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By M. C. Leverett, W. B. Lewis

The dynamic behavior of a multiple fluid system is completely describable in terms of driving forces and resistances to flow. The latter are proportional to the viscosity of the fluid under consideration and inversely proportional to a property of the system termed the " effective permeability " to that fluid, a property therefore defined by this relation. Since three phases are usually present in oil reservoirs, it is essential to know the effective permeabilities to the several fluid phases, and the relationship between the composition of the fluid in the pore space and that of the flowing stream, in order to handle satisfactorily certain problems of oil production. In this regard, there are many unknown factors and parameters, and many that can be evaluated only indirectly. However, it is expected that work along lines similar to this present undertaking will help materially in solving these problems. .. . . Previous workers in this field have investigated the two-phase systems, water-gas,' water-oil2 in unconsolidated sands, and water-gasg in consolidated sands. The extension of the study of the flow of heterogeneous fluid systems from two to three phases involved only slight changes in technique. The apparatus used in the present work, except for slight changes to be described, was that used by Leverett in his water-oil experiments.~ Correlation and interpretation of data were made by methods analogous to those used in two- phase work. The relative permeability to a phase—the effective permeability divided by the permeability of the system to a homogeneous fluid—was employed throughout in correlating the rate of flow of that phase with the composition of the pore space. Quantitative measurements of two independent physical properties of the system were required to determine the composition of the pore space. As in the two-phase work, the fraction of water was determined electrically, The gas fraction was determined by measuring changes in volume accompanying measured pressure changes. Suitable account was taken of the solubility of the gas in the liquid phases, and of the vapor pressure of the water phase. Since this work was exploratory in nature, no attempt was made to obtain highly accurate numerical results. Reasonable precision and reproducibility were sought. Experimental Procedure variables Considered.—Of the properties of the fluids, the oil viscosity is most likely in practice to vary widely. Variations in oil viscosity were therefore included in this work, but variations in other properties of the fluids are as yet unexplored. It appears unlikely that the normally encountered variations will produce significant changes. ~h~ observations were made at fairly high pressure gradients, no attempt being made to detect a variation of the relative permeabilities with pressure gradient. It should be pointed out also that since most of the data were taken on one sand size only, it call Only be assumed at present that changes in

Jan 1, 1941

By W. B. Lewis, M. C. Leverett

The dynamic behavior of a multiple fluid system is completely describable in terms of driving forces and resistances to flow. The latter are proportional to the viscosity of the fluid under consideration and inversely proportional to a property of the system termed the " effective permeability " to that fluid, a property therefore defined by this relation. Since three phases are usually present in oil reservoirs, it is essential to know the effective permeabilities to the several fluid phases, and the relationship between the composition of the fluid in the pore space and that of the flowing stream, in order to handle satisfactorily certain problems of oil production. In this regard, there are many unknown factors and parameters, and many that can be evaluated only indirectly. However, it is expected that work along lines similar to this present undertaking will help materially in solving these problems. .. . . Previous workers in this field have investigated the two-phase systems, water-gas,' water-oil2 in unconsolidated sands, and water-gasg in consolidated sands. The extension of the study of the flow of heterogeneous fluid systems from two to three phases involved only slight changes in technique. The apparatus used in the present work, except for slight changes to be described, was that used by Leverett in his water-oil experiments.~ Correlation and interpretation of data were made by methods analogous to those used in two- phase work. The relative permeability to a phase—the effective permeability divided by the permeability of the system to a homogeneous fluid—was employed throughout in correlating the rate of flow of that phase with the composition of the pore space. Quantitative measurements of two independent physical properties of the system were required to determine the composition of the pore space. As in the two-phase work, the fraction of water was determined electrically, The gas fraction was determined by measuring changes in volume accompanying measured pressure changes. Suitable account was taken of the solubility of the gas in the liquid phases, and of the vapor pressure of the water phase. Since this work was exploratory in nature, no attempt was made to obtain highly accurate numerical results. Reasonable precision and reproducibility were sought. Experimental Procedure variables Considered.—Of the properties of the fluids, the oil viscosity is most likely in practice to vary widely. Variations in oil viscosity were therefore included in this work, but variations in other properties of the fluids are as yet unexplored. It appears unlikely that the normally encountered variations will produce significant changes. ~h~ observations were made at fairly high pressure gradients, no attempt being made to detect a variation of the relative permeabilities with pressure gradient. It should be pointed out also that since most of the data were taken on one sand size only, it call Only be assumed at present that changes in

Jan 1, 1941

Discussion Of the paper Of GEORGE K. BURGESS, J. J. CROWE, H. S. RAWDON, and R. G. WALTENBERG, presented at the Pittsburgh meeting, October, 1914, and printed in Bulletin NO. 93, September, 1914, pp. 2433 to 2437. ALBERT SAUVEUR, Cambridge, Mass.-The Bureau of Standards has once more rendered a public service. Manufacturers and consumers of steel rails alike should welcome the important results now laid before them by Dr. Burgess and his co-workers. Personally I welcome these results all the more that in the past, as some of the members may remember, I have never failed, when occasion arose, to call the attention of rail manufacturers to the importance of controlling the finishing temperature of their rails. The pioneer metallographic work conducted at the South Works of the Illinois Steel Co. in the early '90s clearly brought out the close relations existing between the manufacture, properties, and finishing temperature of steel rails and I think I may say without fear of being contradicted that the results of this early investigation had considerable influence in drawing the attention of manufacturers to the importance of finishing temperature and of heat treatment in general. The results now before us should be, it seems to me, of great value to rail manufacturers in their efforts to produce a better and, above all, a safer rail. It seems to be demonstrated in this paper that there is no difficulty in installing in rail mills pyrometric outfits, making it possible to record, without interfering in the mill operations, the temperature of the rails as they leave the finishing rolls, or of the ingots as they are withdrawn from the soaking pits, or at any intermediate point in the process of manufacture. The inference necessarily follows that manufacturers should see to it that such pyrometric installations are made, in order that they may actually know, instead of guessing at, the temperature of their rails;, and, for obvious reasons, rail consumers should insist upon such installations. In the rolling of heavy sections especially should care be taken to lower their finishing temperature, seeing that the present tendency is to finish them at higher temperature, whereas, owing to the slower cooling of their central portions, which makes for coarseness of grain, they should, if anything, be finished at a lower temperature than lighter rails.

