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By P. T. Carter, A. B. Murad, H. B. Bell

The distribution of manganese and oxygen between molten iron and FeO-MnO-SiO2 slags not saturated with SiO2 has been determined and used to calculate activities of MnO and SiO2 in MnO-SiO2 slags. These were found to be intermediate between the corresponding activities in FeO-SiO2 and CaO-SiO2 slags. THE equilibrium constant for the reaction between molten iron containing manganese and slags containing FeO and MnO, namely: FeO(slag) + Mn = MnO (slag) + Fe(1iquid) is most conveniently represented by: (MnO) Kmn== (FeOHMn] [Fe] is omitted, since for dilute solutions of manganese in iron, afe is approximately constant. When activities are used for (MnO), (FeO) and [Mn], Kmn is a true equilibrium constant and will apply to all types of slags, but when weight percentages are used, the values obtained for Kmn for different slags vary considerably. The equilibrium between iron containing manganese and relatively pure FeO-MnO slags has been investigated by several workers;1-4 the most recent investigation reported is that of Chipman, Gero, and Winkler.4 Their results, corresponding to slags containing up to 4 pct SiO2, were represented by the equation: 6440 log KMn = +2.95 In this case both slag and metal may be assumed to be ideal solutions, therefore the values of Kmn so derived represent the true constant for the manganese reaction. As the molecular weights of MnO and FeO are almost equal, weight concentration of these oxides may also be used in the above expression. Acidic oxides such as SiO2 and P2O5 affect the activities of FeO and MnO differently, so that when total concentrations by weight of FeO and MnO are used in the above expression for Kmn the values obtained are no longer constant. These will be denoted by K'mn. Körber and Oelsen5 investigated the manganese reaction using silica-saturated iron-manganese-silicate slags and found: 7940 logK'mn =3.172 This corresponds to Kmn values much higher than those obtained for pure oxide slags. The results of Körber and Oelsen, and Chipman, Gero, and Winkler are summarized in Table I. In the present investigation it was decided to study the manganese reaction using iron-manganese-silicate slags not saturated with silica, and which fell mainly between the orthosilicate join 2FeO . SiO2 - 2MnO.SiO2 and the FeO-MnO side of the ternary system FeO-MnO-SiO2. It has been shown" that the phases present in solidified slags of this part of the diagram are (FeO, MnO) and (2Fe0.Si02, 2Mn0-SiO,) solid solutions. Such an investigation would be of interest in deoxidation and also gives information on activities in liquid slags. This equilibrium has not as yet been investigated successfully. Hilty and Crafts7 attempted to examine this reaction in a rotating crucible furnace, but were unable to obtain suitable slag samples. In the present investigation one series of experiments was carried out in a rotating crucible furnace, because the success of Taylor and Chipman8 with such a furnace in their study of oxygen distribution between molten iron and (CaO, MgO) — FeO-Si0, slags suggested that it would minimize contamination of the slag by the crucible material. A second series was carried out using a wire-wound resistance furnace. Rotating Crucible Furnace Experiments In all cases the metallic charge consisted of 800 to 1000 g Armco iron containing 0.02 pct C, 0.03 pct Mn, and traces of Si. Manganese and silicon additions consisted of electrolytic manganese (99.9 pct)

