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By L. W. Kemph

The thermal expansion characteristics of aluminum alloys have been examined by several investigators, among whom may be mentioned Shakespear,' Schulz,2 Hidnert13 Hidnert and Sweeney4 and McCullough.' Shakespear compared the expansion of a series of aluminum alloys containing 14 per cent copper, with separate additions of about 1 per cent each of manganese, tin and zinc with that of pure copper. Schulz examined the expansion of aluminum and zinc and some aluminum-zinc alloys. Hidnert determined with a high degree of precision the exp:tnsion characteristics of pure aluminum, some aluminum-copper, aluminum-zinc, aluminum-silicon and some commercial alloys.' Hidnert and Sweeney examined the expansion characteristics of aluminum-beryllium alloys. McCullough, by an interferometer method, determined the expansivity of some aluminum-copper, aluminum-magnesium, aluminum-iron, aluminum-nickel, aluminum-silicon and aluminum-manganese alloys. Incidental to an investigation carried out during the past six years and leading to the development and exploit,ation of an aluminum piston alloy of relatively low thermal expansivity, the expansion characteristics of a wide variety of alloys were examined. Some of the data which might be of general interest are gathered in this paper. Experimental Procedure The apparatus used was essentially similar to those developed by the Bureau of Standards6 and Howard Scott,? with a few minor changes for expediency. The specimen was approximately 4 in. long and the differential length changes between specimen and the quartz tube were

Jan 1, 1933

By A. M. Lovelace

Introduction One area of engineering utilization of materials in which the requirements are especially rigorous and demanding is that of aerospace systems, including aircraft, helicopters, missiles, and space satellites. Materials used in these systems must reliably perform many critical functions in a broad range of adverse environments. Some of the most critical functions are performed by polymeric nonmetallic materials such as elastomers (rubber), coatings, fibrous materials, and reinforced plastics. These types of polymeric materials have some common characteristics that make them attractive to aerospace system designers: light weight, corrosion resistance, and relative ease and low cost of processing and fabrication. Each type also has its own special characteristics that enable it to perform certain required functions better than other competing materials can (Table 1). The desirable properties of polymeric materials, which in some applications make them the only practical candidates, are partly offset by their principal limitation, which is degradation by exposure to high temperature. [ ]

Jan 1, 1971

By J. B. Austin, R. L. Rickett

Measurements of the rate of decomposition of austenite at constant temperature are commonly represented by plotting the percentage transformed on linear coordinates against time on either a linear or a logarithmic scale, a method that yields a curve that in shape resembles an integral sign (Fig. 1). A graph of this kind is not always convenient because extrapolation to the beginning or end of the transformation, or even intebrpolation, may be uncertain unless there are a large number of observations, which seldom happens; furthermore, the degree of consistency of a set of measurements is difficult to judge from such a curve. It is desirable therefore to find some mode of plotting, or even better to find a standard variety of graph paper, that gives a straight line instead of the integral shape. The straight line has many advantages; the number of readings required to fix the position of the curve is greatly reduced, interpolatiorr is easy and rapid, extrapolation can be carried out with greater confidence and, finally, the consistency of the measurements is readily estimated from the scatter of the points. The last advantage is particularly valuable when the data are obtained by direct microscopic examination alone, because they are influenced by the skill of the observer in estimating the relative size of areas, possibly also by undetected inhomogeneity of the specimen. A search for ways of representing the observations as a straight line yielded two methods which are described in this paper. The paper also includes an account of some interesting relations brought to light in applying these methods to the available experimental data. Usually the best way to derive such a method of plotting is to base it on established principles of chemistry and physics, as has been done, for example, for the temperature variation of the equilibrium constant of a chemical reaction. But so little is known of the mechanism of the decomposition of austenite, and so little is available in the way of well established background for changes of this kind, that it is simpler to rely upon purely empirical means. The general plan therefore is to study existing data with a view to finding some function of the direct observations that will

