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By T. J. Koppenaal, M. E. Fine

A yield point effect attributed to short-range ordevi?g (SRO) occurs in Cu base Al. At at 296°K varies with heat treatment, decreasing as the annealing ternperature is raised .from 433Oto 598°K. Davies aid Cahn' observed a corresponding decrease in SRO. (523 °K anneal, measured at 77°K) is approximateZy proportional to the variations of A7 with strain rate and testing temperature are also Consistent with the idea that is associated with SRO. A preliminary investigation of the tensile properties of a Cu-Al single crystals showed the presence of a rather strong yield-point effect (drop in flow stress after initial yielding). The object of this research was to investigate its origin and behavior. a Cu-Al alloys are particularly interesting because diffuse X-ray scattering measurements by Davies and Cahn,' Houska and Averbach,' and Borie established the presence of short-range order. The degree of local order may be changed with heat treatment.' cottrel14 suggested that the presence of local order might result in a yield-point effect, and thus the possibility exists here for experimentally ascertaining the importance of short-range order with respect to yield points in these alloys. Since a 12 pct difference exists between the atomic sizes, elastic or Cottrell locking5 must also be considered. Further, Howie and swanne have shown that the stacking fault energy of copper is reduced by aluminum additions. The width of extended dislocations should thereby increase. hus the conditions appear attractive for Suzuki locking.' Finally, the possibility of stress-induced order at dislocations, schoeck locking,' must also be examined, EXPERIMENTAL PROCEDURE Alloys up to 14 at. pct Al were prepared by induction melting high-purity (99.999 pct) Cu and (99.996 pct) Al in a graphite boat under a dynamic vacuum of 5 X 10o mm of Hg. After homogenizing the ingots at 900°C for at least 24 hr under vacuum, they were rolled with intermediate anneals to strips 1.55 mm thick. Single crystals 10 in. long were grown by lowering strips, contained in a split graphite mold sealed in fused quartz at 5 X lo-' mm of Hg, through a single coil induction heater at a constant rate of 1/2 in. per hr. Tensile specimens 1.25 in. long were cut from the single crystal strips and reduced cross sections about 0.7 in. long and 3.0 to 3.5 mm2 in area were introduced by filing and abrading.8 To remove the worked portion about 10 pct of the cross-sectional area was removed by etching. Back-reflection Laue photographs of a filed and etched specimen were taken before and after annealing at 900°c for 24 hr. Small, well defined Laue spots were obtained with no visual difference in the two photographs. Further, specimens with and without the reduced sections began yielding at about the same stress. Hence, for our purposes, filing and abrading did not affect the structure of the specimens. Each single crystal specimen was annealed at 900° c in vacuum for at least 24 hr and furnace cooled; while cooling through the range of 250o to 200°c, the rate was about 55°C per hr. Orientations were determined by the usual back-reflection Laue

Jan 1, 1962

By G. L. Corrigan, J. R. Coleman

Four factors that largely determine the end product obtained when cement and water are mixed are the chemical compo ition of the cement, the fineness to which the cement is ground, the amount of mixing water used, and the procedure used in mixing the slurry. In order to study the effect of two of these factors, the other two, the chemical composition and method of mixing, are kept constant, leaving as variables fineness and water-cement ratio. Through years of experimentation and usage it has been well established that the reduction of cement clinker to a very fine state by grinding improves its cementing value, principally because the reaction between cement and water takes place only at the surface of the cement particle, further action being hindered by the accumulation of reaction products that tend to coat the unreacted material. Therefore, the more finely ground a cement, and the greater the surface exposed in proportion to its mass, the more rapid is the hydration rate. Similarly, the greater the surface exposed, the greater the proportion of the cement that reacts, and the lower the amount of residue that is unreacted and so remains inert and unable to make any contribution to cementing properties.1 Although it is more expensive to manufacture a finely ground cement than a coarser cement, the advantages of fine grinding of construction cements were so marked that the fineness of cement has increased considerably in past years. When the manufacture of special oil-well cements was begun, it was necessary to consider properties of cement that previously were considered of minor importance, foremost of these being pumpability. Since, with the water-cement ratio constant, a finely ground cement will produce a neat slurry of higher consistency and shorter time of pumpability than will a coarser cement, there is a tendency to grind oil-well cements to a lower degree of fineness. Therefore, in order to produce oil-well cements that will make a slurry having a long time of pumpability, cements are manufactured that because of their coarseness generally are poorer cementing materials than some of the more finely ground construction cements. On the other hand, often it is necessary to pump oil-well cements for long periods of time to place them properly behind a string of casing in a deep well, and since high strength is not of foremost importance for such cement, there is room for considerable controversy concerning the proper fineness range.

