Search Documents

By M. D. Cooper

UNDERGRADUATES in mining engineering may be prepared for work by giving them sound instruction in the courses generally considered essential to the profession. The industry is not deeply concerned about the details of those courses. The average man in the coal industry does not wish to insist upon a rigid program. Therefore, he differs little from those in the teaching profession who evidently are not unanimous in their opinions, or all college catalogs would be alike. For the good of the profession, it is just as well that there should be differences in regard to details. It appears that students graduating in mining engineering from the accredited institutions receive similar instruction. It is taken for granted that the graduate will have a good understanding of English, mathematics, mechanics, electricity, chemistry, physics, geology, and surveying, in addition to his major courses in mining. Somewhat belatedly, industry hopes he will have had at least an introduction to the subject of labor relations, the importance of which is only too clear at present. The coal industry expects, of course, that students in mining engineering will be taught the strictly mining subjects by men who have had practical experience in the mines and who keep themselves well informed in regard to current methods. While the undergraduate is subject to the control of members of the teaching profession, industry expects him to be trained in certain ways that are not a part of his textbooks, but can be made an inseparable part of his development by the skillful supervision of his teachers. Of the desired characteristics, dependability is of the utmost importance. Probably most employers would overlook certain short-comings if the young graduate demonstrated that he was thoroughly dependable. If he always appeared at the right place at the right time with the proper equipment, he would soon be well established as a welcome member of his organization. The graduate who gets a reputation for being undependable will have little opportunity for advancement. Closely allied to dependability is loyalty. Athletic teams and social groups in college tend to develop loyalty which may well be carried over into industry. This does not mean that the graduate has to be satisfied with customary practices. The average manager is glad to see the graduate make constructive criticism as long as he demonstrates his loyalty at the same time. It is important that his loyalty keeps him alert arid ready to take helpful action for the benefit of his organization, and especially to stand with it during times of stress. With or without an introduction to labor relations in college, the graduate is expected to develop ability in this most important field. Beginning with himself, he will find it essential to deal agreeably with his immediate associates. Getting along in friendly fashion with his own small group will be a great help as his responsibilities increase and he is required to deal with larger numbers of persons. On a higher scale, his interest in his community may grow at the same time by voluntary work in any one of a great number of useful activities. Industry expects the graduate engineer to be a mature man at the time he gets his first job. Supposing that he has better than average intelligence, industry expects him to continue to grow intellectually and to fit himself for responsible jobs when they are offered to him. For this reason, employers are apt to look over his college record to see what he did that would indicate his fitness for leadership. There is interest in knowing what he did beyond the requirements. As evidence of his mental growth, it is expected that the graduate will do independent thinking; that he will not take too much for granted. When he reads a report, he should develop the ability to see whether the subject is new or whether it is just a description of an old method that has been superseded by something better. For the same reason, the graduate should be able to accept conditions that have been arrived at by sound experience rather than cling to something else that seems better in theory. In this connection, it may be remarked that the ability to operate successfully a personal budget will be noteworthy, as it may be assumed that a man who knows how to conduct his own affairs will be prepared to assume the larger responsibilities of industry. Membership in AIME will indicate to the employer that the graduate is interested in the mining industry as a whole. Therefore, it is good evidence of something more than a local outlook. Quite apart from college training and mental ability, the newly employed graduate will be expected to be willing to do hard manual labor for a time. This will give him an understanding of the actual conditions of work done by those he supervises later. He will gain their confidence and be able to see that the work is carried on in a safe and efficient manner. Part of this experience may be acquired in his summer vacations during his undergraduate career. Such work would make a favorable impression on a prospective employer, especially if the graduate showed a willingness to continue it until he was prepared for something better. To summarize, the man in authority in the coal industry will not quarrel with the professor of mining engineering over details of curriculum. He will be pleased if the school sends him graduates who possess a good foundation in the courses studied, and who may be depended upon to do their work faithfully and intelligently. Such men will be ready when the time comes to assume their places as leaders of an essential industry.

