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By A. H. Grobe, F. N. Rhines

AT elevated temperatures the oxide of silver is unstable in the air at atmospheric pressure, consequently no external oxide scale forms upon pure silver under conditions of high-temperature annealing When small quantities of certain alloying elements are present in the silver, the formation of a thin external scale is possible' and in addition there may form a subscale composed of the oxide of the solute element precipitated within the body of the silver Norbury2 and Leroux and Raub3 have reported internal oxidation (subscale formation) in alloys of silver with 2, 7 5, and 30 per cent of copper The presence of the subscale is believed to be responsible, at least in part, for the objectionable "fire mark" in Sterling silver' Several other alloys of silver, after oxidizing heat-treatments, are known to exhibit undesirable polishing characteristics that may be the result of internal oxidation Except for the absence of an external scale of silver oxide, it is to be anticipated that silver alloys will prove to be very similar in their oxidation behavior to the alloys of copper, the oxidation characteristics of which have been studied in some detail 5,6 The present research confirms this anticipation The oxidation of a series of 20 dilute alloys of silver has been studied metallographically, some types of subscale not encountered among the copper alloys have been found Instances of internal oxidation in alloys of most of the metals of the I-b and VIII groups of the periodic system are on record, but evidence of this type of oxidation in alloys of the metals of the intermediate groups is lacking A number of the metals of the intermediate group, among them cadmium, lead, tin, and zinc, appear to provide the conditions essential to subscale formation, i e , they form oxides with a relatively low negative free energy of formation, they dissolve other metals that form more stable oxides, and, presumably, oxygen will diffuse through them In a study of 4o alloys of these white metals only a few cases of internal oxidation have been found The probable reasons for this difference in behavior will be discussed presently EXPERIMENTAL PROCEDURE Silver -The silver alloys employed in the oxidation studies were prepared in heats of 30 grams each from high-purity silver (99 993 per cent Ag)* and the purest avail-

Jan 1, 1942

By R. F. Mehl, C. S. Barrett, A. H. Geisler

THE studies of the mechanism of precipitation and of the resulting property changes in aluminum-silver alloys1-3 have presented some new concepts of the aging reaction-concepts that may be fundamental in establishing a complete quantitative theory of age-hardening. With both aluminum-copper and aluminum-silver alloys, thin platelike aggregates form parallel to the Widmanstätten planes of precipitation.1,4 These platelets grow in lateral dimensions and in thickness with aging time until they are thick enough to produce an X-ray diffraction line pattern. Their structure is that of a transition lattice which is coherent with the matrix, since the atomic spacings in the matrix and the precipitate are the same on each side of their common interface.2,4 The equilibrium precipitate forms later from and at the expense of the transition lattice. Since age-hardening occurs during the formation and growth of the transition lattice, the major contributor to the hardening no doubt is the stress condition in the matrix resulting from the matrix holding the precipitate in the coherent condition. The development of these stresses also appears to be responsible for an increase in the electrical resistance superimposed on the normal decrease resulting from a change in the concentration of the matrix during aging.3 The two consecutive reactions constituting the aging process are accompanied by characteristic microstructural alterations. The initial precipitation process results in the formation of a Widmanstätten figure, while the later transformation of the transition lattice to the equilibrium lattice is accompanied by a coalescence, in the case of aluminum-copper alloys,5 and by the appearance of light areas at the grain boundaries with aluminum-silver alloys showing a structural rearrangement of matrix and precipitate.3 This latter reaction is similar microscopically to the so-called "discontinuous precipitation." Possibly discontinuous precipitation is a process that often if not always follows true precipitation of a coherent lattice and during which the transformation of the coherent transition lattice to the equilibrium lattice takes place accompanied by matrix recrystallization.3 EXPERIMENTAL PROCEDURE The alloys were made using 99.97 per cent Al or distilled magnesium, with

Jan 1, 1943

During induration of iron ore pellets produced from magnetite concentrates, there are many reactions occurring simultaneously. While the magnetite is being oxidised to hematite, carbonate fluxes are being calcined, leading to the formation of complex oxides. Calcination of fluxes and the formation of calcium and magnesium ferrites and silicates during the preheat stage can influence the magnetite oxidation process. As the calcination reaction proceeds quicker than oxidation at temperatures experienced during the preheat stage (700 - 1200¦C), the bulk flow of CO2 emanating from within the pellet should disrupt the diffusion of O2 to the magnetite reaction as the gas fluxes are similar in magnitude. This increases the time required for the oxidation of the pellet. Using an infrared rapid heating furnace, experiments were performed on heating individual magnetite green balls in an air atmosphere. These experiments showed that time played an important role in the extent of oxidation and calcination and temperature significantly influenced the initial evolution of high temperature phases such as magnesioferrite, calcium ferrites and calcium silicates. Understanding the kinetics of all these reactions for a particular pellet feed, and their interaction, is important for optimising the design of the induration furnace.

