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By Hojat Naderi

In this research assisted leaching of chalcopyrite using sodium peroxodisulfate was studied. Electrochemical techniques such as Tafel analysis and electrochemical impedance spectroscopy (EIS) were used to investigate the surface reactions of a chalcopyrite electrode in the presence and absence of Na2S2O8. According to the results, addition of sodium peroxodisulfate increases the current exchange of the corrosion process and prevents the formation of a passive layer on the surface of the electrode. EIS tests show the trans-passive dissolution of the passive layer on the chalcopyrite electrode in presence of Na2S2O8. Equivalent electrochemical circuits were modeled for Na2S2O8-free and -containing solutions and the model parameters were compared to determine the effect of S2O8 2− on chalcopyrite dissolution. Copper dissolution from pure chalcopyrite mineral and chalcopyrite concentrate was carried out using 15 g/L sulfuric acid solution with and without Na2S2O8. Simultaneous presence of 10 g/L ferric ion and 40 g/L peroxodisulfate salt results in about 40 and 18% of Cu extraction from chalcopyrite concentrate and pure chalcopyrite mineral, after 96 h, respectively.

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 H. Yin, T. Emi

"Advantages of gas/flux injection technology as materialized in the main stay unit processes for steelmaking are depicted covering hot metal pretreatment through secondary refining. Current status of micro-kinetic issues involved in the injection technology are reviewed including gas-in- metal, gas-in-slag, flux-in-metal, metal-in-flux and three-phase dispersion systems with reference to macro-kinetics. Key problems are briefly addressed to further develop injection technology for steelmaking processes.1. FROM PAST TO PRESENTApplication of gas injection to steel industry started in early 1950's when inert gas bubbling via stopper rod, lance, or porous refractory plug was practiced to make the temperature of steel melt in ladle uniform The gas bubbling in ladle was then extended to slightly removing hydrogen ti'om the steel melt tapped from Electric Arc Furnace (EAF) and Basic Open Hearth Furnace (BOH) when vacuum processing facilities were not popular. Later, oxygen gas injection via calorized steel pipe into molten steel bath in BOH Furnace was also put into operation to promote the decarburization to increase the productivity of the process. This line of development has been made in parallel with more profound processes, i.e, top blowing Basic Oxygen Furnace (BOF) for primary steelmaking and side blowing Argon Oxygen Oecarburization (AOD) vessel for decarburizing stainless steels.On the other hand, injection of fluxes into steel bath was first industrialized in Germany in 1960's, Primary objective was to desulfurize steel melt in ladle by injecting CaC2 or CaCrCaO mixture via lance under neutral slag cover with good success. Difficulties in injecting fluxes without clogging and rippling at a desired flux/gas ratio, and durability of injection lance were resolved in due time to bring forth many injection facilities to flourish for versatile refining operation. Top injection of fluxes from main oxygen lance to BOF was also industrialized as LDAC to promote early slag formation. A new process then emerged which injects oxygen gas and fluxes together through concentric annular tuyere, installed at the bottom of the BOE into steel melt. This process, developed in Germany [Oxygen Bottom Maxhutte (OBM)] and brought into maturity in USA (Q-BOP) and Japan in a large scale operation, became the predecessor of the combined blowing (top and bottom blown) BOF which dominates modern steelmaking."

Jan 1, 1996

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 A. F. Kaczmarek

Cerro Negro is an undeveloped ore body located at the Cerro Verde mine near Arequipa, Peru. The mineable reserve contains 70 Mt of oxide ore grading 0.532% copper. Mineralization is hosted in three distinct rock types: tourmaline breccia, crackle breccia and granodiorite. Rock type effects copper recovery and acid consumption. The paper describes Cyprus' testwork philosophy and the resulting four-phase metallurgical program used to define the commercial leaching parameters. Copper recovery and acid consumption were monitored as functions of crush size, heap height, irrigation rate and acidulation conditions. Single lift, on-off and permanent multi-lift heaps were considered. Leach cycle times were based on incremental copper extraction and acid consumption rates, with added constraints imposed by operational requirements. The optimum leach system involves an on-off pad using tertiary crushed ore acidulated with 20 kg/t acid and stacked to a height of 6.5 m. The active leach cycle is 82 days at an irrigation rate of 0.26 l/min/m2. Under these conditions copper recovery is expected to average 81% over the life of the mine.

