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By R. W. Raymond

The immense commercial value of the Gayley dry-blast process has been established beyond controversy. The testimony of practical blast-furnace managers, on both sides of the Atlantic, agrees that it reduces the cost of pig-iron about $1 per ton; but from the same testimony it appears that this direct economy does not by any means cover its commercial advantages—in fact, that under conditions frequently encountered in practice, it presents other benefits of even greater immediate financial importance. To this point I shall recur in a later part of the present paper. The history of the reception given to this invention, especially on the other side of the Atlantic, has repeated an experience familiar to American engineers. First, the reports of our practice were rejected as theoretically impossible, according to generally accepted notions and formulas; then the figures were reluctantly accepted; and finally the attempt has been made to explain how they could have been obtained. As to the Gayley dry blast, me Americans have been for several years in the last stage of the discussion, and the rest of the professional world is rapidly coming to it. Meanwhile, the remark has been repeatedly made that, whatever Mr. Gayley's process may turn out to be worth, it was not an invention on his part, but simply the energetic and persevering execution of a procedure already proposed by others. This question I wish to discuss first in the present paper. I. What Did Mr. Gayley Invent? Realizing that this is not the place for detailed argument on an issue of patent law, I shall not undertake to quote and criticise the publications prior to Mr. Gayley'a first patents. It may be admitted, without such critical analysis, that the possible advantages of removing moisture from the air forced into an iron blast-furnace were recognized and talked about a hun-

Jan 1, 1909

By David J. Dunn

At a time when mill availability is at a premium, production costs are rising, and lead time for mill liner casting is a year or more, mill liner design is an important factor in ore grinding. Testing and selection of the optimum liner profile for a given set of mill operating conditions can improve mill capacity, reduce liner wear rate, and lengthen liner life. The mill liner that grinds best, lasts the longest, and costs the least is a necessity for economic mill operation. After testing four mill liner profiles for 3.96 X 3.65-m (13 x 12-ft) overflow ball mills, Climax Molybdenum Co. found that an improved design increased mill tonnage by 2.72 t/h (3 stph) while reducing finish grind by 1.7% minus 100-mesh, reduced liner wear rate, and almost doubled liner life.

Jan 12, 1976

By H. D. Hagen, George W. Abbott

2.2-1. Need for Acquisition Operating Plan. In planning a trip by automobile, a road map is procured and studied. Travel by plane suggests detailed examination of route maps, weather charts, and navigation charts. Planning for construction of a factory, office building, shopping center, or housing subdivision envisages working out a complete development plan. Household needs arc generally jotted clown on a shopping list, with each item checked off as it is purchased. In turn, forwarding of any surface mining project should be undertaken only after an acquisition operating plan has been set out, by checklist, under three general headings: 1. Public relations-a check list setting out applicable Federal, State, and local laws and regulations, and the office, board, commission, and individuals having responsibility for licensing, administration, and enforcement of each such law or regulation. 2. Land requirements-a complete check list encompassing all aspects of land acquisition, ownership, management, control, and disposition, with applicable laws. 3. Water requirements-a full check list embracing all aspects of water development and control, acquisition of rights to use, manner of use, and manner of disposition, with applicable laws and regulations. 2.2-2. Public Relations Aspects of Operating Plan. NEED TO DETERMINE APPLICABLE LAWS. The laws and regulations governing acquisition of land and mineral rights, water and water rights, and the use and control of those rights, vary so much from state to state that one cardinal rule must govern all preplanning: determine applicable Federal, State, and local law at the outset. Changing conditions in the past century have resulted in a multiplication at all levels of governmental agencies interested in, and having responsibility for, acquisition, use, control, and disposition of minerals and mineral lands. The same is true of waters and water rights found in, brought to, or discharged from, the operating site.

