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By R. F. Stilwell

There are three things that all coal consumers look for when they burn coal: (1) suitability for their particular requirements and burning equipment, (2) uniformity of shipments, and (3) quality as expressed by heating value and other chemical and physical tests. Suitability, or proper application, is determined generally from previous buying experience. It is a function of (1) the reliability and integrity of the shipper and distributor, (2) of a certain coal field or seam and of (3) uniformity and quality. Quality is limited by the location and geology of the seam and mine, the mining and preparation methods and equipment and the knowledge and ability of the personnel. Uniformity of shipments is in many ways the most important factor in coal selection. Lack of uniformity in chemical quality, size consist and treatment cause most of the customer complaints that arise from faults of the coal shipper. Lack of uniformity destroys suitability and quality standards, causing a large customer turnover, and greatly increases sales expense and reduces the net return to the operator. Oil and gas fuels are more uniform in quality than solid fuels, and there will be more gas and oil competition for coal markets after this war than before, because the size of their market is a direct function of the dimensions of their pipe lines, which have been greatly increased during the war. Present mechanical coal-cleaning equipment based upon gravity concentration has gone a long way toward giving us a coal of uniform ash content. The chart in Fig. I, by Hebley,1 shows the greater uniformity of the ash content of washed coal as compared with that of raw coal. Wide variation in the nature and amount of ash in the coal feed to the washer leads to a coal of non-uniform ash content. Mechanica1 cleaning equipment does not understand such terms as ash-softening temperature, coking properties, size consist and sulphur content. Unless the feed to the washer is uniform, the washed coal probably will not be uniform. Table I shows the ash, sulphur and ash-softening temperature of two mines in the Pittsburgh bed, both raw and washed, loaded over the same tipple; also No. 3 and No. 4 Pocahontas seams, both raw and washed, loaded from the same preparation plant. It is obvious that they must be blended or loaded separately if a uniform product is to be obtained. Why Is Blending Necessary? It was natural for the operators of captive mines producing by-product coals to recognize the necessity for blending raw coals of different quality and coking characteristics. They have had many years of experience with blending high, low and medium volatile coals at their oven plants. They have found that careful blending gives a coke of more uniform quality and better structure. Coals that could not be

Jan 1, 1947

By Carl Floe

A NUMBER of proposals have been made for the hydrometallurgical recovery of copper from flotation concentrates, but as yet no process has been developed that has demonstrated an ability to compete with the present smelting methods under ordinary conditions. The treat-ment of copper concentrates by hydrometallurgical methods is in general similar to that used in the present electrolytic zinc process and involves roasting, leaching with H2S04 solution, separation of solutions, control of impurities and electrodeposition. While many of these steps are simpler and more readily carried out for copper than for zinc, a number of inherent difficulties have prevented the general adoption of the process. To compete with smelting, the following problems must still be con-fronted, although many solutions for their have been proposed: (1) con-duction of the roast in such a way that leaching will give an extraction of copper comparable to that obtained by smelting; (2) regulation of the ferric iron content of the solutions during electrolysis; (3) disposal of the excess acid regenerated from the sulphates formed in roasting; (4) eco-nomical recovery of the precious metals from the leach residues. The roasting problem is largely one of preventing the formation of copper ferrites, CuO.Fe2O, and Cu20.Fe2O3, which are quite insoluble in dilute sulphuric acid. These ferrites are apparently formed' to a small extent even at low temperatures and above 650° C. their formation is rapid1. While it is possible to carry out laboratory roasts in such a way that less than 5 per cent of the total copper is present in the insoluble ferrite form, a closer temperature control is required than can readily be obtained in industrial furnaces. The flash" roasting effects and consequent high temperatures that occur as the calcine falls from hearth to hearth in the ordinary multiple-hearth roaster are probably largely responsible for the inevitable formation of some ferrites. The result is that in a commercial plant the extraction of copper would not average more than 90 per cent in a single 10 per cent H2SO4 leach. This is

