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By Jorge Alberto Soares Tenório, Romano Espinosa, Felipe Fardin Grillo, José Roberto de Oliveira, Denise Crocce

"The aim of this work was evaluation of the recovery of Zn and Fe of the EAFD added to the hot metal in the form of briquette at temperature of 1500°C. The EAFD was agglomerated by cold briquetting and introduced in the hot metal. This study utilized a bench-scale equipment to melt, during this process to kept a flow rate of inert gas above the bath. Were collected periodically metal samples and the samples were analyzed for determination of the content of total silicon and carbon by chemical analysis. Zinc oxide, zinc ferrite and other oxides were reduced and were volatized and collected by a cleaning system of dust (baghouse) located on top of the oven. More than 98% of iron were recovered from EAFD during the test. It was possible to produce a dust containing about 68% zinc by means of adding of EAFD.IntroductionIn the first semester of 2010, steel production was about 706 million tons, 27.9 % more than in the first half of 2009. Not a significantly increase if 2010 data is compared with the first semester of 2007 (only 7.2 % higher), before the world’s economic crises. Steel production is divided into two main routes. The first one, and most used, is the Basic Oxygen Furnace Process (BOF process), which in 2008 accounted for approximately 67.1 % of steel production. The second route is carried out in the Electric Arc Furnace (EAF) that in 2008 represented 30.6 % [1 ].Electric arc furnace dust (EAFD) is a solid waste generated during the steel making process. It is classi?ed according to NBR 10004 as dangerous solid waste-class I, because the elements Pb e Cd leach in water exceeding the maximum limits permitted by the NBR 10004 [2 ]."

Jan 1, 2012

By R. E. Sundell, S. M. Correa

"A mathematical model is developed for the fluid flow in tungsten-inert gas weld pools. The fluid is taken to be incompressible, viscous, electrically conducting, and confined within a pool of specified shape. The flow is driven by surface-tension gradient (thermocapillary), electromagnetic, and buoyancy forces generally in this order of importance. Analysis indicates that the electromagnetic field may be calculated a priori and so decoupled from the nonlinear fluid mechanics and heat-transfer problem. The resulting set of equations is solved numerically by a line relaxation process. Computational errors caused by truncation in finite-difference schemes and by inadequate grid distributions are considered. The model is used to study several cases of differing heat and current input to the pool with and without surfactant-induced thermocapillary forces. The principal conclusions are that the thermocapillary flow, when present, is dominant with surface velocities on the order of 1 m/s. The heat transfer, as deduced from isotherms within the pool, is crucially dependent on the flow. Also, flow velocities and weld-pool surface temperatures were measuredand agree well with the model.2. IntroductionThe requirements of improved control and of automation in the TIG (tungsten-inert gas) welding process have led to the development of mathematical models for the heat transfer to the workpiece. It is now widely recognized that the fluid flow in weld pools sufficiently distorts the conduction heat transfer pattern to warrant inclusion in a process model. The experiments of Woods and Milner (1), among others, demonstrated that TIG weld pools could be driven by the electromagnetic J x B body forces present, J being the current distribution and B the induced magnetic field. Atthey (2) calculated that in typical pools the buoyancy force was about an order of magnitude less important - despite the large temperature gradients present - and neglected it in a computational study of the magnetohydrodynamic (MHD) flow. This work also reviewed many earlier studies of MHD flow caused by a source of current at a fluid surface, including analytical studies by Shercliffe (3), Sozou (4), and Sozou and Pickering (5), and a numerical study by Andrews and Craine (6). These works establish the importance of the electromagnetic force in the weld-pool flow."

Jan 1, 1986

By W. E. Wallace, V. Castranova, F. Saus, D. Bates, C. A. Hill, V. Vallyathan, M. J. Keane

