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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 Warren L. Howes

THIS paper deals primarily with an investigation of ball-mill liners that was conducted by the writer over a period of six years at the Mammoth mill in Arizona. The investigation covered a wide variety of designs of liners in both primary and secondary mills. The comparative results are presented herein as evidence of the extent to which design influenced liner life and mill performance. FLOWSHEET The feed to the Mammoth mill was a complex, oxidized, gold-silver-lead-molybdenum-vanadium ore with rhyolite, andesite and granite as gangue. Although the ore varied between stopes, the long-term average in character remained substantially the same. Capacity was 560 tons per day. [t] Fig. I shows an abbreviated flowsheet of the grinding section of the mill. PRIMARY BALL MILL A 3-ft. Symons shorthead crusher in open circuit crushed to ¼ -in. maximum one-way dimension the feed to the 5 by 10-ft. Marcy open-end ball mill. The mill rotated at 80 per cent of critical speed and was charged with 4-in. forged steel balls. Cast balls were used for a few months at a slight reduction in ball cost, but breakage of the large balls reduced the ball size and grinding capacity to a point where the over-all costs suffered out of proportion to the saving in cost of balls. For metallurgical reasons, the finished product of the mill was maintained at minus 8-mesh. This coarse product, plus the very abrasive ore and the absence of fines in the feed, caused abnormally rapid wear of the mill liners. The resultant high operating cost led to the most extensive phase of the investigation. [ ] In order to clarify the difference in design of the various types of liners used, Fig. 2 shows the profiles with the arrangement in which grinding balls of maximum size would lie on the face of the liners. The results with each type of shell liner in the primary mill are shown in Table I.

Jan 1, 1943

By W. G. Sinclair

THE North Texas district presented in this paper includes the counties of Archer, Baylor, Clay, Cooke, Foard, Hardeman, Jack, Knox, Montague, Wichita, Wilbarger and Young. It corresponds with the Texas Railroad Commission's district No. 9. Table I conforms with the nomenclature of pools as designated by the Commission. Most of the oil and gas produced in this region, generally referred to as the Red River uplift, comes from the Pennsylvanian strata. In recent years, however, increasing amounts are being developed in both the Mississippian and Ordovician.

Jan 1, 1946

By N. J. Themelis, P. Spira

The efficiency of the reverberatory furnace operation in producing. slags of 1020 copper content depends on the mixing and flow conditions in the bath. Radioactize-tmcer tests have indicated the jkaction of bath volume engaged inflow and the mixing conditions in the bath. The factors controlling the flow pattern of slag have been classified as laminar transfer flow, natrsral convection, and flou, due to the rapid addition or removal of slag.. Similarity criteria for model studies have been developed. The pyrometallurgical processing of copper begins with the smelting of either flotation concentrates, or direct-smelting ores which have been partially roasted to calcines. These materials are generally smelted in a reverberatory furnace, Fig. 1, and separate into two liquid phases, a sulfide matte and an iron silicate slag. he matte is tapped and subsequently reduced to metallic copper in a converter, while the reverberatory slag is usually discarded without any further treatment. Molten slag from the converting operation is returned intermittently to the reverberatory in order to recover its high copper content (1 to 3 pct Cu). The reverberatory furnace is about 115 ft long by 30 ft wide. In general, the solid charge is fed at intervals through openings along the sides of the roof and forms sloping banks from which the molten materials trickle down into the bath; the charge banks extend over a length of about 70 ft from the firing wall. The depth of the slag and matte layers varies from smelter to smelter; in the Noranda furnaces, the slag depth is 24 to 30 in., while the depth of matte at the taphole is about 20 in. Apart from smelting, the functions of the reverberatory are to recover most of the copper content in the converter slag by physical and chemical interaction with the furnace bath, and to provide adequate time for optimum separation between matte and slag. The efficiency of these operations depends on the mixing and flow conditions in the bath and is reflected on the copper losses in the slag. In the present study, the reverberatory furnace is considered as an open-channel chemical reactor and the driving forces for material transport through the bath are examined by means of flow and mathematical models. FLOW CONDITIONS IN THE REVERBERATORY FURNACE To facilitate the study of mixing conditions in continuous-flow reactors, two idealized patterns of flow have been accepted by workers in this field.' The term "backmix" flow is used to describe complete and instantaneous mixing in the reactor (perfect mixing); all particles have the same chance of leaving the system, independently of their time of entrance, and the fluid is uniform in composition throughout the vessel. On the other hand, "plug" flow, or "piston" flow, assumes that a fluid element moves through the reactor without overtaking or mixing with fluid entering at an earlier or later time. In addition to the two idealized patterns of flow, "deadwater" flow accounts for that portion of the fluid which is moving so slowly that it may be assumed to be stagnant. According to the definition by evensppiel,' the cut-off point between active and stagnant fluid may be taken as material which stays in the vessel for a period twice the mean residence time. The flow patterns in real vessels may be approximated by a combination of the above flows. Thus, the vessel is assumed to consist of interconnected flow regions with various modes of flow existing between them. The flow pattern may be determined directly from the flow paths of fluid through the essel. -However, the difficulty of obtaining and interpreting such information has led to the alternate approach of determining the residence time distribution of fluid elements by means of stimulus-response studies. The stimulus is provided by introducing a tracer in the inlet stream and the response by the record of the change in tracer concentration in the exit stream from the reactor. Such tests have been conducted in glass tank furnaces using either chemical7"9 or radioactive tracers1'-'' and, in one case, experiments have been reported for a metallurgical furnace.'"

