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By M. H. Childs, K. E. Merklin

Blast furnace feed specifications are being revolutionized because of the large increase in iron pellet production from low-grade ores of the Lake Superior region. Recent laboratory findings aimed at a better understanding of factors influencing the physical quality of pellets produced from taconite concentrates are reviewed. Tests for determining better product quality, the effects of additives, and production factors are discussed. The current revolution in specifications for blast furnace feed is typified to a great extent by the recent tremendous growth in iron ore pellet production from low grade ores of the Lake Superior region. Indeed, pellets are responsible, at least in part, for many of the stringent new requirements that are being placed on the suppliers of furnace raw materials. As the tonnage of pellets going to the steel mills increases, more and more attention is being turned to the detailed characteristics that make this product an ideal blast furnace feed. Control of quality in pellets is similar to that of any other product. A basic understanding of the factors that are encountered in their production, from the crude ore through to the finished product, is required, along with careful process supervision and frequent quality checks. Normally, chemical grade is not a problem. This usually can be controlled within the desired specifications by minor operating variations in the con- centrator. While future changes in requirements may result in the need for self-fluxing pellets1 or other chemical changes, today's quality demands center primarily around the physical characteristics of the pellets. It is in this area that many of the recent laboratory studies have proven helpful to the operating plants. A better understanding of the physical factors involved in pelletizing has provided the basis for a continuing program of quality improvement. Tigerschiold and Ilmoni2 and Cooke with various associates are responsible for the development of much of the basic understanding of the pelletiz-ing process. These earlier findings have served as a most useful background for this work. LABORATORY PROCEDURES Magnetite concentrates produced from eastern Mesabi Range magnetic taconites were used for all of the work reported herein. The sizing and chemical analysis of a random sample are shown in Table t Additives usually are mixed with the concentrates in taconite plants before pelletizing to improve the strength characteristics of the unfired balls. Ben-tonite, soda ash, and coal are in common use. The bentonite used in these studies was of the Wyoming sodium type; the soda ash was a standard commercia1 brand. Anthrafines were used where coal was called for. The procedure for making batches of balls at the Hibbing Laboratory is as follows: In an especially designed mulling equipment 2800 g of dry ore are mixed for 10 min with the desired additives. Water is added and mixing continued for 1 1/2 min. The charge is removed from the muller and put through a mechanical shredder to break down any lumps that may have formed. sixty previously formed seed balls are placed in the balling drum, which is in fact a 6 x 16-in. diam airplane tire turning at 53 Wm. Two thousand grams of the shredded concentrate and additive mix are fed by hand into the tire at a con-

Jan 1, 1961

By P. J. Burkhardt, L. V. Gregor

The oxidation kinetics of single-crystal silicon has been investigated using extremely dry oxygen as the oxidant. Two techniques were used. The first involved a flow system with which incremental thickness measurements were made. This sytem provided an oxygen ambient at atmospheric pressure which had a moisture content of less than 0.1 ppm of water. The second technique involved measuring the change in volume of oxygen with time in a closed system. A temperature range of 900O to 1200 "C and a pressure range of 20 to 760 Tory were covered. Both techniques showed that a simple parabolic rate law holds only at the higher temperatures. At lower temperatures, the data up to 5000Å can be fitted well to a linear-parabolic equation. The two constants in this rate equation are examined in terms of a physical model. The parabolic portion of the low-temperature oxidatLon fits along the high-temperature curve of an Arrhenius plot. The parabolic rate constant for the flow-system technique can be expressed by k = 2 x 10-9 exp (L 31 kcalRT) sq cm per sec. The manostatic technique gave k = 1 x 10-exp (- 23 kcalRT) sq cm per sec. By extending the thickness range to over 104. a rate law of X = At seems to fit all of the data better than the linear-Pavabolic law. Here the exponent n increases from 0.518 at 1150 V to 0.637 at 900°C. PASSIVATION of silicon planar devices through thermal oxidation is of such great importance that considerable effort has been devoted to the study of the process.17 Much of this work involves hydrothermal oxidation, in which H2O is the oxidant: whereby H2 is produced. It has been proposed that the reaction proceeds by the formation of Si-OH groups and hydroxyl diffusion through the film to react with the silicon surface. Thus, the silicon oxide layer probably contains residual hydrogen in some form after oxidation in H2O and it has already been established that hydrogen has a marked effect on the electronic properties of oxide-passivated silicon surfaces. Silicon is oxidized by oxygen at elevated temperatures; but the rate of oxide formation is considerably lower than that for 0." By using dry O2 as the sole oxidant, the presence of residual hydrogen is presumably avoided. At present, the mechanism of thermal oxidation by dry O2 is a matter for conjecture, and the presence of small amounts of H2O was reported to have a marked effect on the rate of oxide formation10 (perhaps on the electronic properties of the surface, as well). Hence, this study of the kinetics of silicon oxide growth in 0, was undertaken: 1) to determine the oxidation rate at atmospheric pressure in a system designed to exclude rigorously all traces of H2O in the ambient 0,; 2) to obtain oxidation-rate data in situ in dry O2 by means of a continuous monitoring of the amount of 0, consumed during oxide growth. These objectives are complementary—the first assesses what effects (if any) are obtained by excluding H2O from the reaction, and the second expands this information while at the same time avoiding the uncertainty inherent in relying upon incremental measurements of oxide growth to furnish kinetic data. EXPERIMENTAL PROCEDURE The conventional silica open tube in a resistance-heated oxidation furnace is subject to sources of trace H2O, even after the input O2 is thoroughly dried and the outlet gas stream is passed through a trap to prevent

