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By E. N. Smith, J. C. Redmond

The increasing need for materials capable of withstanding higher operating temperatures for various applications such as gas turbine blading and other parts, rocket nozzles, and many industrial applications, has brought consideration of cemented carbide compositions. The well known usefulness of cemented carbides as tool materials is attributable to their ability to retain their strength and hardness at much higher temperatures than even complex alloys. However, it has been found that the temperatures encountered in cutting operations do not approach by several hundred degrees1 those involved in the applications mentioned above where the interest is in materials possessing strength and resistance to oxidation at temperatures of 1800°F and above. At these latter temperatures, the tool type compositions which are made up essentially of tungsten carbide are found to oxidize very rapidly and to produce oxidation products of a character which offer no protection to the remaining body. As a further consideration, the density of the tungsten carbide type compositions is high, from about 8.0 to 15.0. The refractory metal carbides as a class are the highest melting materials known as shown by Table 1 which summarizes the available data from the literature for the carbides of the elements which are sufficiently available for consideration for these uses. The density is also included in the table, since as mentioned above it is an important consideration in many of the applications for which the materials would be considered. It has been established that in the tool compositions the mechanism of sintering with cobalt is such as to result in a continuous carbide skeleton and that the properties of the sintered composition are thus essen- tially those of the carbide.2 On the hypothesis that this mechanism holds to a greater or less degree in cementing most of the refractory metal carbides with an auxiliary metal, it appears from Table 1 that titanium carbide compositions would offer possibilities for a high temperature material. Titanium carbide has extensive use for supplementing the properties of tungsten carbide in tool compositions. Although the literature contains several references to compositions containing only titanium carbide with an auxiliary metal,3,4,5,6 it may be inferred from the meager data that such compositions were deficient in strength and were considered to have poor oxidation resistance.7 Kieffer, for instance, reports the transverse rupture strength of a hot pressed TiC composition at 100,000 psi as compared to up to 350,000 psi for WC compositions. The work described herein was undertaken to determine the properties of compositions consisting of titanium carbide and an auxiliary metal and to improve the oxidation resistance of such compositions. It appeared possible that the inclusion of one or more other carbides with titanium carbide might improve the oxidation resistance and also that this might be more desirable than other means from the point of view of maintaining the highest possible softening point. Consideration of the available carbides in Table 1 suggests tantalum and columbium carbides because of their high melting points and general refractoriness. The work on improving oxidation resistance was concentrated on the addition of tantalum carbide or mixtures of tantalum and columbium carbide. The auxiliary metals used included cobalt, nickel and iron. It was also desired to learn the general physical properties of these compositions. Experimental Procedure The compositions used in this study were made by the usual powder metallurgy procedure applicable to cemented tungsten carbide compositions. The powdered carbide or carbides and auxiliary metal were milled together out of contact with air. In some cases cemented tungsten carbide balls and in other instances steel balls were used to eliminate any effect of tungsten carbide contamination. A temporary binder, paraffin, was then included in the mix and slugs or ingots were pressed with care to obtain as uniform pressing as possible. The ingots were presintered and the various shapes of test specimens were formed by machining, making the proper allowance for shrinkage during sintering. Thereafter the shapes were sintered in vacuum at temperatures of from 2800 to 3500°F. Final grinding to size was carried out by diamond wheels under coolant. The titanium carbide used contained a minimum of 19.50 pet total carbon and a total of 0.50 pet metallic impurities as indicated by chemical and spectrographic analysis. It was found by X ray diffraction examination with

Jan 1, 1950

By James Ruddy

THE medical program of the Climax Molybdenum Co. is under the supervision of the department of industrial medicine of the University of Colorado, of which James J. Waring, professor of medicine at the University Medical School, is director. Dr. Waring is consultant and direct supervisor of both the hospital and industrial medical department at Climax. At Climax the program is in charge of the medical director and the associate physician, Dr. Galen M. Hover. The hospital at Climax is completely equipped with all that is necessary for the practice of scientific medicine and surgery. Only graduate registered nurses with experience in industrial medicine are employed. Being only a few hundred yards from the portal of the mine. acci-