Jan 1, 1939

ALTHOUGH the open-hearth charge contributes CO, C02, H2, A and water vapor to the combustion gases and absorbs oxygen from them, in the main the thermal effects in the melting charge and molten bath can be considered independently of those in fuel combustion; the latter then is regarded simply as the source of the net heat required to finish a heat of steel. First of all, it should be remembered that a large percentage of the heat supplied to the bath is furnished by oxidation of the various elements in the charge itself. If this charge consisted of 80 to 100 per cent of hot metal and the oxidation were accomplished by blowing in air or oxygen, as in the bessemer converter, the net heat absorption would be negative; that is, the bath would contribute part of the heat required to keep the melting chamber hot, in addition to that contained in the finished steel and slag. In actual open-hearth practices, probably the nearest approach to this is in the duplex furnace, charged with bessemer-blown metal and some hot metal, where very little heat is required to complete the refining and nearly all the heat energy from fuel combustion is used to keep the roof and walls of the melting chamber up to around 2900 to 3000 F (1600 to 1650 C), so that the bath will not cool off during the refining. The other extreme is with all-cold charges containing around 80 per cent steel scrap and 20 per cent cast iron or cold pig iron, in which case a very large proportion of the heat in the bath at tap is supplied from the fuel combustion. THERMAL EFFECTS IN MELTING In a typical heat, the fuel furnishes about four million British thermal units per ton of steel produced. The heat required, for the metallurgical processes is not easily defined in useful manner but it ranges downward from about one million Btu, depending not only on the charge but on the manner of calculation. In, any event, this requirement appears. small in comparison with the

Jan 1, 1964

By Ralph J. Schilthis

Several investigators1-8 have reported evidence of the existence of native or connate water in oil-and-gas-bearing strata. Both water and salt have been detected in cores of oil sands that yielded oil and gas exclusively when produced. Electrical logs often reveal unexpectedly low resistivity through oil and gas sands, indicating the presence of some material that is a considerably better conductor of current than oil and gas. Furthermore, calculationsg of the oil and gas content of reservoirs based upon production and reservoir-pressure decline data indicate appreciably lower values than are arrived at under the assumption that the pore space is occupied completely by oil and gas. Origin and Occurrence of Connate Water in Oil-and-gas-bearing Formations The view has been expressed, 10-15 and is generally agreed upon, that the expulsion of oil and gas material from source beds and the subsequent migration and accumulation occurred in the presence of salt water. As the strata that usually form reservoirs for oil and gas were laid down by, or in the presence of, ancient seas, the pore space within the strata must have been saturated with salt water before the entrance of the oil and/or gas. Thus, the accumulation of oil and/or gas in the upper regions of structures suitable for reservoirs must have required displacement of the connate water therefrom. In the absence of any forces other than gravitational, it would be expected that the displacement of the connate water out of the zones finally occupied by gas and oil would be complete, and that the vertical distribution of gas, oil, and water in a reservoir would be strictly in the order of their densities. Apparently, however, surface and interfacial forces that will not permit complete segregation of the fluids are active within the capillary spaces comprising a reservoir. The effects of these forces on both accumulation and production of oil and gas have been the subject of study by a number of investigators.16-37 In general, the view is held that the character of most materials that make up the reservoir rock leads to preferential wetting of the rock by

Jan 1, 1938

By George A. Roberts, Robert F. Mehl

WHEN austenite first forms from aggregates of cementite and ferrite, it is not homogeneous.1 This inhomogeneity, consisting of both undissolved carbide and carbon concentration gradients, has a profound effect upon the characteristics of the austenite-pearlite reaction. The rate of formation of pearlite is increased by the presence of inhomogeneities2,3 and because of this (when the inhomogeneity is sufficiently pronounced) the hardenability of the steel is reduced,4,5 In addition to this kinetic effect, inhomogeneities will cause the direct formation of spheroidite from austenite at temperatures just below the Ae1.6-11 The present report attempts quantitatively to evaluate the effect of inhomogeneity upon the rate of the austenite-pearlite reaction, presents a method of determining the austenitizing cycle necessary to obtain "practical homogenization," and considers the effect of inhomogeneity on hardenability. EFFECT OF INHOMOGENEITIES ON REACTIONS NEAR Ae1 Few quantitative data are available representing the effect of undissolved carbide or of carbon concentration gradients upon the rate of the austenite-pearlite reaction. In procuring such data it is necessary to separate the effect of undissolved carbide from that of grain size, and this is not an easy task. The solution of carbide is always accompanied by an increase in the grain size, both effects contributing to the retardation of the reaction rate. It has been possible to make this separation and to obtain data that are independent of the grain size by the use of steels that differ only with respect to their tendency toward grain-coarsening. Steels C and D in Table I are such steels. These steels have been studied previously;1,2,12 they differ only with respect to deoxidation practice; C was deoxidized with silicon while D, teemed from a portion of the same heat, was deoxidized with additional quantities of aluminum in the mold. C therefore is what is normally termed a "coarse-grained steel" and D is a "fine-grained steel." These steels can be compared at the same grain size by heating C to a low temperature and heating D to an elevated temperature, producing a structure of austenite plus residual carbide in the former while forming homogeneous austenite in the latter; in such

