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By Manis Kumar Jha

Leaching studies were carried out for the recovery/ recycling of metals from PCBs containing 17.05% Cu, 0.74% Ni, 1.74% Fe, 4.35% Pb and 8.32% Sn using various acids such as H2SO4, HCl and HNO3. While sulfuric acid was not a suitable leachant for the dissolution of metals from PCBs, hydrochloric acid selectively dissolved tin. The nitric acid was found to be effective lixiviant with the recovery of 99.99% Cu, Fe, Ni and 36.7% Pb in 6M HNO3 at S/L ratio of 100 g/L and 90oC. The kinetic studies carried out with 2M and 4M HNO3 at 90oC showed ?Ash diffusion control dense constant size-spherical particles? model.

Jan 1, 2010

By Edwin Adoyi Ali, Zainab Shehu Aliyu, Adele Dzikwi Garkida, Muhammad Dauda

Feldspar from Matari, Nigeria was analyzed using SEM, XRD and XRF techniques for microstructural analysis, mineral phase analysis and chemical composition analysis respectively. Qualitative and quantitative XRD analyses revealed the presence of microcline 59.6%, albite 34.7% and quartz 5.71%. The XRF results showed that the feldspar contains 67.32% SiO2, 17.54% Al2O3, 11.33% K2O, 2.75% Na2O, 0.12% CaO, 0.01% MgO, 0.02% MnO2, 0.10% Fe2O3, 0.00% Ti2O, etc and 0.14% LOI. SEM/EDX analysis shows the presence of microcline feldspar as the dominant phase, exhibiting lamellar twinning. The XRD has also revealed that potash has the highest peak, indicating its high concentration. The 0.10% Fe2O3 present is within the permissible level (0.1-0.3%) for glass making and also within the potash feldspar specifications (0.17%). The Matari feldspar is a microcline type, rich in potash, alumina and silica, enabling it meet the standard specifications for alumino-silicate glass.

Jan 1, 2015

By René Winand

The paper gives a synthesis of research work performed in the department during the last ten years and dealing with cobalt , copper and manganese electrodeposition in chloride aqueous solutions. Special emphasis is given to electrocrystallization. For copper, properties of the electrolyte such as solubility limits, electrical conductivity and complex ions stability are discussed in connection with leaching, purification of the electrolyte, and metal recovery. When possible, kinetic parameters and probable electrode mechanisms are given. Problems that are still to be solved are also listed.

Jan 1, 1985

By A. M. T. S. Bandara

The solubility of rare earth (RE) salts in aqueous solutions depends on many factors including the type of cations and anions in solution, their concentrations, temperature and the type of solid precipitated. Experiments were conducted using anhydrous La2(SO4)3 and Ce2(SO4)3⋅8H2O as solids and lanthanum(III) perchlorate prepared by dissolving La2O3 in HClO4 solutions as RE-sources. Solutions of H2SO4, H3PO4 and their mixtures in the presence or absence of Na+, Ca2+, Fe(III) or Al(III) as perchlorates served as test solutions. Saturated solutions and precipitated solids were assayed and characterized using standard techniques to show that the La(III) and Ce(III) ions precipitate as hydrated sulphates, phosphates or double salts with sodium, depending upon the solution composition. The change in solubility of RE-salts with solution composition and temperature is the result of the composite effect of changes in solubility products (pKSP) of salts, pKa of acids and other equilibrium constants for ion-association.

By Zhang Libo, Wang Xin, Peng Jin-hui, Ju Shaohua, Guo Sheng-hui, Xu Lei, Huang Meng-yang

