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By H. M. Varner

Under sponsorship of the US Bureau of Mines and the Department of Energy, a new type of rotary rock drill was developed by The Bendix Corp. Originally developed for the production of holes for the installation of longer than seam height roof bolts, the flexible drill is a useful tool for many drilling applications. It allows hands-off or remote production of holes for increased drilling speed and greater operator safety in any strata suitable for rotary drilling. This paper discusses various applications and experience for the flexible drill system in coal, metal/nonmetal mining, and for civil engineering uses. Manual, remote control, and automatic roof bolter modules are also discussed.

Jan 1, 1984

By Francois Clerf

IRON ORE fields are situated in both the East and West of France (see maps). The eastern deposit is by far the most important from a tonnage point of view, not only in France, but in all Europe. The ores of this region are known as minette, and are situated in the Lorraine ore fields and the Briey plateau. The iron ores of the West are those of Normandy, Anjou and Brittany. Before the war, a large number of important German companies had acquired considerable interests in these western fields and a heavy trade with Westphalia had begun. Recently, however, conditions have changed and some of the mines of Brittany and Anjou are now idle. From a geological point of view, in Anjou and Brittany, a series of synclines extends from the northwest to the southeast, containing a number of seams of varying thickness and generally intercalated in Silurian and sometimes in Devonian formations. The ore is generally a hematite or a magnetite. The composition varies from 48 to 52 per cent of iron and from 8 to 12 per cent of silica. Con¬servative estimates indicate a con¬siderable tonnage of workable ores (150,000,000 metric tons).

Jan 1, 1936

By Robert L. Slobod

In much of the work reported in the literature on long cores. true connate water value, probably have not been obtained because of insufficient flow of 011 to attain equilibrium. A -.satisfactory method for establishing connate water in long cores has been developed in which oil flow is maintained until no additiona1 water is displaced. INTRODUCTION Long cores have been used by sev-erals investigators in an effort to evaluate the efficiency of oil recovery for various producing schemes. The effects of many variables such as rate of displacement. pressure drop, volume of displacing medium, gas-oil ratio, inter-facial tension, and others have been investigated, and the merits of gas drive have been compared with water drive. In the older experiments no connate water was used. but in the more recent stndies the philosophy of the experiment calls for a core containing oil and connate water (irreducible water) as the starting point of the experiment. The method generally used to establish this condition in long cores involves dynamic' displacement wherein one or more phases are forced through the core. flow being maintained at a constant rate or at a constant pressure until a steady state is reached wherein there is no change of saturation with time. It is one purpose of this paper to point out that in much of the work reported in the literature true connate water values probably have not been obtained. The reason for this failure is pointed out. and a method for obtaining more reliable connate water values on long cores is presented. It is impossible at this time to completely evaluate the effect on the conclusions in the earlier papers resulting from the failure to obtain true connate water in the long cores, but some data are presented which indicate that serious errors may he present in many cases. MATERIALS AND APPARATUS Cores cut front outcrop sandstones (Strawn. Torpedo, and Elgin sandstones) with permeabilities of the order of 300 md were used. The major experiments were made with a core 18-in. long and 2-in. in diameter. Cores of the same diameter but only 12-in. long were used in a few tests? and in some work a core I-in. in diameter and 11-in. long was used. These materials were all somewhat bentonitic. 'To reduce the effect of such constituents, one of the cores (Torpedo No. 10) on which the most work was performed was acid extracted at the start of the experiment. Brine containing 50,000 ppm chloride and naphtha (Stoddard's Solvent) were used as the water and oil phases, respectively. The core was mounted in a rubber sleeve which forms the inner lining of a brass cylinder. In this arrangement2 the rubber sleeve is forced against the core by applying pressure to water in the annular space between the rubber sleeve and the brass cylinder wall. The core is therefore sealed in rubber so that all fluids introduced at the input end of the core flow through the core. With this equipment the core may be easily removed for inspection and analysis. Also, other cores may be introduced for study with no extra time for preparation such as is required when plastic mounting is used. When pressure or conductivity measurements are desired at intermediate points along tile length of the core, the brass cylinder comprising the outer jacket of the core holder is cut into section, of the desired length. Each section is then made up as an individual unit with its own rubber sleeve (see Fig. 1). The individual units are then butted up against a ring of plastic or other insulating material which carries an electrical contact for resistivity measurements and an opening which can be used for the measurements of fluid pressures. The individual units are forced tightly against the plastic ring separators and held in place with several tie rods. Inlet and outlet end butts of the same diameter as the core and several inches in length are provided to control the introduction and withdrawal of fluids and to complete the arrangement for sealing the core within the rubber sleeve. Fluid flow is maintained either by applying pressure to the liquid confined in a reservoir or by the use of a gear pump. The latter is preferable where continuous flow at a moderate rate over a long time interval is desired since a small volume of liquid can be readily recirculated using filters to prevent plugging of the core. EXPERIMENTAL The oven-dried core is weighed and is then completely saturated with brine

