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By J. W. Mitchell

Season cracking of 70-30 cartridge brass cases of small arms and artillery ammunition has been under investigation at the Frankford Arsenal for many years. The nature of this stress-corrosion failure has been found to be intergranular. Much of this work, however, has been directed toward improvements in method of manufacturing the cases so as to reduce the tendency to season crack and little progress had been made toward finding the source of the chemical agent producing the inter- granular corrosion. Ammonia has been shown to produce season cracking in brass and is known to be present in certain atmospheres, particularly industrial, in sufficient concentration to cause cracking. However, in the case of small arms ammunition, the hypothesis that atmospheric ammonia is the cause will not hold, since small arms ammunition is hermetically sealed during storage and yet occasional lots are found to have cracked after 3 to 5 yr. storage. Much of the early study of season cracking in small arms ammunition was done by Nicholas H. Murdza of the Frank- ford Arsenal. In 1936, he suggested that the corrosive agent might be one of the decomposition products of smokeless powder and mentioned nitrogen oxides specifically. Then in 1937, Murdza suggested that the breakdown of smokeless powder in storage resulted in the formation not only of nitrogen oxides but also ammonia

Jan 1, 1945

By R. H. Hiltz, N. J. Grant

Solid-solution titanium-cerium alloys, cold-rolled to 0.010 in. thickness, and annealed, were internally oxidized to produce a fine dispersion of CeO2 in the titanium matrix. The oxidized alloys were cut into sheet stress-rupture specimens and tested for rupture life at 426°C, 538°C, and 648°C. There was noted an improvement in strength over that of pure titanium, the internally-oxidized alloys showing curves with a much flatter slope on the log stress—log rupture life plot, characteristic of the stable metal-metal oxide class of alloy. DURING the past 3 to 4-year period, considerable interest has been aroused by the potential offered by alloys based on the ultra fine dispersion of a hard insoluble phase in pure metals or solid-solution alloys for use at high temperatures. The impetus to the development and study of such alloys was provided by Irmann.1,2 through the success of the SAP alloy (pure aluminum containing about 12-14 volume pct of A12O3). Subsequent studies have thrown light on the true potential of this class of alloys in the remarkable stability of the structure after long-time exposure at high stresses and high temperatures.a-5 While success has been demonstrated in the special case of the A1-Al2O3 alloys, and more recently

Jan 1, 1959

By P. Shahinian, J. Weertman

Minimum creep rates of nickel samples were measured in the stress region of 2.5x107 to 2.8xl0 dyne per sq cm and the temperature region of 400° to 1100°C. The creep rate seems to be proportional to (stress) at stresses below 7x10H dyne per sq cm. The activation energy of creep is approximately 65,000 cal per mol. IN a recent theory' of steady-state creep which is based on Mott's dislocation climb mechanism, the following creep equation was derived for creep in polycrystalline metals (if where K is creep rate, Q the activation energy of self-diffusion, S the entropy of activation of self-diffusion, L' the grain size, L the subgrain size, b the length of the Burgers' vector of a dislocation, u the shear modulus, u the stress, a the critical shear stress, M the density of active Frank-Read sources, v the vibrational frequency of a vacancy, and kT has its usual meaning. This equation predicts a creep rate which depends on the stress through a power law at low stresses. At high stresses the creep rate increases much more rapidly with stress. The theory breaks down for stresses great enough that the inequality holds true. It was the purpose of the present in-

Jan 1, 1957

By D. M. McFarland

A FEW years ago a novel electric detonator known as the split-second or millisecond delay electric blasting cap was introduced for use in quarry blasting. Regular electric blasting caps fired in series may be depended upon to fire within a millisecond or so from the first to the last in a series. Regular delay electric blasting caps are provided that fire one period after the other period in intervals of 1/2 to possibly 1 1/2 sec. Most split-second or millisecond delays are designed to fire one period after the other period in possibly 25 to 50 millisecond intervals. The ear is not capable of detecting time intervals of this magnitude. The primary thought at the time millisecond de- lays were introduced was to investigate the results on rock breakage by firing a line of holes in a quarry face.so that charges in adjacent holes would not be detonated simultaneously. This could not be accomplished satisfactorily with regular delays. The time interval between successive periods of $5 to 1 sec was sufficient to permit considerable movement of the burden. If the burden of one hole was reduced to a great extent by the firing of an adjacent hole, the firing of the hole with the reduced burden would likely reveal this lack of confinement by a terrific report and wild throw of rock.

