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By Evan Bennett

ALMADEN is Arabic for "the mine." The definite article is properly used, for no mercury mine in the world compares with it for richness and volume of ore, produced and potential. After more than twenty centuries of exploitation, intensive throughout the last lour, ore from Almaden is about five times as rich as that of its closest competitor. We drove to the mine one April afternoon, across Don Quixote's plains of the Mancha, up the bleak, arid valley of the Rio Valdeazogue where we passed tenth century Moorish workings and their ruined castles. At dusk, we came to the Hacienda de Castilseras, a large farm where Almaden miners work their land on off days. Then we drove through the whitewashed, well-ordered town to the Castillo de la Direccion where we were challenged at the iron gate by two picturesquely costumed Guardias Jurados.

Jan 1, 1948

By F. Lynwood Garrison

Except in the old Catalan forge, or its modifications, attempts to make iron and steel directly from ore in a practical and economical manner have failed so frequently and completely that such schemes are looked upon with justifiable distrust. Without exception, all have failed from one cause or another, although in some instances every indication of a practical success was manifest in the beginning. It is, therefore, necessary to carefully examine and consider every detail affecting the process, or more properly, furnace, under consideration. This I have done to the best of my ability during a long visit to Russia last summer, and after satisfactorily observing the practical success of the furnace in the iron works of Count Stroganoff at Dobriansky in the Government of Perm, I decided to investigate as completely as possible the history of similar furnaces in Finland and Russia. These data, sifted and verified with the greatest possible care, form the substance of the present paper.* An illustration on page 321 of Percy's Iron and Steel shows the old type of Osmundssmide or harkugnar, which has been in use in Northern Europe since pagan times. Fig. 1 shows a furnace of this kind. It should, perhaps, more properly be called a high-bloomary furnace or forge, the Swedish word hark meaning bloom or loupe. It was with this type of furnace that Mr. Husgafvel began his experiments at Porsaskoski in 1875. Attempts to obtain better results with larger furnaces of this type were failures, as every bloom or loupe obtained necessitated blowing out the furnace with a consequent large waste of fuel. A larger furnace of course increased this waste with no corresponding advantage. A movable hearth of threeeighth inch iron, lined with a mixture of clay, quartz and lime, was next tried, but in consequence of the frequent repairs of this lining,

Jan 1, 1888

Philip Argall, Denver Col. (communication to the Secretary): Dr. Raymond claims (Trans., xxiii., 560)) that my statement (p. 557) regarding the crystallization of iron "is beyond question incorrect." He says: "It is not even settled that vibration will crystallize iron under any conditions." While admitting that authorities differ on the possibility of cold crystallization of iron, I believe it is a settled and undisputed fact that vibration in the presence of heat will crystallize iron. Bloxam and Huntington say :* " Vibration assists 'in converting fibrous metal (iron) back into a crystalline state when heated, a lower temperature sufficing than in the absence of vibration." Mr. A. F. Hill, summing up a very exhaustive review upon the crystallization of iron and steel, pronounces against crystallization, but only at temperatures below 900' F. Mr. Howe, discussing ,the breakage of a 20-foot porter-bar with a crystalline fracture, suggests that it was attributable to heat, jointly with the jar. We see, then, that vibration of heated iron bars will induce crystallization and consequent change of structure. Referring to my statement, I wish to point out, that I was discussing the vibration of stamps arid should have said, "vibration under all such conditions," etc. That is, vibration attended with sharp blows, such as a stamp-stem is subjected to, will crystallize iron; yet I believe that intense vibration under any condition will

