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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 Spencer Peng, Larry Wasik, Akram Alfantazi, Michael Mahon

A dynamic simulation of a zinc tankhouse is a potential tool to improve tankhouse production and cost efficiencies. A fully dynamic simulation has potential uses in the design of new tankhouses as well as in the optimization of existing facilities. Equations from previously validated models of a single cell have been adapted to the industrial dynamic process simulation software, CADSTM Plus. Based on the inlet concentration, current density, and electrode setup, the simulation can predict many parameters, including outlet concentrations, flow rates, current efficiency and energy consumption. Multiple cells have been simulated simultaneously, allowing for an entire hypothetical tankhouse to be modeled. The simulation can be used to dynamically predict the conditions in a zinc tankhouse throughout an operation time scale. Further applications of this model include, tracking impurity buildup, modeling of recycle streams and the development of new flow regimes within the tankhouse.

Jan 1, 2012

By S. S. Chabot, S. E. James

A recent survey of major steel companies worldwide revealed the importance of recycling zinc units from electric arc furnace (EAF) dust, mill scale, blast furnace dust and other zinc containing streams within the steel industry. Many processes have been developed and installed in response to this challenge. The most successful approach involves the production of a crude zinc oxide and its sale to primary zinc producers to recover the metal values. The problem with this process is the high concentration of halides in the crude oxide. This type of material cannot be processed directly in an electrolytic zinc plant because of the corrosion problems it will cause in electrolysis. In 1999, Big River Zinc installed a zinc oxide receiving and washing plant to minimize the impact of halides in its electrolysis circuit. A description of the washing plant and the initial operating results are presented in this paper.

Jan 1, 2000

By Mark Samonds

"Manufacturing processes which involve liquid to solid and solid state transformations in metals encompass a wide variety of physical phenomena. The past twenty years have seen a steady evolution in the complexity and scope of numerical models of these processes, beginning with thermal analyses without phase change. Recently, a few software packages have become available which have true multi-physics capabilities. This permits the treatment of thermal, fluids, stress, electromagnetic, chemical reaction and microstructure development aspects altogether in a fully coupled simulation. This paper will consider various aspects of these types of models.Coupled thermal and fluid flow analyses of continuous castings have been around for fifteen years. Coupled thermal and free surface fluid flow simulations of shape castings have been available for ten years, including view factor radiation models for investment castings. Only recently, however, have fully coupled thermal, fluid, and stress analyses become practical. This implies the reverse coupling of the mechanical deformations to the solution of the energy and momentum equations through modification to the interface heat transfer coefficients and the fluid domain geometry. This has been implemented with a combined eulerian-lagrangian finite element method. Appropriate mechanical constitutive models will also be discussed.Many types of defects need to be predicted in casting processes. Those related to stress include hot tearing, hot cracking, part distortion, and thermal fatigue in dies. Macroporosity, microporosity, and microsegregation are determined by the solidification behavior and microstructure development in a casting. In particular, microporosity is influenced by dissolved gases, the morphology of the mushy zone, the liquid to solid density change, and the local pressure conditions. Macrosegregation is caused by the partitioning of solutes during. solidification and subsequent thermo-solutal convection. An additional transport equation is required for each solute that is being tracked. Computational thermodynamics is being incorporated into these types of analyses to determine transformation temperatures, partition coefficients, densities, and enthalpies. In combination, the microstructure and microporosity models can frequently predict a variety of mechanical models, such as yield strength, tensile strength, and elongation."