Jan 1, 1950

By Basil B. Zavoico

Production of crude oil in the U.S.S.R. during 1940 is estimated at 222,600,000 bbl., as compared with the revised figure for the preceding year of 220,866,000 bbl., an increase of 0.79 per cent, and at least 20 per cent under the planned output. Baku district (Transcaucasus) remained the outstanding producing area, accounting for 72.33 per cent of the country's production, and this relative importance of the Apsheron Peninsula oil fields will probably continue lor many years to come. In the North Caucasus the Grozny-Dagestan area further extended its decline and the current production in this district amounts to only 6.06 Per cent Of the total U.S.S.R. output, as compared with 35.76 Per cent in 1931 The production of the Kuban-Maikop district remained virtually ullchanged from the preceding year, amounting to 7.64 per cent of the country's total. The Caucasian Province, therefore, in I940 produced 86.03 Per cent of the total production of the U.S.S.R. The promising new Permian Basin district, called Ural-Volga, and referred to sometimes as the "Second Baku," increased its production appreciably during 1940 and the output of that area amounted to 8.31 per cent of the country's total, as compared with 6.35 per cent during 1939. Production in the secondary districts of Russia continued unchanged though some new discoveries in the Emba salt-dome basin suggest that the output of that district may show some increase during the coming years. The drilling operations in Russia during 1940 reached a stage of virtual breakdown and the original footage plans were fulfilled only to the extent of around 50 per cent, while exploration drilling schedules were fulfilled only to the extent of about 25 to 35 per cent. This condition was due to the obvious lack of modern drilling rigs, of good drill pipe and of strong casing. Extended breakdowns occurred with deeper drilling, particularly because with few good drilling rigs available speed was being attempted with rotation rates that the inferior drill pipe and bits could not stand. Twistoffs and endless fishing jobs resulted. The difficulties became so serious a handicap to the Soviet oil industry that it was found imperative to order American drilling equipment and pipe in quantity, a policy that was never favored in the U.S.S.R because it requires expenditure of gold or exchange in major volume, and such exchange usually is reserved only to less bulky key items or to orders directly connected with armaments; also, oil-field machinery is very bulky and the prevailing lack of bottoms makes the transport of the indicated equipment a major problem. But little progress was similarly made in other branches of the Soviet oil industry. NO new major pipe-line construction work was undertaken, consequently the railroads continued to be overburdened with traffic that could be much more effectively handled by pipe lines. No new refinery construction of any magnitude was initiated, though several plants that had been in course of construction for several years were completed during 1940 and operation 554

