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By B. Woyski

Many writers, in discussing defects caused by oxidation and gassing of bronzes and red brasses advocate substantially the same cure for both. But from its nature, oxidation cannot take place if there is an excess of fuel in the furnace, while the gases absorbed by some alloys are products of incomplete combustion of the fuel. Hence the metal can be either oxidized or gassed, but it is doubtful whether these actions can take place simultaneously. Oxidation can be easily overcome by the use of deosidizers or it may be avoided by protecting the molten metal with suitable fluxes. Absorption of gascs is more difficult to overcome: the regulation of the air and fuel, so as to produce complete combustion, and the protection of the bath by mineral fluxes arc the most important factors. Gas expulsion, resulting in gas holes, porosity, unsoundness, and swollen or cauliflower-headed risers, is said to have several causes. One writer1 lists the most common causes in the order of their importance, as follows: Superheated metal, dirty or slaggy furnace conditions, using metals low in quality or those previously subjected to bad melting practice, poor grade of fuel, use of newly lined or damp ladles, indiscriminate mixing of scrap or illogical combinations of metal. Superheating the metal usually occurs when the heat is ready to be poured but for some reason must be held in the furnace. In this case, a careful furnace tender tries to avoid overheating the metal by keeping a mild fire; that is, a reducing fire which, unfortunately, results in gassing the metal. A dirty, slaggy furnace may result in gassing the metal by retarding the heating and prolonging the time necessary to bring the metal to the proper temperature, thereby increasing the chances of gassing in uncertain furnace atmosphere. It is doubtful whether rnetals of low quality have anything to do with gassing molten metal, except, possibly in the case of metals containing

Jan 1, 1923

By G. D. Cremer, J. J. Cordiano

Aluminum powder is a well-known article of commerce and in various forms has been marketed widely for use in paint, for pyrotechnic purposes and for exothermic mixtures. For a number of reasons, however, aluminum powder has not been employed extensively in powder metallurgy, although a great many proposals along this line have been offered. Aluminum and alumiuum-alloy powders oxidize readily upon exposure to air and the thin film of oxide (or hydroxide) thus formed is highly refractory, in that ordinary gaseous reducing agents such as hydrogen or carbon monoxide do not reduce the oxide to metal at temperatures below the melting point of aluminum. It has been thought that the presence of these films of oxide on aluminum particles would interfere markedly in powder metallurgical work and a number of suggestions have been made, either for preventing the formation of the film through the production of the powders in inert or reducing atmospheres, or for the removal of the oxide by means of powerful reducing agents, including "nascent" or atomic hydrogen released from metal hydrides. A second and more serious difficulty in the use of aluminum and aluminum-alloy powders in powder metallurgy resides in the fact that during compression such powders tend to adhere or cold-weld to the die walls, thus interfering with the formation and ejection of a compact. A third difficulty, which has been encountered only with aluminum-alloy powders, is their hardness when compared with elemental aluminum. Certain of these powders are susceptible to age-hardening, which further hinders the formation of strong green compacts. These conditions are particularly true of atomized aluminum-alloy powders. Even in the annealed condition, plastic deformation of alloy powders under pressure is low when compared with unalloyed powders. This fact, coupled with the lower corrosion resistance of the alloy powders. is probably the significant factor in our failure to obtain strong sintered pieces. Methods of Puoducing the Powder Many methods have been proposed for manufacture of aluminum powder, only a few of which are used commercially. Several of the more important processes include: (I) atomization of the molten metal; (2) mechanical pulverization and other types of comminution; and (3) graining, in which molten aluminum is stirred during freezing. For pigment and certain pyrotechnic uses aluminum flake powder is desirable, because of its greater proportion of surface to volume; and large quantities of such material are made by a procedure that involves stamping or ball milling. In making flake intended for use as pigment,

Jan 1, 1943

By Rollin E. Hook, Attwell M. Adair

The response of CrzO3 and C~304 to various heat treatments was studied in are-melted iodide chromizim over the temperature range 1000" to 1750°C. These oxides, which are present as impurity phases in this material, were identified by X-ray diffraction teclzniques which were supplemented by optical metallop-aphy. As a function of increasing temperature, Crs04 is first observable in samples annealed at 1300°C and coexists with Cr2O3 (the low-temperature oxide) over a temperature range exceeding 200°C. As the temperature decreases, Cr3O4 dissolves with the concomitant precipttation of Cr2Y2. Both oxides precipitate predominantly at pain boundaries. The reactions which occur are involved with at least ternary equilibria, possibly due to iron which is present as an impurity in arc-melted iodide chromium. HILTY, Forgeng, and Folkman' reported in their investigation of the Fe-Cr-0 system that Cr3O4 (with about 8 pct Fe substituted for chromium) is a primary phase found in alloys with 9 or more pct Cr. They reported that this phase is stable only at high temperatures and that below the liquidus Cr3O4 is disproportionated into Cr2O3 and chromium-rich metal for both Fe-Cr-O alloys and in oxygen saturated pure chromium. Further, they proposed that CrsO4 forms by a peritectic reaction between Cr2O3 and the liquid. On the other hand, Hook, Garrett, and Adair2 found in their investigation of impurity phases formed in "pure" chromium (material consolidated from iodide chromium crystals) that Cr3O4 forms intergranularly and is stable as low as 1500°C which is 375OC below the melting point of chromium. The purpose of the research described herein is to determine the temperature range of stability of Cr3O4, and to show the nature of its decomposition. This further investigation indicates that Cr3O4 undoubtedly occurs in this material as low as 1300°C. The chromium studied was consolidated and fabricated from iodide chromium crystals (ICr-5) and contained Fe r 135 ppm, Si = 20 to 100 ppm, and 0 = 35 to 137 ppm. A complete chemical analysis is given elsewhere.' Annealing was conducted in 1 atm of purified helium and all samples were rapidly cooled (-200°C per sec) by withdrawing them from the furnace hot zone under a high flow rate of helium. The details of the electrolytic-etching technique and electrolytic-digestion techniques for preparation of insoluble residues for X-ray examination are given elsewhere also.' EXPERIMENTAL RESULTS The Starting Material. The as-swaged rod (final swaging done at 900°C) had a wrought grain structure and contained a dispersion of CrzO3 inclusions of maximum particle size of about 2 or 3 p, Fig. 1. The microstructure also contained a dispersed

