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By G. Morin, S. Amira, F. Chiesa, B. Duchesne

"The effect of heat treatment on the stress corrosion cracking (SCC) resistance of A206 aluminum alloy was studied using the breaking load test according to ASTM G139 standard. This method uses the residual strength measurement from tensile test specimens previously stressed axially while exposed to the 3.5% NaCl alternate immersion test according to ASTM G44 standard. The residual strength after exposure is used as a measure of SCC degradation. The performed heat treatments were conventional natural aging T4 and artificial over-aging T7 tempers in addition to artificial aging T6 temper added for purpose of comparison. These tests showed that A206-T4 has a good resistance to SCC at pre-loads up to 100 MPa while A206-T7 was prone to SCC for pre-loads of 0 and 50 MPa, and showed total loss of ductility for pre-load of 100 MPa. Both A206-T4 and A206-T7 pre-loaded at 150 MPa showed poor resistance to SCC. A206-T6 showed the worst susceptibility to SCC as it lost all mechanical resistance at the end of the alternate exposure to 3.5% NaCl solution, even without any applied pre-load. Metallographic analyses showed that the resistance of A206 alloy to SCC is mainly affected by the transition from pitting to intergranular corrosion attack. The initiation and the propagation of intergranular corrosion attack might be assisted by high stress concentrations in the pits, particularly for pre-loads higher than 100 MPa. The transition from pitting to intergranular corrosion can also be promoted by hydrogen evolution from growing pits, which supports crack propagation by hydrogen embrittlement.INTRODUCTIONA206 aluminum-copper casting alloy offers ones of the best mechanical properties among the aluminum foundry alloys. This alloy belongs to the 206 alloy family developed in 1970s as an alternative to the highly resistant and ductile but more expensive Ag containing 201 alloy (Tiryakioglu, 2009). A206 showed also good low cycle fatigue strength (Sigworth, 2002). These properties made A206 alloy a strong candidate for some vehicles lightweighting applications. In spite of its interesting properties cited above, A206 alloy was rarely used in critical applications due to its tendency for hot tearing and stress corrosion cracking (SCC). Studies of A206 hot tearing behavior showed that this tendency can be reduced by improving castability and by grain refinement (Sigworth, 2002). The optimisation of the casting design can also prevent the tendency toward hot tearing. The SCC of aluminum-copper alloys arises from their susceptibility to localised corrosion, especially in chloride containing media. The localised corrosion in Al-Cu alloys is caused mainly by their heterogeneous microstructure, where the presence of many phases leads to the formation of micro-galvanic coupling with the matrix. However, most of the studies aimed at investigate the SCC of Al-Cu alloys concerned the wrought ones, especially the AA2024 alloy tempered in the T3 (or derivative) condition and few studies concerned the 206 and cast alloys in general (Alexopoulos, 2009 and 2016; Campestrini, 2000; Vogt, 1998; Talamantes-Silva, 2008; Zhang, 2003). Jean et al. (Jean, 2009) studied the effect of heat treatment on SCC behavior of B206 alloy using alternate immersion technique and grain boundary attack method and did not find direct correlation between the two methods. Another study showed that aging of 206 alloy may make a casting susceptible to SCC (Sigworth, 2002). However, these studies did not provide detailed information about the mechanisms of SCC of 206 alloy, as well as the effect of the stress intensity. The present work investigates the effect heat treatments and the stress intensity on the morphology of the corrosion attack and the SCC behavior A206 aluminum alloy. This study uses the breaking load test according to ASTM G139. This test utilizes direct tensile specimens and was developed to give a more quantitative measure of the SCC performance of resistant aluminum"

Jan 1, 2016

By James A. Kiger

We at Colowyo would like to thank you for the opportunity to share with the Society of Mining Engineers of A.I.M.E. the progress of reclamation at Colowyo Coal Company's multiple seam open pit coal mine which is a general partnership of W.R. Grace and Co., and the Hanna Mining Co. First, a brief history of Colowyo Coal Company (Colowyo). The Colowyo operation is located approximately 28 miles southwest of Craig, Colorado, which is in the northwest corner of the state. The Colowyo operation produces coal from a Federal Coal Lease, a portion of which has experienced previous coal mining by underground methods. The underground coal mines were known as the Red Wing Mine and The Streeter Mine, and supplied coal to numerous locations in the Rocky Mountain region.

