Search Documents

By William P. Blake

The salt-beds at Salton, on the line of the Southern Pacific railway, in San Diego county, California, have been successfully worked for many years by the corporation known as the East Liverpool Salt Co., and the salt has been largely used upon the Pacific coast generally and in the interior. But the industry has lately been destroyed by the overflow from the Colorado river. The salt is dissolved, and the waves of the Salton sea now roll 50 ft. above the site of this once thriving and growing business. The salt-bed was evidently the residual accumulation from the waters of an ancient lake, which I have named Cahuilla, from the name by which a large part of the valley—the home of the Cahuilla tribe of Indians—is known. The deposit covered a comparatively small area in the lowest part of the valley, 280 R. or more below the sea-level. This depressed area is now generally known as the Colorado desert, but has a soil of wonderful fertility wherever water can be had on its surface. The deserted beaches, and the water-lines, only a few feet above tide-level, upon the rocks of the bordering mountains, as well as a great abundance of shells in the soil, all bear decisive testimony to the former occupation of the valley by water. The depression is topographically the northern end of the Gulf of California, from which it is now separated by the delta of the Colorado river, extending practically from the mouth of the Gila river across the valley to the coast mountains on the

Jan 1, 1908

By C Gunther

The purpose of this book is to present the practical side of economic geology concisely and in convenient form; established facts and the applications of accepted views are emphasized; theoretical discussions and questions of genesis are avoided. Coal, iron, and placer deposits are omitted; they are subjects of specialized study that are fully and concisely treated in other works. The reader is assumed to possess a knowledge of mineralogy, petrography, and elementary geology. The arrangement adopted is based on Kemp's theory of magmatic waters, on Lindgren's conclusions on hydrothermal and secondary alterations, and on the theories of secondary enrichment enunciated by Emmons and Weed. No general classification of ore deposits is attempted, nor is any attempt made to fill by hypothesis the wide gaps, nor to explain the apparent contradictions that rank economic geology among the most inexact of sciences. The present knowledge of the subject is too incomplete to warrant such broad generalizations. The demand for good properties generally exceeds the supply. While mines of the first rank will undoubtedly be discovered from time to time, it is probably true that a great proportion of deposits having outcrops of commercial grade or of evident promise have been recognized and explored. A review of mining conditions over long periods shows that the rich discoveries belong to pioneer days, and that as time goes on the more important developments are the result of lower working costs, improved metallurgical processes, and an increasing knowledge of economic geology. As engineers in search of developed mines no longer expect to find properties having positive ore of greater net value than the price asked, so those in search of prospects should not expect to

Jan 1, 1932

By N. A. Ziegler

THE present publication is a continuation of the work on gas analysis, described in a paper presented before the Institute of Metals Division a year ago.1 While that paper was largely descriptive in character, dealing with the various parts of the apparatus and method of operations, the present one gives numerical data obtained as a result of a series of experiments with iron-carbon alloys. The apparatus and the methods applied are essentially the same as previously described, changes being only in minor details. Attention should be called to the fact that in the present work we are dealing with the gaseous mixtures obtained as a result of vacuum melting of various ferrous alloys. It should be understood that when the terms "degasified sample" and "products of degasification" are used, they refer to the sample remaining after the vacuum fusion of the alloy and the gaseous products removed therefrom, respectively. The writer does not wish to create the impression that the metallic products of this process are absolutely free from any gaseous elements, nor that the gases obtained are present as such in the original sample. These two points are not yet definitely known and are subjects for future investigation. The point, however, which has been established beyond doubt, is that all the gases dealt with come from the metallic charge and are present either in the charge as such, or are produced as a result of chemical reactions going on within the charge.. The suggestion that the gases are due to the reactions between the metallic charge and the refractory materials has no valid basis.

Jan 1, 1929

By L. F. Reinartz

The furnace in which rimming steel is made has an important bearing on the quality of the steel produced. Furnace.—Particularly in the manufacture of low-carbon rimming steels, it is necessary to have an efficient, easily regulated furnace, because of the relatively high finishing temperature requirements. In recent years, the most important development in design of open-hearth furnaces has been the sealing and insulation of the greater part of the furnace to prevent air infiltration and loss of heat. Efficient, straight-line valves insure proper draft. Combustion controls guarantee correct gas-air ratios. Furnaces of all sizes ranging from 20 to 200 tons have been used successfully in the manufacture of rimming steels. Metal bath is varied from 20 to 40 in. in depth without appreciable variation in quality. Charging.—A normal open-hearth charge consists of pig iron (hot or cold), scrap of miscellaneous nature, and slag-making additions, such as limestone and burnt lime. Because of local conditions, some plants find it necessary to discard the use of pig iron and use some carbonaceolis substances with varying percentages of cast iron to replace the pig iron. It is questionable whether such practice will consistently produce the quality of rimming steel required for auto stampings and other severe drawing requirements. Pig Iron.—An open-hearth furnace under proper control should melt 150 tons of low-carbon rimming steel on about 35 to 38 per cent pig-iron charge basis. In some practices, best results are obtained when the total charge contains from 0.40 to' 0.50 per cent silicon. If reasonably low-

