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By Paul Tyler

FULLY a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite,2 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines, It is largely a matter of mar-kets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal,"

Jan 1, 1938

By W. Tovote

This paper is based upon 12 years' experience in the Southwest, including three years that were spent in constant traveling as examining engineer for the Phelps-Dodge Corporation. The material was gathered during rather extensive work in Bisbee, Clifton-Morenci, Globe, and Tombstone, and also on short and rapid trips into most of the mining camps and prospect fields of New Mexico, Arizona, the desert country of California, and as much of Sonora as was safe at the time. My methods of observation and my deductions are not put forward as new or scientific; they are simply rough field methods, based upon short notes, rough sketches, and largely upon memory, which I have found useful for coördinating geological data for the purpose of passing quick judgment on mining possibilities in certain districts exhibiting uniform characteristics. The opportunities for observation have been better these last few years than ever before, due to the unprecedented activity in mining, which has caused the reopening of hundreds of old mines and the starting of even more numerous prospects all over the mining states. Possible Systems of Classification By Geological Provinces There are a number of well defined geological provinces in the territory under discussion, and a study of their individual features is of interest. The following are a few of those that are most striking in their uniformity. 1. The "Desert province," extending roughly from Wickenburg, Ariz., to and beyond Barstow, Cal. In its north-south extent it reaches up to the Colorado River and down into Sonora, but overlaps other provinces. It is characterized by a worn-down basement of schistose and granitic rocks, on which rest remnants of Paleozoic and pre-Paleozoic sediments, including very old limestones. The sediments are disrupted and contorted. Alteration in the mineralized areas is very prominent, especially in the schists and limestones. Cenozoic volcanic rocks, principally of semi-basic composition, have been intruded into this complex and sometimes cover it as lava flows. 2. The "Yavapai schist" province, similar to the one first mentioned, consists of metamorphosed basic and semi-basic rocks. It lies in northern

Jan 1, 1920

By E. L. Dougherty, J. W. Sheldon

A numerical method for computing the dynamical behavior of fluid- fluid interfaces is described. Results of studies made to assess the accuracy and economy of the method on a computer are reported. It is concluded that it is practical to obtain digital computer solutions for fluid- fluid interface problems with two space dimensions. PROBLEM DEFINITION We consider two-dimensional flow in a rectangle as shown in Fig. 1, where a fluid-fluid interface divides the rectangle into two regions. The pressure is specified along the lower boundary (the injection boundary) and upper boundary (the withdrawal boundary). There is to be no flow of fluid across the side boundaries, which are walls of symmetry for the flow, and px = 0 along these boundaries. The fluids are incompressible, the absolute permeability and porosity is constant, and each fluid has its own constant mobility. Thus, the pressure satisfies Laplace's equation in each region. Across the interface, pressure is continuous and the normal component of fluid flux is 1. These conditions are shown in Fig. 1. The velocity of a point on the interface in the direction of the normal from Fluid 1 into Fluid 2 is U,/ Q, where Un is the normal component of volumetric flux at the point on the interface, i.e., For brevity, we call the problem defined above "Problem A". Problem A is a simple example of a dynamical fluid-fluid interface problem. However, the same numerical methods which we use to solve Problem A can be extended to the solution of a large number of fluid-fluid interface problems which are mathematical models for various oil recovery processes,l hence our interest in Problem A. We define the interface by prescribing the x, y coordinates of a finite set of points. These points are called "interface mesh points" and are illustrated by triangles or asterisks in the figures. Fig. 2 is a procedural (flow) chart displaying the main steps in the solution. We comment briefly on some of these steps in this section and then give further details in subsequent sections. For mobility ratio greater than one it is well known that Problem A is unstable.*2 Small amplitude,

