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By Kenneth N. Ham

Hydrometallurgy covers a wide spectrum of areas and its knowledge base is enlarged and enhanced by contributions from many other fields. Dissolution of metals and alloys in aqueous media will be used to illustrate how rich the field of metal extraction can be. Comprehensive understanding of the fundamentals of metal and alloy dissolution in aqueous systems requires creative application of thermodynamic principles, solutions chemistry, ligand complexation theory, electrochemistry, transport phenomena and heterogeneous kinetics. In addition, recent developments in instrumentation in the fields of interfacial phenomena and corrosion have tremendously advanced the field of metal extraction in aqueous system. The close relationship between metal extraction in aqueous systems and various physicochemical phenomena occurring in corrosion and interfacial systems will be discussed and illustrated with examples.

Jan 1, 2002

By Anna Franzkowiak, Dean Gregurek, Alfred Spanring, Angelika Ressler

In order to determine the most suitable refractory products and improve the lining lifetime for the diverse furnaces used in the nonferrous metal industry, corrosion tests are performed at RHI’s Technology Center. The practical facilities include the cup test, induction furnace, rotary kiln, and drip slag test described in this paper, which enable a comprehensive understanding of the chemo-thermal brick wear on a pilot scale. The corrosion trials are performed with actual slags generated during operations at a customer’s plant. To determine the highest influencing wear parameter, every single test is combined with a detailed mineralogical investigation and thermochemical calculations performed using FactSage. Based on the results, tailored refractory solutions for the nonferrous metal industry can be provided in combination with trials conducted at the customer’s site.

Jan 1, 2014

By Deming Wang, R. A. Overfelt

"This paper presents a computer-aided heat transfer simulation method to predict the thermal characteristics of an alloy sample in a special furnace for directional solidification. A two-dimensional transient heat transfer by conduction combined with radiation is developed to calculate the energy exchange between a directional solidification furnace and the sample. Finite difference equations with control volumes are used to calculate the transient heat transfer. A special boundary control volume is used to combine heat conduction and radiation in the transient heat transfer. Heat radiation effects on the surfaces of the special control volumes with a changeable view factor during directional solidification processing are also represented. The simulation results are verified by measurable experimental data. Using the computer simulation model, many thermal properties of the directional solidified castings can be obtained, such as temperature distribution, solidification velocity, the shapes and positions of the liquid/solid interface and thermal gradient at the interfaces. These are very important to analyze microstructure of casting alloys, avoid casting defects and control casting quality. 1 IntroductionIn directional solidification (DS) processing of castings, the temperature distribution, the interface between liquid and solid zone, thermal gradient in the mushy (pasty) zone and solidification rates are very important factors to analyze the microstructure and the casting quality. These variables affect the orientation and size of dendrites, shapes of grains, solute segregation and deleterious casting defects, such as microporosity, freckles and segregation channels. In order to avoid the casting defects, the temperature distribution and thermal gradients of castings during directional solidification must be strictly controlled. However, the structure of furnaces used for directional solidification is often complex. Heat transfer and temperature distribution within a casting not only depend on furnace temperature but also on the thermal properties of the casting alloy, crucibles, retorts etc. A more accurate heat transfer analysis."

Jan 1, 2001

By Dean Ilievski

Mathematical modelling of the precipitation process requires that the kinetics of crystal growth, nucleation and agglomeration be known: This paper reviews the current state of knowledge on these precipitation sub-processes (ie. growth, nucleation and agglomeration) and describes a number of experimental techniques for estimating their kinetics. The experimental methods used to generate the precipitation data and the data analysis techniques used to extract the kinetics information from the data are discussed separately. There is no universal "best" technique for determining the kinetics. However, studies on multi-crystal systems are more reliable for modelling purposes than are single crystal studies. The selection of a technique will depend on which sub-processes are present. A problem with all kinetics studies is that there is generally a large uncertainty in the estimated kinetic parameters. This stems from the scatter in the experimental data being further propagated by the mathematical techniques used to extract the kinetic parameters.

