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By Norbert R. Morgenstern

INTRODUCTION An understanding of the role of water in controlling the stability of rock masses is central for a rational approach to the subject. The presence of water can hinder mining opera- tions in two ways: 1. excessive discharge 2. excessive pressure It should be noted that if the rock mass is very tight, excessive pressures can exist without large discharges. Alternatively, if abundant water is available and the rock mass is open, then substantial discharges can occur under quite small pressures. The problems associated with excessive discharge are usually well understood by the mining engineer. Vehicle mobility is inhibited, some areas are flooded and hence become inaccessible; at best, a costly nuisance exists. The methods of solving these problems are also well-known to mining engineers. They generally involve tapping the source of the excessive discharge and channeling it away in such a manner that any hindrance to the mining operation is minimized. The effects of water pressure on the stability of rock masses are less obvious and the following will be devoted solely to this aspect of the problem. The manner in which water pressures enter into the consideration of stability is made clear by an understanding of the concept of effective stress. THE CONCEPT OF EFFECTIVE STRESS The simplest mechanical model for the problem of rock slope stability consists of a rough, rigid block sliding down an inclined plane under the influence of gravity. This is illustrated in [Fig. 1]. The down-slope component of the weight of the block tends to produce movement which is resisted by the shearing force generated by friction along the base of the block. The shear stress per unit area inducing movement is

Jan 1, 1971

By A. L. Field

WOOLSEY McA. JOHNSON, Hartford, Conn. (written discussion).¬When ;we regard the number of British thermal units running into the billions that-must be applied to metallurgical slags in the United States, we cannot but conclude that the physical chemistry of-slags is a very important subject when measured in dollars and cents. A further contemplation of the subject shows us that it has been hitherto treated in too purely a practical manner. It is needless to comment at length on the cost of these heat units and on the cost of fluxes to produce these metallurgical slags, for, it amounts to tens of millions of dollars annually. Accordingly, this research is of value to the country. But we must,all balance our results against our efforts. Therefore, while the speaker is unwilling to criticise unduly this meritorious research, lie does criticise it in the interest of the profession for the reason that it seems to him too highly theoretical. The article is much too, scientific to produce results at a minimum cost. Let us explain our meaning. It has been said that there are always two sides to a question. It may be further said that there are always three sides to a question, the two extremes and the middle ground. In any industrial research there are the highly theoretical side, the purely practical side, and the theoretico-practical side. To study a slag and be practical in the studying, there is something needed that represents in the laboratory (or in microcosm) what actually happens macrocosmically in the blast furnace. There is such a thing as the art of metallurgical research occupying the middle ground between theory and practice.

Jan 4, 1917

By R. J. Colony

THE failure, or disintegration, of concrete in structures, even when the cement, sand, and coarse aggregate used have passed satisfactorily all tests and inspections, is not uncommon. Such failures occur even when proper methods of mixing and placing have been used and where, weather conditions were correct. In these cases, the origin of the trouble must be sought in the cement, therefore some additional mode of determining the quality of cement must be employed. The problem is to find a simple, usable; easily applied method that will supplement the standard tests. The solution of this problem in-volves a knowledge of the chemical composition of Portland cements, also of their constitution (or componental composition), as the behavior of a cement, when gaged, is dependent on the physical and chemical characters of the compounds of which it is composed, the proportions existing between them, and the fineness of grinding. It is likewise essential to know the character, behavior, and composition of the hydration, products of Portland cement. The most promising method of attack makes use of chemical, mechanical, and petrographic methods. Chemical, by determining quantitatively not only the usual constituents, but the carbon dioxide and water. Mechanical, by determining the fineness with the air analyzer,1 which separates into fractions of various grain dimensions all of that portion, which in the ordinary sieve test passes the 200-mesh sieve and constitutes at least 75 per cent. of the total cement. These fractions may be further studied chemically and petrographically and micrometric measurements made of the grains. Petrographic, by the method of immersion, and by making thin sections from test pats of both neat cements and standard` mortars.

