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By Walter P. Jenney

An investigation, conducted by the author, was begun in September, 1889, by the United States Geological Survey, having for its object the study of the questions bearing upon the occurrence and manner of formation of the deposits of lead- and zinc-ores in Missouri and the adjoining States. The field-work was completed in December, 1891. During the first season the State Geological Survey of Missouri furnished an assistant, and in other ways co-operated in the research within the boundaries of that State. In order that the ore-deposits of the southwest might be compared with those of other sections of the Mississippi valley, an examination was made of the lead- and zinc-mining area of Wisconsin-Iowa, and of the argentiferous lead-mines of the region extending westward from Hot Springs, Arkansas, to Indian Territory. In the discussion of the general geology, and in comparisons between the ore-deposits of the Mississippi valley and those of the Rocky Mountains, the writer has drawn largely from his personal experience, having been engaged for many years in professional work as a geologist and mining engineer in that region. The Director of the U. S. Geological Survey and the Scate Geologist of Missouri have kindly consented to the publication of the present paper. While giving the more important economic results, an endeavor has been made to set forth the unity of plan which appears in the formation of the deposits of lead and zinc of the Mississippi basin, and to show their relation to the argentiferous ores of the Rocky Mountains—that the ores of gold, silver, and mercury, and also of copper, antimony, zinc, and lead, have a universal common origin, irrespective of the geological formations in which they occur.

Jan 1, 1894

By Richard H. Sprute, Dennis J. Kelsh

Slow-settling, fine-grained suspensions can often be dewatered and densified by applying direct current between buried electrodes. Although water removal rates and power expenditures depend on physical and chemical properties of the treated slurries, metal mine tailings from Idaho, Colorado, and Mexico have responded well in laboratory testing, as have 29 samples of ultrafine coal waste from mines in nine states. This Bureau of Mines report reviews field tests at two Idaho metal mines and describes the recent installation at the Henderson molybdenum mine near Empire, Colorado, and the treatment of coal sludge at a Clinchfield Coal Co. preparation plant near Dante, Virginia.

Jan 1, 1980

By L. T. Leyson, U. C. Tainton

Some time ago, at ameeting of the Institute Prof. J. W. Richards1 said, "I take exception to the statement that all the factors in the production of electrolytic zinc were known long ago.... There is possible in my opinion an improvement of perhaps 50 per cent. in the new electrolytic processes." An examination of the literature of the subject will show the justness of Professor Richards' contention. The work of the earlier investigators was carried on in the shadow of difficulties that, today, are hardly more than memories. We seldom hear now of zinc sponge, that bête noir of the electrolytic-zinc pioneers. Zinc sponge was the name given to a peculiar, soft, black, non-adherent form of zinc deposit that was utterly useless for melting into ingot form. At the big plant at Cockle Creek, New South Wales, in 1897, Edgar Ashcroft2 said that the solution in the plant would suddenly, and without ascertainable cause, go' "bad" and begin to deposit spongy zinc. The most delicate, even spectroscopic, methods of analysis were unable to detect any difference between "good" solution and "bad" solution; either form might change to the other on being kept for a while. When it is added that an outbreak of this insidious disease (which appeared to be infectious, or at least contagious) could be dealt with only by discarding the solution and washing out all tanks and pipe lines, some idea may be gathered of the troubles of the zinc electrometallurgist in what may be spoken of as the "sponge age" of electrolytic zinc. Thanks to the efforts of a number of investigators, we are today able to diagnose with considerable certitude the nature of the malady that puzzled Ashcroft and his co-workers. The researches of Mylius and

