Search Documents

Those familiar with the war in France at first hand know that in these last two years the weight of the suffering has fallen upon the families of the well-to-do classes; those who before the war lived in comparative ease and comfort, with every prospect of educating their children as their parents and grandparents had been. Thousands of the men in these families have been killed, "officiers d'élite," and the small pensions accorded the widows permit them only to house and feed their children HELÈNE JOURNÈS. and give them a common-school education. The pension for a lieutenant's widow is $245 a year; for 'a captain's, $345; for a colonel's $575; and so on. At present, it requires three francs a day to provide food for one person in cities, and conditions are not improving. The American Ouvroir Funds, 681 Fifth Ave., New York City, has tried for nearly two years to have individual Americans give individual children a "bourse," or purse, as it is called, of from $150 to $250 a year, so that they may enter such educational institutions as the Lycées, the Polytechnique, Beaux Arts, St. Cyr, etc. The war relief societies of these military schools furnish photographs and histories of children under their care and on their lists.

Jan 12, 1918

By T. L. Joseph

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

Jan 9, 1924

By R. W. Raymond

This paper is simply a summary, prepared at the request of the Council of the Institute, of the report of Mr. Albert Ladd Colby, of South Bethlehem, Pa., presented at the New York meeting (October, 1896) of the Association of American SteelManufacturers, on " The Advisability of the Endorsement by the Association of the United States Standard Gauge, approved by Act of Congress, March 3, 1893, to the Exclusion of the Birmingham Gauge, the .Brown and Sharpe, and all Others:" a subject on which, at the Pittsburgh meeting (April, 1896) of the said Association, Mr. Colby had been appointed as a committee. The report favors the adoption, not of the United States standard gauge to the exclusion of others, but of a decimal system of gauging all materials in thousandths of an inch, thus doing away entirely with arbitrary gauge-numbers running in inverse order to the actual thickness. The American Institute of Mining Engineers originated this movement. The report of its committee on a standard wiregauge, presented in October, 1877,* recommended the abandonment of the system of fixed gauges for commercial use, and of the system of representing the diameters and sizes by numbers, and the adoption, in lieu thereof, of the system of expressing sizes in thousandths of an inch or fractions of a millimeter, and the use of the micrometer-gauge as a means of measuring sizes. In 1892 the American Society of Mechanical Engineers appointed a similar committee, and corresponding action was

Jan 1, 1898

By R. H. Sweetser

At the Buffalo meeting in October, 1898 (Trans., xxviii., 865), our Secretary, Dr. Raymond, in speaking of the obstacles he had encountered in securing contributions to the Transactions from members in practice, said : " It is the disinclination of many members to communicate incomplete or partial or preliminary results. They are going to write, ' some day,' a thorough and monumental paper; and meanwhile they prefer to communicate nothing.... It is the difficulty to which I have just referred that I have encountered in a wide correspondence with members, undertaken for the purpose of securing contributions of fact and opinion concerning the special subject of this discussion.... Almost none of them seem to recognize the value of preliminary, incomplete and indecisive reports of practice, as laying the foundation for a thorough' inquiry." This remark was made in immediate reference to a discussion concerning blast-furnace tuyeres; but, notwithstanding this appeal from the Secretary, little has been recorded regarding the distribution, the penetration, and the pressure of the blast at the tuyeres and inside the iron blast-furnace. I am therefore encouraged to contribute the following incomplete and crude observations of the blast-pressure inside the hearth. At the suggestion of J. H. Frantz, the general manager of the Columbus Iron & Steel Go., a test was made at the East furnace of the company to determine whether there was any difference in blast-pressure at the different tuyeres. The apparatus used for this test was not sensitive enough to give accurate results. It consisted of a small pressure-gauge mounted on a 3/8-in. gas-pipe. A hollow plug, fitting into the peep-hole of the tuyere-cap, prevented the blast from blowing-out during the test. The test-pipe was held in place by means of the handle on the outer end.