Jan 4, 1915

By Thos. W. Gibson

The object of taxation is the raising of a revenue. Unless a tax accomplishes this, it is a failure. The right to take for public purposes a part of the moneys obtained from the carrying on of private enterprises is an attribute possessed only by a lawful government, and may indeed be called the supreme attribute of government. In free, democratic communities this power must of necessity rest upon the consent of the governed. Power implies obligation, hence it is obviously the duty of a government, in framing a system of taxation, to provide one which, while effective in producing a revenue, is also just and impartial. • It will be conceded that mines and mining property ought to bear a fair share of the public expenditure. The question is, upon what basis taxation should proceed. Two separate taxing principles are usually contended for: Taxation should be proportionate to the benefits received by the person or property taxed; taxation should be based on ability to pay. A third is sometimes added, taxation should have reference to the extent and value of the natural resources enjoyed. As applied to mining taxation, it is pointed out by those who support the fist mentioned basis that, mines being usually situated in rocky and hence sparsely peopled regions, mining companies are frequently obliged to construct roads, railways, telegraph and telephone lines, schools, water and sewerage systems, and many other amenities and conveniencea of civilization the cost of which in regions better suited for agriculture, and consequently more thickly populated, has either been defrayed locally, or can be spread over a sufficiently large taxable group of people to materially lighten the financial burden on the mine. The mining company, it is argued, having made these outlays, should receive credit for them and be relieved of taxation to a corresponding extent. There may be some force in this contention, but the situation is capable of relief without attempting to place taxation upon so unworkable a basis as the value of benefits received. Who is to be the judge of these benefits, and how are they to be valued? The very existence of a mining company and its ability to carry on business in peace and security depeind on the prevalence of law and order, which is a result of good government. The state provides protection against violence, and courts of law for

Jan 1, 1920

By Thomas L. Garwood, F. C. Menk

IT is generally accepted that no method of coal cleaning except froth flotation is effective in cleaning dust. In the majority of coals mined in the United States the dust sues contain a high percentage of impurities, hence the removal of the dust from the coarse sizes lowers the impurity content of these sizes. Dedusted coal is desired as a means of providing a better feed to cleaning plants because of increased efficiency in I both dry and wet plants. In dry-cleaning plants, a dedusted feed makes for a pervious and uniform bed. With a dusty feed the fines tend to segregate in the feed stream and pass en masse over the air separators, causing a lack of uniform aeration and fluidity of the bed necessary to efficient cleaning. In wet-cleaning plants dedusting of the feed often decreases the sludge problem to the point of eliminating the necessity of wasting wash water. It may be advantageous to eliminate sludge-settling equipment in favor of dedusting equipment, to provide the advantages of a dedusted feed to the wet-washing process. Dedusting advantages may include: (1) the removal of fusain, especially advantageous in plants washing coal intended for metallurgical coke; (2) prevention of the gradual build-up of solids in the wash water, with a consequent variation in the washing ability of the system; (3) prevention of the loss of dust to the sludge ponds, providing instead a fuel for local consumption or special markets. DEDUSTING The practice of dedusting, sometimes called aspirating, has presented a problem in disposing of the dust and intermediate small sizes recovered in the process. It has been found that no difficulty is experienced in disposing of the intermediate sizes, since they are free of fine dust and burn freely on grates built for small coal. They handle well, flowing freely from bins and hoppers and into conveyors, and pulverize easily. They have a low angle of repose. In tests made on this size as a feed to coke ovens, the results have been excellent, in that the natural breakdown of coal in handling and shooting in the mine gives this small-size coal good coking characteristics-producing a strong, fingery coke structure. Deduster dust from Illinois coal has been

Jan 1, 1950

By S. Korman, S. B. Tuwiner

THE purpose of this study is to investigate the effect of agitation upon the flotation of chal-cocite. It is believed that the concentration of collector which is required to produce a water-repellent surface upon the mineral is determined among other things by the rate of collector diffusion through an impeding film of more or less stagnant fluid. Its thickness depends upon the intensity of agitation. In the first part of this study a method is developed for determining the thickness of the fluid film upon a polished surface of synthetic chalcocite. The film thickness is then determined as precisely as possible under three readily reproducible condi-tions of agitation intensity. These determinations serve as a quantitative evaluation of agitation. In Part 2 it is demonstrated that in solutions of lime at PH 10.5 and in the absence of air or dissolved oxygen the concentration of collector required to develop water-repellency upon the surface in any given time is a function of the fluid film thickness, and that after about 10 min the relation becomes linear. This points to the possibility that the collector ions may be involved in a diffusional process through the fluid film. In Part 3 it is shown that where air is present more collector is required to produce water-repellency than for the case in which air is excluded. Next, it is shown that for the latter case the most minute amount of sodium sulphide suffices to preclude development of water-repellency. Both oxygen and sulphide are in a sense, therefore, depres- sants for chalcocite in a lime solution at PH 10.5. When oxygen and sulphide are present simultaneously there is a region of minimum critical collector concentration for water-repellency which is very markedly lower than the concentration where oxygen alone or where sulphide alone is present. Moreover, this minimum appears to be identical with the collector concentration which is required where sulphide and oxygen are both excluded. This would appear to indicate that in certain ranges of concentration of oxygen and sulphide, each cancels the effect of the other. The range of concentration of solution for this effect in solutions saturated with oxygen is a function of the agitation intensity. Thus we are led to believe that a chemical reaction involving sulphide and oxygen occurs at the surface of the chalcocite. Part 4 of this study is a further development of this idea and some of its consequences from an electrochemical standpoint, while in Part 5 the disappearance of sulphide from pulps of several minerals is noted with an indication that both dissolved oxygen and the mineral are necessary, the reaction being catalytic or pseudocatalytic. Part 1. Determination of Fluid Film Thickness The Fluid Film Concept: The hindrance to the diffusion of collector to the surface of the chalcocite is a barrier of stagnant fluid in the vicinity of the surface. It is the same barrier that limits the rate of transfer of heat, the rate of solution of dissolving crystals, or any of the other rates pertaining to chemical engineering unit operations in which the film resistance to diffusion plays a principal role.' Fluid films are present upon the surface to an extent which varies with the geometry and intensity of agitation. They result from the fact that in the region within the fluid near a surface, motion is entirely parallel to it. From the standpoint of transfer to or away from the interface the effect is as though the fluid were stagnant. Outside of the film, movement of the fluid may be streamline or turbu-