Jan 1, 1953

By R. G. Grieves, G. Thodos

A method is presented for the accurate calculation of the cricondentherm and cricondenbar pressures of multicomponent hydrocarbon mixtures of known composition. The mixtures may contain six and quite possibly any number of components including paraffins, isoparaffins, olefins, acetylenes, naphthenes and aromatics. The approach is similur to that used for calculating critical pressures and cricondentherm and cricondenbar temperatures. The critical pressure, the normal boiling point and the approximate vapor pressure behavior of each component are all that art required. A stepwise culculation procedure is necessary for mixtures containing more than two components. From an analysis of 22 binary systems and 118 mixtures, the average deviation of calculated cricondentherm pressures from reported values is 2.4 per cent. For nine multicomponent mixtures the average deviation is 1 per cent. Considering 19 binary systems and 108 mixtures, the average deviation of calculated cricondenbar pressures from reported values is 1.7 per cent. For 15 multi-component mixtures, the average deviation is 2.2 per cent. INTRODUCTION A knowledge of the phase behavior in the critical region of multicomponent hydrocarbon mixtures is of value both in industrial processing operations and for the optimum operation of gas condensate reservoirs. Accurate methods of calculating the critical temperatures and critical pressures4,6,7,8,9,23 and cricondentherm and cricondenbar temperatures6p10 of multicomponent hydrocarbon mixtures are available in the literature. If the cricondentherm and cricondenbar pressures could be calculated with equal accuracy, the entire phase diagram of a multicomponent hydrocarbon mixture could be well approximated. The work of Etter and Kay6 is limited to systems containing the normal paraffins and has not been tested on systems containing a heavier component than heptane. In addition, the development of their multicomponent equations is based upon a limited number of mixtures containing from three to six components. Silverman and Thodos have considered systems containing both paraffinic and non-paraffinic hydrocarbons, but their correlation is limited to binary systems and is highly inaccurate for methane systems. Eilerts has done extensive work on the cricondenbar pressure; he has produced an excellent correlation for binary systems. However, his procedure for multicomponent mixtures is chiefly useful for highly complex mixtures requiring a knowledge of the vapor-liquid equilibrium behavior of the mixtures; he has not considered the cricondentherm pressure. The objective of this study was the development of an accurate and rapid method for the calculation of the cricondentherm and cricondenbar pressures of multicomponent mixtures containing all types of hydrocarbons and having a wide volatility range. The approach that was adopted is similar to that used by Grieves and Thodos for cricondentherm and cricondenbar temperaturesl0 and for critical pressures.9 However, methane systems had to be considered separately and a modified stepwise calculation procedure was utilized for the cricondertherm pressure. The correlations were developed in a manner similar to those for critical pressures and cricondentherm and cricondenbar temperatures. Based upon binary data reported in the literature it was observed that the ratios of cricondentherm and cricondenbar pressure to the pseudocritical pressure (molar average), pt/ppc and pp/ppc, respectively, in two-component systems depended upon the mole fraction of the low-boiling component and upon the diversity in properties of the two components. A dimensionless boiling-point parameter Tb,/Tb was chosen to represent the diversity in properties of the components. For a binary system, Ti,'is the molar average of the normal boiling points of the two components involved. For a multicomponent system it is either the molar average of the normal boiling points of all of the components involved or the molar average of the normal boiling point of the pure low-boiling component and of the atmospheric boiling point of the low-boiling-free mixture of

Jan 1, 1965

By B. M. Larsen

NEVER having actually tried to engage in the systematic education of anyone, and having little direct knowledge of the practical problems and limitations in the field of education, I can pose only as a "nonexpert" in this field, one whose ideas are to be regarded as personal opinions. The necessity for compromise between educational ideals and the practical limitations of time, money, and mental capacities of both student and teacher is evident in the preparation of an end product that we may regard with a reasonable degree of conviction as a professional engineer. We need to do so many things. The engineering student must have a clear understanding of the basic sciences; he should develop manual skills and co-ordination; he should speak and write the language with simple clarity and directness; he should gather knowledge of a special field; and, he should be educated for living in a broad ..

Jan 1, 1948

By John Mills

THREE case histories from professions other than engineering will serve to introduce ideas basic to this discussion. Case (1) Date, about 1900. A young man, B. D. from a three-year graduate course in a prominent divinity school, was for two years a successful pastor of a small church; then friction over theological matters arose with a fundamentalist deacon of the "Bible belt" type. He resigned, returned to his university for a four-year medical course, interned for two more, and thereafter was successful and apparently happy as a physician. We may assume that he was converted in early adolescence and vowed himself to service as a minister. Acceptance of his announced career by parents, friends, and teachers plus his own determination confirmed his choice until illiberal criticism threatened his usefulness and he awoke to the fact that his inner needs were not along the direction in which inertia and his conscience had constrained him.

Jan 1, 1947

By Heinrich Oscar Hofman

IN THE death of Professor Hofman who was born on Aug. 13, 1852 and died on April 28, 1924, the world has lost a great metallurgist and a great author of metallurgical literature. Measured in time his life was not quite seventy-two years, but measured in work accomplished it was much longer than this. It is not surprising that Dr. Hofman became a great scholar for his father, Karl Hofman, was on the faculty of Heidelberg University, and his early days were spent in these surroundings. He studied in the University under such men as Kirchoff and Bunsen and often spoke of the intimate relations he had with them. Following his course at Heidelberg, he studied at the Clausthal Mining Academy where he graduated with honors, receiving the degrees of Mining Engineer and Metallurgical Engineer in 1877.

