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By J. R. Long, T. R. Graham, C. W. Matthews, R. S. Dean

IN a previous paper§ the authors reported on the mechanical properties of a 65 per cent copper, 10 per cent manganese, 25 per cent zinc alloy as compared with similarly processed cartridge brass. Additional investigations by these laboratories, on higher copper alloys, have demonstrated that at lower zinc concentrations even larger amounts of pure manganese may be added to copper-zinc alloys without exceeding the single-phase solid solution limits, and that similar increases in tensile strength, yield strength, and hardness may be obtained without excessive decreases in ductility. Several compositions in this range showed also a decided color change with increasing manganese. The normal "brassy" color was considerably lightened and reduced to a faint yellow cast at 15 per cent manganese. With higher manganese contents the alloys were essentially white and similar in appearance to the nickel-silver alloys. From this work it appeared that it would be desirable to determine more completely the properties of the wrought and annealed white alloys. Accordingly, a more detailed study was planned of an alloy having the composition 70 per cent copper, 20 per cent manganese, and 10 per cent zinc. This alloy remained single-phase throughout the working and annealing cycles of the preliminary tests and appeared to be about the strongest of the white single-phase alloys. The project included also an investigation of additional alloys, deviating from this composition by 5 per cent of each of the three components to evaluate the effects of variation in composition; also a study of the properties of the central alloy made with silicothermic manganese. MATERIAL PREPARATION Electrolytic manganese, wirebar copper, and electrolytic zinc were used for the preparation of the alloys. Representative analysis of the electrolytic manganese seldom exceeds 0.01 per cent iron, 0.02 per cent sulphur and 0.02 per cent lead, with no silicon or aluminum. A typical sample of the silicothermic manganese metal contained 2 per cent iron, 0.81 per cent silicon, 0.i6 per cent carbon, and 0.36 per cent aluminum. Melting and alloying were performed in a high-frequency furnace with magnesia crucibles. Melts were deoxidized with small aluminum additions and cast into 25-lb. slab ingots. Care was exercised in deoxidation to avoid excessive amounts of residual aluminum, which has been found to have significant effects on alloys in this system. All ingots were hot-rolled at 1200° to 1300°F. and then cold-rolled with intermediate anneal-

Jan 1, 1945

By Harrison Schmitt

The definitions of the terms commonly used in connection with metamorphism at elevated temperature near igneous contacts are re-examined. As the study of tactite zones associated with igneous contacts progresses, more and more emphasis is put on the localization of the ore by structural forms. The generally early age of the silicates and late age of the sulphides is well established. Postsilicate structural deformation is likely to localize ore bodies. The silicates are often replaced by the ore minerals. we may not be far from proving that the elements involved in the formation of silicate aureoles are merely normal "volcanic" emanations, that silica, lime, magnesia, and alumina, and probably soda and potash, are likely to undergo local transfers only. The work of Newhouse suggests the agents of the formation of sulphides in deposits of various classifications are the volcanic emanations. Introduction The purpose of this paper is to define the terms commonly used in connection with the subject, to briefly review and discuss the broad features of the aureoles, to indicate some of the features lately recognized: to discuss the genesis, and to suggest how the associated ore deposits can best be studied and developed. When developing a subject in mining geology one is soon conscious of the vast amount of pertinent literature and that most relevant ideas, no matter how obscure, have been considered. One can only hope to make some small contribution in point of view, a few confirmatory observations, or, perhaps, suggest a small new idea indebted to the most recent data. It is nearly impossible, also, to give specific credit, and adequate credit, to all the contributors to a given subject. This study, furthermore, was not intended to cover the field exhaustively, nor is the bibliography complete. Definition OF Terms There is much confusion in the use of the broad terms concerned. Needless to say, metamorphism means change of form; metasomatism, change of substance. The term contact metamorphism, however, has been widely misused possibly by a majority of economic geologists and engineers. As originally adopted by European investigators it meant changes effected largely by heat (thermal effects) in the rocks invaded by plutonic intrusives, but did not include those local changes usually at the immediate contact brought about by the addition of substance, i.e., by metasomatism. The term has become clouded. In Europe it has

