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By William A. Fuchs

A study of carbonaceous ore at the Santa Fe mine (Corona Gold Inc.) shows that there is no quantitative relationship between organic carbon content and preg rob, although much of this material preg robs. However, there is a relation between K20 and preg rob. Preg rob generally occurs only in those samples with greater than 2% K20. X-ray diffraction and chemical . studies show that the critical factor is the illite content of mixed (possibly interstratified) illite-smectite. Apparently illite, at a certain threshold, "geo-activates" the carbon. The potential for easily monitoring preg rob using a gamma ray spectrometer is discussed.

Jan 1, 1990

By M. Olper

Today, copper production from direct leaching of oxidized copper ores followed by solvent extraction-electrowinning (SX-EW) accounts for about 15% of the total primary world output. SX-EW is a well-accepted process with an operating cost in the range 16-20 cents/lb. copper for small and medium size plants, depending on the plant size and local conditions. However, this technology presents some drawbacks that affect the operating cost and cause environmental concerns. ENGITEC and Paques Bio Systems have developed a new process that avoids the solvent extraction step and operates the copper electrowinning step at a lower cell voltage because of the depassivation of the anodic reaction. The consequence of this new concept is that the direct operating cost is in the range 10-12 cents/lb. copper. This new process is composed of the following steps: ? Selective precipitation of copper from leach solutions by biogenic H2S, yielding CuS and regenerating acid ? Leaching of the CuS with a ferric fluoborate solution to dissolve copper and produce elemental sulphur that is recycled back to the H2S biogeneration step ? Electrowinning of copper fluoborate solution in a diaphragm cell with the ECUPREX® Process, producing copper cathodes and regenerating the ferric fluoborate solution to be recycled back to the leaching step ? Biogeneration of H2S from the elemental: sulphur generated during the leaching step, with the nutrient source for the anaerobic bacteria selected form a wide range of organic substances and/or some industrial by-products containing carbon and hydrogen This paper describes all process steps with particular reference to the biological H2S generation technology. Also discussed' is the capability of the ECUPREX® Process to treat copper sulphide concentrates and copper matte.

Jan 1, 1999

By Qinghai Pang

"With the increasing proportion of bituminous coal in blend coal, the safety of blend coal during pulverization and transportation is gradually being paid more and more attention. Therefore, the explosivity of bituminous pulverized coal (PC) with different volatile content from 25 to 38% was studied by measuring the combustion flame length after its injection into a glass pipe with the heat source installed in the center. The results indicated that high volatile content bituminous PC is apt to have higher explosivity. By blending different bituminous PC with 10% anthracite, the explosivity of bituminous PC showed a positive correlation with the proportion –OH radical. However, different bituminous PC seemed to have the same explosivity when the addition of anthracite increased to 20%. With the further increasing proportion of anthracite to 30%, the explosivity of bituminous PC with high –OH proportion became negligible while a weak explosivity of high –CH3 proportion bituminous PC still remained.IntroductionWith the increasing iron ore prices and decreasing steel prices, it has become critical for iron and steel enterprises to control the cost in ironmaking and steelmaking process. Blast furnaces (BF) are the main consumer in ironmaking process, which occupies 70% fuel consumption of total steelmaking process [1]. In this circumstance, any means necessary is taken by BF operators to lower the cost of iron in production. Coke and iron ore are the main expense in this process, who takes up a very high proportion in total cost. Pulverized coal injection (PCI) is the most efficient way to reduce coke ratio, which replace coke with relatively cheaper PC.At present, most of BF is injected with blend coal in the consideration of decent combustion property and quantity of heat. Simultaneously, bituminite and anthracite blending is an effective method to obtain blend coals with required composition and performance, such as volatile and ash content, etc. Nevertheless, a very huge gap was found between the price of bituminous coal and anthracite in some regions of China, in which the price of bituminite can be just 70% of the price of anthracite. Thus, iron enterprises in these regions attempt to possibly amplify the proportion of bituminite in blend coal. Increasing proportion of bituminite results in higher volatile content in blend coal, by which the safety of blend coal during pulverization or transportation was deteriorated.Relatively, coals with higher volatile content usually possess stronger explosivity, which means that volatile and explosivity may related to some extent. However, the relationship between volatile and explosivity is not of certainty for some PC with high volatile content around 40% was found to be inexplosive in comparison to the coals with lower volatile content. With the increasing proportion of bituminous coal in blend coal, investigations on the factors of PC explosivity have become more and more important. Therefore, bituminous coals with different volatile content were selected. The explosivity of blend coal and its relationship between volatile content and functionality was investigated in this research."

