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By W. F. Kieschnick, C. C. Miller, E. R. Brownscombe

The possibility has been mentioned that large pressure gradients in a solution gas driven field caused by high production rates might lead to a reduction in the ultimate recovery obtainable compared to that which would be obtained by a very slow rate of production. In the present study the reservoir conditions accompanying a high rate of production and the corresponding ultimate recovery were compared with those obtained if the reservoir were produced at some marginal rate throughout its entire life. The method of calculation involved the application of fluid flow - material balance analysis to a series of successive steady state conditions in the reservoir. In the case studied very little difference in recovery was obtained at the abandonment pressure. An analysis of the basic factors involved indicates that the sane results would hold for considerable variation in properties of reservoir fluids, permeability of the formation or well spacing. Even if the reservoir has a water drive it appears that no harm will be done by- open flow production if the rate is cut back before any appreciable free gas is produced. However, any condition which leads to disproportionate withdrawal rates and which causes large pressure differences over large areas might result in substantial loss in ultimate recovery. INTRODUCTION When the pressure declines in a reservoir, gas is evolved from solution causing a shrinkage in the reservoir oil so that a stock tank barrel of oil with its residual dissolved gas occupies a smaller volume than originally. For a given reservoir oil saturation, therefore. stock tank oil content will be higher at the lower pressure. At the same time the evolved gas which remains in the reservoir reduces the reservoir oil saturation, and this would be expected perhaps to cause a reduction in stock tank oil content. However, around the well the shrinkage occurs so rapidly that stock tank oil may actually accumulate in this region in spite of the simultaneous reduction in reservoir oil saturation. If this accumulation should continue, spreading into a larger zone, the loss might be appreciable and because larger pressure gradients accompany higher rates the accumulation might possibly be large if wells are produced at too high a rate. It is the purpose of this paper to determine the effect of rate of flow on ultimate recovery by solution gas drive. The problem under consideration involves the unsteady state flow of oil in a closed radial system from which oil is produced by the evolution of gas as a finite drawdown is estalllished and the reservoir pressure declines. A somewhat similar unsteady state production problem dealing, however, with a linear system has been considered by Muskat and Meres, but these authors do not discuss the effects which rate may have on recovery. Other methods have been reported for estimaling recovery as a function of pressure decline when producing at an infinitesimal rate, and Muskat and Taylor' have shown the effect of fluid and reservoir characteristics on recovery under these conditions. Assuming steady state to exist, Babson has given a procedure for computing the decline in well productivity as the field is depleted, and Moyer has combined these methods to estimate abandonment conditions and the resulting ultimate recovery. These latter approaches to the problem either do not consider the effect of rate or assume steady state can be established. In detail this paper presents the behavior of the reservoir producing under unsteady state conditions and considers the effect of production rate during this unsteady state flow on the recovery attained. The analysis also shows that there will exist at abandonment a type of steady state, and on this basis a method has been clevelopetl for rapid calculation of abandonment conditions.