Jan 1, 1946

By C. S. Witherell

THE first feature that strikes one when considering the use of air enriched with oxygen in pyrochemical processes is the conservation of Enriched Air FIG. 1.-TEMPERATURES THEORETICALLY OBTAINABLE BY BURNING PURE AMOR¬PHOUS CARBON IN AN ATMOSPHERE COMPOSED OF AIR ENRICHED WITH OXYGEN, PRODUCING GAS CONTAINING CO. heat due to the partial elimination of the inert heat-carrier nitrogen, as set forth in the report of the committee. The second feature, which

Jan 11, 1924

By Walter Nummela

This acronym may be readily deciphered, and it represents the programming theme for the SME Sessions at the Centennial Meeting of AIME in New York in 1971. The Concentration Committee thus charged out to grab, to induce, and to accept volunteered papers within that framework. The program for the Concentration sessions is in and hopefully all deadlines will be met as specified in the instructions to authors. Without spelling out what is to be seen and heard in New York, how well did the Committee satisfy the theme described in the title? Perhaps it was by virtue of the international makeup of the Committee (Member Dan Pickett is with the Mines Branch in Ottawa) that an international slate of authors was assured. Four countries are to be represented-Bolivia, Canada, Italy, and the United States.

Jan 1, 1970

By W. R. Wardner

During 1928 low prices in the East greatly restricted the Atlantic market for California petroleum. The situation was made difficult by only partial control of production. The month of December is estimated in the figures presented here and it is hoped that the differences in the final figures will be immaterial. Daily averages are used throughout. Production Daily average crude production for 1928 was 633,942 bbl., very little more than 1927. Natural gasoline production was 35,453 bbl. daily and the supply (crude and natural gasoline) was 669,395 bbl. However, potential supply was 785,621 bbl. daily, 47,436 more than that of 1927. This is accounted for by more production being shut in so that 116,000 bbl. daily was conserved in 1928 which would otherwise have been produced. Fig. 1 shows production by months for 1928. It will be noticed that while crude production held fairly uniform from January to October, the

Jan 1, 1929

The following resolution was prepared, by the War Minerals Committee and was submitted by it to the Board of Directors of the American Institute of Mining Engineers, asking that it be passed by the Board and used to the best advantage to secure the end desired. WHEREAS, the steel industry of the United States is almost entirely dependent on the importation of foreign manganese ores, the consumption of which for the year 1918, it is estimated, will exceed 850,000 tons; and WHEREAS, the ships now engaged in transportation, especially from Brazil, are needed with ever increasing urgency for supplying our Army and Navy forces abroad; and WHEREAS, much shipping may be spared from manganese transportation and the domestic sources of manganese may be utilized, provided the steel manufacturers of the United States will cooperate to this end by taking advantage of the possibility, in open-hearth and Bessemer practice, of so called "residual" manganese, and by using spiegeleisen instead of ferromanganese, thereby following the example already set by three large and prominent steel producers; BE IT RESOLVED, that the Board of Directors of the American Institute of Mining Engineers urges the steel manufacturers of America, for patriotic reasons, to give immediate consideration to the development and utilization of domestic manganese ores; to use no ferromanganese, except for the manufacture of grades of steel below 0.15 per cent. carbon, to use domestic ores whenever possible in place of the high-grade imported ores; and to urge their associates and colleagues in this and other possible ways, to vie with one another in releasing ships for importation of any materials that cannot be secured or produced in this country.

