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By Z. S. Wronski

In rapidly solidified Fe-Nd-B permanent magnet alloys, the content and distribution of Nd-rich intermetallic and Fe-phases determine coercivity Hc and remanence Br. Consequently, microstructure plays a crucial role in deter- mining the (BH) max-product of permanent magnets fabricated from these alloys. A study has been initiated to investigate changes in microstructure and the effects on magnetic properties as the material is processed from arc-melted ingot to melt-spun flakes and finally to a product consolidated by hot-forming. Anisotropic magnetization behaviour has been observed in rapidly solidified flakes after low-temperature annealing.

Jan 1, 1989

By Pradip

The selective adsorption of chemisorbing fatty acids at high temperatures together with the addition of soda ash and lignin sulfonate as depressants is the key to the industrial processing of bastnaesite ores. This paper presents the results of a fundamental investigation that indicate that alkyl hydroxamates can be an alternative collector for the beneficiation of bastnaesite ores that contain barite and calcite as the principal gangue minerals. The primary mechanism for providing sites for the chemisorption of hydroxamate on bastnaesite appears to be through dissolution of cations, formation of the respective hydroxo complexes and readsorption at the interface.

Jan 1, 1989

By M. D. Bishop

Loss of organic solvent extraction circuits occurs through several accepted methods. Losses are commonly attributed to entrainment of the plant organic and evaporative loss of diluent. Evaporative losses of diluent have been estimated using various models or by considering all losses over and above entrainment to be due to evaporation. Other possible loss mechanisms are discussed and data on losses during weather conditions are presented. Accurate estimation of evaporative loss is vitally important to the industry due to both cost factors and environmental concerns. Data for and description of the Diffusive Flux Model are presented as an improved-method of estimating evaporative losses:

Jan 1, 1999

By Christian M. Sagedahl

The stringent environmental regulations for air pollution regarding emission control, along with the need of dry concentrates to feed autogenous smelting processes, are enhancing the development of cleaner technologies. Indirect drying of concentrates by a Kvaemer steam dryer is a technology with promising results, reducing dust entrainment to the exhaust gas stream and leading to smaller dust separation units. The Kvaemer dryers are designed for a very high availability, a high-energy efficiency, low amount and velocity of exhaust gases, no SO2, CO or CO, emissions combined with a wide range of satisfactory operating conditions and low total operational costs.

Jan 1, 1999

By Moo Eob Choi

The reduction of iron oxide particles by hydrogen is one of the most widely investigated gas-solid reactions. The search for new methods for producing iron by the direct reduction of iron oxide has resulted in a large number of exhaustive studies of the various aspects of this reaction. However, previous studies have largely been done with either pellets or lump ores. Little has been published on the hydrogen reduction of very fine concentrate particles smaller than 37 µm (-400 mesh). The kinetics of hydrogen reduction of fine iron oxide concentrates were investigated in the temperature range of 900 - 1300°C.

Jan 1, 2006

By L. H. Lewis

The relationships that link microstructural properties of advanced permanent magnet materials with magnetic properties such as the coercivity are often difficult to quantify, especially in materials with nano-scale structures. Recent work on RE2Fe14B-based powders fabricated with rapid- solidification techniques such as inert gas atomization (IGA) and melt-spinning provide insight into the nanostructural features which affect the acquisition and stability of coercivity. In all cases the coercivity is found to be a function of both the scale of the constituent microstructure and of the presence and distribution of minor phases.