Jan 1, 1949

By C. C. Miller, W. F. Kieschnick, E. R. Brownscombe

The possibility has been mentioned that large pressure gradients in a solution gas driven field caused by high production rates might lead to a reduction in the ultimate recovery obtainable compared to that which would be obtained by a very slow rate of production. In the present study the reservoir conditions accompanying a high rate of production and the corresponding ultimate recovery were compared with those obtained if the reservoir were produced at some marginal rate throughout its entire life. The method of calculation involved the application of fluid flow - material balance analysis to a series of successive steady state conditions in the reservoir. In the case studied very little difference in recovery was obtained at the abandonment pressure. An analysis of the basic factors involved indicates that the sane results would hold for considerable variation in properties of reservoir fluids, permeability of the formation or well spacing. Even if the reservoir has a water drive it appears that no harm will be done by- open flow production if the rate is cut back before any appreciable free gas is produced. However, any condition which leads to disproportionate withdrawal rates and which causes large pressure differences over large areas might result in substantial loss in ultimate recovery. INTRODUCTION When the pressure declines in a reservoir, gas is evolved from solution causing a shrinkage in the reservoir oil so that a stock tank barrel of oil with its residual dissolved gas occupies a smaller volume than originally. For a given reservoir oil saturation, therefore. stock tank oil content will be higher at the lower pressure. At the same time the evolved gas which remains in the reservoir reduces the reservoir oil saturation, and this would be expected perhaps to cause a reduction in stock tank oil content. However, around the well the shrinkage occurs so rapidly that stock tank oil may actually accumulate in this region in spite of the simultaneous reduction in reservoir oil saturation. If this accumulation should continue, spreading into a larger zone, the loss might be appreciable and because larger pressure gradients accompany higher rates the accumulation might possibly be large if wells are produced at too high a rate. It is the purpose of this paper to determine the effect of rate of flow on ultimate recovery by solution gas drive. The problem under consideration involves the unsteady state flow of oil in a closed radial system from which oil is produced by the evolution of gas as a finite drawdown is estalllished and the reservoir pressure declines. A somewhat similar unsteady state production problem dealing, however, with a linear system has been considered by Muskat and Meres, but these authors do not discuss the effects which rate may have on recovery. Other methods have been reported for estimaling recovery as a function of pressure decline when producing at an infinitesimal rate, and Muskat and Taylor' have shown the effect of fluid and reservoir characteristics on recovery under these conditions. Assuming steady state to exist, Babson has given a procedure for computing the decline in well productivity as the field is depleted, and Moyer has combined these methods to estimate abandonment conditions and the resulting ultimate recovery. These latter approaches to the problem either do not consider the effect of rate or assume steady state can be established. In detail this paper presents the behavior of the reservoir producing under unsteady state conditions and considers the effect of production rate during this unsteady state flow on the recovery attained. The analysis also shows that there will exist at abandonment a type of steady state, and on this basis a method has been clevelopetl for rapid calculation of abandonment conditions.

Jan 1, 1949

By Fred A. Anderson, George B. Wallace, Edward J. Slebir

Auburn Dam will be a thin, double-curvature concrete arch dam about 685 ft high. With a crest length of about 4000 ft, it will be the world's longest single-arch dam. The site is located on the North Fork of the American River about 40 miles northeast of Sacramento, Calif. Construction is scheduled to get under way in 1970. In planning for the design and construction of Auburn Dam (see artist's conception), the foundation material, with its various discontinuities, is being investigated and the structural characteristics of the rock mass evaluated. The investigation and testing programs will aid in defining the pertinent geologic features and their individual and cumulative influence on the foundation. The work includes geologic surface mapping, surface trenching, core drilling, geophysics, tunneling, excavating shafts and raises, performing in-situ tests, and conducting laboratory tests on core and block samples. Competent amphibolite is the predominant material in the foundation, but significant bodies of chloritic, talcose, and metasedimentary rocks, a strongly developed jointing pattern, faults, and shear zones also affect the deformability of the rock mass. A comprehensive rock mechanics program, closely coordinated with geologic investigations as well as the engineering studies, therefore is required The rock mechanics work is a combination of many analytical studies and experimental investigations. The experimental work includes laboratory tests on core samples from holes drilled for geological studies of the entire foundation and in-situ tests performed in selected areas. The laboratory testing program evaluates the general properties of all important rock types and aids in correlating many of the key structural features encountered within the foundation. To derive maximum benefit from the field tests, they are conducted in materials which represent a

