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By George Stern

THE purpose of this investigation has been to study one method for making ordinary carbon steel by the powder metallurgy technique. This method con- [ ] sists of pressing and subsequently sintering an intimate mixture of iron powder and graphite in a suitable atmosphere to produce a steel. Two types of iron powder have been studied, electrolytic and reduced. The sintering of mixtures of loose carbonyl iron and carbon black for several hours at 1000° to 1100°C. (1830° to 2010°F.), followed by forging of the resultant ingots to bars, has been studied by Offermann.1 Trail' has reported on the properties of hydrogen-reduced and electrolytic iron powders, both containing 0.5 per cent carbon. Methods for making steel bodies by powder metallurgy have also been sug- [ ] gested by Goetzel,3 who recommends the addition of steel powder of well-defined carbon content to pure iron powder, and Volterra,4 who suggests compaction and subsequent sintering of a mixture of steel powder, iron oxide and iron powder. Additional methods for making steel bodies by powder metallurgy have been reported in the literature by Koehring,5 Allen,6 Balke,7 Wulff,8 Boegehold,9 and others. 10,11,12 It is felt that the method of pressing iron powder and graphite, as described herein, lends itself best to production because of the lubricating action of the

Jan 1, 1946

By Edward Sampson, Allan B. Griggs

SURVEYING of many holes drilled by the U. S. Bureau of Mines in the Metaline district has shown surprising deviations. The holes start in the Ledbetter slate (Ordovician) and pass into the underlying gently dipping Metaline limestone (Cambrian) at varying depths, locally in excess of 1000 ft. All holes start vertical, but one had deflected as much as 35° at a depth of only 300 ft. One hole was found to be deflected 70° at a depth of 1000 ft. These deviations were not indicated to the drillers by any action of the rods or machines. Analysis of the survey data in the light of the observed geology indicates that the holes deviate most in the Ledbetter slate and scarcely at all in the Metaline limestone. The upper part of the "limestone"' in most holes is a massive rock strongly altered by hydrothermal action and essentially homogeneous. The slate is only obscurely bedded but has a cleavage, varying from slight to strong, which is unrelated to bedding. Drill holes have deflected to become nearly perpendicular to the cleavage. Several plans and cross sections are submitted showing the behavior of various holes.

Jan 1, 1946

By A. G. Roach

THIS paper deals with a plant built under joint agreement between the Canadian and United States Governments to supply the strategic mineral, corundum, at a time when African production was dwindling and war demands still increasing. The operation began in September 1944, retreating the tailings from a former mill by gravity methods, and is still in production (Sept. 1946). In 1942, when it became apparent that South African production would be insufficient to meet mounting wartime requirements of corundum, a survey was made of Canadian sources of the mineral, at the request of the Foreign Economic Administration of the U. S. Government. The investigation1 indicated that the quickest and cheapest supply would be obtained by reworking the tailings deposit at Craigmont, Ontario. Sampling of the dump by Canadian Government engineers revealed that 125,000 tons of tailings, averaging 2.96 pct corundum, was available for retreatment. Ore-dressing tests on representative samples of the deposit were conducted by the writer in the laboratories of the Industrial Minerals Section of the Department of Mines and Resources at Ottawa; and gravity concentration on tables was indicated as the most suitable method of treatment. Decision to proceed with the project was deferred until May 9, construction was begun on May 18, and tune-up operation of the plant begun on Sept. 15, 1944. CORUNDUM-ITS PROPERTIES AND USES Corundum is an oxide of aluminum having the formula A1203. Its outstanding characteristic is its great hardness; 9 in the Mohs scale. In this respect it is second only to the diamond. It usually occurs in barrel-shaped crystals in nepheline syenites and other feldspathic rocks deficient in silica. It has a specific gravity of 3.95 to 4.1 and is insoluble and infusible. In color it ranges from white, through red and green, to black. Ruby and sapphire are gem varieties of corundum. Corundum is supplied to industry as closely graded grain.2 The coarser products (10 to 24-mesh) are used largely for snagging wheels in the steel-castings industry, while the finer grades (from 70-mesh down to flours) find a wide application in the polishing of lenses and for other uses in the optical trade. All sizes of corundum grain are in close competition with synthetic abrasives such as carborundum and alundum. In some fields of application the artificial product is superior to the natural grain but not in all. The shape of the particle and its behavior under conditions of actual use determine its sphere of employment. The United States is the largest consumer of corundum, annual consumption in peacetime approaching 3000 tons; during the war this figure was roughly doubled. During the years 1902 to 1913, the bulk

