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By Hans Chr Andersen

Almost every form of iron ore and carbon material has been used as a raw material in the production of pig iron in electric reduction furnaces. Experience derived from the operation of the large 33,000-kva. Tysland-Hole furnaces, however, indicates that production results are very much influenced by the raw material conditions. The author presents the principle pattern of the metallurgical structure of the interior of an electric pig iron furnace. On the basis of this, he discusses the variations of electrical and metallurgical conditions for the process which will take place with changing raw materials. The formation of a coke bed underneath the electrodes, and its influence on the furnace operation, is illustrated. Quality and grain size of the coke added to the charge will influence the build-up of the coke bed and will thereby also affect the electrical re-''Elektrokemisk A/S, Oslo, Norway. resistance and reduction potential in the furnace.

Jan 1, 1963

By Granholm S

The current emphasis within the mining industry to reduce the cost of production has stimulated interest in the fields of maintenance and operational reliability of capital intensive mining equipment. From an economic point of view, high reliability is desirable to reduce the maintenance costs of the systems. Two graphical methods consider reliability analysis. The first one, the method of Total Time on Test (177)-plotting deals with the reliability data which are free from trend and serial correlation. The second method which is based on time dependent modelling approach deals with the data which are not free from trends and serial correlation. The examples show how these graphical methods can be used to calculate the optimal maintenance intervals for components or systems.

Jan 1, 1991

By D Cotnoir, Q Liu, D Richard, M Ourriban

The difficulty in fine particle flotation has been attributed, among other things, to a low bubble-particle collision efficiency. Many technologies have been developed which aim at increasing bubble-particle collision efficiency, either by generating micro bubbles or by enlarging particle sizes. However, commercial applications of these technologies are limited. Over the last five years COREM has been actively testing fine particle froth flotation technologies with the objective of commercialisation. Several fine particle flotation technologies, such as dissolved air flotation, electro-flotation, floc flotation, selective flocculation-flotation and carrier flotation, were tested on both single minerals and ore samples in order to identify the reasons that prevented these technologies from being used on a commercial scale. It was found that the two most noticeable factors that prevented the successful application of these technologies were: Mechanical entrainment of fine gangue minerals. This was a general problem in fine particle flotation, but was aggravated by these technologies that either generated micro bubbles or enlarged the sizes of hydrophobic particles. Oxidation of (sulfide) minerals that resulted in hydrophilic oxidation product coatings. The oxidised fine particles could not be recovered by these fine particle flotation technologies effectively. Solutions to the two problems, ie gangue entrainment and fine particle oxidation, were proposed and tested. It seems that polymeric depressants with both depression and flocculation functions could significantly reduce gangue entrainment, and hydrophilic surfaces of oxidised fine particles could be modified by high intensity conditioning or controlled sulfidisation, thus increasing the recoveries of fine valuable minerals. The improved fine valuable particle flotation and reduced fine gangue entrainment along with fine particle flotation technologies resulted in much improved flotation separation of fine particles.

Jan 1, 2005

By L. R. Jackson

THE idea presented in this paper is that the capacity of a metal for plastic flow before rupture is dependent on the type of stress system applied-that is, the absolute magnitude of the stresses are unimportant provided that they are large enough to produce continued flow; the important factor is the "type" of stress system. A term called the "triaxial stress ratio" is defined in such a way that this ratio can be used to characterize the "type" of system. The paper is divided into three sections. The first section discusses means of representing the effect of complex stresses on plastic flow and defines "triaxial stress ratio"; the second section discusses various methods of' obtaining complex stress distribution. The third section gives some experimental results showing the effect of types of complex stress on the capacity of various metals for flow. An appendix discusses some details on methods of obtaining complex stresses. I. REPRESENTATION OF COMPLEX STRESS SYSTEMS AND THEIR EFFECT ON PLASTIC FLOW Representation of Stresses It is convenient to have a consistent system of notation that will allow the representation of the entire range of complex stresses from hydrostatic compression to hydrostatic tension on plastic flow in a single diagram. Such a system is provided by making use of the fact that any complex stress system can be resolved into a hydrostatic tension or compression and a pure shear. Consider a stress system having the principal stresses [S1 S2 5 S3]. This system can be resolved into a new system consisting of the three components [ ] and three pure shears. If Sm is positive, the net stress effect is hydrostatic tension; if it is negative, the effect is hydrostatic compression. In order to produce a systematic notation, a quantity that will be referred to as the "triaxial ratio" will be defined by the equation [ ] Sm is given by Eq. I and S1 is the absolute magnitude of the largest principal stress without regard to sign. Table I lists the triaxial ratios for various common systems. [ ] Representation of Strains Strains will be plotted as "true" strains according to the system proposed by Ludwik.1

