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By J. Visman

FOR more than 25 years evaluations of coal cleaning units have appeared in many publications, and during this time considerable progress has been made in developing the theory and techniques of calculating washery results. A variety of characteristics have been defined over the years, many receiving general recognition during the first post-war Coal Preparation Conference in Paris in 1950. Coal preparation has become a science, and the approach to preparation problems is being revolutionized. Formerly, for example, if a coal operator wanted to know the performance of a given cleaning unit for a particular grade of his run-of-mine, he either shipped a carload to the manufacturer for a test run or relied on a report of a test carried out on a coal similar to the one he intended to clean. In modern practice the expensive, time-consuming test work generally can be avoided if the washability curves of the coal in question and the error curve of the cleaner are known. Normally a guarantee can be given on the strength of this information. General acceptance of modern standards has thus reduced the need for pilot-scale models of existing types of coal cleaners. Needless to say, the method requires exhaustive and accurate information on the cleaning unit and on all the additional circumstances affecting its results, in- formation that ultimately can be secured only from actual tests made in the laboratory or in the washery.

Jan 10, 1954

By L. H. Wolfe, J. O. Thieme

The tensile and shear strengths of frozen soil and the compressive strengths of ice and frozen soil were measured These tests showed that the strength of ice and of frozen soil increased as the temperature was decreased. A method is presented for the measurement of thermal conductivity and specific heat of earth and ice. Using the parameters thermal conductivity, specific heat and density, the thermal diffusivity was calculated. Results of thermal property tests establish water as the major variable contributing to thermal property values. INTRODUCTION During the last few years, a considerable interest has developed in underground storage of cryogenic liquids such as liquid natural gas. Because of its economy and safety, underground storage is being used. Before underground caverns could be seriously considered, however, the strength and thermal characteristics of the soil had to be obtained. Methods are presented herein for measuring tensile, compressive and shear strengths, specific heats and thermal conductivities. The tests were performed on two soils at temperatures from ambient to -195C. Because it is difficult to find data in the literature that pertain to a particular soil, ice was used to evaluate some of the experimental procedures. Some of our ice data are compared to the published values. PHYSICAI, PROPERTIES SOIL SELECTION AND SAMPLE PREPARATIONS The physical and thermal tests were performed on recompacted samples of two typical soils that might be encountered in underground caverns: a gray, fire clay that had been pulverized and mixed with water into a pliable mud; and a brown, sandy silt that was dug from a dry river bank and subsequent1y mixed with tap water. The moisture content of the test specimens was 17 to 22 per cent (based on the wet weight of the soil). This amount of water nearly saturated the silt, but the clay was well below the saturation point. The soils are partially described by the sieve analyses (Fig. 1) which show the particle size distribution of the coarser than 44 micron portion of the soils. The curves also show that approximately 75 per cent of the clay and 20 per cent of the silt are finer than 44 microns. The particle size seems to affect some of the physical properties, and the finer than 44 micron portion is important in the thermal conductivity test. Physical specimens were cut with a bandsaw from frozen blocks of the soil. The specimens were then sanded and kept frozen until after they were tested. They were stored at the approximate test temperature for several hours. Then, to equilibrate the samples to the test temperature, they were stored at the temperature at least an hour before they were tested. TEST EQUIPMENT An Instron, which is a constant speed gear-driven instrument, applied force to the samples and drew stress-strain plots of the test. All of the samples were strained at 0.02 in./min. All of the physical tests were conducted in a temperature cabinet that controlled the temperature to 1C. TENSILE STRENGTH Briquette or "dog-bone" shaped tensile specimens were pulled with suitably shaped jaws. This shape of specimen, which is usually used for tensile tests of concrete, is satisfactory for testing frozen soils except that the samples tend to