Jan 1, 1996

By Donggen Fang, Liu Xuan, Jilai Xue

SiO2 and Al2O3 in the metallurgical slag of nickel laterite ore have great recycling values. In this work, Si and Al were extracted from the slag in NaOH based molten salts through alkali roasting and water leaching process for preparing zeolite materials. The extraction ratio of SiO2 increases with increased temperature and appropriately prolonged time, and more than 80% SiO2 can be recycled from the slag after roasting at 550°C. Si and Al from the slag are in the filtered liquor for producing zeolite materials, while Mg, Ca, Fe and other impurities remain in the leached residues. Adding Na2CO3 into the alkalin-slag roasting process can reduce the amount of pure NaOH used with minor decrease in extraction ratio of SiO2, while make better separation of Ca to avoid it getting into the filtered liquor. Adding Al2O3 into the alkalin roasting process can replace part of more expensive NaAlO2 addition that is required for preparing zeotite material, which may bring out a minor decrease in extraction ratio of SiO2 due to formation of NaAlSiO 4 in the filtered residues. Quality X zeolite and 4A zeolite materials can be made from the starting liquor containing Si and Al recycled from the laterite nickel slag through alkali roasting and water leaching process.

Mar 1, 2018

By C. Lupi

"The energy consumption of copper production by electrowinning, generally represents more than 1/4 of the total energy requirement in hydrometallurgical traditional process (roasting, leaching, purification and electrowinning). The considerable saving can be achieved just in this step that requires about 2.2 kWhlkg of the produced copper. To save energy the cell voltage, or more appropriately its anodic component, can be reduced: that is because the anodic voltage represents the main component of cell voltage and so it is largely responsible for the excessive energy consumption in copper sulphate electrowinning.In this work some ways are studied to lower the anodic voltage. First the cobalt ions were added to the sulphate solution in order to study the catalytic effect on oxygen discharge. Then lead alloys anodes (Pb-Ag, Pb-Sb-Ag and Pb-Ca) were used to promote a better oxygen evolution as a result of a different anodic surface. Their behaviour was compared with the PbSb traditional ones. Finally, as already pointed out by several authors for zinc electrowinning, ethylene glycol was employed as anodic depolariser in order to verify its effectiveness in the case of copper electrowinning. By combining all the above-mentioned ways, energy saving ranging from 20% to 27% is achieved.All the tests were carried out on a laboratory pilot-plant for long time to simulate the industrial conditions. The obtained copper deposits were observed by SEM to highlight their morphology."

Jan 1, 1997

By Paul Dewison

For nine years, from mid-1987 to mid-1996, the copper market enjoyed what appeared to be an endless boom in which prices were much higher relative to production costs than for most other base metals. After the boom ended abruptly mid-1997 with the Sumitomo affair, copper was burdened by an overhang of new projects that promised to swamp demand in what, with the Asian financial and economic crisis of 1997, had become a considerably worse consumption environment. Now, demand prospects do not look so bad. If, as we suspect, we will be dealing with a more rational market in the future, it becomes all the more important to forecast accurately the prospects for consumption. In this paper, we present a new methodology for copper demand forecasting. The methodology forms the backbone of the demand-side analysis for the multi-client study entitled "Long Tenn Outlook for Copper", co-authored by Metalica Ltd. and Bloomsbury Minerals Economics (BME). Key components of the methodology are as follows. (1) Relate demand to economic structure. (2) Focus on products rather than refined consumption. (3) Apply a consistent products/applications analysis to all countries and time series. (4) Incorporate scrap market dynamics within the analytical framework.

Jan 1, 1999

By Xue Sun, Dengfu Chen, Yuting Chen, Mujun Long, Song Xu, Helin Fan

In order to seek an effective extraction process for vanadium, the recovery of vanadium from a high Ca/V ratio vanadium slag was studied by sodium roasting and ammonia leaching. In the present paper, the oxidation and leaching process of vanadium slag was investigated by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive X-ray spectrometry (SEM/EDS) techniques. The effects of ammonium carbonate concentration, leaching temperature and leaching time on the leaching ratio of vanadium were discussed. As indicated in the experimental result, the optimal (NH4)2CO3 concentration was 120g/L, leaching temperature was 60°C and leaching time was 20 min. Approximately 92% of the vanadium was recovered under the optimal conditions. Furthermore, by means of X-ray diffraction analysis, the phase transformations of the vanadium slag during roasting and leaching processes were analyzed and discussed.

