Search Documents

By W. J. Schuster

Safety in coal mines depends largely upon adequate training of the foreman. Although management must provide modern and safe equipment and at all times keep mines in first class condition from a safety viewpoint, final results will be determined by the quality of supervision. HANNA COAL CO., Division of Pittsburgh Consolidation Coal Co., operates three large underground mines in eastern Ohio. The section of Pittsburgh No. 8 coal seam in which these mines are located varies in thickness from 52 to 64 in. It is immediately overlain by a stratum of shaly material 12 to 15 in. thick locally known as draw slate, which is structurally very weak and which disintegrates rapidly upon exposure to atmosphere. Immediately above the draw slate as it is normally found is a band of extremely high ash material 6 to 12 in. thick known as roof coal or rooster coal, and above this is a stratum of conglomerate material varying from 4 to 10 ft in depth. Overlying the conglomerate is a relatively thick stratum of limestone, the first stable material above the Pittsburgh coal seam in eastern Ohio. With the method of full-seam mining that has been adopted, draw slate is shot down, loaded with the coal, and removed in the preparation plants. The roof coal then becomes the permanent roof. The major problem in mining the No. 8 seam in eastern Ohio is control of the roof. Since the strata above the draw slate contains no material with a structure firm enough to provide self-support, the roof begins to sag in a relatively short time after the coal and draw slate have been removed. The problem thus becomes one of getting temporary safety posts under this roof as quickly as possible to prevent a break or separation from occurring either in the roof coal or in the conglomerate above it. Haulage System The Pittsburgh No. 8 seam in eastern Ohio is relatively level, with only minor local dips. Throughout the Hanna Coal Co. mines, entries are generally 12 ft wide. Rooms are driven on a 60" angle on 30-ft centers and are 22 ft wide. No attempt is made to extract the 8-ft pillars between. The entire length of main line haulage is gunited in one mine, and a major portion in another. Two of the mines have single-track main haulage roads with passways. The third, a new mine, is double-tracked, and the roof is supported by steel crossbars, 60 lb or heavier, spaced on 4-ft centers and lagged. In recent years timbering on main line and secondary haulage roads has been accomplished by one of two methods: 1—crossbars are supported on a small section of post set in a hitch hole in the rib, or 2—or a hole is drilled in the rib about 12 in. below the roof, of sufficient depth to fasten securely a short length of 40-lb rail, the bottom of the rail facing the roof, on which a short post is set directly under the crossbar. At present the hitch-hole timbering method is favored. At two of the mines the main line haulage locomotives are 26-ton, 8-wheel units. These locomotives are of the axleless type, each wheel being individually mounted on the frame. The motorman's compartment is encircled by 3-in. armor plate for the protection of the occupants. At the third underground mine conventional 15-ton locomotives are being used. However, these locomotives have been completely rebuilt in the company's shops. Equipment has been streamlined and quarters have been provided for two people, who are protected by heavy steel plate in much the same way described above. This modernization program has been completed on all secondary haulage locomotives at the three mines, and the company is well on the way to similar equipment of the 6-ton section locomotives. The following additional features have been included in their modernization: 1—additional support for the motors to prevent their falling to the middle of the track and derailing the locomotives should a break occur in the suspension bar support; 2—installation of additional bracing to prevent brake rigging from becoming displaced and causing derailments; 3—enclosure of all electric wiring in conduit or raceway; 4—provision of an enclosed compartment for the storage of re-railers, jacks, and other equipment, so that they need not be carried on the outside of the motor; and 5—redesign of the end of the locomotive opposite the operator's compartment to prevent anyone's mounting from that direction. It is interesting to note that some

Jan 1, 1955

By D. Harrington

ANNUAL or necessary inspections and investigations of coal mines for various purposes were made possible through the Federal Coal Mine Inspection Act of May 7, 1941, which authorized entry to the Secretary of the Interior through the Bureau of Mines. Primary object of these inspections is to obtain information pertaining to health and safety conditions. Among the purposes for which the data are to be used, are annual reports to Congress, the publication of inspection reports, and the compilation and publication of statistics. The act states that inspections and investigations shall be made by employees of the Bureau of Mines, who shall co-operate with other bureaus of the U. S. Department of the Interior, as well as with the official mine-inspection, safety cr health agencies of the several states and territories. The act specifies that a coal-mine inspector shall have "the basic qualifica-

