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By E. F. Burch, R. W. Schoenberger

This paper deals with an investigation of the use of steam filtration for filter cake dewatering and shows that it may be applied on a practical scale. The advent of larger quantities of minus 1/4 in. coal in the raw feed to the preparation plant and the necessity of recovering this material has made the problem of meeting product moisture specifications more difficult. For a number of years thermal dryers have been used advantageously as a means of reducing fine coal moisture content where the over-all economics would justify such an installation. However, these units are not without their drawbacks because of high capital and operating costs, safety hazards and possible degradation of the product, and thus an alternative method of moisture reduction is highly desirable. After the various mechanical variables associated with filtration have been optimized, an examination of theory shows that surface tension and liquid viscosity are the only two remaining variables which might be altered to reduce moisture content. A lowering of the surface tension within the limits of normal wetting agent dosage results in a rather insignificant decrease in cake moisture content. Not until the dosage is increased to a point well beyond this limit is there an appreciable decrease in moisture. At these high dosage levels, interfacial tension is a major factor contributing to the appreciable moisture reduction obtained. Since no suitable method has been developed to recover and recycle this wetting agent, this phenomena is not of practical significance. On the other hand, a reduction in liquid viscosity has a pronounced effect on cake moisture. While it is readily apparent that one method of reducing liquid viscosity is to heat the entire feed slurry, it is equally apparent that this would not be an economic approach except, perhaps, in certain isolated cases. It does, however, suggest that water circuits should be designed to conserve heat as much as possible and to make use of any waste heat that may be available. The use of hot air as a heat carrying medium for drying porous materials on a filter has been practiced for many years. However, this method is restricted to materials with a high air rate in the order of 100 cfm/ ft2 because of the low heat release per unit weight of air passing through the cake. The normal fine coal filter cake has an air porosity far too low to make this a practical approach. Various types of radiant heating devices have been investigated and can significantly lower moisture content at reasonable thermal efficiency. However,

Jan 1, 1964

By Harold M. Feder, Irving Johnson

Tkermodynamic functions for dilute solutions of uranium in liquid cadmium were obtained from galvanic cell measurements. Deviations from Henvy's law were observed at concentvations down to 2 x 10-3 atom fraction. Unusually large negative values of the pavtial molal relative enthalpy and excess entvopy of uranium, suggestive of the occu,vvenctwe of partial ovdering of cadmium around uranium in these solutions, were found. The negative relative partial molal enthalpy of uranium at the liquidus accounts for the observed retrogvade solubility of metallic uranium between 473" and about 630°C. The standard free enevgy of formation of UCd,, from a-uranium and liquid cadmium is given by F,° THE constitutional diagram of the U-Cd system,' Fig. 1, is unusual in several respects. The near equality of the Goldschmidt atomic radii2 (Cd, 1.52A U, 1.56A) might be expected to give rise to extensive mutual solubility of the elements except for the restrictions imposed by differences in valence and electronegativity.3 The latter factors must be strongly influential because mutual solubilities in the terminal solid phases are probably negligible, and the solubility of uranium in liquid cadmium in the readily accessible range is only about 1 at. pct. Interestingly, the solubility of uranium in liquid cadmium actually decveases slightly with increasing temperature from 473" to about 630°C. Such a retrograde solubility in a liquid phase is a rare phenomenon in metallic systems; no other authenticated examples were found among the nearly 700 binary phase diagrams compiled by Hansen and Anderko.2 These observations suggested the existence of some unusual interaction between uranium and cadmium. Greater insight into the nature of this interaction was sought by measurement of the thermodynamic properties of the system. EXPERIMENTAL PROCEDURE The emf of cells denoted by the scheme was measured. Each cell consisted of two uranium and two alloy electrodes immersed in a molten lithium chloride-potassium chloride eutectic mixture containing uranium trichloride. The physical arrangement is shown in Fig. 2. The potential between any pair of electrodes could be measured with a Leeds and Northrup Type K-3 potentiometer. The measurements were made at points marked in Fig. 1. It should be noted that points on the phase boundaries represent the concentrations of uranium in the saturated liquid phases of heterogeneous alloys. Uranium Electrodes. Uranium, which is not a particularly soft metal, is capable of retaining residual stresses, and its potential may depend upon its physical condition. Electrodes were prepared from 3-mm diam rods of hot-rolled high-purity4

Jan 1, 1962

By Paul H. Price, John P. Nolting

The history of the salt industry in West Virginia dates back nearly two hundred years; howTever, the history of salt as an important raw material for the chemical industry is much more recent. The earliest record of West Virginia salt was in 1753, when a raiding party of Shawnee Indians attacked frontier settlements in Virginia taking captive a number of the pioneers. One of these, who later escaped and returned to her friends, described how the Indians camped at a salt spring on the banks of the Kanawha River and evaporated the water to obtain a supply of salt to take back to Ohio with them. Settlement of the Kanawha Valley began in 1774, that same year the Battle of Point Pleasant ended the Indian's power in the Ohio Valley; and settlement of the Kanawha Valley progressed rapidly with a consequent increase in the importance of the Kanawha Licks as a source of salt. In those days the evaporation of the brine was a family matter for which the family wash-kettle was commandeered. In 1797, Elisha Brooks erected the first salt furnace in the Kanawha Valley. It consisted of two dozen small kettles set in a double row, with a flue beneath, a chimney at one end, and a fire bed at the other. He obtained his brine at a depth of 20 to 30 ft by sinking hollow logs, called "gums" into the salt lick and dipping the brine with a bucket. His production was about 150 lb a day and sold for 8 to 10 cents a pound. In 1806, the Ruffner brothers, David and Joseph, prospected for and drilled the first well in America using a spring pole and steel chisel bit. After several failures they succeeded, in 1808, in drilling to a total depth of 59 ft where they secured a good flow of strong brine. Most standard drilling tools, jars, casing, and practically all the basic oil well drilling machinery now in use, were developed in the drilling of salt wells. To evaporate this brine, the brothers built a wood-burning furnace similar to that of Brooks but with a better arrangement and with more and larger kettles. When production was started they reduced the price of salt to 4 cents a pound. By 1817, there were some 30 salt furnaces in the Kanawha area. It was in this year that bituminous coal first was used as an industrial fuel. David Ruffner again pioneered the way by converting his furnace for the consumption of coal. This year also brought about the formation of the first trust which controlled production and set a price of 1 cent a pound for the salt.