Jan 1, 1965

By Howard A. Meyerhoff, J. Earl Frazier

It is not known when silica sand was first noticed along the north coast of Puerto Rico, but the first mention of its occurrence was made in 1922, by N. L. Britton,1 who described its presence in isolated patches extending from Loiza westward beyond Manati. Further observations were made in 1925 and 1926 by Meyerhoff,2 who extended the known occurrences still farther westward to the low hill belt in the Quebradillas limestone immediately south of Hatillo. The extraordinary purity of the sands, which in most localities exhibit no contamination from the non-siliceous materials surrounding them, was quickly appreciated, and the feasibility of utilizing them for the manufacture of glass was investigated, initially by the Committee on Mineral Resources3 and later (1936) by the Puerto Rico Recon-structionAdministration and by H. C. Ray, mining engineer of the Insular Bureau of Mines. In 1934 samples submitted to the Hazel Atlas Glass Co., of Washington, Pennsylvania, were reported to have the composition as shown in the table on column two. Appreciation of the quality of the sand prompted geological and quantitative studies of the deposits, as well as cornmercial investigations to determine the feasibility of utilizing it locally or on the mainland for the manufacture of glass containers. Distribution of the Sands The quartz sands consistently lie within the outcrop area of the Quebradillas limestone, the youngest of the Miocene formations in the Tertiary coastal plain that fringes the northern coast of the Island. Many of the deposits are closely associated with limestone outcrops, but some appear to be embedded in lagoonal sediments at some distance from rock exposures, and at least one deposit, near Dorado, has been reworked by waves and littoral currents. With this single known exception, the deposits consist of irregular, patternless patches of white sand, which have sharply defined contacts with the surrounding material. Although patches of sand are present in a 90-km. belt that is not more than 5 km. wide, extending from Loiza to Hatillo, they attain maximum size, purity and number in the north central coastal area between Dorado and Barceloneta. Fifty separate deposits have been mapped in Lago Tortuguero and to the south of it, some as small as 50 ft. in diameter but

Jan 1, 1948

By J. Earl Frazier, Howard A. Meyerhoff

It is not known when silica sand was first noticed along the north coast of Puerto Rico, but the first mention of its occurrence was made in 1922, by N. L. Britton,1 who described its presence in isolated patches extending from Loiza westward beyond Manati. Further observations were made in 1925 and 1926 by Meyerhoff,2 who extended the known occurrences still farther westward to the low hill belt in the Quebradillas limestone immediately south of Hatillo. The extraordinary purity of the sands, which in most localities exhibit no contamination from the non-siliceous materials surrounding them, was quickly appreciated, and the feasibility of utilizing them for the manufacture of glass was investigated, initially by the Committee on Mineral Resources3 and later (1936) by the Puerto Rico Recon-structionAdministration and by H. C. Ray, mining engineer of the Insular Bureau of Mines. In 1934 samples submitted to the Hazel Atlas Glass Co., of Washington, Pennsylvania, were reported to have the composition as shown in the table on column two. Appreciation of the quality of the sand prompted geological and quantitative studies of the deposits, as well as cornmercial investigations to determine the feasibility of utilizing it locally or on the mainland for the manufacture of glass containers. Distribution of the Sands The quartz sands consistently lie within the outcrop area of the Quebradillas limestone, the youngest of the Miocene formations in the Tertiary coastal plain that fringes the northern coast of the Island. Many of the deposits are closely associated with limestone outcrops, but some appear to be embedded in lagoonal sediments at some distance from rock exposures, and at least one deposit, near Dorado, has been reworked by waves and littoral currents. With this single known exception, the deposits consist of irregular, patternless patches of white sand, which have sharply defined contacts with the surrounding material. Although patches of sand are present in a 90-km. belt that is not more than 5 km. wide, extending from Loiza to Hatillo, they attain maximum size, purity and number in the north central coastal area between Dorado and Barceloneta. Fifty separate deposits have been mapped in Lago Tortuguero and to the south of it, some as small as 50 ft. in diameter but