Jan 1, 1965

By John R. Freeman

The die pressing of brass may be described as a method of producing irregularly shaped parts of brass and other copper alloys by hot deformation in a die under pressure. Die pressing of brass was first developed as an improvement on sand castings in order to obtain irregularly shaped articles of brass with superior surfaces, a closer tolerance in dimensions, a denser structure, freedom from porosity and elimination of the relatively large amount of scrap invariably attached to sand castings. The freedom from sandy surfaces with consequent greater tool life in machining operations was also recognized as well as elimination of losses due to the uncovering of blowholes in machining operations. Die pressing also gave alloys of superior strength. Die pressings today are made from extruded rod or shapes, according to design of the part to be made. The greater number of pressings are made from round rod, because of its relatively lower cost and ease of handling. The rod is first sheared or sawed into desired lengths, the diameter of rod used and length of "slug" or "rivet" depending upon ultimate weight and shape of the die-pressed part to be made and design of die. The dimensions of the slug are figured so as to give the minimum amount of scrap to be sheared from the pressing as it comes from the die. Extruded shapes having I, T or X sections are often used when the finished part is to have a similar shape or heavy sections are joined by relatively light sections of considerable length. A rod bent in the shape of a U is also used on occasion, for similar reasons. Proper shearing of the slugs is of considerable importance. The sheared ends of the slugs should be as flat and straight as possible. Improperly sheared ends having an angle to the axis of the bar or a rough, uneven surface are liable to give folds or laps in the finished pressing and proportionately high rejections. The property of shearing varies considerably with different alloys and should be considered in the selection of a material for a given part. Where satisfactory shearing is not possible, the slugs may be cut from the bar by power saws. Extruded

Jan 1, 1931

By M. R. Todd, J. Szekely

THE mechanism of carbon oxidation in steelmaking processes has attracted considerable attention in recent years. The generally accepted model postulates that the reaction between carbon and oxygen occurs at the surface of CO bubbles that originate at the suitable nucleation points and subsequently rise through the metal bath.1-4 Although this model describes adequately the behavior of open-hearth type operations, it is not a satisfactory representation of carbon oxidation in oxygen steelmaking processes since it cannot account for either: i) the very high rate of oxidation per unit bath area,or ii) the commonly reported shapes of the curves showing the dependenie of the oxidation rate on the carbon concentration. The very high decarburization rates commonly encountered in oxygen steelmaking processes need no further elaboration; some typical plots of the rate of carbon removal against carbon concentration, taken from a publication by Li, Dukelow, and smith,' are reproduced in Fig. 1. It is seen from the curves that the decarburization tends to decrease from a peak or a plateau once the carbon concentration falls below a certain value; in the experiments reported, this critical value ranged from 1.2 to 0.2 wt pct C. The apparent dependence of the decarburization rate on the carbon concentration indicates that within this region phenomena associated with the transfer of car- bon must play an important if not predominant role. Since the concentration of oxygen in molten iron at steelmaking temperatures (removed from the immediate impact zone) is only about 0.1 wt pct,6 it is clear that simple simultaneous diffusion of carbon and oxygen to the surface of CO bubbles could not account for the rate of carbon transfer being the controlling step at carbon concentrations as high as 1.0 wt pct. The purpose of this communication is to present an alternative model which may explain at least qualitatively the apparent anomalies mentioned and may stimulate further experimental work. The Physical Model. It is suggested that the principal mechanism of decarburization is the reaction between CO bubbles and an emulsion consisting of molten iron and molten iron oxide particles in the vicinity of the "slag-metal interface9'.* This mech-