Jan 1, 1951

By S. Korman, S. B. Tuwiner

THE purpose of this study is to investigate the effect of agitation upon the flotation of chal-cocite. It is believed that the concentration of collector which is required to produce a water-repellent surface upon the mineral is determined among other things by the rate of collector diffusion through an impeding film of more or less stagnant fluid. Its thickness depends upon the intensity of agitation. In the first part of this study a method is developed for determining the thickness of the fluid film upon a polished surface of synthetic chalcocite. The film thickness is then determined as precisely as possible under three readily reproducible condi-tions of agitation intensity. These determinations serve as a quantitative evaluation of agitation. In Part 2 it is demonstrated that in solutions of lime at PH 10.5 and in the absence of air or dissolved oxygen the concentration of collector required to develop water-repellency upon the surface in any given time is a function of the fluid film thickness, and that after about 10 min the relation becomes linear. This points to the possibility that the collector ions may be involved in a diffusional process through the fluid film. In Part 3 it is shown that where air is present more collector is required to produce water-repellency than for the case in which air is excluded. Next, it is shown that for the latter case the most minute amount of sodium sulphide suffices to preclude development of water-repellency. Both oxygen and sulphide are in a sense, therefore, depres- sants for chalcocite in a lime solution at PH 10.5. When oxygen and sulphide are present simultaneously there is a region of minimum critical collector concentration for water-repellency which is very markedly lower than the concentration where oxygen alone or where sulphide alone is present. Moreover, this minimum appears to be identical with the collector concentration which is required where sulphide and oxygen are both excluded. This would appear to indicate that in certain ranges of concentration of oxygen and sulphide, each cancels the effect of the other. The range of concentration of solution for this effect in solutions saturated with oxygen is a function of the agitation intensity. Thus we are led to believe that a chemical reaction involving sulphide and oxygen occurs at the surface of the chalcocite. Part 4 of this study is a further development of this idea and some of its consequences from an electrochemical standpoint, while in Part 5 the disappearance of sulphide from pulps of several minerals is noted with an indication that both dissolved oxygen and the mineral are necessary, the reaction being catalytic or pseudocatalytic. Part 1. Determination of Fluid Film Thickness The Fluid Film Concept: The hindrance to the diffusion of collector to the surface of the chalcocite is a barrier of stagnant fluid in the vicinity of the surface. It is the same barrier that limits the rate of transfer of heat, the rate of solution of dissolving crystals, or any of the other rates pertaining to chemical engineering unit operations in which the film resistance to diffusion plays a principal role.' Fluid films are present upon the surface to an extent which varies with the geometry and intensity of agitation. They result from the fact that in the region within the fluid near a surface, motion is entirely parallel to it. From the standpoint of transfer to or away from the interface the effect is as though the fluid were stagnant. Outside of the film, movement of the fluid may be streamline or turbu-

Jan 1, 1951

By C.H. Lorig, M.C. Udy

Through the years much interest has been centered in attempting to develop a direct method of iron-ore reduction, to replace or supplement the present indirect blast-furnace process. It would not be difficult to produce a list of more than 500 patents dealing with the direct production of iron and steel, but the few of this type of process that have proved successful do not produce in competition with the blast furnace; they produce special products. A survey of the literature reveals that the equilibrium conditions for the reduction reactions (iron oxides with carbon monoxide and with hydrogen) have been fairly well established but that data on the rate of reaction are discordant, although the genera1 effects of the variables are known. This dissertation deals with the rate of reduction of a magnetite concentrate with hydrogen. The following variables have been studied: bed depth, gas velocity, particle size and temperature. The behavior of a single particle was also studied. Literature Two general factors should be considered in a study of reduction of iron oxide: (I) equilibrium relations, and (2) rate of reaction. The first factor, equilibrium, has received the attention of many investigators and the equilibria Fe304-FeO-H2-H2O, Fe3O4-FeO-CO-CO2, FeO-Fe-H2-H2O, FeO-Fe-CO-CO2 are fairly well established. Of the second factor, the rate of reaction, much less is known. Data are comparatively scarce and there is very little concordance. The discordance probably results from the large number of variables influencing the reactions. However, the general effect of the variables is known. Among these variables are temperature, gas velocity, particle size, porosity, gas composition (distance from equilibrium), presence of impurities, greater or less prevalence of side reactions, and even design of the apparatus itself. Wetherill and Furnasl published an excellent paper in 1934. They point out that any one or more of five processes (the chemical reaction, diffusion of the reactant through the gas film, diffusion of the reactant through the solid phase, diffusion of the reaction product through the solid phase, or diffusion of the reaction product through the gas film) may be the slow process, and thus the rate-controlling process. It is regretted that the work of these authors was limited to experiments at One temperature, and that the range of gas compositions was limited. Langmuir2 has shown that heterogeneous reactions take place at phase boundaries.

