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By Renato G. Bautista

The solvent extraction separation of nickel, cobalt and their associated metals have been considered for industrial application since the early 1960's. This review of the solvent extraction processes is limited to the industrial applications, pilot plant and the more extensive bench scale studies reported in the literature. The processes with their significant chemical and technological contributions are discussed in detail whenever the information are available. The application of solvent extraction to the nickel-cobalt processing has so far been limited to the secondary separation of nickel-cobalt containing feedstocks derived from other primary nickel-cobalt separation methods.

Jan 1, 1993

By Hang Goo Kim

A computer simulation has been carried out to predict the distribution behavior of minor elements such as Pb. Zn, Bi, Sb and As in recently proposed copper smelting and converting processes with submerged oxygen injection in which tonnage oxygen is used with a shielding gas. In this study the technique of stepwise equilibrium modeling was employed and some of the thermodynamic data were updated or reassessed. The volatilization and slagging of undesirable elements were investigated in copper smelting (steady-state) system, copper matte converting (batch) system, and the combined (smelting + converting) system at extremly high oxygen-enrichment levels. The predicted minor-element behavior under high oxygen- enrichment was compared with that in the Noranda process (normally 42% oxygen-enrichment in smelting and 24% in converting) and the reverberatory process using air. The effects of various operating parameters such as temperature, the final matte grade in smelting, the initial matte grade in converting and the O/Fe ratio in slag on the behavior of minor elements are discussed.

Jan 1, 1991

By Toshiki Kabutomori

In fuel cell powered automobiles, hydrogen is required to be stored in materials that have a hydrogen storage density of over 4 mass%; further, these materials should be capable of supplying hydrogen by using the waste heat from a fuel cell, which is at a temperature of 373 K, in order to match the mileage of gasoline-powered vehicles. A Ti-Cr-V alloy, which exhibits a BCC structure and forms a solid solution, is a promising candidate for onboard hydrogen storage materials. Although it has a large hydrogen storage capacity of over 3.9 mass%, the rechargeable hydrogen capacity is limited to approximately 2.6 mass%. In this study, the effects of fine pulverization of the alloy on PCT (hydrogen pressure-composition-isotherm) characteristics were investigated in order to improve the rechargeable hydrogen storage capacity of the alloy. From the PCT measurements of the finely pulverized samples of the alloy, a plateau in the absorption curve was observed to begin at a hydrogen concentration of 0.5 mass%; further, a rechargeable hydrogen storage capacity of 3.3 mass% was obtained. This was greater than that obtained from the sample that was not finely pulverized, i.e., 2.5 mass%. However, the plateau width in the desorption curve was 2.5 mass%, which was the same as that observed for the sample that was not finely pulverized. The increase in the rechargeable hydrogen capacity during absorption is attributed to the precipitation of the -hydride phase (MH~2) directly from the metal phase (phase). The precipitation of the phase (MH~0.5), which should be formed in low hydrogen concentrations, is suppressed as a result of a possible reduction in the internal defects such as dislocations, vacancies, and grain boundaries by fine pulverization and annealing of the alloy.

Jan 1, 2006

By R. Elliott, H. Bayati

"Effect of time and temperature on microstructure and mechanical properties of an austempered ductile iron, ADI, of composition 3.6%C, 2.6%Si, 0.4%Cu, 0.2%Mn are reported. Xray analysis and. microstructural observations indicate that lowering the working temperature, aging temperature, increases the lifetime of ADI significantly. Results show· that lowering the aging temperature increases the strength and reduces the ductility of ADI. DSC traces for ADI austempered at 340°C are presented. Comparison of the DSC analysis and kinetic measurements demonstrates that the DSC traces can be· used to predict the life time of ADI successfully.IntroductionAustempered ductile iron, ADI, is one of the most significant developments in cast iron technology over the past two decades. Outstanding properties of high yield, ultimate strength, ductility, fatigue and wear· resistance make ADI suitable for a range of applications including gears, connecting rods, crankshafts and agriculture machine components. The austempering reaction in cast iron occurs in two stages, Fig. I, in contrast to the single stage reaction in steel. In stage I the relatively low carbon austenite produced during austenitising transforms into ferritic plates and high carbon austenite, a metastable structure called·ausferrite. The high carbon ailstenite and supersaturated ferrite produced in stage I decompose into ferrite and carbide in stage II: to form a structure similar to the bainitic structure in steel. This behaviour exposes a well-defined processing window, t1 - t2, over which the maximum amount of ausferrite is produced, Figure 1. Whereas the bainitic structure determines the properties of austempered steel, ADI properties are mainly affected by volume fraction of retained austenite (VRA), austenite carbon content (ACC), unreacted or martensite volume fraction (UA V), compositiori and amount of carbides, and morphology of ferritic plates[l,2]. Due to the detrimental .effect of martensite and carbides on properties of ADI, an ideal structure of ADI consists only of ausferrite [l,2]. Thus, it is common to determine the processing window for each austempering treatment in order to identify the optimized austempering time. Decomposition of austenite (stage II) signals the end of the life time for an ADI component, therefore, the aging behaviour of ADI at different working conditions can be studied by determining the t2."

