Search Documents

By R. R. Byran, M. H. Kuryla

The Compania de Real del Monte y Pachuca started a 10-ton pilot plant in March, 1906. The distinctive features of the first cyanide installations at Pachuca were: grinding in cyanide solution, all-sliming and filtration of ore in which silver constituted the major value. Loreto started with a 300-ton " all-sliming" plant, using jaw crushers, grinding in stamps, Chilean mills and pebble mills in cyanide solution, concentrating with Wilfley tables and Johnson vanners, classification by cones and Dorr classifiers, intermittent thickening by decantation, mechanical agitation in flat tanks by stirrers and centrifugal pumps, filtration in Butters filters and precipitation by zinc shavings. The "San Francisco" mill No, 1 was contemporaneous, using a rather similar flow sheet. We shall trace the main developlnents in the three large mills of the district to their present practice. Developments in Large Mills of District Crushing and Grinding.—The trend of development in this part of the work has been the same as throughout the milling world; via., all increase in the degree of comminution of the ore in dry-crushing machines, the advance from pebble mill to rock mill and then to ball mill and the elimination of the stamp battery through the encroachment upon its field on the one side by finer dry crushing and on the other by more efficient wet grinding. The single-stage crushing in jaw type crushers, used at the start, has been replaced by two stages; at first, both stages by gyratory type and later the present practice, which is the same in all three mills, consisting of gyratory as primary followed by cone as secondary and delivering a product that may be rated at 56 to 1 inch. Primary wet grinding, at first performed by stamps and Chilean mills, is now by hall and/or rod mills; present practice differing widely in the three mills. Santa Gertrudis uses a 7 by 15 ft. rod mill, San Rafael

Jan 1, 1935

By E. H. Lee, F. J. Fayers

Problems in reservoir analysis can usually he cupressed in terms of a system of nonlinear partial difjerential equations. A rnethod for .setting physically reasonable boundary conditions for these systerrls by ayplication of the theory of characteristics is discussed. A short description i.c. given of the technique for finding chnmcteristics of general first order and second orrler equations. Specific examples are quoted jrorn eqrrations occurring in theoretical reservoir studies. The princip1e. ossocicred wit11 the use of chnracteristic to set physically realistic boundary conditions me developed, and thr method is discussed in terms of boundary condition for the noncupillary, compressible, two-phase flow problen: jor the cupillary, ir~cowlpressible, two-phase flow problems for the tlrtergent flooding prohlenl; as for the compressible. noncapillary, two-phase flow pro11letn. INTRODUCTION In most problcms in reservoir analysis the physical situation is described by a system of nonlinear partial differential equations. The general solution to the set of equations usually comprises a wide range of functions ancl a particular solution is normally selectetl by applying suitable boundary conditions to the problem. In some cases it is clear from the physical situation what form the boundary conditions should take, but it is usually desirable to have an independent mathematical check of the suitability of the chosen conditions. From the mathematical standpoint, a system of partial differential equations with boundary conditions is said to be properly set if the combination determines a unique solution which is continuously dependent on the equation and the boundary conditions. Such a solution is sometimes termed "reasonable". In investigating the properties of the mathematical representation, it is useful to determine the structure of the system by the application of the theory of characteristics. This theory determines in the space of the independent variables, lines or surfaces which play a special role in thc system's behavior. The characteristics determine the possibility and nature of the propagation of discontinuities in the derivatives of the dependent variables. Along the characteristics certain differential relations hold which for some problems allow a so- lution to be obtained analytically. In the case of hyperbolic equations the characteristics can bc used as 3 basis for a numerical solution. If a complicated nonlinear system is to be solved, a study of behavior of the characteristics will indicate what boundary conditions should be chosen. By using the method of characteristics, several advances have rccently been made in solving reservoir engineering problems. Sheldon, Zondek and Cardwell' have discussed how the the method may be used grap-phically to solve the incompressible two-phase displaccmerit problem when the gravity term is included in the equations. Fayers and Perrine' have applied the method to study the equations representing detergent flooding. When compressibility and solution-gas effects are introduced into the two-phase flow problem, the equations and their characteristics become more complicated. It will be seen that in this problem the characteristics are useful for indicating a reasonable set of boundary conditions but cannot readily be used to compute a numerical solution. This problem has been solved on the IBM 701 using normal finite difference methods hy West, Garvin and Sheldon." The material to be prcscntcd in this report is divided into three sections. The first discusses the determination of the characteristics of first and second order partial differential equations; the second describes the selection of suitable boundary conditions by the application of the principle that the future cannot affect the past; the third discusses the use of characteristics for setting the boundary conditions of the two-phase solution-gas flow problem. A useful introduction to the method of characteristics has been given by Hildebrand.' A summary of the method will be given in this section of the paper. The First Order Equation The quasi-linear equation of first order is It is linear in the partial derivations of z. The properly linear equation has the form The characteristics of are curves along which the

