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By Clyde Wyman

THERE has always been a question as to the extent to which oxidizable alloys might he recovered from charged scrap in the, acid electric furnace. While qualitative information was not lacking, the quantities that might be recovered and the conditions best suited for such recovery were not clearly defined. The present investigation was carried out to determine the efficiency of alloy recovery from residuals contained in the bath, especially in regard to the recovery of vanadium. A series of 24 heats was produced at the Burnside Steel Foundry Co., including medium manganese-molybdenum-vanadium, manganese-chromium, and grade B steels, in which vanadium recoveries from the residual vanadium were investigated. Recoveries of other alloys were also studied from the accumulated data. These heats were produced in a 5-ton acid-lined electric furnace. The analysis of metal and slag samples and the micrographs were prepared by the Research Laboratories of the Vanadium Corporation of America. In addition to the vanadium contained in the scrap charge, ferrovanadium was added to the charge and to the molten bath to bring the residuals up to the desired level. Vanadium pentoxide (V2O5) in one series of heats was added to the bath after meltdown, for the same reason. In addition to the general furnace practice, the slags of these various heats were treated with coke breeze, Ferrocarbo-S (silicon carbide), and aluminum dross to determine the effects of different reducing agents upon the alloy recoveries and upon the final product.

Jan 1, 1947

By Ralph C. Holmer

IN the field of mineral exploration, 1956 can be looked upon as the International Geochemical Year. This is not because of unusual developments in geochemical prospecting but rather because of the world-wide effort in geochemistry and the realization that geochemistry is now an established exploration method. Use of mining geophysics has continued to increase. Those extensively employing exploration techniques indicate that developments of the past few years have permitted better programming of methods, from reconnaissance to location of drill- holes. There is greater diversification of methods- reliance is not placed on results of one. However, it is realized that often it is more economical to drill an anomaly than to conduct additional expensive geophysical surveys

Jan 2, 1957

By George Frederick Kunz

The manifold inconveniences resulting from the absence of a uniform standard of mass for determining the weight of precious stones have long been obvious. This lack has been keenly felt in commercial transactions, and those who have devoted time and research to the study of historic diamonds and precious stones have had frequent occasion to deplore the absence of such a standard in the past. In a paper read in Chicago in 1893, before the International Congress of Weights and Measures, held in connection with the World's Columbian Exposition, the writer suggested dividing the carat into 100 parts, and constituting a standard international carat of 200 mg.; that is, 5 diamond carats or 20 pearl grains to a French gram, making 5,000 carats or 20,000 pearl grains to a ki1ogram. He also called attention to the fact that while this would depreciate the present diamoiid carat or pearl grain only about 2.5 per cent., it would abolish the troublesome discrepancies between the various carat-weights now in use, and could be easily explained and understood everywhere.' The subject of the various diamond carats, their incongruity, and the resulting confusion as to the correct weights of historic gems when definite records of them are searched for, has been fully treated by me in an extensive study of this subject in The Book of the Pearl2 To the earnest and unremitting efforts of C. E. Guillaume, Director of the Bureau Internationale des Poids et Mesures at Sévres, is largely due the eventual success of this eminently desirable reform, which he has constantly urged both by articles on the subject and by addresses delivered in Paris before the International Committee for Weights and Measures.3 The general adoption of a uniform standard for dealings in pre-

Jan 1, 1914

By L. L. McDaniel

During the past few years a nuinber of improvements in smelting and power equipment have been made at the Douglas smelter of the Phelps Dodge Corporation at Douglas, Ariz. In the summer of 1935 work was started on the first unit of a new reverberatory waste-heat boiler plant which ultimately was to furnish steam for a modern high-pressure power pIant. A second reverberatory waste-heat boiler unit

