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By Peter Greenfield, Paul A. Beck

Thirty binary systems of vanadium and chromium group transition elements with second and third long period transition elements were explored in regard to the intermediate phases formed. It was found that the phases predominating in these systems are s, AB type with ordered a-tungsten or C8 structure, close-packed-hexagonal with small unit cell dimensions and, finally, phases isomorphous with 1-manganese. IN recent years, considerable information has become available concerning the intermediate phases in binary systems of the transition elements. Thus, the s phase has been found to occur in most of the binary systems of vanadium, chromium, and molybdenum with the group of elements manganese, iron, cobalt, and nickel.' It was observed that, while the rr phases formed by chromium with manganese, iron, or cobalt possess a considerable temperature range of stability, particularly in the Cr-Co system, the corresponding s phases with molybdenum are limited to a temperature range of less than 400" above about 1200°C. Goldschmidt' reported v phases of tungsten with iron and cobalt, and these are apparently stable only at (and above?) 1400°C." Exploratory work in this laboratory with Fe-W and Co-W alloys of approximately 60 atomic pct W annealed at 1300°C did not produce X-ray patterns suggesting the presence of a phase. It appears then that the phases of iron and cobalt with the chromium group elements decrease in stability as the two components are chosen from long periods further removed from each other. From the available information, it might be concluded that the controlling factor is the increasing difference in atomic radii between the components. In contrast to the a phase, the phases formed by iron and cobalt with chromium group elements' are stable only when the latter have large atomic radii (molybdenum and tungsten); the corresponding phases with chromium do not occur. When the difference in atomic size becomes still larger (r,/r,, approaching the ideal value of 1.225), the u and p phases are replaced by Laves phases (AB,), as in the alloys of iron and cobalt with columbium," tantalum." and titanium."-" However, atomic size certainly cannot be the sole determining factor, since, for instance, in contrast to the very stable (Mo, Co)p phase, no such phase occurs in the Mo-Ni system even though the atomic diameters of cobalt and nickel are nearly the same. Similarly, chromium and cobalt form a a phase in a wide temperature range," but the corresponding s phase in the Cr-Ni system is missing. It has been shown that the composition of the u phase in various binary and ternary systems of transition elements in the first long period may be correlated in a fairly quantitative manner with the number of electron vacancies. The influence of electronic structure is probably present also in binary and ternary phases' and to some extent, apparently, even in Laves phases." " Although the absence of phases in the Cr-Ni and Mo-Ni systems has not as yet been explained on the basis of electronic structure, it appears reasonable to suspect a connection. One of the great difficulties in arriving at well founded rules in regard to the alloying behavior of transition elements lies in the lack of reliable information concerning the details of their electronic structure in the metallic and alloy form. The theoretical penetration of this field appears to be beset by very considerable difficulties, even when the complications due to alloy formation are disregarded. Another great source of uncertainty is the scarcity of phase diagram information even for binary systems of the transition elements so that only a very limited basis is provided for generalizations as to the occurrence of intermediate phases. For instance, very few binary phase diagrams of second and third long period transition element systems have so far been published. The present work was undertaken in order to survey the various types of intermediate phases occurring in 30 binary systems of elements of the group vanadium, columbium, tantalum, chromium, molybdenum, and tungsten with the elements rhenium, ruthenium, rhodium, palladium, and platinum. For most of these binary systems phase diagrams are very incompletely or not at all known, as will be further reviewed.*

Jan 1, 1957

By H. E. Cline

A criterion for stability of a lamellar structure in two-phase alloys ulas derived froflr perturbation analysis of the steady-state solutions for eutectic growth. Both the mass and thermal diffusion were considered with boundary conditions for coupled lamellar growth. The concept of an effective liquidus slope was introduced. Excellent agreement was found with the experiments of Mollard and Flemings and the theory predicted a range of compositions on one side of the eulectic composition in which stable growth may occur with zero temperature gradient. The lamellar structure was found to be more stable than predicted by simple constitutional supercooling. The effect of impurity additions was also considered. DIRECTIONALLY solidified eutectic alloys may have a structure consisting of parallel plates or rods. It is important to know the range of composition and growth conditions that produce this ideal composite structure. Breakdown of the planar solid-liquid interface during growth may lead to a dendritic or cellular structure as in single-phase alloys. In the case of single-phase alloys, the concept of constitutional supercooling1 may explain breakdown, but in two-phase alloys the concept is no longer valid because the melting point is not given by the liquidus of one phase. Both phases must be considered in the mass and thermal diffusion problem. In the following theory a boundary condition at the solid-liquid interface was determined by using the steady-state equations of Jackson and ~unt' to relate the average temperature and composition of the liquid at the interface. Then a sinusoidal perturbation in the shape of the interface was introduced to test for stability as in the analysis of Mullins and ~ekerka.~ The wavelength of the important perturbation was assumed to be much larger than the lamellar spacing, h, and the perturbation was assumed not to change the lamellar spacing, A. Both the mass and thermal diffusion equation were used with averaged quantities at the boundary to determine whether the perturbation grows or shrinks in time. A stability criterion was determined by considering the case in which the perturbation remains stationary. An example of Pb-Sn alloys was used to illustrate the validity of this theory. I) THEORY A) Temperature at the Interface. The temperature of the interface in coupled two-phase growth is close to the eutectic temperature TE even for alloys off eutectic composition. It is assumed that the interface is in local equilibrium and one expects the temperature at the intersection of the liquid phase and the solid phases a and 0 to be near the eutectic temperature. The interface is undercooled because of curvature and the deviation of the composition in the liquid from the eutectic composition. The average interface temperature Ti for steady-state growth of a lamellar eutectic with a plane interface was determined by Jackson and Hunt' as given in their Eq. [17c]. Instead of using the ratio of the lamellar widths hp/h, as a parameter, the volume fraction of the 0 phase, +, will be used as it simplifies the algebra. The average interface temperature using this notation becomes: The average temperature of the interface depends on the volume fraction of the 0 phase, +, which may be related to the composition of the solid or the bulk composition of the liquid Co by: where C, and Cp are the average compositions of the solid phases. In steady-state growth, the composition of the solid is equal to the composition in the liquid far from the interface. The variation of the average interface temperature with composition is illustrated in Fig. 1 for the case of Pb-Sn alloys with a 10"4 cm lamellar spacing as calculated from Eqs. [I] and [2]. The interface temperature goes through a maximum at a composition near but not exactly at the eutectic composition. There is no reason why the composition corresponding to the maximum temperature should be equal to the eutectic