Jan 1, 1946

By Lawrence K. Jetter, Robert F. Mehl

SOME advances have been made recently in the theory of the kinetics of precipitation from metallic solid solution despite the complexities of the problem, but there is surprisingly little quantitative information available on rates of precipitation with which to test present theory or upon which to build new theory.? Attempts to measure rates of precipitation have been beset with difficulties which originate both in the anomalies that attend the changes in the properties selected for measurement, as, for example, in electrical conductivity or mechanical properties, and also in the complexities in the structural changes in some systems, as in the aluminum-copper system. If the functional relationship between the quantity of precipitate and the value of the selected property is uncertain, measurements of that property are obviously of uncertain utility in determining absolute rates of precipitation. If the precipitating system passes through one or more transition stages, the interpretation of measured rates lacks definiteness; in such cases, it is necessary to measure the rate of reaction in each separate stage, if the rate measurements are to have any significance from the kinetic point of view.* These difficulties cannot be wholly avoided, for at least in some measure they are characteristic of the process of precipitation from solid solution, but they can be minimized both by the selection of a simple system and by the use of a method of measurement relatively free from anomalous behavior. The present paper reports dilatometric measurements on the rate of precipitation of silicon from the aluminum-rich solid solution in the aluminum-silicon system-a study that approaches the desiderata of simplicity. The aluminum-silicon system offers advantages from these points of view: there are no known anomalies in the property changes accompanying precipitation ;2,3,4 there are no known transition stages; the precipitate is an element, not a compound, and both matrix and precipitate are cubic, and while the structures are not identical (the solid solution is face-centered cubic and the precipitate is diamond cubic), the system at least approaches the ideal case of a crystal precipitating from a matrix of the same crystal type-the ideal case which Becker5 assumed in treating the precipitation process theoretically. The dilatometric method, while not free from disturbing effects, as the subsequent dis-

Jan 1, 1942

By Harry L. Washburn, Robert L. Llewellyn, W. J. Halvorsen

Many of the problems that occur in the preparation plant originate from practices in the mine. Impurities in raw coal can be in the seam itself or from extraneous material taken in mining from the roof or bottom. In the case of underground mines, the choice of mining equipment will affect the size consist and the amount of extraneous material included with the coal. Also, governmental regulations concerning the degree of rock dusting, gobbing underground, and cleanup have increased the dirt in raw coal. Sulfur dioxide emission standards, on the other hand, are pressuring the coal industry to clean coal more thoroughly. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent (Fig. 1) and only incidentally with mines shipping raw run-of-mine coal crushed to a top size of, usually, 51 to 102 mm (2 to 4 in.), with little, if any, other treatment. JUSTIFICATION FOR COAL PREPARATION During the past decade, major changes have occurred affecting the market, profit, and long-range planning of the coal industry. Mining companies have become "partners" with consumers at many new and some old mines, both for steam and metallurgical coals. Coal properties have become "assigned" tonnages at mutually agreed upon conditions and prices. Lower unit-train tariffs have been instrumental in helping coal markets to compete against oil and nuclear energy. Coal prices for power plants are still on a Btu (British thermal unit)

Jan 1, 1981

By K. E. Gray

The status of rock mechanics as applied to petroleum production might be termed, "Rock Mechanics-A New Name for Old Problems." The petroleum industry's efforts, from its earliest days, have been concerned with rocks, hopefully containing hydrocarbon accumulations in economic quantities. Geophysical and geological studies, wildcat and development drilling procedures, well bore mechanics and reservoir engineering operations, and certain aspects of production operations involve rock mechanics in various ways. Stress states and temperatures of interest range from low values in surface or near-surface activities, to very high values encountered at depths now exceeding 25,000 ft; deeper and deeper drilling will continue to increase this range. Time scales vary from a few microseconds in wave propagation measurements and some aspects of rock behavior during drilling, to seconds, minutes or hours for other drilling and well bore mechanics problems, to several years during which the efficient and economical depletion of reservoir systems is achieved. Subsurface sedimentary formations contain various fluids, of course, and reservoir fluid movement commonly involves three-dimensional, three-phase (oil, gas, and water) fluid flow. Many extremely difficult problems in rock mechanics arise for the Petroleum Engineer because of fluid movement (or lack of desired movement) in a well bore or reservoir. The discussion to follow illustrates just a few of the many topics in rock mechanics of significance to the petroleum industry. Time precludes anything other than a superficial treatment of the topics mentioned. A great deal of work has been carried out by various research groups in the petroleum field and significant efforts are continuing, as a review of the technical literature will reveal.

