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By Robert :H. . Lesemann

I recently gave a talk at a seminar on mine development in the Eighties. I had to present CRU' s long-range market outlook for copper, lead, zinc, nickel, molybdenum and silver. In reviewing the recent history of each metal, and our projections, I tried to find some common pattern of behavior that could prove a guide in projecting future market behavior. When you sweep aside your input-output models and econometric equations, what you seem to be left with is this: "When a market goes through a prolonged period of price weakness, you can usually look forward to a period of considerable improvement. " "When a market goes through a prolonged period of price strength, you can always anticipate a prolonged period of price weakness." Stated another way, "The better things are, the worse they will get."

Jan 1, 1982

By Oliver Bowles

DELICATE PLANTS are now put to bed for the winter under glass-wool or rock-wool blankets. Thus arise new and unexpected uses for non-metallic materials and rocks and, at the same time, certain unique uses are fading out; for instance, the Italians have taken steps to bar the use of salt for money in Ethiopia. Novel sources of supply find a place in the record of recent achievements as exemplified in the migration of the frontiers of industrial mineral exploitation beyond the land area of the earth to include the ocean. Salt, of course, has been recovered from the sea for years but the treatment of enormous quantities of sea water for bromine has lately added to the importance of the ocean as a reservoir of mineral wealth. Increased use of non-metallic minerals in the commercial and economic life of the country is reflected in the wide scope and activity of the Industrial Minerals Division of the Institute. The outstanding recent achievement of the Division is the publication of a 955-page volume on industrial minerals and rocks, comprising 48 commodity chapters each written by an authority on the subject.

Jan 1, 1938

By Michael S. Koleda

Less than two years ago, the, Congress, with broad bipartisan support, passed the Energy Security Act of 1980. A decade marked by ten- fold increases in world oil prices and two major interruptions in oil flows from the Middle East had ended. An all-out national commitment to transform America's vast tar sands, oil shale and coal resources into conventional fuels had begun. The national synfuels effort was to be public-private cooperation at a scale unmatched in peace time. Private industry would own and operate the synthetic fuels facilities. Government would reduce market uncertainties to acceptable levels. The potential government commitment was substantial. Up to $88 billion would be available through the Synthetic Fuels Corporation, principally in the form of contingent financing. Billions more would be spent through Department of Energy programs. Additional incentives for alternate energy development were contained in the Energy Tax Act of 1978. The Energy Security Act clearly specified national synthetic fuels production objectives: 500,000 barrels per day by 1987 -- 2 million barrels per day by 1992. Finally, said Congress, Uncle Sam was going to do something about rapidly rising oil prices, uncertainties of energy supply, and the resulting disruption to the U. S. economy. Simply put, the purpose of the Energy Security Act of 1980 was to provide government guarantees sufficient to get synthetic fuels projects off the private sector drawing boards and into commercial production. Because of their huge cost, technological uncertainty, and lengthy pay-out period, these projects were always second place to projects of smaller size, known technology and more rapid pay-out. The Energy Security Act was the legal expression of public policy to bring the free-market synfuels timetable into line with the faster paced political timetable in the interest of national energy security.

Jan 1, 1982

By Oliver Bowles

PRICES of quartz sold in the United States in 1938 ranged from $1.15 to $36,000 a ton. This startling variation was due simply to the differences between glass sand and rock - crystal, materials that are virtually the same in composition. It illustrates the complexities in qualities, uses, and values of industrial minerals. It is generally stated that mineral deposits are exhaustible resources which can never be replaced when depleted. This statement is no longer true with respect to certain industrial minerals now recovered in increasing quantities from that most inexhaustible of all sources of supply, the ocean. Salt has long been obtained from sea water, particularly on the Pacific Coast, and reference was made a year ago to the large bromine recovery plant at Wilmington, N. C. Now the Westvaco Chlorine Products Corp. is operating a large plant at Newark, Calif., having a capacity sufficient to recover daily from the ocean raw materials that will produce 60 tons of various magnesium products. Lime is used to precipitate the magnesia from salt-water bittern. The products are chiefly magnesium carbonate for chemical uses, periclase and other refractories, and oxychloride cement for flooring.

Jan 1, 1939

By James H. TaVoularis, William J. Wiehagen

This paper discusses the application of commercially available microcomputers for assisting trainers in the delivery and evaluation of new hire, refresher, and occupational training. A brief overview of mine training highlights major issues facing the mine training community. The use of computer-based training has a potential for reducing costs and improving the transfer of conventional training to the job.

Jan 1, 1983

By Albert Sauveur

IT is not without some hesitation, and even misgiving, that I venture into a discussion of the now classical Roberts-Austen Roozeboom diagram, lest I too fail, like so many other writers, in giving a satisfactory and logical explanation of these interesting curves. Roozeboom's original diagram is reproduced in Fig. 1. The generally accepted meaning of the various curves has been so often described before this Institute that it will suffice to recall it briefly before passing to my own interpretation of the changes involved.

Nov 1, 1906

By Henry D. Hibbard

A NOTED ordnance engineer once said to a friend, in speaking of the production of great steel guns, "How is it? We design our guns with a factor of safety of eight, and the guns burst." The vague way in which internal stresses and strains in iron and steel are often considered and spoken of makes it worth-while to examine them, as to their nature, their causes and results, how they may, for useful purposes, be advantageously dealt with, and how, when detrimental or dangerous, they may be reduced or kept within harmless proportions. Rankine defines ?strain " as a change of form or dimensions of a solid or liquid mass produced by a stress. This definition seems not intended to cover strains due to internal stresses, and it will help us in the present inquiry to consider strain as a tendency to change as well as an actual change of form. Internal strains in iron and steel are the result of stresses within the mass of the piece, some parts pulling and others pushing in resistance to them; or, in other words, some parts are in tension and some in compression, each part striving to relieve itself from strain and make the piece assume a form in which all parts are at rest. Subdivision, so that each part could relieve its strain by motion relative to the other parts, would, if carried out far enough, practically obliterate strain. The internal strains we are now to consider are not those due to the stresses of the service which the piece is rendering, either alone or as, a part of a structure, which may be termed service-strains, but those which originate or at least are contained in the piece itself. Internal stresses in a piece of metal are, like action and reaction, always equal and in opposite directions. The stresses

Sep 1, 1906

By Joseph A. Holmes

I. INTRODUCTORY. THE plans for the investigation of fuels and structural materials now being conducted by the Technologic Branch of the United States Geological Survey were, before being decided upon by the Director of the Survey, submitted for consideration to the National Advisory Board, upon which there are nine representatives from the membership of the American Institute of Mining Engineers, viz.: Messrs. John Hays Hammond, Robert W. Hunt, B. F. Bush, and E. V. d'Invilliers (representing the Institute); Messrs. Julian Kennedy and C. S. Robinson (representing the Iron and Steel Institute); Dr. Charles B. Dudley (representing the American Society for Testing Materials); Mr. F. H. Newell (representing the U. S. Reclamation Service); and Dr. Richard Moldenke (representing the American Foundrymen's Association). It seems fitting, therefore, that a report of these investigations of the past three years should be submitted to the Institute for publication in its Transactions. The above, together with other representatives of the national engineering societies and allied organizations, were invited by President Roosevelt to serve, along with the Chiefs of the several Government Bureaus who have charge of public works and large. fuel purchases, on the National Advisory Board to give advice concerning these investigations. The appointment of this National Board grew out of a wish on the part of the President, the Secretary of the Interior, and the Director of the Geological Survey not only that the appropriations for these investigations be expended in a manner most beneficial to the several branches of the government