Jan 1, 1967

By AIME AIME

ON Sept. 24, 1875, a remarkable deposit of silver ore was discovered by James Ryan and Samuel Hawkes at the east base of Grampian Hill in central Beaver County, Utah.. A shaft was begun and had been sunk about 30 ft. in ore when the claim was sold on Feb. 17, 1876, to A. G. Campbell, Matthew Cullen, Dennis Ryan, and A. Byram for $25,000. To them is due the credit of having developed the mine and started the district on the road to its present state of prosperity. Their development resulted in proving the vein to a depth of over 280 ft. and about 2500 tons of ore was extracted and turned into bullion. In February, 1879, the mine came into the possession of the Horn Silver Mining Co., and since then over $65,000,000 worth of ore has been taken from the mine. Two smelters were built in 1878, near the mine; 400 men were employed underground, and 1000 on the surface, burning charcoal, hauling wood from the surrounding hills, and freighting and hauling hay for the hundreds of horses used in the work. Ore was hauled thirty miles to the

Jan 1, 1936

By A. Muan

Liquidus data are presented for mixtures in the ternary system FeO-Fe2O3-SiO2 in equilibrium with a gas phase with O2 pressures ranging from 10-10.9 to 1 atm. Data obtained are combined with previously published data to construct lines of equal 02 pressures and lines of equal CO2/H2 mixing ratios along the liquidus surface. Courses of crystallization of selected mixtures under conditions of constant total composition, constant O2 pressures, and constant CO2/H2 mixing ratios are discussed. PHASE equilibrium studies of silicate systems where iron is one component are complicated by the fact that iron readily occurs in three different states of oxidation: Fe3+, Fe2+, and Fe0. Success or failure in work with iron silicate systems is to a large extent dependent on control of the oxidation state of iron and all investigations therefore must be carried out under carefully controlled atmospheric conditions. Silicate systems containing only strongly electropositive metals (like Na+, Ca2+, Mg", etc.) can, for simplicity, be treated as condensed systems, that is, the gas phase can be neglected and the phase relationships discussed in terms of the phase rule written in the well known simplified form P + F = C + 1. In the case of iron silicate systems, however, the composition of the condensed phases varies with the gas composition, and a complete picture of phase relationships can be obtained only by varying the gas composition over a wide range. In order to understand the phase relationships in the more complicated multicomponent silicate systems with iron oxide as one of the constituents, a knowledge of the ternary system FeO-Fe2O3-SiO2 is essential, since it constitutes a bounding portion of all such systems. It was with this in mind that the present study was undertaken. Previous Work A considerable amount of work has been done on various aspects of the chemistry and metallurgy of systems containing silica and iron oxides. The two bounding binary systems FeO-Fe2O3 and FeO-SiO2" The first attempt to obtain information on phase relationships of iron oxide-SiO, mixtures at different 0, pressures was made by Greig.' Darken" determined the melting points of iron oxide on solid silica under various atmospheric conditions. Darken did not determine experimentally the composition of the melts at liquidus temperatures but discussed very ably the principles involved in applying the phase rule to the system. In a recent study Schuhmann, Powell, and Michal8 determined experimentally the liquidus surface of a portion of the ternary system and combined the new information with data in the literature to construct a phase diagram. Their method was briefly as follows: Homogeneous mixtures with various contents of SiO2, FeO, and Fe2O3 were made up by melting together stock mixtures in various proportions. Samples of the homogeneous mixtures, the compositions of which were determined by chemical analysis, were then heated in platinum crucibles in an inert atmosphere until equilibrium among the condensed phases was achieved. The samples were quenched to room temperature and the phases present determined by microscopic examination. Assuming that no change in composition takes place during the equilibration run in inert atmosphere, the liquidus surface can be determined, but no information is obtained regarding the partial pressures of 0, of the gas phase in equilibrium with the condensed phases. The author's method, to be described in the next section, permitted the location of points at the liquidus surface as well as a calculation of the corresponding partial pressures of O2. Experimental Method General Procedure: The standard quenching technique was adapted for a study under controlled variable atmospheric conditions. Premelted mixtures of silica and iron oxides in platinum envelopes were held at constant temperature under chosen atmospheric conditions until equilibrium was reached among solid, liquid, and gas phases. The sample was then quenched to room temperature, the phases present identified, and, for the most significant runs, the composition was determined by chemical analysis. The corresponding partial pressure of 0, was calculated from known equilibrium constants of the gas reactions occuring in the furnace atmosphere. Materials: Starting materials were oxides of commercially highest available purity; cp silicic acid was dehydrated by heating to 1350°C for 6 hr and cp Fe2O3 was dried at 400° C for the same length of time. Samples of 10 g were made up by mixing