Jan 1, 1895

By Arthur C. Forsyth, R. L. Dowdell

A search through the available literature shows that the cobalt-nickel-silicon system has not been systematically studied. This seems rather odd because all three elements are fairly abundant and have better than average corrosion resistance; however, they have high melting points, which makes experimental work difficult. Cobalt and nickel form a continuous series of solid solutions and each metal dissolves about 7.5 per cent silicon. Many ternary alloys have been studied and the results have been published in a great many different ways, but to present such data in a short but clear and understandable manner is still a problem. The following pages describe the results of the study of 76 alloys from which the partial ternary diagram (Fig. 1) of the cobalt-nickel-silicon system has been drawn. The alloys were chosen according to the plan in Fig. la by taking definite ratios of cobalt and nickel, such as 70 Ni, 30 Co or 40 Ni, 60 Co, and adding silicon in various percentages. Each section was studied in detail by means of thermal analysis and microscopic examination, but only two of these detailed sections were thought necessary in the point perspective drawing to give a comprehensive picture of the liquidus, solidus and solid transformations that take place over the temperature ranges studied. Complete thermal analyses and microscopic data are given in Table 1. Experimental Procedure The alloys were prepared from metals of commercial purity, as follows: electrolytic nickel 99.60 + 0.35 Co; chemically purified silicon 99.79 per cent plus impurities of Fe 0.027, A1 0.008, Ca 0.014, C 0.004, N² 0.10; and cobalt 98.82 per cent plus impurities of Ni 0.42, Fe 0.12, CaO 0.27, S 0.012, Mn 0.10 and SiO² 0.15. It should be noted that the largest impurity in cobalt is nickel, one of the alloying elements. The alloys were melted in a small Ajax induction furnace, the nickel and cobalt being melted first because of their better ferromagnetic

Jan 1, 1940

By Arthur C. Forsyth, R. L. Dowdell

A search through the available literature shows that the cobalt-nickel-silicon system has not been systematically studied. This seems rather odd because all three elements are fairly abundant and have better than average corrosion resistance; however, they have high melting points, which makes experimental work difficult. Cobalt and nickel form a continuous series of solid solutions and each metal dissolves about 7.5 per cent silicon. Many ternary alloys have been studied and the results have been published in a great many different ways, but to present such data in a short but clear and understandable manner is still a problem. The following pages describe the results of the study of 76 alloys from which the partial ternary diagram (Fig. 1) of the cobalt-nickel-silicon system has been drawn. The alloys were chosen according to the plan in Fig. la by taking definite ratios of cobalt and nickel, such as 70 Ni, 30 Co or 40 Ni, 60 Co, and adding silicon in various percentages. Each section was studied in detail by means of thermal analysis and microscopic examination, but only two of these detailed sections were thought necessary in the point perspective drawing to give a comprehensive picture of the liquidus, solidus and solid transformations that take place over the temperature ranges studied. Complete thermal analyses and microscopic data are given in Table 1. Experimental Procedure The alloys were prepared from metals of commercial purity, as follows: electrolytic nickel 99.60 + 0.35 Co; chemically purified silicon 99.79 per cent plus impurities of Fe 0.027, A1 0.008, Ca 0.014, C 0.004, N² 0.10; and cobalt 98.82 per cent plus impurities of Ni 0.42, Fe 0.12, CaO 0.27, S 0.012, Mn 0.10 and SiO² 0.15. It should be noted that the largest impurity in cobalt is nickel, one of the alloying elements. The alloys were melted in a small Ajax induction furnace, the nickel and cobalt being melted first because of their better ferromagnetic

Jan 1, 1940

By Richard J. Lund

Stock piling-and by that I mean well-organized stock piling on a substantial scale-is almost as old as the hills themselves. It was back in early Biblical times, as recounted in the Book of Genesis, that Joseph was charged by Pharaoh with the responsibility of stock piling food during the seven years of plenty to guard against the seven subsequent years of famine that were revealed by the Pharaoh's dream. And this same policy of storing up food or materials to provide for future anticipated emergencies can be traced repeatedly down through the ages. So our own efforts are anything but new. Our modern concept of stock piling-the purchase and storage of strategic materials to assure supplies needed in time of some future war- stems from our experience in World War I. In 1920, the War Department was charged by Congress with the responsibility of procuring all War Department supplies and mobilizing industry in the event of another war. During the two decades that followed there were many authoritative studies made of our deficient mineral problem, all of which pointed out the urgent necessity of stock piling certain strategic materials as a reserve against future war. One such study, made in 1925 through the combined efforts of the Mining and Metallurgical Society and the AIME, was done at the ex- press request of the War Department. Eight years later another more de-