Jan 1, 1924

By W. L. Saunders

It has been estimated that the value of the mineral products of the United States is about $2,000,000,000 a year; that about $25,000,000 is expended annually for explosives and that about double this sum is paid in wages where blasting is done. The value of the mineral products does not adequately express the importance of the industry involved in the excavation of rock and ore because of the enormous sums of money expended in tunnel driving, in quarries, and in open-cut excavation generally. We know that the Catskill Aqueduct in the neighborhood of New York, which is now nearing completion, has cost some $165,000,000 and that about one-third of this may be rated as rock excavation. These illustrations are given in order to call attention to the great importance of an industry the extension and development of which in our industrial life depend so much upon the economics of rock drilling. Reference has been made to the new Catskill Aqueduct. There are three aqueducts leading into New York, each built at periods separated by some 20 years of time. The first one, known as the Old Aqueduct, conveys the waters of the Croton river to New York City in a manner which reminds one of the old Roman aqueducts, the ruins of which are still in evidence. The engineers who laid out these old conduits sought to direct their lines around the hills and into the valleys, at all times avoiding the rock. When it was necessary to cross a river or a deep ravine, a bridge or causeway was constructed. High Bridge, over the Harlem river, is an arched masonry viaduct differing in no essential features from the aqueducts of the Romans. When the second Croton Aqueduct was built, about the year 1890, the art of drilling rock had been so far perfected, and the use of explosives, through the invention of dynamite, had become so general, that this waterway was planned and executed on straight lines, following rather than avoiding the rock. The second Croton Aqueduct is a tunnel through rock, about 32 miles in length; material gneiss, almost as hard as granite. Its construction was made practicable by sinking

Jan 1, 1914

Unlike the bituminous part of the coal industry, the production of anthracite has been fairly well publicized; in fact until about 1845 whenever the coal industry of Pennsylvania was mentioned in papers, magazines or books, anthracite only was meant. Beginning with shipments by river in 1820 fairly complete records of shipments were published each year, and as this variety of coal was the only one used for domestic purposes east of the mountains and north of the Potomac, there was considerable interest in the producing fields on the part of the public. Transportation of anthracite was the cause of the building of the early canals in the state, and later, of some of the earliest railroads. In most publications it has been assumed that commencement of shipments in 1820 was the beginning of the industry; this is far from being so, and it is with the earlier developments this chapter will deal, leaving the later and better known records to existing publications. (See Table No. 53.) The first reference to coal in Pennsylvania by Gabriel Thomas in 1698 has already been mentioned,1 it could only have been anthracite in that section; although of course, he never saw any coal there. Little coal was used excepting by smiths for many years after that. In 1728 the Coventry Forge paid the expenses of a man "to town for Sea Coall and Steell for ye hammer;”2 in 1729 New Castle coal was sold in Philadelphia;3 in 1740 an advertisement mentioned, "very good Pitt and Sea Coal at 18 pence a bushel; at which price 'tis allowed to be cheaper Fewel for Hearth Fireing than Wood at the present Rates,"4 a view not shared by most of the people there for about eighty years; in 1752 Newcastle coal was again mentioned.5 There are no references to coal in the writings of any of the Moravian missionaries, although some who settled near Mauch Chunk in 1746 said that the Indians there made their pipe heads of a soft black stone, which was much more apt to have been slate than anthracite." Several stream

Jan 1, 1942

By William Plank

IN PAST YEARS, engineering educators and others have been able to study the problems relating to en-gineering education in the United States with only inadequate and, frequently, inaccurate data at their command. For the first time there is now available fairly full and accurate information on this subject, gathered and compiled by the Board of Investigation and Coordination of the Society for the Promotion of Engineering Education. This board, of which W. E. Wickenden is the director, has for the past four years been carrying out fact-finding investigations into "the objects of engineering education and the fitness of the present day curriculum," under a grant of funds from the Carnegie Corporation of New York. Twelve bulle-tins have already been published by the board and others are in the process of preparation. The studies made, thus far, have been of the various phases of engineering education in general as well as of the major branches of engineering. Within the past year. the board has completed a study of mining engi-neering education by means of a questionnaire sent to members of the Institute. A special committee, con-sisting of Charles E. Locke, Allen H. Rogers and the writer, cooperated with the board in drafting certain parts of the questionnaire and in selecting the mailing list. Similar studies have been made through the mem-bers of the four other national societies. The results of these studies have been published only in mimeo-graphed form, therefore, in order to place the data before the members of the Institute an incomplete sum-mary of the replies to the A. I. M. E. questionnaire is here given. The full report will be available for distri-bution at the annual meeting in February. The questionnaire was sent to 306 members of the Institute, a proportion about equal to the proportion of the membership of the other national societies can-vassed; 152 members replied to the questionnaire, 55 per cent of whom had received college degrees in some branch of engineering connected with the mineral in-dustry. Forty-seven educational institutions were rep-resented in the replies. Seventeen different positions were held by the members who replied, with 24 con-sulting engineers at the head of the list, 20 managers, 16 superintendents, 11 presidents, 10 professors, 6 deans, and others.

