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By Gabriel Zarate

Mantoverde is a heap leach-SX-EW plant that was commissioned in December 1995 at a production rate of 42,130 tonnes of copper per year and 5.4 million tonnes of ore per year. Copper production was steadily increased reaching a maximum of 62,239 tonnes in 2012 for an ore throughput of 10,5 million tonnes. In order to get these production and throughput rates, a number of changes have been made in the metallurgical parameters of the plant operation since the start up, among them particle size, heap height, acid addition distribution in curing and leaching solution, leach cycles and pad type. Most of the modifications have been implemented after carrying out extensive column test work programs. The modifications implemented and the results obtained, as well as the test work programs carried out, are discussed in this paper.

By N. M. S. Balbinot, A. L. Rodríguez, C. M. Mahlmann, R. de C. de S. Schneider

The use of sunflower oil co-products it was studied for production thermoplastic composites. Thermoplastic composites have been processed in polyethylene matrices of virgin linear low density polyethylene (LLDP) or recycled. Samples have been formulated with 10% mass fraction of sunflower bran, seed coat and mixture of bran and seed coat. The material characterization has been achieved by mechanical tensile test and Shore D hardness and by density physical testing. The results have demonstrated better properties to thermoplastic composites with sunflower seed coat.

Jan 1, 2008

By G. Nazari

ERAMET, through its subsidiary COMILOG, have rights to a rich niobium and rare earth deposit inGabon. The Mabounié deposit, is located 50 kmfromthe town of Lambaréné, in a fairly remote location. ERAMET has been developing a process to recover value metals for several years, and approached Hatch Ltd. to design a sizeable Demonstration Plant to help them further optimize the process, and prove the flowsheet is technically viable. The process employs concentration techniques to recover an upgraded Nb/REE feed material for processing in the subsequent leach step. Rare earths and niobium are selectively leached, and subsequently precipitated. Following precipitation, rare earths undergo bulk separation and are purified to produce LRE and mixed MRE/HRE products, which will be further processed by Third Parties. This paper provides a high-level overview of the process, summarizes the motivation for a Demonstration Plant in the vicinity of the deposit, and discusses technical challenges faced during the flowsheet definition and design phase. Key challenges are focused on and summaries of the methodologies used to address each challenge, as well as the solutions to overcome the challenges, are discussed. The paper provides motivation for further process simplification and concludes with a project update.

By Bo Jiang, Lianyun Liu, Hongmin Zhu, Kai Huang

"Watermelon peel is selected as a novel adsorbent to remove Pb(II) from aqueous solution. A simple saponification process is proposed to modify the peel and the adsorbent is characterized by SEM and FTIR. The effects of pH, contact time, initial concentration of Pb(ll), biosorbent dosage and temperature on adsorption of Pb(II) are investigated. Different models are used to fit experimental data. These models indicate that the adsorption process follows the Langmuir model and pseudo-second-order model. The maximum adsorption capacity obtained from Langmuir model is 1.05mol kg-1 for the prepared sorbent. Equilibrium time is attained in 5-10 min for the studied concentrations. The watermelon peel can be used as an effective and low-cost biosorbent for removal of Pb(ll) from aqueous solution.IntroductionRecently, removal of heavy metal ions from industrial effluents by biosorption has become a very attractive topic, since the more serious pollution issues caused by heavy metals emerge frequently, and more strict requirements for its control are called upon by society [1,2]. In this case, most conventional purification technologies are not suitable due to poor cost-effectiveness [3]. For example, chemical precipitation by alkaline reagents usually can not decrease the metal ion concentration below the permissive levels, and also it will produce a large amount of sludge containing toxic metals. Membrane separation techniques can realize deep purification of wastewater easily, although its operating cost is usually high. Thus, considering the high effectiveness, low cost and free-sludge operation, bisorption has become a promising technique in water treatment [4]. The most important thing for this technology is the synthesis of a suitable biosorbent, whose adsorption properties will determine the removal efficiency and economic cost for the whole process. Watermelon is one of the most popular fruits for mankind for its delicious flavor. Usually, the watermelon is consumed mainly for its edible pulp, and its peel is discarded or only used as feed for livestock. Considering the pectin contained in the watermelon peel, just like that in orange wastes in the reported literatures [3], the idea of using it as the raw material to prepare the biosorbents for heavy metal ions removal from the aqueous solution was evaluated in this study."