Jan 1, 1941

By R. F. Mehl, B. Lustman

THE formation of intermediate phase layers in cementation processes has been subjected to extensive qualitative investigation though to relatively little quantitative study; this work has recently been fully summarized by F. N. Rhines.1 It is necessary here only to enumerate the general conclusions drawn concerning the kinetic laws governing the growth of intermediate layers and to state what is known concerning the structural changes accompanying the generation of phase layers. I. When the intermediate phase is protective in type-i.e., when its density is less than that of the base metal, so that a continuous coating is formed and maintained-the isothermal growth of the phase follows a simple parabolic equation: [1 = ki [I]] where X is the thickness of the alloy layer, k the reaction rate constant, and [t] the time. The applicability of this equation to diffusion processes is tested by plotting the square of the thickness versus time, or by plotting the thickness versus the square root of time; the resultant achievement of a straight line in such a plot has been considered sufficient proof of the validity of this equation. Exceptions have been found where liquid phases are involved in the reaction, where the diffusion layer is cracked,2 and where thin semimetallic oxide and sulphide coatings are formed on metals.3 In the first two cases the thickness increases linearly with time, and in the latter it is a logarithmic function of time. 2. The rate of thickening varies with temperature according to the Arrhenius equation: [k = Ae-QIRT [2]] where k is the parabolic rate constant of Eq. I, or some other rate-descriptive function, A is the action constant, e the base of natural logarithms, Q the heat of activation, R the gas constant, and T absolute temperature. This equation has been found to be generally valid except when transformations occur during reaction in either the base metal or in the reaction layer; in such instances Eq. 2 is still applicable with different values for the constants A and Q above and below the transformation temperature. 3. All phases that are stable at the temperature at which diffusion occurs will appear in the interdiffusion of two components. In some cases certain of the phases may be too thin to be observed and identified easily. Nonequilibrium phases have never been noted in thick reaction layers; i.e., layers of a thickness that may be discerned microscopically. The relative thickness of each phase in a diffusion layer is proportional to the concentration gradient and to the rate of diffusion in that phase.4 The reaction layers tend to have a

Jan 1, 1942

By G. M. Ikeda, J. G. Sibakin

An investigation was carried out to determine the variables affecting the coiling temperature of strip in the 56-in. hot strip mill. After statistical treatment, equations have been derived to determine the temperature drop between mill and coiler for both full spray (top and bottom) and top spray only practices. The individual influences of each variable in the temperature drop were derived for both practices. Limitations of the present practices were shown and adjustments in cooling for increased rolling speeds were suggested. A method of estimating the required number of sprays, their spacing, pressure, etc., to achieve a desired temperature drop is developed. MAXIMUM finishing temperature of a hot strip mill is mainly determined by the rolling speed, gage, and the temperature of the bar entering the mill. This finishing temperature may be limited by the maximum admissible coiling temperature in cases when either the cooling facilities on the runout table are not adequate or, more generally, when the cooling capacity of the runout table and the production capacity of the continuous mill are out of balance. Some time ago, the balance between these two factors was not considered detrimental to production. Recently, a new drafting schedule was introduced which increased the production rate, the entry temperature, and hence the finishing temperature. Thus, the restriction of the maximum specified coiling temperature became an important factor for many of the thicker gages. An investigation of the factors determining the coiling temperature may be, therefore, of considerable importance. A brief description of the available equipment will be a useful illustration of the techniques and methods used for this investigation. The 56 in. continuous hot strip mill is composed of six 4-high stands each containing two 221/2-in. diam work rolls and two 45-in. diam back-up rolls. Either of the last two stands can be used as the finishing stand. Which stand is used is dependent on the total percentage of reduction to be taken over the whole train, i.e., on the entry thickness and the final gage. The characteristics of these last two stands are given in Table I. Table I. Operational Characteristics of Nos. 5 and 6 Stands No. .5 NO. 6 Maximum voltage GOO 600 Power, hp 30(10 W00 I normal, kilonmp 4.35 3.73 Rpm of motor and rolls ISO 15 0 ITS to 300 Spettl ot strip, fpm 333 6 to 376T.2 103) to 2062 The speed of the finishing stand varies with the amount of reduction, strip width, and the exit gage. Finishing speeds in general use for varying gages are shown in Table 11. These speeds may change with an increase or decrease in the entry temperature of the strip. Even though the maximum speed of No. 6 stand is shown as 2062 fpm, this has so far never been attained,