Jan 1, 1946

T.P. 1958 D. H. DAVIS.*-Mr. Carris has ably pre¬sented the problems of coal preparation, particularly those brought about as the result of increased mechanical loading. Many mines are now crushing the run-of¬-mine raw coal through 12 or 15 in. immediately after it is dumped from the mine car and before it is handled by conveyors. At certain mines the removal of large slate mechanically has been solved by the installation of scalping screens consisting of bars or rails set at spacing of 12 to 15 in. on the top deck of the main raw-coal sizing screen. At the plants where these are in use, the plus 12 or I5-in. raw material contains 60 per cent or more free rock or slate, so that it is easier to pick coal than to pick rock. After the screening at 12 or 15 in. is accomplished, the oversize material is diverted to one side of the shaker, where a picker allows the refuse to pass off the shaker into a chute and guides the coal back onto the shaker. After the large rock has been removed, it is then advisable to reduce the size of rock by crushing before putting it onto a conveyor. A great saving in picking labor has been made by the use of such scalping screens, which in addition has maintained the plant capacity when handling a dirtier feed. The great increase in percentage of coal under 1/4 or 3/8 in., coupled with a greatly increased percentage of free impurities in this size, is the most serious problem that has been brought about by mechaniced loading. Many plants that formerly prepared good quality 1/4-in. to o or 3/8-in. to 0 slack by air¬cleaning are faced with installing facilities for wet-cleaning mechanical and heat-drying and water clarification. The change to wet prepa¬ration of fines usually affects the marketing problems for many coal companies. There will also be problems involving wastage of fine solids and stream pollution. Much work will be necessary for improvements in present practice. Pneumatic and electrostatic methods for cleaning fine coal should receive consider¬able attention in an attempt to avoid wet¬cleaning of fines. The preparation supervisor and the plant personnel should not be satisfied merely to run the cleaning-plant machinery and assume that the job will be done for them. Coal is a heterogeneous substance and in many instances is constantly changing. This is more true when full-seam methods are in use. Only persons trained to observe closely and make the necessary changes in plant operation will be able to solve the many problems that will be imposed on the preparation plants. The plants will require skillful and observant operating men. With full-seam mining methods, seams of roof coal will often be mined. Under the former mining systems these strata were not mined and frequently they contain a high per¬centage of bony and banded partings. The mining of this coal will greatly alter the washability and specific gravity characteristics of the feed to the plant. Often the percentage of 1.40 to 1.60 sp. gr. increased from 3.5 to 7.5 per cent, or nearly a 1.0 per cent increase in the ash content of the 1.60 sp. gr. float coal. Thus the cleaning problem is much more difficult, and it is unlikely the same ash content of cleaned coal can be produced as before without a decrease in recovery or the produc¬tion of a "middlings" product. Mr. Carris had this in mind when he said "The quality of the

Jan 1, 1946

By H. M. Stewart, R. A. Grange

MANY steel parts may crack if quenched directly into a bath near room temperature, but not if quenched at a temperature just above the range where martensite forms and then allowed to cool slowly to room temperature. This latter procedure, which is the basis for such modern hardening techniques as "martempering " and "isothermal quenching," may entail some sacrifice in depth of hardening but very little, if any, in intensity of hardening. In planning such treatments, it is necessary to know the upper limit of the martensite range, and often desirable to know the proportion of martensite that would form on cooling to any lower temperature; furthermore, the tendency of a particular steel to crack when quenched is unquestionably associated with the temperature range of martensite formation, and consequently knowledge of this range aids in selecting the optimum composition for a given application. Certain puzzling phenomena associated with the properties of quenched and tempered steel may be at least partly clarified as the manner in which martensite forms is more fully under- stood. Information on the temperature range of martensite formation, particularly with respect to how much martensite results from quenching to a given temperature, is lacking for most commercial types of carbon and low-alloy steel. These considerations led us to study martensite formation in 14 carbon and low-alloy steels. The resultant data may be directly used in the following ways: (I) for selecting the lowest quenching temperature at which no martensite will form; (2) for selecting the highest quenching temperature at which virtually dl marten- site will form, thereby avoiding quenching to an unnecessarily lower temperature with attendant danger of cracking; and (3) in producing a mixture of tempered marten- site and bainite, which in high-carbon steels has been found to possess somewhat better ductility than tempered martensite, yet does not require the full transformation time necessary for a completely bainitic (austempered) structure. PART I. OBSERVATIONS OF MARTEN- SITE FORMATION IN FOURTEEN CARBON AND LOW-ALLOY STEELS Transformation of austenite to pearlite or bainite can be conveniently studied by observing the change that occurs over a period of time at constant temperature; such studies are the basis of the isothermal transformation diagram (S-curve). This isothermal technique is not applicable to martensite formation, which occurs within a time interval too small to measure, at least by any ordinary means. For all practical purposes, therefore, martensite may be regarded as forming only during cooling and not during a period of time at constant temperature. As austenite is cooled below