Jan 1, 1910

By H. S. Coe

ENGINEERS have long recognized the desirability of correlating the data obtained from small-scale slime-settling tests with commercial work as carried on in large tanks. This need, though most apparent in designing new installations, frequently arises also in existent plants, since a large range of experimental work can be performed without interfering with regular operation. GENERAL SETTLING PHENOMENA In order to develop rational methods of laboratory testing, it becomes necessary to study the general phenomena of settling. Since it was desired to give the public the benefit of these methods at as early a date as possible, together with the knowledge of the general principles of slime settling necessary for a clear understanding of the laboratory tests, we have ventured to discuss the subject in so far as brought out by the work which we now have under way. We realize that certain of our preliminary conclusions may be subject to modification, but it seems probable that, with but few exceptions, the general laws enunciated will cover the settling behavior of all pulps encountered in metallurgical plants. However, it must be recognized that there is still a vast amount of work to be done upon certain phases of the subject; therefore, at this time we will attempt only a discussion of the behavior of ore pulps during the process of settling or dewatering, under certain given conditions. The laws and principles controlling these conditions are not fully established, so that a complete discussion of them will not be attempted in this paper. In metallurgical practice, slime pulp consists of water, finely divided sand

Jan 3, 1916

ROBERT E. TALLY,* Jerome, Ariz. (written discussion ?).-Mr. Sherman's paper, entitled "Measures for Controlling Fires at the Copper Queen Mine," embodies two new and very important features: First, automatic closing of doors communicating with the dangerous area; second, the use of a portable storage-battery fan. His other procedures, such as giving a general fire alarm, getting workmen to the surface, etc., are equally important, but have long been in use in other places. Fire and ventilating doors in connections leading to shafts, air raises, and other large timbered areas, have been in use at other mines; but the method described by Mr. Sherman for operating these doors by compressed air, through a valve on the surface, is, so far as I know, original, and should be installed in every mine where there is danger of fire. Nearly all large mines are now using artificial ventilation, with the result that there are strong air currents in the shafts and other important workings. The most important feature in mine fires is a quick and positive control of the ventilation, for it takes but a few moments for smoke to travel over a large area, with the usual results of suffocation, and destruction of property. A strong air current in an upcast shaft acts as a draft in case of fire, and unless quickly cut off the fire would soon get beyond control. An upcast shaft usually changes to a downcast when large amounts of water are used. Human lives are in more danger from downcast currents, as the smoke travels into the workings.

Jan 4, 1918

By Max Y. Seaton

THE scope of this paper will be limited to finished materials that contain a large preponderance (around 80 per cent or more) of magnesium oxide. The large and commercially important production of refractory dolomite and modified dolomites is not discussed here, and the production of magnesium basic carbonate for use as a heat insulator is barely mentioned. The discussion is confined mainly to magnesias produced in comparatively great quantity by direct processing of naturally occurring raw materials and hence excludes secondary or highly purified products such as pharmaceutical products or U.S.P. light and heavy calcined magnesias of commerce. NOMENCLATURE The nomenclature of the magnesia products that will be discussed is somewhat confusing, in that it is customary in the trade to designate as "calcined magnesite" the materials that result from the calcining of magnesite to temperatures that remove the contained carbon dioxide. The finished product, therefore, is not magnesite at all but simply a more or less pure magnesium oxide or magnesia. Furthermore, partly for statistical and partly for commercial reasons, it has been customary, during recent years, to classify as "calcined magnesite" products that result from the heat-treatment of magnesium hydroxide precipitated from magnesium-containing brines; products that, obviously, have no relationship whatever to magnesite. In the listing of magnesia-containing materials, tonnages of which are regularly reported by the Bureau of Mines, reports ordinarily are made under two headings: "caustic calcined" magnesite, in which all of the varieties of products treated at relatively low temperatures are lumped; and "dead-burned" magnesite, in which are included both high-purity and low-purity, and particularly both high-iron and low-iron, materials that have been so heat-treated that the magnesium oxide occurs predominantly as crystalline periclase-materials used almost entirely for refractory purposes. In 1940 the apparent domestic consumption of "caustic calcined" magnesite was approximately 17,000 tons, about 95 per cent of which was produced in this country. The apparent consumption of "dead-burned" magnesite was approximately 172,000 tons, some 82 per cent of which was domestically produced. In both total quantity and percentage of material produced within the United States, these figures are record highs for many years past. UTILIZATION As indicated by these figures, the major tonnage outlet for magnesia is the refractories industry, in which magnesia is employed principally in three ways: (I) as dead-burned grain magnesite for the construction and maintenance of the hearths or bottoms of basic open-hearth furnaces; (2) in the form of refractory magnesite bricks and shapes; and (3) as a chemical

