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By J. M. Lovejoy

Various estimates have been made as 60 the percentage of oil left in a field after the wells have become so small that it is no longer practical to produce them. Engineers have given the matter much study and can substantiate their figures by data taken from fields from the Appalachians to California. The average oil sand has a porosity of about 20 per cent., which gives a capacity per acre-foot of approximately 1500 bbl. The sand thickness in Oklahoma pools averages 20 ft. With 20 per cent, porosity and a 20-ft. sand thickness, the capacity per acre is 30,000 bbl., yet these pools will seldom yield more than 5000 bbl. to the acre. These figures gupport the theory that at least 50 per cent. of the oil remains in a sand after all known methods to recover it have been used. Certainly we can never recover all the oil, unless in years to come oil becomes so rare and yet so necessary that the price will justify sinking shafts into the abandoned fields and regular mining methods of drifting and stoping. However, with improved methods of production and conservation of the natural agencies of expulsion, we should be able to increase recovery. It is with this in mind that this paper, relating to the effect of back pressure on wells, is presented. Except in the fields where production is caused by hydrostatic pressure, the chief agency for getting oil out of the sand into the hole is the gas that occurs with the oil. After the pressure has declined, probably gravity also is a factor, but not an important one. With a given amount of oil in a sand and a given amount of gas occurring with the oil, the ratio of gas volume per barrel of oil is the key to the ultimate recovery from that sand. Our efforts should be along lines that will lower this ratio and make the gas, the agency given us by nature, do its work better and yield more of the oil, of which it is a part. T. E. Swigart,' of the U. S. Bureau of Mines, has published an extract of the paper he is preparing under the title "The Effect of Back Pressures. on Wells." The experiments described were made on two

Jan 1, 1924

By J. H. Wiggins

Granting that about 600,000,000 bbl. of light oil will be produced in the United States this year and taking the Bureau of Mines' statement that 71/2 per cent. of the total crude production will be lost before the finished gasoline is shipped from the refinery, the volumetric evaporation will be 45,000,000 bbl. of the cream of the gasoline. This is a ConseNative figure and is equivalent to 1,890,000,000 gal. The real value of this liquid is at least 150 per cent. of the value of an equal volume of motor fuel. At only 10 c. per gal., the value lost is $189,000,000; at 15 e. per gal. the loss is $283,000,000. If 750,000,000 bbl. of light and heavy oil are produced here this year and the average price per barrel is $1.333, the gross return to producers will be $1,000,000,000 and the net returns about $200,000,000, if the cost of production is only $1 per barrel. Thus, the evaporation bill is about 20 per cent. of the gross income and is equal to the net income of the crude-oil producers. Two other comparisons with popular phases of the petroleum industry will help give an adequate conception of the evaporation problem. These are: cost of preventing evaporation compared to cost of cracked gasoline and volume of gasoline evaporated compared to volume of gasoline manufactured from natural gas. When gasoline is manufactured from heavy oils by the cracking process, there are two important divisions of the total cost of the product: the manufacturing cost, such as plant cost, operation, maintenance, etc., and the cost of the barrel of heavy oil, from which the cracked gasoline is made. In preventing evaporation loss the cost first mentioned enters into the total cost, but the second cost is eliminated; that is, no charge is necessary for stock from which to manufacture the saving. A detailed analysis of these two costs on a large scale shows that the net income from a dollar spent in preventing evaporation loss from the lease through the refinery is twice the net income from a dollar spent in cracking. Of