Jan 1, 1941

By Basil B. Zavoico

Production of crude oil in the U.S.S.R. during 1940 is estimated at 222,600,000 bbl., as compared with the revised figure for the preceding year of 220,866,000 bbl., an increase of 0.79 per cent, and at least 20 per cent under the planned output. Baku district (Transcaucasus) remained the outstanding producing area, accounting for 72.33 per cent of the country's production, and this relative importance of the Apsheron Peninsula oil fields will probably continue lor many years to come. In the North Caucasus the Grozny-Dagestan area further extended its decline and the current production in this district amounts to only 6.06 Per cent Of the total U.S.S.R. output, as compared with 35.76 Per cent in 1931 The production of the Kuban-Maikop district remained virtually ullchanged from the preceding year, amounting to 7.64 per cent of the country's total. The Caucasian Province, therefore, in I940 produced 86.03 Per cent of the total production of the U.S.S.R. The promising new Permian Basin district, called Ural-Volga, and referred to sometimes as the "Second Baku," increased its production appreciably during 1940 and the output of that area amounted to 8.31 per cent of the country's total, as compared with 6.35 per cent during 1939. Production in the secondary districts of Russia continued unchanged though some new discoveries in the Emba salt-dome basin suggest that the output of that district may show some increase during the coming years. The drilling operations in Russia during 1940 reached a stage of virtual breakdown and the original footage plans were fulfilled only to the extent of around 50 per cent, while exploration drilling schedules were fulfilled only to the extent of about 25 to 35 per cent. This condition was due to the obvious lack of modern drilling rigs, of good drill pipe and of strong casing. Extended breakdowns occurred with deeper drilling, particularly because with few good drilling rigs available speed was being attempted with rotation rates that the inferior drill pipe and bits could not stand. Twistoffs and endless fishing jobs resulted. The difficulties became so serious a handicap to the Soviet oil industry that it was found imperative to order American drilling equipment and pipe in quantity, a policy that was never favored in the U.S.S.R because it requires expenditure of gold or exchange in major volume, and such exchange usually is reserved only to less bulky key items or to orders directly connected with armaments; also, oil-field machinery is very bulky and the prevailing lack of bottoms makes the transport of the indicated equipment a major problem. But little progress was similarly made in other branches of the Soviet oil industry. NO new major pipe-line construction work was undertaken, consequently the railroads continued to be overburdened with traffic that could be much more effectively handled by pipe lines. No new refinery construction of any magnitude was initiated, though several plants that had been in course of construction for several years were completed during 1940 and operation 554

Jan 1, 1941

By Raja V. Ramani, Ralph W. Barbaro

This paper presents an application of a Mixed Integer Programming (MIP) model to the problem of locating a centralized coal preparation plant and determining the production schedule for the mines. The system used for illustrating model application is hypothetical but realistic. It consists of three mines, two potential preparation plant sites, heavy media processing plant, and one market. The goal is to maximize the total profit of the system while satisfying the coal delivery schedule over a three year period meeting both quantity and quality requirements (ash, sulfur, and heat content). In addition to the base case, four different scenarios are analyzed. These four modifications are: (1) removing the flotation circuit from the preparation plant and sending all of the fines directly to the clean coal, (2) lowering the quality of coal from one of the mines, (3) applying discounts to the unselected site to improve its competitive position, and (4) adding a new mine. A detailed discussion of the base case and the effect of these four alternatives is presented.