Jan 1, 1950

By L. C. De Jong, J. F. Shirley, M. L. Campbell

At the Southern Peru Copper operation in Toque-pala, Peru, a new process flowsheet for the recovery of byproduct molybdenite has proved successful in dealing with complex and highly variable ores. This paper describes the process and the functions of each of the chemicals used. The Toquepala concentrator of the Southern Peru Copper Corp., located approximately 720 miles southeast of Lima near the Chilean border, processes a daily 36,500 tons of ore containing between 0.50 and 3.00% copper. The molybdenite content in the ore also varies greatly ranging from essentially nothing to as high as 0.15%. The 1966 yearly averages were approximately 1.20% copper and 0.03% molybdenite. The Toquepala porphyry deposit is a mushroom-shaped ore body consisting of a flat-lying enriched zone of predominant chalcocite with a stem-like extension of hypogene chalcopyrite ore in depth within and around a large breccia pipe.1 The underlying chalcopyrite ore has not been reached; however, due to the presence of a major post orebody fault, predominantly chalcopyrite ore is present in the north side of the pit. Most of the molybdenite occurs either as small, fine granular, pulverulent masses in vugs or empty voids of breccia, or as thin foliated masses and narrow thread-like filling in rock joints and fractures. The normal occurrence of quartz gangue with the molybdenite gives some basis for correlating the molybdenite mineralization to some later periods of silicification. On April 18, 1962, the molybdenite recovery plant at Toquepala went on stream, approximately 27 months after the copper concentrator had been in production. The plant was designed and built by Southern Peru Copper Corp.'s engineering and mechanical departments. The basic method chosen for separating the molybdenite from the copper concentrate was the sodium hypochlorite-sodium ferrocyan-ide process. The selection of this process was based on the results of an extensive testing program performed by the Colorado School of Mines Research Foundation, Inc. and the economic conditions of the area. The originally designed process could never be fully implemented due to a lack of sodium hypo-chlorite and has had to be continually modified to satisfy the requirements of the kaleidoscope of ores from the mine. The three basic problems that plague the operation of any molybdenite recovery plant are all present at Toquepala in large measure. Both the quantity of plant feed and the quantity of molybdenite contained in the plant feed are continuously changing. Even more detrimental to an efficient operation is the fact that the copper mineralization in the feed frequently changes once in every 24 hours and occasionally once a shift. From the point of view of the molyb-

Jan 1, 1968

By Jose A. Ruiz

INTRODUCTION For heterogeneous non-catalytic solid-gas reactions carried out in fluidized bed reactors, nominal bed temperature is an average value between gas and solid. For highly exothermic reactions, actual particle temperature can be up to hundred degrees above termocouple temperature, since heat dissipate at slower rate than heat generation during some steps of transformation. These micro instabilities at particle level can displace thermodynamic equilibrium from the desired phase to others. This effect is important when relatively narrow range of phase stability exists, like in sulphation roasting of sulphides, where bed discharge contains, in addition to the desired sulphate others metastable phases such as basic sulphate and ferrite. For example, for copper-iron sulphide concentration roasted below 680°C, no cupric ferrite is formed, as shown by Jakob et al., therefore the separate Kellogg's stability phase diagrams Cu-S-O represent the roasting (Fig.l). At temperature above this one, like 760°C for example, phase stability changes from CuSO4 to the basic sulphate Cu0•CuSO4. Solid state reaction between Cu0•CuSO4 and Fe203 also occurs to form cupric ferrite, Cu0•Fe2O3, therefore the Cu-Fe-S-O Kellogg's phase diagram of Fig. 1 (continuous line) represents this condition of roasting. Although both Cu0•CuSO4 and Cu0•Fe2O3 are metastable phases under normal operating conditions of sulphation roasting(1-10% SO2, 1-10% 02 and 680°C, points A and B,Fig. 1) sulphation of these species and particularly ferrite are slow and limited due to diffusional control. This explain why reactors discharge contains several phases: CuSO4, Cu0•CuSO4, CuO•Fe203 plus small amounts of CuS and FeS due to the baclonixed conditions of fluidized bed reactors. The presence of cuprous ferrite due to reducing conditions inside individual particles also occurs, but in very limited extent at the reaction interface, as it is demonstrated by the low soluble iron levels of calcines. On the other hand, the presence of cupric ferrites can be explained only due to the higher temperature achieved by particles, since below 680°C cupric ferrite formation does not take place. [ ] This phenomena also occurs for others non-ferrous metal sulphides concentrates roasted under sulphation conditions, such as 7n, Co and Ni. Therefore the prediction of discharge composition of fluidized beds is not possible based only on kinetics and mechanistics models alone or purely thermodynamical considerations, since all factors should be integrated to describe the overall phenomena. SINGLE PARTICLE TRANSFORMATION Assuming a first order reaction with respect to the gas and zero for solid, such as

