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By John J. Reed

This paper was prepared as a supplement to the general review by Dr. N. G. W. Cook. His analysis of the problem in terms of the strain energy involved in making the excavation is excellent. It will contribute much towards a clearer understanding of rock behavior and control. Several of the practical applications described herein can be directly related to Dr. Cook's theories and conclusions, and are based on the very same principles. CONTROLLED BLASTING IN ROCK EXCAVATION Generally speaking, the natural rock is a relatively strong and competent structural material, if we conserve its inherent good properties and perhaps reinforce its weak spots. The difficulty often lies in blasting out the tunnel or chamber without damaging the walls and roof we wish to have remain afterwards. Much progress has been made in the last five years in better understanding the controlled excavation of rock. The specialized techniques known as smooth wall blasting and presplit blasting have now developed from the status of curiosities of rock excavation to the point where these techniques are specified in contracts drawn up for such rock excavation projects as tunnels, underground pourer houses, etc. These techniques have been well described and discussed in previous publications; there is no need to reiterate here. It might be well to point out that recent research has demonstrated the effect that inherent rock stress may have on presplitting in certain directions. Material can be presplit most readily parallel to the direction of maximum compressive stress, and this may not always be in the direction desired. Inherent rock stress measurements by stress relief over coring, etc., may have important value in deciding how to best presplit proposed excavations. In addition, recent work at the Colorado School of Mines has demonstrated the feasibility of con-

Jan 1, 1967

By R. E. Somers

Discussion of the paper of R. E. SOMERS, presented at the San Francisco meeting, September, 1915, and printed in Bulletin No. 101, May, 1915, pp. 957 to 996. A. C. LAWSON, Berkeley, Cal.-One point to which Mr. Graton (in summarizing the paper for us) called attention is that the author had not explained why some copper was fixed in the zone of oxidation. I recollect very well puzzling over that question at Ely, Nev., some years ago. Mr. Sales, in his paper on Butte,1 suggests the explanation. It is clue according to him to the paucity of pyrite in the primary ore. Where there is abundant pyrite sufficient sulphuric acid is formed by oxidation to take all the copper into solution and carry it to lower levels; but where the pyrite is scant so that insufficient sulphuric acid is formed, some of the copper is carbonated and so fixed in the gossan. The hypothesis, or some modification of it, as for example the combination of the sulphuric acid with lime, would appear to explain satisfactorily the fixation of the copper in the gossan as carbonate. I have, however, had no occasion in recent years to study the phenomenon. L. C. GRATON, Cambridge, Mass.-As I remember, the rocks in which the chrysocolla occurs in the Burro Mountains are both silicified and kaolinized. It seems probable that in surroundings deficient in carbon dioxide, complete oxidation of chalcocite may yield chrysocolla up to a maximum of half the copper in the chalcocite; while in rocks, like garnet contact zones and certain easily decomposable porphyries, surface decomposition appears often to yield silica in the necessary form to convert the copper of primary sulphides into chrysocolla immediately and directly upon oxidation.