Jan 1, 1984

By P. J. Morgan, E. Wolmarans

The selection of the main mineralised zone (MMZ) concentrator milling circuit has followed a comprehensive route over the preceding 10 years. Many knowledgeable parties have contributed and assisted in developing the milling circuit according to the best available information. The final selection of the flow sheet was completed after DRA conducted a techno-economic study on four possible comminution circuits ranging from conventional crushing and ball milling to fully autogenous (AG) milling. The results from all the above mentioned work indicated that it is possible to treat the MMZ ore at the desired throughputs to the desired grind sizes in a fully autogenous grinding circuit. The flow sheet was designed to treat the main mineralised zone (MMZ) arising’s from both underground and open cast operations and incorporates a fully autogenous grinding (AG) circuit. Commissioning of the 375ktpm concentrator at Nkomati Nickel began in August 2009 with the first ore reporting to the mill on the 15th of September 2009.

Jan 1, 2012

By Howard Smith

AT the meeting of this Institute in February 1933, I presented a paper on potash development in southeastern New Mexico1, which contained a brief review of the Geological Survey's 20-year search for commercial sources of soluble potash minerals and of the events, that led to the discovery, exploration, and first development of the deposits in that state. As a more comprehensive review of the subject was published in December2, the present paper is intended only to discuss recent developments in the domestic potash industry, particularly in New Mexico. A summary of the findings of potash in the Permian Basin, by. G: R. Mansfield and W. B. Lang, geologists of the United States Geological Survey, is now in process of publication by the University of Texas and will be omitted from this paper. In New Mexico prospecting for potassium salts during the past two years has increased materially the known area .of commercial deposits; development has resulted in an increase from one to three in the number of shafts and the starting of a fourth; an increase of annual productive capacity to 1,000,000 tons of crude salts, or 250,000 tons of K20; and an increase in annual refining capacity to 140,000 tons of muriate of 62.5 per cent grade. Construction has been completed to increase still further the production of high-grade salts. In California the American Potash & Chemical Co., operating on Searles Lake brines, has increased its plant capacity from about 100,000 tons to 180,000 tons of muriate a year and is now producing soda ash and salt cake in addition to potash and borax. Potash production from cement-plant and industrial-alcohol wastes remains unimportant.

Jan 1, 1935

The potential of the developed multi-dimensional analysis system to assist interpretation from large data sets through derived digital mapping models is presented accompanied by preliminary results. The concept learning model is original and its application general. Applications exist in general science, engineering, earth resource management and economics. The developed system incorporates advances in machine learning, neural networks, object-oriented software engineering, knowledge representation and fuzzy logic. ' The specific application presented involves automatic earth resource modelling and assessment involving geological theories of mineral potential. The developed system functions as a new and powerful mineral exploration tool, To date the model has been trialled on an earth resource database and several published data sets. A more general potential application is knowledge discovery within databases. The specific theory that is tested in the experimental results is the nature of the cause-effect relationship between the hypothesised geological causes and the measured effects within a previously published test survey. Also integrated here are a neurophysiological cerebellar model of human learning, a new concept similarity measure for pattern recognition, modelled components to explain human concept formation through knowledge discovery and a means of permanent representation.The implementation is as a new artificial neural network architecture functioning as a hybrid expert system. Understanding of programmed concept learning is extended through the model. Also established is a basis for a new approach to multivariate data analysis. Spatial analysis for decision support is integrated over many dimensions, relationships, data types and data modes. Application of the developed methodology and system adds value to data bases. Discovered knowledge is represented as new generalisations, interpolations, classification hierarchies, aggregations and associations within a dynamic, maintainable and reusable integrated knowledge framework. New digital knowledge products and intelligent access follow. Permanently stored, maintainable, easily accessible and discovered knowledge improves decisions through extended hypothesis testing, spatial data analysis and inferencing, prediction, logical deductions and explanations.