Jan 1, 1984

By Martin A. Mayers

It has long been recognized that it would be highly desirable to be able to predict the temperatures at various points in a burning fuel bed and their variations with changes of the properties of the fuel and the rate of air supply. Experimenta1 investigations of fuel-bed temperature1-4 have not been lacking, but the absence of any theoretical background has made it impossible to use the results of these tests as a basis for prediction, except in a very general may. A mathematical analysis", based on a somewhat simplified theory of the distribution of lieat in a fuel bed, lias recently been completed by the author. Even though numerical values of some of the coefficients are not known, the calculations result in some conclusions of general significance. Thus, for example, it appears that when the temperatures throughout the fuel bed can be calculated, the rate at which ignition of the fuel by underfeed action can be maintained can also be calcu1ated. The uncertainty concerning the values of the coefficients referred to above is serious limitation on the use of that method. The following paper presents a discussion of these coefficients and includes estimates of their values based on the data now available. A brief description of the theory on which the analysis is based, and some results of the calculations showing their degree of agreement with experimental results, are presented by way of introduction to the discussion of the coefficients. For a more. extended discussion of the theory, see the A.S.M.E. paper5. Theory and Comparison with Experiment The theoretical analysis is similar to that used in the calculation of the stationary temperatures in a conducting solid in the classical theory of heat concluction. The fuel bed is pictured as a uniform, continuous, porous solid through the interstices of which air can be blown and ill which combustion can take place. The solid lias a finite thermal conductivity, so that heat may be transported in any direction, against the flow of air as well as in the same direction. While it is true that nothing

Jan 1, 1938

The Lornex mine is located in the Highland Valley area of British Columbia, Canada, one of the most,promising districts of low-grade porphyry-type copper mineralization in the world; Lornex is operated by Rio Algom Mines, Limited, a member of the Rio Tinto Zinc Group of London. Exploration from 1965 to 1968 disclosed an ore body of 293 million tons with a grade of 0.43% copper and 0. 14% molybdenum; this led to the decision to construct a 38,000 tpd operation, and production commenced in the fall of 1972. The ore is open-pit mined with 15 cu yd (11 5 m3 shovels, which load 100- and 200 -ton trucks. These trucks dump directly into a 60 in. by 89 in. Allis -Chalmers gyratory from two sides of the 14 ft 6 in. (4.42 m) deep dump pocket and across splitters mounted on the pocket sides. The unlined pocket would hold 1,000 tons level full. The crushedore discharges into a 300-ton surge hopper equipped with an automatic sonic level indicator to prevent over -filling. A 96 in. by 23 ft (2.44 m by 7 m) apron feeder delivers the ore from the surge hopper to a 72 in. (1.83 m) transfer belt equipped with a tramp iron metal detector. The transfer belt discharges to a 60 in. (1. 52 m) conveyor which conveys the ore about 3,000 ft (914 m) to the 475,000 ton ore storage pile located near the concentrator. Four 48 in. (1.22 m) pan feeders transfer the ore to the mill feed conveyors, which in turn supply the two 32 ft by 15 ft (9. 75 m by 4. 57 m) semi-autogenous mills, which easily accept the 10 in. (254 mm) product of the crusher. Each semi- autogenous mill is followed by a secondary ball mill. The unusually large open side setting of the crusher accounts for its 6,300 tph maximum capacity. Concentrator capacity is now 48,000 tpd. Eccentric removal is eased by the design of the door to the crushed ore pocket, which has the cart rails mounted on its outer surface and is lowered to a horizontal position in the pocket by an electric winch. The top of the door rests on wear bar covered concrete piers in the pocket. Another feature is a chute through the floor at the crusher base that extends into the crushed ore pocket. Dust and spills of ore on that floor during crusher repairs are easily swept into the crushed ore pocket. This feature is also used at Bougainville and Palabora and has been added to others after operation has commenced. The design follows the concrete rectangular box concept with four main service and maintenance levels shown in the sectional drawings, although a third additional section has been added at the maintenance

Jan 1, 1978

By Lyall Zickrick

Numerous brands of virgin pig lead are used in the manufacture of lead and lead-alloy cable sheath for commercial cables. In changing from one brand of pig lead to another a readjustment of press operating conditions is nearly always necessary. This is due largely to different flow characteristics, and some brands extrude at a much lower pressure than others; for example, copper-bearing lead requires much more pressure than a low-bismuth lead under the same operating conditions. With the modern type of lead press the extrusion practice in general differs very little. Molten lead at a temperature of 375" to 400" C. (710" to 750" F.) is cast in a water-cooled cylinder and allowed to cool or solidify into a slug for six to nine minutes, This slug is forced into the die block and around the core tube through which the cable runs. The • die block is held at an optimum temperature by means of gas flames, usually 175" to 225" C. (350" to 435" F.). Measurements of the temperature of the cable sheath taken at the time of extrusion have covered a range of 190" to 225" C. (375" to 435" F.). According to Tammann, the rate of extrusion for a metal under constant pressure through a simple orifice is almost doubled for each 10" C. rise in temperature. Because of the irregularity of die-block construction, such a great increase is not obtained in lead-cable extrusion practice. To obtain more definite information about the effect of small percentages of metals usually present as impurities in virgin pig lead, a series of compression tests were made covering several different brands of lead and various alloys. Since the usual temperature of the sheath is approximately 200" C. as it emerges from the die block, these compression tests were all performed at 200" C. Five different brands of virgin pig lead were selected, as follows: Brand A: A desilverized western lead of very high purity. This lead contains neit,her copper nor bismuth. Brand B: A bismuth-free southeastern Missouri lead, usually containing 0.05 to 0.08 per cent copper. Brand C: A copper-free mid-western desilverized lead of very good grade, usually containing around 0.06 to 0.10 per cent bismuth.