Jan 1, 1937

By J. H. Palm

Experiments have shown12 that the formula -S = St - (St - Se')e ne [1] expresses very well the relation between the true stress S and the true form monotonic deformation of plastic metals in single tension and compression (Fig 1). St (asymptotic or final stress), Se' (threshold stress) and ne (characteristic or specific strain) are constants, the significance of which immediately follows from Fig 1. Only at the initial stages of deformation the experimental curve runs below the theoretical curve. This may be due, at least partly, to the uneven stress distribution caused by the anisotropy of the crystals. It is now obvious that a similar formula H = Ht- (Ht- He)e ne' [2] might be valid for the relation between the hardness and the strain. The hardness can be only a function of the strain and must therefore be independent on the hydrostatic tension present in the neck during straining. Hence, if Eq 2 is correct it will also represent the relation between hardness and strain in the middle section of the neck, the strain of which is generally assumed to be almost or fully homogeneous. For aluminum, copper, and several copper alloys it is indeed observed that Eq 2 agrees very well with the experimental Vickers hardness-strain relation from zero strain on up to the strain at fracture. Moreover nc' is, for several metals fairly equal to nc- Hence H = C1 + C2S [3] C1 and C2 are constants during uniform uniaxial tension. Eq 3 was also obtained for copper by Voce.3 According to Hencky's theory4 the ratio of the Brinell or Vickers hardness and the yieldstress (expressed in kg per mm2) of a non-strainhardening metal is approximately equal to 2.8. If Eq 1, 2 and 3 are correct the ratio Ht/S, must accordingly be the same for all plastic metals and be equal to 2.8. It is now experimentally established that this ratio varies between 2.7 and 3.1 with a mean value of 2.9. Taking into account that Ht and especially St can be obtained only by extrapolation from the range of rather low strains, the agreement with the theory is very satisfactory. References 1. J. H. Palm: Appl. Sci. Res. Al (1948) 198. 2. E. Voce: Jnl. Inst. of Met. (1948) 74, II, 537. 3. E. Voce: Metal Treatment (1948) 15, 53. 4. H. Hencky: Zlsch. f. angew. Math. and Mech. (1923) 3, 241.

Jan 1, 1950

By William M. Agar

Now that both the national and state legislatures are seeking ways of reducing expenses, the appropriations for geological investigation and for the study of mineral resources have been greatly reduced and in some cases entirely stopped. Is this policy justified? The sums saved by these reductions are always small. If the work accomplished by these surveys has no intrinsic value to the community, but is only an interesting way of spending some of the people's money when that money is plentiful, there should be no surveys at any time. If, on the other hand, they perform a necessary function, it is indeed foolish and short-sighted to save these paltry sums to the detriment of the community. It is not my purpose to undertake a general justification of geological surveys. Rather, 1 wish to call attention to the work of one state survey that has been discontinued, and to indicate ways in which the work was valuable to the people, even though that state's mineral resources are not very important, and why it should be continued. Though at one time in Connecticut's history iron mining and smelting were important, and copper was mined in appreciable quantities in two localities, it is many years since it could be regarded as a mining state. At present Connecticut stands far down among the states in the value of its mineral products. Granite for architectural and structural purposes, trap rock, clay, agricultural lime, feldspar and quartz, together with a few other nonmetallic minerals, are produced in appreciable quantities, but the natural resources of the state consist at present much more largely in its attractive scenery, woods, lakes, shore line, and in the opportunities that these offer for rest and recreation. Is the prosecution of geological work in such a state a waste of the taxpayer's money? Or can it be that though it was formerly valuable, the work is now completed? The only way to answer these questions is to review the geological work done in the past and to consider the type of information the people want, as reflected in the requests that have been received by the director of the survey in the last few years. There have been two periods during which Connecticut has supported geological work within its borders. The first began in 1835 when Percival

Jan 1, 1935

By H. L. Barr

THE following report covers the history of the development of the mine, present equipment, methods and costs of mining and milling. In addition, a description of the ore deposit is given with emphasis on the origin of the fractures, mode and types of ore occurrence, and mechanics of granite emplacement. An endeavor has been made to present a complete and accurate statement of the San Mauricio mine, the highest grade gold mine in the Philippine Islands. Credit is gratefully acknowledged to the mine staff for descriptions and details regarding their particular field of work. All analyses were made by Mr. T. A. DeVore, head chemist, San Mauricio Mining Co. Messrs. Edward Wisser, J. E. Fyfe, A. F. Skerl and W. B. Meek, geol-ogists, have contributed geologic information and ideas, for which thanks are extended. The Executive Committee of Marsman and Co., Inc., Managers of the Company, has kindly given permission for publication. Mr. J. B. Stapler, Division Manager, Marsman and Co., has had the courtesy to read the manuscript and to give critical and helpful suggestions.