Jan 1, 1918

By C. Y. Ang, C. Wert

Quench aging of supersaturated solid solutions of nitrogen in columbium takes place in reasonable times in the temperature range 300&apos; to 500°C. Changes in internal friction, hardness, and electrical resistivity are found to accompany this change. THERE is practically no detailed information in the literature concerning interstitial solid solutions in either columbium or tantalum. The fact that both of these metals are used extensively commercially in both pure and alloyed states makes studies of their properties of value. While the plan is to study both these metals and their alloys extensively, so far only a small number of measurements have been made. This paper presents data obtained in the initial investigations of columbium. The principal interstitial impurities of columbium are likely to be hydrogen, carbon, oxygen, and nitrogen. The first of these, hydrogen, is outside the scope of internal friction measurements at present and nothing quantitative is known about the initial hydrogen content of the specimens. However, it is believed that it is completely absent after the preliminary heat treatments are carried out. The carbon content of the original samples is low and can be reduced still further during sample preparation. Oxygen is normally present to some extent in columbium and can also be added or removed easily. Nitrogen is also normally present in small amounts and can also be controlled within limits. Since it is not possible yet to remove all the nitrogen from columbium and since it is possible to remove essentially all the oxygen and carbon, initial measurements were made on the alloy system nitrogen in columbium. In this sense then, the alloys are true binary alloys. Little is known about the effects of nitrogen on the physical and metallurgical properties of columbium, so it was necessary to perform some rather elementary measurements on the specimens. These measurements are described briefly in the next section and are discussed in detail in later sections. Scope of the Work That internal friction is associated with diffusion of nitrogen in columbium has been known for some time. It is similar in nature to that for carbon and nitrogen in a-iron. In these latter cases, the information obtained from internal friction has been useful metallurgically.&apos; and it is not too much to expect useful information from similar studies on columbium containing nitrogen. The technique of internal friction measurements is adequately described by Ke2 At a frequency of 1 cps the internal friction peak for nitrogen in columbium occurs at 300°C and that for oxygen at 160°C." So that all the measurements will be meaningful metallurgically, the internal friction has been calibrated by making a measurement of the damping at the two peaks and a measurement of oxygen and nitrogen content by chemical analysis. A comparison of the two gives the following calibration factor: To go from damping capacity expressed in terms of 1/Q to weight percent of oxygen and nitrogen in solid solution in columbium, multiply the peak values of internal friction by about 4 and 3 respectively." Data from which these factors were calculated are presented in Table I. The increase of electrical resistance of columbium caused by the addition of oxygen and nitrogen as interstitial impurities has been quantitatively determined. At room temperature the percentage increase is small for small additions of impurities (<0.1 wt pct); as the temperature is lowered it becomes an increasingly larger factor of the total resistance. An empirical relation has been established to express the resistivity at — 195°C in terms of weight percent of oxygen and nitrogen in solid solution. It is easy to make supersaturated solid solutions of nitrogen in columbium and to observe aging phenomena. The optimum aging temperature, as in the case for carbon and nitrogen in a-iron, occurs at the temperature for which the time necessary for a single place-change in diffusion is about 1 to 10 millisec. This means for nitrogen in columbium that significant property changes should take place for this alloy at about 400" to 500°C in reasonable time intervals. Results of such aging experiments are

Jan 1, 1954

By AIME AIME

MOST of us are far .from home, and yet our Japanese hosts- have made us feel very much at home. Here in the Orient we engineers are .learning a new meaning for the word "orientation"- hereafter that engineering term will be a synonym for gracious hospitality, and "to orient" will mean to turn a whole country over to the World Engineering Congress. Mere geographic distance is no longer able to separate nations, for the conquest of distance is one of the triumphs of &apos;modern engineering. We of the Americas are fortunate in the position of our continents: with their shores lapped by the waves of two oceans, we face&apos; two great civilizations, the&apos; Occidental and the Oriental, and thus we can share the intellectual resources of these two older cultures.

Jan 1, 1929

By Arthur Taggart

IN 1900, Elmore found that if an acidulated pulp was stirred up with an oil which was relatively insoluble in and lighter than water, and the mixture was al-lowed to stratify, much of the sulfide would be found hanging to the lower surface of the floating body of oil and could be skimmed off or overflowed with it. The action of the flotation agent here is two-fold, first to select the sulfide from the gangue-what to-day is called collection-and second, to buoy the col-lected sulfide away from the gangue. The action in collecting is illustrated by Fig. 1, which contrasts the behavior of drops of oil brought, under water, to the surfaces of gangue and sulfide particles, respectively. The oil displaces water from the surface of the sulfide; the water displaces oil from the gangue surface. If, instead of considering the solid particles the fixed parts of the system of oil, water and solids, we consider the oil and water fixed and the solids pre-sented to the surface of contact, the condition will be as shown in Fig. 2 ; the sulfide tends to be drawn into the interface and the gangue to be excluded. The sul-fide particles are held in the oil-water surface by the tension of this surface. The buoyant effect is supplied by the oil droplets in bringing the sulfides to the water surface, but not in holding them there.