Jan 1, 1997

By Dai Yongnian

"The feasibility to vacuum distillation of a crude metal or an alloy was discussed. The equilibrium relationship between vapor phase and liquid phase in A-B system - - - - - PA/PB =BAa*/b has been derived. The separation coefficient, BA = rAPA/(rBPB) is a judgment criterion. By calculation PA/PB, the equilibrium composition diagram of vapor phase and liquid phase was drawn. By use of the equation derived by M. Olette, the relationship among the volatilization amounts of various impurities in a crude metal (yi) was further solved. 1-(X/100)= C =(1-Y1/100)1/02i . From yi value obtained in practice, 2i, Pi and then can be calcu-lated. The correct volatilization order of various impurities was obtained. These results can be applied to determine the practical conditions (temperture, vacuum degree, type of distilla¬tion furnace, times of distillation and control of product composition) in distillation of a crude metal or an alloy.INTRODUCTIONRefining and separation of various impurities from nonferrous crude metals by vacuum distillation have many the advantages of high metal recovery, impurities recovered in metallic state, flowsheet simplified, good enviromental protection, low operation costs and in complex equipment. So in recent years this method has been adopted widely.Vacuum distillation has also been studied and used in separation of various elements from non-ferrous alloys and the area of its application is being extended rapidly.At this situation, some problems have been put up: What kind of impurities can be removed from crude metals? What kind of alloys can be separated by vacuum distillation? In present paper, attemps have been made to answer these problems and combine with practical results to analyse some valuable data obtained from testwork on vacuum distillation of crude tin and Pb-Sn alloy."

Jan 1, 1988

By Fumio Hashiuchi, Yushiro Hirai, Masatoshi Maeda, Toshihiro Nagata

"Increase in the copper smelting capacity at Saganoseki Smelter & Refinery was attained through various improvements in the PSconverters and the flash furnace. Two of the major innovations in the converting process were: a new operational technology which avoids increase in the copper content in the converter slag even when higher copper grade matte (65%) are treated in the slag making stage and a technology which shortens the operational interruption time which is caused by coolant charging. The latter was realized by introducing a new automated coolant charging system with which it was made possible to charge the coolant without stopping the blowing into the converter. These improvements brought about a remarkable increase in · the production capacity per converter and an annual production of 450,000 tons of copper without adding new furnaces was made possible. In addition, good results have been obtained of the tests with modified tuyeres to further increase the production.IntroductionIn a bid to renovate its Saganoseki Smelter & Refinery and to establish a leading production unit in terms of global competitiveness, Nippon Mining & Metals undertook major restructuring efforts since 1994. One of its themes was the shift from· a two-flash furnaces operation to a single-flash furnace operation. The shift was successfully completed in 1996 while maintaining the production at the same level (330,000 tons per annum of copper). Then, the productivity was enhanced to 450,000 mtpy without adding new furnaces through technological and operational improvements. It is now planned to increase the smelting capacity further to 470,000 mtpy this year.Some technological and operational improvements in the matte converting process and the new plan resulted from the tests with modified tuyeres are presented in this paper."

Jan 1, 2000

By Wilson Acchar, Fernando Barcelos, Luis Carlos Pereira

"Porous ceramics have been extensively investigated as structural materials for flow of fluids in many applications, such as filters for molten metals, water purification and hot gases, thermal protection systems and heat exchangers. This class of material must have two special features: high permeability and mechanical strength. However, these parameters are influenced in different ways by the processing method and the consequent cellular structure. In this work two different types of commercial ceramic filter materials are investigated. Characterization included the evaluation of the strength values as well as the permeability behavior and microstructural analyzes of the surface fracture. The results indicate that the strength values are strong dependent on the filament defects.IntroductionCeramic materials with a cellular structure have been extensively investigated as structural materials for flow of fluids applications [1-3]. Microstructural aspects such as morphology, size of the cell and the degree of interconnectedness are mainly parameters that influence the properties of these porous materials [4-6]. The most used industrial process to produce cellular ceramics for filter application is the polymeric sponge replication method. This technique consists in dipping the polymer foam into slurry containing an appropriate binder and the necessary ceramic materials, followed by a heating treatment [2,5].Mechanical properties of cellular ceramics depend basically on cell size, degree of interconnectedness and density [1,2,5,8,9]. Materials used as filters required a good strength and also permeability values. These properties are inversely proportional to each other. Higher porosity increases permeability values but decreases the strength values [1,2,5]. The objective of this work is to study the strength resistance of a commercial porous ceramic material (10, 20 and 30 ppi) based on silicon carbide."

