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By Albert S. Trube

Increasing emphasis is being placed on the necessity for obtaining reasonably accurate estimates of the physical properties of reservoir fluids well in advance of more accurate laboratory data. One such factor is the isothermal coefficient of expansion of an undersaturated hydrocarbon liquid which may be contained in a particular reservoir. This coefficient, or liquid "compressibility", has often been assumed to be relatively insensitive and nearly constant. Although this assumption may be nearly correct in the case of high specific gravity liquids, it cannot apply in the case of medium to low specific gravity liquids. Any treatment of the nature of liquid compressibilities must give consideration to the variable nature of the isothermal expansion coefficient and the fact that it can be both pressure sensitive and temperature sensitive. The isothermal coefficient of expansion, or compressibility, of a substance is defined as -c = 1/V (?V/?p)T......(1) The value of Eq. 1 may be approximated for a finite pressure change by using the well-known relation, c = V1 - V1/Ve (p2-p1), ........(2) in which p1 > p1 and V2 > V2 and V1 + V2/2. The instantaneous compressibility may also be estimated from the slope of a curve on which log V is plotted vs pa. In this instance, it has been shown that c = In V1/V2/p2-p1 ...........(3) Eq. 3 may be used for variable compressibilities by plot-ting V vs p on semi-log paper. In this case, the instan-taneous or point compressibility is c = 2.303 m.......... . (4) in which m is the slope of the curve at a point in log cycles per psi. ISOTHERMAL COMPRESSIBILITY OF UNDERSATURATED LIQUID In the case of gases, the compressibility has been defined by Muskat' and others as Co = 1/p - ?z/z?p ..........(5) This was later generalized through application of the theorem of corresponding states' to co = 1/pr - (?z/z?pr) T8 ........(6) in which c, is defined as the pseudo-reduced compres-sibility and is numerically equal to (c.p,) and the sign is arbitrarily changed for mathematical convenience. Eq. 6 is general and applies to gases and liquids. In the case of liquids, c. = c1,pe, but if Eq. 6 is used, values of z and ?z/?p, must be determined for the liquid in question. The difficulty of obtaining accurate values of ?z/?p,, particularly in the region where T, is approaching 1.00, was pointed out in the previous paper'. This method of approach is unreliable for extension into computations of liquid compressibilities. On the other hand, c, can also be defined as follows: - Cr = 1/Vr (?Vr/?pr) Tr ......(7) and from which, Cr = 1/pr (?pr/?pr) Tr .....(8) In accordance with the theorem of corresponding states, Vr = V/Vr, p, = p/pr and pr = p/pr. Ref. 2 pro-vides an excellent source of reduced density, reduced pressure and reduced temperature data for a wide variety of fluids. For the purpose of this investigation, the set of fluids2 having ze = 0.27 was chosen because it in-cludes most of the heavier hydrocarbons usually found in those complex mixtures loosely defined as "reservoir oils". Data on undersaturated liquids in Ref. 2 were rearranged to conform with Eq. 8. To simplify the computation of cr, the isothermal p, data were plotted vs the log of pr, in which case for any straight line or tangent cr = 1/M pr pr .....(9)

Jan 1, 1958

By C. D. Johnson

Exploration work in 1932 in the Rocky Mountain region, which includes the states of Montana, Wyoming, Utah, Colorado and New Mexico, resulted in the discovery of one new oil field, Cut Bank in Glacier County, Montana; one new gas field, Craig in Moffat County, Colorado; and the definite outlining of a second gas field, Piceance Creek in Rio Blanco County, Colorado, in which there had been drilled but one small gas well prior to 1932. During the year, 95 producing oil or gas wells were completed, giving new initial production amounting to 188,000,000 cu. ft. of gas and 176,420 bbl. of oil per day for the region. By far the largest part of this new production of both oil and gas was developed in southeastern New Mexico, mainly the Hobbs field. However, the Dry Creek field of Carbon County, Montana, contributed over 5000 bbl. of; new oil production. Sixty-two wells were abandoned during the year but of this number only 10 promising structures were nonproductive. The remaining 52 wells had little to recommend their drilling from a structural or strati-graphical standpoint. Eighty-eight wells were suspended in the region' during 1932 before the tests had reached their individual objective horizons. Many of these suspensions were due to financial difficulties and it is possible that several of the operations may be resumed at a later date. At the close of the year, 54 wells were actively drilling, 54 were shut down and there were 20 rigs and locations in the five Rocky Mountain states. The accompanying table gives details of drilling and production.

