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By J. L. Bruce, G. W. Nicolson

ThE country rock of the Mavrovouni mine of the Cyprus Mines Corp. is hydro-thern~ally altered, disintegrated pillow lava, with very little tensile strength ("short" ground). In places, especially when wet, it is heavy ground, though not extremely heavy except where movement has been caused by underlying or nearby stoping operations. Damage by caving from roof or sides of galleries is not sudden but progressively faster when the size of the cave increases as a result of the fall of small pieces. CeMent and Concrete Linings During early operations, galleries in the country rock were supported by customary mine-timbering methods. Available timber, howcver, was of poor quality and of relatively high price, and replacements were frequent and expensive. Furthermore, the massive sulphide ore bodies required large volumes of fresh air for ventilation and cooling, and it was therefore desirable to provide smooth-lined galleries with low resistance for the introduction of air to the ore bodies. It was also desirable to eliminate hazards of fire in shafts and underground workings insofar as this would be practical. Cement and concrete were relatively cheap, and plans for using these in support of shafts, underground galleries, raises, and chutes, were developed steadily. Circular shafts with diameters ranging from 10 to 15 ft were adopted for all permanent shafts and airways. In places these were lined with concrete poured behind sectional pressed-steel forms especially constructed for this purpose. In other places, they were lined with precast-concrete blocks. It was found that such precast concrete of good quality could be produced on mass production scale and delivered at the mine from most favorable point of manufacture, at a cost of about 25 cents per cubic foot of concrete. This refers to prewar costs. As the use of concrete blocks in circular lined galleries was developed, it was found that there were very great advantages in the reduction of air resistance as compared with customary timber supports. After best methods had been developed, it was found that breakage and replacements were extraordinarily low, averaging only about 11\2 pct per year during a period of about 15 years. Furthermore, it has been possible to reclaim for re-use a very large percentage of the concrete blocks from abandoned galleries. During the history of the operations precast-concrete blocks have been used for lining shafts, raises, ore chutes, galleries, and shaft stations, ranging from 3 to 16 ft id. The thickness of lining has varied from 5 to 10 in.; with 12 in. thickness in a few cases. Junctions of two galleries at angles ranging from about 30 to 60° are usually made of poured concrete behind sectional forms, or of a combination of poured concretc and precast blocks. In nearly all cases it has been found advisable to make the point of the wedge at the junction, of

Jan 1, 1949

By J. L. Lytton, J. E. Dorn, L. A. Shepard

Single aluminum crystals were subjected to creep in simple shear on the (111) planes in the slip direction. The activation energies for creep were calculated from the effect of small abrupt changes in temperature on the creep rate just before and immediately following the temperature change. The results definitely establish the fact that creep of single aluminum crystals occurs by-three unique processes, characterized by thethree distinct and isolatable activation energies: The 35,-500-cal-per-mole activation energy obtained at the highest temperatures was ascribed to a dislocativationtion climb process; the 28,000-cal-per-mole activation-energy process, occurring over the intermediate-temperature range was attributed to a cross-slip mechanism; and it was suggested thot the 3400-cal-per-mole process observed below 400°K may be the Peierls energy. THE most pertinent question regarding the phenomenon of creep in crystalline materials is concerned with the identity of the crystallographic mechanisms of deformation that control the creep rate. For many years slight progress was made in uncovering the basic mechanisms for creep. Over the past 10 years, however, two parallel lines of investigations have contributed to a more definitive understanding of the processes involved in creep. The extensive development and maturing of dislocation theories for deformation of crystalline materials' proved to be of paramount importance for this progress. And second in importance was the replacement of the former prosaic methods of creep testing by new techniques'." which were especially

