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To THE BOARD OF DIRECTORS AND MEMBERS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS. GENTLEMEN Like every other significant activity in the United States today, the work of the Institute has been affected by and adjusted to the prosecution of war against Germany, .Japan and their satellites. As the elaborate engines and materiel of modern mobile warfare are made, for the most part, of metals and other minerals; and are powered by mineral fuels, the industries -represented by the A.I.M.E. are of primary and vital importance. Of some 29 critical materials officially listed by the War Production Board, 24 are minerals. An alternate for one of the others, rated as a nonmineral, is to be made principally from petroleum. This alludes, of course, to rubber. The procurement of tremendous quantities of such raw materials and the effective processing, fabrication, and utilization of them depend on members of those branches of the engineering profession represented by the A.I.M.E.

Jan 1, 1943

PORPHYRY mining in the Bisbee district in Arizona did not begin until 1923, though Bisbee had been the scene of profitable copper-mining operations since 1880, and during the interval had contributed roughly 2,000,000,000 lb. of copper to the world's supply. At that time it ranked third among the copper districts of the United States, first place for total production going to Butte, Montana, and second to the district centering around Calumet, Michigan. Bisbee's production had come from the so-called "limestone" mines operated principally by the Phelps Dodge Corporation and the Calumet & Arizona Mining Co. Each of these companies had a large smelting plant at Douglas, 25 miles southeast of Bisbee on the Mexican border. The town of Douglas owed its existence primarily to the copper mines of Bisbee, the particular location having been determined, first, by the fact that water in adequate supply could be obtained by sinking wells; and, second, by its position about equally distant from Bisbee and the mines in Sonora, Mexico, of the Moctezuma Copper Co., a Phelps Dodge subsidiary. Three partners, Martin, Reilly, and Ballard, conducted the first operations of consequence at Bisbee about 1880; and in 1881 a smelting plant consisting of two 36 in. water-jacketed blast furnaces was erected near by. The ore came from open-cut workings on the later-to-be-famous Queen orebody. The furnace charge is said to have averaged 23 per cent copper-twice as rich as the concentrates from the mills and four times as rich as the smelting ore shipped from Bisbee in recent years. As early as 1881, disputes arose among owners of various claims, and groups of claims, over the ownership of orebodies under the law of apex and extra-lateral rights. This law gives a miner the right to follow his vein downward on its dip, even

Jan 1, 1933

By C. C. Nathan

Data are resented on the physical properties of five waxes obtained from fields in Texas and Louisiana in which "parafin" troubles are being experienced. The crude parafin was fractionated into three components, voluble in cold acetone, soluble in boiling acetone, and insoluble in boiling acetone. The acetone insoluble fraction was found to consist essentially of straight chain parafin hydrocarbons in the molecular weight range 525 to 700. Solubilities of the purified high molecular weight parafins were determined in a number of solvents. It was found that in hydrocarbon solvents, including crude oil, solubilities could be calculated satisfactorily by use of ideal solubility relations. In chlorinated, and oxygenated solvents, large deviations from ideal behavior were observed. These deviations could be partially correlated with the internal pressure of the solvent. INTRODUCTION A problem encountered in many producing oil fields is that of "paraffin" deposition. The problem refers to the deposition of material from the crude oil onto tubing, pumping rods, flow lines, or other material contacted by the crude. This problem has been recognized for nearly a hundred years, and numerous investigations have been reported on its causes and prevention or alleviation. One of the more comprehensive of such investigations was published by Reistle1 in 1932. A few of the salient findings of his report are briefly as follows: The term "paraffin" as used to describe this problem refers to the deposit of carbonaceous material which is not soluble or dispersible by the crude oil under the conditions where deposition occurs. The "paraffin" normally consists of high molecular weight paraffin hydrocarbons, both straight chain and branched, resins and asphaltic materials of undetermined nature, occluded oil and water, and possibly sand. In consistency, the deposit may vary from a soft, sticky material, to one which is hard and brittle. Deposits are usually black, although lighter colors are sometimes observed. Under the conditions of temperature, pressure, and crude oil composition occurring in the underground reservoir, the paraffin is in suspension or solution in the crude. As the oil flows to the surface, there is generally a reduction of temperature, pressure, and the amount of dissolved gases contained in the oil. Reduction of temperature and gas break-out were shown by Reistle to be factors causing reduced solubility of the paraffin in the crude. Thus, as the crude containing paraffin rises to the surface and flows to storage tanks at atmospheric temperature, the solubility of the paraffin may be exceeded. Deposition will begin at the point in the system where the temperature of the system falls below its cloud point, and continue as long as there is a further drop in the solution power of the crude for the paraffin. The severity of the deposition as well as the location of the bulk of the deposition, i.e., in subsurface or surface equipment, will depend on the amount of paraffin originally in the crude, the manner in which pressure and temperature of the crude