Jan 1, 1943

By Clarence E. Jackson, George G. Luther

THE ever increasing array of information concerning the measurement of the effect of the welding process on the properties of a steel is an indication of the tremendous effort that is being expended in this field. The methods that have been considered may be divided into two groups: first, those that measure directly the effect of welding on the ductility of a steel, and, second, those that observe the change in some property, such as the hardness of the heat-affected zone, and assume a direct correlation between this change and the resultant ductility. The nick-bend test is a direct method designed for studying the effect of welding on the ductility of a steel. The test specimen (Fig. I) consists of a bar cut from a plate with a bead weld on the surface. The specimen is prepared with a saw-notch placed so as to restrict deformation to the heat-affected zone under the bead weld when tested as a static bend. Failure is caused by rupture of the low-ductility metal in the heat-affected zone. The angle at maximum load is used as an index of the effect of the welding process on the material. In the development of the nick-bend test considerable scatter was noted in some of the results, although the agreement of duplicate specimens welded at the same time and tested consecutively was excellent. Upon further investigation it was found that the change in ductility was dependent upon the interval of time between the welding operation and the testing of the specimen. For the six steels of Fig. a, the angle at maximum load in four cases was doubled and in one case was tripled. All steels that have been studied show an improvement in the angle of bend for longer intervals between welding and testing. This same behavior has been found in weldability tests using the Navy T-bend

Jan 1, 1945

By Paul M. Tyler, Oliver Bowles

The extensive employment of nonmetallic minerals antedates the use of metals, but only within the last two decades has the production of nonmetals begun actually to keep pace with the complicated activities which characterize the so-called Machine Age. The economic changes ushered in by the Industrial Revolution were reflected first in an increased demand for metals and for fuels. In the modern sense, therefore, the nonmetallic mineral industries are new and afford new opportunities for engineer and economist alike. A certain amount of caution is indicated, therefore, before attempting to apply ready-made formulas to the problems of these industries. Economics is not an exact science. In the field of production technology where the number of variables is fairly well known, the principles of economics are readily applicable, but as the student proceeds through the province of marketing into the unexplored regions of psychology and sociology he must distinguish carefully between scientific reasoning and purely metaphysical speculation, even when the latter masquerades as economics. The present paper attempts to prove no preconceived theorems and is designed primarily to stimulate careful thinking on sundry neglected phases of these industries. An attempt is made to differentiate the general problems into single aspects which afford promise of being comprehended separately; also, some fundamental statistical data are presented, but merely to indicate a method of scientific approach applicable to more intensive studies. Definition Before discussing the economics of the nonmetallic mineral industries, it is appropriate to consider what we mean when we say "nonmetallic minerals." This term, inasmuch as it is merely a negative description, is somewhat loose and ambiguous and gives rise to questions in regard to minerals that, like chromite or bauxite, are alternatively classed either as nonmetallic or as metallic minerals (or ores). The chrome ore used to make ferrochrome for steel manufacture is undoubtedly metallic in character; similar material destined for use as a refractory in the same

Jan 1, 1934

By J. B. Austin, R. L. Rickett

Measurements of the rate of decomposition of austenite at constant temperature are commonly represented by plotting the percentage transformed on linear coordinates against time on either a linear or a logarithmic scale, a method that yields a curve that in shape resembles an integral sign (Fig. 1). A graph of this kind is not always convenient because extrapolation to the beginning or end of the transformation, or even intebrpolation, may be uncertain unless there are a large number of observations, which seldom happens; furthermore, the degree of consistency of a set of measurements is difficult to judge from such a curve. It is desirable therefore to find some mode of plotting, or even better to find a standard variety of graph paper, that gives a straight line instead of the integral shape. The straight line has many advantages; the number of readings required to fix the position of the curve is greatly reduced, interpolatiorr is easy and rapid, extrapolation can be carried out with greater confidence and, finally, the consistency of the measurements is readily estimated from the scatter of the points. The last advantage is particularly valuable when the data are obtained by direct microscopic examination alone, because they are influenced by the skill of the observer in estimating the relative size of areas, possibly also by undetected inhomogeneity of the specimen. A search for ways of representing the observations as a straight line yielded two methods which are described in this paper. The paper also includes an account of some interesting relations brought to light in applying these methods to the available experimental data. Usually the best way to derive such a method of plotting is to base it on established principles of chemistry and physics, as has been done, for example, for the temperature variation of the equilibrium constant of a chemical reaction. But so little is known of the mechanism of the decomposition of austenite, and so little is available in the way of well established background for changes of this kind, that it is simpler to rely upon purely empirical means. The general plan therefore is to study existing data with a view to finding some function of the direct observations that will