"China is lacking high grade titanium ores. This work intends to leach impurities such as Fe, Ca and Mg from a low grade titanium ore, to increase the grade. The original material contained 65% TiO2 , 16.12% Fe, 9.4% CaO + MgO, 4.2% SiO2, 1.25% A12O3, and the particle size is between 0.053-0.045mm. Microwave energy was used to enhance the leaching effect. The results showed that when normal heating was used to leach the mineral, the extraction of impurities Fe, Ca and Mg was very low. However, when microwave energy is introduced, the extraction of Fe, Ca and Mg increased dramatically. The optimized conditions are: relative power 5W/g, the ratio of concentrate to HC1 isl5%, leaching at 160°C for 20 min with a ratio of liquid to solid 12:1 mL/g. The material obtained under these conditions contains 92.73% TiO2, 0.207% Ca + Mg, 0.8% Fe, with 94.6% Ti recovery. The poduct meets with the quality for boiling chlorine.IntroductionThe resources of titanium are very abundant, and are distributed all over the world. There are almost 140 minerals containing TiO2 with a content of more than 1%. However, there are only several minerals which can be used for producing sponge titanium. They are mainly rutile and ilmenite. The grade of nature rutile concentrates is higher than 95% TiO2, and it is a high quality raw material. But the resources of nature rutile are relatively low; after mining for many years, its resources are exhausting gradually. Although ilmenite reserves are great, ilmenite cannot be used as a raw material because of its low content of TiO2, only 45-70%; also it has a high impurity content of Ca, Mg and Fe. In these years, there is a tendency for titanium industry to use high grade concentrate."

Jan 1, 2012

By Milton Blander

A review of concepts and theories for predicting thermodynamic solution properties of multi- component high temperature liquid solutions is reviewed. During the last 50 years the ability to predict :such properties for molten salts, silicates and metals based on the generally known properties of the lower order (often binary) systems has been developed and shown to provide predictions which are quite useful in science and technology. There are many gaps in our understanding of these high temperature solutions, especially for metals, and considerably more work is needed.

Jan 1, 1996

By Marcio B. Fonseca

Nickel-cobalt laterite deposits have become the focus of attention for hydrometallurgical processing. Following the lessons of the second generation high pressure acid leach (HPAL) projects in Western Australia other Ni-Co laterite projects are now evaluating potential HPAL projects with a rigorous integrated approach that begins with geological modeling, resource estimation and metallurgical studies. The Vermelho nickel-cobalt laterite deposit has been under exploration and study for several years with investigations of various metallurgical processes. Recent HPAL studies have indicated that the nickel and cobalt laterite at this deposit is amenable to upgrading by silica rejection followed by pressure leaching. These studies have required a detailed geological investigation to generate a new resource model. The recent development of a sophisticated geological model integrated with a multi-element resource estimation for this complex tropical nickel laterite deposit in northern Brazil provides an example of the contribution of geology at the critical project stage where process technology decisions are made on relatively small samples of the total resource.\ Keywords: Ni Laterite, Geological Modeling, Resource Estimation

Jan 1, 2004

By Pertti Koukkari, Nagendra Tripathi, Karri Penttilä, Justin Salminen

A computational fluid dynamic model for a novel flash ironmaking process based on the direct gaseous reduction of iron oxide concentrates is presented. The model solves the threedimensional governing equations including both gas-phase and gas-solid reaction kinetics. The turbulence-chemistry interaction in the gas-phase is modeled by the eddy dissipation concept incorporating chemical kinetics. The particle cloud model is used to track the particle phase in a Lagrangian framework. A nucleation and growth kinetics rate expression is adopted to calculate the reduction rate of magnetite concentrate particles. Benchmark experiments reported in the literature for a nonreacting swirling gas jet and a nonpremixed hydrogen jet flame were simulated for validation. The model predictions showed good agreement with measurements in terms of gas velocity, gas temperature and species concentrations. The relevance of the computational model for the analysis of a bench reactor operation and the design of an industrialpilot plant is discussed.