Jan 1, 1940

Jan 1, 1916

By J. R. Campbell

THE need for standardizing methods of arriving at definite conclusions regarding the cleanability of a given coal, and for measuring the performance of coal-cleaning equipment, is constantly increasing. Earlier notes by the author on this subject are amplified in this paper, because he believes that better preparation of bituminous coal is a partial solution of the coal operators' troubles. WASHABILITY STUDIES The term "washability" of coal was coined when washing was the universal method of separating coal from its impurities by utilizing their difference in specific gravity. This and analogous terms are still used in their broad sense although pneumatic or air separation is now used to clean coal. These terms are so used in this paper. Too much time or money, can hardly be spent on "feed surveys" to get a "picture" of the coal that is to be cleaned. There have been too many "rule of thumb" methods used. Screen analyses and "sink-and-float" tests on the raw coal enable the coal operator and washery man to predict within reasonable limits the results that may be expected from any efficient cleaning apparatus.

Jan 1, 1928

Page Foreword—H. Foster Bain........................ 9 Letter of Transmittal—F. Julius Fohs...................11

Jan 1, 1927

By William P. Blake

The copper-beariug rock formations of Cananea, Sonora, Mexico, present conclusive evidences of extensive and sharp plication. Some of these evidences are here briefly stated. 1. There is a succession of approximately parallel outcrops of an altered limestone, alternating with dikes and masses of porphyry. The great copper-ore deposits are in close association with these ridges of limestone, which trend northerly and southerly and stand nearly vertical. This parallel succession is so well-defined that the management of the mines has, for convenience, recognized and named five zones, known from the chief mines, in their succession from east to west, as the " Cobre-Grande," " Veta-Grande," " Esperanza," " Capote," and " Puertocitas " belts. The intervening and separating formations are coarsely crystalline feldspar porphyries, highly basic, of light color, which may be regarded as intrusive and, in part at least, as the cause of the metamorphosed condition of the limestone. 2. These cupriferous limestone-zones are similar in constitution, are similarly charged with copper-ore (in association with quartz as a gangue, or veinstone), and are marked by similar croppiugs of gossan. 3. Distinctly folded outcrops of the surrounding strata can be observed, especially on the eastern border of the copper-bearing district north of the Democrita ground, and not far from the Veta-Grande. 4. The limestone ridge adjoining the Veta-Grande ends a short distance north of the mine, and appears to be the extretne end of a synclinal trough. 5. The Capote limestone, the most western of the croppings of the central copper-bearing area, is contiguous to stratified sandstones and quartzites, uplifted at high angles, but showing an easterly dip. The Capote limestone is apparently conformable

