Search Documents

By C. Dalton, H. L. McGill

The purpose of this study was to develop a method for predicting the time delay created by metering a fluid through an annular restriction with translational motion of the boundaries. This time delay is utilized to control the opening of valves in various down-hole oilfield tools and forms the basis for the "hydraulic jar". The hydraulic jar is used to give upward impact forces to tubing or other tools that become lodged down-hole. The design of these jars has primarily been by trial and error; varying the clearances, fluid viscosities and dimensions of the jar until a satisfactory time delay was achieved. Obviously, a better understanding of the fluid flow characteristics is required to produce designs that are satisfactory and to eliminate the trial-and-error approach. Previous studies of flow in annular spaces were based on constant length of the annular restriction. Any motion of the boundaries of the annular space was confined to a rotational motion, like that encountered in journal bearing design. Consideration of the effect of translational motion of one boundary with respect to the other was necessary in applying this previous work to a time delay device. A prediction method was developed that takes into account this relative translational motion. Equations were developed to predict the relative velocity, the flow rate, and the time delay in a concentric annular space. The effect of eccentricity also was included. Experimental data were obtained and closely correlated with the prediction method. This correlation is presented graphically in terms of predicted and actual relative velocities for various annular clearances and pressure drops. This extension provides design equations which predict the performance of the hydraulic jar, thereby eliminating trial-and-error solutions and reducing the development time required for satisfactory designs. INTRODUCTION The design of down-hole oilfield tools which use hydraulic delay systems based on flow through annular orifices with relative motion of the boundaries is usually a trial-and-error process. The annular clearances, fluid viscosities and dimensions of the mechanisms were varied until satisfactory delay times were obtained. The development of these tools has been expensive, and a better understanding of the characteristics of annular flow with relative motion of the boundaries could result in superior and less expensive designs. The purpose of this investigation was to provide a method of predicting the performance of down-hole tools which use annular flow and, in particular, the performance of a down-hole tool known as the "hydraulic jar". The hydraulic jar is used to free pipe, packers and other tools that become lodged down-hole. The jar, located in the tubing string between the surface and the object which is stuck, releases the object though the repeated application of upward impact blows. The jar is basically a slip joint that is restrained in a collapsed condition until the desired tubing tension has been developed. The slip joint is then released and accelerates rapidly until it shoulders, delivering an impact blow or jar to the object. The delay obtained by metering the fluid through the annulus formed by the jar valve and housing provides the time delay necessary to stretch and apply tension to the tubing or pipe. Fig. 1A gives a schematic diagram of the hydraulic jar and brief details of its operation. The metering of the hydraulic jar begins when the tension force being applied to the jar by the pipe creates a pressure differential across the valve that is approximately equal to the force divided by the displacement area of the valve. This pressure differential induces flow through the annular restriction formed between the valve and housing. The valve moves with respect to the housing as the

Jan 1, 1969

By Henry Rumfelt

8.1-1. History and Description of Shovels. The history of excavating machinery is not clearly defined but the machines seem to have been originally developed for dredging activities, principally involving rivers and harbors. The first, as far as can be determined, was a steam "spoon dredge" developed by Grimshaw of Boulton and Watt of Sunderland, England, in 1796. The land machine forerunner of the present-day power shovel was not developed until 1835. It was invented by William Smith Otis, a young partner of a Philadelphia contracting firm by the name of Carmichael and Fairbanks. The moving force behind this invention was the heavy activity in railroad construction. From this early start the power shovel has developed from steam powering to internal-combution-engine powering and to electric powering. In both directions it has developed to its present state of a finely engineered and precision-built tool. Through the interim the railroad-type shovel, about a half-swing arrangement designed especially for making railroad cuts and mounted on rails, was developed. The rail-mounted shovel gradually gave way to the full revolving shovel. It was high on the list in 1912 and was practically extinct by 1927. From the beginning, a few of the small revolving shovels designed primarily for the general contractors' market had found their way into quarry and mining operations. During this same period, the stripping shovel had been introduced-a 2 ½ cu. yd., 100-ton, full revolving stripping machine with a 41 ft boom. Although this shovel was designed especially for stripping, it was also used for heavy-duty, open pit mining service. In 1925 the heavy-duty, full revolving quarry and mine machine was developed. Strip mining shovels evolved through a somewhat separate path. Hand digging plows and mule-drawn slip scrapers were first reported used by Kirkland, Blakeney and Groves near Danville, Illinois for strip mining