Jan 1, 1948

The meeting of the Institute at St. Louis brought together many members of the Women's Auxiliary, and Mrs. Philip N. Moore, who was nominated as the Director for the St. Louis Section, took the occasion formally to inaugurate the organization in that district. A meeting was held at the Planters Hotel, anti after discussion as to, the aims and objects of the. Auxiliary, officers were nominated for the' Section; the meeting then adjourned for two days, to he resumed in Joplin.. Here a very successful meeting was held, at which the Vice-Chairman, Secretary, and Treasurer were elected. A great deal of interest was arouse under the able directorship of Mrs. Moore the St. Louis Section is likely to become a large and active organization. The president of the Women's Auxiliary, in opening the meetings, told the ladies present of the inauguration of-the-Society in February, 1917, and of the work which had been accomplished up to date. She told how the Society devotes itself to patriotic and humanitarian work along lines acceptable and interesting to the Mining Engineer, standing always alongside and behind the men of the profession. The Central Welfare Committee of the organization has three Sub-Committees: Foreign Relief, Emergency, and Americanization, and under one or other of those heads most of the work of the' Society has been done. Mr. Hoover was responsible for the inception of the Foreign Relief Committee, as its first work was the collection of funds for the supplementary meals for the Belgian Children. Under the energetic administration of Mrs. H. Knox, this sub-committee raised $12,100 in the period between the February meeting and the Declaration of war by the United States, when our government took over the entire duty of feeding starving Belgium. The organization of the Belgian Relief Committee, as it was styled, still remains, but the members are now asked to take up the question of relief in France. The President, Mrs. S. J. Jennings suggested at the St. Louis meetings that one way of working for the foreign relief alight be that all the members of the Auxiliary should, during the period of the war, forego all giving' and receiving of Christmas presents, except those they have been accustomed to give to the poor or in charity, and those they would give to the men in the services of the United States; that the money usually spent on the Christmas gifts should be put into a fund to be sent abroad for the fatherless children of France, as a gift from the families of the Institute. A good deal of discussion followed this proposal, as some of the ladies felt that children should have their Christmas gifts as usual. The Director of the Section emphasized the truth that the Christmas spirit was the .spirit of giving and sacrifice, and that no sacri-

Jan 1, 1918

By C. Coles, J. A. I. Young, W. A. Wyeth, D. A. Fenton, G. W. Herzog

The reliability of large diameter, high horsepower ball mills is paramount when large production and minimum downtime is required. The 518 x 1706 mm (17 x 56 ft) double compartment ball mill at St. Lawrence Cement Co. has the fist gearless drive built in North America and has the world's largest hydrodynamic bearings currently built and running. The machine has seen three years operation and has met its specifications. The mill wm designed by Aerofall Mills Ltd. and the gearless drive built and designed by the Canadian General Electric Co. The paper discusses the operation of the machine from the mechanical, electrical and process aspects.

Jan 1, 1980

By W. O. Philbrook. K M Goldman, M. M. Helzel

RADIOACTIVE calcium has been used to learn whether calcium can be detected in iron saturated with carbon after it has been melted under CaO- A12O3- SiO2 slags similar to those used in the iron blast furnace. It was hoped that the radioactive tracer technique might make possible a general study of steelmaking reactions in which calcium or calcium oxide are involved. No calcium could be found in the metal under conditions which were favorable for the reduction of calcium, and it has been concluded that the calcium content of the iron was less than 6 x 10 - pct. Some of the problems encountered have been instructive with regard to pitfalls and limitations of tracer methods. Calcium oxide occurs in almost all iron- and steelmaking slags, and it is essential to the success of all commercial basic steelmaking processes. Calcium alloys are sometimes used in the deoxidation of steel and for the innoculation of gray iron. The element calcium is therefore almost as ubiquitous in the steel industry as are carbon and oxygen, but calcium has been thought to be completely immiscible with iron in both the liquid and the solid states.' It does not seem entirely unreasonable to Suppose, however, that some low concentration of calcium might exist in liquid iron under a basic slag with other conditions being favorable, just as silicon and other elements can be introduced into iron by reduction of their oxides from slags under appropriate circumstances. The radioactive tracer technique offered a more sensitive method than chemical analysis of testing this supposition. The reasons for interest in this investigation were strong enough to justify a recognized risk of failure. On the theoretical side, information on the distribution of calcium between liquid iron and a slag and the rate at which the equilibrium distribution is approached would contribute strongly to the general theory of slag-metal interface reactions. Furthermore, any evidence on the presence of calcium in liquid iron might provide a vital clue to the mechanism of the desulphurization of iron by slags. All of the reactions which have been proposed to explain desulphurization postulate that the sulphur ultimately becomes fixed in the slag as calcium sulphide, but the mechanism by which sulphur

