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By Masatsugu Taniguchi

Onoda Cement Co., Tsukumi is one of the largest limestone producer in Japan. From mines called Suisho and Ganji, it supplies limestone for cement plant, lime manufacture, iron and steel industries and for many purposes. The Suisho mine is highly productive, though it's operations are governed by the utmost regard for its impact on the surrounding environment. However, it became difficult to meet additional expanding demand and to assure continuity of high rate production. Present production rate 1s 6 million tons per year. The Ganji mine, some 2 km south west of the Suisho mine, began first-stage development In mid- 1973 and in january I976 started production. The capacity of major facilities is 9 million tons per year. Full production is predicted in 1979. Mining and milling methods of these mines under strict environmental considerations are discussed.

Jan 1, 1976

By Rudolf Gahl

THE history of flotation in America is very short, at least as far as the large-scale application of the process is concerned. It is remarkable how many important developments have taken place inn the last few years and are already being extensively utilized. What was new a year ago, seems almost commonplace now. For this reason it is with hesitation that I follow the suggestion: of Dr. Ricketts, President of the Institute, to describe the experiences of the Inspiration Consolidated Copper Co. with the flotation process. TESTS CONDUCTED IN SMALL TEST-MILL When the Inspiration company first decided to build a concentrating plant, nothing was known about flotation, and the process was to be gravity concentration pure and simple. Demonstration Tests Conducted by Minerals Separation Co. While plans were being prepared by H. Kenyon Burch (who had been intrusted with the design and construction of the concentrator) the Minerals Separation Co., a concern at that time little known in America, asked and obtained permission to demonstrate the value of its flotation process for Inspiration ore. As. a consequence, a small 50-ton flotation machine of standard design was added to the company's test plant and started to operate in the beginning of 1913. This marks the beginning of flotation at Inspiration. The results obtained with this machine, which was operated by members of the Minerals Separation staff, so far surpassed what this company anticipated that it was decided to continue flotation tests for this purpose, and two of the flotation experts of the Minerals Separation Co., I. L. Greninger and G. A. Chapman, were retained. L. R. Wallace, now superintendent of the Miami works of the International Smelting Co., was at that time metallurgist of the Inspiration company and in that capacity took an active part' in these tests. Great credit is due to him for his quick recognition of the possibilities of flotation.

Jan 9, 1916

By C. H. Mathewson, W. R. Hibbard, Robert Maddin

A satisfactory mathematical relationship between shear, elongation and change of orientation in the axial straining of a single crystalline rod or wire may be based on a simple model in which blocks, representing glide lamellae, glide over one another and rotate so as to maintain the original fixed position of the axis as the wire elongates.' Obviously such a model gives no information concerning strain-hardening or the atomic adjustments at the sliding surfaces and their influence on the internal structure of the blocks. Moreover such an operation could be conducted with rigid blocks only by using self-aligning grips or a flexible attachment which would permit the adjacent blocks to freely assume their changing orientations. There are many unsolved problems (see Andrade2) concerning the manner in which nature departs from the simple model in permitting the essentials of slip, rotation and elongation to occur along with strain-hardening and the appearance of glide lamellae of various dimensions and special characteristics, not fully appreciated at the present time. This paper describes part of an extensive investigation on the development and characteristics of glide ellipses in single crystalline alpha brass rods and is especially concerned with the observation of cross-slip in crystals oriented wholly within the range of slip on a single system according to the generalizations first presented by Taylor and Elam in 1923.³ Experimental Procedure Half-inch rods of alpha brass (nominally 70 pet Cu, 30 pet Zn)* were converted into single crystals by melting and gradual solidification in a graphite mold according to the Bridgman method.4 In order to remove any coring, the crystals were homogenized at 800°C for 16 hr and tested by etching with a 50 pet nitric acid solution. The back-reflection Laue technique as described by Greninger6 was used for determining the orientations of the crystals. Standard stereographic operations were employed to locate the specimen axis in a triangle of the Taylor and Elam3 projection so that the slip plane and direction could be predicted. The lineage structure reported by Buer-ger6 was present in the crystals used in this investigation. However, only crystals were used in which the internal differences in orientation did not exceed two degrees. Very little is known concerning the effect of the presence of a lineage structure on the detailed mechanism of plastic deformation.