Jan 1, 2012

By Shun Myung Shin, Dong Hyo Yang

Cobalt is recovered from square type of spent lithium ion batteries (LIBs) containing 5~20 % Co, 5~7 % Li, 5~10 % Ni, 15% organic chemicals, and 7% plastics together with Cu, Al, Fe, and Mn. The waste LIB was prepared by physical treatment. After screening, the crushed LIBs were separated to +8 mesh, -8/+16 mesh, and -16 mesh powder. Among these, -16 mesh powder was selected for leaching. The leaching test was investigated at 2 M H2SO4, 6 vol.% H2O2, reaction temperature 60 ?, agitation speed 300 rpm, solid/liquid ratio 50 g/ 500 ml, reaction time 1 h. The leaching efficiency of cobalt was more than 99 % and its concentration was 24.9 g/L. For removing of impurities such as copper, iron, and aluminum in the leaching solution before cobalt solvent extraction, the impurities were eliminated by pH control with alkali solution. For selective extraction of cobalt, the aqueous phase removed impurities was equilibrated with different volumes of 0.4 M Cyanex 272 saponified of 50 %. Extraction efficiency of cobalt was about 80 % at first step. Separation coefficient (ßCo/Li) of cobalt and lithium extractions was 206.5. Over 9.0 % of pure cobalt sulfate solution was obtained after stripping with H2SO4 solution.

Jan 1, 2008

By Christian M. Sagedahl

The stringent environmental regulations for air pollution regarding emission control, along with the need of dry concentrates to feed autogenous smelting processes, are enhancing the development of cleaner technologies. Indirect drying of concentrates by a Kvaemer steam dryer is a technology with promising results, reducing dust entrainment to the exhaust gas stream and leading to smaller dust separation units. The Kvaemer dryers are designed for a very high availability, a high-energy efficiency, low amount and velocity of exhaust gases, no SO2, CO or CO, emissions combined with a wide range of satisfactory operating conditions and low total operational costs.

Jan 1, 1999

By Wen Chen, Xinghua Liu, Zeyou Peng, Qiulin Wang

"Limonite is a collective for iron hydroxide argillaceous materials. It is very difficult to be treated due to the wide variation in specific gravity and magnetism and the high argillization rate in the course of grinding and beneficiation. The iron ore in Huangmei, Hubei, China is the typical representative of limonite. If the limonite is processed using conventional physical beneficiation methods (e.g. magnetic separation, gravity separation, flocculation-desliming-flotation, or a combined process of the three), it can only be obtained an iron concentrate grade of 51.98% and an iron metal recovery of 86.64%. However, the technique of flash magnetic roasting-magnetic separation can improve the concentrate grade to 61.03%, iron recovery to 91.17%. This paper describes the tests of recovering limonite by flash magnetic roasting in detail.IntroductionLimonite (mFe2O3, nH2O)[1] is a general designation for hydrous iron hydroxides and argillaceous matters. Limonite is hard to be separated because of its complicated geneses, comparatively weak magnetism, nonuniform grain size and being easily slimed during grinding. So most small and medium enterprises sell deslimed limonite product which was dealt with just by simple methods of washing, magnetic separation or gravity separation and so on. In recent years with the iron ore prices soaring, significant progress was made in mineral processing research of limonite. Laboratory research and industrial test results showed that flocculation-desliming-flotation process and roasting-magnetic separation process are the two best methods to recover limonite till now. To compare these two methods, roasting-magnetic separation process is superior to flocculation-desliming-flotation process in aspects of beneficiation indexes and industrial stability."

Jan 1, 2012

By Aurelian Buzaianu, Cristian-Aurelian Popescu, Gabriela Popescu, Petru Moldovan

"A lot of scraps result in processing of composite materials which contain metallic phases that can be recovered and used again in different field. Considering this point of view the aim of the paper was to separate and recover aluminum from aluminum matrix/graphite composites. The separation and recovery of aluminum alloy from aluminum alloy/graphite composites was done by treatment with halide molten salts. As halide salts were used flux tablets that collect the ceramic particles in dross. After dross separation, was used filtration in order to separate the aluminum matrix from the other impurities.Samples from the recovered alloy were analyzed using chemical analysis, optical and electron microscopy, as well as X-ray diffraction. The desired composition of the aluminum alloy obtained from scraps could be reached by some addition of metals to the metallic phase. From optical microscopy it was obvious that the structure of the aluminum alloy obtained after composite reclamation consists large particle of silicon, eutectic, a-Al solid solution and other phases like Fe, Si, Mg and Ni, or some compounds like CuAl2. 1. IntroductionThe research on the recycling and reclamation of metal-matrix composites (MMCs) becomes active to preserve the natural environment, as environmental requirements become stricter, to save energy, and to reduce garbage. In case of recycled aluminum alloy ingot the production energy is about 3 pct of that of the new ingot. This evidence strongly supports the necessity to recycling of aluminum alloys. Among aluminum alloys, metal matrix composites have high strength and elastic modulus, and also good were resistance. These materials have been developed to meet the demand properties which exceeds that of the ordinary materials, and to save energy."

