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By Alberto Oalvez, Lucya Yunus, Pengfii Tan

"Laboratory flotation tests of slow cooled converter slag have showed that 92.5% copper recovery at the copper cut-off grade of 24 - 25 % can be achieved by using a 50:50 ratio of DSP330 and SIBX (sodium isobutyl xanthate) at the natural pH of 7 and with a grinding time of 18.5 minutes. 70ìéç is the P80 achieved at this grinding time. MIBC is the frother and the solid content of the flotation feed was 46%. In the plant trials, two types of collectors at two different feed particle sizes for both the normal and slow cooled slag were operated. The particle size was controlled by the feed rate. The P80 of 75 ìçé at a feed rate between 32 - 36 t/h were tested. The plant trials have demonstrated that the copper recovery in the milling and flotation process of the slow cooled slags was improved by 3%. IntroductionIt is proposed to float the slow cooled converter slag, in the auxiliary circuit of the copper concentrator at Mount Isa, by using the processing conditions identified from several laboratory flotation tests. Among these laboratory tests, one produced a copper recovery of 4 % higher than those achieved from a normal cooled slag with the same slag feed grade and the same copper content (24 - 26 %) in the concentrate. These test conditions were selected for further studies.Laboratory Test Work and Plant TrialsThere has been a lot of work conducted under laboratory and plant conditions [1]. However, the achieved results did not justify their total implementation in the Mount Isa Copper Concentrator. Initially, the lab trials were carried out with slag cooled 100% in air; then it was changed to combined cooling for 12 h with air and 2.5 days with water sprays. The reason for this change was the shortage of space when the slag was cooled 100% in air, as it takes several days to achieve safe temperatures for its removal. The San Manuel Copper Smelter has reported that their slag was left for air cooling in pits for 8 h and then was followed by water cooling for 2-3 days [2]"

Jan 1, 2012

By Fabio J. Esper, Guillermo R. Martín-Cortés, Francisco R. Valenzuela-Díaz, Cassio P. Carvalho, Giorgio Grotti, Reginaldo B. Santos

"Rejected sands from smelting metallurgical process because contain lead and others heavy metals are a problem to dispose as waste in all the countries. A procedure that is being proposed for it is to incorporate it on common clay bodies in the fabrication of structural ceramic products as bricks, blocks and roof tiles. The main goal of this paper is to present the results obtained with mixtures of sands from smelting metallurgical process with common clay from Jundiaí, São Paulo, Brazil. Preliminary incorporation tests (1,0% in weight) were made with hand formed spherical samples. With the higher compression strength of the spheres after drying and firing (950ºC) experiments on bricks production were made for quality technological test. Seven hundred hallow blocks containing 1,0% waste were produced and presented ceramic properties similar to those without sand incorporation. Introduction In last the fifteen years the LMPSol - Raw Materials & Non-metallic Solids Laboratory – Metallurgic Eng. & Materials Depto. – Polytechnic School - University of São Paulo comes studying the possibilities of incorporate industrials waste materials to the production of bricks and other products of construction aiming at to remove pollution products of the environments and to user the properties of the same ones in the structural ceramics products. Examples are the study of the influence of rejected steel furnace dusts in structural ceramic [1], another example is the main subject of the present paper: use of rejected sand from smelting metallurgical process in the production of bricks an other products of structural ceramics. Antecedents More or less one year ago, specialist and members from the direction board of METALÚRGICA GROFE LTD. Company contacted researchers and professors of the LMPSol – PMT – EPUSP seeking for a solution to their concern with the disposal of rejected sand from smelting metallurgical process."