Jan 1, 1949

By Harrison Schmitt

The definitions of the terms commonly used in connection with metamorphism at elevated temperature near igneous contacts are re-examined. As the study of tactite zones associated with igneous contacts progresses, more and more emphasis is put on the localization of the ore by structural forms. The generally early age of the silicates and late age of the sulphides is well established. Postsilicate structural deformation is likely to localize ore bodies. The silicates are often replaced by the ore minerals. we may not be far from proving that the elements involved in the formation of silicate aureoles are merely normal "volcanic" emanations, that silica, lime, magnesia, and alumina, and probably soda and potash, are likely to undergo local transfers only. The work of Newhouse suggests the agents of the formation of sulphides in deposits of various classifications are the volcanic emanations. Introduction The purpose of this paper is to define the terms commonly used in connection with the subject, to briefly review and discuss the broad features of the aureoles, to indicate some of the features lately recognized: to discuss the genesis, and to suggest how the associated ore deposits can best be studied and developed. When developing a subject in mining geology one is soon conscious of the vast amount of pertinent literature and that most relevant ideas, no matter how obscure, have been considered. One can only hope to make some small contribution in point of view, a few confirmatory observations, or, perhaps, suggest a small new idea indebted to the most recent data. It is nearly impossible, also, to give specific credit, and adequate credit, to all the contributors to a given subject. This study, furthermore, was not intended to cover the field exhaustively, nor is the bibliography complete. Definition OF Terms There is much confusion in the use of the broad terms concerned. Needless to say, metamorphism means change of form; metasomatism, change of substance. The term contact metamorphism, however, has been widely misused possibly by a majority of economic geologists and engineers. As originally adopted by European investigators it meant changes effected largely by heat (thermal effects) in the rocks invaded by plutonic intrusives, but did not include those local changes usually at the immediate contact brought about by the addition of substance, i.e., by metasomatism. The term has become clouded. In Europe it has

Jan 1, 1949

By H. W. Krotzer

ADOPTION on a commercial scale of electrolytic deposition of metals brought with it the problem of providing an acid-proof cell or tank. Where the electrolyte contained only a dilute solution of sul-furic acid, wooden, tanks with lead linings were gen-erally adopted. There were cases, however, where a lead lining was impractical as a result of the presence of nitric acid in the electrolyte or because of the method of handling the current for deposition. purposes. Wherever lead was unsuitable for this work, asphaltic mastic was used in its place. This material, in addi-tion to possessing acid-proof qualities and being an insulator for electrical current, is also cheaper than lead. The only reason that prevented the common adoption of mastic for all work of this type was that it was still an unknown, unproved. material; while lead, although more costly, could be relied on. There are several electrolytic tank-houses equipped with acid-proof mastic linings now in operation. The first large one was the series tank-house of the Balti-more Copper Co., where the mastic used was composed of natural asphalts and a silica aggregate. These lin¬ings are now seventeen years old and still in service. The next large plant was that of the Chile Exploration Co., at Chuquicamata, Chile, ,and it is with this that this article deals. Another plant of more recent date is that of the Nichols. Copper Co., Laurel Hill, L. I., and specifications for the new electrolytic tank-house of the Union Miniere du Haut Katanga call for mastic lining. It is also being tried out on a smaller scale or for experimental purposes by many of the larger metal-lurgical companies. Thus while mastic linings were adopted originally to meet operating conditions that prohibited the use of lead, they are now in a position to compete successfully with the standard lead linings that are in general use. The Chile Exploration Co. plant, with a total area of over a million square feet, giving satisfactory ser-vice under the most adverse climatic and metallurgical conditions can be truly called the pioneer in this work. ,This article will deal with the development of the acid-proof mastic linings in Chuquicamata from the original experiments begun in 1912 up to and including the final successful installation that has now been in service for a number of years.

Jan 4, 1927

By Raymond Mancha

TO determine the optimum inside dimension of an airshaft, it is necessary to strike the proper balance between the cost of power for air friction and turbulence losses within the airshaft, on the one hand, and the cost of sinking the airshaft, on the other. An airshaft larger than necessary is extravagant because the increased amortization rate exceeds the reduction in power cost. Conversely, an airshaft smaller than is needed wastes more power than can be justified by the corresponding reduction in amortization rate. The airshaft power is a function of the air volume Q cu. ft. per min. and the air-pressure drop p in. water gauge across the airshaft. † The airshaft pressure drop is calculated by the formula: R X l X O X Q2 P= 5-2 X A3 wherein R is the air-friction coefficient for the portion of the airshaft 1 ft. deep, 0 ft. in perimeter and A sq. ft. in area, when passing an air volume of Q cu. ft. per minute. The airpower w kw. dissipated within the airshaft is computed by the formula: w= 0.746Q X P 6345 With a combined over-all unit efficiency of the fan and drive of E per cent, the air-shaft power requirements become W = 100w There are 8760 hours per year, so with energy at I cent per kilowatt-hour the annual cost per kilowatt for continuous operation is $87.60; therefore, with energy at C¢ per kw-hr. the annual airshaft power cost MI dollars per year becomes: M1 = 87.60W X C which, expressed by the component parts, becomes: M1 V 5.2X4' / XQ Z 0.746 X 100 X 87.60 X C V 60 X E ) The amortization rate a dollars per year per dollar invested includes both depreciation and interest on the investment. These in turn involve the expected useful life of the airshaft and available molletary interest rate. For the purpose of this discussion the cost of airshaft sinking is assumed to comprise a fixed move-in charge Y dollars, which covers the cost of transporting, erecting and removing the shaft-sinking equipment and is independent of the air-shaft size. Also, it is assumed that the cost of shaft lining, if any, is fixed at $X per cu. yd. of lining material and that excava-