Jan 1, 1968

By J. M. Ross

THE Homestake mine is situated in Whitewood mining district, in the northern Black Hills of South Dakota, in the city of Lead, Lawrence County. The entire property, comprising 557 lode claims with a total area of 3343 acres, is held under United States Patent. The older claims were 300 by 1500 ft. under local regulations, the newer ones 600 by 1500 ft. The Homestake was discovered April 9, 1876, by Moses and Fred Manuel, and Jake Harney, who were drawn into the northern hills, from the Custer placer district, by news of the discovery of rich placer deposits in Deadwood Gulch. They located a number of additional lode claims and, in a short time, the whole country was covered with locations. The Manuel brothers built an arrastre the following winter and took out $5000. The next year the Homestake lode was sold to Senator George Hearst and associates, who organized the Homestake Mining Co. Other companies were formed to exploit other groups of claims and at one time five companies were operating on this deposit, the Father DeSmet, the Deadwood-Terra, the Caledonia, the Highland, and. the Homestake Mining Co. These companies, however, have been merged into the Homestake Mining Company. The first stamp mill, known as the "Eighty Mill," commenced operation on July, 12, 1878, and production has been nearly continuous since that time.

Jan 2, 1925

By WILLIAM BOWIE

IN most human endeavors a knowledge of the terrain is essential to the effective carrying out of projects, but no line of work is more dependent on maps than theoretical and applied geology. Maps of a kind do exist for all of the area of the United States, but most of them are crude affairs and of little use in engineering, planning, and scientific research. Topographic mapping in the United States was initiated on a national scale by the U. S. Geological Survey and the organizations that were merged in its creation to make base maps for geologists. Their work could not be effectively done then and cannot be effectively done now without maps that accurately delineate the earth's surface. The distribution of the rock masses that contain valuable mineral bodies, or that by their intrusion brought them into existence, is the first step in a study of the mineral resources of the nation. This work requires three-dimensional maps, that is, topographic maps on which the land forms are shown by contours.

Jan 1, 1938

By W. E. D. Jr. Stokes

THE application of aviation to mining and petroleum operations, on the basis of economy and attainment, has become a demonstrated fact. According to Dominion Government records, 30. Canadian companies engaged in air transportation with northland mining camps, carried 13,000 tons of freight in 1935, and in 1936 carried 16,000 tons. In addition, many mining companies used planes to transport prospectors with canoes, outboard motors, gasoline drums and supplies to remote locations, and one company maintained a plane to take radium-bearing ore from its mine on Great Bear Lake nearly 1000 miles south to the rail-way at Waterways, Alberta. Heavy pieces of mining machinery weighing 2 tons are being carried by Ford trimotor planes over the Andes, at an altitude of not less than 15,000 feet. At Bulolo, New Guinea, 17,500 tons of disassembled gold-dredging equipment has been flown over inaccessible terrain, while supplies and building materials for a, community of 1000 whites have been transported by airplane. A 31..4-ton shaft was carried on one notable trip, while at another time an automobile, 2 tons of rice and a large safe went over the mountains in one plane. Fig. 1 shows an electric generator that was carried by plane to Bulolo. Many large American oil companies operated fleets of planes during 19:36, ranging from fast, luxurious air liners for executives to elaborate geological prospecting units, ambulance planes, freight carriers and pipe-line repair crews. According to the U. S. Geological Survey, commercial firms photo-graphed 16,291 square miles during 1935, while the Government compiled from aerial photographs by the Geological Survey in the United States 85,544 square miles. It was found that information could be determined in a fraction of the time required by surface methods.