Jan 1, 1928

By J. R. Long, R. S. Dean, F. S. Wartman, E. T. Hayes

The production of titanium in I5-lb. lots and with a purity sufficient to be consolidated into ductile metal, as described in a previous paper,' has provided adequate material for a study of the physical properties of titanium and a more thorough examination of its working qualities. Data on the physical properties reported in that paper were obtained on metal fabricated by a fixed procedure, standardized for the purpose of control of the reduction, and are representative only of material fabricated under those conditions. There are many possible variables in the working schedule, which will have significant effects on the properties of the finished material; and since the previous working methods were not necessarily the best, an investigation of the fabrication of titanium by other methods was undertaken. In this work the consolidation of the powder by pressing and sintering was conducted essentially as outlined in the report cited' and all efforts were centered on fabrication methods for those powders and the proper- ties produced by them. Hardness, density, microstructure, and tensile properties were determined at various stages in the working and annealing; and resistivity measurements were made on a few bars and drawn wire. Consolidation of the PowdeR The screen analysis of the available titanium powder is given in Table I. No attempt was made to alter the size distribution from that noted because this powder, although coarse by normal powder-metallurgy standards, produced acceptable compacts suitable for the present work. Because of their large specific surface, finer powders are more contaminated by oxygen and produce harder compacts, which are difficult to work. The powder as produced is soft, compresses in a normal fashion, and exhibits very little tendency to adhere to the die surfaces. Unlike aluminum and magnesium powders, it can be readily pressed without the use of die lubricants. When compacted at 50 tons per

Jan 1, 1946

By J. R. Long, E. T. Hayes, R. S. Dean, F. S. Wartman

The production of titanium in I5-lb. lots and with a purity sufficient to be consolidated into ductile metal, as described in a previous paper,' has provided adequate material for a study of the physical properties of titanium and a more thorough examination of its working qualities. Data on the physical properties reported in that paper were obtained on metal fabricated by a fixed procedure, standardized for the purpose of control of the reduction, and are representative only of material fabricated under those conditions. There are many possible variables in the working schedule, which will have significant effects on the properties of the finished material; and since the previous working methods were not necessarily the best, an investigation of the fabrication of titanium by other methods was undertaken. In this work the consolidation of the powder by pressing and sintering was conducted essentially as outlined in the report cited' and all efforts were centered on fabrication methods for those powders and the proper- ties produced by them. Hardness, density, microstructure, and tensile properties were determined at various stages in the working and annealing; and resistivity measurements were made on a few bars and drawn wire. Consolidation of the PowdeR The screen analysis of the available titanium powder is given in Table I. No attempt was made to alter the size distribution from that noted because this powder, although coarse by normal powder-metallurgy standards, produced acceptable compacts suitable for the present work. Because of their large specific surface, finer powders are more contaminated by oxygen and produce harder compacts, which are difficult to work. The powder as produced is soft, compresses in a normal fashion, and exhibits very little tendency to adhere to the die surfaces. Unlike aluminum and magnesium powders, it can be readily pressed without the use of die lubricants. When compacted at 50 tons per

Jan 1, 1946

By Albert Smith

THE creep properties of metals have as-sumed increasing importance in recent years and many investigations have been made on various phases of the problem. In the past year the annual lectures of the Insti-tute of Metals Division1 and the Iron and Steel Division2 were concerned with this subject, and are excellent reviews. For many years the creep properties of lead and lead alloys have been investigated at the Central Research Laboratories of the American Smelting and Refining Co., and it is hoped that the present paper will contribute knowledge of some of the factors that influ-ence creep. Lead, being a metal that recrys-tallizes readily at room temperature, is an excellent material upon which to investi-gate creep phenomena because of the sim-plicity of the apparatus needed, and it might be expected that results would apply to some extent to elevated-temperature tests of other metals.

