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By Luis W. Pommier

The wastes of the plating industry are generated in the process of rinsing the plated objects and during the cleaning of the plating shops. High volumes of hazardous waters are neutralized on site producing recyclable water, generating a metal rich, hazardous, filter cake. Occasionally, a complete plating bath has to be discarded which increases the metal content of the filter cakes. These filter cakes are discarded as hazardous at a cost of over $ 250 per ton. The metals found in the cakes are generally copper, nickel and chromium or zinc, lead and cadmium, assaying from 2% to 15% or even higher content of each metal The metals and their contents are highly variable. Some plating shops discard their products directly to hazardous waste sites, others, have them collected by companies which consolidate wastes from several producers prior to discarding. These wastes, richer in metal content than mine ores, need neither mining nor crushing and grinding for concentration. The commonly found impurities in the mine ores, i.e.: pyrites, arsenic, and valuable metals which are present in minute quantities, are absent in the filter cakes. The processes available to selectively recover the metals from the filter cakes, are discussed based on their technical and economic merits. The flow-sheets include leaching, solvent extraction when required, and electrolytic refining. Examples, showing the separation of copper, nickel and chromium and also of zinc and lead in pilot plants, show the technical and economic viability of the processes.

Jan 1, 1996

By V. Ramachandran

In view of the increasing environmental regulations that have been promulgated in the last 30 years, non-ferrous smelters and refineries have learnt to handle effectively the process waste streams that need to be bled from the system for impurities' control The cations of concern are copper, lead, zinc, cadmium, mercury, thallium, nickel, silver, sodium and potassium. Anionic species of arsenic and selenium also need to be addressed, Sulfates and chlorides-not a major concern at present-have come under scrutiny in the recent past. The current paper reviews several treatment options with reference to a) types of waste streams processed b )process chemistry c)discharge options and recovery of treated water and d) sludge disposal The long term goal of any smelter and/lor refinery should be to achieve zero liquid discharge from the plant. Methods to obtain zero discharge are discussed.

Jan 1, 2003

By Osarnu Inoue

In Mitsubishi Continuous Copper Smelting and Converting Process, smelting, slag-matte separation and matte converting are continuously carried out in series in three furnaces connected by launders. As a result of this operational configuration of the furnaces, influence of the change in operating condition in upper stream, such as variation of feeds in the smelting furnace, propagates to down stream with some delay. In order to achieve stabler operation, process control algorithm based on the dynamic characteristics of each furnace would be very effective. In this study, the dynamic process simulation model was developed for the smelting furnace. The model consists of two mathematical modules, i.e. the thermodynamic module and the mixing module. The calculation results using operating data obtained at Naoshima Smelter showed good agreement with the actually observed change in temperature, composition and flow rate of matte and slag at the outlet of the furnace. In addition, operation parameters such as reaction efficiency of oxygen and coal, dead volume of melts were estimated.

Jan 1, 1999

By James T. Staley

Quenching and aging are critical processing steps used to produce precipitation hardenable aluminum alloy products. This work describes personal computer programs that employ models to predict certain properties after quenching and aging and graphically display them. One of the programs allows the user to predict the attainable strength and toughness of aluminum alloy products after an arbitrary quench. Another program simulates the changes in strength and electrical conductivity occurring during second-step aging alloy 7050-T7X products as a function of thickness, furnace temperature set point, and furnace characteristics.

Jan 1, 1993

By Yutaka Shiraishi

Two methods were developed to measure the viscosity of the slag from the glassy to the liquid states in an ascending temperature process. The first method employs rotating parallel plates within which is placed a solid cylindrical sample in line with a sphere. The second method uses a tube which is pushed into a sample held in a rotating crucible. Both methods were tested using standard glasses, including boron trioxide and NBS standard glass #711. The main difference between these two methods is in sample preparation. Comparative measurements between two methods were performed using a sodium boro-disilicate glass containing 5%mol of alumina. The results showed good agreement in the mid-range of glassy viscosities, 105 to 107 Pa.s. In the liquid state, there were no significant differences between the two methods.

Jan 1, 2003

By V. Ramachandran

In view of the increasing environmental regulations that have been promulgated in the last 30 years, non-ferrous smelters and refineries have learnt to handle effectively the process waste streams that need to be bled from the system for impurities' control. The cations of concern are copper, lead, zinc, cadmium, mercury, thallium, nickel, silver, sodium and potassium. Anionic species of arsenic and selenium also need to be addressed, Sulfates and chlorides-not a major concern at present-have come under scrutiny in the recent past. The current paper reviews several treatment options with reference to a) types of waste streams processed b)process chemistry c )discharge options and recovery of treated water and d) sludge disposal. The long term goal of any smelter and/or refinery should be to achieve zero liquid discharge from the plant. Methods to obtain zero discharge are discussed.

