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By H. J. Hand

Statistical methods are becoming increasingly important for interpreting routine reports, or for analyzing special test data in industrial plants, such as steel plants. They have already become practically a necessity to the plant metallurgist. A paper by Chancellor, 1 written in 1933, gives many examples of the benefits the plant metallurgist can derive from the use of these methods. The present paper discusses applications of importance to many others who must analyze reports in the steel plant, as well as other examples of interest to metallurgists. Statistical Methods Logically Suited to Plant Problems.—Statistical methods are not new as a branch of mathematics. Until comparatively recently, however, practical applications were confined mainly to actuarial science, biology, and economics; fields in which an observed result is obviously influenced (and often determined) by a complicated set of variables more or less constantly tending to affect it. As pointed out by Daeves,2 a decade or more ago, problems in industry are basically similar to those in these other fields in that a given result is at least partly due to that chance combination of causes happening to be present at the time. When trying to do the same thing repeatedly, constant results are never attained; they vary about the desired result with more or less well defined mathematical regularity. Such a condition arises out of the great number of factors tending to affect the final result. If statistical methods are so valuable to the biologist or economist, why then should they not also be of great value to plant managers and engineers, and to all who must interpret reports from various sources in the industrial plant? Within the last few years, industry has become conscious of this situation, and the use of these methods has been rapidly expanding in such p1ants. Many Useful Statistical Devices Available.—Many statistical methods of attack are available for the analysis of plant data. It is the object of

Jan 1, 1938

By Jasinder S. Jaspal, John A. Reeves, Bradley J. Bourquin

INTRODUCTION The United States has an abundance of coal reserves in thick seams. Most of these resources are in the West. Surface mining operations in thick seams are highly efficient, particularly in the West, but methods for mining thick seams underground are very limited. The percentage of resource recovery in deep mining of thick seams is often as low as 30 percent. It is estimated that there are 45 billion tons of coal reserves for underground mining in seams greater than 10-ft thick in the western states alone. With such a large available reserve base and low rates of recovery, the need to develop the technology to mine these thick reserves is quite evident. As the definition of a thick seam varies widely from country to country, a thick seam is defined here as any seam where the height is such that it is not minable in a single pass with available mining equipment.

Jan 1, 1981

By Virgil Kirkham

NORTH AMERICA has for many years led the world in phosphate production, but with development of African deposits and their marketing conditions with respect to European countries, this leadership will shortly pass to Africa. Algeria, Egypt, Tunis, and Morocco have large phosphate reserves and a correspondingly large production because of easy mining and a ready European market, which was developed during the war. An increase in home consumption is destined to develop for the eastern American fields, and the countries of the Pacific will provide a market for the western producers. New processes indicate a decrease in fertilizer costs, which will encourage a more widespread domestic use and assure better marketing conditions. The African deposits, although benefited by a water haul, have the disadvantage of being isolated from a source of acid so that the crude rock is shipped from Africa to its destination, whereas in the United States the chief product shipped is acidulated rock or various types of superphosphatic fertilizers. The principal types of phosphate deposits used in the manufacture of fertilizers are guanos, apatite, phosphatic marl, phosphatic limestone, phosphatic shale, and phosphate rock which is also known as phosphorite. Some of these deposits are found on each of the continents; Table 1 gives their occurrence, age, location, character, extent, etc. Most of , the information found in this table represents a compilation of information published elsewhere in a different form and widely scattered.

Jan 1, 1925

Prior to any detailed discussion, I'd like to say that Dr. Aplan has made direct hits on two important considerations: 1) The most demanding need in Fine Coal research is to develop improved methods of sulfur reduction. 2) The areas of particle (impurity) liberation and froth flotation hold real near-term promise as techniques for improved sulfur removal. Digressing for a moment, I thin kwe can all remember the time when the biggest problem facing coal research was simply defined - "No money!" In the mid 70's we suddenly found ourselves dealing with a product worth five to seven times the value it carried in the mid60's. All of a sudden, we're talking about a high-profile, high- value commodity. The coal industry still hasn't made the complete psychological adjustment - especially in the operating areas (prep plants included). We have a valuable material at hand which is, in' many cases still being processed as though it were a two or three dollar per ton item. Simply put, I think that while the industry has made some major strides during this transition, a stronger commitment of attitude (and finances) needs to be made toward deeper definition of beneficiation work. Back to specifics - Dr. Aplan has really highlighted three areas where strong research efforts are needed. 1) Liberation processes - not limited to mechanical comminution - must be more fully studied.The industry certainly needs a better handle on value returned (improved ability to beneficiate) for dollars spent on improved liberation. 2) Flotation processes probably hold the most promise for near- term improvement in fine coal beneficiation technology. Dr. Aplan’s.

