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By D. A. Martin, Laird Crocker, W. I. Nissen

The Federal Bureau of Mines has developed a process for removing SO2 from stack gases. The process comprises absorption of SO2 in an. aqueous solution of sodium citrate, citric acid, and sodium thiosulfate, followed by reaction of the absorbed SO2 with H2S to precipitate sulfur and regenerate the citrate solution for recycle. A pilot plant was operated at The Bunker Hill Co. lead smelter in Kellogg, Idaho, to assess the feasibility of using the process for flue gas desulfurization. Nominal capacity of the pilot plant, which treated .tail gas from the lead smelter sintering furnace, was 1699 standard meters cubed per hour (15 degrees celsius) of 0.3- to 0.7-percent-SO2 gas yielding about 272 net kilograms of sulfur per day. The pilot plant was operated for about 4500 hours and produced more than 45 net tonnes of sulfur. The operation demonstrated that (1) more than 95 percent of the SO2 could be removed from the lead smelter sintering furnace tail gases, (2) regeneration of the citrate solution with H2S and precipitation of sulfur in conventional stirred vessels was readily controlled and highly efficient, (3) the precipitated sulfur could be continuously recovered as a 99.5-percent-pure product by kerosine flotation and melting, and (4) the 77- to 79-percent-H2S gas used for sulfur precipitation could be readily produced from pilot plant product sulfur, natural gas, and steam. Projected operating costs, including capital charges, for a citrate plant, installed at a 118 000-tonne-per-year lead smelter and treating 49 271 standard meters cubed per hour of lead smelter sintering furnace tail gas, are estimated to be $384 per tonne of sulfur.

Jan 1, 1976

By L. K. Smith, E. M. de Kock, J. van der Walt

A unique and systematic approach for analysing alternative methods of ventilating and cooling large hot mines is presented. The important factors that have a bearing on ventilation and cooling requirements and practices, such as air flow through the mine, geographical distribution of heat loads, micro ventilation considerations etc., are dealt with. Analysis of these leads to the definitive ventilation and cooling strategies, air and water process design, detail specifications and design of associated plant and equipment.

Jan 1, 1982

By Gustaf Ising

For relative gravity measurements, the author in 1918 described an instrument1 of which the essential part consists of a highly astatized, standing pendulum turning about a horizontal elastic axis. This type of instrument has been used recently in practical field work, therefore a description of its principle and technical development is given herein. Part I, describing the principle, is a direct translation of the original Swedish paper.1 Part II gives an account of the practical elaboration of the instrument, together with some description of measure-ments performed.

Jan 1, 1937

By Richard Moldenke

So FAR as the quality of the product is concerned, the history of the production of pig iron for foundry purposes is one of constant retrogression. The steps in this deterioration began with cold-blast charcoal pig iron, then anthracite iron, coke iron; then gradually warm to hot-blast coke iron, with the charcoal furnaces also heating their blast to get greater tonnages, and finally the present day hot-blast coke irons with scrap additions to the ordinary burden that, according to one European report, have gone as high as 135 per cent. Parallel with this quality retrogression is the enormous increase in furnace tonnages from about 15 tons daily to over 1000 tons per day in exceptional instances of modern practice. The key to this situation is economic pressure. The effect is a growing differentiation between furnace production for gray iron and malleable foundries and for the production of commercial steel. As the foundry is often compelled to draw upon the pig irons made for steel purposes, for economic reasons, whereas the steel industry does not draw upon foundry pig irons proper, the situation is resolving itself into one of grave consequence for the life of the gray-iron castings industry, and hence the intensive present-day feeling in foundry circles for rigid specifications to govern the quality of pig irons sold for foundry use. In the discussion of a paper on the use of scrap in the blast furnace held recently in the Institute, a very pertinent remark was made by one of the participating furnacemen, who confessed that "the things found wrong by the foundryman with his iron were beyond his depth." It may be added that those things are also beyond the depth of most foundrymen who, however, know from their results that they are getting poorer castings today with many pig irons than they did with those same brands in former years. Under the former fracture buying, the foundryman at least could select the strongest metal, as judged by the sledge, from various brands of similar fracture and pig section, and his results proved the soundness of his conclusions. With the advent of iron analysis, and in spite of the growing uniformity of the metal through greater tonnage