Jan 1, 1946

[Abrahamson, Guy C., (5'43) Lt., 0-880861, Hammer Field Fresno Calif. Adamec, LAW, (8'42) c/o Braden Copper Co., Rancagua, Chile. Adams, Karl S., (9'43) Univ. of New Hampshire, Durham, N. H. Agnilar, Roperto Q., (9'43) Texas College of Mines, El Paso Texas. Ainge, B'onald Farra, (943) Otago University, Dunedin, New Zealand. Akaran, Cevdet A,, (9'44) Pennsylvania State College, State College, Pa. Albala, Americo, (5'44) School of Mineral Industries, The Pennsylvania State College, State College, PA.]

Jan 1, 1946

By V. A. Cooney

Introduction For the compliment paid me by the Institute's kind invitation to speak this afternoon, I am very grateful. For the astuteness of your officers in determining that encouragement should be given, through the medium of a paper, towards accident prevention in coal mines, the coal industry cannot but be grateful. Some day, and let us hope soon, a more developed paper may supersede this one. In the meantime, if some knowledge of what one coal field has been able to accomplish, even in the initial stages of its effort, will induce other fields and other sections of the mining industry to launch similar experiments, much good will result and a more developed dissertation on the subject will make its appearance.

Jan 1, 1946

By Maynard H. Jameson

Earlier investigations of the potential-drop-ratio method of electrical prospecting have indicated that under suitable conditions this method is well adapted to the location of formation boundaries in stratified ground. A description of this development was given several years ago by H. Lundberg and Th. Zuschlag.l The curves published by these authors for the potential-drop-ratio variation above a horizontal contact indicated a definite relation of the position of the curve peak to the depth of the interface. The theory underlying this relation was subsequently studied by Z. Mitera in greater detail,' and the theoretical deductions were compared with the results of tank experiments. The investigations available at this writing were confined to studies of horizontal formation boundaries. It is the purpose of this paper to extend the scope of the previous work to the problem of dipping layers. Theory Consider the case of three media of different resistivities, whose interfaces are not parallel. If a point-source is located in one of these interfaces, its images do not lie in a straight line, but on the circumference of a circle whose center is at the hypothetical junction of the interfaces. R. F. Aldredgea determined the relation that exists between the degrees of dip of the two interfaces and the distances between the various images and the point for which the potential is to be found. As seen in Fig. I, three media of resistivities PO, p1, and p2 are involved, and the source I is located at the interface of the media Coo) and (p1). The perpendicular depth of the lower interface is h, 0 is the dip, R is the distance between source I and potential point P, and r is the distance between the images and that point. To distinguish between images lying above the ground interface and those below, the notation "odd" and "even" images will be employed; images below the ground interface will be termed "odd" and those above "even." The following relations govern the distances between either kind of images and the potential point: EvEn Odd Ta — R r1 - [rl] - [RS + 4h(h + R sin 01½ r, = [r] =. [R1 + 4h cos 0)2(h + -R sin 0)1½ ri - [r3] ={r3} [R* + 4h(4 cos2 0 - i)1 (h + R sin 0)l½ r4 = [r4] = [R2 + 4h(4 cos $ cos 30)1 (h + R sin 0)]½ r, — [r4] - [R2 + 4h(4 cos9 R cos 20 + cos 48)2 (h + R sin 01½ I RI + 4h[2 cos 30(4 cos2 0 - I)12 (h + R sin 8)1 ½ rn - [r4] - [R2 + 4hlf(cOs 0)18(h + R sin R)l½ As previously pointed out, the images of the source are on the circumference of a circle. If the angle of dip is 0, the angle measured from the horizontal to the first image is 28; to the second image it is 48, and so on. Since the limit of the reflecting interface is at its outcrop, the last possible

