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By W. J. D. Stone

"INTRODUCTION Over the past decade, a number of publications have described the advances in High Intensity Wet Magnetic Separation. A number of significant, but small capacity installations were made and are successfully operating. These were followed some three years ago by larger installations treating ilmenite gravity concentrates; at least one machine treating 25 tons per hour of new feed was installed and is successfully operating.However, this still did not result in general acceptance that High Intensity Wet Magnetic Separation could be applied on a large scale. Neither did it dispel the feeling that High Intensity Wet Magnetic Separation was ""expensive"" and hence, confined to small scale – high value applications suchas the cleaning of tin concentrates. In addition, there is the usual reluctance of being the ""guinea pig"" which has resulted in waiting to see ""someone else"" make the first large installation decision. Such a decision and installation has now been made.Therefore, the purpose of this paper is to show that High Intensity Wet Magnetic Separation has been commercially accepted on a large scale and to show its general application to the base metal mineral industry.Examples are confined to a few specifics due to the large volume of preliminary test data that is available. The art has now reached the stage where much of the preliminary work should be taken through to serious evaluation."

Jan 1, 1971

By J. G. Montgomery

An increased drilling activity was apparent in the shallow sand fields of northwestern Pennsylvania during the year. This drilling, however, was confined to previously outlined productive areas and as new shallow sand pools of interest were discovered. Drilling for Oriskany gas proceeded at about the same rate as in previous years. One new area in Kinzua township, Warren County, was opened up during the year by a producing well, but later this well developed salt water and the productive capacities of the area are very indefinite at the present time. Production from the shallow sand areas remained approximately the same as in 1935. Production from the Oriskany or deep sand areas increased approximately 20 per cent. Two new markets were made available for the Oriskany gas during the closing months of the year by the completion of the Peoples Natural Gas Co. line from the Hebron field to Clarion County, Pa. and Penn York Gas Co. line from the Harrison field to points in northwestern New York State. With the exception of the Kinzua well, the few deep wildcat wells drilled during the year failed to discover new fields in the deep sands. Bradford Oil Field The accompanying data on the Bradford oil field include only the production obtained from the portion of that field that is in the State of Pennsylvania, for it appears probable that Cattaraugus County production, which consists mainly of the New York State portion of the Bradford field, will be included in annual oil production figures for New York State. The Bradford field production for 1936 totaled 14,533,000 bbl., and as it is necessary to estimate New York State production for the Bradford field, the accompanying data includes the production from the Pennsylvania end of the Bradford field of 13,208,000 bbl., which is an increase of approximately 8 per cent over 1935 production.

Jan 1, 1937

Jan 1, 1969

By T. A. Read, S. W. Kitchen, H. I. Fusfeld

At the present time most artillery cartridge cases are used only a single time. Since the process of reshaping a fired cartridge case so that it may be used again is much simpler and cheaper than the original manufacture of the case, it is clear that important savings could be effected if such re-formed cases were used in place of new cases. Extensive use of reconditioned cases has been hindered in the past, however, by the deterioration of the brass which may occur in the period of time between the first firing and the reconditioning of the cartridge cases. This deterioration sometimes results in a dangerously high incidence of firing splits in groups of reconditioned cartridge cases. It appears that the mechanism of the deterioration is the season cracking of the brass, for season cracks, of varying degrees of severity, may frequently be found in the cartridge cases after their return from the field. There are, of course, severe practical limitations to the extent to which fired cartridge cases can be protected from corrosion under battle conditions, particularly since the powder residue in the case is itself corrosive. The present paper describes a rapid method of testing the sidewalls of artillery cartridge cases for the presence of season cracks. This method has been developed specifically for use in connection with the reconditioning of fired cases, and makes it possible to carry out 100 per cent inspection. This new method of inspecting cartridge