Jan 2, 1927

By J. S. Wakeman

INTRODUCTION The primary purpose of comminution circuits in the mineral industry is to reduce an ore to a particle size that will permit separation of the valuable minerals from its gangue constituents. Wide variations in the mineral content and physical characteristics can and do occur throughout a given mineral deposit From the standpoint of their effects on the comminution characteristics of an orebody, these variations may not be identified by the normal sampling and analysis procedures utilized to delimit an orebody and to characterize its grade distribution. The proper design of a comminution circuit for a mineral deposit is very important to the success of that enterprise. It is also an expensive unit process both from the standpoint of capital and operating costs. It is, therefore, essential that any sampling program be designed to identify the variations that may occur that will affect this circuit. Because of the variety of comminution systems that are available, it is also essential that the sampling and subsequent evaluation program be sufficiently comprehensive to identify potentially inappropriate systems or flowsheets. It would be impossible to describe in a single chapter the techniques and approaches that should be utilized for sampling every type of orebody. Each orebody is unique and requires a sampling and testing program designed to its specific requirements for exploration, characterization and circuit design. The following is a general discussion of the guidelines to be used and considerations to be made in establishing such a program. SAMPLE SELECTION When sampling an ore deposit for the purposes of equipment and flowsheet selection for comminution, it is important that the sample composites for grind testing be chosen on the basis of how they will affect the comminution circuit rather than just how they might affect the subsequent metallurgical operations. For example, grindability, classification and liberation size characteristics are more important to the comminution circuit than ore grade. Mineral deposits may contain a multiplicity of ore types that can vary extensively in the dissemination of minerals and optimum liberation size requirements; and may also vary as much as 100% in ore hardness. The accumulation of samples for grind characterization should be done in such a way as to allow the identification of this variation. A proper mineralogical evaluation of the samples obtained to characterize an ore deposit can be a great aid in identifying the individual ore types within the deposit

Jan 1, 1982

By R. Stefanko, R. H. King, L. A. Morley

Coal mine fires, injuries and electrocutions, and many production delays have resulted from trailing cable splice failures. Research was carried out at The Pennsylvania State University to determine the failure causes and recommended solutions. The study revealed that current splice kit materials are generally adequate with the exceptions of connector flexibility, adhesives bonding, and abrasion characteristics of taped jackets. Research indicated that the most prevalent breakdowns result from workmanship defects. Therefore, guidelines for improved splice construction are reported in detail.

Jan 1, 1976

By Byron S. Gottfried, Guan Qi Zhao, John W. Tierney

Equations for predicting the performance of vacuum filters and centrifuges used for coal dewatering are presented. These equations are the basis for a dewatering module which has recently been added to the Coal Preparation Plant Simulator developed at the University of Pittsburgh under the sponsorship of the Department of Energy. The module provides for mechanical degradation in the centrifuge; loss of fines to centrate or filtrate; changes in size and gravity distribution; changes in ash and sulfur content; as well as final moisture content of the dewatered product. Inputs to the module are the flow rate of the coal to be dewatered, a washability analysis of the coal, and parameters describing the operation of the vacuum filter or centrifuge. Typical results obtained using the module are presented. There are adjustable parameters which can be varied to match plant operation or experimental data if desired.