Jan 1, 1944

By DeVerle P. Harris

Risk for most mineral investments is greater than that of average business ventures, because the physical and economic characteristics of the mineral deposit are never known with certainty. Inasmuch as the merits of a potential mineral investment cannot be fully appraised without consideration of the impact to the investor of the possible unfavorable events associated with the adoption of the project, methods of risk analysis are important in project evaluation and investment selection. The conceptual framework for risk analysis and the means by which some of the recommended practices might be implemented are examined. In addition to the normal business risk due to market forces, the physical and economic characteristics of the mineral deposit are never known with certainty, for only partial or indirect information is available, such as data from drill cores or surface and underground workings. Consequently, risk for most mineral investments is greater than that of average business ventures. Inasmuch as the merits of a potential mineral investment cannot be fully appraised without consideration of the impact to the investor of the possible unfavorable events associated with adoption of the project, methods of risk analysis are important in project evaluation and investment selection. This paper examines the conceptual framework for risk analysis and means by which might be implemented some of the recommended procedures. Utility Theory A discourse on risk and its impact upon investment selection quite often leads the reader into the concept of utility theory, for utility theory is a device constructed by economists to measure the satisfaction an individuai receives from a good; in the case of investment analysis, that good is the outcome of an investment. It briefly is reviewed here to describe the reaction of the individual to risk and as a stepping stone to other techniques more suited to risk analysis at the level of the firm. Utility theory proposes that an investor possess a utility map (curve), such as indicated in Fig. 1, which indicates the value in utiles of potential monetary rewards to an individual with some specific endowment of resources. Points on this map are obtained from the following relationship:

Jan 1, 1971

Jan 1, 1942

By C. D. Rubert, W. J. Parton

A flotation plant was placed in operation in 1945 at the Tamaqua colliery of the Lehigh Navigation Coal Co. Inc., to recover fine anthracite which is discharged from the cleaning plant with the washery water.‡ In addition to the recovery plant, facilities were provided for the complete clarification of the washery water, recirculation of this clarified water for breaker use, and disposal of the refuse solids in a waste impounding dam. Fig I shows a view of the settling tanks and the flotation plant. Flow Diagram The flow diagram for the complete recovery project is given in Fig 2. All the waste water from the cleaning plant is collected in a sump A outside the breaker structure, from which a 7000 gpm pump B delivers it through a 16 in. line to a 75-ft diam hydroseparator C. The hydroseparator, acting as a classifier, is set to give a separation at approximately 200-mesh. The minus 200-mesh overflow is discharged by gravity into the 180-ft thickener D for final settling of the solids. The classifier underflow sludge is pumped to the flotation plant by a 6-in. quadruplex diaphragm pump E. A 10-ft diam hydroseparator F is used to make a second classification on the sludge solids at approximately 28-mesh. The underflow from this classifier containing the coarse particles is elevated by a 6-in. diaphragm pump G and is discharged on two 4- by 6-ft vibrating screens II. These screens are dressed with approximately 28-mesh cloth. Screen oversize product flows directly to the centrifuge that dewaters the cleaned froth. The screen underflow and the overflow from the 10-ft classifier flow to the flotation circuit. The flotation feed is conditioned in a 12 by 12-ft agitator tank J at a pulp density of I:2.33 (30 pct solids). Reagents are fed to the circuit by reagent feeder I. The conditioned pulp is then diluted to a pulp density of approximately I: 5 (18 pct solids) and is fed to two banks of four 100-cu ft froth flotation cells K for primary coal recovery and cleaning. Additional reagents from reagent distributor L are added to the feed weir-box of Nos. 2, 3, and 4 cells of each bank of flotation machines. Clean coal removed from these cells flows directly to the clean-coal sump. Dilute tailings from the primary cells is re-thickened in a 30-ft diam thickener M and is then retreated in a scavenger circuit for final recovery of coal. The scavenger circuit consists of a 6- by 6-ft agitator tank N and two banks of four 24-cu ft froth flotation cells 0. Coal froth from these cells flows to the dewatering equipment and the tailings flows to a vertical refuse pump which delivers it to the 180-ft diam waste thickener D. Dewatering of the coal products is accomplished in a 54- by 72-in Bird centrifugal filter P. The cake product is dropped onto a conveyor and is loaded

