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By Donald Ofte, L. J. Wittenberg

The absolute viscosity coefficients and activation energies for viscous flow of bismuth, lead, and zinc are reported. The viscosities were measured in an oscillating cup viscosimeter from nearly 1000°C to within 1 deg of the melting point of zinc; 2 deg of the melting point of lead; and in the supercooled condition of bismuth, 9 deg below the melting point. Two methods of relating the change in the viscosity coeflicient with temperature were compared. From the plot of the logarithm of viscosity (77) as a function of reciprocal absolute temperature (1/T), the equations of the lines which fit the data are: AS a part of the Reactor Fuels and Materials Research program at Mound Laboratory, precise measurements of the physical properties of liquid metals are of interest because the desirability for a low vapor pressure liquid coolant in high-temperature nuclear power plants has focused attention on the properties of the liquid metals.' Also, a clearer understanding of the liquid metal state can be achieved when better measurements are available. For these reasons, the viscosity values of certain liquid metals have been determined. The viscosities of the liquid metals, bismuth, lead, and zinc are measured in an oscillating cup viscosi-meter. In this apparatus the liquid is sealed in a right-circular cylindrical cup which is attached to a torsion fiber so that the system forms a torsion pendulum. The damping effect of the molten metal upon the normal oscillations of the torsion pendulum is a function of the viscosity of the liquid. This method is advantageous because of the small amount of sample required (8 to 10 cc), the ease of remote operation of the apparatus in a vacuum system, and the containment of the liquid metal in a hermetically sealed, nonreactive, tantalum crucible. With the liquid metal sealed in the crucible, loss of liquid by vaporization and chemical reactions with atmospheric gases are prevented. Additionally, an absolute viscosity determination is obtained which avoids the sources of possible error in a relative measurement. The difficulties in a relative method include the repetitious cup calibrations, and the uncertainty inherent in the practice of calibration of the apparatus at room temperature and extrapolation to the high temperatures necessary for the investigation of most liquid metals. The oscillating cup viscosimeter was first described by Meyer in 1891.2 The first complete mathematical treatment offering an absolute measurement of viscosity with this type of apparatus was proposed by Andrade and chiong3 in 1936 for an oscillating sphere filled with a liquid. This solution was modified to include a right circular cylinder by Hopkins and Toye4 in 1950, and R. Roscoe5 in 1958. Roscoe's treatment for the calculation of the viscosity of a liquid at a particular temperature from the logarithmic decrement and period of oscillation of the torsion pendulum was used in this investigation. A detailed description of the method of calculating the viscosity from these measurements has been reported earlier.' This calculation has been programmed for the IBM 704 and IBM 1620 computers for expedition of the otherwise laborious calculations. APPARATUS The cutaway view of the apparatus in Fig. 1 shows the suspension system within the high vacuum enclosure. The low residual gas pressure. maintained between 1 x 10-4 and 5 X 10-6 mm Hg during a determination, avoided both air drag on the pendulum and

Jan 1, 1963

By A. Zarei-Hanzaki, S. M. Fatemi-Varzaneh, M. Haghshenas

The microstructure in modified semi-solid ALTHIX (A356) alloy consists of aAl phase with Al/Si eutectic structure. Silicon phase in eutectic structure is coral like with fine fibers. The lack of good ductility in this alloy is related to the presence of silicon fibers. Accordingly many investigations have been recently conducted to modify the Si morphology through Thermomechanical processing on this alloy. In the present work an ALTHIX (A356) alloy was deformed at 450°C, 500°C and 540°C through different strain rates. Consequently the silicon fibers were broken into small particles. The results indicated that the Si particles may coarsen according to Ostwald ripening mechanism at 540°C deformed by rate of0.0005 sec-1 & 0.0001 sec-1-

Jan 1, 2006

By E. C. Houston

The presence in the Tennessee Valley of extensive deposits of olivine, a silicate of magnesium and iron that contains approximately 28 per cent magnesium, has been recognized since 1896 when Lewis8 published a survey of basic magnesium rocks of western North Carolina. A recent field survey by T.V.A.7 showed that more than two hundred million tons of high-grade olivine occurs above local drainage levels in western North Carolina and northern Georgia. Except for sporadic attempts to work the olivine for its nickel and chromium contents,10 the ore received little attention industrially until 1926 when Goldschmidt3 suggested its use in the manufacture of refractories. Only one instance is recorded of an attempt to utilize the ore commercially for its magnesium content;" in this case a process was used in which olivine was treated with sulphuric acid, the resultant mixture was leached with water, and the leach solution was purified and evaporated to form epsom salts, which was the end product. As a part of its program of contributing to the development of the natural resources of the region, the Tennessee Valley Authority became interested in the olivine deposits as a source of metallic magnesium because of their high magnesium content and proximity to hydroelectric power. Studies were undertaken to determine the feasibility of producing magnesium chloride by extraction of olivine. The experimental work was carried out successively at the T.V.A. Minerals Testing Laboratory, Norris, Tenn., at the Georgia State Engineering Station,* Atlanta, Ga., and at the T.V.A. laboratory at Wilson Dam, Ala. The present paper describes a process. developed through the pilot-plant stage, whereby magnesium chloride suitable for reduction to metallic magnesium can be prepared from olivine by extraction with hydrochloric acid and subsequent purification. Research on the magnesium-from-olivine process, originally intended for peacetime use, was given impetus by the shortage of magnesium that existed at the beginning of the current world war. By the time the process was sufficiently developed to justify a proposal for its inclusion in the war program, the shortage had been met by expansion and development of other processes. However, it is believed that the magnesium-from-olivine process may have advantages that will warrant consideration of its use after the war, when the economics of the various processes rather than production on a wartime scale will be the criterion for commercial production of magnesium. Description OF Process Metallic magnesium is produced electro-lytically by the Dow and the Elektron