Jan 12, 1915

By A. U. Seybol

Eight binary iron alloys were examined after ion nitriding experiments to determine the behavior of the following elements: Al, Mo, Mn, Si, Ti, V,Cr, and C. Only Al, Cr, Ti, and V additions caused hardening in binary iron alloys. A few steels were examined to see the effect of Cr, Cr + Al, Cr + Ti, and Cr + V. It is suggested that a useful new class of ni-triding grade steels might be those containing about I pct V. The nitriding of steel, first described by Fry1 about 45 years ago, rapidly attained commercial application with very little knowledge of the fundamentals involved. While Fry,' in describing the status of nitriding in 1932, apparently correctly postulated hardening by precipitated nitrides, the details of the nitriding process were not understood, nor has the situation changed much since that time. It is also interesting to note that the compositions of some typical nitriding steels given by Fry at that time have changed little in the intervening years. Currently used nitriding steels owe their surface hardening to either chromium (as in 4340 steel) or aluminum plus chromium as in the Nitralloy grades, where both CrN and AlN appear to contribute to harden ing. Titanium additions have been studied experimentally, but thus far titanium steels have not won wide commercial acceptance. This subject will be expanded later. The orthodox ammonia nitriding process has been reviewed very adequately many times as in Jenkins3 and Case and VanHorn,4 and their is no need to outline the process here. Ion nitriding is not as well-known, although there have been several descriptions5-9 of the process given, sometimes with comparisons with the ammonia process. Most of these papers are primarily concerned with a description of the equipment, or of the physics or electrical engineering aspects of ion nitriding, but Noren and Kindbom9 gave the results of a metallurgical investigation using both processes. In brief, ion nitriding is carried out in a vacuum chamber from which the air is exhausted and replaced by a N2-H2 mixture, typically containing 10 to 20 pct N2, at about 5 to 10 torr pressure. While ammonia gas has also been used in ion nitriding, there is no evidence that ammonia makes any improvement in the ion nitriding process. A few hundred volts dc is applied between the grounded container wall (positive) and an insulated center post supporting the work (negative) to be nitrided. A glow discharge is created in the ionized gas, accelerating positive nitrogen ions to the work. These ions contain enough energy to form the normally unstable Fe4N "white layer", thus establish- ing surface nitrogen solubility characteristic of the a Fe/Fe4N equilibrium. This creates a substantial concentration gradient, driving dissolved nitrogen into the steel. The temperature employed is in the same range (around 500" to 550°C) as in ammonia nitriding, but because of factors which are not understood at present the nitriding time is ordinarily considerably reduced in ion nitriding. Other advantages have been cited,9 but it is not the purpose of the present work to contrast the two processes. The present objective was to examine the behavior of binary iron alloys during ion nitriding with respect to the microstructure, hardness level, and depth, and to examine some of these factors in steels as well. In this way it was hoped to be able to find out something about the individual role of these elements in steels. While all the work was done by ion nitriding, there seems to be no reason why any conclusions reached would not equally apply to ammonia nitriding, excepting only the kinetic aspects of the process. Another objective was an exploration of the critical-ity of the ion nitriding variables: gas composition, pressure, temperature, and time. EQUIPMENT AND MATERIALS The equipment used was substantially as described by Jones and Martin.8 The vacuum tank was about 12 in. in diam by about 18 in. high, and consisted of water-cooled stainless steel, with a single small window at the top for viewing inside. This sat on a heavy mild steel base equipped with the main pumping port, pressure control port, and vacuum gaging. A series of variable resistances was interposed between the glow discharge and a large-capacity -40 amp variable primary transformer feeding a 1000-v transformer, but 600 v were about the maximum ordinarily used. With the small l-in.-round, 4-in.-thick discs used for nitriding, the electrical load was usually about 500 v at 0.8 amp. The specimen temperature was controlled by a stainless-steel sheathed chromel-alumel couple, whose junction was in the steel stool upon which the flat discs were placed. These were ground through 400 Sic paper. Cycling of the temperature controller caused -0.2 amp variation in ion current, providing an ample control band. The binary iron alloys were made from vacuum-melted hydrogen-deoxidized electrolytic iron and alloys of 99.9 pct purity. Cast ll-lb-square tapered ingots were forged and hot-rolled to about 11/4-in.-diam rounds. Discs of 1/4 in. thickness by about 1 in. diam were machined from the rods for nitriding specimens. The following alloys were prepared: 1 pct each of Mn, Mo, Cr, Ti, Al, V, Si, and an Fe-0.8 pct C alloy. EXPERIMENTAL VARIABLES Of the variables total gas pressure, nitrogen partial pressure, temperature, and time, only nitrogen partial pressure was found to be critical to the operation. A critical nitrogen partial pressure was found corre-

Jan 1, 1970

By Michael P. Richardson

INTRODUCTION This paper is intended to be a summation of the state-of-the-art i n draw theory and draw- point spacing. Knowledge of this very important factor in the successful design and operation of a block caving mine is scarce and nonconclusive. It is hoped that the presentation of this paper will stimulate interest and discussion which will lead to a stronger understanding of these a1 1 important factors. Please note that block caving as used here- in refers to block, panel, and mass caving systems in general, not just to the specific system of block caving where discrete blocks of ore are prepared and caved as a unit. DRAW THEORY The knowledge of draw theory as related to the practice of block caving mines is, unfortunately, very limited. In recent years much work in draw theory has been done in respect to sublevel caving systems and an understanding of draw mechanics relating to sublevel caving seems to be emerging. This work is certainly helpful to those of us interested in block caving but the question of "what goes on up above" still hounds us since we are more interested in the region of draw which begins just above the area where sublevel caving interest ends. Herein is presented a brief summary of draw theory with an attempt to look at the factors which can help our understanding of the area of draw influence in block caving mines. Nature of Gravity Flow An understanding of the flow of granular material (rock, sand, grain, or prill as examples) is the first step toward understanding block caving draw. If we take a supported column of granular material and allow gravity flow through an aperture at the bottom of the column, an ellipsoidal shaped zone of disturbance of the in-place material will form and grow with extraction of material through the aperture. The volume of this zone of disturbance or loosening is about 15 times the volume of material extracted at any given time (Kvapil, 1980). Figure 1 shows the development over time of the zone of disturbance. The ellipsoid of disturbance represents a future ellipsoid of extraction which will equate to the volume of materia1 extracted by that future time. Extraction involves the movement of the particles located vertically over the drawhole directly downward while material outside this direct vertical volume moves radially inward and down toward the drawpoint as shown in Figure 2a. Figure 2b shows the result of this motion on originally horizontal strata within the ore column. Increased draw increases the eccentricity of the ellipsoidal volume or, in other words, the ratio of the height over the width of the disturbed area increases as ore is withdrawn from the column (Kvapil , 1980). This becomes important to block caving since eventually a vertical cylinder of draw will be approximated as this ratio increases without bounds. Figure 3 shows this result. The width of this draw cylinder is a critical dimension for the determination of draw point spacing in relationship to block caving mine design. McCormick (1968) for one, felt that within this cylinder of draw, mass flow would take place. This is the