Jan 1, 1949

By C. H. Mathewson, Robert Maddin, W. R. Hibbard

A satisfactory mathematical relationship between shear, elongation and change of orientation in the axial straining of a single crystalline rod or wire may be based on a simple model in which blocks, representing glide lamellae, glide over one another and rotate so as to maintain the original fixed position of the axis as the wire elongates.' Obviously such a model gives no information concerning strain-hardening or the atomic adjustments at the sliding surfaces and their influence on the internal structure of the blocks. Moreover such an operation could be conducted with rigid blocks only by using self-aligning grips or a flexible attachment which would permit the adjacent blocks to freely assume their changing orientations. There are many unsolved problems (see Andrade2) concerning the manner in which nature departs from the simple model in permitting the essentials of slip, rotation and elongation to occur along with strain-hardening and the appearance of glide lamellae of various dimensions and special characteristics, not fully appreciated at the present time. This paper describes part of an extensive investigation on the development and characteristics of glide ellipses in single crystalline alpha brass rods and is especially concerned with the observation of cross-slip in crystals oriented wholly within the range of slip on a single system according to the generalizations first presented by Taylor and Elam in 1923.³ Experimental Procedure Half-inch rods of alpha brass (nominally 70 pet Cu, 30 pet Zn)* were converted into single crystals by melting and gradual solidification in a graphite mold according to the Bridgman method.4 In order to remove any coring, the crystals were homogenized at 800°C for 16 hr and tested by etching with a 50 pet nitric acid solution. The back-reflection Laue technique as described by Greninger6 was used for determining the orientations of the crystals. Standard stereographic operations were employed to locate the specimen axis in a triangle of the Taylor and Elam3 projection so that the slip plane and direction could be predicted. The lineage structure reported by Buer-ger6 was present in the crystals used in this investigation. However, only crystals were used in which the internal differences in orientation did not exceed two degrees. Very little is known concerning the effect of the presence of a lineage structure on the detailed mechanism of plastic deformation.

Jan 1, 1949

By R. J. Blackwell, A. L. Pozzi

Scaled laboratory-model studies provide a powerful method for evaluation of a proposed oil-recovery process. In recent years, models have been used extensively to evaluate processes in which solvents displace oil, both for general cases and for specific reservoir conditions. Since the performance of a miscible flood in a horizontal reservoir can be significantly affected by transverse mixing between solvent and oil, this displacement mechanism must be accurately simulated in the scaled model studies. Unfortunately, precise scaling of transverse dispersion coupled with the requirement of geometric similarity requires impractically large laboratory models and long times for experiments. If scaling requirements for miscible displacements could be relaxed while accurate simulation of essential displacement mechanisms is maintained, the utility of model studies would be greatly enhanced. The purpose of the work reported herein was to evaluate the relative importance of various mechanisms affecting miscible displacement and to ascer tain whether the essential features of the displacement process can be simulated even though some scaling groups are not satisfied. These studies were performed with completely miscible systems in linear, horizontal models packed with unconsolidated media. From the experimental results, a set of relaxed scaling criteria was formulated which allows the requirements of geometric similarity and equality of the ratio of viscous to gravity forces to be omitted for specified conditions. The relaxed criteria are valid whether transverse mixing is by molecular diffusion or by convective dispersion. Correlations which permit prediction of vertical sweep efficiencies in linear, horizontal reservoirs were developed from the experimental data when transverse mixing is by molecular diffusion. These same correlations may be used when transverse mixing is by convective dispersion if an empirically defined, effective, transverse dispersion coefficient is used in the description of the mixing process. The effective transverse dispersion coefficient correlation essentially duplicates the dispersion coefficient correlation for equal-viscosity, equal-density fluid systems. Experimental values for the effective transverse dispersion coefficient can be measured readily. INTRODUCTION One of the most effective methods for evaluation of miscible-displacement oil-recovery processes is that of displacements in laboratory models scaled to simulate reservoir conditions. For these laboratory studies to be meaningful, however, the essential displacement mechanisms affecting reservoir performance must be accurately simulated. Since the performance of a miscible flood in horizontal reservoirs, or in dipping reservoirs at high rates, can be significantly affected by transverse mixing of solvent and oil, this mechanism must be considered in the design of laboratory experiments. Unfortunately, precise scaling of transverse dispersion coupled with the requirement of geometric similarity requires impractically large laboratory models and long experiment times. This difficulty seriously limits the utility of laboratory model studies. Craig,et al,1 demonstrated that geometric similarity is not required when mixing is unimportant. Their experimental data indicate, for the cases studied, that the displacement is sufficiently characterized by scaling the ratio of viscous-to-gravitational forces. This work suggests that relaxation of the requirement of geometric similarity and, possibly, other criteria might also be permissible when mixing is important, provided suitable groups describing the mixing process are scaled. The purpose of the work reported here was to evaluate the relative importance of various mechanisms affecting miscible displacement and to ascertain whether the essential features of the displacement process can be simulated even though some scaling groups are not satisfied. Consequently, laboratory investigations were made of the dependence of recovery on dispersion and other variables,

