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By Theodore Simons

(Butte Meeting, August, 1913.) DURING the last half century a great amount of ingenuity and energy has been devoted to the invention of appliances for the recovery of valuable minerals from very fine sands and slimes. The reason for this is that in almost every dressing plant the greatest losses of values, considered relatively as well as absolutely, occur in the treatment of slimes. The natural aim of mill operators to minimize these losses has in recent years received another impetus, from the fact that the gradually diminishing occurrence of high-grade ores makes a more intense recovery of values from existing resources absolutely necessary for profitable operation. The results of such attempts are found in the appearance of a great number of machines and appliances which make it profitable to-clay to rework old dumps, containing the tailings of older processes. A constantly growing difficulty of obtaining skilled labor and the increase in wages made it prohibitory to employ those types of machines which required much attention, and in the middle of the nineteenth century the various concentrating tables of the percussion type, which automatically discharge their products, began to take the place of the intermittent tables, on which, when the bed had reached a certain thickness, operation had to be stopped in order to allow the skimming by hand of the separate layers formed on the table. In the course of years, two general types of machines evolved for the treatment of fine sands and slimes : The so-called concentrators and vanners, on the one hand, and the buddies and round tables on the other.1 For the profitable treatment of the very finest slimes, round tables have as a last resort proved more satisfactory and economical than other machines.

Jan 7, 1913

By John J. Egan, W. D. Forging, Walter Crafts

Although many elements reduce the tendency to porosity in steel castings, manganese, silicon, aluminum, calcium, titanium and zirconium appear to be most generally suitable for the purpose. The manganese and silicon contents are usually maintained in a fairly constant range. Silicon-killed castings often are made to be sound with little or no addition of the stronger degasifiers. In many cases, however, it is more practical to utilize the stronger degasifying elements, aluminum, calcium, titanium and zirconium. Since they greatly modify the composition, shape, and distribution of the nonmetallic inclusions, and thereby the ductility, the strong deoxidizers must be used in such a way as to form the least harmful types of inclusions. As the reasons for failure always to obtain good results have not been obvious, an effort has been made to determine the mechanism of solidification of steels deoxidized to produce certain types of inclusions. Diagrams representsing the mechanism of their formation have been constructed from the appearance of the nonmetallic constituents and have not only illustrated the limiting features of specific deoxidizing treatments with respect to inclusion formation and ductility, but have also indicated a relation between inclusions and resistance to hot tearing. Three different types of deoxidation treatment have been used for obtaining sound castings with relatively high ductility. The first method is to make and cast the steel under such conditions that deoxidation with silicon and a small addition of a strong deoxidizer assures soundness. The effective addition that will promote soundness without causing the formation of intergranular inclusions varies with the furnace practice and composition, but may be limitled to about 0.025 per cent Al, Zr or Ti. Up to 8.10 per cent Ca and 0.15 per cent V are also used for this purpose. The inclusions in these steels are characteristically glassy silicates and round or irregular sulphides. As pointed out by Sims and Lillieqvist,1 the formation of fine intergranular inclusions, which are detrimental to ductility, limits the amount of strong deoxidizers that may be added.