"Two in vitro systems are being developed to model initial stages in the interaction of respired dusts with the acinar region of the lung. Incubation of quartz and kaolin with dipalmitoyl glycerophosphorylcholine, a major component of pulmonary surfactant, suppresses the prompt C)1otoxicity of both dusts as measured by in vitro enzyme release from pulmonary macrophages or assay by erythrocyte hemolysis. Additional data is presented to quantitate the detoxification of quartz and kaolin by dipalmitoyl lecithin. Subsequent incubation of lecithin treated dusts with phospholipase enzymes results in partial to complete restoration of the assayed cytotoxic potentials, dependent on the lipase activity applied, the incubation time, and the mineral. Restored cytotoxic potential is due to removal of the prophylactic lecithin surface coating and/or due to residual lysolecithin which is produced by the partial enzymatic digestion of lecithin. Data is presented on the contribution of each mechanism to the restored toxicity. Again, this is dependent on the mineral used, the lipase activity applied, and digestion time. Additionally, a system is under development to challenge pulmonary macrophages in culture with native and surfactant treated dusts. A preliminary test of the dipalmitoyl lecithin - quartz rabbit pulmonary macrophage system is presented to illustrate the method.IntroductionRespirable quartz dust exposure is known to cause librotic lung disease; respirable clay dust exposure is less likely to do so as indicated by epidemiologic data on occupational exposures and by animal model studiesP·7) The hypothesis that damage to pulmonary macrophages in the acinar region of the lung by respired dusts is an early event in the disease process requires consideration because kaolin clay and quartz dusts are comparably cytotoxic to pulmonary macrophages in vitro.(3•9)"

Mar 1, 1989

By Emad Farouz, Roger Failmezger

"The proposed reconstruction of I-75 downtown consists of widening an approximately 2.46 Km section of IR-75 through the northern section of downtown Dayton, OH, USA. Bridge B-13 is a 9-span continuos prestressed concrete I-beam, 319.0-meter (1,048-foot) long bridge with a stub abutment on MSE walls for the rear abutment, and a stub abutment with spill-through slopes for the forward abutment. The piers in the river were located parallel to the Great Miami River, and are full-height reinforced concrete wallsPRESSUREMETER TEST PROCEDUREThe driller advanced either casing or augers approximately 1 meter above the pressuremeter test. Steel casing was used to advance borings performed in the river, and augers were used for borings on land. Mud rotary drilling with a large diameter roller bit was used to remove all of the gravel and cobble fragments inside the casing or augers.At the pressuremeter test elevation the driller used a 63.5-mm (2.5-inch) carbide button bi-cone bit, using a rotation rate of about 60 rpm, a mud fl ow rate of about 10 gallons per minute (40 liters per minute), and an advance rate of 6 to 10 minutes per meter (2 to 3 minutes per foot). To minimize vibrations, advance rates were slower where excessive cobbles were encountered. The 63.5-mm (2.5-inch) O.D. slotted casing pressuremeter was lowered to the test elevation, often requiring either pushing or hammering into the test zone. We believe that the test zone was not perfectly straight, or that gravel or cobble fragments jutted into the test zone and had to be displaced to advance the pressuremeter into the test zone. The slotted casing prevented membrane damage during insertion. A photograph of the slotted casing being lowered into the borehole is shown below.The pressuremeter was calibrated for system compressibility and membrane resistance. At full expansion of 800 cm3, the membrane resistance of the slotted casing was about 2.5 bars.Strain-controlled tests were performed using a Texam control unit with a monocell probe. Volume increments of 20 cm3 were injected into the probe and corresponding pressures were measured. Near the end of the elastic portion of the test, an unload-reload cycle was done. A creep test was performed for 10 minutes at the next volume increment. The test continued until either 800 cm3 were injected or the membrane burst."

Jan 1, 2007

By H. N. Eavenson

The eleven mines of the United States Coal and Coke Co. in the Pocahontas coal field are situated in McDowell County, W. Va., which is a mountainous region. The valleys rarely exceed 200 ft. (60 m.) in width, the hillsides slope from 25°to 33°, and the tops, from 600 to 900 ft. above the valleys, carry practically no level land. At least 80 per cent. of the area is covered with timber. All the workings are drift mines; and while the average grades of the seams worked are ample for drainage, local dips and swamps necessitate the use of a large number of local pumps or of numerous drainage ditches to keep the mines free from water during heavy rains. The water handled in any mine is not great, compared with the coal output, and usually causes little trouble except during extremely wet periods. In new workings, the water encountered, except in rare cases, is trifling; it is only after rib drawing has started and the surface has been broken that water troubles begin. The strata overlying the coal are sandstone, shales, and slates; as the soil is thin and sandy, it does not tend to puddle and stop the cracks, which remain open for a long time. As mining progresses and the robbed area increases, the broken area becomes larger, increasing the openings into the mined territory. The cover over the robbed portions of the mines varies from 30 to 750 ft. (9 to 228 m.). When the ground is saturated, considerable water finds its way into the mines the day after a heavy rainfall and for three or four days it tends to fill the low places, wash the tracks, etc. and unless from three to four times as many pumps are installed as are normally needed, considerable output is lost. In most cases the water will flow from the mines, and the obvious solution is to provide drainage ditches of ample size to carry the maximum flow expected, so that the inflow will have no opportunity to flood the working places. Laying out the drainage headings on the proper average grades was an easy matter but where blasting was necessary to provide uniform grades, as was frequently the case, it was important that the maximum flow to be expected and the size of ditches to be provided should be known so that only rock work necessary to provide proper drainage

