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By P. Barnes

Exact accounts hare been kept of the cost of these chimneys, and it may he a matter of some possible interest. that the plans and details of cost should be laid before the Institute. The statement of cost herewith submitted does not give minute particulars of the weights or quantities of material used, although these are noted upon the company's books.

By R. Steven Maxwell, Ulrich Petersen

Most minerals have experienced a slow hut perceptible decline in their annual primary production growth over the past hundred years. This decline is due to a combination of factors: (1) increased recycling; (2) exhaustion of the more accessible or higher grade ores; (3) partial substitution; (4) the more efficient use of materials; (5) progressive saturation of markets as living standards rise. Therefore, future demand for new mineral resources will probably be lower than anticipated. As the world population stabilizes, this slowdown in production growth will become even more pronounced.

Jan 1, 1979

By Charles Meyer, Reno H. Sales

AT Butte, successive zones of sericitized and argillized quartz monzonite occur around every ore-bearing fracture regardless of its size, attitude, or relative age. The two types of alteration always occupy the same relative positions; sericite adjacent to the ore-bearing vein, clay minerals always between the sericitized rock and fresh quartz monzonite, except where overlap of alteration effects between adjacent fissures has eliminated the lower grade mineralogical products, as is the case in much of Butte's Central zone of pervasive sericitization. As long as active circulation continued in the channel, each zone migrated away from the fissure, that is, it grew at its outer edge and simultaneously receded at its veinward edge because of encroachment by the next innermost zone. The different mineralogical and chemical responses within the wall rocks to the attack by the ore fluid are dependent not on a drastic about-face change of composition of the fluid in the channel relative to its ability to alter the quartz monzonite but on continuously varying conditions of physico-chemical environment within the wall rock outwardly from the vein.

Jan 1, 1947

By S. J. Rothman, A. L. Harkness, L. T. Lloyd

Self-diffusion in Y uranium has been measured using U235 as the tracer isotope. The diffusion coefficient fits an Arrhenius-type equation D = 2.33 x 10 -3 exp (- 28,5000/RT) cm2/sec The values of Do and Q are unusually low and are not consistent with the values expected from theories based on a simple vacancy mechanism of diffusion. CYLINDRICAL samples, 1 cm in diam and 1/2 to 1 cm long, were prepared from high-purity uranium containing 0.0343 pct u235, Table I. The samples were water quenched from 690°C (the a-ß transformation is at 668°C) to remove preferred orientation, and annealed at 450 "C to minimize residual stresses. One end of each cylinder was polished on a 1-µ diamond lap and electropolished in a phosphoric acid solution. After a final cleaning by cathodic sputtering, a 1- to 3-µ thick layer of the tracer isotope, uranium containing 93 pct u235, was sputtered onto the sample.' To prevent contamination during the diffusion anneal, the diffusion couples were placed in a tantalum cup and covered with another piece of uranium, and the whole assembly was sealed off in an evacuated quartz tube. Annealing temperatures were constant within +2.0°C. The samples were heated and cooled slowly between room temperature and the ß-? transformation (774°C) in order to minimize distortion of the sample surface that might arise from aniso-tropic thermal expansion and density changes during phase transformations. After machining off 1/16 in. from the radius to