Jan 1, 2001

By E. M. Timoshenko

Autoclave technology can be effectively used for liberation of complex mineral raw materials to transfer valuable constituents into solution for their subsequent recovery or to refine feed material in order to remove deleterious impurities, e.g. arsenic. The high efficiency of autoclave processes is attributed to the fact that they are suitable for processing of refractory raw materials, have low capital costs, high productivity, ensure integrated utilization of the feed materials, produce innovative saleable products, completely eliminate any air emissions, provide low-waste or waste-less technology, mechanization and automation of production processes. In the immediate future, it might be expected that autoclave processes will find use on commercial scale for production of heavy non-ferrous metals in combination with other processes (hydrometallurgical, upgrading, sorption and solvent extraction, electrolytic, etc.) to ensure: - Integrated processing of refractory ores and concentrates (pyrrhotite, zinc, copper-zinc, lead-zinc, nickel-cobalt, copper, pyrite); - Production of metallic powders of base metals as commercial products (copper, cobalt, nickel, etc.), composites on their bases, final products and saleable salts. Processing technologies incorporating autoclave processes, especially at the stage of liberation (chemical upgrading) of raw materials are characterized generally by high overall recoveries of valuable constituents significantly exceeding recoveries common for conventional pyrometallurgical processes (for some elements by several tens of percent).

Jan 1, 2006

By Cameron Harris

With the consolidation of the copper industry in the second half of the 20th century resulting in fewer plants treating ever increasing quantities and qualities of feed, the enormous flexibility of the Noranda Process gives it significant advantages over many competing technologies for the production of matte. Toll smelting, recycling, and secondaries treatment will become the cornerstone of profitable operations for all but the lucky few who have large captive mines associated with the smelter. Consequently, the ability to respond to changing market conditions without significant metallurgical or operational upsets will be of considerable commercial advantage. The inherent stability of this bath-smelting process leads to tight matte grade control, while the bath turbulence leads to rapid consumption of feeds with widely varying physical characteristics. Low capital and operating costs combined with a layout suitable for retrofit into existing converter aisles makes it a sensible choice for parts of the world still experiencing the aforementioned consolidation, which is essentially complete in fully developed economies such as the United States of America and the European Union. This paper will discuss features of the Noranda process compared with other technologies and its place in the future global copper production industry, which is set to become increasingly competitive and aggressive.

Jan 1, 2002

By S. H. Castro

In 1997 Chile was the world's largest copper mine producer with around 3.4 million metric tomes of copper. Conventional technology (conminution-flotation- smelting-converting-electrorefining) for copper sulfide ores was used. For copper oxidized ores hydrometallurgical processes (heap leaching-solvent extraction- electrowinning) were employed. Consequently, the most important waste effluents include flotation tailings, gaseous emissions, smelter slags, acidic and alkaline wastewater, electrolytic sludges, solid residues from leaching, etc. The introduction of stricter environmental regulations are forcing the Chilean industry to minimise the generation of waste and promote cleaner production. Gas emissions such as SO2 and arsenic from smelters and process wastewater are the major problems at this stage. The environmental impact assessment of gas emissions in all six largest smelters namely Chuquicamata, Caletones, Potrenllos, Ventanas, Paipote and Chagres led to design a "decontamination plan." The implementation of this plan resulted in (i) the installation of sulfuric acid plants for SO2 abatement and (ii) the installation of electrostatic precipitators to remove arsenic oxides condensed from cooling gases. The aim of this paper is (i) to describe the type of waste associated to the various stages of the metallurgical processes and (ii) review the main abatement technologies used in medium and large size companies.