Jan 1, 1949

By Hassan El-Shall, G. L. Zucker, T. S. Jordan

INTRODUCTION This chapter will discuss, both from fundamental and practical points of view, the flotation of non-sulfide min- eral s. The flotation characteristics of silicates, salt-type minerals, oxides and coal will be reviewed. Dup- lication of the thorough and excellent presentations by many authors is not intended and a comprehensive list of references is included. GENERAL PRINCIPLES Collectors for Non-Sulfide Minerals : All minerals, with only a few exceptions are readily wetted by water, that is, they are said to be hydrophilic. The purpose of a collector is to coat the mineral surface and render it hydrophobic, preferring an environment of air over an environment of water. Relative to sulphide minerals, the non- sulfides are more naturally hydrophilic and therefore, require a collector with a greater chain length. This is accomplished by using a collector which has a proportionally longer hydrocarbon chain. Both anionic and cationic flotation collectors are used in non- sulfide flotation. Anionic Collectors. These are collectors which ionize in solution to give a negatively charged radical. They have the general structure R-A, where R is a hydrocarbon having 8 or more carbon atoms and A is a hydrogen or an alkali metal. The most common collectors in this group are fatty acids which could have saturated or unsaturated hydrocarbon chains. Such chains may be straight or branched. The configuration of the chains affects their solubility in water and their adsorption characteristics. In general, as the chain length increases the adsorption and the collecting power increases. However, it should be noted that the solubility decreases. The solubility of unsaturated chains is greater than that of saturated fatty acids because double or triple bonds are polar and thus attract water molecules. Solubility data for collector metal salts, even though important for a proper understanding of flotation are not available for all collector systems. Solubilities and structures of different fatty acids are reported by Fuerstenau (1982). Values for the solubility products of fatty acid salts selected from a paper by Du Rietz (1958) are given in Table 1.

Jan 1, 1986

By Eugene A. Stephenson, Leon J. Pepperberg

The natural gas industry is essentially a byproduct of the oil industry. When first discovered the gas was usually regarded as a nuisance, and even when found immediately associated with oil, or suspected to be so, it was customary to blow it freely into the air, in the hope that gas would shortly be replaced by a flow of oil. The early methods of production,' transportation, and utilization were neither economical nor efficient; the chief value of gas was based on its use as a fuel, with no regard to (1) its effect. upon the oil with which it was associated, (2) its importance as a lifting agent, or (3) to its possibilities for the manufacture of byproducts. The spread of scientific research among major gas and oil companies, manufacturers, and academic groups, has gradually brought recognition of the fact that many of the technical problems bearing on production, transportation and utilization are common to both the gas and the oil industry. A few of the problems that have received serious study, and from which highly gratifying results have been obtained, are: (1) gas measurement, (2) oil well and gas well capacity tests, (3) elimination of field waste, (4) design of pipe lines and compressor stations, (5) extraction of constituents which might interfere with the normal flow of gas through the line, (6) control of reservoir pressure, (7) estimation of reserves of both oil and gas, (8) control of water encroachment, (9) measurement of factors which influence fluid movement through sands, (10) solubility of gases in oils, (11) effect of dissolved gases upon the properties of the solution. These investigations have demonstrated that almost every problem relating to oil production also involves some phase of natural gas engineering. During the past 15 years the use of experimental methods for the discovery and measurement of obscure, influencing factors, which cannot be determined purely by hydrodynamic or thermodynamic analyses, have contributed much towards the progress made in solving the problems of the oil and gas industries. Most of the experimental work on

Jan 1, 1934

By Bearman R. A, Parkin R. M

In the comminution industry cone crushers are widely used for secondary and subsequent stages of size reduction. Traditionally cone crushers have been operated and monitored manually. Alteration of discharge setting is now commonly achieved via hydraulic means, however, compensation of liner wear can still involve plant shutdown and loss of production. Drift in discharge setting due to liner wear is still a major problem that must be addressed to improve product quality, consistency and reduce recirculating load. The continuous demand for better quality products and the high cost of reprocessing or discarding unsaleable material, highlights the need for re-examination of the technology associated with the crushers to ensure optimum control and system efficiency. A collaborative project between Pegson Ltd, one of the leading UK manufacturers of jaw and cone crushers, De Montfort University Leicester, and Transfer Technology plc was established to address the technological requirement for automation of the control of cone crushers. The machine chosen for the study is a 900 Autocone cone crusher manufactured by Pegson Ltd. The design philosophy is based on a mechatronic approach providing a complete solution through a distributed network of intelligent sensors, artificial intelligence technology and adaptive control. The modular design of the system ensures a progressive sophistication in technology that allows the automation to be phased in as required. This will ensure maximum benefits to all sectors of the aggregate industry. It is estimated that the automation will result in savings of around ten per cent. The savings will result from minimising the production of unsaleable products by reliable condition monitoring and automation of the control and maintenance of system parameters to optimise system efficiency. Extension of the methods and principles into the mining sector is anticipated. The control over the size of crusher product will offer great benefits to the mining industry with significant implications for subsequent milling and beneficiation processes.