Jan 1, 1968

By L. D. Frink

THOSE actively interested in mining are fully aware of the ever-increasing difficulty of making conditions such that efficient work can be clone in underground openings, especially as higher rock temperatures are encountered in depth. This is also true where an effort is being made to cut down the burden of overhead expense by working headings 24 hr. in a day if blasting is done as often as is possible in that time. That the conditions resulting from both these causes have driven the native-born Americans from the mines and that their places have been taken by less efficient foreigners is a fact that we must all admit. The great war now being fought in Europe and the educational qualification clause written into our immigration law by the last Congress will probably limit very materially the supply of labor, such as we are now using in our mines, and will force upon mine operators the necessity of making this work appeal again to Americans. Metal tubing, with blower or exhaust fans, has long been used in supplying air to dead ends where natural ventilation is impossible, or in driving the smoke from such places, or in doing both, as the need might be. Here in Butte we have now come to use canvas tubing very extensively and find that it has many advantages not possessed by the metal. The use of flexible tubing is not new, but it has not been generally used in mining operations. Recent improvements, however, in the canvas itself and in the jointing of sections and manner of suspension have so increased its usefulness that it promises to add much to the efficiency of mining. There is now on the market a product that is impervious to air, is fireproof, and has a system of jointing which, permits it to be put up or taken clown in a few seconds. In this article an effort will be made to explain the manner in which canvas tubing is being used in the North Butte company's operations at Butte, Mont. The accompanying photographs will, I hope, help make clear what may be done with this material.

Jan 1, 1918

By R. A. Corley, W. R. Wilcox, J. R. Teviotdale

Chemical vapor deposition of hafnium carbide yielded whiskers, needles, dendrites, faceted crystals, and adherent coatings. The gas stream compositiom and the mass transfer conditions determined the habit of the deposit. The deposits were obtained at temperatures ranging from 1100" to 1800°C. HAFNIUM carbide has the highest melting point of any binary compound; therefore, its various potential applications are a subject of vital interest to the aerospace industry. The experiments described herein were performed to investigate the chemical vapor deposition of hafnium carbide with particular interest being placed upon the possible production of high-strength single-crystal whiskers for composite materials. In 1931 Moers 1 used a gaseous mixture of HfC14, Hz, and toluene to vapor deposit crystalline hafnium carbide on a tungsten filament heated to 2400°to 2800°C. More recently Lepie 2 deposited hafnium carbide on graphite using HfC14 and methane in a helium gas carrier. The pyrolytic depositions described here were accomplished in graphite tubes by using various gas mixtures and dopants. The resulting crystal habits included whiskers, needles, needle dendrites, bulbous dendrites, faceted crystals, and smooth, adherent poly-crystalline layers. EXPERIMENTAL The depositions were carried out in an induction-heated graphite tube, 1.2 cm ID, which was contained in a vertical 9-cm-ID quartz tube. (A more detailed account of the experimental procedures and results is given in Ref. 3.) Refractory oxide fiber and tubes and graphite felt were utilized jointly and singly for therma1 insulation. A typical temperature distribution is shown in Fig. 1. The reactant gases were introduced at the top and removed at the bottom of the tube. Table I summarizes the experimental conditions and results. Many deposition habits were obtained. X-ray analyses showed that they possessed the hafnium carbide structure. Almost invariably these formed well above the point of maximum temperature in the graphite tube. The habit depended strongly on the gas composition. In a series of runs (e.g., run A) using HfC14 and toluene in H 2, hafnium carbide coatings, Fig. 2, were reproducibly obtained at the position where the tube wall was 1400°C, and bulbous dendrites, Fig. 3, were

Jan 1, 1969

By Paul M. Tyler

FULLY a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite12 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines. It is largely a matter of markets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal,"

Jan 1, 1938

By A. H. Hand

When considering the question of future demand for crude petroleum in California, one must first decide whether it is to be approached in the light of the definition of "demand" when used in economics; i.e., "The quantity of any commodity required or sought in the market," or in the light of markets developed to dispose of total supply. Therefore, is the California demand of future years to be predicated on a continuation of supplying markets developed following the surplus production commencing in 1922, or predicated on supplying what would be termed economic markets ? If the latter, what are economic markets ? Obviously, the Pacific Coast States and Canada, Alaska, Hawaii and probably the Pacific side of Central and South America, can be considered as normal markets for California petroleum products. While there have been small quantities of gasoline shipped into the PacSc Coast from East Texas, transportation costs, plus import taxes in the case of foreign oil, are a sufficient barrier to justify considering that these markets will be retained. But how about our participation in Atlantic and Pacific foreign and intercoastal markets? During the five years preceding 1931 California shipped substantial quantities of gasoline to the United Kingdom and to France, Germany and Italy. During recent years our business in European markets has been restricted to occasional shipments of gasoline and Kettleman crude. This loss of business is occasioned by the development of production in the Mid-Continent, principally East Texas, and in Iraq, Rumania, Venezuela and other closer producing areas, which makes it impossible at the prevailing crude-oil prices for California to be competitive in supplying any substantial portion of these markets. It is therefore apparent that under a stabilized price structure that will return the California producer a reasonable price for his oil, future Atlantic foreign -business will be restricted to occasional spot cargo sales. As to Pacific foreign shipments which, in addition to Central and South America, consist principally of shipments to Japan, China, Australia and New Zealand: A considerable portion of the business we had with Australia and New Zealand until four or five years ago is now being

