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By Tsunehisa Nishimura

Stable operation of the blast furnace needs adequate control of the lower part. To clarify the behavior of the lower part of the blast furnace with accurate consideration of the property of slag and its flow characteristic, a new mathematical model has been developed. Using this model, the effects of the change of operational conditions on the behavior of the lower part of the blast furnace were studied. Further, means to control of the lower part of the blast furnace, especially effective means to maintain adequate temperature, were discussed. And desirable slag property and composition, especially the method to control FeO concentration dripping from the bottom of the cohesive zone to avoid a decrease in temperature of the lower part of the blast furnace was estimated.

Jan 1, 2006

By Run-bo Wang, Zhe Wang, Fan-yi Meng, Jian-Liang Zhang

The influence of semicharcoal substitution for coke breeze on sintering performance was investigated by pot-grate sintering test. At a fixed fuel ratio, sinter productivity and strength decreased with the substitution increasing from 0 to 100% due to better combustibility. To enhance the utilization efficiency of 100% semicharcoal, sintering parameters (moisture and suction pressure) was adjusted. With the moisture increasing, sinter performance of 100% semicharcoal increased because of the suppression of semicharcoal incomplete combustion. As the moisture further increasing to 9.0%, sinter quality gave rise to a decrease trend. The results also showed that the increase of suction pressure was benefit for the increase of heat transfer rate, leading to the improvement of heat utilization energy. Measures to enhance magnetite oxidation during sintering are discussed based on current understanding of the fundamentals that control the sintering process.

Jan 1, 2015

By G. A. Bala

As part of ongoing research to define mechanisms of microbial enhanced oil recovery (MEOR), this work describes the activity of Bacillus l1chen1formis JF-2 (ATCC 39307) Mosurfactant against crude oils with varying compositions. Surfactant based MEOR improves oil recovery by lowering the oil/brine interfactal tension (IFT) therefore permitting oil to be displaced or solub1lized into the aqueous phase.? MEOR is an Enhanced Oil Recovery (EOR) process which allows for the introduction of chemical and miscible fluids, in the form of microbial metabolic end-products, through the injection of microorganisms into the reservoir or stimulation of indigenous reservoir microbial populations. These microorganisms represent a replenishable in situ source of acid, gas, biopolymer, solvent, or surfactant products which can be. supported and manipulated by the addition of simple and inexpensive nutrients to enhance the recovery of oil. Microbially mediated surfactant production represents one mechanism of MEOR. Bacillus licheniformis JF-2. has been used in a mode 1 MEOR system based on Berea sandstone cores (permeabilly .85 to 400 md) to examine surfactant based MEOR of medium to heavy crude oils (API gravity 38.1° to 17.5°). Enhanced oil recovery was achieved with all oils tested using either cell free culture supernatants or microbial suspensions as injectants with no detrimental effect to the oil. Spatial distribution of cells following mf?crobtal flooding was analyzed with scanning electron microscopy. Data indkate complete distribution of cells with a predominance of organisms located distal to the point of injection. There appears to be no sign:if1cant recovery trend with respect to oil composition.. The biosurfactant produced by Bacillus lichen1form1s JF-2 lowers the interfacial tension of all oils tested equally well.

