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By Hollis Peacock

THE Bingham area in the West Mountain mining district on the eastern slope of the Oquirrh range, some 28 miles southwest of Salt Lake City, has been the most consistent producer for the United States Smelting Refining and Mining Company, production having been continuous, except for minor interruptions, since the organization of the United States Mining Co. in 1899. This production has come from fissures and mantos largely within limestone members aggregating something less than 10 per cent of a thick quartzite sequence of Pennsylvanian age which has been warped into an open syncline plunging northwesterly. Bedding on the easterly limb dips 10°-45° but steep-ens to 90° and even overturns on the westerly limb. Ore bodies cluster about the more northerly of two elongate interconnecting stocks of monzonite which have risen in an axial position within this syncline. Largely within the more northerly of these stocks is the low-grade copper ore body exploited in the Utah Copper open cut of the Kennecott Copper Corp. The values, in seams, minute fracture fillings, and disseminations of pyrite and silica, pervade not only the stock but adjacent sediments, and form a nebulous, sprawling mass which both mineralogically and geographically is the center of the district. The more southerly of the twin stocks appears to be comparatively inert and without obvious relation to mineralization. which

Jan 1, 1948

By L. R. Blair

Many hydrated silicates have been synthesized and sold for commercial use. However, this paper discusses only hydrated calcium silicates and, to a lesser extent, hydrated magnesium silicates. Synthetic calcium silicates were first formed by man when he found that mixtures of silica or silicates and lime in water set up to form cements. The material which was responsible for the cementing properties was calcium silicate hydrate, although this fact was not recognized until early in this century. In the early 19001s, synthetic calcium silicates, reinforced with fibers and formed simply by reacting calcium hydroxide and silica in water with fiber at atmospheric or under low pressure autoclave conditions, found increased use in thermal insulations and in building products. These insulations were found to have a low thermal conductivity and would withstand temperatures up to 650°C. This, combined with their very low densities (from 8 to 50 Ib per cu ft) and fairly high strength, also made them suitable for use as building products. Following the disastrous Morro Castle fire of the 1930Js, calcium silicate board products were used as partitioning material in all shipboard construction in the U.S. As autoclaving techniques were improved and developed, it was: learned that under hydrothermal conditions new and useful calcium silicates which could be used under more extreme temperatures (up to 980' C) could be prepared. These had high surface areas and other unique properties which suited them for use as fillers, pesticide carriers, low temperature insulating materials, and adsorbents for the removal of fatty acids from various solutions. Hydrated magnesium silicates have not been studied as extensively as the calcium compounds. Their first important use was in the filtration of dry cleaning solutions for the removal of fatty acids. With the introduction of detergents, it was found that these products lost their advantage because of their high affinity for the detergent chemicals. However, in recent years these chemicals are finding increasing use as decolorizing agents for fats and anti-caking agents for resins. Some materials with very high surface are finding new use as adsorbents. CALCIUM SILICATE HYDRATE COMPOUNDS AND THElR CONDITIONS OF FORMATION Within the past ten years much has been done in the field of calcium silicate hydrate chemistry. As a result of this work it has been found that at least 25 different forms of calcium silicate hydrate can either be formed synthetically or found as naturally occurring materials. The stability and composition relationships among these 25 compounds present a very complicated picture, and many of these very closely resemble other forms and are difficult to dis-

Jan 1, 1962

By Harlowe Hardinge

AN extensive recent trip throughout the mining districts of the Southwest, Central West, an Northwest,' reveals a numbes of interesting conditions that have influenced operators, in both large and small mills, to modify their flow sheets insofar as they pertain to crushing and grinding. The changes made and planned for the future should be of interest. It is interesting to note when traveling through the country, how ideas change and practice is modified, and it is rather amusing to see how milling methods seem to run, more or less, in cycles. New ideas and developments are brought about which run through the industry and are taken up by many of the best and most well informed operators. Some of them will change, sooner or later, back to their old practice; for, like everything .else, what will work well in one place will not necessarily be suited to another. On the other hand, it is often difficult to establish. other practices known to be of value, owing to the natural resistance to make a change, but on the whole, the western mill men seem to be more alive to possible benefits of various modifications than any other engineers with whom I have come in contact in all parts of the world. Mill men in other parts of the world always keep in con- tact with what is being done in the western part of the United States, but it does not necessarily follow that those in the western part of the United States are always right. Some of these changes that have been made and afterward abandoned will be referred to later.