By Adrian M. Crawford

INTRODUCTION A study has been made of the stability of blocks and wedges of rock subjected to gravity forces in the roofs of underground excavations. Rock wedges may become wholly or partly self supporting with the mobilization of shear resistance of discontinuities bounding such wedges. The influence of in-situ stresses and the relative stiffnesses of the intact rock, and shear and normal stiffnesses of the discontinuities has been investigated. A two dimensional, plane strain model of symmetric rock wegdes in a horizontal stress field has been utilized. A comparison between the results of an extension of a closed form solution proposed by Bray(1981), and numerical analyses with Displacement Discontinuity elements (Crouch, 1976), are presented. These analyses indicate that the stability of the wedge and the stress redistribution around the wedge upon excavation of an opening is markedly influenced by the ratio of intact rock stiffness to seam normal and shear stiffness. It is shown that the analytical solution provides a reasonable measure of the lower and upper bounds of the loads necessary to cause failure of the wedge. MODELS The problem considered (Fig. 1) is a two dimensional plane strain model containing two discontinuities. The discontinuities are symmetrically disposed with respect to a horizontal excavation which forms a wedge of rock bounded by these discontinuities. The angle of the intersecting discontinuities at the apex of the wedge is 2[a]. Mechanical properties of the two discontinuities are identical, being represented by linear normal and shear joint stiffnesses Kn and Ks and angle of friction [o]. The rock wedge is loaded by an in-situ horizontal stress field [ah]

Jan 1, 1982

By D. J. McAdam, R. W. Mebs

THE technical cohesive strength of a metal means, not the interatomic forces, but the technically estimated resistance to fracture. An example of such resistance to fracture is the so-called "true" breaking stress of a tension-test specimen, the breaking load divided by the sectional area at fracture, According to the prevalent view,8 the technical cohesive strength of a metal, in any particular state as regards prior mechanical treatment and heat-treatment, is determined by a limiting value of the algebraically greatest principal stress.? In two previous papers by one of the authors,14,15 evidence was presented to indicate that the technical cohesive strength of a metal cannot be represented by a single stress value, but that it comprises an infinite number of values corresponding to the infinite number of possible combinations of the principal stresses. The technical cohesive strength thus comprises an infinite number of technical cohesion limits, each representing a specific stress combination at fracture. In the same papers, evidence was presented that plastic extension causes a continuous increase in the technical cohesive strength. Such a variation is not in accordance with the prevalent view that plastic extension first increases, then decreases, the technical cohesive strength.8 In this paper, as in the previous papers,14,15 the algebraically greatest principal stress will be designated S1, the least principal stress will be designated S3, and the intermediate principal stress will be designated S2. The technical cohesion limit under polarsymmetric tension (S1 = S2 = S3) will be termed the "disruptive stress," and the cohesion limit under unidirectional tension (S2 and S3 = o) will be termed the "severing stress." 14,15 The yield strength of a metal, according to the generally accepted theory, may be represented by a constant value of the shearing-strain energy, and hence by a constant value of the sum of the squares of the three principal stress differences. In the second of the previous papers,"' however, evidence was presented that the limiting yield stress decreases with increase in the volume stress, the algebraic average of the three principal stresses.* This influence of the volume stress becomes prominent only in the field of triaxial tension. In the two previous papers, 14,15 diagrams were presented to show the variation of the technical cohesion limit, yield stress, and ultimate stress with the combination of principal stresses and with plastic extension. Those diagrams and the resultant conclusions are derived from experimental data obtained by other investigators. They are based chiefly on results of tension tests

Jan 1, 1943

By G. K. Williams

The continuous process of lead refining as at present operated at the Port Piric plant of The Broken Hill Associated Smelters Proprietary Ltd. was a development from investigations conducted in connection with the ordinary Parkes desilverizing process. It is not proposed here to discuss the theoretical considerations involved in continuous desilverizing because this aspect has already been dealt with in previous publications.1 Continuous Softening Process For economical desilverization of lead bullion, the bullion must first be subjected to refining processes for the removal of such impurities as copper, sulphur, arsenic, antimony and tin. This refining is effected by first drossing to remove copper and sulphur and then preferentially oxidizing the arsenic, antimony and tin from the bullion in the softening process. The theoretical basis of the continuous softening process is illustrated by the portion of the Pb-Sb-O ternary equilibrium diagram shown in Fig. 1. Under conditions of complete liquefaction, metal of the composition of softened bullion is in equilibrium with an oxide slag containing about 9 per cent antimony. In practice, of course, arsenic also is always present, and while the 0Pb-Sb-As-O quaternary system has not been worked out in detail, it has been found that in softening drossed smelter bullion of the composition produced at Port Pirie, arsenic is always reduced to 0.001 per cent or less when the antimony in the bullion is reduced to a satisfactory figure. In the operation of the continuous softening process, a two-phase system of a bullion low in arsenic and antimony and an oxide slag relatively high in those components exists in equilibrium. To this system is added continuously a bullion containing 0.2 per cent As and 0.8 per