Jan 1, 1995

By C. B. Manula

This report is volume 7 of an eleven-volume final report for a Grant completed by The Pennsylvania State University for the Bureau of Mines to develop a dynamic general purpose computer simulation model for underground coal mining. The simulator developed under the Grant has a wide range of possible applications in the design and evaluation of underground coal mining systems from the standpoints of health and safety, productivity, and mine environment. The Master Design Simulator consists of nine free-standing function-oriented subsystem models linked together into an integrated, comprehensive model of an entire mining system. The subsystems comprising the Master Design. Simulator include geology and reserves, methane generation, roof support, subsidence, production, rail haulage, cost, water generation," and ventilation. This volume of the final report describes the Rail Haulage subsystem of the Master Design Simulator. This subsystem can be used as a free standing model or can be linked to the Production subsystem to provide rail haulage capability. Complex rail haulage systems can be realistically simulated with this model. This report includes complete instructions for operating the subsystem as well as a program listing. In addition, a case study is included which illustrates the application of the subsystem when linked to the production subsystem.

Jan 1, 1974

By H. R. Gardner

The heat treatmmt of plutonium was studied using the Jominy end-quenching technique commonly used for determining the hardenability of steel. Plutonium specimens were end-guenched from temperatures in each of the ß, y, d, d') and E phases. One series of specimens with a low-iron content, 165 pprn Fe, and another gvoup with a high-iron content, 678 pprn Fe, were used in order to study the effect of a Pu-Pu,Fe eutectic network on the hardness and micro-structure. Hardness traverses indicated no significant variations in hardness with either cooling rate or quench temperature. Metallographic studies indicated major effects on microstructure. Grain size was found to vary markedly with quenching temperature and cooling rate. It was determined that the Pu-PueFe eutectic network could be modified extensively by heat treatment, including spheroi -dization in the y phase and 6 phase below 413°C. An unidentified spheroidal inclusion was observed to go into solution in the delta and higher temperature phases. 1 HE element plutonium is unique among metals in that it has six allotropic forms in the solid state.' These have been designated' as the a, ß, y, d, d', and phases. The respective phase transformations occur at approximate temperatures of 122", 210°, 319°, 450°, and 480°C with a melting point at 640°C. With this number of phase transformations it becomes pertinent to consider the effect of heat treatment and cooling rate in the various phases on the microstructure and hardness of plutonium. To determine; the effect of a wide range of cooling rates, the Jominy end-quenching technique was applied to cylindrical plutonium specimens. In addition, since the presence of iron in amounts greater than 500 pprn is common in plutonium and results in a network of the Pu-Pu6Fe eutectic, it was decided to study heat treatment effects on two bomb reduced plutonium buttons with different iron contents. A low iron button containing 165 ppm Fe and a high iron button containing 678 ppm Fe were selected for this comparison. EXPERIMENTAL PROCEDURE Experimental Material. The cylindrical bars for Jominy quenching were cast from button stock in vacuo in MgO coated graphite molds. Metal pouring temperature was approximately 950°C and the molds were preheated to 300°C. The castings were machined to 0.5 in. diam. by 2.5 in. long cylinders. Chemical analysis and density data for the two groups of Jominy specimens containing different iron contents are presented in Table I. Except for iron, heats 19-12-1 and 20-2-1 are comparable within the limits of analytical accuracy. Representative specimens from the low-iron and high-iron bars were taken for metallographic examination. The low iron specimen was found to have extensive microcracking, Fig. 1. In addition, numerous unidentified spheroidal inclusions were present, Fig. 17. The average grain size of the low-iron plutonium is 0.068 mm, Fig. 4. In the high-iron plutonium, a Pu-Pu6Fe eutectic network is prominent, Fig. 7. The average size of the network is 0.100 mm. Unidentified spheroidal inclusions were also common in the high-iron plutonium. The average grain size of the high-iron plutonium is 0.036 mm. Experimental Technique. A Jominy end-quenching fixture was fabricated for glove box use. A 2.5 in. water height was used with an orifice of 0.250 in. ID. The orifice to specimen distance was maintained at 0.5 in. Annealing temperatures of 160°, 265°, 400°, 465°, and 535°c were chosen for the study of the effect of quenching from ß, y, d, d', and e phases on microstructure and hardness. During quenching, cooling curves were obtained from the Jominy specimens at distances from the quenched end of 1/16, 1/8, 3/8, 3/4, 1-1/4, and 2 in. Cooling rate calculations were made from the cooling curves for temperature intervals of 100° to 110° 160" to 170°, 330" to 340°, 420° to 430°, and 490° to 500°c. These temperature intervals were chosen