Jan 1, 1946

By Victor Azbe

Introduction Lime enters our daily life in many ways. Our building, chemical, agricultural, sanitary, and industrial endeavours depend on it to such a great extent that it could probably be called the most important inorganic chemical, and the extent to which it is used might be considered an index of industrial development. Industrial limes vary greatly in quality, due to internal structure and other characteristics. They may be good or bad, sensitive or slow to react. While improper manufacture may not greatly alter the appearance of the lime, it may affect its properties considerably and thus its suitability in the many processes in which lime is used. In some of the processes, one kind of lime is wanted, in others another. While the nature of the stone from which it is made has much to do with whether a lime is suitable or not, its burning and hydration are the crux of the matter. Up to not so many years ago, the knowledge of lime burning was rather imperfect and it is only relatively recently that its manufacture is approaching the state of a higher industrial art. This slow development was in part due to lime manufacture being scattered among many small concerns who, independently, either lacked the inclination or could not afford to strive for a higher technical development.

Jan 1, 1946

[MINING METHODS PHILIP B. BUCKY, Chairman WILLIAM J. COULTER. Past Chairman J. B. HAPPER, Vice-Chairman LELAND A. WALKER, Vice-Chairman, CLYDE E. WEED, Vice-Chairman E. D. GARDNER, Secretary]

Jan 1, 1946

By Paul J. Sirkegian

The problem of properly controlling the movements of underground trains in the Emma Nevada and Morris Brooks workings of the Consolidated Coppermines Corporation of Kimberly, Nev., became more complex as the rate of production increased. Ore from these mines, which are connected through a 7000-ft. single-track haulageway (Fig. I), is hoisted through the Emma Nevada shalt. All production to date has been from one level. Because of heavy ground, even on the main haulage horizon, experience has shown that it is necessary to have a minimum cross section in the drifts, thus making it impractical to have a double track system. In 1937, production was 3000 tons per day; in 1938 it was increased to 6000 tons per day and in 1940 to 9000 tons per day. Each increase necessitated a revision in the method of controlling the underground traffic. In 1937 the tramming signal system consisted of a few signal lights in the main haulage drift. These lights were two 100-watt bulbs in a metal box that had one green and one red lens on each side. The box was mounted on the underside of a drift cap timber and could be seen For a considerable distance. The lights were so arranged that all boxes showed either red or green at the same time and all were controlled by a magnetic contactor at the entrance to each lateral drift. When the lights showed green, the main haulage was clear of traffic and a train could enter it. As the motor entered the main haulage drift, the motorman pulled the cord of the magnetic contactor switch, thus changing all the main haulage lights to red, which indicated that no other train could use the main haulage until the first train had turned into a lateral drift. When a train left the main line, its motorman pulled the cord connected with the magnetic contactors, causing the haulage lights to show green again. This arrangement permitted only one train at a time to use the main haulage and thus limited the number of train trips per shift, but it was satisfactory when the ore handled was only 3000 tons per day. Second SystEM Installed With a gradual increase in production it became necessary to place a train dispatcher in charge of all trains. He controlled their movements orally, giving his orders direct or by mine phone, instructing them where to load, when to leave for the station and when to return. His objective was to group several trains traveling in the same direction. Because of the human element involved, some mistakes were made. The danger of a serious collision was always possible. There was a 90° turn and curve in the underground haulageway, therefore travel in this section was always dangerous if mistakes were made in directing traffic. To protect the train crew, particularly the rear switchman who rode the last car or caboose, a two-way push button and flash-signal system was installed on the

Jan 1, 1946

By Alex U. Miller

Since its beginning, the occupation of coal mining has been considered hazardous. It is true that there are hazards inherent in mining, but it is believed that most of them, at least, can be guarded against. Moreover, many man-made hazards can be eliminated by officials and workers adopting safer practices. Notwithstanding the hazards in coal mining, the fatal accident rate in the United States has improved. During the, period from 1911, to 1941, inclusive, the fatal accident rate varied from 5.35 to 2.22 per million tons of coal. With many handicaps during the war period, 1942-45, such as the lack of experienced manpower. and the, employment of untrained men, the increased average age of workers, and the shortage of equipment and supplies, the industry s ill further reduced its accident rate, so that it ranged from 2.30 to 1.724/ deaths per millon tons of coal. During 1944, 684,000,000 tons of coal was produced with a rate of 1.91, and during 1945, 631,000,000 tons was produced with a rate of 1.724/ deaths per millon tons of coal. The accident rate for 1945 was the lowest for the industry since records have been compiled.