Jan 1, 1995

By M. Cohen, W. J. Harris

The recent application of lineal analysislt2 to the austenite-martensite reaction has made possible a quantitative study of the kinetics of this transformation during rapid cooling. Martensite range curves can thus be constructed to portray the onset of the reaction at Ma and its subsequent progress as a function of temperature down to and below the ambient. It now seems in order to investigate other aspects of the martensite transformation, using this quantitative method of approach. One of the least understood characteristics of the austenite-martensite reaction is that of stabilization which has been defined by Troiano and Greninger3 as 'la lowering of Ma, resulting from aging, without change in chemical composition of the parent solid solution." In other words, if the hardening quench is arrested at a predetermined subcritical temperature (TA) for a sufficient period of time, more austenite may be retained at a given lower Or reference temperature (Tr) than if the steel had been cooled directly and rapidly to Tr in the first place. For the purposes of the work at hand, the extent of stabilization produced by the isothermal treatment at Th is measured explicitly in terms of the excess austenite (6) that exists in the steel at T,, over and above the amount that is normally present after direct quenching to T,. T, is conveniently taken to be room temperature, but this choice is not essential and is sometimes undesirable. The holding temperature (TA) may be above or below M,, and still cause stabilization depending upon the themistry of the austenite. stabilization has been found to occur in the presence of bainite4 and of martensite6,6,7,8 as well as in the absence of either,g The phe-nomenon of stabilization is not concerned with (and may even be obscured by) ferrite formation or any other type of phase change occurring at T~ that alters the chemistry of the remaining austenite. Such a structural change would obviously influence the martensite transformation during subscquent cooling. Stabilization, however, is more subtle; it appears to manifest itself without detectable variation of the austenite composition, whether in the presence or absence of transformation products. There are relatively few direct references to stabilization in the literature. The stabilizing effect of room temperature aging and tempering on the subzero transformation of retained austenite has been clearly shown in plain carbon,6,8 low alloy6s7.8 and high alloy tool steels.10'5 ssa- with the as-hardened steel, the degree of stabilization increases with tempering time and temperature through

Jan 1, 1949

By V. Panayotov, M. Panayotova

"Finding a reliable relationship between fundamental properties of minerals of non-ferrous metals and their ability to float is extremely important. The approach presented in this work allows us to draw predictive models for an effective flotation, suitable choice of reagents regime and expected technological results before the minerals enter the flotation process. Attempts to adjust the technological regime in already begun flotation are often unsuccessful because the basic physicochemical processes have already taken place. Mineral processing can be optimized on the basis of objective and basic parameters, decisive for the efficiency of the process - the state of the surface of the mineral; assessment of: minerals flotation ability, the need to apply and the type of needed pretreatment, and expected technological results. The theoretical foundations of such an approach are presented in the work, as well as supporting them experimental results, and information on practical implementation in lead-zinc and copper-pyrite ores selection.INTRODUCTIONIncreasing impoverishment of ores of nonferrous metals incoming to the flotation and rising costs for obtaining the final product lead to the inevitable question - will the mineral processing process be beneficial economically, technologically feasible and environmentally safe and what is the way to improve its efficiency. Some of the possible solutions are already in practice - new more efficient and less energy consuming flotation machines and equipment, new - more efficient and selective reagents, new combinations of flotation regimens, and so on.Finding a reliable relationship between fundamental properties of minerals of non-ferrous metals (sulphides and oxides - most of them with semiconductor properties) and their ability to float is extremely important. This is the subject of research, started in the 60s of the previous century and continuing to the present day. Such dependence would enable a realistic assessment of flotation ability (flotability) of minerals before their flotation processing. The basic dependence, displayed by the researchers as Hoberg (1975), Chanturia and Shafeev (1977), Chanturia and Lunin (1983), etc., represents a relationship between bulk properties of minerals and their flotability, considering especially the concentration of the main charge carriers, namely electrons or holes. The bulk properties are practically constant for minerals from a given field. But the 'main arena' of the flotation process is actually the mineral surface (Carta, 1970; Rao, Labonte, & Finch, 1992; Panayotov, 1999; Rao, 2003; Hu, Sun & Wang, 2010). Therefore, we introduce a methodology for studying the surface of minerals, which methodology gives the degree of semiconductor bands bending on the surface and respectively - the charge of the mineral surface and its ability to interact with reagent-collector. The latter can be used to select the most optimal reagent for the corresponding mineral."