Jan 1, 1949

By E. S. Davenport

WHEN annealed carbon, or low-alloy, steels are suitably heated the ferrite (alpha iron solid solution) and the carbide, of which they are composed, react together to form a single solid solution of carbon (and other elements) in gamma iron (austenite). This reaction may begin only at a certain minimum temperature called the eutectoid temperature. The first ferrite and carbide thus to react together do so in definite proportions known as the eutectoid composition. With further heating the original constituent that is present in excess is dissolved in the austenite until exhausted. Whether the excess constituent be ferrite (hypoeutectoid steels) or carbide (hypereutectoid steels) the procedure is much the same, and upon slow cooling the homogeneous austenite expels the excess of either (proeutectoid ferrite or carbide) until the eutectoid composition is reached. Thus the reaction upon heating is strictly reversed upon cooling and accordingly an equilibrium diagram of this process may be constructed. Such an equilibrium diagram concerns itself only with the tempera¬tures involved and with the proportions and compositions of the phases developed under conditions that suffice to permit equilibrium. Specifically it has no concern for the type or mode of distribution of these constituents nor with any extra-equilibrium conditions such as undercooling, which is almost universally encountered in metals. Actually, however, of great importance is the sluggishness toward equilibration caused by the not inconsiderable time involved in diffusion. Thus instead of the theoretical transformation point AE, we find for a certain rate of heating or cooling the use of the designations Ar and Ac (transformation temperature found on cooling and upon heating). These figures obviously have no particular meaning except as measured and expressed for a definite heating or cooling rate, and represent the apparent temperature displacement caused by an inadequate time allowance. In this paper are presented the results of a study of the time required for' the transformation of austenite to ferrite and carbide at a variety of temperatures and also of the time required for the reaction austenite ?martensite at the temperatures at which this reaction occurs instead of

Jan 1, 1930

By R. Bainbridge

THE Consolidated Mining and Smelting CO. of Canada Ltd. has operated a lead smelter at Trail, B. C., for many years. In order to take advantage of metallurgical advances, as well as to improve materials handling methods, this company, commonly known as "Cominco," commenced planning a program of smelter revision and modernization some years ago. The first stage of this program involved the design and construction of a new blast furnace gas cleaning system. The selection of equipment, the design of facilities, and preliminary operating details of this system will be dealt with in this paper. The essential problem was to clean and collect 100 tons of dust daily from 153,000 cfm* (12,225 lb per min) of lead blast furnace gas which varied in temperature from 350º to 1100°F. Because it was desired to collect the dust dry, either a Cottrell or a baghouse cleaning plant was to be selected. Comin-co's many years of experience with both systems provided a background for choosing the most satisfactory installation. All information pertinent to the two methods of dust recovery was carefully investigated, and it was decided to replace the existing equipment with a baghouse. Very briefly, the reasons for this decision were as follows: 1—A baghouse installation would be practical because the SO2 content of the gas was low and corrosion would not be a problem if the baghouse operating temperatures were held sufficiently above the dew point. 2—Variations in the physical characteristics of fume and dust, which are inherent in this blast furnace operation, should not substantially affect the operating efficiency of a baghouse. 3—For the same capital cost, metal losses (stack and water losses) would be appreciably less in a baghouse. 4—A baghouse would be easier to operate, and would not require the use of highly skilled labor. 5—Operating and maintenance costs of a bag-house would be lower. 6—The only available space for reconstruction was relatively small, and not suited to a Cottrell installation. Once the baghouse system was decided upon, detailed design of the installation was begun. Baghouse Design Gas Cooling: Before the required capacity of the baghouse could be determined, the method of cooling the gas to the temperature necessary for bag-house operation had to be chosen. The problem confronting the design engineers was how best to cool 153,000 cfm of gas from a temperature ranging from 350°F to brief peaks of 1100°F, down to 210°F, the maximum safe baghouse inlet temperature. A survey of existing blast furnace gas temperatures in the outlet flue showed that the normal range was as given in Table I. The obvious choices of cooling method were: 1— cool completely by the addition of tempering air; 2—utilize a heat exchanger; 3—cool by radiation; and 4—cool with water spray in conjunction with the admission of tempering air. The advantages and disadvantages of the various cooling methods were: Air Addition: To cool completely by the admission of tempering air involved tremendous volumes, Fig. 1. For example, to cool 1 lb of blast furnace gas at 450°F requires 1.84 lb of air at 80°F or 1.60 lb at 60°F. As it is necessary to design for peak conditions, it can readily be seen that volumes of tempering air in the order of 1,500,000 cfm would have to be handled. Using the normal design figure of 2.5 cu ft per sq ft of bag area, a baghouse installation comprising some 600,000 sq ft of filter cloth would be necessary. Such design requirements would be prohibitive, not only from a standpoint of capital expenditure, but also because of space limitations. Heat Exchanger: The utilization of a heat exchanger was given serious consideration. A horizontal tube unit using air as the medium to cool the required volume of blast furnace gas from 400" to 250°F was investigated. Cooling above 400°F would be done by water spray, and below 250°F by admission of tempering air. The estimated capital cost of such a unit was found to be prohibitive. From an operating standpoint, there was considerable doubt as to whether the soot blowing equipment provided would effectively keep the dust from building up on the tube surface. The performance of heat exchangers operating on dusty gas in other company operations had not been too favorable. Radiation Cooling: Although somewhat cumbersome, gas cooling by radiation from 'trombone' tubes or other similar equipment (cyclones) is employed in many metallurgical operations. Such an installation was also considered. However, calculations showed that an installation much larger than the space available would be required to handle the gas volume involved. For example, to cool 153,000 cfm of blast furnace gas from, say, 600' to 250°F (i.e., remove in the order of 58,500,000 Btu per hr with heat transfer rates varying from 1.1 Btu per sq ft per hr per OF for the higher temperature ranges to 0.88 Btu per sq ft per hr per OF for the lower ranges) would need a cooling area of some 175,000 sq ft.