Jan 1, 2005

By Seymour K. M, Sampson D. B, Walker I. W

Ashton Mining Limited is the operator of two wholly-owned gold mine/mill complexes at Laverton and Leonora. In addition, Ashton owns 43% of the Bardoc Joint Venture mine/mill complex, which is operated by Aberfoyle Pty Limited. All three of these operations are located in the Eastern Goldfields region of Western Australia (Figure 1). At Laverton, milling capacity is in the order of 1 million tonnes per year in 3 mills (Duketon 200,000 tpa, Cork Tree Well 650,000 tpa and Craiggiemore 150,000 tpa). These mills service a distance of 80 km, from Baneygo in the north to Craiggiemore in the south. Mineral tenements cover a 150 km long stretch of a series of sub-parallel mineralised structures. At Leonora, the Harbour Lights mill is designed to treat 750,000 tpa of sulphide ore, and has treated oxide ores at an annualised rate of over 1 million tonnes/year. The mill is supported by several tenement blocks that lie within a 50 km trucking radius of the mill. The most important of these is the Mertondale tenement block, which covers approximately 25km of the Mertondale Shear Zone.

Jan 1, 1991

By A. A. Blow

The productive area of the Leadville mining district immediately adjoining the city of Leadville, which, by its wonderful richness, has attracted the attention of the mining world for the past twelve years, may, with a few exceptions, he considered as divided into seven local mining centers, separated one from another by the topographical features of the country, and designated by common consent as Fryer Hill, Yankee Hill, Breece Hill, Rock Mill, Printer-Boy Hill, Iron Hill, and Carbonate Hill. Of these seven distinot mining localities, or groups of mines, the central one, Iron Hill, is the one of greatest importance and interest. It was the scene of the earliest discovery of carbonates, as far back as 1875, and since that time has always maintained its position

Jan 1, 1890

By N. A. Gokcen

THE data of Chaudron,1 Tonosaki,2 and Collins³ on the thermodynamic properties of MOO, disagree widely. These authors, by using essentially similar methods, studied the following reaction: 1/2MoO2(s) + H2(g) == i/2Mo(s) + Ph,o H2O(g),K = —----- [1] Ph2 Tonosaki used a vacuum system consisting of a furnace containing MOO, and a water saturator whose temperature was kept at 25 °C with a thermostat. After repeated evacuation, hydrogen was admitted slowly into the system. The experiments were based upon the fact that at a constant furnace temperature and constant partial pressure of water, the total pressure of gas mixture over MOO? + Mo is constant. Any attempt to vary the pressure by external forces would vary only the amounts of MoO2, and Mo, after which the pressure should return to the equilibrium value in accordance with the equilibrium constant of reaction 1. The actual value of K was determined from the total equilibrium pressure (sum of Ph2o + Ph2) at each temperature. The total pressure of gas was varied within the range of 80.2 to 125.4 mm Hg, within a temperature range of 645" to 823 °C. The results were summarized as log K = 0.9413 — 1444.6/T for reaction 1. The ratio of H2O/H2 was considered to be uniform in spite of the presence of a thermal gradient across the static gas phase. It was shown by Rosenqvist and Cox,' however, that in somewhat similar circumstances the error resulting from thermal diffusion may be large. Collins³ improved Tonosaki's method by attempting to avoid thermal diffusion errors. His equilibrium data were obtained at 700°, 800°, and 900° C, and the result for reaction 1 was expressed as log K = 1.258 — 1822/T. The purpose of this investigation was to study reaction 1, avoiding the thermal diffusion errors, and to obtain equilibrium data in a considerably wide temperature range for the reliable extrapolation of the resulting thermodynamic functions. Experimental Procedure The diagram of the apparatus is shown in Fig. 1. Tank hydrogen was passed through a tube containing platinized asbestos at 425 °C in order to convert a trace of oxygen into water vapor. The flow rate was carefully controlled with a capillary-type flow-meter B and a bubbling column D. The gas was then presaturated sufficiently at P and led into a condenser system immersed in a thermostat, controlled to within ±0.002C. The temperature of the thermostat was measured with a thermometer calibrated against a certified standard. The temperature of P was adjusted to avoid the condensation of unduly large amounts of water as judged from the rate of flow out of the capillary tube M. Argon was purified by passing it through magnesium chips kept at 630°C. After passing through the flowmeter B', it was mixed with moist hydrogen emerging from the thermostat. The resulting gas mixture was then led into the hot zone of the furnace through the heated glass tubing and the silica tube S, thus insuring the same ratio of PII2o/Ph2 from the condenser to the reaction chamber, thus avoiding thermal diffusion. The entire gas system was of all-glass construction, except at the magnesium train. The furnace comprised a glazed alumina tube over which a 15-in. platinum coil was wound. The lower end of the alumina tube was tightly closed with a brass bottom and a silicone rubber gasket, and the upper end with two glass disks, each with a hole of 1/16 in. in diameter, through which the gas mixture escaped into the atmosphere. A back-up coil of kanthal wire facilitated the temperature control of the furnace. A coil of annealed molybdenum strip of 99.99 pct purity, 0.005 in. thick and 0.050 in. wide, and weighing 17 g was hung in the furnace with a 0.010-in. platinum wire attached to one end of a sensitive analytical balance. The temperature of the furnace was measured with a Pt-Pt-10 pct Rh thermocouple checked against a standard. The experimental procedure consisted of heating the gas purification trains, adjusting the gas flow rates, attaining a constant thermostatic temperature, flushing the entire system for 2 hr while heating the furnace to well above the expected equilibrium temperature and then cooling it at a rate of 0.3°C per min during which time the change in the weight of molybdenum was observed on the balance. For a given thermostatic temperature, i.e., a constant Prr,o/Px,, molybdenum oxidized upon cooling slightly below the equilibrium temperature. The procedure was then repeated by heating the furnace and thus reaching a temperature slightly above the equilibrium value. The average of the two temperatures, differing by 2" to 3"C, was considered to be the true equilibrium temperature. In order to determine the stoichiometric composition of the oxide phase present in this investigation,

