Search Documents

By Anita E. Lam

The thiosulfate leaching of gold generally requires the presence of a catalyst such as cupric tetraammine, Cu(NH3)42+, to obtain reasonable leaching rates and gold extractions. Unfortunately, this same catalyst that accelerates gold leaching also tends to accelerate thiosulfate oxidation to tetrathionate and other species. It is therefore imperative that a detailed understanding of the role of this catalyst and the factors affecting it is obtained. It is equally important for plant application that a method of assessing the catalyst be developed. In this work the role of the cupric tetraammine catalyst was studied using geochemical modeling for speciation prediction, thiosulfate leaching of gold ores, and chemical analyses of resulting leach solutions. It was found that the variables of pH, temperature, and the concentrations of ammonia, thiosulfate, and total copper all work in concert to affect the concentration of the cupric tetraammine species. It was also found that the presence of sufficient thiosulfate and cupric tetraammine was critical to the success of the leach.

Jan 1, 2003

By S. J. Kohut

Until recently SX-EW technology has only been used to produce conventional cathode for the cyclical commodity marketplace. Unlike electrorefining, SX-EW lends itself to the integration with the downstream manufacturing technologies for direct mine site production of value added products. The integration of SX-EW and downstream manufacturing results in the elimination of redundant process steps, the cost savings, and the access to value added product markets which can buffer the producer from swings in the cathode market. SX-EW production of copper powder and powder-based products has been demonstrated at the pilot plant level. The SX-EW process has been successfully redesigned to meet the more specific demands of engineered products. Challenges include the solution purity, the cell ventilation, the high current density operation and the product handling. Successful demonstration of mine site production of value added SX- EW products opens up new non-commodity marketplaces to the mining industry.

Jan 1, 1999

By Ronald J. Roman

The shrinking core model for coarse particle leaching has been generally accepted as describing the leaching of a copper oxide or sulfide ore. However, when a mixed oxide/sulfide ore-is leached this model can not be used in its simple form because at least two and possibly three separate leaching processes are occurring simultaneously (dissolution of oxide copper minerals, secondary copper minerals and primarily copper minerals). It has been impossible to isolate their individual leaching curves from the recovery/time curve generated by the column leach test. This paper describes a tests program carried out at the Groupo Mexico, Mexicana de Cobre's La Caridad operation in which the individual recovery/time curves for the leaching of copper oxide mineral, secondary copper mineral and primary copper minerals were developed from standard column leach tests. Once the individual recovery/time curves were developed scale-up of the column leach test results to the commercial heap leaching operation is possible by using the shrinking core model.

Jan 1, 1999

By Roberto Parra

The selective reduction smelting of Cu2O in Cu2O-FeOx-SiO2 melts has been studied at laboratory level, using as a feed a dead roasted calcine from a copper concentrate. The purpose of the study was to evaluate the kinetic and mechanisms of the indirect reduction with CO and the direct reduction with graphite from 1260°C to 1350°C. The reduction rate by CO was found to be 10-2 to 10-1 mole Cu2O m-2s-1. The graphite reduction macrokinetics for FeO and. Fe2O3 containing melts, was found to be a first order reaction with respect to the Cu2O concentration, with a kinetic constant of 104 to 10-3 s-1. The reduction rate was not sensitive to temperature nor to stirring, in the range studied. The measured reduction rate is almost one order of magnitude larger than the observed rate for the direct reduction of FeO.

Jan 1, 1999

By Joel K. Witt

San Manuel Oxide operations of BHP Copper, located in Southeastern Arizona, operates a leach-solvent extraction/electrowinning (SXEW) facility that produces high quality cathode copper from low-grade oxide ores. Permanent heap leaching and in-situ leaching methods accomplish the dissolution of copper from the oxide ores. Open pit mining and heap leach construction took place from 1985 to 1995. Run-of-mine oxide ore from the pit was hauled to the heap dumps and leached by the soaking cure and continuous irrigation method. Solution application to the heaps still continues and acid soluble copper recovery has reached 86%. This paper presents and discusses the current operating practices and innovations applied to the leach facilities to maximize copper recovery from the heap leached residue. Factors such as irrigation methods, solution chemistry, sideslope treatment, post curing, lixiviant acid strength, and "rice paddies" irrigation, will be discussed. Heap leach solution control and sampling methodologies will be also presented.