Jan 1, 2012

By Majid Sarkari, Hossein Atashi, Farhad Fazlollahi

"The aim of this research work was to prepare the efficient catalyst to purify pollutant output gases such as SO2 , NO2 and CO. This catalyst, lanthanum cobaltat (LaCo03) was prepared by the proper method in the analysis laboratory of Tabriz Oil .The first materials were chosen through calcination operation and temperatures of operation related to the Tamman temperature, therefore the basis for the first material of catalyst was nitrate and aqueous and since we had no availability to lanthanum nitrate, lanthanum oxide was used to prepare the nitrate one. Before all else, the first materials of catalyst were mixed together with the equal mole proportions and then, at the lower and upper temperatures of Tanunan temperature, calcination operation was carried out. To determine the molecular structure, the XRD analysis was utilized and specified that prepared lanthanum cobaltat was sixth aqueous and had the crystal structure type Triclinic.IntroductionLaCo03 has presented a vast interest because of its special electrical, magnetic and catalytic properties [1-4]. The catalyst LaCo03 can be prepared by means of several methods such as spray drying, freeze drying and also co-precipitation [5-12]. Some methods including hydrothermal, sol gel and citrate [13] This material usually has been synthesized by ceramic method and certainly the high temperature for the calcination operation. [14]. Lanthanum catalysts have been researched because of having such an active state [15]. One of the unique properties of this catalyst is the simultaneous conversion of pollutant elements. Nowadays CO oxidation has important applications in environment protection, such as indoor air cleaning and automotive exhaust treatment. LaCoO3 is one of the most important catalysts for CO oxidation."

Jan 1, 2013

By Chenhui Liu, Ka-ma Huang, Hong-ying Xia, Bingguo Liu, Hua Chen, Jinhui Peng, Libo Zhang

"The rising popularity of microwave heating in mineral processing has fuelled the need for knowledge concerning dielectric properties of minerals. Dielectric property and microwave absorption property of anthracite were measured over a temperature range of 20-100°C at 2.45GHz by using an open-ended coaxial sensor measurement system. The results show that the dielectric constant, loss factor and loss tangent increase with temperature rising at 2.45GHz. Microwave absorption properties of anthracite are highly dependent on temperature and frequency. At frequency of 2.45GHz frequency used in microwave metallurgy, anthracite is suitable for reducing agent to achieve fast elevation of temperature then returning to original state. The research will be helpful in explaining the thermal running of microwave dielectric heating the anthracite.IntroductionThe application of microwave heating in minerals processing and treatment has recently attracted great interest from the metallurgical industry. Compared with conventional heating methods, the advantages of microwave heating include rapid and selective heating, uniform distribution, high efficiency, fast on and off switching as well as flexible and modular design[l-3]. As a result of these advantages, microwave heating has been applied in a variety of mineral processing and extractive metallurgy, such as microwave-assisted ore grinding, microwave heating for carbothermic reduction and acid leaching of ilmenite ore, microwave drying, microwave-assisted roasting and smelting of sulfide concentrate, microwave-assisted spent carbon regeneration and microwave-assisted waste management [ 4-6]. Though the application of microwave heating in the metallurgical industry is promising, further studies on the interaction between microwave radiation and minerals and its effects are highly desired to develop innovative techniques for minerals processing and ore treatment using microwave heating [7]."