Jan 1, 1999

By E. Yegan Erdem, Fiona M. Doyle, Alyssa A. Maich

"There is an expanding interest in synthesizing high quality magnetic nanoparticles, most notably for biomedical applications. Different processing routes have been reported for the synthesis of magnetite and maghemite. However, some ambiguity remains on their precise chemistry, intermediates, and final products, due to the structural similarity of maghemite and magnetite, and the relative ease of redox transitions during synthesis. Here we present the results of TEM, x-ray and electron diffraction, and SQUID studies aimed at characterizing the products from two different reaction systems, thereby clarifying the reaction chemistry. The first system hydrolyzed aqueous FeCh and FeCb chlorides with ammonia in a micro fluidic reactor at ambient temperature; although the reaction product displayed a uniform distribution, it included non-magnetic goethite and lepidocrocite. If the aqueous solutions contained dissolved oxygen, there appeared to be extensive oxidation of Fe(II). The second system thermally decomposed iron (III) acetylacetonate in ether. In prior studies, oleylamine has been reported to serve as both a reducing agent and capping ligand to control particle characteristics; however, our studies revealed little reduction, with maghemite dominating the reaction products.IntroductionMagnetite and maghemite nanoparticles are co=only used in ferrofluids, in medical applications, and in drug delivery. Superparamagnetic properties, along with low cytotoxicity, colloid stability and bioactive molecule conjugation capability, make these nanomagnets ideal for both in-vitro and in-vivo biomedical applications [1]. One of the major constraints on widespread adoption of nanoparticles for these applications is the amount needed. Typical batch synthesis methods produce polydispersed nanoparticles, which require further size selection procedures to isolate the mono disperse nanoparticle population needed for many applications. In order to maximize the yield of usable particles from a synthesis operation, the reaction conditions must be closely controlled. This requires full knowledge of how the reaction conditions control the various aspects of nanoparticle growth. Many methods have been used to synthesize iron oxides, including sonochemical reactions, mechanochemical synthesis, hydrolysis and thermal decomposition. This work examines the latter two methods, focusing on oxidation and reduction of iron."

Jan 1, 2012

By Adam Gesing, Paul Marchwica, Jerry Sokolowski, Sharon Lackie

"Often referred to as SEM-EDX, energy-dispersive spectroscopic analysis of characteristic fluorescence x-ray is a standard technique for semi-quantitative elemental composition analysis in scanning electron microscopy. It is quick and extremely useful for identification of phases in the sample microstructure, as long as the constituents are significantly larger than the probe volume from which the fluorescence x-rays originate. The probe volume ranges from a few to several microns, depending on the electron beam spot size and the acceleration voltage. We report on a new variant of an EDX technique developed to overcome this limitation and allow quantitative elemental analysis of smaller phase constituents, down to a size of several nanometers. This variant involves the calculation of compositions of individual phases from multiple analyses of areas containing phases of interest. This significantly increases the usefulness of EDX for quantitative analysis of new nano-structured materials.IntroductionIn any elemental micro-analytical method, the sample material is illuminated by a probe beam that excites an interaction volume of a sample to emit a characteristic signal. This signal in turn interacts with the sample material through absorption and fluorescence mechanisms before a portion of it is collected by a suitable detector and analyzed for elemental composition. The spatial resolution of the method depends on the minimum interaction volume between the probe beam and the sample material.Laser light beams can be tightly focused to a spot size limited by the photon wavelength and can be used to sample the surface of any material. In micro-LIBS (laser-induced plasma spectroscopy) a focused laser beam ablates and vaporizes a small volume of material from the sample surface, creating a plasma spark. Spectral analysis of the light emission from the plasma spark allows the semi-quantitative determination of the elemental composition of the material removed from the sample surface. The smallest reproducible craters achieved are ~ 3mm in diameter and a few nanometers in depth. [l]Particle probe beams of ions or electrons can be focused to a diameter of a few nanometers at the point of impact on the sample. Ions sputter the sample atoms from the point of impact, and the sputtered ionized material is analyzed by mass spectroscopy in a secondary ion mass spectrometer (SIMS). [2] This gives SIMS resolution in a nanometer range. SIMS equipment, however, is expensive and not readily available."