Jan 1, 1940

By W. A. Krivsky, R. Schumann

Relaxation calculations were made to find the temperature distribution in the refractory wall surrounding a tuyere pipe. One set of boundary conditions approxiwated those of a standard copper converter while a second set represented a hypothetical,thermally insulated tuyere pipe. The pvonounced cooling effect of the tuyere is related to the problem of tuyere accretions and tuyere bunching. PARTICULARLY severe service conditions are encountered in the tuyere zone of a basic copper converter during the matte blow. High-temperature gradients result from the juxtaposition of the hot charge and the tuyere pipe carrying cold air. Refractory temperatures near the tuyere mouth vary rapidly with time when the blast is turned on or off. One of the most serious problems is the formation of magnetite accretions around the tuyere mouth, which occurs very rapidly under some operating conditions. As a result, continual punching of the tuyeres is necessary to maintain a satisfactory rate of converting. Thus, if some means could be devised for keeping the tuyere pipes fully open without necessity for punching, a considerable saving should result from reduction in labor cost, maintenance of full capacity operation, and reduction in refractory costs. Recent quantitative studies of the FeO-Fe,O,-SiO, system1 have shown that the solubility of magnetite in iron-silicate slags decreases rapidly with de- creasing temperature in the range of copper converting temperatures. Data taken from the previous work are shown in Fig. 1. Thus the formation of "horns" and accretions around the tuyere mouth can result simply from the freezing out of magnetite on the cooler areas of refractory immediately adjacent to the tuyere pipes. One might expect to find a correlation between the severity of magnetite formation and the area of refractory surface which is cooled below the freezing point of the slag (corresponding to magnetite precipitation). Magnetite itself has a very high melting point (1597°C) so that the accretions are for all practical purposes infusible. The accretions might be dissolved by increasing the silica content of the slag and at the same time raising the temperature, but this approach is not feasible because it results in rapid corrosion of the basic refractory lining of the converter as a whole. In order to understand better the problems involved in tuyere design and operation, it seems essential to have at least a semiquantitative idea of the thermal conditions in the tuyere zone. Accordingly, this paper presents results of thermal calculations for an idealized copper converter tuyere. These calculations follow the so-called relaxation

Jan 1, 1960

THIS chapter and Chapter 19 deal with the heat quantities involved in open-hearth steelmaking, including the thermal efficiency of the furnace as a generator of high-temperature heat, the heat storage in the steel and slag produced and in the furnace walls, and the heats of the various chemical reactions involved in combustion, in the formation of slag, and the refining of steel. The fundamental laws to be considered are the first two laws of thermodynamics as applied to problems involving sensible and potential (or latent) heat only: 1. Heat input equals heat outflow plus storage. 2. Heat may be transferred only from a hotter body to a colder one. The first of these laws relates to the various heat quantities or the heat balance of the process. No one has as yet made an open-hearth heat balance that came out almost exactly balanced. The cause probably lies in the difficulties of accurate temperature and flow-rate measurements at the high temperatures involved and the inherent complexities in flow distribution and air leakage present in any real open-hearth furnace system. Some idea of the magnitude of the heat quantities involved can be obtained by a brief, crude outline of the heat balance of a 90-ton heat of steel. We will assume a 60 to 70 per cent hot- metal charge in a fairly fast working and only moderately efficient furnace, burning fuel oil, with a fuel consumption of around 4 million Btu per net ton of ingots produced. The time from start of charge to tap is 9 hr. During this period, the oil burned represents 360 million Btu and the sensible heat in the preheated air at the port ends is 117 million Btu, so that the total heat input at the ports is 477 million Btu. Heat stored in the steel and slag at the end of the heat, plus the various amounts absorbed by certain bath reactions, amounts to a total of 195 million Btu, but 120 million of this is supplied by the heat in the hot metal and by various heat-evolving reactions in the bath,

Jan 1, 1964

By Charles W. Goodale

The purpose of this paper is to review the history of the Drumlummon, one of the famous old mines of the West. Mining engineers, when sent to examine new mines in old districts, or, to decide whether an old property, under new conditions, will pay to reopen, have had difficulty in learning anything authentic regarding workings which are under water, and historical facts about the working character of the ore, the total production, and the value of the ore with increasing depth. 'Not many years elapse after the pumps are pulled, before maps, books and records are destroyed, and the value of the publications of the Institute would be increased if they contained the history of many old mines now abandoned. The unsuccessful efforts of the writer quite recently in trying to obtain reliable information about a gold mine which was reported to have produced several million dollars between 1880 and 1888, the workings of which are now partially caved and under water, impressed upon his mind the desirability of having a permanent record of old properties. In this particular case, the owners insisted that under present conditions of improved methods of treatment —particularly by the use of cyanide, which was not an applied process when the mine was operated, the property could be made to pay a handsome profit on ore left in sight in the old workings, but no assay records could be found to confirm these assurances, and even the records of bullion shipments had been destroyed. If surveys and maps were made as the work progressed, no trace of them could be found, and therefore opening of the ground through a new shaft and drifts therefrom would be attended by some risk while exploring near the old workings. Fatal accidents by flooding under these conditions have occurred, and as an evidence that miners have fears of such dangers, it was urged upon the Mining Committee during a recent session of the Montana Legislature, by a delegation of