Jan 1, 1945

By R. V. Ramani, J. Qin

"In this paper, the results of a research study on airborne dust transport in a full scale simulated longwall face are presented. The simulated longwall face was set up in the Lake Lynn Laboratory mine of the U.S. Bureau of Mines to conduct experiments under controlled conditions. The controlled parameters in the experiments were the dust dispersion rate, dust size distribution, density of the dust, air velocity, and the rate of travel of the dust generating source. The analyses of the experimental results on mass concentrations, particle size distributions, and real-time respirable dust concentrations are discussed. There are definite spatio-temporal trends between the location of the shearer, the concentration at any location in the face, and the dust generation rates. The size-consist and density characteristics of the source dust, the air velocity in the face, and the air leakage into the gobs all affect the concentration. INTRODUCTIONA detailed experimental study on the characteristics of longwall dust cloud in operating longwall faces has been reported by Ramani, Qin, and Jankowski (1991). The study indicated that there are several important factors whose effects on dust transport in longwall faces need to be further investigated. In an operating longwall face, the effect of these parameters could not be easily isolated as control over the affecting parameters is not readily possible. In a simulated longwall face, however, these parameters can be controlled. Therefore, as a follow-up to the field study, a series of controlled experiments were conducted in a full scale simulated longwall face in the Lake Lynn Laboratory mine of the U.S. Bureau of Mines [Qin, 1992]. Specific aspects which were addressed during the experimental design phase included determining the types of samples to be collected, selecting proper instruments to collect these samples, and developing detailed sampling and time-study plans to correlate the dust concentrations with face activities. Two types of dust--anthracite and bituminous--were used. Dust dispersion rate into the air as well as the source dust particle size distribution were documented. Control was exercised over both air velocity at the face and air leakage along the longwall face. During experiments, the dust source was moved to simulate the shearer movement at operating longwall faces. Detailed descriptions of the design of experiments, experimental results, and data analyses follow in the subsequent sections."

Dec 1, 1996

By Luis Emylnn Salas

If the ordinary wet method be attempted for silver-bullion containing tin, much trouble is experienced, varying with the amount of tin present. Even with a percentage as low as 0.05, the end-point is masked by a persistent turbidity, while with amounts ranging from 0.5 per cent. upward, the determination of the exact end-point is impossible, owing to the finely divided or colloidal metastannic acid resisting all efforts to cause it to settle, or to give a clear supernatant liquid. The object of the following experiments was to seek a remedy for these difficulties, and to find the conditions whereby the Gay Lussac method might be applied directly to these bullions. Material containing tin is met with frequently in bullion from Mexico or Bolivia; and tin is carried (sometimes in large quantities) in jewelers' sweeps. 1. A bullion was prepared containing Ag, 74; Cu, 25; and Sn, 1 per cent. A weighed amount was treated by the humid assay-method as if it were an ordinary bullion free from tin. Ten cc. of HNO, (1.21) was added, and the bottle was heated until all traces of

Jan 1, 1913

By W. Spencer Hutchinson

THE outstanding engineering accomplishment of the last three decades has been the development and application of more and cheaper power and its use instead of the labor of men and animals. Substitution of power for manual labor has taken effect on every hand in the United States. With the aid of energy mechanically available to his hand, one man does the work that only a few years ago required two, three or even a greater number of laborers. The results in respect to the favorable economic effects are well known; namely, increased production, higher wages and lower costs. On the other hand, the vast social effects, both good and bad, have been none the less important, even if less understood and only casually regarded. The chief sources of energy today are the mineral fuels, coal and petroleum. In the United States they yield more than 90 per cent of the total energy demand. Thirty years ago the proportion of energy supplied by the mineral fuels was likewise above 90 per cent, but the division according to origin was very different. These relations. are shown for the years 1900, 1930 and 1950 in Table 1.

Jan 1, 1933

The effect of temperature, time and SO2 concentration in the atmosphate have been studied for a complex Pb-Zn concentrate, which contained four sulphides and some organic material, in order to determine optimum roasting conditions. Under static roasting conditions virtually complete sulphation was achieved after roasting at 650¦C.2 hours in 10% SO2 in air. Both zinc ferrite and zinc silicate were observed to form early in the roasting, but continued exposure to SO2 -containing gases caused decomposition of these as the roasting time increased. Water and acid solubilities of iron, silica, calcium, magnesium and aluminium in the calcine were determined, as a function of roasting time, temperature and atmosphere composition.