Jan 1, 1957

By E. Hoek

The stability of a rock structure depends primarily upon the extent to which fracture develops within the structure, The prediction of the extent of potential fracture, the first step in the study of fracture development, involves a knowledge of both the stress distribution in the structure and the criterion which governs rock fracture under various stress conditions. While a great deal of research effort has been devoted to the development of techniques for analyzing the stresses in mining and civil engineering structures1-3 and to the investigation of the fracture mechanism of rock 4-6 relatively little attention has been paid to the application of available knowledge to the solution of practical engineering problems. This paper describes a photoelastic technique for the determination of potential fracture zones in certain types of rock structures. A practical example, based upon a problem which might be encountered in designing the layout of deep-level mine excavations, is given as an illustration of the application of this technique. STRESS ANALYSIS AND ROCK FRACTURE In deciding upon the technique to be used for the solution of a problem involving the prediction of rock fracture it is necessary to consider: 1) What type of stress information is required to satisfy the fracture criterion for rock; anti 2) How this information can most conveniently be obtained. It has been established, both theoretically 4,7 and experimentally 5,6,8that the fracture of hard rock depends primarily upon the relationship between the algebraically greatest and the algebraically smallest of the

Jan 1, 1967

By A. M. Gaudin, C. S. Chang

IN general, fatty acids or their alkali salts do not cause clean quartz to float. However, the presence of multivalent ions, such as the alkaline-earth metal ions and heavy-metal ions, can activate quartz and thus make it respond to soap flotation. The mechanism of activation and soap flotation of quartz has been studied.1-4 The problem was attacked by making flotation tests rather than by careful adsorption measurements on suspensions of ground quartz in solutions containing the activator and the collector. Attempts have been made to determine the adsorption of barium ion and calcium ion on quartz. The results have only qualitative value as the analytical methods were not adequately precise. Artificial radioactivity and progress in radioactivity detection have introduced a new analytical tool, which can have a sensitivity several orders of magnitude greater than that of other methods.5-6 In the experimental work described in this paper the radioactive tracers, barium 140 and carbon 14, were employed. Lauric acid was synthesized, having a radioactive carbon atom and was used with Ba140 to study the adsorption of barium and laurate ions from aqueous solution on ground quartz. Flotation tests, using the vacuum flotation technique,4 were run in conjunction with the adsorption experiments. The object of this investigation was to understand better the reaction mechanism of barium activation and soap flotation of quartz. Methods and Materials Quartz Sample Preparation: Lumps of hand picked quartz, washed free of stains, were reduced in size to -20 mesh in laboratory crushers. The product was boiled in concentrated hydrochloric acid to remove the abraded iron. The cleaned product then was ground dry in a laboratory porcelain mill, using siliceous pebbles, to pass through a 200 mesh screen. The ground product was deslimed by sedimentation at 37 microns. This -200 mesh +400 mesh material was subjected again to boiling with concentrated hydrochloric acid, followed by washing with distilled water and further desliming. The cycle was repeated until no trace of iron could be detected in the wash liquor. During the final washing, the pH of the wash water was checked to insure the complete removal of the acid from the mineral. The quartz then' was rinsed with conductivity water. The resulting product was dried in a drying oven and stored in mason jars. The impurities (spectrographic) were as follows: Al, 0.01 to 0.001 pct; Li, Mg, Mn,, Na, each less than 0.001 pct; Fe and Cu not detected. The specific surface of the quartz sample was determined by the krypton gas adsorption method.7 The average of two measurements was 881 sq cm per g. The calculated specific surface for 37/74 micron quartz particles, using a surface factor of 1.96,8 is 900 sq cm per g. This is in good agreement with the measured value of 881 sq cm per g. Beta-Counting Method: The radioactive isotope of barium used in the experimental work was barium 140. It has a sufficiently long half-life, 12.8 days, emits high-energy beta particles (up to 1.0