Jan 1, 2008

By Fumitaka Tsukihashi

Phase diagrams of the CaO-SiO2-FeOx-MgO, Al2O3 systems arc necessary for the analysis of copper smelting reactions and sintering process of iron ore. The effect of MgO and Al2O3 addition on the liquidus of the phase diagram of the CaO-SiO2-FeOx system at low oxygen partial pressure was observed. The liquid phase area changed bi the addition of MgO and Al2O3 with a changing oxygen partial pressure from 10-8 to 10-3 atm (10-3 to 10 2 Pal at 1573K. The effect of Fe3+ / Fe2+ ratio on the melting mechanism is discussed.

Jan 1, 2003

By V. Ramachandran

Under the Resource Conservation and Recovery ACT (RCRA), generators of listed or characteristic hazardous wastes must find satisfactory means for disposal. of wastes. Initially, for many this meant landfills and deep-well injection. Until recently, mining and metallurgical by-products have largely been exempt from RCRA, but now are coming under its jurisdiction. With the increasing closures of landfills, companies in the U.S. such as electroplaters, miners, metallurgical plants and others are turning to recycling as an alternative to treat their wastes. While the cost of recycling has been challenging, the long-term economics prove attractive because recycling interrupts the cradle- to-grave responsibility for the waste generator. The present paper describes the recycling of hazardous wastes at ENCYCLE/TEXAS. Encycle extracts marketable metals from metal-bearing sludges and wastewater using hydrometallurgical processes borrowed from the mining and metallurgical industry.

Jan 1, 1994

By Tadafumi Adschiri

"Supercritical water can provide an unique reaction atmosphere for synthesizing metal oxide nanoparticles. Due to the drastic change of properties of water around the critical point, including density, dielectric constant and ionic product, the reaction phase with O 2 or H2 gas and the reaction rate and equilibrium can be varied to synthesize new materials or define particle morphologies. In this work, hydrothermal crystallization experiments are performed with several types of flow apparatus that allow convenient manipulation of variables such as temperature, pressure, and residence time. Key features in the flow modes and material preparation are discussed. The proposed supercritical hydrothermal synthesis method has the following desirable features: i) nanoparticles can be produced, ii) morphology of the produced particles can be controlled with small changes in pressure or temperature, and iii) a reducing or oxidizing atmosphere can be applied by introducing oxygen or hydrogen or other gases. An overview of this method is given for functional material synthesis of significant industrial interest including barium hexaferrite magnetic particles, YAO/Tb phosphor fine particles and lithium cobalt fine crystals.IntroductionHydrothermal crystallization, a method of metal oxide formation from metal salt solutions, is typically used at temperatures ranging from 373 K to 473 K. We are developing a new process for hydrothermal crystallizations that uses temperatures in the range of 673 K to 723 K, which is just above the critical temperature of water1 • 8 • In this work, we refer to this process as supercritical hydrothermal synthesis. The supercritical state of water allows one to vary reaction rate and reaction equilibrium by shifting the dielectric constant and solvent density with pressure and temperature. From of our research on material production in supercritical water, we have identified the following specific features of the supercritical hydrothermal synthesis method: (i) ultrafine particles can be produced, (ii) morphology of the produced particles can be controlled to some extent with pressure and/or temperature, and (iii) a homogeneous reducing or oxidizing atmospheres can be provided by introducing gases, such as O 2, H2, H2O 2• and so on.1"

