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By Serdar Aksu, Fiona M. Doyle

"CMP will be an essential process in the production of integrated circuits containing copper interconnects. This study aims to improve our mechanistic understanding of the role that organic chelating agents might play in the reactive slurries used in copper CMP. Copper dissolution behavior in EDTA arid glycine was first examined by producing potential-pH diagrams for the copper-water-EDTA and copper-water-glycine 'systems. The results of potentiodynamic polarization experiments were then considered in light of these diagrams. . In-situ polarization experiments were conducted to gain insight into the electrochemistry of copper during dynamic polishing in slurries prepared from EDT A and glycine.IntroductionCopper has recently started to replace aluminum as the interconnect metal in integrated circuits. Copper interconnection offers faster and more reliable integrated circuits due to its higher electrical conductivity and superior electromigration resistance (1). The damascene method is used to form multilevel interconnects in the manufacture of integrated circuit devices with copper metallization (2, 3). Copper is deposited by CVD or electroplating into vias and trenches etched in the interlayer dielectric (IDL), over a diffusion barrier usually made from titanium, tantalum or their nitrides. Chemical mechanical planarization (CMP) then prepares the wafer for the next deposition step, by removing excess copper and planarizing the surface. During CMP, the wafer is rotated and pressed against a rotating platen covered with a polishing pad. Chemically active slurries containing submicron size abrasive particles (Si02, Al20 3, ceria, diamond, etc.) are applied. Both the mechanical action of the abrasive particles and the chemical action of slurry constituents remove material from the wafer surface. Planarization results because material is removed faster from protruding regions on the surface than from recessed regions. Since CMP can globally planarize .the entire wafer, it has become one of the key technologies for producing integrated circuits with copper metallization."

Jan 1, 2000

By Eiichi Kuzuno, Atsushi Shibayama, Toyohisa Fujita, Kazuo Koike, Toshio Miyazaki, Hitoshi Masuda

"A solid sulfur is more useful to recover and store than a sulfuric acid as a by-product in the zinc hydrometallurgy. In this experiment a zin concentrate (sphalerite) was leached with ferric sulfate at about 373 K for 3 to 6 hours. Zinc was leached more than 95%. After a solid-liquid separation, the leached residue contained solid sulfur was obtained. The particles in the residue were dispersed by lignin and the solid sulfur of approximately 85% was recovered as float product by a flotation with frother in the pH 4. The dried float product was heated at 413K for 2 hours. The pure solid sulfur was recovered. On the other hand in the leached liquid a zinc oxide was ·added and ferrous .iron was oxidized to ferric iron by blowing oxygen. This ferric iron was returned to the zinc leached process after solid-liquid separation.IntroductionZinc concentrate is usually roasted as pretreatment in zinc hydrometallurgy and the produced S02 is changed to sulfuric acid. However, recently in Japan the utilization of sulfuric acid has been limited and it is more costly to store. Instead of producing sulfutic acid the solid sulfur recovery has been examined by direct leaching of zinc_ concentrate in this experiment.In the direct leaching, several kinds of effects have been studied for leaching of sphalerite in ferric sulfate solution. The addition of lignine siilfonate1 • 2) and fine· grinding3) increases the · speed arid leaching fraction of sphalerite. The leaching ratio depends on impurities in sphalerite ores4 • 5). Here, the zinc concentrate is leached ferric sulfate solution under atmospheric pressure at 373K. The solid sulfur in leached residue is separated as float products from other solids by sink-float separation and flotation. The sulfur in float products is purified by evaporation at 413K and recovered."