Jan 1, 1921

By C. E. Nelson

THE purpose of this discussion is to outline briefly the practices commonly followed in this country for the melting and refining of magnesium and its alloys. The processes used for the various forms of primary magnesium, as far as there are differences in the physical shape or behavior, will be discussed. The refining of general fine scrap or secondary magnesium was presented in an earlier paper.1 Inasmuch as the use of fluxes is an essential part of all the melting and refining processes, the principal aim of this paper will be to deal with these in sufficient detail to point out their unique characteristics, in order to make their use more effective. TYPES OF MELTING PRACTICE All melting and refining processes for magnesium and its alloys require the use of fluxes. These fluxes have a magnesium chloride base and other halide salts or oxides are added to give a density or behavior exactly suited to the particular melting practice. The successful handling of magnesium depends upon the proper use of the correct fluxes. There are four general methods of melting, summarized in the following paragraphs and treated in more detail in the section on Melting and Refining. Open-pot Method The open-pot method makes use of No. 230 flux.* The flux provides protection during melting and a molten pool of flux into which the solid magnesium melts. It is stirred through the molten metal bath and agglomerates oxide or similar foreign bodies; then on quiet standing separates away, leaving the refined metal ball floating in an encircling layer of molten flux. It forms only a thin fluid film over the surface of the molten metal, which may be parted for hand-ladling processes and tends to cover the metal again after the ladle is removed. A very light dusting of the pot surface with fresh flux immediately after the ladle is removed is usually desirable. The open-pot method is used generally in the following processes: (I) alloying and secondary smelting in the production of ingot, (2) in sand foundries for premelting and to a smaller extent for the production of small castings requiring hand ladling, (3) in permanent-mold founding for premelting and also direct ladling to castings, (4) for continuous methods of preparing metal in the production of billets or ingots from which wrought products are fabricated, (5) in general scrap recovery. Crucible Process The crucible process makes use of No. 310 flux, which has the property of being thinly fluid at the start, to provide protec-

Jan 1, 1944

By H. C. Vacher

THE limiting concentrations of carbon and oxygen which may co-exist at equilibrium in liquid iron are important in determining the degree to which liquid steel may be refined before it is deoxidized. Most refining processes depend upon the oxidation of a highly carburized iron which invariably results in contaminating the steel with oxygen. The oxygen .thus introduced presents many problems to the refiner, who in turn has attempted to rid the steel of this impurity by deoxidation with elements such as manganese, silicon and aluminum. The importance of the limiting concentrations of carbon and oxygen is accentuated in view of a number of recent researches which have indicated in many instances the existence of relations between oxide inclusions and dissolved oxygen and physical properties and chemical behavior of steel. The determination of the equilibrium concentrations of carbon and oxygen existing in iron under steelmaking conditions is obviously of fundamental importance. It has been generally assumed that the product of the equilibrium concentrations of carbon and oxygen in liquid iron is a constant and that this product is directly proportional to the carbon monoxide pressure in equilibrium with the liquid iron. Herty1,2 has computed values for this product based on open-hearth data which are all in the neighborhood of 0.01 to 0.03 (per cent. FeO X per cent. C) for temperatures in the vicinity of 1550° to 1600 C. and one atmosphere pressure. Kinzel and Egan3 have attempted to determine the value of this product by exposing liquid iron to carbon monoxide at one atmosphere pressure. The value reported by them was 0.0005 at 1550°. C. In. order to apply certain equations to the rate of carbon elimination in the open-hearth process, Feild4 found it necessary to assume. a value of 0.0102 at 1580° C. for this

Jan 1, 1931

By John A. Church

THE Lake Superior blast-furnaces probably represent the maximum economy of fuel possible in this country. They smelt an ore which is very rich and easily reducible, and as the small amount of gangue present is not all silica, but in part a silicate, the amount of limestone required is a minimum. The average yield of the ore treated at six furnaces was 63 per cent., and the average quantity of limestone 179 pounds per ton of pig. The fuel used is charcoal, so burned as to retain most of the combustible volatile part, which, before the utilization of furnace-gas, was burned away. With these conditions it is not surprising that the Lake Superior charcoal practice is extraordinary in almost every respect. In any scientific discussion of American furnace work, the establishments there will be found at the head of the list, and they work under conditions which are extremely favorable for careful study. The Bay Furnace, near Marquette, has the honor of carrying "the broom" for the largest daily make. With a capacity of 1908 cubic feet it has, for months together, produced 29 tons of pig, graded at