Jan 1, 1970

By James Norman

DIATOMACEOUS earth occurs in deposits widely distributed throughout the nation. The chief producing areas are in the Western States, where many high-grade deposits are known. Eastern deposits of diatomite are unsatisfactory for many purposes either because of impurity or because of the extremely fine particle size. Eastern users of diatomite, on the whole, must pay for transportation of the material from the west coast. The freight rate is necessarily high because of the great bulk of the diatomite. A satisfactory process of purifying the diatomaceous earths of Maryland and Virginia, which are unsuited for wide use only because of impurities, should be of value to eastern users. In the past, benefication of diatomite by wet processes has been limited to classification or sedimentation for the removal of sand from diatoms. Calcination with salt is used to produce a white diatomite when iron is present in the impurities, and small amounts of clay are rendered inactive in the process. No treatment has been developed whereby a large proportion of clay can be removed from a low-grade diatomaceous earth to give a diatomite of very high purity. In August 1937 the Federal Bureau of Mines, in cooperation with Dr. R. C. Williams, of Baltimore, undertook the problem of purifying low-grade Maryland diatomite by froth flotation. Work was done at the Eastern Experiment Station, College Park. Unless otherwise stated, the crude diatomite used was from the Patuxent River deposits near Dunkirk. This material, consisting of roughly one-third each of clay, quartz sand and diatoms, was representative of the usual low-grade marine diatomite found in the Coastal Plain Miocene beds of Maryland and Virginia and sporadically in other Atlantic coast states. As received, it contained 50 to 60 per cent moisture and probably had been wet since its formation.

Jan 1, 1940

By J. Ruzicka

In creep testing, material is subjected to a constant load, preferably at a constant temperature, and its rate of deformation is measured. The method of loading can be of various types but in this paper only creep testing under tensile load will be considered. The ordinary tensile test is essentially a comparison test in conditions that frequently hear little or no relation to those under which the test material is to be used in service. The purpose of creep tests is to measure the strength of the test material at slow rates of deformation that more nearly approach the rates realized in service. One purpose of this paper is to illustrate that the creep test, in addition to its value as a service test, is superior to the ordinary tensile test as a sensitive tool for the comparison of certain metals in investigative testing. The other purpose is to describe equipment having distinctive features of design that make it especially suitable for such tests. Representative data obtained with this equipment on a group of rolled zinc-base materials are given. These data are compared with those from practical comparison tests of the creep type on weatherstrip fabricated from the same group of materials. The comparison illustrates the value of the fast creep test and of the equipment. The Equipment The creep equipment consists essentially of a tank containing a constant-temperature oil bath in which the creep of 14 specimens, loaded by means of levers, is measured by means of one movable extensometer. Figs. 1, 2 and 3 illustrate its general construction and appearance. Constant-temperalure Oil Balh.—A common constant-temperature bath requiring only one temperature-controlling equipment for a number of specimens was chosen as the best means of fulfilling the requirements of low cost and compactness. In addition, this allows the testing of a group of specimens under identical temperature conditions.

Jan 1, 1937

By John Birkinbine

In all metallurgical processes and mining operations, water is an element which receives attention from the management; and provision is required either for a means of supply, or for the disposal of accumulation. In many works the quantity of water to be furnished is sufficiently large to place the item of water supply of equal importance to the reception of material or disposition of product; and the means to be employed receive, or should receive, the most careful investigation. There are exceptional cases where mines or quarries possess a natural drainage, but a large majority of the useful ores and the fuels delved from the earth are obtained from workings in which water accumulates and .must be removed. Often the quantity to be

By James W. Baxter

Underground mining of limestone is becoming increasingly practicable in Illinois. Most quarries are near rivers on the western and southern borders where competition for land use is intensive. Increasing demands for stone can be met by expanded mining with access by adits in existing quarries and by inclines and shafts at downdip sites. Geologic, hydrologic, and engineering conditions indicate that deep mines in the Ste. Genevieve, Salem, Ullin, and basal Burlington limestones of Mississippian age and in the Moredock member of the Dunleith formation of Ordovician age are particularly feasible, but development will require prudent exploration and planning to ensure that the product will be of good quality.

