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By John K. Kennedy

ThE basic equations describing continuous zone-melting via the zone-void method were reported by Pfann. Using these equations, a theoretical study was undertaken in this laboratory on the effect of the variation of the significant parameters of the zone-void system. These parameters are the zone length, 1, the heater length, h, and the effective distribution coefficient, k. The object of this study was to determine the effect of these parameters on and (where a = Cp/Cf and ß = Cw/Cf, Cp, C,, and Cf being, respectively, the solute concentration in product, waste, and feed) so that, in future application of this technique to the ultrapurification of materials, the effect of 1 and h would be predictable regardless of the value of k. The basic assumptions made by pfannl were, for the purposes of this study, assumed to hold. For k < 1, the steady-state solute distribution in the stripping section and the shift in this distribution brought about by passage of a void is shown in Fig. 7 of Ref. 1. In this section the definition of k and ß precludes the possibility of ß assuming values less than unity when k < 1. In the course of this investigation it was found that computations based on Pfann&apos;s equations gave values of ß less than unity in the region 1 > k > l/h for almost all values of Ls, where Further computations showed that 6 assumes negative values when k > 1 for many values of L,, 1, and h. A check of the derivation of the stripping-section equations showed that an error had been

Jan 1, 1964

By G. Meyrick, H. W. Paxton

Observations on the tensile deformation of single crystals of austenitic stainless steels as a function of composition, orientation, and temperature are described and compared with relevant data for other alloys. Crystals free from second phases show sharp yield points followed by Lüders&apos; extensions of up to 20 pct. The critical resolved shear stress is strongly temperature-dependent increasing fourfold between 423O and 77°K. A temperature-independent low rate of hardening follows the Luders&apos; extension and is frequently associated with overshoot. Unlike pure metals where Proficse cross slip usually occurs at the end of linear hardening, this stage is terminated either by cross slip or by slip on the conjugate system, the particular node apparently depending upon initial orientation and composition. The presence of 6 ferrite or martensite has a profound effect upon the magnitude of the yield stress and the shape of the stress-strain curve. In experiments on transgranular-stress corrosion cracking of austenitic stainless steels in boiling magnesium chloride, several workers1&apos;2 have shown that increasing amounts of nickel tend to reduce the probability of specimen failure. Reed and paxton3 have observed in single crystals that the macroscopic crack plane changes as the nickel content is increased. For 18 pct Cr-8 pct Ni, the crack plane is sensibly perpendicular to the applied tensile stress; for 20 pct Cr-20 pct Ni the crack plane is (100). The average crack-propagation speed is much lower in the 20 pct Ni crystals. Furthermore, the possible importance of stack-ing-fault energy in nucleation and growth of cracks has been suggested by a number of workers. While the general effect of variations in stack ing-fault energy appears to be quite well-correlated with observed variations in cracking characteristics, each of the theories assigns rather different detailed reasons for these effects. Because the stack ing-fault energy of austenitic steels is believed to be increased with increasing nickel content, and because some theories of trans-granular cracking postulate a mechanical stage in the crack propagation (rather than relying entirely on electrochemical solution), it appeared to be of some interest to investigate the mechanical properties of a series of different compositions of aus-tenite single crystals. These experiments were considered of intrinsic value in view of the relative scarcity of such data on fcc alloys. This paper gives the results of some experiments carried out with this aim in mind, and suggests various &apos;other experiments which may be helpful in future studies. The experiments are also of interest in view of the recent interest in obtaining higher-strength steels by control of the imperfection content of austenite; although the compositions are not directly comparable, the results are still probably valuable. Comparisons with experiments on other fcc alloy crystals are made where possible to see how well the general pattern of behavior is understood. EXPERIMENTAL PROCEDURE The alloys used in this investigation were vacuum-melted heats of nominally 20 pet Cr-20 pet Ni-60 pet Fe, 20pctCr-16 pct Ni-64 pct Fe, and 20 pctCr-12 pet Ni-68 pet Fe.* Analyses of the material are