Jan 1, 1954

By Augustus Locke

In 1900, when. the public first heard of "secondary enrichment," the Butte chalcocite seemed clearly supergene. Mining, through successive regions of leached capping, bonanza sulfide, and sulfide less rich, had paused at lean bottom levels which, though chalcocite-bearing, suggested the waning of copper. The deepest chalcocite, at 1500 ft., was yet too shallow to disturb the supergene hypothesis. But, with deeper mining, lean levels yielded to fat ones. Here and there they showed, within the same vein, an inverted distribution, chalcopyrite above and chalcocite below. To the miners' astonishment, they carried chal-cocite, unaffected by cross faults, on an independent course to the depth of 2500 ft. The pattern of ore distribution, hitherto revealed only in fragments, was now appearing in perspective, and, in the depth of the chalcocite, was beginning to make Butte differ from all districts where the chalcocite is indubitably supergene. The idea of hypogene origin at length came into favor; by 1913, when Sales' advocated this origin, the argument had become a powerful one. This argument rested on field evidence; but, already, there was beginning to emerge microscopic evidence not included in this argument. Especially pertinent was the proof that (1) the deep chalcocite lies in-mixed with bornite, often microscopic; (2) the deep chalcocite often replaces bornite; and (3) replacement of bornite by chalcocite is accomplished more easily than that of pyrite, enargite, or chalcopyrite. The microscopic evidence has been accumulating for ten years and it demands

Jan 1, 1924

By R. G. Hudson, L. Yang

In electrochemical separation of metals, it is necessary to control the potential applied between the electrodes so that only the desired electrode reactions can occur. A knowledge of the minimum potential needed for a given electrode reaction to take place continuously is therefore pertinent to the success of the process. In molten chloride systems at high temperatures, activation polarization is believed to be small,1,2 so the minimum potential needed for the electrolytic decomposition of a molten metal chloride MC1n (n = valence of the metal ion) is therefore essentially the equilibrium electrode potential E of the metal-chlorine galvanic cell in the solution. If the decomposition products are pure M and chlorine at a pressure of p atm, E*Eo-rt/nf in [i] Since EO (the standard electrode potential of MCln) is a constant at a given temperature and R (the gas constant), and F (the Faraday's constant) are all constants, the variation of E with the electrolytic bath conditions is largely determined by the effect of the latter on the activity of the metal chloride amcln (standard state = pure MC1,). Measurement of E and study of how amCin varies with temperature and concentration, the nature of the solvent, and that of the coexisting solutes are therefore pertinent in the selection of optimum operating conditions for the electrochemical separation of metals. Because of its low melting point, high decomposition potentials of its components, and the low solubility of heavier metals in it, the LiC1-KC1 eutectic melt is a useful solvent and has been used in the electrodeposition of Mo,3Ce,4 and u5 metals. Senderoff and Brenner3 measured the potentials of Zn/Zn++, Fe/Fe++, Cu/Cu+, Mo/Mo+++, and Ag/Ag+ against an Ag/AgCl (pure) reference electrode at 600°C and a concentration of 4.1 mole pct of each chloride and came to the conclusion that complex ion formation occurred in some of the melts. Laitinen and LiUe gave an electromotive force series at 450°C for a number of {Metal/Metal ions (unit activity)) electrodes in LiC1-KC1 eutectic melt, the {pt/pt++ (unit activity)) electrode being chosen as the reference. Walker and Danly7 studied the ther-modynamic properties of NiC12 in LiC1-KC1 eutectic melt over a wide range of temperatures and concentrations by measuring the electrode potential between a nickel electrode and a chlorine electrode in the melt. Since potential measurements made by using the chlorine reference electrode are of more direct significance both in the study of electrochemical separation and in the evaluation of the thermodynamic properties of the melt, it is therefore decided to measure the electrode potentials of cells of the type {M/MCin (mole fraction = N) in LiC1-KC1 eutectic melt/Cl2 over a range of N values and temperature for a number of metal chlorides. The results should indicate the order by which the various metals plate out on the cathode and how this order is affected by temperature and the concentration of the metal chloride in the solu-