By W. H. Bassett

THE modern smelting and refining of copper is distinctly an American development. The present demand for sound and perfect castings for rolling is due to the development of American industry. Prac-tically every article made from sheet metal or, for that matter, from any form of metal is made by mass produc-tion methods. Faulty material disturbs the orderly sequence of operations and in addition requires expen-sive inspection and unbearable rejection of finished product. This demand, therefore, is positive and will have to be met. Some mines produce ore that can be smelted and re-fined without the electrolytic process into satisfactory copper for the wrought metal industry, and some of these ores carry small amounts of impurities that are of use in hardening and toughening the copper. Most of the copper ore mined contains impurities that must be removed and, fortunately, precious metals which are separated at the same time make this re-moval profitable. The modern electrolytic refineries have their methods so well under control that the product meets all re-quirements without question if properly fire refined and cast. The "if" in this case is important, because there is evidence of carelessness or want of control at times in the material from some of the producers. It is nec-essary that the melted cathodes should be saturated with oxide to dispose of sulfur and that the copper should then be poled to the proper pitch or set. Sometimes statements leak out to the effect that it is unnecessary to oxidize completely the molten cathodes and a little less rabbling saves poles, which are expensive. The re-sult is that the rolling mill gets porous castings and produces seamy or slivered sheets or strips. The condition of the molds, their temperature, and the temperature of the metal are all important to good copper cakes, wedges, or wire bars. Cracked, and burned molds leave rough places and porous spots. Molds which are out of shape, or cracked, make shrink-age cracks which gap open when the castings are hot-rolled. Dampness means porosity. Drops of oil mean porous or honey-combed areas. Poor or irregular dress-ing means mold wash in the castings. Cold copper or slow pouring means cold sets.

Jan 4, 1928

By Dever C. Ashmead

FRom time to time metal-mine engineers have inquired why anthracitc mines and their preparators are rarely operated on the two or three-shift basis. The subject may be approached as affecting: labor, development, the underground workers, the preparator, the outside workers, capital, the supply account, power consumption, the storage of coal over various shifts, railroad car supply, and the market. Labor From the start, the adoption of a plan of three full-shift operations in a day would cause difficulty with the colliery employees, for they have never worked on that plan and would show their resentment by suspending work. Even if they could be induced to work according to this schedule they would not be as efficient, for they would be working more or less unwillingly at hours at which they are accustomed to rest. Operation on a three-shift basis would necessitate triple manning of each working place, and dissensions would arise between the men, for each shift would claim that the preceding shift had taken undue advantage and had not left as favorable conditions as it had found. To obviate these disputes it might be [necessary to let out the work to a contractor, who would hire his helpers to mine out the chamber, or breast. The state mining law requires that a miner be put in charge of each working place. To conform with this provision he would have to hire three helpers and two miners to mine the breast. The labor unions have been trying to abolish the subcontractor in mine work and any method of working that would cause his return, however innocent in purpose, would result in labor disturbances. It might be possible to form partnerships of three miners working a place together, but these men would be quite likely to have frequent dissensions as to the proportion of work performed by each shift. Only

Jan 1, 1923

By Dever C. Ashmead

FRom time to time metal-mine engineers have inquired why anthracitc mines and their preparators are rarely operated on the two or three-shift basis. The subject may be approached as affecting: labor, development, the underground workers, the preparator, the outside workers, capital, the supply account, power consumption, the storage of coal over various shifts, railroad car supply, and the market. Labor From the start, the adoption of a plan of three full-shift operations in a day would cause difficulty with the colliery employees, for they have never worked on that plan and would show their resentment by suspending work. Even if they could be induced to work according to this schedule they would not be as efficient, for they would be working more or less unwillingly at hours at which they are accustomed to rest. Operation on a three-shift basis would necessitate triple manning of each working place, and dissensions would arise between the men, for each shift would claim that the preceding shift had taken undue advantage and had not left as favorable conditions as it had found. To obviate these disputes it might be [necessary to let out the work to a contractor, who would hire his helpers to mine out the chamber, or breast. The state mining law requires that a miner be put in charge of each working place. To conform with this provision he would have to hire three helpers and two miners to mine the breast. The labor unions have been trying to abolish the subcontractor in mine work and any method of working that would cause his return, however innocent in purpose, would result in labor disturbances. It might be possible to form partnerships of three miners working a place together, but these men would be quite likely to have frequent dissensions as to the proportion of work performed by each shift. Only