Jan 1, 1951

By M. D. Cooper

UNDERGRADUATES in mining engineering may be prepared for work by giving them sound instruction in the courses generally considered essential to the profession. The industry is not deeply concerned about the details of those courses. The average man in the coal industry does not wish to insist upon a rigid program. Therefore, he differs little from those in the teaching profession who evidently are not unanimous in their opinions, or all college catalogs would be alike. For the good of the profession, it is just as well that there should be differences in regard to details. It appears that students graduating in mining engineering from the accredited institutions receive similar instruction. It is taken for granted that the graduate will have a good understanding of English, mathematics, mechanics, electricity, chemistry, physics, geology, and surveying, in addition to his major courses in mining. Somewhat belatedly, industry hopes he will have had at least an introduction to the subject of labor relations, the importance of which is only too clear at present. The coal industry expects, of course, that students in mining engineering will be taught the strictly mining subjects by men who have had practical experience in the mines and who keep themselves well informed in regard to current methods. While the undergraduate is subject to the control of members of the teaching profession, industry expects him to be trained in certain ways that are not a part of his textbooks, but can be made an inseparable part of his development by the skillful supervision of his teachers. Of the desired characteristics, dependability is of the utmost importance. Probably most employers would overlook certain short-comings if the young graduate demonstrated that he was thoroughly dependable. If he always appeared at the right place at the right time with the proper equipment, he would soon be well established as a welcome member of his organization. The graduate who gets a reputation for being undependable will have little opportunity for advancement. Closely allied to dependability is loyalty. Athletic teams and social groups in college tend to develop loyalty which may well be carried over into industry. This does not mean that the graduate has to be satisfied with customary practices. The average manager is glad to see the graduate make constructive criticism as long as he demonstrates his loyalty at the same time. It is important that his loyalty keeps him alert arid ready to take helpful action for the benefit of his organization, and especially to stand with it during times of stress. With or without an introduction to labor relations in college, the graduate is expected to develop ability in this most important field. Beginning with himself, he will find it essential to deal agreeably with his immediate associates. Getting along in friendly fashion with his own small group will be a great help as his responsibilities increase and he is required to deal with larger numbers of persons. On a higher scale, his interest in his community may grow at the same time by voluntary work in any one of a great number of useful activities. Industry expects the graduate engineer to be a mature man at the time he gets his first job. Supposing that he has better than average intelligence, industry expects him to continue to grow intellectually and to fit himself for responsible jobs when they are offered to him. For this reason, employers are apt to look over his college record to see what he did that would indicate his fitness for leadership. There is interest in knowing what he did beyond the requirements. As evidence of his mental growth, it is expected that the graduate will do independent thinking; that he will not take too much for granted. When he reads a report, he should develop the ability to see whether the subject is new or whether it is just a description of an old method that has been superseded by something better. For the same reason, the graduate should be able to accept conditions that have been arrived at by sound experience rather than cling to something else that seems better in theory. In this connection, it may be remarked that the ability to operate successfully a personal budget will be noteworthy, as it may be assumed that a man who knows how to conduct his own affairs will be prepared to assume the larger responsibilities of industry. Membership in AIME will indicate to the employer that the graduate is interested in the mining industry as a whole. Therefore, it is good evidence of something more than a local outlook. Quite apart from college training and mental ability, the newly employed graduate will be expected to be willing to do hard manual labor for a time. This will give him an understanding of the actual conditions of work done by those he supervises later. He will gain their confidence and be able to see that the work is carried on in a safe and efficient manner. Part of this experience may be acquired in his summer vacations during his undergraduate career. Such work would make a favorable impression on a prospective employer, especially if the graduate showed a willingness to continue it until he was prepared for something better. To summarize, the man in authority in the coal industry will not quarrel with the professor of mining engineering over details of curriculum. He will be pleased if the school sends him graduates who possess a good foundation in the courses studied, and who may be depended upon to do their work faithfully and intelligently. Such men will be ready when the time comes to assume their places as leaders of an essential industry.