Jan 7, 1908

By F. G. Jones, R. D. Pehlke, H. E. Gardner

The solubility of nitrogen in liquid Fe-18 pct Cr-8 pct Ni-0. 7 to 2.3 pct A1 alloys has been measured up to the solubility limit for the formation of aluminum nitride in the temperature range 1600° to 1700°C uszng the Sieverts' method. The solubility of nitrogen in 18-8 stainless steel increases with increasing aluminum content. Based on a nitride composition, AlN, the standard free energy of formation of aluminum nitride from the elements dissolved in liquid 18-8 stainless-steel alloys has been determined to be: ?G° = -42,500 + 20. IT in the range from 1600° to 1700° C. EVANS and pehlke1 have measured the equilibrium conditions for the formation of aluminum nitride, AlN, in liquid Fe-A1 alloys. The present study extends that work to the more complex solvent, liquid 18 pct Cr-8 pct Ni (18-8) stainless steel. Recent work by Small and pehlke2 has dealt with the effect of fourth-element additions on the solubility of nitrogen in 18-8 base alloys. They found the effect of aluminum additions, up to 0.74 pct, on the solubility of nitrogen to be small. The present study covered the range from 0.74 to 2.28 pct aluminum, and by extending the composition range may be used to better define the effect of aluminum on the nitrogen solubility in these alloys. EXPERIMENTAL PROCEDURE The Sieverts' method was used to measure the equilibrium solubility of nitrogen gas in liquid 18-8 stainless steel alloys containing 0.74, 1.49, 1.93, and 2.28 pct Al. The solubility was measured as a function of the nitrogen gas pressure at temperatures of 1600°, 1650°, and 1700°C. The apparatus used is the same as described by Small and Pehlke.2 The 100-g melts were made from Ferrovac-E high-purity iron, Crucible Steel Co.; 99.95 pct Cr, Union Carbide Corp.; 99.9 pct Ni, International Nickel Co.; and 99.99+ pct Al, Aluminum Co. of America. The aluminum was charged at the bottom of the crucible, surrounded by nickel and iron. The chromium was packed into the interstices to minimize vapor transport of the aluminum during initial melting. The hot volume of the system, measured for each melt with argon, ranged from 45 to 55 standard cu cm with a temperature coefficient of —8 x 10-3 cu cm per °C. The melt temperature was measured with a Leeds and Northrup disappearing-filament type optical pyrometer sighted vertically downward on the center of the melt surface. The temperature calibration of the system by Small and pehlke2 was assumed. Two problems are involved in determining the solubility product of a solid, metal nitride phase in liquid iron alloys. These are: 1) establishing the point of departure from Henrian behavior at the solubility limit of the metal nitride phase; and 2) determining the composition of the solid nitride which is precipitated. Determination of the solubility product of AlN was made by admitting small amounts of nitrogen into the reaction bulb until the deviation from Sieverts' law was clearly evident in the form of a pressure halt. To obtain the solubility product at several temperatures during one run the following procedure was used: 1) add increments of nitrogen to determine the Sieverts' law line at the lowest desired temperature; 2) continue to add nitrogen to precipitate a small amount of the nitride phase; 3) increase the melt temperature 50°C to dissolve the precipitated nitride; 4) repeat step 2 until either a nitride formed or the system reached ambient pressure; if a nitride formed at 1650°C, the sequence was repeated at 1700°C. The composition of the precipitated phase was checked by an X-ray diffraction pattern obtained from powder scraped from the surface of the solidified 1.93 pct A1 melt. RESULTS AND DISCUSSlON Solubility Measurements. Fig. 1 is a typical nitrogen-absorption curve obtained from measurements on a 1.93 pct A1 alloy. Since the initial absorption of nitrogen follows Sieverts' law the nitrogen solubility is plotted as a function of the square root of the pressure of nitrogen gas in the reaction bulb. The results of the solubility measurements for all alloys studied are summarized in Table I. The slope of the Sieverts' law line for each alloy was determined. Since this is also the solubility of nitrogen at 1 atm pressure of nitrogen gas, the latter designation is used for the data. It should be noted. however, that in most cases the value lies above the solubility limit for AlN. Fig. 2 shows the effect of aluminum on the solubility of nitrogen at this reference pressure and as a function of melt temperature. The solid portions of the lines represent attainable solutions; the dashed regions lie above the limit for precipitation of AlN.

Jan 1, 1969

By D. L. Harris, A. M. Gaudin

Observations were made of the distribution of mercaptan containing S35 between aqueous solution and mineral and between aqueous solution and the gaseous phase. Although equilibrium may not have been attained, adsorption of the reagent was shown to occur reasily from air or aqueous solution on sphalerite, zincite, and willem-ite and to correspond to flotation. Adsorption on quartz did not similarly occur. THE following results, presented here in condensed form,' were obtained in a preliminary study of the adsorption of n-hexane thiol, hexyl mercaptan, on sphalerite, zincite, willemite, and quartz, from aqueous solution and from a gas. Interest in this subject was aroused by a Belgian report' of effective use of hexyl mercaptan for flotation collection of oxidized zinc minerals. The relatively low boiling point, 149°C, of the mercaptan3 suggested the desirability of extending the usual measurements of partition of collector between aqueous solution and gas and between gas and mineral. It is believed that this paper presents the first measurements of this type on a flotation system. Attempts were made to carry out the measurements at equilibrium, but as the work progressed it became increasingly doubtful that this desirable condition had been achieved. To control composition and extent of the gas phase, the apparatus was a wholly-enclosed thermally-controlled glass system. Because of these constraints and the desirability of dealing with pure minerals, a scale of operations was chosen in which a few grams of deslimed mineral were used in each test. It was also necessary to choose a particularly sensitive method for mercaptan analysis, and in fact a method that would permit the experimenters to follow the approach to equilibrium. For these reasons mercaptan marked by radiosulphur 35 was used. An analysis was made for the radiosulphur by a modification of the method of Gaudin and Carr. Coarsely-crystallized sphalerite was handpicked, stage-crushed in the dry state, wet-screened on a 200-mesh sieve, and deslimed in water at about 5 microns. Further treatment consisted of a wash in dilute aqueous hydrogen peroxide, drying, removal of the dark-colored fraction in a Frantz magnetic separator, washing in very dilute hydrochloric acid, repeated washing in distilled and conductivity water, and drying. The last washings showed a conductivity equivalent to a few ppm NaC1, that is, much more than would be provided, theoretically, by a saturated ZnS solution. The material was stored dry in sealed bottles. Analyses were as follows: Zn, 62.3 pct; Fe, 0.43 pct; Cd, 0.44 pct; S, 31.2 pct; Mn, 0.001 pct. The specific surface (BET method) was 2000 cm2/g. Zincite from Franklin furnace of the New Jersey Zinc Co. was hand-picked, dry-crushed, wet-screened at 100 mesh, and deslimed at about 10 microns. After drying, the associated zinc, manganese, calcium, and silicate minerals were removed in a Frantz magnetic separator. The purified zincite was washed in distilled water and conductivity water to a conductance of less than 2 ppm equivalent NaC1, dried, and stored. Analyses were as follows: Zn, 75.1 pct; Fe, 0.9 pct; Mn, 2.78 pct. The specific surface (BET method) was 1740 cm 2/g. Willemite, also from Franklin furnace, was purified similarly. Analyses were as follows: Zn, 52.5 pct; Fe, 0.12 pct; SiO², 27.3 pct; loss on ignition, 0.13 pct. The specific surface was 1760 cm 2/g. Conductivity water (double-distilled) and demin-eralized-distilled water were used in most of the tests. The specific resistance was not less than 600, 000 ohms, and usually above 1,000,000. Radiosulphur-marked hexyl mercaptan (1-hexane thiol) was synthesized by Tracerlab, Inc., Boston. Two lots were secured several months apart. The last lot, consisting of about 0.5 g of the mercaptan, had a total activity of about 10 millicuries. Tracerlab Co. guaranteed only the activity; hence a quasi -vapor pressure determination (based upon an S analysis) of the mercaptan was made. The calculated value, 4.2 mm of mercury at 25.5' C, has been compared with that of a sample of Highest Purity 1-hexane thiol from Fisher Scientific Co. The latter had a vapor pressure of 4.5 mm of mercury at 2.5 C. Analytical Procedures The sample containing radiosulphur-marked mercaptan was oxidized to convert the mercaptan sulphur to sulphate, carrier barium sulphate being added to provide a suitable quantity of total barium sulphate in a filter cake. The precipitate was filtered and dried, and counting was carried out either in a streaming-gas (Q-gas) counter for high sensitivity or with an end-window G-M counter for convenience. The oxidized and precipitated mercaptan gave a radioactive count of 65 counts per minute per microgram in the end-window Geiger-Mueller counter and 1100 counts per minute per microgram in a Q-gas counter. For standardization of the mercaptan solution, 15 replicate analyses were made. The average deviation per measurement was about 1600 cpm in 65,000 cpm, the probable error in the mean being 275 cpm. It

