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By Harry L. McNeill

The Selective Media Process was developed by the author in a laboratory provided by The Steams-Roger Manufacturing Co. It is the outcome of an investigation into the possibilities of coarse beneficiation by sink and float without using the conventional heavy media. Commercial work to date has been limited to the treatment of minus 3/8-in. iron ore at the Hill Trumbull washing plant of the Cleveland Clifis Iron Co., at Calumet, Minnesota. Two cut away prints of the machine are shown (Figs. I and 2). A rotary conical impeller is mounted within a stationary cone (Fig. 2). This impeller is adjustable vertically by a 12-ton screw jack. The speed of the impeller can be varied from 14 to 32 r.p.m. by the Reeves variable-speed motor pulley mounted on the 7½-hp. motor drive. Attached to the bottom of the stationary cone is the automatic control valve for sink product, actuated by a ¼-hp. gear motor. The sink product is dewatered in a conventional drag driven by a 7½-hp. motor and discharged onto an inclined conveyor containing from 6 to 10 per cent moisture. Two plants are operated at the Hill Trumbull property. All the ore is first treated in a typical washing plant (Fig. 3). when treating "wash ore" a finished concentrate can be produced by the log washers and Akins classifiers, as the separation involves only fine silica (minus 48-mesh) and free iron. However, when "jig ore" is led to the washing plant the coarse

Jan 1, 1947

By Harry L. McNeill

The Selective Media Process was developed by the author in a laboratory provided by The Steams-Roger Manufacturing Co. It is the outcome of an investigation into the possibilities of coarse beneficiation by sink and float without using the conventional heavy media. Commercial work to date has been limited to the treatment of minus 3/8-in. iron ore at the Hill Trumbull washing plant of the Cleveland Clifis Iron Co., at Calumet, Minnesota. Two cut away prints of the machine are shown (Figs. I and 2). A rotary conical impeller is mounted within a stationary cone (Fig. 2). This impeller is adjustable vertically by a 12-ton screw jack. The speed of the impeller can be varied from 14 to 32 r.p.m. by the Reeves variable-speed motor pulley mounted on the 7½-hp. motor drive. Attached to the bottom of the stationary cone is the automatic control valve for sink product, actuated by a ¼-hp. gear motor. The sink product is dewatered in a conventional drag driven by a 7½-hp. motor and discharged onto an inclined conveyor containing from 6 to 10 per cent moisture. Two plants are operated at the Hill Trumbull property. All the ore is first treated in a typical washing plant (Fig. 3). when treating "wash ore" a finished concentrate can be produced by the log washers and Akins classifiers, as the separation involves only fine silica (minus 48-mesh) and free iron. However, when "jig ore" is led to the washing plant the coarse

Jan 1, 1947

By Fun-Den Wang

An open pit rock structure usually contains geological planes of weakness. They are formed by joints, faults, bedding planes, fractures, and cleavages. Rock slope failures often occur in the form of sliding of rock blocks along a plane or several planes. Such a rock block has three- dimensional geometry, and consequently a vector method of analysis has been found useful in evaluating its stabi1ity.l-3 Rock blocks of a tetrahedral shape with one free surface have been analyzed by Londe.3 Rock blocks formed by sets of parallel joints have been analyzed by Wittke.1,2 The present chapter presents the analysis of rock blocks formed by planes of weakness of arbitrary orientation, and of three-dimensional geometry. A plane of weakness is represented by its dip and strike in vector form and is reduced to the form of a linear equation. The geometry of the rock block is defined by solving the linear equations. The geometric characteristics of a rock block are based on triangles and tetrahedrons. By this treatment, the three-dimensional geometry is simplified and the number of calculations of forces and moments is reduced. Methods of finding the geometric characteristics are presented, along with equations for calculating the resultant forces and moments and the factor of safety. BASIC ASSUMPTIONS The following assumptions are used : The solid part of the rock mass is much stronger than the rock mass at the plane of weakness and the rock mass will only fail along planes of weakness.