Jan 1, 1960

By R. B. Snow

THIS paper describes a technique of polishing and etching specimens of open-hearth furnace slags or hearth aggregates for identification of the crystalline constituents-lime (CaO), tricalcium silicate (3CaO•SiO2), dicalcium silicate (2CaO-SiO2), monticellite (CaO•MgO-SiO2), or forsterite (2MgO•SiO2), with especial emphasis on the mineral merwinite (3CaO-MgO.2SiO2). With proper standardization, this identification does not require the use of the petrographic microscope. The composition of basic open-hearth slags and furnace bottoms falls, almost without exception, within systems containing CaO, MgO, "FeO," MnO and SiO2, in which the number of basic molecules so greatly exceeds the orthosilicate ratio (two molecules of base to one of silica) that free basic oxides, and combinations between them such as aluminates or ferrites, are present in cooled specimens. Orthosilicates of (CaO + MgO) are the most common in such specimens, since in nearly all cases, except premelt slags, the molecular ratio of (CaO + MgO) to SiO2 is more than 2 to r. When sufficient lime is available it combines with the silica to form dicalcium silicate (2CaO•SiO2), which contains little, if any, MgO, FeO or MnO in solid solution whereas the latter oxides combine to form the oxide solid solution known as periclase. If the lime present is insufficient to form dicalcium silicate (2CaO•SiO2) it combines with MgO to form either merwinite (3CaO•MgO.2SiO2) or monticellite (CaO-MgO•SiO2); these minerals take little if any FeO or MnO into solid solution and the remaining MgO, FeO and MnO combine as periclase. This generalization seems to be valid for basic slags and furnace bottoms, since minerals such as CaO-MnO•SiO2 and CaO-FeO-SiO2 are found only in slags in which the lime-silica ratio is less than 2 and are not observed in specimens from furnace bottoms. The identification of crystalline constituents in such materials, especially of fine crystals in the groundmass, is difficult under the petrographic microscope. They are often masked by their neighbors because of their small size in relation to the thickness of the thin section and because of the presence of opaque or colored constituents. The indices of retraction and the optical sign of the mineral are sometimes difficult to determine because of the small size or because of twinning or of inclusions within the crystal. Moreover, the positive identification of merwinite (3CaO•MgO.2SiO2) from its optical properties is usually difficult in the presence of dicalcium silicate (2CaO•SiO2). CaO, MgO, 3CaO•SiO2 and 2CaO•SiO2 in open-hearth slags have been identified for a number of years in the U.S. Steel Corporation Laboratory by the usual

Jan 1, 1947

By J. Arce

El presente trabajo describe el proceso de exploración del yacimiento minero de Tintaya en Cusco. Para ello, se realiza un estudio de polarización inducidad y dos perforaciones donde se encontró que dicho yacimiento no se limita al contenido de reservas de óxidos, sino que a partir de esta investigación se pudo localizar gran cantidad de minerales de alcance vertical con bornita y otros sulfuros, considerándolo un potencial de depósito de sulfuros en la minería peruana.