Jan 1, 1933

By P. A. Witherspoon, R. W. Donovan, T. D. Mueller

The use of petroleum-barren aquifers for underground storage has become extremely important to the natural-gas industry. A critical problem in assessing the feasibility of a specific aquifer for such use is the permeability determination of the caprock over the proposed storage project. The approach used here is to conduct both static and dynamic field tests on the aquifer being analyzed. Valuable information on the possibility of communication between the storage aquifer and any other aquifers above can be obtained by measuring hydrostatic water levels and water analyses. Significant differences in such data give evidence of the lack of communication between the intended storage reservoir and other horizons. The dynamic approach requires that one well be pumped in the storage aquifer, and changes in fluid levels recorded in both the aquifer and its caprock. The interpretation of the data from such pumping tests involves the solution of nonsteady radial flow in an infinite aquifer and the influence on such flow of a leaky caprock. A finite-difference model has been used to investigate this problem, and the transient behavior has been solved numerically with a digital computer. It has been found that the pressure transients in the storage aquifer are not affected significantly by moderate caprock leakage. The pressure behavior of the caprock is a much better indicator of the degree of leakage, and generalized solutions for this behavior are included. Field data are presented to demonstrate both the static and dynamic approach. If is concluded that appropriate investigation of the groundwater hydrology in an aquifer-type gas-storage project can provide much valuable information for determining the effectiveness of the caprock to hold gas. INTRODUCTION Underground storage of natural gas in the United States has been developing at a rapid rate over the past few years. In 1955, the total gas-storage capacity was about 1.6 trillion cu ft; by 1961, this figure was almost 3.2 trillion cu ft, an increase of 100 per cent in six years.' This trend un- doubtedly will continue because the economics favor the development of gas storage, as opposed to the construction of new pipelines, to meet the inherent cyclic demand for fuel in the metropolitan areas of this country.' About 15 per cent of the current underground gas storage has been developed in petroleum-barren aquifers, i.e., geological domes or anticlines in which no commercial quantities of oil or gas had been produced prior to the storage operations. The necessity for using barren aquifers outside many metropolitan areas of this country has been due to the lack of depleted oil or gas fields that were near enough and large enough to meet the demands of such consuming areas. Pipeline companies have developed aquifer storage along their transmission lines to meet the fluctuating needs of their complex systems. Considerable thought has also been given to the problem of storing gas in a structureless aquifer, both in this country' and in the Soviet Union outside the city of Leningrad.'," Conditions such as these have led to the development of aquifer gas-storage projects in many parts of the U. S. Most of these developments have centered in the Mid-Continent area, and the greatest amount of activity has been concentrated in Illinois.6 Thus, the use of petroleum-barren aquifers for gas-storage purposes has become extremely important to the natural-gas industry. There are three basic problems in developing aquifer-type storage: (1) finding an adequate geologic structure, (2) finding a suitable storage reservoir within the structure and (3) determining the tightness of the caprock over the intended storage zone. The first two problems can be solved by applying conventional methods of exploration geology, but once these problems are solved, the question arises as to why no oil or gas is present in an otherwise favorable setting. Two situations are possible: (1) an adequate source bed was never present, or (2) a source bed was present but the petroleum seeped away because of a leaky caprock. Determining the tightness of the caprock is one of the most critical problems in assessing the feasibility of a specific aquifer for storage purposes. In attacking this problem, one usually takes cores of the caprock and subjects them to a rigorous investigation. Such core data are desirable, but they only detail the matrix properties and cannot be expected to reveal the gross characteristics of the caprock. Several gas-storage projects in the U. S. have had considerable leakage where

By Charles S. Barrett, Frederick N. Rhines, Robert F. Mehl

The solid solutions which aluminum forms with copper, and with magnesium and silicon, are not extensive, and accordingly could not be expected to form Widmanstatten figures profusely nor with great ease. A study of the Widmanstatten figures in these systems seemed desirable, however, because of the interest which these alloys bear towards age-hardening theories resulting from the necessary relationship between the age-hardening phenomena and the atomic processes leading to the formation of Widmanstatten figures.' Alloys of Aluminum with Copper The most accurate determination of the solid solubi1it.y of copper in aluminum seems to be that by Dix and Richardsoq2 whose results are represented in Fig. 1. According to this work, aluminum dissolves 5.6 weight per cent of copper at 548", and less than one per cent at room temperature. Judging from the constitutional diagram, this solid solu-lion on cooling tends to precipitate the compound CuA12, and this conclusion has been confirmed experimentally by Schmid and Wassermann.