Jan 1, 1964

By S. A. Bradford

Internal-oxide precipitates in decarburized a iron alloys were studied by microscopic and X-ray methods. Diffusion of oxygen is primarily trans-granular, although large amounts of manganese or PhosPhorus cause preferred grain boundary dimsion at temperatures below 1450OF. Transgvanular internal oxidation follows the parabolic rate law with an apparent activation energy of 60 kcal per g-atom for decarburized rimmed steel and around 50 kcal per g-atom for higher alloy contents. The internal oxide is (Fe,Mn)0. Evidence was found for a miscibility gap in the FeO-MnO system. UNTIL very recently, the internal oxidation of metals was studied primarily as a scientific curiosity or, in a few cases, as a means of strengthening alloys by precipitation hardening. However, with the recent development of low-carbon enameling sheet steel, internal oxidation has become a problem of practical importance to the steel industry. For example, in 1961 it was reported1 that internal oxidation of steel can occur during decar-burization by open-coil annealing and will reduce the notch ductility of the sheet unless the process is carefully controlled. The present study was therefore undertaken to learn more about the rates and mechanism of oxygen diffusion and oxide formation in iron alloys. BACKGROUND The process of internal oxidation has been well-defined in the literature:&apos;,&apos; oxygen dissolves in an alloy, diffuses inward from the surface of the metal, and reacts to form a precipitate with the alloying element that will provide the most stable oxide. he growth of the finely divided so-called subscale, i.e., the internal-oxidation zone, depends on the diffusion rates of both the oxygen and the reactive element.4 Investigators have generally found that increasing the temperature increases the size of the oxide particles, the rate of subscale growth, and the tendency to transgranular diffusion. With very few exceptions, the square of the thickness of the internal oxide layer is directly proportional to the reaction time. Given two conditions easily satisfied for iron systems— a) an oxygen solubility much less than the concentration of the alloying metal and b) an oxygen-diffusion rate to the oxide boundary much faster than that of the alloying element—then the general expression developed by Rhines and co-workers5 for the parabolic growth rate of the internal-oxide zone can be simplified to the following form: where Co and CM are, respectively, the solubility of oxygen and the concentration of the alloying element, DO is the diffusion coefficient of oxygen, O/M is the weight ratio of oxygen to metal in the precipitated oxide, and x is the thickness of the internal-oxide zone after an annealing time t. Both the oxygen solubility and diffusion coefficient can be approximately expressed as functions of temperature by Arrhenius-type equations: in which H and Q are, respectively, the heat of solution and the activation energy of diffusion. Consequently, the apparent activation energies calculated from Arrhenius plots are the sum of the heat of solution of oxygen in iron and the activation energy for diffusion of oxygen. The data, if not the interpretation, of Schenck et al.8 bear out the fact that oxygen diffuses in the atomic form. The general rate law for atomic diffusion is: the reaction rate being proportional to the square root of the pressure at low pressures. Benard and Moreau8 studied both the surface oxidation of Fe-Ni alloys and the gradual penetration of oxygen into the metal. They observed that oxide particles first form along grain boundaries and then grow to form continuous films that eventually envelop the grains. The parabolic rate law does not usually apply in these cases, especially at the higher temperatures. The oxide formed is wustite which gradually transforms into Fe3O4 and finally into Kennedy and coauthors8 examined Fe-Ni alloys with 26, 75, and 84 pct Ni oxidized at 800°C and

Jan 1, 1964

By Alvin Kaufman

Geothermal plants are competitive with conventional units. A geothermal plant can produce electric energy for 6.70 mills per kwhr, compared with 6.96 mills for coal, 6.74 mills for oil, and 7.04 mills for gas. These costs include fixed and variable charges. Potential for geothermal power exists in the Western United States, Alaska, and possibly Hawaii. Assuming that the current downward trend in cost per kilowatt of coal will cease and that the relative cost of gas and oil, already trending upward, may rise considerably more, geothermal energy will be utilized where available, in producing electric energy. It will be used in California first because it is directly competitive with gas-and oil-fired installations there. A long-term appraisal is difficult because little is known about the sources of geothermal power and the electric generating capacity which the steam fields will support. However, a market for geothermal steam-generated electricity exists within the Western States.