Jan 1, 1947

By Raymond Mancha

TO determine the optimum inside dimension of an airshaft, it is necessary to strike the proper balance between the cost of power for air friction and turbulence losses within the airshaft, on the one hand, and the cost of sinking the airshaft, on the other. An airshaft larger than necessary is extravagant because the increased amortization rate exceeds the reduction in power cost. Conversely, an airshaft smaller than is needed wastes more power than can be justified by the corresponding reduction in amortization rate. The airshaft power is a function of the air volume Q cu. ft. per min. and the air-pressure drop p in. water gauge across the airshaft. † The airshaft pressure drop is calculated by the formula: R X l X O X Q2 P= 5-2 X A3 wherein R is the air-friction coefficient for the portion of the airshaft 1 ft. deep, 0 ft. in perimeter and A sq. ft. in area, when passing an air volume of Q cu. ft. per minute. The airpower w kw. dissipated within the airshaft is computed by the formula: w= 0.746Q X P 6345 With a combined over-all unit efficiency of the fan and drive of E per cent, the air-shaft power requirements become W = 100w There are 8760 hours per year, so with energy at I cent per kilowatt-hour the annual cost per kilowatt for continuous operation is $87.60; therefore, with energy at C¢ per kw-hr. the annual airshaft power cost MI dollars per year becomes: M1 = 87.60W X C which, expressed by the component parts, becomes: M1 V 5.2X4' / XQ Z 0.746 X 100 X 87.60 X C V 60 X E ) The amortization rate a dollars per year per dollar invested includes both depreciation and interest on the investment. These in turn involve the expected useful life of the airshaft and available molletary interest rate. For the purpose of this discussion the cost of airshaft sinking is assumed to comprise a fixed move-in charge Y dollars, which covers the cost of transporting, erecting and removing the shaft-sinking equipment and is independent of the air-shaft size. Also, it is assumed that the cost of shaft lining, if any, is fixed at $X per cu. yd. of lining material and that excava-

Jan 1, 1947

By A. L. Holley

Those who are familiar with working gas furnaces will perhaps admit that the ordinary producer is the least satisfactory feature of the- whole system, chiefly by reason of its great waste of fuel, both above and below the fire. The waste of fuel in cleaning the fire has not, as fdr as I am aware, been carefully measured ; it has been roughly estimated at various works as averaging twenty per cent. to twenty-five per cent. The coke that falls into the ash-pit is largely mixed, if not stuck together with clinker; when this coke is not recovered and utilized (and where coal is cheap it does not pay to recover it), the waste is certainly as high as above estimated. Cleaning a fire on a grate (especially a fire of dirty coal, like much of our Western coal), by inserting a few temporary grate-bars, then withdrawing the regular grate-bars and letting the whole lower part of the fire tumble into the ash-pit, must necessarily be wasteful of fuel, but it has been found to be the most practical system. The fire under a boiler should be thin, to insure perfect combustion; hence it may be moved from one side to the other, so that .the clinker and ashes may be uncovered and removed. But a producer fire should be so thick that carbonic oxide only shall rise from it; a thick fire cannot be thus manipulated. In several of the French works the ordinary producer without grates is employed ; the whole body of the fire rests on the floor of the ash-pit. It did not seem to me that less fuel was wasted here than with grates in cleaning fires. The bottom layer of the fire had to be drawn out with hooks, and there was nothing to prevent much coke from coming away with the clinker and ash. A producer shaped like a cupola furnace has many advantages, but if grates are employed the waste of coke in cleaning is not lessened. But the waste at the bottom of the fire is only a part of the waste in the ordinary producer. Mr. Emmerton, chemist to the Juliet Iron and Steel Company, has lately made a number of gas analyses from the producers of that company, worked with impure Illinois

