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By Robert D. Thomson

LISTED among strategic and critical minerals for stockpiling, mica is an important raw material in electronic and electrical equipment industries. Each year large quantities are consumed in the manufacture of television and radio tubes, radar sets, generators, transformers, electric toasters, and irons. Crude mica, which comes from the mine in crystals or in rough books of various shapes and sizes, is known as run-of-mine or book mica. Structural imperfections, impurities, rough edges, and defective laminae are removed by cobbing, rifting, and trimming to produce a marketable block mica or film mica.' After the rough books have been hand-cobbed to remove adhering rock, dirt, and crushed or defective mica they are rifted, or split. In the U.S. a straight-bladed knife is generally used for rifting. Products of this operation are classed broadly as untrimmed sheet mica and scrap. Sheet mica is any relatively flat piece sufficiently free from physical defects to be cut or stamped into specified shapes for industrial use. Sheet mica is classed as block, film, and splittings. Block mica is not less than 0.007 in. thick with a minimum usable area of 1 sq in. Film mica is split from the better qualities of block mica to groups of specified thickness ranging from 0.0012 to 0.004 in. Splittings are sheets with maximum thickness of 0.0012 in. and minimum usable area of 3/4 sq in. As virtually no mica splittings are produced in the U.S., they will not be discussed in this report. Small, low quality block is subdivided as punch and washer. Punch mica is thumb-trimmed material large enough to yield a circular disk of at least 11/2 in. diam for stained quality mica and 1 1/4 to 2 in. for clear quality. Poorer lots, often referred to as washer mica, are also included in the general term punch mica. Trimming, the next step in processing sheet mica, removes broken and ragged edges, loose scales, and other major imperfections. Trimming may be done with a knife, sickle, shears, or fingers. In the U.S. it is usually done with a 3-in. linoleum knife to obtain a bevel-edged cut. If ragged edges are broken off with the thumb and fingers, the mica is called thumb-trimmed. Full-trimmed is rifted mica trimmed on all sides with all cracks, reeves, and

Jan 1, 1957

By C. W. Schultz, R. B. Tippin

Statistical screening is so named because a particulate feed is separated into "size" intervals on the basis of the probabalistic behavior of the individual particles (i.e., their probability of passing the screen) rather than by physical restraint. To illustrate this statement, consider a conventional screening operation. A particle which is larger than the openings in the screen cloth is physically restrained from passing through and is repeatedly reflected from the surface until it is discharged as oversize. Of those particles smaller than the screen openings, the very smallest tend to pass the screen near the feed end while those nearer in size to the screen opening tend to pass at a greater distance from the feed end. Alternatively, we could say that the particles with high probability of passing through the screen are concentrated near the feed end while particles of low probability of passing are dispersed from the feed end. This tendency to segregate is the basis for size separation by statistical screening. The purpose of this note is to: 1) Show that the distribution of material passing an array of screens can be described by a modified binomial distribution. 2) Demonstrate that an efficient size separation can be made by this technique. 3) Relate some of the more important screening parameters to the efficiency of the size separation. The Distribution Function The distribution of undersize products along the length of a screen can be derived with the help of a few simple definitions and assumptions. 1) First, we must assume that each particle has some probability of passing a screen on a single presentation. Further, we must assume that this probability is constant and is not affected by the position of the particle on the screen. It must also be acknowledged that several factors enter into this probability. Among them are the "action" of the screen, the slope of the deck, the shape of the openings, etc. The relationship between these factors, however. is not the subject of this paper. 2) To simplify calculations, all particles falling within a size range on the Tyler scale, e.g., —x + x/ mm, are assumed to have the same probability. 3) It is assumed that particles which do not pass the screen on a presentation are reflected a unit distance forward, i.e., the direction of material travel. A unit distance is defined as the distance between the centers of consecutive wires in the screen cloth.

Jan 1, 1971

By H. E. Howe, A. A. Smith

The creep properties of lead alloys have been studied by a number of investigators but most of the work has been done on extruded material and the amount of data available on rolled alloys is surprisingly limited. Greenwood1 and his collaborators investigated various rolled commercial leads containing relatively small amounts of impurities, Phillips2 likewise studied rolled commercial leads, although he did include a few alloys— such as tellurium lead and one per cent antimonial lead. But as far as the authors are aware no data on the creep properties of so-called "hard leads"-—i.e., containing from 4 to 8 per cent antimony—have been published. In this paper some data are presented on a few antimonial lead alloys and compared with a copper-bearing lead. Preparation OF Specimens All the alloys used in this investigation were cast at a temperature of 400°C. into an open cast-iron mold preheated to Ioo°C., the resultant casting being % by I by 10 in. The copper-bearing alloy was cold-rolled by 10 per cent passes to a thickness of 0.100 in. Creep specimens 16 in. long were prepared by clamping the strips between wooden blocks and machining the edges of the strips parallel by means of a plane. Careful manipulation gave parallel specimens with no reduced section and with a minimum of distortion. The antimonial lead castings were hot-rolled in 10 per cent passes at a temperature of I50°C. to a thickness of 0.400 in., the heating being carried out in an electric oven after each pass through the rolls. After the castings had been broken down to 0.400 in., they were allowed to cool to room temperature and then cold-rolled to 0.100 in. with the usual Io per cent passes. Sufficient time was allowed after each pass for the strips to cool to room temperature. The apparatus and method of measuring strain have been adequately described in a previous paper3 and essentially the same practice was used in obtaining the present data. Time-extension curves for only two alloys are given, since these are typical of all. Figs. I and 2 show the time-extension Curves for the copper-bearing alloy A at 30°C. and loo°C., and Figs. 3 and 4 show