Jan 1, 1981

By E. Just

The mining industry is guaranteed an important future because its products are indispensable. However, this can be anything from a brilliant, efficient, profitable future to one of being a heavy-handed, dull-witted claimant for public handouts, according to the caliber and training of the young men who enter the industry. Many views have been expressed about the type of education needed for today's mining industry. Criticisms have been aired to the point that further controversy amongst ourselves could be detrimental to both mining education and the mining industry. It is time we get together and start going somewhere. To canvass the various attitudes of mining educators, a questionnaire was sent to a group of these dedicated, intelligent men, whose primary interest is to help the industry and the profession. The following is a summary of their views.

Jan 9, 1961

By C. E. Violet, R. J. Borg, E. M. Howard

The miscibility gap in the Au-Ni system has been determined by Mossbauer spectroscopy, with used as a probe. The phase boundaries were determined from the compositional dependence of both the isomer shift and Curie temperature. X-ray diffraction measurements were also used to confirm the Mossbauer results. 1 HE purpose of this research is to demonstrate the application of Mbssbauer spectroscopy to the determination of phase boundaries and to redetermine the miscibility gap by an independent and novel technique. The techniques evolved in this study are readily applicable to other polyphase systems and are generally as quick and accurate as the more conventional methods, e.g., metallography, X-ray diffraction, thermal analysis, and so forth. To be sure, not all polyphase systems will lend themselves favorably to Mijssbauer investigations, but this is a problem met in the use of conventional methods as well. The Mbssbauer spectrum responds to a different set of physical parameters, and consequently provides an entirely independent method of analysis. It is especially useful if the system has either a ferromagnetic or an antiferromagnetic transition. The Au-Ni system was selected because alloys containing more than -60 at. pct Ni become magnetically ordered at low temperatures; also the miscibility gap is quite well established (see Ref. 7 for a compilation of pertinent references, also Fig. 11, and thus provides a reliable test of this novel procedure. As Fe is the most commonly used Mijssbauer isotope, there exists a wealth of information concerning its behavior in iron-containing alloys and compounds. However, as yet there have been relatively few experiments using it as a probe to investigate nonferrous systems. By choosing a nonferrous alloy system, we are able to demonstrate that its use is not restricted to systems containing iron as one of the major constituents. Wertheim and ~ernick' have used the same method to investigate Cu-Ni, and demonstrated that one can obtain a systematic variation in the isomer shift and magnetic hyperfine field. However, we believe this to be the first time these techniques have been used to establish phase boundaries. Two hyperfine interactions were measured and used to determine the phase boundaries, viz., the magnetic hyperfine splitting and the isomer shift which in this alloy system are both strong functions of composition. Calibration curves were established based upon single-phase solid solutions obtained by quenching from temperatures well above the maximum of the miscibility gap, see Fig. 1. Solid solutions containing 25, 50, 65, 75, 85, 92, and 96 pct Ni as well as pure nickel were used in the calibration procedure. Fig. 2 shows the Curie temperature, TC, and the isomer shift, v,, as determined from the Mbssbauer spectra, and variation in lattice parameter as determined by X-ray diffraction, as functions of composition. The compositions of the two-phase systems quenched from temperatures within the miscibility gap are obtained by comparing their respective values of TC and v0 with the calibration data. I) EXPERIMENTAL Mbssbauer sources were made by fusing the component metals in a tungsten arc melter, which has a water-cooled copper hearth. Both nickel and gold were 99.999 pct pure, and the melting was done in an atmosphere of purified argon. The alloys were rolled, diced,