Jan 1, 1905

By Robert B. Fulton

The objective of this chapter is to discuss the interrelationship between industrial minerals and chemical manufacturing. It is intended to supplement rather than duplicate the commodity chapters. Particular emphasis is given to the pertinent chemical element and to market factors. Condensing this broad subject into a few pages of this handbook permits treating only the most important elements derived from industrial minerals. Hydrocarbons, which quantitatively dominate as raw materials for the chemical industry, are omitted, as are the metallic elements and the minerals covered in other "use" chapters such as phosphorous, potassium and nitrogen for fertilizers, and titanium dioxide for pigments. The remaining six elements of major importance are: boron, bromine, chlorine, fluorine, sodium, and sulfur. These elements are treated individually under separate headings. Table I (Jones, 1973) affords an overview of the main industrial minerals, the chemical products derived from them, and end uses of the products. Salt brines have particular importance as raw material sources for the chemical industry. Table 2 (Anon., 1967) is a chart of the chemical compounds derived from four types of brines: (1) Owens Lake-type brines, which are sources of boron and sodium compounds; (2) Midland-type brines, from which bromine, iodine, and chlorides of calcium, magnesium, potassium and sodium are derived; (3) Searles Lake-type brines, yielding boron, bromine, lithium, magnesium, potassium, and sodium compounds; and (4) Silver Peak-type brines, produced mainly for lithium. Market Attributes Some of the important market traits common to industrial minerals used by the chemical industry are listed below. 1. They are international commodities, such as fluorspar and sulfur, which largely move to foreign consumers. 2. Grade, and freedom from deleterious elements are important factors affecting their usability in chemical processes. An example is salt (NaCl) used in electrolysis where ultrapure evaporated salt is required to meet rigid specifications. 3. Purified products take on the characteristics of specialty items and command a distinctly higher price than the basic commodity from which they are derived. 4. In practically all cases, chemical users require some sort of cleaning or beneficiation of the naturally-occurring mineral to bring it to specification, and individual specifications may vary from user to user for essentially the same use. 5. In some instances it is necessary to strike a balance between what the vendor can supply and what the buyer requires, with the result that specifications have to be eased to afford the needed materials in marginal cases. 6. Because they tend to be bulk commodities, low cost for handling and transportation are important and such costs may limit the area from which a chemical user can draw his supply. For example, fluorspar from China and Thailand normally goes to Japan, while South African fluorspar can go either to Japan or to the US. 7. Shipments are usually in bulk and frequently in multiple-car, full-trainload or full-shipload lots to reduce transport costs, which in turn may require large terminal investment facilities.

Jan 1, 1983

By A. Raman

The Nb-Co system was nuestigated in the range 10 to SO at. pct Co with X-rays. A pt phase with the W6Fe.r-type structure occurs in the system between 46 and 52 at, pct Co. Its unit-cell dimensions are nearly identical to those of the p Phases found in the Nb-Fe and Nb-Ni systems. Two Laves phases, one having the MgZnz-type structure and the other the MgCuz-type structure, already t-eported in the literature, are found to exist in the system. The ,l.IgZnz-type phase occurs between 62 and 64 at. pct Co. A MgNi2-type Laves phase, reported in the literature, is no! obtained. A binalry phase is found to exist belozv I000C around 82 at. pct Co. THE cobalt-rich side of the system Nb-Co has been repeatedly investigated by previous inestiators" and the following intermediate phases are known to occur: NbCo, which crystallizes in the MgCu2-type structure and Nbc03,' reported originally by Wall-bam, which has the MgNiz-type structre. Jordan and uwez' as well as lliott' were unable to find the MgNiz-type phase. Two phases, designated as x and y, were reported by Saito and eck.' The phase x was inferred to have a narrow composition range near 77 at. pct Co. No published work is known to the author which reports the investigations in the niobium-rich portions of the system. This paper presents the results of an investigation in the Nb-Co system between 10 and 80 at. pct Co. EXPERIMENTAL PROCEDURE Two or three grams of the alloys under investigation were prepared using niobium (99.9 pct +) and cobalt (98.8 pct + with 0.14 pct Fe and and 0.03 pct C) in a tungsten-electrode arc furnace under commercial argon atmosphere. They were then wrapped in molybdenum sheets and annealed for a period between 5 days and 1 week at 1300°C in high vacuum (10-" orr) or in evacuated quartz amules for 2 weeks at 1000°C. Powders of -325 mesh size were prepared for X-ray work by crushing and grinding the specimens. Subsequent reannealing of the powders was not undertaken since most of the alloys were brittle and broke easily. X-ray powder patterns of the as-cast and annealed samples were prepared in a Siemens cylindrical camera (57.3 mm radius) with Cr-K, radiation. A Siemens diffrac to meter was used to get the X-ray patterns of some new phases. Metal log raphic examination of the alloys supplemented the X-ray findings. RESULTS The results of the X-ray and microstructural analysis Of the alloys are in in Table I. The lattice parameters of the phases are listed in Table 11 for quick reference. A set of micro photographs in Fig. l(n) to (j) show the microstructures of some alloys. A probable equilibrium diagram is drawn in Fig. 2