Jan 1, 1937

By L. C. Raymond

Valuations in the mineral industry differ from those of other enterprises because mines and oil wells have a definitive life so cannot be considered a perpetuity. This requires that in any mineral-property evaluation the recovery of invested capital is necessary during the life of the property. Capital writeoffs for nonextractive industries are assumed to be continuously plowed back to sustain the operation and produce yields on the capital invested. The extractive or mineral industry, however, generally attempts to return to the investor both interest and principal during the life of a property. Normally this is done currently and the dividend includes both items. Where the mineral properly possesses large reserves and the life factor approximates a perpetuity, the return on investment is generally comparable to that of industrial stocks. The valuation of a mineral property, at best, is based on educated estimates and judgment factors. This is particularly true as it relates to estimating selling prices over a long term or assessing the quality of management. Also, it is possible to make various assumptions as to rapidity of working out the deposit, varying time for start-up of operations, varying earning rates, so as to obtain different results with the same basic facts. Thus it is not surprising that two engineers, irrespective of their abilities, may not agree exactly even when given the same facts, but their results should be close enough to be used in establishing a fair value for trading purposes. The valuation is no better than the source of basic data and the soundness of judgment factors. Fundamentally the basic principles of mineral valuation are similar for base metals, sulphur, oil, or any other mineral. Each mineral, however, requires an engineer to have a knowledge of such factors as its occurrence, distribution, mining and processing methods, and marketing problems in order to gather and analyze all the facts and data that have a bearing on the earning potential of the property. PRESENTVALUEOFAMINERALPROPERTY In essence the present value of a mineral property is a sum of money in today's dollars that future earnings from the property are worth. It differs

Jan 1, 1959

By T. D. Yensen

In the investigation of the magnetic properties of iron-nickel alloys,' it was found necessary in order to make the alloys forgeable, or malleable, to add small quantities of some other element. Iron-nickel alloys have been known for nearly a century, but have been made in commercial quantities only since 1885. Their remarkable mechanical properties were disclosed by Riley in 1889 and from that time on a large amount, of research work has been done both to discover new properties and to correlate the results obtained.2 Lately the Bureau of Standards has collected the published data in a special circular" giving in compact form an account of the properties of the iron-nickel alloys. It also contains a clear historical sketch of the development as well as a selected bibliography. The chief difficulty with the development of iron-nickel alloys was that the "pure" alloys do not forge readily. The addition of small amounts of manganese, however, made the alloys forgeable, and manganese has therefore come to be regarded as a necessary constituent of nickel steels. The present paper shows to what extent manganese is needed for various nickel contents and also what is the effect of other alloying elements on the forgeability. It also touches upon the cause of forgeability but refers to other sources for more exhaustive treatises on the subject. The alloys were prepared by melting electrolytic iron and electrolytic nickel with or without other alloying elements in the desired proportions in a magnesia crucible in a vacuum furnace under a pressure of 1 mm. mercury. The ingots, weighing about 2 kg., were allowed to cool in vacuo. If pipes or blowholes were present, the ingots were cut in such

Jan 1, 1922

By T. D. Yensen

In the investigation of the magnetic properties of iron-nickel alloys,' it was found necessary in order to make the alloys forgeable, or malleable, to add small quantities of some other element. Iron-nickel alloys have been known for nearly a century, but have been made in commercial quantities only since 1885. Their remarkable mechanical properties were disclosed by Riley in 1889 and from that time on a large amount, of research work has been done both to discover new properties and to correlate the results obtained.2 Lately the Bureau of Standards has collected the published data in a special circular" giving in compact form an account of the properties of the iron-nickel alloys. It also contains a clear historical sketch of the development as well as a selected bibliography. The chief difficulty with the development of iron-nickel alloys was that the "pure" alloys do not forge readily. The addition of small amounts of manganese, however, made the alloys forgeable, and manganese has therefore come to be regarded as a necessary constituent of nickel steels. The present paper shows to what extent manganese is needed for various nickel contents and also what is the effect of other alloying elements on the forgeability. It also touches upon the cause of forgeability but refers to other sources for more exhaustive treatises on the subject. The alloys were prepared by melting electrolytic iron and electrolytic nickel with or without other alloying elements in the desired proportions in a magnesia crucible in a vacuum furnace under a pressure of 1 mm. mercury. The ingots, weighing about 2 kg., were allowed to cool in vacuo. If pipes or blowholes were present, the ingots were cut in such