Jan 1, 1937

By Joseph A. Norden, A. R. Willson

Much has been written concerning the hoisting equipment of various mines throughout the country, but most of the literature on the subject, if not all, describes equipment of extraordinary capacity and the small and medium-sized outfits have been neglected. The hoisting equipment here described is capable of handling about 1200 tons per day. It has not been worked to capacity, but 600 to 700 tons, together with men and materials, have been handled in two shifts without any great effort. Only one shaft extends from the surface to the lowest levels of the mine; see Fig. I. It is composed of three compartments, two of which are used for hoisting, and the third for water, air, and electrical lines, and for sinking purposes. In 1909, this shaft was raised from the 1000-ft. (304-m.) level to the 700-ft. There a station was cut and an air hoist installed. At this time all mining operations were confined to the upper levels of the mine; that is, above the 700-ft. The ore was dropped to this level through chutes from the 300-, 400-, 500-, and 600-ft. levels and then lowered in cars on cages to the 1000-ft., which is the main haulage adit, the mill and railroad bins being about 3000 ft. from the shaft. Orebodies were, in due time, developed on the 1000-ft. level and below. Therefore, in 1913,the shaft was sunk to the 1150-ft. level and thereafter sinking was continued at regular intervals until the 1500-ft. level was reached. But, hoisting from the 1300-ft. level was a difficult and slow process with the antiquated air hoist, so, in 1916, it was decided to raise the shaft to the surface and install a modern, electrically operated hoist. This was completed early in 1917 and the hoist was in operation in March of that year. The Hoist Figs. 2, 3, and 4 show various features of the hoist and electrical equipment. A Nordberg engine of the double-drum, geared type, designed for a 10-ton load, including rope, at a speed of 1500 ft. per min., is used. The drums are 7 ft. (2.1 m.) in diameter, with a 54-in. (137-em.)

Jan 1, 1922

By A. L. Labbe

IT Is well known that the Cottrell process is more easily applied to certain kinds of smoke than to others. The successful Cottrell installations are those treating smokes that carry dust of a mechanical nature; also smoke carrying fume dust that contains an excess of sulfuric acid over that required to combine with the oxides in the dust. But up to the present time the process has not reached a satisfactory economical basis of operation, in the treatment of smoke' containing basic dust. It is not impossible to make a smoke containing basic dust suitable for the process by. humidifying or acidifying. A number of Cottrell plants use these two methods of conditioning smoke previous to Cottrell treatment, which are quite successful, but the use of either results in expensive operation and a substantial loss in metals.. For these reasons, I would say that the baghouse process has not been replaced by the Cottrell process in the treatment of smelter basic smoke. Basic smoke must be given a. preliminary conditioning treatment because the dust is not a conductor of electricity; the water or acid treatment imparts some conductivity to the dust.. The rate at which dust is recovered depends on the proportional amount of power transmitted to the, treater and on the rate at which the smoke passes through; therefore to maintain a maximum constant amount of power across the electrodes of the treater, the same degree of conductivity should prevail, at all times between the surface of the electrodes. For all practical purposes, in the application of this process to lead and copper-smelter smoke, we can consider that the conductivity of the gases is a .constant. The variations in temperature of the smoke have a much greater effect on the solids than on the gases; the only instance where the temperature of the gases plays an important part in the process is at plants using humidifying: The temperature does not affect the conductivity of mechanical dust because such dust has natural conductive properties. However, in the case of smoke carrying acid-fume dust, where the conductivity is imparted to the dust particles by coming into contact with the acid fumes, the temperature is of importance.