Jan 1, 1953

By George M. Fowler

MINING geology is a progressive study, so we must look to the future for the solution of many of its most significant problems. These problems, world-wide in scope, offer ample opportunity for the exercise of the utmost skill and intelligence by all that attempt to solve theta, as it is generally recognized that many ore deposits of the future will he found only by months or years of combined intelligent effort by the several engineering groups. Renewed appraisals are continually being made to better understand the relationship of physical-chemical processes to ore deposition and other mineralization and to interpret the findings of the geophysicists and others in terms of economic results. A study of current geologic activi¬ties clearly reflects the growing tendency for cooperation between the different branches of geology in order to appraise their united efforts. In line with these activities arrangements have been made to transfer the geophysical section of the U. S. Bureau of Mines to the Geological Survey.

Jan 1, 1936

By Robert T. DeGavre

INTRODUCTION The $645 million financing for Inco Ltd's Soroako nickel project in Indonesia not only represents a significant human achievement but also there are certain important lessons that can be derived from Inco's experience in financing the project. The paper will not present a technical assessment of the project since Inco Ltd. submitted a series of papers on this subject at the international Laterite Symposium as part of the 108th Annual Meeting of the AIME in February 1979. BRIEF HISTORY OF THE SOROAKO PROJECT Table 1 summarizes the milestones achieved in the Soroako project and its financing. Exploration Phase A contract of Work was signed on July 27, 1968 by the Republic of Indonesia and F.T. International Nickel Indonesia (P.T. Inco) covering an extensive area of over 25,000 square miles on the two southeastern arms of the island of Sulawesi. The Contract provides that P.T. Inco has the sole responsibility for financing the project and determining the terms on which the financing should be obtained, that P.T. Inco has the right to receive and hold outside of Indonesia foreign exchange revenues and to freely dispose of such revenues, and that Indonesians have the right to purchase up to 20% of the equity of P.T. Inco over a period following start of production. P.T. Inco began field investigations in the Contract Area in August 1968. Preliminary reconnaissance sampling with portable drills broadly outlined areas of favorable laterite terrain which were then systematically sampled on surveyed grids. By early 1971 sufficient exploration work had been completed to indicate that the laterite deposits near Soroako could sustain a major nickel-producing plant (figure 1). Pilot plant studies in 1970 and 1971 at Inco's research station in Port Colborne, Ontario, using two bulk samples of Soroako ore material, also confirmed that the ore could be upgraded and treated for the recovery of its metal values. Feasibility Phase Encouraged by the results of its exploration program and pilot-plant work, Inco Ltd. commissioned Toyo Engineering Company of Japan in August 1971 to prepare a capital cost estimate for a relatively small nickel project called "Stage I". Stage I was to be a single-line pyrometallurqical process plant with an annual capacity of approximately 15,000 metric tons of nickel contained in 75% nickel sulphide matte (see Figure 2). Electric power was to be supplied by a thermal power station. It is important to recognize that Inco's strategy was to develop the Soroako ore deposits in several stages: first, construct a small project to gain experience and to reduce the initial capital outlay and then later expand in one or more steps to a much larger project to achieve maximum economies. The strategy reflected both Inco's financial position in 1971 as its sales and earning dropped sharply and the difficulties previously experienced by Inco in trying to launch in the late 1960's very large "greenfield" nickel projects in New Caledonia and Guatemala. Toyo's Project Development Study was completed. in January 1972. Based upon Toyo's cost estimate for physical facilities, Inco estimated the total capital cost of Stage I to be $115 million. For the next several months, Inco ran numerous in-house financial feasibility studies, using as inputs Toyo's cost estimate and the results of its exploration and pilot plant programs. In September 1972, Inco completed a project feasibility study which was based upon a capital cost estimate of $135 million. The feasibility study was immediately made available to potential partners and lenders. Partner Negotiations The Japanese nickel market had from the outset been central to Inco's planning for the Soroako project. That market had been growing dramatically at rates in excess of 20% per annum during the 1950's and 1960's. Japan had established, for rational security and other reasons, a domestic