Jan 1, 1932

By E. R. Parker, T. H. Hazlett

An understanding of the mechanism of creep of metals requires an accurate knowledge of shape of the time-deformation curve. An expression is developed which accurately expresses the creep curve for a number of structurally stable metals and alloys. VAST strides have been made in the development of high temperature creep resistant alloys; however, no sound understanding of the physical mechanism of creep exists to date. Consequently, creep resistant alloys are still developed by "cut and try" methods formerly so successful but now yielding returns at a continuously diminishing rate. It is apparent to all workers in the field that if the mechanism of creep were understood, much fruitless labor could be avoided. The dirth of fundamental knowledge has not discouraged the theorists. Speculation has flourished and numerous theories of creep have been proposed. A critical review of these theories reveals that, even though there are some general areas of agreement between the majority of the workers, there are many basic questions yet to be resolved.' It is generally conceded that theoretical speculation is far in advance of experimental evidence. The shortage of reliable creep data greatly hinders more rapid progress in this field. It is essential that the effects of different stresses and temperatures on the creep characteristics of metals be quantitatively determined. Once this has been accomplished, it will then be possible to evaluate the effects of alloying additions and, it is hoped, to provide a firm basis of facts for theoretical treatment of the creep phenomenon. The work reported herein was undertaken to determine the effects of such variables as stress, temperature, alloying, and structure on the creep characteristics of some metals. Material and Equipment Nickel was selected as the base material for the current investigation and an experimental program was initiated to determine the effects of temperature and stress on the creep characteristics of this material. Since a large quantity of high purity nickel was required for the proposed program and such material was not commercially available, it was decided to refine, cast, and prepare the required metal in our own laboratory. The resulting nickel test bars had the following composition, given in percentage by weight: Fe, 0.030 (1); Si, 0.003 (2); Ca, 0.001 (1); Mg, 0.020 (2); and S, 0.002 (2); to make total impurities of 0.056. The nickel (balance by difference) is 99.944 pct. The details of the purification process are described elsewhere.' This

Jan 1, 1954

By C. E. Meissner

The need for a practical method of deciding upon new alloy steel analyses to widen its markets was the problem facing the Chrome Steel Works at the beginning of 1927. In addition to determining the physical properties of the alloys under consideration, it was necessary to test their value in service. Small melts of steel in a crucible, from which test specimens could be made, were insufficient to determine more than physical properties, therefore actual castings and ingots had to be made before the products could be placed in service. Furthermore, to save further experimental work, it was desirable that these heats should be made on a "pilot" basis; that is, actually duplicating regular open-hearth furnace practice. Therefore a one-ton (2000-lb.) acid open-hearth furnace was built. Furnace Design There are no special features in the design of this furnace. Standard acid open-hearth practice is followed, with the reproportioning of the dimensions necessitated by its small size; notably, a considerably increased length in proportion to width in order to get proper flame propagation. After the first heat was made it was found that the check-ers were insufficient. The checker chambers were increased in size and the checker openings were made much smaller. The furnace was started late in March, 1927, and made 65 heats. Experimental work was then stopped unti1, the data accumulated could be worked up and summarized. The run was resumed in November and the furnace is still operating, having made at this writing 60 additional heats. For the last series of runs, there was some rebuilding of both the furnace itself and the checkers. Slag pockets were added. Fig. 1 shows details of construction; Fig. 2, the general appearance. All designing was done by the operating and engineering staff. Construction materials were those available around the plant. The reversing valve is a standard butterfly type taken from an old furnace. The slag pockets and checkers are cleaned by digging down to arched openings which have been bricked up.