Jan 1, 1964

By G. D. Cremer, J. J. Cordiano

Aluminum powder is a well-known article of commerce and in various forms has been marketed widely for use in paint, for pyrotechnic purposes and for exothermic mixtures. For a number of reasons, however, aluminum powder has not been employed extensively in powder metallurgy, although a great many proposals along this line have been offered. Aluminum and alumiuum-alloy powders oxidize readily upon exposure to air and the thin film of oxide (or hydroxide) thus formed is highly refractory, in that ordinary gaseous reducing agents such as hydrogen or carbon monoxide do not reduce the oxide to metal at temperatures below the melting point of aluminum. It has been thought that the presence of these films of oxide on aluminum particles would interfere markedly in powder metallurgical work and a number of suggestions have been made, either for preventing the formation of the film through the production of the powders in inert or reducing atmospheres, or for the removal of the oxide by means of powerful reducing agents, including "nascent" or atomic hydrogen released from metal hydrides. A second and more serious difficulty in the use of aluminum and aluminum-alloy powders in powder metallurgy resides in the fact that during compression such powders tend to adhere or cold-weld to the die walls, thus interfering with the formation and ejection of a compact. A third difficulty, which has been encountered only with aluminum-alloy powders, is their hardness when compared with elemental aluminum. Certain of these powders are susceptible to age-hardening, which further hinders the formation of strong green compacts. These conditions are particularly true of atomized aluminum-alloy powders. Even in the annealed condition, plastic deformation of alloy powders under pressure is low when compared with unalloyed powders. This fact, coupled with the lower corrosion resistance of the alloy powders. is probably the significant factor in our failure to obtain strong sintered pieces. Methods of Puoducing the Powder Many methods have been proposed for manufacture of aluminum powder, only a few of which are used commercially. Several of the more important processes include: (I) atomization of the molten metal; (2) mechanical pulverization and other types of comminution; and (3) graining, in which molten aluminum is stirred during freezing. For pigment and certain pyrotechnic uses aluminum flake powder is desirable, because of its greater proportion of surface to volume; and large quantities of such material are made by a procedure that involves stamping or ball milling. In making flake intended for use as pigment,

Jan 1, 1943

By J. W. Spretnak, V. Kandarpa

Stress -induced ordering of carbon atoms is studied in a series of Fe-Mn-C alloys. A prominent peak is found in the vicinity of 280°C at frequencies of the order of 1.0 cps, with an associated activation energy of 37 kcal per mole. The height of the peak is linearly rekzted to the concentration of carbon in solution. The distortion of octahedral holes by manganese atoms appears to be predominant over carbon-carbon pair interactions. RELAXATION by stress-induced ordering of point defects is expected whenever the introduction of these point defects produces distortions which have a lower symmetry than that of the lattice. Under zero stress, the isolated point defects occupy the crystallographic-ally equivalent positions in the lattice, as these represent states of equal energy. However, if the defect sites are asymmetric, application of an uniaxial stress will split the energy states, and a redistribution of the defects among various states will take place. This is the case of the internal friction peak called the Snoek peak,1 resulting from isolated interstitials in bcc metals. The interstitial sites in this case have tetragonal symmetry. In the case of fcc and hcp lattices, such an effect is not expected from isolated point defects because of the symmetrical nature of the interstitial sites. However, internal friction peaks arising from interstitial diffusion have been reported both in hcp2,3 and fcc4-8 lattices. These peaks are often explained on the basis of stress-induced ordering of interstitial solutes, caused by the deviation of interstitial sites from their cubic symmetry through the presence of nearby defects. In the case of fcc lattices, evidence for interactions of both the substitutional-interstitial4,6,13 and interstitial-interstitial types5'798'14 have been presented by various investigators. The purpose of the present investigation was to study the internal friction peak attributed to the diffusion of interstitial carbon atoms in high purity austenitic manganese steels and to account for the peak in the light of the existing models. MATERIALS The Fe-Mn-C alloys used in the present investigation were made in two different ways, designated as Type I and Type 11. Type I alloys were made from high purity Fe-Mn alloys obtained in the form of 0.04- in.-diam wires from Materials Research Corporation, Orangeburg, N.Y. These alloys were carburized to different levels using gas mixtures of H2 and CH4 at 1000°C. Type I1 alloys were made in this laboratory starting with zone refined iron, spectrographically pure manganese, and spectrographically pure carbon. They were melted in an argon arc melting furnace and drawn into 0.04-in.-diam wires. All the wires were annealed at about 900°C for 3 hr prior to the internal friction experiments. After the measurements of internal friction, the phases in the samples were identified by X-ray diffraction and the carbon determined by the combustion method. EXPERIMENTAL PROCEDURE In the present work, a classical Ke-type pendulum was used. The details of the equipment were described previously by D. T. Peters.9 Dry helium at 40 torr was used in all the experiments. The internal friction, measured as the logarithmic decrement of the torsion amplitude of vibration was determined as a function of temperature, from ambient to about 500°C. The background internal friction was assumed to have the form of the exponential of the inverse temperature and was subtracted from the raw data. The height of the peak was measured at the position of the maximum in the plot of the internal friction versus temperature. The activation energies of the peaks were measured by the peak shift method. The internal friction values for an alloy were obtained as a function of temperature at different frequencies of vibration. The position of the peak changes with frequency, the higher the frequency the higher the peak temperature. The activation energy of the process associated with the peak is obtained using the formula