Jan 1, 1943

By M. C. Udy, C. H. Lorig

Through the years much interest has been centered in attempting to develop a direct method of iron-ore reduction, to replace or supplement the present indirect blast-furnace process. It would not be difficult to produce a list of more than 500 patents dealing with the direct production of iron and steel, but the few of this type of process that have proved successful do not produce in competition with the blast furnace; they produce special products. A survey of the literature reveals that the equilibrium conditions for the reduction reactions (iron oxides with carbon monoxide and with hydrogen) have been fairly well established but that data on the rate of reaction are discordant, although the genera1 effects of the variables are known. This dissertation deals with the rate of reduction of a magnetite concentrate with hydrogen. The following variables have been studied: bed depth, gas velocity, particle size and temperature. The behavior of a single particle was also studied. Literature Two general factors should be considered in a study of reduction of iron oxide: (I) equilibrium relations, and (2) rate of reaction. The first factor, equilibrium, has received the attention of many investigators and the equilibria Fe304-FeO-H2-H2O, Fe3O4-FeO-CO-CO2, FeO-Fe-H2-H2O, FeO-Fe-CO-CO2 are fairly well established. Of the second factor, the rate of reaction, much less is known. Data are comparatively scarce and there is very little concordance. The discordance probably results from the large number of variables influencing the reactions. However, the general effect of the variables is known. Among these variables are temperature, gas velocity, particle size, porosity, gas composition (distance from equilibrium), presence of impurities, greater or less prevalence of side reactions, and even design of the apparatus itself. Wetherill and Furnasl published an excellent paper in 1934. They point out that any one or more of five processes (the chemical reaction, diffusion of the reactant through the gas film, diffusion of the reactant through the solid phase, diffusion of the reaction product through the solid phase, or diffusion of the reaction product through the gas film) may be the slow process, and thus the rate-controlling process. It is regretted that the work of these authors was limited to experiments at One temperature, and that the range of gas compositions was limited. Langmuir2 has shown that heterogeneous reactions take place at phase boundaries.

Jan 1, 1943

By James Hyslop

THE Pittsburgh seam in eastern Ohio has an average thickness of 5 ft and lies almost level Immediately above it is a layer of draw slate about 12 in thick, which normally has little structural strength, and is pulled down or allowed to fall as mining progresses Above the slate is a, variable thickness of roof coal, which in places will stand for the life of the working section and sometimes for the life of a secondary haulage entry The thickness of this roof coal varies from zero to 24 in In general, however, it does not provide a satisfactory roof, and usually is supported or pulled down About it is a mass of shale, soapstone and clay, of quite variable thickness, usually running from 5 to 8 ft and above this is a stratum of hard blue limestone, which provides a permanent roof Where entries are to be used for less than five years, the roof usually can be supported by wood or steel crossbars, but if they are to be used for a longer time, roof support is a serious problem All the roof material below the limestone disintegrates when exposed to air or moisture, and in a few years falls out between and over the crossbars Where this material is removed for a considerable height above the coal, the ribs scale and thus contribute to a further collapse of the roof As the height of the entry increases, cost of timbering is greatly increased, a problem that always is encountered where old entries are recovered or repaired METHODS During the last six years the Hanna Coal Co has used gunite for roof protection in mine entries Two general methods of guniting are practiced The first consists of the application of a I-in coating of unreinforced material This application does not provide any appreciable structural strength, and serves principally to protect the strata from exposure to air and moisture With the other method a coat at least 2 in thick is applied and provided with suitable reinforcing, which provides a structural strength proportional to the thickness of the coat and the reinforcing used The first method is adopted as a general practice, modified only where additional support is required "Gunite" is a mixture of cement, sand and water * The cement and sand are thoroughly mixed and screened before being fed into the hopper of a cement gun After the hopper lid is closed, compressed air is applied to force this dry mixture through the hose line to the nozzle, where the quantity of water needed to effect the proper hydration of the cement is added The coating is dense, and stronger than poured concrete

Jan 1, 1941

By A. V. Deforest, A. R. Anderson, C. W. MacGregor

ONE of the important problems in the design of structures and machine parts subjected to rapidly applied loads is the determination of the strength and ductility of the material itself under such conditions. Realizing the need for such information, many investigations have been carried out in the past. Most of these experiments have been made using notched bars in bending either with the Charpy or Izod impact machine. While yielding valuable data on the effect of notches in the energy absorption of the material and on the condition of heat-treatment, this form of test does not lend itself readily to a determination of fundamental stress-strain relations. For this and other reasons, more attention has been paid recently to the tension impact test. An extensive literature already exists on the subject and only those investigations somewhat closely related to the present paper will be mentioned. For a more comprehensive list, the reader is referred to the Symposium on Impact Testing of the A.S.T.M., 1938. The work of Mann,1 Clark and Dätwyler,2 Nádai and Manjoine,3 Winlock and Leiter,4 Deutler,5 and Brinkmann,6 however, deserve especial mention. In most of the previous investigations on the subject, when stress-strain relations were obtained under high rates of loading, it was the common procedure to determine stresses based on the original area and strains based on the original length. Stress-strain curves were then constructed by plotting [So = ooT as a function of eo =o] where A o and Lo refer to the original area and gauge length, respectively. At present there exists a paucity of true stress-strain data in the impact problem. The advantages of constructing so-called true stress-strain curves in order to reveal the fundamental physical properties of the material for the tension test were discussed recently by one of the authors? It was shown that the true physical behavior of the material in the tension test could best be represented by plotting the average true stress, [S = P] as a function of [e = q' = log A-le = log Lo] where P, A, L, S, [e], and q' refer to the load, the cross-sectioned area while the load P is applied, the actual gauge length, the average true stress, the true strain and true reduction in area, respectively. Besides giving a better physical representation, the method has certain additional advantages in that the stress-strain curve so plotted becomes a straight line from the maximum load point to fracture. The construction of such curves, however, while comparatively simple for the slow rates of loading customarily used in the tension test, presents certain difficulties for tensile impact in that both loads and diameters are required throughout the test. The continuous measurement of test-piece