Jan 1, 1999

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 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.

By James Vaughan

Australia is a major miner of ore that requires hydrometallurgical processing. According to the 2016 US Geological Survey Minerals Commodities Summaries, the country is 1st for aluminium (bauxite) and lithium, 2nd for gold, zinc and cobalt, 4th for nickel and silver, and 6th for copper mining, not to mention its wealth in coal and iron ore. In this paper, examples of recent Australian hydrometallurgical activities are summarised. Then, selected research projects from the University of Queensland hydrometallurgy research group are profiled. The projects profiled are related to fundamental aspects of processing bauxite with organics and reactive silica as well as the development of a synergistic hydro- and pyrometallurgical process for copper. The process context and motivation for the research is introduced, key results are highlighted with the associated relevant references.

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 Lloyd Robert Nelson

The historical progression in installed electric furnace smelting capacity of some 1650 calcium, chromium, manganese, nickel and silicon ferro-alloys furnaces is reviewed. Key increases in the inherent installed electrical capacity, often achieved through uprating furnaces, are identified. Possible factors facilitating such advances are explored, including: specific process engineering and pyrometallurgical enhancements (e.g., improved control over the consistency, size and chemical form of raw materials, extents of preheating and pre-reduction delivered into the furnace; and patterns of feed distribution); furnace electrical configuration (AC or DC; immersed, submerged-, shielded- or open-arc); form of electrode (graphite, self-baking or composite); furnace configuration (circular or rectangular; closed or open and 1-, 3- or 6- electrodes); better engineering and equipment designs (e.g., high-intensity cooling) and state of furnace electrical and metallurgical control systems. A view is presented on the prevailing state of evolution of the Mega-scale in ferro-alloy smelting and opportunities for still further improvements.

Jan 1, 2014

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 M. Brian Maple

A rich variety of phenomena are produced by superconducting-magnetic interactions in rare earth and actinide compounds. These phenomena, and the materials in. which they have been observed, are described in this talk, with an emphasis on the new high superconducting transition temperature (Tc) copper oxides. The Materials The-materials in which these phenomena occur can' be divided into two classes. In the first group, there are two distinct interpenetrating systems of electrons, a set of localized 4f or 5f electrons and a set of itinerant electrons. The localized f electrons carry magnetic moments and interact with the spins and momenta of the the itinerant electrons, which are involved in the superconductivity, via exchange and electromagnetic interactions; respectively. This category includes materials containing rare earth (R) and actinide elements with partially-filled f electron shells which have been inroduced as substitutional impurities [e.g., La1-xCexA12, Th1-xUx] or form a sublattice in compounds [e.g., RRh4B4, RMo6S8, RMo6Se8, the high Tc. superconductors RBa2Cu3O7-d(d - 0.05)]. Materials of the second type are characterized by a single band of electrons that is responsible for both superconductivity and magnetic order. This group includes heavy electron rare earth and actinide compounds [e.g., CeCu2Si2, UBe13, UPt3, URu2Si2], and the high Tc copper oxide superconductors such as the hole-doped systems Lag- MxCuO4 (M = Ca, Sr, Ba, Na) and RBa2Cu3O7-d(0 =d= 1) and the electron-dope system Ln2-xMxCuO4-y (Ln = Pr, Nd, Sm, Eu; M = Ce, Th; x = 0.15; y - 0.02).