Jan 1, 1955

By V. Pasupathi, R. E. Hummel, J. W. Koger

Specimens of P1 brass were plastically deformed at room temperature to various degrees of deformation and subsequently cooled in order to transform them to low-temperature martensite. Deformation shifts Ms. A, , and the temperature of minimum resistivity to lower temperatures, and also decreases the temperature coefficient of electrical resistivity. These properties change rapidly up to about 15 pct reduction but vary very little with higher deformation. The possible relationships between martensite formed by deformation and the M, temperature of low-temperature martensite are discussed. Evidence is given that deformation martensite delays the formation of low-temperature martensite. BETA' brass undergoes at least two different types of martensitic transformations. One of these transformations (B1- B2) was first observed by Kaminski and ~urdjumov' and occurs when 81 brass with a zinc content between 38 and 42 wt pct (quenched from the single-phase region) is cooled below room temperature. Jollev and Hull' determined the structure of 0" from X-ray and electron-diffraction data as ortho-rhombic. Kunze came to the conclusion that the super-lattice cell of 0" is one-sided face-centered triclinic (pseudomonoclinic). The second martensitic transformation (B1-A1) occurs when the specimens are deformed at or somewhat above room temperature. This type of martensite will be called deformation martensite. Horn-bogen, Segmuller, and Wassermann4 determined the structure of deformation martensite to be bct. (An intermediate phase, az, occurs before the final phase appears.) At deformations higher than 70 pct, a, transforms into a.4 A critical temperature Md exists above which no transformation occurs during deformation and is estimated to be around 400°C in P1 brass.5 This martensite has elastic properties.6 When the sample is stressed, martensitic plates appear; when the stress is released, the plates disappear. The present paper studies the effect of deformation martensite on the formation of low-temperature martensite. The experiments involved samples of 8, brass which were plastically deformed by various amounts and were subsequently cooled below the transformation temperature. EXPERIMENTAL PROCEDURE The 13 brass investigated was made from 99.999 pct pure copper and 99.9999 pct pure zinc and contained 38.8 wt pct Zn. The specimens, consisting of foils 0.1 mm in thickness, were heat-treated at 8'70°C for 15 min in an argon atmosphere and then quenched into ice water. They were then deformed by cold rolling and subsequently cooled at a rate of 1°C per min. The martensitic transformation that occurred during cooling was followed by electrical resistivity measurements. The resistance measurement technique and its accuracy have been described in a previous paper. Because the transformation 81 —-8" occurs below room temperature, the samples were placed in a cryo-stat which contained isopentane as a cooling medium. The isopentane was cooled by liquid nitrogen pumped under pressure through a 15-ft coil of copper tubing which was immersed in the isopentane. The nitrogen flow was regulated by a temperature controller using two thermistors in the cooling medium. The cryogenic liquid could be heated with an immersion heater. The useful temperature range with this device was from +25° to approximately -155~C. EXPERIMENTAL RESULTS Resistivity Measurements. The following abbreviations are used in this paper to label the characteristic temperatures during the martensitic transformation. M, is the starting point of the martensitic transformation and is defined as that temperature where the resistivity vs temperature curve on cooling first deviates from a straight line. Mf is the temperature at which the martensitic transformation is completed. On reheating, the transformation from martensite to the parent phase starts at a temperature A, and ceases at a temperature Af. Fig. 1 presents five different resistivity vs temperature curves corresponding to the transformation of brass from Dl to 8" after different degrees of reduction in thickness. The following observations can be made from these curves. 1) With increasing degree of deformation the Ms temperature is shifted to lower temperatures. This shift ranges up to 35°C compared to the undeformed state. This is also indicated in Fig. 2, where AM, (the shift of Ms, compared to the undeformed state) is plotted vs the degree of deformation. AM, increases rapidly until a reduction of about 15 pct is reached. With higher deformations, no additional increase in AM, was found. 2) With increasing degree of deformation the temperature of minimum resistivity (M) is also shifted to lower temperatures. The shift, attains a maximum of about 61°C compared to the undeformed state. In Fig. 3, AM is plotted as a function of deformation. It can be seen that, as in 1 above, AM increases rapidly and no further shift of M occurs for deformations greater than 15 pct. 3) The temperature coefficient of resistivity, is given by the slopes (dp/dT) of the linear portions of