Jan 1, 1923

By Charles Fettke

The deposits described occur in a belt starting 1 ½ miles east of Juncos and extending 6 miles in a southeasterly direction. They are of the contact metamorphic type, being associated with a limestone and calcareous tuff that is interbedded with andesite tuffs and andesites which have been invaded by a quartz diorite intrusion. Of the fire occurrences examined, the largest can be traced for a horizontal distance of 2000 ft. No mining has, been done, but some of the outcrops lead to the belief that deposits of commercial size are present. IN CONNECTION with the gathering of data for a report on the geology of the Humacao district of southeastern Porto Rico during the summer of 1916, under the auspices of the Scientific Survey of Porto Rico and the Virgin Islands, conducted by the New York Academy of Sciences, the writer had an opportunity to make a brief examination of the magnetite deposits of the eastern portion of the island. Inasmuch as these deposits have attracted some attention as possible future sources of iron ore, and as there is only scanty reference made to them in literature,1 a short description based on this reconnaissance survey was deemed to be worthy of record. The magnetite deposits of eastern Porto Rico occur in association with a belt of limestone, trending approximately S 53° E, which begins 1 ½ miles east of Juncos and can be traced for about 6 miles toward the coast. Four outcrops of magnetite were observed, which are designated

Jan 2, 1924

By John C. Draper

The principal object of an underground coal mine transportation sys tem is to move coal from the face where it is produced to the outside of the mine where it is prepared for market. In addition to the movement of coal, a transportation system must also move supply materials to the inside; it must move men in and out of the mine ; and it must move rock and other debris out of the mine for disposal. Usually, mine haulage is divided into three categories named for the various areas of the mine served: 1) Face Haulage. This is used at face from the mining machine to the intermediate transport system. 2) Intermediate or Secondary Haulage. Generally this is used between face haulage and main haulage. Sometimes this is merely an extension of the main haulage. 3) Main Haulage. This extends from the secondary haulage to the outside and is usually either a track or conveyor system, sometimes a combination of both. Transportation modes of coal in the various areas pose different problems, but the whole system must be synchronized. For instance, at the face the coal should be removed quickly from the various places to facilitate the movement of machines, whereas the intermediate system just passes the same coal on to the main transportation system. Selection of the transportation system must be based on the seam height, mining methods used to extract the coal, capacity required, ease of coal handling, and haulage efficiency. When driving rooms, mine cars can be used. They often simplify supply haulage and rock handling because they can also handle these items. Conveyors could be used and would have a greater haulage capacity but they cannot handle supplies easily or segregate the rock. When using a different mining method, such as longwall, mine cars cannot be used because there is not sufficient space to move the cars at the face nor can the cars haul the coal without delays which would cause excessive losses in production. As for ease of handling

Jan 1, 1973

By M. B. Riordan

A surface indicating pressure, temperature and flow instrument that ernploys variable frequency sensing elements has proved useful in evaluating flow characteristics of wells. Relative productivity of individual oil and gas sands in a given well can be analyzed at several back pressures. The variable frequency sensing elements are an improvement in sensitivity and accuracy and make possible observation of temperature and pressure variations that have not been possible heretofore. The surface indicating featuere results in a more direct approach to solving problems and eliniinate; many assumptions. All three subsurface factors are evaluated, and correlation between them results in a direct means of analyzing reservoir. and well conditions. Surveys have been used to evaluate well performance. locate gas entry In high ratio wells and to investigate gas injection and water flooding conditions. INTRODUCTION In a flowing well that is open to a multiple number of producing sands with varying characteristics. it is valuable to know which sands are producing fluid at a given back pressure and in what relative quantity. Core studies could qualify an interval as productive, and reserves would be computed on this basis. Unless the well is produced so that the interval does contribute. irreparable damage to the interval can occur. It is generally accepted that the optimum condition of pro-

