Search Documents

Your outgoing President, following the worthy example of distinguished predecessors, submits a reckoning of his stewardship. He renders this fully realizing that without the hearty cooperation of Directors and Secretary, which he here recognizes most cordially, no President, who at best is but a passing force, can achieve markworthy results. The details as to your membership, finances, intellectual output, and,-other activities, have been submitted in the report of the Secretary.* It is enough to emphasize that during the year just expired, your organization has held two of its most successful meetings-one the largest in its history-has produced the largest number of papers, eliciting most interested discussions, has enjoyed its greatest income; and has received more than one thousand new members-passing the best previous record by more than one hundred, and exceeding the average increment of the, past five years by one third. It closes the year with 6528 members, the largest enrollment in its history. All of this might be true and yet the intellectual and social spirit, the loyalty of membership, the real life of the organization, might remain stagnant. As to these, it is for others than your speaker to testify. No comparison is feared.

Jan 3, 1918

By Samuel S. Wyer

The magnitude and economic importance of the problem of correctly valuing natural-gas leaseholds become evident when me consider that: (a) Natural gas is handled in 55 per cent. of the gas distributing plants in the United States. (b) Present known natural-gas acreage forms 47 per cent. of the total known mineral-land acreage in the United States. (c) Five acres of land are now required to protect and maintain continuous service to each of the 2,000,000 domestic natural-gas consumers in the United States. (d) The cost of acquiring and maintaining this acreage of an expendible resource represents a substantial part of the cost of the natural-gas service to the consumer. (e) "The right of a citizen by means of his ownership of or his mining leases on land to draw gas from beneath its surface is property and sometimes valuable property."' A large number of other court decisions have established the basic legal principle that the right to drill for gas within a given area constitutes an interest in the land itself, and is necessarily an exclusive property right. Definition of Vested Interests or Rights "Vested interests are economic interests which are legally recognized to be such that they cannot be impaired by public action, directly or indirectly, without indemnification. Vested interests are largely property interests. The recognition of an interest as a vested interest gives it some of the attributes of property, and by American courts it would be comprised in their very inclusive concept of property. Otherwise than through property, vested interests generally arise through contract."

Jan 1, 1917

The Mount Morgan eopper-gold orebody is contained within a series of Mid-Devonian volcanics which occurs as a roof pendant within Permian granite. The ore minerals comprise pyrite, chalcopyrite, and local aggregations of magnetite and pyrrhotite. Silver-rich gold (electrum) is disseminated through the ore usually in ultrafine to sub-microscopic dimensions. Accessory minerals include marcasite, digenite, chalcocite, covellite, sphalerite, bismuthinite, molybdenite, calaverite, petzite, and cassiterite.Very minor accessories include cubanite, tetrahedrite, galena, arsenopyrite, hematiIe, goethite, and rutile. The gangue minerals are quartz, predominantly, with minor amounts of chlorite and sericite.Study of microtextures of a representative suite of specimens from Mount Morgan does not reveal any criteria indicative of metasomatic replacement but does show, in the case of pyrite, evidence strongly suggestive of annealing recrystallization. Other textures in pyrite indicate porphyroblastic growth of the iron sulphide.It is inferred that the Mount Morgan orebody is genetically related to the volcanic rocks and was later contact metamorphosed by the intrusive granite or by the series of intermediate to basic dykes that transect inmine area. On this basis the Mount Morgan orebody would be a contact metamorphosed volcanic hydrothermal deposit emplaced, according to recent studies, along a pipe-like zone of brecciation.

Jan 1, 1967

By Keith C. Hendrick

"Metal prices are frequently the most critical and least predictable element in determining the profitability of mining operations. Short -term fluctuations can be offset in varying degrees by hedging or other market actions. Such solutions are not practical for the longer term, The paper investigates the nature and extent of metal price risks and evaluates methods to reduce them.IntroductionIt is management's responsibility to improve the odds by managing the-risks by identifying them clearly, assessing them accurately, minimizing them where possible-and, then, timing decision s success fully.In determining the profitability of current operations, preparing forward plan s or developing feasibility studies for new projects or expansions, pr ices are usually the most critical input. Being market determined rather than cost based, they can also be the most unpredictable As a result, commodity prices are frequently the greatest of all risk factors.Nature of Commodity PricesThe cyclical nature of commodity prices is well known. They are stable only when supply is in balance with demand and forecast to remain that way. An imbalance on either side of the equation can lead to a price reaction completely out of proportion to the actual or perceived surplus or shortage.This exaggeration arises through the cumulative effect of market forces. When the market senses an uptrend, consumers buy for the expected increase in activity. They also seek additional quantities for inventory before price s rise. Merchants defer spot sales anticipating higher price s, speculators go along for the same reason, and producers raise prices in response to demand. Events tend to confirm the expectation of each party and strengthen their reaction causing prices to move higher."