Jan 1, 1969

By T. Y. Yan

SUMMARY Laboratory high pressure column tests have shown that the presence of 1-20 ppm of aluminum ion effectively prevents permeability loss during uranium leaching with leachates containing sodium carbonate. If added after permeability loss has occurred, aluminum ion can restore the permeability to nearly its original value. No deleterious effect was observed on uranium leaching performance and the technique should be quite compatible with all field operations. INTRODUCTION The recovery of uranium values from underground deposits by in situ leaching or solution mining has become economically viable and competitive with conventional open pit or underground mining/milling systems (Merrit, 1971). In situ leaching processes are particularly suitable for small, low-grade deposits located in deep formations and dispersed in many thin layers. Many such ore bodies occur along a broad band of the Gulf Coastal Plain (Eargle et. al., 1971). The advantages of the in situ leaching processes have been reviewed (Anderson and Ritchi, 1968). In the in situ leaching process, a lixiviant containing the leaching chemicals is injected into the subterranean deposit and solubilizes uranium as it traverses the ore body. The pregnant lixiviant or leachate is produced from the production well and is then treated to recover the uranium. The resulting barren solution is made up with the leaching chemical to form lixiviant for re-injection. Upon completion of the leaching operation, the formation is contaminated with leaching chemicals and other species made soluble in the leaching operation and has to be treated to reduce the concentration of these contaminants in the ground water to levels acceptable to the regulatory agencies (Witlington and Taylor, 1978). Restoration is accomplished by injecting a restoration fluid, which could be the fresh water or water containing chemicals, into the formation. As it traverses the leached formation, the restoration fluid picks up the contaminants and is then produced at the production well. This produced water is either disposed or purified for recycle. In both phases of operation, formation permeability or well injectivity is one of the most important parameters which determines the viability of the in situ leaching process. Low formation permeability limits production rates, leading to uneconomical operations. The formation is said to be sensitive if there is a sharp loss of permeability on contact with water and other fluids. Many uranium bearing formations, for example, the Catahoula formation of the Texas Coastal Plain, contain significant amounts of clay minerals which are water sensitive. Serious permeability losses can occur when the pH and chemical composition of the lixiviant is significantly different from that of the formation water. Jones has investigated the influence of chemical composition of water on clay blocking of permeability (Jones, 1964) and Mungan studied permeability reduction through changes in pH and salinity of the water (Mungan, 1965). Various mechanisms of permeability damage have been proposed and reviewed (Jones, 1964; Mungan, 1965; Gray and Rex, 1966; and Veley, 1969). When large amounts of swelling clays are present, a significant fraction of the flow channels in the formation can be reduced due to swelling. However, in most cases, swelling need not be the main cause of permeability losses. Particle dispersion and migration or clay sliming can be more important causes for formation damage. Clay particles entrained in the moving fluids are carried downstream until they lodge in pore constrictions. As a result, microscopic filter cakes are formed by these obstructions, plugging the pores, effectively restricting fluid flow and reducing the formation permeability. Moore found that as little as 1-4 percent clays present in a fine grained sandstone could completely plug the formation if they are contacted by incompatible injected fluids (Moore, 1960). It has been found that injection of NaHC03/Na2CO3 lixiviant into formations with significant clay content often leads to loss of formation permeability and well injectivity. To alleviate this problem a change of the lixiviant composition to KHC03/K2CO3 has been proposed. At present, however, many in situ leaching operations employ NH4HC03/(NH4)2C03 mixtures as a source of carbonates. This approach has been successfully used in South Texas by Mobil, Intercontinental Energy, Wyoming Minerals and U.S. Steel, etc. The use of ammonium carbonates solutions, however, contaminates the formation and requires a time-consuming restoration operation. The other approach to reduce the permeability loss is to pretreat the sensitive formation with chemicals which prevent clay dispersion and migration. Such chemicals include hydroxy-aluminum (Reed, 1972 and Coppel et. al., 1973), hydrolyzable zirconium salts (Peters and Stout, 1977), hydrolyzable metal ions in general (Veley, 1969) and polyelectrolyte polymers (Anonymous). Still another approach, is to minimize the "shock" caused by sudden injection by gradually changing the chemical composition of the injected fluids from that of the formation water. THE APPROACH Since permeability loss can be an important factor limiting the efficiency and economic viability of the in situ leaching process, a study was initiated on

Jan 1, 1982

By Joseph Fry, Ralph H. Espach

In the spring of 1943, when it was evident that the Tensleep bandstone in the Elk Basin Field, Wyoming and Montana, held a large reserve of petroleum, Bureau of Mines engineers obtained samples of oil from the bottom of nine wells and analyzed them for such physical characteristics as the volumes. of gas in solution. saturation pressures or bubble points, shrinkage in volume caused by the release of gas from solution, expansion of the oil with decrease in pressure, and other related properties. The composition of the gas in solution in the oil was studied. The pressures and temperatures existing in the reservoir and the productivity characteristics of the oil wells were determined. The data obtained indicate that the oil in the Tensleep Reservoir of the Elk Basin Field has unusually varying physiral characteristics, such as a saturation pressure of 1,250 psia and 490 cu ft of gas in solultion in a barrel of oil at the crest of the structure and a saturation pressure of 530 psia and 134 cu ft of gas in solution in a barrel of oil low on the flanks. The hydrogen sulfide content of the gas in solution in the oil varies from 18 per cent for oil on the crest to 5 per cent for oil low on the flanks of the structure. Of even greater significance is the fact that these and other variable characteristics of the reservoir oil are related to the position of the oil in the structure. Many geologists and petroleum engineers have considered that all the oil in a petroleum reservoir has rather uniform physical characteristics and that equilibrium conditions prevailed in all underground accumulations of oil and gas; that such is not always so is borne out by the results of the study by the writers. INTRODUCTION The Rocky Mountain region is one in which may be found striking examples of the unusual in oil and gas accumulations, as is evident from the following: The high helium content (7.6 per cent) of the gas in the Ouray-Leadville limestone sequence in the Rattlesnake Field, New Mexico, and gases of similar helium content in other fields; 50" to 55' API gravity distillate in solution in carbon dioxide gas and recoverable through retrograde condensation, in the North McCallum Field, Colorado; the occurrence of gas, oil, or both in closely related structures contrary to the usual concepts of gravimetric segregation: the accumulation of gas and/or oil in structures closely related to other structures that apparently are more favorable but do not contain oil or gas accumulations; the high hydrogen sulfide content (as high as 42 per cent) of the gas associated with oil in some fields in the Big Horn Basin, Wyoming; and the wide range of fluid chararteristics found in the Elk Basin reservoir. Elk Basin, an interesting old oil field that has been producing oil from the Frontier formation since 1915, is situated in a highly eroded basin resulting from the erosion of the crest of an anticline and some of the underlying softer shales. The field came back into national prominence during 1943 when it became known that it was the largest single reserve of new oil discovered in the United States that year. The Tensleep sandstone was found to contain oil in November. 1942, when a well drilled to a depth of 4,538 ft (44 ft into the Tensleep sandstone) flowed oil at the rate of 2,500 B/D. By the end of 1949, 137 oil-producing wells and five dry holes had been drilled, and approximately 32 million bbl of oil had been produced. Approximately 6,000 acres may be considered productive of oil in the Tensleep Reservoir, and estimates of the oil that will be produced average 200 million bbl. The Tensleep Reservoir has further interest because it ha-greater closure than any oil field in the Rocky Mountain region; the closure of the Elk Basin anticline is variously estimated at 5.000 to 10,000 ft. of which the top 2.00 ft of the structure contained oil. SUBSURFACE OIL SAMPLING Fig. 1 is a structural map of the Elk Basin Tensleep Reservoir, on which the nine wells used in this study and the numbers correvponding to the well designations hereafter referred to are shown. Wells 1. 2, 3, 4, and 8 were tested and sampled during October and November. 1943. and Wells 5, 6. 7, and 9 during June and July, 1944. An electromagnetic type sampler developed by the Bureau of Mines and described by Grandone and Cook' was used in obtaining the subsurface oil samples. As the wells were tubed nearly to bottom, the sampler was run as far as possible in the tubing hut never below the top perforations. The following procedure was used in testing and sampling the wells: A well was shut in for at least three days, after