Jan 1, 1941

By Howard R. Keil

Reactor at Carlton mill successfully calcines pyrite-telluride flotation concentrate for cyanidation. CARLTON mill in the Cripple Creek district, 45 miles southwest of Colorado Springs, Colo., has been in operation for approximately three years, treating the custom sulpho-telluride ores formerly handled by the Golden Cycle mill in Colorado Springs. At the new mill the pyrite-telluride flotation concentrates have been roasted, prior to cyani-dation, in a Dorrco FluoSolids reactor, which has proved capable of yielding calcine readily amenable to cyanidation. Incoming ores are crushed at Carlton to % in. and sampled in 30 to 75-ton lots before the individual lots are mixed in the fine ore bin. The composite ore then goes to the grinding circuit. Classifier overflow from the grinding circuit is treated by flotation to produce a concentrate containing approximately 85 pct of the values in 5 pct of the weight. The flotation concentrate goes to the FluoSolids reactor prior to cyanidation. Cyanide solution values are recovered by zinc dust precipitation. Flotation tailings are thickened and cyanided, the values from this part of the circuit being recovered from solution by activated carbon. Gold values in the flotation concentrates consist of a small amount of finely divided metallic gold; the tellurides, sylvanite and calaverite; and gold very intimately associated with the pyrite. The metallic gold and a part of the telluride values can be extracted from the concentrates by cyaniding without roasting. However, extraction on the tellurides by this method is not satisfactory, and the pyrite values are so intimately associated with the pyrite that very fine grinding and cyanidation for a prolonged period under ideal laboratory conditions does not yield good recovery. Upon roasting, the tellurides are oxidized to very finely divided metallic gold which is readily soluble in cyanide. The pyrite is oxidized mainly to a porous iron oxide which allows cyanide solution to penetrate to gold particles and take them into solution. Feeding the Reactor Flotation concentrates move by gravity to a thickener. Thickener underflow is discharged at approximately 60 pct solids, by means of a diaphragm pump, into a storage and blending agitator. From here the concentrates are pumped to a disc filter. The filter cake, at 84 to 88 pct solids, drops directly into a repulper where it is repulped into a slurry of 78 to 80 pct solids. The repulped filter cake flows into a 6x6-ft slurry agitator from which it is fed directly into the reactor by the Moyno pump. The Moyno pump has eliminated a large number of difficulties that were first encountered in feeding a wet concentrate to the reactor. On the original installation in Canada a screw feeder was used to introduce the filter cake directly into the reactor. Since the reactor is under a slight positive pressure it was necessary to have a suitable seal to prevent gas escaping from the reactor at this point. When the concentrates produced in flotation were coarse or granular they could be readily fed to the reactor but when fine-textured, clayey concentrates were produced a great deal of trouble was encountered.

Jan 1, 1955

By H. S. McKnight

One phase of Canada's rapid development in mining and metallurgy during the past few years has been the creation of Canadian Copper Refiners Ltd., and the establishment of its modern electrolytic copper refinery at Montreal East, Quebec. Canadian Copper Refiners Ltd. is made up of three well-known metal firms whose combined activities cover the entire industry from the mine to the market. They are Noranda Mines Ltd., Toronto, Nichols Copper Co., New York, and British Metal Corporation, Ltd., London. Noranda Mines is the principal owner and provides the greater part of the raw material received by the refinery for treatment. Nichols Copper Co. designed and built the plant and is operating it under contract. British Metal Corporation acts as sales agent and markets the refinery's products. Montreal East was chosen as the site of the new refinery only after a careful survey had been made of the entire eastern part of Canada. The location chosen offers many advantages, chief of which arc the relatively low costs of power, labor, fuel and bupplies, and the fact that it is situated on Montreal harbor, the nearest seaport to the points of origin of the ram materials. All incoming material is received by rail. A majority of the plant's product is exported through the port of Montreal to European markets, being handled to the docks in railroad cars. A large proportion of the product is delivered by means of an industrial railway to the adjacent rolling mill of the Canada Wire & Cable Co., Limited. The refinery was designed to treat primarily the copper produced by Noranda Mines, Ltd. and Hudson Bay Mining &. Smelting Co., Ltd., and its rated capacity is 75,000 short tons per year. A general layout of the plant is shown in Fig. 1. Its capacity can be readily doubled, as shown by the dotted lines. Figs. 2 and 3 are sections taken through the furnace department and the tank house respectively. Except for the main office and laboratory and an auxiliary building containing the stores, warehouse, change rooms, compressor room and machine shop, the entire plant is under one roof. The type of building construction consists of reinforced concrete foundations supported on concrete piles, a steel structure covered with Robertson Protected Metal siding and a 3-in.