Jan 1, 1968

By Franklin J. Stermole

INTRODUCTION Economic evaluation of an open pit mine is similar to the economic analysis of any major investment project in any industry. It requires (1) taking into account all of the costs and revenues that are estimated to be incurred over the economic life of the project; (2) crediting the project with all the tax savings and tax credits that will be realized over the project life from tax deductions and credits related to various project costs; (3) charging the project with all taxes to be paid on taxable income over the project life; and (4) properly accounting for the time value of money for all project costs, revenues, taxes, tax savings, and tax credits when making the overall project economic evaluation. These considerations must be taken into account for any valid method of economic analysis such as discounted cash flow rate of return (DCFROR) or net present value (NPV) analyses. All economic analyses fall into one of two categories. ( 1 ) comparison of income-producing alternatives, or (2) comparison of service-producing alternatives. The analysis of alternatives in either of these categories can be made by using correctly any of five basic economic evaluation approaches which are. ( 1 ) present value, annual value, (3) future value, (4) rate of return (ROR) , and (5 ) break-even analysis. Of these evaluation techniques, DCFROR and NPV analyses are used most widely for evaluating income-producing alternatives while present worth cost and equivalent annual cost analyses are used most often for the evaluation of service-producing alternatives. In this chapter income- producing alternative analysis is emphasized, so DCF- ROR and NPV are utilized for evaluating the case studies presented.

Jan 1, 1979

By M. R. Geer Olds, H. F. Yancey

THE increase in the number of coal-cleaning plants employing dense-medium processes occurring since 1946 is especially interesting when viewed historically. Both sand and magnetite were introduced as material for heavy mediums at about the same time, sand in the Chance process in 1921 and magnetite in the Conklin process in 1922, but from that point on their records diverge. The Chance process enjoyed a steady growth from its inception, whereas no additional magnetite plants were built in the United States for over 20 years. Then, following the close of the World War 11, magnetite was again introduced, this time with marked success. During the following years some 47 plants employing magnetite medium were built. This rapid growth of dense-medium cleaning has been concurrent with widespread adoption of full-seam mining on one hand and a return to a more competitive market on the other. At a time when changing mining practice has provided cleaning plants with dirtier coal and changing market conditions have simultaneously demanded a cleaner product, the industry has through necessity turned to improved preparation. The inherently greater sharpness with which dense-medium processes can separate coal from impurity is thus helping to hold the line against ever-increasing mining costs and at the same time assisting materially in retaining badly needed markets. Although dense-medium cleaning unquestionably offers a distinct advantage when the washing problem is difficult, other methods can provide almost equally high efficiency when the coal is easy to wash. Moreover, fine coal cannot yet be treated by heavy medium in a proved process, although the Driessen cyclone is in the pilot-plant stage. Most of the present types of dense-medium equipment have been in use only a few years, and the dearth of information in the literature concerning their performance characteristics is entirely understandable, Nevertheless this information is necessary if the process is to be intelligently applied to individual cleaning problems. Without data on the efficiency of a process in a particular type of separation, it is difficult to assess the advantage to be expected from it. Similarly, the role of particle size in heavy-medium separation is important in some cases, yet there is little published information on this aspect. To mention only one more of the numerous points on which essential information is lacking, the bearing of medium characteristics on performance has been discussed only in qualitative terms. It was with the hope of providing information on some of these points that the Bureau of Mines built a dense-medium pilot plant for cleaning coal at its Northwest Experiment Station in Seattle in 1950. The plant has been operated continuously since that time, and over 50 runs have been made on 7 coals exhibiting a wide range of washability characteristics. An idea of the magnitude of this work will be gained from the fact that examination of the plant products has involved some 600 float-and-sink separations and about 2500 ash determinations. A laboratory pilot plant is especially well adapted to investigate many aspects of performance because close control over test conditions can be exercised and because a large number of tests can be made rapidly. On the other hand, factors such as consumption of medium and other cost items can be investigated satisfactorily only in a commercial plant. Actually, the two forms of investigation should be complementary, with the laboratory work pointing the way for confirming tests in commercial units. Pilot Plant The dense-medium pilot plant employed for this work comprises a 24x30-in. drum-type separating vessel, a 12-in. densifier, a 12-in. magnetic separator, a 26-in. x 9-ft vibrating screen, and the necessary pumps and conveyors for handling materials. Arrangement of these units corresponds with the flowsheet used in most commercial plants, except that a thickener is not provided for the feed to the magnetic separator. Coal and refuse discharge from the separating drum to the vibrator, which is divided longitudinally down the center. Medium draining through the first 3 ft of the screen is recirculated directly to the drum. Sprays on the middle 3 ft of the screen rinse medium from the products, and the last 3-ft section is for dewatering. Dilute medium from the rinsing and dewatering sections is pumped to the magnetic separator, where magnetic solids are recovered. These are pumped to the densifier, from which they return to the medium-drainage sump by gravity through a demagnetizing coil. The drum-type separating vessel is a scale model of a commercial unit. Feed enters axially at one end of the drum just below the surface of the bath, and float material overflows through a circular opening at the other end. Particles sinking to the bottom of the bath are picked up by lifting flights bolted to the inner wall of the drum, elevated out of the bath, and sluiced to the vibrating screen. Baffles suspended in the bath prevent float material from entering the sink-lifting flights. About 8 gpm of medium is used to sluice the feed into the drum. An additional 15 to 24 gpm, depending upon operating conditions, is added through two pipes dipping into the bath behind the baffle on the side where the sink-lifting flights enter the bath. The bath available for separation is 2 ft long and 13 in. wide, giving an area of 2.08 sq ft. Depth of bath from the surface to the top of the sink-lifting flights, measured vertically below the axis, is 6 in.