Jan 1, 1922

By Arthur F. Taggart, A. W. Thomas, T.C. Fitt

It was noticed early by operators that high recoveries and flocculation of the sulphide minerals were closely correlated in agitation-froth flotation. Later, this readily visible flocculation was found almost invariably to be due to the binding together of the oiled sulphides by minute air bubbles, and is now known to be characteristic of pulps in which at least one of the mineral species is coated with an insoluble collecting oil. In 1930 it was reported1 that in differential flotation a correlation exists between Brownian movement of particles in the pulp and their nonfloatability, and that Brownian movement and dispersion are likewise correlated, whence it would appear to follow that dispersion of a mineral particle in a flotation pulp denotes a particle condition unfavorable to flotation. In 1934 it was postulated2 that Brownian movement, dispersion and nonfloatability all flow from the condition of the surface of the dispersed particles. It was also postulated at that time that the surfaces of dispersed particles are ionized, the ionized compound being a product of reaction between a component of the particle and a component of the pulp, of a mass solubility of the general order of a fraction of a milligram to I 5 to 20 mg. per liter. It was then further asserted, and has since been confirmed by Bankoff,3 that sulphides so conditioned with soluble collectors as to be floatable flocculate without the intervention of air bubbles as binding media. The present paper comprises an inquiry into the nature of the bound and counter ions in zinc sulphide dispersed by sodium arsenate. A part of its findings was mentioned in the 1934 paper above cited.= The tests show that: I. When powdered granular zinc sulphide is immersed in aqueous solutions of sodium arsenate, arsenate ion is abstracted from solution and anchored to the solid surface, while sulphate and lower sulphoxy ions are concurrently displaced therefrom in substantially stoichiometric quantities. 2. The ion counterbalancing the anchored arsenate ion is zinc. 3. Dispersion and Brownian movement of zinc sulphide are concurrently maxima at an arsenate-ion concentration lying between 0.01 and 0.001-molar sodium arsenate. 4. Any condition or reaction that tends. to remove the zinc arsenate coating from the zinc sulphide particles decreases dispersion and Brownian movement concurrently. Experimental Three samples of zinc sulphide were used. Lot I was C.P. zinc sulphide, washed well be~ond absence of chloride, as shown by test with silver ion. Lot 2 was prepared by precipitation from hydrochloric acid solution of arsenic-free zinc, and was washed as lot I. Lot 3 was prepared by heating a portion of lot 2 in absence of air at 1200° to r300°C. for one hour."