Jan 1, 1961

By S. K. Tarby, A. E. Rathke

A series of 0.21 pci carbon steel melts was processed under conditions which sinzulated industrial vacuum degassing practices. The results indicated that the efliciency of carbon deoxidation was not significantly increased by vacuunz degassing at chamber pressures below 100 torr. The two common phenomena of vacuu?rz carbon deoxidation, i.e.,an unaccountable carbon loss and nonequilibrium deoxidation, were observed in this study. Oxygen from adsorbed and chenzically combined water of certain refractory structures was probably responsible for the unaccourttable carbon drop. The nonequzlibrium deoxida-tion phenomenon was adequalely correlated by a bubble nucleation )mechanism. Although the major limiting factor in oxygen removal from these melts contained in alumina crucibles could not be eslablished with certainty, there was some evidence that melt-refractory interactions were not the most imp-portant limiting factor. CONSIDERABLE attention has been given to the use of carbon in conjunction with vacuum degassing* as a deoxidation technique. An advantage of utilizing the reaction: for deoxidation purposes is that the reaction product is gaseous and hence can be effectively removed from the melt. The pressure dependency of Eq. [I] is illustrated by the expression for the thermodynamic equilibrium constant, K: where pco is the partial pressure of carbon monoxide, and hc and ho are, respectively, the Henrian activities of carbon and oxygen in molten steel. The thermodynamic aspects of the C-0 reaction in molten Fe-C-0 alloys have been investigated extensively. Theoretical predictions based on Eq. [2] indicate that, at the chamber pressures reached in most vacuum degassing units, carbon is the most effective deoxidizer that can be obtained. ~ornak' has compared industrial values of carbon and oxygen contents with values calculated from theory, and has shown that on a commercial basis vacuum carbon deoxidation has not achieved the degree of success that is predicted from theoretical considerations of the C-0 reaction. The use of industrial units to determine the reason for this deviation is limited by economics and the difficulty in controlling critical process variables. Therefore laboratory-sized experiments in this area should yield valuable information. Investigations on vacuum carbon deoxidation have been made in experiments conducted under vacuum induction melting conditions where pressures in the low micron range, long treatment times, exposure to highly dynamic vacuum conditions, and relatively quiescent bath conditions have been maintained. Inve~ti~ators~~~ utilizing vacuum induction melting for the production of high-purity iron by carbon deoxidation have concluded that, under high vacuum conditions, melt-refractory interactions constantly supply oxygen to the melt. Thus, it has been suggested that refractory dissociation rather than the C-0 reaction establishes the lowest possible oxygen content of a melt. Thomas and Moreau4 and Bennett, Protheroe, and ward5 have studied carbon deoxidation of Fe-C alloys melted in magnesia crucibles under reduced pressures. The results of both studies differed considerably from those predicted by theory, and the limiting factor for lower oxygen contents was attributed to melt-refractory interactions. Because the refractory material used in both investigations was magnesia, no quantitative measure of crucible reaction could be made and the amount of carbon consumed during treatment was utilized as an indirect indication of the extent of crucible reaction. Studies concerned with the determination of the minimum oxygen content attainable in pure iron and Fe-C alloy material vacuum-induction-melted in various crucible materials have also been conducted."' The suitability of a crucible refractory for use under vacuum conditions appears to depend upon the major refractory constituent, the amount and type of impurity oxides, and the composition of the melt. Meadowcroft and Elliott9 have presented a theoretical review of the type and extent of various refractory reactions which should be considered in vacuum refining. ~eadowcroft'~ considered the vacuum degassing process to be dependent upon the "carbon boil" and has proposed that a part of the difference between the experimental and theoretical results for vacuum carbon deoxidation may be explained by the fact that the pco term in Eq. [2] is not the chamber pressure. Instead, the pressure necessary for carbon monoxide

Jan 1, 1970

By Richard E. Chism

The dry methods of assaying mercury-ores and other combinations of mercury all rest upon the volatility of this metal as a beginning. After the separation of the mercury in the form of vapor from the matrix upon which the assay is performed, the mercurial vapors are either condensed upon cold surfaces or received upon a gold plate into which the mercury is absorbed.