Jan 1, 1979

By Percy A. Robbins

The central power-station of the De Beers Consolidated Mines, Ltd., was designed and built under my supervision about five years ago. Since no detailed description of this plant has ever appeared, it may possess sufficient interest to arrant its publication, even at this late date. Although some additions may have been made to the plant, the following account, prepared from my notes, and accurate up to May, 1905 (at which time I severed my connection with the De Beers Company), will, I think, be found substantially correct. Certain local conditions governing the design of this plant should be stated first. IT. General Considerations. The climate is hot and dry. The region around Kimberley is arid and water is very scarce. The supply obtained from the mines contains so much material in solution that it is unfit for use in boilers or condensers (although tests recently made with a water-softening plant, built by Hans Reisert, of Germany, would indicate that water thus treated is suitable for boilers). And the amount of water required for concentrating about 30,000 tons of ore per day is so large that the question of adequate water-supply for this power-station had to be carefully considered. The rainy season extends from December to April, and the rainfall averages about 15 in. per year. Droughts are frequent; and in some years there is scarcely any rain at all.

Jan 1, 1909

By J. Lemish

Considerable research has been conducted in Iowa in recent years on carbonate aggregate reactions in concrete. Groups outside the state have become active in the past few years after recognizing that certain carbonate aggregates are reactive in concrete. The paper reviews the nature and extent of the problem and a summary is given of research by the author and his associates. In recent years considerable research has been conducted in Iowa on carbonate aggregate reactions in concrete. The research is part of a general study on the behavior of carbonate rocks as concrete aggregates sponsored by the Iowa State Highway Commission. Research on carbonate aggregates has not been extensive in the past. Laughlin1 published one of the first papers on carbonate aggregates in 1928 and was followed by others, notably H. S. sweet,' B. Mather et al.,3 and K. Mather4 who emphasized the petrographic and physical aspects of carbonate aggregates. The recognition that certain carbonate aggregates are reactive in concrete has led to increased participation in research in the past few years by groups outside of Iowa. Significant contributions have been made by Swenson and Gillot,5 Hadley,6 and Chaiken and Halstead7 in work which emphasizes the expansion of carbonate rocks in alkaline environments and the reaction of carbonate minerals or dedolomitization with alkalies. It is the purpose of this paper to review briefly the nature and extent of the problem and present a summary of the research by the author and his associates. EXTENT AND NATURE OF THE PROBLEM The problem is the deleterious behavior of certain carbonate aggregates in concrete. It was first recognized in Iowa over 20 years ago when poor service records of certain highways were correlated with aggregates produced from the Glory and LeGrand quarries. Deleterious behavior of carbonate aggregates have been reported in Canada and, more recently, in New York and Virginia. As more knowledge is gained concerning the problem, distress in concrete related to carbonate aggregates may be recognized over a widespread area. The problem may potentially exist in the Midwest, the Northeast, and other parts of the country underlain by thick sections of carbonate rocks readily available for utilization as aggregates. The nature of distress in Iowa highways is a general weakening and deterioration of concrete characterized by progressive cracking and spalling away from joints and edges (Fig. 1). The distress generally occurs after 15 years of service and becomes progressively worse. Specimens of such concrete lack the toughness of sound concrete and break easily under the hammer in the manner of a soft brick. The matrix is generally highly carbonated and dark borders, or reaction shells or rims outline the argillaceous carbonate aggregate fragments (Fig. 2). Cracks observed in cores cut across the aggregates and concrete matrix. Although localized volume change (expansion) is associated with spalling, there is no definite field evidence in Iowa that excessive growth of concrete slabs has occurred. The experience with carbonate aggregates in Iowa indicates that the concrete deterioration is not the same as that induced by the alkali-aggregate reaction associated with siliceous aggregates. The principal difference is that in Iowa the distressed concrete is weakened throughout the slab. In concrete affected by the alkali aggregate reaction, the