Jan 1, 1969

(Members are urged to send in for this column any notes of interest concerning themselves or their fellow-members) Members and guests who called at Institute headquarters during the period Feb. 10, 1917 to Mar. 10, 1917: F. H. Armstrong, Vulcan, Mich. G. Komar, Staten Island, N. Y. Franklin Bache, Philadelphia, Pa. H. M. LaFollette, LaFollette, Tenn. R. A. Bingham, W. Orange, N. J. H. Mortimer-Lamb, Montreal, Canada. G. S. Blair, Pittsburgh, Pa. J. S. Lane, New York, N. Y. Graham Bright, Pittsburgh, Pa. D. H. McLaughlin, Cambridge, Mass. C. A. Burdick, New York, N. Y. F. J. McMahon, Wilkes-Barre, Pa. Frederick P. Burrall, Dawson, Y. T. F. Oskar Martin, San Francisco, Cal. William Campbell, New York, N. Y. C. Mentzel, New York, N. Y. G. L. Carlisle, Jr., New York, N. Y. T. C. Merriman, New Haven, Conn. J. Murray Clark, Toronto, Canada. K. -A. Pauly, Schenectady, N. Y. Wayne Darlington, Philadelphia, Pa. , Francis R. Pyne, Elizabeth, N. J. Ralph W. Deacon, Elizabeth, N. J. C. S. Robinson, Youngstown, O. P. St. Jon Dixon; So. Porcupine, Canada. W. A. Scheuch, New York, N. Y. A. E. Drucker, New York, N. Y. Jesse Scobey, New York, N. Y. Lucien Eaton, Ishpeming, Mich. Dunbar D. Scott, Rochester, N. Y. W. E. Goldsborough, New York, N. Y. W. C. Smith, Elizabeth, N. J. C. Marshall Gravatt, Port Royal, Va. Charles Spearman, Mt. St. Patrick, Can. C. N. Hickok, Cleveland, O. . - Harold C: E. Spence, Duncan, Ariz. C. Vey Holman, Rockland, Me. M. M. Thompson, Morsemere, N. J. W. F. Jahn, Kirkland Lake, Canada. Benjamin F. Tibby, Salt Lake City, Utah. F. E. Johnesse, Boise, Ida. J. S. Unger, Pittsburgh, Pa. E. C. Johnson, Chicago, Ill.

Jan 4, 1917

By Jacques B. Wertz

Even with the best geological maps, there is a constant need for further information and a constant demand for new clues, particularly in exploration work. New ideas and new thoughts are a necessity for progress. In the structural study of an area, be it in Arizona, Africa, or British Columbia, the basic fracture pattern has to be determined first. There is, however, no assurance that the trends shown on the map are really meaningful because they often are secondary in nature, having occurred as a consequence of an intrusion, of doming, or of gravity faulting. Thus, such trends often are a weak basis for assuming the presence of ancient and important zones of fractures that could constitute useful guides to mineral exploration.

Jan 6, 1969

By Robert F. Brindisi

There are approximately thirty to forty operating mills in the United States which are currently producing uranium yellow cake. This figure includes a significant number of in situ and by-product operations however the conventional acid leach flowsheet depicted in Figure 1 is the most common process used by domes- tic yellow cake producers. Ground ore is leached with sulphuric acid and the solids are separated from the pregnant liquor and washed in a series of counter- current decantation thickeners. After clarification of the pregnant liquor, uranium is recovered from the solvent extraction/stripping circuit by the addition of ammonia with precipitation of ammonium diuranate, or simply yellow cake. The yellow cake precipitate is then thickened in a conventional thickener before re- porting to the dewatering/washing unit operation. De- watered solids subsequently report to thermal drying, and clarified liquor from the dewatering/washing step is recycled to the yellow cake thickener. The yellow cake dewatering/washing unit operation is generally accomplished using either a solid bowl centrifuge or a rotary vacuum drum filter. In most cases the underflow from the yellow cake thickener is pumped to the dewatering/washing unit operation at approximately fifteen to twenty percent solids. For the purpose of this discussion ammonium diuranate, the product of ammonia precipitation from a conventional acid-leach uranium mill flow sheet, as discussed earlier, will be considered. With only slight adjustment this discussion will be equally applicable to sodium diuranate or uranium perioxide precipitates and to either in situ or by-product operations where such precipitates are generated. Some of the domestic uranium mills which have selected solid bowl centrifuges instead of vacuum drum filters for the dewatering/washing unit operations are listed in Figure 2. Why have these uranium mills, as well as others not listed, chosen to use the solid bowl centrifuge for this particular application? It is simply a matter of performance, reliability and economics. In the remainder of this paper the performance, initial cost, installation cost, maintenance and power consumption of both the solid bowl centrifuge and the rotary vacuum drum filter will be com- pared. In order to provide a consistent basis for comparison the appropriate sized (centrifuge or filter) unit for the dewatering/washing of 400 to 500 pounds per hour of yellow cake solids will be considered. Such a flow will usually be generated by a typical 3,000 ton per day (acid-leach) uranium mill.