Jan 1, 1939

By Edmund B. Kirby

This meeting marks the point at which the long-standing dissatisfaction with the mineral-land laws, the innumerable protests against them, and the many isolated efforts to obtain relief, have developed into a general movement for their revision. That part of the mining industry which is affected by these laws has three general organizations which are able to speak for it: the American Institute of Mining Engineers, the Mining and Metallurgical Society of . America, and the American Mining Congress; all of which are represented in this meeting. In the series of able and thoughtful papers presented here, prominent men have discussed the evils of the present laws and some of the reforms which should be made in them. We all appreciate fully the ultimate value of these studies; but we are also painfully aware of the fact that discussion of this kind has been going on for a quarter of a century without any other effect than a steady increase in the mass of printed records stored on library shelves. In order to get any practical result we Gust induce an indifferent government at Washington to act, and to do this we must unite in pushing some practical plan whereby it may act in a simple and effective way and with the least possible amount of criticism or opposition. The actual question before us is not whether the mining laws are bad; for their evils and absurdities are not only beyond discussion but also beyond the resources of a temperate and dignified vocabulary. It is not what particular changes ought to be made; for it is premature to make . specific recommendations until there is some one to listen to them. Moreover, we all know that there are wisdom and experience enough available, and awaiting that time, for the creation of a code which would be a model to the mining world. The practical question now is, how to obtain the revision; and since the American Mining Congress has of late restricted its attention to this phase of the problem I wish as one of its representatives here to present its views upon the matter.

Jan 1, 1915

By B. E. Parsons

Curtailment of production of crude oil, to the extent of effecting an approximate balance in supply and demand, was a problem confronting the oil industry in California throughout the year 1930. At the beginning of the year, with drilling operations only slightly checked, the California industry faced a steadily increasing potential production, an actual production in excess of market requirements and stocks of crude oil and refined products which had reached staggering proportions. During the year, the intensive development of the Playa Del Rey field and extensions to several oil fields, together with flush production from numerous large wells from both new and old fields, caused a steady increase in the state's potential production to a record peak in November of 1,186,000 bbl. daily. Despite the burden of this steady stream of flush production and the handicap of incomplete cooperation in several fields, curtailment successfully lowered the trend of crude oil production in California, except for the period of an open-flow test to determine actual potential production in several important fields in February. Under the curtailment programs in effect, the state's production of crude oil for the year was reduced 22 per cent. under the production of 1929 and even slightly under the production for the years 1927 and 1928. The total stocks of crude oil and refined products were reduced 2.7 per cent. during 1930, as compared to an increase of 30 per cent. in total stocks of all products during 1929. Drilling operations were reduced 28 per cent. as compared to drilling activities during 1929. Voluntary curtailment of drilling programs by many operators, particularly the major companies, accounts for the greatest portion of the reduction in drilling activity. The decline in drilling activity at Santa Fe Springs and in the east-side fields of the San Joaquin Valley was more than offset by development in new fields and extensions to deeper zones of old fields. There were 755 new wells completed during 1930, as compared to 910 completions in 1929. At the close of the year, 220 wells were drilling in the oil fields of California, 9 of which were being drilled in search of deeper producing horizons.