Jan 1, 2003

By Soumitro Nagpal

Bacterial oxidation of a pyrite-arsenopyrite-gold ore concentrate was carried out in .14-liter continuous-flow stirred-tank reactors (CSTR). Oxygen and carbondioxide consumption rates mineral dissolution rates, and bacterial concentrations were measured at various steady-state residence times and with 6, 11, and 16 wt.% solids in the feed slurry. A sharp optimum in biooxidation rate .was found at a residence time of approximately 40 hours for operation at each of the three pulp-densities. Biooxidation rates increased consistently. with increasing pulp density. Cell washout accompanied by negligible biooxidation rates was found to occur at a residence time of approximately 20 hours. Mineral' oxidation was found to be strongly dependent on bacterial activity. Arsenopyrite was found to be preferentially oxidized? at the higher Pulp densities.

Jan 1, 1991

By Stephen M. Testa

Several methodologies are available for the remediation of contaminated soils including bioremediation, vapor extraction, chemical fixation, incineration and direct disposal. A proven innovative and cost effective alternative for the fixation of contaminated soils is via cold-mix Environmentally Processed Asphaltm (EPA"'). EPAm methodology utilizes contaminated soil as an ingredient in an industrial process to produce a commercially viable product. Petroleum hydrocarbon and metal affected soil is incorporated with a water-based asphalt emulsion and varying amounts of aggregate to produce a range of cold-mix asphaltic products that fulfills the requirements of a variety of end uses. This viable and creative use which is within the intent and spirit of current regulations in producing, in lieu of a landfill waste, an end product for use as a berm, road base, liner, or other site specific application. Consideration of certain engineering and environmental factors including durability, stability, chemical resistance and ageing, biological resistance, permeability, leachability and geochemical aspects suggests that cold-mix asphalt incorporation of affected soil will perform more than adequately under normal conditions for a long period of time.

Jan 1, 1994

By Don Eby

The application of electric arc furnace smelting of lead, antimony, and tin bearing slag from a reverberatory furnace will be discussed. The selection procedure for the 4.0 MVA electric arc furnace in Indianapolis, Indiana is presented. The design criteria for the transformer, electrodes, refractories and associated equipment is presented. The operation of the furnace including chaJ:9ing, bullion tapping, slag tapping, ventilation, slag composition, metal recoveries, and toxic leach results of thra.1 away slag are discussed. Flow charts and the equipment specifications are given.

Jan 1, 1990

By Kenji Morinaga, Shigeru Fujino

"Preparation and vacuum ultraviolet (VUV) transmission spectra of aluminum fluoroberyllate glasses, MgF2-CaF2-SrF2-A1Fr BeF2 (MCSA-Be) and MgF2-CaF2-SrF2-AlFrYFrBeF2 (MCSAY-Be), were studied. The influence of YF3 and BeF2 on the thermal stabilization against crystallization and VUV transmittance was investigated. With increasing the BeF2 content, the crystallization tendency decreased and the absorption edge shifted to shorter wavelength in the MCSA-Be and MCSAY-Be glasses. The MCSA-20Be glass composition exhibited the shortest wavelength UV absorption edge (-147 nm) and the highest transmittance at 157 nm (60% for 2 mm sample thickness). The transmission values at 157 nm and the slope (steepness) of the absorption edge were found to be significantly influenced by the trace amount of Fe2+ derived from the BeF2 raw materials.IntroductionPure beryllium fluoride is known to be an only fluoride that forms one component glass on cooling from the molten state and is structurally similar to silica with [SiO4]4- tetrahedra. Molten BeF2 is highly viscous with a viscosity of about 106 poise near its liquidus temperature at 550""C[l]. The addition of modifying fluorides such as LiF, NaF or KF to BeF2 substantially decreases the viscosity[2]. Glass forming region of binary fluoroberyllate glasses has been mainly reported by several authors [3]. LiFBeF2 binary system is structually analogy for Mg0-Si02 system from their phase diagram and ratio of ionic radius for each cation and anion, respectively. LiF-BeF2 binary glasses seems to be promising candidates for the extreme deep vacuum ultraviolet (VUV) transmitting optical materials owing to their larger band gap. However, it is chemically unstable, and so, have no practical application for lens systems in micro lithography equipments and substrate materials for F2 (157nm) excimer laser[4]. There are also few reports on the VUV transparency of multicomponent aluminium fluoroberyllate glasses from the view point of their compositional dependencies. The purpose of this paper is to prepare deep VUV transmitting optical materials and determine the optimum glass compositions for aluminium fluoroberyllate glasses investigating their thermal stabilization against crystallization."