Jan 1, 1961

By R. J. Fruehan

The oxygen activity and concentration were measured in Fe-Cr-0 melts in equilibrium with an oxide phase at 1600°C (2912°F). The activity was determined by ,use of the following solid oxide -electrolyte galvanic cell CY-Cr8,(s) I ZrOz(CaO) I Fe-CY-G(saturated)(l) The oxygen concentration decreases with increasing Cr concentration to about 270 ppm 0 at about 7pct CY and then increases gradually. The activity coefficient of oxygen (fo) decreases with increasing Cr. In melts containing up to about 20 pct Cr, log f is approximately a linear function of wt pct Cr with a slope (e q 2) of —0.037. The activity of chromium was calculated and found to exhibit a small negative deviation from Raoult's law. From the activity and solubility data for low chromium melts, the free energy of formation of chromite, FeCr204, was found to be -79.8kcal per mole where pure liquid chromium and oxygen at I wt pct in Fe are the standard states. ThE effect of chromium on the chemical behavior of dissolved oxygen in liquid iron is of great importance in controlling the deoxidation of steels containing a significant amount of chromium. Chen and chipman' equilibrated Fe-Cr melts in the presence and absence of slag with hydrogen-water vapor mixtures. They concluded that at 1595°C chromite was the oxide phase in equilibrium with Fe-Cr alloys containing less than 5.5 pct Cr while at higher chromium concentration Cr,O, was the stable phase. In the composition range 0 to 10 pct Cr they found that the interaction coefficient, was equal to -0.041. Turk-dogan,' Schenck and Steinmetz,, and pargeter4 measured egr) in a similar manner and found the value to be -0.064,-0.04, and -0.052, respectively. McLean and Be11 evaluated egr) from their data on the equilibrium of Fe-Cr-Al-0 alloys with H2/H20 mixtures and found it to be -0.058. However, McLean and Bell's value should only be considered an estimate because the effect of aluminum on the activity coefficient of oxygen is about a hundred times greater than that of chromium. Consequently, an error in the value of egl) used, which at the present time is not well-known, or an error in aluminum analysis, which is present in very small quantities, will result in a significant error in egr). Fischer et a1.6 determined the interaction coefficient (eEr) in Fe-Cr-0 melts not in equilibrium with an oxide phase and containing less than 18 wt pct Cr at 1600°C electrochemically. They determined a value of -0.031 for egr). Hilty et aL7 measured the oxygen content of Fe-Cr melts in equilibrium with an oxide phase containing up to 50 pct Cr. They found that the solubility of oxygen decreased as the chromium content increased to about 6 pct Cr and then increased gradually. They concluded that the equilibrium oxide phase was chromite below 3 pct Cr, distorted spinel from 3 to 9 pct Cr, and Cr,04 above 9 pct Cr. Adachi and lwamotoa also investigated this system, but did not find Cr30,. They X-rayed the equilibrium oxide phases and did not find the presence of Cr,O,. They also X-rayed the oxide phase extracted from a 65 pct Cr melt which was heat treated and did not find metallic chromium as would be expected if Cr3O4 were the equilibrium oxide phase as indicated by the reaction : 3Cr3O4 — 4Cr2O:, + Cr [lj It was the purpose of the present investigation to determine the effect of chromium on the activity coefficient of oxygen in Fe-Cr melts by measuring the activity and solubility of oxygen equilibrated with an oxide phase in the composition range 0.18 to 50.5 wt pct Cr at 1600°C (2912°F). The activity of oxygen in the melts was determined by use of the following galvanic cell: The relationship between the partial pressure of oxygen in equilibrium with the melt and the reversible electromotive force of the cell (E) is where 11 = 4, F is the Faraday constant, pb, is the oxygen pressure in equilibrium with the meit and is the oxygen pressure in equilibrium with Cr203 as determined from the free energy data compiled by Elliott et al? The oxide phase in equilibrium with pure chromium was assumed to be Cr If Cr30, were the equilibrium phase the activities derived would be approximately the same, since the best estimated free energy of formation of Cr,O,, if it does exist, is approximately % the free energy of formation of The activity of chromium in Fe-Cr alloys at 1600° C was also determined from the measured electromotive force. The activity of chromium (aCr) is related to the electromotive force as follows: , The oxide phase in equilibrium with pure chromium and Fe-Cr melts from 10 to 52 pct is assumed to be Cr203 so that n equals three. If future work proves the existence of Crs04 in equilibrium with Fe-Cr melts and pure chromium, the experimental results can be reevaluated using a value of $ for n in Eq. 141. A value of ^ for n will make the activities about 10 pct higher. In order for Eqs. 131 and [4J to be valid the electrolyte, ZrOa(CaO), must exhibit predominantly ionic conduction at the temperature and oxygen partial pressure of its use. Previous work1' has demonstrated that ZrOz(Ca0) is predonlinantly an ionic conductor