Jan 1, 1968

By J. C. Williams

The operations described in this paper are those of the flotation plant of the Valley Forge Cement Co. at Conshohocken, Pa., and concern the use of a particular cationic reagent—namely, DP-243. The role of this reagent in this plant may be better understood by first considering the purpose of beneficiating cement rock in general and the specific problems at the Valley Forge plant. The ultimate purpose of beneficiating cement rock is to obtain a kiln feed of the desired chemical composition in a form suitable for the most efficient kiln operation. The chemical composition is governed by the type of cement to be made. Before government restrictions (the purpose of which is to simplify operations during wartime) limited the types of portland cement a manufacturer is permitted to produce, five principal types of cement were generally recognized by the industry. They are based upon chemical and physical specifications proposed by the American Society for Testing Materials, federal and other governmental agencies, state highway departments, water boards and other users of large quantities of cement. The physical as well as chemical specifications for any particular type of cement necessitate proper proportioning of the major components—that is, the silica, alumina, iron and lime—and it is necessary to establish and maintain definite limits for each in the raw mix. The manufacturer must then prepare a kiln feed of a composition that will yield a final product that will fulfill the desired specification. This step is further complicated for kilns using coal as fuel, by the amount and analysis of the ash introduced. The amount and nature of the dust lost during burning will also affect the composition of the kiln feed. The problem of preparing a kiln feed of the desired chemical composition is not a simple one, and it is the final product that governs the methods used to obtain such a feed. For example, in starting with a material deficient in lime for the mix sought, it may not be sufficient to raise it to the required lime content. The other constituents must also be present in the proper proportions. In some cases, it may be necessary to raise the lime content to a point greatly exceeding that of the final mix, then, by addition of one or more other materials lower in lime, obtain the mix. The rock used at the Valley Forge plant is a metamorphosed argillaceous limestone of the Jacksonburg formation, the same formation as that of the Lehigh Valley cement rock (which occurs approximately 50 miles north), and its oxide composition is similar to that of the latter. The only practical differences between the two are that, as a result of metamorphosis, crystallization of the Valley Forge rock is considerably coarser and it contains less carbon than the Lehigh Valley rock as well as slightly more magnesia in the form of magnesian mica. The calcium carbonate content of the various strata in the Valley Forge quarry ranges from about 65 per cent to over 85 per cent, the average for the entire quarry being somewhat under the requirement for manufacture of cement, which usually is from 75 to 76 per

Jan 1, 1947

By J. C. Williams

THE operations described in this paper are those of the flotation plant of the Valley Forge Cement Co. at Conshohocken, Pa., and concern the use of a particular cationic reagent-namely, DP-243. The role of this reagent in this plant may be better understood by first considering the purpose of beneficiating cement rock in general and the specific problems at the Valley Forge plant. The ultimate purpose of beneficiating cement rock is to obtain a kiln feed of the desired chemical composition in a form suitable for the most efficient kiln operation. The chemical composition is governed by the type of cement to be made. Before government restrictions (the purpose of which is to simplify operations during wartime) limited the types of portland cement a manufacturer is permitted to produce, five principal types of cement were generally recognized by the industry. They are based upon chemical and physical specifications proposed by the American Society for Testing Materials, federal and other governmental agencies, state highway departments, water boards and other users of large quantities of cement. The physical as well as chemical specifications for any particular type of cement necessitate proper proportioning of the major components-that is, the silica, alumina, iron and lime-and it is necessary to establish and maintain definite limits for each in the raw mix. The manufacturer must then prepare a kiln feed of a composition that will yield a final product that will fulfill the desired specification. This step is further complicated for kilns using coal as fuel, by the amount and analysis of the ash introduced. The amount and nature of the dust lost during burning will also affect the composition of the kiln feed. The problem of preparing a kiln feed of the desired chemical composition is not a simple one, and it is the final product that governs the methods used to obtain such a feed. For example, in starting with a material deficient in lime for the mix sought, it may not be sufficient to raise it to the required lime content. The other constituents must also be present in the proper proportions. In some cases, it may be necessary to raise the lime content to a point greatly exceeding that of the final mix, then, by addition of one or more other materials lower in lime, obtain the mix. The rock used at the Valley Forge plant is a metamorphosed argillaceous limestone of the Jacksonburg formation, the same formation as that of the Lehigh Valley cement rock (which occurs approximately 50 miles north), and its oxide composition is similar to that of the latter. The only practical differences between the two are that, as a result of metamorphosis, crystallization of the Valley Forge rock is considerably coarser and it contains less carbon than the Lehigh Valley rock as well as slightly more magnesia in the form of magnesian mica. The calcium carbonate content of the various strata in the Valley Forge quarry ranges from about 65 per cent to over 85 per cent, the average for the entire quarry being somewhat under the requirement for manufacture of cement, which usually is from 75 to 76 per