Jan 1, 1962

By L. W. Holm

Laboratory flooding experiments on linear flow systerns indicated that high oil displacement, approaching that obtained from completely miscible solvents, can be attained by injecting a small slug of carbon dioxide into a reservoir and driving it with plain or carbonated water. Data are presented in this paper which show the results of laboratory work designed to evaluate this oil recovery process, particularly at reservoir temperatures above 100°F and in the pressure range of 600 to 2,600 psi. Under these conditions CO2 exists as a dense single-phase fluid. It was found that a bank, rich in light hydrocarbons, was formed at the leading edge of the CO? slug during floods on long cores. Formation of this bank is probably due to a selective extraction by the C02 and, it is believed, partially accounts for the attractively high oil recoveries. In crddition to the efficient displacernerlt of oil from the pores of the rock by this process, the favorable rnobility ratio related to a C0 2-water flood also contributes to high oil recovery. A further advantage of this process is noted on limestone and dolomite rock, in that the CO1 reacts with the porous medium increasing its permeability. Flooding experiments were conducted on sandstone and vugular dolomite models. The results of this experimental work show the effect on oil recovery of type of porous medium, pore geometry, flooding length, and flooding pressure. The porosity of the cores and rilodels varied from 16 to 21 per cent and their pern~eabilities ranged from 100 to 200 md. A reconstituted West Texas reservoir oil, a West Texas stock tank oil, an East Texas stock tank oil and Soltrol were used to represent reservoir oils in this study. Oil recoveries ranging from 60 to 80 per cent of the original oil in place in these cores were obtained by CO2,-carbonated water floods at pressures between 900 and 1,800 psi, compared with conventional solution gas drive and water-flood recoveries of 30 to 45 per cent on the same cores. Oil recoveries greater than 80 per cent resulted frorn f1oods at pressures above about 1.800 psi. There high recoveries were noted from both the sandstone and the irregular Porosity carbonate cores. In all floods, additional oil was recovered by a solutiorr gas drive resulting from blowdown following the flood. Oil recoveries of 6 to 15 per cent of the original oil in place were obtained during this blowdown period. This additional recovery was found to be a function of oil remaining after the flood, decreasing with decreasing oil saturation. It was also noted that highest oil recoveries by blowdown were obtained when carborlated water rather than plain water followed the CO, slug. INTRODUCTION Miscible phase or solvent flooding processes, which are designed to increase oil recovery -from petroleum reservoirs, involve the injection of small quantities of a petroleum solvent into the reservoir, followed by an inexpensive scavenging fluid which is miscible with the solvent. Essentially complete displacement of oil from the pores of reservoir rock has been obtained by this technique. CO,, although not completely miscible with most reservoir oils at moderate pressures, is highly soluble in these oils at pressures above about 700 psi; there is appreciable swelling and reduction in the viscosity of oil when CO, is dissolved in it. Therefore, CO, could be expected to perform similarly to other oil solvents as a displacing agent. CO, is also highly soluble in water at elevated pressures, so water should be a satisfactory material to drive a slug of CO, through an oil-bearing reservoir. A favorable mobility ratio would be obtained through the reduction in viscosity of the oil and the use of water as a final displacing agent. A number of investigations of the use of CO, to improve oil recovery have been reported in the literature.2,3,4,5,6 These studies, however, have been conducted on uniform porosity sandstone at relatively low temperatures and pressures. The behavior of CO1 as a flooding agent at temperatures above its critical temperature could not be predicted adequately from these studies, particularly for the case of non-homogeneous rock. The purpose of this work was to evaluate the oil recovery efficiency of a process involving the injection of a CO2 slug followed by carbonated water, at reservoir temperatures above 100°F and in the pressure range of 600 to 2,600 psi, and to compare this process with conventional water flooding. The investigations were primarily designed to provide information on the efficiency of the process in irregular porosity carbonate rock. The effects of flooding path length, the presence of free gas, the type of oil to be recovered, and the amount of solvent required were also determined. The essential results of static phase behavior studies and experimen-