Jan 1, 1970

By E. G. Leonardon

THE object of this paper is to describe briefly the practical results obtained in several problems of civil engineering by resistivity measurements of the underground. It is intended for the mining engineer, as well as for the construction engineer; the stratigraphical problems discussed are general and frequently are encountered in mining exploration. Resistivity measurements have been used in mining and oil exploration for a number of years.1 Their introduction in the field of civil engineering, on the contrary, is rather recent. It was applied for the first time in the spring of 1928 near Littleton, N. H., in the survey of two dam sites for the New England Power Assn .2 Since then, the geophysical firm with which the author is connected has had an opportunity to develop this field of activity, and more than 20 investigations at dam and tunnel sites have been carried out in the United States and Canada. A part of this work has been verified by underground or drilling exploration. This paper deals with but a few of the results, which we are permitted to make public now. The theoretical and technical sides of the processes employed will not be discussed; they have already been described in various technical. .publications. A few general points will be mentioned, to make clear the practical examples given.

Jan 1, 1931

By Louis Ware

At the beginning of the present war, the United States faced the need to multiply its production of magnesium metal almost roo times within the shortest possible period. Urgently needed for construction of military aircraft, incendiary bombs, and other war uses, magnesium was at the top of the list of critical war materials. Up to that time only one Producer, employing Only One process and using One raw material in a single plant, represented this country's entire Production capacity. It was immediately desirable to plan a numher of plants located strategically over the Count'Y and to expand an industry more rapidly and to a greater extent than ever before had been attempted in so short a time. In '939 this American producer, the Dow Chemical .9 was making about 7 million Pounds of magnesium metal. It utilized as a raw material brine containing magnesium chloride, which was pumped from wells in Michigan. The logical ap-preach to certain increased production was to employ the same process on the same raw material in other sections of the United States. In Europe and other countries, different processes had been used and different raw materials were being utilized, but all of the skill and knowledge for production in this country was that of using the Dow type of cell and magnesium chloride as a raw material. The Government was testing other processes, but none then had been proved commercially feasible. Development OF New Process The International Minerals and Chemical Corporation had available a large quantity of magnesium ,chloride at Carls-bad, New Mexico, contained in the end liquor produced from its potash plant sillce the buildng of the plant in 1941 It was the only company mining commercially a magnesium ore and having anything like this quantity of magnesium chloride liquor. The magnesium ore, langbeinite, was being mined from the 800-ft. level for its content of potassium sulphate. This ore, a potassium magnesium sulphate, was reacted in a base exchange plant with potassium chloride to produce potassium sulphate, the discharge liquor having a high content of magnesium chloride. Three potash-producing companies are in the Carlsbad area, but only International has developed and is commercially producing the potash-magnesium ores. The lower, or No. 4, veil, in that area is potassium chloride ore, and is continuous through all the properties. The langbeinite, or No. 2, vein is minable at the International property, but occurs sparsely, if - at in other areas being mined in that vicinity. It is understood that most of the mag. nesium produced] by Germany comes from magnesium and magnesium-potassium ores obtained from potash mines. It was logical for International to pro-pose to make available this magnesium material and to offer its technical staff to design, construct and manage a magnesium plant for the account of the Government. The plan that finally was adopted by the