Jan 1, 1972

By Frederic P. Dewey

The improvement in leaching introduced by the Russell process has stimulated the development of processes for refining lixiviation-sulphides. In the early days several processes for dealing with the sulphides were proposed, and some of them were tried more or less ; but the business finally settled down to sending the sulphides to the smelters, although this was known to be both troublesome and expensive. In 1891 Mr. C. A. Stetefeldt* introduced at the Marsac mill, Park City, Utah, an unpatented process, built up out of the general fund of information available. It consisted in matting the sulphides, grinding, roasting, grinding again, and dissolving the copper out in diluted sulphuric acid, then melting the silver and crystallizing the bluestone. It did not yield fine bullion, hence the bullion had to be refined as well as parted; besides, there was some loss. This process was thoroughly tried at the Marsac refinery and then a year's run was made, the net result of which was that it did not prove sufficiently better than the sending of the sulphides to the smelters to warrant its substitution for that practice. In 1893 the Dewey-Walter Refining Company undertook the refining of the Daly sulphides in the Marsac refinery by the sulphuric acid process, upon which two United States patents ? have been issued to the writer. Naturally, difficulties were encountered in starting a new process, and most of 1893 was taken up in getting it into smooth working order; but in 1894 a run was started, in which all the regular sulphides produced by the

Jan 1, 1897

By L. C. Weiner

THIS study was undertaken to round out an investigation on the effects of solid environments on the brittle fracture of zinc single crystals.' In the previous work it was demonstrated that the presence of a surface film increased the cleavage strength of crystals whose basal planes were oriented almost parallel to the tensile axis by some 43 pct. This increase was observed to be independent of the type of surface-coating material, as well as of thickness of film above a certain small critical value (about 200 to 300A). These observations were described sat- isfactorily by a dislocation-pile-up-at-a-barrier model of brittle fracture2 in which twins modifying the dislocation path act as barriers, their increase in number and homogeneity of distribution brought about by the presence of the surface film. From previous work reported on the strength of ductile metal crystals as affected by gaseous and liquid environments,3 it may be concluded that the effects of these media are present only when the environment produces a surface film on the initially clean-surfaced crystal, or when it has a disintegrating effect on a previously existing surface layer. Similarly, it might be expected that an increase in cleavage strength of initially clean zinc crystals (xo = 3", A, - 28") will result only when the gas or liquid reacts with the crystal to produce a solid, adherent surface film. Clean-surfaced crystals,l 2 1/12 in. in length, were tested in tension at room temperature in an Instron

Jan 1, 1959

By Joseph B. Umpleby

WHEN the Cushing field flooded the oil market in 1914 and 1915 with a daily output equal to nearly one-third of the world's production, the situation was soon corrected by increased consumption, and the price of crude oil rose from 45 c. per barrel in, February 1915 to $1.10 in December of the same year-the highest price paid in the Mid-Continent field up to that time. The intensive search for oil during the following seven years failed to disclose a single new ,field equal to Cushing, and many observers concluded that the rapidly increasing number of wells contributing to the world's output, each declining roughly 20 per cent. a year, combined with the rapidly increasing con¬sumption of petroleum, made it highly improbable that any field would; be found again sufficiently large to seri¬ously affect the oil market. That seven exceptional fields should then be discovered simultaneously is a remarkable coincidence. Long Beach, Santa Fe Springs, and Powell, each exceeded Cushing in daily output and reached the apex of their production during a year when Burbank, Tonkawa, - Smackover and Huntington Beach each contributed several times the daily output of the average new pool. This unexpected and tremendous flood of flush production could only have the effect of depressing price and greatly adding to stocks throughout the country. It was particularly depressing in the Mid-Continent as the new oil from California proved of attractive refining grade and because of cheap transportation by water easily undersold Oklahoma crude in the eastern markets.

Jan 1, 1924

By B. Ladanyi, B. Hoyaux

A first requirement for assessing the safety of a rock slope, either artificial or natural, particularly if the rock behaves in an elastic-brittle manner, is a propw knowledge of the distribution of stresses within the slope and their development with time and advancement of workings. There are a uumber of different methods that can be used, in principle, for obtaining this information, such as (1) stress measurement in situ, (2) photoelasticity,1 (3) analytical methods, and (4) numerical methods. In cases where the stress distribution cannot be obtained by classical analytical methods, as in the one considered herein, either photoelasticity or numerical methods are norrnally used. However, actually, due to the rapid development of high-speed computers, increasing preference is given to the numerical methods. Among the latter, the most successful ones, to date, for determining the stress distribution in slopes have been (1) the finite difference method,2-4 (2) the lumped parameter method,5 and (3) the finite element rnethod.6 However, for determining gravity stresses in a natural rock slope, only the finite difference method has been used until now.7,8 A solution of the same problem by the finite element method will be shown here in which a particular reference is given to the development of tensile fracture zones within the slope. FINITE ELEMENT METHOD The stress analysis using the finite element method originates from an extension of the matrix analysis of structures.9 It consists in decomposing a continuous medium, assumed herein to be homogeneous and isotropic,