Jan 1, 1983

By Patrick M. James

Many in mining believe that the industry is slipping behind in public image, in public mineral education and, particularly, in mining's basic right to do business. It is critical to turn things around - to change the rules of the game soon - before mining loses any chance of recovery. In the industry's experience, there is a technique of project development and operation that can help gain ground on public opinion. Only recently has this technique had a name, and that is sustainable development. What is sustainable development? Sustainable development is broadly accepted and supported by the international business community. And significant thought and work has been devoted to the subject. Research into the topic was initially confusing because the definitions of sustainable development are written in terms the writer, and his or her constituency understands. To some, it refers to environmental protection. To others, it is about social responsibility. And to the developer, it is about economic benefit. Slowly a theme emerged from the research that seemed to be part of all the definitions. That theme has three parts. First, the development, whatever or wherever it is, must contribute economic value to the developer and the stakeholders of the development. Stakeholders in this context include employees, neighbors, residents of the surrounding area, citizens of the country, suppliers and all others affected by the development. Next, sustainable development must contribute environmental value. This means that at a very minimum it must be neutral and not cause irreparable damage. And last, and what is new for miners and most other businessmen, it must contribute real social value to the stakeholders. How to use the concept? With that three-part theme as a working definition, the mining industry must find ways to use that “the challenge is for an individual company to translate what sustainable development means for them. There is no one model..." Donald W. Gentry is president and chief executive officer of Polymet Mining and former professor emeritus of mining engineering at Colorado School of Mines. He added: "While simple to state, the concept is anything but simple to implement. Present trends indicate ... one wins the sustainable development argument by staking out the high ground early..." In other words, start using sustainable development principles at the beginning of the project. New ways of doing business The mining industry's challenge is to implement sus¬tainable development universally around the world. Paternalism as a way of doing business is dead and a new model of doing business is emerging. All types of businesses are learning to deal with the stakeholders of new developments. Mining cannot be an exception to these trends. To understand how the international mining business came to sustainable development, it is useful to look back a few years. For many North American mining engineers, there were few opportunities for foreign assignments from the 1960s to the 1980s. American companies had been asked to leave many of the Latin American countries. Africa was going through a continent-wide upheaval. The Soviet Union and China had Eastern Eu-

Jan 1, 2000

By J. P. Messervey

THE story of the efforts made by the Department of Mines of Nova Scotia in the search for and investigation of mineral resources for the Canadian war effort began in the spring of 1937. During the past five years, however, heavy enlistments in the Active Service Forces by employees of the mining industry of the Province caused a recession in the production of coal, salt, and other essential minerals required to keep industry rolling on a wartime basis. A marked increase was shown during the period in prospecting for 'strategic' minerals, not only by individuals but also by some of the foremost mining companies. The Provincial Government offered encouragement in this field of endeavour by the enactment of legislation whereby the prospector was enabled to secure the maximum area of ground in a prospecting license at a minimum of cost. The labour requirements on the ground staked, however, remained unchanged. The Nova Scotia Department of Mines continued active investigation of minerals vital to the war effort. These included fluorspar, barytes, diatomite, limestone, and coal. Fundamental knowledge concerning the geology and mode of occurrence of these minerals was accumulated and extensive diamond drilling was carried out on the promising occurrences. Work in these fields is being continued.