By Theron Wasson

The discovery of two new fields—the Reed City area of Osceola County and the Headquarters field, of Roscommon County —and the important development in Winterfield township, Clare County, again demonstrate the fact that it is the unknown and unexpected that enter very definitely into the oil-producing history of Michigan. This is particularly true in the area of thick glacial drift in the north central part of the state, where the new prolific fields have been discovered this year. This shifts the interest from the southwestern part of the lower peninsula, where a number of pools were rapidly developed during 1939 and 1940, back into the Central Basin area. As a result of strict proration in the new areas, the production for the state of Michigan for the year has not been as great as in 1940 or 1939. In 1941 the total production was 16,300,000 bbl., in 1940 it was 19,551,000 bbl., and in 1939, which was the peak year, it was 23,300,000 bbl. However, the discovery of the new fields this year nearly doubles the estimated reserves for Michigan reported at the end of 1940 In 1941 about 12,000,000 bbl. of oil was produced from the older fields, in which the individual well productions were so small that proration was not an important factor. The total production for the state from the discovery of oil in 1925 through 1941 now stands at 161,205,000 barrels. ActIVe Oil Fields Reed City Field.—In the Reed City field, Lincoln township, Osceola County, only small oil wells were completed during 1939 and 1940. The discovery of much larger production in wells drilled somewhat deeper, by The Pure Oil Co. and the Weber Oil Co., in the early part of 1941, led to the rapid development in this area. Some wells have had initial productions as high as 10,000 bbl. By the end of the year III producing wells were completed, with an average depth of 3600 ft., from the Detroit River formation of Devonian age. The entire development of the field to the end of 1941 was on 20-acre spacing. Headquarters Field.—The Headquarters field, which lies along the line between Clare and Roscommon Counties, was one of the most important discoveries of 1941 and will be the scene of vigorous development during 1942. Production so far has been from the Traverse lime at about 3400 it., and development has indicated that this is probably one of the most productive Traverse pools yet discovered. One well had been given a potential of 10,000 bbl. per day. Dry holes well located in relation to big producers indicate that it is a typical Traverse development. Winterfield Field.-This field, in Winter-field township, Clare County, was discovered late in 1940. By December 1941, 14 Dundee and 5 Traverse producers had been completed. The Dundee lime is found at a depth of 3750 it. and the Traverse lime at 3070 it. Producing conditions in the Dundee seem to be erratic because of varying porosity in the dolomit-ized limestone. Kawkawlin Field.—The Kawkawlin field, which was discovered by the Gulf Refining Co. in 1938, is in Monitor and Kawkawlin townships, Bay County. Small production

Jan 1, 1942

By Ralph M. Hunter

Until recent years, maintenance of surface coal handling facilities was a relatively simple task. Equipment consisted principally of conveyors, screens and crushers of comparatively simple construction. Electrical equipment consisted of motors and starters, with little, if any, interlocking. In most cases failure of any component affected only the grades of coal loaded so that even a prolonged breakdown did not affect mine operation materially. However, with the introduction of modern cleaning plants, the picture has changed. The equipment is much more complex and therefore more difficult to maintain. In many cases failure of any component of the plant prevents loading of coal. Even if provision is made to bypass, the quality of coal loaded is lowered, affecting markets. In the case of plants designed to permit full seam mining, marketable coal cannot be loaded without operation of the cleaning plant. Under these conditions it is apparent that considerable thought and effort toward better maintenance are justified. In order to assure continuous, efficient and economical operation, maintenance should receive consideration, not only after the plant is in operation, but while it is being designed. It is hardly necessary to say that the designer should strive for sturdi-ness and wearing qualities. It is sometimes not realized, however, that even the best parts will sooner or later require replacement or repair. The designer should, there- fore, give consideration to accessibility. Anyone who has had to do with cleaning plant maintenance is familiar with installations where several hours are required to get at a part that can be repaired or replaced in a few minutes, once it is accessible. As in most cases, experience is the best guide. The men who operate and maintain this equipment know the problems encountered. Whenever available, the opinions of these men should be sought and heeded. As an example, we might consider the refuse elevator on a Chance Cone. Our company is now operating three of these cones, the first of which was installed in 1941, and the latest in 1946. Exact records are not available, but well over 50 pct of delays charged to the Chance Cones have been caused by the refuse elevator. This elevator receives refuse from the cone and carries it to a point above the water level of the cone, discharging onto a dewatering and desanding screen. Since the elevator operates under water and necessarily has close clearances in the lower boot, it tends to jam on large pieces of refuse or tramp iron. The chain, buckets and boot are also subjected to the action of water, sand and refuse, which accelerate normal wear. In case of jamming or chain-breakage it is necessary to drain the elevator and the cone so that even a minor fault in the elevator causes a considerable loss of time for the cone. In our new plant, which will contain two Chance Cones, the refuse elevator has been eliminated. This was accomplished by raising the cone so that the refuse gates could discharge directly onto the dewater-

Jan 1, 1949

By M. H. Cullender

The performance characteristics 01 gas wells producing from formations which fail to stabilize within a relatively short period of time are obscured by the interrelation of the coefficient (C) and the slope "n" of the conventional back-pressure curve q = C(P2 f- p2s)n An empirical method is presented whereby the characteristic or true slope (11) of the back-pressure curve may be determined for a particular gas well. For those gas wells which do not stabilize within a relatively short period of time, the coefficient (C) is considered as a variable with respect to time and as a constant only with respect to a specific time. Thus, the back-presrure performance of such a well is presented as a series of parallel curve5, each curve representing the performance of the well at the end of a given time interval. Through use of the method presented, a simple presture gradient is developed and maintained within the drainage area around a producing gas well during the test period in order that the variation of the coefficient (C) with respect to time does not obscure the true value of the lope. INTRODUCTION The back-pressure method of testing gas wells as set forth by Schellhardt and Rawlins1 is dependent upon the requirement that a series of flow rates and corresponding pressure data be obtained under stabilized conditions. These data arc then plotted on logarithmic coordinates of flow rate (Q) vs difference in squared pressures (P2f — P2s) in order to determine the constants (C) and (n) for Equation 1. With respect to this method of presenting the performance characteristics of a gas well, it should be pointed out that although Equation 1 is an empirical relationship, the form of the equation was justified to a considerable extent by an independent development by Muskat and Botset.2 This development was theoretical in nature; however, certain assumptions with respect to the type of flow existing (viscous vs non-viscous) were madc which may or may not be correct. As the use of the method presented by Schellhardt and Rawlins spread through the industry, it became evident that the method of testing was applicable for those wells which approached stabilized prbducing conditions within a relatively short period of time. Performance characteristics could not be determined by this method, however, for wells which approached stabilized protlucing conditions slowly over a considerable period of time. This characteristic of "slow stabilization" has generally been associated with gas wells producing frorn reservoirs of low permeability. As the demand for natural gas continued to grow through the years, a great number of wells were completed in reservoirs of low permeability which exhibited "slow stabiliz:~tion" characteristics. Consequently, the problem of determining the true performancc characteristics of these wells became more apparent. It is with this problem in mind that the isochronal performance method of determining the flow characteristics of gas wells is presented.