Jan 1, 1929

By Galen H., Clevenger

THE first and most important thing that affects the majority of lead producers in the Rocky Mountains and the western mining regions is that zinc in an ever-increasing degree is inseparably associated with the lead. The Sullivan mine in British Columbia is not only a great lead mine, but also a great zinc producer. This mine could not reach its full measure of productiveness, nor was its great value established, until a reasonably good physical method was developed for separating the lead from the zinc prior to the recovery of each metal by an appropriate process. The western metallurgists and also metallurgists in other parts of the world have long faced the lead-zinc problem. This for many years stimulated a great deal of experimental work looking toward the development of a physical or chemical method of separating lead and zinc in concentrated form from complex ores. Space will not permit of going into this work in detail, but it is sufficient to say that with but few exceptions the western lead smelter continued smelting charges many times too high in zinc for the most efficient operation of lead furnaces. The zinc was not only lost, as the zinc content of many a western slag dump bears mute testimony, but the cost of lead smelting was increased by reason of the presence of the zinc. The owner of the ore under these circumstances could be paid nothing for the zinc and, indeed, he was penalized for it

Jan 1, 1926

Although copper production established a new record, lead and zinc registered gains, and iron production held steady, the mixed trend in metallic and nonmetallic mining and generally lower prices in 1961 resulted in a net decline in the total value of domestic mineral production. According to preliminary estimates from the U.S. Bureau of Mines, the value of metals produced in this country during the year was approximately $1.9 billion, a decrease of $117 million from 1960; the value of nonmetallics was about $3.7 billion, a $14 million decrease. The following report of mining and mineral developments during 1961 is based on USBM and industry sources. Aluminum Output Dips from 1960 Record Government reports indicate that the domestic primary aluminum industry produced approximately 1,880,000 tons, equivalent to 77% of this nation's capacity. This production is about 6% below the 1960 record output of 2,014,498 tons. Shipments of primary metal ingot slightly exceeded the quantity produced.

Jan 2, 1962

John Eliot Allen has been made acting head, dept. of geology, New Mexico Institute of Mining and Technology, Socorro, N. Mex. He had been associate professor of geology. Robert B. Anderson has accepted a position with the U. S. Steel Co., Gary, W. Va., as assistant to the superintendent, No. 2 mine. [ ] Donald L. Archibald has joined the sales dept. of the Ellicott Machine Corp., Baltimore. He formerly had been associated with the Joy Mfg. Co., St. Louis. J. C. Boswell has been appointed manager of the Fairbanks dept., United Smelting Refining & Mining Co. J. B. Metcalfe has been appointed assistant to the president. G. Howard LeFevre was elected vice-president and general manager of metal sales and R. N. Hunt, vice-president and chief geologist was elected a director. R. B. Earling, vice-president and general manager of Alaskan operations, has retired but. will con¬tinue to serve on the board of directors. J. D. Crawford has been appointed general manager of Alaskan operations.

Jan 1, 1952

By Hal M. Scrugham

UNITED States Steel Co.'s Tennessee Coal & Iron Div. Wenonah mines present definite materials handling problems arising from the natural features of the operation. Trackless equipment went a long way toward supplying the answers-but at the same time gave birth to several new posers. Machines-trackless or otherwise-require maintenance and Wenonah's experience may do much to add to the body of information already available on this type of equipment. Let's look at the mines themselves. Ore is of sedimentary origin, extending over an area of several square miles. A thickness from 8 to 14 ft is mined. Bed dip varies from the horizontal to 20 pct in local rolls. Practice is to mine across the dip at 14 pct or less. A parting forms a smooth footwall in some of the mines while in others the footwall must be blasted smooth. Ore weighs 215 lb per cu ft in place and is extremely abrasive.