Jan 1, 1970

By Sergey Ulianov, Arkady Senchenko, Alexey Shvets, Arkady Bakotin

"This paper is devoted to ultrafine grinding of processing products. This process allows one to include into operation complex ores which earlier were considered as inefficient and economically inadvisable to treat. Fine dissemination of valuable component often does not allow its liberation via standard grinding in ball mills, and therefore requires modern methods of ultrafine grinding (UFG). An example of successful ultrafine grinding usage is its application for crude flotation concentrates regrinding before cleaner flotation stages. A problem often arises with a commercial copper concentrate production in the course of copper ore flotation. Crude flotation concentrate regrinding in a ball mill does not provide for good liberation of the material before cleaner stages. UFG application allows one to get commercial copper concentrate with copper grade of 20% and higher. Another example of ultrafine grinding application is its usage for highly refractory pyrite product received after gold-lead scavenger flotation of polymetallic ore. Earlier this product treatment was economically inefficient. At current application of ultrafine grinding down to 85% minus 20 µm and subsequent gravity processing it is possible to pass major part of gold (73.4%) into concentrate. The constraining factor for UFG application in processing may be the chemical activation of minerals. In the result of this, flotation selectivity may decrease. Therefore ultrafine grinding application extends the areas of efficient usage of metallurgical processes. New technologies allow increasing the level of valuable metals recovery."

Jan 1, 2014

By A R. Bonani, M P. Pe±a

The optimisation of slope angles, that is to say, increasing them, compared to the original design is always the subject of analysis of stability for geotechnical engineers and economic analysis for planning engineers. Questions to be answered include: What is the acceptable risk? What factor of safety? What probability of failure or reliability? The Rosario Open Pit has a history of failure, poor quality rocks and high pore pressures. It was decided to deepen the pit below the programmed design to test the practicality of different design approaches, which if successful, could be used to improve the economics of mining at Collahuasi. The revised slope design has factors of safety in the range of 1.0 to 1.2, probabilities of failure of ten to 38 per cent, and increased slope angles of between 3¦ and 5¦ with respect to the original design. The pit deepening with these design slopes will deliver an extra two million tonnes of ore which will have a significant positive impact on mining economics.

Jan 1, 2007

By R. S. Kinasevich, D. D. Crabtree, D. W. Fuerstenau, T. P. Meloy, A. L. Mular

This paper presents details of the concept that size reduction in comminution machines takes place by three mechanisms; namely impact, abrasion, and chipping grinding. Experimental evidence is presented to show that each of these comminution mechanisms produces particles of a characteristic size distribution. The actual product from a comminution device has been postulated to be the result of a composite of these three types of mechanisms. Composite curves are demonstrated for a material following the Gaudin-Schuhmann, Gaudin-Meloy, and Rosin-Rammler size distributions. About forty years ago, Gaudin1 showed that grinding may be considered a combination of impact and attrition. Since that time, major efforts have been devoted to studies, both experimental and theoretical, of impact and compression fracture, while attrition has been almost wholly neglected, at least quantitatively. A significant attempt to distinguish between attrition and impact grinding is the work of Tanaka2 in Japan. By means of an instrumented abrasion grinder and a drop weight device, he determined coefficients relating the increase in surface area of various materials to the energy expended by the two methods of comminution. He showed that physical properties of a material determine its response to attrition and impact grinding. By extending his ideas to ball milling, he concluded that to a large extent the basic comminution process in a ball mill is due to the impact of falling media. Because Tanaka used a mass of particles in his drop weight device, however, he did not obtain pure impact size reduction. The purpose of this paper is to define basic mechanisms of size reduction, to verify that each has a characteristic and meaningful distribution curve, and to show how a combination of these mechanisms results in a size distribution very like that produced by grinding mills. DEFINITION OF COMMINUTION MECHANISMS The product from a grinding device will be considered to be the sum of the contributions resulting from the action of three basic mechanisms of size reduction which operate in a ball and rod mill. These are impact grinding and two forms of attrition, namely abrasion grinding and chipping grinding. Each is defined below. Impact Grinding: If a straight line is obtained when the cumulative weight fraction finer than a given size is plotted on log-log paper as a function of that size, the slope of the line is defined as the distribution modulus. A number of investigators 3,4,5 have shown that impact fracture of single specimens of different composition and shape results in a distribution of daughter particles that exhibit a distribution modulus of unity. This has also been true for materials broken in slow compression. Moreover, under slow compression or impact fracture conditions, theoretical distribution equations6*' which approximate the Gaudin-Schuhmann distribution when the distribution modulus is close to unity agree reasonably well with the experimentally obtained products. If one now considers a comminution process where many impact or compression fracture events are taking place, then any rational summation of the individual events yields, in the finer size range, a Gaudin-Schuhmann distribution whose distribution modulus is also unity. If the size distribution of the product from a mill has a distribution modulus of unity, it is implied that particles are fractured in a manner which results in a comminution event having a distribution like that obtained for the breakage of single specimens. These impact events would occur when a particle is smashed between balls or between a ball and the mill liner. Attrition, on the other hand, is that form of grinding which cannot be called impact grinding, and comprises both abrasion and chipping grinding. Abrasion Grinding: Abrasion is a form of surface wear resulting when particles rub against each other or against balls or the mill liner of a tumbling mill, somewhat like a piece of wood being rubbed over a piece of sandpaper. The surface wears at a more or

