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By R. L. Miller

Oil -bearing metal sulfide sludges produced in treatment of an industrial wastewater, which includes plating wastes, have yielded to treatment by electrooxidation and hydrogen peroxide processes. The oxidation can be controlled to be mild enough to avoid decomposition of the organic phase while oxidizing the sulfides to sulfates. The pH is controlled to near neutral conditions where iron, aluminum and chromium(II1) precipitate as hydrous oxides. Other metals, such as lead and barium, may be present as sulfate precipitates with limited solubility, while metals such as nickel and cadmium would be present as complexed ions in a sulfate solution. The oxidations were found to proceed smoothly, without vigorous reaction; heat liberation was minimal.

Jan 1, 1992

By W. Persson

The first installation at a copper smelter of a Semtech OPC System for continuous, on-line production control of copper converting in PS converters took place in 1994. At present OPC systems are installed at 19 PS converters. The technology presents to the operator real-time information on the progress of the process he is controlling in the form of optical process parameters, thus facilitating dynamic process control. The optical process parameters are based on time- and wavelength resolved registrations of the light emitted by the off-gas flames and identification of correlation between these parameters and characteristic metallurgical process data. The present paper provides a description of the technology as seen by the furnace operators and a summary of operating experiences made during five years of full-scale, operation at various smelters, reviews influences from the technology on smelter operational practises and comments on recent developments as regards new applications of the technology.

Jan 1, 1999

By S. Motoiu

Data acquisition is widely used for controlling flash smelting furnaces. A Romanian smelter from which a large amount of data can be collected uses such a technique. A computer program was developed for interpretation of the data. Inputs to the program are the process data files. Abnormal data are identified using standard statistical techniques; they can be edited if necessary. The following methods can be used for the analysis: linear correlation (single or multiple), polynomial correlation or comparison of two average values. Time variation graphs and histograms can be displayed. The random balance method was used for determination of significant parameters influencing the process performance. Not all process parameters are recorded, and some of them are not even measured. The software can compute some of these parameters such as: air flow rate required and the oxygen content of the gas: exiting the reaction tower. The software was used for the interpretation of a large amount of process data. The analysis showed that the process did not operate properly at some times.

Jan 1, 1999

By Juha Järvi

Outokumpu Zinc Oy has two separate roasting lines with fluidized bed furnaces and waste heat boilers for calcine collection and heat recovery. During the last 30 years, zinc production in Kokkola plant has increased continuously and at the same time the raw materials have changed. Therefore, the waste heat boiler has been under continuous research and development. The waste heat boiler plays a significant role in the process and consequently the reliability and efficiency of the device is important for the effectiveness of the entire process. Many changes have been made to the boiler in the last decades. New radiation tube screens, tube bundles, and baffle-plate constructions have been added to the boiler and also rapping systems for the dust have been developed. The latest improvement to the boilers was a baffle wall, located in the middle of the radiation section roof in the first boiler, and baffle plates in the lower part of the convection section in the second boiler. The new boiler design and optimization were carried out using physical water and air-dust modeling as well as computational fluid dynamics. The modeling work agrees well with experiences in practice. The latest developments have increased the operating hours per year and the effectiveness of the waste heat boiler.

Jan 1, 2002

By Matthew Jeffrey

Leaching, cementation, electroplating and flotation are all electrochemical phenomenon. They are also key processes in the hydrometallurgical treatment of metals. Unfortunately electrochemical methods tend to be under-utilized when studying these processes and one possible reason for this is the confusion surrounding the large number of electrochemical techniques available. In this paper four former PhD students of Professor Ian Ritchie present an insight into how one electrochemical technique can be used to compliment rate/kinetic studies. The paper details how to perform the experiments, interpret data, and recognize complications with the results. Examples where this approach has been highly successful are presented, and include: cementation of zinc by aluminium, cementation of copper by nickel, cyanide leaching of gold and the cementation of gold thiourea by mild steel. The examples illustrate that this universal approach adopted by Ian Ritchie provides the key to understanding the mechanism of many hydrometallurgical reactions.