Jan 1, 1985

By L. R. Smith

BUTANE OPERATED drilling rigs are a recent innovation in the petroleum industry, so extensive data on their operation are not available. However, experience indicates that, within limitations, as much can he accomplished with butane as with steam, at a decided reduction .in expense of installation and cost of operation. Commercial butane is a liquid motor fuel similar to gasoline, but much more volatile, so that it has to be stored under pressure. At 10° F. it is liquid at atmospheric pressure, but at 100° it has a pressure of 70 lb. or more. As soon as the pressure is reduced, it turns to vapor and in that state is far more easily mixed with the air necessary for combustion. Butane occurs as a by-product in the absorption process of natural gasoline extraction from casing-head gas. The product has been used to some extent 10 raise the octane value of gasoline. However, because of its volatile nature, such admixture is stable only to a limited degree. Attempts also have been made to introduce the product in a gaseous form into oil- hearing formations in repressuring work. It has, however, until recently, for the most part been wasted.

Jan 1, 1937

Jan 1, 1970

By K. C. Strebig, C. W. Schultz, A. A. Selim

The effect of some organic additives in diamond drilling of quartzite was investigated in the laboratory. The drill was designed to measure the rate of penetration, the thrust, and the torque and to record each as a function of the distance drilled. A statistical plan was followed throughout the investigation and an equation representing the bit performance was derived from the mathematical theory of reliability. The drilling torque was found to increase with the use of additives while the sliding coefficient of friction and the wear coefficient decreased. The energy per unit volume consumed was found to increase with the use of additives. A hypothesis explaining the effects achieved with the additives is given. INTRODUCTION For some time researchers have attempted to increase drilling efficiency by adding certain agents to the flushing medium. Much of this interest is the result of the observations of Rehbinder, Shreiner and Zhigach1 They postulated that "...in processes for the mechanical destruction of solids, a region of increased crack formation is created in the deformed layers adjoining that surface of destruction, forming the predestmction zone. The surrounding medium (for example, a liquid) which wets a given solid will penetrate the embryo microcracks of the predestruc-tion zone. Increasing the molecular affinity of this liquid for the surface of the solid considerably facilitates the deformation and destruction by softening the solid in the zone of increased crack formation. In this manner, the hardness or strength of the deformed body is decreased by the influence of the penetration of the liquid into the predestraction zone." This is known as the "Rehbinder effect". Rehbinder's work has prompted many investigators to examine the effect of additives on the mechanical destruction of rocks. Engelmann, Terichow and Selim reported that the maximum penetration of the rock by a diamond point in a solution environment was at the isoelectric point of the solution.* Robinson reported that his results did not appear to support the theory of Rehbinder.3 Joris and .McLaren suggested that additives with surface tension lower than water will be more efficient in cooling the diamonds.4 Their effectiveness in removing the fine cuttings from the face of the bit will also improve the efficiency of the system. They reported an improvement in impregnated bit life and penetration rates with the use of soluble oil additives. In contrast, Long and Agnew, drilling with surface set bits, reported that lubricating agents increase bit temperature and wear.5 A significant change was reported6 in the mechanical properties of rock with polar additives. It was concluded that this change in the mechanical properties of the rock in the presence of the additive is due to the rock hydrophilic properties. Ethylene glycol, glycerine and anionic detergent were selected for this investigation because their surface tension is lower than that of water. The surface tension of these additives for the concentrations studied was 42 to 75 percent of the surface tension of water. A low surface tension additive would wet the surface of the diamonds more easily and hence would be more effective in cooling the diamonds. Another characteristic of these low surface tension additives is their effectiveness in removing the cuttings and preventing the flocculation of the formed particles in the drilling process. This article summarizes the results of an investigation performed at the laboratories of USBM, Twin Cities Mining Research Center. The objective of the investigation was to study the over-all effects of some organic additives on the performance of diamond impregnated bits in atmospheric drilling conditions only and not in downhole pressured conditions.