Jan 1, 2000

By C. F. Feng, L. Froyen

"In-situ processes have emerged as new and promising techniques for metal matrix composite fabrication. They offer significant technical and economic advantages over conventional processing. One of the in-situ processing routes that have been used is reactive free sintering of a mixture of powder reactants. However, materials synthesised via this route are always porous because of density differences between reactants and products. An example are the porous Al/(TiB2+Ah03) MMCs obtained by heating powder mixtures of Al+ Ti02+B with Ti02 and B in stoichiometric ratios for forming TiB2• In this study, porous Al/(TiB2+Ah03) composites were further processed by hot-pressing at temperatures above 600°C. This processing cycle was designed so that the composites could be densified. Furthermore, the reaction kinetics of the in-situ processing are studied by means of DSC analysis measured at different heating rates. The activation energies of the three intermediate steps that are involved in the reactive processing for preparing AV(TiB2+Alz03) MMCs are determined to be 923 kJ/mole, 241 kJ/mole and 235 kJ/mole respectively.XRD proved that the hot-pressed products consist of Al, TiB2 and Al203- Properties of the products are assessed by microstructural characterisation (LOM, SEM and EDS), microhardness, Young's modulus and bending tests. The results show that good microstructures, elastic properties and strengths, as well as acceptable ductilities were achieved. For the composition 79.74wt% Al-15.95wt% Ti0z-4.31wt% B, after the reactive free-sintering and hot-pressing cycles, Young's modulus is 105 GPa, bending strength is 509 MPa and maximum strain is 5.0%; for composition 88.73wt% Al-8.87wt% Ti0z-2.40wt% B, they are 89 GPa, 311 MPa and 8.2% respectively. It can be seen that the properties of products can be tailored by adjusting the relative amounts of reactants in green samples. Furthermore, for comparison reasons, Al and a binary system Al-Ti02 were identically processed as the ternary systems. Their microstructures and properties were studied."

Jan 1, 1998

By A. Buzaianu, P. Motoiu, G. Popescu, C. A. Popescu, I. Rusu, A. F. Olteanu

"In recent years, the recycling magnesium metallurgy has developed new types of alloys, some of which exhibiting special electrochemical characteristics. Their application has found a fertile field in the energy conversion technologies. The paper introduces some technologic data on the recycling of aeronautical parts and scrap materials generated from the disassembling of magnesium alloy components, attempting to also solve the recycling of magnesium painted parts. The approach is meant to establish a superior quality method for recycling discarded parts or the excess of re-melting material in order to reduce environmental impact and costs. Magnesium-base alloys used as anodic materials are characterized by a high uniformity of the structural properties as well as by superior electrochemical performances, as compared to the ""classically"" used materials: Zn, Pb, etc. In nonconventional applications of magnesium alloys used as sacrificial anodes working in seawater, special alloying elements contribute to improving anodic processes. The influence of these alloying elements on magnesium sacrificial anodes was studied. It was found that the use of recycled materials in anode manufacture could reduce the Mg alloy cost by as much as up to 75% of the cost for virgin material, including the costs for the entire sequence of collection and transportation from a molding factory to a refinery, re-melting and composition adjustment.1. IntroductionMagnesium alloys are valuable materials because they exhibit low density, good forming and machining qualities, particular electrochemical properties and have a high recycling potential. There exists a false idea about the high costs of the use of magnesium alloys, partly justified by the lack of secondary materials suppliers and the insufficient knowhow in the diverse user industries to provide for an efficient substitution of conventional magnesium alloys for multipurpose applications. These circumstances have lately spurred the magnesium industry to develop new alloys and coatings and to improve processing techniques [1]. As a result, magnesium supply has greatly expanded and so have the research and development efforts to achieve complete recycling of Mg alloys.In consumer markets, magnesium is frequently selected because it helps reduce enery consumption. For example, an equal volume part made of magnesium is 23% the weight of a steel part and 64% the weight of an aluminium part."

Jan 1, 2008

By A. J. Maselli, E. C. Cemak

Hartford Steel Technologies (HST) has a pyrometallurgical and hydrometaliurgical process capable of reclaiming valuable metals from a hazardous waste· stream such as EAF Dust. The HST Process effectively addresses the growing environmental concerns surrounding the increasing production of EAF Dust without producing any hazardous waste material as byproducts. Currently EAF Dust production levels are exceeding the 1,000,000 metric tons per year mark. The HST Process is designed to separate iron, zinc, lead, cadmium, copper, and silver metals using a two-phased process. The Pyrometallurgical side of the Process utilizes a Rotary Hearth Furnace to separate the iron metal from the remaining metals. These remaining metals are further separated, using a Hydrometallurgical Process, in a series of digestion tanks. The individual metals are then collected in saleable form.