Jan 1, 1983

TO THE, BOARD OF DIRECTORS OF THE AMERICAN INSTITUTE OF MINING AND METALLURGICAL ENGINEERS Gentlemen -The following report covers briefly some of the more important activities of the Institute during the year 1923. In my report for the year 1922, I drew attention to the falling off in membership of the Institute due to the depressed condition of the mining industry in several lines and the inability of many of our members to find profitable employment in mining or its associated branches. A number who were unemployed during 1922 established connections during 1923, but a still greater number have been forced to resign or drop their membership during 1923 Fortunately, the number dropped is not so great as in the previous year. The Employment Service conducted by, the four Founder Societies bears witness to the trend in business For the young men just out of college, there are plenty of opportunities at small salaries, there are plenty of opportunities for them as laborers; but for the mature members, those of experience, there are few calls During the last eighteen months, our Employment Service has been able to place only six of our members out of every hundred engineers for whom it has found work. Another loss which this Society has suffered, but which is not felt so keenly by our sister societies, is in its foreign members. The A. I M. E. has always had a large foreign membership, but of recent years exchange has been so heavily against many European and South American coun¬tries that a large number of members residing abroad have been compelled to relinquish their membership Almost invariably these members express keen regret because of the necessity that confronts them, and almost invariably the writers express hope that present conditions will not last long and that they will soon be able to ask for reinstatement. Having stated the darkest side of the picture first, it may now be drawn to your attention that in spite of these losses the number of persons applying for membership was decidedly encouraging. From the quality point of view, the membership has not gone back¬ward The Membership Committee has declined to recommend many

Jan 1, 1923

By W. C. Wright

A PRACTICAL program of education for workers of the mining industries is being formulated by the Federal Board for Vocational. Education in cooperation with the States in which this industry is a dominant one. The Federal Government last year passed a law, known as the Federal Vocational Education Act, that provides for the promotion of vocational' education and for cooperation with the States in the promotion of such education in agriculture and trades and industries and in the preparation of teachers of vocational subjects. More than 1,000,000 men in the continental United States are employed in mines and quarries. The following table, from the-1910 Census Report, shows the relative importance of mining and manufacturing pursuits: Manufactures Mines and Quarries Employees 7,405,313 1,109,410. Capital $18,428,269,706 $3,380,525,841 Value of product $20,672,051,870 $1,238,410,322 Of the more than 1,000,000 men employed in mining, almost three-fourths are engaged in the, production of bituminous and anthracite coal; one-fifth, in the production of copper, iron, lead, zinc, and other metals; and the remainder in getting out structural and miscellaneous materials from quarries. The meeting of the needs of the coal-mining industry, therefore, is the problem of greatest importance in the point of numbers to be served. Moreover, the dangers in coal mining are greater than in metal mining. Practically all States have set up educational and technical standards , for the position of foreman, boss, superintendent, etc., and every applicant for these positions must have a certificate of competency. The qualifications, too, are becoming increasingly difficult in the field of technical information. In some States, every miner must have a certificate, which is issued by the mine examining board. only after an oral examination.

Jan 1, 1919

C. P. BOWIE, San Francisco, Cal.-In my work with the U.S. Bureau of Mines, I have been detailed to report on oil storage containers, and in going around the country I have, been much interested in, the possibilities in the use of concrete for such containers. In talking with a good many people, I have discovered that concrete is being used A good deal for a wide variety of oils ranging from 14° to as high as 40° Bé., especially, by some of the western railroads:, If any member has had experience, in storing gasoline in concrete, I should like to learn of it. DORSEY HAGER, Tulsa, Okla.-Mr. M J. Munn, formerly .with the U. S. Geological Survey, acid connected with the Gypsy Oil Co., until a short time ago, has invented a invented a method for the application of concrete to the storage not only of crude oil but of refined products:. The Cosden Oil Co., of Tulsa, is now working on that plan, and, expects to store refined products in concrete tanks. THE CHAIRMAN (I.N. KNAPP, Ardmore Pa.).-I have had considerable experience in building masonry tanks for gas Holders. I do not believe it is possible to build a concrete or masonry tank of any kind. With hydraulic cement, mortar, which will be absolutely water-tight, unless the bottom and inner wall, after completion are waterproofed with some impervious material. The same will be true of oil tanks, the bottom and inner face of which must be made impervious to oil. Masonry tanks are intended to be sunk in the ground. All that the wall of the tank then amounts to is a retaining wall to keep the excavation in shape and to receive an impervious coating. The bottom of, a; tank, when empty, must be protected by a relief valve from any hydraulic: pressure acting from below. At ordinary prices, for sheets, a tank 100 ft. diam by 20 ft. deep can be built of steel much quicker and cheaper than of masonry. Several years, ago I saw very large oil storage tank under construction in California the bottom and sides being concrete. The sides were, sloped at about the single of repose for the material excavated: If you build a steel oil tank, you can get. .men for the work who do nothing else, and you, are likely to get a satisfactory job; but if you wish to build a concrete or masonry tank it is almost: impossible to find men skilled in building absolutely water-tight masonry Work. The general idea is that any laborer can mix up concrete in any old way and make a,