Jan 1, 1876

At the eastern end of the Mesabi Range, 70 miles due north of Duluth, is the vast plant of Erie Mining Co. Operated by Pickands Mather G Co. for the mine's four owners-Bethlehem Steel, Youngstown Sheet and Tube, Inter- lake Iron, and Steel Co. of Canada-Erie Mining Co, has earned just fame as a pioneer and a leader in the mining, beneficiation, and agglomeration of the lean iron ores of the Lake Superior district. Here is the story of Erie and the integrated operations that have made it such an outstanding member of America's iron ore industry.

Jan 5, 1963

By Percival Roberts

IT may seem necessary to offer an apology for presenting for consideration a process which is conspicuous by its absence in the literature of the Institute, and which may be thought by some to belong to the past in metallurgy, and to have been already superseded. But the large capital invested in puddling calls for a careful consideration of the question whether the time has certainly arrived when the puddling furnace must be replaced by the converter and open-hearth furnace. May there not still be a place for puddled iron alongside of molten iron and steel, and is not the improvement of the puddling process itself worthy the attention of engineers equally with the Bessemer and open-hearth processes? The changes involved in the conversion of pig iron into wrought iron are well understood and need only be briefly alluded to. The patent of Henry Cort bears the date of 1784. Since that time the improvements in the process have mainly consisted in the replacement of sand by iron bottoms by Samuel Baldwyn Rogers in 1818, and the still more recent substitution of iron oxide for the refractory materials used for the rides and bridge of the hearth, which distinguishes the wet or boiling process from the dry or paddling process. Chemically, the process consists in the removal of the metalloids from the pig iron, a result effected mainly by the iron oxide. Silicon is first oxidized, then the phosphorus, and finally the carbon. The silicic and phosphoric acids produced pass into the cinder and the carbonic oxide burns as it escapes from the bath of metal. It is interesting in this connection to note the effect of temperature on the removal of the phosphorus from the iron. As is well known, no phosphorus is eliminated under the oxidizing influences prevailing in the Bessemer converter, while from 70 to 80 per cent. is removed in puddling. But we find, if in working cold short irons

Jan 1, 1880

By J. McD. Porter

In many of the old placer-mining districts are still to be found large tracts of gold-bearing gravel not suitable to be worked with a dredge, because the bed is too shallow or the gulch too narrow. Frequently there is not enough grade to handle the gravel successfully by ground-sluicing or a bedrock flume, or it contains too many boulders to be worked succeeefully with the ordinary hydraulic pipe or tube elevator. In southwestern Oregon, two practical placer-miners named Ruble, after working for years trying to make money out of placer-ground coutaining many large boulders, invented and patented a hydraulic elevator of an entirely new type, and one that has been found to work very successfully in flat ground and in gravel containing many large boulders. It is a very simple contrivance. A few years ago I acquired the property near Pierce City, Idaho, known as the American placer-mine. Various attempts had been made to work this ground. A bed-rock flume had been installed by one company, an Evans elevator by another, and still other methods were tried on a smaller scale. All were