Jan 1, 1991

By N. Pradhan, B. K. Mishra, B. D. Nayak, B. K. Mohapatra, R. K. Mohapatra

"Present study is about use of a group of Iron[Fe(III)] Reducing Bacteria (IRB) to convert the goethite (a-FeOOH) present in the original lateritic Nickel ore to magnetite under an anaerobic condition and subsequently release the bound Co(III) and Ni(II) through leaching. The lateritic Nickel ore contains 0.8% Ni, 0.049% Co, 1.92% Cr, 0.32% Mn and 50.2% Fe. An anaerobic dissimilatory Fe(III) reducing bacterial consortium capable of using acetate as carbon source (electron donor) and lateritic ore as terminal electron acceptor, changes the initial light brown color of the ore to dark brown. The change in color is due to the conversion of goethite to magnetite, which was confirmed by XRD. When the IRB treated sample was subjected to both bioleaching and acid leaching, it shows a greater recovery of Nickel and Cobalt values as compared to untreated original lateritic Ni ore. Further a magnetic separation method was used to separate the magnetic part of the treated lateritic ore and subjected to acid- and bio-leaching for better recovery of Nickel and Cobalt.IntroductionIt has been known that micro-organisms have the potential to reduce metals but more recent observations have shown that a diversity of specialist bacteria and archaea can use such activities to conserve energy for growth under anaerobic conditions [12]. Natural Fe(III) oxides are high in surface area and are reactive [1]. Fe (III) oxides adsorb a wide range of metal cations and anions by complexation to surface hydroxyl groups [17], and function as the primary redox buffering solid phase in many sediments and subsurface materials [5].Recently a number of bacteria have been isolated based on their ability to use metal ions, including Fe(III), as electron acceptor under anaerobic conditions. These are capable of producing energy by coupling the oxidation of organic compounds to reduction of Fe(III). Iron[Fe(III)]-Reducing Bacteria (IRB) have been isolated and identified from a wide variety of environments including freshwater and marine aquatic sediments and submerged soil [8]. The biogeochemical cycle of iron is linked to those of the trace metals, as many trace metals coassociate with Fe(III) oxides or reduced iron phases (e.g., magnetite, siderite, or iron sulfide). IRB can utilize Fe(III) oxides as terminal electron acceptors for respiration [18]; thereby reducing all or a fraction of the solid. The reductive portion of the iron biogeochemical cycle in non-phototropic environments (e.g., sediments and subsurface materials) is driven by the direct enzymatic reduction of Fe(III) oxides to Fe(II) by dissimilatory iron reducing bacteria [13,14]."

Jan 1, 2009

By Florian Kongoli

New operating conditions and process parameters are often necessary in today's industrial practice of non-ferrous smelting and converting in order to accommodate various new chemical compositions of mineral charges and environmental requirements or to conceive new and more efficient industrial technologies. An important parameter in non-ferrous smelting and converting is the liquidus surface of multicomponent slags. This surface is affected by multiple factors such as temperature, gaseous potentials, the content of each component in the slag, etc., and cannot be quantified by the existing ternary liquidus diagrams. In this work a new type of representation of the liquidus surface of multi component systems has been presented by means of a thermodynamic model. This representation waives the need of the multidimensional representation of multi component systems and yields practical two-dimensional diagrams, which can be easily used in the industrial practice.

Jan 1, 2000

By Zhihao Yue, Honglie Shen, Yahui Teng, Ye Jiang

"In this paper, manganous nitrate [Mn(NO3)z] was used to assist the etching of silicon wafer in hydrofluoric acid (HF) for the antireflective application, and alumina (Al2O3) layer was deposited on the surface of the etched sample by atomic layer deposition method for further antireflection. The surface morphological and compositional studies of these samples were performed by scanning electron microscopy attached with an energy-dispersive X-ray spectrometer. The surface reflectance measurements were carried out using UV-Vis-NIR spectrophotometer. Binary structures of pyramids and nanopores were obtained by etching the alkaline textured monocrystalline silicon wafer in HF and Mn(NO3)z mixed solution for not more than 15 min. But excessive increase of etching time of up to 30 min resulted in the whole destruction of pyramids. The average reflectances of the 5-min-etched sample before and after being coated with 75-nm-thick Al2O3 layer are 4.62% and 3.47% in the range of 200-1000 nm, respectively.1. IntroductionAs we know, the reflectance of silicon wafer after being sliced is so high that the maximal photoelectric conversion efficiency of silicon based solar cells is limited. Therefore, alkaline texturization process was used for silicon solar cell in industrial production. But the reflectance of this alkaline textured wafer is still greater than 10% and this process can only be used for monocrystalline silicon solar cell."

Jan 1, 2013

By K. Morsi

Carbon nanotube (CNT) reinforced metallic composites have been recently generating significant scientific interest, due to their expected superior properties compared with other composites. Out of the metallic matrices investigated for reinforcement with CNTs, aluminum has received considerable attention. A major problem has been the dispersion of CNTs in metallic matrices. This paper discusses preliminary results on the mechanical dispersion of CNTs in aluminum powder, powder processing, stability and characterization of aluminum dispersed with CNTs at reinforcement levels equal to and below 5 wt.%.

Jan 1, 2009

By I. Gaballah

High and low grade concentrates of tantalum and niobium oxides were obtained by leaching a medium grade tin slag. Chlorination and carbochlorinalion of these concentrates were studied between 200 and 1000 "C. Chlorination or carbochlorination of the low grade concentrate led, at 1000 OC, to the extraction of about 95 % of the tantalum and niobium oxides. However, the tantalum and niobium chlorinated compounds were contaminated by iron and manganese chlorides. Complete extraction of the niobium and tantalum pentoxide was achieved during the carbochlorination of the high grade concentrate at 300 and 500 "C, respectively. While chlorination of this concentrate at 1000 "C, allowed to the volatilization of about 60 and 80 % of Ta205 and Nb205. In both cases, condensates were composed of almost pure tantalum and niobium chlorinated compounds. The results demonstrate the advantages of the lixivialion based on the "pseudo- structure" of the raw tin slag to obtain the high grade concentrate. The conclusions of this work suggest that the carbochlorination of the high grade concentrate is an efficient process for the extraction of refractory elements from tin slag.