Jan 8, 1925

By Theodore P. Holt

The Mines Operating Co.'s plant at Park City, Utah, was designed to treat the low-grade fillings in the old stopes of the Ontario mine. These fillings carry 6 to 14 oz. of silver, 1 to 2 lb. of copper, 0.01 to 0.015 oz. of gold, and a small percentage of lead and zinc. The treatment consists in mixing the crushed ore with coal dust and salt and then roasting in a new type of furnace by combustion of the contained fuel. The roasted ore is leached with an acid salt solution to dissolve the silver, gold, copper, and lead. At present these metals are precipitated together on scrap iron and the product sold to a refinery. The only new feature of importance in this scheme of treatment is the roasting process, which makes possible the chloridizing of ores without any loss of the valuable metals, and at a very low cost. History of the Development of the Process The roasting process- had its beginning in connection with research work at the Utah State School of Mines. N. C. Christensen, Jr., who held one of the School of Mines' fellowships, was engaged in some experimental work on blast roasting. At the same time I was doing some work on the insoluble gold in Mercur base ores. Mr. Christensen roasted some of this base gold ore in his pot furnace, and found that when he mixed a sufficiently low percentage of fuel with the ore, it did not sinter but roasted to a leachable product. We considered this a new application of blast roasting, and proceeded to test out a large number of ores in several different types of small roasters which we constructed.. This experimental work continued well into the summer of 1911. In August, 1911, the Consolidated Mercur Gold Mines Co. installed a small roaster of our design, which we proposed to operate on the counter-current principle, feeding mixed ore continuously on top, and at the same time drawing off the roasted ore from the bottom. By proper adjustment we hoped to maintain a permanent roasting zone near the center of the column, the ore moving downward as roasted. However, we

Jan 1, 1915

By L. A. White

IN this paper it is proposed to follow the developments in the design of the lead blast furnace at Port Pirie from the time The Broken Hill Associated Smelters Pty. assumed control in 1915 to the present time, with special reference to the development of the system using two superimposed rows of tuyeres as is now in operation. Lead smelting operations first commenced in 1889, when the British Broken Hill Pty. Ltd. started its first furnace. This was followed by installing two more furnaces during the same year and another the following year. In 1892, Broken Hill Proprietary Co. Ltd. acquired the smelting works and combined operations with those at Broken Hill, New South Wales; by 1897, the whole of the smelting operations had been transferred to Port Pirie and thirteen blast furnaces were built to treat the Broken Hill ore production. In 1915, The Broken Hill Associated Smelters Pty. Ltd. took over from the Broken Hill Proprietary and have carried out operations since that time. From its inception, the present company started on a long range program of reconstruction, in which the development of the lead blast furnace has played a prominent part. A definite trend in plant development has been towards the simplification of plant control by a reduction in the number of operating units. The great advantages of technical control which resulted from the very simplified flowsheet established in the continuous refining process stimulated the desire to extend the principle to the smelting operation. Thus in the sequence of furnaces described here, it will be noted that the trend has been towards larger and, of course, fewer units. With each such development it is significant that the operating conditions and metallurgical results have shown steady improvement. Standard Furnace In 1920 there were seven furnaces operating, five of a type subsequently called the standard furnace and two of the original thirteen smaller furnaces, the latter type being used for the treatment of drosses, etc. produced from the refinery section, while the standard type carried out the main, lead-smelting operations. The standard furnace (figs. 1 and 2) had the dimensions given in table I.

