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By Radoslav Despotovic

The developed radiometric method of particle system analysis has been applied to investigate the bulk properties of particles precipitated from solutions. The nature and principles of the method applied are described briefly, and some possible models in the field of fine colloid particles precipitation discussed. Changes in radionuclide distribution were followed during the solid phase formation and the data were used to calculate changes in bulk composition of colloid precipitates. The radiometric data show interesting phenomena closely connected with the characteristic of bulk particles. The measured radiometric data are highly reproducible, the applied methods have proved to be sensitive, and the developed techniques have been tested by various standard procedures.

Jan 1, 1980

By Corale Brierley

The effect of hydrogen peroxide (H202) on growth and respiration of Thiobacillus thiooxidans and Thiobacillus ferrooxidans, organisms involved in acid leaching of copper sulfide minerals and uarnium oxides, was examined. Oxygen uptake and growth by T. thiooxidans were totally inhibited after contact with 0.82 mM H202. Complete inhibition of oxygen uptake by T. ferrooxidans occurred at 8.75 mM H202, and growth was inhibited after 6 hr exposure to 2.06 mM H202. Higher concentration of H202 can be used without detriment to thiobacilli if it is dissipated prior to reaching the oxidation pond or dump surface.

Jan 1, 1980

By Andrew Torok, Thomas D. Thompson

Research efforts have not developed techniques for the complete desulfurization of coal that is needed to reduce air pollution caused by burning coal and to reduce the sulfur in metallurgical coke. Sulfur in coal occurs in three forms and of these, the pyritic sulfur occurs as discrete mineral particles and, at least theoretically, should be subject to physical rejection. Pyrite occurring in hard rock mining is concentrated by froth flotation; therefore, the possibility of removal of pyrite from coal by flotation does exist. With this possibility in mind, the flotation and adsorption characteristics of ore and coal-pyrite were compared while using potassium ethyl xanthate as the collector.

Jan 1, 1973

By Alan K. Burton

Having estimated fleet size and productivity, the next and final step in this analysis is to introduce cost. Total cost of the system is a combination of capital, operating, and any other external costs that may be incurred. The last item, external costs, can be particularly important when comparing one size or type of truck fleet with another. Once costs are calculated, it is possible to compare systems on a total cost, cost per hour, cost per ton, or any other basis that is required. Methods used vary from simple owning and operating costs to sophisticated discounted cash flow analyses involving optional fleet replacements over the project life.

Jan 1, 1976

By Roshan B. Bhappu, Raul A. Deju

The mineral olivine has been the subject of continued research by various authors. Paik1 conducted infrared and flotation studies of the adsorption of sodium alkyl benzene sulfonates on olivine. These studies are of interest from two points of view. First, in the metallurgical field it is of interest to understand the mechanism of silicate flotation using sulfonate collectors and second, hydrologists are interested in studying the chemical reactions that take place when water plus sulfonates encounter a porous silicate medium. On the basis of his study, Paik was able to postulate a possible mechanism for the attachment of RSO3- (sulfonate radical) to the olivine surface.

Jan 1, 1973

By F. M. Lyon, F. J. Chernosky

Research efforts have not developed techniques for the complete desulfurization of coal that is needed to reduce air pollution caused by burning coal and to reduce the sulfur in metallurgical coke. Sulfur in coal occurs in three forms and of these, the pyritic sulfur occurs as discrete mineral particles and, at least theoretically, should be subject to physical rejection. Pyrite occurring in hard rock mining is concentrated by froth flotation; therefore, the possibility of removal of pyrite from coal by flotation does exist. With this possibility in mind, the flotation and adsorption characteristics of ore and coal-pyrite were compared while using potassium ethyl xanthate as the collector.

Jan 1, 1973

By R. W. Marrs

Kimberlite contains a unique assemblage of minerals and exhibits a characteristic pattern of spectral reflectance in the visible and near-infrared wavelength region. This spectral pattern is readily discerned in well exposed kimberlite outcrops, but becomes increasingly difficult to identify when outcrops are partially covered by vegetation or soils derived from nonkimberlitic materials. Detection of poorly exposed kimberlite diatremes is possible using multispectral imaging techniques where spectral bands are chosen to optimize contrast between the kimberlitic soils, nonkimberlitic soils, and vegetation. Careful processing of the multispectral data is essential to separate the spectral signature of kimberlite from the signatures of other components of the scene.