Jan 1, 1924

THERE can be little doubt in the mind of anyone of the great interest which has been provoked in the mining and petroleum industry by the com-paratively new geophysical methods of prospecting, after the sessions at this year's meeting of the Institute. Not only were the sessions very well attended but every¬one seemed most attentive. Although the discussion was somewhat limited in general, that may well be at-tributed to the newness of the subject. Two sessions on this subject were planned originally, but these gave insufficient time for the presentation of all the papers prepared and a third session was abso-lutely necessary. The first meeting dealt entirely with the gravity methods and was completed in the scheduled time owing to the fact that but two of the five papers listed were read. The second session was devoted to magnetic and electrical methods, the completion of which had to be carried over into the third period of geophysics. The first session on geophysical prospecting, and in-cidentally the first scheduled Institute meeting devoted entirely to this subject, was most appropriately opened by E. L. DeGolyer, the chairman of the session. It was through the efforts of Mr. DeGolyer that the first gravity work, as applied to prospecting, was under-taken in this country. Again most appropriately, the first paper presented was given by Donald C. Barton, who carried on the first work with the Eötvös torsion balance in America and aided materially in its development. A subject, the theory of which is so difficult to understand as it is generally presented, was so clearly illustrated and ex-plained by the speaker that even a novice could grasp the fundamentals. Dr. Barton, in showing actual re-sults obtained in torsion balance surveys with the in-terpretation of the sane and later drilling records, was free in stating that there are many limitations to the field in which this and the other geophysical instruments may be successfully employed. This paper called for considerable discussion relative to the application of the torsion balance to gravity surveys over various types of structures. During the course of this discus-sion a very important point was emphasized by the chairman, namely, that for successful application of any or all of the scientific methods of prospecting, a back-ground of experience is absolutely necessary to serve as a basis for further work. This can only be secured by contributions from the results of actual prospecting work.

Jan 3, 1928

By W. D. MOTTER

THE following brief description of the status of operations of the Chile Exploration Co. at Chuquicamata, Chile; and of the plant as it exists today, points out the-great progress that has been made since the initiation of prospect drilling in 1912. During the 11 years which have elapsed since then, a group of small mines, eking out a 'precarious existence, has been consolidated into one large operating property,, taking high rank among the world's producers of copper. After a drilling campaign followed by a construction period, the plant first started operations in 1915. Since then production has been gradually increased, as world conditions permitted, until the present status has been reached.

Jan 1, 1924

By WALTER M. DAKE

WITH the renewal of the contract between bituminous miners and operators, whereby a period of three years is assured without the devastating effect of irregularity of operation due to general strikes; and, with the increasing comprehension on the part of the large consumers as to the stabilizing effect of adequate storage upon prices; the coal industry has reached that period of its history in which permanence of purpose towards necessary changes is being crystallized, and these changes accomplished by the industry. It is to be hoped that during this era the phrase- " Our National Coal Problem "-will be relegated to the limbo of' antiquated expressions. That this epoch is upon us is evinced by the fact that operators are turning to consolidations, whereby financially sound companies will acquire smaller production units and place themselves in position to maintain constant supervision and control of their development and output; and, as further proof of the arrival of these changes, may be cited the entrance of additional members of the engineering profession into the many phases of management and operation, where- by the cost per ton of output will be, constantly reduced through the increasing use of modern methods and equipment. As an instance, attention is specifically called to the developments in mechanical loading, proposed and actual continuous underground transportation systems and betterment in methods of preparation.

Jan 1, 1924

By Wayne T. Brooks

The Occupational Safety and Health Act of 1970, although providing no precise definitions of safe and healthful working conditions, specifies mandatory duties, and methods and procedures -- "to assure so far as possible every working man and woman in the nation safe and healthful working conditions." The dynamics of the workplace ad the dynamics of this coextensive Act both spring from the same source. Both require at any given time an application of the then con- temporaneous highest state of the art. Both are flexible, ongoing, adaptive, changing; both advance by a blending of experience and research.