Jan 1, 1951

By C. M. Myrick

(Cleveland Meeting, October, 1912) THE following notes are submitted in the belief that they may interest some of the many owners of small water-power plants, so generally used in mining-work throughout the West. A small and somewhat primitive quartz-mill was taken over by a leasing company, and a 10-stamp battery was installed. Originally, power had been furnished by a Pelton wheel ; but, since the supply of water depended on the rate at which snow was melting on the mountains, a steam-plant had been added to help out during cold spells. This auxiliary plant was antiquated and expensive to operate, and, soon after starting up the remodeled mill, it broke down completely; so that it became necessary to get all the power possible out of the Pelton wheel,. with its ever-varying water-supply. The pipe-line, about a quarter of a mile long, was made up. of assorted sizes, from 7 to 11 in. in diameter; and, since it was buried deep under snow, there were no data from which to calculate the theoretical size of the nozzle. The stream being at this time at a low stage, it was important to make the most efficient use of the available water. This was done by using a nozzle large enough to pass the whole supply-taking care, however, to limit the size so as not to lower the water-level in the tank at the head of the pipe-line. As the weather became warmer, the nozzles were gradually enlarged to meet the increasing volume of water; but a point was finally reached where further enlargement only gave decreased power. Evidently the loss from friction had more than balanced the gain from the increased flow through the pipe. However, the area of nozzle that developed the, maximum power from the pipe-line had been found. This was used; and the surplus water was allowed to run to waste at the head of the line.

Oct 1, 1912

By G. Austin Schroter, Ian Campbell

ALTHOUGH there is now an extensive literature on the bleaching clays, not a great deal of material is to be found concerning the geological features of these deposits and their bearing on problems of exploration and development. At the same time, chemical and crystallographic research on the clay minerals during the past few years has laid a suitable foundation upon which to base conclusions of economic value drawn from field observations. All of the criteria and deductions herein presented are based upon extensive field work by the senior author, both in the United States and Canada, and when subjected to the ultimate tests of development and exploitation they have held up remarkably well, despite the fact that many of these conclusions apparently have not been reviewed in the literature heretofore. The nomenclature of the bleaching clays is rather confusing in the light of present-day commercial standards and has even led to litigation." The old term "fuller's earth" is largely based upon trade usage and the definition of the term therefore is dependent upon the changing standards of commerce. For statistical purposes the Bureau of Mines81 classes as "fuller's earth" all natural bleaching or filtering claylike materials that possess high adsorptive capacity without previous chemical treatmerit or activation. Conversely, the so-called activated or acid activated clays are now generally recognized as any clay mineral or mixture of the clay minerals whose adsorptive capacity has been developed to commercial standards by chemical or physical treatment. Therefore, without attempting to propose any additions to the nomenclature of bleaching clays, this paper will refer to naturally adsorptive clays and activable clays, respectively, for the two types indicated.

Jan 1, 1940

By M. L. Brashears

IN the last 15 years industrial use of ground water has more than doubled, and in 1951 amounted to 5 billion gallons per day. A similar sharp increase in the utilization of ground water for irrigation and public-water supply occurred in the same period. In many areas rapid increase in withdrawal from wells has taken place almost entirely unhampered by regulatory control and with little or no integration of effort. As might be expected, the chief interest in many regions has been maximum production rather than sustained perennial yield. As a result, widespread depletion of underground reservoirs and deterioration of the quality of the water stored in them has taken place in many areas, even though total pumpage in the United States is far below ultimate potential. Of even more concern is the fact that excessive withdrawal has drawn salt water into the reservoirs beneath many heavily populated centers along the Atlantic, Gulf, and Pacific coasts, causing costly abandonment of pumping plants.1

Jan 10, 1953

By Howard Eavenson

ONE who has been trained in belief in the law of supply and demand and its effect upon prices finds it difficult to adjust himself to the minute regulations imposed by the New Deal, and also to the bewildering changes of government policy as expressed within a short period of time between the antitrust laws and the N.R.A., and later by the Bituminous Coal Conservation Act of 1935. A survey of the coal industry since the World War, both in this country and Great Britain, however, shows that regula-tion of some sort is needed if any stabilization is to be achieved and if the Wage structure and economic welfare of the many communities dependent solely upon coal are to be maintained. Let us look at what has happened to the industry since 1920, which can be considered as the end of the period affected by the war influence. This discussion will be confined solely to bituminous coal, although many of the general conditions are equally applicable to anthracite, the position of which now is at least as bad as that of the softer variety. Since 1920-to the end of 1934-the production of coal has decreased from 568.7 million to 358.4 million tons, or 37 per cent; the number of mines from 14,766 to 6,258, or 58 per cent; the average annual production per mine has changed from 38,512 to 57,425 tons, or 50 per cent. The number of large mines has increased considerably, and the number of men employed has decreased from 639,547 to 458,011, a reduction of 28 per cent, while the average output per employee has changed from 4.0 to 4.4 tons, or an increase of 10 per cent. The average price per ton of coal at the mine has varied from $3.75 to $1.75. During that time wages decreased largely until 1933 and since that time have increased, until now the rates paid are- considerably above those in other occupations, although the actual yearly earnings are low, because of part-time work. From 1920 to the signing of the Jacksonville wage agreement in 1924, about two-thirds of the men were union members and practically all of the nonunion mines were south of the Ohio River; with the fixing., of the high wage scale of that agreement, which soon proved to be an uneco-nomic one, many of the mines found that they could not retain their business, so gradually changed to nonunion. By 1928 the proportion