Jan 1, 1954

By R. Jr. Schuhmann

PROBLEMS in expressing, interpreting, and using size-distribution data recur in many phases of mineral dressing; therefore it is desirable that size analyses be ex-pressed in such a form, either numerically or graphically, that comparisons can be made readily. The size distribution of comminuted material is a result of a specific physical operation on the material and therefore should be governed by some definite physical principle, or cause-effect relation. Although this principle has not been dis-covered, it has been found that the size distribution of comminuted, homogeneous solids may be expressed by relatively simple mathematical equations. Two equa-tions in particular, proposed by Gaudin1 and by Rosin and Rammler,2 respectively, have stood out, both having wide demon-strated ranges of application. The form and the method of application of the two appear almost irreconcilably different on the surface, but, as will be shown, they are asymptotic in the fine sizes when expressed in the same units. This paper gives the results of a further study of the Gaudin and Rosin-Rammler relations, made with the object of develop-ing a form of size-distribution equation that will be more usable and more signifi-cant-particularly in comminution studies, both for interpreting the nature of size distribution and for evaluating surface. The work is summarized in the following:

Jan 1, 1940

By Allan Clark

(San Francisco Meeting, September, 1915) IT is nearly three years since the metallurgy of the Homestake ore was discussed with considerable thoroughness, in a paper' read before the Institution of Mining and Metallurgy. Certain changes have been made in this period which are perhaps of sufficient interest to justify a brief description, and it is chiefly with such details and miscellanies that this paper will deal. In the circumstances, a certain amount of repetition is inevitable, but matter treated of in the former paper will be referred to here only when it is necessary for the sake of coherency. For full descriptions of equipment and technique, the former paper should be consulted. The mineralized slates and schists which constitute the ore vary considerably in composition, but the unoxidized ore, perhaps constituting the major part of the reserves, contains either chlorite or hornblende (cummingtonite), with quartz, carbonates of lime, magnesia and iron, and arsenopyrite, pyrite, and pyrrhotite. Ferrous minerals predominate, and this fact has been an important factor in determining the metallurgical treatment. With one or two exceptions the minerals noted are of relatively high specific gravity, and the ore as a whole is exceptionally heavy, many determinations giving an average specific gravity of 3.00. This high specific gravity presents one decided advantage, when the' cost of treatment is compared with operations elsewhere, in that the ton, almost universally the basic unit, represents a volume probably less by 10 per cent. than that of many gold ores. On the other hand, this high gravity renders more difficult the discharge of pulp from mortars, its distribution on amalgam tables, and its transportation in launders.

Jan 7, 1915

As bizarre an example of competitive salesmanship to be imagined took place last June in Western Australia. A half dozen world renowned mining groups received a Japanese iron and steel investigatory mission. Geologists, engineers and businessmen, all specialists in iron ore, representing elements of the Japanese government and steelmakers, politely grilled each iron ore group for technical information and plans for property development. At stake were sales contracts with Japan for many millions of tons of iron ore. Since approximately two dozen visitors were involved, it was necessary to divide them into four groups for dispensing information, transportation and accommodations at the remote exploration camps. In a continent noted for its wide open spaces, the hinterland of Western Australia is spectacularly lacking in settlements. The state has better than one third of Australian land and statistically 0.8 persons per sq mile. In reality, however, over 400,000 of the 800,000 population reside in Perth. Under such circumstances, properly receiving and feting these important visitors would seem to be difficult but the competing exploration groups vied ingeniously to outdo each other in hospitality.