Jan 1, 1922

By Thomas Darlington

THE obligation of an employer to the State requires certain things of him as matters of good citizenship: for instance, that his workmen shall have a living wage, that child labor shall not be employed, that injuries from accidents shall not- make workmen a charge upon the State, and that the laborer's children shall have opportunity for education and to become good and useful citizens. Affairs of this kind are not taken up as philanthropy, for the officials of a corporation or a large manufacturing concern may not feel at liberty to spend the funds of their company as prompted simply by motives of kindliness; but they may spend company money on such matters because it is good business. For years, the poisonous effects of lead, phosphorus and dust have been emphasized in books on industrial hygiene and their elimination has been urged; but the more important and everyday physiology of the workman himself has been neglected. Part of my object in writing this paper is to show how our knowledge of physiology may be applied to working conditions in everyday life. In the interest of industrial laborers, accident compensation laws have been enacted in 33 States. This has been carried forward rapidly, because it has been shown that it pays both employer and employee. A further step is the recognition of sickness and disablement independent of accidents, not only because of their immediate cost to the worker and to the employer, but because continued efficiency in work and business depends largely upon health. Some measure of the importance of health in industry can be gained by the knowledge that records kept by some companies which now make this the subject of careful inquiry show that the time lost by employees, through illness; is several times as much as that lost as the result of industrial accidents. It is true that accidents frequently result in permanent disability or death, but it is equally true that illness is also a cause of permanent disablement or death. Thus the chief difference is that the loss to the employee through accidents occurring in the course of his employment is now generally recognized as a cost

Jan 2, 1918

By G. Townsend Harley

STOPING methods in which shoveling plays an important part are gradually being replaced by other and cheaper methods. But there will always be considerable shoveling done underground in stopes as well as in drifts, tunnels, urinzes, and shafts. At the mines of the PhelpsDodge Corporation at Tyrone, N. M., the cost of shoveling in all stopes in 1917 amounted to 24c. per T. In the top-slice stopes for the same period, it cost 27 c. per T. or 16 per cent, of the total cost of these stopes. The tonnage for shovelers from all stoping was 9.3 T. per man, and for topslicing 8.2 T. per man. These stopes were not unduly hot, and there was not more than the usual amount of timber to interfere with the work of the men. The tonnages obtained per shoveler were considered low; first, because of a poor grade of Mexican labor, many of the men having come in from railroad grading camps; and second, because of a poor spacing of raises, especially in the top-slice stopes, where, in general, they were spaced 25 ft. by 66 ft. (7.6 by 20.1 m.) centers. The average wage per laborer shift was $2.67 during the year. It was thought, however, that even under these conditions the men were not producing the tonnage that they should, so, with the consent of the management, the writer undertook to determine how the general efficiency of the underground shoveling could be improved. No predetermined plan for conducting these experiments was arranged because we had no definite ideas as to the scope of the work or the number of elements into which the investigation would resolve itself, before all of its phases could be determined. We were sure, however, that any work that would thoroughly cover the ground would have to be in the nature of a systematic time study, combined with a course of instruction in correct shoveling methods and adequate and intelligent supervision of the work. Two or three companies in the Southwest have done some work to determine the proper shovel to be used undcrground, but so far as is known the work has been limited to equipping certain parts of their mines with a particular type and size of shovel and thereafter watching the cost and efficiency records. In each case it seems to have been the shovel that held the 21-lb. (9.5-kg.) load that gave the bcst results. Excepting personal communications from these companies, the only data available on scientific shoveling are contained in F. W. Taylor's book, "The Principles of Scientific Management," and D. J. Haucr's article, in The Contractor for March 29, 1918, "A Hundred Hints for Shovelers." This paper discusses and draws conclusions from several thousand time-study readings, taken both on the surface and in the mines for nearly a year. A sufficient number of readings were taken on each factor in the problem for the plotting of curves of the performances and to obtain accurate indices of the work to be expected from this class of labor. The work is not as complete in all of its details as we would like to havc it, because we were forced to stop the work temporarily, owing to the numbcr of men going into the National service and our inability to get others who could make time studies. The results obtained so far, however, have been of such a startling nature that we have decided to submit them at this time, subject to future modification. It is hoped, also, that a free discussion of this paper will lead to a disclosure of any errors that may have becn embodied and offer some valuable suggestions for the conduct of future work.