Jan 1, 1952

By C. K. Leith

Jan 1, 1906

By A. F. Bertuzzi, M. R. Tek, F. H. Poettmann

A method is presented for predicting pressure drop for two-phase fluid flow in horizontal pipes. A set of 267 experimental measurements randomly sampled from approximately 1,000 measurements from various literature sources was used. Pressure gradients calculated by the procedure developed and compared with the experimental values showed a bias of +0.82 per cent and a standard deviation of 20.8 per cent. The advantatges of this method over other available methods of predicting two-phase flow pressure drop are (a) its comparative simplicity of application, (b) its relative independence of flow patterns, (c) its accuracy, which on the basis of a statistical evaluation predicts pressure drop closer than other available methods, and, (d) its ability to satisfactorily correlate laboratory data from various sources while the correlations from these sources do not appear to agree with one another. The method has been reduced to a simplified graphical procedure, suitable for field use. A two-phase f factor is defined and correlated with parameters involving the flowing gas-liquid mass ratio, a Reynolds number for the gas phase, and a Reynolds number for the liquid phase. The choice of parameters allows the correlation to reduce to the usual f factor plot for the limiting conditions of (111 gas or all liquid. INTRODUCTION The mechanics and characteristics of two-phase flow systems have been of interest throughout the industry for some time. In numerous engineering installations such as pipe lines, chemical reactors, and heat exchangers, two-phase flow conditions are of every day occurrence. In oil production operations it has been desirable, in some cases, to consider transporting gas and oil together in a common pipe from oil field to process plant. The trend toward centrally located stock tank batteries in oil fields has resulted in longer gathering pipelines in which more than one fluid phase is flowing. The increase in the producing capacity of oil wells due to new production tech- niques has created the need for review and re-design of many surface gathering lines for properly handling the increased production. Optimum pipe size for the situations described above has become an important factor. The problem which is of interest here involves the ability to predict the relationship between pressure drop, fluid properties, fluid rates, pipe diameter, and pipe length. Although the literature1,5,10,13,18,19 contains various articles dealing with specific cases of the problem, Lock-hart and Martinelli17 proposed the most general solution. Their method has been later modified by Baker:1 Alves2 demonstrated that different flow patterns are possible for a flow mechanism defined by Martinelli such as gas turbulent, liquid turbulent. Baker explained deviations experienced with Martinelli's correlations on the basis that different flow patterns could exist for the same flow mechanism. Using Martinelli's method of correlatioil, Baker correlated data for each flow pattern for the turbulent-turbulent flow mechanism. Bergelin and Gazley6,7 presented a correlation for predicting gas phase

Jan 1, 1957

By Persifor Frazer

The rocks which cover the east flank of the South Mountain are chloritic schists typical in character. A specimen of this rock from near the Bechtel shaft, Hamilton Ban Township, Adams County, Pa., was selected and analyzed in my laboratory by Mr. C. Hanford Henderson, with the following results: Ignition,........2.740 CaO,..........7.040 SiO,,..........41.280 MgO,.......... 7.486 AI,O,,.........18.480 K,O,..........2.208 Fe,Os,.........9.440 Na,O,.........3.523 FeO,......... 8.200 100. As one penetrates the range by moving westvard, these schists are replaced either by epidotie quartz or by orthofelsite. In the former case, a belt of copper-bearing rock is traversed, but not in the latter case. Inasmuch as this junction of the chloritic schists on the southeast and orthofelsite on the northwest, separated by the epidotic quartz, is several times repeated, we find two or three copper belts arranged in general parallelism to the axis of the chain, because the copper horizon is generally at this junction. Thus, in going west from Fairfield, after entering the low spurs on the South Mountain, one is fairly within the chlorite measures. At the " Virginia Mills " a chlorite schist comes in with a dip of S. 1.5 E.-74 Half a mile up Middle Creek, large numbers of fragments of chlorite schist, decoruposed epidotic matter, and quartz are encountered. The former rock, where in place, dips E. 40" S.-57o. About 4000 feet west of the intersection of this road with the so-called Tape-Worm Railroad, near the house of one Singly, large masses of chloritie schist are found loose on the road. A hundred yards farther west, near a triangle in the road, the latter is less in quantity and much epidotic quartz appears, after which a very large display of orthofelsite succeeds on the left bank of Middle Creek. All these last-mentioned rocks, however, are in fragments. Crossing the stream again a few hundred yards farther On, the chlorite fragments at first preponderate, and then large numbers of both rocks

Jan 1, 1884

THE following paper has been prepared to meet a demand for a concise review of the California oil industry. It is based largely upon information secured during the course of the senior, author's professional activities, and upon data obtained during the course of investigations for the U. S. Geological Survey and the U. S. Bureau of Mines. Considerable information has been obtained from other sources, and to those who by publication or otherwise have contributed, the writers extend their thanks. GENERAL STATEMENT In 1912 the United States produced 63.25 per cent. of the world's production of petroleum, Russia, its nearest competitor, yielding only . about 19 per cent. The production in 1912 reached 222,113,218 barrels (or 29,615,096 metric tons), compared with 220,449,391 barrels in 1911. The average price per barrel in 1912 was nearly 74 c., as against nearly 61 c. in 1911. The total value, therefore, increased 22.20 per cent., or $163,802,334 above the value for the previous year. These figures of production include pipe-line runs, independent railroad shipments, oil piped direct to refineries, and the crude oil consumed as fuel in oil production. The production does not include oil in storage in the field which has not been sold.