Jan 1, 1880

By T. H. Alden

In several recent studies of fatigue fracture in single-phase metals, tests have been made using the condition of essentially constant plastic strain amplitude.1-4 This procedure departs from the more common practice of holding the amplitude of stress constant. From these studies have emerged two important generalizations about the behavior of metals during cyclic straining. First, measurements of the stress amplitude, required to impose the fixed plastic strain amplitude, have shown that the rate of cyclic strain hardening in annealed metals is rapid in the early cycles but decays quickly to a very low value.1"5 This behavior is displayed particularly for a range of strain amplitudes below about 2 pct and at low and high temperature. Frequently, the hardening rate becomes so low that one can determine a "saturation" stress. This stress increases with strain amplitude. In addition, an experimental relation between fracture life and plastic strain amplitude was obtained by Coffin and Taternelli,' namely N 1/2 ep = constant. For several metal:;, this equation has been shown to hold down to a strain amplitude of 0.1 pct. Whether it also holds in the "low amplitude" range (lives of more than about 105 cycles) has not been established. The importance of the saturation stress level (a value derived from strain hardening measurements) to the question of fracture life (the usual quantity of interest of fatigue testing) lies in the observation that cracks start to form when the cyclic hardening rate is essentially zero, and not before.4"5 This point suggests immediately a means of relating tests at constant stress and constant strain amplitudes. When making comparison, the stress in a constant stress test is to be identified with the saturation stress in a constant strain test. If these ideas are correct, then it should be possible, using the relation between fracture life and strain amplitude and experimental curves of saturation stress versus strain amplitude, to predict the fracture life as a function of stress, i.e. predict the S -N curve, for low stress fatigue. Saturation stress amplitude-plastic strain amplitude data, obtained in tension-compression, exist only for a few metals and for relatively high amplitudes of strain. Comparable S -N curves (push-pull loading) were known by the author only for OFHC copper. Values for this metal taken from Ref. 2 are shown in Fig. 1. The strain amplitudes, the lowest

Jan 1, 1962

By Lendall P. Warriner, Blandford C. Burgess

Jasper County lies just north of the geographical center of Georgia, bounded on the west and north by the Ocmulgee River. The county seat, Monticello, is approximately 65 miles east-southeast of Atlanta and 40 miles north of Macon. It is served by the Macon-Athens branch of the Central of Georgia Railway Co. and by five paved highways converging from adjoining county seats. Farming and lumbering are the principal local occupations. About half the county is covered with pine and mixed hardwoods; a large part of the forested land is owned by the Soil Conservation Service of the Department of Agriculture in its Piedmont Land Utilization Project. The topography is one of gently rolling field and forest with occasional hills rising 100 ft or more above the creek beds. Though annual rainfall is in the neighborhood of 60 in., most of it falls in torrential downpours of short duration which tend rapidly to erode the red soil and convert the country roads to greasy tracks of red mud. History The pegmatites of Jasper County produced a small amount of mica in World War I. In World War 11, our Government's search for this strategic mineral brought to Georgia B. C. Burgess, then Southern Manager of Colonial Mica Corp., subdivision of Metals Reserve Corp., who noted on State Highway 83 the presence of pegmatitic material used as road metal. In 1944, after severing his Government connection and returning to private practice, Mr. Burgess investigated the source of the pegmatitic material noted on his previous visit and discovered that graphic granite pegmatite had been mined for the road metal. He secured mineral leases from the Soil Conservation Service and from private owners and began preliminary development work. By 1946 he had uncovered enough pegmatite to warrant an enterprise to undertake economic development of the feldspar. In March 1947, he conveyed his leases and interest to Appalachian Minerals Co., remaining with it as Vice President and General Manager. This company has carried on additional development, removing overburden by bulldozer and drilling the pegmatites uncovered. A modern and efficient feldspar grinding plant to produce 20 mesh feldspar for the glass industry was completed and placed in operation May 1, 1948. Geology GENERAL GEOLOGY OF ROCK TYPES OTHER THAN PEGMATITE Jasper County lies within the Appalachian Crystalline Complex and approximately 40 miles north of the "Fall Line," where the Upper Cretace-