Jan 1, 1999

By J. F. Leroux

The Gaspé smelter at Murdochville, Quebec, Canada introduced concentrate injection into elongated Peirce-Smith converters sized 1.96m x 12.5m (13 ft. by 41 ft.) in 1996, and commissioned a large, converter-like bath smelting vessel in April 1998. The new vessel, which is sized 4.27m x 16.1 5m (14ft. by 53ft.) has several interesting features designed to effectively utilize bath smelting technology for the requirements of the Gaspé smelter. For example, the vessel can operate on concentrate injection at upwards of 60-80 tph rate on an instantaneous basis, can operate as a large Peirce-Smith converter, while it is also fitted with matte and slag tapholes much akin to Noranda Process reactor, and includes a novel cold charge addition system. The new technology will eventually allow the capacity of the plant to increase from about 300,000 tonnes of concentrate per year to over 350,000 tonnes of concentrate per year while improving sulfur capture.

Jan 1, 1999

By Zhang Yongzhu

Developments on bioleaching of low grade ores and refractory gold ores by T. Ferrooxidans in China are summarized. Effect of the ions on bacterial growth, bioelectrochemical reaction mechanism of sulfide minerals and bacterial reaction mechanism are also discussed.

Jan 1, 1992

By W. G. Davenport

Chapter 13 evaluated the %02 in blast, industrial oxygen and oil requirements for smelting FeSrCuFeS2 concentrates~ This chapter examines high eu grade CU2S-CuFeS2 concentrates the same way.

Jan 1, 2001

By E. T. White

The population balance is one of the basic relations for a:n:aIysing particulate minera1 processing operations. It is an exact relation. The principles of the population balance are reviewed and applications in the minerals industry discussed.

Jan 1, 1996

By J. D. Sloop

This paper discusses the current state of EAF dust recycling at AmeriSteel's Dust Processing Division in Jackson, Tennessee. Included are a brief history of the plant, a description of the facility, a description of the process, and operating data.

Jan 1, 2000

By Roberto Javier Santiago

The main properties of Calcium Carbide seem to be the grain size and the CaC2 content. This paper tries to describe the Calcium Carbide used in the South-American steel plants and how and where it is added.

Jan 1, 2006

By Michael B. Mooiman, David J. Kinneberg, Philippe Cettou, Leo W. Simpson, Pierre Ramoni

"The demand for high purity precious metals began with certain industrial applications having uncompromising requirements for quality and performance. As industrial uses proliferated and as the jewelry industry became increasingly sophisticated, the demand for high purity gold has reached the point where 99.99% is now the standard in the marketplace. A similar evolution is expected for other precious metals.In this paper, we examine both the production and use of high purity precious metals, specifically gold, silver, platinum and palladium. After defining what is meant by ""high purity"", we discuss the various analytical techniques used for measuring impurity concentrations. Next, we review process strategies employed by extractive metallurgists to produce high purity precious metals. Lastly, we describe some of the principal applications for high purity materials including thick films, thin films, bonding wire, thermocouples and jewelry manufacture.Precious metals have unique physical properties that, despite their expense (and the ever-continuing search for more economical alternatives), make substitution difficult if not impossible. These physical properties are dramatically affected by small concentrations of certain impurities. As long as manufacturers continue to demand quality and performance, there will be a need for high purity precious metals.IntroductionIn the precious metals industry, the qualifier ""high purity"" describes any specification over and above commodity grade. High purity specifications delineate lower limits on overall metal purity or upper limits on individual impurities or both. Sometimes, if these special requirements become commonplace, either because of improved refining technology or because of market pressures, yesterday's ""high purity"" material becomes tomorrow's commodity. This transition is now occurring with gold bullion and probably will soon occur with platinum and palladium as industrial use of these materials grows."

