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By Wenjun Duan, Kun Wang, Qingbo Yu, Qin Qin

"A novel oxygen production technology noted chemical looping air separation (CLAS) was introduced and properties of Cu-based oxygen carriers used were investigated. The oxygen carriers were prepared by mechanical mixing. Al2O3, Fe2O3, ZrO2, TiO2 and SiO2 were used as binders during the preparation. XRD patterns show that spine! oxides are formed using Al2O3 and Fe2O3 as binders. Phases of CuO and binders keep stable using ZrO2, TiO2 and SiO2 as binders. BET values of oxygen carriers increase in the order of ZrO2>TiO2>SiO2>Fe2O3>Al2O3. The effects of temperatures, binders, particle sizes and flow rates on reduction/oxidation reaction rates were studied in TG experiments. The reduction reaction rate increases in the order of ZrO2>TiO2>SiO2. The effect of binders on the reactivity of oxidation is not obvious. The reduction and oxidation reaction rates both have the tendencies of increasing with the temperature increasing and with gas flow decreasing. However, the effects of gas flow and particle size are little.IntroductionChemical looping air separation (CLAS) is a novel oxygen production technology. The oxygen carriers used in CLAS release oxygen in reduction reactor and regenerate in the oxidation reactor. Selecting suitable oxygen carriers is the key for CLAS. Oxides of CuO, Mn2O3, Co3O4, Pb3O4, CrO2, SrO2, PdO2 and CeO2 have the property of releasing oxygen at suitable temperature and oxygen partial pressure [1]. Among these oxides, CuO, Mn2O3, Co3O4 are the most common compositions used to prepared oxygen carriers for chemical looping combustion (CLC) or chemical looping with oxygen uncoupling (CLOU) [2-5]. Moreover, thermodynamic calculations and preliminary experiments were carried out on oxides of Cu (CuO/Cu2O), Mn (Mn2O3/Mn3O4) and Co (Co3OJCoO) by Moghtaderi to ascertain their feasibility for CLAS process [6]. CuO has the highest oxygen transport capacity (0.1 g 02/g CuO compared to 0.03 g 02/g Mn2O3 and 0.06 g 02/g Co3O4). However, agglomeration is the biggest issue for copper oxides used at high temperature because of its low melting point (l 450°C for CuO, 1235°C for Cu2O and 1075°C for the mixture of CuO and Cu2O) [7]. In order to improve the capability of anti-sintering and stability ofCuO, binders (ZrO2, MgAl2O4, TiO2, SiO2, Fe2O3, Al2O3, cement) are added during the preparation of Cu-based oxygen carriers [8]. In this paper, the Cu-based oxygen carriers were prepared by mechanical mixing method. TiO2, Al2O3, Fe2O3, ZrO2 and SiO2 were selected as binder. XRD, BET and SEM were used to analyze the phase, surface area and surface morphology of oxygen carrier prepared. The reactivity of oxygen reduction and oxidation of oxygen carriers prepared were investigated in STA409PC thermal analyzer."

Jan 1, 2014

By Rodney T. Jones

DC arc furnaces were first used industrially for the reductive smelting of chromite fines to produce ferrochromium thirty years ago. Since then, they have been used for a variety of applications, including the smelting of ilmenite to produce titania slag and pig iron, the recovery of cobalt from non-ferrous smelter slags, and the smelting of nickel laterite ores to produce ferronickel. The power of these furnaces has increased from 12 MW to 72 MW for ferrochromium, and to 80 MW for ferronickel. The largest of these furnaces requires two electrodes to carry sufficient current to generate this much power. A review is presented of various DC arc furnaces in use, along with a discussion of the likely ways in which furnace power might be increased further in the future.