Jan 1, 1910

By James Douglas

Though liberality is not supposed to be a prominent trait of the Scottish character, Canada owes to a Scotchman, Sir Wm. Macdonald, more than to any other of its people, not only wise ideas, but pecuniary help towards extending education: and another Scotchman, in New York, has sumptuously housed under one roof three branches of the engineering fraternity, of which we are one. Having thus created us members of the same family—for the metaphorical meaning of house and kinship is identical—Mr. Carnegie expresses more emphatically than even he could in words, that, by aff'ording facilities for closest intercourse, he invites the mechanical, electrical and mining engineers to participate in the freest interchange of idea and experience, and to correlate and combine the results of their studies and activities; and, being members of the same household, to banish reserve and secrecy. And now we, the members of the American Institute of Mining Engineers, meet as though we were at home in a neighboring country. For whether we meet in Canada, in England, or elsewhere, the Institute is always received as though no political or geographical divisions separated its members from those of congenial associations in the land of its host. In truth, the title which we have assumed claims for the sphere of our activities the whole American continent, regardless of such trifling details as boundary-lines. The fact that we meet to communicate each other's experience, to discuss our difficulties, and to seek each other's aid in solving the intricate problems that so often present themselves in the course of our professional life, is an acknowledgment of our individual helplessness; and therefore an argument for united effort. But no effort can be of any value if there is an underlying suspicion

Jan 1, 1908

WHEN Georgius Agricola, in 155o, dedicated his now famous De re Metallica to the rulers of Saxony, Thuringia, Meissen, and other, smaller principalities, he included in his review of previous works on similar subjects reference to two books written in German: one, an "anonymous, rather disorganized account of assaying for metallic content and of metals," which must be the Probierbüchlein, the other, "dealing - with veins, written by Calbus of Freiberg, a well-known physician."* Calbus is mentioned a second time-and cited-at the end of the Third Book of De re Metallica. Comparison of the citation with the Bergbüchlein leaves no doubt that Agricola considered Calbus of Freiberg the author of the latter work, although all the editions of the Bergbüchlein known now were published anonymously. It is generally accepted by those who have dealt with the bibliography of the Bergbüchleint that Calbus was Ulrich Rülein von Kalbe, who served the City of Freiberg, in Meissen, as health officer in 1497, as member of the City Council in 1509, and as mayor in 1514 and 1519. He died at Leipzig in 1523. In connection with the very garbled description of the mining compass toward the end of Chapter 3 of the Bergbüchlein it is of interest that von Kalbe is supposed to have been not only a physician of repute but a mathematician, astronomer, mine sur-

Jan 1, 1949

By Charles White Merrill

A forecast of mineral demand during the remaining years of the 20th century can serve as an excellent starting point for student mining and mineral engineers in planning their professional careers. This approach of appraising demand before seeking supply is not new. of course, but, it is quite the opposite of the traditional attack on mineral resources in which adventurous prospectors, followed by practical miners and engineers, have in the past sought out and developed mineral supply with a faith that markets existed for the products they were preparing to offer. Such faith, even to this day remains fully justified if the product is gold, which still enjoys an unlimited market at $35 a fine ounce, but other mineral products must compete in markets of varying stability and capacity for adsorbing new supply. The world is in a period of rapid expansion. Most basic is the worldwide increase in the number of people which has reached proportions popularly termed "the population explosion." Conservative demographers, noting an increase from 1 ?h billion people at the beginning of the 20th century to 3 billion today, are predicting 5 billion by the year 2000; some predictions are much higher.

Jan 2, 1964

By Arthur Taggart

INTRODUCTION THE flotation process for the concentration of ores is a method by means of which one or more of the minerals in the ore (usually the valuable ones) are picked up by means of a liquid film and floated at the surface of .a mass of fluid pulp. Here they are separated from the other minerals, which remain immersed in the body of the pulp. In general, the minerals which are floated are sulphides of metallic luster, but some other minerals of metallic luster such as graphite and some sulphides with adamantine luster, such as sphalerite and cinnabar, are amenable to treatment by the process. The importance of flotation lie's in the fact that it is primarily a "slimes process" by means of which the particles of valuable mineral, too fine for efficient gravity concentration, are saved with a high percentage of recovery. Recoveries in the mills treating low-grade copper sulphide ores have been advanced 10 to 20 per cent. by the installation of the process and similar increased savings have been accomplished by the same means in mills treating sulphide ores of zinc and lead. When finely ground ore containing sulphides mixed with a siliceous or earthy gangue is brought gently onto the surface of a body of water, in a direction forming an acute angle with the surface of the water, a considerable portion of the sulphide constituent of the ore floats on the surface of the liquid, while the gangue sinks. This is the so-called film flotation, exemplified by the Wood and Macquisten processes. When gas bubbles are introduced into a fluid pulp composed of finely ground ore and water, to which has been added (1) a small amount of certain oils, or (2) a small amount of certain acids or acid salts, or (3) a small amount of certain alkalis or alkaline salts, or (4) a small amount of a mixture of oil with acid or alkali, the sulphide particles in the ore are brought to the surface on the gas bubbles. These collect in a froth