Jan 1, 1951

By W. T. Turrall, D. Porter

The paper describes a machine developed for the purpose of concentrating clear optical grade fluorspar crystal from a feed material containing less than 1 pct impurities. The principle of concentration is based on the fact that in a liquid having an index of refraction equal to that of fluorite (n — 1.434) clear crystals are invisible, whereas crystals containing occluded impurities absorb a part of the light. As the crystals pass through a light beam, undesired crystals give themselves away by creating a shadow on a photoelectric receiver. .The shadow is converted by the photoelectric cell into an electric pulse. An electronic circuit amplifies this pulse and commands the operation of a mechanical concentrator. Hp HE crystal laboratory, Dept. of Physics, Massa--*- chusetts lnstitute of Technology, was confronted with the problem of obtaining a supply of optical grade calcium fluoride (CaF,) for use in growing synthetic CaF, crystals. A search of the known fluorspar deposits did not indicate that any quantity of optical spar could be obtained. Even the best material had to be sorted by hand to remove impurities. The process for growing CaF, crystals developed by Professor D. C. Stockbarger of the Dept. of Physics, M.I.T., necessitates very pure feed materials. Exclusion of impurities is required, even in amounts detectable only spectrographically. The impurities occurred as minute inclusions of SiO,, BaSO,, CaCO,, FeS2, water or air. Crystals up to 4 in. in diam and weighing several pounds are made by the Harshaw Chemical Co. in Cleveland. Since the time required to grow a 4-in. crystal is about one week, and since the cost of manufacture is high, removal of impurities by any concentration method appeared practical. The mineral engineering section of the Dept. of Metallurgy undertook to investigate the possibility of concentrating clear optical fluorspar, —4 mesh + 10 mesh, from a feed containing over 99 pct CaF,. Various innovations of the known methods of concentration were considered, but in each case the minute amount of impurities associated with the crystal produced such extremely small differences

Jan 1, 1953

By W. T. Turrall, D. Porter

The paper describes a machine developed for the purpose of concentrating clear optical grade fluorspar crystal from a feed material containing less than 1 pct impurities. The principle of concentration is based on the fact that in a liquid having an index of refraction equal to that of fluorite (n — 1.434) clear crystals are invisible, whereas crystals containing occluded impurities absorb a part of the light. As the crystals pass through a light beam, undesired crystals give themselves away by creating a shadow on a photoelectric receiver. .The shadow is converted by the photoelectric cell into an electric pulse. An electronic circuit amplifies this pulse and commands the operation of a mechanical concentrator. Hp HE crystal laboratory, Dept. of Physics, Massa--*- chusetts lnstitute of Technology, was confronted with the problem of obtaining a supply of optical grade calcium fluoride (CaF,) for use in growing synthetic CaF, crystals. A search of the known fluorspar deposits did not indicate that any quantity of optical spar could be obtained. Even the best material had to be sorted by hand to remove impurities. The process for growing CaF, crystals developed by Professor D. C. Stockbarger of the Dept. of Physics, M.I.T., necessitates very pure feed materials. Exclusion of impurities is required, even in amounts detectable only spectrographically. The impurities occurred as minute inclusions of SiO,, BaSO,, CaCO,, FeS2, water or air. Crystals up to 4 in. in diam and weighing several pounds are made by the Harshaw Chemical Co. in Cleveland. Since the time required to grow a 4-in. crystal is about one week, and since the cost of manufacture is high, removal of impurities by any concentration method appeared practical. The mineral engineering section of the Dept. of Metallurgy undertook to investigate the possibility of concentrating clear optical fluorspar, —4 mesh + 10 mesh, from a feed containing over 99 pct CaF,. Various innovations of the known methods of concentration were considered, but in each case the minute amount of impurities associated with the crystal produced such extremely small differences