Jan 1, 2013

By B. Boryczko, J. Norwisz, Jose Escobedo Bocardo, Z. Kolenda, A. Holda

"Classical thermodynamic analysis of any thermal and chemical process is usually based on the first law of thermodynamics. Such an approach is not sufficient when deeper understanding of the nature of each elementary process is required. The use of the first and second law of thermodynamics together is necessary to solve practical process more effectively. Enthalpy and exergy balances allow to enhance our understanding of thermal processes especially when cumulative consumption of energy and exergy is calculated. To ensure reliability of such an analysis the least squares method for adjustment of mass balances of principal chemical elements has been applied and described in detail. Numerical analysis has been carried out to compare two different processes of copper production – shaft furnace and flash smelting.IntroductionClassical thermodynamic analysis of any technological process is usually based on the First Law of Thermodynamics in the form of energy (enthalpy) balances. Such an approach is useful in engineering practice as it makes analysis easier in the global scale neglecting modeling of the elementary processes, allows calculation of the thermal efficiency and makes possible to control quality of the measurement results. Additionally, graphical presentation of the energy balance is simple in the form of Sankey diagram.In the case of aluminum electrolysis process, design of the new electrolyzer or its modernization is always based on the enthalpy balance.However, deeper thermodynamic analysis leads to the conclusion that such an approach is not sufficient. The First Law of Thermodynamics guarantees the exact equivalence of the various forms of energy (allowing all forms to be measured in the common unit such as joules) but it does not guarantee interconversibility. Thermal energy (heat) is in a peculiar and unique position, for whereas all other forms can be completely converted into thermal energy, the reverse process id impossible, only a portion of the heat can be converted into mechanical energy. Explanation comes from application of exergy balances. As we know exergy expresses the amount of mechanical work necessary to produce a material in its specified state from components common in the natural environment, in a reversible way, heat being exchanged only with environment [1]. Consumption of exergy connected with the fabrication of some considered product appears not only in the plant manufacturing the product, but also in all plants delivering raw materials for the final production process"

Jan 1, 2008

By Padmavathy Mahadevan, Samir Chefai, Eduard Guerra

"Electrocoagulation is a technique for treating wastewater streams from metallurgical plants whereby electrodes are corroded to generate gases (most notably oxygen at the anode and hydrogen at the cathode) and solid particulates which acts as substrates for coprecipitation of impurities. The performance of electrocoagulation reactors, in terms of their efficiency for removing a particular impurity, is highly dependent on several factors, most notably: the nature of the electrodes, the spacing between electrodes, the current density, the height of the electrodes, the solution flow rate, and application of periodic current reversal. Because these variables have complex interactions, in order to ensure reliable scale-up of laboratory results, experiments should be conducted under conditions that closely match those that would be employed at an industrial scale. To that end, this article describes the design and commissioning of a versatile laboratory scale electrocoagulation reactor that allows for the control of all the aforementioned variables along with the ability to measure the instantaneous spatial distribution of current within the reactor.IntroductionArsenic is often removed from metallurgical waste streams in stirred tank reactors by coprecipitating it with ferric ions as an arsenical ferrihydrite [ 1]. Electrocoagulation is an electrolytic technology that can accomplish the same task, but has not yet been widely adopted to treat metallurgical waste streams [2]. The electrocoagulation process involves the use of an external DC power supply to drive the dissolution of a relatively non-toxic metal into the wastewater stream, usually either iron or aluminum, which then largely precipitates as oxyhydroxide phases that adsorb undesired impurities [l]. At the anode, the metal is dissolved and oxygen is often evolved, lowering the local pH and enhancing metal ion solubility."

Jan 1, 2012

By K. H. Ho

This paper describes a simplified numerical model which is used to study the skull formation of liquid metal on a rapidly rotating disc in centrifugal atomisation. The skull formation is one of the problems limiting the wide use of centrifugal atomisation. The enlarging skull on the atomising disc reduces the yield of metal powder produced and produces a resistance to the centrifugal force which worsens the quality of the powder. It is costly and often difficult to study the flow behaviour by experiments due to the complex heat transfer and phase transformation during the processing. Computer modelling is therefore a powerful tool for mechanistic understanding of centrifugal atomisation. This paper investigates the flow pattern of the melt on the rotating disc as a function of initial temperature, melt flow rate and disc rotation speed as well as the physical properties of the melt, such as density, surface tension and viscosity using the commercial package Flow-3D. Keywords: Solidification, Rotating disk, Centrifugal Atomization