Jan 1, 1924

By E. L. Ickes

DURing the summer and winter of 1918 eleven standard rigs were erected in the United Kingdom to test the petroleum prospects of- ten structures, eight of which were in England and two in Scotland. By the fall of 1921 ten of the wells were completed; the remaining one, the D'Arcy in Scotland, was stopped some months later. The tests were deep ones, five of the wells being 4000 ft. or more, the rest varying in depth between 1810 and 3918 ft. The total footage drilled was 40,047 ft. The holes were put down with standard or cable tools purchased in the United States (except the boilers). The larger sizes of casing, 10-in. and above, were also from America, while the smaller sizes were secured in Scotland. The Hardstoft well in England found a small production of high-grade oil and the D'Arcy well also encountered what is reported as a favorable showing at a depth of 1810 ft. The Werrington and West Calder wells had to be abandoned on account of drilling difficulties. The Apedale well encountered great thicknesses of ash in the Carboniferous and had to be abandoned on account of depth. The results might be summarized by saying that of the ten structures drilled upon, two yielded encouraging showings; three cannot be considered as having been adequately tested; and five produced dry holes, although in some of these small oil showings and gas were met. The total cost of the work amounted to about half a million pounds sterling, which sum includes the cost of all equipment, subsequently sold by the government. The work, under the superintendence of V. L. Conaghan, took place for the most part in the period immediately following the war—a period of high prices, labor and transportation difficulties, and unsettled conditions generally; factors tending to retard the work and affect the costs. The writer, as a member of the staff of S. Pearson & Son, Ltd., had charge of the administration of the work during its later stages and

Jan 1, 1924

By F. D. Mahone

Much crude oil, as produced from the well, carries varying amounts of water, which may be present as free water in globules sufficiently large to settle out, in time, if the fluid is allowed to stand, or as an emulsion formed by myriads of minute water particles, each surrounded and entrapped by a film of oil through which it cannot break under the action of gravity alone. Such an emulsified mixture of oil and water is commonly termed "cut oil." When such an emulsion is subjected, under proper conditions, to the influence of a high-potential alternating-current field, the minute water particles rupture the enveloping oil films and coalesce into larger water droplets this procedure continuing until all the water is freed into drops of such size that they readily settle out. This action has been photographed by the micro-moving-picture camera; under the microscope, the breaking-up of the emulsion, as described, is seen to be accomplished in a few seconds. The low power requirements of the process, from records of commercial plants, substantiate the theory that the action is that of a multitude of electrical condensers in series, rather than that of a number of conducting paths. The minute water particles serve as the metallic elements, or plates, of the condensers and the separating oil acts as the dielectric. Such surface charges as the particles may have are removed, and the intervening oil is broken, probably electrically by the voltage and mechanically by the attractive force between adjacent oppositely electrified particles. The principle of breaking up an emulsion under the influence of an alternating electric field was discovered by F. G. Cottrell and Buckner Speed, through experiments conducted, at the University of California, which resulted in a plant being installed on the property of the Lucile Oil Co. in the Coalinga field, California, early in 1909. This plant was able to reduce 14-per cent. emulsion to less than Pper cent. with commercial success. Standard Cottrell Apparatus The present standard Cottrell apparatus consists essentially of the electric treater and a settling or trap tank. The treater is a galvanized-iron tank approximately 3 ft. in diameter and 10 ft. high, which con-

Jan 1, 1924

By R. T. Hukki

THE accepted basis of comparisons between mills of different diameter is the percentage critical speed. [ ] In the following analysis capacity, T, is expressed in short tons per hour, tph, and power consumption, P, in kilowatts, kw. Accordingly power consumption per unit of capacity, Po, will be expressed in kilowatt hours per short ton, or kw-hr per ton. In all equations D refers to the inside diameter of the mill in feet and v to the peripheral speed of the mill in feet per minute inside the liners. Comparison between separate mills must be based on equivalent grinding conditions, i.e., same feed, same size distribution of feed, same size distribution of product, and same percentage of solids. In addition, comparisons between separate rod mills must be based on the same rods, same type of liners, and same percentage rod load. Comparisons between separate ball mills presuppose the same balls, similar liners, and same relative ball load. The practical np-range through which the equations apply varies, being narrower for fine grinding in ball mills and wider for coarse crushing in rod mills.