Jan 1, 1967

By John E. Hockett

The need for basic information about the relationship between resistance to dejormatim (flow stress), temperature, strain, and strain rate, for the solution of metal-fovming problems, is pointed out. Some early attempts to satisfy the need are mentioned. A brief description of a machine called a Cam Plastome-ter is given, including the processing of results of testing in the machine. Next, a program of testing aluminum in compression over a wide range of constant true-strain rates (0.1 to > 200 sec-1) and a modevately broad range of temperatures (223° to 673°K) is described. The results of this program are presented in the form of true-stress us true-strain cuvves. The data in these curves are presented in the form of relationships between true stress and true-strain rate in sermilogarithmic and log-log form, as functions of temperatures—for several true strains. Finally, true stress, for a given true strain, is displayed as a function of log true-strain rate and absolute temperature, i.e., a surface. SINCE the publication of Hill's book1 on plasticity theory, increasingly rapid advances have been made in analytical solutions to forming problems. Methods in common use are the slab method, the uniform deformation energy method, the limit analysis method, the slipline field method, and the semiexperimental method called "visioplasticity". These approaches, and examples of their use, are covered in detail by Johnson and Melloor2 and by Thornsen, Yang, and Kobayashi.3 unfortunately, practically all of the above work has had to rely upon a number of basic assumptions, e.g., homogeneous deformation and Coulomb (sliding) friction; and virtually no dependence of the mechanical behavior of the deforming metal, upon temperature, strain, and strain rate, has been included. It is with this dependency that this paper is concerned. Loizou and sims4 looked at the above relationship for lead using both a constant compression-speed Cam Plastometer and a constant true-strain-rate Cam Plastometer designed by Orowan.5 Alder and Phillips8 investigated the relationships for aluminum, copper, and steel in the same constant true-strain-rate Plastometer. cook7 tested twelve steels at temperatures ranging from 1170° to 1473°K in the same Plastometer over a range of true-strain rates of 1.5 to 100 sec-'. The writer tested commercially pure aluminum at room temperature and depleted uranium at temperatures from 573" to 873°K at strain rates from 10-3 to 1.0 sec-1 in a Cam Plastometer designed and built at Los Alamos Scientific Laboratory.8 During the past few years the Cam Plastometer at Los Alamos has been used for a number of relatively minor experiments on brass, mild steel, duralumin, Armco iron, and depleted uranium. In this time the machine has been continually modified and improved. It was decided to utilize fully the wide range of strain rates now available with the machine by testing a material about which some information was already in the literature. Prior work on commercially pure aluminum6 appeared to deserve confirmation and expansion. So it was decided to explore the resistance to compression of this material over the currently available range of constant true-strain rates and a convenient range of temperatures. This paper is a report of that exploration. I) EQUIPMENT AND PROCEDURE The principal item of equipment is, of course, the Cam Plastometer, the working part of which is shown in Fig. 1. In this figure, an aluminum specimen may be seen between two tungsten carbide platens, in position for a room-temperature test. Above the upper carbide platen is a load cell. Output from the load cell is amplified and applied to a galvanometer in a recording oscillograph. Auxiliary equipment includes the oscillograph, the control console, a counter, and a time-mark generator. The counter is first used in adjusting the time base. Then it registers the count, of sixty pips per revolution generated by the rotating cam, in each second. These pips and the time base are also applied to galvanometers in the oscillograph. Thus, load, time, and cam position are recorded simultaneously. Heating of a specimen prior to compression is done

Jan 1, 1968

By Robert W. Hunt

Delays in the completion of the alterations to the plant at the works of Messrs. Oliver Bros. and Phillips, in Pittsburgh, coupled with the increased demand for metal made from regular Bessemer pig, placing the firm many hundreds of tons behind in their deliveries, prevented Mr. Henry W. Oliver, Jr., from redeeming his promise to place his works at my disposal for further tests of high-phosphorus irons, until May 5th. Upon that date, I assumed charge of the operations in his steel-plant. Mr. Oliver had purchased Neshannock pig as a basis for a supply of phosphorus. My information is to the effect that this iron is made from low-grade Lake Superior ores and mill-cinder, the latter "ore" being utilized to about 40 per cent. of the total mixture. At all events the pig had quite as much phosphorus, and in as varying quantities, as the most exacting could desire. My experiments of last fall had well satisfied me as to the effect of from 0.35 to 0.55 per cent. of phosphorus in the Clapp Griffiths metal. Hence at this time my first trials were directed to