Jan 1, 1981

By C. R. Taylor, John Chipman

THE study of chemical reactions of liquid steel and basic open-hearth slag involves a complex slag system of at least eight important components, and often a number of others. In initiating an experimental program on the equilibrium relationship of slag and metal, it became evident that but little progress could be expected in the interpretation of the complex slags until an understanding had been gained of the simpler liquid systems composed of a limited number of slag constituents. The simplest system that in any way resembles open-hearth slag must contain lime, silica and iron oxide. Attempts to produce in an induction furnace slags containing only these constituents have met with serious limitations because of the solubility of refractories in the slag. Thus in acid-lined furnaces the slag is always saturated with silica and consequently contains between 48 and 63 per cent of this component. In basic-lined furnaces an undesired additional component, magnesia, is introduced to the extent of some 3 to 15 per cent, depending upon the acidity, sometimes with disastrous results to the furnace. Thus in a magnesia-lined furnace, Fetters and Chipman1 found it impossible to prepare slags in which the ratio (CaO + MgO)/SiO2 was less than that corresponding to the metasilicate (approximately 0.8: I). Between this composition and that of the true acid slags lies a field of composition about which very little is known and which cannot be explored by any ordinary means. This circumstance, as well as the desire to study the more basic slags in the absence of magnesia, calls for the development of a method by which slags may be brought into equilibrium with molten metal without coming in contact with refractory. Such a technic has been provided by the rotating induction furnace developed by Barrett, Holbrook and Wood.2 Three modifications of the rotating furnace were described by these authors. The first was essentially a rotating refractory cylinder containing the magnesia crucible, which was itself heated by a graphite crucible. In the second, only the magnesia crucible rotated, the cylindrical graphite heater being stationary. In the third, the coil and crucible revolved, and the metal was heated directly by induction. EXPERIMENTAL METHOD Furnace The furnace used in this investigation differed from previous designs and may be considered a fourth modification of the original rotating furnace. Its essential features are shown in Fig. I. The outer case A is a fire-clay flue liner for control of the atmosphere. The top B and base C are alberene stone. The coil supports D are of "Formica," a material formed from phe-

Jan 1, 1942

By Richard R. Parizek, E. Scott Blair

Numerical modeling of ground water flow systems can be used to help analyze many practical problems encountered in the mining industry. Numerical models can be used to predict ground-water seepage rates into surface mines, shafts, and other large excavations; to predict water-level changes under adjacent properties; and to predict the effectiveness of various deep-well dewatering schemes. As with any model, the results from a numerical model are limited by the quality and quantity of data, and by the restrictions of any simplifying assumptions. A case study is presented that shows how a numerical model was used for engineering purposes to help analyze the hydrologic impact of a proposed open-pit mine by Predicting changes in the dewatering rate caused by the lateral growth and deepening of the mine and by predicting the effectiveness of various deep-well dewatering schemes.

Jan 1, 1982

By G. Koves

The behavior of case-hardened AISI C-1213 free -machining steel under complex impact-fatigue -wear load conditions was investigated. The inherently poor dynamic properties of the steel are mainly affected by the stress distribution in the case, component shape, and tempering. Cold-riveted components showed unexpectedly high dynamic strength compared to basic parts. A compromise beatment—which provides good dynamic properties, reasonable wear resistance, and fair riveting characteristics—zuas developed. A number of mechanical components in data-processing machines are made of free-machining carbon steel. Although, selected primarily due to manufacturing requirements, components made of these grades frequently undergo complex heat treatment and must sustain impact-fatigue loads. A typical free-machining steel is the AISI C-1213 grade, which is a resulfurized and rephosphorized open-hearth steel. While the undesirable effects of sulfur and phosphorus on the mechanical properties are well-known, data on dynamic properties are scarce.1"3 Rapid rotating or oscillating motion while carry- ing a high cyclic load requires a combination of wear resistance with high endurance limit and impact toughness. The inherently poor dynamic properties of the free-machining steel are further degraded by the machining, which introduces local stress-concentration areas. While the heat treatment (usually case hardening) improves some mechanical properties, it necessarily impairs others. Another problem arises when components, such as studs, must be fastened by riveting. The high crack-sensitivity of the free-machining steel, especially in the presence of a hardened case, makes this operation difficult. In view of the preceding considerations, it is of interest to investigate the behavior of a typical component under complex impact-fatigue-wear loading conditions in order to explore the effects of material, machining, and heat treatment, to obtain specific data on the dynamic characteristics of free-machining steel, and to arrive at a process which would adequately utilize the inherent qualities of this material. EXPERIMENTAL PROCEDURE To simulate actual service conditions, a typical component was selected, based on frequency of application, complexity of load, and processing difficulties. The dimensions and shape of the component—a stud used in many electromechanical document-handling machines—are shown in Fig. 1.