Jan 1, 2014

By Georgina De Micco

The National Commission of Atomic Energy is investigating a suitable physicochemical process for the conditioning of spent nuclear fuel and treatment of the scrap of research reactors of the Al-UxSiy type. A possible way of processing is through dry chlorination of the cladding with the purpose of selective separation of the aluminium from the remaining elements such as Fe, Ni, Zn, Cu, etc. transforming them into volatile chlorides. Some important advantages of this method are the thermal stability of the chlorides that allow the easy separation of the halides by physical methods and the low volume of radioactive waste generated. The interactions in the following systems were studied in the range of temperature between 150º-500°C: Al-Fe, Al-Ni, Al-Cu, Al-Zn, Cu-Zn and the pure metals. We found that the reactivity was different depending on if the elements were alloyed or separated. The separation factors of the systems under study were determined. Nickel is perfectly separated from aluminium for all temperatures, whereas good conditions for copper separation were achieved below 400ºC. In the case of iron, complete isolation was never attained. However, by decreasing temperature to 150ºC it is possible to obtain aluminium chloride with less iron content. The separation of zinc from the product was also difficult. It was detected that zinc chloride volatilization decreases when other chlorides were present, for example cooper chlorides. In the Cu-Zn alloy, zinc chlorides remained in the condensed product due to interactions with copper. The samples were characterized by scanning- electron microscopy (SEM), X ray diffraction (XRD) and atomic absorption.

Jan 1, 2006

By G. R. Palmer

The success of future electric vehicles will depend greatly upon the power supply choices made today. Research is presently being conducted by automotive engineers and electrochemists to determine what battery type may be the most promising. Not only are product production and application efficiencies being evaluated but also environmental concerns of reclamation and recycling. Rechargeable batteries using nickel-metal hydride electrodes are strong candidates for these electric vehicle applications. The U.S. Bureau of Mines is investigating hydrometallurgical technology that separates and recovers purified metallic components present in nickel-metal hydride battery scrap. Sulfuric, hydrochloric, and nitric acids are all capable of dissolving the battery electrode alloys given the proper operating conditions. Solvent extraction of the leach solutions using D2EHPA removes iron, and selective precipitation shows promise of recovering the other metals in the H2SO4 and HNO, systems.

Jan 1, 1994

By Z. Smieszek, Z. Szota, P. Gajowski

"A new method for measuring the total quantity of suspensions contained in the electrolyte during copper electrorefining has been developed by the Institute of Non-Ferrous Metals, Gliwice. Electrolyte purity, and the suspensions content in particular, is of essential importance for the quality of electrolytic copper produced during the process. Suspensions contribute to the increase of slime impurities in electrolytic copper and increase losses in noble metals. Up to now, the laboratory method has been used for the· process control which provides analytical results with considerable time delay. Therefore, it is useless for the process control.The measuring method developed enables continuous measurements of a suspensions content directly within the stream of the flowing electrolyte. The principle of measurement is based on changes in optic properties of the electrolyte with varying suspensions content.1. IntroductionIn copper electrorefining, it is essential that the final product quality be maintained. If suspensions are present in electrolyte, the content of slime impurities in electrolytic copper, (such as Pb, Ag, Bi, Sn, Sb, and As), increases which can result in the occurrence of the so-called slime dendrites on cathodes, thus debasing the quality of the product. As a normal suspension content in electrolyte, the contents in the order of several mg/l are considered, usually not more than 5-6 mg/l, while contents exceeding 20 mg/l are referred to as an alarm state. Suspensions present in an electrolyte are usually a light fraction of anodic slime whose main components are metallic silver, lead sulphate, complexes of antimony and arsenic, and sometimes even calcium sulphate; they are mainly composed of very small particles of lead sulphate and antimony complexes. Sometimes - - in case of alarm states - - the so-called ""wandering slims"" can be observed, which are composed mainly of arsenic and antimony complexes. These ""wandering slims"" make a serious technological disturbance. In normal operating conditions of the electrorefining plant, an increase of suspension content can result from such reasons as crack of filter cloth in a slime filter, turbulent flow of the electrolyte, anodic passivation, aeration of the electrolyte, and improper servicing of an electrolytic tank. It is necessary to continuously control the suspensions content in electrolyte for proper electrorefining."