Jan 1, 2000

By Eduard Ouerra, Nuo Jin

"The use of polytetrafluoroethylene, PTFE, as a solid sorbent for elemental sulfur during pressure oxidation of chalcopyrite was investigated. The effects of agitation, PTFE particle size and lingin sulfonate addition were evaluated using leaching conditions that were otherwise similar to those employed in the CESL process. The effects of these factors and their interactions on chalcopyrite oxidation are explained in terms of interfacial forces and solid-solid interactions. Using relatively fine PTFE powder with vigorous agitation resulted in about 100% copper extraction in less than 90 minutes without the need for grinding of the flotation concentrate.IntroductionThe extraction of copper from sulfide ores has always been dominated by the conventional pyrometallurgical smelting process. Though much effort has been made to develop various hydrometallurgical processing routes, smelting remains as the dominant process, treating approximately 80% of the chalcopyrite concentrates worldwide [1]. However, some of recently emerged techniques for treating chalcopyrite through hydrometallurgical routes are showing results that are competitive with smelting in terms of economical feasibility. Representative methods include: Activox Process, CESL Process, Anglo/UBC Process, High Temperature Pressure Oxidation, and Bio-Oxidation. Among these, the CESL processes operate at a medium temperature range (typically 140-150GC) and oxygen pressure of 100 psi, with chloride as a catalyst, and reportedly achieve copper extractions of about 95% with a light regrinding of flotation concentrate to a p95 of 45 ìðé [2]. In spite of this satisfactory extraction result, the leach residues contain significant amounts of conglomerates which contain a small amount of unreacted concentrate [2], The conglomerations are formed because the elemental sulfur generated is liquid and sticky (melting point of sulfur being 119°C), and has a tendency to wet the sulfide mineral surface, a fact which inhibits the oxidation of the minerals. The overall process chemistry of the CESL process may be summarized as follows [3]:"

Jan 1, 2012

By Nan Zhang, Lei Zhang, Gai-feng Xue, Lina Wang, Pu Liu

"A novel ß-diketone modified silica gel was synthesized by a simple reaction. The prepared material was characterized by diffuse reflectance FTIR spectroscopy and it was used for the adsorption of heave metal ions in the industrial waste water. The main parameters affecting the sorption of heavy metal ions, including pH, water flow rate, and elution, have been investigated in detail. Under the optimized operating conditions, most of the targeted heavy metal ions could be removed. The material could be simply regenerated by hydrochloric acid solution. The method is rapid, selective, economic and applicable to the removal of heavy metal ions from industrial waste water.IntroductionToxic organic pollutants and heavy metals ions mainly from industrial activities such as plating, metallurgy and dyeing industries, are a threat to human health and the surrounding environment, because of their toxicity and persistence after being released into the natural environment [1]. These pollutants must be removed or degraded to an acceptable level, before being discharged to the receiving waters. Therefore, detection and determination of heavy metal ions in industrial waste water is very important.Inductively coupled plasma optical emission spectrometry (ICP-OES) is the most used technique for the determination of heavy metal ions because of its capability for rapid multi-element detection over a wide concentration range and with relatively low detection limits. Compared to other techniques such as neutron activation analysis (NAA), X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS), ICP-OES has the above advantages. Some constituents in industrial waters, such as organic compounds and inorganic salts, may cause matrix effects. In order to achieve accurate and reliable results, an efficient preconcentration of heavy metal ions and their separation from the matrix are usually required."

Jan 1, 2012

By Bora Derin

The synthesis of titanium diboride (TiB2) by carbothermal reductions of TiO2 and B2O3 was investigated. For this aim, TiO2, B2O3 and carbon black powders were dried, weighed out and mixed in stoichiometric molar proportions (TiO2:B2O3:C = 1:1:5). The experiments were carried out in a graphite resistance furnace in argon media using different range of temperature (1400- 1700 °C) and time (0 and 15 min). The phase analyses observation of the products were examined by using XRD.

Jan 1, 2008

By T. Lezhava

A new reactor model with rotating cathodes has been developed where various forms (dendrite, spongy) of metal depositions and their uninterrupted removal are accomplished by the realization of high current densities and low energy consumption. At the same time in contrast with the existing methods a high quality metal powder may be obtained from concentrated electrolytes without any specific organic or inorganic additives, which allows raising the intensity of the process. The reactor can be used for electrowinning of metals with low adhesive capacity (Pb, Ag, Cu, Zn, Ni, Co, etc.) and the powders. The obtained products may be utilized in general metallurgy as well as in powder metallurgy.