Jan 6, 1953

By G. Osuch, G. Derge, G. M. Pound

Using a new dternating-current potentiometer circuit and a specially designed four-terminal cell, the specific conductance of molten Cu2S-FeS mattes was measured as a function of temperature, from the liquidus to 1500°C, over the complete range of composition. The high conductivities, about 1500 ohm-I cm-l for FeS and 100 ohm-l cm-l for Cu,S, indicate that the conduction is electronic rather than ionic. Molten FeS has a negative temperature coefficient of specific conductance, resembling metallic conduction. Molten Cu,S has a positive temperature coefficient, resembling semiconduction. The binary roughly follows an additive rule of mixtures with respect to both magnitude and temperature coefficient of specific conductance. Metallic bonding in the liquid is postulated to explain these phenomena. MUCH has been learned in the past about the nature of liquids and the ionic or molecular species in solution by means of electrical measurements. Thus, dielectric constants','2 have given information about molecular liquids such as water and benzene. Measurements of dielectric constant usually are impossible in electrically conducting liquids, such as aqueous solutions of ionic salts and molten ionic salts. However, measurements of electrical conductance and ionic transference have provided much knowledge about the latter systems.a-" In recent years, the ionic nature of certain molten metallurgical slags has been established by Derge and Martin7 through electrical conductance and electrolysis measurements. Chipman, Inouye, and Tom-linsonq ave studied the electrical conductance of molten FeO and report a high specific conductance of about 200 ohm-' cm-' (compared with 4 ohm" cm-' for an ordinary ionic liquid such as molten NaCl) and a positive temperature coefficient of conductance. They interpret these results in terms of p-type semiconduction by analogy to the situation in solid FeO.Y imnad and Derge" have studied cell efficiency in the electrolysis of molten FeO-SiO, systems and conclude that ordinary ionic conductance increases with SiO, content. Very recently, interest has been revived in the electrical conductance of liquid metals and liquid metallic solutions. Scala and Robertson1' report a close resemblance between the liquid and solid states with respect to thermal, structural, and compositional relationships. Molten sulphides have not received a great deal of attention. Bornemann and von Rauschenplat" measured the specific conductance of molten Cu2S as a function of temperature with a four-terminal cell using direct current. A high specific conductance and a positive temperature coefficient were found in that investigation." Using a two-electrode apparatus, Savelsberg" electrolyzed various molten sulphide mixtures. He concluded that pure molten Cu,S and FeS were electronic conductors but that the mixtures exhibited some ionic conduction. In the present investigation, the specific conductance of the industrially important Cu-Fe sulphide mattes was measured as a function of temperature and composition in order to investigate the mode of electrical conduction and the structure of these molten mattes. An alternating-current circuit was used to eliminate the effect of any possible electrode reactions. Apparatus The Conductance Cell: Due to the high specific conductance of the systems studied (10' to 10" ohm-' cm-'), the classical two-terminal cell and Wheat-stone bridge apparatus could not be used. A four-terminal cell was developed in order to eliminate lead resistance, and an ac potentiometer circuit was designed to give rapid and sufficiently accurate measurements of the cell resistance. A diagram of the conductivity cell is given in Fig. 1. The molten matte is contained in a dense alundum crucible, and spectrographic graphite rods that dip into the molten matte serve as the four conductance terminals. Two of the graphite rods on opposite sides of the cell serve as current-carrying leads, and the other two graphite rods are null-current probes that detect the potential drop across the cell. These graphite rods are contained in silica tubes, and the lower constricted portions of the two silica tubes define the column of liquid whose electrical resistance is being measured. The electrical resistance of the broad ex-

Jan 1, 1956

By Otto Henry

THE purpose of this investigation was to determine the equilibrium diagram of the lithium-magnesium pair as a first step in studying the possible usefulness of these alloys as ultra-light structural materials. REVIEW OF THE LITERATURE The behavior of lithium towards magnesium was first investigated by Masing and Tammann.(I)? In order to prevent oxidation the alloys were made in iron tubes under an atmosphere of hydrogen; temperatures were measured with a glass-protected thermocouple. These investigators found that lithium and magnesium form two series of solid solutions separated by a miscibility gap between 85 and 95 per cent magnesium; that the alloys with 81 and 95 per cent magnesium showed a homogeneous structure under microscopic examination, while the alloy with 89 per cent magnesium contained two distinguishable crystallites; that the curve indicating the beginning of crystallization rises from the melting point of lithium to that of magnesium; and that no compounds of lithium and magnesium are formed. The equilibrium diagram was not plotted because no definite data were obtained for determining the solidus and the posi-tion of the miscibility gap in the solid state. The difficulties encountered in this investigation were: (1) that it was necessary to heat them as high as the melting point of magnesium in order to obtain homogeneous melts; at such temperatures the alloys attacked the glass protecting the thermo-couple; and (2) that at temperatures above 400° C. the lithium united