Jan 1, 1915

Jan 1, 1902

The ten-year "supply-demand relationship" tables in this chapter for various mineral and metal commodities have been adapted from Minerals in the U.S. Economy, compiled by the Bureau of Mines, U.S. Department of the Interior, published in 1975. Acknowledgment is made to the Bureau of Mines for compilation of the tables. [ ]

Jan 1, 1976

OUR 78th Annual Meeting was, technically and attendance-wise, one of the greatest to date. No one who came to New York's Hotel Statler had time to hear all 266 papers, or to attend all 70 sessions and 27 committee meetings, or to shake the hands of the more than 3000 engineers, educators, students and executives who attended-but no one was lost in the crowd. For crowds always dwindle down to groups of two and three and four, and those are the little sessions which make our meetings well worth attending. Herewith four pages of photographic highlights and sidelights on the February gathering.

Jan 3, 1950

By John Alden

A CONSIDERABLE PROPORTION of the tonnage of aluminum used today has at some stage during its manufacture, been rolled. I. For one, therefore, was particularly pleased to hear that this Society was to hold a symposium on rolling of nonferrous metals. Metallurgists can well afford to direct their close attention to the metallurgy involved in this important operation. To one who has seen today's high production rolling mills for aluminum it is difficult to realize that the first aluminum rolling mill For sheet was installed a scant 55 yr ago, in 1892. This mill was a three-stand train of 2-high mills, driven by a steam engine and was operated for many years successfully rolling aluminum sheet. Mills for the rolling of aluminum rod were installed in 1899 to meet the demand For manufacture of electrical conductor wires and cables. Bars and rods in straight lengths were also made. While these mills were the first built for rolling aluminum products of these types some rod had previously been rolled on brass and copper mills. Not until many years later, in 1929, however, Were facilities provided for the rolling of structural shapes, such as I-beams and channels. Growth of the aluminum sheet business and the necessity for economical manufacture soon brought the realization of the economies resulting From-the rolling of sheet in long lengths and coiling it. A five-stand continuous mill driven by a steam engine, was in operation late in 1907. This took aluminum slabs coating from

Jan 1, 1948

Jan 1, 1887

By Louis A. Panek

Ground movements in the zone adjoining an active cave were measured at four sites in the San Manuel Mine. Measurements were made to detect extension and inclination, basic components of displacement, which can readily be duplicated by mine personnel using relatively simple equipment. The displacements demonstrated the development of a zone of strain relief surrounding the active cave, within which the ground tends to migrate toward the cave, and extension cracks develop tangential to the cave. This expansion of the ground surrounding an active cave can be exploited to promote future caving; it also creates special problems with respect to the design of an effective ground support system for mine openings in the production area.

Jan 1, 1981

By A. E. Gibson

A new feature in coal mining, where the coal is to be conveyed from a high to a lower elevation and the topography of the country is such as to preclude surface haulage.