Jan 3, 1914

By Albert Sir Kitson

THE manganese ore deposits of the Gold Coast, British West Africa, occur in very ancient rocks, of both sedimentary and metamorphic types. In. certain respects, they strongly resemble those of India and Brazil, as contrasted with those of Tertiary age in Georgia. Viewed from the present condition of the maganiferous rocks, the oldest deposits are in the sediments. Later than these are the progressively metamorphosed representatives of these sediments; youngest are the products of decay and degradation with the concentration of manganese oxide of both areas. The oldest occurrences are in argillaceous and siliceous phyllites and slates, which show only a moderate amount of metamorphism. They belong to a series which also includes mudstones, sandstones, grits, conglomerates and subordinate limestones, with tuffs and lava-flow's largely of basic types. To this series I have given the name Birrim. Its age is unknown, for no definite fossils have been discovered in it. As the characteristics of these non-fossiliferous strata at many places are the same as those of strata in many parts of the world that are suitable for the preservation of fossils and that contain them, it is assumed that the Gold Coast deposits are pre-Cambrian. These rocks of the Birrim series have normally a northeast-southwest strike and are folded, but not to any very great degree except in certain belts. From the Eastern Province of the Gold Coast they may be traversed across their strike for more than 600 miles to the extreme northwestern corner of the Northern Territories. Thence they probably extend much further into French Territory.

Jan 1, 1927

For the US coal industry, 1978 was a nightmarish recurrence of 1977 as the United Mine Workers strike cut into production during the first three months of 1978, followed by the strike against the Norfolk and Western Railway during the summer and early autumn. Coking coal production was floored by the one-two punch of environmental constraints on US coke ovens and competition from low-cost, high-quality imports. At the same time, US ex orts of coal fell to their lowest level since 1962. And in the face of all of this, steam coal consumption was sluggish as utilities burned huge amounts of oil to conserve coal stockpiles during the UMW strike. This was followed by decreased electrical demands due to mild summer weather in many parts of the country and dramatically improved availability of hydroelectric power.

Jan 5, 1979

By E. A. Elevatorski

Wollastonite, named after William H. Wollaston, an English chemist, is a calcium metasilicate, CaSiO3. It has a short history as an industrial mineral. The earliest production of wollastonite is reported to be from a deposit near Code Siding, located north of Randsburg, Calif. At this locality small tonnages of wollastonite were quarried during 1933-34 and 1938-41, and processed into mineral wool. This operation was largely experimental and virtually no United States production was again reported until the 1950s when a large deposit near Willsboro, N.Y., was developed by the Cabot Corp. A processing plant was placed on-stream in 1953, with nearly continuous production to date, and it is currently operated by Interpace Corp. Since 1958, wollastonite deposits in the Little and Big Maria Mountains of Riverside County, and in the Panamint Range of Inyo County, both in California, have operated intermittently for production of both ornamental and commercial wollastonite. During 1973, the United States was the major producing country, furnishing about 75% of the world's output. Recent production also has come from Finland, Mexico, and Kenya. Small amounts have been shipped intermittently from India, USSR, New Zealand, Republic of the Sudan, Republic of South Africa, and South-West Africa. The principal use of wollastonite is in the manufacture of ceramics, especially wall and floor tiles. Other uses are for paints, fillers, adhesives, reinforcing agents, plastics, fluxes, and glazes. Mineralogy Pure wollastonite, CaSiO3, has the composi¬tion of 48.3 % CaO and 51.7 % SiO,. However, it is seldom found in the pure state due to the ease with which it takes into solution the metasilicates of manganese, magnesium, iron, and strontium. Predominantly, wollastonite occurs as a contact metamorphic deposit forming between limestones and igneous rocks. Commonly associated minerals are garnet, diopside, epidote, calcite, and quartz. It has a specific gravity of 2.8 to 3.0, and hardness of 4.5 to 5 on Mobs' scale. When pure, it has a brilliant white color, but with impurities it may be grayish or brownish. Luster is vitreous to pearly. Melting point of wollastonite is about 1540° C. Wollastonite occurs in coarse-bladed masses, rarely showing good crystal form. It is usually acicular or fibrous, even in the smallest of particles. The most unique property of crushed and ground wollastonite is its cleavage. Fragments of crushed wollastonite tend to be needle-shaped, imparting a high strength, and this property is the basis for many of its uses. The fiber lengths are commonly in the ratio of 7 or 8 to 1, length to diameter. Some crystals of wollastonite fluoresce under short-wave or longwave ultraviolet light, or both; colors ranging from yellow-orange to pink-orange. Specimens may also show phosphorescence. The brightness of wollastonite is a property of considerable importance to the paint industry. Material, 99% pure, with a size of -325 mesh, has a General Electric reflectance rating of 92 to 96%. Chemically, wollastonite is inert and this property makes it useful as a filler and reinforcing agent. There are two polymorphs of calcium silicates: wollastonite, a low temperature form, and pseudowollastonite, a high temperature form. Inversion of wollastonite to pseudowollastonite occurs at about 1120° C, resulting in an increase in the coefficient of expansion and a color change. Pure white wollastonite, on inversion, may change to a cream tint, or various shades of red or brown. The color change is thought to be due to the presence of iron and strontium.