Jan 1, 1980

By W. R. Phibbs

The blast furnace of the Columbia Steel Corpn., at Ironton, Utah, was put in blast April 30, 1024, and its operation has presented some interesting problems. The coke for the furnace is furnished by 33 Koppers Becker type ovens of 15 tons capacity each. The coal is shipped from the company's mine at Columbia, Utah, which is approximately 123 miles from Ironton, and is probably the highest volatile coal that is being coked for blast furnace use in this country. The analysis of the coal is: PeR Cent. Moisture................................................. 3.90 Volatile.................................................. 39.00 Fixed carbon............................................ 51.10 Ash............................................... 6.00 Sulfur................................................. 1.07 The analysis of the coke is: PeR Cent. Volatile.................................................. 0.55 Fixed carbon............................................. 89.70 Ash...................................................... 9.75 Sulfur................................................... 1.05 The coke is light and of a fingery construction, but is very fast burning. A screen test of the coke as loaded into the skip tubs at the furnace shows the following: Per Cent. On 2 in.................................................. 17.90 On 11/2 in................................................ 41.78 On 1 in.................................................. 27.80 Through 1 in............................................. 12.52 The by-product yields are as follows: Gas................................. 11,000 cu. ft. per ton of coal Sulfate............................... 30 Ib. per ton of coal Tar.................................. 12.65 gal. per ton of coal Motor fuel........................... 3.00 gal. per ton of coal Average B. t. u. in gas................. 567

By Frederick V. Lawrence

Broadly speaking, fluxes are substances which promote wetting and spreading or enhance the fluidity and manipulative properties of materials in joining, fusion, and smelting operations. The term most strictly applies to substances used to facilitate soldering and brazing; but in the discussion which follows, the definition will be broadened to include materials used to promote fusion in arc welding and which aid in the smelting of metals. In each of the mentioned applications, the role of flux and its composition differs considerably; consequently in the discussion which follows, fluxes for soldering, brazing, arc welding, and smelting applications will be considered separately. Soldering and Brazing Fluxes Soldering and brazing are metallurgical joining processes in which a joint is formed using a filler metal of composition dissimilar to that of the joined pieces (base metal). The filler metal, solder or braze, is always of lower melting point than the base metal. Consequently with these processes there is no melting of the base metal. The successful creation of the joint depends upon the wetting and spreading of the solder or braze around or throughout the joint. The obstacles to successful soldering and brazing are contaminants and tenacious oxide films on the metal surfaces. In soldering and brazing applications, fluxes act to remove and exclude oxides and other impurities from the joint. There is no fundamental difference between soldering and brazing. The distinction between them is made on the basis of temperature. Join¬ing operations carried out at temperatures above 500° C are termed brazing. The higher temperatures used in brazing enable higher melting point filler metals to be used which generally provide stronger joints. The higher temperatures of brazing processes also require fluxes which are substantially different from those used in soldering and which will remain effective at high temperatures. Consequently the distinction between soldering and brazing can also be made on the basis of the fluxes used. Soldering Fluxes Even thoroughly cleaned and degreased, metal surfaces still possess tenacious oxide films which inhibit the soldering of the joint. The reactions which form these films increase with increasing temperature. The rate of oxide formation and the tenacity of the film varies with each base metal. Aluminum, magnesium, stainless and high alloy steels, aluminum and silicon bronzes when exposed to air form hard, adherent oxide films. These metals require highly active and corrosive fluxes to remove and prevent the reformation of oxide films during soldering. Metals such as copper and silver, on the contrary, form less tenacious films at a lower rate, so that mild fluxes are sufficient. Soldering fluxes must dissolve or remove oxides and promote rapid wetting and spreading of the solder. The flux removes the oxide film by loosening and floating it off into the main body of the flux. The oxide removal is often aided by the alloying of the solder with the base metal, undermining small areas of the oxide and detaching them (Anon., 1959). The flux coagulates and suspends the oxide particles which have been loosened. The flux forms a protective cover preventing the reformation of the oxides, permitting the spreading of the solder and the formation of a metallic bond between the solder and the base metal. Constituents of Soldering Fluxes: Soldering fluxes are commonly grouped into three categories: highly corrosive, intermediate, and noncorrosive. One normally would choose to use the least corrosive flux which will give satisfactory performance.

Jan 1, 1983

By Paul K. Krueger

SUMMARY Since 1970 the Federal Preparedness Agency has been using computer models to help establish the amounts of strategic and critical materials to be held in the National Stockpile. Fifty-three of these materials are metals or minerals. The following diagram shows the linkage of models used to estimate material requirements. [ ] The starting point for the models are estimates of the major components of GNP for some future period. These may be estimates purchased from a forecasting service or may be produced in-house. The projections are translated into industrial final demands using DITT (Demand Impact Transformation Tables), a system developed at FPA. Then using a version of the current Bureau of Economic Analysis input-output model, estimates are made of the gross output of each industry necessary to support the level and composition of GNP as specified by the macro-economic model.