Jan 1, 2014

By R. S. Tahautdinov, A. N. Posazhennikov, V. V. Bastrygin

"The Bakal (South Ural, Russia) deposit of iron ore bearing iron carbonate (siderite) with the capacity of more than 1 billion tones belongs to the MMK. This ore cannot be fully processed via blast furnace technology because of high content of MgO. According to the investigations carried out in the USA and Japan in 1999-2004 the ITmk3 (Ironmaking Technology mark three) RHF technology is a breakthrough in Ironmaking. Four iron ore types (hematite, magnetite, high and low Al2O3/SiO2) were tested. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from iron carbonate bearing ore via the ITmk3 by means of the lab scale testing. Samples of iron ore and carbon reductant were chemically and physically analyzed. Green pellets were processed via a lab tube furnace to simulate RHF conditions. The nuggets and slag were chemically analyzed. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.IntroductionThe ITmk3 process upon which this paper focuses was developed by Kobe Steel in its research facilities in 1996 [1]. After pilot testing at Kobe Steel’s Kakogava Works in 1999-2004 the pilot demonstration plant was built and operations were successfully carried out by Mesabi Nugget joint venture in 2002-2004. Steel Dynamics has committed to building the commercial plant at the Mesabi Nugget site in Hoyt Lakes (Minnesota). Only 4 iron ore types (hematite, magnetite, high Al2O3/SiO2 and low Al2O3/SiO2), as well as 4 coal types with range of volatility, ash and fixed carbon were tested. Results were consistent with nugget characteristics confirming ITmk3’s flexibility with respect to raw material inputs. At the same time, no research in the field of nugget from iron carbonate bearing ore with high content of MgO has been done. Such kind of iron ore is restricted for charging into the blast furnace due to contamination of MgO. The reason for restriction is the limitation of load of MgO in the blast furnace. If a lot of MgO enters the blast furnace, slag becomes viscous. The viscous slag is obstacle for stable operation of the blast furnace."

Jan 1, 2011

By Donghai Li, Cheng Pan, Xuewei Lv, Mei Liu, Enguang Guo

"Phosphorite is the main raw material for the production of phosphorus in chemical industry. More attentions have been drawn to the phosphorite concentrate beneficiated from low-grade phosphorite due to the decrease of high-grade phosphorite. For another, the agglomeration process is necessary for the phosphorite concentrate after beneficiation process. The mineralogy and sintering process of the phosphorite from Leshan, China were studied in this work. The result shows that the main phases in the phosphorite are fluorapatite (Ca3(P04)3F), hydroxylapatite (Cas(P04)3(0H)), quartz (Si02) and dolomite (CaMg(C03)2). The yield of the sinter increases with increasing the carbon dosage to 7%, and then decreases when it continuously increases. Similar regularities were found for the strength and the content of P20s of the sinter. The best strength of the sinter as well as its P205 content were discovered when the carbon dosage is 7%. Fluorapatite ((Ca5(P04)3)F) is the main phase in the sinter while fuggerite (Ca2MgSiz01) is the main binder phase.IntroductionPhosphorus is an important foundation industrial raw material of national defense industry, food industry and chemical industry, where it is used to produce red phosphorus, phosphonium hydroxide, phosphorus pentasulfide and phosphoric anhydride[l-2]."

Jan 1, 2013

By H. Y. Sohn, M. K. McCarter, Bradley C. Paul

"A computer model was constructed for bacterial leaching of the major sulfides found in porphyry deposits, including bornite, chalcocite, chalcopyrite, covellite, cubanite, enargite, native copper, pyrite, and pyrrhotite. The model incorporates equations for the sulfide minerals dispersed in the rock matrix. Leaching occurs by reactions with ferric ion diffusing into the rock fragment: Ferrous ion is resenerated to ferric with oxygen by bacteria at a temperature dependent rate. The model keeps track of the net acid generated, oxygen consumed by the bacterial oxidation of ferrous ion, heat generated, jarosite and hematite precipitated, and copper leached. The model was used to predict the rate of copper recovery, heat generation and oxygen demand for a variety of run-of-mine sized porphyry ores. These results were used in the design of a ventilation system and the economic analysis of a modified in situ extraction method that may be cost competitive with conventional copper production involving open pit mining.IntroductionA study was undertaken at the University of Utah to evaluate the technological and economic feasibility of mining copper by a method referred to as Flood Drain Leach Cell (FDLC) mining. Cells 60 by 75 meters in plan and 70 meters in height are created throughout the ore body by a modified Vertical Retreat Mining technique that includes the removal of 25% swell material. The swell material is leached in finger dumps on the surface while the cells underground are bulkheaded, flooded, drained, and artificially aerated to promote bacterial ferric sulfate leaching. Solutions are cycled through several cells to reach pregnant grade of 1 gram copper per liter of solution. These solutions are then fed to an underground solvent extraction plant and then a surface electrowinning tankhouse."