Jan 1, 1969

By H. L. Riley, B. W. Gandrud

A froth flotation unit was added to the DeBardeleben Coal Corporation's Empire washer at Empire, Alabama, in the fall Of I94O following an investigation of possible ways and means of recovering coal values from settling-tank overflow or slurry. Officials of the DeBardeleben corporation hoped that some practical and reasonably economical way could be found for recovering fine coal from overflow water, although there had as yet been very little progress along this line in the Alabama coal fields. The Bureau of Mines was asked to cooperate in the project through its Southern Experiment Station, at University, Alabama. This paper presents a brief description of the process and the installation that resulted from the investigation of the overflow water or slurry problem at the Empire mine. The experimental data include' as a Part of this Paper were obtained during the course of the investigation in 1940 Since that time, however, the flotation unit has been running more or less continuously without significant operational changes and is still Performing pretty much in accordance with the data obtained in 1940. Flowsheet at Empire and Type of Coal Treated The Empire mine is developed on the Black Creek bed near the the border of the Warrior field. The coal in this bed is extremely low-ash and although there is an almost complete absence of bone coal and partings, the bed is so thin that, with mechanized mining, a high percentage of rock from roof and floor inevitably gets into the run-of-mine coal. The thickness of the Black Creek bed throughout the part of the Warrior field in which it is mined extensively is rarely over 30 in. and probably would average about 25 in, the coal is of the high-volatile A rank and of excellent quality, but as a result of admixture of roof and floor material, the run-of-mine product usually contains I ; to 20 pct rock by weight. he following is a proximate analysis on an "as-received " basis of a typical seam sample from the Empire mine:' moisture, 3.0 pet; volatile, 34.6 fixed carbon 58.3; ash, 4.1 This sample shelved 15,070 Btu per pound and 0.9 pct sulphur on a moisture-and-ash-free basis. In the Empire preparation plant the lump sizes above 3 in. are removed and hand-picked on a Marcus conveying Screen, the 3 to ? -in. size is removed by vibrating screens and washed in two Montgomery single-cell jigs, and the ?-in. to o slack is cleaned on four diagonal