Jan 10, 1964

By A. Lawley S. Schuster

The tensile behavior of copper foils prepared from rolled bulk material has been studied over the thickness range 2 to 53 , and for a range of pain sizes. For foils of comparable grain size, having the cube texture and tested along (100), yield strength increases with decreasing foil thickness t below -26p, with a corresponding decrease in ductility. Deformation occurs in the form of localized slip clusters distributed throughout the gage section. To the extent that the tensile strength (10 to 18 kg mm-) is unaffected by foil thickness, and that the foils possess fair ductility, the stress-strain behavior resembles that of bulk material rather than that of whiskers or evaporated films of comparable dimensions. The dependence of yield strength o on foil thickness t below -26p is of the form: oy = oo + kt-1/2. Possible explanations for the stress increase are considered based on 1) the dependence of active dislocation source length on foil dimensions, 2) the locking of surface sources, or the blocking of mobile sources at the surface due to surface film. It is now well-established that filamentary whiskers of many materials show exceptionally high strength compared with bulk crystals.'-11 As the diameter of the whiskers decreases to -1, the observed fracture strength approaches, and in certain cases exceeds, the calculated shear stress for the nucleation of slip in a perfect crystal.' In general, the stress-strain curve is entirely elastic, with strains at fracture approaching 1 pct. Similarly, thin films12-24 of evaporated or electrodeposi-ted material have been shown to possess tensile strengths three to seven times that of bulk material, with total strains at fracture -1 to 2 pct. In the present study, attention has been directed to the room-temperature tensile behavior of thin foils of copper over the thickness range 2 to 53, prepared from rolled bulk material. Yield stress, ultimate tensile strength, elongation to fracture, and work-hardening behavior are measured as a function of grain size and foil thickness. Structurally such foils are superior to either evaporated or electrodeposited films, and in the recrystallized condition exhibit considerable ductility. Apart from preliminary work by Sumino and Yamamoto25 on the work-hardening behavior of rolled and recrystallized copper foils, no systematic tensile studies have been carried out on material of this form. EXPERIMENTAL PROCEDURE Tensile specimens were prepared from 99.995 pct purity rolled copper foils of thickness 2, 6, 12, 26, and 53, obtained from the Hamilton Watch Co., Lancaster, Pa. Irrespective of specimen shape, it is necessary to use tensile foils with edges free from notches or tears. To this end, any form of cutting operation was excluded, and the tensile foils prepared using a photoengraving process, the details of which are described elsewhere.26 Since tensile data are required under conditions of uni-axial stress, the specimen shape is extremely important. Ideally, the foil should be infinitely long, allowing a gradual taper from the grip area to the gage section; however, from a practical standpoint, long foils are easily damaged during testing. A modified tensile specimen was therefore selected having a parallel gage section 1.25 by 0.20 in. with a tapered shoulder section increasing to 0.5 in. at the grips, and an over-all length between grips of 4 in., Fig. 1. In practically all tests, these foils fractured within the parallel gage section. By approximating the foil contour (Fig. 1) to a hyperbola it is possible to analyze the stress distribution in the tensile foil using two-dimensional elasticity

Jan 1, 1964

By James W. Dally, William L. Fourney, Anders Ladegaard Peterson

For the past 3 years, the authors have been conducting research sponsored by the National Science Foundation (RANN) to improve the process of excavation by drilling and blasting. The approach followed has been experimental where the development of stress waves and fractures initiated at the bore hole have been investigated in order to obtain a complete understanding of the dynamic fracture process. The second step in the approach has been to introduce modifications in the drill and blast procedure which will permit closer control of the fracture process. The laboratory investigations involve high speed photography where the dynamic fracture process is recorded with a Cranz-Schardin 1, 2 multiple-spark camera. The camera is equipped with 16 spark gaps which are pulsed at 25 K volts to produce an intense but very short (0.5 sec) flash of light. The camera is capable of recording 16 photographs of a dynamic event at framing rates which can be varied from 30,000 to 1,500,000 frames per second. The exposure time is sufficiently short to stop motion associated with detonating explosive charges and to make visible the details of the fracture process at a bore hose. The bore hole in a massive intact rock formation is modelled with a two dimensional plate containing a circular hole to represent the bore hole. The model material employed is a transparent polyester known commercially as Homalite 100.* This polymeric material is extremely brittle as evidenced by its extremely low fracture toughness of [ ]. The fracture toughness is a measure of the ability of a material to resist the propagation of flaws or small cracks. In comparison, Schmidt3 has recently measured the fracture toughness of Salem limestone and determined [ ]. Thus, the Homalite 100 should closely model the brittle nature of rock where fractures occur at small flaws and propagate without any apparent plastic deformation. Homalite 100 is also birefringent, which indicates that it becomes optically anisotropic when subjected to either static or dynamic loads. Circularly polarized light is transmitted through the loaded Homalite 100 model in a polariscope4 and the birefringence produces an optical interference pattern which is called a fringe pattern. For dynamic photoelasticity, the multiple-spark camera is equipped with polaroid filters to produce the circularly polarized light required to generate the photoelastic fringe patterns. An example of a singlespark frame showing a fringe pattern from a typical experiment is presented in [Fig. 1]. The photograph was taken 0.000072 sec (72 sec) after the detonation of the explosive charge. The circular fringes are due to the outgoing dilatational or P type stress wave and travel with a velocity of 85,000 in. per sec (2260 m/sec) in the Homalite 100. The P wave is followed by a second lower velocity stress wave known as the shear or S type wave which propagates at a velocity of 49,000 in. per sec (1245 m/sec). In the local neighborhood of the bore hole, several radial cracks are visible. These cracks propagate at essentially a constant velocity of 15,000 in. per sec (380 m/sec) prior to arrest. The fringes about the crack tips and in the local region of the bore hole are primarily due to the residual gases contained in the bore hole after the explosive charge was detonated. Sixteen frames similar to this one are recorded during the experiment to give full field visualization of the dynamic event at 16 discrete times over its duration. The fringe order number N is related to the difference in the principal stresses of and 02 according to a stress optic law4: [ ] where f0 = material fringe value, and h = model thickness. The wholefield dynamic-fringe patterns provide a basis for simultaneously observing the interaction between propagating cracks and the stresses which drive these cracks. Fracture Control Experiments Improvements in the efficiency of the drill and blast procedures must involve close control of the fracture process following the detonation of an explosive charge in a bore hole. By control it is implied that the number of cracks initiated and the location of each crack on the wall of the bore hole can be specified. Control also, involves orienting each crack and maintaining the crack path and velocity until the specified crack length is achieved. If the entire fracture process can be controlled, then rounds can be designed to optimize volume removed. fragment size and minimize costs. One area of blasting where fracture control is vitally important is in underground excavation where the strength and stability of the rock walls must be maintained and smoothness and precision of the walls must be achieved. The smooth blasting method is one of the most commonly employed procedures for achieving some degree of fracture control. In smooth blasting, the central region of material is first removed, and then the final row of closely spaced undercharged or cushioned holes are fired to remove the final volume and produce a smooth wall. In some instances, unloaded or dummy holes between the loaded holes are recommended to guide the fracture plane. This investigation pertained to an evaluation of 3 features of the smooth blasting process. These included (a) the effect of stress reinforcement on fracture by simultaneously firing 2 charges; (b) the influence of a dummy hole on control of the fracture planes between 2 simultaneously fired charge holes; and (c) the influence of dummy hole spacing on fracture plane control.