Jan 1, 1944

By Scott W. Hazen

COMPREHENSIVE summary is presented of results of several years of research at the Bureau of Mines Mining Research Center at Denver on adapting and applying techniques of statistical analysis in mine and mineral-deposit sampling and in computing grade and tonnage of ore for a mineral deposit. In addition to elementary statistical theory the material presented in the bulletin includes: (1) Certain special statistical techniques that have been found useful in mining applications; (2) problems, implications, and limitations that may be encountered in applying these techniques in mine sampling and evaluation; and (3) numerous examples to demonstrate application of the theory and techniques.

Jan 1, 1967

By W. S. Ayres

BACK in the early nineties the old Dickerson iron mine in Morris county, N. J., was operated by a vertical shaft 850 ft. deep and by a continuing slope for more than 1000 ft. more 011 an incline of 65", together making the vertical depth about 1800 ft. I was then the general superintendent there. This mine, named for a former governor of New Jersey, had been worked more or less continuously from long before the American Revolution and up to this particular time. The pumping equipment was of the old-time Cornish type, with its long pump-rods running down the vertical shaft and the slope to the sump at its bottom. It was operated by a large flywheel engine in the engine room and all angles were turned by the usual bobs. Saturday was the day fixed for lowering the "suction" into the deepened sump at the bottom of the advancing slope. The mine foreman had gone down with the morning shift to superintend this very vital and particular work, which consisted not only of lowering the "suction" into the sump immediately after the pump had been stopped, but of securing it to the rock and putting in the added sections of column-pipe and of tightening up the numerous bolts at their joints, all before the water rose to the point of working. At an appointed time during the forenoon I had agreed to go down into the mine and join the mine foreman in consultation over any difficulties that might have arisen. At the time agreed I went down by the cage to the bottom of the vertical 850-ft. shaft, and then by ladders down the slope for over 1000 ft. more.

Jan 1, 1930

By Bernard Moore

AT present the demands of the United States for strontium are met by imports from Germany, England and Canada, which vary considerably in proportions of ore and finished salts, in tonnage and in value. Statistics for the period 1926-1932 are given in Table 1. Domestic deposits are TABLE 1.-Strontium Imported into the United States, 1926-1932a Ore Chemicals Year Short Tons Value Pounds Value 1926 2,200 $58,159 5,433,044 $115,436 1927 1,356 58,711 4,233,816 149,383 1928 759 31,157 3,380,464 136,561 1929 973 45,505 4,578,327 196,233 1930 220 10,459 2,153,788 104.807 1931 (260 lbs.) 123 1,742,714 83,564 1932 5 276 469,481 20,910 a Mineral Industry (1934) 42, 61. known in many states, but the, larger and purer ones are in the West, particularly in the desert region of southeastern California and western Arizona. These deposits are large enough to command interest, par-ticularly in consideration of future cheap power at the Boulder Dam. The deposits described in this paper were examined during an investi-gation of the mineral resources of the Boulder Dam region by the United States Geological Survey for the United States Bureau of Reclamation in the spring of 1934. Mr. D. F. Hewett, who had general charge of the investigation, Mr. W. T. Schaller and Mr. M. I. Goldman contributed many helpful suggestions. Mr. N. H. Harshman assisted efficiently during the field work.

Jan 1, 1935

By Benjamin Moore

AT present the demands of the United States for strontium are met by imports from Germany, England and Canada, which vary considerably in proportions of ore and finished salts, in tonnage and in value. Statistics for the period 1926-1932 are given in Table 1. Domestic deposits are TABLE 1.-Strontium Imported into the United States, 1926-1932° Ore Chemicals Year Short Tons Value Pounds Value 1926 2,200 $58,159 5,433,044 $115,436 1927 1,356 58,711 4,233,816 149,383 1928 759 31,157 3,380,464 136,561 1929 973 45,505 4,578,327 196,233 1930 220 10,459 2,153,788 104,807 1931 (260 lbs.) 123 1,742,714 83,564 1932 5 276 469,481 20,910 a Mineral Industry (1934) 42, 61. known in many states, but the larger and purer ones are in the West, particularly in the desert region of southeastern California and western Arizona. These deposits are large enough to command interest, par-ticularly in consideration of future cheap power at the Boulder Dam. The deposits described in this paper were examined during an investi¬gation of the, mineral resources of the Boulder Dam region by the United States Geological Survey for the United States Bureau of Reclamation' in the spring of 1934. Mr. D. F. Hewett, who had general charge of the investigation, Mr. W. T. Schaller and Mr. M. I. Goldman contributed many helpful suggestions. Mr. N. H. Harshman assisted efficiently during the field work.