Jan 1, 2000

By Hubert Bril, Priscilla Pareuil, François Bordas, Emmanuel Joussein, Jean-Claude Bollinger

"According to the legislation, valorization type, origin and characteristics of waste material, various standard procedures are available to evaluate environmental impacts. A Mn-rich slag was sampled from a metallurgical plant. After its characterization (elementary analysis and mineralogy), five standard procedures were carried out (i.e. TCLP, EN 12457-1). Each fixed parameter of the standards was systematically studied in a large range: pH, Liquid/Solid ratio, contact time. For example, EN 12457-1 led to a low ME mobilization, increasing with the L/S ratio, the contact time and an acidic pH. As a conclusion, the representativeness of the considered parameters and their potential variations are predominant to assess of the real environmental impact during slag reuse. Introduction Recent studies have been carried out about environmental impacts of waste containing metallic elements (ME) because of their potential mobility [1-7]. Indeed, slags are either dumped or valorized in various activities such as building materials. In order to assess environmental risk, various standard procedures are used depending on country legislation, origin of waste and valorization way. Results of leaching tests are linked either to special legislation (e.g. Dumping: EC, Council Decision 2003/33/EC, Construction products: EC, Council Directive 89/106/EEC) or to legal levels used in drinking water (Directive 98/83/CE) when leachates could migrate to groundwater. If ME in leachates are lower than drinking water authorized levels, the waste will be considered as non-hazardous. On the contrary, if the leachable amounts exceed them, the question about the risk has to be posed. Beyond the abundance of leaching tests available, variety of operational conditions induced by these regulatory tests does not make the choice easier. According to operational conditions induced, ME release could vary from one test to another one. ME concentrations in leachates depend on pH, Liquid/Solid ratio, contact time and particle size [3]. To highlight the importance of these operational parameters, potential risk for valorization of a manganese-rich slag was assessed by comparing several standard leaching protocols [8-12] with a global study dealing with the influence of operational conditions. For each regulatory protocol, the most influential parameters (L/S ratio, pH, particle size and contact time) have been studied in a large range."

Jan 1, 2008

By C. Beckermann

"A diffuse interface model is derived for the direct simulation of two-phase flows with surface tension, density differences between the phases, and phase change. The derivation starts from the balance equations for a sharp interface and uses a formal averaging procedure on an atomic scale to obtain diffuse interface versions of the equations. Two approaches are considered: (i) the two phases have different velocities inside the interface and separate conservation equations are solved for each phase, and (ii) the two phases have the same velocity inside the diffuse interfuce and mixture conservation equations are solved. Based on a superposition of microscopic (atomic-scale) and macroscopic interface morphologies, an expression for the interfacial momentum source term is introduced that models surface tension effects and accounts for immiscibility between the phases.IntroductionDiffuse interface methods have been a popular tool in the direct simulation of two-phase flows [I]. In diffuse interface approaches, the interface between the two phases is characterized by a rapid but smooth transition in the properties, such as density and viscosity. Usually, a phase function ? is introduced to represent this transition, and the evolution of ? in the domain is computed from a separate equation or recipe. A unique set of conservation equations (e.g., mass and momentum) is solved on the entire domain, irrespective of the phase present, by accounting for the transition in the properties and introducing terms that account for interfacial sources. The continuum surface force (CSF) model of Brackbill et al. [2], which accounts for surface tension, is an example of the latter. The volume-of-fluid (VOF), level set, and phase-field methods are all examples of diffuse interface approaches. The major advantage of diffuse interface methods is that explicit tracking of the interface and the application of traditional sharp interface conditions are avoided. A disadvantage can arise from the artificial smearing of what is in reality an interface of atomic-scale width; however, techniques have been developed to overcome this problem."

Jan 1, 2004

A simulation of a capper concentrate smelter was built with a capacity of 450,000 tons per year. The system's components to simulate were three : a Reverbetory furnace, a Wiente ' s modified converter ( TMC ) and two cranes. The system was classified as dynamic, stochastic and discrete. In the simulation language choice it was concluded that the most advantageous one was GPSS/H. The model verification was done through the interactive Debugger that the language has and the statistical validation was done through the result variables of sane activities, that as a whole characterize the system (charged matte and charged concentrate to the TMC, skimming white metal and skimning slag). The validation was done comparing the simulation results of these variables with the ones obtained for those variables in a specific month in the smelter. The comparison consisted in a difference of means test and in all cases the equality was accepted with a 95% of confidence. The animation tool was PROOF, a general purpose animator, that is used after processing the simulation.