Jan 1, 1949

By J. B. Clark

The oil industry has long recognized the need for increasing well productivity. To meet this need, a process is being developed whereby the producing formation permeability is increased by hydraulically fracturing the formation. The "Hydrafrac" process, as it is now being used, consists of two steps: (1) injecting a viscous liquid containing a granular material, such as sand for a propping agent, under high hydraulic pressure to fracture the formation; (2) causing the viscous liquid to change from a high to a low viscosity so that it may be readily displaced from the formation. To date the process has been used in 32 jobs on 23 wells in 7 fields, resulting in a sustained increase in production in 11 wells. INTRODUCTION Need For Process Although explosives, acidizing, and other methods have long been used, there still exists a need for artificial means of improving the productive ability of oil and gas wells, particularly for wells which produce from formations which do not react readily with acids. This paper discusses the development of a hydraulic fracturing process, "Hydrafrac", which shows distinct promise of increasing production rates from wells producing from any type of formation. The method is also considered applicable to gas and water injection wells, wells used for solution mining of salts and, with some modification, to water wells and sulphur wells. Requirements of Process In considering such a possible process, it appeared that certain requirements must be met. Some of these are as follows: A. The hydraulic fluid selected must be sufficiently viscous that it can be injected into the well at pressure high enough to cause fracturing. B. The hydraulic fluid should carry in suspension a propping agent, such as sand, so that once a fracture is formed, it will be prevented from closing off and the fracture created will remain to serve as a flow channel for oil and gas. C. The fluid should be an oily one rather than a water-base fluid, because the latter would be harmful to many formations. D. After the fracture is made, it is essential that the fracturing fluid be thin enough to flow hack out of the well and not stay in place and plug the crack which it has formed. E. Sufficient pump capacity must be available to inject the fluid faster than it will leak away into the porous rock formation. F. In many instances, formation packers must be used to confine the fracture to the desired level, and to obtain the advantages of multiple fracturing. Development of Process As a necessary step in the development of this process, it was deemed advisable to determine if the Hydrafrac fluids were actually fracturing the formation or whether these special fluids were merely leaking away into the surrounding formation. To determine this, a shallow well, 15 feet deep, was drilled into a hard sandstone. Casing was set, the plug drilled, and the well deepened in the conventional manner. A fracturing fluid dyed a bright red was used to break down the formation. Sand mixed with distinctively colored solids was injected into the well with the fracturing fluid to prop open any fracture made in the formation. A simulated gel breaker solution dyed a bright blue was then pumped into the well to determine if the gel breaker would follow the first solution. The results are shown in Figure 1. It was noted that a fracture was formed about the well bore, that the propping agent was transported back into the break, and that the breaker solution did actually follow the fracturing gel out into the fracture. While it is realized that this shallow well test is probably not exactly equivalent to a deep test, the results were interpreted as being a definite indication of what happens down the hole during a Hydrafrac job. Of interest in this connection is an investigation reported by S. T. Yuster and J. C. Calhoun, Jr.' This study, re~orted after the Hydrafrac work was under way, presents some excellent field data supporting the theory of fracturing a formation with hydraulic pressure. METHOD Steps of Hydrafrcu: Process Figure 2 shows a simplified cross-sectional view of a well treated by one version of the process. The first step, formation breakdown, is done with a viscous fluid, usually consisting of an oil such as crude oil or gasoline, to which has been added a bodying agent. Due to availability and price, war-surplus Napalm has been used in the majority of experiments to date. Napalm is the soap which was used in the war to make "jellied gasoline". The next step consists of breaking down the viscosity of the gel by injecting a gel-breaker solution and then after several hours, putting the well back on production. Figure 3 shows diagram-matically, a typical field hookup. The oil or gasoline is unloaded into the 10 bbl. tank shown on the left rear of the truck. This base fluid is picked up by the mixing pump and pumped through the jet mixer, where the granular soap is added. Next it goes into a small mixing tub, from which the high-pressure pump takes suction. The solution is then pumped into the well. The breaker solution is then taken from an extra tank and is displaced into the well immediately following the gel. When required, additional trucks may

Jan 1, 1949

By J. B. Clark

The oil industry has long recognized the need for increasing well productivity. To meet this need, a process is being developed whereby the producing formation permeability is increased by hydraulically fracturing the formation. The "Hydrafrac" process, as it is now being used, consists of two steps: (1) injecting a viscous liquid containing a granular material, such as sand for a propping agent, under high hydraulic pressure to fracture the formation; (2) causing the viscous liquid to change from a high to a low viscosity so that it may be readily displaced from the formation. To date the process has been used in 32 jobs on 23 wells in 7 fields, resulting in a sustained increase in production in 11 wells. INTRODUCTION Need For Process Although explosives, acidizing, and other methods have long been used, there still exists a need for artificial means of improving the productive ability of oil and gas wells, particularly for wells which produce from formations which do not react readily with acids. This paper discusses the development of a hydraulic fracturing process, "Hydrafrac", which shows distinct promise of increasing production rates from wells producing from any type of formation. The method is also considered applicable to gas and water injection wells, wells used for solution mining of salts and, with some modification, to water wells and sulphur wells. Requirements of Process In considering such a possible process, it appeared that certain requirements must be met. Some of these are as follows: A. The hydraulic fluid selected must be sufficiently viscous that it can be injected into the well at pressure high enough to cause fracturing. B. The hydraulic fluid should carry in suspension a propping agent, such as sand, so that once a fracture is formed, it will be prevented from closing off and the fracture created will remain to serve as a flow channel for oil and gas. C. The fluid should be an oily one rather than a water-base fluid, because the latter would be harmful to many formations. D. After the fracture is made, it is essential that the fracturing fluid be thin enough to flow hack out of the well and not stay in place and plug the crack which it has formed. E. Sufficient pump capacity must be available to inject the fluid faster than it will leak away into the porous rock formation. F. In many instances, formation packers must be used to confine the fracture to the desired level, and to obtain the advantages of multiple fracturing. Development of Process As a necessary step in the development of this process, it was deemed advisable to determine if the Hydrafrac fluids were actually fracturing the formation or whether these special fluids were merely leaking away into the surrounding formation. To determine this, a shallow well, 15 feet deep, was drilled into a hard sandstone. Casing was set, the plug drilled, and the well deepened in the conventional manner. A fracturing fluid dyed a bright red was used to break down the formation. Sand mixed with distinctively colored solids was injected into the well with the fracturing fluid to prop open any fracture made in the formation. A simulated gel breaker solution dyed a bright blue was then pumped into the well to determine if the gel breaker would follow the first solution. The results are shown in Figure 1. It was noted that a fracture was formed about the well bore, that the propping agent was transported back into the break, and that the breaker solution did actually follow the fracturing gel out into the fracture. While it is realized that this shallow well test is probably not exactly equivalent to a deep test, the results were interpreted as being a definite indication of what happens down the hole during a Hydrafrac job. Of interest in this connection is an investigation reported by S. T. Yuster and J. C. Calhoun, Jr.' This study, re~orted after the Hydrafrac work was under way, presents some excellent field data supporting the theory of fracturing a formation with hydraulic pressure. METHOD Steps of Hydrafrcu: Process Figure 2 shows a simplified cross-sectional view of a well treated by one version of the process. The first step, formation breakdown, is done with a viscous fluid, usually consisting of an oil such as crude oil or gasoline, to which has been added a bodying agent. Due to availability and price, war-surplus Napalm has been used in the majority of experiments to date. Napalm is the soap which was used in the war to make "jellied gasoline". The next step consists of breaking down the viscosity of the gel by injecting a gel-breaker solution and then after several hours, putting the well back on production. Figure 3 shows diagram-matically, a typical field hookup. The oil or gasoline is unloaded into the 10 bbl. tank shown on the left rear of the truck. This base fluid is picked up by the mixing pump and pumped through the jet mixer, where the granular soap is added. Next it goes into a small mixing tub, from which the high-pressure pump takes suction. The solution is then pumped into the well. The breaker solution is then taken from an extra tank and is displaced into the well immediately following the gel. When required, additional trucks may