Jan 1, 1967

By E. F. Kingsbury

One of the well-known and important uses of the noble or precious metals has been for electrical contacts. In fact, the elements of this group, comprising gold, silver and the six platinum metals, have been called "noble" because of their ability to resist heat and corrosion, properties which were early found to be of importance in good contacts. Of these, platinum and its iridium alloys, palladium, and silver, have been extensively used. In recent years the electrical industry has been responsible for about one-eighth of the total consiimption of the platinum metals in the United States. Information is not available as to what part of this one-eighth has been used for contacts but it is certainly an important one. Substitutes for Platinum During the past 20 years a considerable number of contact alloys have been proposed in the patent literature largely with the aim of more or less replacing platinum by gold or silver, and some of these alloys are finding increasingly widespread application as the reliability of their performance becomes established. From even the partial data at hand it appears that this substitution by the less precious metals has replaced at least one-half of the amount of platinum that the entire electrical industry would otherwise be consuming at the present time. While the subject is of considerable interest to the metallurgist it is even more so to the electrical engineer and it is surprising that the literature records no systematic and comprehensive investigation along these lines. Practically all the scattered work on noble metal contacts has centered around platinum as a standard and has had two more or less distinct aims. One of these has been the replacement of platinum by cheaper matcrials, and the other, the dcveloprnent of materials of superior electrical performance. The merit of a contact metal has been assumed to be dependent on its infusibility, and since thc more precious metals have the higher melting points there has naturally been an association of the two qualities in the sense that the more precious were

By W. M. Rust, W. D, D. W. Mounce

The almost universal acceptance of electrical logging by the petroleum industry calls for a critical examination of the physical bases of the common methods. This is particularly needed for the natural potential log. The conventional explanations are based on the phenomena of electrofiltration and electro-osmosis. However, experimental data show that they fail to give a basis that is quantitatively sound. Moreover, they lead to interpretations of details of electrical logs that are erroneous. It was found experimentally that when a plug of shale is placed in a chain of dissimilar electrolytes, a current flow results. Experiments on oil-well cores and fluids similar to those existing in wells show that potentials are set up which are in reasonable agreement with those encountered in electrical logging. Doubtless other sources of potential are important but this explanation not only accounts for much of the potential but also clarifies some fairly familiar examples of misinterpretations. Introduction The extraordinary value of electrical well logging as a tool for petroleum engineers and geologists is now so uni- versally recognized that it is not necessary to point out the ways in which it can be useful. It is sufficient to mention only the saving that has resulted from the elimination of much coring that would have been necessary under former practices and the considerable additions to reserves resulting from the discovery of sands missed in coring. Paradoxically, the very remarkable success that has resulted from the application of electrical logging to correlation and completion problems has cost some of its most consistent users dearly.' The fact that some operators have placed unwarranted faith in erroneous interpretations of electrical logs does not reduce the value of the logs. It should, however, make one pause long enough to ask why experienced users should be misled. The answer to this question is not hard to find. In nearly every case, the fault has been oversimplification. This is illustrated very aptly by the familiar interpretation and theory of the natural potential log. Recording and Interpreting Logs The natural potential log is extremely simple to record precisely enough for all present-day uses. One needs only an electrode, a cable to lower the electrode through the drilling mud, a recording meter and a surface ground connection. The electrode can be elaborate but need not be. A simple brass rod 2 in, in diameter and 2 or 3 in. long is quite satisfactory. The cable need not be particularly well insulated, nor need it have a very low resistance. The recorder can be a vacuum-tube 1 References are at the end of the paper.