Jan 1, 1931

By H. S. Munroe

AN elaborate discussion under this heading formed a chapter in one of the reports made by Professor Raymond as Commissioner of Mining Statistics.* In a subsequent report- was printed a paper, by Mr. William Main, Jr., of Columbia, South Carolina, containing a theoretical investigation into the effect of the velocity of impact on the effective ditty of stamps. A visit to the Lake Superior copper region last summer suggested an inquiry into the relative efficiency and economy of the enormous steam stamps of the copper-mills, as compared with the results obtained with the cant and tappet stamps commonly used in the West. The atmospheric stamp used at the Phoenix Mill promised to add interest to the inquiry, as giving an example of unusually high speed, this stamp making 160 drops per minute. In introducing his subject Dr. Raymond makes the following remarks, which are quite apropos of the present investigation : "In considering the economical application of stamping machinery, we meet, at- the beginning, with serious difficulties in obtaining accurate data for comparison. The weight and fall of stamps vary as the shoes and dies wear out; and this may lead to a change of speed also. Moreover, defects in engines, boilers, or machinery for the transmission of power, may occasion serious losses, which cannot fairly be charged to the arrangements of the stamps proper. Again, the capacity of stamp-mills is directly dependent, in some degree, upon the nature and extent of discharge, fineness of screens, and other peculiarities of the battery. Finally the hardness and tenacity of the rock crushed varies so much that comparisons between different localities cannot be implicitly trusted. The safest experiments are those made in the same mill, by changing first one and then another condition of working; but this is seldom possible for such * Mineral Resources West of the Rocky Mountains, 1871, p. 380. †- Mineral Resources West of the Rocky Mountains,, 1873, p. 345.

Jan 1, 1881

By Donald Barton

Geophysical methods of prospecting taken as a whole do not seem to offer much promise to a young man planning to enter them in the future. They have come to stay, to be sure, and they will continue in at least moderate use for a long time. Domestic use of those methods presumably is at a maximum at the present time. Geophysical pros-pecting is expensive; the effects of the law of diminishing returns in efficiency in finding prospects can already, be recognized. Small oil companies, independent oil operators, and royalty buyers have been doing much geophysical work. But in face of the increasing costs of discovery of prospects and in face of the probably decreasing favorability of the prospects discovered, I expect to see a sharp drop in their use of geo-physics within the next 10 years. The major oil companies and the larger small oil companies will continue to use geophysics indefinitely, but it seems doubtful whether the very extensive domestic campaigns of a few companies will be maintained for many years, certainly not for 10 years. The use of the geophysical methods in foreign countries has not yet reached its peak, and probaby will continue to increase for several years. That peak level of activity will probably be held for 10 years, although the site of maximum activity will shift from country to country; by the end of 25 years from now, I should expect the foreign use of the methods to have leveled off to one-fourth to one-half the peak level. Foreign service in geophysics does not seem to offer an attractive career, except for men of exceptional disposition. Young men just out of college, who are willing and who can afford to spend three or four years having a fling at adventure before settling down, will find it attractive, but when their tour of foreign service is over, they probably will have harder work finding a job than when they were seniors, and their foreign experience will count for little, except for further foreign service. A few men, mainly the higher men, will have headquarters at civilized or semi-civilized cities and towns or at permanent oil-company towns, and can

Jan 1, 1938

By Portland P. Fox, Berlin C. Moneymaker

THE development, within recent years, of core drills capable of drilling holes up to 72 in., or even more, in diameter, has made possible an entirely new and valuable method of geologic exploration. Although little used until recently as an exploratory tool except in the United States, by the Tennessee Valley Authority and the Corps of Engineers of the U. S. Army, for the exploration of damsites, the large-diameter core drill may be used to good advantage in other types of geologic exploration. Its principal utility is that of supplementing, rather than replacing, other means of exploration. Although core is frequently recovered intact, the greatest advantage of large-diameter drilling is that the holes produced are large enough to be entered by the geologist and engineer, and thus afford an excellent means of examining undisturbed rock. The walls of the holes are smoothly cut, and in some rocks nearly or quite polished, so that the most minute details of structure and stratigraphy are clearly disclosed. Such features as faults, joints, bedding planes, weathered "seams," and beds or layers of soft materials, which are not always amenable to disclosure by cores recovered from small-diameter holes, are conspicuously displayed in the walls of large holes. Frequent reference to the drilling of large-diameter holes is made in engineering literature, but comparatively little emphasis has been placed on their value in geologic investigation. It is, therefore, intended that the present paper acquaint the geologist, as well as the engineer, with the large-diameter core drill and the technique involved in its use, and also with its advantages, disadvantages and limitations as an implement of geologic exploration. THE EQUIPMENT The equipment generally employed in the drilling of large-diameter holes consists of a trunnion-type drill head mounted on a sliding base, which allows it to slide clear of the hole and thus permit the introduction