Jan 1, 1935

By S. S. Peng

This paper presents a convenient way for the preliminary design of the shield supports. The locus equations which are applicable for all kids of shield supports are derived. These equations facilitate the statics analysis of the shields. An indirect method in determining the coefficient of friction, the external toads and their locations are also developed.

Jan 1, 1982

Kalgoorlie is the main mining centre of the Western Australian Goldfields. Its famous Golden Mile' has been noted for the exceptional width and richness of its goldtelluride lodes. Since the mid-1890s production on the major mines has been maintained practically continuously.Rich ore, though not as plentiful or as rich as formerly, is still (1948) being mined in places. Unexplored areas still remain within the main auriferous belt which offer reasonable chances of success with intensive exploration.Much detailed information has accumulated in recent years through the geological mapping of underground workings by some of the larger mining companies. The purpose of this paper is to correlate observations made in most of the accessible old and recent workings in the mines of the Lake View and Star group and elsewhere.GENERAL GEOLOGYRock TypesThe rock formations are:-1. Fine-grained (older) greenstones, locally referred to as calc schists. There were originally pillow lavas and other flow rocks of basic composition, now extensively chloritised and/or carbonated. Pillows and fragmental flow- tops are recognisable. Intercalated with flows near the top of the series are several beds of sediments.2. Graphitic slates and other more arenaceous sediments.Although referred to as slates, they are rarely more than well-bedded shales with poorly developed fracture cleavage:Thick bands of felsitic rock are found in places.

Jan 1, 1952

By S. W. Miller

DURING the examination of welds made in steel by the oxy-acetylene and electric-arc processes, the writer has met with some unusual structures, which he has not encountered elsewhere. They seem to be quite closely associated with the welding methods used, and characteristic of them, and would seem to be worth noting, especially as the references to them in the literature are few, and their explanation not clear or complete. An introductory word or two about fusion welding may not he out of place. The oxy-acetylene process is based on the great and very local heat generated by the burning of acetylene in the presence of commercially pure oxygen, the two gases being thoroughly mixed before combustion. The theoretical temperature is somewhat under 4000° C., but on account of various losses, the actual maximum temperature is probably about 3000° C. 1 The electric-arc process, using a metal electrode, which is also the filling rod, generates a still higher and more local temperature. The actual temperature of the positive crater of the carbon arc is given as 3500° C.2 No figures have been found for the temperature of the arc using a metal electrode, but it would probably not be very different from that of the carbon arc, and probably higher than that of the oxy-acetylene flame. The greater localization of the electric arc is due to the fact that it is not surrounded by a large envelope flame as well as to its higher temperature; while the oxy-acetylene white cone, or welding flame, in which the carbon of the acetylene is burned to CO, is surrounded and preceded by -a long envelope flame, itself of quite high temperature, in which the CO is burned to C02, and the hydrogen of the acetylene to

Jan 2, 1918

By S. W. MILLE

GEORGE F. COMSTOCK,* Niagara Falls, N. Y. (written discussion?).¬I have recently had the pleasure of reading Mr. Miller's interesting paper, and would like to call attention to a reference to this subject which apparently has escaped his notice. It is an abstract of a German research on the subject of nitrogen in steel, and appeared in the Iron Age of Feb. 17, 1916, page 432. Photomicrographs of needles such as Mr. Miller found in his welds are given, and their identity is discussed. The conclusion reached is that the needles are slip lines due to the brittleness of the ferrite crystals caused by their absorption of nitrogen. The deformation necessary to develop the slips is supposed to be accomplished either in cutting or polishing the microsections or by cooling strains after welding. It seems very reasonable to expect that nitrogen would he absorbed by steel in either electric or oxy-acetylene welding, and the reference I have mentioned gives instances of many unusual structures resulting from the presence of considerable nitrogen with carbon in steel. But the nitrogen is .rapidly given off from steel by ordinary annealing in air, hydrogen or vacuum, and this would explain the disappearance of Mr. Miller's needles after annealing. I think the conclusion that the needles are cementite might well be revised in view of this German work on nitrogen.