Jan 1, 1979

By R. W. Raymond

In a paper on the Divining-Rod (Transactions, xi., 411), presented at the Boston meting, in February, 1883,I suggested, among other signs of which the skilled prospector might consciously or unconsciously avail himself in the search for springs of water or mineral deposits, the presence of particular grasses or shrubs, and the general appearance of the flora. There are not wanting, in the literature of our art, indications that greater attention was paid to such signs in ancient days than at present. It is the tendency of a scientific age to ignore, or regard as superstitious, what cannot be classified or explained. But the acute though unscientific observation of earlier times often, doubtless, accumulated facts which it would be worth our while to re-examine. It is highly probable that the mining prospectors of the sixteenth and seventeenth centuries, to go no further back, were close students of nature, and knew, though they could not explain, and, for reasons of private gain, would not communicate, many curious and significant facts. We can generalize better than they could; but for that very reason we are, perhaps, their inferiors in observation. They let nothing pass, because all things were equally significant to them. We take wider views, and miss more. And, no doubt, there still exists among practical millers, prospectors,, hunters, Indians, etc., an unwritten.

Jan 1, 1887

RECENTLY seven Boy Scouts were chosen from all the troops in the United States for their all-around ability, excellence in' scouting, and special ability as writers. Two of the members of this selected group were sons of In-stitute members. In the accompanying illustration, Ber-nard Queneau, son of A. L. J. Queneau, of the U. S. Steel. Corp., can be seen at the extreme left, just behind Theo-dore Roosevelt, who is shaking hands with the boy next to. Carl Zapffe (standing in the middle with his hands behind him), the son of Carl Zapffe, manager of the iron ore prop-erties of the Northern Pacific Railroad.

Jan 6, 1928

By M. B. Ramachandra Rao

THE spontaneous polarization surveys dealt with in this paper were carried out near Guddadarangavvanahalli (lat. 14° I7' N.; long. 76° 24' E.) in Chitaldrug district, which forms part of the Chitaldrug schist belt. The occurrence of gold, copper, lead and antimony ores has been noticed for several years but efforts to exploit them have been unsuccessful, therefore some spontaneous polarization surveys were made in the hope of finding indications of workable ore bodies. The country examined has a rugged topography, with numerous hills on which there is little vegetation. The climate is generally dry, the average annual rainfall of the tract being about 25 in., of which 17 in. occurs during the southwest monsoon. The geological formations of the area pertain to an ancient schistose series known as the Dharwar system (Archean). Locally, the rock formations have been divided into three series1-the chloritic series (or the Chitaldrug formation), the clay series (or the G.R. formation) and the trap series (or the Jogimardi trap). The chloritic series includes a complex of altered ancient traps and volcanic agglomerates intermixed with some schists of sedimentary origin, all of which are highly metamorphosed. The lithological types of this series are mostly distinguishable as greenstone schists, calc-chloritic schists, slaty schists, ochery and calcareous micachlorite schists, with subordinate bands of secondary limestone. The clay series (G.R. formation) is made up of shaly and argillistic schists, lithomargic clays, sandstones and brecciated ferruginous quartzites. The Jogimardi trap is mostly of the nature of an epidiorite (hornblende diabase), which is distinctly intrusive in the form of large laccolithic and narrower dikelike masses. In addition to this trap, there are other minor intrusives such as the chalybitic trap, quartz porphyry and quartz reefs. The topographical and geological features of the area are noted on the map of Fig. I. The locations of some of the spontaneous polarization centers determined by the geophysical survey are indicated also. METHOD OF SURVEY AND APPARATUS EMPLOYED The spontaneous polarization surveys were carried out in the manner recommended by the Imperial Geophysical Experimental Survey.2 Preliminary reconnaissance was first carried out along a series of parallel traverse lines that were laid out over the area. The potential profiles obtained in these traverses were plotted* on a suitable scale and when any