Jan 1, 1959

By T. M. Kegley, J. H. Frye, D. L. McElroy, M. L. Picklesimer, E. E. Stansbury

Measurements of rate of growth, thermodymmic quantities, and partitioning of Mn are reported for high-purity eutectoid Fe-C and Fe-C-Mn steels for the auistenite-pearlite reaction. Evaluztion of the cotnstants of a derived-rate equation with these data indicate that Mn additions cause the decrease observed by increasivg the activation energy and apparent activation entropy or the movenment of complexes at the interface. A diffusion-controlled mechanism is not required. Appreciable partitioning of Mn to cementite occurs entirely behind the austenite-pearlite interface for more than 30°C of subcooling. ThE growth of pearlite from austenite has been extensively studied over a period of years. but the rate-controlling step in the process is not known nor is the mechanisrn of the effect of alloying elements understood. A comprehensive review of the subject has been given by Mehl and Hagel. The present study has been concerned with further considerations of the effects of alloying elements on the rate of growth of pearlite. Analytical relatioriships for the rate of growth of pearlite have been considered by Zener.2 Turnbull,3 Machlin,4 Cahn.5 Frye,6 and Frye et a1.7 The derived expressions in each case involve the free energy of the transformation. the interlamellar spacing. and some rate term of the nature of the diffusion coefficient. mobility or frequency of occurrence of some rate-determining step. The treatments. of course. differ in detail. Further consideration is given in the present paper to the equation of Frye, Stansbury. and McElroy which was derived from modified absolute rate theory without in any way specifying the mechanism of the reaction. This equation is r=c ? T ? F exp -?E*/RT [1] where r = rate of growth in mm/sec c = a constant AT = equilibrium transformation temperature minus actual transformation temperature "C ?F = free energy per mol of austenite minus that of pearlite ?E* = activation energy R= gas constant ?F in Eq. [1] is computed from the following: ?F=?H?T/To - ?T' dT' ?T' ?CdT"/T" [2] To To where AH is the enthalpy per mol of austenite minus that of pearlite at the equilibrium temperature, To, and AC is the difference in specific heat between austenite and pearlite per mol. Subsequently, Darken, Fisher, and Galligan8 have reported that a layer of ferrite separates pearlite from austenite at the growing interface (i,e., the advancing face of Fe3C is in contact with ferrite, not austenite) and the ratio of the thickness of this layer to the spacing of the pearlite has not been found to vary with alloy content or transformation temperature. This observation does not require any alteration in the above equation: however, it may require that a different significance be attached to the factor, AT. The AT term appears in Eq. [I] as a consequence of a factor for the amount of growth per complex transformed at the interface.* It is based *This is not the sole reason for expecting such a relationship. See Ref. 7._______________________________________________________ on a l/2 ?T dependence of the interlamellar spacing. Zener2 has developed a theory which leads to Soa 1/?V where So = the pearlite interlamellar spacing. This relation is as consistent with the data on interlamellar spacing as other relationships, although, as pointed out by Mehl and Hagel,1 the data are not sufficiently precise to consider the relationship as confirmed. The work of Darken, Fisher, and Galligan8 requires that the above be written where f = the thickness of ferrite layer between austenite and pearlite. The present paper is concerned with iron-carbon-manganese eutectoid alloys and reports experimental measurements of the following kinds: 1) the effect of

Jan 1, 1961

By G. R. M. Del Giudice, A. F. Taggart, Othon A. Ziehl

In a previous paper1 in which one of the authors collaborated, it was postulated that All dissolved reagents which, in flotation pulps, either by action on the to-be-floated or on the not-to-be-floated particles affect their floatability, junction by reason of chemical reactions of well recognized types between the reagent and the particle affected. This generalization, apparently, like many pioneer structures, had for certain observers a flimsy appearance, and these, judging its stability rather by the number than by the character of its foundation posts, have attempted variously to overthrow it, either by the frontal attack of general denial, or by the flanking movement involved in assuming that those cases in which the facts were unknown or unproved were, therefore, discordant. But as time has passed and further evidence on the question has accumulated, it has become apparent that the results of verifiable experiments add stone by stone to the substructure of the hypothesis, and that the super-tructure has lost nothing in weathering. The present paper constitutes an examination of the opposing positions in the light of the more recent evidence developed. It will clarify the discussion if, at this point, we state more fully the implications of the disputed hypothesis. In the first place, it is explicitly limited to reagents that are dissolved in the water of the flotation pulp. Next, it refers only to such of these dissolved reagents as act on the solid particles in the pulp to affect their floatability. This includes the collectors, activators, and certain depressors and gangue-control reagrnts, but not the pure frothers, and not, necessarily, conditioners whose function seems to be merely that of pH control, although in certain cases it has been demonstrated that such control has the effect of regulating the primary reaction of the collector, depressor, or the like. Finally, there is no limitation as to the nature of the chemical reaction postulated.

Jan 1, 1935

By T. Lane Carter

Before describing the experience with the Chinese on the Rand and the work they have accomplished, it will be necessary, first, to give a brief account of labor-conditions in the Transvaal since the war, and then to show how the necessity of importation of labor arose. As is well known, the Transvaal mines are run on the dual system of labor—that is, the rough work is done by colored laborers under the superintendence of white men. From the start of mining operations in South Africa there has been the cry of shortness of native labor, due in great measure to the failure of Kaffirs to work continuously in the mines. While he works, the Kaffir is a satisfactory laborer, but his period of service is short, averaging about nine months. People unacquainted with the Kaffir have maintained that, by offering a higher wage and better accommodation, better results would be obtained from the native workers, but an increased wage simply aggravates the trouble. The Kaffir's wants are few. While at work Be spends little of his money, and before long has sufficient capital with which to buy wives and become a gentleman of leisure. Doubling the wage of the Kaffir means that he acquires a competency in half the time, so that his period of service is correspondingly reduced. In 1899, before the war, there was always a cry about the scarcity of Kaffir labor. The highest number of natives at work was in July and August, 1899, when nearly 100,000 were employed. At the outbreak of hostilities the Kaffirs were scattered far and near, many doing well during the war by working for the military authorities. On the resumption of mining operations on the Rand a serious mistake was made. Based on past experience, it was argued that if the whole industry decided to start anew with