Jan 1, 1938

By R. A. Matuszak

This paper discusses the major portion of the hoist (drag or crowd) system and it shows how static control accomplishes its major aims. In 1959, the first truly static control for Ward-Leonard equipped electric excavators was designed, developed and placed in service. The control system, originally intended only as a more modern electronic type of alternate to the proven rotating amplifier control system has since proven to be much more. When they conceived the original system, the designers had much more in mind than simply replacing the rotating amplifier with one that had no moving parts. The long range plan, which started with the initial system consisting of an SCR (silicon controlled rectifier) preamplifier and magnetic amplifier power amplifier, called for eventually, a control system low in cost and maintenance, relatively simple in design and extremely reliable. The plan also included the elimination of as many of the shortcomings of the rotating system as possible. No small accomplishment, when it is considered that the rotating control system had been, with only minor modifications, the standard of the industry for 20 years. The final step in the original design plan called for the eventual development of an amplifier that could be used as one of the basic building blocks of the future. DEVELOPMENT RESULTS Since the successful unveiling of the first static control system, continuous development has resulted in a slow, but sure progression along the path described by the original plan. The first version of the new control corrected one of the shortcomings of the rotating system by removing the necessity of operator anticipation. This was accomplished by making the system faster in response so that the operator noticed virtually no delay between his movement of the master controller and that of the machine. Thus, after the operator became familiar with the operating characteristics of the machine, he was able to become more relaxed while digging. The natural result of this accomplishment was higher production. All of the subsequent versions of this new control were even faster than the initial design. Although it was not distinguishable by the operator, the further increase in response resulted in large gains in the limiting of transient torque peaks applied to the machine while digging. Also, a more effective control of the torque and power peaks was obtained when plugging the motion being controlled to a stop. (Plugging is the use of the Ward-Leonard ability to regenerate power and absorb energy from the load to

Jan 1, 1964

By Frank B. Gilbreth

The problem of the crippled soldier in industry is not a problem of war work only; it is a problem of industrial development. As individuals, each one of you is seeking to provide our maimed heroes with such teaching as will render them, in the shortest possible amount of time, productive and satisfied members of the community. As individuals you are interested in the organizations that are preparing to receive these men, to train them and to place them at that work for which they are best fitted. As an organization, it is now your duty to take up the industrial end of the problem, to investigate existing conditions in the industries, to discover where the opportunities for employment lie, and so readjust industrial practice that the cripples may be utilized to their own and the community's good with the least shock to themselves or to the industries, and with the greatest amount of permanent benefit to all concerned. We have divided industrial opportunities suitable for cripples, roughly, into three classes. First, such as already exist in the industries, which can be set aside for cripples only, present occupants being transferred to other work for which they can be fitted but which is not suitable for cripple work; second, opportunities in the industrial world that, through changes in the working equipment or tools, or through appliances attached to the cripple himself, can make the cripple a competitor of the sound worker; third, opportunities not existing at present in the industries, but which could be introduced for the good of the community without placing the cripples into competition with any existing class of workers. As typical of the first type of occupations for cripples, we have mentioned that of store-keeper, of the second type that of typist,2 and of the third type that of dental nurse.3 The last occupation can be so arranged as to take from the overworked dentist the work of cleaning teeth; and

Jan 1, 1918

By Joseph L. Gillson

BRAZIL has had an industry based on ocean beach deposits of heavy minerals containing monazite, zircon, rutile, and ilmenite for well over 40 years, but except at the very earliest period, prior to 1906, and again during World War 11, has this industry been at all comparable in size with similar operations in other countries. Limiting factors have been neither a lack of reserves nor lack of markets (except for zircon). Although poor local transportation and shipping facilities have handicapped the development in Brazil, these conditions were perhaps equally bad (when mining operations started) in the Indian State of Travancore, and in New South Wales and Queensland, Australia, in which states the principal production of beach deposits of heavy minerals has occurred. The outstanding restraints on the Brazilian industry have been the lower quality of the Brazilian minerals, the relative small size of individual deposits that were known until recently, the lack of interest of Brazilian investors in mining ventures, and the unfavorable climate for investment of foreign capital under Brazilian mining law. The lower quality of the minerals is indicated by the fact that the Brazilian monazite carries only 5 to 6 pct ThO2,*, and the ilmenite 56 1/2 pct TiO2, whiteness of the Australian zircon. An inadequate market for the abundant zircon that will be avail- able in any operation in Brazil is certainly a heavy restraint, since otherwise it could be an important byproduct. The oxide of zirconia, baddeleyite, that has come from Brazil is from other sources. 1 Since the Brazilian beach sands carry only a little rutile, that mineral has not been available as a valuable byproduct to help finance the operations.