Jan 1, 1944

By M. B. Ramachandra Rao

The spontaneous polarization surveys dealt with in this paper were carried out near Guddadarangavvanahalli (lat. 14° 17' N.; long. 76° 24' E.) in Chitaldrug district, which forms part of the Chitaldrug schist belt. The occurrence of gold, copper, lead and antimony ores has been noticed for several years but efforts to exploit them have been unsuccessful, therefore some spontaneous polarization surveys were made in the hope of finding indications of workable ore bodies. The country examined has a rugged topography, with numerous hills on which there is little vegetation. The climate is generally dry, the average annual rainfall of the tract being about 25 in., of which 17 in. occurs during the southwest monsoon. The geological formations of the area pertain to an ancient schistose series known as the Dharwar system (Archean). Locally, the rock formations have been divided into three series1—the chloritic series (or the Chitaldrug formation), the clay series (or the G.R. formation) and the trap series (or the Jogimardi trap). The chloritic series includes a complex of altered ancient traps and volcanic agglomerates intermixed with some schists of sedimentary origin, all of which are highly metamorphosed. The lithological types of this series are mostly distinguishable as greenstone schists, calc-chloritic schists, slaty schists, ochery and calcareous mica-chlorite schists, with subordinate bands of secondary limestone. The clay series (G.R. formation) is made up of shaly and argillistic schists, litho-margic clays, sandstones and brecciated ferruginous quartzites. The Jogimardi trap is mostly of the nature of an epidiorite (hornblende diabase), which is distinctly intrusive in the form of large laccolithic and narrower dikelike masses. In addition to this trap, there are other minor intrusives such as the chalybitic trap, quartz porphyry and quartz reefs. The topographical and geological features of the area are noted on the map of Fig. I. The locations of some of the spontaneous polarization centers determined by the geophysical survey are indicated also. Method of Survey and Apparatus Employed The spontaneous polarization surveys were carried out in the manner recommended by the Imperial Geophysical Experimental Survey.2 Preliminary reconnaissance was first carried out along a series of parallel traverse lines that were laid out over the area. The Potential profiles obtained in these traverses were plotted* on a suitable scale and when any

Jan 1, 1946

By M. B. Ramachandra Rao

The spontaneous polarization surveys dealt with in this paper were carried out near Guddadarangavvanahalli (lat. 14° 17' N.; long. 76° 24' E.) in Chitaldrug district, which forms part of the Chitaldrug schist belt. The occurrence of gold, copper, lead and antimony ores has been noticed for several years but efforts to exploit them have been unsuccessful, therefore some spontaneous polarization surveys were made in the hope of finding indications of workable ore bodies. The country examined has a rugged topography, with numerous hills on which there is little vegetation. The climate is generally dry, the average annual rainfall of the tract being about 25 in., of which 17 in. occurs during the southwest monsoon. The geological formations of the area pertain to an ancient schistose series known as the Dharwar system (Archean). Locally, the rock formations have been divided into three series1—the chloritic series (or the Chitaldrug formation), the clay series (or the G.R. formation) and the trap series (or the Jogimardi trap). The chloritic series includes a complex of altered ancient traps and volcanic agglomerates intermixed with some schists of sedimentary origin, all of which are highly metamorphosed. The lithological types of this series are mostly distinguishable as greenstone schists, calc-chloritic schists, slaty schists, ochery and calcareous mica-chlorite schists, with subordinate bands of secondary limestone. The clay series (G.R. formation) is made up of shaly and argillistic schists, litho-margic clays, sandstones and brecciated ferruginous quartzites. The Jogimardi trap is mostly of the nature of an epidiorite (hornblende diabase), which is distinctly intrusive in the form of large laccolithic and narrower dikelike masses. In addition to this trap, there are other minor intrusives such as the chalybitic trap, quartz porphyry and quartz reefs. The topographical and geological features of the area are noted on the map of Fig. I. The locations of some of the spontaneous polarization centers determined by the geophysical survey are indicated also. Method of Survey and Apparatus Employed The spontaneous polarization surveys were carried out in the manner recommended by the Imperial Geophysical Experimental Survey.2 Preliminary reconnaissance was first carried out along a series of parallel traverse lines that were laid out over the area. The Potential profiles obtained in these traverses were plotted* on a suitable scale and when any