Jan 1, 1951

By L. L. Foley, C. V. Millikan

The discovery of Bromide production in the Fitts field, shallow production in Jackson County of Southwestern Oklahoma, abundant production in the Edmond field, and discovery of many small pools in all parts of the state, were the events that made petroleum history in Oklahoma in 1934. Wildcatting was much more active, as evidenced by a number of new discoveries. There was no important development in the older fields. The rapid decline of the potential of the Oklahoma City field was an important feature of the history of the year. The accompanying tabulation of oil fields (Table 1) is not complete. Many of the early records of operators and pipe line companies are lost and it will be impossible to work up complete statistics for a number of the older fields. The table includes most of the important fields of the state and includes fields of a number of different types. It is hoped that a great many additional fields may be worked up for next year's report. Fitts Pool.—The Fitts pool, in Pontotoc County, was discovered in 1933. Before the middle of 1934, the Pennsylvanian sands yielded -some oil at depths ranging from 1400 to 2800 ft. The Hunton series (Siluro-Devonian) produced most of the oil with considerable gas. In July, 1934, a well in sec. 25, T.2N., R.6E. was completed in the Bromide (Ordovician " Wilcox ") with an initial production of about 300 bbl. a day. Less than a month later a second Bromide sand well was completed in sec. 30, T.2N., R.7E., which made over 200 bbl. an hour. This started an active drilling campaign, which was accelerated when some of the major companies paid good prices for adjacent acreage. At the end of the year, 23 wells had been completed and the rate of development was increasing rapidly. It is a major oil field. The Fitts pool opened a new geological province for oil production. The structure is a faulted anticline in a graben. The producing formation (Bromide) and the Arbuckle lime below it crop out about 2 miles south of present production. The Hunton lime crops out about 2½ miles north. The field is in a sharply folded and faulted area on the northeast side of the Arbuckle uplift. Heretofore, it was generally considered not favorable for oil production, although some gas had been found in various places. The play has extended east into the McAlester coal basin, and southeast toward the

Jan 1, 1935

Andrew Carnegie, America's best-known ironmaster and philanthropist, died at his home at Lenox, Mass., Monday, Aug. 11, after a three days' illness. A pioneer in the steel industry, he introduced into this .country the Bessemer process And formed the plans that have resulted in this country's supremacy in the steel markets of the world. Known throughout the world for his, gifts, he is also known to engineers as the donor of the home of their National Societies and as the founder of the Carnegie Institute of Technology, of Pittsburgh. For many years, also, he was an honorary member of the American Institute of Mining and Metallurgical Engineers, the American Society of Mechanical Engineers, and of the Engineers Club of New York. What he considered the secret, of his success is shown by the epitaph he wrote for himself, "Here lies a man who knew how to enlist in his service better men than himself." He was buried Thursday, Aug. 14, in Sleepy Hollow Cemetery, Tarry-town, N. Y., the funeral services being private, in accordance with his wish.

Jan 9, 1919

By E. F. Young

The Porter Tunnel will open up 10 million tons of coal for Philadelphia & Reading which can be taken without hoists or pumps.

Jan 3, 1951

By Edward Wisser

The environment of an ore body is taken to mean not only its physical surroundings but every factor, passive or active, that conditioned the ore shoot, saving only the original composition of the solutions that formed the shoot. Collection of data related to the shape and characteristics of veins should be followed by correlation of the data and the formulation of generalizations regarding ore formation. The nature of the criteria used in arriving at these generalizations is discussed. Certain of the criteria, when used with an understanding of their underlying causes, become "ore-guides." In the course of his study the geologist must not confine himself to the immediate surroundings of the veins, but should attempt to work out the geologic history of events culminating in the crucial epoch for any mining district, the period of mineralization. The work may involve study of features far removed from the veins and related to them only indirectly. It commonly means thorough study of the geology of the entire region surrounding the ore deposits. THE following question has been suggested for discussion: ? "Are there any criteria by which one can determine when mining operations have reached the roots of an ore deposit?" The question deals less with the roots of a particular ore body than with the lower limit of the vertical range within which ore bodies may be expected. It concerns a critical line upon the longitudinal vertical projection of a vein. ? Below this line it is useless to look for ore shoots; above the line exploration below the bottoms of individual ore shoots may be justified. Can we learn to determine the position of such a line?

Jan 1, 1939

E. R. Rice, Wickenburg, Ariz. (communication to the Secretary*):—While this paper is primarily intended as a discussion of Mr. Riter's, I think it will be best to indicate my criticism by describing my own field-methods. It has been my experience that, for ordinary work, the regular transit-book is to be preferred to the card-system for recording notes. This is specially true when computations in the field are required, for it is then necessary to have at hand the total latitudes, departures, ancl elevations. Moreover, the transit-book is easier to carry and manipulate in wet or cramped places, and is not as liable to damage as the loose leaf or card. I use a regular transit-book in the field, and then copy my notes, sketches, etc., in an o5ce-book, entering also the latitudes, departures, and other reductions. These values are then copied into the field-book, securing a duplicate record, in case either book should be lost or mislaid. In the field-book, the notes are entered on the left-hand, and the sketches and remarks on the right-hand page. The next two pages are left blank for the latitudes, departures, bearings, reduced distances, etc. Of course, the notes for the different parts of the mine are entered in the field-book in the order in which they are surveyed; but in the they are entered systematically. It has been my experience that the system of keeping notes used by a surveyor, is particularly adapted to the needs and temperament of the individual. Otherwise, he would not be