Jan 1, 1986

By John E. Caffrey

The Federal Coal Mine Health and Safety Act of 1969, Title III, Interim Mandatory Safety Standards for Underground Coal Mines, is devoted to protection of workmen from hazards of electricity, roof, ribs, fire, and explosions. The Rules and Regulations, promulgated through the Federal Register, provide the criteria by which the law would be administered. Certain aspects of the law involve features that could be summarized under entrapment. These are sections 303 (y)(1), (y)(2) and 317 (f) (4). This paper is intended through the use of the figures to describe how these features of the law affect mine ventilation design, what are the problems, and possible solutions to them.

Jan 1, 1974

By A. W. McReynolds

E. OROWAN*—I observed the phenomenon of jerky yielding many years ago with zinc25 and cadmium single crystals. A significant point was that the jerks occurred not only when the stress was raised but also (sometimes, after a pause of many minutes during which no trace of creep was observable) at constant stress. The phenomenon may be closely linked with the inertia of the testing machine and of the specimen, although the inertia alone cannot account for it. If, during the test, the resistance of the material to plastic deformation suddenly diminishes while the applied force remains constant, a sudden deformation follows until the yield stress has risen, by strain hardening, to the level of the applied stress (= the value of the previous "upper yield point."). When this is reached, the rate of deformation has attained a maximum value because, up to this moment, the applied force was higher than the plastic resistance of the specimen, and the difference was used for accelerating the moving parts of machine and specimen. The kinetic energy accumulated is now transformed into plastic work by further deformation; that is. the deformation overshoots the point at which the plastic resistance equals the applied static force. When the kinetic energy has been used up, therefore, we are left with a specimen the yield stress of which is higher than the applied stress, and no further deformation can occur (apart from a little creep) until either the applied stress has been raised to the new yield stress level, or the yield stress has fallen by thermal recovery to the level of the applied stress. While this occurs, a new upper yield point can develop, for example, by precipitation.26

Jan 1, 1950

By P. A. Toynbee, D. G. Wilson

The combustion performance of sub-bituminous slack coal is greatly improved by the removal of the smaller size fractions. Screening processes are not well suited to the size separation, at 1/8 in. or 1/16 in., with coals which are normally wet, and the use of an alternative size-separation device has been investigated. It is felt that this classifier might be applied equally well to other minerals in cases such as this, where precise size limits are not essential. Coal is dropped as a curtain onto a curved metal plate, shaped rather like a ski-jump. The smaller particles, slowed up in their free fall to the plate and also by contact with the metal, leave the plate with a lower horizontal velocity; they can be separated from the larger particles by virtue of their shorter trajectory. The principle of the classifier is obvious from the diagram (see Fig. 1) which shows also the positions, relative to the curved plate, of the point of coal feed and of the dividing plate which separates the streams of coal particles. The horizontal distance between the curved plate and the dividing plate is varied in the tests. It is designated in the general case, by X. Tests were carried out using slack coal with a free moisture content higher than that expected in any commercial operation. The results given in Table I. show the percentage recovery of upgraded product, and the cumulative screen analysis of both the upgraded and reject material, for three different positions of the dividing plate. The results show, for example, that the original coal can be upgraded, with a recovery of 80%, to reduce the minus 1/8 in. frac-