Jan 1, 1956

By C. M. Young

The following paper has been prepared with the object of placing on record in the Transactions some facts concerning the present condition and future prospects of the coal industry of Illinois. In presenting it, the writer wishes to say that a considerable amount of the material contained is taken from the publications and records of the Illinois Coal Mining Investigations, the annual Coal Report of the State Mining Board, and the work of the State Geological Survey. Coal Beds and Mining Methods According to the latest maps of the State Geological Survey, there are only 19 of the 102 counties of the State some portion of whose territory is not within the borders of the coal measures. If outlying areas in Calhoun and Whiteside Counties are considered, the number is reduced to 17. This does not mean that all of the 85 counties that are partly or wholly underlain by coal measures will become producers, as there are some portions of the State in which the coal does not occur in beds of such thickness as to warrant the hope that it can be mined. The mining of coal is widespread, however, for in 1916 there was production from 61 of the 102 counties of the State, There seem to be no cases in which operations will be limited by depth, as none of the coal measures lie at depths much greater than those at which it has been proved that coal may be profitably mined in this field. In fact, the deepest shaft reaching a bed of bituminous coal in the United States is located in this State at Assumption, where coal only 3 ½ ft. (1.07 m.) thick is worked at a depth of 1004 ft. (306 m.). The coal beds occur in the form of a basin which is deepest along a line extending through the central part of the State and bearing a little west of north. The northern, western and southern borders of this basin lie within the boundaries of the State, but on the eastern side the Illinois field is continuous with the Indiana field. The glacial drift covers all except the extreme southern end of the State and the visible outcropping

Jan 1, 1918

By J. S. Marsh

JOSEPH PRIESTLEY prepared oxygen on Aug. 1, 1774, and noted with great surprise "that a candle burned in this air with a remarkable brilliant flame." On Aug. 2, 1774, some ironmaker possibly began to wonder if this substance could be used to increase his rate of production; at any rate, there is no disputing the fact that the notion of using oxygen for steelmaking in concentrations greater than that available in great abundance-as air-has been in existence for years. Action was delayed by the lack of enough oxygen at a cost within reach of the steelmaker. Within the last several years enough has been available to permit large-scale tests of its use for both combustion, with which this paper is concerned, and for decarburization. The literature is now enormous and easily available; it is sufficient here to cite three items of historic- importance in that all are about 25 years old and in that all are remarkably consistent as far as they go, with what is known today.1,2,3 SIGNIFICANCE OF HIGH-TEMPERATURE HEAT The principal 'function of the open-hearth furnace is to supply sufficient, high-temperature heat to melt the charge and then to increase its temperature to a range suitable for tapping, ordinarily in the neighborhood of 2900°F. That heat is required to make steel everybody; however, there seems to be some confusion now and then about the significance of high-temperature heat. Transfer of energy-and heat is energy is always from a point of higher potential to a point of lower potential and, other things being equal, the greater the potential difference, the greater is the rate of transfer of energy. In the open hearth the flame, of course, is the high-potential source. Perhaps the most satisfactory approach is through the notion of theoretical flame temperature; which is the ratio of heat input to the heat content of the combustion products,* the former is composed mainly of heat of combustion of the fuel plus sensible heat of the fuel plus sensible heat of the combustion air. Thus, flame temperature can be increased by increasing the value of the numerator, by decreasing the value of the denominator, or both. The first method is as old as the open-hearth process and, of course, makes use of preheated air; its possibilities have been by no means exhausted. The second method can be put into effect only by changing the composition of the combustion air, since the combustion of a given quantity of fuel produces a definite quantity of product, and since the denominator includes the non-reactive fraction of the air, principally nitrogen. In other words, the denominator consists of the volume of exit gas multiplied by its heat capacity and that volume consists of carbon l is understood by dioxide and water vapor as reaction

Jan 1, 1948

By George H. Ashley

The present critical state of the supply, distribution, and utilization of coal and the necessity for pooling and zoning coals calls renewed attention to the lack of any fully adequate classification of coal. In the past coals have been classified as anthracite, semianthracite, semibitumi-nous, bituminous, subbituminous coals, and lignite, and a few special types, such as splint coal and cannel coal. But under the term bituminous coal are included a great variety of coals differing markedly both physically and chemically. The term subbituminous coal covers as great a range of chemical differences. In order to distinguish these varieties of bituminous coals it has been customary to designate coal by names derived from the place where mined, or by the name of the bed from which it is mined. Thus, in the market reports, coals are quoted as Pocahontas coal, New River or Sewell coal, Moshannon coal, Ohio coal, Williamson County coal, Jellico coal, and so on indefinitely, no limit being set as to the boundaries of the area to which a given name is applied. Nor is there any scale by which the coal from one place may be compared with the coal from some other district or some other bed. On the one hand, coals from the same district may be quite distinct and sell at very different prices or coal from the same bed may differ greatly in different districts; on the other hand, coals from different states may be so similar physically and chemically that one could replace the other in practical use without any appreciable difference in service. The following classification, arrived at after a careful review of a large number of systems of classification and of all of the recognized characteristics of coal, brings together all coals that so nearly resemble each other physically, chemically, and in heating qualities that any coal of a given type could replace any other coal of the same type and grade in use. Thus, if coals A and B are classed as of the same type and grade they have, so far as known to the writer, approximately the same heating value when burned under the same conditions, and the same character, length of flame, and properties affecting transportation and stocking; and if of the same grade, approximately the same percentage of impurities.