Jan 6, 1928

By Y. S. Bonillas

IRA B. JORALEMON, Warren, Ariz.-This paper has covered the situation so well that I have few suggestions to offer. Two points, however, are shown more clearly in the lower mines of the Calumet Arizona Mining Co. than in Copper Queen workings, and may be worth mentioning. The first is the usual association of high-grade primary sulphide orebodies with much larger masses of pyrite and silica, averaging less than 1 per cent. copper. The richer areas occur sometimes around the borders of the lean pyrite bodies, and sometimes entirely within them. While as yet we have not been able to find any certain reason for the location of high-grade sulphides in low-grade masses, it seems likely that the age of fracturing is one controlling feature. The first stage of mineralization, with pyrite and silica, had the effect of sealing up the rock. The later solutions, richer in copper, could pene-

Jan 12, 1916

By John C. Shyne, Eric R. Morgan

BORON as a hardenability agent of commercial importance has been the subject of extensive study in recent years. It has been suggested in the past that boron increases hardenability by combining with nitrogen, thus rendering it innocuous.&apos; More recently it has been proposed that boron increases hardenability by reducing the free energy of sites of ferrite and pearlite nucleation.&apos; The segregation of boron to grain boundaries, the primary site of nucleation, would account for the large hardenability effect of minute additions of boron in steel. This grain boundary theory has found general acceptance while the concept of boron as a nitrogen scavenger has been disregarded. However, the interaction of boron and nitrogen in steel is considered to be important to hardenability because boron may be made ineffective by combination with nitrogen.". * The present work was undertaken to examine some of the effects of boron and nitrogen arid their interaction in steel. A base composition of moderate hardenability was chosen. This was a 0.35 pct C steel containing 2.50 pct Ni and 0.30 Mo. This composition was used because it contained no strong carbide, nitride, or Table I. Composition of Steels by Analysis, Wt Pct Steel C Ni Mo 0&apos; B N* Base 0.35 2.50 0.30 0.0012 nil <0.0001 Boron 0.35 2.50 0.32 0.0012 0.0022 <0.0001 Nitrogen 0.33 2.60 0.35 0.0015 nll 0.0052 Boron plus nitrogen 0.35 2.48 0.30 0.0006 0.0020 0.0040 * Obtained by vacuum fusion technique. boride-forming elements. The other alloys examined were modifications of the base composition and contained nitrogen, boron, or nitrogen plus boron. The compositions of the four alloys used are listed in Table I. The alloys were vacuum melted from electrolytic iron, electrolytic nickel, ferromolybdenum, and fer-roboron. When required, nitrogen was added by admitting a partial pressure of nitrogen over the melt after vacuum melting. The alloys were cast into 21h-in. diam ingots and hot rolled to %-in. sq bars. No ingot pattern was discernible on the polished and etched cross sections of the hot-rolled bars. The alloys were normalized at 1650°F, then machined into standard %-in. diam end-quench hardenability test bars. Four different austenitizing treatments were used: 60 rnin at 1550°F, 45 rnin at 1800°F, 30 rnin at 2000°F, and 20 rnin at 2000°F followed immediately by 30 rnin at 1550°F. The 1550" and 2000°F treatments were carried out in duplicate for each of the four steels. In order to prevent surface oxidation the bars were austenitized while buried under charcoal in an atmosphere of argon. After quenching the bars in a conventional end-quench fixture, the hardness surveys were made in the usual fashion on parallel flats ground along opposite sides of each bar. These were ground 0.050 in. deep rather than the conventional 0.015 in., to avoid decarburized or deboronized regions.5 The austenite grain sizes which resulted from each heat treatment were observed metallographically using Vilella&apos;s etch for martensite. The criterion used as a measure of hardenability was the distance from the quenched ends of the bars at which a hardness of RC 35 was observed. This hardness represented the inflection point on the hardness vs distance plot. Fig. 1 shows the hardenability of each steel after the several heat treatments. The duplicate tests demonstrated excellent reproducibility; the distance to Rc 35 was reproduced within 1/16 in. for duplicate test bars. All four alloys had the same grain-coarsening characteristics. Neither boron nor nitrogen had any observable effect on grain size. The grain sizes resulting from the various austenitizing treatments were ASTM 7 at 1550°F, ASTM 4 at 1800°F, and ASTM 2 at 2000°F. The small amount of boron in the boron steel greatly enhanced hardenability when the samples were austenitized at 1550°F. The low hardenability of the boron plus nitrogen steel showed that nitrogen eliminated the boron contribution to hardenability. Both steels containing nitrogen, with and without boron, exhibited lower hardenability than the base composition when quenched from 1550°F.