Jan 1, 1964

By R. A., D. L. Sponseller, Flinn

Using specially del&apos;eloped titanium nitride crucibles and a pressurized syslem, it has been possible to determine the solzibilitv of liquid calcium in liquid iron and iron-base alloys. At 2925°F the solubility is 0.032 wt pet Ca in pure iron. The solubility is increased by aluminum, carbon, nickel, and silicon additions, and lowered by additions of gold. An inflection in the calcium-solubility curve occurs as carbon is added to iron. At approximately 0.87 Wt pet Ca the CaC, phase replaces liquid calcium, and the calcium concentration de- creases as more carbon is added to the iron. The maximum solubility, 0.36 wt pet Ca, was obtained in iron containing 10.5 wt pet Si. The data have important implications regarding the use of calcium in process metallurgy, as well as providing an interesting test of theories of metallic solutions. Reasonably good agreement is found with theories of Alcock and Richardson and of Wagner, and criteria are suggested which permit these theories to be applied more readily to systems of this type. AT the present time relatively little is known about the factors influencing solubility in liquid metals. Information of this type is important for such matters as the control of impurity levels in liquid metals, the use of magnesium in ductile-iron production, and the use of liquid-metal alloys as fuels and coolants in nuclear power plants. One important example of restricted solubility concerns the extent to which liquid calcium will dissolve in liquid iron. This is a matter of considerable interest in view of the strong potential of calcium for removing certain impurities in steel,. as well as the ability of calcium to desulfurize, inoculate, and produce spheroidal graphite in cast irons.&apos; Since ferrous materials normally contain other elements in addition to iron, the interactions of third elements with the Fe-Ca system are of interest. In view of the foregoing, this investigation was conducted to determine the solubility of liquid calcium in liquid iron and the effects of various third elements upon the solubility. For reasons of theoretical and engineering importance, the elements investigated were aluminum, carbon, gold, nickel, and silicon. Numerous attempts were made in the early part of the present century to determine the solubility of calcium in both liquid iron and steel, employing a variety of open-melt and closed bomb-type systems.2-4 From the results of these tests Wever concluded that calcium is insoluble in liquid and solid iron.5 These investigations were unsatisfactory in that they failed to insure the presence of a liquid layer

Jan 1, 1964

By T. W. Healy, P. Somasundaran, D. W. Fuerstenau

The flotation behavior of quartz in the presence of alkyl ammonium acetates as a function of alkyl chain length has been interpreted in terms of hemi-micelle formation at the solid-liquid interface. The van der Waals cohesive free energy that is responsible for hemi-micelle formation has been found from these results to be 1.0 kT per CH2 group. This is in excellent agreement with literature values obtained from research on the properties of micelles in bulk systems. Collectors of the type CH3(CH2)n-2CH2-P, where P is a polar group and n is the number of carbon atoms in the straight alkyl chain, will induce flotation of an appropriate mineral at lower concentrations as n increases. This reduction in collector concentration with increasing n has been reported for such systems as xanthates on sulfides1,2 and amines on quartz.&apos; The effect of chain length of alkyl surfactants on such solution properties as conductivity,&apos; surface tension,&apos; and solubility6 and such interfacial properties of solids as contact angle7 and electrokinetic potential8 have received considerable attention, but only limited quantitative descriptions of the effects have been given. The electrokinetic studies of alkyl amine salts on quartz indicated that the solution concentration of collector at which the marked change in electrokinetic potential of quartz occurs decreases systematically as the length of the alkyl chain increases. The aim of the present work was to obtain a quantitative description in terms of current theories of flotation of the effect of the hydrocarbon chain of alkyl ammonium acetates on the flotation behavior of quartz. BASIC PRINCIPLES The marked changes in electrokinetic potentials of quartz in dodecylammonium acetate (DAA) solutions were postulated to result from the association of adsorbed collector ions into two-dimensional aggregates, called hemi-micelles.9 Subsequently, the rapid increase in flotation rate of quartz was shown to coincide with hemi-micelle formation." We would like to discuss briefly the concept of hemi-micelles in terms of recent interpretations of micelles in bulk solution. Micelle hypothesis: In dilute solutions, alkyl ammonium and related salts behave as ordinary strong electrolytes, but at a certain concentration there is a marked change in physical properties of the solutions, e.g., in equivalent conductance, transport number, freezing point lowering and viscosity. To account for these phenomena, McBainl1 introduced the concept of micelles, which are aggregates of long-chain ions. It is believed that the ionic heads of the constituent ions of the micelle are in contact with water, whereas the nonpolar groups turn away from it and are in contact with each other. Work must be done to bring these charged polar groups together, but energy is gained (i.e., so called van der Waals cohesive energy) when hydrocarbon chains are expelled from the water and allowed to associate. For a given polar group, the tendency to form micelles will therefore strongly depend on the hydrocarbon chain length. Theoretical treatments of micelle formation by Shinoda12 and Phillips13 and others lead to the following expression for the concentration at which micelles form (the critical micelle concentration or cmc) in aqueous solutions of long- chain electrolytes