Jan 1, 1950

By Charles R. Fettke

BefoRe the Drake well on Watson Flats below Titusville, Pa, inaugurated the modern petroleum industry on Aug. 28, 1859, a considerable industry, based on the manufacture of mineral oils through the destructive distillation at relatively low temperatures (750' to 800' F.) of cannel coals and shales in closed, air-tight retorts, had already sprung up in Europe and America because of the increasing cost of animal and vegetable oils and fats and the growing demand for illuminating and lubricating oils. In 1860, eight out of 55 such coal-oil companies in the United States had plants located in Pennsylvania.' Of these, the Lucesco Works, costing $120,000, situated near Kiskiminetas Junction, was the largest operating in the country. It was equipped with 10 revolving 2.5-ton retorts and 16 stills for rectifying the oil, each holding 2000 gal. The total output of crude oil was almost 6000 gal. per day.2 The discovery of an abundant supply of natural petroleum by the Drake and other wells stopped the distillation of coal oil in America. Most of the smaller plants were closed and others were converted into petroleum refineries. At present, in spite of the temporary over-production of petroleum, the coal and oil-shale carbonization industries are again attracting the attention of far-sighted oil companies who realize that the gradual exhaustion of the American petrol-

Jan 1, 1923

By Charles R. Fettke

BefoRe the Drake well on Watson Flats below Titusville, Pa, inaugurated the modern petroleum industry on Aug. 28, 1859, a considerable industry, based on the manufacture of mineral oils through the destructive distillation at relatively low temperatures (750' to 800' F.) of cannel coals and shales in closed, air-tight retorts, had already sprung up in Europe and America because of the increasing cost of animal and vegetable oils and fats and the growing demand for illuminating and lubricating oils. In 1860, eight out of 55 such coal-oil companies in the United States had plants located in Pennsylvania.' Of these, the Lucesco Works, costing $120,000, situated near Kiskiminetas Junction, was the largest operating in the country. It was equipped with 10 revolving 2.5-ton retorts and 16 stills for rectifying the oil, each holding 2000 gal. The total output of crude oil was almost 6000 gal. per day.2 The discovery of an abundant supply of natural petroleum by the Drake and other wells stopped the distillation of coal oil in America. Most of the smaller plants were closed and others were converted into petroleum refineries. At present, in spite of the temporary over-production of petroleum, the coal and oil-shale carbonization industries are again attracting the attention of far-sighted oil companies who realize that the gradual exhaustion of the American petrol-

Jan 1, 1923

By R. W. Smith

IN the manufacture of portland cement, the basic and fundamental essential is a limestone uniformly rich in calcium carbonate and carrying less than 3 per cent magnesium carbonate. In searching for such a deposit, also having in mind quantity of rock, accessibility and quarrying facilities, the Pacific Coast Cement Co. discovered and developed its present quarry at View Cove on the east coast of Dall Island, Alaska. Dall Island is about 100 miles west of Ketchikan and 650 miles north from Seattle. It is 70 miles in length and 5 to 10 miles in width. The climatic conditions are much more favorable than would be expected. The temperature ranges from zero to 70 degrees. The precipitation is considerably more than at Seattle, although there was less snow during the last season than at Seattle. The island is rugged and mountainous; the vegetation is moss and grass and a large portion is timbered with spruce, hemlock and cedar. Some of this timber has market value. The limestone quarry is about 30 miles north of the extreme southern end of the island. The company acquired 240 acres which contain limestone of remarkable uniformity, the percentage of calcium carbonate being about 95. It is estimated that there is ample recover- able rock on the holdings to supply the cement plant at its maximum capacity for well over 100 years.

Jan 1, 1929

By D. J. McAdam

RESULTS of investigation of corrosion-fatigue of metals at the U. S. Naval Engineering Experiment Station, Annapolis, Md., have been discussed by the writer in several recent papers. 1.2.3.1 In those papers references were also given to the work of Haigh in 1917.6 Efforts by the writer to obtain a better understanding of some of the factors involved in corrosion-fatigue finally developed into a general investigation of the effect of time and cyclic stress on corrosion of metals. Corrosion fatigue of Metals As described in the papers mentioned, rotating-cantilever specimens, conically tapered so that the stress is nearly uniform over a length of about 1.5 in., were subjected to simultaneous fatigue and corrosion. For this purpose a stream of water was diagonally applied so as to sweep the specimen from the outer to the inner fillet and surround the stressed surface with water. The fresh water is a calcium carbonate water, the composition of which has been given in a previous paper .2 The salt water is Severn River water having a saline content about one-third that of sea water. The previous papers described results obtained with ferrous and nonferrous metals. The experiments showed that even slight corrosion simultaneous with fatigue may cause failure at nominal stresses far