Jan 1, 1975

By William Hutton Blauvelt

Coke is the product of dry distillation of bituminous coal, by which the volatile matter is driven off, producing a hard body of cellular structure. Not all bituminous coals will coke, and there has been much discussion regarding the substance which is present in coking-coals to distinguish them from dry coals. Professor Lewes says that the bituminous matter in coal is largely derived from the spores of fossil mosses. Resins are present in all soft coals, and contribute largely to the cementing of the coke. The resinates and hydrocarbons begin to distil out at moderate temperatures and leave the pitchy residual, which at 500' C. forms a mass already well caked together, if the proportion of humus residual is not too great. This coke is soft, but if the heat be raised to 1,000° C. the pitch decomposes further, leaving carbon, and Professor Lewes is convinced that the coking bond is due to these liquid products which distil off, leaving pitch, which then carbonizes and binds the mass into coke. Professor Parr concludes that the structures of the organic compouilds of the coal Which furnish the cemeding-material for coke, and which are apparently attacked by oxygen, have not been determined and seen] to vary somesvhat in different types of coal. However, they yield, on oxidation, humic acids of varying composition which decompose into powdery residues. Because of the complex nature of these substances and the difficulty experienced in isolating and identifying them, the theory of coking is still an open problem and the explanations advanced are largely hypothetical. In the coking process the volatile matter driven off in the oven consists mainly of tar, ammonia, and gas, familiarly known as by-products. Both the quality and quantity of coke and by-products vary greatly With the composition of the coal.

Jan 1, 1913

Gentlemen of the American Institute of Mining Engineers.—As you well know an application is about to be made to Congress, by the American Society of Civil Engineers, for the appointment of a cornmission composed of persons skilled in the production and use of iron, steel, and other structural materials, whose duty it shall be to test the strength, elasticity, and other quatities of such materials ; not simply the substances used as such, but the members of large structures composed of such materials, of the forms and sizes in which they are actually used. As I understand, the papers that will be read here to-night will have for their object to show the necessity for such tests, and therefore the necessity for the commission asked for. As the representative of the Society of Civil Engineers, I have to thank you, gentlemen of the Mining Engineers, for the great zeal with which yon have taken up this subject, and seconded the efforts of the Civil Engineers; or, perhaps I ought rather to say, initiated the efforts to get a suitable commission appointed to obtain most vitally important information which it is admitted on all hands we do not now possess. In drawing up the memorial to Congress, in connection with some of the ablest and best informed of our Society, and in all the discossions on the subject, I have been struck with the emphasis with which the confession is made, that so little is known of the strength of the larger-sized members constantly used in building structures of the magnitude which the present requirements of the country now demand. I presume the remarks made to-night will bring this out very prominently. This is no disgrace, for with the means here-