Jan 1, 2000

By Ali Hasham

Reduction rates of FeO in CaO-SiO2-Al2O3 slags by Fe-C melts have been investigated experimentally at 1723 K. The rates were estimated using experimentally determined CO(g) evolution rates. Flash X-ray images were employed to visualize the behavior of the melt-slag interface during the reactions. The influence of melt interface was examined by conducting two types of experiments - (i) dropping one (or several) Fe-C droplet(s) weighing 2 g into the molten slag bath, and (ii) dropping a small amount (10-30 g) of slag onto a Fe-C melt weighing 400 g. The rates from both types of experiments were compared and analyzed to determine the rate limiting steps. It was established that neither the carbon transport in the Fe-C melt, nor the transport of gas species in the gas film adjacent to Fe-C melt was responsible in limiting the reaction rate. It is possible that the slag phase mass transport may be controlling the initial reduction rate in the droplet experiments. However, a, different mechanism was responsible in limiting the reduction reaction when the overall %C in the droplets fell to about 2-3.

Jan 1, 1992

By Evgueni Jak

Pyrometallurgy is an important sector of modern industrial society actively participating in solving current environmental, economic, materials scarcity and other challenges. Recent advances in analytical methods, experimental techniques, thermodynamic, phase equilibria and process modelling tools provide new opportunities to increase the productivity of pyrometallurgical reactors, the treatment of complex feeds and metal recoveries. Fundamental theoretical models can now be used to make a significant next step towards the development and implementation of computerised models describing real industrial processes—Virtual Reactors, and computer-aided smart-decision-making systems that may be called Pyro-GPS by analogy to GPS; these developments can facilitate knowledge-based improvement and optimisation strategies. The implementation of these improvements require ongoing collaboration between researchers, industry and government.

By Willem P. C. Duyvesteyn

A novel hydrometallurgical process for Escondida copper concentrates has been developed by The Minerals Laboratory of BHP. The Escondida Process consists of concentrate leaching, solution purification, electrowinning and residue flotation. Part of the copper will be sold as high grade concentrate and part as high purity SX-EW copper. Contrary to previous efforts for the development of a hydrometallurgical process for copper concentrates, this patented process does not advocate the total dissolution of copper. It only aims for the copper that is readily soluble in a mildly oxidizing environment with an ammoniacal or acidic lixiviant. Both lixiviants were studied, but ammonia was preferred because of fast kinetics at ambient temperatures and pressures. By controlling the oxidation potential, the formation of sulfate ions and, consequently, of an ammonium sulfate byproduct, is precluded. These mild leaching conditions also prevent the dissolution of unwanted impurities and result in the production of ultra-high purity electrowon copper. Solution purification is carried out by solvent extraction with LIX-54. The very high loading capacity of this organic results in a compact SX circuit, consisting of two loading, one scrubbing, and one stripping stage. As the organic is selective for simple copper ions, the copper amine complex is broken down and free ammonia is regenerated and recycled for leaching. High purity copper cathodes are produced in a conventional sulfuric acid based electrowinning system. One scrubbing step is needed to separate the ammoniacal circuit from the acid circuit. Limiting copper dissolution to less than 50% also provides an opportunity to produce high grade concentrates by residue flotation. Copper recoveries in excess of 98% with precious metal values reporting to the final concentrate can readily be obtained. Complete breakdown of the copper mineral- pyrite middlings results in a final concentrate grade that can be even higher than the original feed material. The Escondida Process also provides an opportunity to accept lower grade copper concentrates producing improved copper recoveries in the mill and yet high quality concentrates for marketing. The Paul E. Queoeau International