Jan 1, 1964

By E. W. Edson, F. W. Hertal

In some fields the problem of mud fluid is simple and easy of solution. But in the Ventura Avenue field the acquisition and disposal of good drilling mud is not the least of the problems that confront the operator. In fact, mud fluid in the Ventura Avenue field is a very important factor in the drilling of the wells. It is quite probable that many of the factors affecting mud in this field will not be found in most of the fields with which the reader is familiar. However, in the fields where the mud fluid causes no apparent problem it is probable that some of the points brought out in this paper could be used to economic advantage. In fields where caving and squeezing formations and high gas pressures are present, as in the Ventura Avenue field, it is believed that application of methods outlined will be of great assistance in drilling wells. On account of the sandy nature of the formation and the lack of suitable shale bodies in the strata drilled through in the Ventura Avenue field, the wells make practically no mud during drilling. It is necessary therefore to supply drilling mud to the wells that will carry the drill cuttings to the surface, and also will " wall up" the drill hole and prevent the sandy formations from caving. Mixing and Handling Mud Fluid The clay used to make the mud fluid is obtained from a shale stratum in the upper Pico (Plioccne) formation found about a mile on either side of the field. Since high gas pressures and caving formations were first encountered in the Ventura Avenue field and mud fluid was needed to combat them, the mixing of this mud fluid has gone through a process of evolution. First, the clay was mined and hauled to the derrick, where it was shoveled into the well and left for the churning action of the bit to mix into a mud in the hole. The next move was the construction of a mixer to mix the clay to a mud fluid which was pumped into the well. These mixing

Jan 1, 1930

In 1846 a bill was pending in Congress to reduce, or eliminate, the tariff on coal; the debate caused the same writer to visit the mines on the north side of the James River and to write a letter about them to the same paper.' Omitting the political arguments, his account follows: "July 13, 1846. "Early in the morning we rose, washed, combed, and ate a first-rate breakfast, and then went to the Tuckahoe, mined by Messrs. Sneed and Dietrock. Coal was first discovered here sixty years ago, and mined by Colonel Thomas Randolph, the proprietor of the land. They were worked by him for his smith-shops. Since which time they have been worked periodically, up to the war of 1812, when they were abandoned; and recommenced in 1837 under the management of Dr. W. T.- Scott. Subsequently a Company was formed called Tuckahoe Coal Mining Company, which purchased the whole track at a cost of $30,000. They commenced the sinking of a shaft and went as far as 412 feet, and then pitched the fat all into the fire by hauling off altogether in despair. In 1843 Major Sneed went to work at it, and succeeded. I may here remark that Major Sneed has been the pioneer in this business on the North side of the River, and has sunk more shafts than any other man who has pursued this vocation in Eastern Virginia. The difficulties and expense in sinking these shafts are sometimes immense. The coal on the outcrop or surface is not always a guide to where it may be found imbedded many hundred feet under earth and rock. "The Tuckahoe Pits are on the Eastern end of the coal field, within twelve hundred yards of the Canal, and about twelve miles from Richmond. They employ fifty hands and raise some three hundred thousand bushels of coal per year. It is highly bituminous and excellent for the manufacture of iron. The Tredegar and Belle Isle Rolling Mills are supplied with it. It must be good and of the right kind', or they would not use it. These pits are the only. ones on this side troubled-with gas-of course ventillation is necessary. There is not as much water in this Pit as I have found generally in many others, although they have extended their operations to a considerable distance under ground. I have observed in examining the coal mines, that, where they are sunk over four or five hundred feet, they are annoyed by gas, and where there is a less depth they are troubled with water. It is evident, therefore, that water, in the region of these coal fields, does not run through the earth to any extent, even five hundred feet deep, and the farther you go below that the greater the increase of gas. "We next visited William Cottrell's Pits, situated one mile and a half north of this. He employs some thirty hands, and raises from 4 to 500 bushels per day. "T. & R. Crouch's Pits are one hundred yards north of Cottrell's. This firm employ from 80 to 90 hands, and raise from 8 to 900 bushels per day. They are now