Jan 1, 1937

By Alan M. Bateman

Before World War II we proudly considered that we were the nation of all the world most richly endowed in mineral resources. We knew it was no accident that those countries abundantly supplied with mineral resources became the great manufacturing nations, and the politically and militarily strong ones; and that our own great industrial cities sprang up where coal and iron met. We all reallized, especially we of the mining profession, that the energy of fuels and the solidity of metals spelled industrial growth and in turn industrial might and that other nations came to regard mineral self-sufficiency as one of the chief goalsof economic nationalism.

Jan 1, 1949

By Robert L. Llewellyn

Preparation of coal begins at the face in underground mines or in the pit with surface mines. Impurities in raw coal can be in the seam itself or in extraneous material taken in mining from the roof or bottom. Raw coal is prepared only to the extent that is necessary to make the product salable. Over 60% of all coal production is processed to some extent in cleaning plants. For underground mines the proportion cleaned is 72% as compared to 42% from surface and 15% from auger mines. Coal supplied for coking purposes is nearly all upgraded by washing, while for the largest market, electric power generation, a high proportion is shipped as a raw product with processing, in whole or in part, only as necessary when excess impurities are mined with the coal. This chapter will deal primarily with plants that process or wash coal to some extent and only incidently with mines shipping raw run-of-mine coal crushed to a top size of, usually, 2 to 4 in., with little, if any, other treatment. ECONOMICS OF COAL PREPARATION During the past decade, major changes have occurred affecting the market, profit, and long-rang planning of the coal industry. Mining companies have become "partners" with consumers at many new and some old mines, both for steam and metallurgical coals. Coal properties have become "assigned" tonnages at mutually agreed upon conditions and prices. Lower unit-train tariffs have been instrumental in helping coal markets to compete against oil and atomic energy. Cod prices for power plants are still on a Btu (British thermal unit) basis but with more emphasis on sulfur content. For metallurgical coal, the lower and medium volatile coals are in demand and the price rises, generally, as the volatile percentage is lower. Moisture affects the Btu value of coal almost the same as ash content, but dusty conditions during loading and unloading are no longer accept-

Jan 1, 1973

By AIME AIME

A REQUEST for information as to the details of activities of the Engineering Council was made by the Joint Conference Committee for the benefit of the new American Engineering Council. , This request was complied with, and the scheduled reply so succinctly sets forth the activities of the old Council as well as the scope of possible activities of ,the new Council, about whose efforts there has been much discussion, .that it' is given herewith in full, except the 'budget which is summarized.

Jan 1, 1920

By Hans Lundberg

N OT so long ago, the discovery of an orebody took place only by accident. At the present time mineral deposits, even though concealed, may be revealed by their physical or geophysical characteristics, considered in connection with geological studies. Geophysical methods are based on sound, scientific principles and in no sense partake of the mysteries of "divining-rod " methods. Geophysical methods are divided into two main groups: Group I: Methods where fields of force surrounding mineral deposits are investigated (magnetic, gravitometric, electric) ; Group I1 : Methods where fields of force are applied (produced) and anomalies caused in these fields by mineral deposits are recorded (electric, seismic). By methods belonging to Group I, the investigation of the fields of force may be brought to an astonishing degree of accuracy by means of highly sensitive and delicate apparatus (torsion and magnetic balances) ; at least, in simple cases these methods have proved to be of great value.

Jan 1, 1925

By AIME AIME

QUALITY and size do not ordinarily go hand in hand, but there is good evidence that both these attributes reached a new peak at the Annual Meeting of the Institute in New York just concluded. Certainly, the total attendance of 2500 was far above any yet attained, as might be expected with the recent rapid growth of Institute member- ship. General comment indicates that the quality of the papers also was notable, though not measurable by so definite a yardstick as attendance. During the meeting 49 technical sessions were held, at which more than 250 formal papers were presented. In addition, there were some thirty special meetings of committees, Divisions, and other Institute groups. In reporting the Annual Meeting eleven years ago the statement was made that "unless the Engineering Societies should build for themselves a new building it is probable that no meeting can be larger," and "the fifth floor, where a buffet lunch is served each day, has reached its full capacity and it seems quite evident that any future development of Institute meetings must be along the lines of quality, not size." Unfortunately the angel to succeed Andrew Carnegie, who financed the building of the present home of the Institute 35 years ago, has not yet ' appeared. Even if some one would merely build another elevator or two in the present building it would help. Fortunately, the modern auditorium of the American Radiator & Standard