Jan 6, 1950

By B. M. Larsen, T. E. Brower

INTRODUCTION THIS discussion is based on statistical manipulation and evaluation of operating data from several commercial blast furnaces which include rather wide variations in practice. We are concerned here mainly with the effect of manganese on sulphur elimination under operating conditions in commercial blast furnaces, but this effect can be outlined more clearly by including certain other variables such as silicon in iron and slag basicity, which are all in part interrelated. Real progress in understanding all of the smelting-zone reactions in this process requires more laboratory studies of slagmetal melts similar to those in the blast furnace, with careful control of oxygen pressure. Such experimental work is very difficult, however, and in the meantime, with the present scarcity of more fundamental data, such statistical trends and correlations as can be obtained from commercial furnace operating records may help in choosing laboratory test conditions as well as adding to our knowledge of operating procedures. We do not know just why the furnace data are apparently so irregular that statistical treatment of large numbers is needed to obtain accurate trends. It is .partly caused, no doubt, by the many simultaneous variables present, but there are perhaps also such factors as: (I) the continual swings up and down so characteristic of the process; (2) difficulty of accurate sampling of co-existing phases, as well as (3) the presence of both equilibrium and rate factors as a result of the fast driving of the process, In desulphurization, for example, the flow of thin layers of slag and metal over solid coke surfaces, plus the contact between droplets of iron falling through the slag layer in the hearth, would lead one to expect a close approach to equilibrium, On the other hand, most of the critical part of sulphur removal may occur in a short time and distance below the tuyeres with perhaps an accompanying decrease in oxygen pressure and the concurrent reduction of much of the silicon and manganese, so its degree of approach to equilibrium may be quite variable. PROBABLE CHEMISTRY OF DESULPHURIZATION Since there is little evidence that sulphur atoms in the iron solution are associated to any appreciable extent in molecules such as MnS, the transfer from slag to metal and back again can be written:* [(FeS) -, [FeS],[I] hence the following reactions seem most probable in the slag phase, (FeS) + (CaO) = (CaS) + (FeO), [2] and, (FeS) + (MnO) ;:2 (MnS) + (FeO). [31]

Jan 1, 1948

By W. H. Emmons

The exploration of deposits of the metals will never become an exact science. There will always be an element of uncertainty in prospecting and developing mines. In countries where the surface has been closely scrutinized, most of the deposits whose outcrops contain valuable metals have probably been discovered. Many metalliferous deposits, however, are normally so much altered at the surface that the true significance of their outcrops is likely to be obscured. If a deposit is not exposed, its presence may become known by some one of its characteristics that is different in kind or in degree from a similar feature of the associated rock. Thus, a deposit that is not exposed may be discovered because of its magnetic property. So few minerals are strongly magnetic that the value of magnetic surveys is limited, but the dip needle has nevertheless proved of great aid in locating magnetic belts, and these in some regions are associated with workable iron ores. The Cuyuna Iron Range of Minnesota, which does not exhibit any outcrop of iron ore, was discovered by drilling "areas of attraction" that are due to belts of magnetic rocks associated with the iron ores. In some regions the use of the dip needle is justified, even if it does no more than reveal the strike of the rocks, since a knowledge of the latter enables the driller to locate and point his holes to advantage. The measures of gravity by the use of the pendulum are so accurate, or the limit of error is so small, that one might detect the presence of a concealed tabular deposit approximately at the surface, 34 ft. (10.36 m.) thick, having a density double that of the surrounding rocks. However, not many deposits have a density twice that of ordinary rocks and a thickness as great as 34 ft.; if they lie a short distance below the surface the density or the thickness must be even greater. Consequently, there is not much hope of sufficiently developing the gravity method of detecting deposits of heavy ores to make it of practical value. If the limit of error could be reduced to about one-tenth the present factor, and if the rather tedious and painstaking methods of determining gravity that are now in use could be simplified, the method would promise some degree

Jan 1, 1918

Jan 1, 1924