Jan 1, 2008

By Jong-Jin Pak

The present work reports the commercialization of a recycling process of spent acid to recover molybdenum. The process consists of ammonia gas neutralization of spent acid containing molybdenum, crystallization and filtration of ammonium molybdate, roasting and hydrogen reduction of molybdic oxide to produce a commercial grade molybdenum metal powder. The mother liquor, highly nitrogeneous residual solution after the filtration of ammonium molybdate, can be utilized to produce chemical fertilizers.

Jan 1, 2006

By James C. Sever

Two green field magnesium reduction plants are under consideration using dolomite as the raw material. The Calix calciner was independently selected for both plants. The unique design of this calciner is detailed and the advantages defined for the specific application. The low carbon foot print of this unit combined with the ability to capture food grade carbon dioxide makes this an environmentally proactive approach to carboniferous ore calcination.

Jan 1, 2015

The present work is mainly focused on developing intermetallic inert anodes for aluminum electrolysis. The anode alloy based on Al-Ti-Cu system was prepared by casting, followed by the application of a protective coating. Behaviour of corrosion and the passivation under anodic condition was characterized using the electrochemical and microscopic techniques. The results obtained clearly demonstrate that the oxide coating can provide good corrosion resistance via surface passivation of alloy anodes, rendering them inert in cryolite melt.

Jan 1, 2006

By Supachai Surapunt

The distribution behavior of V A minor elements (As, Sb and Bi) in the smelting stage of the Mitsubishi process were evaluated thermodynamically based on thermodynamic data and operating data. The fractional distributions between the gas, slag and matte phases considered as the degree of vapor saturation of 1.0 are as follows: 53.8, 27.2 and 19% for As, 23.6, 56.6 and 19.8% for Sb, and 91.3, 1.1 and 7.6% for Bi, respectively. Arsenic is mostly distributed to the gas and slag phases. It is effectively eliminated by volatilizing and slagging. Antimony is mainly in the slag phase, which is suitably removed by slagging. Bismuth is easily vaporized to gas phase. The degree of vapor saturation has a large effeet on the distribution behaviors of the three elements between the three phases. The amount of a minor element in the charge has an effect on the distribution of As but no effect on the distributions of Sb and Bi. Increasing matte grade and temperature results in the change of distributions for As and Sb, significantly. The change in the distribution ratio between slag and matte phases also considerably affects the distributions of As and Sb. The distribution behavior of Bi is not significantly changed by the change in matte grade, temperature and distribution ratio.

Jan 1, 2003

By Xiaodi Huang, Matthew Andriese, Zheng Zhang, Jiann-Yang Hwang, Zhiwei Peng

"A simplified finite-difference time-domain (FDTD) algorithm for modeling microwave propagation in magnetic dielectric materials was developed and employed to study the microwave dissipation in magnetite. Heat transfer during microwave heating of magnetite was subsequently investigated by solving heat transfer differential equation using explicit finite-difference (EFD) method. It is observed that temperature of magnetite surface increases rapidly in the first minute due to the rapid strength decays in both electric and magnetic fields within a short distance along the path of microwave dissipation. A temperature peak, initially formed at the surface of the sample slab, migrates inward as heating time extends and microwave power increases.IntroductionAs one of primary materials in iron and steel industry, magnetite exhibits excellent microwave absorption capability, which leads to great energy conservation in microwave assisted steelmaking [1,2]. The fast temperature increase in microwave heating of magnetite can be attributed to both dielectric and magnetic losses [2]. Although much experimental work has confirmed this observation, detailed computational studies for modeling of microwave field dissipation in magnetite at commonly used frequencies, such as 915 MHz, has not been well addressed [1,3].Finite-difference time-domain (FDTD) method is widely used in computational electrodynamics modeling to simulate the dynamics of electromagnetic wave scattering from various media [4,5]. This approach requires modeling algorithm to be formulated with integration of specific characteristics of each medium. An extensive literature survey indicates that current formulations are only suitable for modeling electromagnetic waves propagating in normal dielectric lossy materials [5,6]. Since magnetite is a magnetic dielectric material in which both dielectric and magnetic properties contribute to the heating process under microwave irradiation, a specific algorithm should be developed for the simulation."