Jan 1, 1956

By C. S. Smith, E. W. Palmer

For several years an investigation has been in progress in the research laboratory of The American Brass Co. to determine the thermal and electrical conductivities of most copper alloys of commercial importance and several of scientific interest. This paper contains such data on the binary alloys of copper with silicon, aluminum, manganese and nickel, and on a large number of ternary or more complex alloys. Some interesting general relationships between the thermal and electrical conductivities for all copper alloys at all temperatures are pointed out. The data for the copper-zinc, copper-phosphorus and copper-tin binary systems have already been published1,2 † except for the electrical conductivity at 200" C., which is given in the appendix of this paper. Literature on Thermal Conductivity of Copper Alloys The papers referred to above contained a summary of the figures available in 1929 for the thermal conductivity of copper alloys. There is given in Table 1 herewith a selection of the data that have appeared since that time. The measurements of Hanson and Rogers3 are particularly interesting since they cover a series of alloys in the alpha solid solution range and show the effect of heat-treatment. Their alloys were tested as annealed castings, and are not therefore directly comparable to the worked alloys measured in the present investigation, although the difference is small. Bailey's determinations4 were carried out on the alloys used by Lees6 in 1906, and extend his results to higher temperatures. It is most unfortunate that the alloys were not analyzed, for the approximate compositions given are hardly sufficient identification of the material. It is equally to be regretted that neither Hanson and Rogers nor Bailey give data for the electrical conductivities of their samples. Sager6, using the heat-wave method of King, determined the thermal conductivity of copper, nickel and four alloys of the two metals. His results are included in Table 1.

Jan 1, 1935

By H. I-Lieh Huang, O. D. Sherby, J. E. Dorn

RECENT investigations1-4 have suggested that the total plastic strain, C, for high temperature creep under a given stress can be correlated by means of a temperature-compensated time, te- where t is the duration of test, e is the base of natural logarithms, aH is the activation energy for creep, R is the gas constant, and T is the absolute temperature. A typical set of data on which this deduction was based is given in Fig. la. Inasmuch as the e-in t curves for the various temperatures are identical except for their displacement along the In t axis where f and are appropriate functions. If the increase in creep rate with an increase in temperature is exclusively ascribable to a single process involv- ing thermal activation, (T) should equal RT and therefore it = constant [2] where ?= te Assuming the validity of this relationship, ? = ?2 at the same strain, or where the subscripts refer to two alternate test conditions.

Jan 1, 1957

By Glenn A. Marsh, George Bernard

It is often assumed that aerated oil field brines which are to be injected underground contain dissolved oxygen in amounts which will cause appreciable corrosion. Through the use of a new portable dissolved oxygen meter, accurate determinations were made at three brine conditioning plants. At two older plants, dissolved oxygen concentration in the final treated brine was found to he almost zero In spite of aeration during the conditioning process. At a new plant, dissolved oxygen was initially present but disappeared soon after the brine was "inoculated" with oxygen-free brine from one of the other plants. Corrosion tests at the two older plants have substantiated predictions that the brines would lint be corrosive. These results show that mechanical deaeration may not always be required in brine treating plants. INTRODUCTION The present work was undertaken to add to our knowledge of aeration and deaeration of oil field brines in brine conditioning plants. It is commonly assumed that brines which are exposed to the air soon become more or less saturated with dissolved oxygen. Since oxygen-containing brines are known to be corrosive, precautions are often taken to keep air out of brine through the use of closed systems or mechanical deaeration. The study of oxygen in brine has been seriously hampered in the past because of the lack of a suitable analytical tool. The standard Winkler method for the determination of dis-solved oxygen is satisfactory for use in fresh water, but not in many oil field brines. Corrections have to be made for a number of reducing substances such as ferrous iron and hydrogen sulfide which are commonly present in natural brines. Very often the correction factors are much greater in magnitude than the amounts of oxygen which are to be determined, and consequently erroneous results are obtained. Also. erratic Winkler data are obtained when appreciable concentrations of calcium and magnesium salts are present. The first step in carrying out a systematic study involved designing a portable dissolved oxygen apparatus which would operate in natural brines. Subsequently, this apparatus was used in three brine conditioning plants. Dissolved oxygen data obtained here, and certain corrosion rate data, illustrate the interesting behavior of oxygen in these oil field brines. APPARATUS A portable dissolved oxygen meter described in detail elsewhere,' was developed specifically for use with oil field brines. It is a polarographic apparatus employing a small rotating platinum electrode (cathode) and calomel reference electrode (anode). A potential of 0.7 volts is applied across the electrodes while they are immersed in the brine to be tested. 4References given at end of paper.