Jan 1, 1953

By D. Roberts

SUMMARY In order to accommodate a new plant in a limestone quarry in the Mendip Hills, it became necessary to excavate a potentially unstable disused face of the quarry. A simple two-dimensional graphical method was used to analyse a failure, which occurred during a period of exceptionally heavy rain in 1968, and the results of this analysis were used in estimating the stability of the proposed excavation. The presence of water in vertical fissures and tension cracks was found to be a dominant factor in determining the stability of these faces. The results of this approximate analysis were used as a guide in deciding upon the final slope design and the purpose of presenting this example is to illustrate how the various factors involved in arriving at this design were weighed to arrive at a compromise between theoretical recommendations and practical considerations. INTRODUCTION The successful outcome of a geological and geochemical survey to prove adequate re- serves of high quality limestone, suitable for producing burnt lime, led to planning for the installation of the necessary plant at Amalgamated Roadstone Corporation's Batts Combe Quarry at Cheddar in Somerset. Topographic and property boundary limits added to restrictions which were likely to be imposed by any forthcoming planning consents and restricted the choice of plant location to one site. The particular site is, in fact, the main floor area of the original quarry which, like many hillside quarries, had been worked with just one face. Before a benching scheme had been introduced on higher ground, the original face had attained a height of 230 ft. and sloped at angles of 58º to 64º. Fig. I shows the present configuration of the disused quarry face and the present working area above. The floor area below the disused face accommodates the existing crushing, conveying, and screening plant. The new facilities for lime burning are to be in addition to the existing main line business of producing roadstone and concrete aggregates and, although a new aggregate production plant would be included in the new installation, no disturbance of current production was to be contemplated.

Jan 1, 1972

J. C. WRIGHT.-The problem of organizing and maintaining a vocational class for those employees who are engaged in the mining industry depends on several most important factors. The first is the sympathetic cooperation of employer and employee; the second is to find the subject matter that must be presented to these men; and the third is to find the instructor who can present that subject matter. This is perhaps the most difficult, for we usually find a man who knows the material that is to be presented but is not a teacher or does not know how to organize his material. The man must know the subject matter from the standpoint of absolute contact with industry in order to be a successful teacher. I have come into contact with two kinds of schools organized in connection with mining occupations. In one type the instruction leans very largely toward elementary subjects, arithmetic, reading and writing and spelling; it is not of such a character as to help or improve the working man in his occupation in the sense that we are attempting when we speak of vocational education. In the other type of school, an engineer is usually employed as a teacher. He immediately begins to give the things with which he is most familiar and the instruction becomes such as only those who possess a high-school or college education, perhaps, are able to receive. In between these two schools is the school we are trying to, promote, a school that will meet the needs of those employed. MARGUERITE W. JORDAN,* Altoona, Pa. -Vocational education has become the business man's problem; for he is the keeper of that white elephant, labor turnover, and anything that will decrease the size of the monster is worthy of serious consideration. This vocational education can do; for it can supply many of those deficiencies in upbringing and. environment that make for the discontent and restlessness of our varied classes of unskilled labor: the Anglo-Saxon mountaineer; the Southern negroes who have crossed Mason & Dixon's line by the thousands, "searching satisfaction for our minds;" and the still greater number who have sought across the sea America, "the promised land.

Jan 4, 1919

By Richard H. Zinszer

Application Of electric logs has been used in correlation of subsurface structure to determine the size and shape of the oil reservoir. Such a knowledge is hardly complete until saturation and productivity are determined for the various horizons. It is difficult to use electric logs successfully for this purpose because of the many factors that influence the curves. In this work an effort was made to establish an empirical correlation between formation resistivity for a series of electric-log curves and water saturation and oil productivity of sand. Electric logs were obtained by recording with 10 different electrode spacings through the same interval of a well. In the analysis of these curves all factors except two, a dependent and independent variable, were held constant. The interval studied had been cored and a large number of samples were analyzed in the core laboratory in order to compare the values of permeability and saturation with the measured values of formation resistivity. Results of this analysis indicate: (I) the depth to which mud filtrate enters a sand body, (2) a correlation between permeability and sand resistivity for shallow penetration depths, and (3) that the water saturation for an oil sand can be determined from the measured sand resistivity after making suitable corrections for sand thickness. The procedure in the last method depends on a correction for thickness factor and a theoretical curve. The accuracy of the theoretical curve is now being tested in the laboratory Introduction In an effort to place the analysis of electric logs on a quantitative basis, there is need for a better understanding of the many factors that influence an electric-log curve. These factors may be large differences in sand thickness, permeability of the sand, salinity of the interstitial water, mud resistivity, formation temperature, and other sources. A number of examples were presented by Archie,' which treat the effect of sand thickness on measured resistivity. He compared the true resistivity of a sand with the observed resistivity for sands 8 it., 16 ft., and 24 ft. thick, and found the observed resistivity of the 8-ft. sand to be approximately