Jan 1, 1945

By W. E. Bruce, R. J. Morrell, James Paone

This chapter is a partial summary of an investigation by the U.S. Bureau of Mines (USBM) made in response to a recent request by the Assistant Secretary, Water and Power Development of the U.S. Department of the Interior, for a comprehensive review of horizontal boring technology related to underground power-line installation. This review is concerned primarily with 3 to 36-in. diam horizontal holes from several hundred to several thousand feet in length. An electric power system consists of three essential functions: generation, transmission, and distribution. The generation component includes the generating station and step-up substation; the transmission component includes the transmission line and stepdown substation at typical voltage levels ranging from 69 to 345 kv for underground lines and 69 to 500 kv for overhead transmission lines; the distribution component includes the distribution line carrying the commonly used voltages of 120, 208, and 240 v, the distribution transformer, and the line to the service customer.l The Federal Power Commission reports that 1600 miles of underground transmission lines of 60 to 345-kv capacity are now in service in the United States. By 1980, it is estimated that approximately 3000 miles of trans- mission lines will have to be placed underground.2 The cost of burying electric transmission lines underground in metropolitan areas, approximately 30 miles from the center of each of the most populated cities, will exceed $1.5 billion with the methods now available. The wide spread in unit costs of overhead and underground transmission lines narrows as right-of-way costs for overhead transmission in congested areas increase. Improved methods of underground emplacement will certainly reduce this difference in costs and even further favor underground emplacement. Also, in the future, overhead transmission lines will probably not be permitted in highly built-up areas.

Jan 1, 1970

By George I. Adams

A party, consisting of George I. Adams, of the United States Geological Survey, A. H. Purdue, of the University of Arkansas, and Ernest F. Burchard, was engaged, during the summer of 1902, in the study of the zinc- and lead-deposits of Northern Arkansas. An extensive report on this field is now in preparation. The following preliminary statement of results and conclusions is made in advance of the final publication, which will be accompanied by detailed geologic maps and other illustrations and a fuller treatment of the subject. Location.—The Northern Arkansas field embraces Marion county and adjacent portions of Boone, Baxter, Newton and Searcy counties. Outside of this area there are a few scat tered mines, notably in Sharp and Lawrence counties. The mining development lies north of the Boston mountains, in what is known as the Ozark Plateau. The country has a broken surface, as a result of dissection by streams, and there are numerous exposures of the mineral-bearing horizons in the valley slopes. This has greatly facilitated prospecting. History.—Lead-ore was discovered in Northern Arkansas by the early explorers and pioneers, and at first was utilized for rifle-ballets. Later, it attracted considerable attention, and in the '50's was smelted in the vicinity of Lead Hill. There was a revival of the industry during the "70's, but the cost of transportation was so great that it was practically abandoned. Zinc-ores at first attracted little attention, probably because they were not so well understood. Before the Civil War, however, some zinc was smelted. In the '80's, prospecting was carried on generally throughout the field, and resulted in finding zinc at so many places and so readily accessible that

Jan 1, 1904

By R. V. Whetsel, V. R. Garfias

For some time the writers have been compiling and analyzing statistics of consumption and production of petroleum, its products and related fuels, in order to arrive at a fairly accurate picture of the world-wide situation of the petroleum industry. In production, crude oil, natural gasoline, benzol and alcohol blended with motor fuel have been considered. In consumption not only refined products, but crude consumed as fuel, refinery losses, ships' bunkers and blended fuels have been taken into account to obtain a true balance between supply and demand. Statistics from practically every country and territory have been studied, and where actual figures were not available the estimates have been based on all the data available. The figures in Table 1 indicate that during the last five years the world's production has exceeded demand every year and that the aggregate difference is some 207,150,000 bbl. The supply in the United States exceeded consumption by 111,401,000 bbl. over the same five-year period and in 1931 and 1932 the demand exceeded supply, while outside the United States the excess of output over demand was 95,749,000 bbl. Table 2 combines the excess production in the United States with its favorable balance of exports over imports, showing that the United States has reduced its storage over the five years by about 136,-595,000 bbl., while in Table 3 it is shown that, including its excess of imports from the United States, the rest of the world has added 343,-745,000 bbl. to storage during the period in question, the greatest accumulation coming in 1934. Table 4 shows the world's consumption classified by countries according to the principal products. These tables also indicate that at the end of 1934 the statistical position of the petroleum industry outside the United States was decidedly unstable, a situation that probably will become more acute as a result of the added Iraq production; and that the present favorable statistical position of the industry in the United States, which is partly due to the excess of exports over imports, may be to some extent jeopardized by the unstable situation in the foreign market.