Jan 1, 1909

By W. B. Gogarty

With flow of non-Newtonian fluids in porous media, effective viscosities are needed for use in the Darcy equation. These viscosities depend on the rock parameters and flowing conditions. In this investigation, rheological and flow results were correlated to develop an expression for calculating effective viscosities. Surfactant-stabilized dispersions of water in hydrocarbon were used with consolidated sandstone cores of different permeabilities. The average shear rate in a core was related to the permeability and porosity of the core and the frontal velocity through the core. By using the correlation obtained for determining effective viscosity, experimental and theoretical values were compared for each fluid system by determining average and maximum errors. For the fluid system showing the largest average error, the correlation fit 38 experimental points with an average and maximum percentage error of 4.3 and 14.8, respectively. For the fluid system showing the least error, average and maximum percentage errors of 1.8 and 4.3, respectively, were calculated using 29 experimental points. INTRODUCTION Use of non-Newtonian fluids in the petroleum industry is not new. Fluids of this type have been used for many years as fracturing agents and drilling muds. Recently, attention has focused on the use of high molecular weight polymer solutions for secondary recovery. Results have been reported on studies relating to the flow behavior of polymer solutions in porous media.1-4 Each study gives the viscosity in the Darcy equation as a function of the rheological properties of the fluid, the characteristics of the porous medium and the pressure gradient. The functional forms of the reported expressions differ somewhat in each study. The first three studies used unconsolidated porous media while the fourth used a single consolidated core. Because of the limited information available on the flow of non-Newtonian fluids in porous media, further investigation was undertaken in this area. We selected non-Newtonian fluids that did not contain high molecular weight polymers in order to minimize core plugging. The over-all objective was to gain a better understanding of the flow behavior of non-Newtonian fluids in consolidated porous media. Specifically, our goal was to determine the relationship between the average shear rate in a core and the frontal velocity. Because of this goal, it was necessary to determine the effect of permeability on the shear rate-frontal velocity relationship. We wanted to replace the viscosity in the Darcy equation with an expression relating to the average shear rate in the core and the rheological properties of the non-Newtonian fluid. THEORY For a time-independent, non-Newtonian fluid, the apparent viscosity is a function of the shear rate. This relationship is given by µ = F(v')...........(1) With Eq. 1, a single value of shear rate determines the apparent viscosity at that shear rate. With flow in porous media, a spectrum of shear rates occurs at any average throughput. An average shear rate v' can be used to represent the spectrum of shear rates that exists within the core. By using v' and the rheological data given by Eq. 1, an effective viscosity is determined for the flowing fluid. If v' is the correct average, µe becomes the appropriate viscosity for use in the Darcy equation. Under these conditions, flow rate-pressure drop relationships can be determined for non-Newtonian fluids. HOW the correct average shear rate might be related to the frontal velocity through the core and the characteristics of the porous media will now be considered. Later, the experimental data are presented that indicate the validity of these

By T. B. Counselman

An iron blast furnace of 1000 tons daily capacity will produce a 100,000 cu. ft. per minute of blast-furnace gas. This contains a 25 per cent of carbon monoxide, and has a B.t.u. value of about 95. gas is used primarily for heating the stoves of the blast furnace, secondarily, under boilers, for steam production. Occasionally it is used in gas engines. The raw gas coming out of the furnace carries about 10 grains of dust per cubic foot of gas, under best operating conditions. With furnace "rolling" or slipping, this quantity may temporarily be gre increased. This dust would, of course, deposit on the checkers o: stoves, or plug the burners under the boilers; therefore the gas : be cleaned. Flow Sheet The first step in the cleaning operation, as shown by the flow s Fig. 1, is a dry dust catcher, of which there are several forms, partially cleaned gas next goes to a primary wet washer, where v sprays knock down most of the solid particles. If further cleani desired, the gas may then go to electrical precipitation. Again, the removed is collected in water. Dry dust catchers reduce the dust col from 10 grains to between 4 and 6 grains per cubic foot, and rec roughly half of the total flue dust in the gas. The wet washers rea most of the remaining dust, reducing the dust content to about 1/4 per cubic foot. Electrical precipitators, if used, further reduce the content to about 0.01 grain per cubic foot of gas. The flow sheet s the dust content of the gas at various steps in the treatment and als content of solids in the water. It should be noted that some plant less water on the primary wet washer than indicated, and that ofte solids content of the scrubber water will be 300 grains per gallon, or much higher. Reasons for Recovering Flue Dust.—There are two main incentive recovering flue dust from the scrubber water: (1) the value of the (2) stream or lake pollution, where such a reason applies.

Jan 1, 1937

By Robert Bosworth

THE liability for damages to the surface caused by subsidence is an ever present threat in all underground mining. In ordinary lode mining, this threat rarely materializes into an action, due to the method of mining metalliferous ores, the dip of the veins, and the nature of the ground itself. In the mining of coal, however, this threat is very real. The coal frequently lies close to the surface, in beds underlying large areas of land of which the surface is suitable for agricultural or urban development. Furthermore, the coal is generally mined by the "room and pillar" method and when the pillars of coal are removed, the subjacent support is destroyed. This question of the duty of surface support has now become a very live one in Colorado. What was waste prairie land a few years ago has become valuable agricultural land dotted here and there with growing towns. Frequent references will be made here to Colorado conditions and adjudicated cases, but those conditions and cases and the conclusions to be drawn therefrom are applicable to all coal-mining states. Briefly stated, the question is "Does the owner of the substrata or underlying mineral owe any duty of surface support to the owner of the superjacent strata or surface?" There is -no absolute duty of support owed by the mineral owner and this assertion is made with full knowledge of numerous expressions to the contrary by courts of Pennsylvania, Illinois, Colorado and other coal-mining states. Whether or not any duty exists depends upon the circumstances surrounding each case, and since in the nature of things those circumstances are rarely identical, there can be no absolute rule.