Jan 1, 1994

Lead removal has been problematic in nickel production by electrowinning from chloride solutions, as developed by Falconbridge. The C12 leach liquor needs to be diluted by electrolyte to allow precipitation of the lead prior to electrowinning. This results in higher solution purification costs and an aversion to consider lead contaminated (secondary) feeds. In this paper, the electrowinning of nickel chloride is carried out in a membrane equipped electrolytic cell. When lead containing nickel solutions are fed into the anode compartment and the anolyte is separated from the catholyte with a cation exchange membrane, lead remains in the anolyte due to the presence of a negatively charged chloride complex. The positive nickel ions migrate preferentially through the membrane to the catholyte, allowing a lower lead nickel cathode to be produced. Lead concentration in the catholyte and the cathode product has been tested as a function of lead concentration in the anolyte. Results are presented and discussed.

Jan 1, 1998

By John Wallace, Chib Iheagwara

"Refinements in sensor design have produced low-cost rugged elements to act as loop coupled with stable detection hardware for eddy current measurement in difficult environments. This has allowed direct dimension gauging of nonferrous and ferrous products above the curie point for absolute dimensions and electrical conductivities independently. The software was developed for the analysis of electrical conductivity profiles in CZ silicon crystal growth, then refined for monitoring bar properties and tube properties. Since in most metal working operations, speeds at the minimum of a few hundred feet per minute are encountered the design of the gauge was optimized for a rapid measurement. Independently extracting electrical conductivity provides data in some metal systems for determining the temperature of the monitored product.IntroductionThe primary reason for the use of eddy currents in gauging is that in hostile environments of metal working techniques such as laser gauging and ultrasonics are not always robust enough for in process measurements. Our goal is to use the technique of eddy current measurement as a quantitative control element in various hot and cold processing operations. Inspection in the early stages of metal and semiconductor processing is usually too costly to introduce in a well developed process and these tools are usually only employed in process development. Until recently there has been no efficient general analysis to allow real time measurements in the cylindrical and the probe geometry that could separate dimensional changes from material property changes both which effect the eddy current response. The basis for these measurements is that forward electromagnetic problem for conductors can be solved exactly for the test geometry which allows an inverse analysis to be made by relaxing the dimensions and conductivity to values which reproduce the measured response[!]. This transformation is based on analysis developed in Robert Siegfried' s thesis and was explored both by modeling and by physical measurement. This analysis was extended over the last few years to allow a more compact data set to be used to exact physical properties. The main result was that the technique would work on high ·quality physical data on as little as three test frequencies with the penalty being that the analysis is computational intensive. The main result of this work was that a quantitative inverse analysis of eddy current response would allow a general instrument to be used for a variety of measurements rather than being tailored for a specific measurement on a specific material test geometry. The development of these instruments has progressed over the last ten years for monitoring real time solidification, crystal growth[2] and hot seamless tube forming where the use of standards in traditional eddy current is limiting. The specific instrument design was dictated by the requirements of the algorithm for both frequency selection and levels of systematic noise that could be tolerated. Because the data is need for real time information this dictated that the system be a parallel multifrequency eddy current instrument feeding the same sensor. The sensor have to be simple and robust and usually a single loop or several loop of heat resistant wire or tube. This presentation is about using inversion of multifrequency eddy current data in real time to produce dimensional and property data on cylindrical conductors and planar conductors in real time. The object of the measurements is to produce dimensional outputs on measurements of conducting material without having to establish a detailed standard for each material or size tested. The dimensional measurements using eddy currents is complicated by material variations in conductivity due to temperature and composition. Those variations that are not geometric are often not of critical interest and complicate the measurement. The dimensional changes are often of more importance"

Jan 1, 1997

By Kathryn Hindmarsh

The most common method for the concentration of cyanide in gold leach circuits is based on the titration of cyanide ions with silver ions. This can either be done manually as a titration with a visual end-point or by using one of several commercial cyanide analysers which are 'based on the same titration but use a potentiometric end point This method has 'its limitations in the case of some ores such as those containing high amounts of soluble copper and those that are treated at low (less than pH 9) pH values in that the titration results do not accurately reflect the concentration of cyanide which is available for the dissolution of gold. This paper will present the results of the development of a novel "active" cyanide analyser which is based on the rate, of the reaction between gold colloids and cyanide. Gold colloids have a deep red colour and can be very simply prepared and stored for extended periods of time when stabilized. t has been shown that colloidal gold behaves similarly to metallic gold, dissolving in aerated sodium cyanide solutions to give the colourless Au(CNh-ion, This allows the reaction between the colloids and cyanide to be monitored spectrophotometrically at 520 nm. An automated instrument has been developed around this concept which can analyse a filtered pulp stream every few minutes with periodic calibration using standard cyanide solutions, Results of test work on synthetic solutions and solutions derived from several Australian gold plants will be presented as will the results of a comparative evaluation with a commercial titration analyser on a local gold plant