Jan 1, 2003

By J. W. Whitney

Itronics Inc., through its wholly owned subsidiary Itronics Metallurgical, Inc. (IMI), has successfully developed technology that allows it to be fully integrated as a photochemical recycler. IMI is now using this technology to expand its regional operation, which collects used photographic chemicals, chemically removes 99.997% of the silver and uses the residual to make a line of high quality liquid multinutrient liquid fertilizer products. Elevated silver discharges from the Reno-Sparks sewage treatment facility, that were traced back to incoming waste photographic chemicals and which were seriously impacting the sensitive fishery, provided the impetus for this project. This paper is updated from a paper presented at the Twenty-Second International Precious Metals Conference Toronto, Ontario, Canada in June 1998. It presents an overview of the scope of the problem solved by the technology, some of the permitting and development issues, and some of the specific fertilization formulations that are now being marketed.

Jan 1, 2000

By Bahram Rezai

Fine particles float poorly and less-selectively under normal flotation conditions. One of the promising methods for fine minerals is the utilization of the principle of Flocculation. Hydrophobic flocculation flotation (or floc flotation) was tested on a magnetite concentrate that was finely ground to be micron particles, for producing a concentrate with sulphur grade less than 0.1%. After that, slurry dispersing with water glass as dispersant, pyrite fines were subjected to hydrophobic flocculation induced by xanthate and a small amount of kerosene then the slurry was transferred to a flotation cell for recovering the hydrophobic flocs. The experiments carried out indicated that through one-step rougher and two-step cleaner flotation, sulphur grade was reduced from 1% to 0.1%. It has been found that the separation efficiency of the floc flotation process closely correlates with the main parameters of hydrophobic flocculation such as xanthate addition, conditioning time and kerosene addition.

Jan 1, 2006

By Corby Anderson

The efficient separation of palladium from the transition metals copper, nickel and iron can be effected by passing a leach solution of these metals through a column of the silica polyamine composite material, WP-1, patented by Purity Systems Inc (PSI), Assignee, University of Montana with exclusive license to PSI. The separation can be done at the intrinsic pH of a nitrogen species catalyzed (NSC) oxidative pressure leach solution (~0) and stripping of the palladium from the composite can be effected with hydrochloric acid/ammonium chloride solutions at 50oC. Batch capacities of the composite for palladium are ~ 1.8 mmol/g resin. The possibilities for isolating the metal from the strip are discussed. Given the proven longevity and rapid capture kinetics of the polyamine composites, this new approach should prove to be an economically viable alternative to the multi-step concentration processes practiced in the PGM industry to date.

Jan 1, 2003

By Patricio F. Mendez

This paper presents a formalism to automate portions of the traditional scaling procedure. This formalism, called here Order of Magnitude Scaling (OMS), captures essential components of the governing equations into a set of matrices and arrays amenable to computer implementation using standard linear algebra tools. This approach is valid and specially useful for large systems of multicoupled equations. The matrix approach proposed enables one to automate operations such as normalization, dominant balance, obtention of characteristic values, and check for self-consistency. Also, automation permits an exhaustive exploration of all possible balances and the discovery of unsuspected scaling laws. As an example, OMS is applied to the analysis of the viscous boundary layer with no external pressure gradient. The obtained scaling laws for boundary layer thickness and transverse velocity are the same as those obtained with traditional scaling, and in addition, a meaningful estimation for pressure variations within the boundary layer is obtained; this last estimation is typically not addressed in the manual analysis.