Jan 1, 1943

By Arthur F. Taggart, T. C. Fitt, A. W. Thomas

It was noticed early by operators that high recoveries and flocculation of the sulphide minerals were closely correlated in agitation-froth flotation. Later, this readily visible flocculation was found almost invariably to be due to the binding together of the oiled sulphides by minute air bubbles, and is now known to be characteristic of pulps in which at least one of the mineral species is coated with an insoluble collecting oil. In 1930 it was reported1 that in differential flotation a correlation exists between Brownian movement of particles in the pulp and their nonfloatability, and that Brownian movement and dispersion are likewise correlated, whence it would appear to follow that dispersion of a mineral particle in a flotation pulp denotes a particle condition unfavorable to flotation. In 1934 it was postulated2 that Brownian movement, dispersion and nonfloatability all flow from the condition of the surface of the dispersed particles. It was also postulated at that time that the surfaces of dispersed particles are ionized, the ionized compound being a product of reaction between a component of the particle and a component of the pulp, of a mass solubility of the general order of a fraction of a milligram to I 5 to 20 mg. per liter. It was then further asserted, and has since been confirmed by Bankoff,3 that sulphides so conditioned with soluble collectors as to be floatable flocculate without the intervention of air bubbles as binding media. The present paper comprises an inquiry into the nature of the bound and counter ions in zinc sulphide dispersed by sodium arsenate. A part of its findings was mentioned in the 1934 paper above cited.= The tests show that: I. When powdered granular zinc sulphide is immersed in aqueous solutions of sodium arsenate, arsenate ion is abstracted from solution and anchored to the solid surface, while sulphate and lower sulphoxy ions are concurrently displaced therefrom in substantially stoichiometric quantities. 2. The ion counterbalancing the anchored arsenate ion is zinc. 3. Dispersion and Brownian movement of zinc sulphide are concurrently maxima at an arsenate-ion concentration lying between 0.01 and 0.001-molar sodium arsenate. 4. Any condition or reaction that tends. to remove the zinc arsenate coating from the zinc sulphide particles decreases dispersion and Brownian movement concurrently. Experimental Three samples of zinc sulphide were used. Lot I was C.P. zinc sulphide, washed well be~ond absence of chloride, as shown by test with silver ion. Lot 2 was prepared by precipitation from hydrochloric acid solution of arsenic-free zinc, and was washed as lot I. Lot 3 was prepared by heating a portion of lot 2 in absence of air at 1200° to r300°C. for one hour."

Jan 1, 1943

By Bucknell WR, Clarke DE

The paper provides a company's view of the relative merits of various valuation methods and outlines the basic approach it takes to the valuation of an exploration property. The negotiating process and methods of acquiring an interest in an exploration property is discussed The valuation methods discussed are: 1. Exploration Expenditure. 2. Real Estate. 3. Joint Venture Terms. 4. Rule of Thumb. 5. Net Present Value - Discounted Cash Flow. 6. Geoengineering.

Jan 1, 1994

By Frank Firmstone

IN 1871, two furnaces at the Glendon Iron Works, which had been blown out on account of the "coal strike," were altered from the open-top plan with side flues for collecting the gas, to closed tops with cup and cone. In one furnace the suppression of the side flues permitted a considerable alteration in the profile, but in the other (No. 5) no change in this respect was made; the side flues were simply bricked up and new ones cut through the sides close to the top. This furnace was in blast over four years, and we can, therefore, form a pretty good idea of the effect of the alterations on the furnace process. The principal dimensions are; Height 72'; greatest diameter, 18'; diameter at tuyeres, 8'; diameter of top, 10'; diameter at stock line (point at which the top of the materials is kept), 11'; cubic contents, 11,900 cubic feet. The table below shows the average results for periods of twenty-six weeks each. 1st, of the open-topped furnace; 2d, of the furnace with the first charger used, which was an ordinary cup and cone (diameter of cone 5' 2") 3d, with the charger used ever since, a "double" cone 7' 5" diameter outside, having a central opening 3' in diameter. The diagram (Plate II) shows the daily variations, in the grade of the irons for the same periods.* * In calculating the average grade of each day's iron, each twelve hours was taken by itself whenever more than two kinds of iron were made in the 24 hours, and the diagram drawn accordingly. By counting, it will be found that there were more such days with the single cone than with the "double" cone, and more with this than with the open top. † Anthracite.

Jan 1, 1876

By Zhong Juya, Wang Yong, Guo Xueyi, Song Yu, Tian qinghua

"In this work, the flow of zinc in China, 2004, was traced within the STAF model, and the situation of production, consumption and recycling of zinc resources in China were introduced. The SFA is performed on zinc flows during its one year life cycle in detail. The result reveals that China produces and utilizes a large amount of zinc, while the efficiency of renewable zinc resources is still relatively lower. As one of the biggest producer and consumer of zinc in the world, China is facing a severe depletion of zinc resources. How to increase the resource efficiency is a significant issue for zinc industry of China. Based on the result, several advices were proposed in the paper, aiming to contribute important reference information for the industrial metabolism and resource management and recycling of zinc industry in China. IntroductionZinc is one of the important metals in national economic development in China; it has good conductivity and corrosion resistance, with high scalability when heated to 100 ~105_. Zinc is mainly used for galvanized zinc industry, as the coating of steel and various parts, and it has also been applied to the manufacture of brass, bronze and corrosion-resistant alloys, which are widely used in machinery manufacturing, printing, national defense and so on. In addition, zinc compounds are utilized in various fields, for example, ZnO is used for infiltration wood, paper, rubber, paints, etc.; ZnSO4 for leather, ceramics, textiles, medicine, etc.; ZnCl2 for infiltration wood; ZnS2O4 and Zn (HSO2 • CH2O) 2 for the paper and textile bleaching, etc. [1]. The extensive use and consumption of zinc in industrial production and social life promot the rapid development of zinc industry, which made zinc the third largest non-ferrous metals in the world."