Jan 1, 1998

By Jun Zhu, Jilai Xuel, Tao Li

"Coal gangue is industrial waste containing Al2O3 and SiO2 with great recycling and reuse values. This work is aimed at extracting Al2O3 content in the coal gangue by a process of carbonthermal reduction - alkaline leaching. The Al2O3 and SiO2 contents first became a mixture of SiC and Al2O3 in the process of carbonthermal reduction, and then Al2O3 was separated by leaching in NaOH solution, thus producing the sodium aluminate solution for Al(OH)3 precipitation. The products generated at various stages in the process were inspected using XRD and chemical analysis. The effects of parameters such as reduction temperature, carbon ratio, NaOH concentration, leaching time, leaching temperature, stirring speed, etc were investigated in details.IntroductionCoal gangue is an industrial residue resulted from the process of coal mining and washing, accounting for 100 - 150 kg with 1 ton raw coal mined. The existence of coal gangue in large quantities has become a serious problem for environment pollution. On the other hand, the chemical compositions of coal gangue are Si02 and Ah03 primarily. In China, the accumulation storage capacity of Ah03 in coal gangue is not less than 600 million ton at a rough estimate, which should be considered as an abundant second resource [1]. If the alumina can be recycling and reused effectively from coal gangue, it will not only reduce the imperilments caused by coal gangue, but also yield good economic returns.Generally, the processes of extracting Al2O3 from coal gangue can be divided into acid leaching (vitriol or hydrochloric acid) and alkaline leaching (mostly NaOH) [2]. The acid leaching processes have many problems, such as lower leaching ratio, corroding the equipments, recycling the spent acid hardly, etc. The primary matter of alkaline leaching process is silica dissolving with alumina, which brings perplexing desilication process, alumina loss seriously and higher energy consumption."

Jan 1, 2011

By C. J. Beyke

Slags and/or mattes from three secondary lead producers were studied as part of an effort to develop treatment methods for these lead-bearing residues. Each company used a somewhat different production process. Company A used a reverberatory furnace followed by a blast furnace. Company B used only a blast furnace. Company C used both a reverberatory and a blast furnace, and the scrap material was desulfurized with sodium carbonate prior to smelting. The slag matrix produced from sulfur-bearing scrap consisted mainly of iron-calcium silicates; the slag from desulfurized material was similar, but also contained sodium. In all the slags most lead was present in metallic form, often alloyed with tin, antimony, arsenic, and/or iron. Slag from Company B contained the most alloying elements, often as discrete subparticles within the lead droplets. Mattes were produced at Companies A and B; predominant phases were pyrrhotite and magnetite, while lead was present in metallic form and as galena.

Jan 1, 1995

By F. Qian

An impinging gas jet on a liquid surface is found in many industrial process systems such as electric arc furnace, welding, steel-making operation and others. Fundamental understanding of the interaction of a gas jet on a liquid pool can provide important insights into process behavior resulting in improved efficiency. A numerical model is developed for solving the flow fields of both impinging gas jet region and liquid pool below, in which the deformed interface shape is predicted simultaneously. Using curvilinear coordinates, the Navier-Stokes equations of each phase are solved separately through coupling of static pressure, shear stress and velocity at the interface. Several cases for jet distances and flowrates were investigated both numerically and experimentally with an air-water model. Favorable comparison of numerical results with experimental data confirms the validity of the present numerical approach. An existing phenomenological model for 'penetration depth' prediction was extended for smaller 3et exit height to jet diameter' ratios.

Jan 1, 1995

By Thomas M. Harris

Cation exchange is not sufficiently selective to be used for the removal of heavy metal ions from a general industrial wastewater. However, if the metals can be converted to polyvalent anions through complexation, they may be removed both selectively and efficiently by anion exchange. This approach, referred to as chelation-assisted anion exchange (CAAE), has been examined using industrial wastewater samples contaminated with Ni2+ and Cr3+. For this particular application, the Ni2+ is complexed with 8-hydroxyquinoline-5-sulfonic acid, and the Cr3+ with sulfosalicylic acid. Removal efficiencies and adsorption isotherms for both the complexants and the complexes were determined in batch-mode tests.

Jan 1, 1994