Jan 1, 1993

By Guillermo Rios, Arbizum Cristina, Joa Viflals, Alba Sunyer

"Atlantic Copper is one of the largest copper producers in Europe. Its production facilities are located in Huelva (Spain) and account for the smelting of over one million tpy of concentrates to produce up to 260 ktpy cathodes and 900 ktpy of sulphuric acid. During copper concentrate smelting, the slag coming from the flash furnace and PS converters are treated in an electrical slag cleaning furnace. As a result of the treatment of the off gases from this furnace, approximately 2,000 tpy of a Zn-rich filter cake are produced and are sent to authorized waste managers. This paper describes the characterization of this material and the preliminary results of a new process to recover zinc as a pure zinc hydroxycarbonate while lead is collected as an indium-rich anglesite product. The behavior of impurities (Cd, As, Tl, Sn, Sb, Bi, Cu, Se, Te) in the leaching, solution purification and precipitation steps is also reported.IntroductionThe Atlantic Copper Metallurgical Complex in Huelva (Spain) was commissioned in 1970 with a capacity of 40,000 tpy of copper from concentrate. In 1975, the old blast furnaces were replaced by Outokumpu flash smelting furnace (FSF) technology, and the copper refinery capacity was increased to 108,000 tpy. Between 1994 and 1996, an expansion project was carried out to increase the copper from concentrate and cathodes to 250,000 tpy and 215,000 tpy, respectively. This expansion basically consisted of a new sulphuric acid plant, replacement of the anode furnaces by two 400 t units, redesign of the slag cleaning furnace (SCF), an increase in the electrolytic cells to 1,120 and implementation of ISA permanent cathode technology. Furthermore, a debottlenecking project has led to a capacity of 1,000,000 tpy of fresh concentrate since 1997. Meanwhile between 1995 and 1998, a cathode production rate of 260,000 tpy was reached as a result of a progressive increase in the current density in the refinery."

Jan 1, 2012

By John A. Gisby

Phase equilibria for multi-component systems can be calculated reliably from critically assessed thermodynamic data for sub-systems using software packages like MTDATA, developed by the National Physical Laboratory, UK (NPL). Models and data resulting from an ongoing Mineral Industry Research Organisation (MIRO) project make such calculations possible for the complex systems encountered during sulphide smelting, involving interactions between matte, slag, metal, and gas phases. Predictive calculations can be made that are directly relevant to industrial processes, covering composition and temperature ranges beyond the scope of hard- copy phase diagram compilations, allowing the feasibility of more economic and environmentally sound routes to be explored, better choice of materials to be made, and pilot plant studies to ,be directed more efficiently. Current applications include the selection of suitable fluxing practices in copper and nickel smelting, analysing the operation of the Kennecott copper smelter, optimising the recovery of precious metals and investigating refractory wear.

Jan 1, 2002

By Sang Han Son

The vapor pressures of FeCI2 and ZnC12 in the FeCl2-ZnCl2 system were measured by the transpiration method at 873K and 917K. The vapor pressure data were interpreted to indicate the formation of complex ions in the FeCl2-ZnCl2 melts. It is presumed that the complex molecule FeZnCl4 as well as FeCI2 and ZnCI2 exists in the vapors in equilibrium with molten FeCl2-ZnCl2 mixtures. The activities in the FeCl2-ZnCI2 system are shown a negative deviation from Raoult's law. These results suggest the formation of complex ions such as ZnCl42- in molten FeCI2-ZnCI2 mixtures.

Jan 1, 2003

By Youn-Bae Kang

Evaporation mechanism of S from liquid Fe–C–S alloys at 1873 K was proposed by analyzing available experimental data. It has been known that increasing C content in liquid alloy increases activity coefficient of S ðfSÞ, and it could raise driving force for the evaporation reaction S = S(g). However, experimental data of the evaporation of S in the Fe–C–S alloys could not be accounted for only by considering the increases of fS. In the present study, formation of carbosulfides, CS(g) and CS2(g), was additionally taken into account in order to explain role of C for the accelerated S evaporation. Surface adsorption of S was also taken into account, which retards the evaporation rate of S. An evaporation model equation was formulated. It can be applied to calculate the evaporation rate of S over wider C content (from zero to its saturation to liquid alloy).