Jan 1, 1964

By H. H. Rachford, J. Douglas, D. W. Peaceman

A numerical solution of equations describing two-phase flow in porous media shows promise in providing a technique for predicting the displacermet from satlds of oil by water or gas. The description includes the influence of relative permeability, fluid viscosities and densities, graviry, and capillary pressure, and, tholrgh tested ortly for two-dimensional cases, should be eqlmlly applicable in three-dimensional geometry. Two memorical methods ore presented: the first method is quite general in its applicability; the second method can be used only with certain types of boundary conditions but requires less computing. Comparisons of computed results with data from Inhoratory models are presented. These data were taken on a water flood of a strarified model and on water floods of a five-spot model for favorable and unfavorable mobility ratios. On the stratified model, excellent agreement with recovery at breakthrough was obtained; agreement with recovery after breakthrough was poor. In the five-spot model, good agreement was obtainecl with recovery at and after breakthrough. The purpose of this paper is twofold: first, to present a reservoir engineering method requiring knowledge only of rock geometry and the normally measured rock and fluid properties for calculating the multi-dimensional flow of water displacing oil from porous, water-wet rock containing connate water; and, second, to investigate the validity of the method by comparing results of calculations with previously observed displacements in laboratory models. The availability of such a verified technique of reservoir analysis would afford major advantages. First, it would demonstrate that the fundamental macroscopic concepts of two-phase fluid mechanics, i.e., relative permeability and capillary pressure, yield an adequate description of the physical process. Also, since most reservoir rocks appear to be water-wet and contain connate water along with oil, it would provide a method of technical and economic value for calculating the course of oil displacement by water directly from measured reservoir and fluid properties. It is important to emphasize that the calculation is subject only to the limitations of detail and precision of reservoir information, but not to limitations introduced by simplifying assumptions. Further, it would providc almost the only means of examining the influence of factors such as the size and extent of reservoir inhomogeneities and uncertainties in the basic reservoir data. Knowledge of this influence is essential in stating quantitatively the detail required to define a reservoir and in establishing the relation between the uncertainty in the definition of reservoir properties and the reliability of predicted performance. Moreover, in the process of solving a particular problem much detailed information would become available about the displacement process. For example, at each point in the reservoir for all stages of the displace ment. the calculations would yield not only the water and oil saturations but also the direction and magnitude of fluid velocities and the local fluid mobilities. Such dctail is potentially of great value in giving insight into the mechanics of particular displacements. The development of such a method has long been the goal of research in the application of numerical an-alysis to petroleum reservoir enginecrinz. The most complete treatment of the displacement process published to date is that of Douglas. Blair, and Wagner,' which, however, was limited to flow in a single dimension. The method presented in the present work is hascd on the numerical solution of a finite difference analogue of the multi-dimensional differential system describing the displacement process. Although current work has considered only displacement of oil by water from water-wet sands, the differential system for other immiscible displacements, such as gas displacing oil with which it is in phase equilibrium, is quite similar. It should therefore be expected that the technique described will be applicable to displacement by gas as well. The description of the simultaneous flow of fluids through porous media in terms of relative perrncability and capillary pressure has been adequately discussed in the literature and standard textbooks. Sec, for exampje, Muskat. Chapter VII.'