Jan 7, 1954

By P. K. Guerrero, Nathaniel Arbiter

The correlation of power consumed by a tumbling mill with the dimensions, speed, and load has been attempted by three principal methods. One of these, the torque formula, has been reviewed critically elsewhere. This approach, while analytical, disregards the individual motion and speed of the tumbling bodies and assumes that the gross geometry of the entire load is sufficient to establish the power requirement. A more general approach, using dimensional analysis, has been applied in this laboratory by the present authors, and more recently by Rose. This disregards the internal conditions within the mill entirely and in effect is an empirical procedure for correlating data. Finally, the complete analysis of tumbling mill dynamics as first made by Davis attempts to develop the power requirement from individual ball and rod paths and velocities. Although Davis' result is applicable only at a single speed for a given size and load it could be useful, since his optimum speed is at the upper limits of conventional tumbling mill practice. Where power values predicted by the Davis equation were compared with actual mill requirements, they were found too low for small mills and much too high for the largest mills. This suggested that the agreement with actual intermediate range requirements might be fortuitous, and the development of the equation was examined critically.

Jan 5, 1960

By William E. Ford, Edward Salisbury Dana

The monoclinic Wolframite Group and the tetragonal Scheelite Group are included here. Wolframite Group WoIframite (Fe,Mn)W04 a : b : c = 0.8300 : 1 : 0.8678 B = 89' 22' Hiibnerite MnW04 048362 : 1 : 0.8668 89' 73' WOLFRAMITE. Monoclinic. Axes a : b : c = 0.8300 : 1 : 0.8678; B = 89' 22'. mm"', 110 A 1TO = 79" 23'. ay', 100 A 101 = 62' 54' at, 100 A 102 = 61" 54'. $', 011 A 011 = 81" 54'. Twins: (1) tw. axis c with a (100) as comp.-face; (2) tw. pl. k (023), Fig. 449, p. 171. Crystals commonly tabular (1 a (100); also prismatic. Faces in prismatic zone vertically striated. Often bladed, lamellar, coarse divergent columnar, granular. Cleavage: b (010) very perfect; also parting (1 a (100), and 11 t (102). Fract,ure uneven. Brittle. H. = 5-5.5. G. = 7.2-7.5. Luster submetallic. Color dark

Jan 1, 1922

By Chung Yu Wang

MINING ENGINEERING presents the fourth in a series of articles on strategic minerals. Preceding it are "Cobalt" in January, "Sulphur" in May, and "Nickel" in August. Here, an authority in the field analyzes the resources, production, uses, defense impact and future outlook of Tungsten

Jan 10, 1951

By W. P. Sykes

TUNGSTEN serves mankind in two major roles. The first of these is represented by the tungsten filament of the incandescent electric lamp, a common article of commerce. In the field of hard alloys it plays its second substantial part. A fortunate combination of physical properties in this metal ac- counts for its efficient service as a source of illumination. Tungsten melts at about 3400°C, has a relatively low vapor pressure and at the same time sufficient strength, both hot and cold, to serve satisfactorily as filaments, which may range in diameter from 0.060 to 0.0005 in. In the early days of the incandescent lamp, the pioneers realized the importance of using a substance of high melting point for the source of light. The metals osmium (mp approx. 2700°C) and tantalum (mp approx. 2850°C) were both employed to some extent. Tantalum actually attained some commercial importance in this field because it could be drawn into small wires of appreciable length. DUCTILE TUNGSTEN WIRE Before the year 1908, tungsten was considered a nonductile metal, since no one had succeeded in overcoming the brittleness so typical of the unworked metal at room temperature. The methods employed today in producing ductile tungsten wire were developed over a period of years. The process was largely determined by the exceedingly high temperature required to melt this metal. Even today the difficulties involved in producing an appreciable quantity of pure