Jan 1, 1915

By P. W. Guild

DURING 1956 the application of geology and related scientific disciplines to the search for new mineral deposits went forward on an ever widening front. Spurred on by record-breaking consumption of many of the established commodities and new uses for minerals and metals that were hardly known a few years ago, the profession is figuratively leaving no stone unturned in the effort to insure that adequate raw material supplies will be avail- able for the future. More money was spent and more people were engaged along more lines of research than ever before. A huge project to map much of the Canadian Shield area by photogeologic methods stands at one extreme; application of isotope ratios to ore finding stands at the other; between them the more traditional techniques are being increasingly refined. In the Fiftieth Anniversary volume of Economic Geology, published late in 1955, Alan Bateman sketches the development of fundamental concepts as recorded in the pages of the journal over the first five decades. An additional 24 review articles cover individual aspects of the field and constitute a base for further advances.

Jan 2, 1957

By C. R. Forbes, J. C. Barton

Many different shapes of drill bits are in use with hammer drills, but little definite information is available whereby to judge which one of these shapes is the best. The following investigation was undertaken in order to determine what effect, if any, the shape of the cutting edge has on the cutting speed and wearing qualities of drill bits. The bits tested were those in common use, namely, the 4-point or cross bit, the 6-point bit, the Z bit and the "Carr" bit. The rock in which the tests were made was the red granite from southeast Missouri. It is a coarse crystalline granite containing an unusually large amount of quartz and is extremely hard, and on account of its uniform texture is admirably adapted to this work. While tests in other rocks might show somewhat different results, nevertheless it is the opinion of the authors that the relative cutting quality inherent in the shape of the bits would be the same in all rocks. Other qualities, such as mudding freely, freedom from fitchering, etc., might make one bit more desirable than another in softer rocks. Description" of Bits Tested 'I'he 4-point bits were the usual shaped bits commonly made on the Leyner sharpener, with 14' taper on the wings and a 90" angle between cutting edges. Some tests were run at 85 Ib. pressure with a 4-point bit made with a 50 taper on the wings; this bit was formed with the Carr bit dies. The 6-point bits were the usual shaped bits made on the Leyner sharpener. The Carr bits were made with a 5º taper and an angle of 100" between cutting edges.

Jan 1, 1918

By John S. Johnson

The maintenance cost, or renewal cost, in any preparation plant is a large item of expense and reflects in the total cost of producing and preparing the ton of coal. It is given constant study to the end that ways and means of controlling and reducing this proportion of the total cost may be developed. Study of this item of cost has proceeded along usual lines, which are: proper functioning of the maintenance organization; systematic and thorough inspection to prevent breakdonns; the making of repairs before renewals are needed; maintenance work done thoroughly the first time, instead of patching, study of parts needing frequent renewal or repairs or conditions resulting in delays, thorough knowledge of cost by the mall responsible for maintenance; and the use of special equipment and materials. This paper is to deal with special equipment and materials to reduce the maintenance cost hut before going into that I want to express an opinion on the general subject. Maintenance Organization Usually maintenance is taken care of by a group of men who perform their work on the off shift. The work is arranged by the operating official who should be thoroughly familiar with maintenance, so that materials needed may be made up for the particular job and waste of time in looking up materials be prevented. To perfect the maintenance organization, all operating attendants should be thoroughly trained to be familiar with all working parts of their equipment, to make a thorough inspection and to write out the slip for the work required. This requires job analysis, but it is worth the effort, because the attendant usually is better informed than anyone else about his particular equipment. The operating official can judge the scope of the work to direct the repair and to have material ready. Lubrication is an important item in maintenance, and a subject by itself. Usually the breaker oiler is designated to perform this task. This man should be picked for his ability and put in line for promotion to machinist. He should be trained as an inspector, as he is constantly visiting most parts of the breaker and has an opportunity to observe needed maintenance. The first thing is to lay out maintenance work and arrange to have it done; the next is to check the work and see that it has been properly done. This check should be made by the operating official, and through the attendant. The cost statement showing the various items of maintenance cost is not often understood by the man in direct charge. Cost sheets should be simplified and worked up by breaker sections; e.g., the cost of