Jan 1, 1945

By David A. Keys

The actual procedure in estimating depth of overburden from magnetic observations made on the surface will vary with the form of the deposit and any theoretical discussion will apply only so far as the form of the deposit conforms to the mathematical premises on which the theory is based. Since the shapes of natural deposits in the field cannot be expressed rigorously in mathematical form, the best that can be done is to assume some simple form and deduce results. Fortunately many small variations in form produce only slight changes in the estimated depth of overburden, therefore the methods have a definite practical value. For the theoretical treatment, magnetic ore deposits may be divided roughly into three classes, depending upon whether the magnetic anomalies may be considered to arise from (1) a single magnetic pole, (2) a dike or (3) a magnetic doublet. Particular cases, falling under one or other of these classes, have been discussed by different authors.1"4 In general, it may be stated that when the magnetic effects as measured on the surface are due only to one pole of the body, the other pole being so remote that its effect may be neglected, the resultant anomaly F at any point will vary as the inverse square of the distance r of the point from the pole, which may be expressed mathematically by F = k/r2, where k is a constant. When the deposit occurs in the form of a long, thin dike, the resultant anomaly will be of the form F = k'/r and when the deposit is in the shape of a lens, so that both poles have an appreciable effect on the surface, the result will be similar to that caused by a magnetic doublet, and the form will be F = k'/r3. The particular class under which a deposit falls may be deduced from the results of the magnetic survey. The second class is readily found, but there may be difficulty in deciding between the first and third. Isody-namic contours of both the vertical and horizontal anomalies will often be a good guide in making a correct decision. The correctness of the theoretical calculations may be checked in two ways. The first is to make laboratory models of various known shapes and pole distributions, to calculate the anomalies to be expected

Jan 1, 1940

By David A. Keys

The actual procedure in estimating depth of overburden from magnetic observations made on the surface will vary with the form of the deposit and any theoretical discussion will apply only so far as the form of the deposit conforms to the mathematical premises on which the theory is based. Since the shapes of natural deposits in the field cannot be expressed rigorously in mathematical form, the best that can be done is to assume some simple form and deduce results. Fortunately many small variations in form produce only slight changes in the estimated depth of overburden, therefore the methods have a definite practical value. For the theoretical treatment, magnetic ore deposits may be divided roughly into three classes, depending upon whether the magnetic anomalies may be considered to arise from (1) a single magnetic pole, (2) a dike or (3) a magnetic doublet. Particular cases, falling under one or other of these classes, have been discussed by different authors.1"4 In general, it may be stated that when the magnetic effects as measured on the surface are due only to one pole of the body, the other pole being so remote that its effect may be neglected, the resultant anomaly F at any point will vary as the inverse square of the distance r of the point from the pole, which may be expressed mathematically by F = k/r2, where k is a constant. When the deposit occurs in the form of a long, thin dike, the resultant anomaly will be of the form F = k'/r and when the deposit is in the shape of a lens, so that both poles have an appreciable effect on the surface, the result will be similar to that caused by a magnetic doublet, and the form will be F = k'/r3. The particular class under which a deposit falls may be deduced from the results of the magnetic survey. The second class is readily found, but there may be difficulty in deciding between the first and third. Isody-namic contours of both the vertical and horizontal anomalies will often be a good guide in making a correct decision. The correctness of the theoretical calculations may be checked in two ways. The first is to make laboratory models of various known shapes and pole distributions, to calculate the anomalies to be expected