Jan 1, 1899

By T. Y. Yan, W. F. Espewheid

The various ion exchange reactions occurring during restoration of formations contaminated with ammonia during in situ uranium leaching are reviewed. Data are presented on the restoration of a previously leached laboratory packed column wing lime saturated brine. Although this restoration fluid selectively and effectively removed the ammonia, 24.5 pore volumes are required to reduce the ammonia concentration from 500-3 mg/L (29- 0.18 gr per gal). The essence of NaCl in the restoration fluid at levels in formation water is beneficial in improving the selectivity of the system for NH4+ removal and reducing Ca + + ion consumption

Jan 1, 1984

By G. F. Comstock

A serious disagreement as to the effect of titanium on the hardenability of steel exists in published references to this subject. Kramer, Hafner and Toleman reported1 that acid-soluble titanium decreased the hardenability, with multiplying factors less than unity according to Grossmann's system for calculating hardenability from the composition. Crafts and Lamont, on the other hand, showed2 how titanium increased the hardenability, with multiplying fdctors up to nearly I.; for about 0.1 per cent titanium, though reducing the hardenability with higher titanium. Their data, however, were obtained almost exclusively from steels containing more than 1.4 per cent manganese, and thus should be considered as applying mainly to manganese steels. Likewise, the results of Kramer, Hafner and Toleman regarding titanium are subject to the limitation that although they eliminated the effect of the insoluble titanium compounds from their calculations, they did not make a similar correc- tion for the carbon that was combined with titanium and therefore occurred in a similarly ineffective form. It is suggested by the literature referred to that titanium may have different effects on hardenability, depending on the mode of its occurrence in the steel. The different effects on strength, ductility, etc., have already been discussed by the author.3 In the present discussion some comparisons, on the basis of hardenability as revealed by the Jominy end-quench test, are given between three titanium and two non-titanium steels heat-treated in the same ways, and between other titanium steels heat-treated in several different ways. Comparison of Plain-carbon, Vanadium and Titanium Steels The five steels used for these experiments were cominercially melted and rolled products received in the form of 1.5-in. rounds from three different mills. Their analyses are given in Table I. Steels 2, 3, and 4 are from the same basic electric heat1 containing 0.009 per cent of phosphorus and the same amount of sulphur. They were made by adding aluminum and low-carbon ferrotitanium to different ingots. No. I is a plain carbon

Jan 1, 1947

By G. F. Comstock

A serious disagreement as to the effect of titanium on the hardenability of steel exists in published references to this subject. Kramer, Hafner and Toleman reported1 that acid-soluble titanium decreased the hardenability, with multiplying factors less than unity according to Grossmann's system for calculating hardenability from the composition. Crafts and Lamont, on the other hand, showed2 how titanium increased the hardenability, with multiplying fdctors up to nearly I.; for about 0.1 per cent titanium, though reducing the hardenability with higher titanium. Their data, however, were obtained almost exclusively from steels containing more than 1.4 per cent manganese, and thus should be considered as applying mainly to manganese steels. Likewise, the results of Kramer, Hafner and Toleman regarding titanium are subject to the limitation that although they eliminated the effect of the insoluble titanium compounds from their calculations, they did not make a similar correc- tion for the carbon that was combined with titanium and therefore occurred in a similarly ineffective form. It is suggested by the literature referred to that titanium may have different effects on hardenability, depending on the mode of its occurrence in the steel. The different effects on strength, ductility, etc., have already been discussed by the author.3 In the present discussion some comparisons, on the basis of hardenability as revealed by the Jominy end-quench test, are given between three titanium and two non-titanium steels heat-treated in the same ways, and between other titanium steels heat-treated in several different ways. Comparison of Plain-carbon, Vanadium and Titanium Steels The five steels used for these experiments were cominercially melted and rolled products received in the form of 1.5-in. rounds from three different mills. Their analyses are given in Table I. Steels 2, 3, and 4 are from the same basic electric heat1 containing 0.009 per cent of phosphorus and the same amount of sulphur. They were made by adding aluminum and low-carbon ferrotitanium to different ingots. No. I is a plain carbon