Jan 1, 1918

By Dale I. Hayes

Combined loader and transport, the Gismo is now built for sale in one size, 5 to 6 tons. It will operate in a minimum opening of 7x7 ft and can be built to operate at lower heights. Where space limitations are not a factor it could be designed with much greater carrying capacity-12, 18, or 25 tons-to be powered with a standard heavier tractor. The Gismo is mounted on crawler tracks of the same design as the tracks of the small Allis- Chalmers HD-6B tractor used to power it. With the HD-6B tractor it will negotiate upgrades of 12 pct and downgrades of 20 pct. The next tractor size would make the device feasible for steeper grades or for a machine of larger capacity at moderate grades.

Dec 1, 1956

By W. N. Lacey, D. F. Botkin, B. H. Sage

JOULE-THOMSON coefficients for two natural gases were determined at pressures up to 600 lb. per sq. in. throughout the temperature interval between 70° and 310°F. From these primary data and available information relating to the isobaric heat capacities of the components at infinite volume, the heat capacities of these gases were computed throughout the above-mentioned range of pressures and temperatures. The enthalpies of the gases were computed as a function of state and the results compared with values obtained by several methods of prediction currently available. The results are presented in graphical and tabular form.

Jan 1, 1942

By E. V. Given

Designing a tailing dam is a major step toward fully integrated mill operation. In the case of large concentrators considerable planning is necessary, and the site of the tailing disposal area may very well dictate the location of the concentrator itself. Before a suitable location can be selected several pertinent factors should be investigated: estimated life expectancy of the mine and, if possible, approximate total tonnage; knowledge of daily mill capacity; and the possibility of future mill expansion. In addition, the area should be able to store tailing for many years and, from a cost and maintenance stand- point, gravity flow will probably be desired.

Jan 7, 1959

By Walter Dake

THE mining engineer is being more generally called on to examine and report on properties where the introduction of mechanical loaders is proposed, and as the use of these labor-saving devices presents an entirely different problem from that of hand-loading, an outline of procedure is herewith pre¬sented based on five years of intensive field experience in making such studies. It is impossible to outline an examination which will cover every condition but the most important variables are noted and the re¬port may be amplified or abridged to suit individual mine requirements. There are, of course, exceptional cases in which a single minor variable will determine the final conclusion; the result of mechanical loader application can be, estimated within close limits by considering all variables listed and taking into account the sum of all those found to be applicable to the property under examination. It is necessary that a high degree of accuracy be exercised in the analysis of conditions, and that a relatively narrow margin be figured on all estimates of tonnage outputs and costs. In making an examination for this purpose the data as to company name, business address, name of mine, geographical location, rail or water connections, type of mine (whether shaft, slope, or drift), and the name of seam should, of course, be included, to be followed by the minimum, maximum, and average thickness of seam, a brief description of the charac¬teristics of the coal, the impurities contained, location of regular impurities or partings, together with nota¬tion as to quality, uses, and-markets for the coal. It is also necessary to make cross-sections of the seam so that face preparation may be studied in an effort to eliminate all regularly-occurring impurities at the working place. The possibilities for further cost re¬ductions by the removal and gobbling of partings under¬ground before mechanically ? loading out a face are sufficiently great to warrant careful study and analysis. The classification of the mine from the standpoint of gaseous or non-gaseous operation will determine the general type of electrical equipment needed. A notation regarding the power whether generated at the mine or purchased, together with the amount, voltage, and type of current available is necessary since these matters determine the exact type of elec¬trical equipment to be used. A brief description of the ventilating system, giving type of fan, amount. of air delivered, water gage, and whether force or ex¬haust type, will enable the engineer' to figure venti¬lating requirements per man under mechanical loading practices. The pitch of seam in degrees, the pitch of working faces, and a brief description of rolls or horsebacks should be included, as these affect the efficiency of mechanical loading and, therefore, the economic re¬sults obtainable. -Notations should be made as to the amount of water found in working faces, and whether pumping, sprinkling or rock-dusting methods should be considered. As the character of the floor affects the operation of the machine at the face if a cater¬pillar-tread type, its hardness should be determined, and also whether impurities consisting of floor ma¬terial are likely to be loaded with the coal. The char¬acter of the roof and overlying stratification determine the mining system and width of roof span at work¬ing faces. It therefore directly regulates the amount of tonnage to be loaded by machines without a move from one place to another.