Jan 1, 1934

By G. Derge, Ling Yang, G. M. Pound

The specific conductance and its temperature dependence were measured over the entire composition range of the molten Cu2S-CuCI system. At a typical temperature of 1200°C, 10 rnol pet of the ionically conducting CuCl reduced the specific conductance from about 77 ohm-lcm-l for pure Cu2S to about 32 ohm -1cm -1, and 50 mol pet CuCl reduced the conductance to that for pure CuCI—about 5 ohm 1cm1. The nature of electrical conduction in molten Cu2S, FeS, CuCI, and mixtures was studied by measuring the current efficiency of electrolysis at about 1100°C. The Cu2S, FeS, and mattes were found to conduct exclusively by electrons, but addition of 1 5 wt pet CUS to Cu2S produces a small amount of electrolysis. Addition of CuCl to Cu2S suppresses electronic conduction, and ionic conduction reaches almost 100 pet at a CuCl concentration of about 50 mol pet. These facts are interpreted in terms of electron energy level diagrams by analogy to the situation in solids. RESULTS of electrical conductivity studies on molten Cu-FeS mattes as a function of composition and temperature have been reported.' The specific conductances ranged from about 100 ohm-' cm-' for pure Cu2S to 1500 ohm-' cm-1 for pure FeS. This is in sharp contrast with the low specific conductance of molten ionic salts for which the transfer of electricity is by migration of ions in the field. In general, these ionically conducting molten salts, such as NaC1, KC1, CuC1, etc., have a specific conductance of the order of magnitude of 5 ohm-' cm-'. It was concluded on the basis of this evidence that molten FeS and Cu,S exhibit electronic conduction. Pure molten FeS has a small negative temperature coefficient of specific conductance, resembling metallic conduction, while pure molten Cu2S has a small positive temperature coefficient, resembling semi-conduction. The molten Cu2S-FeS mattes follow a roughly additive rule of mixtures, both with respect to specific conductance and temperature coefficient. Savelsberg2 has studied the electrolysis of molten Cu2S and Cu2S + FeS. He concluded that while molten Cu2S is an electronic conductor, there is some ionic conduction in molten Cu2S + FeS3 owing to the formation of the molecular compound 2Cu2S.FeS and its dissociation into Cu1 and FeS2-1 ions. The present work does not verify his results. Chipman, Inouye, and Tomlinson" have studied the specific conductance of molten FeO and report a high specific conductance, about 200 ohm-1 cm-1 of the same order of magnitude as that found for molten mattes, and a positive temperature coefficient. They interpret these results in terms of p-type semiconduction in the ionic liquid by analogy to the situation in solid FeO.1 imnad and Derne' detected appreciable ionization in molten FeO by means of electrolytic cell efficiency measurements. In order to verify the conclusion that electrical conduction in molten Cu2S and mattes is electronic, and to gain further insight into the structure of molten sulfides, the following investigations were carried out in the present work: 1) The specific conductance, s of the molten system Cu2S-CuC1 was measured as a function of temperature over the entire composition range. As discussed later, molten CuCl is an ionic substance. It was thought that if molten Cu2S were simply ionic in nature, addition of small amounts of CuCl might not have a catastrophic effect in lowering the high conductance of the Cu2S. On the other hand, if much electronic conduction occurs, addition of the ionic CuCl should have a large effect in destroying the electronic conduction. 2) The electrolytic cell efficiency of the following molten systems was measured at about 1100°C in specially designed cells: Cu3; Cu2S + FeS, 50:50 by wt; FeS; Cu2S + CuS, 15 wt pet; Cu2S + CuC1, 5.9 to 46.4 mol pet; and CuC1. This gives a direct measure of the fraction of current carried by ions in these melts. Further, the cell efficiency, extrapolated to zero ionic current, is given by cell efficiency = (s leasile + s elexstronic). [1] s lucile for molten CulS would be expected to be no greater than that for molten CuC1, whose s lonle is about 5 ohm-' cm-1, as will be seen in the following. u,.,,.,.,.......for molten Cu,S is of the order of 100 ohm-' cm-'.' Thus, a large increase in cell efficiency from 0 to values of 10 to 100 pet upon addition of CuCl to Cu2S would indicate destruction of the electronic conductance. Conductance Measurements Experimental Procedure—The apparatus and experimental method were the same as those described in detail in connection with the study of electrical conduction in molten Cu,S-FeS mattes.' A four terminal conductivity cell and an ac poten-