Jan 1, 1953

By Zay, Jeffries

THE effect of thoria (ThO2) on grain growth in tungsten was discussed in some detail in a paper presented before this Institute by one, of the authors in 1918.1 In that paper it " was assumed that the, thoria was present in the tungsten entirely as a mechanical mixture. There was no indication in the experiments described that even a trace of the thoria was in solid solution in the tungsten. Langmuir,2 however, observed that thoriated-tungsten filaments under certain conditions showed electron emissions many thousand times greater than unthoriated tungsten at the same temperature. He concluded from his studies that a slight amount of the thoria had dissociated on heating the filament to a temperature near 220°. C. At this temperature and higher, part of the thorium diffuses to the surface of the filament where it evaporates at. a much faster rate relatively, than the tungsten, and also at a rate, nearly as fast as it is brought to the surface by diffusion: If the temperature is lowered to say 1800°,. C., diffusion of the thorium atoms to the surface is more rapid than evaporation, sown adsorbed film of thorium atoms is produced on the surface of the tungsten filament. The electron emission is governed by the outside layer of atoms so the emission from such a filament might be expected to approxi¬mate that of a thorium filament at the same temperature. PRESENCE OF METALLIC THORIUM IN THORIATED TUNGSTEN If the filament containing the adsorbed film of thorium. is heated to a sufficiently high temperature, the thorium atoms evaporate: rapidly and the electron emission becomes more nearly that of tungsten. On cooling again to 1800° C., or thereabouts, the emission 'builds up gradually to a maximum. The filament containing the adsorbed layer of thorium atoms is said to be "activated." By studying the rates of activation under different conditions of prior thermal treatment and at different temperatures, Langmuir was able to arrive at an estimate of the

Jan 1, 1927

By A. Eugene Lillstrom

I N the development of iron mines and production of iron ore from the Marquette range, drilling blast-holes is an important phase of the mining cycle. The ground drilled in ore production can be classified into two main categories, soft hematite and hard hematite or magnetite. Within these categories the material exhibits a wide range of penetrability by percussion drills. Development work encounters various types of rock. Slate and altered basic intrusives constitute the softer types commonly encountered. Harder materials are represented mainly by greywacke, quartzite, iron formation, and diorite.

Jan 12, 1951

By L. Graydon Carpenter, Donald E. Garrett

Probably the largest single tungsten deposit in the U. S. is one that has yet to produce any tungsten; it is not even listed in tables showing U. S. reserves. This deposit is at Searles Lake, Calif., where the brine contains about 70 ppm WO3. Small though the concentration is, the amount of brine in the lake is so great that it is estimated at 170 million lb of WO3 (8.5 million units), equaling the total of all other known reserves in the U. S. This dry lake is located in the basin formed by the Argus and Slate ranges in the northeastern corner of the Mojave Desert (Fig. 1). It consists of a massive salt body some 35 sq miles in extent, varying in thickness from 0 to 120 ft and containing more than 3 billion tons of salt. A central section of about L. G. CARPENTER and D. E. GARRETT are with the Research Dept., American Potash & Chemical Corp., Trona, Calif. TP 47881. Manuscript, Nov. 4, 1958. AlME Trans., Vol. 214, 1959. 8 sq miles is exposed salt; the remaining area is overlain by mud. Except for the exposed sodium chloride (10 to 15 ft thick) the body consists of a very complex and heterogenous mixture of soluble crystals, containing at least eight major phases. It is only about 53 pct solid, the voids being occupied by a dense brine which is the raw material for two chemical companies operating in the valley.

Jan 3, 1959

By J. P. BONARDI, William F. Boericke

BOULDER COUNTY, Colorado, ranked during the war years and until the end of 1918 as one of the foremost tungsten-producing districts of the world. In 1919 production fell off drastically, due to heavy importations of foreign ores from China, Burma and South America. So large were the imports that even after the enactment of a protective tariff in 1922 of 45c. per lb. on tungsten metal, equivalent to $7.14 per unit (201b.) of tungstic acid? (WO,), the stocks of metal in this country were extensive enough to supply the demands of industry, and prevent general resumption of mining by domestic producers. Even today there are only two producers in the Boulder district though at one time as many as twenty separate companies were in operation. About the same ratio holds for other tungsten-producing districts in the country, including California and Nevada. Total consumption of tungsten concentrate in terms of 60 per cent WO2 in the United States amounted to approximately 3790 tons in 1928, according to Frank L. Hess.' Of this amount, domestic mines contributed 1290 tons, and the rest, 2500 tons, was imported. Yet in 1917, with tungsten concentrate selling at $20 per unit, the Boulder district alone produced 2707 tons, indicating the effect of enhanced ore price upon production. It is believed by American tungsten miners that, given a sufficiently high tariff, all the demands of industry can be met by domestic production without placing a prohibitive burden on consumers. For instance, in steel manufacturing the percentage of tungsten entering into the manufacture is so small that, ?regardless of cost, it can constitute but a small fraction of the cost of steel to the buyer.