Jan 1, 1951

By W. E. Bergman, P. G. Carpenter, H. B. Fisher

The conditions under which barium carbonate can be used to remove sulfates from drilling muds are limited The amount of sulfate remaining in solution in the system after treatment with barium carbonate is shown to be a function of the concentration of the carbonate and barium ions and the concentration of other electrolytes. Barium hydroxide may advantageously replace barium carbonate when the contamination is not entirely due to anhydrite (calcium in the system is then stoichiometrically less than sulfate) or when the carbonate concentration is high. The effect of substances such as quebracho, phosphates, and chromates, which form complexes or precipitates with barium, is discussed. INTRODUCTION As the complexity of the operations in drilling for oil has increased, more attention has of necessity been directed to the problems pertaining to the maintenance of good drilling mud properties. As a result, chemical treatment of muds has become an important factor in recent years. Some of these treatments have been designed to eliminate the deleterious effects of contaminants in aqueous mud systems by precipitation or other means. The most common of substances encountered during drilling include sodium chloride, cement, and calcium sulfate while various other contaminants: usually in small amounts, may be introduced from the water, clays, and other materials used in preparation of the mud. In certain cases, for example where continued salt-water flow is encountered or massive anhydrite is drilled, special muds may be used so that the physical properties of the mud will remain satisfactory for drilling. In other cases, it is desirable to remove the contaminants so that soluble electrolytes in the system are maintained at low values. For sulfate contamination, the conlmon practice in the field is to add barium carbonate to precipitate the sulfate as barium sulfate Ordinarily such a procedure gives satisfactory results. There have been important instances, however, where addition of barium carbonate was not effective in removal of soluble sulfates from drilling muds. and it is to these cases that the present paper is directed. While it is generally known that barium carbonate is not always effective in removing soluble sulfates from drilling muds, certain inconsistencies appear in the literature as to the limitations of its use, and little explanation for the limitations are given. Varnell and Kimbrel state that "the treatment (with barium carbonate for removal of sulfate) is simple and consists in maintaining a pH of 9 with caustic soda and quebracho." They caution that concentrations of quebracho greater than 1 lb./bbl. may inhibit the reaction. In another publication', a pH of 10.5 is considered "the maximum desirable," and the indication is that as much as 2.5 lb. quebracho per barrel may be present in the particular mud under discussion. Lancaster and Mitchell5 state that appreciable amounts of phosphates in the mud will inhibit the reaction with barium carbonate and that the phosphate treatment should be discontinued at least 24 hours before addition of the carbonate. Experimental work was initiated to ascertain the factors involved in using barium carbonate for the removal of sulfate contamination in drilling muds. While the experimental data herein reported are limited, they focus attention on the pertinent factors which must be considered for successful treatment. These factors are discussed from a practical and a theoretical view, the latter being supported by equilibrium data found in the literature. Further, it will be appreciated that the factors involved in this specific study will be closely analogous to those in certain of the other chemical treatments which involve a precipitation of the soluble contaminant. A thorough comprehension of these factors should result in a more fruitful application of this type of chemical reaction to the treatment of drilling muds. EXPERIMENTAL A. Reagents Two muds were used during this investigation. For one series of tests, bentonite suspensions were prepared by dilution of a stock suspension containing 8 per cent by weight of bentonite (Aquagel). For another series, a 6.4 per cent ben-tonitic mud weighted to 9.7 lb./gal. with barium sulfate (Mag-cobar) was used. Distilled water was used in all preparations. The quebracho (72% tannin extract) was obtained from the Thompson-Hayward Co. of Tulsa and contained 11.4 per cent moisture (105 C.). All other materials were reagent grade, and concentrations were corrected for water of crystallization, if any. All concentrations are expressed in pounds per barrel (42 gallons). B. Technique The systems — either mud or water — were contaminated with either sodium or calcium sulfate after treatment with the desired amounts of sodium hydroxide and quebracbo. For treatments with barium carbonate an approximately 3-fold excess (5 lb./bbl.) was used over that computed to be required to precipitate all the sulfate as barium sulfate. Barium hydroxide was used in concentrations of 2 lb./bbl. — about

Jan 1, 1949

By T. L. MacKay

Oxidation rates of single-crystal and poly crystalline zirconium in oxygen at temperatures from 307° to 815°C obey the parabolic rate law for short ex-posure time, 4 to 6 hr. The activation energy for the oxidation of single-crystal zirconium between 420° and 790°C is 42.6 ± 0.7 kcal per mole, and in the temperature range 307" to 600°C the activation energy for oxidation of poly crystalline zirconium is approximately the same. The high-activation energy is indicative that diffusion through the bulk oxide film is the primary mode of mass transport for both types of metal. The higher oxidation rates for poly -crystalline zirconium in this temperature range were attributed to differences in the orientation of the grains in the metal with respect to the oxidizing surfaces. Above 600°C, vain growth was observed in polycrystalline zirconium, and the oxidation rates approached those of single-crystal zirconium. ThE kinetic data of previous oxidation studies1-' of zirconium in oxygen have been interpreted by both parabolic and cubic rate laws. There is some evidence that there is a transition from the parabolic to the cubic rate law at prolonged exposures, but the question is still controversial. For the parabolic rate law activation energies are reported in the range 18.6 to 35 kcal per mole, and for the cubic rate law in the range 38 to 47 kcal per mole. So far as the mechanism of zirconium oxidation is concerned, inert marker studies10,11 have indicated that the oxidation proceeds by oxygen (anion) diffusion through the oxide film toward the metal-metal oxide interface. Pemslerl2 observed that the orientation of the grains in the zirconium metal substrate affected the rate of formation of the oxide film on the surfaces of the grains and that the orientation dependence of the corrosion rate persisted beyond the initial stages of reaction. The rate of oxidation was a minimum when the c axis of the grain was parallel to the surface of the sample, and rose to a maximum when the c axis was inclined at about 20 deg to the plane of sample surface, and decreased again at higher inclinations. cox13 observed that in 300°C steam a thin oxide film was formed initially on zirconium and that this oxide film, which exhibited interference colors, became dark first along the grain boundaries and then over the whole surface in an inhomogeneous manner as the film thickened. Cox proposed a mechanism in which oxygen diffused along preferred paths created by grain boundaries in the metal and formed a much thicker film at or near the grain boundary than on the central zone of the grain. In the present study, the oxidation rates of single crystals of zirconium were measured in oxygen and compared with the oxidation rates of polycrystalline zirconium of the same bar stock. It was felt that such a comparison would elucidate the role of grain boundaries in the metal substrate. SAMPLE PREPARATION Single crystals of zirconium were prepared by following the procedure of I3apperport,14 starting with 1/4-in. rod purchased as crystal-bar zirconium. Zirconium rods 2 in. long were wrapped in tungsten foil and sealed in quartz tubes at pressures of less than 10-6 mm of mercury. Large single crystals were grown by thermal cycling above and below the a-/3 transformation temperature, 862°C. Several specimens were simultaneously subjected to the same cycling procedure, heating to 1200°C, holding for 4 hr, then cooling in the furnace and holding at a temperature of 840°C for 5 to 10 days. This cycle was repeated five or six times for each set of specimens. The grain size of the crystal-bar zirconium before thermal cycling was between 10 and 30 p. Fig. 1 shows the microstructure of an end section of as-received crystal-bar zirconium. A longitudinal section of each zirconium rod after thermal cycling was polished and examined under polarized light, see Fig. 2, and the largest single crystals were selected for this study. Zirconium rods 1/8 in. in diameter and 1/2 in. long with spherical ends were machined from the single crystals and from the as-received bar stock. An X-ray examination showed that the c axis of the single crystals made either a 34-deg or an 89-deg angle with the rod axis. The specimens were chemically etched for 2 min in solution consisting of 15 parts hydrofluoric acid (48 pct), 80 parts nitric acid, and 80 parts water. The chemical polish removed 1 to 2 mils from the surface. EXPERIMENTAL The Sartorius vacuum microbalance used in this study has a sensitivity of 0.5 pg and a capacity of