Jan 1, 2003

By Douglas Robinson

This paper describes technical work done to develop a Spouted Bed Electrode Cell into a commercially viable Electrowinning Cell; (a previous paper has been presented at the ECS meeting in Paris in May of this year, with a more general overview of the cell, [1]). The studies have included hydrodynamic tests to understand the criteria for the circulating flow of metallic beads in the cell, particularly in the region at the entrance to the draft tube, and electrochemical tests to find a suitable diaphragm for extended time electrolysis. Various patent pending features were developed including a double nozzle to allow for automatic stopping and restarting of the bed, an arrowhead shaped draft tube to control the flow of beads into the entrance to the draft tube, a roof-top shaped device to control the flow of beads out of the top of the draft tube, an overflow weir to allow the continuous recovery of beads from the cell, and a family of diaphragm fabrics for extended operation. Prior to the identification of the diaphragm material, short circuits would develop within a few hours. A pilot scale cell was operated for three days, with continuous operator attention, and then for ten days with operator attention only on day shift. The cell is currently advancing to the next stage of development which will involve continuous testing in a commercial copper electrowinning facility.

Jan 1, 2003

By L. Béjar-Gómez

The aim of this research work is to study and characterize the precipitates in structural microalloyed steel by transmission electron microscopy and analysis by low resolution. Microalloyed steel with niobium was produced by casting in an electrical induction oven of 25 Kg capacity. Carbon content in steel was less than 0.1 % and 0.036% of niobium. Steel was processed thermomechanically; reheated to 1250 °C and hot rolled on a laboratory mill to a 13.0 mm thick plate with a finish rolling temperature of 900ºC and a thickness reduction of 80% . This work shows what precipitates are present in steel, the type of precipitates and their morphology. Analysis by transmission electron microscopy of low resolution was applied to obtain the chemical analysis of precipitates and the matrix. Spectroscopy of dispersive energy (STEM - EDS) was applied to obtain the element profile of precipitates. Particles of precipitates of NbC were found; with cubic morphology and size from 70 to 130 nm, circular morphology and size from 10 to 70 nm, polygonal morphology and size from 10 to 80 nm.

Jan 1, 2006

By C. A. Landolt

Inco pioneered the use of tonnage oxygen in non ferrous metallurgy when it commissioned the first .industrial oxygen flash smelting process for the treatment of copper concentrates in the early fifties. This technological innovation was followed by other applications of technical oxygen. Inco is currently implementing a Sulfur Dioxide Abatement Program designed to reduce S02 emissions from the smelter by 60% in 1994. The new flowsheet includes new equipment for the oxygen flash smelting of Cu-Ni concentrates and for flash conversion of chalcocite. Oxygen smelting and converting technology will lead to a substantial decrease in use of fossil fuels and to generation of high strength S02 off gases suitable for efficient fixation in a new acid plant.

Jan 1, 1992

By Veronica Escobar

This paper presents results from a two month pilot evaluation of EMEW® technology at CODELCO Radomiro Tomic, in Chile. A prime focus in the test programme was to assess the technology?s capabilities to recover high quality copper from the Radomiro Tomic electrowinning tank house bleed stream. The EMEW® cell developed by Electrometals Technologies Ltd. tolerates substantially higher levels of contaminants than those found in conventional tankhouse, operating at high current densities while maintaining high cathode copper quality all the way down to low copper concentrations. To maintain high copper purity in a copper electrowinning (or electro-refining) tank house, a continuous bleed of solution must be taken from the tank house inventory to prevent build-up of contaminants, and resulting degradation in cathode quality. In an SX-EW operation, this bleed stream is normally recycled back to the solvent extraction circuit, but is occasionally sent to the raffinate pond to re-enter the leach circuit. Return of the bleed stream to the solvent extraction circuit creates a continually recycling load of copper in solution, which may reduce overall plant capacity and expansion potential. Return to the leach circuit has a similar effect, and methods to reduce its impact are always under consideration. The use of the EMEW® technology allows for direct and efficient recovery of near 100% of the contained copper instead of recycling. Tests were run at ambient temperature on bleed electrolyte using current densities which varied between 250 and 1100 amps per square meter, with copper concentrations between 38 and 1 g/l. A profile of maximum allowable current density with respect to concentration was developed, showing that high grade copper can be obtained at all levels of concentrations tested, by choosing an appropriate current density and electrolyte flow rate. The results of this programme show that the recirculating bleed electrolyte from an SX-EW operation can be converted into an expansion in copper production at a comparatively low investment cost.