Jan 1, 2016

By L. K. Nemeth, H. T. Kennedy

The investigation presented in this paper was performd to develop a relationship between the dewpoint pressure of a hydrocarbon reservoir fluid and its composition, temperature and characteristics of the heptanes-plus fraction. This is part of an over-all program to develop correlations for the essential properties of reservoir fluids with the composition, temperature and pressure. In all, 579 dewpoint pressures, determined experimentally on 480 different condensate systems along with their compositions and temperatures, were obtained from the literature and from previously unpublished sources. Compositions were expressed in terms of mol fractions of methane through heptanes-plus, nitrogen, carbon dioxide and hydrogen sulfide, and the molecular weight and specific gravity of the heptanes-plus fraction. Distribution of the samples assured a good representation of most of the major oil-producing areas in the world. A multiple regression analysis program written for the IBhl 7094 digital computer was used to compare numerous equations and to calculate their coefficients. The final equation containing 11 coefficients resulted in an average absolute deviation of 7.4 percent for all the samples. Segregation of data on the basis of one or more variables did not materially improve the results. The correlation developed is useful in predicting the dewpoint pressure of condensate reservoir fluids from variables normally measured in the laboratory. INTRODUCTION In any discussion of the dewpoint of hydrocarbon mixtures, it should be noted that there are two kinds of dewpoints which must be distinguished. The first type, or normal dewpoint, usually occurs at low pressures as dry gas is compressed to the point where liquid first forms. The second type, sometimes called the retrograde dewpoint, occurs when a gas mixture containing heavy hydrocarbons in solution is depressured until a liquid is formed. The first type, as applied to condensate mixtures, would normally be below atmospheric pressure and would be of no interest in reservoir performance. The second type is of great significance in interpreting reservoir behavior and is the property referred to throughout this paper. Laboratory measurement of dewpoints is laborious, expensive and subject to many errors, and it is desirable to find a reasonably accurate method to predict dewpoint pressures from the composition and other readily available properties normally measured on the fluids. A possible method of calculating dewpoint pressures would be to employ a set of equilibrium ratios (K-values). 1 However, the K-values themselves depend on composition as well as temperature and pressure; presently their use adds nothing to the accuracy of predicting dewpoints. If future correlations provide a significantly better method of estimating K-values for heavy hydrocarbons, they may be of greater use. REVIEW OF LITERATURE In 1944, Olds, Sage and Lacey 2 studied the behavior of fluids from the Paloma field. Properties of seven mixtures were studied at temperatures ranging from 100 to 250 F and at pressures up to 5,000 psia. From the information obtained, the influence of composition and temperature upon the dewpoint was determined. It was found that removal of the intermediate molecular weight components from the mixture resulted in considerable increases in the dewpoint pressures. Results indicated that the effect of changes in temperature was relatively minor when compared with the effect of modifying the mixture by removing the intermediate components. Thus, removal of propane and butanes resulted in an increase in dewpoint pressure more than 10 times greater than a change in temperature from 100 to 250 F. The authors stated that althouah

By G. H. Alani, H. T. Kennedy

One of the major difficulties in predicting the performance of oil reservoirs from their early pressure history lies in the uncertainty of estimating the volume of the liquid hydrocarbons contained in them. As a first step in filling this need, an equation was developed to determine the Inolal liquid volume of pure hydrocarbons over a wide range of temperature and pressure. The second step consisted of adapting the equation to apply to mixtures, with the heary hydrocarbons expressed as c The equatious are similar in form to van der Waals equation. hut the constants a and b tire considered as furnctions of temperature. In addition to the gas constant R, there are four constants characteristic of each hydro- When comptired with experimental values jound in the literal the. the average absolute deviation in the calculated molal volumes is found to be a Maximum of 0.33 per -cem for any of the pure liquid hydrocarbons studied. This maximum deviation was that found when comparing the calculated and observed values over a temperature range of 86° to 482°F and a pressure range from the bubbl-point ro 10,000 psis. The equations expressing the correlation for. mixrurrc were developed from 647 experimental measure-rilents of volume on 47 bouom-hole samples covering ; temperature range of 72" to 250°F and a pressure znge from bubble-point ro 5,000 psig. The average absotute deviation was found to he 1.6 per cent with the maximum for any measurement of 4.9 per cent. INTRODUCTION Accuratc information of the pressure-volume-temper-iiture behavior of hydrocarbon liquids is of considerable importance in the field of both applied and theoretical science and, especially, in the solution of petroleum reservoir engineering problems. These PVT relationships can be expressed graphically, in tabular form or as equations of state. Equations of state for gases have been developed based on the ratio of pressure, temperature and volume to the pressure, temperature and volume at the critical points of the hydrocarbons. These equations have been successful in yielding values fairly accurate for reservoir engineering purposes. For liquids, however, relations of this type are more complex and have not yielded useful results. The composition of reservoir liquids is normally expressed in terms of the moles of hydrocarbons C,? C,. C,. elc, per mole of mixture. The composition must include the fraction of a mixture such as C,,, which cannot be separated with reasonable time and effort into specific hydrocarbons. Although there are several equations of state having variable degrees of accuracy applicable to pure liquid hydrocarbons, none includes a means for estimating the volume of mixtures as a function of temperature. pressure and composition expressed in this manner.

By C. G. Southmayd

Anyone who has been confronted with the problem of predicting the performance of a sand-pump installation is vitally aware of the dearth of precise information that has been published on this important subject. Such data as have been collected are not readily available in a concise and readily usable form, so that many operators would find it a considerable chore to find the pertinent information required to undertake a detailed study. The purpose of this paper is to assemble such established data, correlate them with field experience and outline the factors that must be appraised in the determination of a satisfactory pump installation. The transportation of solids in solution is of vital interest to every mill superintendent and operator, and many of the factors that are involved in this hydraulic problem vary widely from installation to installation, and in some cases even from time to time on any one installation. These include: type of solids (including shape of particles), size of solids (grind), percentages of fines (slimes), dilution of pulp, contour of pipe line, type of pipe, age of pipe line, effect that diameter of pipe has on characteristic flow conditions, and other factors. Some of these have been fairly well determined by experimental work but many still must be established through interpolating or extrapolating between values that have been derived from known field conditions. Most problems primarily concern the transportation of a definite weight of dry solids from one specific location to another. The type of material, shape of particles, grind and percentages of fines are established and very often the dilution at which the solids must be handled as well. The problem then evolves into a determination of the size, type and contour of the pipe line and the net effective head against which the pump must operate. Before discussing the determination of the head, it might be well to review the interrelationship between the pump discharge (capacity), the head developed by the pump and the pump speed, which will apply to any centrifugal pump installation. Effect of Pump Speed Basically, the head developed by a centrifugal pump varies as the square of the pump speed and the discharge as the first power of the speed. However, even at constant speed a centrifugal pump will operate over a wide range of capacities, depending upon the head that must be developed to deliver the liquid or pulp to the end of the pipe line. This is shown graphically in Fig. I. If the pump in question is being driven at a constant speed of goo r.p.m. it will deliver 500 U. S. gal. per min. against a head of 56 ft., 800 U. S. gal. per min. against a head of 50 ft., and so on. In other words, at this speed the capacity of the pump will be determined and limited by