Jan 1, 1949

By Emmanuel P. Papadakis

Ultrasonic velocity measurements have been made to study the preferred orientation in cube-textured copper. Methods applicable to thin specimens were employed since the specimens were necessarily of sheet material. The measured velocities in various directions in the sheet differed from the corresponding values in single-crystal copper by 1 to 6 pet. The distribution of the deviations indicated that the align-ment of the (001) planes with the rolling plane was better than the alignment of the [100]and [010] directions with the rolling and transverse directions. Ultrasonic pole figures (velocity us orientation) are shown to be useful in the study of preferred orientation. THIS paper describes one set of experiments in a continuing study of preferred orientation in worked metals. This study has been undertaken to investigate the fundamental properties of metals when used as propagation media for ultrasonic waves. Many such materials are of current or potential use in ultrasonic delay lines. Fundamental studies on ultrasonic propagation parameters such as velocity, attenuation, and diffraction (beam spreading) are of importance in the design of delay lines, in the development of nondestructive testing methods, and in the study of materials themselves. Preferred orientation in worked poly-crystalline metals influences all three above-mentioned parameters, and hence is of particular importance. When polycrystalline metals are subjected to mechanical working, they develop textures dependent upon their crystal structure and the symmetry of the working operation.' The texture consists in the alignment of the crystallographic axes of the grains in preferred directions with respect to the symmetry axes of the working operation. Since the grains are elastically anisotropic, the elastic moduli of worked metals are anisotropic. Hence the velocities of elastic waves in worked metals depend on the directions of propagation and polarization. The worked metal may be thought of as taking on the elastic symmetry of a single crystal: so it possesses the same number of independent elastic moduli as the crystal class it simulates. In general, a worked metal does not adopt the crystalline symmetry of its own grains. For instance, most rolled sheet becomes effectively orthorhombic while all bar stock and wire develop hexagonal symmetry. However, certain metals with cubic crystal structure develop a cube texture upon rolling and annealing.= Nearly perfect alignment of [100]-type directions with the rolling direction, transverse direction, and rolling-plane norma1 can be achieved in certain fcc metals and alloys. These cube-textured rolled metals provide an excellent opportunity to test preferred orientation by means of elastic waves, since a worked metal with 100 pct cube texture would have elastic moduli identical to the moduli of its constituent metal. It is the purpose of this paper to present the results of an investigation upon cube-textured copper. Ultrasonic waves were used. The methods of measurement and the experimental results on the effective moduli will be given. The ultrasonic measurements will be shown to complement X-ray pole figures for the determination of preferred orientation in worked metals. EXPERIMENT To study cube - textured material, it was necessary to use thin-sheet material since a severe reduction in gage (95 to 99 pct) is necessary to produce cube texture. Special ultrasonic methods were needed to investigate the thin material at megacycle frequencies. A) Materials. The cube-textured material tested was a copper alloy containing 1 pct Zn. Specimens already measured for Young's modulus4 by Alers were kindly supplied by him. The specimens were slabs 3.00 by 0.25 in. cut from sheet 0.047 in. thick. The orientations of the long axes of the specimens with respect to the rolling direction were taken in 15-deg steps from 0 to 90 deg. B) Measurements. Two distinct experiments were performed to measure the phase velocity in these specimens. One measured the shear wave velocity for propagation in the 0.25-in. direction and polarization in the 3.00-in. direction. The other measured the velocity of both shear and longitudinal waves propagating in the thickness direction in the sheet. 1) Plate-Mode Measurements. The velocity of the zeroth-order shear mode5 was measured in the 0.25-in. direction in each strip. The specimens were ground thinner over half their length to assure that the first-order shear mode would be cut off below 6 Mc per sec, leaving the zeroth-order nondispersive shear mode as the only propagating mode. Piezoelectric ceramic transducers of 5 Mc per sec resonant frequency poled in their long direction were solder-bonded to the edges of the thin part of the slabs as in Fig. 1 after these edges had been made flat and parallel by fine grinding. These transducers produced waves polarized in the 3.00-in. direction and propa-