Jan 1, 1972

By Thomas R. Scotese

A rock mechanics instrumentation and monitoring program was implemented during pillar extraction at Gulf Mineral Resources' Mt. Taylor Mine, the deepest uranium mine in the U.S. Three types of monitoring were employed: (1) drift convergence around stopes (using a portable tube extensometer), (2) stress changes in pillars (using vibrating wire stressmeters in horizontal boreholes), and (3) load changes in haulageways under stopes (using vibrating wire load cells in jack stands). Results include convergence-time graphs, convergence contour maps, stress-time graphs, a stress increase contour map, load-time graphs, and abutment load limit maps. Major factors influencing results include (1) size of pillars around the extraction area, and (2) presence and orientation of a major fault adjacent to one extraction area. These factors, combined with pillar extraction, produced evidence of load transfer over 120 m from a stope measuring only 55 m x 45 m. Vertical stress increases of 7 to 17 MPa (1000 to 2500 psi) within 60 m of the stope were obtained using the stress- meter manufacturer's method. The fault apparently prevented load transfer in the down-dip direction but increased load transfer in the up-dip direction. Convergence rates of up to 1.3 cm/day (0.5 in/day) were measured at two stations. Instruments were generally reliable despite adverse underground conditions. The instrumentation and monitoring program at Mt. Taylor provided a warning system against ground control problems and a characterization of ground behavior for future development and extraction of pillars. Recommendations are made for future mining and instrumentation practices.

Jan 1, 1984

By Robert Maddin

crystal prior to, polishing in order to eliminate coring. This treatment may be accomplished by wrapping the single crystal tightly in very thin, dead soft, brass foil and annealing in the presence of air for 20 hr at 800°C. Since the wrapping encircles the sptcimen three to four times, only a very slight amount of oxidation occurs on the specimen surface. On unwrapping one of these cylindrical single crystals. in. in diam by ro in. long (72.75 pct cu, 27.23 pct Zn, 0.01 pct P11, 0.01 pct re), mall light-gray depnrrits in the form of circular arcs werenoted on the part nf the foil which had been in contact with the single crystal, Fig r. (By superim- approximatetl). These deposits, which, from their color, suggest the appearance of sublimated zinc, were found to coincide roughly with a set of octahedral planes nearly perpendicular to the rod axis. The pattern shorn in the figure held no relation to the profle of the sample since the markin~s on the crystal More annealing werc attributed to traces of cube planes. It seems very likely that the deposits were formed by sutllimation of zinc diffusing from octahrdral planes since diffusian would Eogically take place along planes of maximum atomic spacing. However, it is difficult to understand why a continuous sublimation of zinc should occur from a single crystat in contact with a wrapping roil OF the same composition, and why diffusion would take place along specific octahedral planes and in a regular pattern.

Jan 1, 1949

By Oscar Lachmund

During the driving of the main haulage level at the Copper Mountain mines of the Canada Copper Corpn., Ltd., near Princeton, B. C., some very rapid driving was done, though no claim for a world's record is made. Conditions, however, were unfavorable for economical operations. The cost of power was high, for the fuel was of poor grade; besides, during the time the work was in progress, very little other power was needed so that most of the power cost was charged against the footage. The transmission line consisted of No. 4 galvanized iron wire with the result that the line lass was considerable. The voltage transmitted was about 30,000. The plant was operated under a lease, which was due to expire about the same time this work was supposed to be completed; an extension was refused, therefore speed was most important. The plans called for a straight adit 2900 ft. (884 m.) in length. At a point 2800 ft. (853 m.) from the portal, two raises were to be put up to the next nearest workings, a difference in elevation of about 800 ft. (243 m.). One of these was to be a two-compartment hoistway and the other a zigzag ore pass, or muck run. A location for these raises had been determined by a number of diamond-drill holes, but the material to be penetrated by the adit was not known. It seemed imperative to get the tunnel work completed as rapidly as possible, in

Jan 1, 1920

By Strathmore R. B. Cooke, Robert E. Brandt

EARLIER work1,2 has shown that the strength developed by fired magnetite pellets containing silica or silicates is due to three separate effects. Two of these are associated with the formation of slag in the interior of each pellet at temperatures above 1000°C, where the atmosphere is substantially though temporarily neutral. The third is independent of the silica content and is responsible for the development of a hard shell around the pellet during the initial stages of firing, a condition which permits the pellet to assume the increasing load of the overlying burden and prevents extrusion of the slagged and semi-liquid interior. Pellets made from hematite concentrates do not show these effects unless specific additives are incorporated, and it is these differences in behavior which in large part account for the difficulty in producing satisfactory pellets from such concentrates. Elsewhere it has been stated that "the most important factor responsible for the development of strength in fired magnetite pellets containing no additive is the oxidation of magnetite to hematite and the subsequent recrystallization and grain growth of this constituent."1 The object of the investigation reported in the present paper was to study in detail the mechanism described above and to evaluate its contribution to the strength of the fired pellet compared with other possible mechanisms, excluding slag bonding. This was effected by placing together polished faces of two cubes prepared from specific minerals and then heating them under constant pressure at different temperatures both in air and in nitrogen.