Jan 1, 1951

By M. B. Riordan

A surface indicating pressure, temperature and flow instrument that ernploys variable frequency sensing elements has proved useful in evaluating flow characteristics of wells. Relative productivity of individual oil and gas sands in a given well can be analyzed at several back pressures. The variable frequency sensing elements are an improvement in sensitivity and accuracy and make possible observation of temperature and pressure variations that have not been possible heretofore. The surface indicating featuere results in a more direct approach to solving problems and eliniinate; many assumptions. All three subsurface factors are evaluated, and correlation between them results in a direct means of analyzing reservoir. and well conditions. Surveys have been used to evaluate well performance. locate gas entry In high ratio wells and to investigate gas injection and water flooding conditions. INTRODUCTION In a flowing well that is open to a multiple number of producing sands with varying characteristics. it is valuable to know which sands are producing fluid at a given back pressure and in what relative quantity. Core studies could qualify an interval as productive, and reserves would be computed on this basis. Unless the well is produced so that the interval does contribute. irreparable damage to the interval can occur. It is generally accepted that the optimum condition of pro-

Jan 1, 1951

By W. N. Poundstone, P. C. Thakur

Introduction Horizontal drilling in coal mines is a relatively new technology. The earliest recorded drilling in the United States was done in 1958 at the Humphrey mine of Consolidation Coal Co. for degasification of coal seams. Spindler and Poundstone experimented with vertical and horizontal holes for several years. They concluded in 1960 that horizontal drilling in advance of underground mining appeared to offer the most promising prospect (for degasification) but effective and extensive application would be dependent upon the ability to drill long holes, possibly 300 to 600 m, with reasonably precise directional control and within practical cost limits (Spindler and Poundstone, 1960). Mining Research Division of Conoco Inc., the parent company of Consolidation Coal Co., began a research program in the early 1970s to achieve the above objective. The technology needed to drill nearly 300 m in advance of working faces was developed by 1975 and experiments on advance degasification with such deep holes began in 1976. Preliminary results of this research have already been published (Thakur and Davis, 1977). To date nearly 4.5 km of horizontal holes have been drilled for advance degasification and earlier results were reconfirmed. In summary, these are: • The greatest impact of these boreholes was felt in the face area where methane concentrations were reduced to nearly 0.3% in course of two to three months from original values of nearly 0.95%. • The methane concentration in the section return reduced to 50% of its original value immediately after the boreholes were completed, indicating a capture ratio of 50%. • The total methane emission in the section (rib and face emission plus the borehole production) did not increase but rather gradually declined with time. • Initial production from 300 m deep boreholes in the Pittsburgh seam varied from 3 m3/min to 6 m3/min but then slowly declined as workings advanced inby of the drill site (well head) exposing a larger surface area parallel to the borehole. Encouraged by these results, it was decided to design a horizontal drilling system that would be mobile and compatible with other face equipment. A mobile horizontal drill can be divided into three subsystems: the drill rig, the drill bit guidance system, and borehole surveying instruments. The drill rig provides the thrust and torque necessary to drill 75- to 100-mm diam holes up to 600 m deep and contains the mud circulation and gas cuttings separation systems. The drill bit guidance system guides the bit up, down, left, or right as desired. Borehole surveying instruments measure the pitch, roll, and azimuth of the borehole assembly. Additionally, it also indicates the thickness of coal between the borehole and the roof or floor of the coal seam. Thus, it becomes a powerful tool for locating the presence of faults, clay veins, sand channels, and the thickness of coal seam in advance of mining. In recent years, many other potential uses of horizontal boreholes have come to light, such as in situ gasification, longwall blasting, improved auger mining, and oil and gas production from shallow deposits. The purpose of this paper is to describe the hardware and procedure for drilling deep horizontal holes. The Drilling Rig [Figures 1 and 2] show the two components of the mobile drilling rig: the drill unit and the auxiliary unit. The equipment (except for the chassis) was designed by Conoco Inc. and fabricated by J. H. Fletcher and Co. of Huntington, WV. The drill unit. It is mounted on a four-wheel drive chassis driven by two Staffa hydraulic motors with chains. The tires are 369 X 457 mm in size and provide a ground clearance of 305 mm. The prime mover is a 30-kw explosion-proof electric motor which is used only for tramming. Once the unit is Crammed to the drill site, electric power is disconnected and hydraulic power from the auxiliary unit is turned on. Four floor jacks are used to level the machine and raise the drill head to the desired level. Two 5-t telescopic hydraulic props, one on each side, anchor the drill unit to the roof. The drill unit houses the feed carriage, the drilling console, 300 m of 3-m-long NQ, drill rods, and the electric cable reel for instruments. The feed carriage is mounted more or less centrally, has a feed of 3.3 m, and can swing laterally by ± 17°. It can also sump forward by 1.2 m. The drill head has a "through" chuck such that drill pipes can be fed from the side or back end. General specifications of the feed carriage are: [ ] The auxiliary unit. The chassis for the auxiliary unit is identical to the drill unit but the prime movers are two 30-kW explosion proof electric motors. It is equipped with a methane detector- activated switch so that power will be cut off at a preset methane concentration in the air. No anchoring props are needed for this unit. The auxiliary unit houses the hydraulic power pack, the water (mud) circulating pump, control boxes for electric motors, a trailing cable spool, and a steel tank which serves for water storage and closed-loop separation of drill cuttings and gas.