Jan 1, 1928

By J. J. Scott

During 1967 wage settlements and strikes ran at a high rate and it has been estimated that union gains of 4 ½ % to 5% per year have been attained in many instances. When these events are coupled with the need to operate on lower grade and deeper deposits the need for technological advances in underground mining becomes obvious. Emphasis has been on ways to reduce the number of manshifts required per ton of product. Most significant advances have been made in rapid advance of primary mine openings, development of mobile, rubber-tired, front-end loaders and hauling units, high-speed drilling with rotary and rotary percussive units and a serious look at nuclear devices to break large volumes of ore cheaply. Boring Developments in bit manufacture and metallurgy have allowed continuous boring-type machines to be used on harder formations than was deemed feasible in the past. Hecla Mining Co. has been using raise boring equipment for drilling 9 7/8 in. diam pilot holes in raises which are later reamed in an upward direction to 48 in. diam. The machine used is a J. S. Robbins model 42R raise borer which has been used successfully to drill two relatively long 48-in. diam holes. The first was 520 ft in length at a dip of 76º, and the second was a 785-ft vertical hole.

Jan 2, 1968

By J. H. Frye, S. G. Holder, E. E. Stansbury

Internal friction studies on annealed and cold-worked pure silver and alloys of silver with 4.5 atomic pct each of Cd, Sn, and Sb are reported. Small amounts of cold work, introduced by stretching pure silver, decrease the internal friction; large amounts of cold work, by wire drawing, cause this decreased internal friction to rise. Results of severol anneoling histories on the room-temperature in-ternal friction indicate a rather complex recovery and recrystallization behavior. A rather system-atic alloy effect is observed for the elements of Period V-B in silver in both the annealed and cold-worked states. DURING recent years internal friction measurements at very small stress levels have been interpreted in terms of structural models and mechanisms occurring within the metal or alloy.These measurements have been made over wide ranges of frequency of vibration and of temperature. While the effects of impurities, alloying, and plastic deformation have been studied by numerous investigators, no investigations of the effect of a series of solutes related by their position in the Periodic Table on a given solvent seem to have been reported. The present paper reports internal friction measurements on silver and on certain silver-base solid solutions to determine the values of room-temperature internal friction associated with varying amounts of plastic deformation and after different annealing

Jan 1, 1957

By C. C. Harris

The 3-parameter equation* was introduced1 as having the necessary form and flexibility for describing the major features of size distribution curves. Also, Eq. 1 was shown to contain most of the widely used 2-parameter equations as special cases. Special methods are necessary in order to determine the parameters of 3-parameter equations by graphical means. The procedure given previously required double graphical interpolation followed by regraphing the interpolated data. The theoretical basis of the method was a difference equation eliminating y. Several other methods for obtaining the parameters have been under development and one method appears to overcome the disadvantages of the earlier method and satisfies several procedural requirements. The points in favor of the new method as compared to the earlier method are as follows: 1. Estimation of the quality of fit is direct, and is in fact an essential part of the procedure. 2. The data is plotted directly without the necessity of interpolation from a graph. 3. The method makes use of Rosin-Rammler2 paper which because of expanded scaling in the coarse sizes leads to improved accuracy1 as compared with the log-log plot for the Gates3-Gaudin4-Schubann5 representation. 4. There is a gain over the earlier method in overall accuracy and in simplicity.

Jan 1, 1970

By Wm. E. Milligan

LEAD stocks at the beginning of 1943 were comfortable when compared with those of other base metals such as copper, zinc and tin. This situation was early recognized by W.P.B. and other Governmental agencies and every effort was made to encourage the substitution of lead for these latter metals in all essential uses. Despite this apparently healthy condition, lead was not denied participation in the various measures inaugurated by the Government to relieve metal shortages. Thus in the Mexican trade agreement, effective Jan. 20, the tariff on two important classes of lead importss was halved. Similarly, in the setting up of B quota premiums, a B base was allotted to lead, with all pro¬duction above this figure receiving an additional payment of 2.75c. per lb., or a total payment of 11.75c. per lb. At about the same time it was announced that all quota transactions would be based upon the lead content as shown by the smelter settlement sheets. This basis was 86 percent of the lead content for all ores shipped to custom milling plants and 95 per cent for ores and concentrates shipped to custom smelting plants. The importance of this action can be appreciated when in the Coeur d'Alene it was estimated as equivalent to a 5 per cent increase compared to the previous base.