By Laurel E. Burns

Alaska is in competition with the rest of the world for exploration dollars. Providing a "seed package" of airborne geophysical data for the state's numerous mining districts encourages companies to begin more detailed exploration in more areas than they could have afforded on their own. When data are already available, the initial risk decreases for people involved in exploration. Airborne magnetic and electromagnetic data help ge¬ologists and geophysicists determine what rocks and structures are present under overburden and vegetation. These data form a fundamental package that exploration companies want before intensively exploring most regions. Individual mining companies have conducted their own geophysical surveys during the past several decades. However, these data are not available to other companies. The companies able to afford geophysical surveys have less money for ground exploration after purchasing expensive, private geophysical data. Therefore, they are not able to explore as many places as they might. Additionally, since data are not shared with other exploration companies, the proprietary surveys do not foster intercompany competition to move projects forward. Individual prospectors and small companies can not afford their own geophysical surveys. "It is more often than not the grassroots exploration efforts of the smaller operator that leads to significant discoveries," said Klaus M. Zeitler, senior vice president for development and exploration at Teck Exploration. Acquiring and releasing the geophysical data to the public produces several benefits. The increased explo- [ ]

Jan 1, 1998

By J. A. Rose, A. S. Atkins

Environmental awareness has become a paramount consideration in the issue of planning and licensing arrangements for the disposal of wastes associated with mining operations. In this con- text the disposal of liquid tailings is a difficult and controversial problem with regard to environmental surface disposal. The paper outlines the use of Information Systems for decision support in the safe and environmental disposal of liquid tailings linked to conventional coarse refuse operations. This offers both an economic and an aesthetic approach to a historical perception of waste tipping in the underground coal extraction industry. The paper will demonstrate a prototype system that incorporates multimedia facilities which include data such as; voice comments, site photography, site plans and fluid flow circuits.

Jan 1, 1996

By C. M. Acuña

At the Chuquicamata Division of Codelco-Chile high arsenic concentrates are produced, which at the smelter are processed via the Outokumpu Flash Furnace and Teniente Converters to obtain copper mattes. In the case of the Teniente Converters the production of matte grade near white metal composition is a common practice since the eighties and provided in the pyrometallurgical route no appropiate measures are taken, penalties have to be paid because of arsenic content in the anodes. During smelting huge volume of slag is produced and elimination of arsenic by slagging at this step is not economically attractive. Although during fire refining is possible to eliminate arsenic by use of mixtures of calcium and sodium carbonates this alternative is expensive, takes long process time and decreases the lifetime of the refractory lining. In spite of these facts a reasonably way to control arsenic in metal, and therefore in the anode, is taking, action in the converting step. The effects of oxygen and arsenic content in metal, arsenic in white metal and basicity index of the slag upon the distribution coefficient of arsenic between metal and slag were investigated at pilot and industrial levels. The best results are obtained for metals around 7,000 ppm oxygen and 0.3 basicity index slag, which results in a 5.7 distribution coefficient for a 5,800 - 7,100 ppm arsenic content in white metal, 18%-24% CaO slag at 1473 - 1523K. Furthermore, no significant/visible refractory wear has been realized.