Jan 1, 1946

By J. C. Williams

The operations described in this paper are those of the flotation plant of the Valley Forge Cement Co. at Conshohocken, Pa., and concern the use of a particular cationic reagent—namely, DP-243. The role of this reagent in this plant may be better understood by first considering the purpose of beneficiating cement rock in general and the specific problems at the Valley Forge plant. The ultimate purpose of beneficiating cement rock is to obtain a kiln feed of the desired chemical composition in a form suitable for the most efficient kiln operation. The chemical composition is governed by the type of cement to be made. Before government restrictions (the purpose of which is to simplify operations during wartime) limited the types of portland cement a manufacturer is permitted to produce, five principal types of cement were generally recognized by the industry. They are based upon chemical and physical specifications proposed by the American Society for Testing Materials, federal and other governmental agencies, state highway departments, water boards and other users of large quantities of cement. The physical as well as chemical specifications for any particular type of cement necessitate proper proportioning of the major components—that is, the silica, alumina, iron and lime—and it is necessary to establish and maintain definite limits for each in the raw mix. The manufacturer must then prepare a kiln feed of a composition that will yield a final product that will fulfill the desired specification. This step is further complicated for kilns using coal as fuel, by the amount and analysis of the ash introduced. The amount and nature of the dust lost during burning will also affect the composition of the kiln feed. The problem of preparing a kiln feed of the desired chemical composition is not a simple one, and it is the final product that governs the methods used to obtain such a feed. For example, in starting with a material deficient in lime for the mix sought, it may not be sufficient to raise it to the required lime content. The other constituents must also be present in the proper proportions. In some cases, it may be necessary to raise the lime content to a point greatly exceeding that of the final mix, then, by addition of one or more other materials lower in lime, obtain the mix. The rock used at the Valley Forge plant is a metamorphosed argillaceous limestone of the Jacksonburg formation, the same formation as that of the Lehigh Valley cement rock (which occurs approximately 50 miles north), and its oxide composition is similar to that of the latter. The only practical differences between the two are that, as a result of metamorphosis, crystallization of the Valley Forge rock is considerably coarser and it contains less carbon than the Lehigh Valley rock as well as slightly more magnesia in the form of magnesian mica. The calcium carbonate content of the various strata in the Valley Forge quarry ranges from about 65 per cent to over 85 per cent, the average for the entire quarry being somewhat under the requirement for manufacture of cement, which usually is from 75 to 76 per

Jan 1, 1947

R. W. Raymond, New York, N. Y,:—Since the presentation of my note on this subject at the New York Meeting, Professor Louis has pointed out an error in my statement of his conception of " pitch "—namely, he understands the pitch, in the restricted sense which he proposes, to be the angle of inclination of the axis of an ore-body, measured on the vertical plane drawn through the body; whereas, I represented him as proposing to define " pitch " as the angle of inclination of an oblique body, measured on the plane of the dip, in the direction of the strike. The difference will appear upon consideration of the accompanying isometric projection, Fig. 1, in which ABCD represents the plane of the inclosing ore-deposit (vein or bed), and AC the axis of the oblique ore-shoot. ABE is the angle of the dip, as universally understood; and ACE

Jan 1, 1909

By AIME AIME

WHEN Vice-chairman Calvert Townley calls the next meeting of the Executive Board of the American Engineering Council of the Federated American Engineering Societies to order in Washington on Sept. 30, it will be the first meeting in that city for almost a year. It is probable that the Board will decide at this meeting whether future board meetings will be held regularly at the headquarters in Washington or whether the plan of meeting at various engineering centers throughout the country, as has been done during the past year, will be followed. The most important business coming before this .meeting will be the election of a president to succeed Herbert Hoover, who resigned after he became Secre¬tary of Commerce. Nominations to fill this vacancy were ordered 'at the last meeting of the Executive Board, to be reported at the September meeting. Special attention will be given the plans for the engineering assembly, extension of employment service, question of licensing and registration of engineers. The engineering assembly, committee has been appointed, with A. P. Davis as chairman, the other members being Philip N. Moore, L. P. Alford, John C. Hoyt and F. A. Vaughn. This committee will work out detailed plans for an assembly to be held in con¬junction with the annual meeting of the American Engineering Council in, January. Tentative plans provide for a three-day session; one day to be given to special meetings of the executive boards of member organizations and committees of the American Engineering Council; one day to the sessions of the American Engineering Council; and at least one day to discussion of some, special topic.