Jan 1, 1935

By O. N. Carlson, H. A. Wilhelm, J. M. Dickinson

On the basis of microscopic studies, melting-point observations, and X-ray analyses, a phase diagram is proposed for the Cb-V system. A complete series of solid solutions is formed with a minimum in the solidus at 1810°C near 35 wt pct Cb. No compounds or intermediate phases were found in the system above 650°C. THERE is an ever increasing need for better structural metals and alloys for use in nuclear reactors. In addition to the normal properties of engineering structural materials, such as high temperature strength, resistance to corrosion, and fabric-abil~ty, the nuclear properties of the material must be considered. In a nuclear reactor it is important to conserve neutrons, so a material which removes these neutrons from the reaction excessively is considered to have unfavorable nuclear properties. In nuclear-reactor design the engineer must have nuclear as well as other data available on alloys in order to make a wise selection of materials. Due to the fact that many of the common structural materials have undesirable nuclear properties, it is vital that new alloys of metals having more favorable nuclear properties be investigated. Columbium and vanadium are both high melting metals, both exhibit resistance to chemical attack, and no great difficulty is encountered in fabricating them into desired shapes. With proper treatment both metals can be cold rolled extensively without failure. In addition they have desirable nuclear properties for certain types of reactors. Therefore, the alloys of columbium and vanadium should be of interest in the atomic energy program. Since an alloy-development program is enhanced by a knowledge of the phase equilibria of the components, this investigation was undertaken to establish the phase diagram for the Cb-V system. According to the Hume-Rothery rules for alloying,' the chemical similarity, crystal structure, and atomic-size factor are favorable for a complete series of solid solutions for this system. Both elements are in the same family of group V of the periodic table and thus are quite similar chemically. The crystal structures of columbium and vanadium are compatible for extensive solid solubility, since both have body-centered-cubic structures. The atomic diameters of columbium and vanadium are 2.85 and 2.62Å, respectively. This difference of slightly more than 8 pct is well within the 15 pct maximum difference allowed for extensive solid solubility. Experimental Procedures Source of Materials: Columbium powder and sheet trimmings were obtained from the Fansteel Metallurgical Corp. According to the manufacturer the metal contains less than 1 pct impurity. An analysis of the metal showed approximately 1800 ppm C in the powder while the sheet trimmings contained less than 500 ppm C. Spectrographic analysis showed minor amounts of Ca, Cr, Fe, Mn, Si, Ti, V, and Zr in both forms of the columbium. No commercial source of vanadium having the ductility and purity desired was available to the authors at the beginning of this investigation. As a result, all of the vanadium used in this study was prepared by the bomb reduction of vanadium pen-toxide with calcium employing the method reported by Long.' Yields of massive vanadium normally were about 80 pct. Chemical analysis of the vanadium prepared in this manner showed the presence of 200 to 500 ppm N and 800 to 1000 ppm C. Minor amounts of Ca, Fe, Mn, Si, Zr, Cr, and Cb were detected by spectrographic analysis. This vanadium metal was ductile and was cold rolled into 5 mil sheet. Annealing was not necessary during this rolling and the metal retained its cold-rolling characteristic after are-melting. Preparation of Alloys: The Cb-V alloys were prepared by melting pieces of vanadium sheet togethel-with columbium in the form of sheet or pellets of powder. The melting was carried out under argon in conventional arc-melting equipment employing a tungsten electrode and a water-cooled copper crucible. Each alloy was remelted three or four times, inverting the alloy after each melting in order to assure complete mixing. Alloys normally were obtained as round flat disks, weighed approximately 70 grams, and had roughly the shape of a disk 1 1/2 in. in diameter and 1/4 in. thick. Half of each alloy