Jan 1, 1967

By G. Donald Emigh

Nothing is more important to life-plant and animal-than phosphate. Its compounds are essential to the energy functions of all living systems and for the formation of bones and teeth. Animals get their phosphate from eating plants and other animals, or domestically from feed supplements. Plants get their phosphates from the soil. Man's most important use of phosphate is for fertilizer; approximately 95% of the world's phosphate rock production is consumed by fertilizers. Most of the balance is processed in electric furnaces into elemental phosphorus, the important raw material for making industrial phosphates. Recovery of uranium from phosphates has been possible but not widely used. However, recent significant developments have generated interest in such recovery in the US and elsewhere. Phosphate occurs in all igneous and sedimentary rocks, and in all fresh and salt water. However, economical recovery is limited to deposits where natural concentration of the phosphate mineral has occurred. Occasionally natural concentration is great enough that the material can be used as mined; generally, however, the ore is low grade_ and must be concentrated. Phosphate rock is produced in 31 countries. Fig. 1 shows the location of major phosphate rock producers as well as some of the known phosphate deposits not yet in production. In the last decade the world phosphate industry has experienced steady growth. World production rose from 98 Mt of phosphate rock in 1973 to 140 Mt in 1982. Fig. 2 shows the growth curve of rock production and graphically illustrates the almost straight-line rise since 1945 in both US and world production. Table 1 gives the breakdown, by countries, of world rock production, 1974 through 1979. Table 2 shows US rock production by producing areas. Definitions of Terms Used in the Phosphate Industry Phosphate Rock: Commonly called rock in sedimentary deposits and apatite in igneous deposits. Those expressions generally include any mined, or mined and beneficiated, fluorine-containing calcium phosphate used as the raw material for the next stage of manufacturing. The average phosphate content in rocks is 0.1 to 0.2% P2O5, as documented by McKelvey (1973). About 200 minerals contain more than 1 % P2O5. However, the important mineral in igneous rocks is fluorapatite, [Ca5 (PO4),3 F], containing about 42% P205 and 3.8% F2; in sedimentary rocks the important mineral is francolite, a carbonate fluorapatite containing up to 2% molecular CO2. Both are in the apatite family of minerals. Most phosphate rock, whether beneficiated or not, is a fine-grained material. The expression phosphate rock has no relation to its phosphate content. For example, phosphate rock from Idaho used in the production of phosphorus may contain about 24% P205, whereas rock from Morocco may contain 36.6% P2O5. Phosphorite: A deposit of phosphate directly or indirectly of sedimentary origin, which is of economic interest. Grade of Phosphate Rock: The calcium phosphate content of phosphate rock is expressed in different world areas by one of the following terms: BPL (bone phosphate of lime) TPL (triphosphate of lime) P2O5 (phosphorus pentoxide) P (phosphorus-not commonly used) An illustration of relationship is: 80% BPL = 80% TPL = 36.6% P5O2 = 16% P

Jan 1, 1983

By W. A. Tiller

The conventional techniques1 for determining the liquidus and solidus surfaces of an alloy system containing more than two components are extremely tedious to use and do not provide a complete picture of the equilibrium relations between solid and liquid alloys. These techniques are unable to yield "tie-line" information concerning solid and liquid phase equilibrium, a very important parameter in the solidification description of the liquid alloy and a very necessary parameter in the preparation of "zone-levelled" alloy crystals. The tie-line in a polycomponent system is analogous to the partition coefficient, k, in a binary system, it gives the composition of the solid, Cs, in equilibrium with a liquid of composition CL. That is, CS = kCL, where CL = [CO, c1,...Cn] denotes the concentrations of the n + 1 constituents, and k = [ko, kb ,...kon] denotes the gross partition coefficient for the elements between the two phases; thus, k is the tie-line in this system. To provide complete information concerning the two-phase equilibrium in a polycomponent system it is necessary to know both the liquidus surface and the gross partition coefficient. From these two the solidus surface is obtainable. The conventional techniques are unable to provide this information in other than a binary system so we must look elsewhere. In recent years considerable insight has been gained into the correct description of the liquid-solid transformation, 2,3 and controlled solidification experiments may now be designed to both facilitate and enhance equilibrium diagram studies. In the present paper consideration is given to two methods for obtaining the liquidus surface and the tie-lines in polycomponent systems. The methods to be described below deal with the solidification of an n + 1 constituent liquid alloy of initial composition [co, Co ,...Con], where the superscripts refer to the elements present and the Oth element is considered as the solvent in which the n solutes are dissolved. The general assumptions made in the treatment are the following: (i) the solid and the liquid at their interface are in equilibrium during the growth of the solid phase, (ii) there is no diffusion in the solid phase, and (iii) the liquid phase is completely mixed and is therefore homogeneous in concentration. METHOD I In this section a general experimental method will be described which, in principle, is capable of giving an exact description of the liquidus surface and tie-lines. Consider the unidirectional solidification of the liquid alloy specimens L cm in length (freezing either horizontally or vertically). Allow the sample to be frozen very slowly from one end, as indicated in Fig. 1, with complete mixing in the liquid, and then analyze the solid bar to determine its chemical constitution as a function of position, x, along the bar. Let Fig. 2 represent a possible distribution of the ith constituent along the bar. At the point x' the concentration of the ith constituent is C1/5(x'), and the average concentration of the rest of the bar between x' and L is given by C:(X' - L) where [ A(x) c1s(x)dx c1/s(x'-L) = f A(x) dx x * and A(X) is the cross-sectional area at x. In a similar manner. all the Cf(x' - L) may be determined. Thus, the gross artition coefficient k for liquid of composition [Cs(x - L),...Cs(X' - L)] is given by -ko= CUs')/Cos(x' - L)" k0 = csn{x')/cs(x'- L) During the freezing of a charge of length L, the liquid composition may vary over a wide segment of the phase diagram and the gross partition coefficient over this segment of the phase diagram may be determined from one, bar. Fig. 3 illustrates the magnitude of Cs(g)/C,' as a function of the fraction g of the bar which has Solidified.2 We can see that the concentration in the bar will vary over a range of about 15 wt pct for C,' = 10 wt pct and k0 = 0.5. It appears that 4 or 5 specimens would be adequate to study a simple binary eutectic phase diagram.