Jan 1, 1970

By OWEN H. PERRY

One of man's primary tools is the ordinary screen. Whether of mesh or punched plate, it is fundamental in principle, primitive in its origin, and common in its application through all the world; and yet the screen goes only a part of the way toward the completion of its job of separating materials according to size. It will give a practical and continuous separation according to "size," as generally understood (accurate according to the breadth), but the accurate and continuous separation as to thickness is not a practical function of the screen. Still, all through history, the thickness of particles of material must have been important to many people; therefore, one would expect that some standard method of sizing for thickness would long since have been evolved and that equipment applying that method would be readily available to any in¬dustry. This, however, seems not to be so.

Jan 1, 1949

By Kennedy, Joseph E.

MANY things must be considered in coming to a decision as to what type of crushing and grinding equipment is to be used for preparing run-of-mine ore for concentration, amalgamation, flotation, or cyanidation. This paper is intended in no sense as a thorough discussion of these various factors, but rather contains a few observations based on a wide experience in the manufacture and application of milling machinery. One important governing factor is the tonnage to be dealt with. In large plants treating several thousands of tons in eight hours, a large jaw or gyratory crusher of substantial construction is standard equipment for reducing ore to 8 or 10 in. or finer. In open-pit work, using power shovels with 4- or 5-yd. dippers, a jaw crusher should have a receiving opening of 48 by 60 in., or 60 by 84 in., so that dynamite or hand sledging will not be required for breaking to a finer size before primary crushing. The coarsely broken ore is then conveyed by a belt to vibrating screens, the oversize from which is again conveyed by belts to secondary crushers having openings of 12 or 14 in., the product from which is conveyed to storage. From storage, the material goes to a finishing gyratory for reduction to 1/4 in. or finer.

Jan 1, 1936

By K. D. Jacob, W. L. Hill

Fluorine recovery in the United States has been restricted chiefly to manufacture of ordinary superphosphate and wet-process phosphoric acid. However, there is an expanding use of fluorine by industry in the form of hydrofluoric acid. Improved methods for recovering fluorine from phosphate rock would yield an adequate supply of fluosilicates and a substantial contribution to the hydrofluoric acid requirement. THE bulk of natural phosphates is comprised of calcium phosphates, which are usually apatites;' calcium aluminum phosphates such as pseudowavel-1ite; and aluminum phosphates, which occur in extensive deposits, notably on Grand Connetable Island." Nearly all deposits of current commercial value are apatite, often with admixed material of other classes. In the trade coarsely crystalline material, mainly fluorapatite of igneous origin, moves as apatite, whereas the fine-grained material of sedimentary origin is marketed as phosphate rock. The latter classification includes the phosphate shales in western North America. Although several genetic varieties of phosphate rock are recognized, most known reserves are of marine origin. Calcium phosphate is concentrated from Florida land pebble and Florida hard rock deposits and from Tennessee brown rock deposits. Phosphate Rock as a Fluorine Carrier: More than two decades ago Reynolds and Jacob surveyed the fluorine content of commercial phosphate rock from various parts of the world. Later these samples were re-analyzed by a new and more reliable method of determining flourine. The revised results with interim additions of new samples, published a few years ago in a brief summary," are shown in Figs. 1-3. Through the points representing the respective varieties of rock medial straight lines are drawn. In some instances the lines are well defined by the points; in others, where scattering renders the position of the best line uncertain, the greater weight is given points near the end of the covered range. Wherever distinct varieties are not recognized among regional deposits the custom is to identify the sample with the geographical location of the deposit. Although all rock varieties cannot be classified with certainty, the plotted results exhibit three distinct types of rock in which the F to P2O5 ratio diminishes, remains sensibly constant, and increases, respectively, as the grade of rock increases. Existence of two types of Florida land pebble, Fig. 1, is supported by additional results recently supplied by a producer." Generally speaking, phosphate rock from continental deposits carries considerably more fluorine, and apatite and insular phosphates less, in proportion to the phosphorus content than is required by the formula for fluorapatite. Exceptions to this are apatite from Canada and certain samples of Florida waste-pond phosphate. The manner in which excess fluorine is held and the nature of the carbonate in carbonate apatite are discussed in recent articles. High-grade calcium phosphates with F to P2O5 ratios less than 0.05 have been found in Curacao, Christmas Island," Mexic,13 and elsewhere. The calcium aluminum phosphates and aluminum phosphates aften carry notable amounts of fluorine. The F to P2O, ratio for one sample of pseudowavel-lite concentrate was 0.05." Aluminum phosphate from Grand Connetable Island is very low in fluorine, whereas some aluminum phosphate minerals" carry as much fluorine as highly fluorinated phosphate rock. Fluorine in Domestic Phosphate: The curves shown in the figures permit interpolation of the F to P2O5 ratio corresponding to the midpoint of selected ranges in grade of any one of the several varieties of phosphate. Multiplication of the interpolated ratio by the mid-range grade (P2O5) yields a figure for the percentage of fluorine in this grade. Then, with the use of the mid-range grade, the amount of fluorine held in phosphate reserves can be estimated, see Table I. Accordingly, on Jan. 1, 1950, the fluorine complement of known domestic reserves exceeded 420,000,000 long tons of the element. A previous figure," deduced in 1940 by a simpler procedure