Jan 1, 1952

By Charles Goodale

THE principles and theory on which the U. S. mining law of 1872 was based are well understood, and have been discussed at great length by many writers. The papers by Dr. R. W. Raymond1 in the Transactions of the American Institute of Mining Engineers have covered the subject very fully, with explanations of practical results in many adjudicated cases. It is believed that the following instance of the application of the law in recent years will have some weight in a discussion of proposed changes in our mining laws. The litigation between the St. Louis Mining & Milling Co., and the Montana Mining Co., Ltd., a British corporation, over portions of the Drumlummon lode covered more than 20 years, and resulted in a judgment for damages in favor of the St. Louis Co. of such an amount that the Montana Co. declined to pay the judgment, and therefore lost the entire property. The Drumlummon lode claim in the Marysville district, Mont., was located in 1876 by Thomas Cruse. When he staked out his claim, he assumed that the discovery on the Drumlummon vein, and another showing of mineral about 200 ft. distant, were on the same vein, and the center line of the claim was given a course of N. 57'2'E. Development of the Drumlummon vein soon showed that its strike was about N. 15 E., and that the other outcrop was on the North Star lode; so it was inevitable that the Drumlummon vein would cross one or both side lines of the location, and the Montana Co. found it advisable to acquire adjoining claims on both sides of the Drumlummon, in order to avoid possible litigation over apex rights. They bought the Marble Heart, but would not purchase the Hopeful (see Figs. 1 and 2), at the terms proposed for the reason that exploration in the Cruse level had shown the vein to be barren in that region. The owners of the Hopeful were sinking an incline from that claim in 1889, and the Montana Co. enjoined them, contending

Jan 5, 1914

By C. S. Smith, E. W. Palmer

For several years an investigation has been in progress in the research laboratory of The American Brass Co. to determine the thermal and electrical conductivities of most copper alloys of commercial importance and several of scientific interest. This paper contains such data on the binary alloys of copper with silicon, aluminum, manganese and nickel, and on a large number of ternary or more complex alloys. Some interesting general relationships between the thermal and electrical conductivities for all copper alloys at all temperatures are pointed out. The data for the copper-zinc, copper-phosphorus and copper-tin binary systems have already been published1,2 † except for the electrical conductivity at 200" C., which is given in the appendix of this paper. Literature on Thermal Conductivity of Copper Alloys The papers referred to above contained a summary of the figures available in 1929 for the thermal conductivity of copper alloys. There is given in Table 1 herewith a selection of the data that have appeared since that time. The measurements of Hanson and Rogers3 are particularly interesting since they cover a series of alloys in the alpha solid solution range and show the effect of heat-treatment. Their alloys were tested as annealed castings, and are not therefore directly comparable to the worked alloys measured in the present investigation, although the difference is small. Bailey's determinations4 were carried out on the alloys used by Lees6 in 1906, and extend his results to higher temperatures. It is most unfortunate that the alloys were not analyzed, for the approximate compositions given are hardly sufficient identification of the material. It is equally to be regretted that neither Hanson and Rogers nor Bailey give data for the electrical conductivities of their samples. Sager6, using the heat-wave method of King, determined the thermal conductivity of copper, nickel and four alloys of the two metals. His results are included in Table 1.