Jan 1, 1947

By C. G. Southmayd

Anyone who has been confronted with the problem of predicting the performance of a sand-pump installation is vitally aware of the dearth of precise information that has been published on this important subject. Such data as have been collected are not readily available in a concise and readily usable form, so that many operators would find it a considerable chore to find the pertinent information required to undertake a detailed study. The purpose of this paper is to assemble such established data, correlate them with field experience and outline the factors that must be appraised in the determination of a satisfactory pump installation. The transportation of solids in solution is of vital interest to every mill superintendent and operator, and many of the factors that are involved in this hydraulic problem vary widely from installation to installation, and in some cases even from time to time on any one installation. These include: type of solids (including shape of particles), size of solids (grind), percentages of fines (slimes), dilution of pulp, contour of pipe line, type of pipe, age of pipe line, effect that diameter of pipe has on characteristic flow conditions, and other factors. Some of these have been fairly well determined by experimental work but many still must be established through interpolating or extrapolating between values that have been derived from known field conditions. Most problems primarily concern the transportation of a definite weight of dry solids from one specific location to another. The type of material, shape of particles, grind and percentages of fines are established and very often the dilution at which the solids must be handled as well. The problem then evolves into a determination of the size, type and contour of the pipe line and the net effective head against which the pump must operate. Before discussing the determination of the head, it might be well to review the interrelationship between the pump discharge (capacity), the head developed by the pump and the pump speed, which will apply to any centrifugal pump installation. Effect of Pump Speed Basically, the head developed by a centrifugal pump varies as the square of the pump speed and the discharge as the first power of the speed. However, even at constant speed a centrifugal pump will operate over a wide range of capacities, depending upon the head that must be developed to deliver the liquid or pulp to the end of the pipe line. This is shown graphically in Fig. I. If the pump in question is being driven at a constant speed of goo r.p.m. it will deliver 500 U. S. gal. per min. against a head of 56 ft., 800 U. S. gal. per min. against a head of 50 ft., and so on. In other words, at this speed the capacity of the pump will be determined and limited by

Jan 1, 1947

By C. G. Southmayd

ANYONE who has been confronted with the problem of predicting the performance of a sand-pump installation is vitally aware of the dearth of precise information that has been published on this important subject. Such data as have been collected are not readily available in a concise and readily usable form, so that many operators would find it a considerable chore to find the pertinent information required to undertake a detailed study. The purpose of this paper is to assemble such established data, correlate them with field experience and outline the factors that must be appraised in the determination of a satisfactory pump installation. The transportation of solids in solution is of vital interest to every mill superintendent and operator, and many of the factors that are involved in this hydraulic problem vary widely from installation to installation, and in some cases even from time to time on any one installation.. These include: type of solids (including shape of particles), size of solids (grind), percentages of fines (slimes), dilution of pulp, contour of pipe line, type of pipe, age of pipe line, effect that diameter of pipe has on characteristic flow conditions, and other factors. Some of these have been fairly well determined by experimental work but many still must be established through interpolating or extrapolating between values that have been derived from known field conditions. Most problems primarily concern the transportation of a definite weight of dry solids from one specific location to another. The type of material, shape of particles, grind and percentages of fines are established and very often the dilution at which the solids must be handled as well. The problem then evolves into a determination of the size, type and contour of the pipe line and the net effective head against which the pump must operate. Before discussing the determination of the head, it might be well to review the interrelationship between the pump discharge (capacity), the head developed by the pump and the pump speed, which will apply to any centrifugal pump installation. EFFECT OF PUMP SPEED Basically, the head developed by a centrifugal pump varies as the square of the pump speed and the discharge as the first power of the speed. However, even at constant speed a centrifugal pump will operate over a wide range of capacities, depending upon the head that must be developed to deliver the liquid or pulp to the end of the pipe line. This is shown graphically in Fig. I. If the pump in question is being driven at a constant speed of 900 r.p.m. it will deliver 500 U. S. gal. per min. against a head of 56 ft., 800 U. S. gal. per min. against a head of 50 ft., and so on. In other words, at this speed the capacity of the pump will be determined and limited by