Jan 1, 1940

By W. S. Row

This mine is operated at 4000 to 4500 tons daily through a single shaft, with one rock hoist and one senice hoist. Latest shaft construction is concrete with wooden dividers. Economics of drifters and air-leg drills are compared, as well as costs of shrinkage and sub-level stoping. Economy of large haulage equipment and underground crushing is shown. THE property of Kerr-Addison Gold Mines is located in the Larder Lake district of Ontario about 3 miles from the Quebec boundary on the highway between Kirkland Lake and Noranda. It is roughly 320 miles due north of Toronto and 365 miles north of Buffalo, N. Y. The property was staked in 1906 and after several development efforts finally came into continuous production at 500 tons per day in 1937. In 1939 the daily tonnage -was increased to 1200 and in 1941 to 2100 tons. At the end of the war, because of the shortage of labor, tonnage was down to 1100 tons per day, rising to 2200 in February 1947. A further plant expansion inaugurated in 1946 was completed by December 1948, bringing the capacity of the mine and mill to a production rate of 4000 tons per day. Current production, with 880 men employed, is 4400 tons per day. Changes in mining methods and equipment, required by the recently completed expansion program, have yielded interesting comparative results, some of which are described in this paper. Hoisting of ore and waste from the mine, as well as all service facilities for handling men and supplies underground, are provided for in a single vertical five-compartment shaft. Ore and waste are hoisted in 12½-ton skips in balance by a 14-ft diam hoist with drums 115 in. wide, grooved for 2?-in. wire ropes. This hoist, with a total rope pull of 85,000 lb, was designed to operate at a speed of 2600 ft per min to a depth of 4000 ft, hoisting 15 tons of ore in each skip. It is amplidyne-controlled and powered with dual drive dc motors of 2250-hp each, through flexible couplings to two pinion shafts, one on each side of the main gear. Each motor has a peak load rating of 4500-hp at point of greatest duty. Direct current power to the hoist motors is supplied from a motor generator set consisting of a 5000-hp synchronous motor driving two 1750-kw dc generators. The loading pockets used so far are at depths of 1500 and 2725 ft respectively. Consequently the present hoisting speed is 2000 ft per min and the skips capacity only 12½ tons. Now that the shaft has been deepened the new pockets at 3934 ft will be increasingly used so that the speed and the skip size will be increased up to original specifications as required. Some difficulty in meeting the required hoisting cycle is expected because of the shape of the skips. As now in use the cross-sectional dimensions of the inside of the skip are 4 ft 6 in. x 3 ft 8 in. To hold 121/2 tons, therefore, they are 14 ft 10 in. deep. Since the skips are the conventional overturning or Kim-berley type, considerable hoisting time is lost in retardation in entering the headframe dump and in acceleration when leaving. It is expected that to obtain the specified tonnage from this hoist when the skip size is increased to 15 tons it may be necessary to resort to bottom dump skips. This type of skip could reduce considerably the present excessive acceleration and retardation times. Analyses of the skip-hoisting operation are made monthly, and every effort is made to reduce controllable delays. For a nine-month period in 1951 such an analysis shows that the hoist was in operation 92.5 pct of the available time, which was allotted as shown in Table I. Overall hoisting costs, cage and skip, for the year 1951, averaged $0.168 per ton of ore milled. The mine is serviced entirely by means of a single cage, capacity 35 men or 15,700 lb, operating in con-

Jan 1, 1954

By M. B. Hopkins

FOR years the expression "except rubber, tin, and manganese" has appeared in practically every discussion of the natural resources of the United States. Knowledge that natural rubber is not produced in the United States has now spread from the relatively few who have reason to be interested in the country's basic raw material supplies to all those who ride in automobiles, which means everybody. This "everybody" reads in the daily papers that we have a stock pile of natural rubber and that plenty of synthetic rubber is just around the corner. Statistics as to the United States' rubber requirements and sources of supply are of interest to him only to arrive at an answer to the question : "After taking care of rubber requirements for military purposes, will there be rubber for my automobile and the many other rubber articles I want?" More than 30,000 different rubber articles are manufactured in addition to the tires and tubes which use up about 70 per cent of the rubber supply.