Jan 1, 1912

By John C. Kleiber, George M. Meisel

From time to time since the initial installation of an experimental flotation section in 1940, Permanente Cement Co. has made efforts to beneficiate the low-grade limestone fraction which occurs in its deposits at Permanente, Calif. The encouraging results outlined in this article are the result of Permanente's latest effort. THE PERMANENTE LIMESTONE AND THE REASON FOR ITS BENEFICIATION The Permanente deposit is a sheet of Calera limestone over 700 ft thick lying within the Franciscan sediments of the San Francisco peninsula. Limestone suitable for cement manufacture underlies, overlies, and is interbedded with low-grade limestone and chert. Andesite intrusions are found as a secondary gangue. The limestone is identified as follows:

Jan 3, 1964

By M. E. de Morton

Recovery and early recrystallization of heavily deformed, 99.98 pct Cr was investigated by studying metallographic structure. X-ray line sharpening, electrical resistivity, plastic properties, internal friction, and shear modulus. Appreciable recovery of resistivity, internal friction, and shear modulus together with some hardening and relief of internal strains occurred before the visible growth of a textured substructure above 350°C (recrystallization in situ). The complex behavior of shear modulus, internal friction, and its strain amplitude dependence during annealing are discussed qualitatively in terms of the relative mobility of dislocations. BY plastically deforming fully recrystallized 99.98 pct Cr above the brittle to ductile transition temperature, at -350°C. as in wire drawing, chromium can be made very ductile at room temperature. However, this ductility is lost on annealing at high temperatures when recrystallization takes place.' The present investigation was made to determine the general pattern of the changes in a number of physical and mechanical properties during recovery and recrystallization of heavily deformed chromium as part of an effort to elucidate the reasons for lack of ductility in the fully recrystallized condition. PREPARATION OF MATERIAL Wire specimens 0.027 in. in diam were prepared from arc-melted, electrolytic chromium by extruding, hot swaging and finally wire drawing at 300" to 350°C, i.e. above the brittle-to-ductile transition temperature. The total reduction in area of the wire was 98 pct and the last 3 pct of reduction was made at 100" to 150°C before cooling to room temperature. The impurity content of the material is shown in Table I. Internal friction and modulus measurements were made on a single specimen after annealing in situ at successively higher temperatures. For all other measurements, a fresh specimen was used for each temperature and annealing of these specimens was done in evacuated (0.001 mm Hg) and sealed silica tubes for 1 hr at the various temperatures up to 700°C. EXPERIMENTAL METHODS AND RESULTS The occurrence of a. transition in some physical properties of chromium at - 40°C2 imposed limitations on the temperature region where some of the measurements could be made. The reason for this transition in chromium is at present unknown but is probably associated with an antiferromagnetic state observed below - 40°C.* Heavy deformation produces an anomalous decrease in resistivity when measured at temperatures below -40°C4 though a normal increase is observed above this temperature. On the other hand internal friction in heavily deformed chromium5 over the temperature range 40" to 50°C is invariant with temperature. Above and below this range internal friction is strongly temperature dependent, increasing with increasing temperature. A temperature in this range was therefore convenient for both resistivity and internal friction measurements and for consistency the measurements of the mechanical properties were also made at about this temperature. No structural change has, however, been observed in careful X-ray measurements6 between -195" and 50°C, i.e. departure from cubic symmetry was not greater than 3:10,000; X-ray line sharpening measurements were therefore more conveniently made at room temperature.