Jan 1, 1928

By E. S. Grumell

The correct sampling of coal and coke is becoming important to an ever increasing number of producers and consumers. This, therefore, may be an opportune moment to examine where we stand with regard to existing and proposed methods. In this paper an attempt will be made to review, as briefly as possible, some of the considerable amount of painstaking research which has been done in the last 10 years, and which has unquestionably led to a much better understanding of the subject. In so doing we shall try, on the one hand, to make clear where substantial progress has been made, and on the other hand, to draw attention to points that require further investigation. The paper is divided into sections in order to emphasize the major divisions of the subject; further, in order to retain this emphasis, detailed consideration of some of the points has been relegated to appendixes. No attempt has been made to give a complete survey of the literature, as this has already been done by L. A. Bushell.2 The following abbreviations will be used: A.E., average error; P.E., probable error; S.W.R., size-weight ratio; B.S.I., British Standards Institution. Section 1.—Cost It has often been stated that the cost of sampling should bear some relationship to the value of the product, and since coal is a relatively cheap raw material it would be a major error to specify, for ordinary commercial purposes, elaborate and costly methods of sampling which nobody would adopt. Specifications must be of such a nature that they will be used. We believe that one of the achievements of the last 10 years has been to reduce the cost of sampling. There is, however, another point to be considered; via., that the cost of sampling should bear some relationship to the value of the investigation. Correct sampling is a cog (possibly a small one) in the wheel

Jan 1, 1940

By Cyril Wells, Robert F. Mehl

The diffusion of carbon in gamma iron plays an essential role in many metallurgical processes. In carburizing, in graphitizing, in homogenizing, in the formation of pearlite from austenite, and in other processes, migration of carbon in gamma iron occurs.1'2 A full understanding of the rate at which these processes occur obviously requires a knowledge of the rate of diffusion of carbon. In carburizing, for example, the depth of carbon pentration is determined by the carbon concentration in solid solution at the surface, and by the rate of diffusion inward of the carbon. Until reliable data on the rates of diffusion of carbon are available it is unlikely that a full quantitative description of this process will be obtained. In the formation of pearlite from austenite, the segregation of carbon and alpha iron from the austenite obviously requires the diffusion of carbon; the rate at which pearlite nodules grow is evidently controlled at least in part by the rate of diffusion of carbon; it is unlikely that we shall understand the factors that determine the rate of growth unless data on rates of diffusion of carbon, and the variation of these with composition, grain size, and temperature are available. Accordingly it was decided: (1) to determine, more accurately than hitherto, the diffusion coefficients of carbon in austenite over a wide temperature and a wide concentration range, (2) to study the influence of grain size and impurities on this diffusion coefficient, and (3) to study the effect of manganese and nickel on the rate of diffusion of carbon in the austenite of manganese and nickel steels, respectively; the influence of carbon on the rate of diffusion of manganese and of nickel will be made the subject of later papers. The rate of diffusion of carbon in gamma iron has been studied by Runge3 by Tammann and Schonert4, by Bramley and co-authors,5-14 and

Jan 1, 1940

By Benjamin Lustman, Robert F. Mehl

The study of the high-temperature oxidation of pure metals, intensively pursued experimentally since the pioneer work of Pilling and Bedworth1 and supplemented by the recent theoretical work of Wagner2 is now well advanced. The important field of low-temperature oxidation—i.e., oxidation extending only through the temper color range of thicknesses with the formation of thin oxide layers in the range from 0 to 1000-2000 ?ngstroms—has not, however, reached so satisfactory a state, owing largely to the experimental difficulties that attend the formation and study of thin films; most of the work has been performed on abraded specimens whose surface irregularities approximated the thickness of the films formed. It has been pointed out that the rates of oxidation of different crystal faces are different and that the difierence may be related to the orientation relationships that obtain between the metal crystal and the superimposed oxide crystal; it has also been suggested that this orientation dependence should manifest itself in rates of oxidation and perhaps also of corrosion in aggregates bearing preferred orientations.3'4 An attempt to measure the rates of oxidation of different crystal faces of alpha iron demonstrated this difference in rate,4 but the dependence of rate on orientation was not simple; the method of measuring thickness, consisting of a color comparison with barium stearate multi-films of known thickness, was not wholly satisfactory. For these reasons it was felt that a study of the rate of oxidation of single crystals prepared with surfaces as smooth as possible, using a sensitive method giving true film thickness, should be profitable. Copper was chosen because of the ease of reduction of the primary oxide film and because the orientation relationships between metal and oxide and the composition of the oxide films formed at low temperatures are known; for thin films formed at low temperatures, Cu2O alone occurs.22-24 Experimental Procedure Various methods of surface preparation were attempted in order to obtain a surface that would oxidize uniformly and repro-ducibly. Electrolytic polishing by the method of Jacquet5 and electrolytic and mechanical polishing followed by annealing in vacuum and in purified hydrogen at various temperatures were tested. The procedure finally adopted consisted in a fine metallographic polish followed by an anneal in purified hydrogen at temperatures of 900° to 1000°C. for 12 hr. or more. The surface so produced was very bright and smooth, with no trace of specular etching (though some grain-boundary etching was observed); indeed, fine scratches produced by the final polish were entirely removed by the high-temperature anneal. After this treatment, the specimens were cooled in hydrogen to room temperature and placed in the oxidation furnace, where