Jan 1, 1972

By George Burgess

THE Pyrometer Committee was. formed Sept. 20, 1918, at the suggestion of Dr. H. M. Howe, Chairman of the Engineering Division of the Research Council, for the purpose of developing a pyrometric method suitable for open-hearth steel practice so that the effects of temperature in the various stages of the processes of steel making might be correlated quantitatively with the other factors influencing the production of sound .steel. As finally constituted the Committee consists of Dr. George K. Burgess, Chief Division of Metallurgy, Bureau of Standards, Chairman. Dr. Paul D. Foote, Chief of Pyrometry Section, Bureau of Standards, Secretary. Dr. H. M. Howe, Chairman Engineering Division, National Research Council, ex officio. Prof. G. H. Clevenger, Chairman Metallurgical Section, National Research Council, ex officio. Mr. F. E. Bash, Leeds & Northrup Co., Philadelphia, Pa. Mr. R. P. Brown, The Brown Instrument Co., Philadelphia, Pa. Prof. G. H. Brown, Rutgers College, New Brunswick, N. J. Mr. R. C. Drinker, metallurgical engineer, Boston, Mass., Dr. W. E. Forsythe, Nela Research Laboratory, Cleveland, Ohio. Mr. J. T. Hall, Taylor-Wharton Iron & Steel Co., High Bridge, N. J. Mr. J. S. McDowell, Harbison-Walker Refractories Co., Pittsburgh, Pa. Mr. Malcolm McNaughton, Joseph Dixon Crucible Co., Jersey City, N. J. Mr. A.' H. Miller, Midvale Steel Co., Philadelphia, Pa. Mr. F. E. Walduck (since deceased), The Norton Co., Worcester, Mass.

Jan 9, 1919

By John B. Porter

Within the last year or so, a great deal has been heard about Southern iron ; even the Eastern markets have felt the effect of the cheap Alabama ores and coals, and public attention has again been drawn to what is now getting to be an old story—the great mineral wealth of the South. The following paper is based on a report prepared several years ago for a special purpose; but since then, through association with Mr. C. B. Going in a large analytical practice and as chemists to the Queen and Crescent Railway, I have had opportunity to increase my material so greatly that the present paper is really a completely different work. I am under very great obligation to Mr. Going, without whose assistance my work would have been very incomplete, and have also been materially assisted by Mr. F. P. Dewey, of Washington, and a host of gentlemen connected with the railroads and furnaces of the South. The arrangement of this paper is not all that could be desired. Some localities of importance are very poorly represented, both in the description and the tables of analyses. This, however, was in most instances unavoidable, as the study has been done ill the intervals of professional work. I have visited almost all the localities described, and, in all cases possible, have taken my own samples, and have made careful per-

Jan 1, 1887

By R. S. Archer

THE name molybdena was employed by Pliny to denote various substances resembling lead. Later this name was applied to galena-the naturally occurring sulfide of lead-or substances of similar appearance. By the middle of the eighteenth century, it was applied to graphite and to the mineral sulfide of molybdenum (MoS2) now called molybdenite. This confusion is quite understand- able inasmuch as these substances look and feel very much alike. In 1778, the Swedish chemist Scheele published a treatise in which he pointed out essential differences between graphite and molybdenite. On treatment with nitric acid, molybdenite, unlike graphite, produced a peculiar white earth with acidic properties which he called molybdic acid. Since the same mineral gave off sulfurous fumes on heating, he concluded that it was a sulfide of molybdenum. In 1790, there appeared an account of the isolation by P. J. Hjelm of the new element molybdenum, as a metallic powder, by heating the oxide with carbon. It was not until Bertelius conducted the necessary experiments, about 1818 to 1825, that the foundation of the chemistry of molybdenum was laid. The only recorded use of molybdenum during the first century after its isolation was as a chemical reagent, primarily for the determination of phosphorus. It was not until the last decade of the nineteenth century that the use of molybdenum in steel appears to have been investigated. A

Jan 1, 1953

The 128th meeting of the American Institute of Mining and Metallurgical Engineers constituted a two weeks trip through the Great Northland of Ontario and Quebec and was a most memorable occasion. The last visit of the Institute to Canada was made in 1907 when the mines, which now have brought world wide fame to some of the camps, were not yet dis-covered. The party reached its greatest numbers at Porcupine where 167 visitors and nearly one hundred local members participated. Five members of the party from the States were on the previous trip in 1907. They were Mr. and Mrs. L. D. Huntoon, John Stevenson and son and E. F. Eurich. The Minister of Mines for the Province of Ontario attached his private car to the "Mining Engineers' Special" and made the complete trip through Ontario. This was a happy incident in many ways and gave the visitors an opportunity to discover a spirit of mutual accord between the Minister and mining industry that might well be emulated elsewhere. Two compartment cars and one standard Pullman with the Institute members from New York and the metropolitan district were attached special to the 6.15 p.m. Lehigh Valley train from New York, Sunday, Aug. 19, en route to Toronto, where was held the first session of the Institute's 128th Meeting.