Jan 1, 1886

By S. Skowronski

PURPOSE OF INVESTIGATION Since cuprous chloride melts at 418° C., boils at 954° C. to 1033° C.,1 and is known to be volatile at a much lower temperature, the presence of chlorine in any form in or on copper to be melted has always been looked upon by copper refiners as a possible source of-serious copper loss. Although this fact has been known for some time, the copper literature contains little or no information regarding it and the field seems .never to have been properly investigated from a metallurgical standpoint. According to Greenawalt,2 cupric chloride, CuCl2, when ignited gives cuprous chloride; therefore cuprous chloride is always formed when copper enters into reaction with chlorine at a high temperature. Cuprous chloride melts somewhat below a dull red heat, and does not volatilize in closed vessels, even if strongly heated, but if heated in the air it goes off as a white vapor. Hofman3 gives the melting point of cuprous chloride

Jan 2, 1919

John A. Church, New York City: It requires some courage to appear as a critic of a theory which is not only the fashion among American geologists but is usually presented by them in terms which imply that any other views are an exhibition of ignorance. Still, I am obliged to say that the theory of lateral secretion as it is stated in this and other writings of Mr. Emmons and other geologists has not added much to our real knowledge or clearness of view. In the earlier and less developed stages of the theory, when it was used as Sandberger used it, to show that certain veins were probably derived from the rocks in which they lie, or which are adjacent, it was valuable in pointing us to an immediate source of ore-deposition. When we are driven to assume the existence of undiscoverable rocks at an unknown but certainly a considerable distance and in an unknown direction from the vein, I do not see that we have improved upon the despised " unknown source in depth " with which our ignorance has been covered so long. The new theory may suffer from adolescence, and these points map be cleared up by further study, but I speak of it as it is. Differentiation in a magma, by which a metal is concentrated in one member of a series of outflows, may explain why certain ores have favored a given locality with their presence; but it is not a necessary precedent to ore-formation. Concentration in the source of supply cannot be a requirement, for the forces that have been able to take up four or five tons of gold from an extensive body of rock must be able to collect four or five thousand tons of lead, copper or nickel from a proportionately more extended body of rock. That is to say, concentration is no more essential for these metals than it is for gold. In fact, differentiation, as it is now explained, is not an advance upon old ideas, but a retreat from them. It was noticed long ago that violent eruptive phenomena, however long continued, died away in solfataras; and when a vein came to be looked upon as an extinct solfatara the inference was ready that veins are eruptive in the sense that the solfataric waters collected the metals from the unerupted residue of the magma and carried them to the veins. The early views carried differentiation further than the modern school.

Jan 1, 1894

By H. A. Guess

INTRODUCTION. HISTORY AND PRODUCTION STATEMENTS. SOUTHEAST Missouri is the oldest of the large producing districts of the United States. The first recorded production from disseminated ores was in 1869, although for many years prior to that time lead had been mined from shallow pockets, and steady growth in production has been shown ever since, the greatest increases being during the past five years. The production by years for each of the operating companies from 1869 to 1907, inclusive, is given in Table I. In Table II. is given the production by years from 1908 to 1912, inclusive, for the district as a whole, showing the tonnage of crude ore mined, yield in concentrates, average assay of concentrates; yield in metallic lead both per ton of crude ore and in total; also approximate value of the yearly production.

Jan 12, 1913

By J. H. Nelson

An outline survey of the economic outlook for the United States export trade in petroleum products resolves itself broadly into two general divisions; first, a consideration of our present position in this trade, and second, a discussion of the visible factors which promise to affect appreciable changes in the immediate future in that trade. The United States PetRoleum Exports of majoR Petroleum Products 1925, 1926 and 1927