Jan 1, 1977

By C. D. Hunter, J. B. Browning

During the year 1934, Kentucky oil and gas operators have partly overcome their past depression fears and in the oil industry, with possibly more abandonments of old oil producers than the completion of new oil wells, produced 4,814,904 bbl. of oil in 1934 against 4,501,511 bbl. in 1933. In the gas industry of eastern Kentucky, 115 gas wells were completed during 1934. This production is delivered through two 20-in., one 16-in., one 12-in., one 10-in., and two 8-in. pipe lines to supply both domestic and industrial markets in Cincinnati, Ohio; Louisville, Lexington, Frankfort, Winchester, Ashland, Covington and other Kentucky towns; Washington, D.C., and other eastern cities. The largest percentage of these gas wells and production are from the Devonian black shale area of Floyd, Pike, Knott, Martin and Magoffin counties, Kentucky. In this area the largest percentage of 1889 wells, developing 421,-215 acres, has been completed in the past 10 years, of which 55.3 per cent produce from the 400 to 550 ft. of Carbonaceous Devonian black shales. The successful results obtained from these Devonian shales are due to the physical effects of the 5000 to 6000 lb. of gelatinated nitroglycerin with which the entire 400 to 550 ft. of shale is shot. A very small number of the shale wells are natural producers and do not require shooting. Other than the Devonian shale gas production, the remaining 44.5 per cent of the gas in this field is encountered throughout the entire strati-graphic section above this horizon; namely, salt sands of Pennsylvanian age and Maxon, Big Lime and Weir of Mississippian Age. A very small percentage is encountered in the Corniferous Devonian lime and the Silurian Big 6 below the black shales. In western Kentucky, in the counties of Henderson, Webster, Hopkins, McLean, Christian, Muhlenburg, Ohio, Daviess, Hancock, Brecken-ridge, Hart, Barren and Warren, many gas wells have been completed, but, because of insufficient market, activity has been somewhat desultory. The area is served by the pipe lilies of the Kentucky Natural Gas Corporation, with headquarters at Owensboro. Their market is increasing and the gas is delivered to Owensboro, Henderson, Madisonville, and many

Jan 1, 1935

By Joseph Pogue

IT IS well known that one of the cornerstones of economic theory is the so-called law of supply and demand, which, really, is a group of economic laws, one of which may be succinctly stated : A rise in price tends, sooner or later, to increase supply. It is the fear that, in the case of petroleum, a limited natural resource, a point will soon be reached when supply will not respond adequately to price advances, which in recent years has prompted a movement for oil conservation. This movement has lately taken concrete shape in the appointment of a Federal Oil Conservation Board by the President. An important aspect of the law of supply and demand is that the supply of any commodity is not an entity per se, but is a factor of price. Supply, without the specification of price, has no exact meaning; and in practice supply cannot be divorced from considerations of price. Mathematically, supply may be expressed by the formula SP, which means that supply varies with price, just as the value of 10 raised to the x power varies with x. In its technical usage, supply is the quantity of a commodity that is bought currently on the market at a given price. In the case of a natural resource, however, this quantity will eventually depend not alone on price but on the physical volume of the reserve that exists and. that, in consequence, can respond to the stimulus of price. If this reserve is fixed in size, we must sooner or later reach a point where supply can no longer respond to price in the usual degree and a permanent shortage. will develop which no advance in price can correct, except in so far as higher prices may curtail demand or improve the efficiency of utilization.

Jan 3, 1925

By Peter N. Calder, Alan Bauer

INTRODUCTION One of the most important decisions involved in the design of an open pit mine is the selection of a slope angle. Despite this fact, engineering procedures have developed slowly in this field. Only recently have the instruments and know-how become available to undertake a design based on sound engineering principles. The effect of blasting on open pit slope stability is one aspect in which the state of the art has not developed fully. These effects include: a) the effects of the ground motion associated with blast waves on slope stability, and b) the fracturing of rock in the vicinity of slopes caused by blast waves. Natural rock jointing plays an important role in both of these. SUMMARY OF BLASTING EFFECTS In recent years there has been a trend to larger sizes of blast holes in open pits to the extent that today 9% in. and 12% in. diam. holes are the most common. The reasons for this have been economic. Larger machines are more efficient and produce at a lower overall cost per ton. As the size of blast holes have increased, so have the other factors associated with blasting. Bench heights have increased, the tons/ft. of hole yield has risen significantly and the explosive load per hole has increased. Quite naturally the rupture radius for a single blast hole has increased along with the vibration level produced per blast hole. Open pit blasting operations can result in two types of unwanted damage: 1. Damage to structures, such as buildings, dams and slopes by ground vibrations initiated by the blast. 2. Fracturing of ground beyond the planned excavation limits. Let us first consider item one. Vibration effects are determined by the type of blast which is fired and the type of medium through which the blast wave is being transmitted. They are strongly influenced by the weight of charge per hole, the number of holes per delay, the distance from the shot point, the mode of initiation, the point of interest relative to the blast, etc.