Jan 1, 1882

By W. A. Nagel, R. P. Alger, H. Sherman, J. Tittmann

A sidewall epithermal neutron tool has been developed to substantially reduce environmental effects that have previously complicated neutron log interpretation. Designed for operation in uncased wells, the device provides increased accuracy in both liquid-filled and empty holes. A brief discussion of neutron moderation, diffusion and capture shows that logs using epithermal neutron detection depend on a smaller number of formation-characterizing parameters than those using thermal neutron or capture gamma ray detection. Thus, they come closer to providing an unambiguorls determination of hydrogen content. In this new device a directionally sensitive epithertnal neutron detection system has been incorporated in a side-wall source-detector skid to minimize borehole effects. The effects of variations in borehole size and shape, mud type, temperature and salinity are greatly reduced. Small residual borehole effects are then computationally accounted for in the surface control panel to provide a borehole-corrected neutron log. The log presents a direct recording of neutron-derived porosity on a linear scale. With corrections for borehole effects already applied, this direct recording of porosity simplifies log interpretation. Furthermore, comparison with a linear porosity presentation of a formation density log permits sandstones, limestones and dolomites to be readily identified. Thus, in complex or variable lithology, porosity is determined with greater accuracy and reliability than heretofore. Laboratory data and field results demonstrate the improvements in neutron logging afforded by this new side-wall epithermal neutron logging device. INTRODUCTION The new Sidewall Neutron Porosity (SNP) logging system, designed for use in uncased wells, provides reliability and accuracy never before achieved with neutron logs. The effects of variations in borehole diameter and shape, fluid salinity, mud weight and temperature—parameters that have long complicated neutron log interpretation— are suppressed or corrected for by this sidewall epithermal neutron detection system. Furthermore, to simplify interpretation the SNP log presents a direct recording of computed porosity on a linear scale. The performance improvements achieved by this new system arise primarily from the combination of two im- portant design features. First. though not unique to this new tool, an epithermal neutron detection system is used,',' Epithermal neutron detection substantially reduces the perturbing influences of the thermal neutron absorption properties of rock matrices and water salinity. Second, the neutron detection system is mounted in a directionally sensitive sidewall skid to greatly minimize borehole effects. The purpose of this paper is to explain briefy the advantages offered by the detection of epithermal neutrons, to describe the SNP equipment and the log, to present calibration and correction data and to give examples of interpretation methods made especially convenient by this new system. ADVANTAGES OF EPITHERMAL NEUTRON DETECTION Epithermal neutron detection, of all the neutron methods in current commercial use, provides the simplest determination of formation hydrogen content. Advantages of epithermal neutron detectors, as compared with thermal neutron and gamma ray detectors, are probably best explained by a brief review of the life of a source-emitted neutron. A fast neutron from the source will eventually be cap-tured by the nucleus of an atom. However. before capture is likely to occur, the fast neutron (energy of 100,000 electron volts (ev) or more) will be slowed down until it is in thermal equilibrium with its surroundings. The neutron is then considered to be a "thermal" neutron (average energy of 0.025 ev at 25C). The overwhelming majority of the slowing down thus occurs in reaching epithermal energies (energies just above thermal—0.5 to several ev). After reaching thermal energy. the neutron will "diffuse" through the formation with, on the average, no further energy change until capture. Upon the capture of the thermal neutron, relatively high energy gamma rays arc usually emitted. Hydrogen plays a very important role in the process of slowing down fast neutrons. On the other hand, the absorption effects of water salinity and low concentrations of other strong thermal neutron absorbers—relatively unimportant in the moderation process-—are very important in thermal diffusion, capture and the production of gamma rays. Thus, by detecting only epithermal neutrons with the SNP, spurious effects due to these thermal neutron absorbers are greatly minimized as compared to the effects on tools using thermal neutron or gamma ray detectors. The epithermal neutron detection system affords another important advantage. Log response in various litho-

Jan 1, 1967

CHARGING of an open-hearth heat is begun as soon as possible after the previous heat has been tapped. Ordinarily, about 40 min is required to drain and dress the furnace hearth, make up the taphole, and perform routine repairs of the banks. Repairs to the upper back wall and to the front wall and jambs can ordinarily be done while the first scrap charge is being heated and are therefore allowed to wait in order to save furnace time. Any major repairs required on the hearth or other parts of the furnace necessitate longer delays because such repairs must be made while the furnace is empty. Although charging practice varies considerably in detail with the type and proportions of scrap and iron used, many factors are common to all varieties of charge. Such general considerations are dealt with first. CHARGING EQUIPMENT AND STOCK HANDLING The physical equipment available for loading and weighing the stock, transporting it to the furnace, and charging it, may have a major effect on charging practice. Limestone, scrap, and all other solid melting stock are charged mechanically by means of equipment illustrated in Fig 2-1. The charging of hot metal is shown in- the background of this figure. Mechanical equipment and plant layout for stock handling are described in Chapter 1. It is generally desirable to charge the scrap about as fast as the physical volume can be put into the furnace. Charging scrap that is too heavy or adding the charge too rapidly (less than 45 min) may be detrimental to melting rate because of excessive chilling of the entire furnace system and also because of poor conduction of heat to the lower layers in the furnace; but the more common problem is the reverse one of charging light scrap fast enough to maintain a normal heat time. A limiting factor may be the height to which the scrap may he piled in the fur-