Jan 1, 1942

By T. A. Rickard

The function of a preposition is to show the relation of one thing to another; it is necessary therefore for the writer to select the preposition that indicates the particular relation, otherwise he will fail to express himself clearly. Is it against common sense' to suggest that a Government is justified, morally as well as constitutionally, in preventing the decay of an industry by insisting upon the amalgamation of the prosperous with the needy? All these seven prepositions are used correctly. With the first dredge introduced in Russia, of Werf Conrad, Haarlem, make, this method of alluvial dining became important. Here the prepositions "with", "in", and "of" are used wrongly. He means: "This method of a1lu;ial mining sprang into importance shortly after the first dredge, made at the Werf Conrad, Haarlem, was introduced into ;Russia." The statement itself ii not true, but for that I am not responsible. Once, while I was serving with him, we were frozen in out of sight of land in the Gulf of Pichili in the North of China. Admiral Fisher wrote thus. He has used nine prepositions in making this brief statement. The sequence of three prepositions "in out of" is particularly awkward.

Jan 1, 1931

By Stirling Huntley, L. G. Huntley

THE controversy regarding the ,'probable future of the Mexican oil fields, and its relation to the oil industry of the United States, has led to the preparation of this paper. As has been predicted by several writers in recent papers, certain of the producing areas in the so-called "southern fields" in the Tampico Embayment have only a limited oil reserve. These areas are being pulled on by every pipe line in that region, and the length of time that they will continue to produce is a direct factor of the daily oil shipments of these companies. However, this is not the whole story, and in the following paragraphs an attempt will be made to show that the life of Mexican oil production will be a long one, and Mexican oil will continue to be a large factor n the market for an indefinite time after the areas mentioned above have been drained. The past and present producing fields will be discussed separately, in order-to establish a basis for comparison, the ,only method by which underground reserves 'can be estimated in these fields.

Jan 1, 1921

By J. H. East, E. R. Maize

Probably no other type of equipment is now being introduced into American underground mines about which less is known and about which there is more misinformation than the Diesel mine locomotive. Any equipment installed underground brings with it hazards that were not present before, and it is the purpose of this paper to show that Diesel-powered equipment can be used with safety in underground mining if certain feasible but very important precautions are taken. Diesel locomotives are not new in underground mining, since they have been used successfully in European mines for at least 19 years, but their use in American mines is exceedingly limited; so far as is known, only five Diesel mine locomotives are operating at present in United States mines. Diesel locomotives were permitted underground in Great Britain for the first time in 1939, and the rapid increase in the number in use in those mines testifies to their safety and efficiency. More than 1300 Diesel mine locomotives are in use in European mines, according to the latest statistics; these locomotives are employed in coal, iron, lead-zinc and mercury mines. SO far as is known, the Diesel mine locomotive has not yet caused an explosion or mine fire, and has not been the cause of any fatalities from toxic gases in the mines in which it has been used. Adjustments of Diesel Engines foR Underground Use A Diesel engine adjusted to work in an underground mine should not be confused with the same engine adjusted for use outside the mine. Adjustment of the air:fuel ratio for engines that are used on the surface is intended to give the maximum fuel economy, and little or no attention is given to the chemical composition of the exhaust gas produced. Many such engines are poorly adjusted and perhaps poorly maintained, with the result that the engine emits smoke in quantity as well as the disagreeable odor familiarly associated with Diesel engines. The air:fuel ratio in the case of Diesel engines operated on the surface is generally around 15:1; that is, 15 lb of air to burn I lb of fuel. Diesel engines adjusted to work underground usually have an air:fuel ratio of about 20:1, as at this ratio the minimum quantity of toxic gases is given off in the engine exhaust. Diesel engines operated underground must be maintained in better condition than similar engines used on the surface; otherwise, the smoke emitted in the exhaust becomes objectionable if not unendurable. Practically normal air is required for safe operation of Diesel engines underground or in confined places; failure to provide virtually normal air for Diesel engine operation is almost certain to result in trouble. Bureau of Mines engineers have determined that the air in which a Dicsel Operates hi confined places should contain less than % pct of carbon dioxide and at least 20 pct of