Jan 1, 1955

By W. L. Hill, W. H. Armiger, S. D. Gooch

The physical properties, chemical behavior under thermal treatment, and fertilizer value of fluorine-containing pseudowavellite (hydrous calcium aluminum phosphate) that occurs as phosphate clay admixed with quartz sand in an extensive deposit near Bartow, Fla., were determined by experiments in laboratory, pilot-plant, and greenhouse. When the mineral was heated at 500°C, 80 pct of the phosphorus became citrate soluble. The heated product, however, deteriorates markedly under moist conditions such as obtain in the soil.

Jan 1, 1950

By Mäkinen, Eero

OUTOKUMPU, a large copper mine in eastern Finland, has the distinction of being one of the few important mines in the world discovered by a geologist the late Otto Triistedt, of the Geological Sur- vey of Finland, having found the out- clop in 1910 by tracing glacial ore boulders, some of which had been carried as far as fifty kilometres. As the mine had no connection with either railways or waterways and the possibilities of transport were poor, the owners first tried the Hybinette hydrometallurgical process to extract the copper. The raw ore was finely crushed, treated by a sulphatizing roast. and then leached. The resulting solution was electrolyzed, using lead anodes. This experimental plant, having a capacity of 10,000 tons (all Ions are metric tons in this paper) of raw ore and producing 300 to LEO0 tons of electrolytic copper annually, was built in 1913 and run until dis-