Jan 1, 1949

By F. J. Fayers, R. L. Perrine

For many years the problem of increasing ultimate recovery of oil from a reservoir has been a subject of interest to the oil industry. At present, a standard secondary recovery technique is to flood the reservoir with water once natural forces of the system are depleted. The permeability characteristics of the rock, together with interfacial forces which exist between the two fluids and the porous material. allow only part of the oil in the rock formation to be recovered by the water-flooding process. Laboratory experiments have shown that when detergents are added to the flooding water, the flow properties of oil in a porous rock arc improved. This improvement results in greater oil recovery. Even though higher recoveries are obtained using detergents, the extra cost associated with the method may make it economically unsatisfactory. To establish economic feasibility requires experimental laboratory measurement of fluid and rock properties together with a calculational procedure to predict field results. Pilot tests in the field may also be required. This paper presents a mathematical procedure for predicting detergent flood behavior. A number of reasonable simplifying assumptions are made to obtain a tractable system of equations. The resulting method may be regarded as a generalization of Buckley-Lev-crett' theory to solve simultaneously for water saturation and detergent concentration profiles. Consequently this type of calculation can be used in much the same manner as Buckley-Leverett theory is used to evaluate a water flood. The mathematical method employed is the so-called method of characteristics for solving hyperbolic partial differential equations. This application of the method is instructive because several other problems in reservoir analysis may be analyzed in a similar manner. FLUID FLOW EQUATIONS The flow behavior of oil and water without detergent through porous reservoir rock is usually expressed by Darcy's law and a continuity equation for each phase. If gravitational forces are neglected, vrg = kr (s)µr v p rg.........(1) vrg = kr (s)µr v p rg.........(1) ? pa va = F ?/?t (sd) where v is the volumetric flux, k represents permeability, S is saturation, and P the pressure. Fluid viscosity is denoted by 11, p is the density, 4 is porosity, and I the time. The subscripts w and o refer to water and oil. The capillary forces in the system lead to a difference in pressure between phases. This may be expressed by the relation: Pm -P0 =Pc(S).........(5) The capillary pressure? P,, is determined experimentally as a function of saturation. DETERGENT BALANCE EQUATION Addition of detergent to the water phase affects the flow properties of the system. Capillary pressure and relative permeability become functions of detergent concentration, c, as well as fluid saturation. That is: P--P (S,c) and k,,,.- - -- k,,,. At low oil saturation values, the presence of detergent reduces capillary pressure and reduces the relative permeability ratio. Detergents are surface-active and adsorb on rock surfaces. The quantity adsorbed, a, will depend on the concentration c of detergent solution and may also depend on the saturation; thus, a = a(S,c). In this analysis we have assumed that the detergents used are water soluble but not oil soluble, and their movement is therefore restricted to the water phase. The dispersion of detergent in water is neglected by comparison with transfer by flow within the system. Detergent movement is determined by the water flux and adsorption: ? cv m = -F ?/?t (cs + a) We will assume that the quantity of detergent in solution is too small to significantly change water density or viscosity. When the permeability and capillary pres-

By Thomas W. Dawson

THE H. C. Frick Coke Co. has used belt conveyers for handling coal for the last eighteen years but, until recently, only for small tonnage and over short distances. The first installations were outside the mines for distributing coal to various parts of plants. A belt conveyer was put in service at Colonial No. 4 Mine in November, 1906, to carry coal from the main hoisting shaft to a storage bin serving two blocks of beehive ovens on the other side of the valley; it was in constant service until the Colonial No. 4 ovens were abandoned less than a year ago. This conveyor was in an overhead gallery that spanned our sidings and yard tracks and the main line of the Pennsylvania Railroad. It was a crude installation, from the viewpoint of present conveyor engineering practice. It had no mechanical feeding device, the coal simply ran through a gate in the side of a bin on to the belt; but one belt on this conveyor lasted eleven years. This conveyor is about 300 ft. long center, to center of pulleys. It operated at a speed of 250 ft. per min. and carried about 400 tons per day. On this basis, the belt life of eleven years means that not over a million and a quarter tons were carried by the belt. While this is not a large tonnage, the cost per ton was much less than by any previous method in use for supplying coal to ovens located at a distance from the main shaft. The next belt conveyor was installed at Bridgeport Mine in 1907. It carried about the same daily tonnage as the first, delivering from the hoisting shaft to a coke-oven bin. Very few data were kept on this conveyor. It also operated until the coke ovens at the plant were put out of blast and the coal taken to the Clairton byproduct plant by river. In 1916, work was started to equip the Bridgeport, Palmer, Gates, and Ronco mines to load their entire output on, the river for transportation to the Clairton byproduct plant, which was then being built. These mines were all operating at that time and had a large area of coal available for river shipment. The Monongahela Railroad was located between the hoisting shaft and the river at each of these plants and,, therefore, had to be crossed at each location to deliver coal to the river.