Nov 20, 1972

By E. H. Dix

All commercial aluminum contains small percentages of copper, iron, and silicon as unavoidable impurities. The purest metal obtainable commercially, special grade high purity ingot, contains a maximum of 0.50 per cent. impurities of which the usual minimum amount of copper is 0.01 per cent.; silicon, 0.12 per cent.; and iron, 0.20 per cent. This grade is too costly for most purposes. The two standard grades, Nos. 1 and 2, containing a minimum of 99.0 and 98.0 per cent. aluminum, respectively, are more generally used. Other grades of secondary aluminum often contain as high as 3 or 4 per cent. of impurities, which include 1 per cent., or more, of zinc. Specifications for high-grade aluminum-casting alloys generally allow a maximum of 1.7 per cent. for total impurities. The S. A. E. Specification No. 33, which is intended to cover alloys made from secondary aluminum ingot, gives the iron maximum as 1.5 per cent. and the maximum for silicon (including manganese and tin) as 0.75 per cent. The effect of even relatively small amounts of impurities on the physical properties of ingot aluminum is shown by the following cornparison of two lots of aluminum, which may be taken as representative of special grade and grade No. 2 ingot, respectively. AnalysEs Special Grade, Gbade No. 2, Per Cent. PeR CBnt. Copper................................. 0.01 0.32 Silicon................................. 0.12 0.32 Iron................................... 0.42 0.82 Aluminum.............................. 99.45 98.54

Jan 1, 1923

By W. L. Saunders

It has been estimated that the value of the mineral products of the United States is about $2,000,000,000 a year; that about $25,000,000 is expended annually for explosives and that about double this sum is paid in wages where blasting is done. The value of the mineral products does not adequately express the importance of the industry involved in the excavation of rock and ore because of the enormous sums of money expended in tunnel driving, in quarries, and in open-cut excavation generally. We know that the Catskill Aqueduct in the neighborhood of New York, which is now nearing completion, has cost some $165,000,000 and that about one-third of this may be rated as rock excavation. These illustrations are given in order to call attention to the great importance of an industry the extension and development of which in our industrial life depend so much upon the economics of rock drilling. Reference has been made to the new Catskill Aqueduct. There are three aqueducts leading into New York, each built at periods separated by some 20 years of time. The first one, known as the Old Aqueduct, conveys the waters of the Croton river to New York City in a manner which reminds one of the old Roman aqueducts, the ruins of which are still in evidence. The engineers who laid out these old conduits sought to direct their lines around the hills and into the valleys, at all times avoiding the rock. When it was necessary to cross a river or a deep ravine, a bridge or causeway was constructed. High Bridge, over the Harlem river, is an arched masonry viaduct differing in no essential features from the aqueducts of the Romans. When the second Croton Aqueduct was built, about the year 1890, the art of drilling rock had been so far perfected, and the use of explosives, through the invention of dynamite, had become so general, that this waterway was planned and executed on straight lines, following rather than avoiding the rock. The second Croton Aqueduct is a tunnel through rock, about 32 miles in length; material gneiss, almost as hard as granite. Its construction was made practicable by sinking

Jan 1, 1914

By Richard L. Gordon, William A. Vogely

ENERGY POI.ICY-PRINCIPLES AND THEIR PRACTICE Persistently, at least since the end of World War 11, governments have intervened broadly, deeply, and incoherently in major energy markets. If we take a broad definition of energy that encompasses gas distribution and electric power, we can observe regulations of even older vintage. This trend, of course, is not unique to energy. Expansion of government controls has occurred in many areas. The relevant basic question about energy regulation, therefore, is not why is energy special, but whether any general principles exist to explain the wisdom of existing regulations. This review takes place at a time, the middle 1980s, in which a massive onslaught is being undertaken against government regulation. However, the present chapter is influenced primarily by my observations of the failures of energy regulations and not by any inspiration from those ideologically opposed to government intervention. Several subquestions arise in policy appraisal. A primary need is to establish clear objectives and determine the consistency between these goals and the policies imposed. Thus, the first step is to set objectives. The next is to outline ways to attain these goals. However, it should be recognized that many apparently distinct options are economically equivalent. When the goal is to charge producers or consumers for something, it is possible to attain the same result through either government ownership or taxing private transactions. The tax can raise the price to the level the government would have charged if it were the owner. Creation of a Department of Energy is not necessarily any different from having separate energy agencies well coordinated by some small supervisory body. Thus, a distinction should be made between substance and form in policymaking. The critical substance concerns such matters as whether the government imposes financial penalties, incentives, or rules to attain a goal. Then, there can be many equivalent ways to implement the basic policy form. The second prior illustration suggests that one favorite question is how to attain proper integration of policy. At various times, voices on either (or even both) sides of the Atlantic have called for a coordinated energy policy. The U.S. Paley Commission made this a primary goal for future policy. The western European governments that were the founding members of the Coal and Steel, Economic, and Atomic Energy Communities spent much time in the middle fifties and much of the sixties trying futilely to agree on an energy policy. (See Gordon, 1970 for an annotated review). The energy price rises of the 1970s rekindled United States interest in coordination. However, astute observers of the problem such as O. C. Herfindahl of the United States and Maurice Allais (1 962) in France warned the discussions confused form with substance. The crucial issues were what were the goals and what were the best types of policies to attain such goals. Policy suffered, not from poor organization, but from discord about the goals and how to attain them. All this suggests that we need principles to guide policy appraisal. The branch of economic theory known as welfare economics concentrates on providing guidance about the problems of policymaking. The theory examines both what