Jan 1, 1988

By Yuanbo Zhang, Mingjun Rao, Guanghui Li, Chongzhong Ouyang, Shuhui Zhang

Oolitic hematite ore with high-phosphorus content is currently recognized as one of the most refractory iron ore resources in the world. The high-phosphorus content and unique structure of the oolitic hematite ore make it difficult to be beneficiated. The process of direct reduction followed by magnetic separation has significance to the utilization of oolitic hematite ore, and sodium salts can improve the dephosphorization. However, the behavior of phosphorus during reduction roasting, and the intensified dephosphorization mechanism of sodium salts are not clear. In this study, by using chemical analysis, chemical phase analysis, XRD analysis, optical microscopy, and scanning electron microscopy analyses, the behavior of phosphorus during reduction roasting of high-phosphorus content oolitic hematite ore and the effect of sodium salts on behavior of phosphorus were studied.

Jan 1, 2015

By E. V. Redin

"The Bakal (South Ural, Russia) deposit of iron ore bearing iron carbonate (siderite) with the capacity of more than 1 billion tones belongs to the MMK. This ore cannot be fully processed via blast furnace technology because of high content of MgO. According to the investigations carried out in the USA and Japan in 1999-2004 the ITmk3 (Ironmaking Technology mark three) RHF technology is a breakthrough in Ironmaking. Four iron ore types (hematite, magnetite, high and low Al2O3/SiO2) were tested. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from iron carbonate bearing ore via the ITmk3 by means of the lab scale testing. Green pellets were processed via a lab tube (chamber) furnace to simulate RHF conditions. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.IntroductionThe ITmk3 process upon which this paper focuses was developed by Kobe Steel in its research facilities in 1996 [1]. After pilot testing at Kobe Steel’s Kakogava Works in 1999-2004 the pilot demonstration plant was built and operations were successfully carried out by Mesabi Nugget joint venture in 2002-2004. Steel Dynamics has committed to building the commercial plant at the Mesabi Nugget site in Hoyt Lakes (Minnesota). Only 4 iron ore types (hematite, magnetite, high Al2O3/SiO2 and low Al2O3/SiO2), as well as 4 coal types with range of volatility, ash and fixed carbon were tested. Results were consistent with nugget characteristics confirming ITmk3’s flexibility with respect to raw material inputs. At the same time, no research in the field of nugget from iron carbonate bearing ore with high content of MgO has been done. Such kind of iron ore is restricted for charging into the blast furnace due to contamination of MgO. The reason for restriction is the limitation of load of MgO in the blast furnace. If a lot of MgO enters the blast furnace, slag becomes viscous. The viscous slag is obstacle for stable operation of the blast furnace."

Jan 1, 2012

By Stanko Nikolic

Ferrous calcium silicate slags are potentially important for future practice in copper converting operations and processes and can be described by the ?Cu2O?-FeO-Fe2O3-CaO-SiO2 system. Despite its industrial importance the phase equilibria in this system have not been fully investigated. Characterization of this slag system is necessary to improve the design and optimization parameters of new processes, including fluxing and operating temperatures. Experimental methods have been developed to investigate the phase equilibria of these slags at copper saturation and without copper. This technique involved equilibration of samples at a fixed oxygen partial pressure, rapid quenching, and analysis of the compositions of phases using electron probe x-ray microanalysis (EPMA). Liquidus and solidus data are reported for the primary phase fields of spinel, wollastonite and tridymite at 1250oC and an oxygen partial pressure of 10-6atm. The resulting data has been used to construct liquidus isotherms in the ?FeO?-CaO-SiO2 system both in equilibrium with and without molten copper. The experimental results were compared with the predictions of a thermodynamic computer package utilizing a self consistent thermodynamic database. The predictions of the model were in good agreement with the experimental isotherms when projected onto the FeO-CaO-SiO2 section, however the copper concentrations in the liquid phase at copper saturation were lower than predicted using the current database of the model.