Jan 1, 1921

By Harry Perry

In the United States the state mining laws enacted in the late 1800s were the first laws to recognize that an employer had a responsibility to provide the employee a place to work that met at least some minimum safety standards. The coal mining industry was also the first major industry in the United States to be regulated in 1952 by federal safety laws, although federal inspectors had the right-of-entry as early as 1941. Within recent years, however, the Congress has enacted a number of federal safety regulations for a variety of industries, such as the Aviation Act (1958), National Traffic and Motor Vehicle Act (1966), National Gas Pipeline Act (1968), and Radiation Control for Health and Safety Act (1968). The fatality and injury experiences of the mining industry in the United States, while at a significantly higher rate than for industry as a whole, showed a continuous improvement until the last decade or two-at which time the rate leveled off. Although fatality and injury rates in foreign countries have been generally lower than in the United States, further improvement in those countries also has been difficult to achieve in recent years. It appears, therefore, that some major change in mining laws, combined with a radical improvement in mining technology and a more effective labor-management safety program, will be needed if further reductions are to be achieved in fatality and injury rates. At the same time, there is a growing awareness by society that an employee's place of work, where he spends nearly half of his waking hours, should be made as safe as possible. As increased consideration is given to means for achieving greater safety in all industrial situations, it is becoming apparent that more is required than merely providing physical safeguards on tools and machines. Rigorous, strictly enforced safety standards are useful, but more important is the desire of labor and management to make certain that industrial accidents are prevented. The pressure to achieve increased productivity, and thus receive higher wages, can be a significant deterrent to safe working practices. The temptation can be great to "take a chance" or "cut a corner" in order to speed up production. Public concern over all types of industrial safety in the United States was reflected by the introduction of a number of general occupational health and safety bills in Congress for the first time in 1968. While no legislation resulted, the hearings revealed that, although there were differences in how standards should be set and who should administer them, there was agreement on the need for adequate laws. Since the mining industry has been subject to safety standards longer than other industries, it is not surprising that advanced safety concepts for mining are being explored by the industry and the enforcing agencies. More complete and sophisticated accident reporting is being planned that will reveal the

Jan 1, 1976

By Herbert Hoover

I HAVE been greatly honored as your unanimous choice for President of this. Institute, with which I have been associated during my entire professional life. It is customary for your new President, on these occasions, to make some observation on matters of general interest from the engineer's standpoint. The profession of engineering in the United States comprises not alone scientific advisers on industry but, in great majority, is comprised of the men in administrative positions. In such positions, they stand midway between capital and labor. The character of your training and experience leads you to exact and quantitative thought. This basis of training in a great group of Americans furnished a wonderful' recruiting ground for service in these last years of tribulation. Many thousands of engineers were called into the army, the navy, and civilian service for the Government. Thousands of high offices were discharged by them with credit to the profession and the nation. We have in. this country, probably, one hundred thousand professional engineers. The events of the past few years have greatly stirred their interest in national problems.' This has taken practical. form in the maintenance of joint committees for discussion of these problems and support to a free advisory bureau in ,Washington. The engineers want nothing for themselves from Congress.. They want efficiency in government, and you contribute to the maintenance of this bureau out of sheer idealism. This organization for consideration of national problems has had many subjects before it, and I propose to touch on some of them this evening.

Jan 1, 1920

By Tegner C. Johnson

Just a few years ago, my company was referred to as the Marion Steam Shovel Company. Though we still make shovels, both two and eight-crawler types, the eight-crawler stripping shovel appears to have been replaced by the walking dragline for overburden removal and in some cases for the mineral as well. The walking dragline appeared in the coal fields in the early 1930's. It is popular because it can cope with overburden depths in excess of 100 ft and with blasted sedimentary rock, all at an O & O (ownership and operational) cost of ±10[c] per bank cu yd (bcy).