Jan 1, 1946

By Walter R. Jr. Hibbard, William A. Vogely

INTRODUCTION Volatile markets and pricing, increasing imports, constraining but effective laws related to the environment, health and safety and price controls lead to concerns which generated pious laws stating non-fuel policy and authorizing studies but resulting in ineffective implementation. Several commissions, reports by the Secretary of Interior and even the President have led to many recommendations but little or no action. No single comprehensive policy could solve problems which are diverse, commodity specific and not categorizable (Landsberg 1982, 1983). Thirteen laws administered by 27 agencies regulate or affect minerals and materials. Political instability created by communist regimes in Southern and Central Africa jeopardized sources of critical imported materials. This situation led to a Resource War mentality. It was feared that the U.S.S.R. was seeking to control this area and exclude the United States from resources (Vogely, 1980). The success of the Organization of Petroleum Exporting Countries with a petroleum cartel led to fears of an Organization of Minerals Exporting Countries which might create more cartels and/or make the existing ones more effective. Economic needs of developing countries required export to maintain employment and balance of payments have led to world surpluses, weak markets, low prices, and large loans from the World Bank which have under- mined U.S. industry (Landsberg, 1982a). Un- cooperative environmental laws, obsolete facilities and non-competitive costs have led to shipping U .S. ores to other countries for processing into ingot and bars which are imported back to the United States. Yet massive internal turmoil has interrupted supplies, and led to un- certain availability and higher prices. This situation could happen again. Included in this category of critical materials with uncertain sources are metals required in the manufacture of military aircraft, which has led to concern regarding the defense industry base (Morgan 1983). Remedies have been proposed which include: updated stock piles, material substitution, international cooperation and coordination, foreign policy aimed at resolving racial and national stresses in South and Central Africa, relaxing U.S. environmental and public land regulations and action under the Defense Production Act (Goth 1982). The President's report (1983) to Congress has stated a national materials policy which recognizes: that materials play a critical role in our economy, defense, and standard of living; that public lands contain a vast untapped mineral wealth; that the role of government is to identify mineral issues and act on them; and that there is a need for long term high potential pay off research (Bureau of Mines 1983). There is a serious question as to whether or not a comprehensive national mining, minerals, and materials policy is feasible let alone necessary. One solution is to abandon the attempt at comprehensiveness and to target specific is- sues with realistic policies (Comptroller General 1979). In the following sections, the major studies of the 1970s will be reviewed, major issues yet to be faced will be identified, the principles involved in these resolutions will be reviewed,

Jan 1, 1985

By E. J. Nielsen, P. R. Strutt

A study has been made of the progressive changes in the distribution of etch-pit structures occurring during high-temperature creep in copper + 7 wt pct Al single crystals oriented with a [113] tensile axis. The two equally stressed glide systems with the highest Schmid factor would be expected to form subboundaries of the type predicted by Kear.2 The alignments of etch-pits on sections parallel to different (111} planes consistent with these types of boundaries were not observed. However, they were consistent with planar subboundaries (on a macroscopic scale). From an analysis of Amelinckx1 it may be shown that stable cross-grid dislocation boundaries may form in the primary slip planes. These boundaries form when dislocations with a Burgers vector not in the slip plane move into the plane by combination of climb and glide. THE geometry of subboundaries formed by the interaction of dislocations of two glide systems has been analyzed by Amelinckx,1 and the particular types produced by deforming fee crystals are predicted by ear.' In this paper types of boundaries which may be formed when climb as well as glide occur are discussed as this is relevant in high-temperature creep. It is assumed in the present investigation that the etch-pits observed in Cu + 7 wt pct A1 on surfaces parallel to {111} planes delineate the sites of dislocations. Although there is no direct evidence for this previous work on a-Cu/Al single crystals by Mitchell, Chevrier, Hockey, and Mon-aghan,3 would show this assumption to be reasonable. The alignments of etch-pits which form during creep are studied on sections parallel to each {111) plane. It is then deduced that these alignments are consistent with a specific type of planar subboundary. The Cu + 7 wt pct A1 single crystals had a [113] tensile axis and Fig. 1(a) shows schematically the relation of the slip planes and slip directions (as represented by tetrahedron ABCD) with reference to the tensile axis. The two equally stressed glide systems with the maximum Schmid factor namely ß-AD and (a-BD, from the analysis of Kear,2 would be expected to form the boundaries shown in Fig. l(a) and (b), also Fig. 5(a) and (b). EXPERIMENTAL PROCEDURE The a-Cu/Al single crystals were grown and annealed in a "gettered" argon atmosphere. Chemical analysis showed the aluminum content to be uniform in each crystal and the difference between crystals was maintained to an accuracy of ± 0.25 wt pct. The initial dislocation density and mean subgrain diameter after annealing was -106 cm-2 and 250 µ, respectively. Surfaces parallel to (111) planes were produced by specially developed electrolytic machining processes. The {111} faces were next electropolished for 5 min in a solution consisting of 25 g chromium trioxide, 113 ml glacial acetic acid and 40 ml water; the applied potential was 8 v. Dislocation etch-pits were revealed using l an etchant described by 1 ml bromine, 45 ml HCl, and - 250 ml water. RESULTS In crystals strained into secondary creep at higher stresses (443 and 750 g - mm-2 at 650° C aligned rows of etch-pits parallel to slip plane traces were evident in sections parallel to the (1111, (ill), and (111) planes, see Fig. 3. As well as the longitudinal alignments in Fig. 3, well formed randomly oriented arrays indicative of an equiaxed subgrain structure are evident. At the lower stresses (100 to 230 g . mm-2) only an equiaxed structure formed during creep. The sections in Fig. 3 are from a crystal crept for 70 hr at 650°C with a CRSS of 443 g.mm-2. Two identically oriented crystals were also deformed at the same temperature and stress for 5 min and 4 hr. In the crystal crept for 5 min, the etch-pits were randomly distributed with no tendency for directional alignment, see Fig. 2(a). As shown in Fig. 2(b) aligned arrays were evident after 4 hr creep but they were not nearly so well defined as in Fig. 3. The alignments (parallel to the arrows) in Fig. 3 are consistent with the existence of boundaries in the two main slip planes a and ß. The way in which this is deduced is seen by reference to Fig. l(c), where the existence of boundaries in the a and ß planes is verified by sectioning parallel to a,ß, and d. The (111) and ß(111) planes intersect the d(111) plane along BC [101 ] and AT [011] and alignments parallel to [101] and [011] are clearly evident in Fig. 3(c) in a section parallel to the d(111) plane. Similarly the a, and ß planes in Fig. l(a) intersect each other along DC [110] and hence there will be an alignment parallel to [110 ] in sections parallel to the a-plane and the ß-plane; this is evident in Fig. 3(a) and Fig. 3(b). It is interesting to note that alignments of etch-pits consistent with the boundaries predicted by Kear2 were not observed; see Figs. l(a) and l(b). The geometry of boundaries in {111} planes as shown in Fig. l(c) is discussed later. In Fig. 4(a) the individual etch-pits are resolved and the alignments are exactly parallel to the slip trace direction [101]. However, in some areas alignments deviate away from the slip trace direction by as much as 10 to 15 deg, this is evident in Fig. 4(b), and in Fig.