Jan 1, 1965

George W. Maynard, New York, N. Y.:—It is well known that there are many magnetite-mines of which the ore is too low-grade for direct use in the blast-furnace. For carrying out the sintering process, the preliminary step, in the case of magnetites, is the separation of the ore from the gangue by magnetic concentration. The resulting fine-grain product is very objectionable in the blast-furnace, and when used must be a very small percentage of the charge. The sintering process has saved the situation by furnishing a product which is absolutely ideal on account of its cellular structure. (In reply to questions by W. J. Tudor, and Joseph W. Richards, the following additional information was given by Dr. Maynard.) The percentage of iron in the product is determined entirely by the degree of concentration of the raw material and is practically not increased by the sintering operation. The magnetic concentrates at Port Henry and at the Benson and one or two other mines contain from 65 to 67 per cent. of metallic iron. The cost of sintering is from 39 to 41 cents per ton of product, including superintendence, depreciation, and repairs. The itemized figures are about as follows : Mixing (including labor), 24; power, 9; ignition, 5; repairs, 3; total, 41 cents. Prof. J. W. Richards, South Bethlehem, Pa.:—From a metallurgical standpoint I question the accuracy of the statement on p. 374: " C.—An increased reducibility of the iron so treated. (This has been conservatively estimated as 5 per cent. better than the best available ore.)" It seems to me that when a material is' sintered in this way, the constituents present, as lime, silica, and alumina, have a chance to form a compound with the iron oxide; that such a compound, if formed before the material goes into the blast-

Jan 1, 1913

By Edward F. Divers

Face ventilation is generally the most critical area in the coal mine ventilation system. Various studies have repeatedly shown that good ventilation is by far the most effective and least costly method of controlling dust and gas problems created during face operations. The Bureau of Mines has recently developed and assisted in the development of several new concepts in face ventilation systems, and in methods to accurately evaluate these systems underground. A new type of scrubber and ventilation system design built into the auger support frame of a continu- ous miner was developed. The objective was to improve face ventilation and reduce respirable dust concentrations. With this arrangement, one scrubber is mounted into each side of the boom. Laboratory and underground tests of various scrubber discharge arrangements showed good to excellent dust and methane control. Combined face ventilation systems, using both blowing and exhaust curtain, potentially offer dust and gas control and deeper cutting. Bureau tests at a mine using a combined face ventilation system and remote- control-operated continuous miners showed excellent dust and methane control. The advancement of line curtain systems beyond permanent supports without exposing workmen to roof fall hazards can be accomplished only with specially designed extendable devices. Numerous concepts for line curtain extension have been developed and tested. For the past several years, the Bureau has been testing various types of extensible face ventilation systems. These extensible systems can generally be classified as floor-, roof-, machine-, and rib-mounted systems. In the past 6 years, approximately 40 systems have been evaluated for feasibility. From these, several have been selected as practical or innovative and are presented herein. A technique developed by the Bureau to accurately and safely evaluate the effectiveness of face ventilation is also presented.

Jan 1, 1982

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 David Baker

Our large modern blast-furnaces, equipped with ore-bins, larries and mechanical means for putting stock into storage, withdrawing it therefrom, and charging it at the tunnel-head, are indeed wonderful in capacity; yet, it is admitted that, with some notable exceptions, they have disappointed us in economy—that is, in the items of low fuel-consumption, uniformity of product, freedom from slips, and reduced cost of repairs and relining. The manager who estimated the cost of pig-iron to be made in a modern plant, by taking the costs of the hand-filled furnace and deducting the amount to be saved by the mechanical appliances, has been surprised, in many cases, to find that unfavorable results in these items of economy have greatly reduced his expected gains. Is there any reason why the fuel-consumption should be greater for a modern furnace than for an older stack using the same mixture ? Certainly the equipment is much more complete, and the trouble, therefore, must lie in the management or in the character of that equipment. Everybody knows that intelligent and vigilant management is a prime requisite: that any neglect of a detail, though it may not be felt that day or week, will surely sooner or later make its appearance as an increased item of cost. But to hold the furnace-maaager responsible for the relatively poor work of the modern blast-furnace would be, I am convinced, a great injustice. For its management has received much more study and care than was given to the older types. Many furnace-managers have lost their health through worrying over this problem, and some hare lost their positions, being held responsible for results made inevitable, as I believe, by the equipment provided for them.