Jan 1, 1942

By Max Y. Seaton

THE scope of this paper will be limited to finished materials that contain a large preponderance (around 80 per cent or more) of magnesium oxide. The large and commercially important production of refractory dolomite and modified dolomites is not discussed here, and the production of magnesium basic carbonate for use as a heat insulator is barely mentioned. The discussion is confined mainly to magnesias produced in comparatively great quantity by direct processing of naturally occurring raw materials and hence excludes secondary or highly purified products such as pharmaceutical products or U.S.P. light and heavy calcined magnesias of commerce. NOMENCLATURE The nomenclature of the magnesia products that will be discussed is somewhat confusing, in that it is customary in the trade to designate as "calcined magnesite" the materials that result from the calcining of magnesite to temperatures that remove the contained carbon dioxide. The finished product, therefore, is not magnesite at all but simply a more or less pure magnesium oxide or magnesia. Furthermore, partly for statistical and partly for commercial reasons, it has been customary, during recent years, to classify as "calcined magnesite" products that result from the heat-treatment of magnesium hydroxide precipitated from magnesium-containing brines; products that, obviously, have no relationship whatever to magnesite. In the listing of magnesia-containing materials, tonnages of which are regularly reported by the Bureau of Mines, reports ordinarily are made under two headings: "caustic calcined" magnesite, in which all of the varieties of products treated at relatively low temperatures are lumped; and "dead-burned" magnesite, in which are included both high-purity and low-purity, and particularly both high-iron and low-iron, materials that have been so heat-treated that the magnesium oxide occurs predominantly as crystalline periclase-materials used almost entirely for refractory purposes. In 1940 the apparent domestic consumption of "caustic calcined" magnesite was approximately 17,000 tons, about 95 per cent of which was produced in this country. The apparent consumption of "dead-burned" magnesite was approximately 172,000 tons, some 82 per cent of which was domestically produced. In both total quantity and percentage of material produced within the United States, these figures are record highs for many years past. UTILIZATION As indicated by these figures, the major tonnage outlet for magnesia is the refractories industry, in which magnesia is employed principally in three ways: (I) as dead-burned grain magnesite for the construction and maintenance of the hearths or bottoms of basic open-hearth furnaces; (2) in the form of refractory magnesite bricks and shapes; and (3) as a chemical

Jan 1, 1942

By Max Y. Seaton

The scope of this paper will be limited to finished materials that contain a large preponderance (around 80 per cent or more) of magnesium oxide. The large and commercially important production of refractory dolomite and modified dolomites is not discussed here, and the production of magnesium basic carbonate for use as a heat insulator is barely mentioned. The discussion is confined mainly to magnesias produced in comparatively great quantity by direct processing of naturally occurring raw materials and hence excludes secondary or highly purified products such as pharmaceutical products or U.S.P. light and heavy calcined magnesias of commerce. Nomenclature The nomenclature of the magnesia products that will be discussed is somewhat confusing, in that it is customary in the trade to designate as "calcined magnesite" the materials that result from the calcining of magnesite to temperatures that remove the contained carbon dioxide. The finished product, therefore, is not magnesite at ali but simply a more or less pure magnesium oxide or magnesia. Furthermore, partly for statistical .and partly for commercial reasons, it has been customary, during recent years, to classify as "calcined magnesite" products that result from the heat-treatmerit of magnesium hydroxide precipitated from magnesium-containing brines; prod- ucts that, obviously, have no relationship whatever to magnesite. In the listing of magnesia-containing materials, tonnages of which are regularly reported by the Bureau of Mines, reports ordinarily are made under two headings: "caustic calcined" magnesite, in which all of the varieties of products treated at relatively low temperatures are lumped; and "dead-burned" magnesite, in which are included both high-purity and low-purity, and particularly both high-iron and irow-iron, materials that have been so heat-treated that the magnesium oxide occurs predominantly as crystalline periclase— materials used almost entirely for refractory purposes. In 1940 the apparent domestic consumption of "caustic calcined" magnesite was approximatcly 17,000 tons, "bout 95 Per cent of which was produced in this country. The apparent consumption of "dead-burned" magnesite was approximately 172,000 tons, some 82 per cent of which was domestically produced. In both total quantity and percentage of material produced within the United States, these figures are record highs for manY Years past. Utilization As indicated by these figures, the major tonnage outlet for magnesia is the refractories industry, in which magnesia is employed principally in three ways: (1) as dead-burned grain magnesite for the construction and maintenance of the hearths Or bottomS of basic open-hearth furnaces; (2) in the form of refractory magnesite bricks and shapes; and (3) as a chemical