Jan 1, 1981

By A. Gatti, R. L. Fullman

A very fine dispersion of aluminum oxide is produced by internal oxidation of solid-solution alloy of 0.14 pet A1 in Ag. The particle size of the aluminum oxide is approximntely 50 to 100A in radius. The yield strength of the alloy is increased markedly by internal oxidation. A further increase in strength is produced by cold working the internally oxidized alloy. Recrystallization is retarded by the finely dispessed aluminum oxide particles, so that the strength increase resulting from cold work is retained on annealing at temperatures 14 to about 700°C. MANY workers'-3 in the past have studied various aspects of the internal oxidation of aluminum-silver alloys. This paper is an extension of these studies with emphasis placed on the effect of time and temperature of annealing on the strength of these alloys after oxidation and subsequent cold working. Two general conditions are necessary to internally oxidize an alloy. First, oxygen must diffuse through the base material more rapidly than does the addition; otherwise oxidation will take place as a surface layer. Secondly, the affinity of oxygen for the addition must be greater than for the base material. After internal oxidation of certain alloys takes place, a marked increase in hardness accompanied by higher yield stress and improved creep properties is noted, presumably as a result of the highly dispersed oxide within the base material. Meijering and Druyvesteyn1 also noted that the internally oxidized portion of a partly oxidized alloy failed to recrys-tallize under annealing conditions that led to coinplete recrystallization of the unoxidized part. EXPERIMENTAL-METHODS AND PROCEDURES Few alloys can be made to contain a second phase that is extremely stable at high temperatures. Silver plus aluminum in solid solution was chosen for these internal oxidation studies because of the high rate of oxygen diffusion through silver and the very stable nature of aluminum oxide. Two alloys were vacuum cast. The nominal compositions were: Alloy A—1 pct Al, balance Ag; Alloy B—0.1 pct Al, balance Ag. Chemical analysis, which does not distinguish between aluminum and aluminum oxide, showed the conlposition to be: Alloy A—1.6 pct Al, and Alloy B—0.14 pct Al. The ingots were machined for surface cleaning, swaged and drawn to 0.020-in. diam wire. A sample 20 ft long of the 0.020-in. dianl wire of each composition was annealed 24 hr at 800°C in pure dry hydrogen. Each wire was then cut into two equal pieces. Photomicrographs of the 0.14 pct A1 alloy are shown in Fig. 1, the annealed 0.020-in. wire at the left and the oxidized wire to the right. The oxidation treatment for the first set of data was 1000 hr at 800°C in air. After this treatment the 1 pct A1 proved to be brittle. It is assumed that high alunlinum oxide concentration at the grain boundaries was responsible. The 0.14 pct Al wire remained ductile and all further data were derived using this alloy. One-half of this wire, about 5 ft, plus 5 ft of as-homogenized wire, was then drawn cold to 0.005 in. diam. All tensile tests were conducted with an Instron Engineering Corp. tensile-testing machine, Model TT-B. Unless otherwise indicated, the tests were made at room temperature with a strain rate of 0.1 per min. All metallographic samples were etched with an aqueous solution of 2 pct each of CrO3 and H2SO4 . EXPERIMENTAL RESULTS AND DISCUSSION PARTICLE SIZE DETERMINATION A study was made of the particle size of the aluminum oxide produced in the samples of Ag + 0.14 pct Al, oxidized 1000 hr at 800°C. A cross section of the as-oxidized wire was mounted in bakelite, polished, and etched with an aqueous solution of 2 pct each of CrO3 and H2SO4. The specimen was then thoroughly cleaned by stripping successive coatings made by applying 10 pct nitrocellulose in amyl acetate. The final replica of the cross section was made by applying 2 pct nitrocellulose in amyl acetate. The replica was stripped, transferred to a copper screen, shadow cast with chromium at 10 deg and photographs taken using a Phillips Metallix electron microscope at an accelerating potential of 100 kv. A photograph of an etched sample of the as-oxidized material is shown in Fig. 2. We believe the pits in the photograph are places were A12O3 inclusions were sitting in the matrix. By inspection, it appears that the volume fraction ob-