Jan 1, 1998

By Dean G. Heitt

"The Rain and SMZ mines from 1987 to 1994 produced a total of22.0 t of gold from a pre-mine reserve of 14.24 Mt of ore grading 2.13 g/t Au.Gold at Rain is hosted within the basal portion of the Mississippian Webb Formation. ·Mineralization is closely tied to the Rain Fault which is interpreted to be the main feeder for the deposit. Multiple collapse and hydrothermal breccia events provided permeability for the mineralizing fluids in the otherwise unreactive siltstones. Major alteration events include: decalcification and dolomitization of the Devils Gate Limestone; and silicification, baritization, argillization and oxidation of the Webb Fm. Six ore types based on XRD and visual rock chip Jogging have been identified: siliceous ore containing >40% quartz and <30% barite; siliceous-baritic ore containing mostly silica but >30% barite; baritic ore containing >40% barite; argillaceous ore containing >40% total clays (including alunite); calcareous ore containing mostly calcite and dolomite; and carbonaceous ore which has significant pyrite and organic carbon. Metallurgical testing of the oxide leach grade ores found that recoveries, on -1.3 cm crushed material, were greater than 70%. Results also found that Rain ore has strong grind dependency due to silica encapsulation.The Rain leach pad was commissioned in 1988, and to date 9.3·Mt at an average grade of0.65 g/t Au have been placed. Life to date recovery, through December 1995, is approximately 51 %, for a total of3.87 t of gold produced. Two major factors have contributed to the low leach recoveries at Rain when compared with the metallurgical testing: 1) More argillaceous ore than expected was placed on the pad especially late in the mine life and 2) approximately 50% of the tons placed were run-of-mine with no agglomeration."

Jan 1, 1997

By Ji-He Wei

The ESR of Cu-Cr-Zr alloy has been experimentally investigated. The remelting experiments have been carried out with different slag fluxes in the Cal, + Nal, CaF2 + ZrO2 and CaF2 + NaF + ZrO2 systems on an ESR furnace of 25kg capacity; using a water-cooled copper mould of 96.5 mm diameter, with the forged square bar electrodes of 50x50 mm2. The slag amount was taken to be 1.5 kg. The remelting current and voltage used were 1600-1800A and !5-25K, respectively. The influence of the slag composition on the stability of the remelting process and the losses of alloying elements (2r and Cr) has been considered and examined. The technologies of hot working and heat treatment of the ES ingot have been described and discussed. Some physical properties of the slag in a CuF2 + NaF + ZrO2 system and the remelted Cu-Cr-Zr alloy have been determined. The results indicated that with the slag flux of CaF2 + NaF + l0 mass % ZrO2 and the other operation parameters employed, a high quality ingot of Cu-Cr-Zr alloy may be obtained at the considerably high yields of Zr and Cr by means of ESR. For the remelted Cu-Cr-Zr alloy with a specified composition of 0.5 mass % Cr and 0.1 mass % Zr, the appropriate electrical conductivity, hardness and softening temperature are as high as 45-46S/m, HRB 82-84 and 550°C. respectively. The properties of the Cu-Cr-Zr alloy products are in accordance with and superior to the requirements and specifications of ISO5l82-l99l(E).

Jan 1, 2000

By F. M. Wang, J. P. Lin, G. Y. Tang, H. C. Zhou, Y. F. Liang, F. Ye

"Fe-6.5%Si alloy is a very excellent soft magnetic material compared with conventional Si steel (Si content ~ 3.5%), especially in high frequencies with reduced iron losses and noises. But it is hard to be fabricated due to its brittleness at room temperature. Dynamic electropulsing is applied to the cold rolled Fe-6.5%Si sheet during tensile deformation. Mechanical and microstructural properties are investigated with different electropulsing and strain rate. It is found that the yield stress decreases and the elongation increases dramatically with the application of dynamic electropulsing. It is indicated that the work hardening could be reduced with the dynamic electropulsing during deformation, which provides a promising way to fabricate this alloy sheet much easier.Introduction Fe-6.5%Si (weight percent, same as below) alloy has more excellent soft magnetic properties compared with conventional silicon steel (Si content ~ 3.5%), such as higher resistivity, higher permeability, near zero magnetostriction, etc. and exhibits much lower core losses and noises [1]. However, Fe-6.5%Si is very brittle at room temperature and hard to be fabricated in strip by conventional hot-cold rolling process [2]. This lack of low-temperature ductility has been generally attributed to structural ordering ofB2 and D03 phases [3]. Several methods have been developed to avoid its brittleness, such as chemical vapor deposition (CVD) [4], rapid quenching [5, 6], dipping and diffusion [7, 8], direct powder rolling (DPR) [9], etc. However, hot-cold rolling method is still of interest for industrial applications. In our previous work, this alloy can be cold rolled after certain thermomechanical process and heat treatment [10-13]. The cold rolled sheet exhibits some extent of ductility [11]. However, side cracks are common for the rolled sheet, it is very necessary to improve the ductility of this alloy by other technical applications."