Jan 1, 2014

By Biswadeep Saha, Meenakshisundaram Ramanathan, Chai Ren, Sivaraman Guruswamy

"Fe-Ga alloys have a large low-field magnetostriction and these alloys are attractive candidates in energy conversion and harvesting applications. Small additions of W also increase the magnetostriction of Fe. In this paper changes in magnetostriction by W substitution for Ga in various Fe-x at.% Ga alloys are presented. Fe-Ga-W single crystals were grown using vertical Bridgman Growth technique. [001]-orientated single crystal samples were prepared with faces within 1 degree off <100> orientation. The samples were annealed at 1150 °C in the alpha-phase region and water quenched. The magnetostriction coefficient (3/2)A-100 measurements were made on these Fe-Ga-W single crystals. The result on the effects of W substitution and annealing on the magnetostrictive behavior of these alloys are discussed.*Support of this work by NSF-DMR under the award DMR-0854166 is gratefully acknowledged.IntroductionMagnetostrictive materials changes their dimension exhibit reversible strains and changes in elastic properties in the presence of an applied magnetic field or the reciprocal effect of changes in the magnetic properties with the application of stress [IJ and are very important in sensor, actuator device, linear motor, magnetomechanical devices, microelectro- mechanical devices, active vibration dampening devices application areas. The discovery of an order of magnitude enhancement in the magnetostriction of Fe with Ga addition coupled with low saturation magnetic fields, and excellent mechanical properties opened up the possibility of obtaining larger magnetostriction values in other low-cost ductile a-Fe phase based alloys with alloying additives that are less expensive than rareearths such as Tb and Dy [2·4l_ The magnetostriction values observed in Fe-Ga single crystals are sensitive to thermal history and composition. The formation of second short range ordering phases and local defects inside crystal structure can also cause a dramatic change to this alloy's magnetostriction behavior [5-9l_"

Jan 1, 2012

By Józef Czemecki

Polish copper concentrates are characterized by high levels of impurities, particularly Pb and As. Two technologies are being used for copper concentrate smelting at KGHM Polska Meidz S.A., namely the shaft furnace process (Legnica Copper Smelter, Glogów I Copper Smelter) and a single-stage process for direct to blister concentrate smelting in a flash furnace (Glogów II Copper Smelter). Both technologies are used at different physical and chemical conditions which results, in different impurities behavior. The paper presents flow sheets for copper production in a plant using the shaft furnace process and in another in which a single stage flash process is used. The metals distribution in particular semi-products is given as well as a method for elimination of impurities from the copper production cycle. Methods are also discussed for alloy and matte converting and copper refining to obtain low Pb and As concentrations in anode copper (0.3% Pb and 1500 ppm As maximum) that are being used in the KGHM Polska Meidz plants. Useful co-operation between the plants using different technologies, aimed at the limiting the effect of undesired impurities on the quality of blister copper produced, is also described.

Jan 1, 1998

By Jian Zhang

From the standpoint of quality, surface cracks normally pose more of a problem than internal cracks. Hypo-peritectic (HP) steel grades are well known for their proneness to surface longitudinal cracking (SLC) during continuous casting. This study analyzed the influences of chemical composition, technique parameter and secondary cooling on the surface longitudinal cracks. Based on the optimized the first and secondary cooling zone water distribution in the process of continuous casting, low cooling water distribution at solidification initial stages and uniform cooling at secondary cooling zone were suggested, which can be used to effectively control the surface longitudinal cracks.

Jan 1, 2010

By R. G. Haire

Studies of the f-elements under pressure provide important insights into their solid state chemistry and physics. From such studies, of the elements and their alloys, it has been established that the normally localized f- electrons of several of these elements can become, involved in bonding under pressure. The electronic behavior of f-element compounds under pressure tend to be more difficult to interpret, due to the variety and the nature of electronic orbitals that are present. The 4f-elements and some 60% of the 5f-elements have been studied under The systematic comparisons that have been established for these materials are discussed.