Jan 1, 1989

By J. P. Constantinea

The use of fluidized beds for the roasting of zinc sulphide concentrates marked a milestone in the electrolytic production of zinc. Stable operation of a fluidized bed for zinc roasting requires a particle size distribution that minimizes the risk of defluidization and helps control carryover to manageable levels. However, the understanding of the roasting process is limited, and changes in operating conditions mainly rely on intuition, experience, and trial and error. A research program has been initiated at UBC to study the phenomena that influence the particle size distribution of fluidized bed zinc roasters. In preparation for the experimental phase, this paper reviews the current literature on the phenomena that affect the particle size distribution during fluidized bed roasting and other fluidized bed processes.

Jan 1, 2002

By T. S. Piwonka

Modeling the solidification of shaped castings has progressed beyond the initial problem of determining the correct heat and fluid flow relationships which describe the solidifying castings. Today the challenge is to describe second order effects which determine the ultimate quality of the casting. The challenges to the modeling community posed by the needs of today's foundries for models that work are discussed, with some examples of current modeling problems.

Jan 1, 1992

By Kanchan Mondal

"Methanol, lower hydrocarbons, CO, and HCOOH formation have been by the reduction of CO2 with H2. Un-catalyzed electro-reduction requires a significant overvoltage. An alternate route has been conceptualized. Production of hydrogen from water can be achieved by chemical oxidation of a metal in water followed by oxidation of the hydronium ion by the released electrons to form hydrogen radical. It is hypothesized that circumventing the problem of the formation of hydrogen molecule is essential while having the hydrogen radical to react with CO2 forming methanol, etc. This may be possible by a bimetallic catalyst acting as a galvanic couple, wherein one metal acts as the electron donor for the production of hydrogen radical while the other acts as a catalyst for the reduction of CO2. This may enhance the reaction rates. The current concept circumvents the need for an external electric field unlike the electrochemical process.IntroductionUtilization of carbon dioxide as a raw material, not only as carbon sources but also as useful chemical feedstock is a more holistic approach to reduce air pollution by flue gases (1-3). Several methods have been proposed to maintain the concentration of atmospheric CO2 or to reduce and recycle it. One of these is the chemical fixations using catalysts. The conversion of CO2 to methanol by hydrogenation over copper containing catalysts is one of the most widely studied subjects in this area. The limitation in this reaction is the low conversion of CO2."

Jan 1, 2008

By Susanne Pignolet-Brandom

Reflected light microscopy scanning electron microscope energy dispersive spectroscopic analysis and backscatter electron image and electron microprobe chemical analysis have been used to study lead sinter and lead blast furnace slag. These studies provide invaluable information on the phases present their intergrowths, and their chemical composition. Such information increases the understanding of the nature of pyrometallurgical processes and the behavior of minor elements during these metallurgical processes.

Jan 1, 1987

By Robert G. Telewiak

During the past few years, the international nickel industry has taken some important steps to respond to conditions of global production overcapacity, relatively flat demand and low prices. These include the implementation of major cost reduction programs by most producers, closure of some high cost operations and the establishment of the Nickel Development Institute. Consumption in the western world increased by about 7 per cent in 1987 compared to 1986, supplies were less than demand, inventories were low, and late in the year prices increased dramatically. By year-end 1987, most producers were operating at, or close to, their effective capacities. Nickel demand is expected to increase to the year 2000 at an annual rate of about 1.7 per cent, led by increasing usage in the stainless steel sector. If this rate of growth is realized, then there will be need for the effective capacity of the nickel industry to be increased. Producers in Canada have put considerable effort in the past few years into reducing costs - with impressive results. Mining costs, in particular, have been reduced dramatically. While production is still less than the peak years of the yearly 1970's, it has increased substantially from levels of the early 1980's. Over the next few years, production is expected to increase slowly. A key determinant of the level of production in the 1990's could be the effect that regulations on sulphur dioxide emissions have on limiting production.