Jan 1, 1944

By Oscar Aguilar, Jin-ichi Nakamura, Kazuo Nakamura

Michiquillay deposit is porphyry copper type with over 500 million tons of 0.70% Cu ore. In order to reflect the true nature of the orebody as to shape and value distribution and to compensate for insufficient data in the outer perimeter and lower portion, "Triangular Interpolation Method" is used in the computation, wherein block grades are determined by "Plane Regression". The results thus obtained are compared with the data from additional investigation and are found to match well with each other. Aside of total Cu, assays of Fe, S, MoS2 and geological data such as alterations, rock types, faults, mineralogical compositions are also stored in the computer. By this system, their distribution and relation to alteration become clear and classification of ore into types affecting recovery become possible. The outputs of this system make clear the characteristics of the orebody and furnish valuable geological data on the orebody.

Jan 1, 1976

By J. B. NEALEY

THE common method of shale mining, drilling, shooting and steam-shovel loading, is fast giving place to a comparatively new method which is purely mechanical. This machine is known as the shale planer and takes a cut from a very large face, 50 ft. or more in height. As shale deposits are usually stratified, the quality varying with the stratification, a very uniform product is obtained with this planer, for its "cut" is across the entire face, vertically. This planer was designed and built some 15 years ago by J. M. Powell, president of the Indiana Drain Tile Co., Brooklyn, Ind. Unevenness in mixing the material from the different layers in the shale deposit of this company was causing considerable fluctuation in the firing- shrinkage and color of the ware produced, thus lowering the quality. Some method of maintaining a uniform proportion was vital and this planer was therefore devised. Its capacity was approximately 175 tons daily: cut, mixed and loaded.

Jan 1, 1929

By L. L. Gray, D. W. Reed, F. Morgan

A flowMeter has been developed at Gulf Research and Development Co. and tested in the field for measuring the flow of gas in well bores. It has been used in a study of the injection capacity of different horizons in gas injection wells in Oklahoma. The flow sensitive element of the meter is a semi-conductor having a very high temperature coefficient of resistance. Advantages possessed by this meter are the result of that property and the high specific resistance of the element. The instrument possesses a sensitivity considerably higher than any reported previously. In the application described here the element is heated to a temperature considerably above ambient by an electric current, which is supplied by a voltage source at the surface. When fluid flows through the meter the rate of dissipation of heat is increased and the temperature of the element decreases. Because of the negative temperature characteristics of the resistance element such a decrease of temperature will be accompanied by an increase of resistance which, under flow conditions ordinarily found in wells, is of such a magnitude that it can be directly measured or recorded in terms of a change in voltage at the surface. In practice, rate of flow is measured in terms of the drop in voltage in the resistance element. All the metering and control apparatus remains at the surface while the thermal element is lowered into the well on a single conductor cable, consisting of an insulated wire and sheath. The meter is calibrated by passing known quantities of gas through it either at the surface or in the hole at a point immediately above the region in which gas is lost to the formation. In case calibration is made at the surface, the ambient temperature in the hole may readily be obtained by a second resistance element which is operated at a current so low that effectively no heating occurs. The instrument has been adapted to con-tinuous recording, but the velocity of the meter relative to that of the gas must be low unless corrections are made. Curves giving data obtained in actual field tests are shown' The meter can also be used to determine the distribution of flow capacity in a gas producing well. A differential form of the meter has been designed and built in which the local flow or injection capacity of the formation is obtained directly. Introduction When fluid is injected into a well in a secondary recovery or pressure-maintenance operation the question of its most effective use invariably arises. Although the core log, when available, will show the regions of good permeability and oil saturation, there is normally no assurance that the fluid actually enters the formation in zones where injection is deemed desirable. In view of the uncertainties involved in such programs, it is generally conceded that measurements of permeability for a formation in place are more significant than those obtained by the core-sampling technique. A subsurface meter has been developed at the Gulf Research and Development Co. for measuring flow of fluids at different horizons in a well bore, and field tests have been made on the instrument in Cooperation with the Tulsa Division of the Gulf Oil Corp. In this paper the meter is de-