Jan 1, 1970

By J. G. Balkestein, J. W. R. Baerts

During an attempt to develop a method for accurate, rapid, continuous analysis of ash content of wal, the Dutch State Mines Laboratory found that the absorption coefficient for X-rays was related to ash content. This relationship was utilized in the development of an apparatus called CendreX, used to measure the absorption and in turn the ash content. The principle, procedure, accuracy, and applications of the CendreX automatic determination of ash in coal are discussed in detail. Until recent years coal preparation research was concentrated on the possibilities and efficiency of preparation equipment. Ever increasing demands for quality in coal, however, have caused researchers to become concerned with quality control. One of the characteristics strongly influencing quality (calorific value) and, consequently, the price of coal is ash content. Both customer and producer require that the ash content be controlled. To make this possible it is necessary for the producer to collect samples from the coal stream in the washery and to determine their ash content. On the strength of the results obtained the production process can then be adjusted, if required. Until recently incineration was the only method for determining ash content. When coal is incinerated with oxygen, it takes at least 15 min to determine the ash content. Even then some time may be lost in passing on the data. Therefore, this discontinuous and time-consuming method does not make a suitable starting point for checking, re-adjusting, or modifying the production process. Since it was not possible to accelerate incineration by mechanization and automation, another type of rapid continuous analysis had to be found. This would have to depend on some coal characteristic closely linked with ash content. At the Central Laboratory of Dutch State Mines, Dijkstra and Sieswerda found that the absorption coefficient for X-rays was suitable for this purpose. An apparatus based on the measurement of this characteristic was developed. Named CendreX,* this patented equip- *A Stamicarbon N. V. registered trademark. ment, used in combination with a sampler and conditioning apparatus, permits continuous determination of ash content with satisfactory exactness to within 3 min.t At the American Mining Congress meeting of May 1961, Log A. Updegraff, surveying aspects of continuous analyaia, reported on the CendreX appartus (Mining Congress Journal, August 1961). Since the first Condition for correct ash determination, whatever the method used, is always a sample taken in the right way, some practical aspects of sampling will be discussed first. SAMPLING In coal handling operations, each grain has its characteristic properties. In both the cross-sectional and longitudinal direction of the product stream the mixture of these grains is imperfectly blended. The elimination of the factor of segregation between the cross-sections from the direction of the stream is the principal aim of continuous analysis. Therefore, the samples to be analyzed are withdrawn in various places from the segregated product stream in such a way that they form a semi-continuous flow. In order to be truly representative of the product stream, the sample flow must fulfil two conditions: 1) The sample flow must be sufficiently large to insure that adventitious differences between the composition of the product stream and sample flow will be as small as possible. 2) All grains through the entire cross section of the product stream must have an equal chance to get into the sample flow. Since there is always a segregation through the cross section the sample flow will have a bias if the sampler collects only part of this section. In order to prevent the volume of the sample flow from becoming too large, the cross sections are taken discontinuously. However, this discontinuity gives rise to the adventitious differences that arise between the composition of product stream and the sample flow, and these differences become greater and are more deranging as the fluctuations follow each other more quickly. Moreover, the intervals between the morrnents of sampling mean a delay in the analysis. The aim will, therefore, be to collect small samples, or in other words thin cross-sectional increments, taken at sufficiently high frequencies. The following points should also be taken into account: 1) The smallest dimension of the openings in the sample collector must be equivalent to at least 3 d in

Jan 1, 1962

By Strathmore R. B. Cooke, Paul B. Queneau

The kinetics of the dissolution of scheelite in basic solutions of carbonate and fluoride were investigated. Work was also done with solutions of alkali metal chloride, hydroxide, phosphate, and mixtures of phosphate and fluoride. The study was conducted at 90 psig and at temperatures ranging from 100" to 155"C, and both natural and synthetic scheelite single crystals were used. The interaction of scheelite with carbonate solutions generally followed a parabolic rate law, and resulted in the formation of calcite crystals on the attached surface. The transport of the CO3 through the calcite to the scheelite surface was probably rate -controlling between 115" and 135°C. Positive deviations from Parabolic behavior were observed at 100" and 155?C, presumably due to the calcite grain growth, and to the formation of a noncoherent calcite layer, respectively. The leaching of scheelite with alkaline fluoride solution produced a calcium fluoride reaction-product which covered the surface as a sheet-like layer. Below 110°C the dissolution rate was parabolic; at 115" and 135°C it was linear. In the linear region, the periphery of the calcium fluoride layer lifted from the sample. Only the lower layers, braced by the scheelite substratum, remained unbroken. This bound layer, approximately constant in thickness, limited the rate at which the fluoride could attack the scheelite. The phosphate and phosphate-fluoride leaches dissolved scheelite at a linear rate; solid reaction products were respectively hydroxyapatite and fluorapatite. Sodium hydroxide and chloride were not effective leachants, and did not produce observable solid reaction products. THE feasibility of pressure leaching of scheelite pulps with basic solutions containing either carbonate or fluoride ions, as indicated by the following equations, has been established by previous investigators:1-3 200°C CaWO4s + CO37q - CaCO3s+WO4aq [1] 200°C CaWO4s + 2Faq ^ CaF2s+WO4aq [2] It is to be noted that a commercial process employing reaction [I] is in use at Union Carbide's operation near Bishop, Calif. In the earlier work referred to, it was apparent that the precipitation of the solid reaction-product on the scheelite particles sharply reduced contact of the leachant with the scheelite. We have extended this work by studying the kinetics of dissolution employing single crystals of scheelite of known exposed surface area. In addition, the effectiveness of solutions of phosphate, of phosphate with fluoride, and of chloride and hydroxide as leachants for scheelite have been investigated. EXPERIMENTAL Apparatus. The low-pressure autoclave used in this wo (100 psig maximum) is essentially that of J. Halpern4 as modified by F. A. Forward.5 Constructed entirely of 316 stainless steel, its maximum capacity is 4000 ml. The temperature in the autoclave was regulated to *0.5?C by a Wheelco thermocouple controller. A 4-in. diam, three-bladed impeller, circulated solution upward against the sample, and a strobo-scope permitted holding the stirring rate to *15 rpm. A check valve and a "pop" type safety valve were installed, a sample holder was fixed to an externally adjustable rod, and a water-cooled condenser was placed in series with the sampling valve. The stainless steel sample holder, Fig. 1, held the epoxy-mounted sample (f) five mm above the impeller. Tightening the tapered sleeve (d) positioned the epoxy-resin specimen-mount by forcing it back against the spacer (c). The mount (e) was 1 in. diam. Sample Description and Preparation. Both synthetic and natural scheelite crystals were leached. The former were single crystals of 99.95 pct purity which were leached approximately perpendicular to the "c" axis; they were supplied by the Gallard-Schlesinger Chemical Manufacturing Corp. The natural crystals, supplied by Minerals Unlimited, were transparent, analyzed 99.8 pct CaWO4, and in ultraviolet illumination exhibited the characteristic blue glow of substantially molybdenum-free scheelite. To permit exposure of an essentially constant surface area of scheelite to the leachant, the samples were mounted in Scotchcast Brand Resin No. 250 (Minnesota Mining and Manufacturing Co.). The mount-