The library of the above-named Societies is open from 9 A. M. to 10 P. M. except on holidays. It contains about 70,000 volumes and 90,000 pamphlets, including sets of technical periodicals and publications of scientific and technical societies. Members of the Institute, with few exceptions, are forced to spend a portion of their time in localities isolated from sources of information. To these the Library, through its Library Service Bureau, can render valuable service through correspondence; letters requesting information will receive especial attention. The Library is prepared to furnish references and photographic copies of articles on mining and metallurgical subjects; to determine the existence of mining maps, and to furnish general information on the geology and mineral resources of all countries. All communications should he made as definite as possible so that the information received may be what is desired and not include collateral matter which may not be of interest. The time spent in searching for such collateral matter will be saved, and the information will be sent more promptly and in more usable shape.

Jan 11, 1918

By Henry S. Drinker

THE Musconetcong tunnel is situated in New Jersey, near the line of the Central Railroad of New Jersey, about twelve miles from Easton, on the Easton and Amboy Railroad, the latter being the extension of the Lehigh Valley Railroad to tide-water. Up to the present time, the terminus of the Lehigh Valley Railroad has been at Phillipsburg, N. J., opposite Easton, passengers connecting there with New York by the Morris and Essex (D. L. and W.) and New Jersey Central lines; freight and coal being forwarded by the Morris and Essex to tide-water at Hoboken, and by the Central Railroad to Elizabethport and Port Johnson ; also, by the Belvidere and Delaware connections through Trenton to South Amboy.

Jan 1, 1875

By F. V. Lenel

INTRODUCTION Two years ago in Chicago a seminar was held on the theory of sintering of pure metal powders As an introduction to this seminar Dr Rhines1 gave an excellent survey of the literature on this subject His method of presentation was to summarize the experimental observations on sintering and from them to develop a composite theory of sintering in which he combined all the important contributions to the theory into one organic whole In contrast to the mechanism of sintering of pure metal powders, which, of course, always takes place in the solid phase, sintering in the presence of a liquid phase, cannot be treated as one unified mechanism, such as the sintering mechanism of pure metals The reason is that there are really several mechanisms depending upon the type of alloy system which is sintered and the field of its constitutional diagram in which the sintering takes place Two mechanisms have been investigated and will be reviewed in this paper In the first mechanism the liquid is present during the entire time while the compacts are at the sintering temperature In other words they are sintered between the liquidus and the solidus of the alloy System and are heterogeneous during the entire sintering cycle The second mechanism applies to alloys in which the liquid phase is formed during the sintering process, but disappears before the sintering process is completed through diffusion and formation of a solid solution These alloys are therefore homogeneous at the end of the sintering cycle This second mechanism is more complicated because of the two stages of sintering, the liquid and the solid, as they may be called It is therefore not surprising that the few detailed investigations of sintering in the presence of a liquid phase have been concerned with heterogeneous sintered alloys, namely the tungsten-nickel-copper alloys, which is the so-called "heavy alloy," and the cemented carbides The mechanism of sintering of these systems is characterized by the fact that theoretical or near theoretical density is attained during sintering, while simultaneously a distinct grain growth takes place through solution of the smallest grains of the solid phase in the liquid phase and reprecipitation on the larger grains In the first part of the survey this sintering mechanism which is called for short the heavy alloy mechanism is treated in detail In the second part of the survey experimental observations for the sintering of homogeneous sintered alloys where the liquid phase disappears before the completion of sintering are discussed Much less systematic work has been done on these alloys to which the commercially important porous bronzes and the iron-nickel-aluminum permanent magnet alloys belong Emphasis will be laid throughout this survey upon the microstructural and density changes during sintering because the sintering mechanism can usually be described directly by these changes Other