Jan 1, 1920

By Theron Wasson

The discovery of two new fields—the Reed City area of Osceola County and the Headquarters field, of Roscommon County —and the important development in Winterfield township, Clare County, again demonstrate the fact that it is the unknown and unexpected that enter very definitely into the oil-producing history of Michigan. This is particularly true in the area of thick glacial drift in the north central part of the state, where the new prolific fields have been discovered this year. This shifts the interest from the southwestern part of the lower peninsula, where a number of pools were rapidly developed during 1939 and 1940, back into the Central Basin area. As a result of strict proration in the new areas, the production for the state of Michigan for the year has not been as great as in 1940 or 1939. In 1941 the total production was 16,300,000 bbl., in 1940 it was 19,551,000 bbl., and in 1939, which was the peak year, it was 23,300,000 bbl. However, the discovery of the new fields this year nearly doubles the estimated reserves for Michigan reported at the end of 1940 In 1941 about 12,000,000 bbl. of oil was produced from the older fields, in which the individual well productions were so small that proration was not an important factor. The total production for the state from the discovery of oil in 1925 through 1941 now stands at 161,205,000 barrels. ActIVe Oil Fields Reed City Field.—In the Reed City field, Lincoln township, Osceola County, only small oil wells were completed during 1939 and 1940. The discovery of much larger production in wells drilled somewhat deeper, by The Pure Oil Co. and the Weber Oil Co., in the early part of 1941, led to the rapid development in this area. Some wells have had initial productions as high as 10,000 bbl. By the end of the year III producing wells were completed, with an average depth of 3600 ft., from the Detroit River formation of Devonian age. The entire development of the field to the end of 1941 was on 20-acre spacing. Headquarters Field.—The Headquarters field, which lies along the line between Clare and Roscommon Counties, was one of the most important discoveries of 1941 and will be the scene of vigorous development during 1942. Production so far has been from the Traverse lime at about 3400 it., and development has indicated that this is probably one of the most productive Traverse pools yet discovered. One well had been given a potential of 10,000 bbl. per day. Dry holes well located in relation to big producers indicate that it is a typical Traverse development. Winterfield Field.-This field, in Winter-field township, Clare County, was discovered late in 1940. By December 1941, 14 Dundee and 5 Traverse producers had been completed. The Dundee lime is found at a depth of 3750 it. and the Traverse lime at 3070 it. Producing conditions in the Dundee seem to be erratic because of varying porosity in the dolomit-ized limestone. Kawkawlin Field.—The Kawkawlin field, which was discovered by the Gulf Refining Co. in 1938, is in Monitor and Kawkawlin townships, Bay County. Small production

Jan 1, 1942

LIBERIAN ore has been called the richest iron ore mined in the world, and thus far, the output from the Liberian Mining Co.'s Bomi Hills mine has lived up to its reputation. Iron content has been variously given as 68.47 pct to 68.825 pct. A recent United Nations survey gave it first place, surplanting the previously top-rated Swedish product. The first shipment of Liberian ore to the United States reached Baltimore in June, 1952 and went into blast furnaces at Republic Steel's Cleveland plant, where excellent results were reported. The physical make-up of the ore was hard, dense lumps, free of fines and with ideal size distribution. The Bomi hills mines were scheduled to be in full operation by the end of 1952. At the close of 1951, 200,000 tons of ore had been delivered to Baltimore. Liberian Mining Co. states that production is about 90,000 tons of ore per month at present. Between 1200 and 1500 men are employed at the mine site, with about 25 pct of them Americans. The Bomi Hill project was financed with the aid of the Export Import bank, which loaned Liberia Mining part of the sum needed to initiate and put the development into production. No definite expansion plans are in the making but extensive diamond drilling is being pursued. Original estimates of annual production for Bomi Hills ran in the neighborhood of 1.5 million tons, but the figure is no longer applicable. Liberia's potential as an iron producing country has been known for a long time, but the physical obstacles in the way of large scale production were such as to prohibit even contemplation of the project. Until recent years, the only route from the mine site to Monrovia was a foot trail. Once to the coast, over swamps and unbridged rivers, the ore was still useless because of the lack of loading facilities. Transportation Solved One problem was solved with the completion of the artificial harbor at Monrovia. Harbor construction was well under way when the mine project began in 1948. The island location of Monrovia also made the building of a bridge across the St. Paul River necessary. The 980 ft reinforced concrete structure, accommodating railroad and vehicular traffic, was opened in 1949. Meanwhile, preliminary work on railroad construction started. Grading was completed quickly. In April, 1951, the first train made the trip from Monrovia to the Bomi Hills. About half of the cost of the entire project went into railroad construction. More than 2200 men, often forced to resort to primitive methods, were engaged in clearing a path through the heavy forests between the mine and port. Swamps were drained and filled, and bridges, including the William V. S. Tubman, named for the Liberian President, were constructed. At the port, a Robbins Conveyor Belt Co., orehandling plant was installed. Ships can be loaded from the stockpile at the rate of 3000 tons per hr and vessels need spend only one day in port. Liberian Mining is operating under an 80 year lease, giving the company exclusive mining rights to all minerals, except gold, platinum, and diamonds, within a 40 mile radius of Bomi Hills. The contract provides a fixed royalty to the Liberian Government of five cents per ton of ore extracted, and a premium -based on the New York market price for Bessemer-grade pig iron. The entire project started because an American,