Jan 1, 2003

By Tabbetha A. Dobbins

We report studies concerning the time frame for catalytic reactions between NaAlH4 (sodium alanate) and TiCl3 during high energy milling. Spectral features in x-ray absorption spectra were analyzed for samples milled for various times (0 minutes, 1 minute, 5 minutes, 25 minutes, and 125 minutes). A structural transition from Ti3+ to Ti0 is observed within the first 5 minutes of milling. The Ti0 structure persists for samples milled for times longer than 5 minutes?even after those samples underwent a subsequent single hydrogen desorption/absorption cycle. Samples milled for less than 5 minutes retain Ti3+. For samples milled for 1 minute, the Ti-K edge position shifts from Ti3+ to Ti0 after a single desorption/absorption cycle. However, the first coordination sphere around the Ti0 absorber occurs at longer distances for 1 minute milled sample. These results hint at the formation of Ti0 pure metallic clusters upon desorption/adsorption cycling of 1 minute milled sample. Previously reported x-ray absorption spectroscopy studies have demonstrated the structural transition from Ti3+ (in TiCl3) to Ti0(determined to be TiAl3 found at the surface of the alanate powder). Aluminum deficiency on the NaAlH4 lattice is responsible for controlling hydrogen absorption capacity. These time-resolved spectroscopy studies suggest the possibility for controlling aluminum deficiency, while still maintaining titanium activation of the alanate powder, by manipulating the coordination environment of the titanium dopant during the first five minutes of high energy milling. Specifically, a possible approach to mitigating aluminum deficiency during doping would be to introduce an alternative species to which the to Ti3+ catalyst would form a metallic bond after the TiCl3 has attached at the surface of the sodium alanate powder and before the Ti3+ forms the TiAl3 intermetallic species.

Jan 1, 2006

By Dale T. Peters

In the United States, the United Kingdom and numerous other countries, copper has long been the plumbing material of choice. This has been the case since the late 1920s in the United States and since World War II in the United Kingdom. However, in recent years the plumbing tube market has caught the eye of the chemical industry, and several plastic resins have been introduced to the marketplace as substitutes for copper in household plumbing systems. One of these, polybutylene tube, had so many failures in the United States that a class action law suit was filed, and the manufactures of this product were forced to create a trust fund of nearly one billion dollars to repair damages caused by their product. Chlorinated polyvinylchloride (CPVC), in rigid pipe form, on the other hand, has been mechanically acceptable albeit its recent introduction precludes the test of time enjoyed by copper tube in this application. This paper reviews the State of California's portrayal of copper's environmental effects and will be largely based on the data and information assembled by the Copper Development Association Inc. in its presentation to the State of California in August, 1998 in response to the State's Draft Environmental Impact Report for Chlorinated Polyvinyl Chloride (CVPC) Pipe for Use for Potable Water Piping in Residential Buildings. The paper is intended for use as a model for the use of other copper organizations and individuals in responding to similar situations.

Jan 1, 1999

By L. A. Barta

A new process for the leaching of chalcopyrite concentrates has been developed and tested in miniplant campaigns and locked cycle testwork carried out between 1996 and 1999. The process involves pressure leaching in a sulphuric acid solution, e.g. raffinate from copper solvent extraction. Iron in the feeds is precipitated predominantly as hematite in the autoclave, simultaneously with copper extraction. Gold and silver in the pressure leach residue are recoverable by conventional cyanidation, following flotation to remove elemental sulphur by-product. The results of recent miniplant tests and batch locked cycle tests are provided.

Jan 1, 1999

By Daniel Kim, Justin McAllister, Shijie Wang

"At the Kennecott Utah Copper Refinery, impurities in the electrolyte are being precipitated in the circulation system and form a hard scale in the piping. This scale must be removed periodically for proper electrolyte flow. Distinct layers of differing composition form as the operating conditions of the tank house change. Scale samples from the inlet and outlet pipes were analyzed to discover the nature of the precipitates. Each sample was sectioned and examined under optical microscopy and SEM. The composition of the scale was analyzed using ICP, XRD, and SEM/EDX mapping. The rate of deposition was determined by measuring the amount deposited on new pipes after elapsed time intervals. In order to determine how to minimize the formation of the scale, the mechanism was studied and the results are presented in this paper.IntroductionIn copper electrorefining, impure copper anodes are refined into pure copper cathodes. The impurities from the anodes are either insoluble and report to the slimes or soluble and dissolve concentrating in the electrolyte. These impurities are controlled by bleeding electrolyte from the system. Over time, the impurities combine to precipitate a hard scale on the surfaces contacted by the electrolyte. The scale causes problems with tank house circulation systems. In order for the refinery to operate properly, the scale must be removed periodically from the walls of the pipes. The first step to control the buildup of scale on the pipes is to understand the composition and the phases that are present in the scale."