By Rodney L. LeRoy, Michel G. Drouet, Peter G. Tsantrizos

"DROSRITE is a unique process that makes possible economic in-plant recovery of metal from hot aluminum dross. It is environmentally friendly, requiring no salt and producing no C02 or NOx gases. The salt-free residues of the process are suitable for production of calcium aluminate or for other value-added use. The process is highly energy efficient, extracting process heat from energy in the residue and, thus, it does not require an external plasma torch, electric arc or fuel heat source.A DROSRITE pilot unit built by PyroGenesis has been tested with both black and white dross types. The unit was installed at two different aluminum plant locations, and tests were conducted for a total of six weeks ""online"" with hot metal holding furnaces where the dross was skimmed.Results of both of these industrial trials are presented, together with an economic analysis indicating cost savings in excess of $1 70 per ton of dross treated."

Jan 1, 2000

By Tracy Morris, Weldon Read, Luis Navarro

"During the leaching of anodic slimes, tellurium dissolves into the leach liquor together with copper and must be removed before the solution is sent to liberator cells for copper recovery. Prior to the installation of autoclaves, tellurium was precipitated using raw slimes that caused a recirculation of tellurium in the leaching circuit. After autoclaves were installed the old leach tanks were converted into tellurium reactors utilizing copper chips, steam and agitation to form a copper telluride precipitate. Tellurium levels of less than 10 rng/L are achieved in a timely manner.IntroductionThe electrolytic refining of copper consists of an electrolytic cell provided with an anode of impure copper, a cathode of substantially pure copper (starter sheet) and an electrolyte made of copper sulfate and sulfuric acid [1]. When a direct electrical current is passed between the anode and cathode inside the cell, the impure copper anode dissolves in the electrolyte and pure copper is plated onto the cathode. During this operation, many of the impurities are deposited on the bottom of the cell as an anodic slime residue composed of insoluble chemical compounds. Slimes are a major source of rare and precious metals in the copper industry [2-5],In the Amarillo Copper Refinery (ACR), the anodic copper slimes are sent to the Precious Metals department in order to extract and then refine the gold, silver, platinum and palladium from them. The remaining impurities, in the form of a soda slag or copper slag are sent to the Hayden smelter for further processing. Copper telluride is sent to the Selenium/Tellurium department inside the plant for selenium and tellurium recovery. During the leaching process of the anodic slimes, copper, tellurium, and other metal species in the slimes are dissolved into leach liquor that cannot be returned to the tankhouse unless the tellurium concentration is below 10 mg/L."

Jan 1, 2012

By Ejike Emmanuel, Nwoye Chukwuka, Ogwuegbu Martin, Asuwaji Ayuk, Onyedika Gerald

"Microwave pre-treatment of cassiterite ore prior to leaching was carried out in an attempt to obtain high grade of Sn02 and to conserve the total energy expended during processing. Microwave treatment was selected due to the presence of associated minerals which behaves differently to microwave energy. Studies in this work showed that microwave pretreatment of cassiterite ore can be applied to increase the recovery of tin oxide within 5 minutes of leaching. Microwave treatment of the ore resulted in mineral liberation at all particle sizes. Tin oxide was separated from the major impurities via leaching in potassium hydroxide solution and precipitation, resulting in 98% Sn02 at pH 7.IntroductionIn the nineties, the available techniques used for ore processing and analysis in Nigeria was the solution methods of either alkaline fusion or acid digestion [1,2]. A process in which cassiterite is made acid soluble by reduction to SnO2 , which stabilizes by glass formation and the tin was extracted by leaching the glass with sulphuric acid, followed by electrowinning was reported [3,4]. In another study, Baba et al [5] studied the dissolution kinetics of a Nigerian casiterite ore in hydrochloric acid solution. The effects of acid concentration,temperature, particle size and stirring speed were examined. It was found that the dissolution rates of cassiterite depends on hydrogen ion concentration, H+, stirring speed and ore particle dimensions. These were believed to report low data due to incomplete solubilization of the ore minerals in aqeous medium [6]. Analytical chemists have used microwave heating devices routinely for the dissolution of metals, minerals and various chemical products in chemical analysis [7,8]. It offers faster heating rate and consequently faster dissolution rate than conventional heating. The principle of the dissolution of analytical samples has been applied to the leaching of various minerals contained in an ore or concentrate sample. Some researchers [9, 10] conducted microwave assisted leaching of laterite ores containing oxides of nickel, cobalt, and iron. The metals of these mineral components were converted into their chlorides by microwave heating (1200 W, 2450 MHz, Nz atmosphere) a mixture of the ore and ammonium chloride between l 77°C and 312° C for 4-5 min, followed by water leaching at 80° C for 30 min. Nickel and cobalt extractions were 70% and 85%, and respectively, and are comparable with roasting at 300°C in a conventional rotary kiln for 2 hours."