Jan 1, 1956

By E. A. Almond

An attempt is made to explain the effect of stress on strain aging by examining the mechanism of yielding for a group of aged dislocations. The experimental results on which the theory is based indicate that a linear relationship develops between the aging stress and the discontinuous yield effect in a low carbon steel THE discontinuous yield effect that occurs in bcc metals after strain aging is usually explained by the interaction of interstitial atoms with individual dislocations. Attempts have been made to interpret the kinetics of strain aging in terms of interstitial segregation to nonrandom groups of dislocations1-3 but apart from Li's4 work little or no effort has been made to examine the effect of groups of aged dislocations on mechanical properties. It appears likely that such groups can be stabilized if a positive load is maintained on the specimen during aging5 and, furthermore, that the enhanced strain aging effect associated with aging under load might be due to the stability of these aged groups. The effects associated with this latter phenomenon have been described by Almond and Hull, Ref. 5, Figs. 2 and 3, and it is found that the upper yield stress, the lower yield stress, and the yield point elongation are increased by aging under load. The yield point elongation reaches a maximum value but the enhanced effect persists in the upper and lower yield stress values even after extended aging treatments when the general level of the flow stress curve rises. The flow stress, as measured at 8.5 pct total strain, however, is independent of aging stress. Almond and Hull5 showed that it was unlikely that the differences in mechanical properties could be caused by stress enhanced diffusion and they suggested that the effect was in some way associated with the different dislocation distributions that are obtained when specimens are aged with and without an applied stress. At that time no explanation was offered for the strengthening effect produced by stabilized dislocation distributions but additional tests have been performed to establish a quantitative relationship between aging stress and mechanical properties, and also to examine more closely the effect of varying the procedure for applying the aging stress. EXPERIMENTAL The material used was an iron wire containing 0.015 wt pct C, 0.002 wt pct N, and 0.006 wt pct 0. Tensile specimens with a 1 cm gage length and 0.08 cm diam were annealed at 850°C for 1 hr in vacuum to establish a grain diameter of 0.032 mm and then aged at 200°C for 24 hr. After this treatment the amount of carbon left in solution would be less than 10-4 wt pct, and ni- as aging time is increased. It is suggested that this observation, and effects that arise from varying the method of applying the aging stress, can be explained by a strengthening mechanism whereby dislocations are more difficult to move when they are aged in piled-up groups. trogen would be the main cause of strain aging. Tensile tests were performed in a hard beam machine at a constant crosshead speed of 0.02 cm per min and the specimen chamber was immersed in a temperature controlled silicone oil bath at 32" * 0.05"C. RESULTS All specimens were prestrained 5 pct before aging under stress and the results in Figs. 1 to 5 show the effect of aging time and aging stress on the following parameters ?UY = auy — ?F(5); i.e., the difference between the upper yield stress after aging,?uy, and the flow stress after prestraining 5 pct, ?f(5). ?LY = sly —sf(5); the difference between the lower yield stress after aging, ojy, and the flow stress after prestraining 5 pct. s8.5 = the flow stress at 8.5 pct total strain after aging at 5 pct strain. Varying the Loading Procedure. Three variations in the procedure for applying the aging stress were examined; i) After prestraining, the specimen was unloaded to a stress of 18 kg mm-2, aged at that stress, and then tested. ii) After prestraining, the specimen was unloaded to 2 kg mm-" then reloaded to 18 kg mm-', aged at that stress, and tested. iii) After prestraining, the specimen was unloaded to 18 kg mm-', aged at that stress, then unloaded to 2 kg mm- before testing. Specimens were unloaded or reloaded by decoupling a clutch in the drive transmission of the tensile machine. This enabled the crosshead to be driven manu-