Jan 1, 2012

By G. A. Bala

As part of ongoing research to define mechanisms of microbial enhanced oil recovery (MEOR), this work describes the activity of Bacillus l1chen1formis JF-2 (ATCC 39307) Mosurfactant against crude oils with varying compositions. Surfactant based MEOR improves oil recovery by lowering the oil/brine interfactal tension (IFT) therefore permitting oil to be displaced or solub1lized into the aqueous phase.? MEOR is an Enhanced Oil Recovery (EOR) process which allows for the introduction of chemical and miscible fluids, in the form of microbial metabolic end-products, through the injection of microorganisms into the reservoir or stimulation of indigenous reservoir microbial populations. These microorganisms represent a replenishable in situ source of acid, gas, biopolymer, solvent, or surfactant products which can be. supported and manipulated by the addition of simple and inexpensive nutrients to enhance the recovery of oil. Microbially mediated surfactant production represents one mechanism of MEOR. Bacillus licheniformis JF-2. has been used in a mode 1 MEOR system based on Berea sandstone cores (permeabilly .85 to 400 md) to examine surfactant based MEOR of medium to heavy crude oils (API gravity 38.1° to 17.5°). Enhanced oil recovery was achieved with all oils tested using either cell free culture supernatants or microbial suspensions as injectants with no detrimental effect to the oil. Spatial distribution of cells following mf?crobtal flooding was analyzed with scanning electron microscopy. Data indkate complete distribution of cells with a predominance of organisms located distal to the point of injection. There appears to be no sign:if1cant recovery trend with respect to oil composition.. The biosurfactant produced by Bacillus lichen1form1s JF-2 lowers the interfacial tension of all oils tested equally well.

Jan 1, 1991

By K. C. Liddell

"Cu/Ni multilayers exhibiting giant magnetoresistance were deposited from a single electrolyte under stepped potentiostatic control. To enable transport measurements to be made without remounting the multilayer film, we developed a novel method that involved plating on a thin metallic basal layer atop a rigid non-conducting Si substrate. Rotating ring-disk electrode techniques were used to monitor the composition and thickness of individual plated layers. Transmission electron microscopy confirmed that the interfaces between adjacent layers were sharp and that the structure of the layers was uniform throughout the film. Atomic force microscopy images indicated that the film's surface was smooth and free of defects.ELECTRODEPOSITION OF THIN MULTILAYER MAGNETIC MATERIALSI. IntroductionElectrodeposition of compositionally modulated films will in all likelihood continue to be used to produce the read heads for stored magnetic data. However, the next generation of head materials will require both improved sensitivity and reduced film thickness. Certain multi layers consisting of thin alternating ferromagnetic and nonmagnetic layers exhibit giant magneto resistance and consequently are promising candidates for read head applications. We have successfully made multilayer films with giant magnetoresistance that have total thicknesses as low as 25 nm, approximately 120 times thinner than the thinnest similar films reported in the literature. This paper describes early results from our work on electrodeposition and characterization of Cu/Ni multilayers, a model system with enhanced magnetic and mechanical properties, including the GMR effect. The structure and composition of the multilayers were determined using TEM, AFM, and electrochemical methods, and their magnetoresistance was measured by the standard four-probe technique. A novel method developed in this work enabled the transport properties of the ultrathin films to be measured reliably without the need to dissolve the cathode or handle the films. To provide a context for these results, short accounts of other work on giant magnetoresistance and multilayer electrodeposition are also included."