Jan 1, 1936

In situ mining is no longer a "last ditch" approach for recovery of uranium, but a proven and competitive method of exploiting sedimentary deposits. Today, in any feasibility study of uranium properties, the project manager would be prudent to compare the economics of in situ methods with conventional surface and underground techniques. In this comparison of in situ and open-pit mining, John J. Borkert and Carl E. Gerity of Occidental Minerals Corp., evaluated a group of hypothetical uranium deposits using the three most sensitive depositional characteristics of depth, size, and grade. Their conclusion: in situ is generally the better method to maximize total net profits and return on investment. At uranium values of $40 per pound, their analysis found open-pit mining to he unprofitable, generally, when stripping ratios were greater than 30:1, the deposit grade-thickness (GT) was 0.5 or less, or the ratio of depth to GT was greater than 200.

Jan 10, 1978

By Helen L. Cannon

BOTANICAL methods of prospecting for metalliferous ores are based on the premise that deposits at depth may be reflected chemically in surface vegetation. For the past several years, on behalf of the Atomic Energy Commission, the U. S. Geological Survey has investigated on the Colorado Plateau the application of botanical methods to uranium prospecting. Results suggest that orebodies may be found under a considerable cover of barren sandstone through the absorption of uranium and associated trace elements by plants growing at the ground surface. Plant physiologists have demonstrated that uranium is a necessary nutrient for plant growth and therefore is present in all plants.' The amount present is small but measurable. The absorption of uranium by plants growing over ore deposits forms

Jan 1, 1955

By Homer E. Harris, William C. DeSieghardt, William A. Burgess

Under sponsorship of NIOSH, Eastern Associated Coal Corp., with the Harvard School of Public Health acting as a subcontractor, has determined for the first time the effective protection provided to working underground coal miners wearing approved half-mask dust respirators. This was done by conducting 187 man-shifts of in-mine testing in four different coal mines; included in this testing were 37 different test subjects representing 11 different job classifications and 5 different models of respirators. Presently available respirators on average provided significant protection levels to working miners even though on an intermittent use basis. However, "average" protection values were well below those achieved under laboratory conditions. Protection levels varied from man to man in a given work crew and from day to day for a given man. In addition, some of the factors affecting use and effectiveness of presently used respirators are discussed, as are areas in which improvements are needed, and the need to consider these improvements in context of a systems approach.

Jan 1, 1975

By G. G. Gunther, C. L. Boeke

THE zinc deleading processes at the Parral and Santa Barbara mills are described separately to provide a basis for comparison. Although the two procedures are fundamentally alike, there are some differences in application to meet specific conditions. The Asarco mill at Parral in the State of Chihuahua is a flotation plant treating 1450 metric tons per day of complex sulphide copper-lead-zinc ores. In general, the procedure used for selective separation of the minerals into a copper, a lead, and a zinc concentrate follows the usual practice. First, a bulk copper-lead concentrate is floated and then separated into a final copper and a final lead concentrate by the sulphurous acid process. A small tonnage of high grade gravity lead concentrate is tabled from the bulk copper-lead cleaner tailing before it is reground so as to avoid undesirable over-grinding and sliming of this portion of the lead mineral. Next, a zinc concentrate is floated from the lead rougher tailing and, as described later, is separated into a final lead product and a final zinc concentrate. Finally, the zinc rougher tailing receives a strong scavenger float to remove all recoverable middling values for regrinding and return to the flotation circuits. The slime is separated from the scavenger flotation product, and only the sand portion goes to the regrind section. The minerals in the separated slime are extremely resistant to all methods of selective separation and pose one of the major problems awaiting solution. Nevertheless, the slime shows a profit when mixed with either the lead or the zinc concentrate, except when metal prices are very low, so it is accepted as a final product for lack of a more profitable method of handling it. In contrast, the minerals in the reground sands of the