Jan 1, 1941

By George W. Bain

Some problems concomitant with commercial exploitalion of marble are presented as examples of interesting, useful and profitable fields for application of scientific knowledge. The marble industry is only one such field and is selected because its varying new aspects are familiar to the author. However, what is true for marble is equally so in principle for many industrial minerals. The problems of any stone industry are to maintain markets, create new outlets for stone already in demand, and develop varied uses for varieties that are not so popular. Here the geologist has a different role from most of his colleagues in metal mining. The producing branch may ask about the expectable variation in thickness or size of a deposit as development proceeds. The stock department may call for the available amount of a given type of stone before accepting a large order. The sales force requires data on the use for stone from certain parts of deposits in order to divert grades to the most suitable use. The service department wants defects rectified and the cause determined to avoid recurrence The mills want data on durability and cutting quality of abrasives. The geologist occupies no special department; he is on general call, as may be illustrated by a few types of problems that may be classified as: (1) dominantly geological in character, (2) dominantly chemical in character, (3) dominantly physical in character. Geological Problems The geological problems deal almost exclusively with the size of blocks. Size across the deposit is limited by thickness of individual beds. and along the strike by the space between crosscutting joints. Frequently the vertical depth of a block is reduced by exfoliation shells arising from spontaneous expansion. All these factors require consideration in developing a deposit to fill an order. Thickening of Marble Beds The limestone beds that became the marble deposits of the northern Appalachians and of the Yule locality in Colorado were seldom homo-

Jan 1, 1941

By Herman Dykstra, Irving Fatt

Relative wetting phase permeabilities calculated from capillary pressure-saturation data are compared with measured relative permeability data. The equation relating relative permeability to capillary pressure-saturation data is derived by assuming that a porous medium is analogous to a bundle of capillary tubes. The equation includes a term to correct for the difference between fluid path length and length of core. Relative oil permeability data in the water-oil-gas system are presented, and it is shown that if the water is considered part of he rock matrix, the relative oil permeability curve is typical of a wetting phase relative permeability curve. Apparatus for measuring two and three-phase relative permeabilities are described. INTRODUCTION The difficulty in measuring relative permeability of cores has made it desirable to have a correlation between relative permeability and some more easily measured property of porous media. Such an easily measured property is the capillary preisure-saturation relation. In the past there has been a tendency to separate the capillary pressure concept from the very complex pore geometry and to consider that the capillary pressure-saturation curve give? only some characteristic distribution of interfacial curvature between two fluids.' Recently, however, it has been realized that if capillary pressure data are to yield information concerning pore size distribution2 and fluid flow in porous media. the pore must be assumed to have a simple shape such as a cylinder or a sphere. Childs and George' showed that relative water permeability could be calculated from the capillary pressure-water saturation curve by assuming that the pores are cylinders in which the fluid flowing obeys Poiseuille's Law, and that the capillary preisure curve indicated the size and number of pores. Purcell5 derived an equation relating the permeability of a porous medium to the capillary pressure curve by assuming the porous medium to he analogous to a bundle of capillary tubes. Gates and Lietz6 calculated relative permeability by an equa-tion derived from Purcell's equation. In this paper an equation is derived giving the relative water permeability as a function of water saturation by as-sulning that the core sample can be represented by a bundle of capillary tubes in which the fluid path length is not the same as the bulk length, and in which the fluid path length varies with saturation. THEORY For a bundle of N capillary tubes the flow through dN tubes will be dQ = qav dN ..........(1) where Q is the total flow rate through all the tubes and q., is the aberage flow rate through the tubes in the interval dN. If the interval dN is made small the average flow rate through a tube in the interval dN is given by Poiseuille's Law, 8 nl where ?P is the pressure drop across the tube of length 1 and radius r, and µ is the viscosity of the fluid. Substituting for qav in Equation (1), dQ =pr4 ? P/8µl dN.........(3) Darcy's Law for linear flow of an incompressible fluid in a porous medium is Q = KA?P/µL...........(4) where K is the permeability and ?P is the pressure drop across a bundle of tubes which has replaced the porous medium of length L and cross-sectional area A. Differentiating Darcy's Law with A, ?P, µ, and L constant, dQ = A?P/µL dK.........(5) Equating (3) and (5) gives dK------------dN.........(6) 8Al If the pores are assumed to be cylinders dV =pr2ldN..........(7) where V is the volume of flowing fluid in the pores. Substituting for dN in Equation (6) gives dK = —dV..........(8) 8AI' By definition the saturation, S, of the core is v v S =V/Vp..........(9) Vv -PAL