Jan 1, 1934

HeRbert A. MeGRaw, San Luis de la Paz, Guanajuato, Mex. (communication to the Secretary*) :—Although Mr. Bordeaux prefaces his paper with the statement-that it is a general outline of practice in the Republic, many of his statements seem to be made from the view-point of a particular case, which does not always agree with general practice. For the purpose of calling attention to some of these variations, I respectfully offer the following comments: The operation of crushing and grinding is performed by so many different methods and systems that it is useless to select any one as the standard. However, primary crushing in rock-breakers followed by stamps is thus far so general that it might be so classified. Whether or not it is the best way, is open to question. Regrinding may be performed by any of the various types of Chilean mills, Huntington mills, or similar machines, or the material may be taken directly from the stamps and delivered to the tube-mills. Mr. Bordeaux's statement that " the slimes can be treated only by decantation; the new Butters slime-filter, as used in Nevada, does not seem to be successful with silver-ores," is surely an error. All over Mexico many of the purely silver-ores are being successfully handled by the Butters or similar filters, such as the Moore and the Burt filters, and a letter to the manufacturers of these filters will undoubtedly bring a list of the silver-ores now being successfully treated in this way. The statement that crushing silver-ores in solution is impossible is equally erroneous. Most modern mills crush the ore in solution, in some cases containing as much as 0.12 per cent, of KCN. I cannot for the moment recall any modern mill in Mexico which does not follow this practice. There may be some reason for it in particular instances, but, generally speaking, the practice is to crush in solution. Care in installation avoids any mechanical loss of cyanide, and the chemical loss is so small as to be negligible.

Jan 1, 1910

By M. C. Dow

Belt conveyors generally are conceded to be the most economical method yet devised for the transportation of large quantities of bulk materials within plants. Belts are coming into greater use for transportation over long distances and are replacing other forms of long-haul conveyance. It is not the intent of the writer to comment on the design of belt conveyors, but to offer some suggestions for improvement in the operation of conveying belts, based on many years experience with belts in several stone-crushing plants. It is the contention of this writer that opportunities for improvement not fully realized by most operators exist in many plants and that a study of the individual conveyors can result in lower unit belt costs. General Reliability It is the fool-proof nature and general reliability of the belt conveyor that is responsible for its neglect. Even when abused, a belt will carry large tonnages and last a long time, often outlasting the personnel responsible for its care. Some operators look upon the purchase of a new belt as an expensive outlay every so many years, rather than a constant and steady cost amounting in belt wear alone to several dollars every operating day. This belt wear for all conveyors in one stone-crushing plant known by the writer costs 1 /12 cents per ton or $12 to $15 per hour, based on the present cost of belt replacements. The fact that these replacement costs are double those of prewar quality emphasizes the necessity of improving the conditions that make belts wear out. Some of those conditions are the responsibility of the conveyor designer, and if a serious original error has been made, this handicap cannot be overcome by the operator. If the belt is too narrow, too steep, or too fast for good loading, the operator finds that he has an inherently expensive belt. The other factors that decrease the life of a belt are more or less under his control. The two factors of most importance are the loading conditions and the alignment. Most of the cover wear and carcass cutting occurs at the loading point and if the alignment is not good under all conditions, edge wear or damage may result, Fig I. Loading the Belt It is difficult to load a belt in an ideal manner; that is, to flow the material on the moving belt at a steady rate, without impact, without turbulence, and with a velocity equal to and in the same direction as the belt. An inclined belt is especially difficult to load and particularly when its speed is over 300 or 350 fpm. Inclined conveyors require longer skirt plates to prevent spillage until the load settles. It does not seem reasonable to expect an inclined the to carry the same load as a horizontal belt of the same width and speed, because of the difficulty in loading

Jan 1, 1948

By M. C. Dow

Belt conveyors generally are conceded to be the most economical method yet devised for the transportation of large quantities of bulk materials within plants. Belts are coming into greater use for transportation over long distances and are replacing other forms of long-haul conveyance. It is not the intent of the writer to comment on the design of belt conveyors, but to offer some suggestions for improvement in the operation of conveying belts, based on many years experience with belts in several stone-crushing plants. It is the contention of this writer that opportunities for improvement not fully realized by most operators exist in many plants and that a study of the individual conveyors can result in lower unit belt costs. General Reliability It is the fool-proof nature and general reliability of the belt conveyor that is responsible for its neglect. Even when abused, a belt will carry large tonnages and last a long time, often outlasting the personnel responsible for its care. Some operators look upon the purchase of a new belt as an expensive outlay every so many years, rather than a constant and steady cost amounting in belt wear alone to several dollars every operating day. This belt wear for all conveyors in one stone-crushing plant known by the writer costs 1 /12 cents per ton or $12 to $15 per hour, based on the present cost of belt replacements. The fact that these replacement costs are double those of prewar quality emphasizes the necessity of improving the conditions that make belts wear out. Some of those conditions are the responsibility of the conveyor designer, and if a serious original error has been made, this handicap cannot be overcome by the operator. If the belt is too narrow, too steep, or too fast for good loading, the operator finds that he has an inherently expensive belt. The other factors that decrease the life of a belt are more or less under his control. The two factors of most importance are the loading conditions and the alignment. Most of the cover wear and carcass cutting occurs at the loading point and if the alignment is not good under all conditions, edge wear or damage may result, Fig I. Loading the Belt It is difficult to load a belt in an ideal manner; that is, to flow the material on the moving belt at a steady rate, without impact, without turbulence, and with a velocity equal to and in the same direction as the belt. An inclined belt is especially difficult to load and particularly when its speed is over 300 or 350 fpm. Inclined conveyors require longer skirt plates to prevent spillage until the load settles. It does not seem reasonable to expect an inclined the to carry the same load as a horizontal belt of the same width and speed, because of the difficulty in loading