Jan 1, 1948

By Paul T. Allsman

THIS CHAPTER reviews the highlights of developments in mining technology during 1956 and presents a special report on the design of mine openings in stable ground. This special report is presented each year in an endeavor to stimulate use of the scientific approach to the solution of problems related to mining technology. Assuming that the literature on mining technology reflects trends in mining, it appears that two areas of activity were given most attention in 1956. One was research on mining technology,4 and the other was improvement of transportation, particularly trackless transportation, both at surface and underground mines.

Jan 1, 1958

By Thornton D, Esterle J, La Rosa D

Control of blast fragmentation has a significant impact on coal mine profitability. Two approaches for the characterisation of coal blastability, particularly in terms of fines, are presented. Both approaches were implemented for the predictio

Jan 1, 1998

By Frederick M. Becket

DoctoR Albert Sauveur, distinguished scientist and Honorary Member of this Institute, predicted in the first Howe Memorial Lecture that the privilege of delivering' this annual address would be considered a highly significant honor. The intervening years have well borne out Sauveur's prophecy. I wish to assure the American Institute of Mining and Metallurgical Engineers that I also deeply appreciate this honor, recognizing at the same time the present and even more the future responsibilities with which it is accompanicd. Several of the previous lecturers had the good fortune to attend the classes of Professor Howc and to work in his laboratories. I was similarly favored, although in my instance and to my great regret the period was all too short. However, Howe's book, published in 1903, "Iron, Steel and Other Alloys," afforded me abundant opportunity to continue these studies. How well I remember the inspiration I derived from this famous book by Howe, the metallurgical master, pioneer, and educator! Remembering that Professor Howe contributed numerous papers to The Metallographist, a magazine supported from a technical point of view by the world's pioneers in metallography, I was curious a few days ago to learn the nature of Howe's early contributions to this magazine. The first paper by Howe in the first year of The Metallographist (1898) dealt with the allotropic theory; the second also treated of allotropy, and I quote the first sentence of that paper: The allotropic theory of the hardening of steel may, like so many other important theories, have to be accepted or rejected not on direct proof or disproof, but on the accumulation of circumstantial evidence for or against it. Howe's ability to stimulate others by his deep understanding and clarity of expression was truly remarkable; but just as striking was his intuitive judgment concerning the implications of metallurgical data in the arts and scienees. It therefore seems fitting that this lecture comprise a broad treatment of the subject chosen, rather than a closely documented thesis on any one phase of the problem; that in it attention be focused