Jan 1, 1993

By Jing-she Li, Hai-yan Tang, Cheng-song Liu, Wei Liu

"In order to effectively utilize cheap and low quality iron ores, a hematite ore in a certain steel plant in Xinjiang was researched on to obtain ""iron increase and silicon reduction"" by ore dressing operation experiment and the performance indexes of the hematite ore were optimized. Based on the fundamental characteristics and high-temperature properties of the concentrate after ore dressing and other five kinds of iron ores which were co=only used in this steel plant, ore matching principles were proposed and a sintering ore blending optimization model was established. Finally, sinter pot test was carried out to verify the validity and practicability of the sintering ore blending optimization model which was aimed at giving consideration to the sintering indexes and the cost.IntroductionIn recent years, the price of imported iron ore with high quality is always at a high level, while iron ore self-sufficient rate in China is less than 50%. Enormous market demand and high dependence of domestic enterprises on imported iron ore makes the price of it hardly return to rational. In order to get rid of the situation of long-term meager profit and even deficit, more and more iron and steel enterprises in China transit their focus of reducing production cost to the utilization and development of relatively cheap but low-grade iron ore resources at home[l-4l_ However, besides the disadvantages of low iron grade, high content of impurities and complex embedded properties, the high-temperature properties of iron ore often go beyond the suitable ranges for producing sinter with high quality. Thus directly utilization of this kind of iron ore without ore dressing process would probably affect the metallurgical performance and indexes of sinter ore.Previous research and production practice have shown that traditional iron ore matching in sintering mainly focus on the reasonable collocation of properties of iron ores with low quality and high quality, but pay less attention to ore dressing process of low quality iron ores and matching them with high quality iron ores. Actually, compare with directly utilization, iron ores with low quality after ore dressing have higher suitability for matching with high quality ones which is beneficial to reduce the consumption of iron ores with high quality and control the production cost of sintering [5-s1."

Jan 1, 2014

By Leiting Shen

The thermodynamics of tungsten ore decomposition in mineral acid and alkaline solutions were studied. The published thermodynamic data of tungsten minerals were collected and assessed. The Gibbs energies of CaWO4 (−1538.43 kJ/mol), FeWO4 (−1053.91 kJ/mol), MnWO4 (−1206.08 kJ/mol), H2WO4 (−1003.92 kJ/ mol), and Na2WO4 (−1455.58 kJ/mol, aq) at 25 °C were adopted in the calculation using HSC software. The results show that CaWO4 is decomposed more readily in Na2CO3 solution than in NaOH,while FeWO4 andMnWO4 aremore reactive inNaOH solutions. Froma thermodynamic point of view, tungsten ore decomposes easily in acid solutions despite most ΔGo T increasing slightly with temperature. Oxidizing Fe2+ to Fe3+ in acidic solutions facilitates decomposition of FeWO4, and the reaction of CaWO4 in H2SO4 solution occurs more easily than in other mineral acids, due to the formation of sparsely soluble CaSO4. The results fit well with the experimental data and industrial experience previously reported in the literature.

By Dachun Liu, Lei Shi, Yongnian Dai, Bin Yang, Yang Tian, Tao Qu

The carbonthermal reduction of high Mg–Si nickel laterite was studied under vacuum. The effects of adding calcium oxide and the reducing agent on the reduction of silicon in residue were studied at pressures of 10–200 Pa and different temperatures, with varying proportions of carbon and CaO. The analysis of the residue was performed using X-ray diffraction and chemical composition analysis. The results show the following: At 1350 °C with a C/O ratio of 1.5:1, the recovery of Si reached a maximum 71.09%. Under these conditions, Si exists mainly in the forms of Fe3Si, Fe2Si, FeSi and SiC. The recovery of Si was above 80% when the temperature was 1450 °C, the C/O ratio 1:1, and 15% addition of CaO. When CaO addition was 22.61%, all of the solid phase was Ca2SiO4.