Jan 1, 1970

By W. A. Hockings, M. E. Volin, A. L. Mular

Batch grinding tests at short times were made in a laboratory rod mill with 10 x 14 mesh quartzite in corn syrup-water mixtures of varying viscosity. The weight fraction broken and size modulus were found to be independent of viscosity up to 20 cp, but at higher viscosities breakage of the feed decreased while the size modulus increased. The mechanisms of the effect of viscosity are discussed on the basis of particle dynamics. The effect of viscosity of the suspending medium on grinding has not been accorded much attention, although both wet and dry grinding are used in bene-ficiation processes and the viscosities of water and air differ greatly. schweyerl investigated the rates of grinding of quartzite in a pebble mill with air, water and glycerol as the suspending media and found the rate in terms of new surface developed per thousand revolutions of the mill to be constant and dependent on viscosity up to 20,000 rev, but to decrease and become independent of viscosity for longer grinding times. Based on considerations of the drag forces exerted on suspended particles and on the grinding media under turbulent and laminar flow conditions, viscosity can be expected to inhibit the rate of grinding in a given system as it changes the flow conditions from turbulent to laminar. The objective of this study was to determine the effect of viscosity of the suspending fluid in the batch grinding of a homogeneous feed of uniform size for short residence times, a region of more practical interest than the long times investigated by Schweyer. In actual grinding operations, the viscosity of the fluid does not change, but the consistency (apparent viscosity) of the pulp increases with additions of fines. In this study the consistency of the pulp was not measured because it was thought that the grinding times were too short to alter the apparent viscosity appreciably.* *Minus 200 mesh quartz at 65% solids has an apparent viscosity of about 25 cp as measured by a simple consistometer. Personal communication from D. F. Kelsall to A. L. Mular. For the purposes of this study, the effect of viscosity on grinding can be shown sufficiently well on the basis of the cumulative weight fraction finer than the feed size at any time, and the size modulus, ku, of the finer than feed sizes. The parameter, ku, is obtained from a form of the Gaudin-Schuhmann equation. METHOD AND MATERIAL The grinding tests were accomplished in a laboratory rod mill 10-1/2 in. long and 8 in. bore with a 20-lb rod charge consisting of two 1-in., eight 3/4-in., eight 1/2-in., and eight 1/4-in. diam rods. The mill speed was 43.2 rpm. Charges of 400 g 10 x 14 mesh Wisconsin quartzite** were ground for times of 60, **Courtesy of Minnesota Mining and Mfg. Co. 120, 180 and 240 sec in 500 cc of fluid made up of corn syrup and water in measured proportions. The temperature of the pulp was measured immediately upon completion of grinding, and the size distribution of the quartzite was determined by a wash-wet-dry screening technique. Corn syrup was chosen because of its high viscosity and ideal viscous behavior, and also because its density is not greatly different from that of water. The viscosity of each fluid mixture was measured with an Ostwald viscometer at 25 C. and a correction was made for the temperature of the pulp according to tabulated values for sucrose solutions. The density differences were so small that they probably did not significantly affect breakage. RESULTS AND DISCUSSION The conditions of the grinding tests, computed viscosities, weight fractions finer than the feed size and values of a and ku are listed in Table I. The values of a and ku were taken from the linear portions of the log-log plots of cumulative weight fraction finer vs size for the various grinding times. The plots for tests in fluids of average viscosity 8.6 cp are shown in Fig. 1. In general all of the sets of curves were linear throughout most of the size

Jan 1, 1965

By George S. Evans

Certain American operators bclieve that desulphurizing in the ladle offers a means of increasing blast-furnace and open-hearth yields with the possibility of improvements in quality of the steel. In fact, several producers have experimented with practically all of the known desulphurizing agents, including both standard grades of the alkalies and special preparations that have been offered from time to time during the past several years. Some of these are regularly being used today in large-scale commercial operations, with good results. Also, it is the practice to treat off-sulphur casts in the blast-furnace ladle at a number of plants. It is not known, however, that anyone in the steel industry (American) has ever adequately equipped a plant for desulphurizing blast-furnace metal in an efficient manner as regular operating practice. The purpose of this paper is to illustrate the importance of correct equipment and proper handling for obtaining uniform and efficient results. As will be shown, at the temperature of molten iron the alkalies are instantly neutralized by any free slag present, dissipating their desulphurizing value. Entrained silicates are rapidly washed out of the metal bath by the highly basic soda slags and will be satisfied ahead of desulphurizing reactions with FeS. More or less of the reagent will always be used up through reactions with the refractory lining. Desulphuriza-tion will be limited to the action of the free alkali then remaining in the slag. Causes for the erratic results generally found with desulphurizing tests in blast-furnace transfer ladles would include, among other things, variations in the quantity of furnace slag coming down with the metal, and differences in the percentage of kish and entrained silicates in the different casts. As the alkalies instantly unite with any free slags or silicates present, these, with any kish coming off, both dilute the reagent and reduce the surface contact between the slag and metal, thereby retarding the desulphurizing reactions.