Jan 1, 1950

By Kendall E. Born

Production of crude oil in Tennessee during 1944 was slightly more than 9500 bbl., about 1300 bbl. more than 1943. Approximately 8000 bbl. was produced from the "Mississippi lime" in Scott and Morgan Counties. Some half dozen wells in Clay, Pickett, and Fentress Counties, pumped intermittently, produced about 1500 bbl. This production is from rocks of Ordovician age ranging in depth from less than 500 ft. to approximately 1000 ft. Natural gas was marketed from wells in Morgan and Fentress Counties for consumption in the Sunbright and Jamestown areas, respectively. The production of oil by counties is shown in Table I. Developments There were 20 completions during 1944 totaling 19,615 ft., nearly twice as much as in 1943. One well was drilling on Dec. 31, 1944. Of the 20 completions, one was a small oil well soon abandoned. Three gas wells were completed which are used locally. The completions are listed in Table 2. The distribution of tests according to physiographic divisions is given in Table 3. Cumberland Plateau There were five completions in the northern part of Cumberland Plateau. One was a small gas well in the Cooper pool 3 miles west of Oneida, but an attempt to extend the pool to the south resulted in a dry hole. The most active area in the state during 1944 was the northern Cumherland Plateau, especially in Cumberland, Morgan, and Scott Counties. Several blocks, aggregating more than 500,000 acres, were assembled and leasing was continuing in the early part of 1945. Surface work has been, or is being, carried on by at least four companies. While in an area of past oil and gas production from the "Mississippi lime," the principal interest appears to be in the essentially unexplored pre-Mississippian possibilities. The Knox dolomite group of Cambro-Ordovician age is receiving some attention as a possible reservoir. As the year closed one well was drilling on a surface structure near Lantana, 6 miles southwest of Cross-ville. This test will be drilled into the upper part of the Knox. Late in 1944, it was planned to lay a gas line from northern Morgan County to Oneida in Scott County, a distance of approximately 20 miles. Middle Tennessee Fifteen wells were drilled in Middle Tennessee. In the northeastern Highland Rim area there were 11 completions, one

Jan 1, 1945

By W.W. Weigel

The mines of the St. Joseph Lead Co. in St. Francois County, Missouri, form a roughly triangular area of about 45 square miles. Locally this is known as the Lead Belt. The four operating mines in the area at present are the Federal, Leadwood, Desloge, and Bonne Terre, in decreasing order of mine area and daily production. Mining began in 1864 and has been carried on in the district continuously since that time. As a group, the Lead Belt mines now handle 20,000 gal. per min. of water, average head about 465 ft., against a normal daily ore tonnage of 21,200 tons. For a six-day operating week this gives a ratio of 6½ tons of water per ton of ore. Total average pumping in 1931 was about 15,000 gal. per min. Since that time a large area of virgin territory has been opened, much of which has had temporary flush flows. About 75 per cent of the water enters in certain restricted very wet areas. Production figures are given in Table I. The figures by divisions for 1931 and 1941 are not exactly comparable, as there were several transfers of pumping loads from one division to another during that period of time. Geology The, basement formation in 'the Lead Belt area consists of the pre-Cambrian rhyolite porphyry and granite. Overlying this is the La Motte sandstone, of Middle Cambrian age, which offers a good medium for circulation of water. It varies in thickness up to 400 ft. Above this is the Bonne Terre dolomite, approximately 375 fl. thick, which in turn is overlain by the 150-ft. Davis shale. The formations above this, present in the Lead Belt in small areas only, are of minor importance. The ore bodies occur as large, horizontal tabular masses or as long, narrow runs; they are found throughout the Bonne Terre but largely in the lower 150 ft. The rather indefinite contact with the La Motte is a favorite ore horizon. Milling is entirely by open stope and pillar breast systems. To the south, west, and north of the district, sandstone outcrops are few and limited. Heavy faulting bounds The district on those sides and probably there is little if any artesian circulation from those directions. To the east, the La Motte rises to an outcrop area of about 40 square