Jan 4, 1954

By H. Rush Spedden

R. T. Hukki has extended his study of ball mill grinding at supercritical speeds with an excellent mathematical analysis of tumbling mill grinding. When he speaks of supercritical speeds he is referring to the original Fahrenwald critical-speed formula. He said that, as an example of the use of supercritical speeds, if a fine grinding mill of any type is wet-grinding ore of 3.5 sp gr with steel balls at a certain conventional subcritical speed, the same power input and capacity should be obtainable with autogenous medium of 3.5 sp gr at a speed 100 to 120 pct of the critical in a grate- type mill of the same effective size. In addition, he introduced what he calls the base mill concept which, he stated, makes it possible to compare performances of mills of different sizes grinding with a metallic medium or with an autogenous medium of any specific gravity and at any speed. He showed the use of this concept and explained how it makes possible the evaluation of mill sizes and motors for any grinding purpose at any accuracy well within the conventional standards of design in milling practice. He further stated that the maximum capacity in pilot plant mills with various media, either metallic or autogenous, has always been found to be within the supercritical speed range. In his discussion of this paper he substantiated these findings with statements showing the increased capacity obtained in a milling plant in Finland which followed his principles.

Jan 7, 1960

By J. D. Raulerson, J. M. Williams

This paper presents a comparative evaluation of several system currently being used or proposed for the transport of matrix from an open-pit mine to a large fixed plant. The matrix is a sticky, wet clay to be carried from 8-16 km (3-10 miles) at 910 t/h to 1.8 kt /h (1,008-2,000 stph). The system is complicated by frequent moves of the open-pit mine site and other factors, such as use of the clay component in land reclamation.

Jan 1, 1984

By R. S. McClellan

Western Talc Company, Inc., with headquarters in Los Angeles, Calif., has just completed an extensive modernization and expansion program at its talc mine near Tecopa, Calif., and at its talc and clay mills at Dunn Siding, Calif., the nearest rail shipping point to the mine. The basic objective of the program was to provide facilities necessary to produce 300 tpd of a wide range of ground talc and clay grades for the ceramic, paint, paper, rubber and other industries. In the planning of the program every effort was made to provide a system which would permit a high degree of quality control and uniformity of the finished products, along with efficient operation. Several years ago, R. T. Vanderbilt Co., Inc. purchased Western Talc Co. after a comprehensive investigation of its properties, including an extensive diamond drilling campaign. Western Talc's properties embraced a number of claims in the Resting Springs mining district in the northern part of San Bernardino Co. and the southern part of Inyo Co., Calif., some seven miles southeast of the town of Tecopa. Operations by the original company were started on a small scale in 1913 and production from that date to the time of purchase of the company by Vanderbilt is estimated at 250,000 tons. The major part of this output was sold to the ceramic wall tile industry.

Jan 3, 1968

By C. L. Warwick, A. B. Parsons

The papers and discussion appearing in this volume were presented at a symposium jointly sponsored by the American Society for Testing Materials and the American Institute of Mining and Metallurgical Engineers and held at Philadelphia, Pa., November 29, 30, and December 1, 1944. Late in January, 1944, Lieut. Col. C. H. Greenall, Officer-in-Charge of the Laboratory Division, Frankford Arsenal, Ordnance Department, U.S.A., suggested to the American Society for Testing Materials that it might be a propitious time to arrange for a symposium on stress-corrosion cracking at the Annual Meeting of the Society in June, and agreed to make available a number of papers relating to work being carried out at that Arsenal. The Society's Committee B-5 on Copper and Copper Alloys, Cast and Wrought expressed keen interest in the symposium, and other Society committees were contacted and agreed to cooperate. Since the subject is one of primary interest also to the American Institute of Mining and Metallurgical Engineers, it was arranged that the two organizations would jointly sponsor the symposium. A Symposium Committee was formed under the joint leadership, for A.S.T.M., of Carter S. Cole, then Chief of the Metals Branch, Conservation Division, War Production Board and now Engineer on the Headquarters Staff of the Society; and, for A.I.M.E., of E. A. Anderson, Chief of Metals Section, Research Division, New Jersey Zinc Co. (of Pa.) and chairman of the Program Committee of the Institute of Metals Division. The Symposium Committee was constituted as follows:

Jan 1, 1945

By John Tyssowski

IN 1925, Harry Howard Stout, then metallurgist for Phelps Dodge Corporation, while investigating the cleaning of cathode copper by various gases at elevated temper-atures below the melting point of the metal, observed in the laboratory that particles of pure copper heated in a closed tube filled with hydrogen seemingly "stuck together." By further investigation he found that there was actual crystal growth across the boundaries of the particles of pure metal; in other words, there was a complete new crystal realignment and growth throughout the newly formed copper mass. It was coalescence, not adhesion; the several parti-cles had become one unit. From this dis-covery has been developed the coalescence process, whereby copper of cathode purity is squirted out in semifabricated form from an extrusion press, by the appli-cation of about 30c0 tons pressure on a 10-in. piston. Stout decided that cathode copper pro-duced by electrolytic deposition was the logical source of the pure copper required for the coalescence process, but as there was no way of reducing the ordinary tough commercial cathodes to the small particles required he was confronted by a serious problem at the outset. Under his direction, this problem was solved by William H, Osborn and Harry Howard Stout, Jr. They developed the process and technique for producing cathode copper in brittle, friable form, and to them must be given the greater part of the credit for this phase of the development program as well as for that relating to the gas cleaning of the cathode particles.

Jan 1, 1940

By R. Van A. Norris

The following tests were made, during 1889, for the Susquehanna Coal Company, to determine the relative efficiency of several styles of mine-car wheels in use at their collieries at Nanticoke, Pa. The wheels experimented upon may be divided into two classes: The "old style" (Figs. 1 and 2), which are oiled at every trip; and the "new style" (Figs. 3, 4, and 5), which require oiling about once in two to four months. Fig. 1 shows a section of a plain cast wheel, with patent annular oil-chamber. This is held in position on the axle by a square, split cotter-pin. Fig. 2 is a similar wheel, with a patent cast bushing, which is readily replaced when worn. The lubrication is effected by a simple oil-hole, but the oil is delivered a little inside of the gaugeline of the wheel, where it is most needed. Figs. 3, 4, and 5 are sections of a " new style " patented, self-oiling wheel. In this, the outer end is cast closed, and the wheel is fastened to the axle by a spring cotter-pin passed through one of the plugged holes. Dirt is prevented from entering the open end by a cap, with faced end and packing-ring, fitting over the end of the hub. The lubricant is introduced into the oil-chamber through one of the plugged holes in the hub. When the wheel is in motion, the lubricant is thrown by centrifugal force away from the axle, enters the two ports shown, and is

Jan 1, 1890

In accordance with the provision of the Constitution, notice is here given to all Members, Associates, and Junior Members, that the dues of the year 1918 will be payable on Jan. 1, 1918, at the office of the Secretary. The dues for Members and Associates are $12 per year and the sum of $3 additional is asked of those Members and Associates who desire to have the three volumes bound in the Institute's standard half-morocco binding. The dues of Junior Members are $5 per year.

Jan 1, 1918

By John B. Pearse

THE works heretofore used in carrying out the Bessemer process have been constructed substantially as follows : The whole works or plant has been divided into three parts. 1. The division in which the metals for conversion are melted. 2. The division in which the metals are converted into steel and cast into ingots, or the converting department. 3. The engine and boiler department which supplies the hydraulic power required to move the machinery, and which furnishes the blast used for converting the crude metal into steel.

Jan 1, 1876

By Carl S. Westerberg

1,. C. McCABE*-—An increased derliand for coal in the west is to be expected because of the growth in population and industry during the past ten years. The author calls attention to the increased mechanical cleaning of Utah coal between 1938, when no cleaning was being done, and 194.7, when more than 24 pct of the production was cleaned. This is essentially the Period of most rapid growth of the Pacific Coast. area altliough the growth and, no doubt, the general trends in coal production and cleaning continued at a less accelerated rate during 1948. The Pacific southwest increased 37 pct in population between 1940 and 191.7 while the United States showed only a 7 pct increase in the same period. it has been estimated that there will be an additional 15 pct increase in population between 1947 and 1950. The conclusion that more coal and more mechanicak cleaning capacity will be required appears to be well founded. Mr. Westerberg discusses the cco- nomic advantages of coal cleaning reflected in freight savings, in lower cost per million Btu, and lowered ash and sulphur content. In view of the limited occurrence of coking coals in the west it would be interesting to know whether significant beneficiation in coking strength can be expected from mechanical cleaning of Utah coals. This has been demonstrated for some eastern and midwestern coals. One can readily agree to the desirability of recovering the fine coal that has heretofore been lost in washery slurry. The very cheapness of coal has Iridered

Jan 1, 1950