Jan 1, 1983

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 W. R. Hibbard

It has been proposed1 on the basis of slip and flow that the ideal deformation texture of drawn wire for face-centered cubic metals is a (111) direction parallel to the wire axis. Under these considerations, an intermediate [loo] texture is permissible but should eventually change to the stable [Ill] orientation. This theory does not explain why copper and its alloys containing up to about 30 pct nickel, 5 pct zinc and 1 pct aluminum were found to have a double [Ill], [100] texture, while alloys with at least 8 pct zinc and 2 pct aluminum developed essentially a single [Ill] texture.1,2 It does suggest, however, that the [loo] component of the former alloys should disappear with additional deformation.3 Some evidence exists to support this suggestion. Howald4 reported that annealed copper wire previously drawn 93.8 pct and 98.5 pct developed a single [Ill] texture. Since, in wire, the drawn and annealed textures are similar, these wires probably had a single [Ill] deformation texture before annealing. In addition, although cold rolled polycrystalline copper and 80-20 brass were found to form different types of pole figures,5,6 single crystals of these metals when rolled from the stable (110) [112] orientation were found to produce essentially the same polo figure.7.8 It may be, therefore, that while the addition of solute elements changes the path by which the final texture is obtained, the final texture is not changed. Experimental Results The wires remaining from the previous investigation1 already drawn about 50 pct reduction in diameter were further drawn to 86 pct and then to 96.4 pct total reduction in diameter. The textures were determined after these stages by transmission X ray photograms taken with a copper K-alpha beam rotated 0 degrees toward the wire axis. It was found that the ratio of the [111].] and [100] intensities of the double texture in copper and its alloys containing 0.94 pct aluminum, 30.70 pct nickel, 2.61 pct zinc and 4.99 pct zinc increased from about 3:l for the 50 pct reduction to about 9:l for the 86 pct reduction. After 96.4 pct reduction, these wires exhibited essentially a single [lll] texture. Summary Thus, the drawn wire deformation texture of copper and its alpha solid solution alloys containing aluminum, nickel or zinc is essentially a single [Ill] texture as predicted by theoretical considerations of slip and flow.' For copper and its alloys containing up to about 1 pct aluminum, 5 pct zinc and at least 30 pct nickel, an intermediate [loo] component is found after about 50 pct reduction in diameter, but disappears after about 95 pct reduction in diameter. For alpha solid solution alloys containing at least about 2 pct aluminum and 8 pct zinc the single [Ill] texture is developed considerably more easily and is found after about 50 pct reduction in diameter. No explanation of this compositional effect is apparent. Similar work is contemplated for cold rolled and cold compressed alloys. References 1. w. R. Hibbard, Jr. and M. K. Yen: Trans. AIME 175, 126. Metals Tech., Feb. 1948, TP 2334. 2. W. R. Hibbard, Jr. and D. E. Trout, 11: Trans. AIME 185, 620. Jnl. of Melals, Sept. 1949, TN 18. 3. W. R. Hibbard. Jr.: Disc. of R. M. Brick's paper on Deformation Textures, ASM Symp. on Cold Working of Metals, Oct. 1948. 4. T. S. Howald: Disc. of Ref. 1. Trans. AIME, 175, 126. Melals Tech. Aug. 1948, TP 2449. 5. R. M. Brick, D. L. Martin and R. P. Angier: Trans. ASM (1943) 31, 675. 6. 0. Dahl and F. Pawlek: Zlsch. Melall. (1936) 28, 266. 7. C. S. Barrett and F. W. Steadman: Trans. AIME (1942) 147, 57. 8. J. E. Burke and C. S. Barrett: Trans. AIME 175, 106. Melals Tech., Feb. 1948. TP 2327.

Jan 1, 1950

By B. B. Rath, Hsun Hu, R. S. Cline

FOLLOWING the techniques used by Beck and co-worker~ "~ the characteristics of selective growth in the recrystallization of a zone-refined aluminum single crystal, rolled 80 pct at -78°C in the (110)[112] orientation, have been studied. The material was 99.999+ pct pure. The as-grown crystal had a resistance ratio, R(298°K) /R(4,2°K), of approximately 5000. The method of preparation of the single crystals and the necessary precautions in handling them during rolling in order to avoid recrystallization in locally distorted regions were described in an earlier paper.3 The rolling texture of this zone-refined aluminum crystal is practically identical with that of less pure aluminum crystals rolle! in the same orientation, i.e., a very sharp (110)[112]. Random nuclei were provided by artificial nuclea-tion by abrading one face of the rolled crystal on 600-grit emery paper in a random fashion. The thin layer of disturbed metal recrystallized at room temperature into fine grains almost immediately. An X-ray diffraction pattern was taken from the abraded surface of the crystal, and the relative intensities of the various reflection peaks were compared with those obtained from a powder specimen. As shown in Fig. 1, the relative intensities of the various peaks from the recrystallized layer varied somewhat from experiment to experiment, depending presumably on the abrading technique. However, the texture of the recrystallized layer produced by this method is nearly as random as that of a powder specimen. Fig. 2 shows the texture determined from the "growth side" (face opposite the abraded surface) of the crystal after it was kept at room temperature for 100 hr. The specimen was only partially recrystallized, as shown by the remaining deformation texture. The new orientations are derived from the recrystallized grains grown through the thickness of the crystal from the "nucleation side" (the abraded surface). Fig. 3 shows the texture after complete recrystallization produced by annealing at 60°C for 1 hr. The arrows indicate 40-deg rotation around the (111) axes of the deformation texture. The microstructure of a completely recrystallized specimen is shown in Fig. 4. As shown in Figs. 2 and 3, the texture of the re-crystallized grains grown from the nucleation side to the growth side is essentially the same as that observed in less pure aluminum' (99.994 pct) and dilute alloyz crystals rolled in the same orientation. How-