Jan 1, 1944

By W. D, D. W. Mounce, W. M. Rust

The almost universal acceptance of electrical logging by the petroleum industry calls for a critical examination of the physical bases of the common methods. This is particularly needed for the natural potential log. The conventional explanations are based on the phenomena of electrofiltration and electro-osmosis. However, experimental data show that they fail to give a basis that is quantitatively sound. Moreover, they lead to interpretations of details of electrical logs that are erroneous. It was found experimentally that when a plug of shale is placed in a chain of dissimilar electrolytes, a current flow results. Experiments on oil-well cores and fluids similar to those existing in wells show that potentials are set up which are in reasonable agreement with those encountered in electrical logging. Doubtless other sources of potential are important but this explanation not only accounts for much of the potential but also clarifies some fairly familiar examples of misinterpretations. Introduction The extraordinary value of electrical well logging as a tool for petroleum engineers and geologists is now so uni- versally recognized that it is not necessary to point out the ways in which it can be useful. It is sufficient to mention only the saving that has resulted from the elimination of much coring that would have been necessary under former practices and the considerable additions to reserves resulting from the discovery of sands missed in coring. Paradoxically, the very remarkable success that has resulted from the application of electrical logging to correlation and completion problems has cost some of its most consistent users dearly.' The fact that some operators have placed unwarranted faith in erroneous interpretations of electrical logs does not reduce the value of the logs. It should, however, make one pause long enough to ask why experienced users should be misled. The answer to this question is not hard to find. In nearly every case, the fault has been oversimplification. This is illustrated very aptly by the familiar interpretation and theory of the natural potential log. Recording and Interpreting Logs The natural potential log is extremely simple to record precisely enough for all present-day uses. One needs only an electrode, a cable to lower the electrode through the drilling mud, a recording meter and a surface ground connection. The electrode can be elaborate but need not be. A simple brass rod 2 in, in diameter and 2 or 3 in. long is quite satisfactory. The cable need not be particularly well insulated, nor need it have a very low resistance. The recorder can be a vacuum-tube 1 References are at the end of the paper.

Jan 1, 1944

By E. B. Snyder, H. M. Kraner

This paper shows that volume stability, low porosity and decreased pyroplasticity are desirable for blast-furnace linings, partitularly for the hearth. It shows further that a hot load test is a valuable means of testing the fusion or softening behavior of a refractory at operating temperatures. The effect of carbon monoxide on commercia1 blast-furnace refractories in their as-received condition and after refiring is reported, showing that many commercial blast-furnace refractories disintegrate badly but that refiring decreases the effect and certain special refractories are now available which are almost free of the tendency. Factors Affecting Choice of ._ Refractories If one were to depend entirely upon experience or trial in the selection of clay refractories, the solution of a problem would be a slow process. Furnace campaigns are so long and attended by so many variables that it is difficult to draw fine distinctions within a reasonable period of time in regard to the quality of refractories used. It could be said, of course, that if service results do not yield the proper information for intelligent choice, there is no difference in the quality of brick being considered, but this is not necessarily true. Conventional ceramic tests are designed to give the ceramic engineer information as to the refractoriness and firing tempera- . ture, which he in turn internrets in terms of volume stability, ability to withstand load at high temperature (pyroplasticity), permeability, chemical stability and re-. sistance to the action of slag. In most refractory applications . several of these factors are involved. In a particular instance, one requirement may be predominant, while in others some other factors may be of primary importance. In this country, clay refractories are generally made from mixtures of plastic and flint fire clays. The process of firing a clay refractory is one of slowly melting the constituents, and during this operation its porosity is gradually reduced. The process is arrested, of course, in its incipient Stages and the Progress is determined by measuring slight changes in porosity, volume, bulk gravity, etc., that have taken place. Often the temperatures to which clay refractories are exposed in service are higher than those employed in their firing. However, if the manufacturer were to fire them at such high temperatures the brick would distort. Therefore it would be difficult for the manufacturer to fire all of his clay refractories to temperatures at which they are to be used, although in many cases it would be desirable from the user's point of view if he would do so. The porosity of clay refractories decreases by firing, to a minimum limit, after which a further increase in the temperature causes expansion in certain clay constituents and bloating in others. Both may occur in the same refractory containing two such clays.