Jan 1, 1942

By Max Y. Seaton

The scope of this paper will be limited to finished materials that contain a large preponderance (around 80 per cent or more) of magnesium oxide. The large and commercially important production of refractory dolomite and modified dolomites is not discussed here, and the production of magnesium basic carbonate for use as a heat insulator is barely mentioned. The discussion is confined mainly to magnesias produced in comparatively great quantity by direct processing of naturally occurring raw materials and hence excludes secondary or highly purified products such as pharmaceutical products or U.S.P. light and heavy calcined magnesias of commerce. Nomenclature The nomenclature of the magnesia products that will be discussed is somewhat confusing, in that it is customary in the trade to designate as "calcined magnesite" the materials that result from the calcining of magnesite to temperatures that remove the contained carbon dioxide. The finished product, therefore, is not magnesite at ali but simply a more or less pure magnesium oxide or magnesia. Furthermore, partly for statistical .and partly for commercial reasons, it has been customary, during recent years, to classify as "calcined magnesite" products that result from the heat-treatmerit of magnesium hydroxide precipitated from magnesium-containing brines; prod- ucts that, obviously, have no relationship whatever to magnesite. In the listing of magnesia-containing materials, tonnages of which are regularly reported by the Bureau of Mines, reports ordinarily are made under two headings: "caustic calcined" magnesite, in which all of the varieties of products treated at relatively low temperatures are lumped; and "dead-burned" magnesite, in which are included both high-purity and low-purity, and particularly both high-iron and irow-iron, materials that have been so heat-treated that the magnesium oxide occurs predominantly as crystalline periclase— materials used almost entirely for refractory purposes. In 1940 the apparent domestic consumption of "caustic calcined" magnesite was approximatcly 17,000 tons, "bout 95 Per cent of which was produced in this country. The apparent consumption of "dead-burned" magnesite was approximately 172,000 tons, some 82 per cent of which was domestically produced. In both total quantity and percentage of material produced within the United States, these figures are record highs for manY Years past. Utilization As indicated by these figures, the major tonnage outlet for magnesia is the refractories industry, in which magnesia is employed principally in three ways: (1) as dead-burned grain magnesite for the construction and maintenance of the hearths Or bottomS of basic open-hearth furnaces; (2) in the form of refractory magnesite bricks and shapes; and (3) as a chemical

Jan 1, 1942

By K. C. Heald

THE places where, yesterday, oil was unknown contain tomorrow's fields. Unquestionably, some states that now yield little or no oil have great potentialities, and developments in these states, although perhaps of less immediate interest than those in regions where great pools now exist, may easily be of greater ultimate importance than the results of exploration closer to known fields. Not long ago, Montana had only a quarter of an oil pool, and that was regarded by many as an accident that had strayed from Wyoming. More recently, the northern line of Louisiana was a dead line that would not be crossed by any Louisiana operator who valued his reputation for sanity. Within the past few months, Colorado has shown that it is far from being a negligible factor in the oil supply of the Rocky Mountain states, and it is now known that western Kansas, long shunned by many reputable geologists and operators, should be reckoned with. There may be a vast difference between what a wildcat well yields and what the well signifies. The fact that no commercial production is encountered may be lamentable and may well be disastrous to an individual or a company, but the same well that spells ruin to one may convey to another the information that will result in opening a new field. In presenting the conclusions, in this paper, the writer recognizes fully the possibility of erroneous deductions, particularly since he has had contact with only a few of the wells that are mentioned. Information comes principally from the scout. maps and files maintained at the Geological Survey by M. E. Latimer and G. K. Drach, without whose cooperation this summary would not be possible, supplemented by some personal contact and second-hand information gained by. conversation and correspondence. However, it is felt that the data contain few errors, and that the conclusions are at least reasonable.