Jan 1, 1940

By F. W. Bremmer

The experiments described in this paper constitute the preliminary work of an investigation outlined to determine the combined effects of steam and temperature on the endurance properties of certain steels. Essentially of a fundamental nature, it was found necessary, in order to make the investigation comprehensive, to test materials treated to give a wide range of properties. The work reported deals chiefly with nickel steel with one series of tests including nitriding steel. Such a study involves numerous variables, and requires an endurance-testing machine of rather special design. Testing Machines The testing machines used were designed by C. E. Weaver;l they are a modification of the White-Souther and McAdam types. Each was driven directly by an individual 1/2-hp. 115-volt direct-current motor, running at a speed of 2200 r.p.m. Fig. 1 shows the assembly drawing and Fig. 2, a photograph of one of the machines. Specimen B is held by the rotating specimen holder A inside the steam box F, which is closed at the top by a tight-fitting, elliptical cover G. The load is applied to the specimen through the rod D and bearing C. E is an oil pipe leading fromthe lubrication system to the bearing C. The steam, which comes from the power house, is admitted through an inlet (not shown in Fig. 1) at the side of the box, the drain being at the bottom. Steam packings were placed around the rod D and the rotating shaft at H, from which the water was drained by means of a vacuum, which usually showed a gage reading of about 10 in. The temperature was measured by a mercury thermometer, and the pressure by a steam gage. Method of Applying Load After the motor has been started and the specimen as a consequence put in rotation, the load is applied by placing the foot pedal A (Fig. 2) in contact with electromagnet B, the winding of which is connected electrically in series with the motor. This operation releases the support under the weights that constitute the load. By this means the load

Jan 1, 1930

By P. W. George

This paper presents geological data regarding deposits of over 7,500,000 tons of fine-grained sulphide ore in barite gangue. A series of pyroclastics and arkoses was intruded by sills of quartz porphyry in connection with batholithic intrusions of granite 3 miles from Buchans. Gentle folding, with fracturing acid shearing of tuff beds and intruded quartz porphyry, accompanied and followed the intrusion of granite and porphyry. The sulphide-barite mineralization is localized primarily in fractured and sheared tuff beds, but also in the sheared quartz porphyry. Two structures have proved particularly favorable for mineralization-one, the center of an anticline; the other, a series of weak, incompetent tuff beds intruded by thin sills of quartz porphyry and located between strong beds of arkose. During the folding the weak tuff with intruded quartz porphyry was intensely sheared and contorted and subse-quently mineralized by sulphides and barite.

Jan 1, 1937

On the following pages are abstracts of papers published by the Institute during the year 1931 as Technical Publications, Preprints, and in bound volumes. For abstracts of papers that appear in bound volumes in 1931 but that were published as Technical Publications in 1930, see the Transactions, 1930. Papers that appear in the volume in which this list is printed are not abstracted here. Many of the Technical Publications have been reprinted in bound volumes. Information regarding this disposition, and number of pages in each paper, may be found in the list beginning on page 616. The abstracts are grouped as follows: Page Page Metal Mining....................... 578 ing and Metallography of Non-Milling and Concentration........... 578 ferrous Alloys)................586 IronandSteel...................... 580 Coal Division.. ................ 592 Petroleum and Gas.............. 598 Mctallurgy......................... 585 .............. 613 Institute of Metals Division (Found- Geophysical Prospecting......... 613 Metal Mining Use of Models for the Study of Mining Problems. By Philip B. Bucky. (Tech. Pub. No. 425, 12,000 words.)—This paper describes a research project undertaken to provide a means of studying the behavior of weighty structures such as mines, dams, foundations, etc., with models of the same material in the laboratory. The paper shows that in general it can be done. The underlying theory is explained, the apparatus which was developed and built to do this is described, and the results of laboratory experiments with sandstone mine structures are given. There is discussion of the accuracy of results with the present equipment, the model size necessary, and of the size and type of equipment necessary for the obtaining of results of practical value in the field. Milling and Concentration Ball Mill Studies, I. By A. W. Fahrenwald and Harold E. Lee. (Tech. Pub. No. 375. 25,000 words.)—This paper presents the results of an extensive experimental study of some of the numerous elements entering into ball mill grinding. All apparatus used was equipped with ball bearings. Every experiment was accompanied by a power measurement accurate to 0.005 hp. Quartz was used. Each element studied, such as ball load, was varied systematically. Power curves were obtained for the mill for three general sets of conditions; namely, (1) balls only (2) balls and quartz and (3) balls, quartz and water. For each general condition, power curves were obtained for various mill speeds, ball loads and ball sizes. For conditions 2 and 3, feed sizc and weight and pulp dilution also were studied as variables. The mill output, in grams of finished product per unit of time, was obtained for each test. In a general way, output (mill capacity) paralleled the power data and this attached