Mar 1, 2017

By Vladimiros G. Papangelakis

During the past five years, chemical modelling work at the University of Toronto has elucidated the role of soluble magnesium on the autoclave acidity and has demonstrated why feeds rich in magnesium, and other divalent metals, require more than the stoichiometric requirements in acid to produce a leaching performance comparable to that of low magnesium feeds. This understanding has allowed the calculation of acid additions to the pressure acid leach (PAL) on a less empirical basis. Optimizing acid additions to the PAL confers savings in neutralization costs, ensures high productivity and minimises corrosion problems. Hence, our picture of the solution chemistry inside the autoclave during the PAL process has been substantially improved and is reviewed here. Experimental techniques based on solubility and direct acidity measurements that support the theoretical predictions are presented. Concepts of chemical modelling of electrolyte systems at high temperature and software issues are also discussed. Finally, a better understanding of the solution chemistry at temperature has led to better kinetics models because all metal dissolution and precipitation reactions are acid driven and controlled. . Therefore, reactor modelling efforts by our group are also presented and a reactor model with very good performance, as compared to pilot-plant data, is also made here. Finally, in spite of the above success in PAL solution chemistry and reactor modelling, significant challenges lie ahead in theoretical data gaps and instrumentation; these are also discussed in this paper. Keywords: Laterites, process modelling, pressure acid leach, solution chemistry, chemical modelling, reactor simulation

Jan 1, 2004

By Wilhelm Brandstätter, Johannes Steiner, Alois Triessnig, Christian Redl

"The results of numerical simulations of bubble detachment from an orifice in a horizontal plate submerged in liquid are presented. The bubbles are created by forcing gas through this orifice into stagnant liquid. The simulations are performed with a two-dimensional incompressible Lattice Boltzmann (LB) scheme. In previous works the same problem was investigated by two-phase simulations in which surface tension effects were considered by an interaction potential formulation between the phases. In contrast, in the present work a volume of fluid (VOF) model consisting of a carrier fluid and a passively advected scalar function for the calculation of gravitational and surface tension forces, respectively, is used. The aims of this study are to examine the applicability of the one-phase LB method to the numerical analysis of bubble formation and to verify the theoretical and experimental predictions of the dependencies of the departure diameter on gravitational forces, surface forces and wettability effects. To this purpose the simulations were performed at different values of gravitational acceleration g, surface tension coefficient s and contact angle ß. Nonlinear fits to the data yield functional dependencies which are in good agreement with the predictions. IntroductionBubble formation behavior is an extensively studied subject, especially in chemical engineering, power industries and metallurgical processing. Knowledge of the underlying physics of bubble motion is, for example, required for the design of chemical reaction towers and agitation tanks. Another important application is the argon gas injection through the wall of the tundish nozzle into liquid steel stream to deter clogging with solid inclusions. Argon bubble motion and its effect on flow depends greatly on different parameters, e.g. gas flow rate and size of the bubbles. Thus, if these bubbles are not managed properly, they can become encapsulated upon solidification and result in undesirable impurities in the material [1, 2]."

Jan 1, 2004

By C. Kathryn Sole

The close proximity of cobalt and nickel on the Periodic Table and their frequent occurrence together in nature means that their separation in primary hydrometallurgical flowsheets is not only often necessary, but requires the use of innovative chemistry to achieve high selectivity. Today, increasingly stringent demands for the high-purity cobalt and nickel salts required for battery applications in consumer electronics, electric vehicles, and solar applications are again challenging the state of the art. The evolution of cobalt–nickel separations is traced from the basic precipitation technologies employed in 1960s, through commissioning of the first cobalt solvent-extraction plant in South Africa in 1974, to the commercialisation of organophosphinic-acid extractants (which provided a step-change improvement in selectivity) and their eventual widespread use in the 1980s and ’90s. This was followed later by their sulphur analogue, which enabled different possibilities for laterite processing in the new millennium. Separations in chloride media, which take advantage of the different speciation chemistries, and nickel extraction by oximes in ammoniacal systems are also discussed. More recently, chelating and solvent-impregnated resins have added further dimensions to the possibilities for flowsheet design and enabled higher purity products to be attained from both primary and secondary sources. Selected case studies and flowsheets are described.