Jan 1, 1960

By D. K. Crampton

NEARLY everyone who has not had the benefit of study in the field of metallurgy subscribes to a persistent and enthusiastic belief in the legendary lost art of hardening copper. This of course supplies a perfect introduction to a chapter of information on copper and its alloys, since the dissipation of fallacies and superstitions affecting an art probably constitutes the best method of getting at its real substance. Metals are hardened, but also embrittled, by a plurality of impurities. In the modern technology of copper-base metal products, we are familiar with a great host of materials, passing from one extreme of dead soft copper better than 99.9 pct pure, which in the form of wire about as thick as a match will stand hundreds of full twists in a 12-in. length, to an alloy containing less than 3 pct of alloyed substance possessing the strength of pretty good steel and capable of manufacture into razor blades, should we suddenly be deprived of steel; certainly a much better material for this purpose. Every copper alloy known to primitive man lies in some inter- mediate position and the ancient bronzes that have been found all over the world wherever an early civilization existed are usually contaminated by such impurities as sulfur, oxygen, antimony, arsenic, iron, or other materials, so that they could not possibly conform to any modern intelligent specification insuring the best combination of useful properties in alloys of their type and would go

Jan 1, 1953

By F. S. Jr. Norcross

MANGANESE has long been considered one of the United States' most important strategic raw materials. Its indispensabil-ity in steel manufacture makes it vital to the nation's industrial life. Coupled with this indispensability is the fact that domes-tic producers have not been able as yet to supply more than a small part of the nation's manganese needs; consequently the United States has had to depend upon such distant foreign sources as the U.S.S.R., British India, the African Gold Coast and Brazil for the major portion of its ore. The great bulk of the mineral is con-sumed in the form of ferromanganese, an alloy that averages 8o per cent manganese and 20 per cent mainly iron and carbon. Manganese is used as a deoxidizer and desulphurizer in steel manufacture. By combination with the residual oxygen and sulphur of the bath, it helps to produce a clean, sound metal. Approximately 14 lb. of manganese, it is estimated, is used in making one ton of steel. For standard-grade ferromanganese, the ore should have a minimum of about 48 per cent Mn and preferably more. Beneficiation methods have not yet been developed for making the immense low-grade deposits in the United States salable at prevail-ing prices.

Jan 1, 1940

By F. S. Jr. Norcross

MANGANESE has long been considered one of the United States' most important strategic raw materials. Its indispensabil-ity in steel manufacture makes it vital to the nation's industrial life. Coupled with this indispensability is the fact that domes-tic producers have not been able as yet to supply more than a small part of the nation's manganese needs; consequently the United States has had to depend upon such distant foreign sources as the U.S.S.R., British India, the African Gold Coast and Brazil for the major portion of its ore. The great bulk of the mineral is con-sumed in the form of ferromanganese, an alloy that averages 8o per cent manganese and 20 per cent mainly iron and carbon. Manganese is used as a deoxidizer and desulphurizer in steel manufacture. By combination with the residual oxygen and sulphur of the bath, it helps to produce a clean, sound metal. Approximately 14 lb. of manganese, it is estimated, is used in making one ton of steel. For standard-grade ferromanganese, the ore should have a minimum of about 48 per cent Mn and preferably more. Beneficiation methods have not yet been developed for making the immense low-grade deposits in the United States salable at prevail-ing prices.

Jan 1, 1940

By Frederic Dewey

BONE-ASH cupels have been used from time immemorial to absorb litharge, and accompanying oxides; in assaying. Doubtless, also, from the earliest days cupels have been most unjustly blamed for much poor assaying. It has long been known that the precious metals go with the litharge into the cupel. This occasions a loss of precious metals and reduces the results of the assay. There have been many investigations of cupels and the most diverse views have been expressed, the extremes being the statements of Lodge 1 that every cupel has some effect upon the loss in assaying telluride ores and of the Campredons2 that coarse and fine and hard and soft cupels all give the same loss of silver when cupelling the same weights. The truth lies between these statements and much nearer the latter. In a vast majority of cases the influence of the cupel is not dominant and is outweighed by other conditions, particularly the temperature of the cupelling bead. At the Spokane meeting of the Institute I presented a paper on the Assay and Valuation of Gold Bullion,3 which recorded the results of many hundreds of assays made in the Mint service under everyday commercial conditions, which of necessity differ from scientific conditions. In following this matter up, for the purpose of increasing the accuracy of our commercial methods of bullion assays, the question of the absorption of gold by the cupel was found to be a most important one and was taken up for investigation. In a lesser degree, the silver absorption is important and interesting, but at present it appears to be far more complicated and, while many figures showing silver absorption may be found through this paper, much further investigation is required to put the subject upon a satisfactory basis.