Jan 1, 1970

By Thomas M. Drown

The process for determining phosphorus in iron now in most general use in the laboratories of iron and steel works, is, I think, the one proposed bv Mr. Emmerton." In this process the solution of the iron for precipitation by ammonium molybdate is effected by treating the iron with nitric acid, evaporating to hard dryness in a dish, taking up with hydrochloric acid and driving off the greater portion of the hydrochloric by nitric acid. This procedure accomplishes, first, the destruction of all the carbonaceous matters; and, second; it renders all the silica insoluble. Experience has proved the former—the complete oxidation of the carbon—to be absolutely essential; but the explanation usually given, namely, that unless the carbon compounds are destroyed they will have a solvent action on the yellow precipitate, I am inclined to

Jan 1, 1890

By G. E. Archie

THE usefulness of the electrical resistivity log in determining reservoir characteristics is governed largely by: (I) the accuracy with which the true resistivity of the formation can be determined; (2) the scope of detailed data concerning the relation of resistivity measurements to formation characteristics; (3) the available information concerning the conductivity of connate or formation waters; (4) the extent of geologic knowledge regarding probable changes in facies within given horizons, both vertically and laterally, particularly in relation to the resultant effect on the electrical properties of the reservoir. Simple examples are given in the following pages to illustrate the use of resistivity logs in the solution of some problems dealing with oil and gas reservoirs. From the available information, it is apparent that much care must be exercised in applying to more complicated cases the methods suggested. It should be remembered that the equations given are not precise and represent only approximate relationships. It is believed, however, that under favorable conditions their application falls within useful limits of accuracy.

Jan 1, 1942

By John Birkinbine

Among the notable deposits of iron-ore, the Iron Mountain at Durango, Mexico, is prominent. But, although it has been noticed in records of travel and official reports for three centuries, the statements made concerning it have been so largely alloyed with improbabilities that general credence has not been given to data relating to the Cerro & Mercado, that being the name by which this remarkable mountain of ore is known. Location. Geographically, the mountain is centrally located, being situated immediately at the City of Durango, which is distant in direct lines (as the crow flies) as follows: From the Rio Grande River at El Paso, Texas, in the north, 510 miles; from the same stream at Laredo, Texas, in the northeast, 410 miles; from Tampico, in the east, 475 miles; from the City of Mexico in the southeast, 520 miles; from Mazatlan in the west, 110 miles. At El Paso, the standard-gauge Mexican Central Railroad, and at Laredo, the narrow-gauge Mexican National Railroad, enter Mexico. Tampico is a prominent Mexican port on the Gulf of Mexico, and Mazatlan occupies a similar position on the Gulf of California. To reach Durango from Laredo or Tampico, spurs of the Sierra Madre Mountains must be crossed, and between Mazatlan