Jan 6, 1925

By S. R. Elliott

The principles of the caving system, as they apply to mining soft iron-ore deposits, are well known, as this method has been in use for many years. It is, however, necessary to give a general description of it before describing the Athens method. The shaft and surface equipment should be placed at a sufficient distance from the orebody, so that the caving and pulling of the surface will not disturb the operations of the mine. Levels are started at the proper intervals, and when raises are completed, slicing commences at the top of the orebody and progresses downward. The necessary precautions are taken to avoid the occurrence of large open rooms and it is customary to break sufficient capping to form a mat to prevent heavy falls of ground from crushing through to the lower sublevels and endangering the lives of the workmen. Slicing is continued, and when sufficient width and length are undercut, the capping commences to cave, and in time a settlement occurs at the surface. As soon as this caving commences, the pressure on the timber increases; after it extends to the surface, the amount of pressure has a certain relation to the depth. In other words, the pressure increases with the depth, but not in direct proportion. At great depths, such as are found at the Athens, 2500 ft. (760 m.), the pressure might be so excessive that the cost of keeping working places open would be prohibitive. The actual caving of the surface in a deep mine, with a great thickness of capping, is slow and often takes years to accomplish. After sufficient width and depth have been undercut, the capping starts to break away, but, through arching, large masses of rock fill the opening, support the capping, and retard the continuation of caving. Caving to the surface is, therefore, retarded until either a sufficient thickness of the orebody is removed, or the width and length of the undercut part have been greatly increascd. I wish to emphasize this fact of slow caving, for it is on this principle that the success of the Athens system largely depends. Assuming that work is begun at the top, in this case at an elevation of about 1500 ft. (456 m.); that there is a thick bed of sand saturated with

Jan 1, 1922

It was a pleasure listening to this paper. Gary Works' problems were a lot more extensive than the trunnion bearing problems encountered at the Weirton Steel Division. In our two-vessel shop bearing failures are critical in that with a bearing failure on an operating vessel and the second vessel under rebuild, we are down until the vessel rebuild is completed or the bearing is repaired. The first bearing problem at Weirton occurred after we had been operating three years. The failure occurred during the 8th heat following "bum-in" of the vessel. Immediate steps were taken to change the damaged float bearing without an extensive search for the reason the bearing failed. Once the campaign was run out the bearings were inspected and found to be damaged. Field checks revealed that the bearing pedestals were not properly located and as a result the freedom of the float bearing was restricted. The trunnion pin end to end dimension had decreased due to distortion and deflection in the trunnion ring. These dimensions were within tolerances. The damage to our bearing was similar to that in the exhibits from U.S. Steel-Gary Works. Steps taken to correct what was found in the field checks were as follows: 1. The pedestals were relocated to center the bearings. 2. 4" diameter pins were installed to locate the housing in the pedestals. 3. The bearing pedestals were opened up to allow the bearing housing to move slightly in the pedestal. 4. Lubrication fittings for greasing between the bearing housing and the pedestal were installed.

Jan 1, 1972

By D. Murgue

The circulation of air in underground workings is subject to a gradual and continuous reduction of its pressure, from intake to outlet, caused by the friction between it and the more or less rough and uneven surfaces of the passages. For comparison with the flow

Jan 1, 1894

By Geo Ashley

THE following paper is intended to be suggestive only, and to open the way for discussion and further observation. Its preparation was requested only two days before the time limit set for the submission of the papers comprising this symposium. Thus no time existed for detailed studies so it is largely a memorandum of such facts as have come incidentally to the notice of the writer in the study of coal in the field. The field study of sulfur in coal has received very little special attention or description from coal students. The presence of sulfur concretions is noted in hundreds of descriptions, and certain benches of a coal bed may be described as "sulfury" or the presence and position of sulfur bands may be noted in coal sections in connection with sampling. It may be accepted that some sulfur is present in all coal. The amount varies greatly in different regions, in different beds, and in the same bed in different areas. The anthracite of Rhode Island comes the nearest of any coal known to the writer of being free from sulfur, several analyses of that coal showing less than 0.1 per cent. Subbituminous coals in Colorado in a few places have close to 0.2 per cent. of sulfur on the dry-coal basis and in other states subbituminous coals approach this lower limit. Bituminous coals seldom run under 0.4 per cent. of sulfur on the dry basis, though in a few places dry bituminous coals in Colorado and Washington have between 0.3 and 0.4 per cent. The better known bituminous coals have almost everywhere over 0.4 per cent. The best of the Pocahontas and New River coals run close to 0.4 per cent., but there is very little commercial coal in Pennsylvania, Ohio, Indiana, Illinois, Kentucky, or the other states that runs under 0.5 per cent. on the dry basis. From these minimum figures, the amount will range up to 5 or 6 per cent. or higher if visible sulfur is not excluded. It must be remembered that the usual -analysis of a coal bed is not intended to give the total proportion of sulfur in the bed but the amount in the coal after the removal of the more obvious and larger sulfur masses.