Jan 1, 1964

By J. W. Keyes

"The original grinding circuit at East Malartic consisted of two 8 by 8 C.A.C. mills in closed circuit with two 72 inch Akins Classifiers and an 8 by 10 secondary mill in closed circuit with two 48 inch duplex classifiers. With this circuit, we experienced a drastic drop in tonnage from one month to another, due to variations in the hardness of the ore. The first step to overcome this difficulty was made by increasing the critical speeds of the mills from 78% to 82%. This resulted in an increase in the secondary mill throughput; but, when the change was made on the primary mills no increase was obtained.The drastic drops in tonnage were still experienced and through working with Allis Chalmers the 8 by 10 mill was converted to a rod mill and the two 8 by 8 n1ills to secondary mills. This change eliminated the two 72 inch Atkins classifiers and the scoops on all the mills, since the 48 inch Akins classifiers sands could then be fed by gravity to the secondary mills through feed pipes.The rod mill and secondary mill discharges were fed to a common pump box using 5 by 5 S.R.L.'s running at 1085 R.P.M. with a twenty-five foot head. When this was done the pumping costs jumped from $105. 00 for 6 months to $1050. 00 in one month, or from 0. 0004 to 2. 75 cents a ton milled. Several factors contributed to this jump in pumping costs as follows:"

Jan 1, 1964

By J. M. Oblak, R. F. Hehemann, R. H. Goodenow

STUDIES of surface relief and growth kinetics have lead to the concept that widmanstatten ferrite along with upper and lower bainite constitute a continuous series of decomposition products.1-4 Current models4 propose that these products form as plates with a coherent or semicoherent leading edge which propagates at a rate controlled by diffusion of carbon into the surrounding austenite. There are, however, important crystallographic and morphological differences between these products—particularly between upper and lower bainite. For example, upper bainite appears to exhibit a (11lIy orientation habit, whereas lower bainite develops with a more irrational habit near {2251y.5-7 Many of the morphological features of these decomposition products are not yet well-documented. Recent studiess have demonstrated that low-carbon martensites form as sheets of closely spaced needles on {lllly planes while higher-carbon martensites form as plates with {225}? or other orientation habits. The similarity in the crystallography of these two modifications of martensite with upper and lower bainite is striking. Therefore, a study of the morphology of bainite in a series of hypoeutec-toid alloy steels has been initiated to explore these relationships further. The question of immediate interest is whether upper and lower bainite form as plates or needles. A two-surface (approximately perpendicular) metallographic method was employed to study the morphology of bainite in a variety of low and medium alloy steels. Compositions of these steels have been reported elewhere. The behavior of 4340 and 4370 was typical and will be described here. Austenitizing treatments involved 20 min at 2350°F for 4340 and at 2000°F for 4370. Isothermal transformation was conducted in molten-salt baths. Upper bainite was produced at 925°F in the 4340 steel and lower bainite at 575°F in 4370 with transformation times adjusted to produce 10 to 15 pct of the decomposition product. Many of the morphological features of upper bainite have been catalogued in the recent literature.&apos;&apos; The two principal variants observed in the present investigation are illustrated in Fig. l(a). One form appears as long, thin plates or needles and the other as small, frequently irregularly shaped particles. Both variants may occur as isolated forms but more frequently appear in groups as demonstrated in Fig. l(a). Two-surface analysis reveals that these two variants constitute different sections through a single morphological form. To demonstrate this, a number of sections perpendicular to the plane of Fig. l(a) were prepared at various positions along the length of the elongated particles. A section taken at position 1 in Fig. l(a) is presented in Fig. l(b). Here, the dark line represents the edge of the sample and the left-hand portion of this photomicrograph is that from the surface perpendicular to the original plane of polish. Since it was necessary to repolish the original surface after each sectioning, the shape of the bainite particles on this surface, right hand side of Fig. l(b), changes with each sectioning. The disappearance of plate A, Fig. l(a), in Fig. l(b) emphasizes the small cross section of these structures. The group of particles in the lower left-hand