Jan 1, 1955

By David E. Jones, Dean K. Hunt, C. Y. Chen

INTRODUCTION Of all the numerous geological hazards that threaten the well-being of urban areas in the United States, probably none is so widespread, persistent, and diversified as surface subsidence (HRB-Singer, Inc., 1977). Simply defined, subsidence is the vertical displacement or sinking of the ground surface caused by either natural phenomena or man's activities. The downward movement, however, can be accompanied by horizontal movement, strain, tilt and even by a locally upward movement. Damage to structures and the environment can result from any of these movements. Extracting subsurface materials, fluids and solids, accounts for most man-induced subsidence in the United States. Among all the mining-related subsidences, the collapse of voids created by underground coal mining has been the major cause in inflicting surface damage (Comptroller General of the United States, 1979). Subsidence from coal mining may occur within a few weeks or be delayed for years, depending upon the mineral layer's depth below the surface, the overlying rock strata's characteristics, the extent and methods of mining that were employed, and the time deterioration of pillar and mine structure. Unless underground resources are not mined or control measures are implemented to prevent or minimize damage, some degree of surface subsidence and its accompanied deleterious effects are often inevitable. The ways to control the subsidence and minimize surface damage may include: 1. Precautionary measures built into new structures or surface features. 2. Preventive works applied to existing structures or surface features. 3. Mine design incorporating special underground layouts. 4. Any combination of the above measures. Upon the enactment of Public Law 95-87, the Secretary of the Interior, through the recently created Office of Surface Mining (OSM), was authorized to promulgate rules to regulate mining reclamation including subsidence control. Proposed on September 18, 1978, these rules were finalized, following public comment and hearings, on March 13, 1979, as part of the permanent regulatory program for the regulation of surface mining and reclamation operations which include the surface effects of underground mining. On January 28, 1981, Secretary Watt of the Department of the Interior issued an order to re- quire all agencies to identify with recommendations all regulations which are believed to be excessive, burdensome or counterproductive. Also on February 17, 1981. President Reagan issued Executive Order No. 12291 requiring all Federal agencies to conduct a regulatory review to make a determination that each promulgation of a regulation is clearly within the authority delegated by law and consistent with Congressional intent (Federal Register, 1981). As a result, OSM initiated the regulatory reform to revise the permanent regulatory program. Following a brief discussion of the technical aspects and the effects of subsidence on man and his environment, this paper presents a historical overview of how rules and regulations are used to govern the subsidence related problems. The development of the regulation of subsidence under Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977 (SMCRA or the Act) are also discussed, including the new regulations being developed under the regulatory reform program. SOME TECHNICAL ASPECTS Am EFFECTS OF FINE SUBSIDENCE An extensive historical review of mining subsidence is given by Zwartendyk (1971) and Shadbolt (1978). Comprehensive technical presentations have been given by Henry (1956), King and Whetton (1957), Hall and Orchard (1963). Muller, et al. (1968). Grard (1969), Voight and Pariseau (1970). Kapp and Williams (1972), Cummins and Given (1973), Brauner (1973) , and NCB (1975). A theory of surface subsidence due to underground mining was perhaps first fundamentally stated by a French engineer, Toillez, in 1838, and formulated by a Belgian engineer, Gonot, in 1839 (Goldreich, 1913, cited by Zwartendyk, 1971). Since that time,

Jan 1, 1982

By I. N. Knap

Discussion of the paper of HOWARD R. HUGHES, presented at the Now York meeting, February, 1915, and printed in Bulletin No. 99, March, 1915, pp. 629 to 635. I. N. KNAPP, Ardmore, Pa.-The claims made in the paper for the Sharp & Hughes cone bit are modest. I have used it with satisfactory results. It is a wonder for eating through hard, brittle rock; it will drill through iron pyrites that the fish-tail bit cannot enter. Soft ground is apt to contain concretions that are much harder than the containing ground. ?We have at times in drilling with a fish-tail bit thought the hole was partly in such hard material and partly in soft, thus making a difficult place to drill past in the ordinary way. By changing to a Sharp & Hughes cone bit such obstructions were easily overcome. This cone bit has greatly widened the range of work that may now be profitably accomplished by the hydraulic rotary method of drilling. It is not, however, adapted to drill soft or sticky ground, the old fish-tail bit being better for such purposes. The fish-tail bit usually scrapes its way through the material drilled, but not always. I believe at times it cuts and chips in soft friable rock. That is, the bit seems to bite into the rock, and when sufficient torsion is put on the drill stem it breaks its hold and jumps around and chips the rock from the bottom of the hole, like a stone cutter's chisel, and then takes another hold. This condition occurs only in friable material when the bit is sharp and the feed properly controlled. The Sharp & Hughes cone bit is a most valuable -tool for the rotary driller.

Jan 5, 1915

By Edgar T. Wherry

EDGAR .T. WHERRY,* Washington, D. C. (communication to the Secretary ?).-Dr. Pogue's presentation of the facts concerning the emerald deposits is very clear and convincing, and the only addition that I can suggest is a summary of previous theories of origin. He makes it evident that the pegmatite theory is the only one capable of explaining the existing relations, but upon certain details there may be some difference of opinion. If I understand the term pneumatolytic, it does not imply that all the elements concerned in a given deposit were transported as gases, but rather that the crystallization of these elements into the various minerals was favored by the presence of certain gaseous substances, notably H20, C02 and HF. It is highly improbable that the oxides of glucinum, aluminum, chromium, and silicon, which enter into the composition of the mineral emerald could have been transported in the gaseous form. The same is true of the metallic constituents of the parisite and other associated minerals. The explanation suggested, that solutions separated into liquid and gaseous portions, the latter ascending and forming the emerald in the upper portions of the rock only, therefore, seems to me untenable. When two formations exist side by side and one, A, is mineralized while the other, B, is barren, the possible explanations may he classed as (1) chemical, and (2) physical. 1. Some chemical feature of A not found in B might have caused crystallization of certain minerals in the former, which did not appear in the latter. In the present instance both rocks appear to be so similar chemically that no such effect can be looked for. Pogue mentions carbon as a possible precipitating agent, but describes both formations as carbonaceous, so that the difference in the minerals of the two can not be thus explained.