Jan 1, 2014

By Mao Chen, Baojun Zhao, Zhixiang Cui, Leonel Contreras, Chuanbing Wei

Bottom blown oxygen copper smelting process developed at Dongying Fangyuan Nonferrous Metals shows many advantages such as flexible feed requirement, high productivity, low energy consumption and high direct copper recovery. However, the weak acid generated during the process is not stable which influences the waste management and continuous operation. The amount of the weak acid is determined by SO3 formed in copper smelting process. SO3 can be formed inside copper smelting furnace and boiler at different conditions. Effects of temperature and oxygen partial pressure on the formation of SO3 during copper smelting process have been discussed thermodynamically. Understanding of the mechanisms for SO3 formation will enable the operation of bottom blown copper smelting furnace to be optimized and generation of the weak acid in the process can be managed. The fundamentals developed in this study can also be applied to other copper smelting processes.

Jan 1, 2016

By Ashwini Kumar

Flame impingement on the burden is routinely encountered during the initial phase of melting in aluminum reverberatory furnaces. This impingement causes an obstructed pathway for the hot gases, and hence the circulation and residence time of the hot gases are greatly impacted. Moreover, as the load melts, the flames gradually achieve an unobstructed path leading to reduced gas residence times. This flame impingement and constantly changing combustion space volume will lead to vastly different fuel and oxidizer mixing patterns and thus affect the overall furnace performance. Fine tuning the burner operating conditions such as flow rates and injection angles with the changing combustion space could result in significant improvements to the furnace efficiency. However, one has to gain a better understanding of the furnace dynamics to know the suitable parameters to adjust. Physical modeling can be elaborate and expensive to conduct on a regular basis while Computational Fluid Dynamics (CFD) can cost-effectively address this challenge. In this study, the furnace model is created with a particular loading pattern to understand the flame dynamics in the presence of a piled load. This configuration can be thought of as a computational model of the furnace with the burden at a particular stage of the melting process. Thermal efficiency and behavior of the furnace are quantified and the predicted values are compared with the operational data from an experimental reverberatory furnace.

Jan 1, 2008

By Khalid Hattar, Alexander McGinnis, Buchheitm Thomas, Paul Kotula, Luke Brewer

"Understanding the effects of extensive radiation damage in structural metals provides necessary insight for predicting the performance of those metals considered for application in the extreme radiation environment. Predicting mechanical performance after long term radiation exposure is of great importance to extending the life of current nuclear reactors and for developing future materials for the next generation of reactors. A combination of finite element modeling, nanoindentation, and TEM characterization were used to rapidly determine the microstructure and mechanical properties influences of ion irradiation on a standard 3 l 6L stainless steel sample. The results of this study found that ion irradiation and small scale mechanical property testing can be used to characterize extensive levels of radiation damage structure, only when significant consideration is given to ion irradiation depth, surface roughness and polishing condition, the irradiation temperature, and many other experimental parameters.IntroductionFor either the success of next generation nuclear reactors or the extension of current nuclear reactors significantly beyond their designed lifetimes, research is needed into the degradation of the microstructure and mechanical properties governing the performance of the reactor alloys exposed to extreme environments. Although the exact dose and temperature of these nuclear reactor plans may vary, the cladding and other structural components will be exposed to greater dose and at elevated temperatures. To acco=odate these severe exposures, established cladding materials are being testing to longer exposure and new alloy compositions are being considered. [1-3] For neutron test facilities to reach 100 dpa level, exposure times often span several years, significantly limiting the down-select process of potential new materials for extreme radiation environments. Ion irradiation has been used as a technique to provide a look at the effect of irradiation damage on materials in a significantly shorter time frame. Previous work using proton irradiation provides a deep, broad, and relatively uniform defect profile compared to heavy ion irradiation; however, using this type of radiation still requires weeks to months to reach the 100 dpa level. [4] In this research, we investigated the feasibility of using heavy ion (nickel) irradiation and small scale mechanical testing to provide in a few days a first order screening technique for potential alloys that are being considered for advanced testing."