Jan 1, 1948

By F. Morgan, L. L. Gray, D. W. Reed

A flowMeter has been developed at Gulf Research and Development Co. and tested in the field for measuring the flow of gas in well bores. It has been used in a study of the injection capacity of different horizons in gas injection wells in Oklahoma. The flow sensitive element of the meter is a semi-conductor having a very high temperature coefficient of resistance. Advantages possessed by this meter are the result of that property and the high specific resistance of the element. The instrument possesses a sensitivity considerably higher than any reported previously. In the application described here the element is heated to a temperature considerably above ambient by an electric current, which is supplied by a voltage source at the surface. When fluid flows through the meter the rate of dissipation of heat is increased and the temperature of the element decreases. Because of the negative temperature characteristics of the resistance element such a decrease of temperature will be accompanied by an increase of resistance which, under flow conditions ordinarily found in wells, is of such a magnitude that it can be directly measured or recorded in terms of a change in voltage at the surface. In practice, rate of flow is measured in terms of the drop in voltage in the resistance element. All the metering and control apparatus remains at the surface while the thermal element is lowered into the well on a single conductor cable, consisting of an insulated wire and sheath. The meter is calibrated by passing known quantities of gas through it either at the surface or in the hole at a point immediately above the region in which gas is lost to the formation. In case calibration is made at the surface, the ambient temperature in the hole may readily be obtained by a second resistance element which is operated at a current so low that effectively no heating occurs. The instrument has been adapted to con-tinuous recording, but the velocity of the meter relative to that of the gas must be low unless corrections are made. Curves giving data obtained in actual field tests are shown' The meter can also be used to determine the distribution of flow capacity in a gas producing well. A differential form of the meter has been designed and built in which the local flow or injection capacity of the formation is obtained directly. Introduction When fluid is injected into a well in a secondary recovery or pressure-maintenance operation the question of its most effective use invariably arises. Although the core log, when available, will show the regions of good permeability and oil saturation, there is normally no assurance that the fluid actually enters the formation in zones where injection is deemed desirable. In view of the uncertainties involved in such programs, it is generally conceded that measurements of permeability for a formation in place are more significant than those obtained by the core-sampling technique. A subsurface meter has been developed at the Gulf Research and Development Co. for measuring flow of fluids at different horizons in a well bore, and field tests have been made on the instrument in Cooperation with the Tulsa Division of the Gulf Oil Corp. In this paper the meter is de-

Jan 1, 1948

By K. R. Waugh, Barbara S. Brown, D. W. James

AN electronic data-processing system is described which permits rapid, accurate, low-cost processing of strain-dependent damping data utilizing equipment normally available within the service facilities of most large laboratories. On analyzing the record of a stress-dependent damping test, the operator usually measures the double amplitudes at several points on the decay curve. The logarithmic decrement is then calculated for decay between consecutive amplitudes. These values of 6 are plotted against the corresponding maximum surface shear stress, T, which is proportional to the average of the two amplitudes between which is calculated: where d is the specimen diameter. The period of the vibration is not necessarily constant during decay; thus, each cycle must be counted. A decay curve may extend to, perhaps, 1000 cycles, and at least two curves are always obtained for each specimen or set of conditions. It can, therefore, be seen that manual analysis of decay curves is both tedious and costly in terms of man-hours. Furthermore, the resolution of the record is often such that accurate measurement of amplitude is extremely dif-

Jan 1, 1969

Three years ago, when Sun Energy Development Co. (Sunedo) dedicated its Cordero mine in Wyoming, the company noted that its decision to venture into the coal industry was prompted by the need for domestic energy self-sufficiency. Now, as the energy situation assumes crisis proportions and the cry For coal intensifies, Sunedoo has begun a $21 million expansion program that will double the mine's productive capacity by the mid-1980s. When the Cordero come was originally conceived, Sunedoo obtained permission from permitting authorities to produce up to 11 million t/y (12 million stpy) of coal. But seeing opportunities in the coal market, Sunedoo returned to the agencies in 1976 and came away with permission to produce 22 million t/y (24 million stpy). Of that total permitted capacity, Cordero is expected to produce about 3.6 million tons (4 million st) this year.