Jan 1, 1935

By M. C. Leverett

THE dynamic behavior of a multiple fluid system is completely describable in terms of driving forces and resistances to flow. The latter are proportional to the vis-cosity of the fluid under consideration and inversely proportional to a property of the system termed the " effective permeability" to that fluid, a property therefore defined by this relation. Since three phases are usually present in oil reservoirs, it is essential to know the effective permeabilities to the several fluid phases, and the relationship between the composition of the fluid in the pore space and that of the flowing stream, in order to handle satisfactorily certain problems of oil production. In this regard, there are many unknown factors and parameters, and many that can be evaluated only indi-rectly. However, it is expected that work along lines similar to this present under-taking will help materially in solving these problems. Previous workers in this field have inves-tigated the two-phase systems, water-gas,1 water-oil2 in unconsolidated sands, and water-gas3 in consolidated sands. The ex-tension of the study of the flow of hetero-geneous fluid systems from two to three phases involved only slight changes in technique. The apparatus used in the present work, except for slight changes to be described, was that used by Leverett in his water-oil experiments.2 Correlation and interpretation of data were made by methods analogous to those used in two-phase work. The relative permeability to a phase-the effective permeability divided by the permeability of the system to a homogeneous fluid-was employed through-out in correlating the rate of flow of that phase with the composition of the pore space. Quantitative measurements of two inde-pendent physical properties of the system were required to determine the composition of the pore space. As in the two-phase work, the fraction of water was determined electrically. The gas fraction was deter-mined by measuring changes in volume accompanying measured pressure changes. Suitable account was taken of the solubility of the gas in the liquid phases, and of the vapor pressure of the water phase. Since this work was exploratory in nature, no attempt was made to obtain highly accu-rate numerical results. Reasonable precision and reproducibility were sought.

Jan 1, 1940

R. W. Guard (General Electric Co., Schenectady)— The method of fractional replication discussed by the author has proven very valuable to us in applied research connected with alloy and process development where many of the same experimental difficulties exist. Several of our experiences may be of assistance to those who want to apply the method in these fields. Contrary to the author's observation that interactions are rarely significant, we have found in a number of cases that first order interactions exist which are significant and metallurgically important. Because of this difference there are two further precautions which should be taken in order to minimize the difficulties from this point. First, in evaluating the importance of

Jan 1, 1957

By A. Vignes, J. P. Sabatier

A study of ternary diffusion at 1315°C in the Fe-Co-Ni system covering the entire ternary phase diagram has been carried out. Experimental values of the four interdiffusion coefficients DFeNico,DFeCoCo, DFeCoNi were computed at 33 points of the ternary diagram. The limiting values of these coefficients on the three sides of the ternary diizgram have also been determined. This set of data is presented as a contour map on the ternary isotherm for each of the four coefficients. Assuming that the Fe-Co-Ni system can be considered as ideal, the phenomenological coefficients Lk ij (with k = Fe) have been computed and the Onsager reciprocal relutions verified. It is shown that, in the Fe-Co-Ni system, the diffusion process can also be described by only two interdiffusion coefficients DFeFe and DCoNiFe, the second cross diffusion coefficient DCoFeNi being equal to zero and the second direct difusion coefficient being given by The values of the cross interdiffusion coefficients and of the Onsager coefficients are explained in terms of atomic mobilities of the three components with the help of a kinetic calculation due to Lane and Kirkaldy.8 It is shown that all the results are explained if the tracer difusion coefficients of the three components are such that DFe > DNi ~ DCo in complete agreement with experimental data on the three binary systems. DIFFUSION in a ternary alloy system is basically and significantly different from diffusion in binary alloys. In binary diffusion, there is just one independent composition variable and only one coefficient Dij is needed to describe the interdiffusion process. In ternary diffusion, we must allow for cross interaction between two independent species, and four interdiffusion coefficients are necessary to describe the transport process. Kirkaldy et al.1,2 have determined interdiffusion coefficients in the systems, Cu-Mn-A1 and Zn-Cu-Al. Guy and Leroy4 have reported intrinsic diffusion coefficients for the r phase at 1300°C of Co-Ni-Cr alloys as a function of composition using the analysis of Philibert and Guy.3 Interdiffusion coefficients were measured at three different compositions at 850°C in the single phase copper-rich corner of the Cu-Zn-Mn system by Dayananda and race.5 Zie-bold and Ogilvie6 have determined interdiffusion coefficients in the single-phase field of the Cu-Ag-Au system at 725°C. Preliminary results on diffusion at 1136°C in the system Fe-Co-Ni have been reported.7 In this study, data are reported on a more complete determination of interdiffusion coefficients in the Fe-Co-Ni system in the entire ternary at 1315°C. There is complete solid solubility with the fcc structures at 1315ºC, and this system can be considered as nearly ideal. This approximation allows the computation of the Onsager phenomenological coefficients. These values can then be used to test a kinetic calculation of the Onsager L coefficients in ternary substitutional solid solutions due to Lane and Kirkaldy.8