Jan 9, 1919

By E. T. Dumble

For many years there have been occasional reports of the discovery of gold from a belt of the coast country of Texas which is underlain by deposits belonging to the lower Eocene. For the most part they have been treated as newspaper reports and no examination or record of them has been made. Among such, it may be mentioned that in 1896 there was a flurry over reported gold-discoveries west of Luling and elsewhere in this belt, and in 1903 some prospect-shafts were sunk on the Gon-zales branch of the Galveston, Houston & San Antonio railway, 3 miles below Harwood. During 1912, further discoveries have again brought the matter to our attention, and it may be of interest to record the facts as we have found them. Some years ago specimens were sent me, which were said to have been taken from certain beds on Gazley creek, and concentrated by washing in a rocker. In them were several particles of gold sufficiently large to be visible to the eye. Under the microscope they showed to be, with few exceptions, sharp cornered, and not rounded as is usual with placer-gold. They were not filings, however, but their sharpness seemed rather to be due to a recent freeing from their matrix. One or two grains were rusty, and one copper-hued, but the most of them were tolerably bright. On examining the material of the samples small grains or fragments were found, of a yellowish brown color, which seemed to be of a finely-granular structure—possibly a sandstone. In these fragments I found particles of gold, one of them being large enough to be visible without a lens. Gazley creek empties into the Colorado river just north of Smithville, and for a few miles north of that place its banks show, beneath the deposits of more recent materials, the sands and clays of the Lignitie division of the Eocene, with lignite, shells of iron, etc.

Jan 1, 1913

By A. T. Tye

REGARDING the results of preferential flotation at Cananea, Weinig has stated that "The concentrating mill of the Cananea Consolidated Copper Company at Cananea, Mexico, furnishes an excellent example of modern flotation practice. The complete figures are given because they present so forcibly the advantages of modern selective flotation."' L. 0. Howard notes that "Perhaps the outstanding example so far published of improvements in results through the use of selective flotation is that at Cananea, Mexico."2 The following notes indicate the conditions under which the results were obtained at Cananea; also the effect of preferential flotation at the concentrator and at the smelter. In the majority of cases the full benefit of selective flotation is not fully realized, as the concentrates are shipped from the mill to smelters owned by other companies. The saving made at a certain concentrator by this method of flotation may be well understood but the saving resulting at the smelter from the results of preferential flotation at the mill is not so apparent, as the data are contained in the smelting records of some other company. Even at the smelter the great gains following preferential flotation may not be noted, as a variety of ores and concentrates from various sources are received and the difference from the changed concentrator operations of a certain mill may be obscured. As noted by Professor Weinig and Professor Howard, the results obtained at Cananea brought about a veritable metallurgical revolution at the smelter.

Jan 1, 1927

By B. Egeberg

BRITANNIA metal is a white alloy consisting primarily of tin and antimony, the tin greatly predominating. The alloy usually contains a small amount of copper and occasionally very small amounts of one or two, other metals, such as bismuth, zinc, and lead. It is capable of being cold-rolled, it takes a high polish, and it is fairly noncorrosive; properties which make it a popular metal for many household and traveling utensils. Britannia metal is similar in many respects to pewter and has largely replaced pewter in the arts, but it should not be confused with that alloy, because pewter is essentially a tin-lead alloy, while Britannia is a tin-antimony alloy. In view of the fact that so little has been published concerning Britannia metal, the authors feel justified in presenting the results of their investigation, particularly since the behavior of this alloy under cold rolling and heat treatment differs so greatly from that of other metals and alloys. The old craftsman, engaged in the making of ornaments or tableware, heated the cold-rolled sheet metal or his finished product to a straw color corresponding to about 375° F., claiming to produce thereby a harder and more rigid article. The fact that possibly led him to this heating was that a reheated article or sheet made from Britannia metal has a distinct metallic ring when struck a sharp blow, whereas an unheated article or sheet has a leady, dead note. No doubt he has associated the metallic ring with a greater rigidity and strength, and justly so, as will be seen later.

Jan 1, 1928

By J. F. Wilkinson

A high degree of accuracy is often required in mine-surveying, in order that expensive mining work may not be misdirected. The making of underground connections by drifts or shafts located as the result of surveys presents a crucial test of correctness not usually involved in any other class of surveying. In view of these considerations, the present notes and description of a survey made in June, 1890, for the San Francisco shaft of the New Almaden quicksilver-mines, may be of interest to members of the Institute who are surveyors. The purpose of this survey was to locate on the surface a vertical 2-compartment shaft (3.5 by 7 ft.), to connect with another vertical shaft, of practically the same size, which had been sunk a number of years before from an adit-level about 240 ft. vertically below the surface, to a deeper, so-called 600-ft. level. It will be seen, of course, that the most important matter was to secure an exact coincidence in vertical line, so that the resulting continuous vertical shaft from the surface should have no offset or irregularity at the point of junction between its two parts. The levels were of less importance; but, as the hoisting-works were to be placed in position and the new shaft permanently timbered from the start, its correct alignment was an essential requirement. The important features of the work, therefore, were the methods used in determining with certainty : 1. That the shaft was located in the right place in a general way; 2. That the ordinary inaccuracies of linear and angular measurements were so reduced as to insure correctness of location within certain defined and allowable limits. Instruments.—Thc instruments used were: a Buff and Berger transit-theodolite, with a 6-in. horizontal plate, reading to 10 seconds; a Heller and Brightly Y-level; a Chestermán steel tape, graduated in tenths and hundredths of a foot; and New York leveling-rods, graduated to thousandths of a foot.