Jan 8, 1916

By Edward Wichers

THE purpose of this paper is to set forth the matters of principal interest in connection with work done in the past few years on the purification of the metals of the platinum group, including the study and modification of methods already in the literature and the development of new procedures. For the most part, the results will be given in summary form, reserving the publication of detailed data and directions for a forthcoming paper to be issued by the Bureau of Standards. In recent years increasing interest has been shown in the preparation of the pure platinum metals, both by those concerned with the manufacture of the metals and their alloys for scientific and industrial purposes and those who are engaged in the study of the chemical or physical properties of the elements. The purification of the metals usually has been regarded as a matter so involved and difficult as to require the attention of specialists. It is hoped that this paper will show that any of the metals can be prepared in any desired degree of purity by relatively simple straightforward chemical methods. For the most part, it is thought that the methods given are suitable for small-scale refineries as well as for the laboratory; also, that they will bring the time required for the purification of any of the metals within reasonable limits. The new procedure suggested for purifying platinum should prove to be much shorter than any methods described in the literature.

Jan 1, 1928

By L. A. Jr. Norman

ANOTHER chapter in the history of Mother Lode mining is being written by operations in the Old Eureka mine near Sutter Creek, Amador County, California. During a two-year period (1938-1939), 85,517 tons of ore averaging 0.62 oz. gold per ton were mined and milled, as compared to the production of approximately 210,000 tons of 0.315-oz. gold ore during the preceding seven years. This is a repetition of mining history in the Mother Lode, where a period of prosperity has followed a long period of lean production. The location of this new ore in the hitherto unproductive hanging-wall greenstones and its mining and geological developments are most interesting.

Jan 1, 1939

By W. M. Weigel

WHILE electric lamps both of the cap and hand type are being introduced into many mines requiring the use of safety lamps, the oil-burning safety lamp is still used in the great majority of cases, and even where the former are used the latter must continue to be employed when testing for gas. It is not the intention to discuss here the relative merits of the two types, but simply to give a comparison of the illuminating effect or candlepower of several kinds of ordinary safety lamps used for general work and for testing. Few data have been published in recent years on this subject and because of this it is hoped that the following information may be of some interest and value. The lamps tested were in all cases. of standard size and in good condition, all practically new, and were selected from a collection of about 100 with a view to obtaining results on as many different common types as possible. With the exception of the gasoline-burning lamps, five different oils were used in each lamp to determine whether -particular oils were suited to particular lamps and whether there was any great difference in the illuminating power of the different oils, or whether some oils would maintain their illuminating power better than others throughout a working period of 8 hr. No attempt was made to determine the amount or cost of oil burned by each lamp, but the condition of the lamp, wick, glass, and gauzes was noted after each test.

Jan 8, 1916

By H. H. West

Modern mining is vitally concerned with the prompt, efficient movement of great quantities of bulk materials. It is not surprising, therefore, that intensive efforts are being directed toward improving effectiveness and reducing costs of materials handling systems. Historically, the operation of removing bulk material from a moving conveyor and depositing it in utilization or storage areas has been a high cost segment of the materials handling system. Since this operation is often performed by belt trippers, considerable attention has been focused on improvement of these devices. Frequently, the greatest opportunity for improving performance of these devices is the incorporation of remote or automatic control systems. This article describes tripper control systems developed by Kennecott Copper Corp. and explains the control philosophies used in designing these systems.