Jan 1, 1957

By Albert Sauveur

Jan 1, 1924

By Albert Sauveur

Jan 1, 1924

Abramovits, Charles, Student, Case School of Applied Science Cleveland, Ohio. '37 Abreu, Ovidio M., Student, Stanford Univ Stanford University. Calif. '38 Adams, Albert, Student, New Mexico School of Mines Socorro, N. M. '38 Adams, Benjamin C., Jr Address Wanted. '36 Adams, George H 44S2 4th St., Riverside, Calif. '36 Adams, Robert E., Student, Univ. of Wisconsin Madison, Wis. '38 Adkisson, J. F., Jr., Student, Agricultural & Mech. College of Texas, Box 2044, College Station, Tex. '38 Afshar, Hodji khan A., Amiranian Oil Co 10 Khiahan-i-Nusrat, Teheran, Iran. '35 Agvas, Cesar G., Student, Adamson School of Industrial Chem. & EngrgManila, P. I. '38 Ahlen, Louis S., Student, Univ. of North Dakota Univ. Sta., Grand Forks, N. D. '37 Albers, Francis C., Student, Univ. of Wisconsin Madison, Wis. '38 Alden, George P., Student, Univ. of Tulsa Tulsa, Okla. '38 Alexander, Donald B... Student. Univ. of Oklahoma, Sigma Nu House Norman, Okla. '37Alexander, Joe M., Student, Agricultural & Mech. College of Texas. Box 954. College Station. Tex. '38

Jan 1, 1938

By Tadao Nagai, Masao Sato

Electrochemical measurements have been carried out in an auto- clave to investigate the electrochemistry of hydrogen precipitation of nickel from acetate buffered solution. After having previously obtained the rate equation for this reaction we have now made a concentrated effort to explain the rate equation electrochemically. A saturated NaC1-type Ag/AgC1 reference electrode has been improved so that it can be used in an autoclave. Polarization curves for the reaction, [H2=2H+ + 2e,] on nickel electrode were measured in solutions free from nickel ions at 185°C, and the parallel curves were obtained by changing PH2 and pH for normal and reverse reactions, respectively. Polarization curves in nickel solutions were complex, probably because the potential of hydrogen electrode is close to that of nickel and of the nickel surface altered during polarization. Then the nickel electrode potential and the reaction rate were measured simultaneously during pressure reduction at various hydrogen pressures and at various nickel concentrations. The reaction rates in terms of current density were plotted to obtain the local polarization curves for reactions Ni2+ + 2e ? Ni and H2 ?2H+ + 2e. The anodic and cathodic local polarization curves exhibit potential dependency. Therefore it is likely that the pres- sure reduction can be regarded as a coupled electrodes reaction.

Jan 1, 1973

By AIME AIME

NAPOLEON'S dictum that an Army travels on its stomach has not changed in this present war, but the things an Army's stomach calls for would be more than strange to Napoleon. Today one of the main articles of diet for the mechanized army is oil and gasoline, and the chief and most efficient source of 'apply overland is the pipe line. It was a flexible 4-in. pipe line that supplied the voracious appetite of tanks, trucks, jeeps, and planes across the North African desert. and it is the 1800-mile pipe line from Calcutta to Kunming, Yunnan Province in China, the longest in the world, that supplied oil and 100-octane gas for the trucks, tanks, Jeeps, and planes fighting on the Assam-Burma-China front in recent months. Completion of this approximately 1800-mile pipe line to China over rivers that had never been bridged, over hill that towered 9000 ft., and over swamps

Jan 1, 1945

By Clyde Williams

IF you would allow me some liberties, I would restate the title of this talk as "Scientific Research, Our Greatest Resource," because that title would represent more clearly a present-day conception of the metals and minerals situation. It is a subject worthy of careful consideration. Canada and the United States are so similar and interdependent in their national economies that, in the following discussion, examples of conditions in the United States may be interpreted to apply to Canada as well. Moreover, it is a striking fact that the per capita value of mineral production in Canada and the United States in 1940 was almost the same. Therefore, in the consideration of this subject, I have made no attempt to differentiate between the two countries. Consumption of the world's mineral resources in the last few decades. and particularly during World War II, has been so enormous as to require some form of magic to ensure the continued progress of civilization in the face of a diminishing supply of these resources which are so critically essential. As C. K. Leith pointed out, in 1941, indus-

Jan 1, 1947

The Committee on Nominations begs to submit the following names as its nominees for the respective offices indicated: For President, SIDNEY J. JENNINGS, New York. For Vice-Presidents, WALTER H. ALDRIDGE, New York; MARK L. REQUA, San Francisco. For Directors, J. E. JOHNSON, JR., New York; ALLEN H. ROGERS, Boston; HOWARD N. EAVENSON, West Virginia; ROBERT M. RAYMOND New York; WILLET G. MILLER, Canada.