Jan 1, 1938

By B. Otto Pixler

Mud-analysis logging provides identification of the fluid content of formations drilled by the rotary method and permits the accurate correlation of oil and gas shows with the depth. Mud-analysis logging eliminates much coring and has an especially important application in drilling programs when coring is particularly hazardous or the electric log is difficult to interpret correctly. An appreciation of the factors that influence the results of the mud analysis, such as rate of penetration, mud properties, coring, and characteristics of reservoir rock as related to the "flushing effect," permits a better understanding of the mud-analysis log. Recent studies of the relationship of the two gas readings obtained by the gas-detector instrument have proved significant. The difference between the total combustible gas reading and the higher molecular weight gas reading indicates the presence of methane. With few exceptions, zones not showing an increase of methane probably can be condemned. Mud-analysis logging furnishes valuable information, which generally cannot be obtained by other methods. Introduction Logging by mud analysis of wells drilled with rotary tools is a direct method of locating oil-and-gas-bearing formations. The use of this method of logging has increased each year until now more than 20 field units are being used in 13 oil-producing states and in some foreign countries. Several papers1-9 have been published in the petroleum trade journals describing in detail the equipment and the application of mud-analysis logging. This paper will discuss briefly the method and review its application and some of the late developments. Method As the drilling of a well progresses, the drilling bit dislodges and disintegrates a cylindrical section of the formation. If oil or gas is contained in the pore spaces of the cylinder, some of the contents of these porous spaces will be entrained in the drilling fluid. In wall logging by mud analysis, the mud is continuously examined for oil and gas on its return to the surface, and the results are correlated back to the actual depth of the hole at the time the mud was clearing the eyes of the bit. The test for gas is made by diverting a portion of the circulating mud from the flow line to a separator or gas trap, where the mud is thoroughly mixed with air and a portion of the gas entrained in the mud is removed. A stream of air is drawn coun-tercurrent to the flow of mud in the gas trap, thus materially assisting the separation of the gas from the mud. The air-gas mixture is then drawn into a "hot-wire" gas-detector instrument where the percentage of the combustible gas is determined. The presence of oil in the formation drilled is detected by a physical examination of the drilling mud under ultraviolet light. A sample of the mud is treated to reduce the surface tension and gel strength, after which it is placed in a viewing box. This box is so constructed that all external light is excluded and so that the sample may be subjected selectively to either ultra-

Jan 1, 1946

By George S. Evans

Certain American operators bclieve that desulphurizing in the ladle offers a means of increasing blast-furnace and open-hearth yields with the possibility of improvements in quality of the steel. In fact, several producers have experimented with practically all of the known desulphurizing agents, including both standard grades of the alkalies and special preparations that have been offered from time to time during the past several years. Some of these are regularly being used today in large-scale commercial operations, with good results. Also, it is the practice to treat off-sulphur casts in the blast-furnace ladle at a number of plants. It is not known, however, that anyone in the steel industry (American) has ever adequately equipped a plant for desulphurizing blast-furnace metal in an efficient manner as regular operating practice. The purpose of this paper is to illustrate the importance of correct equipment and proper handling for obtaining uniform and efficient results. As will be shown, at the temperature of molten iron the alkalies are instantly neutralized by any free slag present, dissipating their desulphurizing value. Entrained silicates are rapidly washed out of the metal bath by the highly basic soda slags and will be satisfied ahead of desulphurizing reactions with FeS. More or less of the reagent will always be used up through reactions with the refractory lining. Desulphuriza-tion will be limited to the action of the free alkali then remaining in the slag. Causes for the erratic results generally found with desulphurizing tests in blast-furnace transfer ladles would include, among other things, variations in the quantity of furnace slag coming down with the metal, and differences in the percentage of kish and entrained silicates in the different casts. As the alkalies instantly unite with any free slags or silicates present, these, with any kish coming off, both dilute the reagent and reduce the surface contact between the slag and metal, thereby retarding the desulphurizing reactions.

Jan 1, 1938

By N. I. Fisher, J. Shepherd

Abstract-Statistical studies have been carried out on structural geological data collected across a large zone of roof failure 600 m (1968 ft) wide and at least 800 m (2642 ft) long in the Greta coal seam at Aberdare East Colliery. Two swarms of hundreds 2 of minor, normal faults with throws commonly between 3 and 300 mm in the room and pillar workings are broadly coincident with roof failure. The faults have been classified into dip slip and oblique and strike slip types. Roof conditions have been classified into good; troublesome with subclasses scaly, heavy, gutter falls and wide, flat-roofed falls; and severely failed with subclasses very heavy roof, gutter falls and dome falls. Troublesome conditions are defined as those in which the height of the fall is less than or equal to 0.3 m, and severely failed conditions as those in which the fall height is greater than 0.3 m. Comparison of faults, roof conditions and mining rate on a shift basis indicates that faults and roof failure are much more important than machine breakdowns in reducing mining rate. The effect of faults on roof conditions has been quantified using a concept called the "zone of influence, " a rectangular area around a fault in which the fault has potentially deleterious effects. The spatial comparison of fault "zones of influence" with areas of roof failure using Spearman's rank correlation coefficient shows that, while normal dip slip faults do not appear to be associated with roof failure, oblique slip and strike slip faults appear to be associated with roof classed as severely failed. The "zone of influence" of an oblique slip fault may extend up to 3 m on each side of it in the headings and up to 1.14 m in the cut-throughs. The fault "zone of influence" has geomechanical implications for the design of mine openings and possibly represents the maximum length of a cantilevered roof beam likely to fail during mining, owing to a fault. Roof conditions could possibly be predicted in blocks of virgin coal if the type of fault could be identified in oriented drill cores.

Jan 9, 1978

By O. W. Ellis

In view of the extensive use of the brasses and bronzes in engineering practice it is indeed surprising that so little scientific work has been done on the oxides in these alloys. Recognition of the ill effects of these compounds is universally accorded, both in foundry procedure and in such specifications as cover the melting of these useful mixtures. In the latter, limits, for example, are placed on the proportions of scrap metal In the charge, and clauses governing the use of fluxes are included, the addition of fluxes to the charge being made with the object of avoiding oxidation during the process of melting and of subducing and separating non-metal-lic matter from the melt.1 In the manufacture of brass it occasionally, though rarely, occurs that the virgin metals, copper and zinc, alone arc used. In the event of virgin metals being employed, that of the higher melting point is always melted first. If it is melted under suitable conditions, little or no oxidation will occur. Whether oxidation has occurred or not, however, can best be determined by microscopic examination of a sample taken from the melt. Avoidance of Oxidation in Furnace Practice When melting virgin copper in crucible practice, the avoidance of oxidation is not difficult, nor is it hard to forestall trouble in the electric furnace. In gas-fired furnaces of the barrel type, however, the avoidance of oxidation is almost impossible, no matter what the condition of the flame, the flux employed, or the amount of charcoal included in the charge. Copper melted in furnaces of this type is almost invariably so highly oxidized as to requirc very considerable additions of such deoxi-dizers as, for example, silicon copper to render it free from cuprous oxide. As a result,, the castings produced are decidedly inferior, on account of the. large amount of silica which is engendered in the metal as a result of the reaction, Cu2O + Si = SiO2 + 2Cu. The deoxidation of such oxidized copper could, of course, be effected by means of zinc with, however, even more disastrous results.