Jan 1, 1932

By A. F. Lucas

The discovery of oil in 1901 on the Spindletop dome, Texas, inaugurated a new industry on the Gulf Coast, an industry which has gran with the discovery of successive fields, until today it engages the services of thousands of workers and employs enormous capital. New fields are being discovered from time to time and doubtless some still remain to be found, though of late years discoveries have become more infrequent. Nowadays several hundred dry holes are drilled each year in a fruitless and blind effort to discover new fields, for as yet geologic science has developed no effectual method of locating the coastal oil deposits in advance of drilling. Moreover despite the occasional discovery of new fields, the total production of the Gulf Coast is today no greater than it was in 1906, for the added production of the new fields has been offset by the rapid decline and more or less complete exhaustion of some of the older ones. Careful geologic work within the fields has in some cases increased the production temporarily, but has developed no really new supplies. The Gulf Coast oil industry seems to have passed its period of greatest expansion and to be declining at a fairly steady rate, and this condition is naturally viewed with alarm by the more farsighted operators. In my opinion, the time has come for the adoption of radical and aggressive methods of prospecting; and a fraction of the money wasted yearly in drilling shallow wells in hopeless locations might well be devoted to this purpose. Many facts lead me to believe that all the salt-dome oil has had a common origin; that it has migrated up from considerable depth along lines of structural weakness; and that a deep well, properly located, stands an excellent chance of discovering the parent reservoir and thus of developing new and probably great supplies. This paper is presented as a discussion—necessarily hypothetical and based largely on personal opinion—of the possibility of encountering deep-seated oil deposits beneath the salt domes. Salt-dome Structure All of the oil produced in the coastal region of Texas and Louisiana is probably associated with salt domes, though in Goose Creek, Edgerly, and one or two other fields no salt has yet been actually penetrated. As

Jan 1, 1920

By Bernard N. Moore

At present the demands of the United States for strorltium are met by imports from Germany, England and Canada, which vary considerably in proportions of ore and finished salts, in tonnage and in value. Statistics for the period 1926-1932 are given in Table 1. Domestic deposits arc known in many states, but the larger and purer ones are in the West, particularly in the desert region of southeastern California and western Arizona. These deposits are large enough to command interest, particularly in consideration of future cheap power at the Boulder Dam. The deposits described in this paper were examined during an investigation of the mineral resources of the Boulder Dam region by the United States Geological Survey for the United States Bureau of Reclamation in the spring of 1934. Mr. D. F. Hewett, who had general charge of the investigation, Mr. W. T. Schaller and Mr. M. I. Goldman contributed many helpful suggestions. Mr. N. H. Harshman assisted efficiently during the field work. Celestite Deposits The celestite deposits described in this paper are of sedimentary origin and Tertiary age. They are widely scattered, as shown on Fig. 1,

Jan 1, 1935

By Bernard N. Moore

At present the demands of the United States for strorltium are met by imports from Germany, England and Canada, which vary considerably in proportions of ore and finished salts, in tonnage and in value. Statistics for the period 1926-1932 are given in Table 1. Domestic deposits arc known in many states, but the larger and purer ones are in the West, particularly in the desert region of southeastern California and western Arizona. These deposits are large enough to command interest, particularly in consideration of future cheap power at the Boulder Dam. The deposits described in this paper were examined during an investigation of the mineral resources of the Boulder Dam region by the United States Geological Survey for the United States Bureau of Reclamation in the spring of 1934. Mr. D. F. Hewett, who had general charge of the investigation, Mr. W. T. Schaller and Mr. M. I. Goldman contributed many helpful suggestions. Mr. N. H. Harshman assisted efficiently during the field work. Celestite Deposits The celestite deposits described in this paper are of sedimentary origin and Tertiary age. They are widely scattered, as shown on Fig. 1,