Jan 1, 2006

By J. E. Dutrizac

The behaviour of the lanthanide elements during the precipitation of sodium and potassium jarosites at 98oC from sulphate media was systematically investigated. The lower atomic weight lanthanide elements (La to Gd) are characterized by the limited solubility of their alkali-lanthanide sulphates, such as NaNd(SO4)2?H2O, which commonly contaminate the jarosite precipitates. Hence, single phase jarosite-type compounds were precipitated only from solutions containing <0.4 g/L of the La to Sm lanthanides. The sulphates of the heavier atomic weight lanthanide elements (Tb to Lu) have significantly higher solubilities such that solutions containing up to 10 g/L of the individual lanthanides could be investigated without the precipitation of alkali-lanthanide sulphate species. Even at the highest lanthanide concentrations, however, none of the jarosite precipitates incorporated more than 0.3 wt% of any of the lanthanide elements. Comparable levels of lanthanide incorporation were noted in both Na-jarosite and K-jarosite. Although the mass of the jarosite precipitate increased with increasing ferric sulphate concentration or with increasing pH, the extent of lanthanide incorporation was not significantly affected. Clearly, the trivalent lanthanide elements do not substitute extensively for trivalent iron in the jarosite structure. This behaviour likely reflects the significantly lower hydrolyzability and larger size of the trivalent lanthanide ions relative to ferric ions.

Jan 1, 2003

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 Vahid Rastegar

"Characterization of the microstructure and revealing dendrites in the microstructure and also measuring the dendrites arm spacing and the distribution of silicon were studied in various pieces of compacted graphite cast irons with 0.17, 0.185, 0.2, 0.22 and 0.24 percent of mischmetal. Black-white and color metallography (quantitative and qualitative) were carried out on the various steps of the cast samples. Distribution of silicon was studied quantitatively using spot analysis with scanning electron microscopy. Furthermore, effects of two variables (cooling rate and mischmetal percentage) on dendrites arm spacing were investigated.In order to color metallography, the samples were plunged into a boiling solution of 18% KOH, 9% NaOH and 9% picric acid in distilled water. It was inferred that the microstructure coloration varies according to the sequence: green-->red-->yellow-->blue-->dark brown->light brown as the silicon content decreases. After observing dendrites, dendrites arm spacing was measured. In this method, it seems to be possible to predict the mechanical properties of compacted graphite cast irons by knowing dendrites arm spacing and without any destructive testing. After studying the two variables, it was concluded that dendrites arm spacing decreases as the amount of mischmetal increases and it increases as the cooling rate increases.IntroductionIn general, detecting of primary austenite dendrites is not possible in cast irons due to their solidification system. Observing the dendrites in the room temperature is possible only in those gray cast irons that contain type D graphite. With collecting data of dendrites arm spacing (DAS) measurements, it could be possible to achieve the mechanical properties of cast irons without any destructive testing. In this research by applying a particular method, primary austenite dendrites and also distribution of silicon in the microstructure has been observed."

Jan 1, 2012

By Robert Kozicki, Eric Graham, George Wrightson

"IntroductionThe manufacture of Ferro Chromium involves the smelting of various ores and fluxes to produce the metallic product.Slag is inherent in the process. It has a much lower density than the metallic FeCr. Some chrome may be trapped in the slag as either FeCr or Cr203.Previous methods to estimate the slag in the FeCr have revolved around separating the slag and metallic portions by exploiting the differences in density. The downside with that procedure is that material will often contain pieces that are adhered FeCr and slag. The Metallic FeCr may also be completely encapsulated in the slag.An alternative and more precise method involves calculating the slag content based on chemical analysis of Mg and Al. The Mg and Al will be at relatively low levels (less than 0.1 % ) in the Metallic FeCr pieces and considerably higher in the slag (3% or greater). The overall sample will have a proportional amount and is calculated using simultaneous equations with the assumption there is only one kind of slag and one kind ofFeCr present. ""Pure"" slag and ""pure"" FeCr are needed in order to determine the Mg and Al in each. The detemlination of the Mg and Al in the overall sample would then be used to calculate the amount of slag.When the particle size is small, it is difficult to sample and get ""pure"" pieces of the slag and FeCr of sufficient quantity to perform a proper analysis. Often, historic data is used but that is dependent on the source of the FeCr and the materials used in its production. Mg and Al levels in slag can vary between 3% and 20% in different FeCr slags depending on their origin."

Jan 1, 2013