Jan 1, 1940

By R. F. Mehl, W. Batz, C. Wells

Diffusion coefficient values for carbon in austenite covering a wide range of temperature and composition have been determined employing statistical methods. In addition, the relation between concentration and each of the following, D (diffusion coefficient), Q (activation heat of diffusion), and A (the constant in the diffusion equation), has been obtained. A study of the rates of diffusion of austenite was published in Metals Technology in 1940.' The present investigation is an extension of the earlier work, undertaken (1) to obtain values of the coefficient of diffusion, D, over a much wider range of carbon concentration, and (2) to provide data in all ranges of concentration and temperature in such abundance that statistical methods could be employed to evaluate the accuracy of the data with unusual precision. Composition of Materials: Composition of materials used in this research program are listed in table I. These materials, all forged to about 1 1/4 in. rounds, consist of a high-purity iron, Armco iron, a large number of laboratory-made plain carbon steels containing amounts of impurities normally expected in high-quality commercial steels, and three silicon steels. Since it was known at the time these steels were being made that impurities in the amounts present were unlikely to affect carbon diffusion rates' significantly, the effort made to obtain high-purity steels was not as persistent as it otherwise would have been. Procedure: In general, the procedure followed by Wells and Mehl and described' in detail in an earlier publication' is the one used by the present authors. However, certain modifications have been made which it is believed allow diffusion data to be interpreted more objectively and correctly. These are described completely under appropriate subheadings which follow. Experimental Procedure: Experimental procedure includes (1) the preparation of specimens by welding steels of different carbon contents, (2) the heating of these for certain times at selected temperatures in order to diffuse carbon along the specimens across the welded "interface," and (3) the determination of the carbon distribution across the diffusion zone. Preparation of Specimens: Prior to welding steel of one carbon content to iron or steel of another carbon content, surfaces to be welded are machined perpendicular to the longitudinal axis of cylinders which are about 3/4 in. in diam and 1 1/2 in. long. The prepared, flat, parallel surfaces are brought together and butt-welded electrically. Evidence of a good weld is given in fig. 1. Welding temperature

Jan 1, 1951

By W. G. Woolf, E. R. Crutcher

The electrolytic zinc plant of the Sullivan Mining Co. is in Government Gulch, at Silver King, Shoshone County, Idaho, in the Coeur d'Alene mining district, about one mile from the Bunker Hill smelter and about three miles from Kellogg. The Sullivan Mining Co., which owns both the zinc plant and the Star mine, is itself owned jointly by the Bunker Hill & Sullivan Mining & Concentrating Co, and the Hecla Mining Company. The Tainton high-density, high-acid process is used at this plant, therefore some parts of its flowsheet differ markedly from those of electrolytic plants using the low-density process. While it is a custom plant and has treated a variety of zinc concentrates originating from various sources in a number of states, it has obtained its main supply of zinc concentrates chiefly from the zinc-bearing ores of the Coeur d'A1ene mining district, of which the principal important sources have been the Bunker Hill and Star mines. Thus the main feed has been zinc concentrates obtained from complex lead-zinc-silver ores. For the year of 1935 the concentrates had the following composition: water, 9.5 per cent; Zn, 50.6; Pb, 3.3; Fe, 9.4; S, 31.0; Cu, 0.2; insoluble, 2.9. Flowsheet The concentrates are delivered to the plant in railroad cars, which discharge into storage bins directly under the track. Bottom-dump cars are dropped directly into the bins while a slip scraper, pulled by an air tugger hoist, is used to empty box cars. There are five storage bins for concentrates, each of approximately 300 tons capacity. At the bottom of each bin there are individual belt feeders that discharge onto a common conveyor belt, which in turn discharges to another belt that carries the concentrate onto a weightometer belt for weighing. Immediately after the weighing, the crushed oversize return from the roasters is added to the load on the belt and then the ground-up sweepings, lumps and roaster cleanings. An electromagnet at the end of this conveyor removes tramp iron from the feed. The belt discharges to a set of 30 by 12-in. rolls, which break up lumps or frozen chunks of concentrate, etc. Beneath the rolls there is a screw conveyor, which conveys the roll discharge to a

Jan 1, 1937

By George C. Ference

Sulfur is the 13th most common element in the earth's crust, constituting approximately 0.05% of the total. It occurs naturally in its elemental form, as metallic sulfides, nonmetallic sulfates, and as combined or free sulfur in natural gas, crude oil, and coal. COMMERCIAL SOURCES Most of the sulfur that is consumed is converted into sulfuric acid before use; therefore, it is not necessary to recover sulfur solely in its elemental form. Processes for recovery are peculiar- to the types of reserves being processed. The major commercial processes as well as the general geographic locations where the appropriate reserves occur are listed in the following. It should be noted that the sulfur values may be recovered as the primary product, as a coproduct with other materials, or as a byproduct. Elemental Sulfur 1) Frasch mining is used for subterranean deposits of elemental sulfur around the Gulf Coast areas of the United States and Mexico. Generally, but not exclusively, such deposits are located in salt dome structure. 2) Autoclaving, flotation, or solvent extraction of surface deposits of elemental sulfur is practiced throughout the world. 3) Extraction and conversion of hydrogen sulfide from sour natural gas into elemental sulfur is done principally in Canada, France, and the United States. 4) Conversion of metallic sulfides from pyrites into elemental sulfur is done via the Outokumpu process in Finland. 5) Catalytic cracking and hydrocracking of sulfur-bearing crude oils to produce elemental sulfur is done worldwide. Desulfurization of refined petroleum products also yields elemental sulfur. 6) Recovery of elemental sulfur from sulfur-bearing oil sands (Athabasca tar sands) has been initiated in Canada. 7) As of this writing (1970), a plant has been constructed for the thermal decomposition of gypsum to produce elemental sulfur in the United States. Sulfuric Acid Sulfur values in the form of sulfuric acid are recovered via: 1) Recovery from smelter gases throughout the world. 2) Roasting of pyrites throughout the world with iron sinters as a byproduct. 3) Roasting of anhydrite with cement as a coproduct, primarily in Europe. 4) Processes currently are being developed for recovery of sulfuric acid from combustion gases resulting from the burning of high-sulfur-content fuel. Other Sulfur values also are recovered from waste products which normally occur in highly industrialized areas. Some examples are: coke-oven gases, sludge sulfuric acid, and pickling liquors (ferrous sulfate).