Jan 1, 1953

IN order to make his work easier, every master of any art whatever keeps always to the road that he has learned or that his skill or good judgment has shown him to be the best. Although there are various methods used in making moulds for guns, depending on whether they are large or small, nevertheless almost the same road is traveled in all. You must first know that it is necessary to make a pattern of wood or clay exactly as the gun is to be, with those ornaments of cornices and rings that you wish to be in the bronze. Let us suppose that you wish this pattern to be of wood. You must try to have for this a piece of fir as long and thick as you wish, dry, solid, and well seasoned, with few or no knots if possible. This should be longer than the gun by the length of the head and foot rests where it is pivoted [83v] so that it can be turned as on a lathe. On the end where the mouth is to be it should project out enough so that you can attach a feeding head at the top of the casting. You can make or have this pattern made round, fluted, spiral, or half fluted, as you like best, making the measurements exactly correct with all care and attention. Then two bearing trestles must be fixed firmly in the ground, one at the head and one at the foot, as is usually done with roasting spits and as you see drawn here. This done, if it is fluted, put the cornice pieces at the place where you wish the mouth to be and at the foot where the fire is applied. These are

Jan 1, 1942

Just three years after researchers announced its development, Dravo is putting the finishing touches on a new $60-million Thiosorhic lime mine/kiln complex near Maysville, Ky. Electric utilities in western Pennsylvania and Ohio have already signed long-term contracts for over three-quarters of the projected 907 000-t/v (1-million-stpy) production. Thiosorbic lime, a flue gas desulfurizing agent, proved in industrial testing that at high emission levels (greater than 3000ppm SO2) it could be twice as effective in SO2 capture as conventional lime, while eliminating the major problem of scaling and plugging of scrubber equipment.

Jan 4, 1977

By Gordon A. Gross

Banded siliceous manganese-iron bearing sediments recognized as distinctive facies of Algoma-type iron formation constitute low-grade resources of manganese in many countries. Manganiferous facies associated with oxide and carbonate facies of iron formation have iron to manganese ratios ranging from 0.2 to 2 and commonly about one. Manganiferous facies up to 30 m thick occurring separately or with other iron formation facies are associated with cherts, carbonates, shales, turbidites, tuffs, and lavas. Primary cherty manganiferous facies and their gondite metamorphic equivalents represent significant manganese resources and are protores for higher-grade deposits derived by secondary enrichment processes.