Jan 1, 1920

By John Griffen, David H. Davis

Much of the ground to be covered by this paper was ably covered by a paper presented by Messrs. Morrow and Jordan1 before a joint meeting of the Iron and Steel Section of the Engineers Society of West-ern Pennsylvania and the A.I.M.E. Pitts-burgh Section at Pittsburgh in the spring of 1940. As that paper was not published, the present authors have availed them-selves of Mr. Morrow's kind permission to use information given therein. Similar figures for the latest years available have been added to many statistics originally presented. It is unfortunate that Mr. Jordan's death removes his stimulating guidance and help, which the authors would have welcomed and have found invaluable in the past. One interested in the Pittsburgh seam should not fail to read the exhaustive and authoritative paper by Eavenson2 presented in 1938. As Allegheny, Fayette, Greene, Washington, and Westmoreland Counties contain practically all the reserves and furnish nearly all of the production from the Pittsburgh seam in Pennsylvania at the present time, this area only is intended when reference is made to the Pittsburgh seam in Pennsylvania. On much of the seam in Greene and Washington Counties, which contain a large proportion of the total reserves, insufficient data are available to determine the detailed characteristics of the seam with any degree of finality. It is hoped that the data presented here will fairly well indicate the probable characteristics. Economic Importance of the Pittsburgh Seam The Pittsburgh seam in Pennsylvania is of primary importance as a coal resource, not only because of its substantial reserves but because it contributes such a large proportion of the coal used in the country and an even larger proportion of that used in the manufacture of coke. Mr. Ashley3 placed the estimated recoverable reserves (1935) of the Pittsburgh coal bed in Pennsylvania at 7,500,000,000 tons.* Although a considerable portion of this tonnage is not now suitable for coking coal, because of its high sulphur content, undoubtedly the supply of coking coal will last for many years and that not suitable for coking will furnish industry with an ample supply of energy. In attempting to assess the contribution of the Pittsburgh seam to total coal production and to that of coal used in making coke, one finds that the statistics published annually by the U. S. Bureau of Mines, Minerals Yearbook, do not give tonnages classified as to seams but only as to districts or states and counties. However, it happens that, at present and during much of the

Jan 1, 1944

By David H. Davis, John Griffen

Much of the ground to be covered by this paper was ably covered by a paper presented by Messrs. Morrow and Jordan1 before a joint meeting of the Iron and Steel Section of the Engineers Society of West-ern Pennsylvania and the A.I.M.E. Pitts-burgh Section at Pittsburgh in the spring of 1940. As that paper was not published, the present authors have availed them-selves of Mr. Morrow's kind permission to use information given therein. Similar figures for the latest years available have been added to many statistics originally presented. It is unfortunate that Mr. Jordan's death removes his stimulating guidance and help, which the authors would have welcomed and have found invaluable in the past. One interested in the Pittsburgh seam should not fail to read the exhaustive and authoritative paper by Eavenson2 presented in 1938. As Allegheny, Fayette, Greene, Washington, and Westmoreland Counties contain practically all the reserves and furnish nearly all of the production from the Pittsburgh seam in Pennsylvania at the present time, this area only is intended when reference is made to the Pittsburgh seam in Pennsylvania. On much of the seam in Greene and Washington Counties, which contain a large proportion of the total reserves, insufficient data are available to determine the detailed characteristics of the seam with any degree of finality. It is hoped that the data presented here will fairly well indicate the probable characteristics. Economic Importance of the Pittsburgh Seam The Pittsburgh seam in Pennsylvania is of primary importance as a coal resource, not only because of its substantial reserves but because it contributes such a large proportion of the coal used in the country and an even larger proportion of that used in the manufacture of coke. Mr. Ashley3 placed the estimated recoverable reserves (1935) of the Pittsburgh coal bed in Pennsylvania at 7,500,000,000 tons.* Although a considerable portion of this tonnage is not now suitable for coking coal, because of its high sulphur content, undoubtedly the supply of coking coal will last for many years and that not suitable for coking will furnish industry with an ample supply of energy. In attempting to assess the contribution of the Pittsburgh seam to total coal production and to that of coal used in making coke, one finds that the statistics published annually by the U. S. Bureau of Mines, Minerals Yearbook, do not give tonnages classified as to seams but only as to districts or states and counties. However, it happens that, at present and during much of the