Jan 1, 1985

By George M. Fowler

THE Tri-State district, as outlined in this paper, refers to the entire mineralized area in southwestern Missouri, southeastern Kansas and northeastern Oklahoma (Fig. 1). The part of the district in Missouri and near Galena, Kans., is still sometimes referred to as the Joplin district (Fig. 2). The Picher-Miami area is that part of the Tri-State district located contiguously in Kansas and Oklahoma in the vicinity of Baxter Springs, Picher and Miami. This paper is confined almost wholly to the ore deposits of the Tri-State district and particularly to the Picher-Miami area. Our study of the ore deposits of this district dates from late in 1925 (by Fowler) and early in 1927 (by Lyden) to the present. Our work has been confined almost entirely to the search for ore for numerous companies and individuals. It was not possible for us to undertake numerous highly interesting investigations which presented themselves but which would not immediately help in finding ore. We particularly refer to the general structural geology of the Ozark uplift, the genesis of the ore, and other problems of a similar nature. The local and general structural problems of the district are being solved gradually as the work progresses. The factors that control the loci of the several orebodies are evident. This paper is based almost exclusively upon our own observations. Most of the important mines in the Picher-Miami area were studied in detail. A map (Fig. 5) is included which shows this area and the properties we have examined to date. When it was convenient we visited, studied and compared structural relations in numerous mines in states outside the district. Some of these observations are noted in this paper.

Jan 1, 1932

By Milton H. Fies

Although pig iron from iron ore and red cedar charcoal preceded the mining of coal by many years, for tradition says that Alabama iron was used to shoe the horses of Andrew Jackson's soldiers, coal was not produced until 1830. In that year, coal was mined in Tuscaloosa County, in the vicinity of what is now the University of Alabama, and shipped on flat boats (obviously during the wet season, for there were many shoals) down the Warrior River to Mobile. About that time, the first railroad, the Decatur & Tecumseh, was being constructed in northern Alabama to overcome the obstructions to freight traffic caused by the now well-known Muscle Shoals in the Tennessee River. This railroad was patterned after a railroad at Mauch Chunk, Pa., which was used for hauling anthracite from the Panther Creek valley. The Alabama railroad, which required about four years to complete, was 46 miles long and was used solely for the transportation of cotton. Although it was a failure, it demonstrated the practicability of the undertaking, and the succeeding railroads, which were begun in 1834, 1848, 1852, and 1853, added immeasurably to the development of the coal resources of the state. Between the years 1830 and 1860, practically all the coal mined in the state was dug from the outcrop near the river or from the river beds, and shipped by boat to Mobile. Transporting coal down the Warrior River was an undertaking of great risk, required much skill, and frequently had heavy losses. It is recorded that this coal was sold to the gas company in Mobile in 1844; it was most likely mined from the Black Creek Seam. In 1914, on the completion of Lock 17, the Warrior River became a navigable stream from 9 miles above Cordova, Ala., to Mobile and offers a great opportunity for the future development of the coal resources of the state. Coke for foundry use was first made in Alabama in 1855. It was 21 years later, however, in 1876, that pig iron was made from Alabama ore with Alabama coal.

Jan 1, 1925

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

UNIT OF MEASURE ABBREVIATIONS USED IN MFIRE FT foot FT3/MIN cubic foot per minute LBM•MIN2/FT4 pound mass times minutes squared over feet to the fourth FT2/HR square feet per hour BTU/HR*FT*F British thermal unit divided by hours times fimes feet times degree Fahrenheit IN W G inches water gage FT3/MIN cubic feet per minute FT2 square feet FT3 cubic feet LBM, pound mass F Fahrenheit IN W G /CFM2 inches water gage per cubic foot per minute squared PERCENTAGE percent BTU/MIN British thermal unit per minute MFIRE BAT PROGRAM cls echo off echo MFIRE activated mfire0 echo Wait a moment for loading the program if EXIST zheng chg mfirel if EXIST zheng chg mfire2 if EXIST zheng chg mfire1 if EXIST zheng chg erase zheng chg if EXIST hang chg erase hang chg if EXIST yunzhi fan copy yaodong.ion+yunzhi fan yaodong ion if EXIST yunzhi fan erase yunzhi fan if EXIST xintan chg copy yaodong xin+xintan chg yaodong ion if EXIST xintan chg erase xintan chg if EXIST yaodong xin copy yaodong.xin mfire out if EXIST yaodong.xin erase yaodong.xin if EXIST net erase net echo Your output is saved in file MFIRE OUT MFIRE0 FOR PROGRAM CHARACTER•50 A OPEN (10,FILE='NET',STATUS='UNKNOWN',FORM='UNFORMATTED') NETWW=0 WRITE (10) NETWW OPEN (21,FILE='ZHENG CHG',STATUS='UNKNOWN',FORM='UNFORMATTED') A=) ' B=0.0 WRITE (21) A WRITE (21) A,B