Jan 1, 1944

By H. M. Kraner, E. B. Snyder

This paper shows that volume stability, low porosity and decreased pyroplasticity are desirable for blast-furnace linings, partitularly for the hearth. It shows further that a hot load test is a valuable means of testing the fusion or softening behavior of a refractory at operating temperatures. The effect of carbon monoxide on commercia1 blast-furnace refractories in their as-received condition and after refiring is reported, showing that many commercial blast-furnace refractories disintegrate badly but that refiring decreases the effect and certain special refractories are now available which are almost free of the tendency. Factors Affecting Choice of ._ Refractories If one were to depend entirely upon experience or trial in the selection of clay refractories, the solution of a problem would be a slow process. Furnace campaigns are so long and attended by so many variables that it is difficult to draw fine distinctions within a reasonable period of time in regard to the quality of refractories used. It could be said, of course, that if service results do not yield the proper information for intelligent choice, there is no difference in the quality of brick being considered, but this is not necessarily true. Conventional ceramic tests are designed to give the ceramic engineer information as to the refractoriness and firing tempera- . ture, which he in turn internrets in terms of volume stability, ability to withstand load at high temperature (pyroplasticity), permeability, chemical stability and re-. sistance to the action of slag. In most refractory applications . several of these factors are involved. In a particular instance, one requirement may be predominant, while in others some other factors may be of primary importance. In this country, clay refractories are generally made from mixtures of plastic and flint fire clays. The process of firing a clay refractory is one of slowly melting the constituents, and during this operation its porosity is gradually reduced. The process is arrested, of course, in its incipient Stages and the Progress is determined by measuring slight changes in porosity, volume, bulk gravity, etc., that have taken place. Often the temperatures to which clay refractories are exposed in service are higher than those employed in their firing. However, if the manufacturer were to fire them at such high temperatures the brick would distort. Therefore it would be difficult for the manufacturer to fire all of his clay refractories to temperatures at which they are to be used, although in many cases it would be desirable from the user's point of view if he would do so. The porosity of clay refractories decreases by firing, to a minimum limit, after which a further increase in the temperature causes expansion in certain clay constituents and bloating in others. Both may occur in the same refractory containing two such clays.

Jan 1, 1944

By Warren E. Wilson

The transportation of solids in pipe lines is a matter of deep concern in many fields of engineering. Much experimental and theoretical work has been done in an effort to devise means of designing pipe lines that will satisfactorily transport given solid loads, but there remain many unanswered questions in this field. The present discussion will be confined to a rather narrow portion of this field and will endeavor to point out certain factors that may well be considered when comparing the relative economy of various installations. The data have been presented previously but a new interpretation was prompted by a suggestion in a paper by Professor O'Brien,1 of the University of California, that the friction work per pound of dry material should be considered in determining the relative efficiency of various installations. This method of considering relative economy in various pipe lines leads to some rather unexpected conclusions, especially with reference to the economy of large pipe sizes. A previous suggestion by the writer3 concerning the economy of a rather peculiar type of installation is strengthened. It is not believed that the considerations set forth herein apply directly in the case of dredge lines, where economy is largely a matter of a high rate of pumping in order to reduce the unit overhead charge. However, it is believed that some value may be gained from these considerations in cases involving the disposal of a fixed amount of solids per unit time with a minimum expenditure of energy and at a low cost for replacement of worn pipes. Such situations are not uncommon in the disposal of mill tailings and the disposal of solids deposited from irrigation waters. It was found that data leading to general conclusions for various pipe sizes were not available but certain definite trends are indicated and methods of analyzing available data are presented in the hope that they may be of assistance in preparing engineering estimates on designs of pipe lines of the type described above. Energy Requirements Carrying out the idea contained in ' Professor O'Brien's paper concerning the method of computing energy required to transport solids, the following analysis leads to some rather interesting conclusions. Let us represent: Solids load in term of mass per unit time by W Ratio of mass of suspended solids to total mass of mixture flowing by p Volume rate of flow of mixture by Q Length of pipe by L slope of energy grade line by s Mass per unit volume of solids by m. Mass Per unit volume of liquid by mi Mass per unit volume of mixture by mm We then have as an expression for the solids load: W = pQmm The work done per unit mass, P, on the mixture to move it along the pipe the