Jan 11, 1917

By Robert Glass Cleland

THE MEMBERS of the Phelps-Dodge, Phelps-James co- partnership differed widely from one another in certain aspects of temperament and personality; but in one thing Anson Phelps, William Dodge, and Daniel James were fundamentally alike. They were all bred in the English Puritan tradition. Their creed, moreover, was the stern, militant, uncompromising creed of John Calvin and John Knox. The present generation, harshly intolerant of such a creed, has little understanding of the authority it exercised on the thinking and conduct of its adherents or of the contributions that those same adherents made to human welfare and social progress. The men who accepted its authority "were characterized by a blend of strong individualism and an equally strong sense of social duty, and they submitted their own souls to the same searching scrutiny that they applied to their business ledgers." To all three of the immediate founders of Phelps Dodge, their religion was the most real and important thing in life. It was with them day and night, in joy and sorrow, in loss and prosperity, in their most trivial personal affairs, in business transactions of the greatest moment. It was with

Jan 1, 1952

By Norris Johnston, Carrol M. Beeson

The gravimetric-vacuum distillation method was developed to permit rapid and accurate determinations of the oil-water ratios of small samples or sands containing little oil. In addition, the samples usually are so well cleaned and so little altered by the distillation at reduced pressure that rapid estimations of other physical properties may be made with the evacuated cores. Requiring only elementary glass-blowing technique, the distilling tubes and traps used in determining oil-water ratios were easily fashioned from the usual glassware. A sketch and description are given of the necessary apparatus, including the cylindrical electrical heaters. The procedure, requiring about 40 min., consists in raising the temperature and maintaining it between 675' and 725°F. for at least 10 min. while the pressure is held between I and 2 mm. Hg. The fluids condensed in the trap (cooled by a mixture of kerosine and solid carbon dioxide) are separated in a centrifuge and the volume of water is recorded. Determination of changes in weight with an analytical balance of all parts of the apparatus permits computation of weight of oil distilled and total weight of oil recovered. Introduction In determining the oil-water ratios of core samples, distillation at atmospheric pressurel-5 has proved to be sufficiently reliable for samples containing moderate quantities of oil. Since small samples and sands with little oil are encountered, how- ever, it appeared advisable to develop a method that would be applicable under these circumstances. Thegravimetric-extraction procedure1,6-9 undoubtedly is very reliable and could be used in all tests, but the time consumed in the determination would often delay field operations. This would be especially true when dealing with tight sands or viscous oils, both of which retard the extraction process. Accordingly, the gravimetric-vacuum distillation method was developed in order to combine the good features of both of the older methods; that is, accuracy and speed. By reducing the pressure, it was found possible to perform the distillation at a temperature that permits the use of glass apparatus, all parts of which can be weighed on an analytical balance. Thus, the fluids may be removed quickly from the core, the water is readily trapped and measured, and the loss in weight of the core is easily determined. In addition, the total weight of material condensed in the distilling tube and in the trap provides a method of determining the oil-water ratio that is practically independent of the one involving the loss in weight of the sample. The use of vacuum not only permits as much accuracy as does the gravimetric-extraction process, but it actually allows an increase in speed over the atmospheric-distillation method, because of the time required to cool the metal pots from about 1200°F. between runs. More important yet, the innovation makes possible the almost immediate reporting of permeability, and saturation, which is impossible