Jan 1, 2012

By Xiaodi Huang, Matthew Andriese, Zheng Zhang, Jiann-Yang Hwang, Zhiwei Peng

"The thermal decomposition and regeneration behaviors of wüstite were investigated by in situ high temperature X-ray diffraction (HT-XRD) under non-isothermal condition at heating rate of 4 K min-1 in vacuum ranging from 294 K to 973 K. Wüstite on heating decomposes to magnetite and iron up to 823 K, above which it exhibits marked tendency to regenerate. Investigation of thermal stability of the reaction system shows that the decomposition proceeds under kinetic reaction control while the regeneration is under thermodynamic control. Kinetics study based on the Coats-Redfern integral approximation method indicates that the decomposition reaction follows a Komatsu-Uemura model-based diffusion-controlled kinetics with activation energy of 32.860 kJ mol-1. The thermodynamics analysis of regeneration reaction demonstrates that wüstite regenerates at lower temperature than stoichiometric ferrous oxide.IntroductionOwing to its importance in preparing various magnetic ceramic/metal nanocompostites or nanocrystals with high values of coercivity for the application as recording media, wüstite (non-stoichiometric ferrous oxide) has been attracting the attention of scientists over a long period [1-6]. The thermal behavior of wüstite was investigated by several researchers and phase transformations due to thermal decomposition and regeneration of wüstite during the heating in a specific temperature range was observed [7-9]. In spite of wüstite being found to dissociate to magnetite and iron at temperatures lower than 848 K and then regenerates at higher temperature, a clear understanding of the reaction mechanisms is clearly lacking [9]."

Jan 1, 2012

By M. D. Crites

As part of a multi-year program for assessing the viability of chrome-free refractories in copper smelting, converting and refining furnaces, dynamic corrosion tests have been conducted on a series of refractories from the magnesia-alumina system, using a ferrous silicate slag. The corrosion rates of the test refractories are compared with those of a reference mag-chrome brick, and recommendations are made for more in-depth evaluations of the more corrosion-resistant materials.

Jan 1, 1999

Accretions of dust on the walls of the offtakes from furnaces and in the waste heat boiler are a cause of significant operating and maintenance problems in non-ferrous smelters. The dust originates from entrained solids in the gas stream and vaporised species that condense during gas cooling. Control of dust formation is very important for minimising the formation of accretions and reducing the severity of environmental problems caused by toxic species, such as those containing arsenic, in the dust. The present paper discusses the formation of accretions and the condensation of dust in copper smelting from a thermodynamic viewpoint. Changes, in gas composition and the amounts and identities of the condensed species in the dust are calculated using computational thermodynamics. Interactions between dust species to form accretions are considered in the light of appropriate phase equilibria. The results show that the nature of the dust formed varies greatly, depending on the temperature and the amount of oxygen present during cooling. Control of the amount of oxygen is required if offtake and waste heat boiler accretion problems are to be minimised.