Jan 1, 1951

By D. B Kibler

The Florida hard-rock field extends from Suwanee and Columbia Counties in northwest Florida to south of Croom, Florida, in Hernando County. This area is approximately 100 miles long and varies from 2 to 30 miles in width. Florida hard-rock phosphate was discovered at Hale Springs, about one mile northwest of the town of Dunnellon, Marion County, in the year 1888, by Alber-tus Voight, who lived within a few hundred yards of the spring. Soon after this discovery there was a great influx of land speculators and wildcat operators into the vicinity of Dunnellon. A few years later phosphate was found in Alachua, Levy, Citrus and Hernando Counties, and a great number of small crude plants were built from Newberry, Alachua County, all the way to Croom, Hernando County. Phosphate was found in many places as "outcrops." Looking for outcrops was the first method used by the early prospectors in searching for deposits. Several years passed before any systematic method of prospecting was used. Early Mining The early method of mining hard-rock phosphate was with picks and shovels, wheelbarrows, mules and wagons. The pick-and-shovel method was used altogether until about 1900, when some of the larger operators began to use railroad-type steam shovels of from ½ to I-yd. capacity Picks and shovels, with negro labor loading the phosphate ore (called "matrix") into wooden side-dump skip-cars, was continued until about 1907. From the discovery of hard-rock phosphate until approximately 1905, overburden was removed with mules and scrapers. At some places, the overburden was loaded into side-dump skip-cars by negro laborers and the cars were then pulled up an incline with a steam hoisting engine. The maximum depth of overburden that could be economically removed by hand labor, mules and scrapers was approximately 15 feet. About 1905 one of the companies erected a producer-gas power- I house near Dunnellon and generated its own electricity and about the same time the larger companies began using hydraulic methods for the removal of overburden. From the year 1888 through the year 1939 approximately 75 companies were operating at one time or another in the hard-rock territory, on approximately 500 locations. The hard-rock deposits are more irregular and have higher mining costs than the pebble-rock deposits, therefore 1 they have not been competitive in the domestic market, but because of the higher grade of the hard rock it is in demand for I the export trade. Discovery of phosphate outside of the United States has made it increasingly difficult in recent years for the hard-rock companies to survive, so today i only three companies are operating. These

Jan 1, 1942

By W. A. Turcotte, A. D. Paananen

Introduction The large reserve of fine grained oxidized iron-formation at the Tilden mine has been the object of research and development efforts to concentrate the iron oxides as far back as 1949. Due to the nonmagnetic nature of the ore and the fine grinding required to liberate the iron oxide minerals, this crude ore was not amenable to concentration by conventional methods. The iron oxides of the Tilden, ore body have a grain size of less than 25 microns and recovery of the finer, well-liberated iron oxides is essential. Conventional methods of desliming employing cyclones or thickeners were not feasible because of the excessive loss of iron oxides in the finer fractions. Development of selective flocculation-desliming was a key to commercialization of the process. Operations started in late 1974 with Algoma Steel Corp. Ltd., J & L Steel Corp., The Steel Company of Canada Ltd., Wheeling-Pittsburgh Steel Corp., Sharon Steel Corp., and The Cleveland-Cliffs Iron Co. as participants. Cleveland-Cliffs operates and manages the operation. Development of the Tilden Flowsheet The geology and ore reserves of the Tilden mine have been detailed in a paper by Villar and Dawe (1975). A joint program was undertaken in 1961 with the US Bureau of Mines in Minneapolis using the flowsheet developed by the Bureau employing the selective flocculation-desliming and calcium activated anionic silica flotation method (Frommer, et al, 1966; Frommer, 1964; Frommer, Wasson, and Veith, 1973). During this time, parallel testing at Cleveland-Cliffs Research Laboratory and Pilot Plant centered on the same type of desliming but was followed by the cationic flotation of silica with amine collectors (Columbo and Jacobs. 1976). The cationic silica flotation system was eventually chosen for its overall efficiency and simplicity. Regardless of the flotation method chosen, the technique of selective flocculation-desliming prior to flotation is the key to the success of the process. The flowsheet is described in detail by Villar and Dawe (1975). [Figure 1] shows a simplified one-line flowsheet of the Tilden concentrator. A total tailings thickener has been added to the original flowsheet and was placed in operation in 1978. The total-tailings thickener overflow reports to the reuse water pond and the underflow is pumped approximately 8 km (5 miles) to a storage basin. A flowsheet of the reuse water system is shown in [Fig. 2]. Selective Flocculation-Desliming Data have been published on the mechanisms and factors affecting selective flocculation in iron oxide-silica systems. The intent of this paper is not to discuss the theoretical aspects of selective flocculation, but rather to present experience gained from the commercial Tilden operation and from bench and pilot plant testing of fine-grained oxidized iron ores. From the bench and pilot plant testing prior to plant startup, certain reagent combinations and rates for the commercial Tilden plant were established. In the experience gained from three years of plant operation at Tilden, some of these reagent dosage rates have required significant adjustments due to changes in reuse water quality and to meet the requirements of varying ore types. Reuse Water The process water quality is a major concern at the Tilden mine and is constantly being monitored for selected chemical and physical characteristics. This monitoring has continued on a regular basis in order to gain a more thorough understanding of the interactions taking place in a dynamic water system and particularly as water quality is influenced by seasonal variations. Control of the reuse water chemistry is essential to the Tilden process both in the selective flocculation-desliming and flotation stages of concentration. With roughly 75% of the reuse water used in grinding-desliming operations, it is readily apparent that the biggest "reagent" in the selective flocculation-desliming process is water. Not enough can be said about the close control that must be exercised on the overall reuse water system. Control of the chemical treatment of the feed to the total tailings thickener is of utmost importance in order to produce a reuse water for the concentrator that is compatible with all stages of the concentrating process. There are many analyses made which aid in judging the quality of the water. Some of these are shown in [Table 1]. Five are particularly important and are monitored daily so that reagent adjustments can be made as required: suspended solids, calcium hardness, pH, dissolved silica concentration and temperature.