Jan 1, 1976

By H. R. Drullard

TO obtain the best results from hammer drills, close attention must be paid to two factors in drill maintenance, which are of equal importance; one is lubrication, the other is the shank. With the exception of stoping drills, most modern rock drills require both oil and grease. The oil ports are in the lubricator, on or behind the hammer cylinder; the grease port for the lubrication of the chuck sleeve and rotating mechanism is on the chuck end. Ordinary machine oil is not adapted to rock drills; a heavier more gelatinous oil such as castor machine oil or liquid grease should be used. The lubricators should be filled once for every 12 or 14 ft. (3.5 to 4 m.) of hole drilled. Grease guns should be used to fill the port in the chuck end once a shift; a medium (No. 3) grease is well adapted to this purpose. Hard grease must not be put into the lubricators, as it will not flow through that part. Contrary to the popular belief, oiling a machine once or twice a shift does not provide sufficient lubrication; the drills should be oiled once for every 12 or 14 ft. of hole drilled. The rotating handle of a stoping drill is an oil reservoir and is provided with a port for oiling. The rotating handle is packed with wick-ing, or similar material, which causes the oil to feed slowly from the handle to the other parts of the machine. Stoping drills require oil at least twice a shift; lighter oils than castor, such as Arctic Ammonia, may be used. Drills used in shaft sinking can be oiled satisfactorily by placing a good-sized, drop, sight lubricator on the station above the sinking operations and connecting it with the air-line supplying the sinking drills. If this lubricator is properly filled and adjusted, a uniform oiling of the sinking machines will be effected without the necessity of oiling the drills individually. The grease end should be filled at the station or surface before each drilling period. The shift boss should see that the machines are greased and also that the lubricators at the station function properly. The life of the air-drill hose is somewhat shortened by this method, as oil attacks the inner tube; but as some oil is always present in the compressed air, this is not a serious objection to the method.

Jan 1, 1922

By George Watkin Evans

The need for mechanization in coal mining wherever it can be successfully introduced is evident when we take into account the fact that during recent years the coal-mine employee's wages have increased and his hours have been shortened. Coal is no longer King, and a brief study of statistics covering the production of coal, petroleum and natural gas and the development of water power will convince anyone that coal has had very powerful competitors during the past 10 years. Petroleum production in the United States between 1918 and 1936 increased from 100 per cent to 309 per cent. Water power increased from 100 per cent in 1918 to 270 per cent in 1936. Bituminous coal slipped from 100 per cent in 1918 to 75 per cent in 1936. The anthracite industry slipped from 100 per cent in 1918 to 50 per cent in 1932, but climbed to 55 per cent in 1936. In 1918, the State of Washington produced a little over four million tons of coal and the production of California oil, at that time, was a little less than one hundred million barrels per year. By 1929 the production of California oil had increased to a little over 292,000,000 bbl. or nearly 300 per cent as compared with 1918. By 1934 the production of coal in the state of Washington had dropped to about 1 1/3 millions of tons per year. Our neighbors in British Columbia had their coal production reduced from a little over 2 1/2 million tons in 1920 to less than 1 1/3 million in 1933. The North western Improvement Co., a subsidiary of the Northern Pacific Railroad Co., owns coal properties in various parts of Washington and Montana. The Northern Pacific is one of the very few railroads using any considerable quantity of coal in its operations. Practically all of the American railroads in the Pacific Northwest, except the Northern Pacific, are using cheap California fuel oil or electricity. This problem, of course, is not a new one in coal mining, and all of the progressive coal companies in the country have tried to meet competition from an overproduction of petroleum and an overproduction of natural gas as well as enlarged developments of hydroelectric plants.