Jan 1, 1885

By G. A. Reinhardt, Albert Sauveur

Although many metallurgists know that some pearlitic special steels can be made troostitic, martensitic, and even austenitic, without quenching, and, therefore, without exposing them to the dangers of the quenching-bath, the practical significance of such possibility does not seem to have received the attention it deserves. Let us recall briefly the mechanism of the transformation alluded to. In Fig. 1 (after Guillet) is shown the constitutional diagram of nickel-steel; that is, of alloys of iron, carbon, and nickel. Any steel the composition of which falls within the area LPO is pearlitic after slow cooling; any steel the composition of which is represented by a point within the area MLO is martensitic, and any steel within the area MNO is austenitic. Starting with pearlitic steel, then by increasing the carbon-content or the nickel-content, or both, the metal becomes marten-sitic and eventually austenitic; that is, its composition crosses first the boundary-line LO and then the line MO—and it remains martensitic or austenitic after slow (air) cooling.' We have in this way imparted to the metal without quenching it the properties of hardened carbon-steel. In other words, the steel is now self-hardening; Nickel cannot be introduced into solid steel, but by the well-known process of case-hardening it

Jan 1, 1913

By J. E. Hilliard, H. E. Cook

It is shown that for systems having a miscibility gap the spinodal composition (c,) in the vicinity of the critical temperature (Tc) is related to the equilibrium composition (c,) by where cc is the critical composition. This expression is exart for the limit T — Tc and is a good approximation down to (T/Tc) - 0.9. If the miscibility gap meets the composition of the pure components THE recent theoretical treatment by cahn1,2 on spinodal decomposition of solid solutions has revived interest in methods of estimating the chemical spinodal, * i.e., the locus on a binary phase By use of the appropriate expression, the spinodal can be drawn on the Phase diagram almost by inspection with an accuracy comparable to that of lengthy calculations in which a free-energy function is fitted to the phase diagram. Satisfactory agveemenf is also obtained with spinodals comPuted from experimental free-energy curves. where G is the Gibbs free energy of the homogeneous solution and c the atomic fraction of component 2, the derivative being evaluated at constant temperature (T) and pressure (P). (These subscripts will hereafter be omitted from the partial derivatives.) If experimental measurements of G as a function of c and T are available in a single-phase region above the spinodal, then these can be extrapolated to obtain a series of metastable free-energy isotherms in the two-phase region, and from these isotherms a series of spinodal compositions can be calculated. Because the value of is very sensitive to experimental errors, an elaborate analytic procedure is required for

Jan 1, 1965

By R. K. Waring

A KNOWLEDGE of the mutual liquid solubility of zinc and lead is of importance in various phases of zinc metallurgy. The determination of this solubility has been the subject of numerous investigations, but unfortunatel, the results vary widely, particularly at higher tempera-tures, and it has been impossible to decide what data are most reliable. It was decided to investigate the matter and in view of the disagreement in the published results, it was felt necessary to take rather unusual precautions to insure the reliability of the data. For this reason deter-minations were made by four different methods, and the procedures of several of the previous investigators were duplicated. The previously used methods can be divided into two classes: methods involving freezing the entire melt and taking samples of the lead-rich and zinc-rich phases in the solid state, 1,2 and methods in which the. samples are taken while the bath is liquid and at the desired temperature. 3,4 Data obtained by methods involving freezing the entire melt show much lower solubility of lead in zinc than methods in which the liquid is sampled at temperature. The latter method was used by Spring and Romanoff5 and by Hass and Jellinek.6 The results of these two investi-gations are in agreement at temperatures near the melting point but at higher temperatures Hass and Jellinek find a higher mutual solubility.

Jan 1, 1934

By Frank Foote, Willard L. Bruner, Eric R. Jette, Y. New york

The alloys of gold and iron were investigated in 1907 by Isaac and Tammann,l who determined the thermal diagram for the entire system by thermal analysis and microscopic examination. They also reviewed the previous literature. Since that time the present authors have been able to find only two additional references. Guertler and Schulze2 examined the electrical resistance of iron alloys containing up to 40 per cent by weight of gold between 0" and 200" C.; the alloys were in the form of wires. The main result of this work was to confirm the solid solubility limit found by Isaac and Tammann; namely, about 20 per cent Au. More recently, Shih3 has examined the magnetic properties of gold alloys containing up to 10 weight per cent iron and particularly the range below 5 per cent. The alloys in the lower range were found to be paramagnetic; the 10 per cent alloy was ferromagnetic. The present investigation was undertaken to determine the solid solubility limits at various temperatures, particularly below the a-y transformation point of iron, since these solubilities are of some importance in connection with the working of the alloys in the manufacture of certain "grey" and "blue" golds. Materials and Methods The gold was obtained from the U. S. Metals Refining Co. and contained 99.99+ per cent Au. The electrolytic iron had been annealed in hydrogen and contained impurities as follows: P, 0.035; Si, 0.001; S, C, Mn, Cu, each 0.01 per cent. Weighed quantities of the two metals were placed in small crucibles lined with pure sintered MgO; a saturated solution of magnesium nitrate