Jan 1, 1948

By R. G. Webber, F. C. Langenberg

During the course of some magnetic investigations which the authors have under way, six bars of 0.43-carbon steel were tested, a permeameter designed after the Hopkinson yoke type being used. The results obtained were of some interest and although far from complete serve at least to show the necessity for a careful investigation of the previous history of the samples under study as well as the chemical composition. A steel of given chemical composition may assume a great variety of structures, depending on its treatment. Professor Sauveur has devised a very clear and effective means of illustrating this point. The accompanying microphotographs show some of the possible structures assumed by a 0.30 carbon steel (Fig. 1). It is now a well-established fact that a structural change is accompanied by changes in the tensile strength, elastic limit, hardness, etc., and it seems reasonable to assume also, a change in the magnetic properties. Six bars of a 0.43-carbon steel were used, all the bars being taken from the same rod and treated as follows: Bar 1. Heated to 1,100° and cooled in the furnace. Bar 2. Heated to 1,000° and cooled in the furnace. Bar 3. Heated to 900° and cooled in the furnace. Bar 4. Heated to 1,000° and cooled in air. Bar 5. Heated to 900° and cooled in air. Bar 6. Untreated. The bars were then turned to 13 mm. diameter and tested by the Hopkinson yoke method. After testing, three specimens were taken from each bar, one from each end and one from the middle. The homogeneity of the bars was tested in this manner and in no instance could any difference in structure in the three specimens1 be detected. Bars 1 to 3 inclusive are pearlitic in structure. The white areas are ferrite (iron with certain impurities in solution) and the dark areas pearl-

Jan 1, 1915

By M. R. J. Wyllie

The relationship between the electromotive force (E.M.F.) across a shale barrier and the concentrations of sodium chloride solutions on either side has been investigated. It is shown that the action of a shale barrier is analogous to a glass membrane separating two acid solutions of different hydrogen ion concentrations. The shale behaves as a sodium electrode and is responsive to the activities of the sodium ions in the two solutions in such a way that the potential can be calculated by means of the Nernst equation. This conclusion is confirmed by laboratory experiments. In a borehole the total E.M.F. of a shale cell is the algebraic sum of the ~otential across the shale and a boundary potential. The relationship between total E.M.F. and the resistivity ratio of two sodium chloride solutions is indicated for a number of formation temperatures. The E.M.F. thus predicted is then compared with the .elf potential read from an electric log and good agreement is demonstrated. Based on both the self potential and resistivity curves of the electrical log. a method is given for calculating connate water content in a bed having in-tergranular porosity and containing both connate water and hydrocarbons. INTRODUCTION The first paper on electrical well logging by C. and M. Schlumberger and E. G. Leonardon in 1934' attributed the self potential curve principally to streaming potentials, i.e. to electroki-netic effects. Almost immediately great difficulties were encountered in reconciling many of the curves they obtained with this interpretation. and a ~econd paper' by the same authors soon appeared. In this second paper self potentials were attributed to the combined effects of streaming potentials and electrochemical potentials, the electrochemical potential being considered the result mainly of the interaction of fluids of differing salt concentrations, i.e. a boundary potential, and partly of potentials set up at the faces of impermeable materials. Some experiments involving a gray clay for the impermeable material were quated. The Schlumbergers and Leonardon deduced from the equation for a simple boundary ~otential that the electrochemical potential, as opposed to the electrokinetic potential, could be expressed in the form E=Klog- .......1 pe where K is a constant, pm the mud resistivity. p, the resistivity of the connate water in a porous bed. However, no general expression for the constant K was obtained. Although the literature between 1934 and 1943 contains a number of quotations of their results, the valuable work of the Schlumbergers and Leonardon was not extended so that the electrochemical potential has been generally attributed wholly to boundary potentials between the mud in the borehole and the connate waters in porous formations. Unfortunately, however, the fundamental premise of all these papers, that a boundary potential can give rise to current flow in a borehole, is thermodynamically untenable. As will be shown. the fact that the electrochemical potential can be fairly accurately express as E = K log pm/pc, a form in which a boundary potential may also be written, is partly fortuitous. The boundary potential is indeed an integral part of the expression for the electrochemical potential in a horehole, but in magnitude it represents only about 20% of the total potential. In 1943 an important step in the elucidation of electrochemical potentials was made by Mounce and Rust3 who showed that if a wall of shale separated two compartments which contained saline solutions of different concentrations, and if the two solutions were themselves brought into contact in the pores of a porous inert membrane (such as unglazed porcelain) a current flowed through the shale and saline solutions. The direction of positive current was from the shale into the more dilute solution. The paper of Mounce and Rust, while repeating some of the observations of the Schlumbergers and Leonardon, seems to be the first to show that the shale was the seat of a genuine electrochemical effect capable of causing current flow. In the same paper Mounce and Rust pointed out the similarity between the fundamental conditions of their experiment and the conditions which existed when a bed of shale in the ground was simultaneously in contact with a porous sand containing saline connate water and mud fluid of salinity different from that of the water in the sand. Since it is now generally recognized that the S.P. curve measures ohmic potential changes in the mud fluid in the well bore resulting from changes in current flow, it is apparent that currents having their origin in the electrochemical interaction of mud filtrate and connate waters with shale beds are a very important portion of the total S.P. The work of Mounce and Rusta and others appears to indicate that, in general, the electrochemical portion of a particular kick on a S.P. curve far exceeds any electrokinetic potentials resulting either from streaming potentials or Dorn effects. The Dorn effect, or sedimentation potential. arises when small particles are allowed to fall through certain fluids under the influence of gravity. a difference of potential being observe? between two electrodes placed at different levels in the stream of falling particles. The Dorn effect is unlikely to affect seriously the S.P. curve as now measured. A successful analysis of the electrochemical aspects of the S.P. log should