Jan 1, 1930

In the 100' years since AIME was founded in 1871, the Institute has issued a great many publications in a variety of forms: periodicals, Transactions volumes, and special volumes or books. The following is a brief history of AIME publishing with some suggestions for proper referencing. TRANSACTIONS AIME Transactions volumes have been numbered consecutively since No. 1 was issued in 1873, including papers for the period 1871-1873. One or more volumes have been issued each year and may be divided into three general time periods: General Volumes (1873-1927), Volumes classified by subject matter (1928-1949), and the present practice, begun in 1949, of issuing three volumes per year, one each in the fields of mining engineering, metallurgy, and petroleum technology. The broad divisions of subject matter in each of these volumes correspond to the technical areas of the three constituent societies of AIME. AIME's Technical Publications, usually designated by TP number's (until the change in numbering system by the Society of Mining Engineers in 1958), may, with some exceptions, be referenced to an AIME Transactions volume. Reference to a specific volume, rather than paper number, is the preferred reference, since the volumes are the form of publication most commonly available in libraries. In many cases, over the years, the Technical Publications may also have been available in some other form, either as separates or in a periodical. General. Volumes (Vols. 1-78, 1873-1927): Until 1927 all papers eligible for Transactions were published in general volumes with no systematic attempt made to segregate the material on the basis of the technological fields to which the papers related.. One volume per year was issued from 1873 until 1912; from 1912 until 1927 from two to four volumes were issued annually. In addition to the Transactions papers, these volumes carried some of the proceedings of the business meetings of AIMS. Subject Volumes. (Vols. 79-183; 1928-1949): The material for these volumes was segregated according to subject matter, and up. to seven volumes were issued a year. In the latter part of the period, from 1934 on, there was one volume each' year for the Petroleum, Institute of Metals, and Iron and Steel Divisions and-the remaining papers were grouped in various ways and is sued whenever sufficient numbers of papers had accumulated: The subject volumes containing mining engineering papers are listed in Table 1. The volumes for the period, 1936-1949 are included in this Cumulative Index. Each of the Transactions volumes carries on the binding the year of publication; this date does not give an indication of when the papers included were originally presented at meetings. The contents of the volumes usually list the meetings at which. the papers were presented. Not all papers from a given meeting necessarily are in one Transactions volume. Some of the earlier volumes do not have a number on the binding or within the volume. In 1934 numbers" were assigned to all Transactions volumes, commencing with the 1871-1873 volume as No. 1. Many of the papers published [ ]

Jan 1, 1972

By B. Otto Pixler

Mud-analysis logging provides identification of the fluid content of formations drilled by the rotary method and permits the accurate correlation of oil and gas shows with the depth. Mud-analysis logging eliminates much coring and has an especially important application in drilling programs when coring is particularly hazardous or the electric log is difficult to interpret correctly. An appreciation of the factors that influence the results of the mud analysis, such as rate of penetration, mud properties, coring, and characteristics of reservoir rock as related to the "flushing effect," permits a better understanding of the mud-analysis log. Recent studies of the relationship of the two gas readings obtained by the gas-detector instrument have proved significant. The difference between the total combustible gas reading and the higher molecular weight gas reading indicates the presence of methane. With few exceptions, zones not showing an increase of methane probably can be condemned. Mud-analysis logging furnishes valuable information, which generally cannot be obtained by other methods. Introduction Logging by mud analysis of wells drilled with rotary tools is a direct method of locating oil-and-gas-bearing formations. The use of this method of logging has increased each year until now more than 20 field units are being used in 13 oil-producing states and in some foreign countries. Several papers1-9 have been published in the petroleum trade journals describing in detail the equipment and the application of mud-analysis logging. This paper will discuss briefly the method and review its application and some of the late developments. Method As the drilling of a well progresses, the drilling bit dislodges and disintegrates a cylindrical section of the formation. If oil or gas is contained in the pore spaces of the cylinder, some of the contents of these porous spaces will be entrained in the drilling fluid. In wall logging by mud analysis, the mud is continuously examined for oil and gas on its return to the surface, and the results are correlated back to the actual depth of the hole at the time the mud was clearing the eyes of the bit. The test for gas is made by diverting a portion of the circulating mud from the flow line to a separator or gas trap, where the mud is thoroughly mixed with air and a portion of the gas entrained in the mud is removed. A stream of air is drawn coun-tercurrent to the flow of mud in the gas trap, thus materially assisting the separation of the gas from the mud. The air-gas mixture is then drawn into a "hot-wire" gas-detector instrument where the percentage of the combustible gas is determined. The presence of oil in the formation drilled is detected by a physical examination of the drilling mud under ultraviolet light. A sample of the mud is treated to reduce the surface tension and gel strength, after which it is placed in a viewing box. This box is so constructed that all external light is excluded and so that the sample may be subjected selectively to either ultra-

Jan 1, 1946

By Paul J. Sirkegian

A detail of the guide rollers is shown on Fig. I; and Fig. 2 shows a photograph of a guide roller that has been in service for several months on the haul-back cable. The former practice of supporting and guiding the haul-back cable on slusher hoists at Kimberly was accomplished by using the conventional type of snatch-block pulley, but it was found that an excessive amount of cable whipping and unreasonable wear on both rope and pulley resulted from this type of cable support. The guide, which is wholly made in the Corporation's shops, consists of two vertical and one horizontal roll assembled in a frame that is lagged to the cap timber in a slusher drift. In some slusher drifts more than one guide-roller assembly is used, depending upon the length of the drift. The installations usually are placed at 30-ft. intervals. We have found by actual experience that these rollers have increased the life of the haul-back cable approximately 200 per cent, as compared with the usage of the conventional sheave-block pulley. Cable Care The underground rigging crew and the slusher operators are trained in rope splicing. No cable clamps or knots are permitted on slusher cables and all cable "eyes" are spliced. The standard practice has been to use preformed cables of ?-in. diameter for haulage and ½-in. diameter for the haul back. The preformed cables have proved to be important factors for safety in use and speed in making splices. No external lubrication is used on the cables. It has been found that dry ropes have about 400 per cent longer life than those that were lubricated under these operating conditions. An accurate record is kept of all cable life and the tonnage moved by the slushers in each working place, and if the rope wear is excessive in any particular working place, an investigation is made to determine the reason. Wire-rope Sling for Snatch-block Anchor The rope sling is shown by Figs. 3 and 4. These slings support the snatch-block pulley for the haul-back rope. The standard practice at Kimberly is to use a roller-bearing snatch-block pulley 10 in. in diameter. The snatch-block housings are equipped with a clevis attachment in preference to swivel hooks, as it has been found that the more rigid clevis keeps the cable in better alignment. The snatch blocks are hung from the cable sling, which is wrapped around the posts of the drift sets as shown on Fig. 3. This method of anchoring the pulley provides better anchorage and flexibility than those of the rigid or spring-mounted types. When the slusher-drift headings are being advanced, the snatch blocks are hung from a "gin" pole ahead of the last set of timbers' An employee is assigned on each production shift to take care of the lubrication of all slusher hoists that are being used and he is provided with tools for minor repairs.