Jan 1, 1942

By Henry Carlisle

Henry Carlisle: This is November, 1960, and my good friend John Gustafson is sitting on the other side of a tape recorder. I, Henry Carlisle, am going to ask him some questions on the highlights of his life, and he has been good enough to say that he will play this question and answer game with me. Now, John, let's pick out a very interesting period when you went to North Labrador and made a preliminary investigation of the big iron deposits there. You were working for either Timmins or Hollinger, which was it? John K. Gustafson: I was in charge at that time of a Hollinger Exploration Co. office in Toronto. We had acquired options on enough shares to control Labrador Mining and Explorations Co., and through Hollinger North Shore Ltd., another company, we had a 3000 square mile concession in Ungava, Quebec, on the direct extension of the iron ore fields.

Jan 7, 1972

By James B. Cathcart

Marine phosphorite deposits occur in Braxil, in the Bambui Group of late Precambrian or Early Cambrian age. The phosphorite is laminated, isoclinally folded, and is composed of black, elongated apatite pellets and quartz grains cemented by quartz and muscovite. Abundant, narrow quartz veinlets cut through the .rock at right angles to the elongation direction of the pellets. The phosphorite is 0 to 80 m thick and contains 5 to 30 percent P2O5. The deposit is elongate towards the northeast, and the central, thickest, and richest part is bounded by faults. Measured reserves are about 250 million tons that average a bout 13 % P205. Preliminary testing indicates that grinding, scrubbing, and desliming will produce a material usable for fertilizer manufacture at a cost competitive with imported phosphate fertilizers.

Jan 1, 1979

NEW MEMBERS The following list comprises the names of those persons who became members during the period Sept. 10 to Oct. 10, 1914: Members ALLEN, MILTON A., Min. Engr., Alaska Gastineau Mining Co., Juneau, Alaska. ALLPORT, ROBESON H., Gent Supt Colonial Coal & Coke Co., Dorchester, Va. ALSDORF, FREDERICK C.... Murray Apartments, 1026 Orange St., Los Angeles, Cal. ANDERSON, CARL A., Min. Engr 920 Wooward Ave., Portland, Ore. ARMS, CHARLES SEELYE, Asst. Met Willys-Overland Co., Toledo, Ohio. BAILEY, PHILIP P., Min. Engr McGill University, Montreal, Canada. BECK, CHARLES SMITH, Engr Detroit Copper Co., Morenci, Ariz. BEESON, ALEXANDER G., Chief Engr., Pittsburg-Buffalo Co. and Four States" Coal & Coke Co., Washington, Pa. BINGHAM, RAYMOND A Box 173, Bridgeport, W. Va. BJORGE, Guy N., Geol., Old Dominion Copper Mining & Smelting Co.,. Globe, Ariz.

Jan 11, 1914

By T. L. Joseph

Sulfur balances calculated from operating data covering thirty-five blast furnaces indicate that approximately 92 per cent. of the total sulfur charged enters with the coke, 7 per cent. with the ore, and 1 per cent. with the stone.. Most of the sulfur is carried from the furnace by means of the slag, the total amount eliminated being the product of the slag volume and the percentage of sulfur it contains. Additional sulfur in the charge must be eliminated either by increasing the percentage of sulfur in the slag or the quantity of slag. From relations found between slag volume and coke consumption and sulfur in the coke and slag volume, curves have been prepared showing the relative value of blast-furnace coke as its sulfur varies from 1 per cent. CHARCOAL was the predominant blast-furnace fuel until 1838, when it was found, by the operation of a 2-ton experimental furnace, that anthracite could also be used. This information was a stimulus to the iron industry, particularly in eastern Pennsylvania where anthracite was available at low cost. The production of anthracite pig iron increased steadily and, in 1855, its tonnage exceeded that of charcoal iron. Of the 680 furnaces in operation in 1874, the 226 using anthracite produced nearly one-half the total tonnage. In 1869, the production of coke furnaces exceeded that of charcoal furnaces and, in 1875, coke surpassed anthracite as a metallurgical fuel. In 1907, the output of anthracite pig dropped well below a million tons and its present significance is largely historical. In recent years, the production of coke has gone hand in hand with the production of pig iron and it has gradually attained the position it now occupies as a universal blast-furnace fuel. Charcoal, however, has great merit as a blast-furnace fuel chiefly because of its freedom from ash and sulfur. The harmful effect of the latter and the necessity of keeping the percentage of this element in pig iron at a minimum are well recognized. Other contaminating elements can be reduced to specified limits in the steelmaking process, but the control of sulfur belongs essentially to the blast furnace. The purpose of this paper is to point out the distribution of this impurity in blast-furnace