Jan 1, 1935

By Noel Stearn

OF THE many instruments devised for the measurement of magnetic anomalies, the ordinary dip needle, by virtue of its superior simplicity of construction, facility of manipulation, and definiteness of interpretation, seems to merit serious attention as the instrument most readily applicable to the detection of magnetic anomalies of the higher order of magnitude. , In spite of the fact that it has been used for many years for the discovery of iron ore in Europe and in the Lake Superior region of America, its capabilities as a geological instrument have not yet been thoroughly plumbed. The Wisconsin Geological Survey, under Dr. W. 0. Hotchkiss, E. F. Bean, and H. R. Aldrich, has been most thorough in developing the technique of the instrument, and the results it has obtained have aroused a general interest in a more widespread use of geomagnetics as an exploration method and the dip needle as a geological instrument. The simplicity of the instrument is an especial advantage, as it can be used by anyone, regardless of his technical training; but to insure useful results not only is a knowledge of the background of geomagnetics necessary but also an understanding of the principles of the instrument itself.

Jan 1, 1928

PRESIDENT L. D. RICKETTS,1 NEW YORK, N. Y. PAST PRESIDENTS BENJAMIN B. THAYER,1 NEW YORK, N, Y. WILLIAM L. SAUNDERS,2 NEW YORK, N. Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS,1 NEW YORK, N. Y. TREASURER GEORGE C. STONE,1 NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W.. RAYMOND NEW YORK, N. Y SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 6, 1916

PRESIDENT L. D. RICKETTS,1 NEW YORK, N. Y. PAST PRESIDENTS BENJAMIN B. THAYER,1 NEW YORK, N. Y. WILLIAM L. SAUNDERS,2 NEW YORK, N. Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS1 NEW YORK, '_N. Y. TREASURER GEORGE C. STONE,1 NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y. SECRETARY BRADLEY STOUGHTON NEW YORK, N. Y.

Jan 4, 1916

By Michael Chender

The current outlook for financing new copper production is not very encouraging. At a time when companies are slogging through a protracted period of low prices as well as having to accept lower profits due to more stringent tax and royalty schedules, banks are beginning to require companies to take a greater equity interest in new projects. Mineral resource financing, including copper, seems to have lost much of its appeal to the lending institutions, and loans of any kind to many of the developing countries -from which over half of new copper capacity could be expected to come-are being examined much more critically than they were in the late 1960's and early 1970's.

Jan 12, 1976

Spencer Gulf takes off from the Great Australian Bight cutting a 200 mile deep wedge of water into the South Australia coastline. A pale winter sun shines yellowly on the choppy surface of this body of water which is progressively more salty as it approaches Port Augusta at the head of the Gulf. Once Port Augusta thrived as a grain port and the speedy clipper ships began or ended their legendary races there. On the eastern shores of Spencer Gulf, farm land spreads away from the water's edge. The western side of the gulf meets marginal grazing land of acacia tree and salt bush. Part way down the gulf, there are two industrial towns facing each other from opposite shores; Port Pirie on the east and Whyalla on the west. These towns are like half brothers, the common parent being the founders of Broken Hill Pty. Ltd., (BHP) who began lead smelting at Port Pirie and discovered iron ore near Whyalla needed for the lead smelting process. The iron deposits later became the inspiration for BHP's iron and steel business.

Jan 10, 1964

By Richard Hodgson

FMC Corporation, at their mine and soda ash refinery near Green River, Wyoming, currently mines in excess of 3 million tons per year of trona. Upon completion of the current expansion, the mine will be producing in excess of 4.0 million tons per year. The single level mine, approximately 1,500 feet in depth, is currently serviced by five (5) concrete lined circular shafts varying in diameter from 12 ft. to 24 ft. A sixth shaft is complete, but not yet operational and the seventh is currently being sunk. Two of the shafts are equipped with single drum hoists. The original production shaft is equipped with a double drum hoist. The newest production shaft and the main service shaft are both equipped with ground mounted friction hoists. These friction hoists have given excellent service and another will soon be installed as a man and material hoist at No. 7 Shaft. There are a number of advantages that the ground mounted hoist has over a tower mounted hoist. There are also operating problems common to both. FMC's original experience with ground mounted friction hoists began in 1962 with the conversion of a single drum hoist to a friction hoist. The converted hoist was an Ottumwa with a 5 ft. diameter drum and a 4 ft. face. This hoist had been installed at the No. 3 Shaft for some years prior to its conversion to a friction hoist. At the time the conversion of this hoist was made, there were no friction hoists in service in Wyoming. Wyoming mining laws required that all conveyances carrying men be equipped with safety dogs. Since it was desired that wire rope guides be used, safety dogs were impractical. Agreement was reached with the State Mine Inspectors that safety dogs would not be necessary provided that recommended rope safety factors for hoisting men would still be maintained if one hoisting rope was broken. Since-the shaft is approximately 1,500 ft. deep, the recommended safety factor is 6.0 so that this installation has a safety factor in excess of 8.0 for hoisting men when new ropes have been installed. The hoist conversion was engineered by Lake Shore, Incorporated. The friction ring was made in halves and bolted over the original drum face which had been machined to remove the grooves. The ring provided for four 3/4 in. diameter ropes on 8 inch center to center spacing. The pitch diameter of the modified drum was 72 inches. The grove liners are hald in place by hard-wood wedges bolted to the drum. The other modification required by the conversion was an increase in size of bearing caps and the hold-down bolts because of the increased force tending to lift the drum.