Jan 9, 1979

By R. J. Brison, R. D. MacDonald

This chapter is written primarily from the standpoint of development of flotation processes for treatment of specific ores. However, most of the principles and techniques discussed are equally applicable to other forms of applied flotation research such as improvement of procedures in existing plants and development of new reagents or methods without reference to specific ores. Because it is not possible to cover this subject in detail here, much of the material presented is in the form of a guide to the literature, with emphasis on readily available, English language publications. Details are included only if considered to be widely applicable or not readily accessible in the literature. Related subjects which are covered elsewhere in this volume, such as flowsheet design and statistical techniques, are not emphasized in this chapter. The material presented is intended primarily for those familiar with the theory and practice of flotation, but with limited experience in applied flotation research. It may be of value to the experienced investigator as well, by calling to his attention some useful viewpoints or techniques that he may have overlooked. It has often been said that flotation is more of an art than a science. In- deed much of the knowledge of flotation behavior is empirical. However, the unsystematic, artisan approach to flotation problems results only in an ac- cumulation of unrelated data. Like any other physical or chemical process, flotation is amenable to investigation by systematic experimental methods. The experiments should be based, as far as possible, on an understanding of the natural laws that govern the process and on good experimental procedures. SAMPLING OF A DEPOSIT In working out a flotation process for a mineral deposit, no step is more important than that of obtaining a suitable sample or samples. Experimental procedures cannot compensate for the lack of a representative sample. Methods of sampling a deposit have been published elsewhere,l-4 but a few points are of special importance from the standpoint of flotation. First, the sample should be representative of the deposit, not only in respect to chemical composition, but also in respect to mineralogical composition and degree of dissemination of the valuable minerals. To help ensure

Jan 1, 1962

The research project on size reduction, sponsored by the mining industry through financial support from individual companies, is now embarking on a second three-year program. The first 3-year program had as its objectives assimilation of the literature on comminution and development of simulation programs encompassing the basic mechanisms of grinding. This involved investigating conditions under which a particle in a mill is captured, the stress to which it is subjected, its break probability, and the resulting particle size distributions. The results were used to obtain the most representative simulation models based on current knowledge of mechanisms. As part of this work a set of computer programs has been developed for the following cases: . Batch mill, by numerical integration for completely general selection and breakage functions. . Continuous open-circuit mill by same method as above. . Continuous open-circuit mill by general numerical integration method, including transient behavior

Jan 1, 1969

By P. K. Foh, C. G. Dunn

IN an investigation of the rolling and recrystalliz-ing textures obtained from single crystals of Si-Fe, Koh and Dunn included specimens in the (111) [lie] orientation.1,2 This note reports some additional results obtained on samples of this orientation set aside for further study. After, primary recrystallization longer annealing treatments at 980°C produced only normal grain growth; after 16 hr at 980°C the largest grains were approximately 0.010 to 0.020 in. in diam. The orientations of 13 of the larger grains were found by the transmission Laue method. The unidentified (110) poles of these grains have been added to the (110) pole figure obtained after primary recrystallization2 to give the plot shown in Fig. 1. When grain identifications are also included, such a plot reveals the following. Two orientations agree almost exactly with the peak pole ,density positions of component B of the primary recrystallization texture, one with component A, and one with component C. All the remaining orientations except one have (110) poles near weaker and unidentified pole density peaks. In fact, the correlation is good enough for an identification of eight components. Previously only components A, B, and C were certain. The results are perhaps even more informative when combined with the (110) pole figure of the cold-rolled crystal to give the plot shown in Fig. 2. Each of the 13 orientations is identified and uniquely determined by selecting two (110) poles per crystal, which are 90" apart. The plot shows that every grain of the 13, except grain 6, has a (110) pole in common with a (110) pole concentration of the cold-rolled crystal. The orientation relationship with the cold-rolled orientation may be expressed as approximately 25" rotations about <110> axes, which is in agreement with the results found for coarse-grained primary recrystallization.2 If primary recrystallization had occurred according to the <110> rule without preference, there would have been 12 components. Actually our limited data reveals nine of the possible 12. The integrated pole figure also shows preferences among them, since three are considerably stronger than the rest. In addition to the above direct information, the following conclusions may be drawn. Primary recrystallization of the (111) [110] cold-rolled crystal produces a limited number of weak and strong components with the larger than average primary grains from these components related to the cold-rolled crystal by 25° <110> relationships. In arriving at this conclusion of limited orientations the (111) [110] orientation has to be ruled out as a source of large primaries for two reasons. First, growth in this orientation was not observed, despite an expected high grain boundary mobility (due to its 25" <110> relationship with every component of the texture). Secondly, primary recrystallization usually produces grains in new orientations, particularly in a single orientation matrix; but (111) [110] is not new. Other orientations besides those of the <110> type may be considered unlikely, of course, because the <110> relationship holds quite well for primary recrystallization2 and should produce the large primaries. There are exceptions to this rule, but probably not enough to provide large