Jan 5, 1918

H. M. BOYLSTON, Cambridge, Mass.-We should feel greatly indebted to Mr. Miller for collecting this admirable series of photographs, but I cannot quite agree with his conclusions as to their significance. He apparently concludes that these needle-like constituents which he has shown in a good many cases, in the welded material at least, are cementite; that is, as we understand it, a carbide of iron. Now there seem to be

Jan 4, 1918

By Grimes, J. A.

EXTENSIVE discovery 'and rapid exploitation of orebodies within the past half century have attracted many able geologists to the mining industry and furnished them a wealth of data from which to develop theories concerning ore genesis. By tosting and elimillating theories which are not sufficiently sup- ported by fact, or which are based on inaccurate observation of field data, the trend of geological opinion has . moved strongly in certain directions until, at the present time, large numbers of geologists subscribe to a broad concept of .ore genesis that I would summarize as below:

Jan 1, 1928

Suggestions have been made at various times that there may be a recurrence of lodes similar to those at Kalgoorlie in the country to the south of the Golden Mile, but, so far as is known, there has been no geological evidence to support these suggestions apart from the possible extension of the younger quartz-dolerite greenstone in this direction.Geological mapping carried out by the writer in the Coolgardie district in 1946, provided some additional geological evidence to support this claim, and the ideas then held have since been expanded and are now considered to be sufficiently advanced to present them as concrete suggestions. As will be seen from the following pages, the critical area for lode prospecting is Hannan's Lake, where the basement rocks may include younger quartz dolerite greenstone, which, although perhaps distributed over a smaller area than at Kalgoorlie, could, on structural grounds, have a similar fracture system and similar ore deposition.There is little need to stress the importance discoveries in this area would have in prolonging the life of the field, and stimulating the post-war gold mining revival.Previous Work: Only the publications having a direct bearing on the preparation of this paper are given in the list of selected references, but the writer is very conscious of the fact that much other geological work has been carried out in the Kalgoorlie district since its discovery, by the W.A. Department of Mines, by mining companies, and others, all of which has contributed to the present knowledge of the field, and acknowledgment of the value of this work is given herewith. In presenting the suggestions in this paper a broad structural control of ore deposition is assumed, but this has already been established in other parts of the goldfields of Western Australia, including adjacent areas. In the early nineteen thirties, the Western Mining Corporation commenced work on the basis that there was a close relationship between geological structure and auriferous ore deposition, and a similar approach was first made by the Geological Survey of Western Australia in the South Yilgarn in 1935. These ideas were further developed during later surveys, particularly in the North Yilgarn and the Mount Margaret Goldfield.During the Coolgardie Survey in 1946, broad structural mapping was done in greater detail than before, and the structural ideas were implemented and further developed, leading to some success.Other work to which particular acknowledgment is given is that of Stiltwell, Gustafson and Miller, Forman, Prider and Finucane, at Kalgoorlie, and that of Honman in the Kalgoorlie-Coolgardie district, references to which are given at the end of this paper.Valuable constructive criticism of this paper has been given by Professor E. de C. Clarke and Dr. R. T. Prider, of the University of Western Australia.

Jan 1, 1950

By A. N. Mitinsky

(San Francisco Meeting, September, 1915) THE theory of elasticity, the science of the strength of materials, and all our calculations regarding engineering structures are based on Hooke's law, that in loaded bodies the deformations are, proportional to the load producing them. Without this law it would be impossible to design intelligently engineering structures such as bridges, frames, axles, etc. This being the case, the proportional limit,1 that is, the point at which deformation ceases to be proportional to load, is the most important factor in engineering design. Further, the working fiber stress should be fixed in reference to the proportional limit instead of, as is usual, in reference to the ultimate strength. The incorrect use of the ultimate strength instead of the proportional limit in setting the working fiber stress is probably clue to two reasons: (1) it is a more delicate operation to measure the proportional limit; (2) it is usually -assumed, though incorrectly, that the proportional limit is determined by the ultimate -strength. In Germany the point at which permanent set first appears is often taken instead of the proportional limit. The two points will coincide if Gerstner's law, that elastic deformations are proportional to the loads producing them both before and after permanent set, is true; and the limit of proportionality and the elastic limit or point of permanent set will both 'be represented on a stress-strain diagram, by the point at which the line ceases to be a straight line and becomes curved-or changes its inclination. It is to be further noted that the difference in definition between proportional limit and elastic limit introduces a difference in methods of determination in the testing laboratory. The German method of determining. the elastic limit by alternately loading and unloading