Jan 1, 1952

THE Annual Fall Meeting held in Chicago in conjunction with the celebration of a Centennial of Engineering brought forth a round of field trips and symposiums which did much to add to the store of information of the 240 who registered for the gathering. Instead of a scattered program, technical papers were grouped together in organized symposiums, where the particular importance of each report was enhanced by presentation in context. Despite the heavy accent on technical papers and informative field trips, those attending the meeting had ample time to enjoy the benefits of a visit to Chicago. The AIME dinner dance was held at the Palmer House, in the Red Lacquer Room. The Chicago Section played host Friday evening at dinner. The MBD held four sessions at the meeting headquarters, the Palmer House, September 4 and 5. Featuring the meetings was a review of taconite concentration and new theories on comminution. The first session opened with a paper on the Structural Features Which Effect the Concentration of Iron Formations, presented by F. J. Tolonen. The paper was centered upon the various members of the low grade iron formations of the separate Michigan districts. The study correlated macrostructure, microstructure, and concentration tests. [ ] Beneficiation Characteristics of Michigan Low Grade Iron Ores, presented by F. X. Tartaron, cochairman of the session, reviewed the work of his laboratory on the beneficiation of low grade ore taken from various strata of a deep shaft on the Marquette Range. The paper included data on flotation, gravity separation, magnetic separation, and combinations of these processes. The economics of low grade ore treatment generated great interest. Ty. Maki offered a compilation and correlation of field results with magnetic separators in ferrosilicon and magnetite medium recovery circuits. Following the morning session, 130 persons attended a luncheon, followed by a brief business meeting. Later, a film illustrating the grinding, separation, and pelletizing steps investigated by the Mines Experiment Bureau, was presented by H. H. Wade. T. E. Ban, and L. J. Erck gave a report on pelletizing which evoked much discussion. R. A. Limons presented a paper on the Mineralogy of Blast Furnace Sinter, for its author, H. M. Kraner. Friday sessions featured a new hypothesis for high speed drill rod milling and a new technical approach to comminution. Jack Myers commented that Consolidated's large rod mill was a hammer mill turned inside out. Steve Erickson described the use of Cyclones for Heavy Media Concentration of Iron Ore Fines. Bob Meaders gave a Progress Report on the Aerofall Mill. Shiou-Chuan Sun described an improved high frequency analyzer for studying the conductivity of suspensions of various minerals. L. A. Roe discussed a magnetic reflux condensor which enabled him to determine the degree of liberation of magnetic iron ores. Roy A. Johnson described a function of the hydroscilator in which the fan rake was eliminated in favor of a conical bottom. The Industrial Minerals Division sessions held September 5 and 6 and were well attended. The Friday morning session was particularly concerned with developments and advances in industrial minerals with special emphasis on the Chicago area. The first two papers dealt with transportation on the Great Lakes and fuel movement into the Chicago area. The third paper proved to be of great interest, turning the spotlight on the fairly new hydraulic mining methods introduced by a silica company in the Ottawa, Ill. field.

Jan 1, 1952

By V. N. Mackiw

IN the process employed by Sherritt Gordon Mines Ltd. for the production of metallic nickel, a sul-fide concentrate is leached with ammonia and air under pressure. Following the removal of iron, copper, and other impurities, there remains a purified solution having the following analysis: 40 to 50 g per liter Ni, 200 to 400 g per liter (NH4)2 SO 4, and 20 to 30 g per liter NH3. Metallic nickel is reduced from this solution by hydrogen under pressure at 300' to 350°F in mechanically agitated autoclaves. A catalyst, ferrous sulfate, is required to initiate the first reduction. After the reduction, the depleted solution is discharged, leaving the metallic nickel in the autoclave. The nickel produced, being in a finely divided form, is used as a catalyst for the reduction of the next batch of solution. Upon repeated use the metallic nickel particles increase in size and become more compact, resulting in the production of a powder with higher apparent density. For this reason, each reduction is termed densification. Finally, when the burden of metal powder in the autoclave becomes too great to obtain effective agitation, both powder and depleted solution are discharged. The autoclave is then filled with fresh solution, ferrous sulfate catalyst added as before, and a new cycle started. The operation is described in earlier publications.1-6 A comprehensive historical review of the reduction of metals from solutions in general was given in a paper by Schaufelberger.7 The experimental data presented in this paper were taken from the work done in the Research Laboratory of Sherritt Gordon Mines Ltd. in Ottawa during the development of the process in 1951 and 1952. The results of the work were tested on a pilot plant scale in Ottawa in the period 1952 to 1953. Following laboratory and the pilot plant studies a commercial process has operated successfully since 1954 in the Nickel Refinery of Sherritt Gordon Mines Ltd. in Fort Saskatchewan, Alberta. General Experimental Technique The experiments were carried out in a stainless steel, 1-gallon, agitated autoclave designed and manufactured by Autoclave Engineers Inc. The inside dimensions of the vessel were 5 in. diam and 12 in. depth. The stirrer consisted of a 1/2 in. diam shaft 11 in. long fitted, with an axial flow type impeller (three blades bent to throw downwards) and a radial flow

Jan 1, 1958