Jan 1, 1999

By J. Nagy, D. W. Mitchell, E. M. Murphy

In 1957 research was initiated in the U.S. Bureau of Mines experimental coal mine near Pittsburgh, Pa., to study factors affecting foam generation and transport, to evaluate the effectiveness of high-expansion foam for controlling mine fires, and to develop techniques for applying the method under U.S. mining conditions. These investigations showed that high-expansion foam containing at least 0.2 oz of water per cu ft of foam is effective in controlling experimental underground fires burning coal, wood, and oil. Sometimes the fire was completely extinguished, but more often, it was brought under sufficient control to permit either a direct attack on the fire with a stream of water or loading of the hot material into cars. A progress report' prepared in July 1958 summarized the initial achievements of the USBM experiments. Since then other phases of the foam-plug method for attacking fires have been studied in the laboratory and in the mine. Previous studies by British engineers' of the foam-plug method for fighting mine fires indicated that high-expansion foam was effective in controlling experimental timber fires in an underground passageway. Their subsequent workx-1 pertained to the practical aspects of fighting large fires within a mining area with a foam-plug. CONTROLLING EXPERIMENTAL FIRES In the USBM tests foam was formed by spraying a dilute solution of a foaming agent on a metal or cotton net of 1/8 to 1/4-in. mesh. Air passing through the continuously wetted net forms bubbles of 1/2 to 11/2-in. diam and produces a honeycomb of foam that fills the passageway. Under the ventilating-air pressure, this light-weight plug moves forward through the passageways, around sharp corners, and over obstacles. as illustrated in Fig. 1. High-expansion foam was transported to a wood fire, an oil fire, and 13 coal fires. Figs. 3 and 4 show a typical coal fire before and after attack with foam. In 12 of the 15 experiments the fire was brought under control when the water content of foam was 0.2 oz or more per cu ft. A fire was considered controlled when the flames were quenched and observers could cross the area without wearing breathing apparatus or protective clothing. In the other three experiments, conducted when the water content was less than 0.2 oz per cu ft of foam, the flames were retarded but the fire was not controlled. Coal fires have been attacked successfully by foam introduced at points varying from 155 to 1010 ft from the fire. The time of burning in coal beds 10 in. thick ranged from 11/2 to 5 hrs or more. Most of the experimental fire beds were 15 ft in length. However, in one experiment a floor fire 25 ft long and 5 ft wide was constructed $5 upwind from another fire 15 ft in length; in another instance, the fire was 100 ft long and 5 ft wide. Foam was applied to the fires for periods ranging from 7 to 36 min. The time required for foam application depends on the extent of the fire, time of burning, water content of foam, foam velocity, and degree of fire control desired. In addition to the coal fires, foam was transported to a fire covering 45 sq ft, produced by 15 gal of oil burning in metal trays on the floor. The foam extinguished the oil fire in about 1 min. In one other test, the burning of 1100 lb of dry sawmill slabs stacked in open cribs 4 ft high and 16 ft long was brought under control by foam in 2 min. Composition of Gases in Return Air: In several of the experiments samples of the return air from fire zones were collected; composition of the atmosphere before, during, and after foam application was then determined. Because of condensation in the relatively cool sampling tube, the amount of water vapor was not determined. Analyses showed that concentration of carbon dioxide and combustible gases increased as the foam began passing over the fire. This resulted from the decrease in the volume of air when foam generation started and from the formation of gases when water reached the fire.* The quantity of gases generated would not be greater than that from an equivalent amount of water applied directly to the fire. The highest total concentration of combustibles (CO, CH1, and H2 mixture) obtained during the experiment was about 2 pct; this occurred 6 min after foam reached the fire. This atmosphere was nonex-plosive, but calculations show that if the air flow were reduced to about 5 fpm and if the rate of gas liberation from the fire remained constant, the mixture would be explosive. The use of foam on a fire in all probability would affect the normal ventilation of a mine. If the mine is gassy, this factor must be carefully considered before the foam is applied. APPLICATION OF THE FOAM-PLUG TECHNIQUE IN MINES Equipment and procedures for applying the foam-plug methods must be adapted to the prevailing conditions at a particular mine. Some factors to be considered in developing equipment are: size or extent of the mine, dimensions and number of entries, ventilation system, mining methods, haulage facilities, availability of water, amount of methane liberated, and existing fire-control apparatus. • In most experiments the initial air velocity of 200 fpm decreased to 50 to 100 fpm as the foam plug increased In length.