Jan 1, 1944

By R. L. Bleifuss

The object of this study was to evaluate the oxidized taconites of the western Mesabi iron range and to establish a correlation between the various basic taconite types and their concentratability. The initial work included a study of the original mineralogical and stratigraphic facies of the fresh taconite and traced the oxidation and leaching patterns developed during the conversion of this material to oxidized taconite. Subsequent studies have extended this work to include the semitaconites and also the wash and heavy media ore types widely developed in the area. Each basic original mineralogical facies or taconite type produces during alteration an equivalent secondary oxidized facies which has a unique mineralogical composition and texture. These control the concentratability of the oxidized taconites. Actually the influence of the original mineralogical composition of the iron formation extends even further and determines whether the most likely product of oxidation and leaching will be a wash ore or a heavy media ore and even to the direct shipping ores where the ratio of hematite to goethite is largely determined by the original taconite type. The relationship between original taconite, oxidized taconite, semitaconites, and wash and heavy media ores is briefly summarized in Table I. The terms are not precise and in some instances tend to overlap. The table is intended to point out only the essential differences between the various materials. The original taconite was dominantly composed of mixtures of magnetite, iron carbonate, iron silicate, and quartz (chert). In a few thin stratigraphic units, hematite was present as an original constituent. The alteration of the original taconite to oxidized taconite has resulted from the circulation of ground waters through an initial fracture system related to minor structures in the iron formation. The chemical reactions have involved the oxidation and decomposition of original minerals such as magnetite, iron carbonate, and iron silicates to hematite or goethite. The alteration at this early stage is characterized by pseudomorphic replacement of the original minerals by oxidation products although retaining the major textural features of the original taconite. There was very little secondary migration of iron at this stage and the total iron content of the rock has been only slightly increased. Further alteration of this material to form a semi-taconite, a wash or a heavy media ore, involves extensive removal of silica in solution and significant redistribution of iron units. Wash and heavy media ores are developed by the growth of coarse secondary iron layers, dominantly goethite, coupled with the removal of silica in solution and decomposition of the cherty layers. This paper is concerned primarily with the materials classified as oxidized taconites which are characterized by oxidation of the original mineral constituents with little secondary enrichment. The area studied, shown on the index map, Fig. 1, extends some 30 miles along the strike of the Biwabik formation roughly from Hibbing to Coleraine. This study was greatly facilitated by the basic stratigraphic and mineralogical studies of Gruner1 and white2. The bulk of the material in this presentation represents a portion of the author's contribution to a study sponsored by the Great Northern Railway on the oxidized taconites of the western Mesabi.3 METHOD OF APPROACH A total of 106 drill holes, representing some 30,000 ft of drilling, were examined and sampled. The drill holes were logged and some 1500 composite samples were prepared for chemical analysis and bench scale metallurgical tests. These samples were analyzed for total iron and ferrous iron; and magnetite iron was determined by a standard Davis tube test at minus 200 mesh. Standard reduction roast tests using 150-gram samples of minus 10 mesh material were made on these 1500 composite samples with a mixture of H2, CO2, N2, and H2O at a temperature of 650°C. This roasted material was pulverized through 150 mesh and concentrated in the Davis tube. The iron recoveries and concentrate grades obtained on the roasted products were used to assess the concentratability of the oxidized taconites. Detailed mineralogical work was done on thin sec-

Jan 1, 1964

By Leonard C. Grimshaw

The idea of bonding two dissimilar ferrous metals, and making use of both, is an old one. Tips have been brazed onto tool shanks for many years. The bonding of larger pieces to form whole bars and sheets has also been accomplished, but has received little attention in the technical literature, although a number of patents have been issued covering various methods for its accomplishment. There are three main motives behind the manufacture of composite steels. One is that the physical properties of one steel may supplement those of another; a useful, but at the same time, hard, brittle steel may be backed by a soft ductile one, or a stainless steel may be backed by a steel possessing greater strength. Another motive is direct lowering of cost; an expensive steel may be backed by a less expensive one, bringing down the cost of the piece as a whole. The third motive is an indirect lowering of cost, as when a useful steel is backed by a steel that is easier to machine, so that machining cost on a finished product is lowered considerably. Often more than one of these motives lead to a decision to use a composite steel. Previous Methods There are two methods in use that result in tolerably good bonds between ferrous metals: (1) the casting method, and (2) what we shall call the "heat-pressure" method. This "heat-pressure" method covers processes in which the bond is made between two prepared surfaces by heating them and then applying pressure. Usually sufficient pressure must be used to produce appreciable spread and elongation, or else we arc merely brazing and not truly welding. Casting methods for welding together ferrous metals have been used more than 74 years, and are described in the technical literature as applied