Jan 1, 1928

By J. T. Raleigh, D. L. Flock

This study investigated the nature of formation plugging with bacteria and attempted to relate its characteristics to physical rock properties. Fifteen core samples of four specific formation types were defined and plugged using a commonly occurring, uniform sized dead bacteria, Bacillus subtilis. Two of the formation types were fairly uniform-grained sandstones and two were heterogeneous carbonates. The injection rate and concentration of solids in the brine were held constant during the test runs. The pore geometry factor G was a significant petro-physical rock characteristic for correlation with depth of plugging, but lacked importance as a parameter for rate of plugging. Although the G factor may not completely describe porous rock geometry for plugging predictions, for reservoirs with multi-pore systems, there is evidence that the pore geometry factor might form a basis for establishing injection water specification in more llornogeneous reservoirs with only primary porosity development. INTRODUCTION GENERAL PURPOSE Injecting water into oil-bearing formations to increase recovery is common practice in the petroleum industry. One of the most serious operational problems involved with water injection wells is the tendency of the porous rock immediately adjacent to the injection wellbore to plug partially. This results in increased injection pressures and/or a decrease in the rate of injection. This plugging in injection wells can result from a number of causes, including bacteria contained in the injected water.1 The purpose of this work was to investigate the nature of injection plugging with bacteria and to attempt to relate its characteristics to physical rock properties. Many variables exist in research of this type, so, to reduce them, injection rate and concentration of bacteria in brine were held constant. The bacteria used for plugging was a uniform-sized, dead bacteria, Bacillus subtilis, a micro-organism commonly found in water, air and soils. Four specific porous rock types were plugged—two consolidated sandstones and two heterogeneous carbonates. The experimental work involved two distinct phases. The first concerned determining the physical rock properties and the second was the experimental work of actually plugging the selected core samples. PORE GEOMETRY FACTOR Capillary pressure is necessary to displace a wetting fluid from a capillary opening with a nonwetting fluid. The factors which govern capillary pressure are the surface or interfacial tension of the fluids involved, the system wettability and the equivalent pore radius. Thus: P,= 2ucososrd..........(1) Thomeer used the idea that the location and shape of the capillary pressure curve reflect characteristics of the pore structure of any porous media sample.' He presented the mathematical description of capillary pressure curves and of indicated differences in pore geometry of samples. where G = pore geometry factor PC = capillary pressure Pi = displacement pressure (V,)p, = fractional bulk volume occupied by the displacing fluid at any capillary pressure (V,), = fractional bulk volume occupied by the displacing fluid at infinite pressure or total interconnected pore volumes. The shape of the curve is defined by the pore geometry factor G. The curve shape is related directly to the sorting and interconnection of the pores of the sample. The location of an infinite number of curves can be defined by the same asymptotes. However, these curves differ in shape, each curve being described by a specific value of G. Thus, the description of a curve is unique when, in addition to the position of its asymptotes, its shape is defined. These curves can be used graphically to determine the characteristic parameters of any arbitrarily located curve. Those parameters that can be approximated from any capillary pressure curve are: (1) total interconnected pore volume, represented by (V,),- ; (2) extrapolated displacement pressure, the abscissa axis; and (3) pore geometry factor, by the curve shape. PROPERTIES OF BRINE AND BACTERIA The fluid used throughout this study was an aqueous solution of sodium chloride, 25,000 ppm by weight. The addition of salt to fresh water was intended to eliminate clay swelling in the sandstone cores and to retard leaching in the limestone cores. The viscosity of the brine solution at 100F, the temp-

Jan 1, 1966

By Paul K. Krueger

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

Jan 1, 1977

By David R. Mitchell, Ernest M. Spokes

INFORMATION on magnetic properties of minerals other than magnetite is scanty and some- times erroneous. Often there is no information at all. W. R. Crane's table of tractive forces published in 1901 is still the best guide in the field, but Crane's data can be used as a guide only, since he ignored such important factors as impurities in the minerals, size, and packing effect. During the 1930's work by the U. S. Bureau of Mines added greatly to knowledge of the behavior of certain minerals in a magnetic field. The USBM bulletin gave for the first time complete magnetic characteristics for magnetite and fragmentary data for a few other minerals. The work reported here covers a study of the magnetic-susceptibility relationships of the wolf-ramite series of minerals and sphalerites as related to their chemical compositions. Theories are proposed to explain divergences found from commonly accepted beliefs.

Jan 3, 1958