Jan 1, 1969

By P. N. Eksteen, G. E. Greig

The South African mining industry currently installs about 6 km per month of plastic pipes for conveying compressed air and water. Plastic pipes have a number of desirable properties and are favoured by many mining engineers because of their low mass, which facilitates ease of erection and assembly, and their excellent corrosion resistance and durability. However, they are combustible, and if involved in an underground fire can contribute to the overall toxicity of the combustion gases emitted. Furthermore, plastic pipes have the potential to conduct a fire from one part of a mine to another, and, by so doing, exacerbate an already hazardous situation. The limitations of small scale tests and the need to establish a large facility where underground conditions could be simulated was recognized by the South African mining industry. This paper briefly describes the Industry's full scale fire test facility and presents the conclusions drawn as a result of a number of full scale combustibility tests conducted on pipes manufactured from unplasticized Poly Vinyl Chloride (uPVC) and High Density Polyethylene (HDPE). Based on these findings, some practical solutions to prevent the spread of fire along the length of pipe columns of various pipe diameters and suspension configurations are presented. Recently some new and exciting developments in the field of intumescent coatings have occurred which are proving effective in minimizing the incidence of fire underground on South African mines. The potential benefits of these coatings are briefly discussed. INTRODUCTION Plastic pipes used underground on mines are predominantly in the form of protective cladding on insulated chilled water pipes and as service pipes for the conveying of water and compressed air to the workings. Plastic pipes have found wide use in the aggressive environmental conditions encountered underground due to their favourable properties relative to steel; these include being lightweight, easily installed and virtually immune to corrosion. However, plastic pipes are inherently combustible and can contribute to the overall hazard in three ways: (i) they are easily ignitable and can provide the initial fuel for a fire. (ii) once ignited, they can propagate a fire along their length and by so doing ignite other combustibles in their path, thereby contributing significantly to the overall conflagration. (iii) they can contribute to the overall heat, smoke and toxic gas emissions from a fire. While conscious of the value of small scale fire tests, the South African mining industry recognized the need for full scale testing to determine the combustion characteristics of plastic pipes under conditions closely approximating those underground and, as a consequence, a full scale fire tunnel test facility was commissioned with the objective of being able to (a), accurately evaluate the potential hazard of the various types of the plastic pipes found in mines, (b) use this information to suggest suitable fire engineering practices to minimize the hazard and (c), to practically verify the efficacy of the practices suggested. THE FIRE TUNNEL The fire tunnel is situated on a mine in the Western Transvaal and is 40 m long with a cross section of 3 m x 3 m which is typical of many haulages currently in use in South African gold mines. The ventilation drawn through the tunnel is provided by a 110 kW centrifugal exhaust fan and air velocities can be varied from 0 to a maximum of 5,8 m/s.

Jan 1, 1993

By H. P. Moore, R. W. Fenn, Harold Margolin, W. R. Hibbard

DEFORMATION lines, also called etch markings or strain markings, are noneffaceable lines developed in individual grains by etching a metal specimen which has been cold worked sufficiently to cause atomic non-conformity or slight orientation differences within the grains. Etching occurs more rapidly at these lines of high chemical reactivity to produce a result similar to that revealing grain boundaries.1 Wider etching effects forming bands have been found. They are believed to be bands of deformation lines which form areas of measurably different orientation from the crystal matrix. The crystallite rotations causing these bands have been shown by Barrette to contribute to deformation textures. Although deformation lines have been observed in many metals, the amount of deformation required for their appearance has been established only in general terms. Mathewson and Phillips3 observed the first appearance of deformation lines in cold-rolled alpha brass at about 20 pct reduction in thickness using the standard ammonium hydroxide hydrogen peroxide etchant. Price and Davidson4 noted deformation lines in common high brass after 26.5 pct reduction by cold rolling using the same etchant. Johnson' observed dark thick forklike lines in 99.99 pct pure copper reduced 31.8 pct. Adcock6 observed deformation lines in 80-20 copper-nickel alloy rolled 50 pct. Samans7 found no deformation lines in alpha brass single crystals cold rolled 9.5 pct but they did appear after 25 pct reduction using ammonium hydroxide and hydrogen peroxide etchant. Barrett and Levenson8 observed deformation bands in drawn polycrystalline iron at very small reductions in area and noted that their initial appearance perhaps depends on grain size and other conditions. They reported deformation bands in a single crystal of iron reduced 6 pct by drawing. Brick9 noted that deformation lines in 70-30 brass apparently associated with {111} planes appeared after reductions of from 20-50 pct by cold rolling. Brick and Williamson10 noted that in single crystals of 70-30 alpha brass "as in polycrystalline brass, no deformation markings appeared until reductions exceeded 20 pct." Cook and Richards11 reported that in copper cold rolled less than about 50 pct few strain markings were apparent but for higher. reductions many strain markings appeared transverse to the rolled direction. In a review article Brick and Phillips12 noted that previous studies had not shown deformation lines in cold rolled alpha brass