Jan 1, 2008

By Paul Sands

Single- and two-stage tests were made with 6-inch, coal-cleaning hydrocyclones to determine the effect of hydrocyclone geometry, operating conditions, and feed composition on performance. Most of the testing was conducted in an open-circuit pilot plant that had a maximum capacity of about 9 tons per hour. The coals used in the investigation had top sizes of 1/4 inch and 28 mesh. Considerable latitude was found in the range of geometry variables that could be used without affecting performance adversely, although a certain minimum ratio of overflow to underflow openings had to be maintained for best operation. Two-stage cleaning proved distinctly better than operation with a single hydrocyclone, because clean coal lost in the refuse product of the primary unit can be partly recovered in the secondary. There is an unusually great difference in the specific gravities at which the individual sizes of the feed are separated in the hydrocyclone. This militates against high efficiency because maximum yield occurs when all sizes are cleaned at the same specific gravity. The size composition of the feed and, more particularly, the size composition of the impurity have a greater influence on the efficiency attainable in the hydrocyclone than in most other types of fine-coal cleaners.

Jan 1, 1968

By Emad Farouz, Roger Failmezger

"The proposed reconstruction of I-75 downtown consists of widening an approximately 2.46 Km section of IR-75 through the northern section of downtown Dayton, OH, USA. Bridge B-13 is a 9-span continuos prestressed concrete I-beam, 319.0-meter (1,048-foot) long bridge with a stub abutment on MSE walls for the rear abutment, and a stub abutment with spill-through slopes for the forward abutment. The piers in the river were located parallel to the Great Miami River, and are full-height reinforced concrete walls. PRESSUREMETER TEST PROCEDUREThe driller advanced either casing or augers approximately 1 meter above the pressuremeter test. Steel casing was used to advance borings performed in the river, and augers were used for borings on land. Mud rotary drilling with a large diameter roller bit was used to remove all of the gravel and cobble fragments inside the casing or augers.At the pressuremeter test elevation the driller used a 63.5-mm (2.5-inch) carbide button bi-cone bit, using a rotation rate of about 60 rpm, a mud fl ow rate of about 10 gallons per minute (40 liters per minute), and an advance rate of 6 to 10 minutes per meter (2 to 3 minutes per foot). To minimize vibrations, advance rates were slower where excessive cobbles were encountered. The 63.5-mm (2.5-inch) O.D. slotted casing pressuremeter was lowered to the test elevation, often requiring either pushing or hammering into the test zone. We believe that the test zone was not perfectly straight, or that gravel or cobble fragments jutted into the test zone and had to be displaced to advance the pressuremeter into the test zone. The slotted casing prevented membrane damage during insertion. A photograph of the slotted casing being lowered into the borehole is shown below.The pressuremeter was calibrated for system compressibility and membrane resistance. At full expansion of 800 cm3, the membrane resistance of the slotted casing was about 2.5 bars.Strain-controlled tests were performed using a Texam control unit with a monocell probe. Volume increments of 20 cm3 were injected into the probe and corresponding pressures were measured. Near the end of the elastic portion of the test, an unload-reload cycle was done. A creep test was performed for 10 minutes at the next volume increment. The test continued until either 800 cm3 were injected or the membrane burst."