Jan 1, 1946

By P. de Vitry, Willis P. Mould

THE wire saw is a tool not less than 60 years old, probably nearer 100 years old. It was developed in Europe and is reputed to have originated in Belgium. Frombold is said to be the original patentee. [ ] Wire sawing equipment, as indicated in Fig. I, is very simple. It consists of a three-strand wire cable, usually 3/16 or 1/4 in. in diameter, or a single flat ribbon of medium hard, tough, alloy steel twisted into a helix of those diameters, made to form an endless belt of any length up to several thousand feet. The wire is guided into the cut by sheaves mounted in slides on steel columns situated close to either end of the cut. The feed motion usually is controlled either by gravity or by hand-operated feed screws. The steel columns or "standards" range from 15 to 30 ft. in length. At the top is a swiveled arm supporting a sheave similar to the traveling sheave below. Immediately under the swivel-mounted sheave is a guy plate or collar with shackles attaching four chain or wire-rope guys with suitable tightening devices, or with two guys and two jack legs for supporting the standard vertically or at any desired angle. The usual drive is by a 10-hp. motor through a gear reducer, on which are mounted two grooved sheaves, one of which is keyed and the other free running on the shaft. Tension is provided by a car running on a track in line with the driving sheave

Jan 1, 1946

By D. M. Davidson

THE drill sampling and evaluation of the Piney River ilmenite property was carried out during the early part of 1944 by E. J. Longyear Co., using the company's standard core-drill outfits to complete 44 holes to an average depth of 110 ft., from which were collected 1100 samples. The Piney River ilmenite-apatite lode is 25 miles north of Lynchburg, in Nelson and Amherst Counties, Virginia (Fig. I). Its elevation is about 900 ft. above sea level and it lies in the old pre-Cambrian complex of crystalline rocks that make up the Piedmont physiographic province lying east of the Blue Ridge Mountains. The terrain is gently rolling and well watered, and is drained by the Piney and Tye Rivers, which are tributary to the James. GEOLOGY The Piney River ore body comprises the upper, weathered part of a tabular basic rock, which occurs in a large area of granite-gneiss. The section containing profitable ore is about 3000 ft. long. It is separated naturally by thinning, into northeastern and southwestern segments with widths of 300 and 100 ft. respectively. The dip averages 45° southeast but steepens locally (Figs. 2 and 3). The unaltered rock is an even, granular mixture of feldspar, ilmenite, and apatite, to which Watson1 gave the name Nelsonite. The decomposed ore body, which is now being exploited by open cut, is a yellowish clay material in which black ilmenite and glassy apatite are the only conspicuous minerals. An economically important structural feature of the deposit is a banding of minerals coinciding with the dip and strike of the dike. This is more promounced in the footwall of the northeastern part of the intrusive, where there is also a higher than average concentration of ilmenite. According to Watson,1 the Ti02 content of the Nelsonites of this region ranges from 10 to 42 per cent, while P205 varies from 4 to 15 per cent. It is inexpedient at present to disclose exact metal content of the Piney River ore body; suffice it to say that the average tenor lies well within the extremes noted by Watson. SAMPLING METHODS AND PROCEDURE During a preliminary inspection of the ore body, Longyear engineers surmised that because of its soft, clayey character, drill sampling would yield little core, therefore they made all possible preparations to procure accurate samples of the drill cuttings, or sludge. The first requisite in obtaining representative drill cuttings is to secure their full recovery. Only under certain conditions, and by employing a most careful and rigid sampling technique, is this possible. There must be no loss of the water circulating in the hole, and the velocity