Jan 1, 1938

By C. Ernest Birchenall, Gerd M. Rosenblatt

The pressure and molecular weight of the antimony vapor over solid solutions of tin in antimony, containing 97.4, 94.9, 93.0, and 90.7 at. pct Sb, have been measured from 445° to 545°C by the torsion-effision method. The vapor is all Sb, within experimental error. A solidus curve which differs somewhat from the accepted curve has been calculated using the measured antimony activities. Metallographic examination of additional annealed alloys substantiates the accepted solidus. The solid solutions, which show negative deviations from ideality, probably do not deviate greatly from regular solution behavior. HANSEN' considers the Sb-Sn phase diagram to be well established with the exception of the boundary of the (Sb) phase.* Although there have been no pre- Their data can be combined with data for the solid alloys to calculate the solidus curve of the (Sb) phase. This paper presents measurements of the pressure ant1 molecular weight of antimony over Sb-Sn solid solutions containing 97.4, 94.9, 93.0, and 90.7 at. pct sb. Measurements were made by simultaneous use of the volmer3 torsion and Knudsen, effusion methods. The results of these measurements have been combined with the vapor pressure of pure antimony5 to obtain the activity of antimony in the primary solid solutions. The solidus curve calculated from these data differs somewhat from the accepted curve and is rather uncertain. Metallographic examination of Sb-Sn alloys was carried out to clarify the position of the solidus of the (Sb) phase. EXPERIMENTAL The apparatus and technique have been described previously.5 The measurements were made with the same effusion cells and torsion wire used in the measurements on pure antimony. The torsion measurements were calibrated with mercury at 30" using a mercury vapor pressure of 2.96 x 10-3 mm Hg determined by concurrent, absolute, weight-loss experiments. As in the measurements on pure antimony, an extraneous vapor was observed to distill off during the first run after the cell had been loaded with A fresh sample of alloy and during the first minute or two of every run. The change in composition after a series of runs with one sample was of the order of 0.1 at. pct and thus completely negligible in the calculation of the thermodynamic properties. The alloys were prepared from pieces of Merck antimony and Matheson, Coleman, and Bell reagent-

Jan 1, 1962

By George Watkin Evans

The need for mechanization in coal mining wherever it can be successfully introduced is evident when we take into account the fact that during recent years the coal-mine employee's wages have increased and his hours have been shortened. Coal is no longer King, and a brief study of statistics covering the production of coal, petroleum and natural gas and the development of water power will convince anyone that coal has had very powerful competitors during the past 10 years. Petroleum production in the United States between 1918 and 1936 increased from 100 per cent to 309 per cent. Water power increased from 100 per cent in 1918 to 270 per cent in 1936. Bituminous coal slipped from 100 per cent in 1918 to 75 per cent in 1936. The anthracite industry slipped from 100 per cent in 1918 to 50 per cent in 1932, but climbed to 55 per cent in 1936. In 1918, the State of Washington produced a little over four million tons of coal and the production of California oil, at that time, was a little less than one hundred million barrels per year. By 1929 the production of California oil had increased to a little over 292,000,000 bbl. or nearly 300 per cent as compared with 1918. By 1934 the production of coal in the state of Washington had dropped to about 1 1/3 millions of tons per year. Our neighbors in British Columbia had their coal production reduced from a little over 2 1/2 million tons in 1920 to less than 1 1/3 million in 1933. The North western Improvement Co., a subsidiary of the Northern Pacific Railroad Co., owns coal properties in various parts of Washington and Montana. The Northern Pacific is one of the very few railroads using any considerable quantity of coal in its operations. Practically all of the American railroads in the Pacific Northwest, except the Northern Pacific, are using cheap California fuel oil or electricity. This problem, of course, is not a new one in coal mining, and all of the progressive coal companies in the country have tried to meet competition from an overproduction of petroleum and an overproduction of natural gas as well as enlarged developments of hydroelectric plants.

Jan 1, 1938

By F. E. Bash

Previous to the war, this country depended on Europe for its supply of a number of alloys of great importance in the manufacture of electrical apparatus and equipment. When this source was cut off shortly after the beginning of hostilities and the small stocks in the United States were exhausted, either inferior substitutes had to be used or the manufacture of the apparatus suspended. Since electrical equipment was of primary importance in the prosecution of the war, the substitutes had to be used until the composition and processes of manufacture of the alloys could be determined. Included among these alloys was one generally known as manganin, which is composed chiefly of copper and manganese and which, beside having a low-temperature coefficient of resistance, has a low thermal electromotive force against copper. These qualities make it valuable for the manufacture of electrical instruments and machines in which it is used in the shape of wire, rod, and strip. As a result of these circumstances, an investigation was started to determine how manganin could be made on a commercial basis so that a product of uniform quality and the necessary electrical characteristics could be produced. The object was to procure an alloy with temperature coefficient of resistance not greater than 1 X 1X per " C. and a thermal e.m.f. against copper no greater than that of the imported material. It is characteristic of manganin that the temperature-resistance curve is not a straight line but has a peak, which varies in position with different samples; it is most desirable, however, to have it at a temperature of 25' C. if possible. The coefficients of manganin from all records available ranged from a large negative to a large positive value. The composition as reported by different authorities is given in Table I. Prof. Matthew A. Hunter, of Rensselaer Polytechnic Institute, made up a number of small melts of manganin in a graphite crucible and the one that he reported as having the best cocfficient gave the following analysis: Copper, 83.6 per cent.; nickel 2.5 per cent.; manganese, 13.6 per cent.; iron, 0.3 per cent. An analysis of a sample of German manganin gave the following: Copper, 82.6 per cent.; nickel, 3.8 pcr cent.; manganese, 12.8 per cent.; iron 0.7 per cent.