Jan 1, 1990

By Arsalan Talebzadeh

Construction -Surface ?First two intake fans constructed in 2007; third fan added in 2008 to reduce resistance in the system. 450 HP fans. ?Excavation for exhaust fans started in 2008. ?In parallel with underground construction in preparation for the changeover. ?Bulkhead in place prior to completion/ commissioning of

Oct 1, 2010

By Walter H. Bruckner, George B. Clark

SINCE the end of World War II interest has been increasing in the use of shaped charges in the mining industry and in other industries using explosives for blasting purposes. Shaped charges employ the principle known as the "Munroe effect," which was discovered by Charles E. Munroe more than 50 years ago (in 1888). Details of their design have been explained e1sewhere.l,2,3 Fig I shows the essential features of design of two types of shaped charges (with conical and hemispherical cavities) and a schematic sketch of their action upon detonation. The following discussion deals with the behavior of the metal in the cavity liners when they are subjected to intense pressures exerted when the explosive charge is detonated. Among the conclusions reached in research on shaped explosive charges, the following have been established concerning cavity liners: 1,2 I. The optimum wall thickness of a conical cavity liner is dependent upon the apex angle of the cone as well as on the base diameter of the charge. Acute apex angles require thinner walls for optimum performance and more obtuse angles require thicker walls for the same base diameter. 2. Cones were more effective in forming a penetrating jet when the walls were tapered; i.e., the thickness of the wall of the cone increased from the apex down. 3. The physical and mechanical proper- ties of metals have a marked effect upon their performance as cavity-liner material. Boiling point, ductility, malleability, tensile strength, and hardness are among the properties that influence the effectiveness of a metal used as a cavity liner. Lead, for example, makes a wide, flat crater in steel plates. Aluminum makes a deeper crater than lead, and an aluminum alloy having a high tensile strength makes a deeper hole, but slightly smaller in diameter. Cast iron makes a deep, narrow hole. These findings, together with the following analysis under Metallographic Survey of Slug, offer solutions to many of the problems involved in solving the mechanism of the formation of Munroe jets. It has been fairly well established that cavity liners collapse in a manner similar to that indicated in Fig 2. Conical liners are known to collapse upon themselves while hemispherical liners are believed to turn inside out in the process of jet formation. The first has been definitely proved by recovery of collapsed portions of cones, while liners from partly detonated charges show that hemispheres may turn inside out. Fig 3 shows a sketch of a recovered slug from a 6-in. shaped charge using a 45° cone made of cast iron. (This size of charge drilled holes up to 3 ft in depth in solid granodiorite.)