Jan 1, 1948

By Warren E. Wilson

The transportation of solids in pipe lines is a matter of deep concern in many fields of engineering. Much experimental and theoretical work has been done in an effort to devise means of designing pipe lines that will satisfactorily transport given solid loads, but there remain many unanswered questions in this field. The present discussion will be confined to a rather narrow portion of this field and will endeavor to point out certain factors that may well be considered when comparing the relative economy of various installations. The data have been presented previously but a new interpretation was prompted by a suggestion in a paper by Professor O'Brien,1 of the University of California, that the friction work per pound of dry material should be considered in determining the relative efficiency of various installations. This method of considering relative economy in various pipe lines leads to some rather unexpected conclusions, especially with reference to the economy of large pipe sizes. A previous suggestion by the writer3 concerning the economy of a rather peculiar type of installation is strengthened. It is not believed that the considerations set forth herein apply directly in the case of dredge lines, where economy is largely a matter of a high rate of pumping in order to reduce the unit overhead charge. However, it is believed that some value may be gained from these considerations in cases involving the disposal of a fixed amount of solids per unit time with a minimum expenditure of energy and at a low cost for replacement of worn pipes. Such situations are not uncommon in the disposal of mill tailings and the disposal of solids deposited from irrigation waters. It was found that data leading to general conclusions for various pipe sizes were not available but certain definite trends are indicated and methods of analyzing available data are presented in the hope that they may be of assistance in preparing engineering estimates on designs of pipe lines of the type described above. Energy Requirements Carrying out the idea contained in ' Professor O'Brien's paper concerning the method of computing energy required to transport solids, the following analysis leads to some rather interesting conclusions. Let us represent: Solids load in term of mass per unit time by W Ratio of mass of suspended solids to total mass of mixture flowing by p Volume rate of flow of mixture by Q Length of pipe by L slope of energy grade line by s Mass per unit volume of solids by m. Mass Per unit volume of liquid by mi Mass per unit volume of mixture by mm We then have as an expression for the solids load: W = pQmm The work done per unit mass, P, on the mixture to move it along the pipe the

Jan 1, 1948

By W. F. Holbrook

THE problem of sulfur control is important in all blast-furnace operations but particularly for certain grades of steel because of the rigorous specifications. During the past decade the tendency has been to produce pig iron, and, hot metal of lower sulfur content. As most of the sulfur in the ion originates in the fuel, the use of high-sulfur coke demands modifications in practice to meet sulfur specifications. While it is generally known that high temperatures and more basic slags favor desulfurization, operators as a rule produce the most acid slag that will permit proper desulfurization. The viscosity of blast-furnace slag has been thought to be related to desulfurization and has been investigated by Feild and Royster1, also McCaffery and his associ-ates2, but apparently no systematic effort has been made to determine the relative desulfurizing powers of slags over the range of composition encountered in practice.

Jan 1, 1936

By P. P. Scott, George C. Howard

A field remedial procedure utilizing a kerosene-cement slurry as a water plug-off agent in fractured formations was evaluated both in the laboratory and in the field. This procedure has proved to be capable of effectively shutting off water without causing permanent impairment of the oil production. Success was attributed to the fact that an immobile cement slurry, when placed in a water-producing strata, will set and form an impermeable barrier; whereas when placed in an oil-producing section the cement will retain a relatively high permeability and may be removed by acidizing. INTRODUCTION One of the most perplexing problems facing the oil industry is the selective exclusion of water production from oil or gas-producing wells. This problem has been studied by many investigators in an attempt to develop a material that is not only capable of reducing water production but is also capable of being selective in that it will not impair oil production in either fractured or intergranular type reservoirs. A study of these two types of formations indicated that two distinct types of materials for controlling water production might be required — a completely liquid plugging agent for intergranular formations and a semi-liquid or slurry type plugging agent for fractured formations. This paper is limited to the control of water production from fractured formations. A common source of water in the vicinity of oil bearing rock reservoirs is water which previously has entered and, because of its higher density, generally lies near the bottom of the formation. When the deepest point of penetration of a well into such an oil and water-bearing formation is above the level of the water, and the dynamical gradients due to the flow of oil overbalance the difference in densities between oil and water, water production becomes a problem. Then the water level rises in the shape of a cone and is produced from the lower depths. Other investigators1,2,3,4 have developed theories which define the pressure gradients and contours of this cone in a homogeneous formation and have shown that the placement of a plug in the bottom of a well is only slightly effective in temporarily reducing the flow of water. Assuming that the manner of flow of bottom water from fractured formations to a well is generally similar to the flow in homogeneous formations, then it would be expected that some form of coning, perhaps of less symmetry, would also occur. Then, because of the similarity of the manner of flow of water, placement of a vertical plug in a fractured formation would also probably be ineffectual for controlling water production. However, as has been shown by electric model flow study,' the placing of a plug in a well and an impermeable horizontal streak in the formation might prove to be a means for materially reducing or even eliminating water production in a fractured formation. An indication of the difference in effectiveness between horizontal and vertical plugs based on theory developed from study of the flow of water and oil in rock reservoirs is depicted in Fig. 1. These curves show the expected