Jan 1, 1968

YEAR OF ELECTION 1913. FRANK DAWSON ADAMS, Montreal, Canada. 1922. FEDERICO GIOLITTI Torino, Italy. 1921. FRANK WILLIAM HARBORD London, England. 1917. HERBERT HOOVER Washington, D. C. 1941. DANIEL COWAN JACKLING San Francisco, Calif. 1939. HENRY KRUMB New York, N. Y. 1921. C. McDERMID London, England. 1913. EZEQUIEL ORDONEZ Mexico City, Mexico. 1935. ROBERT PEELE New York, N. Y. 1938. A.M. PORTEVIN Paris France 1937. JOHN V.W. REYNDERS, New York, N. Y. 1937. GEORGE S. RICE Washington, D. C. 1911. ROBERT H. RICHARDS Cambridge, Mass. 1934. T.A. RICKARD Victoria, B.C., Canada

Jan 1, 1942

By S. Chander, D. W. Fuerstenau

The inherently sluggish nature of the reactions involving sulfide minerals, particularly molybdenite, in aqueous solutions under ambient flotation conditions make their investigation complicated and difficult. Since the physicochemical nature of sulfides is known to be controlled by electrochemical reactions, a number of attempts have been made in the past to study sulfide mineral-collector interactions through rest potential and electrode polarization measurements. The purpose of the present investigation was to study the interaction of potassium diethyldithiophosphate (KDTP) with molybdenite. In the present investigation of the interaction of KDTP at the molydenite surface, molybdenite electrode rest potential measurements and electrode polarization behavior were experimentally determined under various solution conditions. The standard reduction potential for the equilibrium between dithiophosphate ions (DTP-) and bis(diethoxythiophosphoryl)disulfide (DTP) [(DTP). + 2e :i7-± 2DTP- (1)] can be evaluated from the electrode rest potential measurements on a platinum electrode in deoxygenated KDTP solutions saturated with freshly prepared (DTP)2. Experimental A platinum wire was used as the electrode for potential measurements. Prior to each measurement the elec-

Jan 1, 1975

By G. R. Fitterer

NONMETALLIC inclusions in steel have received much attention by metallurgists during the past few years. Many investigators have been emphatic in stating their belief that these impurities are the chief causes of steel failures, while others think that their effects are negligible. One of the main reasons that definite information on the effects of these impurities is lacking is that no reliable method has been developed for the exact determination of the amounts of these different impurities in steel. Some valuable new information has been brought out by a reliable method for nonmetallic inclusions which has been developed at the Pittsburgh Experiment Station of the U. S. Bureau of Mines, in cooperation with the Carnegie Institute of Technology and the Metallurgical Advisory Board. This procedure satisfactorily extracts some of the more common inclusions from steels, thus enabling the investigator to correlate steel failures with inclusion content. Although the data given herein are the first to be published on the subject of the electrolytic extraction method, the interest in the subject is evidenced by the fact that it is already being used by some 20 to 30 steel companies for their various purposes. Some of the comments received from these laboratories indicate that the method is highly satisfactory: the unfavorable comments, when traced to their sources, have been found to be based on some small mistake made in either installation or operation. The chief discrepancy seems to have occurred in attempts to apply the method to the extraction of inclusions from alloy steels. The procedure can be used only for the plain carbon steels and for such low alloy steels as those containing the usual amount of copper (0.2 to 0.3 per cent). Steels containing the carbide-forming alloys such as chromium, tungsten, etc., present far too many difficulties for the accurate determination of inclusions. Luckily, the iron and manganese carbides do not offer any difficulties and no contamination of the oxide-sulfide residue results. It is highly probable that some modification of the following