Jan 12, 1916

By R. J. Hopkins, L. B. Haney

On the basis of limited experimental work conducted at the Port Pirie smelter, it would appear that, by increasing the specific surface of sinter, and possibly that of coke as well, a marked increase in the rate and degree of sinter reduction in the furnace shaft can be achieved. Fusion-point tests have shown that this increased reduction means a much higher sinter fusion point and narrower plastic zone, while the more efficient utilization of coke in the furnace is inherent in the intensification of reduction by the provision of a more reactive sinter surface. Investigations aimed at increasing the ability to operate the blast furnace with a higher lead tenor of sinter reducing fuel cost proportionately, and at eliminating the loss in reduction potential in coke entering the furnace, as shown by the presence of appreciable proportions of CO in the top gases, are reported. Several lines for future investigations that could result in improved smelting methods are proposed. A SOMEWHAT informal presentation of ideas on lead blast-furnace smelting will be given in this paper. These ideas have been developed during observations of furnace behavior at Port Pirie and earlier at Mt. Isa, and have been guided by the results of laboratory experiments at Port Pirie. The authors do not intend to propound any particularly new theories, but present their ideas as a basis for discussion which may help toward a better understanding and improved control of blast-furnace operation. Performance variations of considerable magnitude occur from time to time at most lead blast-furnace plants. While Port Pirie is fortunate in having a very regular supply of high grade concentrates, it is no exception in this respect. Such irregularities are of considerable economic importance and they constitute a challenge to present-day metallurgists in their efforts to obtain an ever greater degree of control over furnace operation. In operating as Port Pirie does with a relatively high lead charge, it has been recognized for a long time that shaft conditions are ,of the greatest importance. A practical, or engineering, attack on the problem of accretions consisted of changes in furnace design, e.g., by widening the shaft to 10 ft above the bottom row of tuyeres, and by the provision of curved ends and vertical walls.' That this attack has had a great measure of success is shown by the fact that barring down of these wide furnaces is rarely necessary, shaft conditions have greatly improved, and sensitivity to charge variations has been markedly reduced. These modifications, followed by some metallurgical changes (chiefly the incorporation of pig iron into the furnace charge in 1948), have brought furnace operation to a point where some variables which were previously masked can now be studied. Accordingly, over different periods of time during the last five years, such variables as could be given numerical values have been recorded and subjected to statistical examination. The objectives of this work were: 1—to reveal the true importance of the different variables and 2—to show the proportion of total furnace variation which is unexplained and therefore referable to causes not measured at present? e.g., shaft accretions, sinter structure, coke structure, and others. Statistical Study of Variables In this work factors relating to furnace speed and lead reduction have been examined: 1—slag com-