Jan 1, 1929

THERE are three chief production zones of tungsten ore in China. In the Province of Kiangsi mines are located at Kanchow, East River, and West River. Their combined production is understood to amount to 300 to 350 tons of ore per month, and their original exportation is made through the port of Kiukiang, largely to Shanghai. The second zone is in Kwangtung Province, the mines there being at Tayulin. Produc-tion reaches about 200 tons per month and cargo is gen-erally exported through the port of Hong Kong. In the Province of Hunan approximately 25 tons of ore are produced monthly in the mines at Ton-on. Tungsten ore from Kiangsi and Kwangtung Prov-inces is generally about 70 per cent WO, (tungstic acid), while that from Hunan is of lower quality, run-ning about 65 per cent WO3. Kiangsi ore is received from the mines in 100-1b. and Hunan in 224-lb. gunny sacks. No repacking is done except as it is made neces-sary by the condition of the sacks. Kiangsi Province contains the Chinese districts pro-ducing the largest amount of salable wolframite or tungsten. Many districts west and south of Kiangsi have been found to have wolframite deposits.-Com-merce Reports.

Jan 1, 1928

By W. N. Marchant, P. T. Brooks, P. B. Altringer, R. O. Dannenberg

The US Department of the Interior, Bureau of Mines conducted laboratory tests to devise a process for recovering a marketable grade of tungsten from the brine of Searles Lake, Calif. The brine contains only 56 ppm W (70 ppm W03). Using ion exchange resins synthesized by USBM chemists, 98% oft he tungsten was extracted from the brine and 92% of the tungsten was recovered as a marketable iron-tungsten concentrate containing 44% tungsten as tungsten trioxide. Although major technical problems have largely been resolved, research is progressing to escalate testing in a process research unit to provide more reliable data for an economic appraisal.

Jan 8, 1979

By W. N. Marchant, P. T. Brooks, P. B. Altringer, R. O. Dannenberg

The US Department of the Interior, Bureau of Mines conducted laboratory tests to devise a process for recovering a marketable grade of tungsten from the brine of Searles Lake, Calif. The brine contains only 56 ppm W (70ppm WO3). Using ion exchange resins synthesized by USBM chemists, 98% of the tungsten was extracted from the brine and 92% of the tungsten was recovered as a marketable iron-tungsten concentrate containing 44% tungsten as tungsten trioxide. Although major technical problems have largely been resolved, research is progressing to escalate testing in a process research unit to provide more reliable data for an economic appraisal