Jan 1, 1948

By Ian P. G. Hutchison

12.1 INTRODUCTION This chapter deals with the tools required to design leach operations to minimize spillage from leach pads and ponds and erosion damage during flood events or prolonged wet periods. It outlines methods used to design for prolonged dry periods when water shortage can be a problem. Seasonal operational aspects such as winter shutdown and coping with spring snowmelt periods are also discussed. General criteria useful when designing pregnant and barren solution ponds are also outlined. The aim of these notes is to provide designers and operators with a simp1ified approach to developing design parameters which make effective surface water management easy to achieve without resorting to extensive or elaborate analyses. Section 12.2 briefly outlines the types of problems associated with wet climates and floods, as well as dry periods. Determination of flood design parameters is discussed in Section 12.3. Circuit water balance and pond sizing are outlined in Section 12.4. Pond design considerations are included in Section 12.5. Worked examples are included in Section 12.6. 12.2 RAINFALL/RUNOFF PROCESSES There are two types of rainfall-runoff processes that are important when designing heap leach facilities. The first of- these is the short-term, intense rainfall or snowmelt events that occur over a period of a few minutes or hours, causing flooding that can lead to erosion damage and overtopping of ponds and containment dikes. Specific problems that can manifest themselves during these events include: • Washout of access roads; • Damage to containment dikes; • Flood water contamination of circuit water; • Damage to process water ponds by perimeter erosion or overtopping and erosion; • Loss of process circuit fluid due to breaks in containment dikes or process water ponds; and • Erosion of leach pile and consequent sediment contamination of process fluid. Other types of rainfall -runoff processes that could cause problems are the long-term-(generally months-long) wet or dry periods. Extended wet periods

Jan 1, 1988

By J. M. Donkers, R. de Groot

The various objectives of dredging at sea require different methods and radically different equipment for their optimum fulfillment. In the majority of cases, sea dredging is done by means of dredging equipment connected to a pontoon or ship floating at the surface. As the supporting hull is subject to the influence of waves, swells, currents and wind, the connecting point of the dredging equipment to the hull will generally move relative to the sea bottom with 6° of freedom. The more important hull motions are surge, heave, pitch and roll. Depending on the actual sea and weather conditions and the size of the hull, some of these motions can be so large that dredging equipment of rigid construction (normal or inland dredges) cannot be used. In those cases where mechanical disintegration of the bottom is necessary and where accurate dredging is required, the designer must find a solution for this problem. For cases where the bottom consists of soils that can be handled by plain suction, highly sophisticated dredging equipment such as the trailing suction hopper dredge permit dredging under all but the most severe sea state conditions. This type of dredge picks up the soil from the sea bottom while slowly underway. The drag suction head is fitted on a suction pipe of such flexibility that the supporting ship can carry out all six movements in relation to the draghead (heave, pitch, roll, sway, yaw and surge), while the draghead remains in firm contact with the bottom. The suction pipe is fitted with flexible hoses, a universal hinge, a horizontal hinge, axial turning gland and sliding turning gland with horizontal axis and is suspended flexibly from the ship incorporating swell compensating buffer gear, keeping the wires taut and the draghead bottom contact pressure fairly constant while the dredge moves up and down. Due to the fact that the draghead has a low bottom contact pressure and has little tendency to sink into the bottom, this compensation is not difficult to realize.

Jan 4, 1974

By Nickvinder Bhath, Johnson Matthey Plc, Jamie Baker, Daniel Kim, Jeff Lucht, Shijie Wang

"Precious metals (PM) in copper anode slimes are traditionally recovered by pyrometallurgical processes. Due to the compliance with increasingly stringent environmental regulations, it has made hydrometallurgical processing an attractive method for recovery of precious metals, including relatively inert metals such as gold and platinum group metals (PGMs). In this paper, a new method to recover PGM from complex and difficult feed streams is described. Using a proprietary Advanced Ion Exchange (AIX) adsorbent which has a high selectivity for PGMs over other metals and can achieve high PGM mass loadings with a series of incredible pilot test data plus the business case generated from the study results are also presented in the paper.INTRODUCTIONPrecious metals in copper anode slimes are traditional recovered by pyrometallurgical processes. Due to the compliance with increasingly stringent environmental regulations, it has made hydrometallurgical processing an attractive method for recovery of many metals, including relatively inert metals such as gold and platinum group metals (PGMs). Fully hydrometallurgical processes for extraction and recovery of gold and silver from copper anode slimes were employed in major copper refineries since 1995, which was first developed at Rio Tinto Kennecott Utah Copper.In Rio Tinto KUC process, the wet chlorination and gold solvent extraction were utilized to enable recovery of gold and silver as well as other metal compounds. The availability of water and the interaction and amenability of gold processing in water-based solution makes it possible that gold and silver are produced in only five days, compared with a traditional pyrometallurgical process that took 45 days. Most copper refineries are still following the tradition, but the use of hydrometallurgical technologies is increasing as the world demand for metals increases, energy utilization, and environmental viability."

Jan 1, 2016