Jan 1, 1963

By P. G. Carpenter, H. B. Fisher, W. E. Bergman

The conditions under which barium carbonate can be used to remove sulfates from drilling muds are limited The amount of sulfate remaining in solution in the system after treatment with barium carbonate is shown to be a function of the concentration of the carbonate and barium ions and the concentration of other electrolytes. Barium hydroxide may advantageously replace barium carbonate when the contamination is not entirely due to anhydrite (calcium in the system is then stoichiometrically less than sulfate) or when the carbonate concentration is high. The effect of substances such as quebracho, phosphates, and chromates, which form complexes or precipitates with barium, is discussed. INTRODUCTION As the complexity of the operations in drilling for oil has increased, more attention has of necessity been directed to the problems pertaining to the maintenance of good drilling mud properties. As a result, chemical treatment of muds has become an important factor in recent years. Some of these treatments have been designed to eliminate the deleterious effects of contaminants in aqueous mud systems by precipitation or other means. The most common of substances encountered during drilling include sodium chloride, cement, and calcium sulfate while various other contaminants: usually in small amounts, may be introduced from the water, clays, and other materials used in preparation of the mud. In certain cases, for example where continued salt-water flow is encountered or massive anhydrite is drilled, special muds may be used so that the physical properties of the mud will remain satisfactory for drilling. In other cases, it is desirable to remove the contaminants so that soluble electrolytes in the system are maintained at low values. For sulfate contamination, the conlmon practice in the field is to add barium carbonate to precipitate the sulfate as barium sulfate Ordinarily such a procedure gives satisfactory results. There have been important instances, however, where addition of barium carbonate was not effective in removal of soluble sulfates from drilling muds. and it is to these cases that the present paper is directed. While it is generally known that barium carbonate is not always effective in removing soluble sulfates from drilling muds, certain inconsistencies appear in the literature as to the limitations of its use, and little explanation for the limitations are given. Varnell and Kimbrel state that "the treatment (with barium carbonate for removal of sulfate) is simple and consists in maintaining a pH of 9 with caustic soda and quebracho." They caution that concentrations of quebracho greater than 1 lb./bbl. may inhibit the reaction. In another publication', a pH of 10.5 is considered "the maximum desirable," and the indication is that as much as 2.5 lb. quebracho per barrel may be present in the particular mud under discussion. Lancaster and Mitchell5 state that appreciable amounts of phosphates in the mud will inhibit the reaction with barium carbonate and that the phosphate treatment should be discontinued at least 24 hours before addition of the carbonate. Experimental work was initiated to ascertain the factors involved in using barium carbonate for the removal of sulfate contamination in drilling muds. While the experimental data herein reported are limited, they focus attention on the pertinent factors which must be considered for successful treatment. These factors are discussed from a practical and a theoretical view, the latter being supported by equilibrium data found in the literature. Further, it will be appreciated that the factors involved in this specific study will be closely analogous to those in certain of the other chemical treatments which involve a precipitation of the soluble contaminant. A thorough comprehension of these factors should result in a more fruitful application of this type of chemical reaction to the treatment of drilling muds. EXPERIMENTAL A. Reagents Two muds were used during this investigation. For one series of tests, bentonite suspensions were prepared by dilution of a stock suspension containing 8 per cent by weight of bentonite (Aquagel). For another series, a 6.4 per cent ben-tonitic mud weighted to 9.7 lb./gal. with barium sulfate (Mag-cobar) was used. Distilled water was used in all preparations. The quebracho (72% tannin extract) was obtained from the Thompson-Hayward Co. of Tulsa and contained 11.4 per cent moisture (105 C.). All other materials were reagent grade, and concentrations were corrected for water of crystallization, if any. All concentrations are expressed in pounds per barrel (42 gallons). B. Technique The systems — either mud or water — were contaminated with either sodium or calcium sulfate after treatment with the desired amounts of sodium hydroxide and quebracbo. For treatments with barium carbonate an approximately 3-fold excess (5 lb./bbl.) was used over that computed to be required to precipitate all the sulfate as barium sulfate. Barium hydroxide was used in concentrations of 2 lb./bbl. — about