Jan 1, 1958

By C. H. Mathewson

UNFORTUNATE evasions of metals specifications recently brought to public attention through news items and editorials have caused executives of at least two great corporations to set up defensive procedures and to re¬affirm the patriotic purpose and conscientious effort of their plants in this battle of production. Whatever the exact conditions affecting these cases, in which the public interest has been safe-guarded by vigorous action, my reaction to such offenses in general is a feeling that they arise from the pressure and limitations that afflict our overextended war effort and that inevitably there will be more of them, doubtless more and more expertly conceived and less and less subject to detection as simple faked, or substituted analyses or tests. To the ladies, who doubtless are already beginning to ac¬quire a sense of painful resignation to a dry technical talk, may I say that the cookbook is full of specifications which customarily are varied within rather wide limits but it is generally recognized that the proof of the pudding is in the eating without regard to its exact composition or some scientific evaluation of its texture.

Jan 1, 1943

By Wilbur Jurden

THE writer&apos;s first experience with a nonferrous reduction plant of great magnitude was at the Washoe reduction works of Anaconda some 35 years ago. Here was a plant which had been planned with remarkable skill and foresight considering the time and the state of development of copper-plant practice in the year 1902. The designer utilized topography to fullest extent to provide proper sequence of operations and, what is most remarkable, to leave adequate space for future developments, most of which at that time were unknown. However, the practice then was to locate the various units of the reduction works at the most advantageous points of the existing terrain with little regard for tramming or other auxiliaries and then connect these various units by the essential trackage, conveyor systems, piping, etc., as the need developed. This occasionally led to undesirable track arrangements, sharp curves, and steep grades, especially when it became necessary to extend various portions of the plant. Conveyor systems also became rather complicated, running as they did at various angles, and such items as piping and electrical distribution were often found to be in the wrong place, entirely inadequate in size, or awkwardly arranged for any kind of extension. This condition was not peculiar to Anaconda, for all copper plants at that time were built in the same manner and it was the constant association with these difficulties which, in the year 1925, influenced the layout of the Andes Copper Mining Co. plant. In that plant all trackage was laid out straight and level, all conveyors at right angles to each other with minimum length and number of transfers. All buildings were placed parallel and the main structures were complete for all purposes so that auxiliary buildings and dog houses would not be added later. Piping and electrical work was provided for in the original layout and carefully designed to avoid additions and alterations, and careful study given to every movement of material throughout the entire plant so that it would be accomplished with the least possible effort. Naturally it was hardly expected to attain all these objectives perfectly but our efforts did succeed in creating a plant which was unique and outstanding for its time-1927. It was also most gratifying to find that these design principles contributed to considerable savings starting right in the drafting room, carrying through the construction and ultimately yielding savings in operations and manpower. Not only that, but such a plant gives the observer an impression of symmetry and order, is more attractive to the workmen, and unquestionably eliminates many accident hazards. However, the Andes plant buildings were fitted to the existing terrain instead of having terrain created to fit the buildings-an item which we found advantageous to correct on the next large plant. At Morenci in 1939, all of the desirable features of the Andes plant such as parallel buildings, etc., were incorporated; but we went one step further-power shovels were brought in to make the terrain fit the reduction works. The result at Morenci is well-known and needs no elaboration here, but the success achieved by the design methods used for this and previous plants naturally influenced and guided the layout of the Chuquicamata sulphide plant which is the largest yet conceived. Chuquicamata Plant Design At Chuquicamata several factors not encountered previously complicated the problem to a great extent. The most desirable location for the smelter would allow smelter gases to blow directly into the open-pit mine already producing 60,000 tons of oxide ore per day and employing 1550 men. This, of course, would be a serious condition and, therefore, we were forced to move the smelter to a less desirable location but followed our previous experience at Morenci and made the terrain fit the job. The most difficult problem, however, was the provision for receiving various types of ore both by rail and conveyor. These consisted of: 1-Sulphide-bearing residue from the stockpile from which oxide copper had previously been leached. 2-Sulphide-bearing residue coming direct from the leaching vats. 3-Sulphide ore crushed at the existing crushing plants and hauled to the concentrator in cars. 4-Sulphide ore from the new crushing plant adjacent to the concentrator. 5-Sulphide ore obtained