Jan 1, 1962

By A. L. Bailey, B. A. Landry

All who are even generally aware of the tremendous rate of increase in coal washing operations must realize the growing importance of the float-and-sink test. I believe it is conservative to estimate that, in the past decade, the dollar volume of float-and-sink testing has increased tenfold. It is a simple matter of economy, then, to examine the factors that determine the cost of adequate float-and-sink testing. When the Coal Preparation Section of the Bureau of Mines entered upon a greatly expanded program of such work in connection with the synthetic liquid fuels investigations, it seemed advisable to examine these factors experimentally. The principal consideration that differentiates float-and-sink test sampling from general purpose sampling, is that the original particle size must be preserved. Therefore, the total cost of the test will be directly affected by any standard that might be proposed to limit sample bulk reduction at any given particle size. For this reason, the relationship of sample size to variability of results was the first factor to be studied experimentally. Of course, the matter is rendered complex by the circumstance that the float-and-sink test, not a simple analytical measurement but a process test, comprehends a number of more-or-less independent items of fundamental data; and as shown in the report, the' variability of the samples differs with respect to these different items. This condition and the wide variety of situations in which float-and-sink test data are used, in combination with other factors, to study complex process operations, indicate the difficulty of setting up fixed standards for float-and-sink sampling and testing. At this stage at least, it is the intent rather to obtain experimental data on the principal Factors involved so that the reader may arrive more intelligently at a procedure adapted to his problem. The authors of this paper have presented experimental data showing the relationship between size of sample and particle size for different variability tolerances with respect to percentage of sink. In further studies, data are being collected to appraise also the variability of the samples with respect to float-ash content and size consist. The scope of this work will be broadened to cover particle sizes up to 4 in., and a third series of tests has yielded similar data for a much cleaner type of raw coal. Thus, the further studies will make available a fairly comprehensive meas- ure of variability with respect to size consist, percentage of sink, percentage of middlings, and percentage of ash in the float, for three coals ranging from 3.87 to 17.68 pct in refuse content (heavy sink material) and from 4.18 to 17.52 pct in middlings. Introduction At present there are no published standards for float-and-sink test sampling. During the rapid expansion of float-and-sink test work, varying procedures have been based on adaptations of the ASTM standards for sampling coal for analyses. For this reason, a special study of gross sample reduction has been undertaken to determine the limits for this step in the operation where no reduction in particle size is to be made before testing. Float-and-sink tests are made whenever a thorough study of coal characteristics is desired. The tests may be made on samples from coal-cleaning units such as jigs or tables, or coal samples may be tested which are taken from a loading boom, railroad car, or the coal seam itself. The resultant gross sample may be large and pose a problem of sample reduction. The question is, then, how much can the sample be reduced and still fall within preassigned limits of accuracy of the original gross sample of coal? Coal from channel samples may be crushed to liberate impurities and then separated into various gravity fractions from which washability curves are drawn; from these curves, it is possible to determine the cleaning characteristics of the coal. However, coal samples from coal-cleaning units cannot be

Jan 1, 1950

By Friedrich Wellmer

INTRODUCTION The Ramsbeck Pb/Zn Mine is located in the northern Sauerland area of West Germany, 150 km N of Frankfurt and 120 km E of Cologne. This is a vein deposit which has been worked from the middle of the 19th century to 1974. About 15 million tons of ore were mined and milled. The ore district contains several vein deposits and is roughly 14 km in length and 4 to 5 km in width. The host rocks are strata of Lower Middle Devonian age. The strata strike 60° to 70° NE and where overturned have a dip steeper than the veins (Fig. 1). The galena-sphalerite mineralization is in quartz veins, which are mineralized where they cut the "Main Ramsbeck Quartzite" horizon, a very competent host rock. Vein structures strike at 65º to 75º, dip about 20° to 25º SE and cut the quartzite at approximately 60 m intervals. The main or "steep veins" within each vein structure dip at 10º to 80° SE with an average of 30° and are offset by thrust faults dipping 5º N to 40° S with an average of 5º S. "Flat veins" usually weakly mineralized occur in the thrust faults between the "steep veins", thus forming the overall step-like vein structure. The mineralization is very irregular and changes a- long strike and down dip. It consists of thin veins of pure sphalerite and galena with quartz and pyrite. The thicknesses of the pure sphalerite and galena veins