Jan 1, 1938

By Frederick M. Becket

DoctoR Albert Sauveur, distinguished scientist and Honorary Member of this Institute, predicted in the first Howe Memorial Lecture that the privilege of delivering' this annual address would be considered a highly significant honor. The intervening years have well borne out Sauveur's prophecy. I wish to assure the American Institute of Mining and Metallurgical Engineers that I also deeply appreciate this honor, recognizing at the same time the present and even more the future responsibilities with which it is accompanicd. Several of the previous lecturers had the good fortune to attend the classes of Professor Howc and to work in his laboratories. I was similarly favored, although in my instance and to my great regret the period was all too short. However, Howe's book, published in 1903, "Iron, Steel and Other Alloys," afforded me abundant opportunity to continue these studies. How well I remember the inspiration I derived from this famous book by Howe, the metallurgical master, pioneer, and educator! Remembering that Professor Howe contributed numerous papers to The Metallographist, a magazine supported from a technical point of view by the world's pioneers in metallography, I was curious a few days ago to learn the nature of Howe's early contributions to this magazine. The first paper by Howe in the first year of The Metallographist (1898) dealt with the allotropic theory; the second also treated of allotropy, and I quote the first sentence of that paper: The allotropic theory of the hardening of steel may, like so many other important theories, have to be accepted or rejected not on direct proof or disproof, but on the accumulation of circumstantial evidence for or against it. Howe's ability to stimulate others by his deep understanding and clarity of expression was truly remarkable; but just as striking was his intuitive judgment concerning the implications of metallurgical data in the arts and scienees. It therefore seems fitting that this lecture comprise a broad treatment of the subject chosen, rather than a closely documented thesis on any one phase of the problem; that in it attention be focused

Jan 1, 1938

By Frank Schrader

INTRODUCTION THE present sketch is submitted by request in the hope that it may serve as a basis for geologic discussion of the mining camps in Mohave County, which is experiencing a marked revival of activities. The region, commonly known as the Mohave district and Kingman district, lies in western Arizona in the southern part of Mohave County, bordering California and Nevada on the west (Fig. 1). Kingman, the principal-town; is situated near the center of the area. on. the Atchison, Topeka & Sante Fe Transcontinental Railway. This region is composed of naked desert ranges of mountains and broad detritus-filled valleys, the southern extension of the characteristic topography of the Great Basin. In altitude it varies from 500 ft. in the southwest to 8,300 ft. on Hualpai Peak southeast of Kingman. The mountains trend north-northwest. They rise about 3,000 ft. above the valleys, are generally rugged and were formed mainly by erosion. They are composed in the main of a, complex of pre-Cambrian granitoid rocks which underlies the area as a whole. Like the valleys, they average about 10 miles in width. Beginning on the east, they are the Grand Wash Cliffs, the Cerbat Range, the Black Mountains or River Range, and the Eldorado Range. The upper or dominantly cliff half of the Grand Wash Cliffs, marking the edge of the Colorado Plateau, is composed of nearly horizontal sedimentary Paleozoic strata of the Grand Canyon section, and the lower half of the underlying pre-Cambrian complex. The Cerbat Mountains situated in the central part of the area, and the Black Mountains situated between Detrital-Sacramento Valley on the east and Mohave Valley, the great trough of the Colorado River, on the west, are locally flanked or overlain by Tertiary volcanics (Fig. 2). The latter consist of five groups of mountains of which the most important is the Black Mesa group on the south. The Eldorado Range, rising from the great trough of the Colorado on the west and containing Searchlight, Eldorado Canyon, and other camps, is topographically and geologically similar to the Black Mountains.