By Shadia Ikhmayies

In this work Thermo-Calc software was used to calculate the phase diagram of the Fe–Si system. The deduced phase diagram includes twenty fields, where three fields represent pure phases; two solid solutions and a liquid phase. There are several fields of two co-existing phases; mixed solid phases, and mixed solid with liquid phases. A set of eutectic and eutectoid points were found, where transformation reactions and temperatures were identified. The results were compared with results in the literature and good agreements with some differences were found. This study is a step to understand the phase diagram of Ca–Fe-Si system for refining metallugical grade silicon (MG-Si).

Mar 1, 2018

By Muammer Kaya

This paper reviews the existing and state of art knowledge for electronic waste (e-waste) recycling. Electrical/electronic equipments (EEEs) which are unwanted, broken or discarded by their original users are known as e-waste. The main purpose of this study is to provide a review of e-waste problem, give e-waste management strategies and introduce various physical e-waste recycling processes with special attention towards extraction of both metallic values and nonmetallic substances. The hazards arise from the presence of heavy metals (e.g. Hg, Cd, Pb etc.), brominated flame retardants (BFRs) and other potentially harmful substances in e-waste. Due to the presence of these substances, e-waste is generally considered as hazardous waste and may pose significant human and environmental health risks if improperly managed. This review paper describes the potential hazards and economic opportunities of e-waste. First of all, an overview of e-waste/printed circuit board (PCB) components and substances are given. Current status and future perspectives of e-waste and waste PCB recycling techniques are described. E-waste characterization, dismantling, liberation, classification and separation processes, are also covered. Manual selective dismantling after desoldering and metal-nonmetal liberation at −150 μm with two step crushing are seen to be the best techniques. After size reduction, mainly physical separation processes employing gravity, electrostatic, magnetic separators etc., which are commonly used in mineral processing, have been critically reviewed here for separation of metals and nonmetals. The recovery of pure metals from e-waste after physical separation can be performed by pyrometallurgical, hydrometallurgical or biohydro metallurgical routes, which are not covered here. Suitable PCB recycling flowsheets for industrial applications are also given. E-waste recycling will be a very important sector in the near future from economic and environmental perspectives for both developing and developed countries. Recycling technology aims to take today’s waste and turn it into conflict-free, sustainable polymetallic secondary resources (i.e. Urban Mining) for tomorrow. Recycling technology must ensure that e-waste is processed in an environmentally friendly manner, with high metal/nonmetal recovery efficiency a lowered carbon footprint. Taking into consideration our depleting natural resources, this Urban Mining approach offers quite a few benefits; it provides a substantial secondary resource, while also ensuring that the environment is kept free from harmful toxins in e-waste. This results in increased energy efficiency and lowers demand for mining of new raw materials.

Mar 1, 2017

By G. Mark Aylmore

Various processes have been developed using a combination of elevated temperature and chemical treatment processing to recover Li from silicate minerals. To facilitate further process development, a comprehensive understanding of the deportment of Li and associated minerals in ore bodies is essential to allow the industry to predict the response of ore reserves to metallurgical treatment options. This paper describes results from the integrated use of the John de Laeter Centre’s state of the art analytical and mass spectrometry techniques to characterise a selection of Li bearing ore bodies and determine their amenability to potential processing options for the extraction of Li. The mineralogy, mineral associations, and liberation characteristics of ore-bearing and gangue minerals were characterised using a combination of the TIMA and XRPD studies. The Li content and distribution within minerals were defined using LA-ICPMS and field emission scanning electron microscopy techniques (EBSD, ToF-SIMS) and atomic probe microscopy.

By T. K. Bundtzen

Placer gold in the Iditarod and Innoko mining camps of western Alaska is derived from a suite of comagmatic, Late Cretaceous to Early Tertiary, alkali-calcic, meta-aluminous. volcanic-plutonic complexes and peralumi-nous rhyolite sills that intrude Mesozoic flysch. Heavy-mineral concentrates from 42 mining operations and streams draining known mineralized areas in the igneous complexes contain placer gold and a variety of ore minerals derived from epithermal to hypothermal conditions of formation. The minerals include cassiterite, ilmenorutile, samarskite, cinnabar, scheelite, chromite, stibnite, silver sulfosalts, monazite, and zircon. Results of the study show that 1) cinnabar. stibnite, and quartz formed with the bulk of the placer gold in an epithermal lode environment, 2) chromite appears to have originated in mafic phases of monzonite plutons and alkalic basalts, and 3) niobium-tin-tungsten-uranium-silver values may have been derived from stockwork accumulations in cupolas of monzonite plutons.