Jan 1, 1964

By S. C. Nordeng

The program described in this paper is primarily a test of the possible utility of multiple regression in ore search, It was carried out as a cooperative project between White Pine Copper Company, the Institute of Mineral Research and the Department of Geological Engineering of the Michigan College of Mining and Technology. The authors wish to thank Dr. Cleaves Byers, Associate Professor of Mathematics, MCM&T, and Mr. Robert DeBaubien, Graduate Student in Mathematics, MCM&T, for their work in programming the project for the computer,

Jan 1, 1964

By Fred W. Shultz

The process engineer is familiar with the in any methods employed in the past for analyzing various materials. These include panning. eyeballing, and wet chemistry. Of those mentioned only wet chemistry has been and will continue to be a standard measure for the elemental content in a given material. However, wet chemistry, by the very nature of the method, can be excessively time-consuming and thus reducing obviously the number of samples that may be processed in a given period. The analysis by X-ray, in most cases, requires nothing more than assurance that the sample is in a suitable state for presentation to the X-ray spectrometer.

Jan 1, 1964

By Sumner M. Anderson

THE ENORMOUS contrast between the mineral economy of Cuba in 1963 and in 1958 was the result of the overall Political changed to which the total economy of the country was intimately lined. Creation of the Cuban Mining Institute (Instituto Cubano de la Minería) to direct all mining activities in the country was an early act of the new Government after the revolution on January 1, 1959. During the next 2 years, the Government confiscated foreign holdings,2 including Unite States investments exceeding $1 billion in value. Foreign mining and metallurgical technicians-predominately from Communist areas-were brought in to reorganize the mineral industries. On January 3, 1961, diplomatic relations between Cuba and the United States were severe and then on May 2, Cuba announced its full-fledged membership in the so-called Communist Bloc. Fifty-four international treaties assured Cuba of Communist economic support, technical and financial assistance, machinery, raw materials, and manufactures. The Soviet Union agreed to buy some Cuban mineral products, and Czechoslovakia stated that it would buy all mineral production offered for the next 20 years, but in both cases at prices said to be much lower than the world market. The mineral productivity segment of the mineral economy during and since the period of political metamorphosis, has withstood the political disruption better than has the economy as a whole, but with no direct measure of the magnitude of its cost. The overall economic record is marked with steady deterioration; the annual average per capita income has dropped from $374 in 1957 to $185 in 1963, when Cuba&apos;s deficit with the Soviet Union alone reached an admitted $1 billion.

Jan 1, 1964

THE problem of reaction rates in the open-hearth process is essentially that of trying to form a fairly clear picture of the "chemical mechanisms" in the bath. Quantitative data on reaction rates would perhaps not be of much practical importance even if they were available; however, what few approximate data there are can be used in combination with data given in Chapters 16 and 17 to sketch a picture of the "chemical mechanics" of the open-hearth process that is consistent with essentially all the present available evidence. The result may later be found incorrect in many details but even so it will illustrate certain useful methods for obtaining a clearer understanding of the process. Consistent with the treatment in Chapter 15, but in simpler terms, we may say that chemical reactions in general involve the following elements or steps : 1. The reacting molecules are mixed together in space in such fashion as to favor collisions among them. 2. Units of what is usually an intermediate molecular arrangement called an activated complex are formed at a certain rate, depending on temperature and concentrations. 3. .These activated complex units decompose into the reaction products (this step usually assumed to be so rapid as never to limit the over-all process). 4. In any of these steps, heat energy may have to flow into, or away from, the reaction zone to permit the reaction to proceed. 5. The products of reaction will usually have to move out of the way to permit further reaction. The temperature factor enters mainly through step 2, and its effect is very marked. (What is called temperature is really the mean energy content of all the molecules of the substance involved; at any one temperature a certain proportion of the molecules will have much higher energy content than the mean value.) Various reaction rates measured at around room tem-