Jan 1, 1971

By Gerald Edmunds

THE liquidus line on the phase diagram for temperature versus composition of a binary alloy system, representing the boundary between the homogeneous melt and the heterogeneous melt plus solid, besides showing the minimum casting temperature, is useful in determining eutectic compositions and the presence of phase changes such as peritectic transformations and intermetallic compound formation. The liquidus often is determined by the cooling curves of thermal analysis, but supercooling frequently occurs, so that the temperature values are low. An alternative method, the one employed here, consists of determining the com- position of samples of the melts from heterogeneous alloys that are at equilibrium. With meticulous attention to fundamentals, this method is capable of yielding values limited in precision only by the temperature control and measurement and analyses. APPARATUS By starting, on the one hand, with a supersaturated solution and allowing the excess solute to precipitate, and on the other hand with an undersaturated solution and allowing more of the solute to be dissolved, both processes being carried out at the same temperature, equilibrium may be said to have been approached from both directions; that is, from above and from below. If the analyses show the solutions to contain the same fraction of solute when equilibrium has been approached from above and from below, one is assured that equilibrium has been reached in both determinations. In order to carry out such determinations, it is necessary to have equipment for obtaining and maintaining the proper temperatures; for holding the melt, measuring its temperature, and stirring, sampling and analyzing it. The present work required temperatures from 420° to 900°C. The equipment consisted of: A furnace, which was a vertical alundum tube, 1 ¾ in. diameter inside and 18 in. long, wound with Nichrome resistance wire, surrounded by a 3-in. i.d. alundum tube wound for 5 in. of length near each end, for compensation of end losses. This muffle was contained in an iron shell with Transite end plates, the intervening space being packed with Sil-O-Cel. The outside dimensions of the furnace were 12 in. in diameter by 18 ½ in. in height. Heating current was supplied by three independent variable-voltage transformers (Variac), one connected to each end compensator winding and manually controlled, and one connected to the main winding through a series resistance of 5 ohms. This resistance was short-circuited for

Jan 1, 1944

By J. Gordon Parr, A. J. Goldak

OgdEN et al.1 and Bumps et al.2 suggested that the solubility of aluminum in a titanium extended to 30 pct.* Sagcl,3 Clark and Terry,4 Anderko et al.,5 Ence and Margolin6 and Saulnier and croutzelles,7 subsequently proposed the existence of an intermetallic compound in the region of 25 pct Al. Although Anderko et al.5 suggested that the structure of this phase, Ti3Al, was of the DO,, (Ni3Sn) type, their conclusion was based only upon the results of a powder photograph that included reflections from ? = 0 to ?= 27° (CuK),some of which were reported to be indistinct. Ence and Margolin,6 referring to a 25 pct alloy (but without indicating whether the figure referred to weight or atomic pct) stated: "The structure of Ti2Al is isomorphous with Ti3Sn DO19, as pointed out by Pietrokowsky". But the point was not proven, because Ence and Margolin did not report values of calculated intensities of Ti2Al with the DO,, structure. In fact, the observed intensities they reported are in poor agreement with the values we calculate for DO19 (see Table I). Saulnier and croutzelle7 concluded, on the basis of electron micrography and microdiffraction studies, that the structure of the 25 pct A1 alloy was ordered hexagonal. Our purpose has been to unequivocally determine the Ti3Al structure. Alloys containing 25 pct Al were prepared from iodide titanium and spectrographic standard aluminum by levitation melting. The levitation chamber was evacuated to 10-6 mm Hg before filling with 99.999 + pct A. After casting, the alloy was chilled to liquid air temperature and crushed to -200 mesh in a percussion mortar. The powder, wrapped in molybdenum foil, was annealed (by induction heating) at 1000 "C for 2 hr in the argon atmosphere of the levitation chamber. No sublimate was seen on the foil or elsewhere, and therefore the assumption is