Jan 1, 1934

By Roy P. Hudson

A micropyrometer known as the De Graaf apparatus has several advantages over the gas-furnace method for determining ash fusibility. When the De Graaf apparatus is operated by a modified method of procedure, the results closely check those of the gas-furnace method. This is indicated by tests on 27 samples of coal ash, with an extreme variation in fusibility values of 654" F. However, most of the ashes fused at temperatures between 2300º and 2500º. This, presumably, is the temperature interval within which the micropyrometer gives the best results. Additional comparisons are desirable. DISCUSSION (Thomas G. Fear presiding) A. C. FIELDNER,† Washington, D. C. (written discussion‡).-—The Pittsburgh Experiment Station of the Bureau of Mines has made two investigations1 of the micropyrometer for determining the fusibility of coal ash. These studies were undertaken with a view to adopting the micropyrometer method us a substitute or alternate to the present standard gas-furnace method, in view of the obvious advantages of greater speed, smaller ash sample, smaller laboratory space requirements, less equipment and greater comfort to the operator. However, the investigation showed that the micropyrometer type of furnace as then operated in five laboratories having this equipment could not be accepted as an alternate to the standard gas furnace, which is capable of close duplication in different laboratories, as shown in a recent colmparison between the Pittsburgh Experiment Station of the United States Bureau of Mines and the Fuel Research Station of Great Britain.2 The algebraic meau

Jan 1, 1934

By I. Iwasaki, P. L. De Bruyn

Electrical double-layer properties of the silver sulfide-solution interface in different electrolytes and the influence the properties exert on the adsorption of dodecylammonium acetate (DAA) were studied using an electrochemical titration technique. The flotation behavior of silver sulfide was observed using DAA as collector and the results were correlated with adsorption measurements. Silver and sulfide ions were identified as the potential determining ions and their adsorption densities were measured as functions of the pAg and of the ionic strength at two different pH values. The point-of-zero-charge (PZC) was observed to be at pAg 10.2, the value being independent of pH and of the nature and concentration of the electrolyte used. The surface charge of silver sulfide in these electrolytes was positive for pAg values less than 10.2 and was negative for pAg values greater than 10.2. The adsorption of amine on silver sulfide surfaces at pH 4.7 was found to be strongly dependent on the pAg. A shift in the PZC towards a lower pAg due to the adsorption of amine indicated a specific affinity of dodecylammonium ion towards silver sulfide surfaces. At pH 9.2 a strong adsorption of the undissociated amine molecule was indicated. The PZC shift towards a higher pAg and the adsorption of the amine was virtually independent of the interfacial electrical conditions.

Jan 1, 1972

By F. E. Wood

This paper is written primarily as a discussion of Dr. W. P. Hase-man's paper on "A Theory of Well Spacing"' and presents briefly the production records, and intensity and rate of development in a large portion of the two principal producing sands in the Salt Creek field, Wyoming. The study includes 1350 wells, 160,000,000 bbl. production, well spacings varying from two to seven wells per 40 acres and early and late development. The general conclusions to be derived from this study are: 1. It is impossible to formulate a mathematical rule to apply to well spacing in the Salt Creek field. 2. Each tract is a separate problem. 3. Tracts first drilled produce the most oil, with many exceptions. 4. Initial production is not a reliable index to the relationship between past, current, or future production. 5. Wells which have produced the most oil in the past are not necessarily yielding the greatest current production nor will they yield the greatest future production. In fact, wells which have yielded the greatest past production will, in at least one-half the cases, make less oil currently or in the future than wells which have produced a smaller quantity of oil in the past. 6. The following is a safe rule to apply in well spacing in the Salt Creek field: (a) If the drilling of an additional well on a tract results in a sustained increased production, with prospects of making a profit, the tract is not overdeveloped and additional wells might be drilled. (b) If the drilling of an additional well does not effect a sustained increase in the production of a tract, the tract is fully developed. Second Wall Creek Sand The Second Wall Creek sand, covering 20,000 producing acres, is the principal producing horizon in the Salt Creek field; 1610 wells are producing at this time from this sand. This paper deals with hut a portion of the entire field including 10,680 of the more productive acres,