Jan 1, 1921

By A. W. Schillinger

Drilling was not entirely satisfactory in the search for native copper in the Osceola amygdaloid footwall, for oreshoots mined were more continuous than drilling indicated. The Geophysics Dept of Michigan Technological University developed a portable induced polarization drill hole probe with a 3-electrode configuration and a sampling radius of 5 ft ±. A 20 ma current of alternately reversed polarity is pulsed at 3.5 sec intervals and readings are taken every 2 ft. Potential is read during the "on" cycle for resistivity determinations. During the "off" cycle, after 10 ms delay, the 1P potential is sampled for 10 ms and recorded. Resistivity (ohm-ft) and "S" values (mv/v) are plotted on semi-log paper. A lithologic log is plotted based on resistivity and anomalous S values noted. The low resistivity amygdaloid contains sills of high resistivity basalt. Verified by core logs, contacts between amygdaloid and basalt could be picked to ± 0.5 ft from resistivity alone. Lithologic logs of long-steel holes, based on resistivity, then replaced sludge logging. An S value of 30 mv/v was established as the lower limit of diagnostic 1P effects in mineralized amygdaloid and 50 mv/v as a threshold value for ore. Of 914 footwall zones drilled, 315 were probed yielding 203 anomalies. Success increased from 34% for drilling to 72% for drilling and probing. As checked by mining, 46 probe results were 78% correct. Failures were due to the instrument not detecting copper or to the misinterpretation of an anomaly. No false anomalies were found. During the past ten years, the Calumet Div. of Calumet &Hecla, Inc has conducted extensive exploration and mining in the footwall of the Osceola amygdaloid lode in the native copper district in Michigan's Upper Peninsula. In an attempt to delineate more clearly the extent and nature of high-grade footwall copper mineralization, 876 diamond drill and long steel holes aggregating slightly more than 47,000 ft have thus far been drilled from the accessible hanging-wall workings in the Osceola No. 6, 13, 14 and 15 shafts. Early in this program it became obvious, through inspection of footwall workings in progress, that due to the erratic and bunchy occurrence of the native copper in the footwall zone, the exploration drilling was failing to outline completely the extent of the oreshoots. Early drilling re-

Jan 1, 1964

By Charles Legrand

In many iron, coal and copper mines where large tonnages are known before starting operation and proper provisions can be made, the problems of electric traction by trolley locomotives are not very different from those of surface plants. In such installations the gauge of the track, the radius of curves, and the clearances, both vertical and horizontal, can be made to suit the conditions of the traffic. It is more difficult to install electric traction in mines which were started with hand tramming and where no consideration was given to the possibility of mechanical traction being used. The writer having had some experience in the installation of electric traction in copper mines, the following remarks apply more particularly to these mines. With the gauge of track usually 18 or 20 in., the weight limit of locomotives obtainable from manufacturers in this country varies from 3 to 6 tons. The full-load speed varies from 49 to 6 miles per hour. These locomotives, being made to run on very small radius curves, have a short wheel base and a long overhang from axle to coupling, which necessitates a coupling' with a good deal of lateral motion to avoid derailing the cars on sharp curves, especially if couplings are of the standard railroad automatic type. Although 3-ton locomotives will run on 12- or 16-lb. rails, it has been found more satisfactory to use 25-lb. rails, as the track keeps in much better shape, it is easier to maintain the bonding in good order, and fewer derailments from dirt on the track occur with the larger rails. Where 6-ton locomotives are used the 25-lb. rails are satisfactory, but 40-lb. rails have proved cheaper where the traffic is heavy and the ground is soft, as the track maintenance is considerably lower with the heavy rails. The locomotives will run on 15-ft. radius curves, but on through runs it is advisable not to go below 40-ft. radius. The voltage used should not exceed 250 to 275 volts, and the trolley wire should be protected, to prevent accidental contacts, in front of chutes and at all points where it is low. With the air lacking somewhat in oxygen and the heat and high humidity prevalent in many mines, this