Jan 1, 1946

W. H. LINNEY, Chairman, OSCAR LACHMUND, Vice-Chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154; Spokane, Wash. STANLY A. EASTON, S. SHEDD. Mining camps from Mexico to Alaska and from the Pacific coast to the Atlantic were represented by delegates at the 5th Annual Northwest Mining Convention which was held in Spokane, Wash., Feb. 19-24, 1917. About 300 delegates from outlying regions were present, this being fully 100 more than have been counted at any previous mining convention in Spokane. Graham B. Dennis, president of the Northwest Mining Association, made the address of welcome. In part, he said: "Heaven has made us the possessors of an area great enough for an empire, varied enough in climate and possibilities to compass the whole complex field of modern industry. In the development of this broad heritage, we are not only actors for today, but trustees for future ages. "It is to foster this spirit of unity; to create and maintain strong bonds of mutual good will and confidence, that we founded the Northwest Mining Association. Wee support it because we believe it will give us strength; because we believe we shall learn from each other; because, in industry as in every other walk of life, personal contact and establishment of ties of friendship enrich and round out the characters of men." One of the interesting lectures of the week was that on "Alaskan and Russian Gravel Mining," by Dr.' Henry Mace Payne, consulting engineer for the Russian government and Consolidated Goldfields of South Africa. Dr. Payne's illustrations showed the different appliances in use in the countries mentioned. The Resolutions Committee reported back to the Convention six of the seven resolutions that had been presented to it. These were adopted as submitted, with some minor changes.

Jan 5, 1917

By L. S. Darken

IN the study of reactions occurring in liquid iron, alone or in contact with a liquid oxide or slag phase, it has been found that the experimental data over a limited range of concentration can in some cases be repre-sented satisfactorily by the simple equilibrium expression K - (p1)p1 (p2)p2 . (R1)r1(R2)r2 . where (P) denotes the concentration of a product and (R) the concentra-tion of a reactant in the reaction r1R1 + r2R2 + . . . Some of the reactions for which it holds are listed in Table 1. For others, however, the simple equation apparently does not hold. This has been attributed to an improper method of expressing concentration (for instance, weight per cent instead of mol fraction); or it has been supposed that the solutions are not ideal in the sense that the activity of a com-ponent is not proportional to its true mol fraction, But it may be that the problem has been oversimplified by neglecting some molecular species actually present; that is, by considering only the ostensible simple com-ponents and thus leaving out of account possible compound formation. It is the purpose of the present paper to point out how, in a group of related cases, a reasonable consistent assumption relative to the presence of a compound makes it possible to express the experimental data satis-factorily by the simple equilibrium expression when this compound is taken into account, and to bring into harmony data referring to different reactions in liquid iron. There are several a priori reasons for believing that solutions in liquid iron should not deviate far from ideality, provided that the concentration of solute is not too great and is expressed in proper terms. The factors that commonly lead to nonideality in systems at ordinary temperature as ionization or the occurrence of polar and nonpolar molecules-are presumably less effective in metal and in slag systems at high temperature. Again, the type of equation commonly used to express the value of

Jan 1, 1940

(Under this heading will be published notes sent to the Secretary of the Institute by members or other persons.) The governing body of the Imperial College of Technology, London, S. W. (Royal School of Mines), will shortly proceed to the appointment of a Professor of Metallurgy. This important Chair has been filled in the past by such eminent metallurgists as John Percy, Sir William C. Roberts-Austen, and others. Inquiry has been received at the office of the Institute for an engineer to examine a mica, deposit in one of the New England States. The position of converter blower at. a side-blow Bessemer steel casting plant is vacant.

Jan 4, 1913

By Lester C. Uren

Today, a dozen or more universities and colleges in the United States are offering curricula designed for the specialized training of engineering students who plan to enter the petroleum industry. Many hundreds of students are following these curricula in their academic preparation, with the expectation that by so doing they will be better equipped to enter the petroleum industry in an engineering capacity than their competitors that seek to do likewise with training of less specialized character. Those who have helped plan and develop these curricula believe that such specialization should and does afford the student a superior preparation for his task. Others have questioned this and urge a broad preparation in fundamentals without specialization. Still others are suggesting even greater specialization than present petroleum engineering curricula afford. Some would have the student first prepare himself in one of the more general divisions of engineering, such as civil, mechanical or electrical engineering, and then seek some degree of specialized preparation in a graduate program. Which of these views is correct; or, if there is merit in each, which plan offers the greater advantage to the student? It is time that we paused to take stock of our objectives and of our way of attaining them. Is the training received by our petroleum engineering students what it should be? To what extent is the product of our petroleum engineering schools meeting the requirements of the industry? How may graduates be better equipped for the work they are called upon to do? These are questions that educators interested in the training of petroleum engineering students are ever asking. They must depend upon engineers and executives engaged directly in the industry for advice and helpful suggestions in better planning the training to be offered to our future engineers. This paper will have served its purpose if it is successful in focusing attention of men active in the industry on some of these educational problems, to the end that the ideas of men close to the needs of the industry may be made known to those who have responsibility in the control of our educational programs.