Jan 1, 1970

By F. M. Lewis, J. F. Meyers

This second progress report of grinding presents comments regarding ball consumption and data pertaining to the hydroscillator, which is closed circuited with the tricone mill. A study and postulate of how balls function is presented. The paper summarizes cost reduction obtained by the method of "grinding for the tail race" rather than for "mesh tons." AT the Regional meeting in Columbus, Ohio, in September 1949, the authors presented a progress report of the first year's operation with a Hardinge tricone mill in closed circuit with a Dorr hydroscillator. The present report covers our findings on this grinding circuit to January, 1950. In order to clarify our position, the authors wish to state that no invention or discovery is claimed. The Tennessee grinding circuit is simply an engineered arrangement of known equipment arranged to incorporate all of the recognized efficiency factors of comminution as they are known today. As we concluded our first report, it was not clear how effective the Tennessee mode of operation would be on harder ores. The only information we had at that time was that the Bond grindability test at 48-mesh gave 6.04 g of undersize per revolution. A later test on the same sample at 100-mesh reduced this to 2.04 g, which is definitely in the harder ore class, and which makes the reported 8.80 kw-hr per ton of —200-mesh produced a very creditable figure. Hydroscillator Operation The machine as now developed has proved dependable and easy to operate. It starts easily under full load and responds quickly to operating adjustments. The hydraulic holes in the oscillating plate do not plug when shut down under full load. Absolutely clean hydraulic water is essential. An Elliott water screen or similar device should be an essential part of the machine to keep all scale and trash of all kinds from the hydraulic compartment. The shift operators have expressed approval of the machine. In table I we show a typical screen analysis of the hydroscillator rake sand as compared to conventional classifier rake sand on our ore. We have previously reported that of the 28.7 pct reduction in power, the hydroscillator contributed 6 pct, on a —200-mesh basis. This is a conservative figure. Some of our test runs indicated that the saving was as high as 10 pct. Laboratory studies by the Dorr Co. engineers indicate that still greater efficiency is possible. Nevertheless, the 10-ft plate is overflowing 2100 tons per day at 3 to 4 pct + 65-mesh, which is a very creditable performance by

Jan 1, 1951

I HIT the ceiling when I opened my November MINING ENGINEERING and after waiting a week to cool off I' still find it necessary to express my resentment of the gross libel embodied in the editorial introduction to Norman Stines' legitimate criticism of my paper on "Russia's Mineral Potential" (p. 949). The underlying thesis of my article, and a point that I tried to make even more clearly in my oral presentation at the St. Louis meeting last February, is that we should not over estimate the present and near-future mineral production of the USSR. The words that I resent in your boxed introduction are: "Opinions range from those presented by Paul Tyler ... to those of Norman C. Stines . . ." This is not merely an understatement that can be defended by admitting that the range goes much farther to the left, beyond me. It represents the appraisal that 90 pct of your members will carry away, namely that I am not only an incompetent observer-which may be true-but always that my bias is to applaud the efficiency of the beasts in the Kremlin-which is not true. Notwithstanding my efforts to clarify the record I now find myself branded as being at the opposite pole from 'Mr. Stines among the red-eyed worshipers of Communism or at least among the timid souls that shake in their boots in the belief that the Soviet system has created an invincible as well as an evil menace to the decent peoples of the world. My ideas are somewhere in the middle ground between Mr. Stines' complaisance or contempt and the exaggerated fears of several other observers whose views have received wide acceptance. PAUL M. TYLER MINERAL TECHNOLOGIST & ECONOMIST 5005 EDGEMOOR LANE, BETHESDA, MD. The introductory paragraph to Mr. Stines' criticism of Mr. Tyler's article (Russia's Mineral Potential, June issue MINING ENGINEERING, page 494) is erroneous as pointed out in author Tyler's letter above. In his article he objectively presented an estimate of the mineral position of the Soviet based on the statistics available to him which sources are credited in the first paragraph of his article. We happen to know that, Mr. Tyler was reluctant to prepare the article for the Mineral Economics Division sessions at the 1951 Annual Meeting and did so only because of his loyalty to AIME. It was thought that this article would be a basis for discussion of this important subject at the Annual Meeting. We apologize to Mr. Tyler for any embarrassment our introduction, may have caused him. Editor