Jan 10, 1974

By A. L. Engel

STRICTLY speaking, ore-dressing does not commence until after the ore is in the mill bins, but where complex ores are treated and their minerals separated to make the best commercial concentrate with the lowest economical tailing, ore-dressing problems begin and often center in the mine itself. This does not refer to the grade of the ore, but rather to the frequent condition in which metallurgical results radically different from customary are obtained because of changes in the character of the ore treated. Different varieties of ore can usually be identified as coming from well-defined depths or zones in the mine, or from known sections of the orebody. Varying degrees of alteration of the ore, inclusions of harmful gangue material, or variations in the quantities of component metallic minerals are often causes of temporarily bad metallurgical results in otherwise successfully operated plants, especially those employing differential flotation to. recover several valuable minerals contained in the ore.

Jan 1, 1931

By P. E. Fitzgerald

SOME readjustments in the research programs of most of the oil companics and petroleum engineering schools have been made necessary by the war. The most obvious change has been the conversion from production engineering to problems more closely related to the nation's was effort. Many laboratories now devote much of their time to studies on products to be derived from petroleum. such as synthetic rubber, toluene, and substitutes for critical materials. Others are working to improve motor fuels including high-octane gasoline and the special lubricants required by the wide geographical range of the present conflict. Of great importance is the experience of the geophysicists, who are now devoting a great percentage of their time on instrument research and production or special apparatus required by the armed forces.

Jan 1, 1943

By Robert Linton

SPECIFICATIONS for clays serving raw materials in the ceramic industry usually contain the following items: (1) Chemical analysis, sometimes with mineralogical structure determined by microscopic investigation. (2) Maturing temperature and firing range, usually expressed in terms of pyrometric cone equivalent. (3) Shrinkage (drying and firing shrinkage separately). (4) Degree of plasticity. (5) Color after firing. Clays may be classified, according to the purpose of the classification, in several different ways, based on (1) Geological occurrence-transported, altered An place, indurated (shales). (2) Physical properties-plastic (bonding clays, ball clays) and nonplastic (flint clays, kaolins or china clays, bone clays). (3) Color. (4) Use. A common classification of clays for commercial designation, and one fol-

Jan 1, 1936

By H. J. Wasson, L. W. Mayer

The existing large stocks of raw materials have induced misgivings in the minds of many as to near-view prospects for a return to higher commodity price levels. Until stocks are materially reduced—and this operation will probably extend over a protracted period—a buyers' market will continue. Meanwhile the matter of production cost becomes more and more a factor of consequence to industrial management, finance and the investing public. With many commodities a general level of costs exists with which the public has been made familiar. Certain conditions surround these industries which, at the outset, determine whether there is a basis for sound commercial results. In other words, it can generally be determined in advance whether or not the cost of production is sufficiently below the normal average price to return a reasonable profit over the years. With all domestic agricultural products there are available exhaustive Government studies in the field of production costs. Such figures as the average cost of wheat, cotton, sugar, etc., are reiterated constantly. There are many products of foreign origin such as coffee, rubber, raw silk, etc., the production costs of which are to most of us matters of deep mystery. Forest products also are so diversified that few but specialists know what a thousand feet of lumber really cost at the mill, especially where remotely located. However, with respect to products of mines, production cost information has been widely disseminated. The literature is replete with such data. Here we find that without any special help from outside agencies the industry itself has given publicity to a large variety of cost figures. For example, we know, or know where we can ascertain, the cost of producing a pound of copper from Chile, Arizona or the Lake Superior district. In many cases we can secure from the company reports a vast amount of detail leading up to the cost per ton of ore and the cost per unit of the metal yield. These records are of great assistance to the mining industry as a means of estimating on new exploitations. This industry has been production-cost-minded almost from the beginning.