Jan 1, 1955

By T. M. Morris

G. L. Simard and D. J. Salley—The authors and ourselves" independently came to similar conclusions both as to the value of tracer methods for the study of flotation and the general nature of collector-mineral interaction. The dodecylamine-quartz system appears to be simpler than the dithiophosphate-galena one, and the results therefore appear clearer. It is evident from a comparison of the two papers, however, that care must be used in extending the results to other more complicated systems. In the case of dodecylamine-quartz, the possible influence of micelle formation is of interest. There is no a priori reason why complete monolayer formation should necessarily occur at the concentration for micelle formation, since sorption depends on the nature of the substrate as well as on the properties of the solute in solution which alone determine micelle formation. Indeed, the fact that the onset of increased adsorption, point B in fig. 2, occurs at a concentration one tenth the critical value for micelles might imply that micelle formation does not have an influence. Interestingly enough, the data may be handled by the methods used for multilayer adsorption of gases on surfaces. Thus, if the amount adsorbed is plotted versus concentration, a sigmoid type curve is obtained, similar in form to a so-called Type I1 isotherm13 generally attributed to multimolecular adsorption. A monolayer value of about 0.12 mg per g may be estimated from the knee of this isotherm. On the other hand, if a plot is made according to the multilayer gas equation for adsorption to an unrestricted number of layers, eq 38,13 assuming the critical micelle concentration as the saturation concentration, the data above 120 mg per liter fall on a straight line from which a monolayer adsorption of 0.3 mg per g results. These considerations suggest that the monolayer may occupy an area somewhat less than the geometric value of 0.4 mg per g, and that micelle formation may indeed be a factor in the adsorption. the angle between the solid-liquid and liquid-gas interfaces, measured through the liquid. The value of the equilibrium contact-angle is uniquely determined by the value of the interfacial energies of the three intersecting interfaces and is independent of other forces in the system. When the liquid-gas interface intersects the solid at an edge—as was the case for all the experiments reported in this paper—the orientation of the solid-liquid interface is indeterminate or varies through 90" for a right-angle edge. Mr. Morris has called the angle between the horizontal and the liquid-gas interface for this edge condition a "static contact-angle." I feel that this term is unnecessarily misleading. In the first place, "static contact-angle" sounds too much like "equilibrium contact-angle." In the second place, the magnitude of the "static contact-angle," which I would prefer to call the "supporting angle," is determined by the forces in the system other than those derived from the interfacial energies, hence "contact angle" is misleading. If Mr. Morris had said that the "supporting-angle" is variable and depends on the weight of the particle and size of the bubble and that it has a maximum possible value equal to the equilibrium contact-angle, his discussion would have been more accurate. T. M. Morris (author's reply)—Mr. Kellogg puts forth a reasonable criticism of some of the terminology used in the paper. I agree that the term "static contact angle" may be misleading. Substitution of the term "supporting angle" or "vector angle" may be more suitable. F. X. Tartaron—In this paper the author presents a very interesting mathematical development of the forces present when a mineral particle adheres to an air bubble. Excellent concordance is obtained between mathematical formulation and experimental results. It is the writer's understanding that when the mineral surface presented to an air bubble is greater than the area of contact, the maximum contact angle is obtained. However, this contact angle represents distortion of the bubble, the normal shape of which is spherical or in cross-section, circular. This distortion produces a force that acts in opposition to the force of adhesion between the bubble and particle. Hence, at maximum contact angle, the force of adhesion between bubble and particle is at a minimum for static conditions. However, when the size of bubble is increased, the size of particle remaining the same (and all other conditions remaining the same), the contact angle decreases, the distortion of the bubble decreases and the force in opposition to adherence of bubble and particle also decreases. Thus, there is stronger attachment between bubble and particle. When this situation is applied to actual flotation conditions, it is doubtful that it has any significance. The reason is that the bubbles are normally so much larger than the particles, that in substantially all cases, it is probable that negligible distortion of the bubble takes place. In table IV, the author makes computations for bubbles from 0.50 to 2 mm diam. This is from 0.02 in. to 0.08 in. Certainly the bubbles generated in a flotation machine are far larger than this. The surfaces of the author's bubbles range from 0.79 to 12.6 sq mm. The area of contact of the glass rod (0.15 mm diam) is 0.017 sq mm. Thus, ratio of bubble surface to mineral area of contact ranges from 47 to 741 in round numbers. If we take a %-in. diam bubble and a 65-mesh (0.208 mm) particle of cubical shape, the ratio of bubble surface to mineral area of contact is 2931. Mineral particles do not readily become attached to air bubbles. Taggart has shown that in pneumatic flotation machines collector-coated particles are only temporarily attached to bubbles. They keep falling off and down in the froth but at a delayed rate as compared with gangue. Spedden and Hannan's motion pictures confirm the difficulty of attaching particles to air bubbles. In the agitation froth process, according to Taggart, air is precipitated from the water selectively on to the collector-coated particles and these