Jan 1, 1938

By W. C. Ellis, E. S. Greiner, M. E. Fine

Discontinuous changes of Young's modulus, internal friction, coefficient of expansion, electrical resistivity, and thermoelectric power are evidence for a transition in chromium near 37OC. Although the X-ray diffraction pattern gives no clue, a difference between the thermal expansivity and the temperature dependence of the lattice parameter suggests a crystal-lographic change. Young's modulus data disclosed another transition near THE thermal dependence of a number of proper- ties of chromium indicates a transition occurring over a temperature range near room temperature. Bridgman' noted this first from a minimum in the electrical resistivity near 12°C. In a sample of greater purity, Sochtig' observed the minimum at 41 °C. Erfling3 reported an inflection in the thermal expansivity curve at 36°C. These temperature-dependence curves are reversible with no hysteresis being detected. No discontinuity or inflection has been observed in the heat capacity' or the paramagnetic susceptibility.' Likewise, no one has noted a change in crystal symmetry. In the present investigation Young's modulus, internal friction, coefficient of expansion, electrical resistivity, illustrated in Fig. 1, lattice constant, Fig. 2, thermal electromotive force, Fig. 3, and paramagnetic susceptibility, Fig. 4, were measured over an extended temperature range. The samples were prepared in two ways: (1) By cold pressing a sintered electrolytic powder compact,' and (2) by electroforming from an aqueous solution. The electroformed samples were prepared by R. A. Ehrhardt and G. Bittrich by plating on copper or nickel tubes from an aqueous solution according to the method of Brenner, Burkhead, and Jennings.' The pressed powder samples (method 1) were finally annealed at 1400°C in purified helium: the electroformed samples, packed in powdered chromium, were vacuum-annealed at 1000°C. From the composition of the original powder' the purity of the pressed powder samples is estimated to be 99.8 pct Cr. Spectrochemical analysis furnished by E. K. Jaycox, revealed only slight traces of impurities in the electroformed sample (less than 0.001 pct), neither iron nor nickel being detected. Chromium deposited by this method is reported to contain approximately 0.05 pct 0.- Methods and Data Young's Modulus: For measurement of Young's modulus, an annealed, pressed powder sample, 0.114 x0.237x1.845 in., and an electroformed sample, 0.10 in. od, 0.01 in. id, and 1.86 in. long, were prepared. The resonant frequencies of the rod samples in forced longitudinal vibration were measured at a series of temperatures from —192" to 200°C by a method previously de~cribed.6,7 Because the samples were nonferromagnetic, iron- silicon or molybdenum permalloy tips (0.013 in. thick) were soldered to the ends. The softening temperature of the solder limited the temperature of measurement. Young's modulus, E,, of chromium at temperature, T, may be calculated from the resonant frequency of the composite rod, f,; the thickness of the tips, t; the length of the chromium sample at 25°C, l,.; the density of chromium at 25°C, pc (7.20 g per cc);5 and the thermal expansivity, Al/l25. Modulus differences for two temperatures, ET and E, are accurate to +0.002x10" dynes per cm2. ET = 4PAlc+2tyf Young's modulus at 25°C, Fig. la, is 28.2~10" dynes per cm' (40.8xlO" si) in wrought chromium (upper curve). The modulus of the electroformed sample is apparently lower due to cracks. From the modulus measurements two transitions were observed: one with a critical temperature at 37°C, the other at —152°C. Internal Friction: The internal friction, 1/Q, was determined from the width, Af, of the strain amplitude-frequency curve at 0.707 times the strain amplitude at resonance;' the internal friction, 1/Q, then equals Af/f. Fig. lb shows a sharp peak in internal friction at 38°C. The internal friction of the electroformed sample had a similar maximum. Thermal Expansion: The expansivity measurements, shown in Fig. 2, covering the temperature range —195" to +400°C were made by D. MacNair in an interferometric dilatometer8 sing a sample consisting of three pyramids 0.25 in. high prepared from wrought electrolytic chromium. Below —120°C the experimental points deviated up to ±2x10 from the drawn expansivity curve in Fig. 2 because of decreased precision of the quartz wedge thermometer at low temperatures. Near 38°C the thermal expansivity curve, Fig. 2, goes through an inflection corresponding to a minimum in the coefficient of expansion, Fig. ld, and a relative volume decrease on heating. Electrical Resistivity: The variation of electrical resistivity with temperature measured by the po-tentiometric method is also shown in Fig. l. The resistivity of the wrought chromium (upper curve) at 20°C is 13.6 microhm-cm; of electroformed chromium (lower curve) 12.8 microhm-cm. The lower value reflects higher purity and agrees closely with a published value." A minimum at 40°C occurs in the resistivity curves of both samples. No conclusive evidence for a transition near — 150°C was observed, but the points, Fig. 1, appear to deviate from a smooth curve between —120" and —160°C.

Jan 1, 1952

By R. P. Fischer

The Colorado Plateau region has been the principal domestic source of uranium, vanadium, and radium. The value of these commodities produced from the region through 1964 slightly exceeds $2 billion. Most of the deposits occur in streamlaid lenses of sandstone in the Chinle and Morrison Formations. The ore minerals below the zone of oxidation are low-valent oxides and silicates of uranium and vanadium; all of these, except the quite stable vanadium silicates, oxidize readily to a variety of high-valent uranium and vanadium minerals. The ore minerals partly replace fossil wood but mainly impregnate sandstone, typically forming tabular ore bodies that are nearly concordant to the bedding of the host rock. The deposits range in size from those containing only a few tons of ore to those containing more than 1 million tons. Stratigraphic, lithologic, and sedimentary structural factors obviously influenced the localization of these deposits, but igneous activity, hydrothermal mineralization, and tectonic structures show no similarly consistent influence on localization. The deposits are epigenetic, but the source of the ore metals, the nature of the ore-bearing solutions, and the time of ore emplacement are uncertain. A few uranium deposits in the region are dominantly discordant to bedding and occur in collapsed breccia pipes or along linear fractures. Their origins are also uncertain.

Jan 1, 1968