Jan 1, 2013

By Jing Zhan, Chuanfu Zhang, Yonglin Yao

"The Ni/Co arbitrary ratios of fibrous precursor were investigated during coordinated coprecipitation by changing the precipitating medium. The results show that the original molar ratio ofNi2+ to Co2+ in reaction solution can be maintained in the coprecipitate at pH'.'05.0 and the coprecipitate is single phase solid solution using water and water-X precipitating medium. But the original Ni/Co ratios are no longer kept and composition of the coprecipitate is not uniform at pH>5.0 in water precipitation medium. In order to obtain the precursors with the required morphology and accuracy Ni/Co ratios, the optimum conditions of fibrous precursors were chosen as follows: ammonia used as complex agent and pH adjustor, water-X solvent as precipiting medium, oxalate as coprecipitated agent, 8.0-8.4 for pH value, 50-70°C of reaction temperature, 0.5-0.8 mol/L of initial nickel and cobalt salt concentrations and excesses of oxalic acid of 10% - 20%.IntroductionNi-Co alloy as an important transition metal alloy with high mechanical strength, good anti-deformation, corrosion resistance, thermal conductivity, thermal stability, electrical conductivity, electrical contact, and special magnetic properties indicates that it can be used as high-temperature catalyst, special magnetic material, high-temperature electrochemical devices, and so on [1-6]. An ideal composite powder should have an appropriate stoichiometric ratio, good uniformity of chemical composition, appropriate phase, low impurity content and small particle size [7]. Similarly, the composition of nickel-cobalt alloy powder has an important impact on its crystal structure, properties and applications. Guo[8] found that magnetisms of CoxNi1-x such as magnetic anisotropy, curie temperature, and the shifts of the spin steering are very sensitive to the composition of alloy powder."

Jan 1, 2013

By Jun Lu, Min Chen, Wei-jian Su, Jian-zhong Luo, Yu-tao Lei

"In the case of treating phosphatizing wastewater containing zinc, zinc had an impact on the solution chemistry, especially on pH. Fe2(SO4)3 and CaCl2 were used as precipitators to remove phosphate from zincic phosphatizing wastewater and the optimum pH was investigated. Zinc ion had a significant effect on the optimum pH. The optimum pH ranges were 12.10(inlet concentration of 15.67mg/L, outlet concentration of 9.53mg/L), 3.04-5.50(inlet concentration of 11.97mg/L, outlet concentration of 0.44-0.26mg/L), and more than 10.72(inlet concentration of 12.24mg/L, outlet concentration of less than 0.47mg/L) under the conditions without precipitator, with Fe2(SO4)3 and with CaCl2 respectively.Introduction Phosphate coating is commonly used for protective coating of machine elements. Including oil removal by caustic washing, rust removal by acid washing, phosphatization and inactivation, the phosphatization process produces wastewater containing inorganic salt of high concentration, especially the phosphate, beyond the environmental standards and polluting environment seriously. What’s more, the wastewater from zincic phosphatizing technology also contains another pollutant, zinc. At present, Chemical Precipitation (CP) and Biological Nutrient Removal (BNR) are two of most common technologies of phosphate removal. BNR, such as A/O, A2/O and UCT technology, is suited for wastewater containing organ phosphorus of low concentration and CP for wastewater with phosphate of high concentration [1]. Researches on CP treating wastewater containing phosphate of high concentration, mainly focus on adding quantity of precipitators[2-5] and coagulants[2-4] and the choice of technologies[3-9]."

Jan 1, 2008

By Alice Barreto Bevitori, Frederico Muylaert Margem, Noan Tonini SImonassi, Caroline Oliveyra, Sergio Neves Monteiro, Isabela Leão Amaral da Silva

"The mechanical behavior and the fracture characteristics of composites with DGEB/TETA epoxy matrix reinforced with up to 30% in volume of continuous and aligned ramie fibers were evaluated by tensile tests. Specimens with selected thin fibers aligned along the tensile axis were room temperature tested to rupture. The fracture surface was analyzed by scanning electron microscopy. The results showed significant increase in both the ultimate tensile strength and the elastic modulus. The fracture analysis indicated the possible mechanism for the fiber/matrix interaction, which could be responsible for the composite performance.IntroductionSince the middle of last century, polymer composites have substitute many conventional monolithic materials in applications ranging from aerospace to sport [l]. The main advantages of these composites are the low density and flexible properties specially using fiber as reinforcement to suit the mechanical performance requirements [2]. These are usually high strength and stiffuess requirements that could be reached with synthetic fibers such as gloss, carbon and aramid fibers. Its most commonly used example is ""fiberglass"", i.e., a thermoset polymer matrix composite reinforced with glass fiber. Indeed, ""fiberglass"" has a specific strength of the order of 500 MPa.cm3/g, which is the double of the strongest steels like the maraging. This motivated, at earlier times, ""fiberglass"" to replace many conventional materials including wood and natural fiber composites. Today, ""fiberglass"" has a wide range of uses from aerospace systems and appliances to sport and leisure components. However, its fabrication as well as those of any synthetic fiber such as carbon and aramid composites, requires a relatively large amount of energy. Presently, a growing concern exists regarding the consequences to the environmental by gases like C02 associated with both the energy consumption and the processing of synthetic fibers and their composites. These gases are well known responsible for global warming [3]."