Jan 1, 1901

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 A. S. Michaels, R. S. Timmins

A study of the effect upon oil recovery from an un-consolidated porous medium of chromatographic transport of selected reverse-wetting additives during water displacement is described. Flow tests were performed on hydrocarbon oil-saturated sand columns (containing connate water) into which small volumes of short-chain aliphatic amine solutions were introduced during water flooding. Concurrently, meusurements of oil-silica contact angles, oil-water interfacial tensions and oil-water distribution coefficients were measured us a function of additive concentration. Certain treatments were found to cause a slight reduction in oil recovery, while others produced a significant increase (up to 50 per cent of the normtzl irreducible rninimum oil saturation). Recovery eficiency was correlated most satisfactorily with the maximum degree of reverse wetting produced during additive transport; conditions which resulted in only mild oil wettability of the sand reduced recovery, while those favoring strong oil wetting increased recovery. A mechanism of reverse-wetting additive action during chromatographic transport is developed which ascribes the results to transient changes in oil-solid contact angle during flow, with consequent release of oil trapped by capillary forces. Implications of these observations with regard to improved waterflood efficiencies are discussed. INTRODUCTION The need for finding improved methods of oil production is amply illustrated by the large volume of oil considered economically unrecoverable by existing production practice. Water flooding has long been an excellent method of secondary recovery. However, even in those areas of a formation which are well swept by a water flood, 20 per cent or more of the oil remains trapped within the formation and is not recovered. This trapping of oil within the pores of the rock structure results primarily from interfacial forces. If these interfacial forces were altered, it is possible that the trapped oil could be released and recovered. The addition of surface-active agents to a water flood to alter the interfacial properties of the oil-water-solid system has received considerable attention as a method of increasing oil recovery. Studies of surfactant treatment have yielded varied and, in some cases, apparently conflicting results. Increased oil recovery using surface-active agents has been reported by a number of investigators. Others have found that use of surfactants in a water flood either has no effect upon oil recovery or decreases it. Since surface-active agents tend to alter the formation wettability and oil-water interfacial tension simultaneously, several investigators have tried to determine the role these two factors play in oil recovery. Data have been presented which indicate that the most desirable condition for the solid surface is strongly water-wet. Other results indicate that, although breakthrough recovery may be less, the greatest ultimate recovery is obtained when neutral wettability prevails.", " The desirability of low interfacial tension seems to depend upon the wettability of the formation. Reports of higher recoveries, when the interfacial tension is high in a water-wet system and low in an oil-wet system, are at odds with reports of increased recovery in water-wet systems when surfactants which decrease the interfacial tension are added to the water flood. A review of previous work studying the effects of using surface-active agents in a water flood shows that these agents produce widely different effects and that opinions as to the role of the various interfacial properties are diverse. The consensus, however, is that the interfacial properties are quite important in the displacement of oil from a porous medium by water. Even in those investigations where appreciable increases in oil recovery resulted from treatment with a surface-active agent, economic considerations generally made practical application of the treatment unattractive because surfactants tend to be adsorbed within the formation. This adsorption would necessitate using large quantities of surfactant if all of the flood water were treated to contain a given surfactant concentration, even if this concentration were quite low. Preston and Calhoun suggested that the principles of chromatography could be applied to the use of surface-active agents as a means of increasing oil recovery. A small volume of surface-active material is injec-

By Charles V. Seastone

The hydro-electric plant of the Peninsular Power Co. is located at what is commonly known as Lower Twin Falls on the Menominee River. This location is about 3I/2 miles north of the city of Iron Mountain, Mich. The principal points of delivery of electric energy from this plant are in the mining regions adjacent to Florence, Wis., and Iron River, Mich., and in the cities of Iron River and Iron Mountain. The hydro-electric plant at Twin Falls and the substation of the Iron Mountain Electric Light & Power Co, are connected by a 6,600-volt transmission line carried on steel towers and steel poles, the latter being used within the city limits. The plant at Twin Falls and the substation at Iron River, about 36 miles distant, are connected by a 66,000-volt, duplicate, three-phase transmission line, supported on steel towers. At Iron River, are located a 1,500-kw. auxiliary steam plant, and the substation, from which the current is distributed to the mines in this vicinity. A description of the auxiliary plant, main and customers' substations, and of the main and secondary transmission lines, follows later in this paper. General Layout The relative location of the dam, forebay, and power house will be understood by referring to Fig. 1. The dam is constructed on a ledge of solid rock which forms Lower Twin Falls. This rock ledge offers an excellent location in that the height of the dam, and therefore the amount of concrete, are thereby reduced, and also in that practically no pumping was required in unwatering the dam site. The maximum head provided by the dam is 44 ft., with an average working head of from 40 to 42 ft. The other structures, including the substructure of the power house,