Jan 1, 1930

By Will H. Coghill, Fred D. DeVaney

THE coercimeter, as its name implies, is an instrument for measuring the coercive force[+] of magnetic substances. It was developed by Davis and Hartenheim in the Special Studies Section, Metallurgical Division. A detailed description of this apparatus may be found elsewhere.2 The coercive force determinations of magnetic materials are interesting because of the relationship established by Gottschalk,4 who showed a linear relationship between the magnetization coercive force and the specific surface of comminuted particles. The value of this relationship in determining grinding efficiency has been shown by Dean.3 The determination of the surface contained in the subsieve sizes has always been a difficult problem for investigators. They made approximate measurements of the surface of coarse materials by sizing on screens, but for the determination of the surface of the sub- sieve sizes it was necessary to make detailed grain counts or elutriation tests, or to study dissolution rates. The technical literature contains many references to other methods for determining these surfaces, either by some special apparatus or by mathematical calculations based on distribution lines. Many of the methods are long and tedious, and the results of some, at least, are questionable. The turbidimeter gives quick results on ground cement. By using magnetite as the material to be ground, a simple determination of its coercive force by the coercimeter, requiring 10 minutes or less, can be transposed directly and accurately into units of relative surface. This subject has been pursued further by the U. S. Bureau of Mines in cooperation with the Missouri School of Mines and Metallurgy, Rolla, Mo., and the following is a description of the results.

Jan 1, 1938

By R. P. Marshall

This note describes positive evidence that hydrogen in titanium alloys diffuses under the influence of a thermal gradient. The experiments confirmed the expected similarity of this system to the H-Zr system and produced qualitative information on the magnitude of the heat of transport for hydrogen in titanium alloys. This effect has practical importance in applications where titanium alloys operate in a thermal gradient under conditions such that hydrogen embrittlement may develop within the expected lifetime of the structure, for example in supersonic aircraft service. The theories of thermal-gradient diffusion may be found in recent reviews and experimentation in this field by Shewmon,1 Sawatzky,2 Markowitz,3 and Darken and Oriani.4 The basis for Soret thermal diffusion is the "heat of transport", denoted by Q*. This is an energy term for the amount of heat (energy) transferred by atomic diffusion, and can be either positive or negative signifying a driving force for atomic diffusion to the cooler or hotter region, respectively. Experimentally, Q* is determined by plotting the natural logarithm of the point-to-point concentrations after exposure to a thermal gradient vs the respective point-to-point temperatures in units of the inverse absolute temperature scale. The slope of the straight line is Q*/R, R being the gas constant. For the titanium experiments, specimens (3 by 1 by 1/16 in.) of a) commercially pure titanium, b) the 8 Al-1 Mo-1 V titanium alloy, and c) the 6 A1-4 V titanium alloy were exposed to thermal gradients of 6° to 115°C per in. for 18 days at 250° to 550°C. The temperature gradient was in the direction of the 3-in. dimension. The hydrogen concentrations existing after exposure were determined on sections of the specimens by vacuum extraction. Three sections of unexposed sheet of each alloy were analyzed as standards to allow a check for hydrogen