Jan 1, 1981

By C. H. Aldrich

For many years the City of Prescot, about 8 miles northeast of Liverpool, has been the home of British Insulated Cables, Ltd., one of the largest wire mills and manufacturers of electrical equipment in England. Since this location is close to the industrial center of the country and the seaboard, with good railroad transportation facilities, it was a logical site for the new refinery. Early in April, 1932, the writer was called upon to prepare a preliminary layout and estimate of cost of the proposed plant, and shortly afterward, following a discussion of these figures with officials of British Insulated Cables, in England, the decision was reached to proceed immediately with construction of the plant. The refinery was built by British Insulated Cables, Ltd. Designing of the plant was started early in May, 1932, orders for equipment being placed as rapidly as possible. On July 18 the first steel was erected and the first charge was cast on Jan. 5, 1933. No difficulties of any consequence were experienced in starting the plant and the grade of copper produced was quite satisfactory after the first charge. The initial capacity desired was 2500 tons of refined copper per month. Since only one furnace was to be built, it was necessary that it should have sufficient reserve capacity to catch up after unavoidable shutdowns. It was also necessary to lay out the plant so that it would operate efficiently at this tonnage and at the same time permit expansion in the future, if necessary, to several times its original capacity. In order to meet these conditions and also to take full advantage of the space available, the layout shown in Fig. 1 was adopted. The principal plant structures are a blister storage aisle, casting building, wire-bar storage building and a coal-pulverizing building. Additional smaller structures include a brick and charcoal shed, pumphouse, drill room, water-cooling tower, clay-preparation shed, substation and plant office. Incoming blister is received in either broad-gage railway cars or steam motor lorries in the blister storage aisle, unloaded by overhead electric crane to narrow-gage cars, weighed and sampled, then either sent directly to the furnace or placed in storage. After refining, the copper is cast on the wheel, passes through the cooling bosh and is

Jan 1, 1934

By R. M. Lumley, J. D. Wood

In this investigation, polyethylene terephthalate (Mylar) was coated with various thicknesses of a vapor-deposited silvel- precoat followed by a uapor-deposited zinc using several orders of- magnitude variation in deposition rate of both the silver and zinc. The grain size and resistivity of the zinc film was primarily a function of the silver precoat thickness (in the range of 0.001 to 10 average Agprecoat thickness) and a secondary function of the zinc film thick-ness. The silver and zinc deposition rates were found to have a minor effect on the characteristics of- the zinc film. Electron and X-ray dilffraction results slwwed that all zinc films exhibited a fiber texture mith the (0001) axes essentially perpendiculav to the platze of the film When coating nonmetallic substrates such as paper or plastics with zinc metal vapors, it is found that the zinc will not condense unless extremely high evaporation rates or very low substrate temperatures are used. In 1931, Fraser' reported a procedure whereby zinc could be made to condense on nonmetallic substrates by depositing a very thin precoat of silver. Utilizing Fraser's method, the ermans' developed a commercial process of making "metallized film" capacitors during World War 11. The metallizing process, which was introduced in the United States shortly after the conclusion of World War 11, became one of the first large-scale commercial applications of vapor-deposited metal films and remains one of the larger applications in the electronics industry. The process, as developed by the Germans, consisted of depositing a thin precoat of silver on lacquered, kraft paper followed by a conducting layer of zinc. The resulting silver-zinc film was used as the capacitor The term silver-zinc will be used throughout thiz paper to mean a metal film formed by an extremely thi layer of silver, 10A or less in average thickness, and a zinc film IOOA or more in thickness deposited on the silver film. ---. electrode with the lacquered paper being the dielectric. When polyethylene terephthalate was marketed by E. I. Du Pont Co. in the early 1950's under the trade name Mylar it was substituted for the kraft paper in many capacitor applications. Even though manufacture of metallized paper and metallized Mylar capacitors has been a large commercial process for many years, little information has been published about the deposition parameters. Correlating the work of others to the various effects to be expected of deposition parameters on silver-zinc films deposited on Mylar, it is expected that the