Jan 3, 1924

By A. Kenneth Schellinger

DURING the comminution of a brittle material in the presence of dry air, no known phase change or chemical reaction takes place. The energy changes associated with the comminution are those of the transformation of kinetic energy into heat energy and the energy absorption represented by the actual rupture of molecular and/or ionic bonds. The random nature of the actual grinding process in a tumbling-mill often precludes the effective application of a rupture force on each individual particle of brittle mineral present. The result must be a great deal of useless vibration on an atomic scale in both the brittle mineral and the grinding medium below the elastic limit, which vibration is eventually manifested as heat energy in the mill. The actual rupture of molecular, or ionic, bonds creates new surface on the brittle minerals; each square centimeter of this new surface then must possess a number of potential bonds, each of which could reform theoretically with the release of energy. The sum total of this potential energy of bonding per unit of new surface, minus bond satiation effects of the enclosing gas or liquid, must be the surface energy of the mineral. If the comminution of the brittle mineral were carried out within the chamber of a calorimeter, the energy released as heat could be determined rather accurately. Moreover, the total kinetic energy input to the comminuting mass (mineral and medium) conceivably could be derived by a suitable torquemeter and revolution counter if the whole calorimeter were revolved. The difference between these two energy figures should then represent the net energy (gross energy input-heat energy output) used in creating

Jan 6, 1951

By Douglas Bunting

The first presentation of this paper was before the Pennsylvania Anthracite Section of the Institute in May, 1914, after which a committee was selected to verify and add to the data contained in the original paper. The author is indebted to G. W. Engel, H. W. Montz, R. V. Norris, and H. H. Otto, of this committee, for additional information. I also wish to acknowledge the courtesies extended me by a number of the mining companies for information relative to accidents, systems of proving, and mining practice. The paper should bring forth additional criticism and recommendations, which will be of value in establishing future practice relative to this subject. Throughout the northern anthracite field of Pennsylvania glacial and alluvial deposits of sand, gravel, and clay exist in varying quantities. The extent and character of these deposits are described by N. H. Darton in Bulletin 45 of the U. S. Bureau of Mines, entitled, Sand Available for Filling Mine Workings in the Northern Anthracite Basin. It is estimated that the northern field contains 10,000,000,000 tons of these deposits, or a sufficient quantity to cover the 176 square miles of coal area to a depth of about 25 ft. These deposits of sand, etc., overlying the coal measures attain a maximum depth of more than 300 ft., and are usually saturated to such an extent as to render them semi-fluid. It is this condition of fluidity that limits the mining of coal seams cropping in or in close proximity to these deposits, and it is in the interest of safer and more efficient mining methods under these conditions that the study of this subject is here presented. The dangers incident to mining under deep deposits of sand have long been realized by operators in the northern anthracite field, and much has been done to prove the contour of the rock and vein croppings underlying these water-bearing deposits of sand and gravel. Although, as far as we know, the accidents of the past have not resulted in the loss of life, except in two instances, yet nearly all were attended with more or less miraculous escapes of men working in the vicinity of the breaks, so that the probable existence of pot holes, etc.,