Jan 1, 2013

By Nan Zhang, Gai-feng Xue, Shangchao Liu, Benquan Fu

"The high-magnetization microspheres of Fe3O4 encapsulated with S1O2 and T1O2 layers (Fe3O4@SiO2@TiO2) were prepared. The microspheres were characterized by transmission electron microscopy and scanning electron microscopy. These high-magnetization microspheres could be readily dispersed by shaking whereas they could be rapidly separated from the aqueous solution simply by applying an external magnetic field. The two shells of S1O2 and T1O2 protected the iron oxide well and the microspheres were stable in acid and base solutions. Therefore, they have a good potential for the enrichment of phosphopeptides or photocatalytic activity. They could also be used to remove metal ions from waste water.IntroductionSolid-phase extraction (SPE) is the most commonly used separation technique for its simplicity, consumption of small volumes of organic solvent, and the ability to achieve a higher enrichment factor. The quest for new adsorbents is an important factor in improving analytical sensitivity and precision in SPE techniques. To date, many novel adsorbents, such as nanometer-sized materials, carbon nanotubes, mesoporous materials and magnetic nanoparticles have been employed in SPE.Magnetic polymeric microspheres, an interesting advanced composite material, have received increasing attention in the past few decades because of their unique physical and chemical properties and their potential for use in applications in various fields [1]. Magnetic microspheres consisting of an iron oxide core and a silica shell have attracted particular attention for their unique magnetic response, low cytotoxicity, and chemically modifiable surface. The core-shell magnetic silica microspheres have shown great potential in the fields of biotechnology and biomedicine for applications such as cell labeling and separation, enzyme and protein separations, targeted drug delivery, and magnetic ferrofluids hyperthermia."

Jan 1, 2012

By Isabel Lázaro

A detailed study has been undertaken into the electrochemistry of the leaching of chalcopyrite in acidic solutions containing ferric ions. Mixed potential measurements have shown that the maximum potential achievable on a chalcopyrite disk in a ferric sulfate medium lies within the so-called passive or prewave region in the anodic behavior of chalcopyrite. The very low current densities due to the anodic oxidation of chalcopyrite at potentials in the region of the mixed potential has made studies of the initial stages of dissolution difficult. However a careful rotating ring-disk electrode (RRDE) study has enabled data to be obtained for the stoichiometry of the initial dissolution reaction to be obtained. Thus, in addition to the detection of soluble iron and copper as products in this potential region, a soluble sulfur species has also been detected. A comparison of the experimental with the expected collection efficiencies of the products on the ring has revealed that this soluble sulfur species is likely to be thiosulfate. The characteristic transient anodic behaviour of chalcopyrite in this potential region has been interpreted in terms of a rate limiting solid-state diffusion process. Thus, extrapolated rates based on reported measured solid-state diffusion coefficients for the mineral at elevated temperatures have been shown to be consistent with the potentiostatic current-time transients. Furthermore, comparative studies of the anodic characteristics of the copper sulfide minerals covellite and bornite has confirmed their greater reactivity in this potential region. The results of this investigation have been combined with a parallel study of the non-oxidative behaviour of chalcopyrite in order to derive a model for the dissolution process which is consistent with other published studies of the electrochemistry and dissolution of the mineral.