Jan 1, 1935

By A. L. Titchener, M. B. Bever

FROM their investigation of the martensitic transformation in Cu-Zn alloys, Greninger and Mooradian' concluded that there was no critical temperature at which martensite formation began in this system. Recent unpublished work by Gen-evray With two compositions of brass revealed the existence of a critical temperature, which is a function of composition and stress. In the work reported here the temperature range of the martensitic reaction was studied as a function of composition in high purity Cu-Zn alloys. The specimens were about 4 in. long with a diameter of 1/16 in.; their compositions are given in Table I. They were heated under vacuum for 5 min at 5" to 10°C below the temperature of incipient melting, and quenched into brine at about — 10°C. Specimens of alloys C, D, E and F were obtained with little or no precipitated a phase. Many attempts yielded only three usable specimens of alloy B, and even these contained appreciable amounts of a. All efforts failed to preserve metastable p in alloy A (containing 38.02 pct Zn and 0.002 pct each of Pb and Fe). The transformation was studied by measuring the electrical resistance during continuous cooling and heating of each specimen at similar rates. The cooling media were alcohol with dry ice from room temperature to — 78°C and a bath of petroleum ether and methyl cyclohexane (75:25), cooled by liquid nitrogen, from —78" to about —150°C. Readings were also taken at —195 °C in liquid nitrogen. Fig. 1 illustrates a typical experiment. The relative resistance is obtained by assuming the known

Jan 1, 1955

By L. F. Reinartz

The furnace in which rimming steel is made has an important bearing on the quality of the steel produced. Furnace.—Particularly in the manufacture of low-carbon rimming steels, it is necessary to have an efficient, easily regulated furnace, because of the relatively high finishing temperature requirements. In recent years, the most important development in design of open-hearth furnaces has been the sealing and insulation of the greater part of the furnace to prevent air infiltration and loss of heat. Efficient, straight-line valves insure proper draft. Combustion controls guarantee correct gas-air ratios. Furnaces of all sizes ranging from 20 to 200 tons have been used successfully in the manufacture of rimming steels. Metal bath is varied from 20 to 40 in. in depth without appreciable variation in quality. Charging.—A normal open-hearth charge consists of pig iron (hot or cold), scrap of miscellaneous nature, and slag-making additions, such as limestone and burnt lime. Because of local conditions, some plants find it necessary to discard the use of pig iron and use some carbonaceolis substances with varying percentages of cast iron to replace the pig iron. It is questionable whether such practice will consistently produce the quality of rimming steel required for auto stampings and other severe drawing requirements. Pig Iron.—An open-hearth furnace under proper control should melt 150 tons of low-carbon rimming steel on about 35 to 38 per cent pig-iron charge basis. In some practices, best results are obtained when the total charge contains from 0.40 to' 0.50 per cent silicon. If reasonably low-

Jan 1, 1935

By H. S. Gieser

THE flotation of oxidized silver, ores offers an interesting problem to the operating metallurgist, who has to treat this material. The advances made in the art of selective flotation by the use of newer collectors with accelerating and inhibiting reagents suggests that there should be something to help to decrease tailing losses. For many years there was no working hypothesis, so the subject was approached more or less in the dark, but with the publication of a paper by Taggart, Taylor and Ince1 giving results of flotation tests with many organic compounds and presenting a tentative theory, a better foundation has been laid and henceforth progress should be more rapid. Over a period of one and one-half years there was much experimentation with flotation of oxidized silver ores at El Tigre, Sonora, Mexico. The material coming to the mill was straight sulfide ore in a silicified rhyolite gangue, the ore minerals being sphalerite, galena, pyrite and tetrahedrite. This came largely from the lower levels of the mine. With the approaching exhaustion of these orebodies, attention was turned to oxidized ores left behind during higher prices of silver. Of late oxidized ore has been at times 25 per cent. of mill tonnage. Aerofloat 25, in considerable quantity, together with ethyl xanthate, has been used in the mill. The former raises large quantities of "insoluble" or gangue, which is difficult to reject when the density of the tailing pulp approaches 33 per cent. solids, as it did during periods of water scarcity. The mill tailing at times contained as much as 5 oz. of silver on a 32-oz. mill head.

Jan 1, 1931

By Vincent P. Gianella

THE most intense earthquake on the Pacific coast in the last several years, and probably the second most intense shock to occur in Nevada since it was settled, was felt in many Western States shortly after 10 p.m. on Dec. 20, 1932. Be- cause the rifted area contered about the northern end of Cedar Mountain it is referred to as the Cedar Mountain, Nevada, earthquake. An idea of the intensity of the shock may be gathered from the distance at which it was felt: in Wyoming, Utah, Idaho, Nevada, Washing- ton, Oregon, California and Arizona. It is the strongest quake centering in Nevada since the Pleasant Valley earthquake on Oct. 2, 1915. Despite the strength of the vibrations and the large area over which they were felt, relatively little damage was done. The extent of the damage consisted of a few old stone buildings demolished as shown in Fig. 1, much cracked and fallen plaster, many chimneys shaken down and considerable cracking of brick walls. There were no deaths and four people were but slightly injured. The small amount of damage was due, largely, to the scarcity of structures within the area of strong vibrations, but an important factor was the aridity of the region (see Fig. 2) and the shallowness of soil cover so that there was but little water-saturated loose material in which strong secondary vibrations could be formed. Had this earthquake occurred in a region of heavy precipitation and dense population the damage to property and loss of life would undoubtedly have been large, with consequently much more newspaper publicity.

Jan 1, 1933

Jan 1, 1880

Jan 1, 1949

Jan 1, 1894

Jan 1, 1970

Jan 1, 1955

Jan 1, 1955

Jan 1, 1934

Jan 1, 1970

Jan 1, 1932

Jan 1, 1899

By Lawrence V. Gagin

Jan 1, 1985

Jan 1, 1930