Jan 1, 2006

By Lianjun Liu, Ying Li, Qianyi Zhang

"Photocatalytic reduction of CO2 by H2O for production of Cl fuels (CO and CH4) was studied using copper and iodine co-modified TiO2 (Cu-IffiO2) nanocomposites, with copper deposited on the surface and iodine doped in the lattice. The nanocomposites were prepared via a combined hydrothermal and wet impregnation process. All I-doped samples demonstrated visible light activity. Under UV-vis irradiation, co-modification of Cu and I significantly increased TiO2 photoactivity compared with bare TiO2 or those modified with only one species.IntroductionThe photoreduction of CO2 into fuels on photocatalysts such as TiO2 has been regarded as an important approach to solve both energy shortage and globe warming problems [1]. However, the wide band gap and fast recombination ofphotoinduced hole (h+) and electrons (e"") limited the application of TiO2 in CO2 photoreduction reaction. Extensive research has been conducted to improve the photocatalytic ability ofTiO2 by depositing or doping foreign ions that can enhance charge transfer and/or creates intra-band-gap states to induce visible light absorption at the subband- gap energy. Compared with mono-doping, co-doping of metal/nonmetal species has been reported to have higher photocatalytic activity for TiO2 [1-3]. Our previous studies showed that Cu deposited on TiO2 [4] or iodine doped in TiO2 [5] significantly enhanced the catalytic efficiency for CO2 photoreduction and increased the response to visible light. We hypothesize that there could be a synergetic effect if TiO2 is co-modified by both Cu and I species resulting in further improvement in CO2 reduction efficiency. In this work, we synthesized and characterized Cu-IffiO2 samples and investigated their activity toward CO2 reduction under visible and UV-vis illumination, respectively.Experimental MethodsMaterialsTitanium tetra-isopropoxide (TTIP, 98%) and isopropanol (C3HsO, 99.8%) were purchased from Acros Organic. Iodic acid (HIO3,99.8%) and Copper Chloride (CuCh, 99.9%) were purchased from Alfa Aesar. All other chemicals were analytical grade and used without further treatment."

Jan 1, 2012

By A. V. Tarasov, A. D. Besser

A processing flowsheet has been developed for treating substandard lead-containing polymetallic bulk concentrates and intermediate flotation products containing precious metals, which comprises oxidizing roasting in a calcination kiln and electrothermic smelting generating low volumes of off-gas. The proposed flowsheet also incorporates a dust collection system and sulfur dioxide recovery from off-gas. It is proposed to implement this process by using a reaction smelting technique. For this purpose, the charge to be fed to the smelting furnace after its calcination in a drum-type rotary kiln must have a ratio of sulfide sulfur to sulfate sulfur of at least 1 :2. Electric smelting makes it possible to produce lead bullion that also collects the precious metals contained in the feed, as well as copper-lead matte and slag containing zinc. The recovery of lead into lead bullion and into matte is approximately 83% and 14%, respectively (thus the overall recovery is 97%); the total recovery of gold and silver into lead bullion and matte is 98%; th\lt of copper into matte is 89%; the recovery of zinc into slag is 96%; and that of sulfur into sulfuric acid or gypsum is 90%. After the recovery of zinc from slag, the latter can be utilized in the construction industry.

Jan 1, 2000

By Giuseppe Granata

An innovative process using titanium tetrachloride (TiCl4) gas as reactant has shown successfully to obtain titanium through electro-winning of TiCl2 formed in-situ on titanium cathode. The process involves a continuous feed of TiCl4 gas reacting onto a titanium cathode immersed in a molten salt (NaCl-KCl), whereby in-situ formation of titanium dichloride (TiCl2) through a disproportion reaction. Simultaneously, the TiCl2, thus in-situ formed in the molten salt media, has been reacted into chlorine gas and titanium, the latest electrodeposited on the titanium cathode by electrowinning. The reaction kinetic of this innovative process was investigated in terms of TiCl2 in-situ formation rate and galvanostatic electrodeposition rate, where, in particular, the effect of operating variables such as TiCl4 partial pressure and flow rate, as well as temperature and galvanic potential applied was investigated.

Jan 1, 2014

By Rolando Campos

The CODELCO-CHILE Teniente Converter Technology, is presently being applied in four Chilean smelters (Caletones, Chuquicamata, Potrerillos and ENAMI-Ventanas). A Teniente Converter is due to be used at ENAMI-Hernan Videla Lira (Paipote) smelter in the near future. Also, a Teniente Converter is to be installed as part of a retrofit project for Nkana smelter of Zambia Consolidated Copper Mines Ltd. (ZCCM). The charge to be treated through this smelter will consist of a blend of concentrate arisings from the various concentrators within the ZCCM group. The present status on the application of the Teniente Converter Technology at Caletones smelter as well as its projected performance when used at Nkana smelter, are presented in this paper. The design operational basis, autogenous smelting throughputs, concentrate to matte ratios and benefits due to the use of technical oxygen, are presented and analysed.