Jan 10, 1916

We note with sincere regret the death of H. T. Chen,, who was killed by forest fire in the mountainous re-ion of Kokiu-Chang where he had been operating as Engineer in Chief of the Yunnan Tin Trading Co. Mr. Chen graduated in 1911 from the Department, of Mines, .University of California, being the first Chinese Government scholar in mining to attend that institution; and one of the first in America. He came of a distinguished family, many members of Which are in official life in Peking and in his native province of Hunan, all of whom are noted for their classical scholarship. He was himself a Hsiao-tsai or Bachelor of Arts, a coveted degree of the old literati class, Which he won under the Manchu regime when he was still a stripling. His mining work in Yunnan was carried on with only the most primitive facilities and in a distant province, but was, nevertheless, attended with great success and profit for his company. The region is infested with brigands and rebellious troops. who frequently turn marauders and prey upon the countryside, and Mr. Chen has had to go to the mines always with a large armed guard sometimes aggregating 150 men and some hundreds of miners, also armed. Two armed squads of men keep in touch with his base 'at Kokiu-Chang every day to get supplies and food, and it is feared that the brigands who have thus been prevented from plundering and mobbing his parties have started 'he fires to burn him out, with the disastrous result reported. Mr. Chen has thus given his life to his country in the attempt to win for modern China and Chinese civilization the raw materials of her new industrial life. He did so cheerfully and with full appreciation of the dangers that beset him, and China regards this as one of the most noble sacrifices of her young sons on the altar of patriotism. He is survived by a daughter of two years and by his widow who was also a graduate of the University of California and will be remembered by her classmates as Lucy Kong, 1912.

Jan 7, 1917

By Waldemar Lindgren

Introduction To the miner, as well as to the geologist, the eastern part of Cuba is a most interesting region. Here we find, in contrast to the moderate relief predominating elsewhere in the island, an imposing mountain range, the Sierra Maestra, extending east and west parallel to the coast, its precipitous front facing the blue Caribbean Sea.. In a geological sense this range is largely an unknown land, the only well-explored region being that in the vicinity of Santiago. The range also contains the most important mineral deposits of the island. They comprise, first, a series of iron deposits yielding a partly hematitized magnetite with low content of phosphorus; second, a remarkable copper-bearing vein at El Cobre; and third, various manganese deposits. Probably more deposits will be found, for the larger and western part of the range is as yet little explored and its slopes are covered by a thick tropical jungle. The following notes are based on a short visit by the senior author in January and February of 1914 to the mines at Daiquiri, El Cobre, and Mayari. For many courtesies and great assistance he is deeply obliged to Charles F. Rand, President of the Spanish-American Iron Co.; to George W. Pfeiffer, General Manager, and to the several members of his staff.