Jan 1, 1952

By D. Brabec

Previous studies have demonstrated the possibility of using aqua regia-extractable copper and zinc in plutonic rocks in exploration geochemistry. The present investigation compares this method of extraction with hydrofluoric-perchloric acid attack and bisulfate fusion in terms of precision and discrimination between high and low concentrations. Statistical treatment of data shows that the overall performance of the aqua regia method compares very favorably with other methods of attack.

Jan 1, 1972

By R. D. Coleman, A. E. McIlhinney, C. E. Capes

Problems of unstable operation in continuous balling circuits may be traced to the random generation of seed agglomerates. This has been verified during the continuous operation of a laboratory balling drum with internal recycle described previously by the authors. The cyclical behavior of a balling circuit was also investigated using a simple numerical computer model. Changes are suggested in the design of balling equipment to improve stability.

Jan 1, 1976

By Robert M. Cox

A roof bolting theory and structural model are presented which explain the success of most roof bolting installations as the creation of a competent roof bolt reinforced rock arch within the immediate roof rock overlying an underground opening. Likewise, the failure of some bolted mine roofs can be explained as a failure to create a structually competent rock arch by roof bolting.

Jan 1, 1975

By E. E. Malouf

Leaching is rapidly becoming an important adjunct to mining operations. A summary of various leaching operations is presented showing the role of these activities to the successful operation of the mining venture. The summary will include recent developments in dump, heap, and in situ leaching of copper and uranium ores. It will include a discussion on the expanding impact of industrial and academic research on leaching as a mining tool, showing the interplay of chemical kinetics and biogenic activity.

Jan 1, 1973

By L. P. (Les) Haldane

Building a small underground coal mine is a risky endeavor, especially in the recent economic environment. ARCO&apos;s Mt. Gunnison No. 1 Mine, located in western Colorado, was designed and built as a small expandable speculation mine with initial production to be sold on the spot market, so it was very important to minimize capital exposure. This mine, operated by West Elk Coal Company, a subsidiary of Anaconda Minerals, was successfully built under budget at $35 million, and has been operating successfully since completion of construction in late 1982. The initial planning phase of a project is extremely important for testing the economic and technical feasibility of a proposal. The construction phase, by contrast, carries with it significant cost and quality risks which can relate to long-term economic and operating problems and therefore directly affect the viability of the project. This paper discusses several different aspects of the cost overrun risk involved in building an underground coal mine, and how attempts were made to minimize these risks during construction of the Mt. Gunnison Mine. Good people, construction planning, and execution are essential factors in assuring a quality, cost-effective project, with corresponding risk minimization during the construction phase and long term favorable implications for the operating phase.

Jan 1, 1985

By D. H. R. Price

This paper presents two tentative models of the use of a notional metal in a country like Britian, which have been developed using the System Dynamics modelling method. Computer simulations have been carried out using one of the models. These show the effect on the recycling of the notional metal of a wide range of possible future values of world market price and demand for the metal.

Jan 1, 1977

By A. E. Hall

The paper gives a general solution of ventilation net- works where densities play an important role and fans operating at different densities from branch densities are considered. Both the physics and computing techniques needed to deal with these networks are discussed.

Jan 1, 1977