Jan 1, 1931

By Harrison Schmitt

SINCE the U. S. Geological Survey published the data on the Central Mining District collected by Lindgren and Graton1 and by Paige2 much new information has been obtained by development and mapping, but none of it had been published until recently when Kniffin3 published on Fierro, Lasky4 on the Ground Hog mine, Thorne5 on Santa Rita and Landon6 filed a thesis on the Fierro-Hanover-Santa Rita area at the Uni-versity of Chicago. During the years 1927-1930 much of the writer's time was spent in mapping the geology and ore deposits of this district, particularly in the area of the zinc deposits at Hanover. Some of the data collected are presented here. Previous publications have been freely drawn upon and additional data used that were generously supplied by L. M. Kniffin, Wilfred Wright and Gerald Ballmer. Thanks are due Augustus Locke, Samuel G. Lasky, Kniffin, Wright and Ballmer for suggestions and critical readings of the manuscript, and to the Empire Zinc Co. (a subsidiary of the New Jersey Zinc Co.) for the privilege of publishing material compiled largely at its expense. The relation of the Central. or the Santa Rita-Hanover-Fierro district to the Silver City district is shown on Paige's geologic map in the Silver City folio.7 Granodiorite porphyry and quartz-monzonite porphyry

Jan 1, 1933

By Walter O. Snelling

Continuation of the discussion of the paper of WaltER o. SnelLIng, presented at the New York and San Francisco meetings, February and September, 1915, respectively, and printed in Bulletin No. 100, April, 1915, pp. 695 to 704 and Trans., li, pp. 657 to 671. A. C. McLaUghlin, San Francisco, Ca1.—It seems to me that Mr. Snelling's work, if it is what it appears to be, is one of the most important contributions to petroleum technology that has been brought out in the last 25 years. If his end products are what they seem to be, he has made. a discovery, which, in my judgment, will revolutionize the petroleum industry. As to industrially carrying out these processes I do not think there is the slightest difficulty, for I have had some work recently where crude oils were handled successfully at a temperature of 750" F, and pressure of 750 lb. per square inch. William A. WillIams, San francisco, Ca1.—What metal did you use, Mr. McLaughlin? A. C. McLauGHILIN.—Ordinaly seamless tubing, extra strong. William A. Williams.—Tests were made in Dr. Rittman's experimental plant at Pittsburgh, upon samples of residuum furnished by Mr. Bell, the residuum being the remainder of the crude oil after the lighter fractions had been removed. After the material had been run through Dr. Bittman's plant, yields of from 43 to 58 per cent. of material, boiling under 150" C. were obtained. The distillate had a peculiar odor, due to the presence of benzene, toluene, and other unsaturated hydrocarbons. W. N. Best, New York, N. Y.—What is the difference between the Rittman and the Snelling process or system? William A. Williams.—he fundamental difference is that reactions take place under relatively higher temperatures and pressures and with none of the oil present in its original or liquid state, while the reactions secured by Mr. Snelling and other investigators have been from the liquids in the presence of some vapors. Under such conditions as Mr. Snelling operates, the temperatures and pressures used are limited and the flexibility in the control of these variables is extremely limited when compared with the Rittman process.

Jan 1, 1916

By K. L. Meissner

It is well known that the so-called pure aluminum contains noticeable amounts of impurities, chiefly iron and silicon, and many investigators have studied the forms in which these impurities exist. Hanson and Archbutt1 state that iron exists in aluminum as FeA13 and silicon as elementary Si. The solubility of FeA13 in solid aluminum is practically zero, or at least so small that the smallest trace of this compound is always visible as a separate constituent. Under the microscope an untrained eye can hardly distinguish, without etching, the two constituents FeA13 and Si, but they can be differentiated by suitable etching reagents. Anderson2 also found the same results. At the same time, Merica, Waltenberg, and Freeman3 found a constituent of unknown composition. They found a small thermal effect, at 610" C., on the cooling curves of aluminum with small amounts of iron and silicon. The intensity of this effect increased with increasing silicon content, until an effect occurred at 576" C. due to the eutectic between aluminum and silicon. The authors ascribed the effect at 610" C. to a compound, which they call "X constituent." It was thought to be a ternary compound containing iron and silicon and could be observed under the microscope as dark particles. Dix4 has published unetched photomicrographs of an aluminum with 0.51 per cent. iron, 0.99 per cent. silicon, and 0.32 per cent. copper that shows three constituents: the dark Si (black in the figure), the lighter FeA13, which appears in half tone and crystallizes in needles, and a constituent of the same color as FeAL3 but of different crystal form, often resembling Chinese script. This last constituent, Dix thought, is a compound of Fe and Si; not the compound FeSi but a compound containing a relatively small amount of silicon. Therefore an alloy of aluminum. iron, and silicon (the copper should not be regarded in the following considerations) must contain the following four constituents: Al, FeA13, Si, and a compound of Fe and Si. This, however, does not agree with the laws of chemical equilibrium.