Jan 1, 1988

By S. Katz, V. Stanek, K. L. Moore, E. D. Larsen, D. E. Clark, P. E. King

"Cupola melting is a complex physical and chemical process having a number of nonlinearities which make conventional process control difficult. In addition, sensors for both inputs and outputs of interest to the foundry operator are often difficult or impractical to apply in a production situation. The present work is an effort to control the process using both intelligent and conventional control techniques as appropriate. Neural networks are used as an inverse process model in a cascade, feedforward controller in conjunction with a finite difference model of the cupola. A separate implementation of the neural net serves as a stand-alone visualization tool; it can operate on a laptop computer and is a useful tool for the cupola operator. IntroductionThe goal of the present work is to develop a controller to improve the efficiency of cupola melting. Although cupola melting as a process has a long history, automatic control has been elusive because the process has been poorly understood. The purpose of this four-year program, which has been underway for about six months, is to develop a controller for the cupola process using intelligent and conventional control methods.The Cupola ProcessThe cupola furnace [1,2] is one of the oldest processes for making cast iron, and is still the dominant method. It takes the form of a water-cooled vertical cylinder, as large as 4 m in diameter and 20 m tall. The charge consists of scrap metal, alloying ingredients, limestone, and coke, which serves as fuel; it is composed by weight and fed through doors near the top of the cupola. Air, usually heated and often enriched with oxygen, is blown in near the bottom through tuyeres extending a short distance into the interior of the cupola. As the coke is consumed, the charge drops and melts. A continuous flow of iron emerges from the bottom of the furnace, at rates as high as 100 tons per hour, and. is transferred to casting lines in the foundry. The exhaust gases are drawn from the top of the cupola, where they are processed to meet pollution standards."

Jan 1, 1994

By Daniel Kittelty

A fully instrumented laboratory electrowinning cell has been used to produce nickel cathodes from synthetic solutions containing various impurities in order to evaluate the effects of both metallic ions and organic reagents (from prior solvent extraction and other processes) on the quality of the electrodeposited nickel. The conditions used were typical of those employed in industrial electrowinning operations. The impurities were found to alter the crystal size and shape, induce the development of hydrogen pits on the deposit surface, incorporate as metal hydroxide crystals in the deposit, and alter the internal stress and current efficiency. These effects have been interpreted in terms of previously established relationships between the solution composition and the physical properties of the cathodes. The incorporation of the common metal impurity ions into the deposit have been interpreted in terms of a mass transport controlled reduction or precipitation reactions. In particular, a low concentration of aluminium ions resulted in an initial highly deleterious effect, which was replaced by a positive influence at higher concentrations. A model which involves the buffering effect of the aluminium on the pH at the cathode surface has been proposed.

Jan 1, 2003

By Federica Paglietti

In this work is presented SEX (Structural & Elemental X-Ray Instrument), the first spectrometer completely portable which make non-destructive X-ray fluorescence and diffraction analysis, in contemporary and in real time. This instrument has been realized using miniaturized detectors, the same model installed on the mission Pathfinder NASA, and X-ray microtubes. SEX allows the chemical and mineplogical characterization of all kind of solid materials and allows to make chemical stratigraphy and liquids analysis.

Jan 1, 1998

By Dan Michaelsen, Warwick Stewart

"PT Kaltim Prima Coal (KPC) is a large-scale truck and shovel operation mining thermal-coal in East Kalimantan, Indonesia. The operation produces 15 million tonnes of coal and mines over 120 million bank cubic metres of overburden annually. Approximately 35 percent of the waste rock is classified as potentially acid forming. Acid drainage must therefore be managed to prevent acid formation from spoil dumps and mined-out areas.KPC aims to prevent acid production in dumps by covering potentially acid forming spoils with materials identified as non acid-forming. The covers, built to engineering standards, minimise the flux of oxygen and water to pyritic spoils, thereby controlling the oxidation reaction, and reducing ARD discharge to negligible rates. Cover designs and cover materials vary according to stability, materials availability, equipment availability, and cost effectiveness. A modified field net acid generation (NAG) test procedure has been developed at KPC to identify and segregate overburden geochemical types. This paper discusses the ARD management strategies and operational procedures adopted by KPC to manage potentially acid forming waste rock. The development and field application of the NAG procedure at KPC is presented in a companion paper. Analytical"

Jan 1, 1999

By Nickolas J. Themelis

The role of copper in the economy will not diminish in the 21st century. Following the tenets of industrial ecology, production and use of copper must take into account both human needs and also how to minimize "collateral" effects on the environment. Dispersive uses will be phased out and post-use recovery of copper will increase. This will result into an advantage for smelting processes that can accommodate mixed metal scrap and waste streams. The bath smelting processes of Noranda and Mitsubishi will continue to make progress but the dominance of the Outokumpu flash smelting will not be challenged until the Noranda reactor overcomes the obstacles to the direct production of copper, thus eliminating the need for a converter.