Jan 1, 1931

By C. J. P. Ball

Prior to 1939 the bulk of the magnesium metal produced outside of the united Stater was extracted directly from the ore and ifi the United States from magnesium chloride obtained as a by-product from the treatment of natural brines. A typical brine is one containing about 0.25 to 0.75 per cent bromine, 11 to 14 per cent sodium chloride, 9 to 11 per cent calcium chloride and 3 to 10 per cent magnesium chloride. The state of Nevada was known to possess large deposits of magnesite ore (MgCOs, the carbonate of magnesium), in Gabbs Valley, near Luning, approximately 350 miles north of Boulder Dam. Deposits mined in Europe were supplying magnesite giving 97 per cent MgCOs with about I per cent each of silica, lime and oxides of iron and aluminum. parts of the Luning de-posits Were almost equally rich, and the general average was of sufficiently high grade for production of magnesium. power to the amount of 200,000 kw. was available immediately from Boulder Dam, and water from Lake Mead, and it was this combination of available power, water, and ore that led to the initial proposal to erect a magnesium reduction plant in southern Nevada to reduce the magnesite ores from Gabbs. The extraction of magnesium metal from these magnesite deposits had been considered by the I. G. Farbenindustrie of Germany as far back as 1929. Mine and Oxide Plant The mine and oxide plant of Basic Magnesium Incorporated are perched upon the oride slope of the Paradise Range, at an altitude of 5000 ft., overlooking the 30 mile desert panorama of Gabbs Valley, Nevada. , Ore Occurrence The Gabbs magnesite ores occur in a thick series of flat, westerly dipping dolomites of Upper Triassic age. The mag-"esite bodies are exposed in steep canyon "areas encircling the north and east edges of a northerly projecting tongue of a roughly elliptical stock of granodiorite, which intrudes the dolomite. The magnesite mineralization is considered to be a a of calcium by magnesium through the agency of hydro-thermal solutions associated with the intrusion of the granodiorite. The ore bodies are of very irregular shape and distribution. Incomplete evidence points to deep pipelike replacement shapes that mushroom out erratically at various elevations. A wide latitude in the degree of magnesium replacement is reflected in a variance of quality from pure magnesite to magnesitic dolomite. The, ore is a massive crystalline mag-nesite. Though some differences in characteristics occur between ore bodies, in general the ore is a medium-grained carbonate varying in color from white, through all shades of gray, to black. Recrystallized dolomite, which encloses and occurs as

Jan 1, 1944

By Thomas T., Read

TWO American students entered the Ecole des Mines in 1856, Joseph Lesley of Philadelphia and Thomas Egleston of New York. Lesley remained there only one year, but Egleston completed the whole 'curriculum and received, in 1860, the certificate given to foreign students .in lieu of the official appointment and degree. awarded French students. Returning home he received, in 1861, an appointment by Secretary Henry of the Smithsonian Institution to sort, label, and arrange the collections of mineralogical and geological specimens which had been brought to Washington by the various government exploring expeditions in the West. Thomas Egleston, born in New York City on Dec. 9, 1832, was the son of Thomas Jefferson Egleston, who came to New York from Massachusetts some time before 1829. The first American ancestor of the family had settled near Dorchester. in 1630. T. J. Egleston and Joseph Battell established an iron-merchandizing business* at 166 South St., New, York, which prospered exceedingly; so much so that when Thomas J. Egleston died, July 12, 1861, his estate had a book value of over $500,000. Since an older brother was expected eventually to take over this business, Thomas, who had a liking for science, went to Yale,, where he completed the regular four-year course in 1854, and then remained another year for advanced work in chemistry under Silliman. I One biographer says he went to Europe, . early in 1-856, on account of his health. It was the custom at that time for wealthy young men to make a tour of Europe after completing their academic education. Whatever the precise reason, he began scientific work at the Jardin des Plantes in Paris but soon trans* It still operating as Egleston Bros. Inc., though no direct descendants of its founder are now living.