Jan 1, 2002

By Mohamad Omarei, S. M. Sadrameli

"The aim of this research work was to produce biodiesel (fatty acid methyl esters, FAME) from canola oil using KOH loaded on y-Al203 support as a heterogeneous catalyst. Different parameters such as effects of the molar ratio of methanol to oil, catalyst amount and reaction time on the yield were investigated. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used for characterization of the catalysts. A biodiesel yield of 86.67% was obtained under catalyst preparation and transesterification conditions of calcinations temperature of 773 K, 4 h of reaction time at 338 K, and using 3.5 wt% catalysts and molar ratio of methanol/oil of 15:1. The leaching of potassium species in the spent catalyst was observed.1. IntroductionBiodiesel is an eco-friendly and alternative energy source for diesel engines that can be synthesized by transesterfication of vegetable oil or animal fat with alcohols [1 ]. There are four principal approaches to the synthesis of biodiesel involving the transesterification of the triglycerides of the plant oils and animal fats: base catalysis [2], acid catalysis [3-5], employing supercritical alcohol conditions [6] and enzyme catalysis [7]. The commonly used homogeneous catalysts are NaOH, KOH and their alkoxides. Homogeneous alkali-catalyzed transesterification is much faster than acidcatalyzed transesterfication [8]. However, a large amount of water is required to transfer the catalysts from the organic phase to a water phase after the reaction. Therefore, it is considerably more costly to separate the catalyst from the produced solution [9]. These disadvantages could be removed by use of a heterogeneous catalyst [10]. The use of heterogeneous catalysts eliminates the neutralization step, hence it results much easier to separate from liquid products. Also, they can be designed to give a higher activity and selectivity and to have longer catalyst lifetimes [11]. A large number of different heterogeneous catalysts have been synthesized for biodiesel production. For example, calcined Mg-Al hydrotalcites [12], zeolite and metal catalysts [13], metal oxides such as calcium oxide (CaO) [14], magnesium oxide (MgO) [15], zirconium oxide (Zr02) [16], and supported catalysts [17] have been investigated as heterogeneous catalysts. CaO and MgO are most frequently used heterogeneous catalysts for biodiesel production [18]. In this present work, we aimed at developing an efficient catalyst for transesterification of canola oil. We have prepared KOH/ Al203 by impregnation and applied to determine the optimum conditions for biodiesel production. Three different variables including reaction time , alcohol to oil molar ratio and catalyst loading with may influence the quality of the produced biodiesel were optimized. Moreover, SEM (scan electron microscope), XRD (X-ray diffraction) and XRF were used for characterization of the catalysts."

Jan 1, 2012

By G. T. Lapidus, O. J. Solis-Marcial

"The oxidative dissolution of copper from refractory minerals, such as chalcopynte, represents a technological challenge that has occupied hydrometallurgists for more than half a century. Innumerable processes have been suggested, but the majority operates at high temperatures or employs corrosive media. The origin of this refractory nature is the formation of passivating phases of iron(III) or copper. One option is to add non-corrosive ligands that complex these metal ions, thereby facilitating their dissolution. In the present work, the effect of acetone in sulfuric acid solutions was studied. The initial experiments were on chalcopynte carbon paste electrodes using cyclic voltammetry, where greater reactivity was observed. Later, leaching tests with hydrogen peroxide, cupric sulfate and ozone and, as oxidants, were performed. High extractions were achieved in three hours at 50°C. The solid residues contained the iron in the form of Fe203 and FeOOH.IntroductionChalcopyrite is the most important mineral of polysulfide copper ores [1] and accounts for approximately 70% of the world's copper reserves [2]. Currently, the copper present in chalcopyrite is extracted mainly by pyrometallurgical processes, which generate environmental concerns because of the formation of SO2 gas and submicron particulates [3]. The development of a less aggressive hydrometallurgical process for the extraction of copper would constitute a possible solution to these problems. For that reason, studies of the dissolution behavior of chalcopyrite are of great technological importance [4], However, the proposed oxidative leaching routes for chalcopyrite, generally at high pressures and temperatures, have not been implemented on an industrial scale, because of the elevated costs required to equal the high copper extractions obtained in thermal processes. These extreme leaching conditions are required because of the refractory nature of chalcopyrite. Passivation has been used to explain this phenomenon, although researchers have disagreed on the composition of the layer, which is various have assumed to be sulfur, copper sulfides, and iron-bearing jarosites or hydroxides [5]. If the latter compounds are the cause, an alternative solution would be the use of polar organic solvents in the oxidative leach to decrease the formation of the passivating iron layer. In this work, the influence of acetone on the oxidative leaching of a chalcopyrite concentrate at room conditions is explored."

Jan 1, 2012

By Peter Kong

This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free radicals and excited state atoms. Thus, both thermal and nonthermal atmospheric-pressure plasmas are finding applications in a wide variety of industrial processes, e.g. waste destruction, material recovery, extractive metallurgy, powder synthesis, and energy conversion. A brief discussion of recent plasma technology research and development activities at the Idaho National Laboratory is included.

Jan 1, 2006

By R. Cheng

The kinetics of the solvent extraction of ythium from HCl solution with mono-2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester (HEHEHP) have been studied using a rotating diffusion cell (RDC). The effects of rotation speed, pH, ymium and extractant concentrations and temperature on the rate of extraction were examined. The rate of extraction of ythium appears to be controlled by an interfacial reaction of metal ion and extractant. The concentration of the latter is determined mainly by diffusion through the membrane. The contributions of the rates of diffusion in the diffusion layer, diffusion in the membrane and chemical reaction at the interface to the overall rate have been calculated on the basis of a kinetic model.

Jan 1, 1992