Jan 1, 2012

By V. A. Bryukvin

A hydroelectrochemical technology has been proposed and experimentally proven for processing metallic gold- and silver-containing concentrates on the basis of copper and copper alloys obtained as a result of preliminary physico-mechanical upgrading of electronic scrap. The proposed technology is based on hydroelectrochemical leaching of scrap using reversible electric current and diluted nitric acid solutions, containing complexing agents, permitting complete separation of gold from the nonferrous matrix without involving gold in the process, and dissolving copper, zinc, lead and tin virtually without any emission of nitrose gases.

Jan 1, 2006

By Anders Salwén

In 1975 T. Nishizawa and A. Chiba reported on observed deviations from the ferrite-austenite local equilibrium in several diffusion couples based on the Fe-Cr system. In order to try to verify these results the austenite-to-ferrite transfonnation in a Fe-20 %Cr-Invalid Code [Fe-]-%Cr diffusion couple held at 1100 for 100 hours has been simulated. The simulation model is based on the postulated principle of maximum dissipation rate of Gibbs energy during transformation, which allows non-equilibrium interface conditions. Keynotes: Computer Simulation, Austenite-to-Ferrite Transfonnation, Diffusion Couple

Jan 1, 2003

By Steven C. Torma

The present article reviews some of the technologies available for recycling high-energy yield explosives loaded projectiles. These activities lead to reduction of military ammunition stockpiles and their conversion into commercial and industrial applications. The recycling technologies involve dismantling and separation of ammunition components into recyclable metals, plastics, paper and explosive materials. The metal 1 ic components will be sent to smelters, where they will be converted to products that can be used in a variety of industries, such as construction, automotive, housing and so on. Plastics and paper will be recycled and reused. Explosives will be recycled to be used for industrial purposes in the mining industry. Propellants (ammonium nitrate and ammonium perchlorate) can be ground to small particle size and treated to be used in the agricultural industry as fertilizer. In addition, some of the excess explosive material recovered in the demilitarization process may be incinerated to produce energy for steam production for heating purposes, or for production of electricity. Furthermore, this article reviews the developments in the bioremediation of explosive contaminated soils and industrial effluents.

Jan 1, 1994

By Keri Ledford, Stephanie Lin, Jason Nadler

Novel processes are being developed to fabricate thin copper thermal wick samples of a targeted porous microstructure. Structures of desired porosity, thisckness and pore size and distribution are achieved by tayloring the incorporation of sacrificial polymer beads in to slurry precursors. The thickness of the final structure is dictated by precisely controllable slurry application methods, such as spin coating. Ina subsequent heat treatment, th epolymer components thermally decompose and the remaining copper particles sinter to form a reticulated foam. The resulting microstructures are characterized in terms of porosity, permeability and specific surface area.

Jan 1, 2012

By Yuan Zeping

The Guixi smelter is the first Outokumpu flash smelter in China .It was commissioned on December 31, 1985. Originally, the smelter was designed to produce 90,000 tonnes of copper annually. After the implementation of oxygen enrichment and other modifications, the smelter will reach its anticipated annual capacity of 200,000 tonnes of copper in December 1999. This paper describes the performance of the smelter, the first phase modification project and the second phase expansion project which have made Guixi one of the best copper smelters in the word through the use of existing and innovative technologies.

Jan 1, 1999

By Jeff M. Kuhn

A new solvent extraction process for the removal of halides from zinc sulphate solution was tested in pilot plants at both a 0.1-L/min scale and at a 3-L/min scale. Teck Cominco?s process is called the HalogonTM process, for which patents are pending. Mixer-settlers were used for the 0.1-L/min pilot scale and two BATEMAN pulsed columns for the higher rates. Pilot testing was performed with commercial zinc sulphate solutions containing variable amounts of chloride and fluoride. Sulphate extraction was also controlled and deleterious halides were loaded and stripped into a form suitable for disposal. The engineering aspects and economics of this solvent extraction process for halide removal are also reported.

Jan 1, 2003

By Peter Forschner

Classical Mixing Theory is based on applying many fundamental correlations to standard baffled dished bottomed vertical cylindrical vessels with high degrees of symmetry. Horizontal autoclaves operating at elevated temperatures and pressures have been used for more than two decades. All compartments and especially the first and last compartments are asymmetrical. To date no comparison of the effects of the asymmetric geometry on mixing system design and scale-up has been published. The results of investigating solids suspension, mixing time, momentum transfer from the impeller to feed slurry and feed inlet location in the first autoclave compartment are presented as influences on residence time distribution. CFD modeling was developed and verified with the test apparatus.

Jan 1, 2003