Jan 1, 1905

By Charles Barrett

PLASTIC flow in metal crystals and the changes in orientation resulting from it are generally understood to take place by the following funda-mental mechanisms: (1) slip on crystallographic planes, (2) homogeneous crystal rotation resulting from the slip, (3) bending of the lattice between the planes of slip, and, under certain circumstances, (4) twinning. This paper and a preceding one on iron subjected to uniaxial compression1 concern two additional processes that must now be added to this list: (5) the formation of deformation bands, and (6) the bending and rotation of these bands. The present investigation yields a new understanding and definiteness to the common terms so loosely used when speaking of cold-worked metals -"grain fragmentation," "elongated grains," and "deformation twins," "deformation bands," "etch bands," or "X-bands." Bands have been noted on the polished and etched surfaces of cold-worked metals by vari-ous investigators for more than 25 years, ? yet their nature and their significance have been so little understood that they are not treated in the most comprehensive modern texts on the deformation of crystals. The experiments in this series show that they are one of the fundamental processes in the deformation of metals, of importance in the development of preferred orientations, in work-hardening (since they have the effect of reducing the effective grain size and interfering with slip), and in the recrystallization process. The present experiments were performed on the same stock of mate-rial that was used in the earlier compression experiments1-hydrogen-purified mild steel in which the carbon content had been reduced to the limit detectable under the microscope and in which single crystals could be grown by a strain-anneal treatment.2

Jan 1, 1939

By A. R. Kaufman, P. Gordon, C. H. Schramm

AS a part of the general program on alloys of uranium carried out at the Massachusetts Institute of Technology under contract W-7405-eng-175 for the Manhattan Project during the recent war, it was considered desirable to investigate the boundary binary phase diagrams of the ternary alloy system uranium-tungsten-tantalum. Previous work on these alloys was practically nonexistent. A brief statement to the effect that tantalum and tungsten form a continuous series of solid solutions was found in a general paper on tantalum by W. V. Bolton1 but no information was available on the uranium-tungsten and uranium-tantalum systems. The research to be described in this paper has served to delineate the main features of the uranium-tungsten, uranium-tantalum phase diagrams and to check Bolton's work on the tungsten-tantalum diagram. Experimental Details Metals: The tungsten and tantalum used for preparing the alloys were 99.96 and 99.65 pct pure, respectively. The chief impurities in the metals were about 0.02 pct molybdenum in the tungsten, and 0.2 pct columbium, 0.05 pct tungsten, 0.02 pct barium and 0.01 pct silicon in the tantalum. The uranium used was 99.9 pct pure, with the main contaminants being iron and carbon. (An appreciable amount of magnesium was present in the uranium as received, but this distilled off during melting and so is not reported as an impurity.) The composition of specimens indicated in the subsequent figures and tables of this paper are the results of chemical analyses on the cast alloys except for the tantalum-tungsten alloys. For the latter, chemical analysis was not very reliable as a result of the difficulty of separating tungsten and tantalum chemically. Consequently, the nominal

Jan 1, 1951

By T. L. Joseph

Charcoal was the predominant blast-furnace fuel until 1838, when it was found, by the operation of a 2-ton experimental furnace, that anthracite could also be used. This information was a stimulus to the iron industry, particularly in eastern Pennsylvania where anthracite was available at low cost. The production of anthracite pig iron increased steadily and, in 1855, its tonnage exceeded that of charcoal iron. Of the 680 furnaces in operation in 1874, the 226 using anthracite produced nearly one-half the total tonnage. In 1869, the production of coke furnaces exceeded that of charcoal furnaces and, in 1875, coke surpassed anthracite as a metallurgical fuel. In 1907, the output of anthracite pig dropped well below a million tons and its present significance is largely historical. In recent years, the production of coke has gone hand in hand with the production of pig iron and it has gradually attained the position it now occupies as a universal blast-furnace fuel. Charcoal, however, has great merit as a blast-furnace fuel chief1y because of its freedom from ash and sulfur. The harmful effect of the latter and the necessity of keeping the percentage of this element in pig iron at a minimum are well recognized. Other contaminating elements can be reduced to specified limits in the steel-making process, but the control of sulfur belongs essentially to the blast furnace. The purpose of this paper is to point out the distribution of this impurity in blast-furnace materials and to indicate how its presence alters the composition, quantity, and free-running or critical temperature of the slag, and the relation between these factors, fuel economy, and the cost of iron. Sulfur Distribution in MateRials Table 1 shows the distribution of sulfur in charcoal practice. Similar figures taken from coke practice are given in Table 2. These data were