Jan 1, 1992

By Meyer Steinberg

"Some early experiences of a Cooper Union Chemical Engineer on the Manhattan project and his latest studies on CO2 Greenhouse Gas Mitigation Technologies are presented. Mitigating Global Greenhouse effect while maintaining a fossil fuel economy, requires improving the efficiency of conversion and utilization of fossil fuels, use of high hydrogen content fossil fuels, decarbonization of fossil fuels and sequestration of carbon and CO2 applied to all energy consuming sectors of the economy including electric power generation, materials production, transportation and industrial domestic heating. Decarbonization means removal of carbon as C or CO2 either before or after fossil fuel utilization and sequestration means long term disposal of C or CO2. The review will cover the principles of removal and recovery from power plant, stacks, the oceanographic and geological disposal of CO2 and the conversion of CO2 to gaseous and liquid transportation fuels. The global economic aspects of CO2 mitigation technologies are touched upon.IntroductionThis is an odyssey of a chemical engineer. My career started with the production of U235 at the Gaseous Diffusion Plant in Oak Ridge, Tennessee and the production of PU-239 metal at Los Alamos on the Manhattan Project. After 40 years at Brookhaven National Laboratory, I wound up performing studies on CO2 mitigation technologies. The following is a power point presentation on the subject of global warmingThe DOE is proposing to increase its sequestration development program in order to maintain the utilization of our vast resources in coal both for power and for transportation fuel production. Congress is considering steps to promote energy efficiency in attempts to solve not only the CO2 problem, but also the prime problem of energy supply. We will be promoting increases in energy efficiency as time goes on."

Jan 1, 2008

By M. Ide, K. Takemura, S. Taenaka, K. Shinzawa

"The laser characteristic is strongry dependent upon the stoichometry of forsterite (Mg2Si04) and YSO (Y2Si05) single crystals, because of change in the valency and occupied sites of doped Cr in the lattice so that mole ratios of Mg0/Si02 and Y203/Si02 in the above single crystals must be precisely analyzed. In this study ICP-AES was applied for analyzing the mole ratios. Emission intensities corresponding to Si and Mg or Si and Y were measured at the same time with internal standard method. Preparation of sample solutions, measurement conditions of ICP-AES and interferences by coexisting components were discussed, resulting in excellently precise detennination of stoichometry of the above single crystals.IntroductionIn conventional stoichiometric analysis of single crystals, the stoichiometry is detennined by analyzing each component separately with titrimetry and gravimetry techniques. On the other hand, by stoichiometric analyses using ICP-AES, emission intensities corresponding to components are measured at the same time with internal standard method. Consequently erros caused by variation of analytical condition are canceled out.Cr-doped Mg2Si04 and Y2Si05 syngle crystals are known as laser materials. The change of valency and occupied sites of doped Cr affect the characteristic of single crystal as aleser materials. The change of state of doped Cr.Stoichometric composition of Mg2Si04 is constructed by 2mole of MgO and 1mole of Si02, and Y2Si05 is constructed by 1mole of Y203 and 1mole of Si02. In this study, required analytical precision in component mole ratio is within an error of 0.0010 for Mg2Si04 (CV=0.05wt%), and within an error of 0.0030 for Y2Si05 (CV=0.05wt%) (Table I )."