Jan 1, 1915

By F. W. Bloecher

DETERMINATION of the surface area of finely divided minerals is of interest to mineral engineers engaged in flotation, comminution, and de-watering studies. In the industrial minerals field, many materials are classified as to fineness according to their specific surface (surface area per unit weight). A method of surface area determination has been tested and used in the Richards Mineral Engineering Laboratories at M.I.T. It involves low temperature krypton adsorption measurements using the technique described by Beebe.' During the past fifteen years a number of new surface measurement techniques have been developed. Those that are broadly applicable to materials dealt with by mineral engineers include the permeability method in which a gas or liquid is passed through the sample, and the low temperature gas adsorption methods first described by Brunauer, Emmett, and Teller."" Efforts to make surface determinations from size distribution curves have long been attempted"."." but because of the uncertainty of sub-sieve size distribution and inaccuracies in screen analyses, the method is at best only a rough approximation. The most widely used gas adsorption method utilizes nitrogen gas." Nitrogen adsorption, however, is not particularly suited as a tool for most mineral engineers because the method is not applicable for surface determinations on coarse materials, that is, materials coarser than approximately 150 to 200-mesh. Other gases have been used in mineral engineering studies, particularly ethane."' lo The use of ethane gas, however, involves .a technique that is too sensitive for most mineral engineering work. The permeability method of surface area determination has the disadvantage of not being sensitive enough to detect the surface represented by minute cracks, the so-called internal surface of a particle. The low temperature krypton adsorption method described by Beebe1 utilizes apparatus and techniques that are essentially the same as those used in the ethane adsorption method."1° The surface area is calculated by the B.E.T. method."-' The krypton adsorption technique is particularly suited to the needs of the mineral engineer because: (1) The method can be used for making surface area measurements of rather coarse materials (35 to 48-mesh), as well as extremely fine materials, such as clays or colloidal slimes with specific surface that might be as high as 20 to 30 mb er g. (2) The use of krypton gas offers the advantage of low saturation pressures (2-3 mm) at the conveniently obtained liquid nitrogen temperature. Therefore the krypton vacuum system need not be designed to measure or withstand internal gas, pressures above one atmosphere as is the case with the nitrogen gas method. (3) The krypton technique offers the safety feature of employing liquid nitrogen, as contrasted to the ethane technique in which liquid oxygen is required. Furthermore, ethane vapor pressure at liquid oxygen temperatures is low (about 10 microns), and a high sensitivity McLeod gage is required for pressure readings. (4) The measurement technique with krypton gas is much simpler and faster, and the apparatus is less elaborate than that required with either nitrogen or ethane gases. Apparatus A krypton surface measurement apparatus like that used at M.I.T. is shown in Fig. 1. It is constructed of pyrex glass. A vacuum is maintained by two mercury diffusion pumps in series backed by a mechanical vacuum pump."' The vacuum thermocouple gage is used for checking the vacuum within the system. This type of gage is quite sensitive down to a pressure of 1 micron of mercury," but may be used to indicate pressures much lower than that

Jan 1, 1952

By J. K. Gustafson

MEASURED in terms of ore tonnage, the New Quebec and Labrador iron ore fields promise to rank with the greatest iron ore districts of the world. -- Over 400 million tons of high-grade ore for direct shipping have been discovered to date. Much greater amounts of lower-grade beneficiating ores are indicated by outcrops. Many hundreds of square miles of iron formation await testing.

Jan 6, 1953

By D. W. Fuerstenau

In recent years, various advances have taken place in the flotation recovery of fine mineral particles. A number of new approaches to recovery of fine particles have been proposed. In this paper, the background and performance of some of these tech- niques for fine particles processing are reviewed. A brief sum mary of the problems associated with fine particles in flotation and related processes is presented.