Jan 1, 1946

By F. H. Deily, L. W. Ledgerwood, J. E. Eckel

A new method for drilling the earth's formations has undergone extensive laboratory and shallow earth drilling experimentation. This method, pellet impact drilling, uses the energy of a large mass of high velocity steel spheres to break and crush the rock. Pellets are confined to a region close to the hole bottom. Motive fluid for transporting and recycling the pellets is supplied by a modified jet pump. The pellet drilling method has inherent advantages over conventional rotary drilling. First, only a nominal amount of weight need be applied to the hole bottom. Second, only a very small amount of torque is required for bit rotation. Third, means are available for continual replacement of the cutter medium. The experimental laboratory work and analytical procedures necessary for the design of a pellet drill bit are described. In the laboratory program approximately half the effort was devoted to the development of a better understanding of the physical process, and half to the empirical testing of new bit configurations. Factors such as pellet size and velocity, jet pump characteristics and modifications, and power distribution are discussed. The design and construction of a pellet impact bit for drilling a 9 in. hole with 1 1/4 in. steel pellets are described. Drilling performance in representative rocks, hydraulic operating characteristics, and metallurgical problems are discussed. INTRODUCTION This paper discusses an attempt to reduce drilling costs through the development of a drilling method basically different from rotary drilling. Publications on drilling research indicate that the major effort on the part of manufacturers and operators has been confined to research in rotary, or rotary-percussion drilling. This applied drilling research has produced significant gains in drilling rates and bit life, but thus far it has failed to achieve any major decrease in general drilling costs. From recent statistics released by Drilling Contractors, it can be shown that the total cost of drilling an "average" well in 1953 was about 2 1/4 times the corresponding cost in 1935. Analysis of the costs will show that they are not due to inefficient field operations; they are due instead to both an inflated economy and greater "average" well depths. Diligent work by the industry has reduced the backlog of potential economic improvements in rotary drilling to a group of rather marginal prospects. Increasing depths and poorer quality reservoirs at these depths continue to make the drilling cost problem more acute. Hence, the aim of the work reported here was to develop a new drilling method not limited by the inherent characteristics of rotary drilling and thus capable of attaining further significant reductions in drilling costs. The effort devoted to research on this proposed new drilling method was of considerable magnitude and represented .in excess of 37 man-years of research. The affiliates of Standard Oil Co. (N. I.) sponsored this development program which was conducted by the Drilling Methods Section of the Carter Research Laboratory in Tulsa, Okla. The purpose of this paper is to

Jan 1, 1957

By C. L. Prokop

A laboratory investigation has been made of the effects of mud hydraulics upon the formation and erosion of mud filter cakes. The tests were conducted to simulate drilling conditions as nearly as possible. The formation of mud filter cake in a drilling well does not proceed at a uniform and unbroken rate. Instead, the rate of cake accumulation depends upon whether or not the mud is being circulated. If the mud column is quiescent, filter cake formation is a smooth function of the filtration characteristics of the system. If the mud is being circulated filter cake formation depends not only upon the filtration characteristics of the mud but also upon the erosive action of the flowing mud column Filter cakes formed during continuous mud circulation were observed to reach an equilibrium thickness after several hours' circulation. Mud circulation was maintained at a constant volumetric rate throughout each experiment. The fluid velocity at equilibrium cake thickness was dependent upon the thickness of the filter cake. Muds having exceptionally high water loss deposited thick filter cakes in spite of very high eroding velocities. The muds having good filtration characteristics deposited thin filter cakes at equilibrium circulating velocities well within tile range of those in a drilling well. It was observed that filter cakes deposited during stagnant filtration were quite difficult to erode by mud circulation. The - rate of crosion computed from the rate of filtrate accumulation after equilibrium cake thickness had been reached was in reasonable agreement with the rate of erosion obtained by direct observation. Continuous mud circulation usually caused the permeability of the filter cake to decrease with time. INTRODUCTION Many of the difficulties encountered during tile drilling of a well have been attributed to the loss of water from the mud and the attendant deposition of solids upon the walls of the hole. Past experience has shown that a reduction of the filtration rate of the drilling fluid eliminates or greatly reduces these difficulties. Definite filtration requirements, however, are hard to establish for a given set of conditions. This is due. in part, to the fact that the usual filtration test performed upon mud doe? not simulate well conditions as closely as desirable. The filtration characteristics of a mud are customarily determined by means of the standard low-pressure API wall-building tester.' In this instrument a filter cake is deposited upon a horizontal bed under a pressure differential of 100 psi. The rnud is quiescent during the filtration period. In actual practice. mud filtration occurs within a well under quite different conditions. One of the major differences is that mud flows upward across the filter bed as the filter cake forms. This undoubtedly produces a change in the filter cake which cannot be reflected in the results of the API test. The laboratory work described in this paper had as its primary objective a better understanding of the influence of mud circulation upon the thickness and ,characteristics of the filter cakes deposited under conditions similar to those existing in a drilling well. ANALYSIS OF PROBLEM Once a permeable formation is penetrated by the bit, filtrate from the mud flows into the formation. 'he mud solids plaster against the walls of the hole, forming a filter cake. If the mud column is stagnant, that is, if it is not being circulated. the filter cake will increase in thickness until the hole is filled. Prior to the time that the hole is filled, the thickness of filter cake existing at any given time will be a function of the filtration characteristics of the mud, the temperature, and the pressure differential. The effects of these variables have been investigated in the past for both flat bed filtration2'3 and for radial filtration.' When the mud is circulated in a hole in which a filter cake i. being deposited. some of the solids that would ordinarily deposit in the filter cake will be carried away by the eroding action of the mud. This will limit. filter cake thickness. Some work has been done to determine the effect of flow upon the filtration rate in a circulating mud system' but little work has been done upon the factors which determine the filter cake thickness existing in a circulating system. On first sight it would appear that the major factors controlling filter cake formation in a circulating system should be: 1. The rate of deposition of solids from the mud. 2. The erosive force that the flowing mud exerts upon the filter cake. 'A. The erodabilitv of the filter cake. 4. Any change in filter cake characteristics attributable to the scouring action of the mud. The rate at which solids are deposited from the mud will be controlled to a large degree by the filtration characteristics of the mud, the pressure differential. the temperature under