Jan 1, 1949

By M. R. J. Wyllie

The relationship between the electromotive force (E.M.F.) across a shale barrier and the concentrations of sodium chloride solutions on either side has been investigated. It is shown that the action of a shale barrier is analogous to a glass membrane separating two acid solutions of different hydrogen ion concentrations. The shale behaves as a sodium electrode and is responsive to the activities of the sodium ions in the two solutions in such a way that the potential can be calculated by means of the Nernst equation. This conclusion is confirmed by laboratory experiments. In a borehole the total E.M.F. of a shale cell is the algebraic sum of the ~otential across the shale and a boundary potential. The relationship between total E.M.F. and the resistivity ratio of two sodium chloride solutions is indicated for a number of formation temperatures. The E.M.F. thus predicted is then compared with the .elf potential read from an electric log and good agreement is demonstrated. Based on both the self potential and resistivity curves of the electrical log. a method is given for calculating connate water content in a bed having in-tergranular porosity and containing both connate water and hydrocarbons. INTRODUCTION The first paper on electrical well logging by C. and M. Schlumberger and E. G. Leonardon in 1934' attributed the self potential curve principally to streaming potentials, i.e. to electroki-netic effects. Almost immediately great difficulties were encountered in reconciling many of the curves they obtained with this interpretation. and a ~econd paper' by the same authors soon appeared. In this second paper self potentials were attributed to the combined effects of streaming potentials and electrochemical potentials, the electrochemical potential being considered the result mainly of the interaction of fluids of differing salt concentrations, i.e. a boundary potential, and partly of potentials set up at the faces of impermeable materials. Some experiments involving a gray clay for the impermeable material were quated. The Schlumbergers and Leonardon deduced from the equation for a simple boundary ~otential that the electrochemical potential, as opposed to the electrokinetic potential, could be expressed in the form E=Klog- .......1 pe where K is a constant, pm the mud resistivity. p, the resistivity of the connate water in a porous bed. However, no general expression for the constant K was obtained. Although the literature between 1934 and 1943 contains a number of quotations of their results, the valuable work of the Schlumbergers and Leonardon was not extended so that the electrochemical potential has been generally attributed wholly to boundary potentials between the mud in the borehole and the connate waters in porous formations. Unfortunately, however, the fundamental premise of all these papers, that a boundary potential can give rise to current flow in a borehole, is thermodynamically untenable. As will be shown. the fact that the electrochemical potential can be fairly accurately express as E = K log pm/pc, a form in which a boundary potential may also be written, is partly fortuitous. The boundary potential is indeed an integral part of the expression for the electrochemical potential in a horehole, but in magnitude it represents only about 20% of the total potential. In 1943 an important step in the elucidation of electrochemical potentials was made by Mounce and Rust3 who showed that if a wall of shale separated two compartments which contained saline solutions of different concentrations, and if the two solutions were themselves brought into contact in the pores of a porous inert membrane (such as unglazed porcelain) a current flowed through the shale and saline solutions. The direction of positive current was from the shale into the more dilute solution. The paper of Mounce and Rust, while repeating some of the observations of the Schlumbergers and Leonardon, seems to be the first to show that the shale was the seat of a genuine electrochemical effect capable of causing current flow. In the same paper Mounce and Rust pointed out the similarity between the fundamental conditions of their experiment and the conditions which existed when a bed of shale in the ground was simultaneously in contact with a porous sand containing saline connate water and mud fluid of salinity different from that of the water in the sand. Since it is now generally recognized that the S.P. curve measures ohmic potential changes in the mud fluid in the well bore resulting from changes in current flow, it is apparent that currents having their origin in the electrochemical interaction of mud filtrate and connate waters with shale beds are a very important portion of the total S.P. The work of Mounce and Rusta and others appears to indicate that, in general, the electrochemical portion of a particular kick on a S.P. curve far exceeds any electrokinetic potentials resulting either from streaming potentials or Dorn effects. The Dorn effect, or sedimentation potential. arises when small particles are allowed to fall through certain fluids under the influence of gravity. a difference of potential being observe? between two electrodes placed at different levels in the stream of falling particles. The Dorn effect is unlikely to affect seriously the S.P. curve as now measured. A successful analysis of the electrochemical aspects of the S.P. log should

Jan 1, 1949

By F. N. Koepel, L. A. Callaway

The property of the Andes Copper Mining Co. is in the central part of the Republic of Chile, Province of Atacama, about 75 miles to the eastward from the port of Chafñaral. At this point the Andean system is made up of two principal ranges, and the mine and metallurgical plant are both on the westerly slope of the outer or western range. Mean elevation of the mine is 10,500 ft., while at the plant the elevation ranges from 9445 to 9700 ft. A meter gage railroad extends from the company's port at Barquito, near Chañaral, to the reduction plant at Potrerillos. This road has a total length of 94 miles, of which 57.79 miles are owned by the Andes Copper Mining Co. and the remainder of the road is controlled by the State. Development of the Potrerillos mine and installation of the metallurgical equipment presented unusual difficulties due to the arid nature of the country, high altitude and remoteness of the location from any considerable center of population. As a primary step it was necessary that railroad transportation be provided in order that mine development and plant construction could go forward on an economical basis. Provision of an adequate supply of water for domestic and metallurgical uses involved the construction of approximately 178 miles of pipe lines, all of which have their sources at altitudes ranging from 12,000 to 14,000 ft. above sea level and traverse rough and difficult terrane. Water for metallurgical use is brought to Potrerillos from the Ola River, a stream originating in the high cordillera to the eastward from the property. It is delivered by means of a steel pipe line, 32 miles long, having diameters ranging from 22 to 36 in. Domestic water is supplied to the various camps through a system of pipe lines aggregating 146 miles in length, the Ola water being unfit for this purpose. These conductors gather water from numerous springs in the high mountains to the eastward from Potrerillos and deliver it to the mine, the reduction works and the port at Barquito. Extensive permanent housing facilities had to be provided as it was necessary to care for more than 3000 workmen and employees at the

Jan 1, 1934