Jan 10, 1915

By F. Kurata, A. F. Bertuzzi, P. C. Davis, T. L. Gore

The phase and volumetric properties of 10 very volatile mixtures are presented for temperatures from — 200°F to above the critical points. These mixtures consisted of natural gases and of mixtures of natural gases with methane and nitrogen. Existing correlations of compressibility factors have been extended to apply to these mixtures. Existing correlations of critical pressures and temperatures do not apply to these mixtures. Methods have been developed for estimating critical temperatures of these mixtures to ± 4°F and critical pressures to 2 5 per cent. These methods apply to other volatile and very volatile mixtures. The results of this work are particularly applicable to the separation of nitrogen from hydrocarbons by low-temperature distillation. INTRODUCTION Knowledge of the low-temperature phase and volumetric properties of natural gases and of other mixtures of the light hydrocarbons is becoming increasingly important as interest in low-temperature separation processes increases. Low-temperature distillation has been used to separate ethane and ethylene from natural gas and from refinery gases for petrochemical uses. Removal of nitrogen from natural gas by low-temperature distillation has been proposed 7,20 as a means of increasing the capacity of existing gas transmission lines and of improving the marketability of the gas. Further application of low-temperature separation processes has been retarded by lack of data on the phase and volumetric behavior of mixtures at low-temperatures and at high pressures. This paper presents the results of determination of the phase and volumetric properties of 10 very volatile mixtures at temperatures from - 200 °F to above the critical point. These mixtures consisted of natural gases with methane and nitrogen. Generalized methods are presented for estimating the critical temperatures, critical pressures, and the densities of such mixtures. EXPERIMENTAL APPARATUS AND PROCEDURES The apparatus and the experimental procedures have been described in an earlier paper13. The method consists of displacing the mixture from a reservoir which is maintained at constant temperature and pressure into an agitated glass equilibrium cell which is maintained at constant temperature. The liquid level within the glass equilibrium cell was visually observed, and the pressure was measured to within & 3 psi with a calibrated Bourdon gage. COMPOSITIONS OF MIXTURES STUDIED The compositions of the mixtures studied are summarized in Table 1. The measured properties included in Table 1 will be discussed later in this paper. The sources of these gases are described below: Gas "A-1'' was obtained from the Phillips Petroleum Co. Its composition was reported in connection with earlier work." The properties of this gas were reported in an earlier paper.13 Gases "A-2, A-3, A-4" were prepared by mixing nitrogen with gas "A-1." Gas "AB-1" was prepared by mixing methane with gas "A-1." The properties of this gas were reported in an earlier paper.'" Gases "AB-2" and "AB-3" were prepared by mixing nitrogen with gas "AB-1." Gas "B" was obtained by W. W. Bodle of J, F. Pritchard & Co. from the primary separator of a well in western Kansas. Gas "C" was obtained from a Cities Service Co. pipeline at Lawrence, Kans. Gas "D" was prepared by mixing gas "AB" with gas "C."

Jan 1, 1955

By S. B. Lement

THE nature of the carbides that form during the tempering of martensite is a subject of continuing controversy. The only direct methods of identification available are X-ray and electron diffraction. These methods are subject to several difficulties. Only a relatively few diffraction lines of appreciable intensity emanate from carbide phases that are formed at low tempering temperatures. Furthermore, some overlapping of carbide and matrix lines occurs. There is also the problem that numerous lines in the patterns of possible carbide phases that may be present have about the same d-spacings. Increasing the number of carbide lines and eliminating the matrix lines can be accomplished by extraction techniques. However, there is always the possibility that a change in carbide structure will occur as a result of removal from the parent matrix. Therefore, such techniques as electrolytic extraction and making extraction replicas should be checked by other methods. For identifying small amounts of carbide in a tempered martensitic matrix, electron diffraction carried out in reflection is more advantageous than X-ray diffraction. To properly prepare a specimen for reflection electron diffraction, an etchant that will selectively attack the matrix and thereby cause the carbide particles to stand in relief should be used. With an electron beam directed at a grazing angle to the specimen surface, the major contribution