Jan 1, 1946

By Norris Johnston, Carrol M. Beeson

The gravimetric-vacuum distillation method was developed to permit rapid and accurate determinations of the oil-water ratios of small samples or sands containing little oil. In addition, the samples usually are so well cleaned and so little altered by the distillation at reduced pressure that rapid estimations of other physical properties may be made with the evacuated cores. Requiring only elementary glass-blowing technique, the distilling tubes and traps used in determining oil-water ratios were easily fashioned from the usual glassware. A sketch and description are given of the necessary apparatus, including the cylindrical electrical heaters. The procedure, requiring about 40 min., consists in raising the temperature and maintaining it between 675' and 725°F. for at least 10 min. while the pressure is held between I and 2 mm. Hg. The fluids condensed in the trap (cooled by a mixture of kerosine and solid carbon dioxide) are separated in a centrifuge and the volume of water is recorded. Determination of changes in weight with an analytical balance of all parts of the apparatus permits computation of weight of oil distilled and total weight of oil recovered. Introduction In determining the oil-water ratios of core samples, distillation at atmospheric pressurel-5 has proved to be sufficiently reliable for samples containing moderate quantities of oil. Since small samples and sands with little oil are encountered, how- ever, it appeared advisable to develop a method that would be applicable under these circumstances. Thegravimetric-extraction procedure1,6-9 undoubtedly is very reliable and could be used in all tests, but the time consumed in the determination would often delay field operations. This would be especially true when dealing with tight sands or viscous oils, both of which retard the extraction process. Accordingly, the gravimetric-vacuum distillation method was developed in order to combine the good features of both of the older methods; that is, accuracy and speed. By reducing the pressure, it was found possible to perform the distillation at a temperature that permits the use of glass apparatus, all parts of which can be weighed on an analytical balance. Thus, the fluids may be removed quickly from the core, the water is readily trapped and measured, and the loss in weight of the core is easily determined. In addition, the total weight of material condensed in the distilling tube and in the trap provides a method of determining the oil-water ratio that is practically independent of the one involving the loss in weight of the sample. The use of vacuum not only permits as much accuracy as does the gravimetric-extraction process, but it actually allows an increase in speed over the atmospheric-distillation method, because of the time required to cool the metal pots from about 1200°F. between runs. More important yet, the innovation makes possible the almost immediate reporting of permeability, and saturation, which is impossible

Jan 1, 1946

By Thomas Fraser

UP to the present, there has been no large coal-producing industry in any of the South American countries. Since colonial times, the great mineral and agricultural wealth of that continent has led the people to activities other than the development of manufacturing industries based on coal; and climatic conditions are such that there has been very little demand for solid domestic fuel. However, there are extensive and widely distributed reserves of coal in South America that would make the development of a modern coal industry feasible. That factor is of the utmost significance now, when it is believed that the South American countries are entering the pioneer phase of a broad industrial development. Coal Fields Great areas of coal-bearing formations of Cretaceous and Tertiary ages occur generally throughout the Andean uplift and extend into the coastal range of the Caribbean region far east of Caracas. Thus the west coast countries have adequate reserves of coal, which include a wide range of types and classes. In the eastern part of South America, east of the Cordillera, as in North America, the coal measures are of Carboniferous and Permocarboniferous ages. The principal known deposits in this area are in the southern States of Brazil. Permocarboniferous coals ranging in rank from lignitic to anthracitic are found in the States of Rio Grande do Sul, Santa Catarina, Parana and Sao Paulo. In the great.interior plateau of Brazil, south of the Amazon River, are extensive areas of Carboniferous strata that may contain coal deposits. There are widely scattered reports of findings of coal in' wells and stream beds in northern Piaui and Goias. In the Rio Fresco Valley, explorers have observed outcrops of two beds of anthracite and have brought to Rio de Janeiro samples from these beds. The Fresco is a tributary of the Xingu River that enters the Amazon from the south, but coal could not be shipped by water since the Rio Fresco area is in the upper part of the Xingu Valley, and there is a formidable series of rapids between that area and the lower level of the Amazon River basin. It is doubtful if coal deposits in this general area will be of economic importance for many years to come. Fig. 1 shows the general location of known coal fields of South America that have been explored sufficiently to indicate the presence of workable reserves. The coal deposits of the Andean region are similar in occurrence and general characteristics, as well as in age, to the coals of the Rocky Mountain region of North America. Although the coal fields obviously

Jan 1, 1952

By D. J. McAdam

Results of investigation of corrosion-fatigue of metals at the U. S. Naval Engineering Experiment Station have been presented by the author in four papers.1, 2, 3, 4 In those papers references were given to the work of Haigh in 1917.5 The investigation at Annapolis included a variety of ferrous and non-ferrous alloys. The experiments showed that even slight corrosion simultaneous with fatigue may cause failure at stresses far below the ordinary endurance limit. The experiments also showed that, for most metals, severe stressless corrosion prior to fatigue is much less damaging than even slight corrosion simultaneous with fatigue. The term "corrosion-fatigue" was restricted to mean the simultaneous action of corrosion and fatigue. The combined effect of corrosion followed by fatigue was called "prior-corrosion fatigue." A stress-cycle graph representing corrosion-fatigue is a curve approaching a horizontal asymptote, the ordinate of which may be called a "corrosion-fatigue limit." To avoid confusion in later discussion, the term "endurance limit" will be restricted to mean the fatigue limit obtained by tests in air with specimens as free as possible from stress concentration and from corrosion. The cndursnce limit as thus obtained presumably represents an inherent property of the metal.

Jan 1, 1929