Jan 1, 1915

NAME AND OBJECT. SEC. 1. This Institute is incorporated under the Membership Corporation Law of the State of New York ; its corporate name is AMERICAN INSTITUTE OF MINING ENGINEERS; and its objects are such as are stated in its Certificate of Incorporation. ARTICLE II. MEMBERS. SEC. 1. The membership of the Institute shall comprise four classes, namely (1) Members ; (2) Honorary Members , (3) Associates , and (4) Honorary Associates Only Members and Associates residing within the United States of America, Republic of Mexico and Dominion of Canada shall be entitled to vote at the meetings of the Institute. SEC. 2 All Members, Honorary Members, Associates and Honorary Associates of the American Institute of Mining Engineers as the same existed on the day of the incorporation of this Institute, are Members, Honorary Members, Associates and Honorary Associates, respectively, of this Corporation SEC. 3. The following classes of persons shall be eligible for membership in the Institute, namely, as Members and Honorary Members, all professional mining engineers, geologists, metallurgists or chemists, and all persons practically engaged in mining, metallurgy or metallurgical engineering ; as Associates and Honorary Associates, all persons desirous of being connected with the Institute who, in the opinion of the Council, are suitable. SEC 4. Every candidate for election as a Member or Associate of the Institute must be proposed for election by at least three Members or Associates; must be approved by the Committee on Membership, as prescribed in the By-Laws ; and .must be elected by the Council. Not less than three-fourths of the votes cast shall be necessary to an election Every person so elected shall become a Member or Associate, as the case may be, upon payment of his first dues as herein-after prescribed Each candidate for Honorary Member or Honorary Associate, must be recommended by at least ten Members or Associates ; must be approved by the Council ; and must be elected by ballot at a meeting of the Board of Directors by the unanimous vote of all the Directors present ; provided, however, that the number of Honorary Members and Honorary Associates shall not at any time exceed twenty SEC. 5. If any person elected a Member or Associate does not, within sixty days after notice of his election, accept the same and pay his initiation fee and dues for the current year, his election may be cancelled at the discretion of the Council.

Jan 1, 1910

History of Production, of Salt Creek Oil Field, Wyoming Discussion of the paper of EDWARD L. ESTASROOK and CLARENCE M. RADER, presented at the Casper Meeting of the Petroleum Division and issued, as Paper No. 1503-G, with MINING AND METALLURGY, September, 1925. C. E. REISTLE, Laramie, Wyo.-The application of water analysis to petroleum engineering problems is successful in many cases, particularly if the water in the sands is of uniform chemical constituency and if each sand water varies definitely from the others in its chemical properties. At Salt Creek, the sand waters are not of uniform chemical character, and the waters in the various sands do not differ greatly; so a water from one sand might easily be classified as a water from some other sand. The water from the Shannon sand contains sulfates; this alone makes it possible to differentiate between the Shannon and the First and Second Wall Creek and Lakota sands. However, it is not so easy to differentiate between water of the First and Second Wall Creek sands. As a rule, the Second Wall Creek sand contains a higher concentration of mineral matter, but in Table 19, sample 2; of the First Wall Creek sand and sample 7 of the Second Wall Creek sand have approximately the same amount of total solids. As a rule, the chlorides are higher in the Second sand waters than in the First sand; but, the chlorides in sample 6 of the Second sand show practically the same amount as sample 3 of the First sand. The use of reaction properties does not. solve this trouble, as they generalize the conditions even more. For instance, the reaction properties of sample 3 of the First sand are almost identical with the reaction properties of sample 6, of the Second sand. The authors suggest that the chemical characteristics of the water in a sand are not uniform because of the concentration of the water by underground evaporation. In that case should not the ratio of the various chemical constituents remain the same? Gas does remove some mineral matter, as evidenced by deposits in the gas lines and packing in the absorbers of the natural gasoline plants, but why does the gas act selectively, removing one salt and not all of the salts in the ratio that they occur?

Jan 12, 1925

By D. J. McAdam, G. W. Geil, D. H. Woodard, W. D. Jenkins

INTRODUCTION IN a series of papers, the authors and their associates have shown that the resistance of a metal to fracture is a function of all three principal stresses. 10-18,20,21,23,[1] Consequently since a technical cohesion limit is defined as the technically determinable resistance to fracture, under a specific stress system, the technical cohesive strength comprises an infinite number of technical cohesion limits corresponding to the infinite number of possible combinations of the principal stresses. As shown in the previous papers, the technical cohesive strength increases with plastic deformation, with decrease in temperature, and with increase in the strain rate. The technical cohesion limit, therefore, is affected by the same factors that affect the flow stress,§ namely, the stress system, plastic deformation, temperature, and the strain rate. The effect of each of these factors on the fracture stress is qualitatively the same as its effect on the flow stress. The effect of any of the factors may be represented by a curve of cohesion limits, although only one point on the curve may represent actual fracture. Since the term "fracture stress" has come into general use with the same significance as technical cohesion limit; the authors are here using the' shorter term with the understanding that it, does not always refer to actual fracture. In the general investigation described. in the previously-mentioned papers,10-18,20,21,23 the influence of the stress 'system on the fracture stress was studied by means, of tension tests of notched specimens. When a circumferentially notched cylindrical' specimen is subjected to longitudinal ten-, sion, the minimum cross section is under " transverse radial tension. The mean radial stress increases with the depth and sharpness of the notch, but is always less than the longitudinal stress. The greatest principal stress (S,), therefore, is longitudinal, and since the radial stress is effectively equal to the circumferential stress, the transverse principal stresses are equiaxial in that plane (S2 = S3). By the use of notched specimens in tension tests it was shown that the fracture stress increases with increase in the radial stress ratio (S3/SI). The evidence is based not only on the results of tests to fracture at various constant temperatures, but also on. results of two-stage tests, in which each specimen was plastically deformed a predetermined