Jan 1, 1949

By Joseph Fry, Ralph H. Espach

In the spring of 1943, when it was evident that the Tensleep bandstone in the Elk Basin Field, Wyoming and Montana, held a large reserve of petroleum, Bureau of Mines engineers obtained samples of oil from the bottom of nine wells and analyzed them for such physical characteristics as the volumes. of gas in solution. saturation pressures or bubble points, shrinkage in volume caused by the release of gas from solution, expansion of the oil with decrease in pressure, and other related properties. The composition of the gas in solution in the oil was studied. The pressures and temperatures existing in the reservoir and the productivity characteristics of the oil wells were determined. The data obtained indicate that the oil in the Tensleep Reservoir of the Elk Basin Field has unusually varying physiral characteristics, such as a saturation pressure of 1,250 psia and 490 cu ft of gas in solultion in a barrel of oil at the crest of the structure and a saturation pressure of 530 psia and 134 cu ft of gas in solution in a barrel of oil low on the flanks. The hydrogen sulfide content of the gas in solution in the oil varies from 18 per cent for oil on the crest to 5 per cent for oil low on the flanks of the structure. Of even greater significance is the fact that these and other variable characteristics of the reservoir oil are related to the position of the oil in the structure. Many geologists and petroleum engineers have considered that all the oil in a petroleum reservoir has rather uniform physical characteristics and that equilibrium conditions prevailed in all underground accumulations of oil and gas; that such is not always so is borne out by the results of the study by the writers. INTRODUCTION The Rocky Mountain region is one in which may be found striking examples of the unusual in oil and gas accumulations, as is evident from the following: The high helium content (7.6 per cent) of the gas in the Ouray-Leadville limestone sequence in the Rattlesnake Field, New Mexico, and gases of similar helium content in other fields; 50" to 55' API gravity distillate in solution in carbon dioxide gas and recoverable through retrograde condensation, in the North McCallum Field, Colorado; the occurrence of gas, oil, or both in closely related structures contrary to the usual concepts of gravimetric segregation: the accumulation of gas and/or oil in structures closely related to other structures that apparently are more favorable but do not contain oil or gas accumulations; the high hydrogen sulfide content (as high as 42 per cent) of the gas associated with oil in some fields in the Big Horn Basin, Wyoming; and the wide range of fluid chararteristics found in the Elk Basin reservoir. Elk Basin, an interesting old oil field that has been producing oil from the Frontier formation since 1915, is situated in a highly eroded basin resulting from the erosion of the crest of an anticline and some of the underlying softer shales. The field came back into national prominence during 1943 when it became known that it was the largest single reserve of new oil discovered in the United States that year. The Tensleep sandstone was found to contain oil in November. 1942, when a well drilled to a depth of 4,538 ft (44 ft into the Tensleep sandstone) flowed oil at the rate of 2,500 B/D. By the end of 1949, 137 oil-producing wells and five dry holes had been drilled, and approximately 32 million bbl of oil had been produced. Approximately 6,000 acres may be considered productive of oil in the Tensleep Reservoir, and estimates of the oil that will be produced average 200 million bbl. The Tensleep Reservoir has further interest because it ha-greater closure than any oil field in the Rocky Mountain region; the closure of the Elk Basin anticline is variously estimated at 5.000 to 10,000 ft. of which the top 2.00 ft of the structure contained oil. SUBSURFACE OIL SAMPLING Fig. 1 is a structural map of the Elk Basin Tensleep Reservoir, on which the nine wells used in this study and the numbers correvponding to the well designations hereafter referred to are shown. Wells 1. 2, 3, 4, and 8 were tested and sampled during October and November. 1943. and Wells 5, 6. 7, and 9 during June and July, 1944. An electromagnetic type sampler developed by the Bureau of Mines and described by Grandone and Cook' was used in obtaining the subsurface oil samples. As the wells were tubed nearly to bottom, the sampler was run as far as possible in the tubing hut never below the top perforations. The following procedure was used in testing and sampling the wells: A well was shut in for at least three days, after

Jan 1, 1951

By J. J. Gilman, T. A. Read

FOLLOWING the deformation 01 zinc monocrys-tals, sharply bent basal planes are observed near several types of inhomogeneities. Three of these in-homogeneities have characteristics which are quite regular so that they can be studied and analyzed. These are compressive kink bands, "deformation bands," and the inhomogeneities near end restraints. The present paper describes experiments in which "deformation bands" were artificially produced, and bend plane phenomena are discussed in terms of dislocation theory. Also, two new bend plane phenomena are described. The importance of bend plane phenomena in the deformation of crystals is not widely recognized. Many phenomena may be explained in a manner similar to the discussion in this paper. Jillson1 has pointed out that the "punching effect" in zinc is a bend plane phenomenon and is not caused by prismatic slip.' Bowles3 has suggested that they may be involved in diffusionless phase changes. Cahn4 has discussed the role of bend plane formation in the polygonization of zinc. Experimental Work Tensile Kink Bands: Because of the geometrical similarity between "deformation bands" and "kink bands" (compare Fig. 1 of this paper with Fig. 1 of the paper by Hess and Barrett"), the band shown in Fig. 1 of this paper will be called a "tensile kink band," and that shown by Hess and Barrett will be called a "compressive kink band." It is felt that the term "deformation band" should be reserved for banded structures in polycrystalline materials such as iron." Tensile kink bands seem to form spontaneously in aluminum crystals deformed by tensile loading.7-10 In zinc and cadmium crystals they do not form in good, carefully loaded specimens.'." However, tensile kink bands can be produced artificially in zinc crystals. The present authors did this by scratching one of the flat surfaces of triangular crystals transversely with a sharp needle. Natural tensile kink bands caused by inhomogeneities sometimes appeared in deformed crystals which were identical in appearance with the artificially produced ones. Zinc monocrystals were grown by the Bridgman method in graphite molds. Chemically pure zinc (99.999+ pct Zn) was used and the molds were sealed inside evacuated pyrex tubes during growth. The crystal cross sections were equilateral triangles with a typical base of 0.210 in. The artificial kink band shown in Fig. 1 is typical of tensile kink bands in zinc. The band lies between two bend planes which run from upper right to lower left and is inclined oppositely to the slip bands which are sharply bent at the two bend planes. The general form of the artificial tensile kink bands was independent of the scratch depth (1 to 5 mils deep) and also independent of which side was scratched. These variables did cause variations, however. Deep scratches produced more localized kink bands than light scratches. Also, if the angle between the slip plane traces and a transverse scratch varied appreciably among the three sides, then localization of the resulting kink bands also varied. Furthermore, if the slip direction lay nearly parallel to the scratched side, the band was more developed near the scratched side than at the opposite edge. Scratches produced tensile kink bands for crystal orientations from xo = 15" to x, = 75". Fig. 2 shows a scratched crystal after deformation. One triangular side lies in the plane of the photograph. The right hand tensile kink band was produced by a transverse scratch on the upper right side. The next two kink bands were the result of scratches on the front surface. The kink band at the left was caused by a scratch on the lower back side. All four bands have the same general form. A longitudinal scratch was also made on the crystal shown in Fig. 2 to determine the effect of a scratch on the critical shear stress. The critical shear stress of the scratched region was 33.9 g per sq mm compared to 24.4 g per sq mm for the un-scratched region above it. Fig. 3 shows Laue patterns of the crystal shown in Fig. 2. Fig. 3a shows the pattern of the undeformed crystal. The orientation was x, = 21°, A, = 31". After deformation, Fig. 3b was made of the homogeneously deformed portion of the crystal. The spots are compact but split into two halves. This region was elongated 45 pct and its orientation was x = 14", X = 20"; the sine law predicts x = 14", A = 20.5". Fig. 3c was taken near the center of the middle tensile kink band of Fig. 2. The pattern shows a range of orientations and polygonization in this region. The spread in orientation was due to the fact that the basal planes were curved (see Fig. 1) rather than flat as in the ideal case. Some may also have been the result of elastic distortions and "local curvatures." The orientation range was x = 23" to 32", A = 30" to 42". It is apparent from Fig. 3 that the material inside and outside the kink band rotated in opposite directions with respect to the tension axis during deformation. The orientation calculated from the ideal configuration of Fig. 9,