Jan 1, 1983

By W. R. Webb, M. O. Peterson

WHEN men drive haulage equipment ranging up to 22 tons in an open pit operation, they must live with the realization that their safety is dependent upon the machines they drive and how well they operate them. The hazards inherent in their jobs must be recognized, met, and defeated. It comprises a never ending struggle toward perfection-an almost un- obtainable goal. The Jones & Laughlin Benson Mines, at Adirondack State Park in New York, created a safety program which resulted in only one three day lost time accident from April 1948 to April 1952. At the very start of the program, management of the open-pit operation recognized the hazards existing at Benson. The program was designed to meet each danger. With a knowledge of the problem faced, the process of minimizing each facet was planned along lines of maintenance of equipment and training of personnel. Its success is evident. In the ever-present struggle, care and maintenance of machines and application of experience to new equipment design are mainstays. Truck Haulage Benson produced 2.9 million tons of crude iron ore and 1.6 million tons of waste in 1951. To do the job, truck mileage reached 500,000 miles. The tremendous mileage emphasized to safety planners, the fact that the more work done, the greater the possibility of risk in haulage operations. Instrumenting the aim of the safest equipment possible is a methodical servicing program. Like other segments of the drive, the servicing program is based on greater production with fewer accidents. Every truck is serviced at least once per eight-hr shift. Examination includes inspecting and tightening wheel studs, checking tires, steering apparatus, lights, brakes, wipers, heaters, fire extinguishers, and refueling. A running history of the equipment's operating life is kept in the form of service and maintenance records. Machine operators are constantly on the alert for malfunctioning of units. At the first sign of trouble the truck is returned to the garage for exchange. No truck functioning incorrectly is kept on the line, regardless of its shift check schedule. The program resulted in a reduction of the number of costly overhauls and cut down the number of haulage accidents. Miscellaneous Mobile Equipment Auxiliary units, operating within the pit, have presented definite safety problems. The highest accident rate in the pit occurred on trucks carrying water and bits to the churn mills. The weight and awkwardness of bits and drill stems, combined with remote delivery points were direct causes of numerous accidents. Here, the problem has been one of equipment handling, rather than haulage. All air compressors for secondary drilling are truck mounted, facilitating mobility. In addition to making it easier to move the equipment, truck mounting has eliminated many of the hazards connected with relocating machinery. By making air compressors independent of other units, drilling operations have been speeded up considerably. Unseen rocks in the path of moving vehicles are a constant source of tire damage. At Benson the problem has been met by supplying each loading crew with a bulldozer for cleanup operations. The pitman directs the dozer operation, and when truck drivers back into loading areas, he serves as an extra set of eyes. Modern Truck Garage Provides Drive-Through Service Simplicity is the essence of any preventative maintenance program. At Benson, a modern garage, with a drive-through service bay simplifies servicing. Shift inspection of the 22-ton haulage units is accomplished with minimum delay and maximum thoroughness. Major repair work and periodic overhauls are done in the repair section of the truck garage. Crane facilities for handling heavy assemblies ease the job and add to the safety factor. Other mobile machinery,

Jan 1, 1952

Manganese ore from the Black Rock, Kramer, and Black Jack mines in Tooele and Jaub Counties, Utah, are of acceptable grade, the U. S. Bureau of Mines has announced. Payment of a premium price of 252¢ per lb to the Copper Range Co., of Michigan for the output of its White Pine mine, has been agreed to by the DMPA. The contract will be limited to $28.6 million worth of copper. The agreement follows an RFC loan grant of $57 million to bring the White Pine property into production within three years. Increases of 5 to 6 cents over the Lake copper ceilings have been granted to the Calumet & Helca Consolidated Copper Co., for operation of "high cost" deposits, according to Jess Larson, DMPA administrator. Mr. Larson expects the move to add about one million lb of copper per month to the supply. The agreement can be cancelled on 60 days notice and is terminated automatically in the event copper ceilings are removed.

Jan 1, 1952

By R. J. De Angelis, J. B. Cohen, A. Nelson

In this note several recent results on twinning in copper shock-loaded with planar shock waves will be presented and the role of the twins in recrystalliza-tion will be discussed. The twinlike markings first observed in shock-loaded copper by smith1 were identified as twins by De Angelis and Cohen.2 This identification has been confirmed by others.3 In Ref. 2 it was also shown that there is an orientation dependence for twinning at low shock pressures, such that twins in a crystal loaded in [lll] form in the rarefaction or tensile wave but in