Jan 1, 1931

By George Otis Smith

In the utilization of natural resources owner, operator, and consumer* should share the attendant benefits. Development needs to be planned under terms recognizing fully the interests of all concerned, for ally undue advantage given to any one of these participants is apt to involve even greater and disproportionate injury to one or both of the others. For this reason it is well to preface any consideration of needed reforms in legislation affecting the disposition of public land with a survey of certain fundamental principles that determine the general conditions of a11 land transfers preliminary to development, utilization, and production. The disposition of any undeveloped natural resource, whether timber, oil, coal, or water power, as a transaction to which land owner and prospective developer are parties, must be based in theory upon a division of expected returns.' Whatever the terms of such disposition, neither party can reasonably ask for anything other than an equitable division of the returns. Under this analysis three and only three questions need to be discussed; namely, what are those profits, how is this division to be accomplished, and what is the equitable basis of division ? The answer to the third question should probably be found by applying to the problem the principles of theoretical sociology, and the question need not be mentioned further at this time, inasmuch as it does not involve the practical considerations to be kept in mind in connection with the other questions, which are concerned with only the measure of returns and their division. That is to say, whether the land owner's equity is to be stated as 95 per cent, ox as 6 per cent, of the profits attending the development of the particular resource, no change would be necessary in the method to be adopted of arriving at the closest approximation of the prospective total profit. If on this basis we now compare the two methods of disposing of

Jan 1, 1915

By CLARESCE CARLETON SEJIPLE

(Wilkes-Barre Meeting, June, 1911.) AT a number of mines in eastern Nicaragua, 3.5- and 5-ft. Huntington mills are used for grinding gold-ore after a preliminary breaking in jaw-crushers. The smaller mills are made sectional to facilitate transportation to the more difficultly accessible mines. The capacity of the smaller mills is about 20 or 25 per cent. that of the larger, but in proportion to the quantity of ore ground they require more power and are subject to greater wear. The notes herein given are from records of the performance of the larger mills, but, in general, apply to the smaller also. THE NATURE OF THE ORE. The ore occurred as a series of flat veins in a highly-decomposed rock, probably alaskite. The primary mineralization comprised pyrite, pyrrhotite, marcasite, chalcopyrite, and quartz; the oxidation-products of which were chiefly hydrated iron oxide or limonite, chrysocolla, azurite, and malachite. The kaolinization of the feldspar of the country resulted in the admixture of a great quantity of clay with the oxidized ore. The quartz was sandy, imbedded in the clay; and probably the greater part represented the residue from the crushed rock in the fissures after leaching, and kaolinization of the feldspar. There was little vein-quartz in the unaltered primary sulphide ore. Only the oxidized ore was mined for the gold that it contained in amounts that averaged $4 per ton. No specks of gold were ever seen in the ore, and the gold obtained by panning was always exceedingly fine. The amalgamation-bullion was about 800 fine in gold and 60 to 80 in silver. The ore delivered at the mill contained from 5 to 15 per cent. of moisture; during the rainy season the quantity was much greater. The moisture and clay made the ore so sticky that it had to be raked over steeply-inclined grizzlies; it hung in the ore-bins,