Jan 1, 1964

By J. L. Ratliff, R. I. Jaffee, H. R. Ogden, D. J. Maykuth

An experimental program was carried out to improve the low-temperature ductjlity of tungsten through the combined use of dispersed oxides for grain-size control and Groups VII and VIII metal additions for matrix softening. Separate binary -alloy studies showed that increasing amounts of finely dispersed thoria or zirconia and critical amounts of rhenium, osmium, and iridium were effective in significantly reducing the ductile-to -brittle bend transition temperature of tungsten as well as in increasing its re crystallization temper - LIKE most of the high-melting point bcc metals, tungsten undergoes a marked transition from ductile to brittle behavior with decreasing temperatures. The material factors which influence the transition temperature include grain size, metal purity, and the presence of dispersed phases. ature and decreasing its recrystallized grain size. The beneficial effects shown by each of these additions on transition temperature and grain size in binary combinations appeared to be additive in tevnary combinations. Thus, combined additions of 2 to 8 vol pct thoria with 5 pct Re, 0.87 pct Os, or 0.30 pct Ir were effective in lowering the transition temperature of tungsten pom 2000 to 75"C, increasing its re crystallization temperature from 1600 to 1800°C, and decreasing its recrystallized gain size from 1175 to 6800 grains per sq mm. The mechanism by which these factors are operable in tungsten is not yet clearly understood. Nevertheless, it has become increasingly apparent that the interrelationship of grain size and matrix composition governs to a large extent the degree of low-temperature ductility which can be achieved. Though it is not possible to accurately assess the relative importance of these variables, the available evidence suggests that, at low temperatures, grain-size effects predominate over purity effects. This was indicated in recent studies by Allen, Maykuth, and Jaffee,&apos; involving single crystals containing 20 to 40 ppm 0 and 1 to 30 ppm C. Thus, while each

Jan 1, 1964

By T. R. Madhavan

The development of contact angles on highly polished ?uraninite surfaces, using sodium oleate and dodecyl ammonium acetate as collectors, has been studied at different collector and hydrogen ion concentrations. It was found that sodium oleate in acidic media (up to a neutral: PH) and dodecyl ammonium acetate in neutral and alkaline media give good contact angles. It appears that the combined forms of these collectors, viz., oleic acid and free amine, are more important in effecting contact. W ITH the emergence of uranium as a strategic metal in the last fifteen years, considerable effort has been directed toward the commercial recovery of uranium from its ores. This has resulted in the development of a uranium technology. It is only in recent years, However, that fundamental data regarding the floatability and surface properties of uraninite and ?pitchblende have been elucidated by different methods. Contact-angle measurement is one of the important tools for tl1e evaluation of the conditions of floatability

Jan 1, 1964

By John C. Kleiber

From time to time since the initial installation of an experimental flotation section in 1940 (reference A), Permanente Cement Company has made efforts to beneficiate the low-grade limestone fraction which occurs in its deposit at Permanente, California, The encouraging results outlined in this paper are the result of Permanente&apos;s latest effort. This paper discusses the factors governing the selection of the flowsheet with particular reference to marketability of the sand tailing by-product. The process flow is outlined in detail, and operating statistics of the plant are presented. Finally, the problems encountered in the operation of Permanente&apos;s beneficiation plant are discussed as well as solutions sought and found.

Jan 1, 1964

By Louis A. Panek

Research on roof bolting has developed significant information with respect to the functions that can be performed by properly installed bolts and the methods that can be used to ensure that effective installation has been achieved. The present paper brings together results that are pertinent to the design of a bolting system for reinforcing horizontally stratified mine roof with vertical bolts. The design approach is based on the use of bolts to decrease the maximum bending stress within an arbitrary sequence of roof strata (such as shown by figure 1) in which the only loads are the weights of the individual beds. The use of rock bolts to achieve other objectives, such as to stabilize a fractured rock mass on the periphery of a mine opening (3), is excluded from consideration herein.