Jan 1, 1937

By Richard D. Hagni

Abstract-Although the ore microscopist routinely examines polished sections to determine the mineralogy and texture of ores, his importance to the solution of problems peripheral to geology is not always fully realized. The techniques which he uses can be applied with little modification to the solution of a wide variety of beneficiation problem. By extending his studies beyond those normally considered to be of interest to the geologist, he can include examinations of polished sections of selected mill products. This is a logical extension, because the minerals and textures in the polished sections of ores are the same as those in mill Products. The mill dressing engineer should be more aware of the types of beneficiation problems that can be solved by the ore microscopist and what the ore microscopist can do for him. A greater degree of cooperation between the ore microscopist and the mill dressing engineer can be of significant mutual benefit. Ore microscopy holds an advantage over chemical analysis, because the interrelations and combinations of the mineral constituents of an ore or mil1 product can be visually determined. This advantage provides solutions to many beneficiation problems. Locking is a type of beneficiation problem that is particularly amenable to ore microscopy. The percentage, type, and distribution of locked particles can be readily determined with the aid of an ore microscope and an estimate made of the extent of additional grinding required for liberation. The extent of intimately locked types, which no reasonable amount of grinding will liberate, can also be evaluated. Mineral coating conditions, free particles of a deleterious mineral, and free particles of a valuable mineral held in floculated clusters of gangue are other features that can readily be observed. In some instances, visual examination may show that the problem is not one of locking. Photomicrographs illustrate the variety of beneficiation problems for which the ore microscope is applicable. These problems and their resolution demonstrate the importance of the instrument and show the value of close coordination between the mill dressing engineer and the ore microscopist.

Jan 10, 1978

By R. J. Tailleur, M. Rosenberg

Oil well drilling muds prepared with lubricating aids such as oil, graphite or mica will not produce a sufficiently strong protective lubricant film for the bit bearing surfaces under high load conditions encountered in drilling operations. Consequently, the damage to the bearing surfaces resulting from the absence of such a film frequently results in a shortening of the drill bit life. Several different types of extreme pressure lubricating additives for use in muds have been developed. These arlrlitives are capable of providing a protective lubricating film for bearing surfaces subjected to high load pressures. A modified version of the Timken lubricant tester, an instrument commonly used for testing the extreme pressure lubricating properties of oils, is used for measuring and controlling the lubricating qualities of the mud. Comparison tests made in the laboratory with 55/8-in. tricone bits drilling on steel plates immersed in extreme pressure lubricating muds and conventional muds showed that the bearing life of those bits tested in the lrrbricating mud was three to four times greater than obtained with conventional muds. Drilling tests made with extreme pressure lubricating muds in West Texas increased over-all bit life three to fourfold, reduced drilling torque and wear on drill pipe and drill collars. INTRODUCTION Roller bit cones contain roller, ball and journal-type bearings that are subjected to very heavy loading during drilling operations in which the only lubricant available for these bearings is either water or drilling mud. These bearings must be able to operate satisfac- torily in order for the cutting structures on the surface of the cones to be fully utilized. Frequently, the bearings wear to the point that the cones freeze and the bit must be pulled before the cutting structures on the cones become worn. In some instances the bearings continue to turn with severe wear but the cones, which are held on the bit by the bearings, drop off; and this causes an expensive fishing job. In other instances the bearings wear to the point that the cones pinch in causing an undergauge hole and delays to ream the hole. The advantage of increasing bit bearing life is self-evident. Because of inability to control the internal wear of bits while drilling, it was felt that improvement of the lubricating qualities of the circulating mud would be helpful. However, the often-discussed lubricating property attributed to muds has been a rather vague and intangible one. The literature has implied that the oil-emulsion muds are more effective lubricants than non-emulsion muds. Actually, there has been no direct method of measuring the lubricating property of muds which would indicate that one mud was better than another; there has been no way to determine whether the lubricating property of any mud was adequate. Furthermore, in comparing lubricating properties of muds, two qualities should be considered—the coefficient of friction and the extreme pressure lubricating qualities. For example, graphite can reduce the coefficient of friction, but does not provide a strong enough lubricating film to protect bit bearings subjected to high loads. The primary object of the investigation reported herein was to find a method for prolonging the bearing life of drill bits; and considering the heavy loads used in drilling, it was felt necessary to find both a method of measuring lubricating properties under high load conditions and methods of establishing effective lubrication under these conditions. Extreme pressure lubrication deals with that realm of lubrication where metal surfaces are in rubbing contact with each other under very high pressures. These pressures may be quite high, as for example,