Jan 1, 2000

By Jianhang Hu, Li Yang, Yonggang Wei, Kongzhai Li

"In this paper, the pyrolysis of biomasses including bamboo, sawdust and walnut shell were performed in a tube furnace under temperatures between 400? and 600? to obtain biomass carbon, gas, and tar. Textural parameters analysis revealed the caloric value of biomass carbons between 32 MJ/kg and 34 MJ/kg. It also indicated that the surface of biomass carbon consists of mesopore and macropore structures. By using GC analysis, it was determined the main ingredients of pyrolysis gas are CO, H2, CO2, CH4, C2H4 and C2H6. Calculation states that the density of pyrolysis gas is roughly between 1.0 kg/m3 and 1.7 kg/m3, while the calorific value of pyrolysis gas is between 12000 kJ/m3 and 16500 kJ/m3, illustrating that pyrolysis gas is a median gas. The calorific value of biomass tar was found to be between 32 MJ/kg and 34 MJ/kg, with more than 80 compounds in the biomass tar identified by GC-MS method.IntroductionBiomass as a renewable source is the world's largest and most sustainable energy resource [1].The conversion of biomass has the potential to be a renewable and carbon neutral method of producing fuels and chemicals [2-4]. Pyrolysis is a thermo-chemical process defined as applying heat to degrade biomass in an inert atmosphere. It transforms unstable biomass and other organic materials into biomass carbon, gas, and tar [5]. Biomass carbon can be stored or transported much easier as compared to parent biomass or be converted to value added products such as activated carbons[6]; gas is a relatively low-energy-density fuel; tar can be considered as a source of useful chemicals[7].The characterization of biomass pyrolysis will lead to its increased understanding and utilization as a source of solid, liquid and gaseous products which can be used as fuels and petrochemical feedstock[8,9].In recent years, many researchers studied the effect of temperature on biomass pyrolysis product distribution characteristics in a variety of pyrolysis reactor[10]. Ramin Azargohar's paper [11] presents the results of characterization for biomass and investigates the effects of pyrolysis temperature on the pyrolysis products obtained by fast pyrolysis of four different types of biomass."

Jan 1, 2014

By Salustio s. Guzman

The standard .free energies of formation of tin chlorides were estimated with reviewed and estimated basic thermodynamic data, and measured reversible potentials for the disproportionation of tin dichloride into metallic tin and tin tetrachloride. Values for cºp, Sº, Hº?-Hº 298, -(Gº - Hº298) /T,.Hºf, Gºf, and log Kp are given in tabular form, these estimations are compared with estimations reported in the literature.

Jan 1, 1985

By Fumitaka Tsukihashi

Increasing amounts of steel scrap are being used as resources for steelmaking. Therefore, there has been a growing interest in the removal of harmful tramp elements such as antimony, zinc, tin, arsenic, bismuth, lead and copper from the molten steel. The problem that should be solved is the economic removal treatment of residual tramp elements in the steelmaking processes and the production of high quality steel by reducing the effect of the contaminated tramp elements and satisfying the environmental regulations. In this paper, the available thermodynamic data of the residual tramp elements in the molten steel arc summarized and the possibility of the removal of residual tramp elements from the molten steel is thermodynamically estimated.

Jan 1, 2003

By Anupam Madhukar

The essence of an atomistic unified kinetic model of strained thin film growth and defect initiation is presented along with a comparison of its consequences obtained from computer simulations with experiments. Within the competing kinetics of a strain dependent activated incorporation of atoms and an asymmetry between upwards and downwards inter-layer migration, the model provides a consistent description of 2D versus 3D morphology evolution accompanied by the appearance of surface vacancies and steps at no energy cost. The correlated migration of these precursor defects offers an atomistic mechanism for the emergence of surface half-loops from the growth front (thus accounting for configurational and thermal entropy) governed by activation energies closer to their correlated motion under the evolving strain fields and thus substantially less than those calculated with respect to the perfect crystal as the reference state. The essential mechano-chemical nature of the problem is compared and contrasted with the historical literature of such phenomenon as precipitation hardening and sintering in metallic and ceramic composites.