Jan 1, 1967

By N. D. Shutler

This paper describes a numerical mathematical model of the steamflood process that depends on fewer restrictive assumptions than models previously reported. The solution, however, is obtained economically. Example calculations are presented that, on comparison with experimental results, tend to validate the model. Results that expose certain process mechanics are discussed. The model describes the simultaneous flow of three phases — oil, water and gas — in one dimension. It includes the effects of three-phase relative permeabilities, capillary pressure, and temperature- and pressure - dependent fluid properties. Interphase mass transfer of water-steam is allowed, but the oil is assumed nonvolatile and the hydrocarbon gas insoluble in the liquid phases. The model allows heat convection in one dimension and two-dimensional heat conduction in a vertical cross-section spanning the oil sand and adjacent strata. The hydrocarbon-steam gas composition is tracked, but the effect of gas composition on water-steam phase behavior is neglected. The model is solved numerically in three separate stages. The three-phase mass balances are solved simultaneously using Newtonian iteration on nonlinearities occurring in the accumulation terms. The energy balance is solved separately by noniterative application of the alternating-direction implicit procedure. Separate solution of the composition balance is accomplished by straightforward solution of the finite difference equations. The method of effecting nonsimultaneous, stable solution of the mass and energy balances is the key to the success of the model. INTRODUCTION Mathematical tools as well as laboratory and field experiments are necessary to help us understand the complex steamflood process. A mathematical model can expose process mechanics and show the relative importance of process variables, but this ability is often limited by restrictive assumptions. Most known models of steam processes,l-5 with the exception of the model of Gottfried,6 are "simplified" in that they involve analytic approximations and require many restrictive assumptions. The primary utility of these methods lies in the routine use as an aid in engineering design. By contrast, the comprehensive model presented here is numerical and requires far fewer restrictive assumptions. It finds its primary utility as a research tool. It serves as an aid in understanding the nature of the process, in interpreting laboratory experiments and in evaluating and developing simpler mathematical models for engineering design. The major reason why previously presented models have been confined to the "simplified" class is evidenced by the one published exception. In 1965, Gottfried6 presented a numerical model for the combustion process of which the steam process is a subset. The result is a comprehensive tool (though it neglects capillarity and two-dimensional heat conduction) that is troubled with convergence problems and that requires 2 to 3 hours of IBM 7094 time to complete a calculation. Though our present model does not simulate combustion, it does consider capillarity and two-dimensional heat conduction and it overcomes the convergence and computer-time problems. MATHEMATICAL DESCRIPTION OF STEAMFLOODING FLUID FLOW The equations employed to describe three-phase fluid flow are of a familiar form. Darcy's. law provides expressions for the velocities of the three phases (oil, water and gas), which, when combined with oil, water and gas mass balances, give the partial differential equations governing flow of the

Jan 1, 1970

By George Ashley

IT has been said that the Pittsburgh bed is the most valuable single mineral deposit yet known to man. The figures in Table 1 are presented in substantiation of that claim. TABLE 1.-Pittsburgh Coal Bed to Dec. 31, 1934 Estimated Recov- State Thousands of ( Value erable Reserves Tons Mined (1935), Thousands of Tons Pennsylvania 3,144,000 $4,922,000 7,500,000 Ohio 493,391 843,699 3,000,000 West Virginia 650,000 1,027,000 5,500,000 Maryland 183,224 254,681 20,000 Totals 4,470,615 $7,047,380 16,020,000 PRODUCTION AND VALUE In order that the figures of Table 1 may have any weight, a statement must be made to show how they were arrived at. Because, to the writer's knowledge, no accurate separate figures ever have been kept of the production and value of the Pittsburgh coal bed, the states will be considered separately.

Jan 1, 1936

By Dale C. Matthews, Donald L. Simpson

Hecla Mining Company's Lakeshore Mine and Metallurgical complex near Casa Grande, Arizona, is the first plant in North America to utilize the roast/leach/electrowinning process for production of cathode copper from sulfide concentrates. Oxide copper ores are also mined at Lakeshore. Using sulfuric acid and sponge iron by-products of the roast/leach operation, the oxide ore is leached in vats, the copper is precipitated with iron and recovered as cement copper. This paper will describe the roast/leach facilities and discuss the operating conditions at which more than 95 percent of the copper in concentrate is made soluble in acid solutions while less than 5 percent of the iron is rendered soluble. More than 97 percent of the sulfur contained in concentrate is captured either as strong sulfuric acid or as soluble sulfates in leach liquors. The iron rich residue after leaching is pelletized and reduced to sponge iron in an SLRN reduction kiln.

Jan 1, 1981

By L. M. Cathles, H. R. Spedden, E. E. Malouf

Fluid flow through an igneous rock formation will occur mainly through fractures. A non-diffusing or slowly diffusing tracer (such as .5µ silica spheres identifiable under electron microscope) will arrive at a monitor well when enough fluid has been injected to displace the volume of water in the flow fractures between the injection and monitor wells. A rapidly diffusing tracer (such as NaC1)-will diffuse into the matrix blocks and so a volume of tracer nearly equal to the total fluid volume contained in the rock formation between injection and monitor wells must be injected before significant diffusing tracer arrival will be noted. The flow fracture porosity is typically one hundred times smaller than the total porosity of an igneous formation. The shift between diffusing and non diffusing tracer arrivals, together with the diffusional characteristics of the tracers, can define the diffusional accessibility of the matrix blocks of an igneous formation. A field test of these concepts and the problems encountered will be described.

Jan 1, 1974