Jan 1, 1936

By Leonard C. Grimshaw

The idea of bonding two dissimilar ferrous metals, and making use of both, is an old one. Tips have been brazed onto tool shanks for many years. The bonding of larger pieces to form whole bars and sheets has also been accomplished, but has received little attention in the technical literature, although a number of patents have been issued covering various methods for its accomplishment. There are three main motives behind the manufacture of composite steels. One is that the physical properties of one steel may supplement those of another; a useful, but at the same time, hard, brittle steel may be backed by a soft ductile one, or a stainless steel may be backed by a steel possessing greater strength. Another motive is direct lowering of cost; an expensive steel may be backed by a less expensive one, bringing down the cost of the piece as a whole. The third motive is an indirect lowering of cost, as when a useful steel is backed by a steel that is easier to machine, so that machining cost on a finished product is lowered considerably. Often more than one of these motives lead to a decision to use a composite steel. Previous Methods There are two methods in use that result in tolerably good bonds between ferrous metals: (1) the casting method, and (2) what we shall call the "heat-pressure" method. This "heat-pressure" method covers processes in which the bond is made between two prepared surfaces by heating them and then applying pressure. Usually sufficient pressure must be used to produce appreciable spread and elongation, or else we arc merely brazing and not truly welding. Casting methods for welding together ferrous metals have been used more than 74 years, and are described in the technical literature as applied

Jan 1, 1936

By Ernest Burchard

FLUORSPAR is found in most of the states from the Rocky Mountains westward, and commercial production of the mineral has been reported from Arizona, Colorado, Nevada, New Mexico, Utah and Washington. The map in Fig. 1 indicates the general distribution of many of these deposits but it is by no means complete. In the summer of 1926 the writer examined certain deposits of fluor-spar in Arizona, California, Colorado, New Mexico and Washington; in November, 1927, revisited the Jamestown, Colo., district, and in earlier years examined deposits in Colorado and New Mexico. Based on notes of his own and. on descriptions and other data by H. A. Aurand, H. W. Davis, R. B. Ladoo, V. C. Heikes, W. D. Johnston, Jr., and by producers of fluorspar, he prepared the following brief descriptions of deposits and estimates of reserves of fluorspar, originally for the use of the subcommittee on fluorspar of the Joint Committee on Foreign and Domestic Mining Policy and on Industrial Preparedness respectively of the Mining and Metallurgical Society of America and the American Institute of Mining and Metallurgical Engineers. Descriptions of many fluorspar deposits in various western states and districts have been published. It is not feasible to summarize this literature here, but the appended bibliography will indicate to the interested reader what papers are available.

Jan 1, 1933

By M. G., Corson

1. In addition to the alloys of copper with iron previously found by Hanson and Ford to show an increase in the concentration of the alpha range with increase in temperature the following binary and ternary systems have been found by the author to exhibit: the same feature: (a) Copper-chromium. (b) Copper-cobalt. (c) Copper-silicon. (d) Copper-nickel-silicon and its pseudo-binary section Cu-Ni2Si (formula of compound definitely established). (e) Copper-cobalt-silicon and its pseudo-binary section Cu-Co2Si (formula of compound established with some probability but not as definitely as for Ni2Si). (f) Copper-chromium-silicon; formation of a compound definitely established (compare Figs. 1 and 2). The formula of this compound may be either Cr2Si or Cr3Si. (g) Copper-iron-silicon; presence of a phase containing both iron and silicon established in an indirect way only. No definite microconstituents observed. 2. RANGES OF SOLID SOLUBILITY (percentage at various tempera¬tures). (a) For copper-chromium: 0.8 at 1000° C.; 0.5 at 900° C.; 0.25 at 800° C.; 0.05 to 0.1 at 500° C. (b) For copper-cobalt: 3.4 at 1000'C.; 2.4 at 900'C.; 1.7 at 800'C.; 0.9 at 600°C.; 0.35 at room temperature. (c) For copper-silicon (Fig. 3) : 6.8 ± 0.1. per cent. at 800° C.; 3 per cent. at 400° C. and probably below 2 per cent. at room temperature if sufficiently long annealed. (d) For copper-cobalt silicide: 3.3 at 1000° C.; 2.4 at 900° C.; 1.6 at 800° C.; 0.7 at 600° C.; 0.3 at 300° C. (e) For copper-nickel silicide (Fig. 4): 8.2 at 1000° C.; 5.5 at 900° C.; 3.6 at 800° C.; 1.6 at 600° C.; 0.7 at 300° C.

Jan 1, 1927