Jan 1, 1952

By N. J. Grant, C. C. Wang

The Ti-Cr-O ternary system has been studied in detail near the titanium-rich corner within the limits of 10 wt pct 0, and 20 wt pct Cr. Studies were extended, but not in detail, to the region beyond 25 wt pct 0, (50 atomic pct) and 62 wt pct Cr (60 atomic pct). Four isothermal sections at 1400°, 1200°, 1000°, and 800°C are presented as well as two vertical sections at 1 and 2 wt pct 02. DURING the last decade much interest has been shown in the development of high strength titanium alloys for high temperature and corrosion resistant applications. Extensive research is being carried out at present, as the current literature indicates, in order to study the properties of titanium and to develop improved alloys. Two of the important alloying elements in commercial titanium alloys are chromium and oxygen and it would be desirable to know their combined influence upon titanium. For this purpose the present work was carried out to investigate the titanium-rich corner of the ternary system TiICr-0. The binary systems Ti-Cr and Ti-0 have been published recently. The Ti-Cr system was studied by several investigators " and their results are in close agreement. The eutectoid decomposition of the B phase has been shown to be extremely sluggish. TiCr, was the only intermetallic compound found in this binary system and was formed at 1350°C by a transformation from the p phase. TiCr? was established as the cubic C 15 (MgCu,) type of structure with 24 atoms per unit cell and was designated as the y phase. This terminology will be adopted in the present work. There was disagreement about the actual composition of this compound among the several investigators, although it is evident from their data that the compound probably has a solubility range of about 2 to 3 pct and is in the vicinity of 65 pct Cr. It has been indicated recently that a high temperature modification of this y phase (TiCr,) existed at a temperature above 1300°C." ' This high temperature modification was identified as a hexagonal C 14 (MgZn,) type of structure with 12 atoms per unit cell. The exact transformation temperature from the high temperature phase to the low temperature phase has not been established. A considerable hysteresis was observed and, due to the sluggishness of this transformation, the high temperature phase often co-existed with the low temperature phase at temperatures below 1300°C. A preliminary study of several Ti-0 compounds and the Ti-0 system had been carried out by Ehr-1ich."-"' The most complete binary Ti-0 system was the one reported recently by Bumps, Kessler, and Hansen." The first intermediate phase found in the system was the 8 phase which formed by a peritec-toid reaction of the phases a and Ti0 at temperatures below 925 °C. This reaction is extremely sluggish. The structure of this 8 phase was tentatively identified by these authors as being tetragonal and the lattice constants were found as c,, - 6.645A, a,, = 5.333A and c/a = 1.246A. Experimental Procedure The raw materials used for this investigation were TiO,, electrolytic chromium, iodide titanium, and sponge titanium. The TiO, was in the form of powder of chemically pure grade (99.8 pct pure). The chemical analysis of the electrolytic chromium was: 0, 0.50 pct; Fe, 0.07; Cu, N, and C, 0.01; and Pb, 0.001. The oxygen in the chromium was calculated as part of the final oxygen content of the alloys. The alloys were prepared by the cold crucible method using a tungsten arc. The entire system was evacuated and flushed with purified helium three times and then filled with helium. Each alloy was melted, turned over, and remelted at least four times to insure homogeneity. The total melting time was generally from 6 to 10 min. A master alloy of 25 pct 0,-75 pct Ti was prepared to facilitate alloying by melting compacts of TiOl powder with either iodide or sponge titanium, yielding the compound TiO. It was found necessary to bake the TiO, powder compact at about 150°C to remove adsorbed moisture. This was done to prevent the disintegration and spattering of the compact when the arc was struck. TiO, powder dissolved quite readily into the melt and no other trouble was encountered.

Jan 1, 1955

By R. P. Heuer, Paul M. Tyler

THE literature on refractories, although fairly extensive, is so scattered through books and periodicals as to be difficult of access to the general reader and most of the individual papers serve merely to illuminate some particular phase of the industry. Two general treatises by American authors8.16 are available, also the somewhat older works by a well-known British authority, 12,13 but these make their appeal to the technically minded ceramic engineer. Another small group of publications deals with the use of refractories, mainly in the iron and steel industry.1, 3,5,6,11,15 Raw materials utilized by the refractories industry have been covered by sundry books and articles. For the relatively nontechnical reader and economist, however, there appears to be no single review that purports to describe the industry as a whole. Furnace linings and other products that are classed as "refractories" are designed primarily to withstand high temperatures but this important property is by no means the only requirement; a suitable refractory material must likewise withstand slagging (chemical' action), abrasion (physical wear), and spalling, as well as the various other stresses and physical phenomena induced by heat, of which softening or incipient melting is only one phase. Nevertheless, subject to these highly practical considerations, the definition of a refractory material is based upon temperature resistance. Broadly speaking, any material that shows obvious signs of fusion after being heated slowly to 1500°C (2732°F) cannot be classified as a refractory material. The characteristic properties and requirements of refractory materials are conveniently summarized in Fig 1, prepared on the American Refractories Institute Fellowship at Mellon Institute, Pittsburgh, Pennsylvania. Most of the factors of service and properties of refractories given in this chart are interdependent and are greatly affected in degree by the functions of temperature and time. The factors in the chart are believed to cover the commoner questions.

Jan 1, 1949