Jan 1, 1948

US 4,135,913-Extraction of nickel values from iron-containing nickel sulfide ore, particularly pentlandite or nickeliferous pyrrhotite A mixture of raw ore, roasted ore, or iron powder, and coal as a reductant is heated to a temperature of 800- 1000° C in a nonoxidizing atmosphere to convert the bulk of the iron content to metallic iron while diffusing into the iron the bulk of the nickel, the mixture cooled, and the cool material separated into a magnetic fraction containing most of the nickel and a non-magnetic gangue fraction A Illis arid L S Renzoni, assigned to International Nickel Co, Inc Jan 23, 1979 7 pp (75-21) Filed 10-10-75 (621,343) Priority Canada, 10-27-72 (155,032) Same Canadian 981,910, dated Jan 20, 1976 Same British 1,389,145, dated Apr 3, 1975 US 4,135,917-In the recovery of gallium from a solution obtained by the digestion of bauxite or nepheline in an alkali solution for the production of alumina, the digestion solution is neutralized, the neutralized solution evaporated to an op¬timum caustic alkali concentration and adjusted to a ratio of alkali metal oxide to alumina of above 2, the corrected solu¬tion contacted with a gallium-aluminum alloy, arid high-purity gallium recovered from the solution by electrolysis or cemen¬tation K A Badaliants, et al Jan 23, 1979 6 pp (75-109) Filed 12-19-77 (862,201) Priority USSR, 12-22-76 (2,428,¬006) US 4,135,918-Extraction of copper from copper sulfide ore containing also one or more of the metals iron, nickel, arid cobalt Ore is roasted at a temperature of 750-800° C to expel sulfur, the sulfur-free calcine slurried in water containing a sufficient amount of sulfuric acid to supplement any sulfuric acid formed in situ, the slurry heated at 150-165° C in the presence of a reducing gas to form soluble sulfates of metals other than copper while reducing copper to elemental form, arid the slurry filtered to recover copper solids Any precious metals present in the ore will report with the copper solids V A Ettel, A P Devuyst, R Sridhar, arid C. E O'Neill, as¬signed to International Nickel Co, Inc Jan 23, 1979 5 pp (75-117) Filed 3-2-78 (882,610) Priority Canada, 5-13-77 (278,360)

Jan 1, 1980

By R. D. Carnahan, J. E. White

ThE use of strain gages in the measurement of microplastic behavior of materials is well-known.'-3 Recently it has been suggested that similar techniques might be useful for determining stress relaation. It is the purpose of this report to comment on the use of strain gages in the measurement of strains in the vicinity of 10"6. We will also discuss observations of an anomalous anelastic behavior apparently associated with small temperature changes, which accompanies the unload portion of a load-unload microstrain test. The key to successful strain determinations at levels below 1 pin. per in. is a good gage-mounting technique and either precise ambient temperature control or a set of matched temperature-compensated gages. The importance of good mounting cannot be overemphasized, for example, as in the use of Eastman 910 contact cement. If the cement layer is not sufficiently thin and properly hardened, it is possible to observe anomalous negative stresses when small loads are removed, which relax back to zero in an orderly way with time. Such anomalous behavior, thought to be due to gage bonding, has been reported in microstrain experiments by Thomas and verbach' who observed a negative strain of -3 X lo-' upon unloading. This kind of behavior severely limits the over-all strain sensitivity which can be achieved in such tests. The relaxation of a small positive strain subsequent to unloading in a load-unload experiment is quite normal, however, and is to be expected. The occurrence of an apparent negative strain is also encountered in those instances where the elasticity of the bonding cement is exceeded—for example 0.5 pct or 5000 pin. for cured Eastman 910. An elastic strain of this magnitude can be encountered during load-unload type testing particularly in higher-strength materials (-150,000 yield strength). During the course of microplasticity studies on pure nickel and nickel alloys,' the authors have made the following observation. In a four-point bending test, two active gages are mounted one on each side of the beam as arms R1 and R z of a conventional strain-gage bridge circuit shown in Fig. l(a). This technique provides two advantages: the sensitivity is doubled because R1 and Rz experience opposite strains and temperature compensation is provided automatically because any ambient temperature change would cause both gages to see a strain of like sign whose signals would cancel in the circuit.

Jan 1, 1964