Jan 10, 1916

By P. W. George

This paper presents geological data regarding deposits of over 7,500,000 tons of fine-grained sulphide ore in barite gangue. A series of pyroclastics and arkoses was intruded by sills of quartz porphyry in connection with batholithic intrusions of granite 3 miles from Buchans. Gentle folding, with fracturing and shearing of tuff beds and intruded quartz porphyry, accompanied and followed the intrusion of granite and porphyry. The sulphide-barite mineralization is localized primarily in fractured and sheared tuff beds, but also in the sheared quartz porphyry. Two structures have proved particularly favorable for mineralization—one, the center of an anticline; the other, a series of weak, incompetent tuff beds intruded by thin sills of quartz porphyry and located between strong beds of arkose. During the folding the weak tuff with intruded quartz porphyry was intensely sheared and contorted and subsequently mineralized by sulphides and barite. Introduction Buchans is 5 miles north of Red Indian Lake, in Central Newfoundland, at an elevation of 900 ft. above sea level and 400 ft. above Red Indian Lake, and is reached by a 37-mile private railway from Miller-town Junction. The first ore body found at Buchans was discovered some 30 years ago in the bed of Buchans River, by Matty Mitchell, an Indian woodsman employed by the Anglo-Newfoundland Development Co. Ltd. In the years following the discovery the ore was developed by shaft-sinking and drifting, with results indicating a lenticular ore body in a shear zone, containing about 100,000 tons of extremely fine-grained sulphide ore in barite gangue averaging about 0.05 oz. Au, 4 oz. Ag, 1.5 per cent Cu, 10 per cent Pb, 18 per cent Zn. Because a profitable metallurgical treatment for the ore was not found, the mine was closed down in 1911. In 1915, Mr. H. A. Guess, Vice President of the American Smelting & Refining Co., learned of the Buchans River ore body, and after metallurgical tests had been carried on from time to time in his company's testing plant a satisfactory separation of the sulphides by selective flotation was finally effected in 1925. Prospecting for additional ore bodies was begun in 1926, utilizing geophysical methods under the direction of Hans Lund-

Jan 1, 1937

By Osamu Takeda

A decomposition process for PCBs by using basic molten salts as a reaction field was investigated in order to establish a safe, simple and highly efficient decomposition process for polychlorobiphenyls (PCBs). PCB containing chlorine (e.g. 2, 2?, 4, 4?-tetrachlorobiphenyl) dissolved in n-nonane solution was supplied into basic molten salts (NaOH-Na2CO3 or KOH-K2CO3) maintained at 500-700 ?C together with the carrier gas (N2-21% O2) through an injection tube. The injected PCBs in a bubble are decomposed by the reaction with the molten salts and oxygen during rise in the molten salts. The decomposition efficiency of PCBs increased with increasing temperature and was achieved to be higher than 99.995% in a certain condition. From a series of systematic study, the effectiveness of the decomposition process for PCBs by using molten salts was demonstrated.

Jan 1, 2008

By Eugene T. Sheridan

The Bureau of Mines annually canvasses the peat producers in the United States and publishes economic data on the industry, based upon reports from producers. This publication lists all producers that reported commercial production to the Bureau for 1959. The companies named herein represent virtually all commercial producers of peat. A few companies, however, may not have been canvassed or failed to respond, as tine survey is voluntary For producers, arid the industry has many small operations that operate intermittently. No consideration was given to the quantities of peat produced and output of the various companies listed ranged from less than 100 tons to more than 50,000 tons, Peat is included in the Bureau's annual surveys of the mineral industries because, technically, peat is a fuel. Although none is used for fuel in the United States, peat is a potential source of energy and one of our large mineral resources. The domestic peat industry produces peat chiefly for use as a soil amendment. The industry has expanded rapidly during the past decade with active operations increasing from 45 in 1947-49 4/ to 105 in 1959. Output during this period has increased 218 percent, rising from 131,782 net tons to 419,460 net tons.

Jan 1, 1960

By L. E. Cardwell

This Bureau of Mines publication contains routine analyses and related source data for 495 natural gas samples from 21 States and three foreign countries. Of this total, 376 samples were collected during calendar year 1968. The remaining 119 analyses are of samples collected during previous years, but releases granting permission to publish the results Here not received until 1968. All samples were collected as a part of a continuous survey of the free world for occurrences of helium in natural gas. This survey has been conducted in the United States by the Bureau of Mines since 1917 and in late 1965 was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus which are described in Bureau of Mines Bulletins 4863 and 576.4 Ten previous publications have presented results of 8,165 gas analyses made by the Bureau of Hines Helium Activity prior to 1968. The first three, Bulletins 486, 576,6 and 617,7 contain analyses and related source data on

Jan 1, 1970