Jan 1, 1946

By Stanley Davidson

Introduction The ore deposit mined by Falconbridge Nickel Mines, Limited, is one of the numerous nickel-copper sulphide bodies marginal to the large oyster-shaped mass of differentiated norite in the Sudbury district, famous as the world's most important nickel producing field. The unique character of the ore deposits of the district has resulted in its intensive geological study over a period of more than fifty years. The results of these studies have given rise to a voluminous geological literature and to a great deal of controversy as to the genesis of the ores. This description of the structural geology at the Falconbridge mine is presented in the hope that it may form a small part of the chain of evidence leading to a reasonably satisfactory explanation of the ore genesis. The mine, named after Falconbridge township in which the deposit occurs, lies along the southeast margin of the norite mass which, however, is here concealed beneath a deep mantle of glacial sands and gravels averaging over 100 feet in thickness. As a consequence, the deposit was not discovered by the early prospectors, and it was not until 1916-17 that E. J. Longyear, of Minneapolis, located the ore by drilling. The discovery was foreshadowed in 1899 by the work of Thomas A. Edison, who found indications of the deposit by what is believed to have been a combination of magnetic and electrical geophysical surveys. He sank a prospect shaft over what has to date proven to be the largest and richest ore section in the mine. A wet quicksand layer at the rock surface proved impenetrable, however, and the "Edison' shaft never reached bed-rock.

Jan 1, 1946

By W. C. Krumbein

Geological problems are approached from a geometrical (space relations) viewpoint, a kinematical (time sequence) viewpoint, or a dynamical viewpoint. The first two require sound training in conventional geology and in field methods. The third approach requires a solid foundation of chemistry, physics, and mathematics. Modern training for geologists should include close integrltion of basic sciences with geological principles. Introduction Our knowledge of the earth has increased tremendously during the last half century. We know more about its surface configuration, the distribution of its natural resources, the proccssion of living forms that inhabited it in the past, the chemical composition of its oceans, the areal distribution of its surface rocks, the movements of its atmosphere, and so on. Not only do we know more facts about the earth, but we have a better understanding of the processes that take place on and within it, such as the nature of earthquakes, the thermodynamics of the atmosphere, the chemical equilibria involved in the formation of igneous rocks, the mechanics of stream flow, the dynamics of the earth's origin, and so on. Many sciences contributed to the sum total of this knowledge, including such established disciplines as geology, geography, physics, chemistry, astronomy, biology. Out of this accumulation of new knowledge grew also a group of new sciences, such as seismology, oceanography, meteorology, volcanology, hydrology. Collectively these latter are known as the geophysical and geochemical sciences, and to a large extent they began as branches of geology. Until the turn of the century, for example, the study of earthquakes (seismology) was a part of geology, although as early as 1846 Mallet, a physicist, had suggested that the subject could be investigated by elastic-wave theory. Comparatively little progress was made along these lines until the seismograph was developed near the turn of the century; since then, additional earthquake data have accurnul~ted rapidly, but more important, the interpretation of these data essentially has kept pace with their accumulation. In similar fashion, meteorology was generally considered a branch of geology as recently as one or two decades ago. Considerable progress had been made in such aspects as weather forecasting, but the science dates its recent rapid rise from the year 1911, when Bjerknes first applied the principles of dynamics to the analysis of air masses. The rapid development of such disciplines as oceanography, volcanology and hydrology was due in part to the application of principles of chemical equilibrium, of dynamics, and of thermodynamics to earth problems, by men who were essentially physicists or chemists by training. The last half century, therefore, and particularly the last two decades, saw the influx of numerous chemists and physicists into the realm of the earth sciences. In the meantime the main body of geology itself showed a marked growth, and

Jan 1, 1946

[*E. O'C. Acker '86 Jinzoc Adachl '88 T. H. Aldrich '96 *Truman H. Aldrich '78 Walter H. Aldridge '89 *Anson W. Allen '87 John H. Allen '84 *Thomas Andrews '94 *William R. Analeby '90]

Jan 1, 1946

By S. J. Kidder, G. C. McCartney

THE Helen Mine, of the Algoma Steel Corporation, in the Michipicoten district, Ontario, Canada, has produced more than 6,240,290 tons of iron ore. Prior to and during World War I, 2,823,369 gross tons of brown ore were shipped, and from 1939 to the end of the 1944 season, 3,416,921 gross tons of siderite ore were produced from open-pit operations. Brief descriptions are given of the nature of the ore, the mining methods employed and the manner of treatment of the ore. Shipment of the finished product, known as Algoma sinter, is made to blast furnaces in both Canada and the United States. The iron-ore bodies-i.e., the oxide ores of the Old Helen and the siderite of the New Helen-are a part of a tabular shaped area of iron formation that extends over a length of more than 10,000 ft. and has a maximum width of 1000 ft. The ores are considered to be a product of introduction of iron-bearing material accompanied by replacement of the rocks already present. It is shown that introduction took place subsequent to the development of the major folded structures. It is believed the iron-bearing material emanated from an igneous source.