Jan 1, 2007

By Werner Bilfinger, Claudio Nahas, Marcelo Waimberg

"INTRODUCTION The so called Porto Maravilha Project consists of the re-urbanization of a 500 ha area in the Rio de Janeiro port region. Several changes in local infrastructure are being implemented, including a significant change in the road system, with the demolition of the former “Via Perimetral” viaduct and construction of 4 new tunnels: • Saúde tunnel - 35 m long (Waimberg et al, 2014); • “Binária tunnel” - 1012 m long; • “Via Expressa” twin tunnels - 1850 m long each way. The tunnels were excavated almost completely in rock using conventional drill and blast methodology and only some short stretches in weathered rock, associated to faults zones, residual soils and marine sediments close to the tunnel portals. During excavation of access shaft and “Via Expressa” and “Binária” tunnels significant ground settlements as well as settlements of buildings founded both on shallow and deep foundations were measured. These values could not be associated to conventional tunneling induced settlement troughs. This paper focuses on the “Via Expressa” tunnels, presenting a brief description of the project as a whole, its geological and geotechnical background, monitoring results, and a discussion of possible causes of the measured settlements. PROJECT DESCRIPTION The Porto Maravilha Project is an integrated multidisciplinary action on behalf of the Rio de Janeiro city council with support from the State and Federal Governments. In addition to creating new conditions for working, housing, transport, culture and leisure for the resident population, it also promotes expressive economic development in the region (Portonovo, 2015). Porto Maravilha Project is carrying out actions for the recovery of the region’s historical heritage, as well as promoting the population´s social and economic development. One of the main benefits of the Porto Maravilha Project is the construction of the new traffic system in the port area, consisting of the Express and Binário roadways. The new project, which will replace the current Perimetral Rodrigues Alves viaduct system, will increase traffic flow capacity by 27%."

Jan 1, 2016

By G. M. Wilemon, Swanton. R. G.

The Bureau of Mines is investigating the leaching of phosphate values from Florida phosphatic clay wastes using sulfuric acid (H2SO4) as the leaching agent and methanol as the solvent. Acid-alcohol leaching studies were done using research-grade apatite to investigate potential causes of flow extractions. It was found that a barrier layer formed on the surface of the apatite. Initial discovery of the barrier layer was made by analyzing pure apatite samples before and after leaching using an optical microscope. Subsequent Fourier Transform Infrared (FT-IR) analyses proved the coating was calcium sulfate hemihydrate (CaSO4•1/2H2O) and that unreacted apatite existed beneath the coating. Scanning electron microscope (SEM) photographs depict the CaSO4• 1 /2H20 morphology as long slender crystals adhering to the apatite surface. It was also shown that grinding the leached tailings and leaching again in the H2SO4-methanol system resulted in additional phosphate extraction.

Jan 1, 1992

By B Indraratna, A Dey

The surface geometry of a rock bolt plays a very important role in the rock/resin/bolt load transfer mechanism. Very little work has so far been reported on the influence of the bolt surface geometry on the bolt/resin interface failure mechanism. This paper examines the behaviour of bolt surface roughness under constant normal stiffness condition in the laboratory. To study the shear behaviour of the bolt/resin interface a series of shear tests with an initial normal stress between 0.1 to 7.5 MPa has been conducted on the flattened bolt surface of two most popular bolt types currently being used in Australia. Bolts with deeper ribs offered better shear resistance at low initial normal stress conditions whereas bolts with shallow and closer ribs offered better shear resistance at high normal stress conditions. The maximum dilation occurred at a shear displacement of 60 per cent of the rib spacing irrespective of the bolt type and depth of the rib.

Jan 1, 2000

By Henry Freiser

For the last several years, a systematic investigation of the equilibrium extraction behavior of selective tervalent lanthanides with representative chelating extractions of a variety of chelating agent families has been undertaken for the purpose of learning how to obtain chelating extractants of improved selectivity for separating individual lanthanide ions. The equilibrium extraction data (expressed as log Kex) for each reagent system are linearly related to the reciprocal ionic radius of the tervalent lanthanide ions. The role of adduct formation, steric hindrance, as well as the nature of the bonding atom in the chelate ring, represent some of the factors affecting selectivity arising out of our database of over 200 individual extraction systems, which will be discussed.