Jan 1, 1980

By R. Al-Hussainy, P. B. Crawford, H. J. Ramey

The effect of variations of pressure-dependent viscosity and gas law deviation factor on the flow of real gases through porous media has been considered. A rigorous gas flow equation was developed which is a second order, non-linear partial differential equation with variable coeficients. This equation was reduced by a change of variable to a form similar to the diffusivity equation, but with potential-dependent diffusivity. The change of variable can be used as a new pseudo-pressure for gas flow which replaces pressure or pressure-squared as currently applied to gas flow. Substitution of the real gas pseudo-pressure has a nrtmber of important consequences. First, second degree pressure gradient terms which have commonly been neglected under the assumption that the pressure gradient is small everywhere in the flow system, are rigorously handled. Omission of second degree terms leads to verious errors in estimated pressure distributions for tight formations. Second, flow equations in terms of the real gas pseudo-pressure do not contain viscosity or gas law deviation factors, and thus avoid the need for selection of an average pressure to evaluate physical properties. Third, the real gas pseudo-pressure can be determined numerically in term of pseudo-reduced pressures and temperatures from existing physical property correlations to provide generally useful information. The real gas pseudo-pressure was determined by numerical integration and is presented in both tabular and graphical form in this paper. Finally, production of real gas can be correlated in terms of the real gas pseudo-pressure and shown to be similar to liquid flow as described by diffusivity equation solutions. Applications of the real gas pseudo-pressnre to radial flow systems under transient, steady-state or approximate pseudo-steady-state injection or production have been considered. Superposition of the linearized real gas flow solutions to generate variable rate performance was investigated and found satisfactory. This provides justification for pressure build-up testing. It is believed that the concept of the real gas pseudo-pressure will lead to improved interpretation of results of current gas well testing procedures, both steady and unsteady-state in nature, and improved forecasting of gas production. INTRODUCTION In recent years a considerable effort has been directed to the theory of isothermal flow of gases through porous media. The present state of knowledge is far from being fully developed. The difficulty lies in the non-linearity of partial differential equations which describe both real and ideal gas flow. Solutions which are available are approximate analytical solutions, graphical solutions, analogue solutions and numerical solutions. The earliest attempt to solve this problem involved the method of successions of steady states proposed by Muskat.' Approximate analytical solutions' were obtained by linearizing the flow equation for ideal gas to yield a diffusivity-type equation. Such solutions, though widely used and easy to apply to engineering problems, are of limited value bemuse of idealized assumptions and restrictions imposed upon the flow equation. The validity of linearized equations and the conditions under which their solutions apply have not been fully discussed in the literature. Approximate solutions are those of Heatherington et al.. MacRobertsl and Janicek and Katz.' A graphical solution of the linearized equation was given by Cornell and Katz. Also, by using the mean value of the time derivative in the flow equation, Rowan and Clegg' gave several simple approximate solutions. All the solutions were obtained assuming small pressure gradients and constant gas properties. Variation of gas properties with pressure has been neglected because of analytic difficulties. even in approximate analytic solutions. Green and Wilts8 used an electrical network for simulating one-dimensional flow of an ideal gas. Numerical methods using finite difference equations and digital computing techniques have been used extensively for solving both ideal and real gas equations. Aronofsky and Jenkins"I " and Bruce et al.11 gave numerical solutions for linear and radial gas flow. Douglas et al." gave a solution for a square drainage area. Aronofsky 13 included the effect of slippage on ideal gas flow. The most important contribution to the theory of flow of ideal gases through porous media was the conclusion reached by Aronofsky and Jenkins" that solutions for the liquid flow case'" could be used to generate approximate solutions for constant rate production of ideal gases. An equation describing the flow of real gases has been solved for special cases by a number of investigators using numerical methods. Aronofsky and Ferris 10 onsidered linear flow, while Aronofsky and Porter 17 considered radial gas flow. Gas properties were permitted to vary as linear functions of pressure. Recently, CarteP 18 proposed an empirical correlation by which gas well behavior can be estimated from solutions of the diffusivity equation using instantaneour values of pressure-dependent gas

Jan 1, 1967

By J. B. Darby

In an investigation of various equiatomic alloys of transition elements, Dwightl did not find evidence for the CsC1-type ordered structure in VMn. More recently waterstrat2 has reported the occurrence of this structure in the alloy his sample had been homogenized at 1150°C and subsequently reannealed at 725°C after crushing to powder. The purpose of this note is to confirm the existence of the CsC1-type ordered structure in VMn and to report a lattice parameter. An equiatomic alloy was prepared by arc-melting under an argon atmosphere vanadium and electrolytic manganese having a purity of at least 99.9 pet. The composition was obtained by charging an excess of manganese and monitoring the weight loss until the stoichiometric composition was achieved; the assumption that the loss during melting was due to the vaporization of manganese appears to be a valid one.' The calculated composition of the sample prepared was 49.85 at. pct V and 50.15 at. pct Mn. Specimens taken from the fractured as-cast buttons were wrapped in molybdenum foil and encapsulated in quartz capsules under vacuum; there was no evidence of a reaction between the alloy and foil. The X-ray patterns were obtained using filtered copper or chromium radiation with a Straumanis-type Debye-Scherrer camera having a diameter of 114.6 mm. The CrKa radiation is best suited for detecting the superlattice lines since it overcomes the slight difference in scattering powers of the components by making use of the anomalies in atomic scattering factor which occur when the frequency of the radiation is close to the characteristic absorption frequency of one of the elements.394 A specimen in the as-cast condition, as well as one which had been annealed for 1 week at 900°C and water-quenched, gave a diffraction pattern for the disordered bcc solid solution. However, when samples were homogenized at 900°C for 3 weeks followed by a subsequent anneal at 700°C for 6 to 7 weeks and then water-quenched or furnace-cooled, the (loo), (1111, and (210) Ka superlattice lines were observed in films taken with chromium radiation. An ao = 2.904 * 0.001 was determined by a Nelson-Riley extrapolation from a film taken with CuKa radiation. The author wishes to thank Mr. J. W. Downey and Mr. L. J. Norton for carrying out the experimental portion of this investigation. This work was performed at the Argonne National Laboratory under the auspices of the U.S. Atomic Energy Commission.