Oct 1, 1911

By David B. Rushmore

Torches were used by the early Romans for mine-lighting, and these were followed by open lamps or earthen jars filled with tallow or oil, and later by candles. In early coal-mining, explosive gases seldom occurred, and, if they were encountered, the danger of explosion was materially diminished by the absence of any ventilating-system and the consequent insufficient circulation of air to form with the methane an explosive mixture. As the art advanced, the danger of fire-damp became more apparent, and methods for testing the air were resorted to as early as in the fifteenth century. The method of testing consisted in lowering a dog in a basket down the shaft. As soon as he encountered fire-damp he would commence to howl, after which he was withdrawn, and a leafy bush was fastened to the end of the rope and run rapidly up and down the shaft. This so disturbed the accumulation of gas as to cause it to rise out of the shaft. Later this odd method of testing was improved upon through the discovery that a light inserted in a body of fire-damp Gould produce a blue flame. Candles were used for this purpose, and, when fire-damp was thus discovered, brushing or some other primitive method of fanning was resorted to for driving out the gas. In some instances the gas was burned away, regardless of the danger thereby incurred. A man, wearing a well-moistened coat and a mask with glass spectacles, descended in the mine a few hours before each shift. With a long stick, to which was fastened a burning torch or candle, he would crawl on the floor with the stick so raised that the light would sweep the roof and ignite the gas which it encountered. In this position the flame of the explosion would pass over him, after which he would retreat from the gases resulting from the combustion. The occurrence of serious accidents resulted in

Jan 1, 1913

By W. Luyken, E. Bierbrauer

A number of articles have been published, notably those by R. S. Handy, R. T. Hancock and A. P. Watt in Engineering and Mining Journal, dealing with the calculations involved in ore dressing. These publications demonstrate both the importance of the subject and the lack of success in developing a generally recognized method for comparing enrichment effects. Considering that we may wish to compare enrichment results on similar or dissimilar ores, that we may desire to make the comparison on the basis of either the absolute or the economical efficiency, and that the number of factors upon which the result depends is large, the question arises whether it is possible to set up a positive method for such calculations. In the following pages it is our aim to show that a sure, complete and successful way to overcome existing difficulties has been found. Graphical Analysis of Ore-dressing Processes The following is from Truscott's Text Book of Ore Dressing (London, 1923): x = assay of ore treated (feed). y = assay value of the concentrate. 2 = assay value of the tailing. a = weight of feed. 6 = weight of concentrate. c = weight of tailing. C = fractional concentration = = . a y - z K = ratio of concentration = 1/c a/b = y-z/x-z 2 B = fractional recovery = 9 = C y/x (3) 100R = percentage recovery. Copt. = theoretically best concentration. 100 — Copt = waste in the feed.

Jan 1, 1930

By Homer N. Mead

This report develops equations for decline curve analysis based upon the premise that the rate of change of the reciprocal of decline for succeeding time intervals is constant when the reservoir is produced under a fixed set of conditions. A method is shown for predicting maximum production rate against cumulative production for any reservoir. A method is also presented for predicting future production rate by an analysis of past production performance after decline has been esrahlished. INTRODUCTION No significant contribution to the analysis of decline curves by the loss-ratio method has been made since J. J. Arps paper1. The concept of loss-ratio that was developed by Arps and his contemporaries has been redefined in another way and the concept of instantaneous loss-ratio at time zero has been added. In the mathematical developmerit by Arps, production rate was related as a continuous function with time and his equatlons were developed on that basis. In this paper, production is considered to be a series of segments for equal time intervals and equations have been developed based upon these finite differences. It is realized that decline curve analysis is not the answer to all predictions of reservoir behavior. However, as production must decline from an initial maximum rate to zero in any reservoir, if such decline can be expressed as an infinite series, this series should accurately predict production. Decline curve analysis should be considered a valuable tool that may be used in conjunction with predictions of future recoveries by other methods. Various uses of the decline curve method will be discussed in this paper. Equations predicting production rate at any time and cumulative production by exponential and hyperbolic decline will be developed. Characteristic values of b related to various types of drive will be discussed. After that a hypothetical reservoir will be studied and ultimate recovery by natural depletion and pressure maintenance compared, then actual field examples will be shown and discussed. The rate-cumulative curve introduced by H. N. Marshs in 1928 is an important one for use in estimating future production rate and ultimate recovery. This graphical method is the one that is used in conjunction with the equations to be developed for predicting production behavior. EXPONENTIAL DECLINE In exponential decline each succeeding production rate per unit of time is a constant percentage of the production rate just before it. Since (1 — r) is the common ratio, where r is the constant decline rate, this condition may be expressed as a geometrical progression; thus Pn = P (1 - r)n-1 . ......(1) Where r is less than unity, r Since P1 (1 - r)n = Pn+1 P1 - Pn+1 C =P1-Pn+1/r........(2) LOSS-RATIO In this paper the calculation for loss-ratio has been changed from the method presented by Johnson and Bollens2. The first loss-ratio to be calculated is a,; it is the initial production per unit of time after decline has set in divided by the difference between the initial and the second production rate. This loss-ratio is for the first time interval. After b (which is the constant change