Jan 1, 1975

By J. C. Allen, E. V. Herring

CHILE EXPLORATION CO's. oxide plant at Chuquicamata, the largest of its kind, started in 1915 with initial operations at the rate of 10,000 tons of ore per day. Anaconda Copper Mining Co. acquired the controlling interest in 1923 and in the next few years modernized the plant and mine, extending operations to a nominal capacity of 490 million lb of electrolytic copper yearly by 1942. Plant production averaging 495.7 million lb of copper per year was maintained for the eight-year period extending from 1941 to 1948 inclusive. During the World War II production reached its highest level when in 1944 the output was 531.8 million lb. The maximum production for any one month was 49.6 million lb, achieved in May 1947. E. A. Cappelen Smith, consulting metallurgist for M. Guggenheim's Sons, worked out the first process for the treatment of Chuquicamata copper oxide ore about 1913, and directed a staff of 20 young engineers operating a pilot plant at Perth Amboy, N. J., on three shifts for an entire year. The copper is extracted from the oxide ore by a hydro-metallurgical treatment described in detail by T. A. Campbell in AIME Transactions, Vol. 106, Copper Metallurgy, 1933. The Oxide Plant is divided into five main operations as follows: (1) Crushing, (2) Leaching, including dechloridizing and sulphur dioxide treatment, (3) Tailing disposal, (4) Electrolytic precipitation, (5) Smelting and melting. Crushing The present Primary Crushing Plant has been in operation 25 years, during which time 4,342,112 cars of 70 tons net capacity have passed through the dumpers. The ore as received from the mine is frequently blocky and up to 5 feet in section. It is reduced to 9-in. size by two 60-in. gyratory crushers, and transported to the east and west ore bins by 60-in. conveyors. In the secondary crushing operation the ore is first reduced to 2 to 3-in. size by five standard 7-ft cone crushers and two No. 10 gyratories. This product is then reduced to 3/8-in. size by fifty-two 48-in. vertical Symons disc crushers and is transported by belt conveyors to the loading bridges from which it is charged° into the leaching vats. Conveyor belt No. 14 which serves the eight vats in the east section of the leaching plant has transported over 125 million tons of ore, which is a record for any type of conveyor. This 60-in. belt travels at a speed of 600 fpm and carries loads up to 5500 tons per hr. Leaching The ore is leached in 14 vats, averaging 13,500 short tons net capacity each. These vats are lined with a natural mastic which adequately resists the sulphuric acid leaching solutions. The leaching process as presently conducted comprises soaking the ore with successive volumes of leaching solution and spent electrolyte and withdrawing successive volumes of enriched solution from the vat to a total of approximately 3.2 million gal. The first 1.6 million gal of this volume withdrawn is called strong solution and contains about 35 parts of copper per 1000. The balance of 1.6 million gal subsequently withdrawn is stored in a