Jan 1, 1964

By Joseph L. Gillson

BRAZIL has had an industry based on ocean beach deposits of heavy minerals containing monazite, zircon, rutile, and ilmenite for well over 40 years, but except at the very earliest period, prior to 1906, and again during World War 11, has this industry been at all comparable in size with similar operations in other countries. Limiting factors have been neither a lack of reserves nor lack of markets (except for zircon). Although poor local transportation and shipping facilities have handicapped the development in Brazil, these conditions were perhaps equally bad (when mining operations started) in the Indian State of Travancore, and in New South Wales and Queensland, Australia, in which states the principal production of beach deposits of heavy minerals has occurred. The outstanding restraints on the Brazilian industry have been the lower quality of the Brazilian minerals, the relative small size of individual deposits that were known until recently, the lack of interest of Brazilian investors in mining ventures, and the unfavorable climate for investment of foreign capital under Brazilian mining law. The lower quality of the minerals is indicated by the fact that the Brazilian monazite carries only 5 to 6 pct ThO2,*, and the ilmenite 56 1/2 pct TiO2, whiteness of the Australian zircon. An inadequate market for the abundant zircon that will be avail- able in any operation in Brazil is certainly a heavy restraint, since otherwise it could be an important byproduct. The oxide of zirconia, baddeleyite, that has come from Brazil is from other sources. 1 Since the Brazilian beach sands carry only a little rutile, that mineral has not been available as a valuable byproduct to help finance the operations.

Jan 6, 1950

By T. L. McCall

The late Walter Herd1 in 1929 gave a full description of past and present conditions in No. 2 mine, Springhill, Nova Scotia, developed theories regarding the cause of these bumps and made certain suggestions regarding possible methods of future development. Recapitulating briefly from Mr. Herd's paper, the seam is bituminous coal, averages 9 ft. in thickness and has a well defined parting containing fusain about 14 in. from the roof. This roof coal is somewhat stronger than the rest of the seam and has a tendency to cling to the roof. The pitch of the seam where it is now being worked is about 20". The first manifestations of bumps began when the room and pillar workings had reached a depth of cover of 1900 ft. and under continuously increasing depth of cover these bumps increased to such an extent, both in number and severity, that in the year 1924 it became apparent that some change in the system of extraction was necessary. After closely studying all the factors involved and benefiting largely by valuable outside advice obtained by the Provincial Department of Mines of Nova Scotia,2 the system of working was changed from room and pillar to longwall retreating. Mr. Herd's paper described in detail three remarkable bumps in the year 1928 in April, July and October that affected the 5700-ft. and 5900-ft. East levels, the last bump being so severe both in intensity and in extent of damage done that this district was abandoned. The longwall workings to the west of the slope had been stopped in the year 1926 owing to an inbreak of water, coming from the flooded waste of No. 3 seam lying some 400 ft. vertically overhead. This inflow was not excessive, but a large quantity of water being impounded in the old workings it was considered advisable to take the prudent course and not incur the risk of possibly increasing the flow by further working. This district has remained idle ever since.

Jan 1, 1934

By A. H. Geisler

INTRODUCTION THE correlation of property changes during precipitation with structure has progressed, sometimes rapidly but other times more slowly, since the fundamental discovery of Merica, Waltenberg and Scott.1 The predominent factor that hampered the progress has been limitations imposed by the various detection methods. Refinements in X ray diffraction techniques and in metallographic methods, which have been extended by the electron microscope, have contributed new information within the last few years. These permit an extension of the theory as proposed by Mehl and fetter in 1940.2 Now that a suffcient number of alloys has been investigated to establish a general mechanism of the precipitation process, a correlation of the facts into a generally applicable theory of age-hardening is both warranted and desirable. 'I he purpose of the paper is to provide an orderly correlation of the phenomenological facts of precipitation hardening. Speculation on mechanism of hardening will be confined to that consistent with existing theories of hardening. Age-hardening accompanies the formation of a new structure, the precipitate, as provided by an alloy system in which solid solubility decreases with decreasing temperature. Upon this premise alone all such systems would be expected to include age-hardenable alloys. Alas, this is not always the case. Few attempts have been made to explain the variable degree of age-hardening among different alloys or to explain the influence of small alloying additions upon the hardening. Dispersion hardening as originally postulated3 is not adequate.* Coherency hardening-the term that will be used to distinguish the properties of a two-phase mixture in the unique and unstable transition state at which the phases are strained into precise atomic registry (continuity or coherency) in planes

Jan 1, 1948