Jan 1, 1998

By G. C. Yao

Branch and needle-shaped intermetallic compounds of iron, silicon and aluminum normally exist in the molten aluminum. If a suitable amount of manganese metal is added into molten aluminum, the shape of the intermallic compound particles may become lumpish and spherical. According to the difference in electric and magnetic properties of these impurity particles and molten aluminum, these impurity intermetallic compound particles can be separated by applying an alternating magnetic field. In this experiment the alternating magnetic field was formed by a "c" type loop with AC (50Hz) current. The inner vacuum of the fireclay refractory separator is 25xl5xl30mm3 with a lateral baffle inside. The separator was put into the interspace of the "c" type loop. It was found that the longer the separation time, the larger the amount transferred of impurities. The amount of transferred impurities increases with the increase of separation time and intensity of magnetic field. The addition of manganese metal enhances significantly the efficiency of impurity separation

Jan 1, 2003

By Yuanyuan Zhang, Patrick J. Masset

"The reduction of FexO in slag is one of the fundamental reactions in iron and steelmaking technology, including the blast furnace process (BF). Experiments on the reduction reaction of iron oxide using CaO-SiO2-Al2O3-FexO-C mixtures were carried out using thermogravimetric analysis (TGA) under reducing conditions at temperatures up to 1100°C. The composition of the primary slag was chosen so that the FexO concentration varied between 0 and 75 wt % and the CaO/SiO2 ratio being kept constant to 0.90. From the TGA curves recorded isothermally at different temperatures the kinetic parameters of the iron oxide reduction were determined.IntroductionIn blast furnace the iron ores and coke are charged in layers from the top. The reduction of iron oxide by coke is one of the fundamental reactions in the blast furnace process. Although a great amount of work has been done on the topic of reduction of composites [1, 2, 3], gasification of carbon [4, 5] and reduction of iron oxides by CO [4, 5, 6], the mechanism of reduction in iron oxide - carbon powder mixtures is not fully understood. Fruehan [1] and Rao [2] studied the reaction rate of the reduction of iron oxide by different types of carbon and concluded that the reaction mechanism is controlled by the oxidation of carbon at temperatures up to 1200°C. Rao [2] studied the reaction of hematite with graphite as carbon source up to 1080°C. An activation energy close to 300 kJ/mol was calculated within the temperature range of 950°C to 1087°C. In his study, Fruehan [1] determined the rate of reduction of Fe2O3 and FeO by coal, coke and coconut charcoal as carbon sources within the 900°C to 1200°C temperature range. He found that the reduction of Fe2O3 by carbon occurs in two stages and that the reduction of Fe2O3 to FeO is faster than that of FeO to Fe. This is due to the fact that the CO2/CO equilibrium ratio is higher, and hence, the rate of oxidation of carbon is faster. Fortini and Fruehan [3] have studied the reduction reaction of wustite by graphite and wood charcoal. They found that the wustite reduction can have a significant effect on the overall rate of reduction in composites at high temperatures or in the presence of a large excess of carbon. The calculated activation energy of the reduction reaction by wood charcoal was close to 368 kJ/mol, while the activation energy of the reduction reaction by graphite was 444 kJ/mol."

Jan 1, 2011

By Neusa Alonso-Falleiros, Aristeu Braz da Veiga, Marcelo B. Mourão, Adriano Pescarmona, Antonio Alberto Froes Schettino, Cyro Takano, Carlos A. S. Giraldo

"The Caron process of nickel extraction from lateritic ores produces a fair amount of an inert residue, the so-called “black sludge”, that is disposed in a dam according to the required environmental regulations. On the other hand, it represents an opportunity to resource recovery. This work presents the characterization of the residue, discusses some possible ways to recover the valuables, and presents experimental results of pyrometallurgical runs aimed at recover nickel as an iron-nickel alloy. It has been shown that the residue contains large amounts of silicon, iron, aluminum and magnesium, in the form of oxides and silicates, and small quantities of nickel, cooper and cobalt, besides several other elements. It has also been shown that gravimetric or magnetic concentration methods do not present promising results. On the other hand, it is possible to obtain iron-nickel alloys by high-temperature carbothermic reduction of the “black sludge”.IntroductionThe Caron process consists of a combined pyro-hydrometallurgical process to extract nickel from high iron limonitic lateritic ores, recovering also the cobalt present in the ore. The main steps are the reduction roasting of the ore, aiming at a selective reduction of nickel and cobalt to the metallic state, avoiding as much as possible iron reduction, followed by leaching with ammonium carbonate solution and the recovery of metal from the pregnant liquor [1,2]. As a result, significant amount of tailings are generated, that are disposed in appropriate dams. This residue, called “black sludge”, contains significant proportion of silica and iron, and also small amounts of nickel, cobalt, cooper and some other elements. Due to diminishing deposits of nickel ore, high metal prices and a significant amount of “black sludge “ available after several years of operation of the plant, Votorantim Metais, who operates a facility in Brazil that uses the Caron process, decided to explore the possibility of recover nickel from the residue. This paper presents the characterization of the residue, and the results of experimental work aiming recovery of nickel from it."