Jan 1, 1952

By J. A. Musselman, P. F. Gnirk

A study was made of indexed penetrations by a single dull bit tooth under statically applied loads into rock subjected to confining pressures from atmospheric to 5,000 p.si and atmospheric pore pressure. Experimental results obtained with a 45" wedge tooth over the above range of pressures are presented for two limestones and a sandstone, a variely of indexing distances and two degrees of tooth dullness. The optimum distance between successive bit-tooth penetrations required for maximum rock damage and chip formation decreases substantially with increa.sing confining pressure above the brittle-to-ductile transition pressure of a particular rock. However, the distance remains approximately constant for a variation in confining pressure below the transition pressure. At a given confining pressure, the bit-tooth force required lor chip formation is constant for indexing distances greater than optimum, but generally decreases linearly with decreasing indexing distance for distances less than optimum. The chip-formation force data obtained at confining pressures for which the chip-generation mechanism is macroscopic-ally of a pseudoplastic nature compare favorably with previous theoretical results for indexed dull hit-tooth penetrntion into an idealized, rigid, perfectly plastic rock. INTRODUCTION To study the cutting action of a roller-cone bit, the interaction of a penetrating bit tooth with craters formed in a rock surfacc by the passage of previous bit teeth must be considered. Current knowledge of the basic mechanics of bit tooth-rock intcract:on under simulated borehole environmental conditions has been extensively reviewed.',' Particularly of current interest are the effects of bit-tooth shape, distance between successive penetrations and differential pressure at the rock surface on the extent of the interaction. Pertinent to this paper are results of an experimental investigationb f the interaction between successive penetrations by sharp, wedge-shaped bit teeth. It was demonstrated that both bit-tooth angle and differential pressure influence the extent of rock damage between successive bit-tooth penetrations. Specifically, the optimum or minimum distance between successive penetrations required for maximum interact'on or chip generation tends to decrease with decreasing bit-tooth angle and increasing differential pressure. In addition, at differential pressures on the order of 2,000 psi for four va- rieties of limestones and sandstones, the macroscopic mechanism of chip formation exhibits a transition from brittle to ductile. In this paper, experimental consideration is given to successive or indexed penetrat ons by wedge-shaped bit teeth. Since pore pressure in a rock sample is maintained at atmospheric pressure, the differential pressure at the fluid-rock interface is equal to the confining pressure. The degrees of bit-tooth dullness include teeth with flat and round apexes (Fig. 1). Of primary concern in this paper are the bit-tooth forces required for chip formation, the macroscopic mechanism of chip formation and the minimum distance between successive penetrations, i.e., optimum indexing distance required for maximum rock damage, as functions of differential pressure. Of further interest is a comparison of actual bit-tooth chip formation forces at elevated differential pressures with calculated forces from previous theoretical results4 for indexed dull bit tooth penetration into a rigid-plastic rock. EXPERIMENTAL APPARATUS AND PROCEDURE The experimental apparatus consists of a pressure vessel equipped with a piston through the side of the vessel (Fig. 2). A single bit tooth inserted in the lower end of the piston is forced at a desired rate into the rock when the ram pressure chamber is pressurized. Electrical instrumentation incorporated into the apparatus yields a graphical plot of force on the piston as a function of bit-tooth penetration or displacement into the rock. Since the piston and ram assembly are in force equilibrium for a constant confining pressure in the main vessel, the fluid volume in the vessel remains constant during bit-tooth penetration. Hence, the force resisting penetration of the tooth is independent of the force exerted on either end of the as-

SUCCESSFUL development of a new process for heat hardening of pellets made from taconite concentrates was announced by Arthur G. McKee & CO., steel plant engineering and construction firm of Cleveland, and Allis-Chalmers Mfg. Co. An order for the design, engineering, and materials for a plant incorporating the process, has been received by the McKee Co. from the Reserve Mining Co. for its new E. W. Davis Works at Silver Bay, Minn. It is estimated that this plant will cost around $19 million and when in full operation, will turn out 12,000 tons of pellets per day.

Jan 10, 1954

PRESIDENT BENJAMIN B. THAYER,1 NEW YORK, N. Y. PAST PRESIDENTS JAMES F. KEMP,1 NEW YORK, N. Y. CHARLES F. RAND,2 NEW YORK, N. Y. FIRST VICE-PRESIDENT SIDNEY J. JENNINGS,1 NEW YORK, N. Y. TREASURER GEORGE C. STONE,1 NEW YORK, N. Y. SECRETARY EMERITUS ROSSITER W. RAYMOND, NEW YORK, N. Y.