Jan 1, 1955

By D. S. Gleason, D. E. Severson, D. R. Skidmore

Pittsburg and Midway Coal Co. has modified the German Pott-Broche process, on which patents date back to 1927, to produce on a bench scale liquid products by solution hydrogenation of coal. A continuing program of lignite solution-hydro gena-tion experiments is directed toward investigating coal solution reactions, determining favorable conditions for the solution refining of lignite by the Pott-Broche process, and investigating some of the uses for the de-ashed product obtained from lignite The German Pott-Broche process1" on which patents date back to 1927, has been modified by the Pittsburg and Midway Coal Co., a Gulf Oil subsidiary, to produce on a bench scale liquid products by solution -hydrogena-tion of coal." The objectives of the present effort are to investigate coal solution reactions, to determine favorable conditions for the solution refining of lignite by the Pott-Broche process, and to investigate some of the uses for the de-ashed product obtained from lignite. This paper is a summary of results to date in a continuing program of lignite solution-hydrogenation experiments. The coal solution reaction program has several principal aims. The first of these is to determine whether lignite can be successfully dissolved in solvents that might be practical for commercial development. The second object is to determine whether the solvents function after successive cycles of use, recovery, and reuse. It seems necessary to the economics of a potential commercial process that the solvent be recycled. Third, it is desired to learn something about the distribution of the ash constituents between cake and filtrate. The extent of ash removal is important. The nature and quantity of mineral matter passing through the filter may determine end-use marketability. For certain use applications, trace quantities of certain minerals can be objectionable, e.g., titanium and vanadium must be very low in electrode carbon for aluminum production. The Solution Reaction The coal solution Process involves an extremely complex system of chemical reactions. An initial solvent such as anthracene oil is a mixture of hundreds of different compounds with a boiling range of roughly 500" to 750°F at atmospheric pressure. The coal macro-molecule is broken down by thermal decomposition and solvent action into myriads of different compounds, some the same as those comprising the solvent. This similarity in structures opens up the possibility of production and subsequent recovery of solvent. Some solvent is inevitably lost by reaction. Regeneration of solvent was not a problem in the early German Pott-Broche plant. The coal refinery was an integral part of a petroleum refinery complex and replacement solvent was readily available. A coal refinery using lignite, however, might be isolated from other hydrocarbon processing facilities and the regenerability of solvent could be vital to the economic success of the venture. Several structural features of the solvent molecules have been cited as important to the coal solution process.'. The first of these is aromaticity of the material, the second, ability to transfer hydrogen to another molecule, as for example the ability of tetralin to transfer hydrogen and be converted to naphthalene. Finally, the presence of hydroxyl groups on aromatic rings within the molecule, i.e., phenolic character, seems beneficial. Mixtures of pure compounds have been tried by various investigators. Mixtures of o-cresol, a phenolic substance, and tetralin were found to dissolve bituminous coal better than either substance alone.3 This maximum solubility was not found with lignite." Hydrogen contributes to the reaction by hydro-genolysis and by combining with free radicals and molecular "loose ends" to stabilize the compounds formed in coal depolymerization. High boiling point, and correspondingly high molecular weight, seems to be a property which improves solution potential for coal with a given type of compound.' The maceral components of the coal appear to have an important bearing on its ease of solution. The fusain portion is quite inert to solvent action, but the an-thraxylon material dissolves quite readily.3 The hydrogenation reaction can be improved by the use of a catalyst; commercial hydrogenation catalysts having been found effective. Although cost is involved in the use of catalyst and catalyst recovery, the resulting saving in time and perhaps lowered temperature or pressure might justify their use in the solution refining process and decrease the total process costs. Apparatus and Procedure The coal solution runs were made in a 1-gal stainless steel stirred autoclave. The autoclave was provided with thermocouple wells and a transducer to permit continuous recording of temperature and pressure. The autoclave stirrer was magnetically driven, eliminating the leakage inherent with a rotating pressure seal. For runs in which a catalyst was used, the catalyst in the form of beads was placed in a wire mesh container mounted on the stirrer shaft. A control system programmed the heatup and reaction cycle. The permissible heating rate was 5°F per min because of the need to minimize thermal stress in the autoclave body. The temperature was raised at that rate until the reaction temperature was attained and then the temperature was held constant for the desired length of time. The maximum temperature seldom exceeded the average run temperature by more than 15°F.