Jan 1, 1987

By Kenneth McGowan

"The aluminum industry is the 5th largest consumer of energy and the largest consumer of energy on a per-weight basis. Process heating accounts for 25% of the energy consumed to manufacture aluminum. Consequently, the generation of this energy results in the production of a significant amount of CO2 (over 3.75 million metric tons in 2003)1. As a result, the Aluminum Industry Technology Roadmap of 2003 listed the development of improved refractory materials as a goal to reduce energy use and decrease greenhouse gas creation. The result of a R&D effort addressing this desire is the development of patented microporous refractory materials for metal contact applications in all furnace areas including the belly band. It has been demonstrated that this material can reduce energy consumption up to 38% in furnaces and significantly reduce heat loss in launder and trough systems. Furthermore the material developed is non-wetting and remains un-penetrated by metal throughout its lifetime. The material does not contribute to the formation of corundum. As a result, the energy efficiency of an older lining remains intact compared to standard refractory materials which may have an initial high insulating value (such as lightweights and board) or standard dense refractory (even with penetration inhibitors) both of which show a rapid increase in thermal conductivity as the refractory is penetrated with aluminum and formed corundumIntroductionThe aluminum industry is the second largest producer of metal in the United States, behind the iron and steel industry. It is the 5th largest consumer of energy and the largest consumer of energy on a per-weight basis. Process heating is required to melt, hold, purify, alloy, and heat treat the metal and accounts for 25% of the energy consumed to manufacture aluminum. As such, process heating is the second largest energy consuming operation. Smelting, which utilizes an electrolytic reduction process is the largest energy consuming operation1.Most process heating is accomplished through the use of fossil fuels, either directly or indirectly. The choice of fuel is dependent on a plant’s location and fossil fuel availability. Table I shows the processes impacted by refractories and the calculated BTU’s generated by usage of the respective fuels as well as the Metric Tons (MT) of metal passed through each process in 20001."

Jan 1, 2009

By Jian-guang Yang, Lei Jie, Si-yao Peng, Jian-ying Yang

A new membrane electrolysis process for bismuth recovery from bismuthinite concentrate was introduced. Under the conditions of temperature 70 degrees C, acidity 3 mol/L, solid liquid ratio 1:4 and 1.1 times stoichiometry sodium chlorate dosage for 1.5 h oxidation leaching, more than 98.5% bismuth can be leached from bismuthinite concentrate. The resultant leach solution was subjected to membrane electrolysis. Under the conditions of NaCl concentration 300 g/L and pH 7 in anolyte, bismuth ions concentration 80 g/L and HCl concentration 3 mol/L in catholyte, heteropole distance 6 cm, temperature 40 degrees C and current density 200 A/m2, a flat deposited bismuth plate can be obtained after 24 h electrolysis, and the bismuth purity was more than 99%. The current efficiency of cathode was 97.88%. Chemical component analysis results showed that the average convert efficiency of the sodium chlorate was 52.77% and the average oxidizing efficiency of chloride ion was 69.78%, and the resultant anolyte generated in anode compartment could be fully reused as oxidant for leaching bismuthinite concentrate again.

Mar 1, 2017

By B. R. Davis, Neale R. Neelameggham, R. E. Brown

The element Calcium element has a unique place in the production of etals, intermetallics and other compounds. The unusualness arises from the fact that we have several possible reductants – metallic calcium, calcium carbide, calcium cyanamide and calcium hydride. A review of how metallic calcium is manufactured and utilized is presented. The difficulties involved in producing the metal in large quantities and price implications are noted. . Fundamental thermodynamics of how these act as reductants are shown, along with the historic application of these in metal production during the past century and a half. Alternate applications as to how to control the cost of the reductant is indicated, such as the numerous attempts in making low cost titanium utilizing direct or indirect calcium reductant.

Jan 1, 2014