Jan 3, 1963

By C. W. Jr. Gennet

ANNOUNCEMENT was made in the spring of 1926 that the Boston & Maine R. R. Co. had contracted with the well known German steelmakers, Messrs. Fried Krupp, for the manufacture of 15,000 tons of basic open-hearth steel rails at the Rheinhausen Works, for delivery to Boston, Mass. The manufacture of rails in the United States has for many years been almost a national pride, and as this feeling is chiefly the result of a long-time liberal and consistent patronage of, American rails by American railroads, it is not strange that this somewhat unusual announcement should arouse more than ordinary interest. Since the end of the World War, the importation of foreign rail has been fairly large, principally because the newly created economic conditions have rendered some American competition more difficult, but the tonnage imported, for the most part, has been made up of small orders for miscellaneous use; and the contract referred to constitutes the largest single importation of foreign rail in over ten years. In 1915, the Algoma Steel Co. of Sault Ste. Marie, Canada; supplied the Illinois Central R. R. with 30,000 tons of rails,1 and various other American roads with smaller amounts. In 1902, 1903 and 1904, large tonnages of rail from abroad were purchased, the Louisville & Nashville R. R. alone obtaining 30;000 tons from German mills. It is the object of this paper, to present, in what is believed to be a new and concise form, figures showing the production and consumption of rails in the United States, and to record some of the testing and inspection results of the recent Krupp rails; also, to direct attention to two quite unique departures from American practice that were regular features of the Krupp process and which are worthy, it is thought, of careful study.

Jan 1, 1928

By H. W. Graham

THE young metallurgist of today who thinks casually of the technical literature of the steel industry might conclude that little has been published concerning the Bessemer process. This conclusion is true as relating to the last decade or two, but there is a fairly voluminous Bessemer literature in the period of 1860 to 1910, Since that time, however, an entirely new level of metal-lurgical knowledge of steelmaking has been reached; and the present paper is simply an effort to look broadly from this new level and to bring the recorded history of the process up to date, It is an effort to appraise the acid Bessemer method of steelmaking in the light of today's technical knowledge thereof. In this paper matters of history will be dealt with only insofar as they contribute to an understanding of today's situation. Attention will be directed to the apparent causes of past developments in seeking to perceive the true direction of trends now in existence and effective as bearing upon future developments. The paper will discuss the economics of the Bessemer process, but only to the extent that will bear upon the metallurgist's understanding of his respon-sibility. The problem of the quality of Bes-semer steel will be reviewed and examples will be given of the technical data upon which the reasoning of the paper is based, Matters of engineering design, mechanical maintenance, operation and metallurgical investigation will be surveyed. Compari-sons will be made between the Bessemer and open-hearth processes for the sake of clear and ready understanding,

Jan 1, 1940

By D. G. Deveraux

A BRIEF SKETCH OF THE DAVE JOHNSTON MINE The Dave Johnston coal mine is located near the southwestern extremity of the Powder River Basin in central Wyoming. This mine is operated entirely for the purpose of furnishing fuel to the 750,000 Kw Dave Johnston power generation station located five miles east of Glenrock, Wyoming on the North Platte River about 24 miles east of Casper, Wyoming. Coal is delivered to the power plant by a company-owned railroad moving the coal 15 miles downgrade from the mine to the power plant. The mine first belonging to Pacific Power & Light Company has now been transferred to Northern Energy Resources Company (NERCO), a mining subsidiary of Pacific Power & Light Company. The coal beds which make up the field at the Dave Johnston Mine are locally referred to as the School and Badger seams and occur beneath gently rolling terrain in the Fort Union formation. The School seam is found approximately 180 feet beneath the Badger in the southern portion of the field and about 110 feet beneath the Badger towards the north. The coal beds dip down toward the northeast on about a four percent average inclination. The School seam has an average thickness of about 35 feet and the Badger seam about 16 feet. The climate at the Dave Johnston Mine is semi-arid, with annual precipitation varying between 10 and 12 inches with 70 percent occurring during the months of April to September, with the maximum occurring in May. A few storms occur in July and August which are usually torrential in character, often causing erosion damage to un- protected soils. Snowfall averages 50 inches a year at the mine with 12 to 15 inches of snow yielding one inch of moisture. However, snow seldom

Jan 1, 1983