Jan 1, 1977

By T. F. Archbold, P. G. McCormick

Silica fiber 11arkevs and hardness irzdentatiozs have been used to study the thermal diffusion of racancies in zinc placed in temperature gradients of 460o and 706oK per Cm All markers mored toward the higher temperatures, and the data show that the heat of trarlsport Q is greater than the eizthalpy of z,acancj3 forrjalion E by an amount equal to 3.5 kcal per mole. These results ore not in agreement with those obtained in either of the two previous studies with zinc. The problem is discussed in terms of experimental differences and racancy source and sink efficiencies. THE general interest in thermal-diffusion phenomena over the past several years has prompted a number of marker movement studies using pure metals. In order to understand better the relationships between thermal and mass flow, a general goal of the experiments has been to obtain values for the net enthalpies carried by the diffusing atoms. For self-diffusion by means of the vacancy mechanism, the determination of relative marker positions before and after an anneal in a temperature gradient permits a calculation of a value for (Q - Ef). Q is the transferred enthalpy, and Ef is the enthalpy of vacancy formation in the metal being investigated. The initial experimental study of thermal diffusion in pure metals was accomplished by Shewmon who found essentially no movement of surface-hardness indentation markers in single and bicrystals of zinc held for 20 days in a temperature gradient of 310°C per

Jan 1, 1967

By Henry Louis

The object of the present paper is to describe a primitive method of gold-extraction, practiced by a small colony of Chinese in the district of Tomoh, one of the Siamese-Malayan States. This district has been worked for gold about 150 years, but has been only twice or thrice visited by Europeans, who are looked upon with a good deal of jealousy by the miners. The gold-district, covering not more than 10 square miles, is situated about Lat. 5' 47l N. and Long. -101' 39 E., on the headwaters of the river Teluban. It is a very mountainous region, lying on the northern flanks of the great range that forms the watershed between the rivers Patani, Kelantan, Teluban, etc., on the north and Perak on the south. The gold occurs in narrow veins and leaders of quartz, intersect- ' ing and intercalated among irregularly upheaved and contorted, highly metamorphosed, micaceous and chloritic schists. These veins vary between 3 inches and 3 feet in thickness, and are sometimes very rich. The geology of this region is thus very similar to that characterizing gold-regions all over the world; if must, however, be.

Jan 1, 1892

By Lachlan Gilchrist

MEASUREMENTS of resistivity by methods involving the use of two current electrodes and two potential electrodes in general collinear with the current electrodes have been made extensively in geophysical investigations. In the method developed by Wenner and made use of by Gish and Rooney, and later in a modified form by Lee, the distance between the current electrodes is divided into three equal parts by the potential electrodes. In one of the methods developed by Schlumberger prospecting methods and by Koenigsberger, one current electrode is placed at considerable distance from the other and potential measurements are made in the immediate neighborhood of one of the current electrodes. The method is described as the single current electrode method, and the effect of the distant current electrode is considered negligible or a correction is made for the effect in the calculation of the resistivity. Usually the correction that is introduced is based on the calculated effect for measurements made in a homogeneous conducting material. The useful application of these methods in prospecting for minerals, of course, is in regions where nonhomogeneous conditions exist. In many of these conditions it is very doubtful whether the effect of the distant current electrode may be neglected, except for measurements in the immediate neighborhood of the "single" current electrode, and corrections based on homogeneity of the medium will necessarily be inadequate. In order to obtain a degree of symmetry that would preclude the necessity for corrections for the distant electrode and that would simplify interpretation, it appeared desirable to use a central current electrode and a set of distant end current electrodes symmetrically placed about the central electrode as shown in Fig. 1 and to provide by means of auxiliary resistances that the currents passing into the earth at the distant end electrodes should be equal. Circumstances did not permit the operation of this plan in complete detail but a degree of symmetry was obtained by using a central current electrode and two distant collinear end current electrodes and by taking measurements along a line passing through

Jan 1, 1931

By F. E. Turton

THE town of Rancagua, at the junction of the state and Braden Copper Co. railroads, is located 82 km south of Santiago, the capital of Chile. From Rancagua 70 km to the east, situated in the Andes at an elevation of 7000 ft, is the town of Sewell, the location of a millsite. Two and one half km east of Sewell by underground railroad at an elevation of 7500 to 10,000 ft is the Teniente orbody. The history of El Teniente dates from the eighteenth century, when according to legend a Spanish lieutenant, or teniente, a fugitive from justice, escaped to the Andes and camped at what afterwards became known as the Mineral El Teniente. This man reputedly discovered a vein of high grade copper ore. The first official records date from 1819, when some exploitation was begun, and continue until 1870. The orebody was large and of relatively low grade and was beyond the capabilities of the small groups attempting to operate it. No effort was made to erect a concentrator until William Braden became interested in the property. In 1901 Mr. Braden promoted the necessary capital for the first practical exploitation of the orebody. Barton Sewell and E. W. Nash, both of the

Jan 1, 1952