Jan 1, 1960

By L. Weyher, H. L. Lovell

This discussion is restricted to a very specific application of the cyclone - its use as a hydro-cyclone in the cleaning of fine coal. It is hoped that the development of the present data will assist in the further elucidation of existing qualitative models, and also in an enhanced application of the hydrocyclone and provide a base for further research. Discussed are the mechanisms of gravity separation in hydro-cyclones, test procedures, experimental observations, and industrial applications from these studies. Within the general area of unit operations, a considerable effort has been expended in theoretical and empirical research associated with cyclone operations. The motivation involves the industrial requirement for devices and techniques to manipulate small particles at low operating costs, a situation required in coal preparation. There are good reasons why the cyclone helps to satisfy this demand, because it combines operational simplicity (no moving parts) with versatility and high throughput capacity per unit area. The cyclone is one of the most widely applied tools in the process technologies. There are areas for potential cyclone application which have been only meagerly explored or not considered at all. This discussion is restricted to a very specific application of the cyclone - its use as a hydrocyclone in the cleaning of fine coal. It represents an initial presentation of a more comprehensive report. Coal preparation can appropriately claim the hydrocyclone since most of its predominant industrial uses have originated in this area and have spread into other applications, including the broad field of ore dressing, the petroleum industry, chemical processing, nuclear engineering and food technology. There is one operational principle common in all cyclones: A fluid is tangentially introduced into a cylindrical or conical container under pressure. A predominantly irrotational flow field1 is established within the cyclone (Fig. 1). The uniqueness of this flow is indicated by the variation in tangential velocity across the cyclone radius, which reaches a maximum a short distance from the center and decays toward the cyclone wall. In contrast, the tangential velocity in a centrifuge increases uniformly toward the wall. Usually two products are discharged from the cyclone. They differ in that one discharge consists predominantly of that portion of the feed fluid which moves along the wall axially away from the feed inlet, while the other consists predominantly of fluid spiralling along the central regions of the cyclone, in an axial direction opposite to that of the wall current. Fig. 2 indicates these discharge points schematically. The latter product may be termed the vortex-product, since it is discharged with the central vortex-current. In the case of conical cyclones, the former product may be referred to as the apex-product. Although the names "over- and underflow" are widely used, many cyclones are operated from extreme angular positions thus the proposed terms are less ambiguous. The cyclone feed fluid can be laden with solid particles or nonmiscible fluid drops. Such a feed component is discharged from the cyclone, after some residence time, into the one or the other product. Yet, the orifice through which a particle will leave the cyclone is dependent upon a number of factors. These factors, in a statistical sense, determine the path of the particle within the cyclone. Thus, different separation phenomena are possible and different process results attainable by the controllable variation of the particle path. It is then, to attain a fuller understanding of this particle path, to which this study is ultimately directed. It is anticipated that the detailed study of the data being developed will allow further elucidation of existing qualitative models. However, the development of a quantitative description of cyclone operation in terms of a mechanism is not currently feasible. The flow conditions in a cyclone are not fully understood even for a pure fluid, without the added complexity of the inclusion of multiple size-density particles. It is hoped that the development of the present data will also assist in an enhanced application of the hydro-cyclone and provide a base for further research. Some practical applications drawn from the data are suggested. Cyclone operations have been classified according

Jan 1, 1967

By Herbert Clark Hoover, Lou Henry Hoover

MANY persons hold the opinion that the metal industries are fortuitous and that the occupation is one of sordid toil, and altogether a kind of business requiring not so much skill as labour. But as for myself, when I reflect carefully upon its special points one by one, it appears to be far otherwise. For a miner must have the greatest skill in his work, that he may know first of all what mountain or hill, what valley or plain, can be prospected most profitably, or what he should leave alone ; moreover, he must understand the veins, stringers1 and seams in the rocks2. Then he must be thoroughly familiar with the many and varied species of earths, juices3, gems, stones, marbles, rocks, metals, and compounds4. He must also have a