Jan 1, 1926

By W. W. Colpitts

To me, as to many other students of railroad needs, the necessity for reducing the dead weight in railroad rolling stock, both passenger and freight, has been apparent for, many years. The problem of weight reduction of passenger cars is so entirely different from that of freight cars, is so much more to the fore at the present moment and would seem to be so much nearer solution, that I shall confine myself in these remarks to the former. On the surface of things there would appear to be no close association of thought between the decline in traffic on the railroads, which is largely responsible for their present deplorable financial condition, and new metal alloys. It sounds like a trick riddle a school boy might propound to his parents. But that there is a relationship between the two, and one that bids fair to be of great mutual benefit to the railroads and the makers of .high-strength metal alloys, I hope I shall be able to show before I have finished. To make the situation understandable to those who are not entirely familiar with the problems of railroad management, and, who feel that the railroads have not moved as rapidly as they should in the direction of greater use of newer materials and newer appliances, I shall have to review briefly the course of recent railroad history. If in this part of my talk I seem to the professional man to be a little off key I feel sure my remarks will be fully appreciated by the business man who cannot understand why he is not making better headway in selling things to the railroads. To do this I shall have to go back to war times for a moment.

Jan 1, 1936

By J. Parke Channing

These days of great industrial and social problems in America produce many suggested solutions and great changes. The practical engineer and employer of labor views these problems differently from the labor leader or the social reformer, but as never before he is sincerely interested in solving them in a way that will be just to all. The inevitable tendency of the day is toward "industrial betterment," " safety," '(industrial education," " efficiency," and the many other things which have become so familiar to progressive employers. There is no longer any question that these things are worth while from both the human and economic standpoints. They "pay" in dollars and cents. The very center of final success in improving conditions and increasing the efficiency of workingmen must be the spirit of fairness and a knowledge on the part of the employer of how to deal sympathetically and intelligently with his employees. Every progressive employer knows how greatly he desires foremen, superintendents, managers and others who possess these qualities. On the other hand, we are all familiar with serious mistakes made by young graduates of engineering schools who have had no opportunity to develop these qualities, and who have no real appreciation of the worth of the workers. Indeed, one wonders whether much ill-feeling, labor difficulties, and many strikes could not be avoided if such men had the right attitude. Is there any way of remedying this condition? If this particular difficulty can be solved, if these young engineers, many of whom are our coming leaders of industry, can be given the right perspective and the right understanding of these other problems in addition to fair, sympathetic methods of handling men, many of our other problems will be solved—not at once, but gradually and permanently, as these men make good and become influential in paths of industrial righteousness and industrial peace. Many progressive employers of to-day have enlarged their own perspective and realize the great importance of enlarging the perspective of those who shall follow them. How can it be done? For seven years a movement has been making

Jan 1, 1915

By Robert Bosworth

THE liability for damages to the surface caused by subsidence is an ever present threat in all underground mining. In ordinary lode mining, this threat rarely materializes into an action, due to the method of mining metalliferous ores, the dip of the veins, and the nature of the ground itself. In the mining of coal, however, this threat is very real. The coal frequently lies close to the surface, in beds underlying large areas of land of which the surface is suitable for: agricultural or urban development. Furthermore, the coal is generally mined by the "room and pillar" method and when the pillars of coal are removed, the subjacent support is destroyed. This question of the duty of surface support has now become a very live one in Colorado. What was waste prairie land a few years ago has become valuable agricultural land dotted here and there with growing towns. Frequent references will' be made here to Colorado conditions and adjudicated cases, but those conditions and cases and the conclusions to be drawn therefrom are applicable to all coal-mining states. Briefly stated, the question is "Does the owner of the substrata or underlying mineral owe any duty of surface support to the owner of the superjacent strata or surface?" There is no absolute duty of support owed by the mineral owner and this assertion is made with full knowledge of numerous expressions to the contrary by courts of Pennsylvania, Illinois, Colorado and other coal-mining states. Whether or not any duty exists depends upon the circumstances surrounding each case, and since in the nature of things those circumstances are rarely identical, there can be no absolute rule.