Jan 1, 1944

By E. M. Wise

THE properties required of gold alloys for jewelry are not well standardized, due in part to problems peculiar to certain branches of the jewelry industry, in part to the individual preference of the fabricator and to his willingness to cope with certain difficulties in manufacture, which arise with the use of certain alloys. GENERAL REQUIREMENTS In general, the properties desired may be classed as follows: 1. Color should conform to the dictates of good taste and smart style. 2. Corrosion resistance and tarnish resistance should be good. This is to a considerable extent determined by the carat. Resistance to such corrosive agents as mercuric chloride as well as certain depilatories is unreasonable to expect and difficult to meet. 3. Strength and hardness must be adequate to maintain the delicate contours of finely modeled jewelry. 4. Wear resistance must be great enough to resist abnormal wear, such as is encountered by a wedding ring in a lifetime of wear. 5. Ductility must be sufficient to permit the fabrication of drawn shells, tubes and difficult shapes. Material having a yield point of not less than 60,000 lb. per sq. in., an ultimate strength of 100,000 lb. per sq. in., and an elongation of 40 per cent. is desirable. 6. Melting point should be between 800° and 1200° C.

Jan 1, 1928

By A. D. Zunkel, A. H. Larson

Equilibrium antimony contents of pb-sb alloys in contact with PbO-Sb2O3 slags containing less than 45 mole pct Sb203 uleve determined at 650', 700°, and 750°C in an inert atmosphere. In this ten~pevature range, the antimony contmzt of the alloy increased with increasing temperature at all slag compositions. The PbO-Sb203 phase diagram below 28 mole pct Sb2O3 was determined by thermal analysis and by application of a log sbZ4/y$b0 us plot determined from the equilibrium-activity data. The resulting phase diagram showed a eutectic at a temperature of 604°C and a comfiosition of 21.6 mole pct Sb2O, with a maximum terminal solid solubility of Sb203 in PbO of 5.6 mole pct. These results are compared with existing data in the literature. In the past three decades, only a small amount of experimental work has been done on the slag-metal equilibria in the Pb-PbO-SbaO3 or the analogous arsenic and tin systems. These systems are important in commercial lead-refining processes such as softening and dross fuming since it is impurities such as antimony, arsenic, and tin in lead bullion and Sb2O3, As2O3, and SnOz in lead drosses which must be re-

Jan 1, 1968

By Jackson R. Pellett

INTRODUCTION The Friedensville mine is situated in Upper Saucon Township, Le- high County, Pennsylvania, in the southern central part of the Allentown quadrangle of the United States Geological Survey, approximately 5 miles southeast of the City of Allentown and 4 miles south of the City of Bethlehem. Zinc was first discovered in the Friedensville area early in the 19th century and several mines were operating during the latter part of the century. Zinc oxide was produced in 1853 and zinc metal in 1859. All mining in the area ceased in 1893 chiefly because of an unfavorable economic situation caused by a severe ground water problem and competition from the higher grade ores in New Jersey. Property acquisition by the New Jersey Zinc Company began in 1899 and periodic exploratory drilling was carried on until 1940 when sufficient reserves were proved for development of a mine. Shaft sinking was undertaken in 1947 and, due to severe hydrologic conditions, was not completed until 1952. Production began in 1958 and today the mine is producing about 64,000 tons of zinc concentrate per annum. The concentrates are trucked to the Company's smelter at Palmerton, Pennsylvania, approximately 30 miles north of Friedensville. The mine also produces from its mill tailings industrial and agricultural grades of limestone for commercial markets.

Jan 1, 1970

By Chi-shing Wang

The late Professor P. B. Bucky of Columbia University introduced the principles and techniques of barodynamic experimentation in early 1931 by the application of centrifugal loading to achieve dynamic similitude between models and prototypes of mine structures.1 Later, he and his associates introduced the combined experimental technique of photo- elasticity and the centrifuge to determine the stress distribution in civil engineering structures and mine workings by the use of transparent bakelite models.2,3 The photostress technique, also known as the birefringent-coating method of photoelastic stress analysis, dates back to 1930, when Mesnager published its principles.4 Since then it has been widely applied to experimental stress analyses in many industries. A practical method of observing the dynamic behavior of opaque mine models, which are made of prototype materials, by means of a combination of the centrifugal and the photostress techniques is a new experimental approach under development at the Henry Krumb School of Mines, Columbia University.5 This paper summarizes the development of the barodynamic photostress technique and presents the information obtained from a recent series of experiments in the study of the behavior of rock beams loaded by their own weight. THEORETICAL BACKGROUND Theory of Pure Bending In the general theory of strength of materials, the flexure stress at any point in a beam of any type of cross section which has a longitudinal