Jan 1, 1950

When Ponce de León landed in Florida in 1573 he was told of an Indian chief that possessed much gold. In 1576 Diego Meruelo obtained some of it from the Indians, and in 1579 Álvarez de Pineda reported that the natives wore ornaments of gold, which they obtained from the rivers. These statements all refer to the southern Appalachian region. The name is recorded in 1527; when Pamphilo Narváez landed at Tampa he heard that there was much gold to be obtained in a region named Apalache. * In 1564 René Laudonnière describes the methods used by the natives to win gold in the Apalatcy mountains.† However, no serious mining operations were undertaken until long afterward; the mining of gold in the Southern States may be said to have had its beginning when a nugget was found at the Reed mine, in North Carolina, in 1799. This nugget, which was of "the size of a small smoothing iron", was kept for several years before the finder learned what it was, but later more lumps, one weighing 28 pounds, were found in the same locality, and eager digging ensued. ‡ Thomas Jefferson, in his `Notes on Virginia', mentions the finding of a quartz specimen, not a nugget as is generally stated, that contained 17 pennyweights of gold; this was found on the Rappahannock river in 1782. §

Jan 1, 1932

Jan 1, 1942

By Michael J. Messel

The critical shortage of asbestos fiber in the world today brings to the foreground the question of locating and developing new deposits. The object of this paper is to discuss some of the more important factors which should be considered in the examination and valuation of a new asbestos enterprise. Some of the more important uses of asbestos fiber are for textiles, heat insulators, building materials, filters and a series of other uses. The properties of this mineral, such as fibrous structure, color, strength, silkiness and flexibility, coupled with resistance to fire, certain chemical action and decay make its application unique for certain industrial uses which consume over 500,000 tons annually. These same unique properties which make this mineral so valuable also make a deposit one of the most difficult to appraise accurately, because of the many undeterminable and varying factors which must be considered before a deposit can properly be termed commercial. The majority of the asbestos fiber today, having the above mentioned properties, is sold by grades which are based on fiber length. Present day fiber prices vary over a wide range from $800 to $225 for crude fibers and $300 to $20.00 per ton for milled grades. For valuation purposes a careful study should be made of existing fiber prices and markets. Examination of Deposits In carrying out prospecting and examination of a deposit, considerable caution is required to get the necessary information in the form that will have the most value for the final determination. There are two main classes of asbestos fibers, chrysotile and the amphiboles, the chrysotile being, by far, the most important both in abundance and uses. This paper will stress mainly chrysotile deposits, however, the amphiboles have many important uses, especially amosite and crocidalite. Their valuation presents special problems as other factors may be involved, especially as they are not graded according to any well defined and adopted standard but usually according to the use for which they are being supplied. Most chrysotile deposits occur in two main types of rock, (I) mainly in basic igneous, such as dunite and peridotite, (2) to a lesser extent in sedimentary rocks, such as dolomite and limestone. All of these require a certain degree of metamorphism to be favorable to asbestos formation. Approximately 90 pct of the asbestos deposits are derived from serpentinization of dunite or peridotite, whereby the magnesium-silicate olivine was altered to hydrous magnesium-silicate serpentine. Under certain favorable geological conditions, this serpentine takes a fibrous form having a definite crystal structure, probably due to molecular rearrangement, and is known as chrysotile. The fiber veins are usually ir-