Jan 1, 1999

By P. N. Anyalebechi

A comparative study of the mechanical properties of automotive steering knuckles produced by three different shape-casting related processes has been conducted. It involved the characterization of the tensile and fatigue properties of aluminum alloy A356 knuckles produced by the vacuum/pressure riserless casting (VRC/PRC), pressure counter pressure casting (PCPC), and the hybrid Cobapress (a casting-forging) processes, in accordance with the appropriate ASTM standards. Surprisingly, the knuckles produced by the hybrid Cobapress process exhibited the lowest strength. For example, the average 0.2% yield strength of the Cobapress knuckles was 31 MPa and 40 MPa less than that of the VRC/PRC and PCPC knuckles, respectively. However, between stresses of 150-200 MPa, the fatigue lives of the VRC/PRC, PCPC, and Cobapress knuckles were comparable. But above 200 MPa, the Cobapress knuckles exhibited the lowest fatigue life. The observed differences in the mechanical properties are attributed to the inherently different microstructures of the different knuckles.

Jan 1, 2009

By Jian Li, Guo Chen, Bingguo Liu, Hongying Xia, Jinhui Peng, Libo Zhang

"Decomposition of ammonium tetramolybdate to prepare Mo03 using silicon carbide crucible in microwave fields was investigated. The results were analyzed Using TG-DTG and X-ray diffraction. Meanwhile, the effects of heating rat, material thickness, socking time, socking temperature on the structure of preparing Mo03 were studied. TG-DTG curves show that the decomposition process of ammonium tetramolybdate is only one stage, in the temperature range 300-350°C, whose begin to decompose when temperature increases beyond 300°C. The molybdenum trioxide was prepared by thermal decomposition. The quality ofMo03 was not affected under the heating rat is 12°C/min. It was beneficial for decomposition ratio with the lower material thickness, longer soaking time, and higher soaking temperature. XRD curves showed that it is viable method for preparation of Mo03 by decomposition from ammonium tetramolybdate in microwave fields.IntroductionMolybdenum is widely used in national defense, aviation, industrial and agricultural production as rare refractory metal. Molybdenum trioxide is vital raw materials for the process of preparation of molybdenum. The traditional production technology of molybdenum oxide is that ammonium tetramolybdate is calcined in rotary kiln or 4-tube furnace [J,2J. But the longer production time, the higher production cost, the lower furnace thermal efficiency, and bigger the energy consumption, especially the powder is easy to leak, the working environment is poor by using rotary kiln [ 3 l _ The particle of molybdenum oxide is non-uniform by using 4-tube furnace because of the uneven temperature of every tube and the poor exhaust of boat bottom [4l _ However microwave heating is quick and uniformity, it is a meaningful research that the microwave is used in the process of calcining ammonium tetramolybdate."

Jan 1, 2013

By John Fallavollita

Conventional gas atomization produces powders that vary widely in size distributions and microstructures, thus making it very costly to produce powders tailor made in a narrow size distribution and microstructure. Furthermore, it is difficult to determine the relationships between atomizer operating conditions and resulting powder characteristics. The Impulse Atomization Process (IAP) was developed at the Advanced Materials and Processing Laboratory to produce powders with narrow size distributions. Powders produced by the IAP were reproducible and their sizes could be easily controlled by adjusting experimental conditions. Characteristics of Zn, Sn-Pb, AI-Cu, and Cu powders will be described to illustrate the flexibility of the process to tailor-make powders.

Jan 1, 1994

By W. Gong

Their outstanding thermal stability and high energy product make Sm(Co,Fe,Cu,Zr),-type alloys attractive for advanced applications. The near net-shape production of Sm(Co,Fe,Cu,Zr), bonded magnets make them potentially superior to any magnets made by sintering. Although pioneering work done by Shimoda et al. and other investigators provide insights on the proper compositions and process control of this alloy system, additional work is still necessary to improve our understanding of alloy behavior at various processing stages and to increase the production yield during powder processing. In this paper we report on the development of anisotropic Sm(Co,Fe,Cu,Zr), alloy powders for the bonded magnet application. Our focus is on the development of a moderate coercivity powder requiring a relatively low magnetizing field to charge the magnets to their optimum Br, Hci and BHmax. The magnetic properties are related to the evolution of the microstructure at various processing stages and the average particle size and size distribution of powders.

Jan 1, 1997