Jan 1, 1968

By F. L. Holderreed

A choosy in what they would smelt. The furnace charge had to be coarse, and it had to be rich. They discarded fines in excess of about 1/10 the total weight. They wanted 10% copper content and fussed about anything with as low as 5%. They concentrated the copper content of the charge as much as they could by prior selection. They roasted off enough sulfur to further enrich the copper content of the succeeding fall of matte (a melt of cuprous and ferrous sulfides or Cu2S.FeS). Then they desulfurized the iron and fluxed it by carefully adding silica (quartz, not silicates) for a slag of lower density than the cuprous sulfide (Cu2S or white metal). After skimming off the slag, they further desulfurized the white metal by blowing the molten bath with compressed air. The result was blister copper. Yesterday Their techniques and furnaces? Some experimented with mechanically rabbled roasters, but their standard roasting practice was burning coarse sulfide ore in 250-ton heaps. These heaps, approximately 24 x 24 x 6 ft, were burned for about 75 days down to 6-10% sulfur. The turnaround time for a given roasting position was 100 days. Assuming the base was a hearth, the calculated rate of treatment was on the order of 0.004 tpd per sq ft.

Jan 1, 1971

By John E. Dowis

Ore distribution being what it is, many of today's mining companies are forced to develop foreign reserves to satisfy the demands of their customers. This necessity complicates the economic picture for a company, because management must look well be- yond grade and tonnage to determine the feasibility of developing a foreign orebody. Above all, the taxes on such a development must be assessed. The difference that taxes can make in mining profits will be illustrated here for three countries-Canada, Mexico and the United States. For purposes of comparison, identical orebodies will be assumed to occur in all three countries. Only the taxes on these properties will vary. Grade, tonnage, gross income, production costs and production rates will all be the same. The discussion will be limited to federal taxes, because state and provincial taxes are usually negligible by comparison. Assumptions relative to the orebody and the nature of the company undertaking the operation are as follows: (1) Copper is the only value to be recovered. (2) Sixty million tons of ore have been delineated. (3) Underground mining is required, and the production rate will be 3 million tpy. (4) The life of the property is 20 yr. (5) Operations in Mexico or Canada will be handled by a subsidiary of a U.S. parent company. (6) The subsidiary will offer stock.

Jan 1, 1970

By Wheeler P. Davey

When metals are subjected to mechanical working, such as rolling, one of the phenomena that take place is a movement of the crystals of the metal into a system or systems of orientation which bear an angular relation to the direction of working. In rolled metal the crystals may orient themselves with respect to the rolling plane or the rolling direction, or both. Direct evidence of the existence of preferred orientations in rolled metal has been obtained by numerous investigators from X-ray patterns of the rolled metal. Most of these workers used a monochromatic pinhole method. Where the degree of preference for a single orientation is high the monochromatic pinhole pattern may be interpreted by a geometrical calculation based on the angular relationships of the planes in the crystal and the diffraction arcs on the X-ray pattern. This process may be aided by the geometrical construction of the locus sphere (Lagenkugel), and reflection circles of Polanyi,l Polanyi and Weissenberg,2 and Mark and Weissenberg,3 and of the plane polar figures (flachenpolfigur) of Franz Wever.4 R. M. Bozorth5 solves X-ray patterns from metals having a single preferred orientation by means of a series of charts which when placed over the X-ray pattern give directly certain angular relationships, between the crystal planes and the surface of the specimen.

Jan 1, 1930

By J. L. Gillson

Historically, rock deposits and sand deposits of titanium minerals came into production about the same time, although there may be some argument as to what is meant by production. Beach de- posits of heavy minerals in India (Figs. 1-4) and Brazil (Figs. 5) were worked for monazite about the turn of century, but as there was then no market for titanium minerals, these were thrown away. The rock rutile deposits at Roseland, Va., Fig. 6, were worked to supply rutile for titanium chemicals and for coloring ceramics long before there was a titanium pigment business. The pigment industry started about the middle twenties, both in Europe and the U. S., and almost simultaneously the rock deposits at Ponte Vedra Beach near Jacksonville, Fla., were worked for titanium content. Since those days, production from both types of deposits has continued to grow at a rapid rate; many deposits of both types have been found, and reserves have grown to very large figures. In total tonnage of reserves, there is no doubt that the rock deposits are far ahead of the sand deposits; nevertheless there is a very large tonnage of commercial sands available. It is the quality of titanium mineral in the sand and the relatively lower costs of operating sand deposits that have kept them abreast, at least in annual tonnage produced, with the rock deposits.

Jan 4, 1959