Jan 1, 1947

By C. H. Li, R. J. Stokes, T. L. Johnson

The effect of alumina particles on the nucleation and growth of cracks through a silver- chloride matrzx has been investigated. It has been found possible to promote fibrous cracking in dispersion-strengthened silver, chloride under notch-impact conditions at temperatures at which silver chloride alone cleaves brittlely The modification) of fracture beIzavzor is thought to be due to the relaxation of hydrostatrc stress beneath a notch by the nucleation of cavities near alumina particles. In recent years, composite or dispersion-strengthened materials have been studied primarily to understand their high resistance to plastic flow particularly at elevated temperatures. Dislocation models have been developed with which it is possible to deduce with fair success the effects of interparticle distance, particle size, temperature, upon yielding and creep behavior.l-4 Much less attention has been paid to the fracture behavior of these materials (with the notable exception of common structural steels) and little is known experimentally about the manner in which inclusions affect the nucleation and growth of cracks through a matrix. Nevertheless a beginning has been made in connection with fibrous cracking in ductile matrices where inclusions appear to play an essential ro1e.5-7 During the severe localized plastic deformation which accompanies necking in a tensile test, cavities are believed to develop at inclusions; these cavities subsequently grow and coalesce by plastic flow until separation is complete. It is of interest to consider whether inclusions can affect fracture behavior under loading conditions which restrict the plasticity of the matrix itself (for example, cleavage under conditions of a high imposed strain rate at low temperatures). It is particularly interesting to study these effects in a solid which shows a spectrum of behavior ranging from fully ductile to semi-brittle behavior. Such a solid is silver chloride whose mechanical behavior depends sensitively upon temperature and strain rate.'," The present paper is concerned with a study of the influence of inclusions (in the form of alumina particles) on the fracture behavior of silver chloride loaded uniaxially at low strain rates at room temper- ature and also under notch impact conditions over a wide range of temperature. In particular, it will be shown that the alumina particles can exert a startling effect on the ductile-brittle transition temperature of notched silver chloride and that the magnitude and nature of the effect depends upon both the quantity of alumina and the shape of the alumina particles. 1. EXPERIMENTAL PROCEDURE 1.1 Materials Used. Silver chloride powder of analytical reagent (AR) quality having an average particle size 6 was supplied by the Mallinckrodt Chemical Works (st. Louis, MO.). Acid washed 900 mesh alumina powder, designated A38-900, was supplied by the Norton Co. (Cambridge, Mass.). This powder was added to silver chloride in two forms: a) the as-received condition in which the individual particles were of random irregular shape; their statistical average size was 7; b) in a condition in which each particle was spherically shaped by a fusion technique. In this case, the statistical average particle size determined with the optical microscope was approximately the same (about 5p) but electron micrographic evidence indicated that many ultra fine particles were present in the spheroidized powder. 1.2 Preparation of Composite Materials. Silver chloride-alumina composites containing 2.5, 5, and 15 pct by volume of alumina were produced by the extrusion of mechanically mixed powders blended in a ball mill for 24 hr at room temperature. The mixtures were compacted at 50,000 psi at room temperature in the form of billets 3/4 in. in diameter and 1 in. long which were then extruded with a 16:l reduction ratio at 370°C through a radius-type steel die having a 5 deg lead-in angle. An extrusion temperature of 370°C was selected to ensure that all composites had sufficient plasticity to be extruded. Apart from this general requirement, the choice was arbitrary. 1.3 Microstructure of Composites. Attempts were made to check the distribution of alumina metallo-graphically by polishing transverse and longitudinal sections of the extruded rod. Specimens were wet-ground to 600 emery paper and lapped successively with 5 and 0.25-p grades of diamond paste. They were etched for 10 sec in 10 pct sodium thiosulfate solution and lightly polished in concentrated ammonium hydroxide. The most effective way to render the alumina particles and grain boundaries visible was to radiate the surface with intense white light to decorate the grain boundaries and the particle-matrix interfaces photolytically.

Jan 1, 1962

By Charles T. Malcomson

In the United States, improvements in methods of combustion have made possible the use of the smaller sizes of anthracite. This coal is now being reclaimed from the culm banks accumulated by the miners in the more prodigal years. To-day the freshly mined "slush" is segrega,ted and stored against the time when, through briquetting or some other means, it may be utilized as a commercial fuel. For many years Europe has achieved enviable results in the conservation of her small coal by briquetting. This profitable industry, first placed on a commercial basis in France in 1842, has grown to such magnitude that the production during 1913 exceeded 36,000,000 short tons. Briquets produced in Great Britain are used principally for steam purposes and the greater part of the output is either exported or taken by the Admiralty. On the Continent the briquets are sold in all branches of the coal trade. The French railways consume from 16 to 40 per cent. of their fuel in briquet form, and in Germany the lignite briquets (of which 20,000,000 tons were produced in 1913) are as familiar and interesting to the American traveler as the huge porcelain stoves in which they are burned. It is not strange, therefore, that aggressive and far-sighted promoters heralded this means of converting our ubiquitous coal waste into revenue. To the superficial student the briquetting process seemed so simple as to make success easy. It is for this reason principally that the path of the industry in America has been strewn with failures. The rash enthusiast had either not worked out the mechanical problems involved or had failed to grasp the local conditions under which the briquets must be made and sold. It may be confidently stated, however, that in spite of the many vicissitudes through which it has passed, coal briquetting is now an accomplished economic success in this country, and as a profitable adjunct to the coal industry it has come to stay. Several valuable contributions relating to coal briquetting are found in the Transactions. Charles Dorrance, Jr., has sketched briefly the history of the anthracite briquetting plants from the time of Loiseau's pioneer plant down to that of the Lehigh Coal & Navigation Co. at Lans-ford. Since then this phase of the industry has remained practically at

Jan 1, 1915