Jan 1, 1948

By Frank H. Reed, P. W. Henline, Harold W. Jackman

A sumMary of the consumption of coal in 1945 shows that the coke industry ac-counted for 17 pct of the total coal used. No substitute for coke and the blast furnace in the reduction of iron ore has gained sufficient prominence so far to be given serious consideration. However, while the same slot-type ovens are being built and used now as were in use a few years ago, the problem of obtaining suitable coking coals, both high- and low-volatile, has forced many operators to revamp coal-blending facilities. Until the beginning of World War 11, high-temperature ooke plants were able to secure the required high-volatile and low-volatile coals from two or three seams and from three or four mines. Thus, many of our coke oven plants were able to operate with storage bins for two coals only. The vari-pnce in raw materials was not great, and uniformity of blend was a relatively simple problem. Since the beginning of World War 11, many and important changes have taken place. Demand for all coals increased greatly. Production, though kept as near maximum capacity as possible, could not meet the demands for coal generally, and particularly for the various kinds of coal which have proved to be satisfactory for specialized uses; coals were allocated as nearly as possible in the order of greatest need; storage piling was reduced to the minimum necessary to keep plants in operation; uniformity of quality could not be maintained, and with this last, uniformity of composition of blends for coking could not be maintained. Whereas before the war producers of metallurgical coke could fill their needs from three or four mines, by the end of the war it was not unusual to find shipments to a single coke oven plant coming from as many as 30 different mines, in a single month. Since many of the mines producing both high- and low-volatile coal for high-grade metallurgical coke are rapidly nearing de-pletion, the problem of seeking new sources and of blending a number of coals in each plant for the production of high-temperature coke is facing practically every producer in the United States at the present time, and is one which will probably continue for many years to come. Midwestern byproduct coke ovens in the Chicago and St. Louis areas use annually from 12 to 15 million tons of bituminous coals which are transported 500 to 700 miles from the Appalachian coal fields of Pennsylvania, West Virginia, and eastern Kentucky. Approximately two-thirds of this coal is high-volatile bituminous. The critical transportation problem confronting the nation in 1943, and the growing scarcity of the best Appalachian coking coals, prompted the Illinois Geological Survey to propose a research program in which would be studied the coking properties of blends of low-sulphur, high-volatile Illinois coal with the high- and low-volatile coals from the eastern fields. Such blends containing Illinois coal, if substituted for the all-eastern blends normally coked,

Jan 1, 1949

By Michael J. Messel

The critical shortage of asbestos fiber in the world today brings to the foreground the question of locating and developing new deposits. The object of this paper is to discuss some of the more important factors which should be considered in the examination and valuation of a new asbestos enterprise. Some of the more important uses of asbestos fiber are for textiles, heat insulators, building materials, filters and a series of other uses. The properties of this mineral, such as fibrous structure, color, strength, silkiness and flexibility, coupled with resistance to fire, certain chemical action and decay make its application unique for certain industrial uses which consume over 500,000 tons annually. These same unique properties which make this mineral so valuable also make a deposit one of the most difficult to appraise accurately, because of the many undeterminable and varying factors which must be considered before a deposit can properly be termed commercial. The majority of the asbestos fiber today, having the above mentioned properties, is sold by grades which are based on fiber length. Present day fiber prices vary over a wide range from $800 to $225 for crude fibers and $300 to $20.00 per ton for milled grades. For valuation purposes a careful study should be made of existing fiber prices and markets. Examination of Deposits In carrying out prospecting and examination of a deposit, considerable caution is required to get the necessary information in the form that will have the most value for the final determination. There are two main classes of asbestos fibers, chrysotile and the amphiboles, the chrysotile being, by far, the most important both in abundance and uses. This paper will stress mainly chrysotile deposits, however, the amphiboles have many important uses, especially amosite and crocidalite. Their valuation presents special problems as other factors may be involved, especially as they are not graded according to any well defined and adopted standard but usually according to the use for which they are being supplied. Most chrysotile deposits occur in two main types of rock, (I) mainly in basic igneous, such as dunite and peridotite, (2) to a lesser extent in sedimentary rocks, such as dolomite and limestone. All of these require a certain degree of metamorphism to be favorable to asbestos formation. Approximately 90 pct of the asbestos deposits are derived from serpentinization of dunite or peridotite, whereby the magnesium-silicate olivine was altered to hydrous magnesium-silicate serpentine. Under certain favorable geological conditions, this serpentine takes a fibrous form having a definite crystal structure, probably due to molecular rearrangement, and is known as chrysotile. The fiber veins are usually ir-