Jan 1, 1949

By A. G. Metcalfe

Observations at temperature are used to investigate the phase changes in alloys containing more than 50 pct Co and above 1000°C. The nonsuppressible transformations in cobalt above 1120°C and in the intermetallic compound Co2Cr3 are studied. The liquidus and solidus surfaces are determined. Insufficient data is obtained to complete the constitution diagram. A REVIEW of some of the earlier work on cobalt' and on the binary systems with chromium2-4 and with molybdenum,5 showed that one likely source of differences might be attributed to the presence of phases at high temperatures which could not be retained by quenching. Consequently, the decision was made that only methods of examination at temperature should be used in this work. The correctness of this decision was confirmed during the course of the work by the investigation of the martensitic nature of the transformation in cobalt- and by the decomposition of the high temperature form of the phase Co2Cr3 on quenching.' The use of high temperature methods, including dilatometry and thermal etching led to the postula-tion of the existence of a high temperature form of cobalt with a probable hexagonal close-packed structure, transforming from cubic cobalt over a range of temperature from 1119° to 1145°C.8 One of the important pieces of evidence for this transformation was that it was observed in alloys with chromium and molybdenum which were nonmagnetic at this temperature so that confusion with magnetostriction effects was impossible. These results were not reported in this earlier paper, so that the data given here supply further evidence for the existence of a second allotropic transformation in cobalt. High temperature observations are necessarily much slower in producing results than the examination of quenched specimens at room temperature by conventional means such as X-ray diffraction or microexamination. The investigation has only covered a limited part of the field, as a result, extending from the liquidus down to about 1050°C and from the cobalt corner up to 50 pct alloying elements. The differences between the various reported diagrams for the constitution of the Co-Mo and Co-Cr systems have already been mentioned. The best available diagram in the first system is due to Sykes and Graff' which is shown in Fig. 1. Fig. 2 shows the latest Co-Cr diagram due to Elsea, Westerman, and Manning.' A comparison reveals that these are incompatible because of the disagreement with regard to the number of allotropes of cobalt. Elsea, Westerman and Manning took their liquidus and solidus curves from Wever and Haschimoto.2 The temperature horizontal in the two-phase field beneath the eutectic was placed 35" to 39°C higher than in earlier work2,4 with a new interpretation of the nature of this transformation. This interpretation also required a peritectic horizontal at about 1470°C, which has been confirmed here for an alloy with 53 pct Cr. No investigation had been made of the ternary system until after this work had been terminated, when a section at 1200°C was published." In this work a ternary compound was found by the X-ray diffraction examination of quenched alloys. This compound contained less than 50 pct Co, and was thus outside the field investigated here. However, some reactions were found dilatometrically which could not be fitted on the diagram and are now believed

Jan 1, 1954

By J. C. HEILMAN

THE Tri-State district, named from its situation in three States, lies in the northeast corner of Oklahoma, the southeast corner of Kansas and the adjacent part of Missouri east of the common corner of the above States. Production in the past eighty years has come from scattered mines within an area of some 35 miles east and west, by 25 miles north and south, although the actual area of the mined ground is but a small fraction of this territory. The land is leased from the individual land-owners, and the size of the tracts varies from 4.0 to 200 acres, the smaller sized tracts predominating. The leases usually call for a royalty of 7% to 15 per cent of the gross receipts of the concentrates, continuous operation during the life of the lease and specifically set out that no ores can be brought in from a foreign lease for custom milling nor can any ore be removed from the lease for milling. The ownership of the tailings remains with the land-owner.

Jan 1, 1931