Jan 1, 2006

By Hong Yong Sohn

A novel flash ironmaking technology is under development at the University of Utah under the support of U.S. Department of Energy (DOE) and American Iron and Steel Institute (AISI). The history of the development from the conception of the idea to the current status will be discussed. The flash ironmaking process produces iron directly from fine iron ore concentrates without requiring cokemaking and pelletization/sintering, which will enable the technology to significantly reduce energy consumption and carbon dioxide emissions compared with blast furnace ironmaking. Unlike other gas-based ironmaking processes, this technology will not suffer from the problems of solid sticking and fusion. Current work is focused on the method of supplying the energy required to maintain the necessary temperature, as an intermediate step to determine the scalability for larger, industrial-scale pilot trials.

Jan 1, 2014

By Garth James

Bacterial consortia capable of degrading cyanide and metal-cyanide complexes were obtained from gold mine process waters using enrichment cultures. The cultures contained either cyanide, tetracyanonickelate, or ferrocyanide as a sole nitrogen source. Several bacteria were isolated from the consortia, but none of these organisms were capable of degrading cyanide or cyanide-metal complexes at rates equivalent to those of the intact consortia. The consortium from the cyanide enrichment was capable of completely degrading cyanide from an initial concentration of over 100 ppm in less than one day, when cultured using a fed-batch method. Tetracyanonickelate and ferrocyanide were degraded more slowly. Overall, these results demonstrate that bacteria capable of degrading cyanide and cyanide-metal complexes can be isolated from mine process solutions and are capable of significantly reducing cyanide concentrations under appropriate conditions.

Jan 1, 1998

By T. K. Mukherjee

The importance of the processing of secondary resources such as solid industrial wastes and liquid effuents as well as byroducts for the recovery of the associated metal values hardly needs any elaboration. Such processing contributes in no small measure.towards the augmentation of the availability and the supply position of resources. As an added benefit, it leads to a reduction in environmental pollution caused by the undesirable waste materials. As some typical examples of secondary resources in the Indian scenario, mention' can be made of spent catalysts, metal/alloy scrap, ash, consumed batteries, flue dust, slag, sludge and slime, pickling solutions, spent acids; plating rinse solutions, spent etchants, waste water from synthetic fibre manufacture and from tanneries etc. These wastes constitute a source of a variety of non ferrous metals. In the processing of secondary resources like these, the techniques of hydrometallurgy such as solvent extraction play a pivotal role. This paper outlines the efforts made to use solvent extraction to recover (1) base metals such as copper, zinc, nickel and cobalt from a number of secondary resources like cake, and sludge(2) refractory metals like molybdenum and vanadium from sulphidic, byproducts and spent catalyst and (3:) nuclear metal like uranium from phosphoric acid. In the case of base metals, process flowsheet involving the use of acidic extractants such as DEHPA and PC88A have been optimised. The problem of iron removal from the leach liquor, "which influences the metal recovery process significantly, has drawn a special emphasis. hi the case of refractory metals, basic extractants .like Alamine 336 has been pressed into service to produce kilogramme. quantities of pure salts of molybdenum and vanadium, Finally, the paper gives a brief account of plant experience in recovering uranium from phosphoric acid, using 'a solvent system comosed of DEHPA and TOPO.