Jan 1, 1943

By W. W. Weigel

The mines of the St. Joseph Lead Co. in St. Francois County, Missouri, form a roughly triangular area of about 45 square miles. Locally this is known as the Lead Belt. The four operating mines in the area at present are the Federal, Leadwood, Desloge, and Bonne Terre, in decreasing order of mine area and daily production. Mining began in 1864 and has been carried on in the district continuously since that time. As a group, the Lead Belt mines now handle 20,000 gal. per min. of water, average head about 465 ft., against a normal daily ore tonnage of 21,200 tons. For a six-day operating week this gives a ratio of 6½ tons of water per ton of ore. Total average pumping in 1931 was about 15,000 gal. per min. Since that time a large area of virgin territory has been opened, much of which has had temporary flush flows. About 75 per cent of the water enters in certain restricted very wet areas. Production figures are given in Table I. The figures by divisions for 1931 and 1941 are not exactly comparable, as there were several transfers of pumping loads from one division to another during that period of time. Geology The, basement formation in 'the Lead Belt area consists of the pre-Cambrian rhyolite porphyry and granite. Overlying this is the La Motte sandstone, of Middle Cambrian age, which offers a good medium for circulation of water. It varies in thickness up to 400 ft. Above this is the Bonne Terre dolomite, approximately 375 fl. thick, which in turn is overlain by the 150-ft. Davis shale. The formations above this, present in the Lead Belt in small areas only, are of minor importance. The ore bodies occur as large, horizontal tabular masses or as long, narrow runs; they are found throughout the Bonne Terre but largely in the lower 150 ft. The rather indefinite contact with the La Motte is a favorite ore horizon. Milling is entirely by open stope and pillar breast systems. To the south, west, and north of the district, sandstone outcrops are few and limited. Heavy faulting bounds The district on those sides and probably there is little if any artesian circulation from those directions. To the east, the La Motte rises to an outcrop area of about 40 square

Jan 1, 1943

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 metallurgical 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 responsibility. The problem of the quality of Bessemer 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. Comparisons will be made between the Bessemer and open-hearth processes for the sake of clear and ready understanding. Production First of all it is considered logical and informative to show how much Bessemer steel has been and is being produced, and the relation of that production to the tonllage made by the open-hearth process. Table 1 shows the tonnages made by the two processes in representative years. It is to be noted that these figures are in net tons of 2000, lb., whereas previous to 1940 the Institute figures were compiled in gross tons. id open-hearth production and steel going into castings are included, since separated data are not available for the early years of the period covered. The ratio shown in Table I is merely the Bessemer tonnage for a given year divided by the open-hearth tonnage of the same

Jan 1, 1941

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 metallurgical 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 responsibility. The problem of the quality of Bessemer 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. Comparisons will be made between the Bessemer and open-hearth processes for the sake of clear and ready understanding. Production First of all it is considered logical and informative to show how much Bessemer steel has been and is being produced, and the relation of that production to the tonllage made by the open-hearth process. Table 1 shows the tonnages made by the two processes in representative years. It is to be noted that these figures are in net tons of 2000, lb., whereas previous to 1940 the Institute figures were compiled in gross tons. id open-hearth production and steel going into castings are included, since separated data are not available for the early years of the period covered. The ratio shown in Table I is merely the Bessemer tonnage for a given year divided by the open-hearth tonnage of the same

Jan 1, 1941

R. B. BrinSmade, Ixmiquilpan, Hgo., Mexico (written discussion*).—While agreeing with Mr. Gibson that his net-profit tax is the fairest and best for mines, I believe that the tax he describes can be more accurately defined by another name. In accounting, net profits are usually considered to be the residual of the gross income after operating expenses and the annual charge for upkeep of plant have been deducted. Even the necessary interest on bonds or mortgages should not be subtracted in this calculation, for this interest represents merely that fixed portion of the net profits going as a return to that fraction of the total property value owned by the bondholders. Applying this method of calculation to the gross income of a mining property, we should onIy deduct operation expenses and upkeep of plant to get the net profits on its whole property value. So Mr. Gibson in deducting a further sum, to cover the interest and amortization of the capital expended in mine development and equipment, really arrives at something quite differen't from net profits; which can properly only be defined as the annual value of the mineral in the ground, or the royalty value in miners' parlance. From one viewpoint, Mr. Gibson's first principle, which assesses taxes, "proportionate to the benefits received by the person or property taxed," is identical with his third principle wbich assesses "with reference to the extent and value of the natural resources enjoyed." With one exception, everything of use around a mine represents a cash expenditure, or its equivalent in human labor, and state action has not added an iota to its value. The one exception is what makes the enterprise possible and it includes the mineral deposits and their associated surface; water and other landed rights. These natural resources are origin2!1y the gift of tile people acting through their agent, the state, and it is evident that a tax laid on whatever profits may arise from their enjoyment will be exactly "proportionate to the benefits received by the person or property taxed." Mr. Gibson is mistaken in his belief that the general property tax of the United States has the same incidence as his system of taxing profits, because the general property tax falls not only on land1 value—as does