Jan 1, 1963

By Charles M. Bayer

Reading in the AIME annual reports that certain activities have been financed by the Rocky Mountain Club Fund, less senior members of the Institute may wonder. "What's the Rocky Mountain Club?" Less youthful members will not have to wonder. They will recall the Club as an intriguing, almost fantastic organization, largely of western mining men, that flared across the New York horizon, flamed brilliantly for a little more than two decades, then sputtered out of existence- glorious even in its last flash. It was the only product of its mold, a fabulous group of magnanimous men who unhesitatingly sacrificed a cherished dream for which they had raised millions of dollars so that the money, instead of creating a magnificent club house, could be used instead to save the lives of starving Belgian children in World War I.

Jan 12, 1964

By R. Sporcic, P. J. Mudra

During the past year personnel of the Roof Control Research Group of the Bureau of Mines designed and developed encapsulated hydraulic cells for measuring pressure changes in coal in situ. Preliminary results from feasibility tests in progress in the laboratory and field indicate that the cells respond favorably to changes in pressures associated with a coal-mining environment. The ultimate objective is to use these cells to obtain engineering information relating to coal bump or coal outburst phenomena. Mining research has experienced a remarkable growth during the past decade and from all indications should surge forward at even a greater pace in the future. This increased interest in mining research has been brought about by the ever-multiplying number of technical problems being encountered by the mining industry in its effort to produce pay-dirt tonnages safely and economically from greater underground and surface pit depths. Among the various divisions in the field of mining research, the study of ground stress has received a large part of the overall attention. Numerous technical papers have been written with regard to ground stress conditions around mine openings and yet the total usable knowledge concerning this subject is extremely limited. Research teams around the world are endeavoring to bridge the gap between theoretical and laboratory approaches and the solution to design problems in the field. The problem of ground stress is not a new one for the coal mining industry. Operators in both eastern and western coal fields of the United States as well as in many foreign countries have long been plagued with a number of ground stress problems, one of which is commonly referred to as the coal-mine bump. This term or phenomenon has been aptly defined by earlier investigators as the violent and sudden failure of coal and adjacent rock. Direct results of such failures have been the loss of human lives and thou- sands upon thousands of dollars of sustained mine damages. In an effort to alleviate the magnitude and frequency of these failures, mine operators have employed and are presently employing various corrective techniques. These include: Inducing failure in heavily stressed areas by augering large-diameter holes into stressed pillars, using extensively yield-able steel arches in both long-term haulage and short-term face entries, backfilling unused or abandoned entries with mine waste to gain additional support, and using systematic pillar coal panel extraction techniques including mechanized longwall mining. The Health and Safety Activity of the Bureau of Mines has for a number of years contributed considerable time, funds, and talent in an effort to define better the ground stress problems associated with coal-mine bumps. As a part of this investigative program, in situ ground pressures are presently being studied in coal mines located in West Virginia and Utah. The description and development of the device being used to measure these pressures is the specific topic of this paper. CHOICE OF INSTRUMENTATION After consideration and evaluation of the various instruments and techniques that are being used by researchers in the field of rock mechanics to detetmine in situ stresses, a simple hydraulic system was selected for detailed investigation. Aside from simplicity, a hydraulic system is relatively inexpensive and also eliminates the need for electricity in its installation and operation. The hydraulic device referred to is, in essence, a simple unidirectional pressure-measuring cell. Hydraulic cells, which had been used for measurement of pressures in hard rock, were investigated but found not entirely suitable for use in coal, particularly since they involved (1) preparation and emplacement of cement grout at the test site, and (2) a waiting period before the cells became operational. At the outset, it was decided that certain design parameters be established. The cell should be simple and inexpensive, constructed of materials readily obtainable and easily built in the laboratory or field by unskilled labor. It was further decided that it was desirable to encapsulate the cell in a suitable mate-

Jan 1, 1963