Jan 9, 1923

The opening session of the Institute was held at the rooms of the American Society of Civil Engineers, No. 4 East 23d Street, VicePresident R. W. Raymond in the chair. After a short introductory address by the chairman, the following names were presented by the Council for election as members and associates of the Institute. They were unanimously elected : MEMBERS. Abbott, James W.,.....Lake City, Col. Abbott, J. J., Jr.,...... Lake City, Col. Bartlett, J. C.,.....Cambridge, Mass. Billings, G. H.,.....Boston, Mass. Blake, Frank C.,.....Lafayette College, Easton, Pa. Dewey, Fred. P.,.....Lafayette College, Easton, Pa. Douglass, Samuel T.,. .. . Ann Arbor, Mich. Emmons, 9. F.,.....New York City. Engle, George U.,.....Philadelphia. Harrington, Dr. Bernard J.,. .. Montreal, Canada. Hayden, Wm. B.,.....Columbus, O. Hill, Leslie C.,.....Capelton, Quebec, Canada. Land, W. J.,......Atlanta, Ga. May, Wm. A.,.....Scranton, Pa. Mills, James E.,.....St. Louis, Mo. Moore, Charles W.,.... Montezuma, Ind. Page, William Byrd,.... Lexington, Ky. Putnam, Douglas, Jr.,.... Ashland, Ky. Richards, Henry,.....Dover, N. J. Boberts, Percival, Jr.,. .. . Philadelphia. Sackett, S. G.,......Brooklyn, N. Y. Schley, Wm. S.,.....Atlanta, Ga. Setz, Gustav,......Mine La Motte, Mo. Talhutt, John H.,.....Lexington, Ky. Torrey, Herbert G.,.... U. S. Assay Office, New York City. Wernlitz, Fred. W.,..., Cartersville, Bartow Co., Ga. Wiestling, Geo. B.,.....Mont Alto, Franklin Go., Pa.

THE opening session of the Institute was held at the rooms of the American Society of Civil Engineers, No. 4 East 23d Street, Vice-President R. W. Raymond in the chair. After a short introductory address by the chairman, the following names were presented by the Council for election as members and associates of the Institute. They were unanimously elected : MEMBERS. Abbott, James W., - Lake City, Col. Abbott, J. J., Jr., - Lake City, Col. Bartlett, J. C., - Cambridge, Mass. Billings, G. H., - Boston, Mass. Blake, Frank C., - Lafayette College, Easton, Pa. Dewey, Fred. P., - Lafayette College, Easton, Pa. Douglass, Samuel T., - Ann Arbor, Mich. Emmons, S. F., - New York City. Engle, George U., - Philadelphia. Harrington, Dr. Bernard J., - Montreal, Canada. Hayden, Wm. B., - Columbus, O. Hill, Leslie C., - Capelton, Quebec, Canada. Land, W. J., - Atlanta, Ga. May, Wm. A., - Scranton, Pa. Mills, James E., - St. Louis, Mo. Moore, Charles W., - Montezuma, Ind. Page, William Byrd, - Lexington, Ky. Putnam, Douglas, Jr., - Ashland, Ky. Richards, Henry, - Dover, N. J. Roberts, Percival, Jr., - Philadelphia. Sackett, S. G., - Brooklyn, N. Y. Schley, Wm. S., - Atlanta, Ga. Setz, Gustav, - Mine La Motte, Mo. Talbutt, John H., - Lexington, Ky. Torrey, Herbert G., - U. S. Assay Office, New York City. Wernlitz, Fred. W., - Cartersville, Bartow Co., Ga. Wiestling, Geo. B., - Mont Alto, Franklin Co., Pa.

Jan 1, 1877

By H. J. C. MAC DONALD

THE mining engineer must have a chest of books snug enough for a camelback or to be stowed away in a canoe; at the lowest possible cost, as he needs it the most in those early years when he earns the least; but at the same time one having an unusually wide range, for he may have to cut down a forest, put up a sawmill, build mine towns, construct dams, power houses, power lines, and railroads. In fact he may be called upon for many unexpected accomplishments and all in extension of the characteristically broad demands of his profession. Suppose that an average mining engineer with a thorough theoretical training and a specialized mining education has accumulated, during a cosmopolitan experience, a complete and up-to-date library, but, unfortunately, in accepting a long term assignment to a far country he is forced to discard the greater part of