Jan 12, 1927

By Dennis V. D’Andrea, Larry R. Fletcher, Peter G. Chamberlain

The evaluation of potential in situ copper leaching deposits requires a thorough examination of the geologic, mineralogic, hydrologic and physiological characteristics of the ore body. The decision to develop the deposit is made with these data along with leaching properties, estimated copper recovery, and economic analysis. A test blast followed by pilot leaching can a so be used for further evaluation and to reduce uncertainty regarding the deposit's potential. This report describes a number of ground characterization techniques that can be used to evaluate potential deposits. Field methods include geologic mapping, groundwater hydrology, core drilling, geophysical logs, permeability testing, and in-situ stress measurements while laboratory tests include assaying, mineralogy, leaching, rock physical properties, size analysis, and computer simulation.

Jan 1, 1980

The Committee on Papers and Publications has set June 1, 1919, as the closing date for the receipt of manuscripts intended for the Chicago meeting, which is to be held in September, 1919. Manuscripts must be received by the Secretary on or before this date. If they are sent through members of the technical committees they must be sent to those committees long enough in advance to be forwarded and in the hands of the Secretary by the time specified.

Jan 4, 1919

By R. E. Zinkham, R. J. Goodwin

A mathematical study has been made of the amount of support a cement sheath could provide to casing cemented into the earth. Several assumptions were required to make the analysis, but only two of them are limiting: (I) the pipe must be completely surrounded with cement, and (2) any mud filter cake between the cement and formation has the same physical properties as either the cement or formation. The calculations showed that little support would be provided to the pipe before an unsupported cement sheath failed in tension; however, when the cement is confined between the pipe and wellbore and is loaded in compression, the pipe could receive a considerable amount of support. In fact, the theoretical results indicate the lower grades and larger sizes of pipe could have their working pressures doubled when reasonable compressive loads were applied to a surrounding cement sheath. These data are shown in six charts. Other down-hole conditions such as setting the cement under pressure, increased temperature and cement confinement all tend to increase the potential usefulness of the sheath. Because of size limitations, a laboratory program to verify the most important results of this mathematical study would be very difficult. However, small-scale field tests would be practicable. This paper shows that, if a solid cement sheath can be obtained in the field by either primary cementing or by repair after detection of flaws by surveys such as the new cement-bond logs, the use of this approach to reducing pipe costs merits further consideration. INTRODUCTION A modification in casing design practices is proposed which may either reduce the amount and grade of steel required to contain a specified internal pressure or permit the working pressure to be increased for a specified weight and grade of pipe. One of the more important considerations in casing design is its resistance to collapse; however, Bowers' and, more recently, O'Brien and Goins' have shown many casing programs are unnecessarily conservative in this respect, and they have indicated how savings can be made by designing for more realistic down-hole conditions. Earlier, Saye and Richardson howed that pipe costs could be reduced by considering the cement sheath as a part of the casing string when collapse resistance was being calculated. More recently, Rogers4 has raised the question as to whether a cement sheath might be considered in the design for burst resistance of the cemented casing. Calculations have been made for the increased burst resistance a cement sheath would provide for casing in a wellbore, and the results show that a sizable amount of support could be obtained in some instances. These data are presented in addition to a discussion of several other factors that are considered to affect the burst strength of pipe supported by cement. Two types of support are