Jan 4, 1914

By K. D. Jacob, H. L. Marshall, D. S. Reynolds

All types of commercial phosphate rock produced throughout the world contain fluorine in quantities ranging from approximately 0.4 to 1.3 per cent in the Curacao and Christmas Island phosphates to 3.1 to 4.2 per cent in the phosphates of the United States and North Africa1. For a given type of rock, the fluorine content is usually roughly proportional to the phosphorus content. Significance of Fluorine in Phosphate Rock On the basis of chemical and X-ray diffraction studies, Hendricks and co-workers2 concluded that fluorapatite, Cal10F2(PO4)6, is the essential phosphatic constituent of the commercial types of domestic phosphate rock. On the other hand, Bredig and co-workers3 have recently advanced the opinion, also based on X-ray diffraction studies, that the mineral phosphates usually contain carbon dioxide in the apatite lattice, and that the phosphate rocks of the United States are really fluorcarbonate apatites. However, the domestic types of phosphate rock do not seem to differ greatly from coarsely crystalline fluorapatite in their behavior toward chemical reagents in general, and for the purpose of this paper it will suffice to consider fluorapatite as being the essential phosphatic constituent of these types of rock. The available data1 indicate that the different commercial types of domestic phosphate rock usually contain about 12 to 52 per cent more fluorine than theoretically is required to form fluorapatite with all the phosphorus. Calcium fluoride (fluorite) has been definitely identified in only a very few of the samples that have been examined1,2. Bredig and co-workers4 state that fluorapatite can take into its crystal lattice excess calcium fluoride to the extent of approximately 70 per cent of that theoretically required by the formula Ca10F²(PO4)6 without causing more

Jan 1, 1938

By D. S. Reynolds, K. D. Jacob, H. L. Marshall

All types of commercial phosphate rock produced throughout the world contain fluorine in quantities ranging from approximately 0.4 to 1.3 per cent in the Curacao and Christmas Island phosphates to 3.1 to 4.2 per cent in the phosphates of the United States and North Africa1. For a given type of rock, the fluorine content is usually roughly proportional to the phosphorus content. Significance of Fluorine in Phosphate Rock On the basis of chemical and X-ray diffraction studies, Hendricks and co-workers2 concluded that fluorapatite, Cal10F2(PO4)6, is the essential phosphatic constituent of the commercial types of domestic phosphate rock. On the other hand, Bredig and co-workers3 have recently advanced the opinion, also based on X-ray diffraction studies, that the mineral phosphates usually contain carbon dioxide in the apatite lattice, and that the phosphate rocks of the United States are really fluorcarbonate apatites. However, the domestic types of phosphate rock do not seem to differ greatly from coarsely crystalline fluorapatite in their behavior toward chemical reagents in general, and for the purpose of this paper it will suffice to consider fluorapatite as being the essential phosphatic constituent of these types of rock. The available data1 indicate that the different commercial types of domestic phosphate rock usually contain about 12 to 52 per cent more fluorine than theoretically is required to form fluorapatite with all the phosphorus. Calcium fluoride (fluorite) has been definitely identified in only a very few of the samples that have been examined1,2. Bredig and co-workers4 state that fluorapatite can take into its crystal lattice excess calcium fluoride to the extent of approximately 70 per cent of that theoretically required by the formula Ca10F²(PO4)6 without causing more

Jan 1, 1938

By W. M. Bertholf

To establish the minimum or break-even efficiency of a preparation plant it is necessary to determine the ratio of production costs per ton of run-of-mine coal to sale price per ton of clean coal. This ratio is then divided by the percentage of plant recovery. Assume, for example, that washability data indicate that 80 pct of the run-of-mine coal may be recovered as clean coal selling for $5.50 per ton. If the same plant incurs $4.00 per ton mining costs and $0.25 per ton preparation costs, the cost to sale price ratio would be 4.25/5.50, or 77.3 pct. Since the plant is capable of recovering 80 pct of the run-of-mine coal the minimum plant efficiency would be 77.3/80, or 96.6 pct. If the plant efficiency were increased to 100 pct the limit on preparation costs would be increased to $0.40. Therefore, the washing operation must be accomplished at a cost of $0.25 to $0.40 per ton and the efficiency must be 96.6 pct or higher. By plotting a curve of efficiency vs preparation costs and taking into consideration the plant cost, feed rate, operating costs, and yields of the various flowsheets it is possible to select a financially sound process. Table I classifies preparation processes according to their nature of separation. It must be remembered that what is thought to be ideal does not always prove practical under actual operation. An outstanding example is the work done on the plunger-type jig. It was determined by the law of equivalence that this unit could treat satisfactorily only sizes differing by no more than a ratio of 2. Yet these same plunger-type jigs are successfully treating sizes considerably greater than this ratio.

Jan 12, 1957