Jan 1, 1996

At its Copper Cliff Smelter, Inco Limited processes a bulk copper-nickel concentrate in two Inco oxygen flash furnaces. The furnace matte is converted to low iron matte for further processing, and the molten converter slag is recycled to the flash furnaces. The flash furnace slag is discarded. Natural gas or coke supplies a minor proportion of the process heat requirements, thus limiting the flash furnace matte grade to the target 45% CuNiCo. Coke addition to the furnace offers a potential means of establishing a reducing barrier on the surface of the molten bath. Such a practice would be conducive to producing sulfur deficient (partially metallized) matte. At the same iron content, the iron activity of sulfur deficient matte is higher than that of regular matte. A supernatant coke barrier could, therefore, be expected to lead to higher nickel and cobalt recoveries, reduction or even elimination of magnetite furnace bottom build-up and increased sulfur elimination as SO2 in the flash furnace. Preliminary experiments were conducted in a mini plant flash furnace to investigate the effect on process metallurgy of the suggested modified scheme. This paper presents the experimental results and discusses key aspects of the possible operation of the Inco flash furnace with a coke barrier separating the freeboard from the molten bath.

Jan 1, 2003

By Zhihe Dou, Yu Fang, Zimu Zhang, Yan Liu, Xiaoli Jiang Dianhua Zhang, Guanting Liu

"With the idea of “waste control by waste itself”, we come up with the crafts of using waste calcium carbide to mineralize CO2 in electrolytic aluminum waste gas, design and make out “Venturi gas-liquid-solid three stage reactor”, do experiments under the system of CO2-Ca(OH)2, investigate the influence on gas absorption by pH meter; investigate the influence on diameter distribution , rise velocity of bubble and local gas hold-up by dual conductivity probes; investigated the absorption of CO2 in every stage reactor under different initial proportion of CO2 by intelligent gas measurement system. The results showed that the reactor can fully absorb the CO2 in waste gas, and it has largely shorten the time of absorption and improve the CO2 utilization compared with the single stage reactor.The residual proportion of CO2 in the gas is below 0.08% through the absorption of three stage reactor,which show that absorption is extremely improved.IntroductionCarbide slag is a kind of polluting hydrolysis reaction byproducts in producing carbide in wet reactor, and it is mainly comprised by Ca(OH)2, It's estimated that there are about million tons carbide slag are piled up per year. Carbide slag is a kind of industrial wastes that hard to deal with ,which are treated by land filled in the past. It would not only occupy a lot of land, but also lead to secondary pollution [1].CO2 is the main greenhouse gas by now. In 2010, global CO2 emission has reached 33.5 billion tons, while China has now become the world's second largest emitter of CO2, emissions accounting for about one-seventh of the world [2].As the experts estimates, the greenhouse gas emission of whole nonferrous metal industry may over 0.6 billion tons per year, while CO2 emission of electrolytic aluminum is 0.334 billion tons per year [3]. So it is necessary and pressing to discover the reusing CO2 of electrolytic aluminum. With the idea of “waste control by waste itself”, we came up with the crafts of using carbide slag to mineralize the CO2 in electrolytic aluminum waste gas, which was experimented on the counterflow-three stage-venturi reactor,and studied the local gas holdup, residual concentration of CO2 and the volumetric transfer coefficient in the reactor."

Jan 1, 2014

By Ahmet Haxhiaj, Jaroslaw Drelich

"Both composition and porosity of pellets are the main parameters influencing the reductive melting process in water-jacket furnace during the roasting of sulfide lead concentrate. Roasting in a smelter located in Trepçë is done at about 9000C, for pellets which are composed of PbS, CaCO3, Fe2O3, and SiO2. In order to faciltiate the formation of slag in the reductive melting, the pellets must have the proper content of CaO, SiO2, and FeO, and porosity. The plant’s practice indicates that pellets with porosity of 18% do not melt adequately in the water-jacket furnace. The optimum porosity for the proper melting of pellets needs to be 32-40% and can be achieved when pellets are loaded with more than 10 wt.% CaO. Pellets with less than 10% CaO have a limited network of pores, such that reactive gases cannot reach the entire ore structure. Also, the composition of the pellets must satisfy the ratio of CaO : SiO2 : FeO = 1 : 1.2 : 1.8 to facilitate the formation of slag in the reductive melting process.IntroductionAgglomeration roasting of sulfide lead concentrate is an important phase in the production of lead by reductive melting [1-6]. The reductive melting process is a complex process with contradictory effects of several technological indexes which many times are hard to measure and determine. In this process, loading the water-jacket furnace with pellets of optimized composition and structure can reduce the consumption of coke, and achieve high level of lead recovery. Pellets (agglomerates) should be porous, but at the same time they should have necessary mechanical strength. ‘Self-melting’ ability of pellets is controlled by the types and quantities of fluxes blended into the pellet composition. Three major additives and their role are:"