Jan 1, 1997

By Hidenori Okamoto, Katuto Itoh

"Nippon Mining & Metals' Hitachi Refinery refines 40% of the anodes produced at its Saganoseki Smelter & Refinery. Its current annual production stands at 180,000tons.The refinery always endeavors to increase productivity. One of the outcomes of its efforts is an originally developed automatic short-circuit detector used to inspect short-circuits between anode and cathode. The detector is designed to inspect the 56 pairs of anode and cathode in a cell by fluxgate sensors at once. It inspects 564 cells, automatically and un-manned, and gathers data to be put into a computer. The development of the detector led to a reduction of man-power and achieved a detection accuracy superior to that of a hand-held gauss-meter. In addition, statistical and historical processing of the data enabled early detection and early recovery of the cells with poor efficiency.The new system also contributed to raising the refining capacity and reducing the unit steam consumption, because it is possible to inspect even the cells covered with thermal insulation sheets.IntroductionInspection of cells is an important component of the operation management of a tank-house. At the Hitachi Plant, it used to be carried out by two workers who walked on and checked all the cells of its tank-house once a day to find out any short-circuits in the cells, using hand-held gauss-meters. They inspected about 33 thousand pairs of cathodes and anodes a day and removed nodules by hammers. This method had following problems:it needed much manpower.the walk on the cells sometimes deranged electrodes positions.there was radiation-loss connected with the inspection due tothe fact that the workers were obliged to uncover thermal insulation sheets on the cells while inspecting."

Jan 1, 2000

By Hongli Wen, Guangkun Shen, Qiong Deng, Xuling Chen, Min Gan, Xiaohui Fan

"In this research, pyrite cinder which contains 53.51% Fe and 0.54% Pb was processed by magnetic roasting separation to obtain a concentrate with 64.62% Fe and 0.56% Pb. The concentrate was then leached with hydrochloric acid to remove lead. Several technological parameters which may influence the removal efficiency were investigated: the mass fraction of hydrochloric acid, pulp density, the leaching time and temperature. On the conditions that the mass fraction of hydrochloric acid of 5%, pulp density of 30%, the leaching time of 30 minutes and leaching temperature of20°C, the lead content in the concentrate was reduced to 0.19%. The product was suitable for agglomeration and pelletization. Through the analysis of the lead distribution and phase change during the whole process, the mechanism of lead separation from pyrite cinder was analyzed.IntroductionPyrite cinder is rich in iron, which defines its most extensive and effective use as raw materials for iron making. However, some pyrite cinders contain much non-ferrous metals, which is detrimental for the iron making process. Lead, one of the harmful elements, will destroy the blast furnace lining. Besides, it causes pollution of the environment[1]. Therefore it is necessary to remove excessive lead before entering the blast furnace. To separate the lead from pyrite cinder, much research was done, including flotation, high temperature evaporation and leaching. High temperature evaporation consumed too much energy. The flotation was difficult to obtain high- grade iron ore concentrate[2]. Majority of the leaching was direct leaching of pyrite cinder, which was also difficult to get high-grade iron ore concentrate[3]. This article explored the magnetic roasting method to get high-grade iron ore concentrate, acid leaching method of the concentrate to remove excessive lead, providing guidance for the efficient utilization of pyrite cinder."

Jan 1, 2013

By V. I. Lakshmanan

"Historically flowsheets are developed for efficient separation of metals for economic recovery. With increasing emphasis on reduction, reuse and recycle (3Rs) efficient methods are sought to recover values from a variety of feeds where cost of collection, transportation, local consumer behaviour and regulatory guidelines dictate the development of economically viable flowsheets. Innovative understanding of potential market applications can provide means to develop value added end products. The paper with examples will discuss the use of innovative-separation technologies to obtain value added end use materials from secondary sources.IntroductionFlowsheets are developed for the efficient separation of materials of value for economic recovery. However with increasing societal pressures and regulatory initiatives for stricter environmental guidelines, there is strong need to provide focus to recover materials efficiently and economically in an environmentally accepted manner. North American industries are increasingly caught between demands for high technology value added products and responsibility for environment. An aspect that is receiving increasing attention is Design for Environment'. This incorporates a system wide approach for product design and incorporates environmentally preferable features such as recyclability, disassembly, maintainability, reusability and use of safe materials as part of a product's design objectives.The present paper with case histories will address innovative flowsheet development to convert wastes into recyclables value added products or for minimising generation of waste materials. Case HistoriesProcess for Separating Fibres from Composite Materials 1In the automotive industry, sheet molded compound (SMC) is used to produce panels, bumpers and the like. During the manufacture and at the end of life, considerable waste materials are generated which are potentially recyclable. Fibre reinforced plastics where fibre substrate impregnated with thermosetting resin, find applications in several manufacturing processes and are potentially recyclable at the end of life."

Jan 1, 1996