Jan 1, 1947

By N. A. D. Parlee, E. M. Sacris

OVER 55 years ago, Sieverts and Hagenacker1 and Donnan and shaw2 made determinations of the solubility of oxygen in liquid silver, over a rather short range of temperatures (973° to 1125°C), using quartz bulbs, mainly at 1 atm. From the results of their investigations, Mizikar, Grace, and parlee3 plotted % O vs 1/T and obtained the following straight-line equation for solubility at 1 atm: log % O = 723.7/T - 1.0949 Recent work on the kinetics of the Ag-O2 system394 indicated there might have been some error due to reaction with the direct heated silica bulbs. Thus it became important to redetermine the solubility with the silver contained in a better refractory such as alumina, and by induction heating where the walls of the container were not so strongly heated. It was also desirable to extend the temperature range. A modified Sieverts apparatus of fairly standard type was used except that a special type of reaction tube was employed, Fig. 1. Dried argon with a guaranteed purity of 99.9 pet, and dried medical-grade oxygen with a guaranteed purity of 99.6 pet containing a little nitrogen, were the gases used. The measuring system consisted essentially of a manometer and a water-jacketed 100-cc gas buret with an open-end vertical tube parallel to the buret. This tube has the same diameter as the buret in order to give the same capillary effect on the mercury. A screw leveling device was used with the buret leveling bulb to help provide accurate pressure readings. A 2-mm ID capillary line connected the buret to the reaction chamber, helping to reduce the dead volume, which was determined with argon. The heating medium was a 2.5-kw output induction furnace. The induction coil was made of a 3/16-in. copper tubing with eight turns and an inside diameter of 4 cm. The reaction bulb was made of a quartz tube 18 cm long and 3 cm in inside diameter, Fig. 1. Inside the quartz tube were two alumina crucibles (Mor-ganite Triangle RR, XN10 and XN5) one inside the other. Below these two was an alumina disk. The disk prevented the corners of the outer crucible from expanding against the quartz tube. The solid sample (99.994 + pet Ag), which had been previously cleaned by air oxidation and repeated removal of scum, was placed inside the inner crucible. An alumina disk with a hole at the center covered the two crucibles. In order to decrease the dead volume, an evacuated quartz "filler" tube was placed on top of the crucible cover. The part of the reaction tube above the spherical joint was made up of Pyrex glass with a flat glass top. It was here that a prism was placed to facilitate the use of an optical pyrometer, previously calibrated at the freezing point of silver. This type of reaction bulb and furnace assembly was specially designed for this work, and used in preference to the relatively new water-

Jan 1, 1965

By H. J. O’Donnell, B. C. Parks

IN 1930 the late Dr. Reinhardt Thiessen set up a method of microscopic analysis and type classification of coal that has since been followed as standard practice in the coal-petrography laboratory of the Bureau of Mines. Thiessen's terminology which designated the constituent parts of coal in terms of botanical origin was introduced in 1920.l The technique, however, of preparing a completely representative series of thin sections from a column sample of coal for use in making quantitative determinations of coal components with a microscope was developed about 10 years later by Thiessen and coworkers G. C. Sprunk and H. J. O'Donnell.2 Complete thin-section analyses subsequently have been made of 126 column samples of various ranks and types of American coals. The data and information were assembled from these thin-section studies and published in a large number of reports dealing chiefly with investigations of the coking and hydrogenation properties of certain American coals. In the years following adoption of Thiessen's method, a considerable amount of work was done in collecting column samples of many coals, making routine thin-section analyses of these, interpreting the results, and finding practical application for the information in other fields of coal research. The many reports and papers covering the work in coal petrography, however, offer very little discussion that can be considered as critical appraisal of the technique. Criticism outside the Bureau most often has voiced questioning opinions concerning the accuracy of the method used of measuring coal components microscopically and classifying the coal into arbitrary types on the basis of the quantitative determinations. The principal purpose of this paper is to discuss in some detail and present data showing the results of certain investigative work done in the petrography laboratory on the accuracy of the Bureau's method of microscopic measurement of components in coal thin sections. Data from microscopic analyses on file made by G. C. Sprunk and H. J. O'Donnell were freely used in the investigation, and a table of columnar analyses from an unpublished manuscript by Sprunk is included in this paper for reference. In the course of the experimental work a method was developed for measuring instrumentally with a planimeter the components shown in micrographs of selected thin sections. Measuring coal components with a planimeter furnished useful information for studying the accuracy of microscopically measuring the same components in thin sections. PETROGRAPHIC COMPONENTS AND TYPE CLASSIFICATION OF COAL Thiessen considered coal to be composed of two visibly different major components present in various types of coal in greatly varying proportions. He named