Jan 1, 2011

By Jim Sarvinis, Rory Hynes, Elizabet Cruz, Kerry McKenna, Maytinee Vatanakul

"Energy efficiency improvements achieved using heat recovery processes offer benefits to both the business case and environmental impact of metallurgical facilities. Global demand drives the development of lower and lower grade ore bodies. This trend results in higher energy intensity and consequently increased waste heat. Waste heat boilers and Organic Rankine Cycle (ORC) processes are becoming cost competitive methods of utilizing this waste heat.This study analyzes heat recovery from available sources to produce power using, • High grade: waste heat boiler and steam turbine generator. This system will produce electricity, and/or process steam.• Low grade: ORC to produce electricity. The cycle is well adapted to low- moderate temperature heat sources.Processes used in metallurgical plants, such as hot exhaust streams, cooling and condensers could benefit from application of these systems.The study demonstrates:• The energy and cost saving potential of waste heat recovery technologies,• The environmental benefit.IntroductionIn recent decades, process intensification has resulted in increased productivity from unit operations such as kilns, fluidized bed reactors and smelting furnaces and decreased unit operating costs. In the coming decades, the industry’s challenge will be to continue this trend while at the same time decreasing the consumption of fossil fuels and further reducing the environmental impact of its processes.The U.S. Department of Energy reports that available waste heat sources in industry, which is approximately seven quadrillion BTU (~7,400 PJ/y), exceeds the current production of all renewable power sources combined. In Canada there are about 2,300 PJ/y of available waste heat, with the pulp and paper, metallurgy, chemical/petrochemical and oil refining industries the main players. Natural Resources Canada (NRCan)9 has estimated that about 25% of that heat could be recoverable using existing technologies, which in turn, represents a reduction of 27 Mt/y of Green House Gas (GHG) emissions, plus considerable water savings due to lower water cooling requirements and less fossil fuel consumption."

Jan 1, 2011

By T. K. Mukherjee, C. K. Gupta

"The importance of the processing of secondary resources such as solid industrial wastes and liquid effluents as well as byroducts for the recovery of the associated metal values hardly needs any elaboration. Such processing contributes in no small measure towards the augmentation of the availability and the supply position of resources. As an added benefit, it leads to a reduction in environmental pollution caused by the undesirable waste materials. As some typical examples of secondary resources in the Indian scenario, mention can be made of spent catalysts, metal/alloy scrap, ash, consumed batteries, flue dust, slag, sludge and slime, pickling solutions, spent acids, plating rinse solutions, spent etchants, waste water from synthetic fibre manufacture and from tanneries etc .. These wastes constitute a source of a variety of non ferrous metals. In the processing of secondary resources like these, the techniques of hydrometallurgy such as solvent extraction playa pivotal role.This paper outlines the efforts made to use solvent extraction to recover (1) base metals such as copper, zinc, nickel and cobalt from a number of secondary resources like cake, and sludge (2) refractory metals like molybdenum and vanadium from sulphidic byproducts and spent catalyst and (3) nuclear metal like uranium from phosphoric acid. In the case of base metals, process flowsheet involving the use of acidic extractants such as DEHPA and PC88A have been optimised. The problem of iron removal from the leach liquor, which influences the metal recovery process significantly, has drawn a special emphasis. In the case of refractory metals, basic extractants like Alarnine 336 has been pressed into service to produce kilogramme quantities of pure salts of molybdenum and vanadium. Finally, the paper gives a brief account of plant experience in recovering uranium from phosphoric acid, using a solvent system comosed of DEHPA and TOPO."