Jan 9, 1924

By H. W. Kropholler, L. A. Cramer, E. T. Woodburn, J. C. A. Greene

A generalized mathematical structure is proposed whereby internal species mass flows within a flotation network are defined uniquely by a matrix of enhancement factors. An element of the enhancement factor matrix is defined as the ratio of the mass flow of that species leaving a given cell in the concentrate to the species mass flow leaving the same cell in the tailings. To predict the enhancement factors, knowledge of flotation kinetics effects is required. Recently experimental data has become available relating to the performance of industrial flotation circuits which indicate that the discrete or discrete-distributed kinetic schemes are capable of reasonably effective simulations. These simulations show the importance of including froth effects. The prediction of performance of networks from small-scale batch tests on flotation streams shows that the model for the froth phase used in the simulations does not scale-up well and that aeration effects are also difficult to predict. The network analysis should be useful in differential flotation of complex ores and it is disappointing-in this context that little information on the kinetics of activation and depression is available.

Jan 1, 1976

By E. P. Shoub, J. P. Riott, R. C. Buehl

Pilot-plant tests have demonstrated that it is possible to produce low-sulphur sponge iron (0.03 to 0.0; per cent sulphur) as a continuous process in an internally fired rotary kiln from iron ore or mill scale; a solid carbonaceous reducing agent; and dolomite to control the sulphur content. The proportion of dolomite employed is small, so that it does not add materially to the cost of the sponge iron. The entire operation is carried out at temperatures well below the melting point of iron, so that the product is discharged in granular form. Compared with other methods for the production of sponge iron, the rotary-kiln method has the advantage of simplicity and low cost of equipment and, in addition, requires little labor for the operation of the process. The pilot-plant equipment used for this work was sufficiently large to demonstrate that the production of low-sulphur sponge iron in rotary kilns is feasible and that the costs are not excessive for applications in which sponge iron has distinct advantages over competing materials. This report constitutes a part of a program by the Bureau of Mines under a special Congressional appropriation for studying gaseous and solid fuel reduction of iron ores. Numerous articles on various phases of these investigations have appeared in Bureau of Mines publications or technical journals. Other articles are being prepared and will be published in the near future. The present program, which is under the supervision of Dr. R. S. Dean, Assistant Director of the Bureau of Mines, was initiated in 1942. However, a considerable portion of the work was a continuation of previous research performed by the Bureau. Previous investigators1-4 utilizing the rotary kiln for the production of sponge iron did not develop a suitable method for controlling the sulphur content. A review of the literature shows that the sulphur content in the product usually exceeded 0.1 per cent unless reducing agents with very low sulphur contents were employed. This high sulphur value made the product generally undesirable for use as melting stock in electric or open-hearth furnaces. The production of sponge iron in an internally fired rotary kiln has been described in detail in Bureau of Mines Bullelin 2702; consequently, this article will be confined mostly to new features of the process—that is, means for controlling the sulphur content of the sponge iron. Suitable raw materials include iron ores or mill scale; coal or coke for reducing them, and sized dolomite ( — poi-100-mesh) as the sulphur-controlling agent. A mixture of the raw materials in granular form is fed into the elevated end of the kiln, which is fired axially from the lower or discharge end. In the reducing zone, which is approximately one third the length of the kiln measured from the dis-