Jan 1, 1941

By R. W. Raymond

(Chattanooga Meeting, October, 1908.) THE immense commercial value of the Gayley dry-blast process has been established beyond controversy. The testimony of practical blast-furnace managers, on both sides of the Atlantic, agrees that it reduces the cost of pig-iron about $1 per ton; but from the same testimony it appears that this direct economy does not by any means cover its commercial advantages-in fact, that under conditions frequently encountered in practice, it presents other benefits of even greater immediate financial importance. To this point I shall recur in a later part of the present paper. The history of the reception given to this invention, especially on the other side of the Atlantic, has repeated an experience familiar to American engineers. First, the reports of our practice were rejected as theoretically impossible, according to generally accepted notions and formulas; then the figures were reluctantly accepted ; and finally the attempt has been made to explain how they could have been obtained. As to the Gayley dry blast, we Americans have been for several years in the last stage of the discussion, and the rest of the professional world is rapidly coming to it. Meanwhile, the remark has been repeatedly made that, whatever Mr. Gayley's process may turn out to be worth, it was not an invention on his part, but simply the energetic and persevering execution of a procedure already proposed by others. This question I wish to discuss first in the present paper. I. WHAT DID MR. GAYLEY INVENT Realizing that this is not the place for detailed argument on an issue of patent law, I shall not undertake to quote and criticise the publications prior to Mr. Gayley's first patents. It may be admitted, without such critical analysis, that the possi-

Jan 1, 1909

By A. M. Rowe

A considerable quantity of experimental hydrocarbon K-factor data has been correlated as a function of component identity, temperature, pressure and convergence pressure. To utilize these correlations effectively, convergence pressure must be determined accurately, particularly for volatile mixtures near their critical states. This paper presents phase diagrams that illustrate physically the meaning of convergence pressure. A new method, referred to hereafter as the "critical composition method", will be outlined for calculating convergence pressure. An example calculation has been included to illustrate how to use this new technique. INTRODUCTION The principle of hydrocarbon phase composition calculations as applied to such diverse problems as optimizing separator performance or predicting fluid compositions at various stages of reservoir depletion is the same. Usually, temperature, pressure and the numbers of moles of the various components of the fluid contained in a given volume are known. Questions answered by the phase calculation are what fraction of the total mass of fluid exists in each of the equilibrium phases, and what are the mole fractions of the various components in the two phases? To answer these questions the Natural Gasoline Supplymen's Assoc. (NGSMA) has correlated a considerable quantity of K-factor data as a function of temperature, pressure, component identity and convergence pressure.l To use these correlations to obtain the best answers possible, one must be able to calculate the convergence pressure. This is particularly true for over-all fluid compositions in the neighborhood of the critical state. STATEMENT OF THEORY Use of convergence pressure as a correlating parameter is based on a postulate similar to the law of corresponding states used in correlating PVT data of hydrocarbon gases. This postulate, which proposes convergence pressure as a correlating parameter, has been stated as follows: "The equilibrium vaporization constant for one component in a complex system is the same as the equilibrium constant at the same temperature and pressure for the same number or kind of components, providing only that the convergence pressures of the two systems are exactly the same at the same temperature and that the components are of the same homologous series".2 This law, as with all laws of physics, cannot be proven theoretically. It can only be justified by experimental data supporting its premises. Arguments have been made that this law violates Gibb's phase rule. For example, consider a four-component system. By Gibb's phase rule, which is thermodynamically rigorous, f = c — P + 2 =4, for a four-component, two-phase system. Thus, four independent intensive variables must be specified to establish completely all the intensive variables of the equilibrium phases. On the other hand, according to convergence pressure theory, only three variables need be specified for any mixture containing four different components. These variables are temperature, pressure and convergence pressure. Thus, the two laws appear to be in conflict. However, the convergence pressure postulate is more restrictive than Gibb's phase rule. It applies only to mixtures of the same homologous series. Hence, these two concepts are not in disagreement. PHASE DIAGRAMS DESCRIBING CONVERGENCE PRESSURE This paper presents phase diagrams grading from the simple two-component system to the more complex four-component system to illustrate convergence pressure. A less abstract definition of convergence pressure will be stated that is

By C. M. Marquardt

Tramp iron and steel moving on a conveyor belt cause small currents to be generated in a coil situated in a strong magnetic field, which are converted to an alternating current and are amplified. The output voltage from the amplifier fires a thyratron with a relay in its anode circuit, which actuates a howler and simultaneously drops a spot of marker material on the belt.

Jan 1, 1950