Jan 1, 2012

By C. Liliane Carvalho

In the current study, bio-oxidation tests were carried out in shaking flasks with a flotation concentrate containing the sulphides pyrite, arsenopyrite and gudmidite. The tests were performed with mesophilic microorganisms (At. ferrooxidans) at 30 °C and also with the moderate thermophile S. thermosulfidooxidans, at 50 °C. The effects of (i) previous adaptation of the microorganisms to the concentrate, (ii) ferrous iron concentration and (iii) pulp density (2%, 4% and 6% (w/v)) on the dissolution of the sulphide were studied through arsenic extractions. S. thermosulfidooxidans was more sensitive to the pulp density in comparison to At. ferrooxidans as a reduction in sulphide oxidation was observed with the increase in the solid content to 6%. Therefore, the mesophilic strain was selected for further work, which comprised a rolling bottle experiment at 10% solids. After 40 days of bio-oxidation, the solid material was subjected to cyanidation, which revealed 85% gold extraction as compared to 21% from the original concentrate. The antimony sulphide grains in the bio-oxidized product showed similarity to what was observed in the original sample, suggesting such particles were not susceptible to the bio-oxidation process.

By Yuanpei LAN, Minren XU, Deliang NIU, Zhu WANG, Qingcai Liu, Shan Ren

Removal of gas is the major function of RH degasser. To optimize the RH refining craft in Chongqing Iron and Steel Co. Ltd, the degassing effect of RH degasser at different degrees of vacuum was investigated using a vacuum induction furnace. In addition, the effect of processing time on the gas content dissolved in molten steel was also studied. The results showed that degree of vacuum was one of the important factors that determined the degassing efficiency in RH refining process. High vacuum degree is helpful in the removal of gas, especially in the removal of [H] dissolved in molten steel. The processing time could be reduced from 25-30 min to 15 minutes and gas content could also meet the demand of RH refining

Jan 1, 2015

"In this paper, a mobile heat treatment furnace from Akkermans Gloeitechniek, a Dutch company, was simulated with Computational Fluid Dynamics (CFD). The furnace is cylindrical with four oil burners, and large metal products such as dredging pumps and impellers can be flexibly heat treated to obtain required microstructure and mechanical properties through stress relief, annealing, hardening and tempering. The furnaces are exposed to the open air, and thus the heat loss becomes significant and varies from day to day and from season to season. Since the temperature of the metal products to be heat treated can only be measured on the surface, the temperature evolution inside the metal could not be tracked in practice. CFD simulation provides a useful tool to predict the temperature evolution within the metal pieces and within the combustion space of the furnace. Energy distribution and heat loss can be subsequently estimated. An overall energy balance through temperature measurement indicted relatively low energy efficiency. Especially during the soaking period, the high energy supplied is barely used to compensate the heat loss of the furnace to maintain a constant temperature of the metal piece. The current CFD modeling aims to give advice on how to modify the design and optimize the operation to reach higher energy efficiency and low heat loss. The CFD model consists of turbulent combustion model, radiation model in participating media, and conjugate heat transfer between the combustion space and solid metal. Temperature measurement was carried out to provide thermal boundary conditions and overall energy balance of the operation. After the model validation with temperature measurement within the combustion space and metal surfaces, furnace optimization will be conducted.IntroductionHeat treatment is a common practice in metal production and manufacturing industries. Through heat treatment at certain temperatures with special patterns, unique mechanical properties of the metals and the metallic products could be obtained. ""Akkermans Gloeitechniek"" is a company situated in K.inderdijk, at location of LHC-Holland (www.ihccaland.com), the Netherlands. Heat treatment of metals is its core business. Various type of heat treatment are applied, such as stress relieving, soft annealing and hardening (quenching), tempering, transformation and precipitation. At the company 6 furnaces are in operation and the 7th is being built"