Jan 1, 1947

By Alexander L. Field

IN a previous paper,' the experimental methods used and some of the results obtained in an extensive investigation of steels containing zirconium were described. The present paper considers in greater detail one of the most interesting of these effects, namely, the elimination of " red shortness" and the occurrence in steel of a compound of zirconium and sulfur. A consideration of the actual percentages of zirconium, manganese, and sulfur in numerous steels in the light of behavior during rolling has led to new conclusions of the most practical import regarding the reciprocal relationships of these elements. The microscopic examination of high-sulfur steels containing zirconium has also been productive of interesting results. Before discussing the experimental data in question, it may be stated, briefly, that the rettetion between zirconium and sulfur in molten steel may be represented by the simple equation, Zr + 25 = ZrS², and that the zirconium sulfide thus formed occurs in the finished steel in the form of gray-colored inclusions, closely resembling manganese sulfide and, like the latter, exhibiting plasticity at rolling temperatures. Molten steel containing zirconium retains such a negligibly small amount of oxygen in solution that the foregoing reaction goes to completion. Hot-rolling Properties of High-sulfur Steels with and without Zirconium The chemical composition of twenty-eight steel ingots embracing eleven heats made in a basic-lined electric furnace is shown in Table 1. The practice followed in the manufacture of these high-sulfur steels was described in the previous paper. Table 1 also gives the behavior of the

Jan 1, 1924

By John S. Johnson

The maintenance cost, or renewal cost, in any preparation plant is a large item of expense and reflects in the total cost of producing and preparing the ton of coal. It is given constant study to the end that ways and means of controlling and reducing this proportion of the total cost may be developed. Study of this item of cost has proceeded along usual lines, which are: proper functioning of the maintenance organization; systematic and thorough inspection to prevent breakdonns; the making of repairs before renewals are needed; maintenance work done thoroughly the first time, instead of patching, study of parts needing frequent renewal or repairs or conditions resulting in delays, thorough knowledge of cost by the mall responsible for maintenance; and the use of special equipment and materials. This paper is to deal with special equipment and materials to reduce the maintenance cost hut before going into that I want to express an opinion on the general subject. Maintenance Organization Usually maintenance is taken care of by a group of men who perform their work on the off shift. The work is arranged by the operating official who should be thoroughly familiar with maintenance, so that materials needed may be made up for the particular job and waste of time in looking up materials be prevented. To perfect the maintenance organization, all operating attendants should be thoroughly trained to be familiar with all working parts of their equipment, to make a thorough inspection and to write out the slip for the work required. This requires job analysis, but it is worth the effort, because the attendant usually is better informed than anyone else about his particular equipment. The operating official can judge the scope of the work to direct the repair and to have material ready. Lubrication is an important item in maintenance, and a subject by itself. Usually the breaker oiler is designated to perform this task. This man should be picked for his ability and put in line for promotion to machinist. He should be trained as an inspector, as he is constantly visiting most parts of the breaker and has an opportunity to observe needed maintenance. The first thing is to lay out maintenance work and arrange to have it done; the next is to check the work and see that it has been properly done. This check should be made by the operating official, and through the attendant. The cost statement showing the various items of maintenance cost is not often understood by the man in direct charge. Cost sheets should be simplified and worked up by breaker sections; e.g., the cost of