Jan 1, 1992

By Robert L. Stephens

"It can be argued that one of the most important property of any material is cost, since this property detennines the applications for which a material can be considered. Despite growing demand and production for commodity metals such as copper, nickel, zinc, lead, and tin, the cost of these metals has been steadily decreasing in real terms. The only way that metal miners and producers can remain financially viable in the long term is by continuing to lower their cost curve through the implementation of new metals production technologies. This paper reviews technological developments in the production of copper, nickel, zinc, lead, and tin that have or threaten to redefine the cost curves for these metals.DisclaimerThe opinions expressed in this paper the author's, and are not necessarily those held by the author's employer, Cominco Ltd.IntroductionThis meeting will discuss many novel technologies and processes for producing metals and materials with specific properties that will enhance the applications ranges for the material or will allow entirely new applications to be developed. However, in every real-world case, the cost of the new material or process is an important property that determines which applications the material or process can be used in. Other properties that are important depend on the applications.A recent press report (1) discussing the potential replacement of aluminum radiators with copper radiators in pickup trucks and sport utility vehicles provides an interesting example to reinforce the importance of cost in materials selection. In this case, the displacement of aluminum by copper is being considered because of the more favorable heat dissipation characteristics of copper. Heat dissipation has become more important due to the development of hotter-burning V-8 and V-6 engines. For this application, engineers also consider cost, weight, size, durability, and manufacturing process. The report stated that the development by the International Copper Association (ICA) of the ""CuproBraze"" manufacturing process for heat transfer products was an important development. This technology produces 845 radiators that weigh less, are more uniform in quality, and are potentially more compact. They are also expected to cost less in high production quantities than copper units produced in the past, last three to four times longer than soldered copper radiators, and the process also eliminates the use of lead solder from the manufacturing process."

Jan 1, 2000

By Fathi Habashi

In the past five years Cuba has been attempting to more than double its nickel production by constructing two new ammonia leaching plants. No metals are yet produced on commercial scale but a variety of oxides and sulfides. This report updates the Cuban nickel industry as a result of two visits : one at the invitation of the Cuban Ministry of Basic Industries in 1987 and the other as a consultant to the United Nations for the Cuban Laterite Project in 1989.

Jan 1, 1993

By Wei Liu

A new process for extracting cadmium from the electric precipitated dust produced by ISP process was studied. A leaching rate of 89.1% of cadmium was attained by leaching the dust with NH3?H2O-(NH4)2SO4 system under the best leaching conditions: ratio of liquid to solid(l:s)=2.5, c(NH3):c(NH4+)=3:5, total concentration of ammonium and ammonia=8 mol?L-1, leaching time= 1.5h, temperature=35. The most troublesome impurity of lead could be deposited from the leached out solution automatically after put it static more than 15h when the total concentration of zinc and cadmium was up to 45gL-1 , and the final concentration of lead was 0.0047 gL-1, which meant 99% of it was removed. Metallic cadmium which contained cadmium more than 99% was prepared by electrowinning under the conditions: current density=750Am-2, total concentration of Cd2+ and Zn2+>25gL-1. The current efficiency was about 87% and the energy consumption for every ton of cadmium was about 548KWht-1. Main impurities of the metallic cadmium were copper and zinc and all of they could be got rid of in the following pyrometallurgical refining step.

Jan 1, 2006

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 Honggang Zhong, Xin Cao, Qijie Zhai, Hongmei Song, Congsen Wu, Cheng Zhang, Jingzheng Ye

"The influence of superheat on the solidification structure and ferrite/austenite phase transformation of a novel lean duplex stainless steel (DSS) was investigated on a setup, which designed to thermally simulate the continuous casting process. The results showed that the macrostructure of the samples all exhibited chill zone, columnar zone and equiaxed zone. The distance from chill zone to position of columnar to equiaxed transition (CET) moved from 51.0 mm to 39.8 mm with an decrease of superheat from 70 °C to 10 °C, and that the grains in the chill zone tended to be finer. In equiaxed zone, the fme and uniform grains were observed when superheat higher than 40 °C; while, coarse grains were found in samples poured at low superheat. Generally, the volume fraction of ferrite increased along the dendritic growth direction, and stabilized in equiaxed zone. The high superheat decreased the volume fraction of ferrite in equiaxed zone, while it had indistinctive influence on chill zone and columnar zone.IntroductionDuplex stainless steel with approximately equal volume of ferrite and austenite, offering an attractive combination of corrosion resistance and mechanical properties. [ l]. The production of DSS, worldwide application in structural engineering[2] and petrochemical industry[3], have increase by more than 100% in the latest decade[4]. But due to the sharp prices increase of nickel and chromium, lean duplex stainless steels which have lower contents of alloy elements were developed. They perform well in both mechanical and corrosion resistance[S, 6] and even have TRlP(Transformation Induced Plasticity) effect[?]. Nonetheless , the mechanical properties of DSS was affected greatly by the solidification structure, such as columnar to equiaxed transition (CET), grain size and phase content[8]. So, the solidification behavior of stainless steel was investigated widely"