Jan 1, 1946

By Richard H. Zinszer

Application Of electric logs has been used in correlation of subsurface structure to determine the size and shape of the oil reservoir. Such a knowledge is hardly complete until saturation and productivity are determined for the various horizons. It is difficult to use electric logs successfully for this purpose because of the many factors that influence the curves. In this work an effort was made to establish an empirical correlation between formation resistivity for a series of electric-log curves and water saturation and oil productivity of sand. Electric logs were obtained by recording with 10 different electrode spacings through the same interval of a well. In the analysis of these curves all factors except two, a dependent and independent variable, were held constant. The interval studied had been cored and a large number of samples were analyzed in the core laboratory in order to compare the values of permeability and saturation with the measured values of formation resistivity. Results of this analysis indicate: (I) the depth to which mud filtrate enters a sand body, (2) a correlation between permeability and sand resistivity for shallow penetration depths, and (3) that the water saturation for an oil sand can be determined from the measured sand resistivity after making suitable corrections for sand thickness. The procedure in the last method depends on a correction for thickness factor and a theoretical curve. The accuracy of the theoretical curve is now being tested in the laboratory Introduction In an effort to place the analysis of electric logs on a quantitative basis, there is need for a better understanding of the many factors that influence an electric-log curve. These factors may be large differences in sand thickness, permeability of the sand, salinity of the interstitial water, mud resistivity, formation temperature, and other sources. A number of examples were presented by Archie,' which treat the effect of sand thickness on measured resistivity. He compared the true resistivity of a sand with the observed resistivity for sands 8 it., 16 ft., and 24 ft. thick, and found the observed resistivity of the 8-ft. sand to be approximately

Jan 1, 1946

By Alfred E. Hunt

The technical papers of the last few years give numerous in stances of serious failures by cracking or rupture of soft steel boiler plates, marly of which have satisfactorily passed the rigid inspection and tests required by both Lloyds' Register and the Board of Trade in England. I speak of the inspecting department of Lloyds' and the Board of Trade, for we do not begin to have as systematic and intelligent work regularly done in this country as is done by these institutions in England. Tension-tests of this steel have given from 65,000 to 65,000 pounds per square inch tensile strength, with from 20 to 30 per cent. elongation in 8 inches. Chemical analyses have shown the steel to contain from 0.12 to 0.15 per cent. carbon, from 0.25 to 0.40 per cent. manganese, and from 0.03 to 0.05 per cent. phosphorus. All of these tests are considered normal, and, in the words of one of our members, " boiler-plates with these qualities ought not to fail." There are, however, several causes of failure in soft steel plates which, although the writer does not presume to ascribe to then], or either of them, any particular instance, are still dangerous, and ought to be guarded against much more carefully than in usual present practice. These causes are: 1. The hardening property of all steel. 2. Insufficient work from the ingot to the finished plates. 3. Temporary fiber in certain steels. 4. Internal strains caused by unequal work upon the material. Hardening.-The writer, in a paper read before the Institute in October, 1883," made the statement that soft .steel, no matter how low in carbon, would harden to a certain extent upon being heated red-hot and plunged into water, and that it hardened more when plunged into brine and less when quenched in oil, and gave the results of one experiment, merely as an illustration of many which had all confirmed the statement made. The illustration was a heat of open-hearth steel made by the . writer, of 0.15 per cent. carbon and 0.29 per cent. of manganese, which gave (he following results upon test-pieces from the same 1/4-thick plate.

Jan 1, 1886