Jan 1, 1967

By Michael Tenenbaum, C. C. Brown

Numerous investigatiolls have been carried out to determine the total oxygen present in the basic open-hearth bath and the results of these studies have clearly defined the factors controlling the bath oxidation during the period prior to deoxidation. On the other hand, very little is known concerning any changes in total oxygen content that may occur during deoxidation, tapping and teeming. The need for such additional data is continually becoming more apparent, since there is no strict technical basis for selecting any particular deoxidation practice. Many steels are made for the same purposes and to the same chemical analyses by widely differing practices. Apparently, each practice is satisfactory. However, it would be desirable to establish more definitely the effects and relative merits of the individual practices. Such information could be used to give a definite foundation for evaluating various types of deoxidation. In order to approach this problem, a study was made of the changes effected in the total oxygen content of several grades of steel by representative open-hearth deoxidation practices. To carry out such studies, it was necessary that a reliable testing procedure for determining the oxygen content of the steel bath and the ingot mold be established. Before entering on any extensive testing program, consideration was given to the available methods of obtaining steel samples and analyzing for oxygen. Testing Procedures It has been shown5-9 that in solidified steel oxygen may ekist in combination with iron, manganese, silicon, aluminum, titanium, chromium and carbon, depending upon the amount of these elements in the sample. In molten steel, however, there has been no direct distinction of the various oxides. Accordingly, the total active oxygen in the molten steel bath is designated by the symbol 0. During deoxidation, various oxides may be present either in solution in the molten steel or as solid or liquid inclusions. Any sample taken from the molten steel for oxygen analysis will include both the dissolved and the mechanically included oxygen. Similarly, samples of the solid steel product will also include the two forms of Oxygen' Methods of Samplirzg the Molten Steel Bath In order to obtain a true oxygen analysis from liquid steel, this element must be completely retained in the solidified sample. Several methods have been proposed whereby this stabilization can be effected. As early as 1915, Kichlinelo proposed a method for testing molten steel, in which the oxygen combined with some added aluminum. The concentration of the resultant aluminum oxide was determined by chemical analysis. This method was

Jan 1, 1945

Chairman James F. Kemp :—I call upon Prof. Albert Sau-veur to open the general discussion on the subject of sound steel ingots. Albert Sauveur, Cambridge, Mass.:—I believe that I have the privilege, this instant, of opening one of the most important, significant and far-reaching discussions ever held before this Institute. I believe that our talk this morning will be heard far and wide, not only on this side of the water, but also on the other side. Everywhere, in short, where steel is manufactured. I welcome the opportunity of expressing my mind in regard to the production of sound steel ingots, a subject about which I entertain Rome very decided opinions. I shall not attempt to discuss the relative merits of the various processes that have been described. I shall, on the contrary, confine myself to a general consideration of the important questions before us. So intensely do I feel regarding the production of sound steel ingots that I have put my remarks on paper in my desire to present my views. I have always remembered my astonishment, not to say dismay, some twenty years ago, when I beheld for the first time a steel ingot, a rail steel ingot, that had been split open from top to bottom. There was the pipe! There was an enormous cavity extending from a short distance from the top to nearly one-third of the length of the ingot; and when I was told that manufacturers seldom discarded more than one-tenth of the total length of the ingot it became evident to me that a large proportion of piped, and therefore, defective, or at least weak and dangerous, rails were manufactured; in fact, probably one rail out of six, nearly 17 per cent., of dangerous rails.

Jan 1, 1914

By L. L. Gray, D. W. Reed, F. Morgan

A flowMeter has been developed at Gulf Research and Development Co. and tested in the field for measuring the flow of gas in well bores. It has been used in a study of the injection capacity of different horizons in gas injection wells in Oklahoma. The flow sensitive element of the meter is a semi-conductor having a very high temperature coefficient of resistance. Advantages possessed by this meter are the result of that property and the high specific resistance of the element. The instrument possesses a sensitivity considerably higher than any reported previously. In the application described here the element is heated to a temperature considerably above ambient by an electric current, which is supplied by a voltage source at the surface. When fluid flows through the meter the rate of dissipation of heat is increased and the temperature of the element decreases. Because of the negative temperature characteristics of the resistance element such a decrease of temperature will be accompanied by an increase of resistance which, under flow conditions ordinarily found in wells, is of such a magnitude that it can be directly measured or recorded in terms of a change in voltage at the surface. In practice, rate of flow is measured in terms of the drop in voltage in the resistance element. All the metering and control apparatus remains at the surface while the thermal element is lowered into the well on a single conductor cable, consisting of an insulated wire and sheath. The meter is calibrated by passing known quantities of gas through it either at the surface or in the hole at a point immediately above the region in which gas is lost to the formation. In case calibration is made at the surface, the ambient temperature in the hole may readily be obtained by a second resistance element which is operated at a current so low that effectively no heating occurs. The instrument has been adapted to con-tinuous recording, but the velocity of the meter relative to that of the gas must be low unless corrections are made. Curves giving data obtained in actual field tests are shown' The meter can also be used to determine the distribution of flow capacity in a gas producing well. A differential form of the meter has been designed and built in which the local flow or injection capacity of the formation is obtained directly. Introduction When fluid is injected into a well in a secondary recovery or pressure-maintenance operation the question of its most effective use invariably arises. Although the core log, when available, will show the regions of good permeability and oil saturation, there is normally no assurance that the fluid actually enters the formation in zones where injection is deemed desirable. In view of the uncertainties involved in such programs, it is generally conceded that measurements of permeability for a formation in place are more significant than those obtained by the core-sampling technique. A subsurface meter has been developed at the Gulf Research and Development Co. for measuring flow of fluids at different horizons in a well bore, and field tests have been made on the instrument in Cooperation with the Tulsa Division of the Gulf Oil Corp. In this paper the meter is de-

Jan 1, 1948