Jan 1, 2004

By B. M. Fisher

A process for making electrolytic copper of high quality from copper flotation concentrates is described. The concentrates are first slurried and then subjected to a high-temperature, high-pressure, oxidation-leaching operation under controlled conditions. The resulting slurry from the oxidation-leaching operation is cooled or flashed to atmospheric pressure and then subjected to a solids-liquid separation. The separated liquor, containing the recovered copper values, is cooled and then fed to an electrolytic deposition operation where metallic copper cathodes of high purity are produced. The spent electrolyte is then subjected to a sulfide treatment to precipitate the residual amounts of copper not deposited in the electrolytic cells. The precipitated copper sulfide is recovered and recycled in the form of a slurry to the initial stages of the process.

Jan 1, 1976

By Tae-Hyun Kim, Kang-In Rhee, Jeong-Soo Sohn

The synthesis of Mn-Zn ferrite powder from spent zinc-carbon batteries was investigated using a series of physical treatment, sulfuric acid leaching and coprecipitation. Physical separation methods such as crushing, magnetic separation and sieving were applied to generate a non-magnetic material of 8- mesh undersize for subsequent leaching process. The 8-mesh undersize of the spent zinc-carbon batteries was assayed 23.9% Mn, 14.9% Zn, and 4% Fe. Metal extractions obtained in sulfuric acid leaching at the solid/liquid ratio of 1:10, 2 M H2SO4, and 60? with 6 vol.% H2O2 addition were 97.9% Mn, 98.0% Zn and 55.2% Fe. The leach liquor was finally adjusted to the Mn:Zn:Fe mole ratio of 1:1:4 suitable for producing MnZnFe4O8 ferrite powder by the addition of Mn, Zn and Fe sulfates followed by pH control. A co-precipitation test for Mn-Zn ferrite powder was performed at 80?, O2 gas flowing at 1.3 L/min. As a result of co-precipitation, Mn-Zn ferrite nanoparticles in 20 nm size with spinel structure were successfully synthesized. The saturation magnetizations of Mn-Zn ferrite powder (Mn1-xZnxFe2O4) were determined to be 39-91 emu/g with various zinc contents (X=0.2-0.8).

Jan 1, 2008

By Peter M. DiGiacomo

In situ leaching technology requires information about how injected fluids flow in the rock in relation to the localization of the valuable minerals to be leached. In oxidative leaching of sulfide copper ores, flow channels can be determined by the observation of residual iron oxides. In contrast oxide copper ores do not leave a detectable residue after leaching. Method is developed that allows a selective labeling of the leach residue with fluorescent compounds. The fluorescent zones can be detected in corings after the leaching operation.

Jan 1, 1981

By L. Yin, R. B. Haber, N. Sobh, D. A. Tortorelli, R. W. Hyland Jr.

"We optimize continuous quench process parameters to produce a desired precipitate distribution in aluminum alloy extrudates. To perform this task, an optimization problem is defined and solved using a standard nonlinear programming algorithm. Ingredients of this algorithm include a cost function, constraint functions and their sensitivities with respect to the process parameters. These functions are dependent on the temperature and precipitate size which are obtained by balancing energy to determine the temperature distribution and by using a reaction-rate theory to determine a discrete precipitate particle size distribution. Both the temperature and the precipitate models are solved via the finite element method. Since we use a discrete particle size model, there are as many as 105 degrees-of-freedom per finite element node. After we compute the temperature and precipitate size distributions, we must also compute their sensitivities. This seemingly intractable computational task is resolved by using an element-by-element discontinuous Galerkin finite element formulation and a direct differentiation sensitivity analysis which allows us to perform all of the computations on a PC.1 IntroductionThis work addresses the need for an integrated design capability that links microstructure evolution to the process parameters. It is motivated by the manufacture of lightweight aluminum-alloy extrusions for use in automotive structures. Aluminum alloys offer obvious benefits, however, care must be taken to manufacture favorable microstructures that ensure acceptable structural performance. For example, the manufacturing process for 6000-series components involves hot extrusion of cast aluminum billets followed by either an air or water quench process. The bill~t's initial grain structure is dramatically altered during extrusion by massive mechanical deformations and recrystallization processes. The microstructure continues to evolve during the quench, as complex chemical processes determine the formation of precipitates. The control of the precipit'ate size distribution is vital. Indeed, large precipitates located on grain boundaries serve as crack initiation sites which adversely effect structural crash· worthiness."