Jan 1, 2008

By P. Gray

Process and engineering development of the Warner Zinc Process over the past two decades has proceeded alongside the world-wide collection and analysis of operating and cost data of current processing practices from sulphide ores to refined metals. Study of these data shows that recoveries are dependent on mineralogical characteristics of the sulphide matrix and point to the inadequacy of differential flotation as a tool for preparing feed for smelters. The paid-for return at the mine on the combined metal values in zinc rich sulphide ores rarely exceeds 80% and increasingly runs as low as 50-60%. Surveying the possible alternative ways of improving these performances leads to the conclusion that the Warner Process is the only technology in sight that could meet a target of 90% paid-for recovery and that its development has now reached a point where it can be a fully practicable process for all mixed sulphide ores.

Jan 1, 2000

By Adrien Antenen, Didier Villette

CITRON has developed a new process for the recycling of hydroxide sludge, household batteries, catalysts, automobile shredding residues, grinding sludge and other metal containing organic and inorganic waste. A pilot plant with a capacity of 1,000 tons per year has started operations in April 1998. In August 1999, an industrial plant became operational with an initial treatment capacity of 23,000 tons.

Jan 1, 2000

By René Bustamante

The subject of this paper is a comparative evaluation of different copper smelting gas cooling techniques, using "productivity and quality" criteria. The first section presents a brief description of the operation of the radiant and the evaporative cooling systems, focusing on the differences between each other, in particular regarding. a) mass and energy balances; b) gas flow, temperature and composition; c) dust concentration and recovery. This section includes a brief discussion of the "client-server chain", i.e. the links between the cooling equipment and the down-and up-stream operations. More in particular, the up-stream server relationship impacts on the operating stability of the furnace, and in turn on furnace down-time and Cu production losses; and the down-stream client relationship affects the operation of the electrostatic precipitators, in terms of workload and cost of handling larger quantities of dust of a given dust size The second section deals with the development of indexes to measure and compare value added through the "utilization, productivity and quality" that can be expected of both cooling methods at the physical and economic levels, and the impact on the overall smelter productivity and the final cost composition of copper. The final section presents the results and includes a discussion of the comparative advantages and disadvantages of both cooling systems.

Jan 1, 1999

By Kathryn Hindmarsh

The most common method for the concentration of cyanide in gold leach circuits is based on the titration of cyanide ions with silver ions. This can either be done manually as a titration with a visual end-point or by using one of several commercial cyanide analysers which are 'based on the same titration but use a potentiometric end point This method has 'its limitations in the case of some ores such as those containing high amounts of soluble copper and those that are treated at low (less than pH 9) pH values in that the titration results do not accurately reflect the concentration of cyanide which is available for the dissolution of gold. This paper will present the results of the development of a novel "active" cyanide analyser which is based on the rate, of the reaction between gold colloids and cyanide. Gold colloids have a deep red colour and can be very simply prepared and stored for extended periods of time when stabilized. t has been shown that colloidal gold behaves similarly to metallic gold, dissolving in aerated sodium cyanide solutions to give the colourless Au(CNh-ion, This allows the reaction between the colloids and cyanide to be monitored spectrophotometrically at 520 nm. An automated instrument has been developed around this concept which can analyse a filtered pulp stream every few minutes with periodic calibration using standard cyanide solutions, Results of test work on synthetic solutions and solutions derived from several Australian gold plants will be presented as will the results of a comparative evaluation with a commercial titration analyser on a local gold plant

Jan 1, 1998

By Suzanne Young

The effect of LiF additions on liqt.1id1.:1s temperature and electrical conductivity over a wide range of cryolite bath ratios (1.0 to 1.5 weight ratio) was investigated. Results did not agree with multi-regression equations reported by Dewing and Choudhary over the entire region. New regression equations were developed. Reasons? are given for the differences. The models are used to discuss the economic implications of LiF additions to Hali cell electrolytes.

Jan 1, 1985