Jan 1, 2003

By Ana E. Bohé, Fabiola J. Alvarez

"The separation of nickel from the aluminum present in spent catalysts and different metallic industrial residues, is proposed in the following systems: alloy Al2Ni and the mixtures 50 wt% Ni + 50 wt% Al, 10 wt% Ni + 90 wt% Al2O3 and 12 wt% NiO + 88 wt% Al2O3. The experiments were carried out in a tubular reactor with a flow of 2 l/h of gaseous chlorine and from 200 ° to 800 °C. The final products of the reaction, extracted from the hottest zones of the reactor where characterized by XRD, SEM, EDS, AA and XRF, as NiCl2 y NiCl2.6H2O while in the coldest regions AlCl3 was deposited in the first two cases and in the other there was a residue of ?, a- Al2O3, sometimes mixed with some remainder of Ni and NiO. The procedure attained different separation factors which showed the optimun conditions for the recovery of both metals. Introduction Some studies of nickel corrosion were carried out in chlorine gas at temperatures above 950ºC, and suggested that nickel is not corroded below 538ºC. [1] However, in a previous work it was shown that the chlorination allows the separation of nickel from aluminum and the formation of NiCl2 was detected from 200ºC in binary mixtures Ni-Al 50 wt%, for isothermal conditions in chlorine flux. [2] Other researchers obtained selective chlorination above 650ºC of a fly ash containing 1.4 wt% of Ni and other metals (V, Mg, Al and Fe). The Ni was separated from the Mg and NiCl2 started to vaporize at 550ºC and was after condensed in a zone of the reactor above 380ºC with 90% of purity. [3]"

Jan 1, 2008

By Hong Liang-shi

Olivine lithium iron phosphate (LiFePO4) is considered as one of the most promising materials for lithium-ion secondary batteries because of its high theoretical capacity, low cost, good safety, benign environment and good cycle performance. In this paper, carbon-free and/or carbon-coated olivine lithium iron phosphate composite ultrafine powders were successfully synthesized from aqueous precursor solutions of (NH4)2Fe(SO4)2?6H2O, H3PO4 and LiOH?H2O by co-precipitation method. The obtained LiFePO4 or LiFePO4/C powders were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Their electrochemical performance was investigated in terms of cycling behavior. As confirmed by X-ray diffraction and scanning electron microscope, the material obtained by co-precipitation within the temperature range of 60ºC to 100ºC and then followed by moderate heat treatment are a single-phase olivine LiFePO4with the particle size of about 300nm. An improved carbon-coated olivine LiFePO4/C material was prepared by adding conductive carbon materials, such as glucose, activated carbon and acetylene black, into the precursor. The carbon dispersed in the materials increases the electronic conductivity of LiFePO4/C composite, and consequently, leads to high rechargeable capacity of the material. The carbon-coated material with carbon amount of 7.64%wt obtained from glucose has the first discharge capacity of 150.3mAh/g at the rate of 0.1C and 129.3mAh/g at the rate of 1.0C, respectively. After cycled for 50 times, the capacity retention rate is 95.13% at the rate of 1.0C in the voltage range of 2.5 to 4.3 V vs. Li/Li+.

Jan 1, 2006

By Billy W. Osborne

The use or primary dross as a source for aluminum ion in the manufacture of aluminum sulfate offers opportunities for an inexpensive raw material. The aluminum sulfate industry in the US is a mature market with numerous small plants operating close to major users. The majority of manufacturers use either bauxite or aluminum oxide trihydrate as a source for the alum¬inum ion.. However, using process technology developed and patented by IWC, the oxides are removed from primary dross for use in manufacturing aluminum sulfate prior to metal recovery. This process offers the benefit of reducing costs for metal recovery. This paper discusses some of the methodology used in this process.

Jan 1, 1995

By T. Shibasaki

Purification of copper electrolyte at Naoshima is carried out by two stage liberation to completely depress copper and impurity ions followed by concentration of the solution to produce crude nikel sulfate as by-product. A new nickel recovering process has been developed and pilot tested recently. It consists of the following process steps.; neutralization of spent electrolyte from liberation section to remove free acid and most part of remaining impurity ions, refining and nickel concentration by solvent extraction, and crystallization of pure nickel sulfate from concentrated strip solution. This paper describes the results of laboratory and pilot plant tests, then briefly discusses feasibility of the proposed process.

Jan 1, 1987