Jan 1, 1996

By Jun Iwai, Osamu Takai, Yasushi Inoue, Hiroyuki Sugimura

"Infrared reflection absorption measurement was performed during plasma-enhanced chemical vapor deposition of silicon dioxide films at room temperature. Hydrocarbon contaminants adsorbed onto growing film surface are oxidized by oxygen radicals in plasma resulting functional groups which include C=O and C-O bondings. These groups exist only near the surface and are hydrolyzed rapidly after exposure to air.IntroductionRecently low-temperature silicon dioxide (SiO2) deposition has been in a growing industrial demand in pa1ticular, polymelic substrates such as polycarbonate and polyethylene telephthalate, which have poor heat resistance, need low process temperature (near room temperature) in coating of SiO2 which is a suitable material to improve optical and mechanical properties of polymenc products. Plasma enhanced chemical vapor deposition (PECVD) using organosilicon reactants is one of the most promising technique for lowering process temperature, so that it has been extensively studied1-12. In the present; however, hydrocarbon contaminants and a plenty of Si-OH termination in Si-O-Si networks tend to exist in the films, which degrade mechanical, optical and electrical properties of the films. It is necessary to understand the deposition mechanism at, low temperature in order to solve the problems. We have studied the low-temperature PECVD of Si02 by spectroscopic diagnosing techniques such as optical emission and mass analysis6-7, 11- 12Infrared reflection absorption spectroscopy (IR-RAS) has been a well-established technique for characterization of thin films on metals as· well as on semiconductors and insulators13-17. In this paper, we report on' the surface reaction of room-temperature PECVD of Si02by using in situ IR-RAS."

Jan 1, 2000

By Niels Verbaan, Ralph Fitch, Charlotte Forstner, David Dreisinger

A process has been developed to extract gold, silver, indium, gallium, lead, copper, zinc, and other metals from a large resource using an oxidizing acid chloride heap leaching technology. The ore is crushed and/or ground to improve reactivity and then contacted with a solution containing NaCl-HCl-NaOCl. The value metals are leached into solution as chloro-complexes. The leachate is treated in a series of separation and recovery processes to produce separate saleable or disposable products. The paper will provide a summary of process development and application to a silver-indium ore from Bolivia. The possible application of the process to other ore types will be presented for discussion.

Jan 1, 2015

By Moto Goto

Today, Pierce-Smith converters, coupled together with various types of smelting units, are used in most of the world's smelters, However, due to the "batch" processing nature, and problems associated with fugitive emissions during the transfer of melt and blowing stages, this arrangement will unlikely be adopted in future smelters. Modern day alternative processes include the Mitsubishi Process, Outokumpu Flash Smelting and Flash Converting Process, the Noranda Process, and the Ausmelt Process, but only the Mitsubishi Process is a "truly continuous" smelting and converting operation, producing a constant flow of blister without tapping, and is economically proven by long term commercial operations. This paper reviews recent advances in modern continuous converting technologies, with a special section devoted to operation of the "first standalone Mitsubishi C-furnace" coupled together with a Noranda Reactor, at Port Kembla Copper Pty, Ltd. in Australia.

Jan 1, 2003

By I. M. Richardson, M. Janssen, W. Geerstma, I. J. Bennett, V. A. Popovich

Avoiding wafer breakage is a big challenge in the photovoltaic silicon industry, limiting production yield and further price reduction. Special fracture strength tests suitable for thin silicon solar wafers and solar cells, to be used in combination with Weibull statistics, finiteelement (FE) modelling and digital image correlation have been developed in order to study the mechanical stability of solar wafers. The results show that removal of the saw damage significantly increases the strength of crystalline silicon wafers. Furthermore, it was found that silicon crystallinity and the location where the wafer is extracted from the cast Si ingot have a significant effect on the strength, namely samples taken from the bottom of the ingot are 30% stronger than those taken from the top. The study also showed that there is a decrease in fracture strength when an anti-reflective SiNx coating is applied, which is caused by high thermal stresses.

Jan 1, 2015