Jan 1, 1947

By J. T. Mackenzie

Henry Marion Howe, in whose memory we are gathered together, was one of the great thinkers who develop from time to time to whom is given the rare gift of synthesis. Analysis is given to few, but synthesis, the ability to show the relation of all parts to each other and thus to give a clear picture of the whole, is reserved for the very few. Analysis can be achieved by honesty, intelligence, and industry, but synthesis is only given to genius. Professor Howe's crowning achievement is the picture of the whole iron-carbon series shown in Fig. I, which places steel, malleable, gray iron, mottled and chilled irons in their proper relation to each other and shows the essential unity of the series. Perhaps his best statement of the case is found on page go of the Metallography of Steel and Cast Iron in these words: " Each member of the gray cast-iron series consists of the metallic matrix approximately equivalent to that member of the steel-white-cast-iron series to which it corresponds in percentage of combined carbon with its continuity broken up—by masses of graphite ..." Apparently he had taken considerable interest in this idea around the turn of the century, for he refers to a discussion at the Franklin Institute in I900 in which he said: "Though many others had probably conceived this relation between the steels and cast irons, it was here enunciated for the first time, so far as I know. It was received with great incredulity." The concept was explained in some detail in a paper on "The Constitution of Cast Iron" presented before the A.S.T.M. in 1902 when Professor Howe was retiring president of that young society. In the discussion Dr. Sauveur stated that he was "very well acquainted with Professor Howe's theory of the constitution of cast iron," and went on to say that while he "shared it to the fullest extent, some foundrymen . . . claim cast iron is a metal entirely different from steel . . . that steel and cast iron have very little in common, and that therefore the knowledge gained in the study of steel is of little or no value in the study of cast iron." Dr. Moldenke, in discussing the same paper, said he had been working on the same theory for 12 years but he laid no claim to publication. Discussing the difference in the micro-structure of the metallic matrix, Professor Howe pointed out that "such minor structural differences are indeed to be expected, because of the difference in the conditions under which these constituents are generated. "One difference in these conditions is that the steel of most micrographs has been either forged or at least treated thermally in such a way as to give a new structure radically different from that which formed during the initial solidification, whereas the cast irons have not. Hence what we see in the steels is a transformation structure, but in the cast irons a solidification structure. By giving the cast

Jan 1, 1944

By J. T. Mackenzie

Henry Marion Howe, in whose memory we are gathered together, was one of the great thinkers who develop from time to time to whom is given the rare gift of synthesis. Analysis is given to few, but synthesis, the ability to show the relation of all parts to each other and thus to give a clear picture of the whole, is reserved for the very few. Analysis can be achieved by honesty, intelligence, and industry, but synthesis is only given to genius. Professor Howe's crowning achievement is the picture of the whole iron-carbon series shown in Fig. I, which places steel, malleable, gray iron, mottled and chilled irons in their proper relation to each other and shows the essential unity of the series. Perhaps his best statement of the case is found on page go of the Metallography of Steel and Cast Iron in these words: " Each member of the gray cast-iron series consists of the metallic matrix approximately equivalent to that member of the steel-white-cast-iron series to which it corresponds in percentage of combined carbon with its continuity broken up—by masses of graphite ..." Apparently he had taken considerable interest in this idea around the turn of the century, for he refers to a discussion at the Franklin Institute in I900 in which he said: "Though many others had probably conceived this relation between the steels and cast irons, it was here enunciated for the first time, so far as I know. It was received with great incredulity." The concept was explained in some detail in a paper on "The Constitution of Cast Iron" presented before the A.S.T.M. in 1902 when Professor Howe was retiring president of that young society. In the discussion Dr. Sauveur stated that he was "very well acquainted with Professor Howe's theory of the constitution of cast iron," and went on to say that while he "shared it to the fullest extent, some foundrymen . . . claim cast iron is a metal entirely different from steel . . . that steel and cast iron have very little in common, and that therefore the knowledge gained in the study of steel is of little or no value in the study of cast iron." Dr. Moldenke, in discussing the same paper, said he had been working on the same theory for 12 years but he laid no claim to publication. Discussing the difference in the micro-structure of the metallic matrix, Professor Howe pointed out that "such minor structural differences are indeed to be expected, because of the difference in the conditions under which these constituents are generated. "One difference in these conditions is that the steel of most micrographs has been either forged or at least treated thermally in such a way as to give a new structure radically different from that which formed during the initial solidification, whereas the cast irons have not. Hence what we see in the steels is a transformation structure, but in the cast irons a solidification structure. By giving the cast

Jan 1, 1944

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Jan 1, 1938