Jan 1, 2013

By T. T. Chen

Copper anodes generated from copper scrap are relatively rich in Sn, Zn and Fe. Because of the presence of oxygen, only trace amounts of Sn occur in solid solution in the copper crystals. Thus, Sn occurs mainly as SnO2, Cu-Sn-Ni oxide and Sn-Ni-Zn oxide in the copper anodes, and Zn and Fe occur mainly as minor constituents in the Sn-Ni-Zn oxide and Cu-Sn-Ni oxide. During electrorefining, these oxide species are liberated from the copper anodes and report directly to the anode slimes. The trace amounts of Sn present in solid solution in the copper crystals dissolve but reprecipitate as Sn arsenate or a Sb-As-Sn-O phase. Accordingly, high Sn contents in copper anodes do not lead to elevated Sn concentrations in the electrolyte.

Jan 1, 2010

By Rajashekhar Marti, York R. Smith

Lithium is anticipated to be a key, strategic material in the clean technology economy. The majority of lithium reserves are contained in continental brines and sea water (>60%). Currently the most economical approach to recover lithium from such resources is through selective adsorption. Spinel type lithium manganese oxide and lithium titanium oxide have demonstrated to be excellent candidate materials (after de-lithiation). However, due to the small size of the powders, they have limited industrial application and require immobilization. In this work, we examine the application of novel manganese oxide nanowire composites for the extraction of lithium from dilute solutions. Manganese oxide nanowires were synthesized and simultaneously immobilized on diatomaceous earth via hydrothermal method. Lithium manganese oxide were then formed by solid-state reaction, de-lithiated and tested for lithium ion adsorption.

Mar 1, 2018

By M. T. Baquera

A comparison of microstructures associated with W single-crystal ([001], [011], [111]) rods prior to deformation (as grown), and after quasi-static compression (at a strain rate of ~1/s) by transmission electron microscopy (TEM) shows several orders of magnitude difference in dislocation density. Dislocation substructures were not significantly different amongst the deformed sample orientations. In contrast, [001] W rods penetrated into steel targets, at impact velocities of ~1.3 km/s, exhibited heavy dislocation densities and dynamic recrystallization as very distinct microstructural regimes accommodating the penetration process. Twinning on {112} also occurred as a precursor to, or remnant of, these microstructures near the projectile head. These results suggest that deformation accommodating the extreme strains and strain rates associated with the penetration of a single-crystal rod into a metal target is not adequately represented by conventional deformation

Jan 1, 2006

By M. J. Collins

A hydrometallurgical process has been tested at the Sherritt Research Centre for separation of zinc, lead, copper and precious metal values from the zinc oxide fume leach residue stockpiled at the HBM&S operations in Flin Flon, Manitoba. Zinc is found primarily as zinc femte and sphalerite in the residue, lead as lead sulphate and jarosite, and copper as sulphide and jarositic compounds. Gypsum and siliceous gangue are significant diluents. The separation process includes hot acid, atmospheric and reducing (sulphur dioxide) leaching; zinc, copper and lead flotation; and atmospheric iron removal steps. Zinc is recovered to a high strength zinc sulphate solution and to a zinc sulphide concentrate suitable for feed to a roaster or to a zinc pressure leach plant; lead to a high grade lead sulphate concentrate suitable for feed to a lead smelter, and copper to a high grade copper sulphide concentrate suitable for feed to a copper smelter. Precious metals are divided between the zinc, lead and copper concentrates.

Jan 1, 1993

By Hiroshi Hashimoto

For the application of sodium carbonate slag treatment to product high purity copper on an industrial scale, the counter-flow batch process that reduces the amount of utilized slag is proposed from the viewpoint of the post-treatment of slag. Based on the distribution ratios of several impurities between the slag and molten copper determined previously, the effectiveness of this process is discussed using a mathematical model and confirmed experimentally. According to the model, the slag consumption to remove Sb to a required level in case of the counter-flow batch process with 3 reactors is calculated to be around 30 % of that in the case of an ordinary batch process, where pure sodium carbonate is used as a slag at every stage.

Jan 1, 2003