Jan 1, 1961

By P. Radziszewski

"The comminution energy curve is a profoundly simple graphical technique that displays detailed operating efficiency information for industrial comminution processes. The database underlying the methodology has recently more than doubled, to now contain a substantial fraction of the international comminution output (1.7 billion tonnes of rock per year) across more than 8 major commodities. This increase has deepened the analytical capabilities and effectiveness for assessing comminution circuit performance in relation to comparable operating mines. This paper will explore how the energy curve methodology can be used to examine the ability of stirred mill technologies to increase efficiency.Specifically, this paper explores how the energy curves methodology can be used to present energy efficiency gains achieved at three mines employing a stirred mill technology under different duties. The first of these cases studies was conducted by Rosa (2014) who compared the performance of two ball mills operating in parallel with a Vertimill in the regrinding circuit at the Samarco Iron project in South East Brazil. The Vertimill was found to achieve the same product specification while consuming 40% less energy. Brissette (2010) investigated the impact of grinding media on the performance of both ball mills and Vertimills. The energy savings achieved varied from 10% to 40% for the ball mills and 30% to 60% for the Vertimills. Lastly, Bergerman (2012) investigated the operating conditions of the Sossego regrind circuit from 2006 to 2011 against design specifications and laboratory testing. The operating work index of this circuit varied from 5.2 kWh/t to 44 kWh/t over this 5 year period. The full suite of energy curves"

Jan 1, 2016

By Frederic Carter

THE gold, silver, copper alloys have been the subject of several fairly complete investigations by Jänecke, Sterner-Rainer1 and others, and indeed it would seem as if almost too much labor had been expended on them when one thinks of the numerous other ternary alloys calling for more light; however, the combinations of the three metals are actually so widely used in jewelry that they merit perhaps the work done on them. There are a few properties of importance and interest not treated by the authors mentioned which the writer investigated some little time ago, and therefore he has ventured to put on record the results of some of his tests made at that time. He has chosen, as being the two series of most importance to the jeweler, only the 14 and 18-kt. golds, so the subject is by no means so inclusive as that previously treated. As stated, this paper is merely a record of tests made in a practical manner on two useful series of alloys, and is not at all a critical study of their properties. 14-KARAT ALLOYS These alloys are important because they are the most generally used in 14-kt. jewelry; by changing the proportions of silver and copper there are obtained all shades of color from the green of the alloy containing gold and silver but no copper, to the red of the alloy containing gold and copper but no silver. Many 14-kt. gold alloys are made with the addition of zinc to the three metals mentioned here; the added metal does not appreciably alter the color of the alloy nor has it, in general, much effect on the working properties; it may, however, prove useful as part of the zinc added may act as a deoxidizer and render the alloy free of gas. It is not a necessary addition because with proper precautions all the 14-kt. gold alloys containing only silver and copper in addition to the gold can be made free of gas and capable of being cold rolled without cracking. The alloys in which approximately equal quantities of silver and-copper

Jan 1, 1928

By C. C. Harris Discussion by B. K. Loveday

B. K. Loveday (National Institute for Metallurgy, Johannesburg, Republic of South Africa) - The paper and subsequent technical note' describing a method of determining the parameters of the three-parameter size-distribution equation developed in the paper were read with much interest. This equation was also used at National Institute for Metallurgy (NIM) to describe size distributions in grinding tests, because it was necessary to have a single equation to describe the size distribution at any time during a test. A graphical method also was used to determine the three parameters, and the use of this method as an alternative to Professor Harris's latest method is discussed here. The three-parameter model can be expressed as follows: Eq. 1 can be rearranged and transformed to Yield a linear reiationship between Y and X (transformed) log

Jan 1, 1970

By C J. Moran

The Gladstone region, as one of the most industrially intense regions in Australia, uses significant quantities of fresh water. Awoonga Dam, situated on the Boyne River, is the only major source of water in the region. The current typical annual usage is 53 GL (Porteous, 2006) and approximately 80 per cent of the water is used by heavy industry (Gladstone Area Water Board, 2004). Until relatively recently, there has been ready and easy access to raw water for industrial use. The recent drought, which resulted in severe water restrictions in 2002 and 2003, emphasised the importance of water for a dominant industrial region like Gladstone. Although now in the process of changing, the typical contractual arrangements in the past have provided little financial incentive for efficient water use. From research undertaken on potential water reuse opportunities, several key questions have emerged related to water management in an industrial region such as Gladstone. This paper highlights these key questions, presents findings from recent regional strategies and assesses the potential for water reuse. Even though there is no clear-cut financial incentive for reusing water, there could be stronger regional and risk mitigation drivers for doing so. Initiatives to incorporate adaptive capacity through collaborative industrial synergies would allow for robustness and resilience in water security, leading to long-term sustainable water management across the Gladstone region.

Jan 1, 2006