Jan 1, 1980

By Paul D. Conatore

INTRODUCTION There are important reasons for a discussion of tungsten resources, reserves, and production in the Circum-Pacific area. First, the world's chief tungsten deposits, as well as most of the world's tungsten reserves and production, occur in this region. It is well known that the world's largest tungsten reserves are located in southeastern China and that for many years, the largest individual mine in the world was there. Although China still has the world's greatest tungsten production, the very high-grade scheelite mine of Canada Tungsten Mining Corporation in the Northwest Territories is the largest producer of tungsten today. There is certainly a great quantity of tungsten in Asia, but the strategic importance of this fact is now offset by the wide distribution of mines and production facilities throughout the world, especially in other parts of the Circum-Pacific area such as Australia, Canada, and the United States. In addition, much of the Circum-Pacific area is comprised of Mesozoic-Cenozoic orogenic belts. These global tectonic units are regarded as very favorable for additional tungsten deposits, particularly scheelite-bearing tactites, and consequently, prospecting and exploration will most likely be concentrated in the Circum-Pacific area. Second, tungsten must be regarded as one of the, most important metals of modern industry because of its very special properties. It has the highest melting point, the highest tensile strength at elevated temperatures, and the smallest compressibility of any metal. The metal also possesses a very high density, excellent corrosion resistance, good thermal and electrical conductivity, and a low coefficient of expansion. As a result, tungsten has found increasing importance in a wide range of industries. From the filament in an electric lamp, to cutting tools and drilling bits, to the exotic radiation shields that protect supersonic aircraft and spacecraft, tungsten plays an indispensable role in our daily lives. The primary objective of this paper is to present an overview of important facets of known and suspected tungsten in the Circum-Pacific area. Resources, reserves, current production, planned capacity expansions, and new operations, as well as an assessment of the probability for development of deposits in the Circum-Pacific area, are discussed. RESOURCES The average crustal abundance of tungsten has been estimated at 0.0015 kilograms per tonne. A comparison of the abundance of various metals in crustal rocks to that of tungsten is presented in Table 1, which shows that tungsten abundance is similar to that of its commonly associated metals, tin and molybdenum. Table 1. AVERAGE CRUSTAL ABUNDANCE OF VARIOUS METALS (Grams per Tonne) [ ] With careful thought, it can be realized that tungsten ore deposits result from the concentration of the metal, through normal geologic processes, to levels substantially greater than its average crustal abundance. The minimum technologically and economically workable tungsten concentration, or cutoff grade, is a function of (1) deposit tonnage, (2) mining and milling methods, (3) production tonnage, (4) capital and operating costs, (5) tungsten market conditions, and (6) value of associated recoverable metals. The tungsten cutoff grade that is currently exploitable at a profit varies from 0.09% W03 to 1.55% W03, reflecting concentration factors from 470 to 8200, as shown in Table 2. Table 2. CURRENT TUNGSTEN CUTOFF GRADES [ ]

Jan 1, 1982

By Zay Jeffries

A. G. WORTHING, Nela Park, Cleveland, Ohio (communication to the Secretary*).-The paper by Mr. Jeffries is very interesting. He is to be commended for his pioneer work in the study of equilibrium systems at the very high temperatures which one obtains with tungsten and molybdenum. There is one statement, however, to which I must take exception. On page 1227, a statement is made which would seem to indicate that the Nela Research Laboratory joined Dr. Langmuir in the recommendation of 3,300°C. as the most probable melting point of tungsten. This is not the case. In. the paper referred to by Mr. Jeffries, I have given 3,630°K. or 3,357°C. as the melting-point temperature for tungsten. Confirming observations by other workers in our laboratory justify the belief that this latter value is correct to within a small part of the discrepancy between the two values quoted.

Jan 12, 1916

By Zay Jeffries

IN this paper, it is proposed to outline a method for the determination of melting points of those metals and alloys having high fusion temperatures. The application of the method as used to determine the melting points of alloys of tungsten and molybdenum will be given. It will be seen from these results that tungsten and molybdenum form a completely FIG. 1.-PARTIAL SECTION OF APPARATUS USED TO DETERMINE MELTING POINTS OF TUNGSTEN AND MOLYBDENUM ALLOYS. isomorphous series. This is also verified by the accompanying photomicrographs. Tungsten and molybdenum have been found to crystallize in the salve system, namely, isometric, and the crystal units are cubes. These determinations were made by examining etching pits in the pure metals.

Jan 7, 1916

By Zay Jeffries

J. W. RICHARDS, South Bethlehem, Pa.-I think that the diagrammatic results can be much more clearly set forth if they are plotted as follows: The present diagram, shown on page 1227 of Mr. Jeffries' paper, Logarithm of Per cent of Maximum Wattage Used plots the variation of wattage with temperature in a very inconvenient and uncertain-way. If, however, you plot as abscissas the logarithms of the wattage, you get very nearly a straight line, so that you can interpolate the values with much greater accuracy than you can by using

Jan 4, 1917