Jan 1, 2014

By Fumito Tanaka

The Mitsubishi process is the sole pyrometallurgical process for the continuous production of blister copper from copper concentrates and has been successfully operated around the world. The development of calcium ferrite slag (CaO-FeOx-Cu20), the so-called "C-slag", has enabled continuous converting from matte to blister copper in the commercial scale operations. Commercial interests in the slag led to many papers over the CaO-FeOx slag. However, CU2O- bearing slag has not been studied well due to experimental difficulties. The authors have quantified the thermodynamic properties ofthe CaO-FeOx-Cu2O system. The results have been utilized to analyze various issues related to the converting furnace, such as the magnetite precipitation from the slag or from blister copper and to develop better controlling criteria for the continuous converting operation.

Jan 1, 2003

By Victor Zavodinsky, Sergey Rogov

"Pseudo-potential fully relaxed total energy calculations are used to predict a hypothetical Si1-xCxO2 (x<0.5) compound formed from SiO2 ß -cristobalite by substitution of some SiO2 complexes by CO2 molecules. The simulation shows that the Si1-xCxO2 compound can be quasi stable if the CO2 content is less than fifty per cent. It is assumed that six-molecule Si6-nCnO12 (n=3) rings can play a role of nucleuses for formation of the Si1-xCxO2 compound from SiO2 and CO2 molecules. Thus, silicon dioxide can be considered as a possible solid store for gaseous CO2.IntroductionThe problem of increasing of CO2 in the Earth atmosphere is one of the main modern problems of mankind. One of conceivable ways to decrease the harmful value of CO2 is to convert a part of it to solid state. Iota et al. [1] reported a polymeric (quartz-like) phase of CO2 solid synthesized at high pressure (~40 GPa) and at high temperature (~1800 K). Shortly after this experimental work, Serra et al. [2] reported a total energy calculation of several possible phases of CO2 using plane wave pseudo-potential density functional theory. They concluded that there should be a transition from a molecular phase to a phase isostructural to SiO2 -quartz in the range of 35 to 60 GPa. The latest calculations by Dong et al. [3] have shown that the more favored solid CO2 phase is ß -cristobalite. Recently, Kume et al. [4] have demonstrated the polymerization of CO2 even at room temperature at high pressures up to 80 GPa. Transformations of gaseous CO2 to different solid phases were studied recently experimentally and theoretically [5-8]. The main obstacle for using synthesized CO2 solid as a solution for the CO2 problem is its pressure instability. However the SiO2 ß -cristobalite with the same structure is stable.The question is whether a silicon-oxide system in which a part of atoms of silicon is replaced by atoms of carbon will be stable? If the answer is positive, this system can be considered, in our opinion, as a possible store for CO2."

Jan 1, 2009

By Robert E. (Bob) Brown

Magnesium was discovered by Davy in 1808. The production processes as they exist are not economically competitive with aluminum The electrolytic magnesium process is divided into two steps; one to make the MgCh feed and the other to apply large amounts of electric current to dissociate the feed into magnesium (450 g) and chlorine (1200 g). The production of fuJIy anhydrous, pure cell feed is a major problem Recently, there has been a growth of thermal processes, mainly the Pidgeon silicothermic production process using FeSi to reduce dolomite in horizontal retorts. Pechiney has a large vertical electrical furnace process that also uses FeSi to reduce calcined dolomite in a molten bath containing alumina. Work is proceeding to develop new or modified processes that will greatly improve magnesium production. The present methods and the research and R&D will be reviewed in this paper.

Jan 1, 2001