Jan 1, 1948

By R. C. Buehl, J. P. Riott, E. P. Shoub

Pilot-plant tests have demonstrated that it is possible to produce low-sulphur sponge iron (0.03 to 0.0; per cent sulphur) as a continuous process in an internally fired rotary kiln from iron ore or mill scale; a solid carbonaceous reducing agent; and dolomite to control the sulphur content. The proportion of dolomite employed is small, so that it does not add materially to the cost of the sponge iron. The entire operation is carried out at temperatures well below the melting point of iron, so that the product is discharged in granular form. Compared with other methods for the production of sponge iron, the rotary-kiln method has the advantage of simplicity and low cost of equipment and, in addition, requires little labor for the operation of the process. The pilot-plant equipment used for this work was sufficiently large to demonstrate that the production of low-sulphur sponge iron in rotary kilns is feasible and that the costs are not excessive for applications in which sponge iron has distinct advantages over competing materials. This report constitutes a part of a program by the Bureau of Mines under a special Congressional appropriation for studying gaseous and solid fuel reduction of iron ores. Numerous articles on various phases of these investigations have appeared in Bureau of Mines publications or technical journals. Other articles are being prepared and will be published in the near future. The present program, which is under the supervision of Dr. R. S. Dean, Assistant Director of the Bureau of Mines, was initiated in 1942. However, a considerable portion of the work was a continuation of previous research performed by the Bureau. Previous investigators1-4 utilizing the rotary kiln for the production of sponge iron did not develop a suitable method for controlling the sulphur content. A review of the literature shows that the sulphur content in the product usually exceeded 0.1 per cent unless reducing agents with very low sulphur contents were employed. This high sulphur value made the product generally undesirable for use as melting stock in electric or open-hearth furnaces. The production of sponge iron in an internally fired rotary kiln has been described in detail in Bureau of Mines Bullelin 2702; consequently, this article will be confined mostly to new features of the process—that is, means for controlling the sulphur content of the sponge iron. Suitable raw materials include iron ores or mill scale; coal or coke for reducing them, and sized dolomite ( — poi-100-mesh) as the sulphur-controlling agent. A mixture of the raw materials in granular form is fed into the elevated end of the kiln, which is fired axially from the lower or discharge end. In the reducing zone, which is approximately one third the length of the kiln measured from the dis-

Jan 1, 1948

By George A. Johnson, Leon H. Banks

The Missouri-Kansas Zinc Corpn., operating in the Waco district, 15 miles northwest of .Joplin, Mo., owns large tailing piles made during milling operations of the years 1918-28 by the Butte-Kansas, Acme, and Barnsdall mining companies, whose holdings have been purchased and consolidated under the ownership of the Missouri-Kansas Zinc Corpn. These tailings had been considered too low in value to be worth retreating by the ordinary methods. C. Erb Wuensch, consulting engineer of the Missouri-Kansas Zinc Corpn., noted the difference in the type of tailing from upper-level and lower-level ore. The latter contained hard lime chats. He also found that mill losses had been due to particles of blende on the corners or sides of the chats and to the existence of soft, porous, cellular, lime chats containing varying amounts of blende. He conceived the idea that a quick grind in rolls or hall rnills might change the type of the rnaterial so that jigging could rnake a clean tailing for discard and a partly concentrated product sufficient in blende content to justify the expense of fine grinding in hall mills to free the mineral entirely. A laboratory was equipped with the necessary machines and the writers were assigned the problem of developing a method of retreating the tailings. Laboratory Testing From preliminary drill sampling of each pile was obtained the blende content, the soluble sulfate content, and the general characteristics of the material to he treated. The tailings were a mixture of lime and flint with some shale. Visual examination showed most of the blende to be in the dolomite and very little in the flint, although there were some flint particles with blende on the cleavages. The blende was found as particles on the corners or cleavage faces in one type of chat and in another disseminated in a soft, porous, cellular lime. Because of the porosity of the latter type of chat, the apparent specific gravity, under hindered-settling conditions, is less than that of a solid piece of lime or flint. That it,

Jan 1, 1930