Jan 1, 1952

By Lee Morris, Charles E. Lawall

This paper represents the results of a study to determine the source, mode of occurrence and conditions influencing the flow and liberation of large volumes of inflammable gas in the Pocahontas No. 4 coal bed in southern West Virginia. A study of this kind is of interest in connection with mine ventilation, because in the removal of gases from coal mines it is very important to know the origin, the occurrence and laws of gas flow. The study was started in April, 1931, and the data and observations were obtained throughout a period of 15 months of field work. Geology The country where this study was made is mountainous and rugged; great cliffs, precipitous slopes and deep narrow gorges are found throughout the area. The outcropping rocks consist of stratified layers of sandstone, shale, limestone and deposits of coal of Carboniferous age. The Pottsville series of the Pennsylvanian, lying at the base of this period, cover the greater portion of the area. A stratigraphic section of the Pocahontas group of the Pottsville series is shown in Fig. 3. The older rocks outcrop in the extreme southeastern part of the area, but are under drainage in the central and northern parts due to the gradual northwest dip of the strata. The structure has a general northeast-southwest trend (Fig. 1). North of Dry Fork anticline the strata have been only slightly disturbed by movements of the earth's crust; it is now a long monocline. Southeast1 of Dry Fork anticline the strata are warped into great arches and deep troughs and are broken by overthrust faults. All of this folding is probably the result of the intense folding associated with the formation of the Appalachian Mountains. Pocahontas No. 4 Coal Bed The Pocahontas No. 4 bed, lying approximately 550 ft. above the base of the Pottsville series, is one of the thickest and most gassy coal beds in

Jan 1, 1934

By D. A. Belforti, M. P. Lepie

Spectroscopically pure copper was melted on sapphire plaques in a zydrogen atmosphere. The surface tension of the liquid metal was determined using the sessile drop technique. Measurements were made by direct observation with the aid of a specially const,mcted telescope. The value obtained, 1268 dynes per cm, is compared to that found in the literature. THERE is at this time considerable interest in the use of ceramics for vacuum tubes. The crystalline material is superior to the more conventional glass in mechanical strength, chemical inertness, dielectric properties, ability to withstand high temperatures, and so forth. However, ceramics are much more difficult to seal hermetically with metals than are the glasses. For this reason an investigation was undertaken to determine the wetting and adhesion of metals to ceramics. The sessile drop technique offers a convenient means at elevated temperatures for measuring liquid surface tension, wetting angle, density, spread- ing coefficient, and work of adhesion. Thus, from the contour of a drop of liquid at rest on a solid surface one can obtain a quantitative evaluation of the degree to which the two substances will bond. To this end a special apparatus was constructed so that various molten metals could be observed. Standardization of the apparatus was done initially by measuring the surface tension of copper since this is well documented in the metallurgy literature. Although there are many methods available for the measurement of surface energy,'+ the sessile drop technique has been used most extensively for molten metals and ceramics.5"' Fig. 1 illustrates the dimensions to be measured. From these values, the surface tension of the liquid can be obtained using the Bashforth and bdams' equation and tables.