Jan 1, 1928

By D. B. Crouch, D. A. Poulter

The engineering and metallurgical assessment of the McLaughlin Project ore body concluded that an open-pit mine and cyanide leach mill process would be feasible, producing both waste rock and residual mill tailings. As a part of the planning and permitting process, site selection studies were conducted for the tailings and waste rock disposal. The site selection process began with a regional identification of potential disposal sites and proceeded through 1) regional screening, 2) elimination of sites with obvious fatal flaws, 3) qualitative ranking of site evaluation criteria, 4) quantitative ranking of sites, 5) field investigation, 6) evaluations of field data, and 7) selection of preferred sites. Based on this approach of site rankings and field evaluations, tailings and waste rock disposal sites were selected and recommended for the preliminary design phase of the permitting and project development process. The site selection study provided the documentation necessary to justify the use of these sites for waste disposal and enabled Homestake Mining Co. to anticipate and integrate environmental concerns with agency requirements into the planning process.

Jan 1, 1986

By L. Yarborough, L. R. Smith

This paper presents results of a laboratory study of retrograde condensate recovery by revaporization into dry injection gas. Flow tests were performed in 10.6-ft long sand packs at 100F and 1,500 psi. In three runs methane revaporized the liquid from a n-pentane-methane mixture in the presence of immobile water. TWO of these tests were water-wet, and the third was totally oil-wet. In the three runs n-pentane recovery was complete after 2.5 hydrocarbon PV of injection. There was no significant performance difference between the two wettability extremes. In a fourth experiment, a methane-hydrogen sulfide mixture revaporized a synthetic light, sour condensate. No water saturation was present. Equilibrium compositions and volumetric data were obtained for the four-component condensate. The heavy component, n-beptane, was removed after 6 PV production. Comparison of the effluent fluid compositions with known equilibrium data shows that the flowing fluid was equilibrium vapor and that the mixing zone between equilibrium vapor and dry injection gas was short. Data indicated that complete recovery of retrograde liquid occurred after it was contacted by a sufficient quantity of dry gas. INTRODUCTION When pressure declines below the fluid dew point in a gas condensate reservoir, a liquid phase forms. In this process, referred to as retrograde condensation, the quantity of liquid formed is frequently small enough that the liquid is not a flowing phase. To prevent loss of valuable retrograde liquids, the process of dry gas cycling has been employed for several years as a more or less standard practice. In this procedure the reservoir pressure is maintained above the fluid dew point so that the liquid components may be produced as vapor and then separated at the surface. Although full pressure maintenance by gas cycling seems ideal in terms of preventing liquids loss, several factors can reduce the atuactiveness of such an operation. From a study of a condensate reservoir in Alberta, Canada, Havlena et a1.1 con-cluded that cycling under conditions of declining pressure leads to economic advantages and to a high recovery of hydrocarbon liquids. This study considered effects of volumetric sweep efficiency, retrograde behavior of the original wet gas and revaporization characteristics of the retrograde liquid when contacted by dry gas. The first major work concerning revaporization of liquid in a gas condensate system is that of Standing et a1.2 Calculations based upon the PVT behavior of a recombined gas condensate fluid indicated that all retrograde liquid can be recovered if it is contacted by a sufficient quantity of dry gas. The paper considered the effect of variable permeability upon the recovery of retrograde liquid. Standing et al. concluded that recovery of heavier components in the retrograde liquid is greatest if reservoir pressure is allowed to decline below the dew point prior to dry gas injection. Since the work of Standing et al., several laboratory studies have been reported which show that recovery of hydrocarbon liquids by vaporization into dry injected gas can contribute to increased recovery above that obtained by ordinary production practices. Vaporization from retrograde condensate,3 conventional oil4-7 and volatile oil8 reservoirs has been considered. There is little work that deals with revaporization recovery from condensate reservoirs. This study demonstrates that vapor-liquid equilibrium exists when a dry gas is injected into a porous medium containing retrograde condensate; investigates the effect of wettability on revaporization of retrograde condensate; and provides an indication of the amount of dry gas necessary to

Jan 1, 1969