Jan 1, 1994

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 Chengyi Ding, Xuewei Lv, Senwei Xuan, Jie Qiu, Yun Chen, Kai Tang

The influence of SiO2 on the reducibility of the CaO–Fe2O3–SiO2 system was fully examined in this study. The isothermal reduction kinetics of CF and CF8S (CaO/Fe2O3 = 1:1, wt% (SiO2) = 8) were investigated through thermogravimetric analysis at 1123, 1173, and 1223 K with 30% CO and 70% N2 gas mixtures. The reduction of the samples with 8% SiO2 was not only highly accelerated but also proceeded easily. Rate analysis revealed that CF and CF8S reduction occurs in two stages, the Fe3O4-to-FeO stage overlaps with the previous Fe2O3-to-Fe3O4 stage and tends to approach the following FeO-to-Fe stage with the addition of SiO2. The apparent activation energy values of CF and CF8S reduction are 46.89 and 8.71 kJ mol−1. Sharp analysis indicated that CF and CF8S reduction was expressed by the Avrami–Erofeev equation presenting a 2D shrinking layer reaction.

Mar 1, 2017

By Dong Joon Min, Joo Hyun Park, Mi Sun Choi, Jae Hong Shin

Sublimation of ZrCl4 is important for the production of nuclear grade metallic Zr in Kroll’s process. The sublimation kinetics of ZrCl4 was investigated by TGA under both isothermal and non-isothermal conditions. The sublimation rate of ZrCl4 increased with increasing temperature under isothermal conditions. ZrCl4 sublimation was confirmed to be a zero-order process under isothermal conditions, whereas it was first-order kinetics under non-isothermal conditions. The activation energy of ZrCl4 sublimation under isothermal conditions was 21.7 kJ/mol. The activation energy for non-isothermal sublimation was 101.4 kJ/mol and 108.1 kJ/mol with the Kissinger method and Flynn- Wall-Ozawa method, respectively. These non-isothermal activation energies were very close to the heat of sublimation (103.3 kJ/mol). Sublimation occurs by two elementary steps: surface reaction and desorption. Therefore, the overall activation energy of ZrCl4 sublimation is 104.8(±3.4) kJ/mol. The activation energy of the surface reaction and desorption steps are proposed to be 83.1 kJ/mol and 21.7 kJ/mol, respectively.

Jan 1, 2014

By Onuralp Yiicel, Ozlem Okur, Murat Alkan

"In this study, Co-Cr-Mo alloys were produced using a mixture of Co304, Cr203 and Mo03 powders with Al powders by a Self-propagating high temperature synthesis process. SHS is a process of material synthesis that has revealed a number of reactants combinations capable of much higher energy release than conventional explosives. Al203 is added to the mixture to decrease the adiabatic temperature of the system. The thermodynamic simulations and the calculations of adiabatic temperature were examined with FactSage 6.2. In the SHS experiments, different Co304/ Cr203/Mo03 ratios were examined, and their effects on the metal recovery and alloy compositions were carried out. The samples were characterized by using chemical analysis, XRD, XRF and SEM/EDS techniques.IntroductionSelf Propagating High Temperature Synthesis (SHS) has significant advantages compared to the high technology furnace applications, such as very short processing time, simple operation, low energy requirement and low cost [l, 2]. In a SHS process, the ignition starts the combustion and propagates throughout the reactant mixture yielding the desired product. However, the disadvantages of the process such as inhomogeneous or unreacted products due to undesirable reaction rates needs to be overcome by changing some parameters such as ignition temperature, particle size, additive, atmosphere etc. [3, 4]. This work aims to establish a scientific and engineering background in the production of some cast Co-Cr-Mo master alloys via SHS (Self Propagating High Temperature Synthesis) metallurgy which is attractive process technique regarding fast and low-cost production ability of cast alloys."