Jan 1, 1948

By Fred D. Fox

INTRODUCTION Approximately two years have elapsed since the first summary of the Grizzly Gulch Tailings Disposal Project was presented (1). Since that time, various physical modifications and additions to the existing treatment system have transpired. Further, Homestake and the entire mining industry have been impacted severely by additional modifications and additions concerning regulatory reform aimed at total disciplinary permitting and hazardous waste management. The following paper summarizes the past accomplishments relating to the Grizzly Gulch Tailings Disposal Project, correlating these accomplishments with future plans that are being developed to comply with regulations and to continue Homestake's commitment to environmental protection. The famous Homestake Gold Mine, located in Lead, South Dakota, has been operating in the Black Hills region for over a century, approximately 12 years before the south half of Dakota Territory was admitted to the Union as the State of South Dakota (2). During the 104 years of operational development, Homestake's Gold Mine, as well as the entire mining industry, have been influenced by numerous governmental regulations dating back to the Refuse Act of 1899 which regulated the deposit of debris from mines and stamp works. The enactment of the National Environmental Policy Act of 1969 may be thought of as the beginning of a long line of unplanned steps to deal with the many concerns of matters pertaining to the environment. Environmental awareness continued into the 1970’s, in which the Clean Air Act, Federal Water Pollution Control Act, Safe Drinking Water Act, Toxic Substances Control Act, and the Resource Conservation and Recovery Act (RCRA), to name a few, surfaced.

Jan 1, 1983

By William McCullouch

The method of determining moisture percentages in coal has been defined as purely empirical. The procedure, as defined, has been published in the U.S. Bureau of Lanes technical papers and approved by the American Society of Testing Materials but deviations from this established procedure are common in most commercial and private laboratories. It is not within the scope of this paper to discuss the deviations in common practice but rather to give a detailed account of the method in use in the laboratories of the United Electric Coal Companies. In general, moisture values are presented as surface moisture and, for lack of a better term, inherent moisture. The formula for adding them together to give total moisture is common knowledge. In practice, on high-moisture bituminous coal, it has been found that the line of demarcation between surface and inherent moisture is very indefinite, the inherent moisture being so loosely held that it is released far beyond its natural limits when the prescribed method of the A.S.T.M. for determination of surface moisture is followed. This is shown in Table 1 for two typical washed coals from Illinois.

Jan 1, 1938

By Emery R. Hayhurst

SILICOSIS has been described in a report of the American Public Health Association as a disease due to breathing air containing silica, characterized anatomically by generalized fibrotic changes and the development of miliary nodulations in both lungs, and clinically by shortness of breath, decreased chest expansion, lessened capacity for work, absence of fever, increased susceptibility to tuberculosis (some or all of which symptoms may be present), and by characteristic X-ray findings. ... The disease is divided arbitrarily into first, second, and third stages for convenience of description and possible compensation purposes. At least two distinct types of silicosis are recognized, acute and chronic. The acute form was reported as early as 1713, when a British patent for grinding flint by wet methods was granted because the dry powdered material "proved very destructive to mankind, so much that any person, ever so healthful, working in that business cannot possibly survive over two years."