Jan 1, 1957

By John D. Ridge

For mining geologists, the most important trends during 1962 have been the increased concentration of the exploratory activities of American mining companies in the United States and Canada and the greater use of the combined techniques of geology, geophysics and geochemistry in searches over larger areas for wider varieties of metals and minerals. The principal reasons for these changes in approach have been the deterioration of the political-economic climate in many areas of the globe of equal or greater geologic promise and the realization that modern exploration is most efficiently and economically conducted through the use of all available means of detecting ores in areas sufficiently large to raise to a maximum the chances of success. The attitude of certain major U.S. metal-producing companies can be shown by the officially ex- pressed positions of their principal officers. Early in 1962, Clyde E. Weed, Chairman of the Board of Anaconda, remarked that "because of unsettled conditions and disruptive influences in many of the copper-producing areas of the world, it is imperative that domestic copper-producing capacity be improved and made as efficient as possible in order to meet consumer demands at reasonably stable prices." In November, Robert G. Page, President of Phelps Dodge, pointed out that his company is not only concentrating most of its exploratory effort on this continent but is also increasing the number of metals for which it is searching. Frank R. Milliken, President of Kennecott, recently said that "most of our exploration money is going into the northern part of the Western Hemisphere."

Jan 2, 1963

By L. P. Teas

In spite of the influx of operators into the Gulf Coast anxious to retrieve their depleted production in other fields, and in spite of very active application of the most scientific geophysical methods to locate new producing areas, the results have been very discouraging and the year has failed to produce more than the average results for a Gulf Coast year. During the year seven new oil fields, some of which are still of very little importance, and one new gas area have been discovered. These fields are Tom Ball, Greta, Cleveland, Raisin and Garwood in Colorado County; Louise and Premont in Jim Wells County, and the new producing gas area near Ace in southern Polk County. During the year salt has been found for the first time at Carlos and Esperson. New producing areas have been developed on East Stratton Ridge, Hockley, Hull, Port Neches, near Pettus in Bee County, and on the O'Connor Ranch in Victoria County. The total production for the Gulf Coast for the year was 62,837,435 bbl., an increase of 18,589,000 bbl. over 1932. During the year, 1307 wells have been drilled of which 207 were wildcats, compared with 653 wells and 141 wildcats the previous year. The total daily production at the end of the year was 165,201 bbl. At present there are 3100 oil wells producing. The average production per well is 55.5 bbl. per day. The price of crude fluctuated considerably during the year, beginning at 80c per barrel and closing the year at $1.04 per barrel. Completion data for 1933 are as follows:

Jan 1, 1934

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members.) Members and guests who registered at Institute headquarters during the period Aug. 10 to Sept. 10, 1914: William Huff Wagner, Milford, Del.. Stanley C.- Herold, San Jose, Cal. Charles W. Hamilton, Tampico, Mexico R. J. Grant, Denver, Colo. A. M. Van Rensselaer, New London, Conn. John Lloyd, Wilkes-Barre, Pa. . Henry C. Carr, New York, N. Y. D. M. Riordan has been appointed to act as special adviser to the Secretary of the Treasury and has sailed on the U. S. S. "Tennessee" for Europe, where he will assist in aiding Americans in returning to the United States.

Jan 10, 1914