Jan 1, 1989

By H. H. Kellogg

Equations representing the standard free energy of formation as a function of temperature, for thirty metallic chlorides, are presented and plotted on a free-energy vs. temperature diagram. The use of these data for calculations on reduction of metallic chlorides, refining of metals with chlorine, and chlorination of metallic oxides and sulphides is illustrated. CHLORINE metallurgy' has attracted metallur- gists for more than a century because the unusual properties of the metallic chlorides—low melting point, high volatility, and ease of formation from the oxides—make possible many useful extractive processes. Interest in chlorine processes is undergoing a renaissance due to present availability of chlorine at relatively low prices, and to recent advances in technology. During the present century there have accumulated a considerable number of reliable values of the thermodynamic constants for the metals and their chlorides. These data permit the calculation of free-energy equations for many metallurgically important reactions. Consideration of free-energy values makes possible certain predictions of the direction and extent of a given reaction, as well as the effect of temperature, pressure, and composition upon the result. Reaction rate, although not predictable from free-energy data, is usually sufficiently great at elevated temperatures that diffusion of the reactants and products to and from the zone of reaction determines the actual rate. Thus, if the free-energy indication is favorable, the chances are good that a high temperature metallurgical reaction will proceed at a reasonable rate, if adequate provision for rapid diffusion has been made. This paper presents standard free-energy equations for a number of metallic chlorides, based on data which are scattered throughout the literature. The equations are presented in a form that simplifies their use, and typical examples are given of the application of free-energy data to metallurgical processes. Free Energy of Reaction The free-energy change (AG) of a reaction is the true measure of the "driving force" of the reaction under a given set of conditions, and this is related to the standard free-energy change (AGO) of the reaction as follows: For the reaction: bB + cC = dD + eE ?G = ?G°+RTln ADd. AEA / ABb. ACc where A, = activity of constituent (i) T = absolute temperature, OK R = gas constant The criterion of a spontaneous reaction from left to right, at constant temperature and pressure, is a negative value for the free-energy change (?G). The standard free energy of the reaction is equal to the free energy of the reaction when all the reactants and products are at unit activity, since under these conditions the second term on the right-hand side of eq 1 is equal to zero. The concept of activity is treated fully in many textbooks on chemical thermodynamics1 and in a recent article by Chipman.2 Briefly, the activity (A,) of a constituent (i) is a measure of the reactivity of this constituent relative to its reactivity in some arbitrary standard state. For liquids and solids the standard state most often used is the pure liquid or solid constituent. Thus the activity of a pure liquid or solid in a metallurgical reaction is equal to unity. Gases under moderate pressure and at elevated temperatures behave very nearly as 'idea1 gases,' and the standard state is chosen as the gas at 1 atm pressure. The activity of an ideal gas is therefore equal to its partial pressure, and this relation is sufficiently exact for real gases in most metallurgical reactions. For a liquid or solid solution there is in general no simple way to express the activity of a constituent as a function of its concentration, and activity must be determined by experiment. A few solutions follow a so-called 'ideal' behavior, and if the pure constituent is chosen as the standard state, the activity of a constituent in an ideal solution becomes equal to its mol fraction. When a reaction reaches a state of thermodynamic equilibrium at constant temperature and pressure, AG becomes equal to zero and eq 1 reduces to: [ADd . AEe ?G°=RTln Abb ¦ Ac c equilibrium [2] The brackets surrounding the activity term are used to emphasize that each of the activities is an activity under equilibrium conditions—not just any arbitrarily assigned value. The bracketed term is the equilibrium constant (K) of the reaction. Eq 2 makes possible the calculation of equilibrium activities for a given reaction, if AGO is known at the desired temperature. The standard free-energy equations presented in this paper were calculated from the fundamental thermodynamic values of enthalpy of formation at 298°K (AH°,), standard entropy at 298°K (So298), heat capacity as a function of temperature (Cp), and enthalpies of transition, fusion, vaporization, and sublimation for the various constituents. Where possible the data reported in the recent "Selected Values of Chemical Thermodynamic Properties," published by the Bureau of Standards," were used. A large number of data came from the publications

Jan 1, 1951

By NATHANIEI HERZ

(Cleveland Meeting, October, 1912.) THE formula very frequently used for computing the economical size of pipe to transmit compressed air is that of D'Arcy, as follows: d5(p1-p2)/w1l D-c w11 Where, D = the volume of compressed air delivered in cubic feet per minute,-at the final pressure. c = an experimental coefficient determined for the various sizes of pipe. d = the diameter of the pipe in inches. 1 = the length of the pipe in feet. P1 = the initial gauge-pressure in pounds per square inch. p2= the final gauge-pressure in pounds per square inch. W1 = the density of the air, or the weight in pounds per cubic foot at the initial pressure, p,. The most common case is that in which the given quantities are: the quantity of air required, the length of the pipe, and the initial pressure. The method of solution is to assume a pressure-loss and to compute the remaining factor, c/d5, thus giving the size of pipe corresponding to the assumed loss of pressure. It is always desirable to try two or more pressure-drops, in order to find the combination that is most satisfactory, since often a small change in the size of pipe will reduce or increase the loss of pressure several pounds. An alternative method is to assume a size of pipe and calculate the corresponding pressure-drop. Each method involves a series of tedious calculations to arrive at the most economical solution, and also requires the use of tables giving the constant, c, the actual diameters corresponding to the nominal pipe-sizes, the density of the air, w1, and often, for convenience, a table giving the