Jan 1, 1936

By Gregory J. Comstock

THERE is a growing interest in the possibilities presented by the manipulation of metal powders, which justifies an attempt to summarize their character and potential value. A summary of this kind presents an opportunity for making a classification of metal powder products into several general types. Our present knowledge of the finer and more abstract aspects of many of the principles involved in metal powder technique is extremely limited. Any conclusions as to the ultimate value of the process will, therefore, for the present at least, be of doubtful value unless they are substantiated by its products. The number of such products is increasing. A study of their diverse and unusual characteristics; an examination of the methods by which they are made, and a consideration of the reactions that take place during their fabrication, in so far as we can define them, should afford as good an evaluation of this interesting development as it is possible to make at this time. A critical study of this kind results in a formidable list of special attributes, which apparently ate characteristic of applied powder metallurgy. A comparison of these special effects with the end products and well defined limitations of the melting and casting process indicate that often they may very well be considered as being special advantages. They are subject, of course, to certain not as yet so well defined limitations of their own. Based on current products only, a necessarily condensed summary of the more striking special attributes of the metal powder process follows. MANIPULATION OF HIGHLY REFRACTORY METALS The powder process presents a means of manipulating highly refractory metals, which cannot be cast and formed in the usual melting and casting process. Tungsten, molybdenum and tantalum are the classic examples of the adequacy of the metal powder process for meeting unusual conditions of this character. The development and application of these metals by means of it, and their importance in the electrical

Jan 1, 1938

Sailing westward from the Society Islands in the fall of 1774, England's noted explorer Captain James Cook discovered New Caledonia-that long, linear island that has played such an important and varied role in the history of nickel. Upon his return to England the following year, Cook's announcement of this uncharted island generated governmental interest, but its distance from the Island Empire, the troubles in the colonies, and the difficulties with France combined to keep English interest indirect and in the background of the then-current events.

Jan 10, 1968

By James S. Baker

LARGER than continental United States but with only about one third the population, Brazil is a land of enormous potential wealth, waiting to be developed. During a recent visit to that country I saw Brazil at war and learned about some of the recent mineral developments. Many engineers and geologists have been sent to Brazil by various U. S. Government agencies to assist the Brazilian producers and co-operate with the Brazilian Government in producing needed war minerals. The Foreign Economic Administration staff of engineers has been active and through their assistance to the Brazilian producers, steadily increasing quantities of strategic minerals were provided to aid the United Nations' war effort. Mineral wealth has been found in almost every state of Brazil. Many mineral deposits have been discovered during the war period. Examples are: barite near Bahia; the tungsten and molybdenum deposits in Rio Grande do Norte; and corundum, beryl, and tungsten ores in Ceara.

Jan 1, 1945

By Strathmore R. B. Cooke, Iwao Iwasaki, C. S. Chang

PYRRHOTITE has long been considered a gangue mineral to be eliminated as tailing in the treatment of various sulphide ores. However, in recent years the world-wide lack of sulphur resources has called attention to this mineral as a potential source of both sulphur and iron. Its importance as an economic mineral, however, has not been particularly emphasized. For this reason very little is known about its response to flotation, except that it can be depressed easily in alkaline circuit, by long aeration,1,2 addition of oxidizing agents3 or by starch.4 The object of this work was to study the floatability of pyrrhotite. This includes the effect of oxidation by aeration, of copper activation, and of change in pH.

Jan 2, 1954

By G. M. Ritcey

Continuous contacting equipment for solvent extraction can be divided into two major areas, according to whether their mode of operation is stagewise or differential (Figure 1). Mixer settlers and the recent Kenics and Sulzer mixers typify the stagewise contactors. In these counter- current contactors, the aqueous and the organic phase are mixed and then separated in a large settling area before the next stage of mixing. Countercurrent differential contact- ors, such as centrifuges and various types of columns, are more compact in that they require less ground area than mixer settlers. [ ] Contactors, in addition to being either stagewise or differential, can be further subdivided into non-agitated and agitated depending on the method used for mixing the phases and producing the countercurrent flow. The simplest contactors such as spray, packed, or perforated plate columns achieve both the mixing and countercurrent flow by means of the gravity difference between the two phases. In agitated contactors such as the Scheibel, Reciprocating Plate, and Sieve-Plate Pulse, mechanical agitation is introduced but gravity differences still produce countercurrent flow. To conserve plant space, and for large throughput with short contact time, centrifugal contactors are used where possible. The reader can refer to reviews on the subject (1-11).

Jan 1, 1978