Jan 1, 1963

By J. J. Kramer, G. W. Wiener, K. Foster

The effects of the primary grain size and sheet thickness on the secondary growth rates of grains with (100) surface planes were studied in 3 pct Si-Fe sheets. This secondary grain growth was carried out under conditions in which the {100} plane had the lowest surface free energy. The value of the surface energy difference, between the (100) plane and the random matrix planes was found to he only about 3 pct of the grain boundary energy, indicating that most of the driving force for secondary growth is supplzed by grain boundary energy. A method for obtaining cube texture in 3 pct Si-Fe sheets by a secondary recrystallization process has been reported.' It has been demonstrated that a difference in surface free energy between the (100) plane and other planes is responsible for this growth, where the (100) plane has the lowest surface energy. A semiquantitative relation has been derived for secondary grain growth in sheets where primary grain growth has proceeded until the grains have grown through the sheet and the average grain diameter in the plane of the sheet is from one to two times the sheet thickness. Then, the linear growth rate, G, for the secondary grains can be given by where M is the grain boundary mobility, is the grain boundary free energy, is the average primary grain radius, A is the average difference in surface free energy between the (100) plane and planes of other orientations, t is the sheet thickness, and C is a term first proposed by zener6 which acts as a negative driving force, the effect of inclusions in holding up grain boundary motion. Since the problem of grain growth being discussed is under conditions where the matrix grain size is at least equal to the sheet thickness, the radius r is, of course, a function of the sheet thickness. The term B/r is the grain boundary driving force normally associated with inclusion inhibited or texture inhibited secondary recrystallization. Here, however, the term is modified to account for the fact that growth occurs in thin sheets. The term is the additional driving force available because of the difference in surface free energy. The purpose of the present work has been to evaluate the driving force terms of the growth equation by studying growth rates of (100) secondary grains as a function of sheet thickness and primary grain size. From these data it has been possible to determine the relative values of grain boundary energy, surface energy difference, and the inclusion term, C. EXPERIMENTAL PROCEDURE A 3 pct Si-Fe alloy was melted and cast under a helium atmosphere using electrolytic iron and a pure commercial grade of silicon as raw materials. The alloy was hot and cold rolled to a thickness of 0.6 mm, and samples approximately 5 in. long by 1 1/4 in. wide were cut from the cold-rolled sheets. Four different primary grain sizes were obtained

Jan 1, 1963

By Benjamin C. Allen

The surface tensions of liquid chromium and manganese were determined by a modification of the dynamic drop-weight method and found to be, respectively, 1700 * 50 and 1100 * 50 dynes per cm at their melting points. Molten drops were formed LITTLE is known about the surface tension of liquid chromium and manganese, even though they are technologically important metals and widely used in steelmaking. In the past, direct determinations have been hampered by their high reactivity on the lower end of a vertically held rod inductively heated under argon. The technique essentially reproduced surface tensions reported for liquid nickel and zirconium using static drop-shape methods. and vapor pressure. In this work, surface tensions were measured by the drop-weight method, using induction heating under argon. EXPERIMENTAL WORK Chemical analyses of rods used are given in Table I. Chromium rods were prepared from iodide-process crystals which had been are-melted, hot-extruded, warm-swaged, and centerless-ground.'

Jan 1, 1964

By F. M. Lewis, J. F. Meyers

This second progress report of grinding presents comments regarding ball consumption and data pertaining to the hydroscillator, which is closed circuited with the tricone mill. A study and postulate of how balls function is presented. The paper summarizes cost reduction obtained by the method of "grinding for the tail race" rather than for "mesh tons." AT the Regional meeting in Columbus, Ohio, in September 1949, the authors presented a progress report of the first year's operation with a Hardinge tricone mill in closed circuit with a Dorr hydroscillator. The present report covers our findings on this grinding circuit to January, 1950. In order to clarify our position, the authors wish to state that no invention or discovery is claimed. The Tennessee grinding circuit is simply an engineered arrangement of known equipment arranged to incorporate all of the recognized efficiency factors of comminution as they are known today. As we concluded our first report, it was not clear how effective the Tennessee mode of operation would be on harder ores. The only information we had at that time was that the Bond grindability test at 48-mesh gave 6.04 g of undersize per revolution. A later test on the same sample at 100-mesh reduced this to 2.04 g, which is definitely in the harder ore class, and which makes the reported 8.80 kw-hr per ton of —200-mesh produced a very creditable figure. Hydroscillator Operation The machine as now developed has proved dependable and easy to operate. It starts easily under full load and responds quickly to operating adjustments. The hydraulic holes in the oscillating plate do not plug when shut down under full load. Absolutely clean hydraulic water is essential. An Elliott water screen or similar device should be an essential part of the machine to keep all scale and trash of all kinds from the hydraulic compartment. The shift operators have expressed approval of the machine. In table I we show a typical screen analysis of the hydroscillator rake sand as compared to conventional classifier rake sand on our ore. We have previously reported that of the 28.7 pct reduction in power, the hydroscillator contributed 6 pct, on a —200-mesh basis. This is a conservative figure. Some of our test runs indicated that the saving was as high as 10 pct. Laboratory studies by the Dorr Co. engineers indicate that still greater efficiency is possible. Nevertheless, the 10-ft plate is overflowing 2100 tons per day at 3 to 4 pct + 65-mesh, which is a very creditable performance by