Jan 8, 1915

By A. N. Mitinsky

Discussion of the paper of A. N. MITINSKY, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 104, August, 1915, pp. 1697 to 1705. LAWFORD H. FRY, Burnham, Pa. (communication to the Secretary*). -The author assumes that the proportional limit and the elastic limit are coincident or very nearly so, and then further assumes that the stress corresponding to these two points is the least stress which if repeated will cause failure. The point is extremely interesting and it is to be regretted that the author did not quote experimental data to show the relation between the limit of repeated stress and the other properties of the material. The author's suggestion that a steel of poor quality may have a normal value for the yield point and tensile strength (see Fig. 2) and an abnormally low elastic limit, and that this will correspond to a low resistance to repeated stress, may account for a number of failures of axles in which the tensile tests show normal physical properties. If so and if a determination of the proportional limit would have eliminated the material before it was put into service, this determination will merit most earnest attention. It appears, however, that considerable further research is necessary before any definite conclusion as to the quality of a steel can be drawn from its proportional limit. Mr. Mitinsky's paper is extremely interesting and if it stimulates thought and work along the lines indicated, it may prove of considerable practical benefit. H. V. WILLE, Philadelphia, Pa.-The paper discusses the difference between the proportional limit, or elastic limit, and the yield point, and refers to the fact that much harm results from confusion of the terms yield point and elastic limit. Similar confusion has arisen in this country; the American-Society for Testing Materials does not even consider the elastic limit and proportional limit to be identical and recently adopted the following definitions:

Jan 12, 1915

By G. T. Swanby

Members of AIME, I read to you now a portion of a very fine business letter which we received several years ago. This letter originated in Rangoon, Burma, and reads in part: "Rest assured, if your goodselves see with us eye to eye, sure as certain we should get the business". I don't plan to give anybody "the business" today, but you can rest assured that if some of "you goodselves see with me eye to eye" on what I am about to discuss, I would be most pleased. My talk with you today will discuss the Federal Corporate income tax and its effect on our lives as engineers. In the-engineering-construction business we are faced with all the usual form of taxation which includes such items as sales tax, use tax, school tax, contractor; gross receipt tax, import duties and excise taxes, severance taxes, etc, adinfinutum.

Jan 1, 1965

By Hemingway P, Boag J

Major operating aspects of the Mary Kathleen Uranium Ltd. treatment plant are discussed with partkular reference to those which are peculiar to this operation.Problems associated with the production of a penalty free uranium oxide product are examined and the methods developed to overcome them are described in detail.INTRODUCTIONMary K,athleen Uranium Ltd. is the largest of the Australian uranium producers. The flow-sheet is based on fine grinding, standard sulphuric acid leach, ion exchange concentration, and magnesia precipitation of the final product, with certain modifications introduced as the result of pilot plant investigations at the South Australian Department of Mines Research Laboratories in Adelaide.The plant commenced operations in June, 1958, attained design tonnlige of 1,120 tons per day in September of that year and has since operated continuously with a throughput in excess of 1,000 tons per day. Pilot plant recommendations generally have been followed, and predicted results have been attained. The only exception has been the silica and rare earth content of the product produced during the early months of operation. Considerable modification of the early resin regeneration techniques resulted in the reduction of the silica content of the product to within specification limits. Research work in the ion exchange section has also resulted in the reduction of the rare earth content of the product to below specification levels. All product now being produced is completely within the agreed specification limits of impurities.

Jan 1, 1961

By John W. Fredland

Conducting mining operations under a body of Water can create hazardous conditions for miners. The potential for a sudden inrush must be considered and abnormal ground control conditions can be encountered. This paper synopsizes the factors which mine operators should take into account when evaluating whether an inrush may occur. It addresses the applicable Federal regulations and discusses some items which coal operators should consider in applying for a permit, Through collecting and analyzing the pertinent information, the likelihood of encountering problems can be judged. Through proper mine planning, the potential for creating hazardous conditions can be mitigated.

Jan 1, 1982