Jan 1, 1962

By Harry H. Power

While the attention of all engineering branches is focused today on changes and improvements in the several curricula, we are concerned here with the many questions arising in industry and college concerning the preparation for the petroleum engineering profession. The succession of problems confronting the petroleum engineer demands a degree of versatility not ordinarily encountered in other professions. As a consequence, the student cannot acquire mastery of all the several engineering branches represented in field practice, and as an alternative, he has learned to appreciate the value of thorough training in the basic or fundamental sciences as a Preliminary foundation for professional work. While our attention is directed primarily to the training of engineers in educational institutions, it is necessary that the ultimate education of the professional engineer be kept in mind. It is apparent that his success as an engineer is limited not only by his educational and job experience, but by his native endowments: mentality, Personality and health. The engineer's lack of job experiences often proves as much a handicap as the lack of adequate college training. If the final product proves to be satisfactory, both industry and technical institutions are to be congratulated. However, if the Product is found wanting, the one most responsible should For the most part, students of engineering colleges have had their interests in applied science awakened at a relatively early age. Manyof them entered college as a convenient means of acquiring a technical education, but undoubtedly would have had better prospects in a shorter program offered by institutions of non-college grade. The activating motive of practical interest is also strong in students suitable for college training, but in many cases an intellectual interest must be awakened in order that it may survive graduation. Numerous engineers believe that this progressive process of selection and determination of career aims is one of the essential services rendered by the engineering colleges. Industrialists, who are more inter. ested in quality than quantity of petroleum engineering graduates, have pointed out the good that should result if more emphasis were given to the work of eliminating the misfits. They also point out the protective measures that have been taken by other professions for the betterment of professional standards. Mention has been ,de of the beneficial results to be obtdned by collective determination of the market for the products of engineering schools, particularly in that the students unsuited to the profession would have an opportunity to prepare themselves for employment more suited to their personalities and other qualifications. In the event that such a system of coordinated personnel direction is developed by the

Jan 1, 1941

By Harry H. Power

While the attention of all engineering branches is focused today on changes and improvements in the several curricula, we are concerned here with the many questions arising in industry and college concerning the preparation for the petroleum engineering profession. The succession of problems confronting the petroleum engineer demands a degree of versatility not ordinarily encountered in other professions. As a consequence, the student cannot acquire mastery of all the several engineering branches represented in field practice, and as an alternative, he has learned to appreciate the value of thorough training in the basic or fundamental sciences as a Preliminary foundation for professional work. While our attention is directed primarily to the training of engineers in educational institutions, it is necessary that the ultimate education of the professional engineer be kept in mind. It is apparent that his success as an engineer is limited not only by his educational and job experience, but by his native endowments: mentality, Personality and health. The engineer's lack of job experiences often proves as much a handicap as the lack of adequate college training. If the final product proves to be satisfactory, both industry and technical institutions are to be congratulated. However, if the Product is found wanting, the one most responsible should For the most part, students of engineering colleges have had their interests in applied science awakened at a relatively early age. Manyof them entered college as a convenient means of acquiring a technical education, but undoubtedly would have had better prospects in a shorter program offered by institutions of non-college grade. The activating motive of practical interest is also strong in students suitable for college training, but in many cases an intellectual interest must be awakened in order that it may survive graduation. Numerous engineers believe that this progressive process of selection and determination of career aims is one of the essential services rendered by the engineering colleges. Industrialists, who are more inter. ested in quality than quantity of petroleum engineering graduates, have pointed out the good that should result if more emphasis were given to the work of eliminating the misfits. They also point out the protective measures that have been taken by other professions for the betterment of professional standards. Mention has been ,de of the beneficial results to be obtdned by collective determination of the market for the products of engineering schools, particularly in that the students unsuited to the profession would have an opportunity to prepare themselves for employment more suited to their personalities and other qualifications. In the event that such a system of coordinated personnel direction is developed by the

Jan 1, 1941

By R. H. Richards

The spitzlutte, as described by Rittinger, is an instrument by which saud is sorted in a continual upward-flowing stream of water. Its usual firm is that of a pointed box, placed with the point downward, the box receiving. its feed of sand and water on one side and discharging its tailings on the other. The sorted product or concentration is discharged at the bottom, at the apex of the box, through which it falls against an upward current of water, which current serves to effect the sorting and separation. To make this exposure to the quicksand condition still more effective, an inverted dam is placed across the spitzlutte, which forces the sand in its passage from the feed side to the discharge to pass clown into the more active portion of the upward-flowing current of water. In the form adopted for small tests in the mining laboratory of the Massachusetts Institute of Technology (see accompaaying sketch) the feed is'throogh a central funnel instead of being at the side, and the apex of this funnel, extending down nearly to the apex of the cone, talks the place of the inverted dam in the large spitzlutte. To keep the experiment perfectly under control a bulb or bottle is attached by a rubber connecting-tube to receive the concentrations, and between this bottle and the apex of the spitzlutte is placed a glass tube of conical form, with a side tube for' the admission of water. By regulating the admission of water through this tube the concentration may be allowed to go down into the bulb as fast or as slowly as the richness of the ore seem.; to demand. This spitzlutte may be used on products that have been previously sized to take out the heavy mineral. As an example of this a test was made upon a sample of ore where the galena, blende, and quartz were much mixed up, but separated fairly when crushed. The sample of ore was from Newburyport, and assayed 16.61) per cent. lead.. After sizing through a series of sieves the ore yielded conceutrations and tailings to the spitzlutte as follows :

Jan 1, 1881