Jan 1, 1915

By G. A. Vissac

The only fine coal washer with proved automatic controls, the feldspar jig is capable of good efficiencies even at low separating gravities, handles a variety of products, and treats 150 tph and over. IN continental Europe the feldspar jig is used almost exclusively for cleaning the fine sizes of coal; it operates with an artificial bed, made up generally of pieces of feldspar or of any other hard and heavy rock with good cleavages. A primitive form of this machine requiring close supervision was used in this country years ago, but output was small. The modern machines are generally air-pulsated Baum-type jigs, with capacities up to 150 tph, and treat sizes from % in. to 0, usually previously dedusted or deslimed. These jigs are equipped with very accurate and sensitive automatic controls insuring satisfactory operation even at low separating gravity and with feeds irregular in quality and quantity. This paper will deal more particularly with coal cleaning separation, but the technical studies apply equally to all minerals. Theory of the Feldspar Jig To understand fully the operation of the feldspar jig and to appreciate its potential value, it is necessary to measure and analyze the motion of small particles of various specific gravities, falling in various media, under various conditions. As no practical formulas were available for that purpose, the writer has developed new theories and established new sets of formulas, which cannot be demonstrated here. They are applicable to all minerals and to many problems of coal or mineral concentration. These formulas do not pretend to absolute accuracy, but results, tested by comparison with experimentally recorded data, are sufficient for practical purposes, as they give definite indications of trends, relative values, and order of magnitude of the many factors involved. For pulsating motions no earlier formulas are available. In the case of continuous currents or motions, such formulas as Rittinger's, Allen's, or Stokes', over a hundred years old, apply only to special shapes and sizes of particles, involve factors and coefficients difficult to measure or appreciate, and deal only with free motions. They are of little use in solving practical problems. Units used with the formulas presented here are in the CGS system. Lateral friction and suction have been taken into account according- to methods currently used in aerodynamics, and only hindered motion is dealt with. As the feldspar jig is primarily intended to create a fluid bed condition, the mixture of fluids and solids obtained is homogeneous, and the apparent specific gravity of the separating medium is calculated accordingly. For instance, if 20 pct of the volume is coal and shale, with an average of 1.60 sp gr, in a liquid of 1.10 sp gr, the actual specific gravity of the separating fluid is 0.80 x 1.1 + 0.20 X 1.6 = 1.20. The fundamental equations are as follows: The general motion of a particle falling in a medium of specific gravity equal to u, hindered motion. is dv/dt = g/Ls [ L (s-u) - u/g v2 [1] g = 981 cm per sec, acceleration of gravity, and L = thickness of the particle of specific gravity (s) and velocity (v). The initial acceleration dv/dt = g (1-u/s ) [2] is a function of the specific gravity of the particle, only for a given medium, and independent of its dimensions—an ideal separating condition. The terminal velocity Vt = gxL- (s-u)/u, [3] for a given value of u, is a function of s and L. Two particles, L, s, and L2 s2, are said to be equivalent if they have the same terminal velocity, and accordingly L1/L2=s2-u/s1-u. [4] Two such particles cannot be separated by continuous currents, in any concentrating device. Because the initial accelerated motion, which provides for efficient separation, is followed by a constant velocity, which has a limiting effect, it is essen-

Jan 1, 1956

By W. J. Millard

It is well known that the excellent mica from Brazil played a most vital role in World War 11. Increased production from Brazil was necessary and with the assent of the Brazilian Government engineers from the united' States went down to study the problem. One of the means advocated by a former Chief of Metals and Minerals Branch of the Board of Economic Warfare, Mr. Carl Schwegler, was the use of stripping machinery. On a pegmatite dike favorable for stripping, a small number of miners could produce as much mica per day as an underground mine employing many times the same number of men. Type of Deposit Favorable The most favorable type of pegmatite for stripping is that which lies more or less parallel to the surface of the slope of a hill. Pegmatite dikes that cut directly into a hill are not suitable for stripping except where a long outcrop extends along the slope. Then just the outcrop could be stripped to some advantage. The ratio at no time should be greater than 1: 3; i.e., I cu. m. of pegmatite to 3 cu. m. of waste, unless the pegmatite was extremely rich throughout the dike. The Economics of Stripping When a mineral is badly needed to win a war, not too much heed can be paid to costs. The object is to produce rapidly and in quantity. Again, a deposit containing a superior grade of mica may be worked although the pegmatite is more costly to work than another deposit containing a considerably greater amount of poor-grade mica. For example: one deposit may have a little mica that will run 11 per cent good stain and better when trimmed and contain 2 kg, of crude mica per cubic meter of pegmatite, while another may run 0.2 per cent of good stain and better, and have a mica content of 10 kg. per cubic meter. A number of stripping projects were found in the vicinity of Raul Soares, Minas Gerais. These were sampled in the various old workings by cutting out a cubic meter of pegmatite and saving the usable mica. Because of the proximity to the surface of most stripping projects, about 34 per cent only of the mica is good for trimming. The other 66 per cent is too badly weathered to be of use. In Table I are given data collected on five properties near Raul Soares. In Table I, "value per cubic meter of pegmatite" means the value of the qualified mica obtainable. This does not include the half trimmed and splittings. By "value per cubic meter of matter" is meant the value of the qualified mica per cubic meter of material excavated; i.e. both waste and pegmatite. This is the figure that should be used to determine whether the operation will be profitable or not, as the cost of stripping is about $0.14 per cubic meter. With new machinery not subject to breakdowns, the cost per cubic meter should be around $0.10 to $0.15. To this should be

Jan 1, 1948