Dec 1, 1912

By L. G. Evans, W. W. Simpson, W. A. McKinney

In conventional dump leaching of strip wastes from open-pit porphyry mining operations, many years are required to extract a fraction of the copper from the contained sulfide minerals. Furthermore, none of the molybdenum, gold, or silver is recovered by current leaching practices. Because the copper sulfide minerals and molybdenite generally are distributed in the minute fractures throughout the host rock, the mineral values tend to concentrate in the finer fraction of the strip material. This suggests the possibility of segregating the enriched fines in as-produced or coarsely crushed strip wastes for blending with the ore grade flotation mill feed. In the past, extra handling or crushing of mine wastes to enable better leach extraction has been deemed uneconomical. However, recent articles on mobile crushing plants and conveyor haulage systems indicate possible cost improvements for these techniques over conventional truck haulage of ore and mine wastes. Another potential benefit from removal of the fines from copper-bearing mine waste derives from the increased permeability of the coarse dump material to leach solutions and air. Better permeability should result in faster oxidation of the sulfide minerals, less channeling of leach solutions, and fewer perched solution tables caused by compacted fines. Therefore, in addition to the metal values recovered by flotation, higher copper recoveries by leaching also might be achieved. The Salt Lake City Metallurgy Research Center of the U.S. Bureau of Mines undertook an investigation to determine the feasibility of removing enriched fines from strip waste material for separate treatment by froth flotation for early recovery of part of the copper, molybdenum, gold, and silver. Percolation leaching tests were made on mine-run and sized fractions of the dump material to determine the effect of fines removal on copper extraction. Samples Tested Three 10-ton samples of copper sulfide-bearing mine waste were obtained for the investigation. Partial chemical analyses of the samples are given in [Table 1] and the consolidated results of detailed screen analyses made on the samples are given in [Table 2]. The -1/4-in, fine fractions contain from 16 to 32% of the copper and 19 to 40% of the molybdenum in 11 to 18% of the total waste. The samples also were crushed to -3 in. to determine the feasibility of crushing to obtain a higher distribution of the metal values in an enriched fine fraction while providing a more leachable coarse fraction that could be transported by a conveyor system to a dump. The -%-in. fine fractions screened from the crushed mine waste were almost identical in grade to the natural fines. From 2 to 4% more1/4-in. fines were produced by crushing to -3 in. Copper distribution was increased by about 3% over that in the natural fines, while molybdenum distribution was increased by about 10%. The -1/4-in. fines screened from the mine-run and crushed strip waste were almost as high in grade as the ore being treated at the mills. In addition, the fines

Jan 1, 1974

By P Mason, J F. Huntington, K M. Scott

Short-wave infrared (SWIR) spectral reflectance of the hydrothermally altered volcanic rocks in the footwall of the Hellyer Zn-Pb massive sulfide deposit was measured with a portable PIMATM infrared spectrometer. The Al-OH absorption band was used to derive information on the cation composition of white mica. The wavelength range of the Al-OH band from 2194 nm to 2222 nm reflects variation in the number of octahedral Al (Alvi) in white mica from 3.9 to 3.2 (based on four octahedral cations per formula). This Alvi range indicates a substantial compositional variation, covering most of the compositional region between muscovite (Alvi = 4.0) and phengite (Alvi = 3.0). Moreover, the spectral reflectance data show that the compositional variations of white mica are spatially related to the hydrothermal alteration zoning, such that the white mica of more phengitic composition tends to form in the main upflow fluid channels in the centre of the footwall alteration system. The results suggest that the octahedral Al content of white mica, which is spectrally definable by the wavelength of the Al-OH band using a field instrument such as the PIMATM, can be used to map fossil hydrothermal systems and potentially as vectors to mineralisation.

Jan 1, 2004