Jan 1, 1971

By Ancel St. John

DURING a session on coal and coke at the February, 1926, meeting of the American Institute of Mining and Metallurgical Engineers, the writer called attention to the important work on the X-ray analysis of coal1,2 being carried on in England by C. Norman Kemp and his associates. This aroused so much interest that a paper on the subject was requested for the October meeting. It has seemed advisable to make this paper a preliminary survey of the present status in the application of X-ray methods to coal problems and to follow it from time to time with further articles as the art develops. A survey of this sort naturally divides itself into two parts, radioscopic analysis of the distribution of constituents through the body of the coal, and diffraction analysis of the state of association of the elementary components. In this article the subject matter concerning radioscopic analysis has been drawn almost entirely from the writings of Kemp and his associates and the illustrations have been specially furnished by him. It is a pleasure to record here a great indebtedness for this courtesy and cooperation. The subject matter and illustrations concerning diffraction analysis are taken from the author's unpublished researches.

Jan 10, 1926

By H. M. Ziesemer, George Mieyr

Prior to 1909 that mountain of porphyry known as Sacramento Hill had hardly been touched though it had always been thought to contain ore. During that year, exploratory work was started by underground methods; drifting and raising continued until 1913. It was proved that a mineralized zone existed, the limits of which had not been determined ; so, because of the lower costs of exploratory work and the greater desirability of vertical sections, it was decided to prove the extent of the ore zone by churn drills. Drilling continued until 1917, when it seemed almost certain that the horizontal limits of the orebodies had been determined. Ore continued in depth in one direction beyond a point where it was economical to explore by churn drilling; this extension is still being developed by underground methods. The irregularities of the boundaries of the ore zones, together with the variable grades of ore encountered, made it necessary to drill on the corners of 100-ft. squares. Two ore zones were proved, known as the East and West Orebodies. The Sacramento Hill porphyry stock intruded into the Dividend fault. The fault ran roughly east and west with a dip to the south, having pre-Cambrian schists on the north against Paleozoic limestone on the south. This intrusion was accompanied by a silica breccia on the south periphery, along the limestone contact side. The ore lay in the silica breccia and in the porphyry, some distance from the breccia. NO ore was found in the heart of the porphyry mass on the north side, along the schist contact. The West Orebody is elliptic in shape, having a major axis of 1200 ft. (366 m.) and a minor axis of 800 ft. (244 m.); these diminish with depth until, at 300 ft., the axes are 500 ft. and 300 ft., respectively. The ore consists of chalcocite, some bornite, chalcopyrite, and considerable pyrite in a siliceous gangue. About 30 per cent. of the copper is caused by

Jan 1, 1923

By George Mieyr, H. M. Ziesemer

Prior to 1909 that mountain of porphyry known as Sacramento Hill had hardly been touched though it had always been thought to contain ore. During that year, exploratory work was started by underground methods; drifting and raising continued until 1913. It was proved that a mineralized zone existed, the limits of which had not been determined ; so, because of the lower costs of exploratory work and the greater desirability of vertical sections, it was decided to prove the extent of the ore zone by churn drills. Drilling continued until 1917, when it seemed almost certain that the horizontal limits of the orebodies had been determined. Ore continued in depth in one direction beyond a point where it was economical to explore by churn drilling; this extension is still being developed by underground methods. The irregularities of the boundaries of the ore zones, together with the variable grades of ore encountered, made it necessary to drill on the corners of 100-ft. squares. Two ore zones were proved, known as the East and West Orebodies. The Sacramento Hill porphyry stock intruded into the Dividend fault. The fault ran roughly east and west with a dip to the south, having pre-Cambrian schists on the north against Paleozoic limestone on the south. This intrusion was accompanied by a silica breccia on the south periphery, along the limestone contact side. The ore lay in the silica breccia and in the porphyry, some distance from the breccia. NO ore was found in the heart of the porphyry mass on the north side, along the schist contact. The West Orebody is elliptic in shape, having a major axis of 1200 ft. (366 m.) and a minor axis of 800 ft. (244 m.); these diminish with depth until, at 300 ft., the axes are 500 ft. and 300 ft., respectively. The ore consists of chalcocite, some bornite, chalcopyrite, and considerable pyrite in a siliceous gangue. About 30 per cent. of the copper is caused by