Jan 1, 1964

THE primary interest in the subject of this chapter lies in the fact that various heats of steel made to the same chemical specification do not always have the same properties. The properties considered here, of course, are those inherent in the ingot immediately after solidification and not qualities imparted by variations in subsequent mechanical or thermal treatment. The expression "made to the same chemical specification" is used because some of the variations in properties are due to variations in chemical analysis within the specified ranges of those elements commonly specified and determined. Other variations in properties are due to variations in those constituents of steel (elements or compounds) that are not ordinarily included among the elements specified, thus not a part of the specified "composition." The term "constitution" is used to include not only the specified composition but also the nature and distribution of every element or compound contained in the steel entering the ingot mold ; also included are items such as aluminum oxides and nitrides, presence of soluble gases, and dispersion of nonmetallic particles. When it is considered that the constitution of steel is determined by the addition or absorption into the bath of all such constituents from whatever source, it follows that constitution is of necessity the final result of steelmaking practice. It is the agency through which steelmaking practice operates to control the properties of the steel. The term steelmaking practice is here used in the broad sense, meaning the control of all the materials entering the steel and of the conditions under which the process is carried out. Steelmaking practice, thus defined, establishes the chemical system within which the reactions between components must proceed in obedience to the laws of chemistry. Thus the chemical constitution of the steel is established and, through constitution, the properties of the metal are established. In the preceding chapters it has been shown how the constitu-

Jan 1, 1964

By Gary A. Kingston

This examination of Pacific Northwest (Idaho, Montana, Oregon, and Washington) ferrous scrap-industry operations, principally those in Oregon and Washington, points out factors influencing the supply and consumption of scrap materials, such as the complete dependence of steel ingot producers in these States on scrap as a metal raw material and the sizable quantity of scrap exported from Seattle and Portland to Japan. The pattern of the industry is presented as a movement of materials from their diverse sources to the consuming market. The geographic locations of the consuming industries in relation to the areas generating scrap materials and the movement pattern of the supply from source to destination strongly influences the cost of the commodity. The best measure of the scrap supply available in an area is experience in terms of how much scrap was withdrawn at a given price. Scrap availability is not finite, because the return of materials as scrap is secular and influenced by constantly varying market conditions. Steel ingot producers use 75 percent of the approximate 500,000 tons of scrap consumed in Oregon and Washington; steel foundries take 15 percent of the total; and iron foundries, ferroalloy plants, and other miscellaneous consumers utilize the remainder. Also, from 1955 to 1960 an average of about 200,000 tons has been exported annually from Oregon and Washington. The foreign exports are supplemented by lesser shipments to other steel producing States, principally in the western United States. From 1955 to 1960 the preferred and higher value heavy melting scrap grades accounted for about 60 percent of total withdrawals which varied between 600,000 and 950,000 tons annually. Total crap withdrawals from Oregon and Washington are projected to 1.8 million tons by 1985, 60 percent (1.1 million tons) of which will be heavy melting grades. No. 1 heavy melting scrap is most attractive to scrap consumers at $35 per ton or less. Price-supply relationships compared with projected scrap requirements indicate future prices possibly over $35 per ton. High prices over a long period could motivate the Pacific Northwest scrap consumers to produce steel from iron ore. However, technologic changes taking place at integrated steel plants could reduce scrap withdrawals from the Pacific Northwest, which might keep the scrap price sufficiently attractive to obviate production of competitive iron products by the Pacific Northwest scrap consumers.

Jan 1, 1964

By E P. Graham

Orebodies occur in an infinite variety of grades, shapes and sizes, and take many millions of years to grow. When extraction starts there is only one possible end -the mine sooner or later will run out of ore and shut down. If the mineral industry is to supply the ever increasing demands of modern civilizations, more and more metals must be found and mined. This will require a never-ending search for ore, and the development of every economic body, large or small. To justify the mining of a small orebody, it first of all must pay its way. If the size of the burden imposed by the capital cost estimates is not carefully worked out, an otherwise promising situation could be killed. The very nature of mining, as a transient industry, re-leases a steady stream of good used equipment, and the trained personnel to install and operate it. All manner of plans and layouts, which can be utilized at a new property, are available. Working these and other economies into the estimates will sometimes make enough difference to give a prospect the green light.

Jan 1, 1964