treated: Case I for tensile loading of the unconfined cement sheath, and Case for compressive loading of the confined cement sheath. ANALYTICAL TREATMENT AND RESULTS CASE I—TENSILE STRESSES IN AN UNCONFINED CEMENT SHEATH Conditions like this would most likely occur in a greatly enlarged portion of the hole where the cement was not in immediate contact with either the formation or a thin and hard mud cake. The mathematical analysis for this condition, as shown in the Appendix, rests on the following concepts. Pressure inside a unit length of pipe causes: (1) a tensile or tangential stress to be exerted over the longitudinal cross-sectional areas of the pipe and cement; and (2) an equal amount of strain in both the pipe and cement that is uniformly distributed over the wall thickness of each. This analysis was then used to make several calculations for a cement sheath around 51/2-in. OD pipe. The results are illustrated in Fig. 1, which shows that a tensile stress of 500 psi is imposed on a 5-in. thick sheath when the casing contains a pressure of only 1,450 psi. It also shows that a 10-in. thick sheath would be stressed to 500 psi in tension when the pipe contained a pressure of only 2,350 psi. Alternatively, if the stress analysis is made by means of the Lame thick-wall cylinder theory, the inner fibers of the 10-in. thick sheath will be stressed to 500 psi in tension when the pressure in the pipe is only 990 psi. This, of course, reveals that an unconfined sheath is of little support to the pipe in burst; however, an entirely different result is obtained when the cement is confined between the pipe and formation.

In accordance with the usual custom, manuscripts to be presented at the next meeting of the Institute must be in the hands of the, Secretary before July 1, 1917. Manuscripts to be properly distributed in advance of the meeting must be in the hands of the Secretary before June 1, 1917. At the last meeting of the Institute 45 papers were presented, and 42 of them were actively discussed. This experience makes us believe that advance distribution is the best possible means of getting a good discussion of papers and of securing for them the interest of the members of the profession. It will be impossible, however, to give the papers proper distribution if they bare not received before June 1, 1917.

Jan 4, 1917

By Hugh Tiemann

(San Francisco Meeting, September, 1915) THE desirability of employing the centigrade scale for the measurement of temperatures is becoming more and more recognized in this country, particularly in view of the fact that this scale is used almost exclusively in technical papers and publications-exclusively in those published in French or German. There are, however, a large number of factories and laboratories which still employ the Fahrenheit scale. It therefore frequently becomes necessary to convert one into the other and the accompanying chart (Fig. 1) has been found very convenient for this purpose.

Jan 6, 1915

By Sabert Oglesby, Albert L. Thomas

Until recently, probably the best means of sampling airborne dusts has been the impinger method. Dust-laden air is drawn into a sampling tube, and the particulate matters separated from the air and collected in the liquid in the impinger. A sample of the suspension is prepared on a slide and counted through a projection microscope. This method is simple and reliable, but it does suffer drawbacks. Since the collected particles must be counted visually, results of the dust count are taken. This seriously impedes studying the effectiveness of dust inhibitors, such as water sprays, or making adjustments in equipment. Greatest disadvantage of all, however, is the tedious task of counting particles in the sample. With the growing desirability of taking more samples, the effort involved in making these counts is a real factor in the cost of dust control. Finally, it is generally recognized that impinger dust counts can be related to health hazard only for specific kinds of dust and under similar conditions. This is because the rather complex mechanism of dust damage depends so much on size distribution of the dust. Counts determined by impinger samples cover a limited size range that does not necessarily correlate with retention by the lungs and upper respiratory tract.

Jan 3, 1959