeal to the emotions, but it did not have the lasting results that would have been achieved by a program with a sound economic basis.

Jan 1, 1959