Jan 1, 1951

By T. M. Morris

G. L. Simard and D. J. Salley—The authors and ourselves" independently came to similar conclusions both as to the value of tracer methods for the study of flotation and the general nature of collector-mineral interaction. The dodecylamine-quartz system appears to be simpler than the dithiophosphate-galena one, and the results therefore appear clearer. It is evident from a comparison of the two papers, however, that care must be used in extending the results to other more complicated systems. In the case of dodecylamine-quartz, the possible influence of micelle formation is of interest. There is no a priori reason why complete monolayer formation should necessarily occur at the concentration for micelle formation, since sorption depends on the nature of the substrate as well as on the properties of the solute in solution which alone determine micelle formation. Indeed, the fact that the onset of increased adsorption, point B in fig. 2, occurs at a concentration one tenth the critical value for micelles might imply that micelle formation does not have an influence. Interestingly enough, the data may be handled by the methods used for multilayer adsorption of gases on surfaces. Thus, if the amount adsorbed is plotted versus concentration, a sigmoid type curve is obtained, similar in form to a so-called Type I1 isotherm13 generally attributed to multimolecular adsorption. A monolayer value of about 0.12 mg per g may be estimated from the knee of this isotherm. On the other hand, if a plot is made according to the multilayer gas equation for adsorption to an unrestricted number of layers, eq 38,13 assuming the critical micelle concentration as the saturation concentration, the data above 120 mg per liter fall on a straight line from which a monolayer adsorption of 0.3 mg per g results. These considerations suggest that the monolayer may occupy an area somewhat less than the geometric value of 0.4 mg per g, and that micelle formation may indeed be a factor in the adsorption. the angle between the solid-liquid and liquid-gas interfaces, measured through the liquid. The value of the equilibrium contact-angle is uniquely determined by the value of the interfacial energies of the three intersecting interfaces and is independent of other forces in the system. When the liquid-gas interface intersects the solid at an edge—as was the case for all the experiments reported in this paper—the orientation of the solid-liquid interface is indeterminate or varies through 90" for a right-angle edge. Mr. Morris has called the angle between the horizontal and the liquid-gas interface for this edge condition a "static contact-angle." I feel that this term is unnecessarily misleading. In the first place, "static contact-angle" sounds too much like "equilibrium contact-angle." In the second place, the magnitude of the "static contact-angle," which I would prefer to call the "supporting angle," is determined by the forces in the system other than those derived from the interfacial energies, hence "contact angle" is misleading. If Mr. Morris had said that the "supporting-angle" is variable and depends on the weight of the particle and size of the bubble and that it has a maximum possible value equal to the equilibrium contact-angle, his discussion would have been more accurate. T. M. Morris (author's reply)—Mr. Kellogg puts forth a reasonable criticism of some of the terminology used in the paper. I agree that the term "static contact angle" may be misleading. Substitution of the term "supporting angle" or "vector angle" may be more suitable. F. X. Tartaron—In this paper the author presents a very interesting mathematical development of the forces present when a mineral particle adheres to an air bubble. Excellent concordance is obtained between mathematical formulation and experimental results. It is the writer's understanding that when the mineral surface presented to an air bubble is greater than the area of contact, the maximum contact angle is obtained. However, this contact angle represents distortion of the bubble, the normal shape of which is spherical or in cross-section, circular. This distortion produces a force that acts in opposition to the force of adhesion between the bubble and particle. Hence, at maximum contact angle, the force of adhesion between bubble and particle is at a minimum for static conditions. However, when the size of bubble is increased, the size of particle remaining the same (and all other conditions remaining the same), the contact angle decreases, the distortion of the bubble decreases and the force in opposition to adherence of bubble and particle also decreases. Thus, there is stronger attachment between bubble and particle. When this situation is applied to actual flotation conditions, it is doubtful that it has any significance. The reason is that the bubbles are normally so much larger than the particles, that in substantially all cases, it is probable that negligible distortion of the bubble takes place. In table IV, the author makes computations for bubbles from 0.50 to 2 mm diam. This is from 0.02 in. to 0.08 in. Certainly the bubbles generated in a flotation machine are far larger than this. The surfaces of the author's bubbles range from 0.79 to 12.6 sq mm. The area of contact of the glass rod (0.15 mm diam) is 0.017 sq mm. Thus, ratio of bubble surface to mineral area of contact ranges from 47 to 741 in round numbers. If we take a %-in. diam bubble and a 65-mesh (0.208 mm) particle of cubical shape, the ratio of bubble surface to mineral area of contact is 2931. Mineral particles do not readily become attached to air bubbles. Taggart has shown that in pneumatic flotation machines collector-coated particles are only temporarily attached to bubbles. They keep falling off and down in the froth but at a delayed rate as compared with gangue. Spedden and Hannan's motion pictures confirm the difficulty of attaching particles to air bubbles. In the agitation froth process, according to Taggart, air is precipitated from the water selectively on to the collector-coated particles and these

Jan 1, 1951