Jan 1, 1960

By M. W. Cox, V. F. Hollister

EXPLORATION for metallic mineral deposits is carried on by those special adaptations of methods which the explorer believes will yield most economically or satisfactorily the particular answer sought. In this project the usual methods of geologic observation, recording, and interpretation, when combined with magnetic geophysical methods and geochemical soil sampling, led to disclosures of appreciable zinc mineralization where none was visible in surface exposure. Since 1945 considerable work has been done with geochemical prospecting methods, chiefly in determining the presence and distribution of various elements existing in minor amounts in rocks, soil, vegetation or waters of mineralized areas. Such work, in which the U. S. Geological Survey has taken the lead, finds a ready place in the field repertoire of the exploration geologist as a supplement, not a substitute, for other methods. The Chollet project was carried out in 1951 by the American Smelting & Refining Co. near its Van Stone mine in northern Stevens County, Wash., in the area shown in Fig. 1. The Van Stone mine is located in the Onion Creek drainage of the Selkirk Mountains, midway between the towns of Colville and Northport, Wash., and some twenty airline miles west of the Metaline mining district. Its zinc-lead orebodies, currently yielding about 1000 tpd of ore, occur as bedding replacement deposits in the middle Cambrian Metaline formation near an intrusive granodiorite contact. The target of exploration at the Chollet prospect was a similar geologic environment along the intrusive contact about 5 miles west of the mine. Geographic Setting The Chollet ground covers a north-facing slope at 3000 to 4000-ft elevation. Second-growth jack pine and tamarack with some hemlock and yellow pine make a thick forest cover. A heavy under-forest of alder, willow, and lesser shrubs occupies the draws, see Fig. 2. Grassy slopes appear at higher elevations. The lower slopes are underlain by a thick blanket of glacial till and alluvium so that outcrops are scarce; however, perhaps 50 pct rock exposure prevails at higher elevations. This part of northern Washington annually receives about 25 in. of precipitation, which largely falls as snow in the winter months. Summers are dry with occasional rainy periods. General Geology The Van Stone mine and the Chollet prospect lie along the southern margin of a westerly extending lobe of the Kaniksu batholith, one of the series of granodioritic masses that are intrusive into Cretaceous and older rocks in northern Washington and southern British Columbia. The margin is composed of complexly deformed Paleozoic sediments ranging in age from the lower Cambrian Maitlen phyllite on the east, through middle Cambrian Metaline formation (limestone and dolomite), to Ordovician Ledbetter slate on the west. In general the formations strike N10 to 50E and dip steeply northwestward, although dip reversals and minor folding occur. This general rock distribution is shown on Fig. 3. In this area the Metaline formation, which is the host rock for mineralization, appears to be of about 4000-ft thickness that can be conveniently divided into the same three units defined by Park and Cannon' for the Metaline area. The basal part consists of 1000 ft of interbedded white limestone, argillaceous limestone, and gray silty argillite. The middle part, approximately 1500 ft thick, consists of fine-grained black, gray, and white dolomite. This unit also contains minor interbedded limestone. The upper part is a gray massive limestone about 1500 ft thick that grades upward into slaty limestone and slate capped locally by a thin black jas-peroidal dolomite which is either the uppermost member of the Metaline formation or the basal member of the overlying Ledbetter (Ordovician)

Jan 1, 1956

By Allen H. Rogers

THE need for coordinated effort on public problem by engineers has long been felt. Early in June there will assemble in Washington a conference composed of delegates from all the engineering organizations in the country. The call for this conference is issued by the Joint Conference , Committee of the four national societies as the completion of its work on the organization of a congress composed of delegates representing all the engineering organizations of the United States. The plan for this confederation was presented at a joint meeting of the administrative boards of the national founder societies on Jan. 23, 1920; and was unanimously approved in principle by that meeting. The work of the committee since that date has consisted in drafting a constitution of the organization to be presented at the conference for discussion and, after such amendments as may be adopted, acceptance.

Jan 1, 1920

By Peter T. Luckie, Harold L. Lovell, E. R. Palowitch, A. W. Deurbrouck, James K. Kindig

PART 1: DENSE MEDIUM SEPARATION by E. R. PALOWITCH and A. W. DEURBROUK INTRODUCTION During 1965, 64.9 percent of the 512 million tons of bituminous coal and lignite produced was cleaned mechanically, of which 95 million tons was cleaned by dense medium processes.l The percentage of bituminous coal and lignite cleaned mechanically by dense medium processes rose from 7.0 to 28.5 percent from 1938 to 1965. Dense medium separations include those coal preparation processes which clean raw coal by immersing it in a fluid having a density intermediate between clean coal and reject. As there is a general correlation between ash content and specific gravity, it is possible to achieve the required degree of removal of ash-forming impurities from a raw coal by regulating the specific gravity of the separating fluid. Dense medium processes offer the following advantages over other coal cleaning processes : 1. Ability to make sharp separations at any specific gravity within the range normally required even in the presence of high percentages of the feed in the range of e 0.1 specific gravity units. 2. Ability to maintain a separating gravity that can be controlled with ±0.005 specific gravity units. 3. Ability to handle a wide range of sizes (up to 14 inches). 4. Relatively low capital and operating costs when considered in terms of high capacity and small space requirements. 5. Ability to change specific gravity of separation to meet varying market requirements. 6. Ability to handle fluctuations in feed both in terms of quantity and quality. HISTORY Sir Henry Bessemer patented the first dense medium process in 1858. Solutions of the chlorides of iron, manganese, barium and calcium were proposed as separating liquids; the separation was made in a cone-shaped separator. One large-scale plant using calcium chloride was erected in Germany but soon was abandoned. The Chance process, using a mixture of sand and water, was first

Jan 1, 1968