Jan 1, 1946

By William B. Stephenson

IN the pumping of sands, slurries and slimes, practices developed over the years are the real keystones of successful operation. These practices are necessarily based on modifications of familiar theories. Practical methods used in the solution of problems involving the pumping of materials are set forth in the following discussion. BASIC REQUIREMENTS To pump sands and slurries economically, a few basic requirements must be met by the pumping system as a whole. A pipe-line velocity must be established that will move the fluid mixture throughout the entire system without any possibility of the solids settling out. To accomplish this, the velocity of flow must be slightly in excess of the critical velocity of the mixture. The critical velocity of a mixture varies from 3 ft. per sec. to 18 ft. per sec., depending on the screen analysis, concentration, and specific gravity of the solids in the mixture. Most tailings are pumped at a minimum velocity of 4 ft. per sec. if they include slimes, whereas the pipe lines of sand and gravel dredges require velocities as high as 18 ft. per second. A number of articles have been written on the determination of the minimum velocities required to maintain solids in suspension. Studies have also been made on the friction and pumping heads developed when handling solids in suspension.1-4 Our experience so far has shown that, within the normal operating limits of a pumping system, the friction factor follows more nearly the basis described by Howard,1 who says, among his conclusions: " ... values of ƒ (friction factor) .. . will decrease with an increase in velocity." This conclusion is borne out by our actual experience. When the velocity in a pipe line is not sufficient to keep the solids in suspension, the total friction head is greater than when the velocity is increased to a point where the solids are in suspension. A slight increase in the volume of feed to the pump and a slight increase in the pump speed are usually all that is necessary to put the system in balance. MAINTAINING CONSTANT VOLUME Within reasonable limits, the volume of mixture to be handled through a pipe line should be held constant, so that the required velocity will be provided at all times. There are several ways in which this can be accomplished. The commonest is to provide a sump of sufficient capacity to take care of slight surges in the volume of mixture being fed to the pumping system. This sump, however, should not be as large as a settling chamber. The use of a float-controlled, fresh-water make-up valve in a sump will guarantee a constant volume. Where variations in volume are slight,

Jan 1, 1946

By L. D. Jaffe, M. R. Norton, J. H. Hollomon

IN the practical heat-treatment of steel the decomposition of austenite usually occurs during cooling rather than at constant temperature. Nevertheless, the course of this decomposition has generally been studied only isothermally. Isothermal studies are not only simpler experimentally, but have the great theoretical advantage that one of the variables, temperature, is constant. It is the purpose of this paper to outline the principles that govern the relations between isothermal and anisothermal? decomposition of austenite, to present and systematize the available experimental information, and to indicate the gaps in the existing knowledge. Some of the experimental information is the result of new work. § Most of it is derived from scattered data in the literature. Many of these data were obtained incidentally in the course of research on other subjects and their significance has not been pointed out and perhaps not understood. It is hoped that this paper will aid future planning of more extensive research on anisothermal decomposition. METHOD In order to study the relations between isothermal and anisothermal decomposition, it appears fruitful to view anisothermal decomposition as taking place at a series of constant temperatures1 (except for the martensite reaction, which does not occur isothermally to an appreciable extent). When the time the steel is at each temperature is finite, the over-all amount of the reaction is considered to be the sum of the amounts occurring at each of the successive temperatures. During continuous cooling or heating, the time the steel is at each temperature and the difference between successive temperatures can be considered to approach zero. The over-all amount of transformation will then be given by integration over the range of temperatures involved. This point of view is advantageous in that it considers anisothermal transformation to be a series of isothermal transformations. The problem thus becomes one of determining the effect of partial decomposition at any given temperature upon subsequent decomposition at another temperature. Single Anisothermal Reaction Consider a phase brought to a temperature at which it is unstable, held there until it has partially transformed, and then brought to another temperature at

Jan 1, 1946