Jan 1, 1920

By Daniel D. Pollock

The il'lott and Jones theory of thermoelectricity predicts that the absolute thermoelectric power of alloys of transition and noble metals should be a maximum when the concentration of the noble metal is approximately 55 to 60 at. pct. An examination of the emf of a series of relatively pure alloys of copper and nickel shows that the predicted maximum occurs at about 57 at. pct Cu. This excellent agreement with the theory is considered to substantiate the Mott and Jones theory of thermoelectricity for binary alloys of transition elements. This theory is extended to show that the emf behavior of dilute, ternary copper-nickel base alloys, which contain approsimately 60 pct Cu and 40 pct Ni, may be described in terms of a scattering mechanism. The scattering effect of a third element is demonstrated to be a function of its valence and its period in the periodic table. Small amounts of solute elements have additive scattering effects upon the emf of the Cu-Ni base. The Mott and Jones equation is modified to include this scattering parameter. This adaptation accurately describes the thermoelectric behavior of ternary and quaternary CLL-Ni base alloys. An empirical form of the modified Mott and Jones equation is derived which permits the calculation of thermoelectric power with an average error of less than 0.4 pct at 500 "C. CONSTANTAN has long been used as a thermocouple element. Its approximate composition varies from 50 pct Cu, 50 pct Ni to 65 pct Cu, 35 pct Ni. Small amounts of manganese, iron, and other elements have been used to modify the composition in order that the resultant emf vs platinum conforms to nationally accepted table. Adjustments of this type are made on a purely empirical basis. Constantan was originally made in Germany and was imported into this country for thermoelectric and electrical resistance purposes. During World War I, the supply of this material became seriously depleted. The work of Bash4 was done in this period in order to develop a satisfactory substitute for the imported material. Bash's empirical work on Cu-Ni alloys is still the basis for all commercial constantans made in this country. No reexamination of the electrical properties of this system has been made, despite the fact that it is now well known that Bash's alloys contained impurities which strongly affected their thermoelectric behavior.

Jan 1, 1962

By J. F. Myers, F. M. Lewis

THE crushing of ore, as defined by Taggart,1 is "usually a stage process, utilizing . . . machines especially suitable for the reduction of particular sizes... . down to a final stage, employed for the reduction of the finest sizes. . .. In contradistinction, comminution to 20-mesh or finer is called grinding. There is a twilight zone in which the product is 6, 10, or 14mesh limiting size which is either crushing or grinding. . .. " Since the data in this paper pertain to a rod-mill operation, comminuting a particular ore size of ¾ in. to a final stage, coarser than 20-mesh, the rod mill is designated as a "fine crusher machine" in this paper. The published literature discloses a wealth of data regarding a rod mill as a fine-grinding machine but relatively little as a fine-crushing operation. Typical of the latter operation is: (I) a description by F. J. Tuck2 in which a fine-crushing rod mill replaced crushing rolls and (2) a description by the present authors3 in which a fine-crushing rod mill was installed instead of a conventional fine-crushing machine. The experience of the authors is that a definite distinction must be made between the rod mill functioning as a fine crusher and as a fine-grinding machine. As a fine-crushing machine it prepares * relatively large amounts of ore for a subsequent fine-grinding operation; as a grinding machine, it grinds relatively small amounts of ore to some predetermined finished product. PULP MOVEMENT AND ACTION IN MILL In considering the work performed by a fine-crushing rod mill, it seems important to understand just what takes place within the mill. We were inspired to study this matter by a paper by E. W. Davis,4 which indicated that definite water classification of ore particles took place in a ball mill. However, in thinking of the rod-mill action from this point of view, we were confronted with the fact that our rod-mill discharge product showed no evidence of action by water classification. The Tennessee Copper Co. ore is relatively high in sulphides, and the gangue rock and the sulphides are of about the same hardness. In the presence of any action by classification, the coarser sizes are definitely very lean in sulphide minerals. [ ]