Jan 1, 1951

By Peter F. Weiss

INTRODUCTION Austro-American Magnesite Co. of Radenthein, Carinthia, Austria, is a wholly owned subsidiary of General Refractories Company, Bala Cynwyd, USA, and has been incorporated since 1908. The raw material basis is the magnesite mine on Millstatt Alp, located in the mountains near Radenthein at an altitude of 1500 m above sea level. The mined crude magnesite is crushed in a surface crushing plant to minus 35 mm and consequently hauled to the processing plant in the valley by means of a cable conveyor of 7.5 km length. The annual production of 350,000 mt is accomplished with 20 supervisors and 122 workers (of those 60 are in the mine). The labor requirement for block caving is 0.2 man hr/mt, corresponding to an output of 40 mt/man/ shift. GEOLOGY The rock in this area mainly consists of crystalline type schist. There are mostly coarse crystalline garnet mica schists with varying mineral concentrations, and to a lesser degree, some deposits of amphibolite and marble. This petrographically rather homogeneous rock is divided into numerous different tectonic units (covers and scales). The magnesite deposit itself is a foreign body that also has been tectonically inserted. The ore body has a length of 600 m, is 450 m deep, and has a thickness of 60 m on average, varying substantially however, The contact with the accessory rock is very precise. The deposit 1 = ore body, 2 = previous open pit, 3 = caved in area, 4 = block under excavation, 5 = land slide consists of coarse crystalline magnesite in excess of 90 per cent. The few impurities consist of dolomite and talc. The lower part of the deposit is inclined parallel with the schists at approx. 40 degrees. In profile it can be seen, however, that the upper part of the deposit has been tilted over. This is a result of a post-glacial land slide reaching from the bottom of the valley at 1400 m above sea level to the peak of the mountain at 2100 m above sea level. Due to this land slide, with horizontal movements of up to 100 meters, as well as older tectonic events, the rock was crushed to a vast extent. Through mining, the land slide was reactivated; about 40 million cubic meters of rock slowly flow downhill almost like a plasticized mass. Near the surface, the rock is completely crushed and resembles a glacier rupture zone. This renders the originally impermeable rock completely water permeable so that practically all of the annual quantity of 1000 to 1100 mm of precipitation permeates the rock and flows down into the mine. The carbonate rock turns into the preferred aquifer. From 1700 to 2600 cubic meters of water have to be pumped from the mine daily. On one hand, additional problems are caused by the water in the mine, on the other hand we have learned to make use of the down- hill pressure forces to improve the crushing process during block caving. The boundary of the downhill shearing zone moves downward as mining goes deeper.

Jan 1, 1981

By C. F. Frey, P. J. Ahern, J. F. Wallace

THE high affinity of molten titanium for oxygen and nitrogen has resulted in considerable difficulty in developing a satisfactory melting procedure. It has been found necessary to perform melting operations either in a vacuum or inert atmos-phere, and failure to obtain a satisfactory crucible material has necessitated the use of special melting techniques. These techniques have included cold-mold arc-melting utilizing both consumable and nonconsumable electrodes, skull-melting, drip-melting, and levitation melting.' It has been recognized generally that the melting of both titanium sponge and titanium scrap would be expedited by the use of induction-melting procedures but the lack of a crucible capable of containing molten titanium without objectionable contamination thus far has prevented the use of induction-melting procedures. An extensive investigation: which included the common refractory materials was not successful in developing a satisfactory crucible for induction-melting. Some success in induction-melting has been attained with the use of a graphite crucible material, but in all instances sufficient carbon contamination was encountered to cause an appreciable reduction in the optimum mechanical properties of the titanium or titanium alloys. These investigations"" report an increase in the carbon content from approximately 0.3 to 1.0 pct. A serious reduction in the tensile and forming properties has been observed as a result of this carbon contamination. The development of a satisfactory induction-melting procedure for titanium without undue contamination undoubtedly would have considerable economic significance. Such a process would be particularly useful in melting the large quantities of low-cost scrap now available that can only be reprocessed at considerable expense and difficulty by the more elaborate techniques referred to previously. In addition, the process could provide a satisfactory method of melting and alloying of bri-quetted sponge for forging ingots.

Jan 1, 1959