Jan 1, 1965

By Ernest A. Hersam

The rate of output of a rock crusher is based upon a certain space relation, the calculation requiring that the size and position of the jaws, the principle of motion, and the speed of the machine be known. The result is a calculated maximum output. The purpose of this paper is to develop a method of calculating this maximum output, to judge the general applicability or utility of such a calculation, and, so far as possible, to lecord calculated values as a basis for the comparison of actual results, or for estimating the capacity of a new crusher or of a standard crusher working under new conditions. A method for calculating the capacity of crushing rolls, which has been in common use for a long time, is well presented by R. H. Richards.' The output is conceived as a ribbon of rock, of which the breadth, thickness and length are governed respectively by the width of the rolls, the space between them, and their peripheral velocity. The weight of the rock thus crushed in a given time can be calculated from its specific gravity, after applying a factor representing the percentage of voids in the hypothetical ribbon. The calculation of crusher capacity is made in a somewhat similar manner. While the action of rolls is simple, with few irregularities in operating conditions, in rock crushers the material advances intermittently, usually under the force of gravity alone, and is subjected to a variety of variable conditions. The effect of these variable influences upon the calculation of capacity is now to be shown. In this paper, capacity will be discussed quite apart from any consideration of mechanical efficiency; that is, results will be stated not in terms of output per horsepower, but of output for a given machine when operated at a known speed, constructed and adjusted to receive material of a known size, and to yield a product having a definite maximum coarseness.

Jan 1, 1923

By Robert W. Hunt

PeRhaps of all the scientific economic questions which have been claiming the attention of capitalists, metallurgists, manufacturers, directors of public utilities, and the general public of America, during the last few years, none have been of more importance than the one relating to the wear and safety of steel rails. The discovery of the Bessemer process made possible modern railway development. In that growth, as has generally happened in all progressive movemeuts, all its departments have not remained equally balanced. Iron rails permitted the construction of roadways for the passage of power-driven vehicles. In time the speed and weight of such carriages proved too much for the wearing-qualities of the rails, and the limit of railway capacity seemed to have been reached. Bessemer made his invention, which was soon perfected and developed, especially as related to steel rails, and thereby increased the limit of capacity, and vastly greater railway progress was made pgssible. The Siemens-Martin open-hearth process followed, and was later supplemented by the Thomas-Q-ilchrist basic improvement. For a time the Bessemer steel rails of commerce were more than equal to all that was asked of them, but this did not long continue, as evidenced by the records in our Tansactions. Revolutionary changes occurred in the industrial world, and in no part of it more than in steel-rail manufacture. Great and powerful commercial combinations were made, whose financial resources made possible the supplanting of the then most efficient blast-furnaces, steel-works, and mills, by others of theretofore unimagined capacity. Old traditions and practices of steel-making were wiped away, and, in too many cases, output was apparently the chief aim, with the result that much dissatisfaction with the wear and safety of rails was felt by railway officials, and the general public was concerned as to its safety when traveling. The climatic conditions of the winter

Jan 1, 1913

By A. C. Fieldner, W. A. Selvig

Ash in coal has always becri regarded as an undesirable substance, as the heat content of a coal dccreases in direct proportion to its ash contcnt. It represents so much inert materid that has to be transported, handled when the coal is burned, and finally disposed of. W. R. Roberts, in an address bcfore the Engineers' Society of Western Pennsylvania, Pittsburgh, on Sept. 29, 1925, said that on an annual output of five hundred rnillion tons of coal, a reduction of 3 per cent. of ash means fifteen million tons of refusc and a decrcase of $30,000,000 in freight charges. Ash also often prevents effieient utilization of the coal through the formation of clinker causcd by the mcltirig of the ash constituents when subjected to heat. The mineral constituents of coal may be of such nature as to make the coal unsuited for speeifie uses as for instance, high-sulfur coal for making metallurgical coke. While the usual proximate analysis of coal gives the amount of ash, it gives no information as to the nature and coniposition of the ash nor of the minera1 constituents from which the ash is produced. For the efficient washing of coal to remove ash-forining constituents it is desirable to know the composition and distribution of the ash-fonning constituents. Obviously such information is also desirable for the most efficient utilization of coal. Nature and Composition of Coal Ash Coal ash may be defined as the inorganic residue remailning after cornplete ignitior of coal. It is dcrived from the mineral constituents of thc coal. The ash-forming constituents may be roughly classified as inherent impurities and extraneous impurities. The former are mixed intimately with the coal substance, and arc derived either from the original coal-forming material or from external sources such as sedimentation and preeipitation while the vegetal coal-forming plant remains accumulated. The latter are present in the coal bed as partings, bands or nodules of pyrite! slate, shale, calcit,e, bone, etc. These are formed either during the laying down of the coal bed, or subsequently. Flag-

Jan 1, 1927