Jan 1, 2013

By Xiao Hong, Zhang Wenqiang, Gao Bing

The characteristics of top charging coke (coke 1) and stamp charging coke (coke2) were investigated. The weight loss ratios of two kinds of cokes with and without alkalis were measured after reacting with CO under the temperature of 2 900, 1000, 1100 and 1200 °C respectively. The microstructures of original cokes were observed by SEM. The experiment results show that, with no addition of alkali, the weight loss ratios of coke 1 and coke 2 were nearly the same under the temperature of 900 and 1000 °C. While the weight loss ratio of coke 2 was much larger than coke 1 under the temperature of 1200 °C. With alkali-rich, the weight loss ratio of the two cokes was almost the same at 1100–1200 °C.

Mar 1, 2017

By Tuomas Hirsi

The world’s first large scale modular solvent extraction plants have been delivered by Outotec. The first of these is now in operation and has proven that the VSF®X technology can deliver the excellent performance of the Outotec VSF® solvent extraction process. Modular delivery allows site work to be minimized and the manufacturing done in a controlled environment, allowing for serial production manufacturing benefits. Container based delivery was found to be a highly efficient way of utilizing the standardized transportation methods on a global scale. Site work with modular units was found to be efficient and highly predictable. In this paper, we present the first successful Outotec VSF®X deliveries and discuss the benefits of the modular delivery and design compared to the standard solvent extraction installation’s delivery. The process performance of the VSF®X is also discussed with experiences from the first industrial reference presented.

By Wang Yun-yan

In order to examine the adaptability and the kinetics of leaching different gold ores in alkaline thiourea system, six kinds of gold concentrate and/or calcine with different physical and chemical properties were chosen as objects. The leaching behaviors in alkaline thiourea system with high stability, acidic thiourea system and alkaline cyanide system were compared. Changes of phase, surface appearance, particle distribution and specific surface area of six kinds of gold ores before and after leaching were studied in virtue of modern analytic techniques, e.g., XRD, SEM, and so on. The results indicate that alkaline thiourea solution can be used to leach gold ore, for oxidized gold concentrate removed arsenic by microbe pretreatment(4#) the leaching rate of gold is up to 82.68%, such conclusion overthrows the parlance reported that pH value must be less than 1.78, or gold can not dissolve in thiourea solution. Chemical components and phase are related to gold leaching rate, different gold ores are fit for different leaching system, and alkaline thiourea solution is suitable for the pretreated oxidized gold ores with low content of sulfur and in which the main phase was SiO2, phase almost does not change after leaching basically. Generally speaking, when leaching in alkaline thiourea solution, surfaces of gold ores with glaze change greatly to ones with coarseness, distinct trace and holes of corrosion. Particle size decrease and specific surface area increase of gold ores after leaching in alkaline thiourea solution with high stability except gold concentrate of Zhongyuan gold smelter(5#).

Jan 1, 2006

By V. I. Lakshmanan

Crown ethers are gaining importance in separation technology specifically for rare earth elements (REE, La to Lu plus Y) and precious metals (Au, Ag, Pt, Pd, Rh and Ir) due to their specific binding ability, metal complex stability and high extraction efficiency. The selectivity of crown ethers in extraction of these metals depends on different factors, including the cavity diameter and nature of a donor atom of the crown ether, size and charge of the metal ion, diluents and counter ion. Demand for strategic REE and precious metals are consistently increasing in the world while the separation of these metals is most challenging tasks. In this paper, the use of crown ethers in separation of REE and precious metals, reaction mechanisms and simplified process flowsheets will be elucidated. New reagents with high selectivity for the separation of these metals are further expected to produce high purity metals.