Jan 1, 1923

By W. I. Garms, J. L. Stevens

BECAUSE of the many conflicting opinions regarding the functioning of the ball load and the characteristics of ball wear in ball-mill grinding, the following resume of reports covering recent tests conducted at the Hayden plant of the Kennecott Copper Corporation is submitted with the view of pointing out certain salient features that should throw additional light on the subject. MILLS USED Cylindrical drum mills with trunnion feed and discharge were used. The discharge trunnion was I3 1/2 in. in diameter. Dimensions inside the lining were 6 ft. 6 in. in diameter and 9 ft. 6 in. long. The mills were Britannia-lined and nine lifter bars projected 2 in. from the lining. The mill speed was 16 2/3 r.p.m. Feed to the mill was 9 per cent on 10-mesh, 85 per cent on 100-mesh, 77 per cent solids. New balls measured 2 in. in diameter and the approximate weight of the ball load was 40,000 pounds. INITIAL TEST During a test that was being conducted to determine the relative economic value of standard cast balls vs. forged steel balls in the local grinding operation, certain observations were made in regard to the functioning of the various ball sizes and the characteristics of ball wear, which warranted a supplementary test for the purpose of confirming such observations. For the initial test, the necessity for developing a graduated load of the new forged balls before the test could be started was realized, but the time required to obtain a graduated load and the functioning of the various ball sizes was not clear. No advantage could be seen for starting out with a full load of forged balls, as this initial load, at the least, would have to be completely ground out and replaced by daily additions of balls before the graduation could be complete and a normal static condition of ball sizes reached. For a considerable period prior to exhaustion of this initial charge there would be an unusual quantity of worn balls of a certain size, which would not be typical of a normal charge and could influence the characteristics and functioning of the entire load. Therefore, it was decided to start by daily addition of the forged balls to a mill that contained a normal operating load of cast balls. After 88 days of operation the mill was shut down for inspection. By that time the load consisted of a mass of forged balls functioning around a large core of the residual material of the former cast-ball load. This core of cast slugs, locally referred to as "the kidney," was well defined from the forged-ball load.

Jan 1, 1946

By J. Bruce Wagner, Roger L. Levin

Lattice-parameter measurements have been carrzed out at room temperature on undoped and on chromium-doped wustite as a function of oxygen concentration. Results may he expressed by for the undoped uustite. These data are in agreement with and extend the work of' Jette and Foole. The present results are consistent with the cation vacancy model. for metal- deficil wuslite, both undopen and doped. SEVERAL investigators have made room-temperature lattice-parameter measurements on wustite as a function of composition. Jette and Foote used these measurements to determine the phase limits of wustite. Willis and Rooksby and Benard have also measured the lattice parameters of wustite at room temperature, but their values of a. vary considerably from those of Jette and Foote. In conjunction with Studies' on the transition from surface-controlled heterogeneous reactions involving CO-C02 oxidation of metals, lattice-parameter measurements on undoped and chromium-doped wiistite have been performed. These studies are especially needed to clarify conflicting data of previous authors, to extend the data to the stability limits of wiistite as determined by Darken and urr,6 which include a larger range of existence than that found by Jette and Foote, and to test by X-ray means the role of chromium as a vacancy producer in wiistite.

Jan 1, 1967

By Charles Y. Clayton

Cast-steel runners, while not interesting from a commercial standpoint, furnish valuable material for microscopic study. Folcyl found not only the usual ingot structure, but zones of Widmannstättian structure, which he explains as due to differential crystallization. The writer, in examining nickel-steel runners, found a type of pro-eutectoid ferrite that is unusual and most probably new. The runner in question was 8.75 cm. (3.5 in.) in diameter and analyzed at its center 2.69 per cent. nickel and 0.350 per cent. carbe a and at its edge 2.62 per cent. nickel and 0.359 per cent. carbon. Th macrostruc-ture, which is the usual type, is shown in Figs. 1 and 2, which are a cross-section and the longitudinal surface, respectively. Slight segregat'ion of ferrite can be seen near the center of the segment and at other points near the edges of polyhedral grains. Stead's reagent brings out the dendritic structure within the grains as shown in Figs. 3 and 4. This texture is what would be expected of such a steel. Figs. 5 to 10 show the peculiar swirls of pro-eutectoid ferrite, the finding of which prompted this paper. These swirls, or eddies, if such a term can be applied, occur in all parts of the runner and in all parts of the individual grains. The upper left-hand figure shows this ferrite at a grain boundary; the middle left-hand figure shows the inner portion of a grain; and the lower left-hand figure shows these swirls at the edge of a grain which is also the outer edge of the runner. Straight-lined ferrite associated with swirls is found in the areas of Figs. 11 and 12. The texture of the carbon-bearing constituent of the runner is shown to some extent in Fig. 12, the pearlite being very fine or sorbitic. Higher magnification does not bring out any new features either in the peculiar ferrite or in the pearlite. Figs. 13 and 14, at 240 diameters, show the curved and straight-lined ferrite.

Jan 1, 1922