Jan 1, 1925

By M. Semchyshen, G. A. Timmons

P. A. Beck (University of Illinois, Urbana, 111.)—An interesting result of this work is the fact that in cold rolled molybdenum sheet complete loss of work hardening is obtainable on annealing, without change in texture. The retainment of the cross-rolling texture on soft-annealing is particularly significant, since this is essentially a single orientation texture, where texture retainment could be achieved by only one of the two niechanisms which produce this effect in aluminum,16 namely by recrystallization in situ. Recrystallization in situ was originally discovered by Collins and Mathewson (1940) and by Crussard (1944) as a phenomenon taking place on annealing in relatively mildly deformed single crystals of aluminum. It now appears to be a major (in many cases the major) mechanism of annealing of severely cold rolled poly-crystalline material, not only in aluminum,le but in metals as different in character as beryllium," tita- nium,'" and molybdenum. All these data now confirm the general validity, at least for more or less pure metals, of the interpretation of the annealing process given a few years ago by Smith.'" The whole question of recrystallization is now reopened. Indeed, it appears that recrystallization, as defined traditionally, may not occur at all, since at the time "deformed material" is absorbed by "recrystallized grains," it has already become completely strain free by recovery and "recrystallization in situ."

Jan 1, 1953

By E. P. Shea

The Anaconda Co.'s Geological Department at Butte, Mont., was started early in the Company's history because of litigation involving vein ownership and extralateral rights. The problems, some of which were resolved in courts, were many because of the large number of veins and lode locations. Defensive action was required to prove ownership and protect against illegal exploitation of the downward and extra-lateral extensions of the ore bodies. In many cases it was necessary to define the outcrop of the vein and to show that its apex was within the boundaries of the lode claim. Exhibits illustrating geology were needed to present the cases clearly, and these could be made only after careful inspection and mapping of the underground workings by competent geologists. Also, The Anaconda Co. was one of the first companies to recognize the worth of skilled mining geologists and the value of accurate records in the search for new ore. The department was organized in 1900 by H. V. Winchell who, with D. W. Brunton, worked out the methods. Reno Sales was Chief Geologist from 1906 until 1948 when he was succeeded by V. D. Perry, the present Chief Geologist. Under their direction, F. A. Linforth, M. H. Gidel, C. H. Steele, E. P. Shea, C. C. Goddard, Jr., and W. A. O'Brien enlarged the scope of the work and improved the technique.

Jan 3, 1961

By Wolfgang Hermann

The ancit-process of the Eschweiler Bergwerks-Verein, an affiliate Company of ARBED S.A., Luxembourg, was developed in its principles by the Dutch State Mines, Limburg, in the mid-50's with the aim of producing a smokeless domestic fuel on the basis of low volatile hard coal. In 1967, the EBV erected a 10 t/h large- size pilot plant along these principles in the Aachen mining district and further developed the acquired know-how. In hardly 10 years more than 650 000 t of ancit briquettes with unit weights between 17 and 100 grams were produced and in the meantime stream rates of over 85 % of the yearly utilization hours have been reached. In more than 10 blast furnace trial runs involving substitution rates up to 100 p. c. ancit have proved the suitability of ancit as a metallurgical fuel both for a burden with a high and a poor iron content. Construction work for a minor process-step to enable processing of coal with a higher content of volatile matters is finished and first results are expected by summer this year. A pilot plant with a 30 t/h capacity working on a low-volatile coal basis is being planned. Engineering and construction are supervised by MecanARBED. Luxembourg, as responsible contractors.

Jan 1, 1977

By P. Somasundaran, R. D. Kulkarni

Reagentizing at elevated temperature, reported in the past as beneficial for the flotation of hematite using oleate, is studied here as a function of collector concentration, solution pH and ionic strength at various levels of conditioning temperature. The study revealed strong interactions between variables; particularly, the effect of conditioning temperature was found to strongly depend on the ionic strength of the solution. Thus, while an increase of conditioning temperature at lower ionic strengths or that of ionic strength at lower temperatures resulted in an increase of both flotation and grade, an increase of the former at higher ionic strength or that of the latter at higher temperatures caused a significant decrease in both responses. These observations have been explained in terms of the increased chemisorption of oleate at elevated temperatures and the temperature effect of ionic-strength on the salting out of the oleate from the bulk solution. The above effects which were first observed during Hallimond cell flotation tests were subsequently tested with Denver cell using low-grade iron ore. The results obtained using the two test procedures were in agreement with each other. The implications of these effects and interactions for process control of optimum flotation performance must be noted since variation in the levels of the above parameters are likely under plant conditions.

Jan 1, 1978