Jan 1, 1958

By R. W. Raymond

ChaRles William HenRy Kirchhoff was born March 28, 1853, at San Francisco, Cal., where his father, Charles Kirchhoff, was at that time consul for his native country, Germany. A few years later, the family moved&apos; to Hoboken, K. J., in which city the son received his preliminary education at the Hoboken Academy, proceeding later to Germany, where he was graduated in 1874 as mining engineer and metallurgist at the Prussian Royal Mining Academy of Clausthal, in the Harz. Upon his return to the United States, he became chemist of the Delaware Lead Refinery at Philadelphia, and retained that position for three years. But in 1877 he began what was to be an almost uninterrupted life-long association with David Williams, the publisher of The Iron Age, of New York, who established in that year, and continued for a brief period, a journal entitled the Metallurgical Review, on the editorial staff of which Mr. Kirchhoff received a place. The enterprise was doubtless an attempt to cover a wide metallurgical field outside of that which properly belonged to The Iron Age. But it was soon abandoned, and Mr. Williams wisely concentrated his energies upon the older journal, which, under his vigorous and skillful management, and the labors of the able editors and correspondents whom he selected, became one of the greatest institutions of its class in the world. From 1878 to 1881, Mr. Kirchhoff was assistant editor of The Iron Age. From 1881 to 1884, he was managing editor of the Engineering and Mining Journal; in 1884 he returned to The Iron Age, to become for five years its associate editor, and in 1889, on the retirement of James C. Bayles, editor-in-chief. This list of dates and employments, without further comment, sufficiently indicates, at least to the eye of an expert, that Mr. Kirchhoff had found his congenial career in trade journalism. His qualifications for this profession were somewhat exceptional. He possessed the scientific training, the knowledge of foreign languages and literatures, and the power of making and keeping friends, which enabled him to get early notice of technical novelties; he had the taste for statistics which made him both industrious and intelligent in their collection and use; and to these traits he added a mastery of the meaning of such accumulated data, and a sane, critical judgment of the situations which they represented, as well as of the sources and the figures themselves, which made his opinion weighty

Jan 1, 1917

By FREDERICK LAISY

A NUMBER of new plants for the treatment of copper ores were completed or under construction during the year. Among these may be mentioned the plants of the International Nickel Co., those of the Hudson Bay Mining and Smelting Co. and of the Roan Antelope Copper Co. Three copper re- fineries have been constructed, one at El Paso, Tex., and the other two in Canada. Two more are projected, one in France and one in England. The International Nickel Co.&apos;s plant consists of an 8000-ton concentrator and a smelting plant containing thirty 10-hearth Herreshoff roasting furnaces, five reverberatory furnaces, and eight Smith-Pierce converter5 . The smelting plant is estimated to have a capacity of 5000 tons of ore or concentrate per day. The roasters are superimposed on the reverbratory furnace plant. As a consequence of this arrangement, the furnace building is unusually high. being 183 ft. from yard level to highest roof elevation.

Jan 1, 1931