Jan 1, 2000

By D. T. Smith, L. M. Hsiung, J. J. Schmitt, J. W. Golz, R. L. Lankey, H. N. G. Wadley, J. Z. Zhang, B. L. Halpern

"The microstructure and mechanical properties of Al/AI2O 3 metal-oxide nanolaminates fabricated by' a novel Jet Vapor Deposition (JVD) process at substrate temperatures of ~25° and -250°C have been investigated using transmission electron microscopy (TEM) and nanoindentation methods. The thickness of the oxide layer was held constant between 2 and 5 nm, whilst the Al layer thickness was systematically varied from -3 to -50 nm. Continuity of the Al layers was significantly improved when the nanolaminates were deposited at an elevated substrate temperature (-250°C). The yield strength of the nanolamintes with Al layers greater than -25 nm follows a Hall-Petch type relationship, whereas that of the nanolaminates with Al layers less than -25 nm is better predicted by a Koehler-Lehoczky strengthening model. IntroductionAluminum-aluminum oxide (presumably A12O3) nanolaminates have been recently fabricated using a novel Jet Vapor Deposition (ND) process developed and patented by Jet Process Corporation [1-4]. ND uses sonic, high purity helium (He) gas jets to entrain atomically dispersed vapor and deposit films. It is of interest here because it can deposit multilayered structures (laminates) inexpensively at high rates. Materials with a thin, multilayer structure are of interest because they potentially offer novel mechanical and physical properties [5]. Koehler in 1970 used an image force model to investigate the strength of laminated materials and proposed the use of alternating layers of high and low shear modulus metals to produce high strength composite materials [6]. He predicted that dislocations would have to overcome a large repulsive image force in order to move from metal layer B of lower shear modulus (uB) into metal layer A of higher shear modulus (uA)' The image force (F) is given by the relation:"

Jan 1, 1994

By B. W. Lightfoot, Neill F. Arthur

"The AusIron process is a new development of the well established Ausmelt bath smelting technology(l). The development of this technology has been tied to the South Australian Steel and Energy (SASE) project which brings dedicated coal and iron resources together with this new technology. SASE is a joint venture between Ausmelt (40%), Meekathara Minerals (40%) and the South Australian Government through Mines and Energy South Australia (MESA) (20%). It will use a multiple lance furnace to process iron ore using steaming coal for both fuel and reductant.It is intended to build the simplest plant economically possible. Refinements such as preheating and prereduction of the ore are compatible with the technology but are not expected to be necessary in the first generation plant.The joint venture is negotiating with suitable partners for funding of the project through to commercial implementation at a target scale of2.5 mt/a of pig iron.ObjectivesAusIron aims to produce pig iron directly from steaming coal and from any of a variety of iron sources in a simple furnace system with a minimum of pre-processing of either coal or iron ore. Preheating and prereduction of ore are compatible with the technology but may not be necessary. The immediate aim is not to be the technology that uses the least quantity of coal to produce iron metal but rather the technology that uses the least number of dollars to produce metal.The chemistry of iron making is well known, probably better known than that of smelting of any other metal. Iron has been made for thousands of years and it is possible to make iron from charcoal and ore in a simple blast furnace the size of a beer barrel. The focus is therefore not making iron but rather making it more cheaply than it is made by current technologies. Large blast furnaces now set the standard and new technologies must perform better if they are to gain market share. It is still the cost of iron, energy units and capital going into these mega blast furnaces which ultimately set the market price for pig iron."

Jan 1, 1996