Jan 1, 1948

By Benjamin F. Tillson

The hammer drill rightly receives the credit for having made the one-man drill possible, and so many economies seem possible through the proper application of different types of hammer drills to various mining, quarrying, and excavating operations, that an indication of the 'economies effected by the New Jersey Zinc Co. at its Franklin mines may be of pertinent interest. When this company commenced its trials of hammer drills in 1907, these tools had not been developed to one-fourth the capacity and refinement which they have at present. At that time it was frequently stated that such a small tool, drilling holes of less diameter than the reciprocating rock drill, could not drill enough holes in a shift to permit the placing of sufficient explosive to break a tonnage of ore comparable with that produced by the "rock drills;" that the placing of small holes inclined upward, at angles steeper than 40' above the horizontal, could not be expected to produce results equal to the large flat, wet or dry, holes in the breasted back of an overhand stope, and would only shatter the ground so as to make the back unsafe. In spite of these adverse opinions, the hammer drills first showed their superiority over both heavy and light reciprocating drills in raising and in stoping, and then in drifting and quarry work. As a result, all of the reciprocating drills at the Franklin mines were scrapped three years ago, all of the mining work being accomplished with increased efficiency, as shown in detail in this article. With the advent of the hammer drill in this property, it was considered advisable to make comparative tests of all the tools accessible, and it has since been the policy to investigate the merits of any advance of the drilling art in order to get the maximum amount of work from the tools. The necessity of devising some means of standardizing drill tests, and of measuring the consumption of compressed air as well as the drilling speed, was early realized. The common test was to fill a measured air receiver with compressed air at a certain gauge pressure, run the drill until the pressure had dropped to too low a figure, then compute from the time, drop in pressure, and

Jan 1, 1915

By C. C. McDermond

In reviewing petroleum development in Venezuela during the year 1936, it is well to bear in mind certain factors that affected progress, although not directly connected with the oil industry itself. At the start of the year, when the present Federal Administration took over the reins of government, reaction against the former regime resulted in some popular uprisings. Although these were entirely political in character, they were not without their effect on the oil industry itself. Such popular agitation really ended with a short general strike in Caracas, Maracaibo and other cities during June, these strikes being based on demands for certain changes in government policies. The strikes were duly investigated and their motives taken into consideration by the executive power or by Congress, and during the year many of the civil, political and administrative laws have been revised. In June and December, however, it was necessary to suspend activities in drilling and production work, particularly in the Lake Maracaibo Basin area. In June a strike caused a five-day shutdown in the main producing fields and on Dec. 14 labor difficulties resulted in a shutdown that continued to the end of the year, which necessitated suspension of all drilling and production in the Lake Basin area and curtailment of shipments to deep-water terminals. Actually, the strike lasted for a period of 42 days, until Federal intervention brought the dispute to a close with minor wage increases to workers hut with no loss of initiative or independence on the part of the oil companies. Operations in eastern Venezuela were not affected by the labor disturbances, production and exports having been reduced in December only in the Lake Basin fields. Well Completions On Jan. 1, 1937, a total of 3384 wells had been completed throughout Venezuelan fields, as compared with 3094 on Jan. 1,1936. Of these wells, 2005 were producers. The 290 completions effected during 1936 were by the following operating companies: Lago Petroleum Corporation, 123 completions; Dutch Shell group, 104; Standard Oil Company of Venezuela, 46; Mene Grande Oil Co., 15; British Controlled Oilfields, Ltd., 2.

Jan 1, 1937

By D. D. Dunkin

Sandstone has been prepared for glassmaking purposes, and marketed from the White River Valley in Arkansas at Guion, Izard County, since about 1910—soon after the completion of the White River Branch of the Missouri Pacific R. R. Co. Until 1921, operations were somewhat spasmodic and ended in many failures. In that year a plant was built by the Silica Products Co., Inc., and since that time the operation has been continuous and steady. The land is held under leases, covering about 30 square miles of the best sandstone adjacent to the railroad. Most of the product is shipped to glassmakers. Geology The St. Peter sandstone is rather widely distributed in north central Arkansas and is exposed most prominently in outcrops along the slopes of the White River Valley and its tributarirs that form the division between the Boston Mountains to the south and the Salem Plateau of the Ozarks to the north. It is of Ordovician age and is generally underlaid by Cotter dolomite and capped by Plattin limestone, except in the vicinity of Bellefonte and Everton. At those places, it is a massive cross-bedded, laminated, saccharoidal sandstone; underlying it is the Everton limestone and overlying it, the Joachim magnesium limestone The sandstone at Everton contains numerous phosphatic pebbles and inclusions of sandy limestone. The irregularity of cross-section, the evidence of sorting action and the phosphatic pebbles appear to be indications of secondary deposition The St. Peter sandstone occurs as a massive formation in the picturesque bluffs along the White River Valley from near the eastern escarprnent of the uplift northwestmard into the Ozarks. The exposure shows a series of gentle anticlinal and synclinal folds. The greatest thickness is at the southeastern end, where it is over 100 ft. in many places. It thins out to the north and west and then to isolated and scattered deposits which cap the ridges and mountains of the Ozarks.

Jan 1, 1928