Jan 1, 1946

By A. L. Holley

THOSE who are familiar with working gas furnaces will perhaps admit that the ordinary producer is the least satisfactory feature of the- whole system, chiefly by reason of its great waste of fuel, both above and below the fire. The waste of fuel in cleaning the fire has not, as far as I am aware, been carefully measured ; it has been roughly estimated at various works as averaging twenty per cent. to twenty-five per cent. The coke that falls into the ash-pit is largely mixed, if not stuck together with clinker; when this coke is not recovered and utilized (and where coal is cheap it does not pay to recover it), the waste is certainly as high as above estimated. Cleaning a fire on a grate (especially a fire of dirty coal, like much of our Western coal), by inserting a few temporary grate-bars, then withdrawing the regular grate-bars and letting the whole lower part of the fire tumble into the ash-pit, must necessarily be wasteful of fuel, but it has been found to be the most practical system. The fire under a boiler should be thin, to insure perfect combustion; hence it may be moved from one side to the other, so that .the clinker and ashes may be uncovered and removed. But a producer fire should be so thick that carbonic oxide only shall rise from it ; a thick fire cannot be thus manipulated. In several of the French works the ordinary producer without grates is employed ; the whole body of the fire rests on the floor of the ash-pit. It did not seem to me that less fuel was wasted here than with grates in cleaning fires. The bottom layer of the fire had to be drawn out with hooks, and there was nothing to prevent much coke from coming away with the clinker and ash. A producer shaped like a cupola furnace has many advantages, but if grates are employed the waste of coke in cleaning is not lessened. But the waste at the bottom of the fire is only a part of the waste in the ordinary producer. Mr. Emmerton, chemist to the Joliet Iron and Steel Company, has lately made a number of gas analyses from the producers of that company, worked with impure Illinois

Jan 1, 1880

By A. L. Holley

THE general usage of engineers, manufacturers, and merchants, is gradually, but surely, fixing the answer to this question. In every country rails, boiler-plates, and machinery bars, whether hard or soft, are almost universally called steel, when they are made from cast ingots. Other names for the softer steels, such as " homogeneous metal," " Bessemer iron," " Martin iron," and the like, have failed to obtain general recognition. The meaning of the term steel, before it was enlarged to cover newly developing varieties, has been traced, by a recent writer, down through Percy, Shakspeare, and the Bible, in a most interesting manner, from an archaeological point of view. Undoubtedly, it did characterize hardness and other qualities imparted by carbon. It is within the memory of most of us, that all steels were tool steels, and that the soft, structural varieties were introduced-varieties which harden but little, which bend cold, and which, in many physical properties, are akin rather to wrought-iron than to tool-steel. But, since both the hard and the soft steels are made by the same processes, and have their great, distinguishing structural feature in common, viz., homogeneity resulting from fluidity, it has come to pass, despite every other proposed nomenclature, that all the compounds of iron which have been cast in malleable masses, are called steel, the term wrought-iron being still confined to malleable iron made from pasty masses, and hence laminated in structure. No inconvenience has been found, so far, in distinguishing between the more or less carburized products, in general, by the terms " high-steel," " low-steel," " tool-steel," etc., and, in particular, by prefixing the percentage of carbon and other ingredients, to the terra steel. Steels which contain distinguishing ingredients other than carbon, are called "chrome-steel," " titanium-steel," and the like, just as variously compounded bronzes are called "phosphor bronze," "alu¬minium bronze," etc. Thus the combination of several words or symbols, and figures, may completely disclose the characters of the metal, in terms that are subject to no misunderstanding. But inasmuch as several high metallurgical authorities and clever writers have of late proposed to disturb this natural and somewhat settled nomenclature, it seems important to consider the claims of the various classifications. I shall attempt, in this paper, to show

Jan 1, 1876

By Boyd Dudley, R. H. Richards

In nearly all ore-dressing operations it is a common practice to discharge mixtures of fine ore and water through spigots; for example, from classifier pockets, from jig hutches, from settling tanks, etc. As a general rule it is desirable to regulate the composition, i.e., the ratio of water to sand, of such discharged products; and this can usually be done by varying the size of the orifice or spigot through which the material is discharged. Thus it is that problems similar to the following are frequently encountered: With a given quantity of solids per unit time, of a given specific gravity, to be discharged with water under a given head, and with a given ratio of water to solid, what must be the size of the spigot opening? If the spigot is to be open continuously, there are, aside from its form, but three factors governing the rate at which it will discharge a mixture of sand and water, namely: the head of water above the spigot; the area of the spigot opening; and the viscosity of the material to be discharged. The term viscosity, as used here, means the ratio of the volume of pure water that will flow through a given orifice under a given head in a given time to the volume of the material under consideration that will flow through the same orifice in the same time under the same conditions. While the actual viscosity of water containing sand in suspension is not increased by the presence of the sand, nevertheless the volume-rate at which such a mixture will flow through an orifice is less than that at which pure water will flow, by reason of the friction of the particles of sand against each other and against the sides of the orifice. In other words, the flow is retarded as it would be by increased viscosity; and therefore, for the purpose in view, we may speak of the viscosity of a mixture of ore grains and water as defined above. The head of water above the spigot is generally fixed by the form and design of the classifier or tank to which the spigot is attached. So, with the head known, in order to determine the size of the spigot required it is necessary to know the viscosity of the desired mixture, and the coefficient of discharge of

Jan 1, 1915