Jan 1, 1925

By D. W. Brunton

The maps of our large mines are usually prepared with the greatest care; and it is somewhat singular that, in compari~on with the great amount of time and money spent in surveying and platting, 80 little actual use is made of them. Almost the only purpose for which a completed survey-map is afterwards consulted, is the determination of the relative position of the different workings to each other, and to the boundary-lines of the property. After the completion of such a map, it should be made the beginning of another, and in most cases a far more important undertaking, namely, its utilization as a starting-point for a complete inventory of the company's underground possessions. The ordinary mine-survey map, being nothing but a record of what has been done, is, in one sense, only ancient history. To increase its value, such additions should be made as will render it a complete statement of the amount and value of ore in sight at any particular time, and a guide for future development. Comparatively little extra labor is involved in this undertaking, since the larger and most expensive part of the work has already been completed when the mine has been surveyed and mapped. The necessary additions consist in working out and platting on the maps, the geology of the mine as exposed in the workings, in such a manner that the geological survey may be of daily use in the development and operation of the mine. The first step towards the production of a geological map consists in tracing individual level-sheets from the general or composite map. The area to be included, outside of the property in question, will depend very much on local conditions; but, for geological, legal and commercial reasons, it should be extended as far as reasonably practicable. The scale to be

Jan 1, 1906

By C. H. Mathewson

(New York Meeting, February, 1916) DURING the past year considerable work dealing with the mechanical properties and microstructure following the anneal under uniform conditions of certain types of commercial rolled brass has been done in this laboratory. Since these experiments were conducted with the active cooperation of the Bridgeport Brass Co., involving free use of its product, and have thus furnished information which is characteristic of some of its special mixtures, full publication of the numerical relationships and comparative results encountered does not seem justifiable. Some of the more general features of this work are, however, available and it is our present purpose to use the material in question, along with some results of special tests, in discussing the characteristics of recrystallization as related to the degree of hardening by strain and the ordinary annealing variables. We desire to make acknowledgment of the many courtesies extended by Mr. Charles Ferry, Metallurgist of the Bridgeport Brass Co., and the value of his cooperation, which has greatly stimulated the study of brass in this laboratory. A clear and systematic presentation of the principal relations between temperature and time of anneal, the changing physical properties and microstructure and the degree of previous reduction by cold-rolling, was first made, in the case of rolled brass and copper, by the French engineer, C. Grard,1 in 1909, although much fragmentary information of this general character had appeared earlier and the main facts involved were undoubtedly known to many brass specialists through their own private research. From this work, it appears that in the cartridge mixture (67 per cent. copper, 33 per cent. zinc) the properties imparted by cold-working within the limits, 13 to 75 per cent. reduction of area by rolling

Jan 1, 1916

By A. I. Blank, S. E. Maddigan

Many experimental and theoretical investigations have been made on the processes involved in annealing and recrystallization of metals. Most of these, however, have treated the time element as constant and heat-treatments used have been for relatively short times. Aside from the early work by Carpenter and Elam,' the few that have investigated the effect of time on the processes have usually done so for fairly short time periods. During recent years the growing interest in long-time creep properties of metals and alloys under stress has made increasingly important a better knowledge of the recrystallization during prolonged heating. The recrystallization temperature of 70-30 brass given by Clark and White" in 1932 was somewhat above 400°F. (204°C.) but under 500" (260°C.), whereas in our laboratory recrystallization has been observed in creep specimens at 204°C., the lowest temperature of Clark and White's range. Since the creep properties are quite different above and below the recrystallization temperature, erroneous conclusions can readily be drawn by the application of short-time recrystallization data to creep problems. It was thus considered of both practical and theoretical value to make long-time annealing studies near the minimum recrystallization temperature. In this way useful additions could be made to data on recrystallization temperatures and, since the reactions in this range are relatively slow, additional insight could be obtained into the factors involved in annealing. Several comprehensive reviews of recrystallization processes have been written,3-6 therefore only a brief review of the generally accepted facts will be given here. Though the effects of heat-treatment usually are expressed as related to observations with varying temperatures, it is logical to assume that the same order of occurrence will exist with time as a variable. Thus, we may postulate that with increasing time we mill observe the following

Jan 1, 1940