Jan 1, 1954

By J. R. O’Connor

Stimulated emission from Nd+3 in yttrium uanadate fYVOJ is reported. Single crystals of YVO4:Nd, obtained from Linde Col-p., have improved substantially in the last several months. Pulsed thresholds of YVO, laser rods are now approximately 2 to 3 5, cowparable to tliose for YAG:Nd. Yttrium uanadate crystalli~es irz a space group similar to zircon. All rare-earth vanadates have this structure. Rare-earth ions sucll as Nd+3 which substitutes for Y+3, aye situated irz a strong tetragonal crystal field which lacks inversion symmetry. This condition increases the p'robability of the parity-forbidden f — f transitions. Yttrium anadate has strong absorption bands beyond -1000A. These are clue to Y-O, V-O charge transfer and molecular transitions. Under 2537 and 3660A irradiation pure YVO, fluroresces u bright yel-LOLO. This fli&orescence is corrzpletely quenched in YV04:Ncl crystals. This and other evidence of energy trut~sjer from the lattice is repovted. Optzcul atz 1user pvope 1-ties o! YI'U4:E[t are brieJy described. THIS paper describes some of the optical and laser properties of Nd+3- and Eu+3-doped yttrium orthovana-date (YVO4). It reports laser action for the first time in this low-symmetry host. For some time we have pursued a research program concerning laser hosts' wherein the rare-earth (RE) ion is situated at a site of low crystal symmetry so as to increase the probability of radiative transitions. Single crystals of doped and undoped YV04 are grown from iridium crucibles in an oxyhydrogen gas-fired furnace by a modified Czochralski technique.' This material crystallizes in a D4li tetragonal space group of the zircon (ZrSiO,) type.3 All RE vanadates have the same structure and form solid solutions with YVO4. Therefore, it will be possible to investigate a variety of cross-pumped laser systems, as in the case of yttrium aluminum garnet (YAG).4 At present, ~d'~-doped YAG is one of the most efficient solid-state lasers.5 Accordingly, most of the material to follow will compare the properties of YV04 to those of YAG. Fig. 1 shows the relative transmission of YAG and two types of YVO4. "Pure" YVO4 has a normal absorption edge and is colorless. A second type has a broad absorption peaking near 4200A and is yellow. Rubin and Van uitert6 suggest the yellow material is slightly reduced. Samples of each type are being investigated by electron spin resonance,7 but these studies are so far inconclusive. The pulsed laser threshold is much lower in the yellow material than in the colorless. Therefore, the absorption at 3500 to 5000.4 transfers energy to the Ndi3 ions. Photons of wave length between 2000 and 4500A cause undoped YVO4 to fluoresce at 4800, 5250, 5460, 5540, and 5750A. This emission, previously reported by Brixner and Abramsom,8 is partially quenched by EU'~ and completely quenched by Ndt3 at room temperature due to energy transfer from the lattice to the RE ions. At low temperatures, some lattice fluorescence is present. This implies that the energy-transfer process is in part phonon-assisted. Although the YVO, single crystals used in this work were prepared from Y2O3 containing less than 0.01 pct rare-earth impurities, there is aopossibility that emission lines between 4800 and 5750A are due to dysprosium, terbium, and so forth. However, these lines are not observed in other compounds, prepared from Y2O3, such as YP04, Y2MoO6, and so forth. Furthermore, extensive absorption measurements on our "pure" YV04 single crystals between 0.4 and 5.0 failed to reveal any characteristic rare-earth lines. Fig. 2 compares the absorption spectra of Ndt3-doped YAG and YVO4from 0.6 to 1.0 . The Ndt3 absorptions are labeled according to free ion, R-S coupling. These term designationsQ are appropriate for YAG:Nd. They appear to be inappropriate for YV04:Nd. In YVO, neodymium must substitute for yttrium. The yttrium site is situated In a strong tetragonal field, where point symmetry is (42m) or possibly lower.1° However, the reduced splitting of the Stark components of the YV0,:Nd spectrum implies that the NdT3 ion is in a cubic site. The only plausible explanation for this discrepancy is that the Ndt3 ion is in a low-symmetry site, lacking inversion symmetry, so that a substantial admixture of 4f and 5d wave functions occurs. In this case, R-S coupling is not valid and J is no longer a good quantum number." Consistent with this view, the 4~ metastable level of YV04:Nd has an oscillator strength larger and a

Jan 1, 1968

By R. H. Jamison

A relatively new haulage system is described. Employed by the Delmant Fuel Co.. the "Full Dimension" system provides an uninterrupted flow of coal from a loader or continuous miner at the face to the main line transportation system. This system is said to provide a higher percentage of recovery as well as additional safety and production. Delmont Fuel Co. is employing a comparatively new system of transportation known as a Full Dimension system. Cne of these systems has been in operation for a year at the company's 10-B Mine as a part of a conventional section. A second was installed at the No. 10 mine in late 1960 to handle the production of a Colmol in a pillar section. SYSTEM COMPONENTS A Full Dimension system is a haulage system that provides an uninterrupted flow of coal from a loader or continuous miner at the face to the main line transportation system. The equipment required for this system consists of a series of interconnected chain conveyors that are mobile and articulated. They will retract or extend a sufficient distance for the development of a five-entry system; or, in the Colmol pillar section, it provides reach of 210 ft in all directions from the section belt. The components of this system are: l)One 160-ft chain line placed in tandem with the belt conveyor. It has a self-propelled drive, is 20 in. wide and 9 in. deep. Moving this conveyor requires the assistance of a loading machine or cutting machine. 2) One 40-ft piggyback that discharges along the entire length of the 160 ft chain conveyor. 3) A mobile bridge carrier, which is a self-propelled conveyor with four wheel steer and four wheel drive, twenty-eight feet long, it delivers coal to the receiving end of the piggyback. Axles steer individually making possible almost lateral movement. 4) Another 40-ft piggyback, duplicate of item 2 that delivers coal along the entire length of item 3 (mobile bridge carrier). 5) A second mobile bridge carrier, similar to the first, which deliver coal to the piggyback (item 4). 6) A third 40-ft piggyback, duplicate of items 2 and 4. This pig is attached to the loading machine and delivers its coal along the length of the second mobile bridge conveyor. Since the original preparation of this paper, the Delmot Fuel Co. has been able to eliminate the 160-ft chain conveyor. This was accomplished by connecting the outby piggyback directly to a loading machine with an extended boom. The loading machine loads directly onto the belt. This change has resulted in a substantial reduction in moving time and greatly increased flexability. A single trailing cable powers the entire string of equipment. It is attached to the side of the equipment in such a way as to keep it off the ground and afford maximum protection. The tramming rate of this equipment is 90 fpm. The conveyor capacity in a conventional section at Delmont's mines is 7.5 tpm and in the Colmol section is 5.5 tpm. This regulation is a simple function of conveyor speed. To visualize operation of this equipment, it would be well for me to touch briefly on local conditions in the Upper Freeport seam in which we mine. (Also, see the photographs of some of the equipment in use.) DELMONT'S TOPOGRAPHY The Delmont Fuel Co. operates two mines in this seam in Westmoreland County, Pa. The No. 10 mine, which was opened in about 1912, is now almost worked out. Depending on economics in the industry, it has a life of two to four years on a declining production basis. A year ago a new drift mine was opened which is called No. 10-B. It is about two miles from the cleaning plant and is connected thereto by an overland belt conveyor. The new mine is being developed at a rate calculated to take up the slack as the old mine plays out. The Upper Freeport seam averages 4.2 ft in thickness in the area of the Delmont mines. It carries 4 in. of boney coal at the top of the seam and a middle man of from 2 to 4 in. We mine just above a 1-in. slate parting which has 4 to 6 in. of highly laminated coal beneath it. This material normally makes a very firm bottom. The roof varies from dark shale to sand rock and 36-in. bolts are placed on 4-ft centers for roof support. All working places are driven 20 ft wide on development and 25 ft wide on retreat. Selection of mobile chain conveyor equipment when it became available, was a very natural move for Delmont Fuel to make, because chain conveyors and piggybacks had been in use at the company's mines for about 12 years. Grades in the new mine

Jan 1, 1961