Jan 1, 1992

By Geir Martin Haarberg

Modern electrolysis technologies can provide possibilities for developing sustainable processes in terms of energy and environment. Laboratory experiments were carried out to study electrodeposition of iron from molten salts and aqueous solutions using an inert oxygen evolving anode to eliminate the emissions of CO2. The possibilities of molten salt electrorefining of metallurgical grade silicon to produce solar grade silicon were also investigated. Electrochemical techniques were used to study the electrochemical behaviour of dissolved iron, silicon, and titanium species. Bulk electrolysis was carried out to deposit pure iron, silicon, and titanium. The quality of the deposits was studied by SEM/EDS and XRD analyses. Calculations based on laboratory studies indicate that great improvements in terms of reduced energy consum

Jan 1, 2010

By V. B. Telles, J. A. S. Tenorio, J. O. Alves, D. C. R. Espinosa

"The world production of crude steel in 2009 reached 1.2 billion tons. For each ton of steel produced, 150 kg of steelmaking slag and 20 kg of steelmaking dust are generated. These are wastes with considerable production and limited applications, therefore this work studied the recovery of these wastes into useful sub-products. The slag was used as raw material in the production of rock wool (a thermo-acoustic insulator) and the dust was inserted in the iron ore sintering process. Results showed that produced materials have exceptional proprieties, therefore the recovery of these wastes can contribute to decrease extraction of non-renewable resources, reduce the costs and impact of disposals, and aggregate value to the slag and dust.1. IntroductionSteel production using Eletric Arc Furnace (EAF) has grown over 119 million tones in the last years. In 2008 30.7% of all steel produced, was obtained through EAF. In United States of America (USA) the percentage of this process in the production of steel was about 58% in 2008, while in 2000 this percentage was only 47% [1]."

Jan 1, 2011

By Muammer Kaya, Sait Kursunoglu

"The aim of this study was to investigate the effectiveness of ascorbic (C6H8O6) / oxalic (C2H2O4) acid as a reductant for the simultaneous recovery of zinc and manganese from a spent and mixed zinc-carbon and alkaline battery powder in sulphuric acid leaching. The effects of sulfuric acid concentration, ascorbic/oxalic acid dosages, reaction temperature and leaching time on the zinc and manganese dissolutions were investigated according to 2k full factorial experimental design; then, a simple optimization study was carried out for the best reductant. The optimum reductive acid leaching conditions were determined at 3 hours leaching time, 70°C leaching temperature, 0.5M sulfuric acid concentration, 13 g/L ascorbic acid dosage, 1/20 g/mL solid/liquid ratio and 200 rpm stirring speed. Under these conditions, the dissolution efficiencies were 99.9% for Zn and 99.3% for Mn. When our results were compared with the previous results, our findings were better than previous studies.In addition, the manganese dissolution kinetics was undertaken, and the activation energy was found to be 7.04 kJ/mol. Selective precipitations of Zn and Mn from acid solutions were carried out using NaOH and KOH. Using 3M NaOH as precipitating agent at room temperature and at pH 8; 95.4% of Zn and at pH 10; 93.7% of Mn were precipitated from the leaching solution. Under the same conditions, using 3 M KOH at pH 8; 91.6% of Zn and at pH 10, 96.4% of Mn were precipitated. Based on the experimental results obtained, an appropriate flow sheet was proposed to recover zinc and manganese."

Jan 1, 2012

By Russell E. Clemons

Coarse-crystalline granite, quartz syenite, syenite, meladiorite, and anorthosite in the Florida Mountains, southeast of Deming, New Mexico, were originally mapped as Precambrian. They were remapped in 1971 and some of them described as Mesozoic intrusives. Several subsequent papers presented Precambrian and Ordovician ages. Zinc, lead, copper, silver, gold, manganese, fluorite, and barite mineralization in the Florida Mountains invite more extensive exploration. Clarification of ages of rocks and periods of alteration and mineralization are necessary for efficient exploration. Field observations combined with petrographic studies strongly suggest that all the coarse plutonic rocks are Precambrian and most were altered extensively by late Tertiary hydrothermal activity.

Jan 1, 1982

By Yury Kapelyushin

Formation of cementite in the reduction of hematite by CO–CO2 gas was studied in situ using high temperature XRD (HT XRD) analysis. Reduction of hematite was examined in the temperature range 873–1173 K by CO–CO2 gas mixture with high carbon activity. When carbon activity in the system was 1.5, cementite was formed only at 1023 K; it was not observed in experiments at 973, 1073 and 1123 K. Formation of cementite was observed at 923–1073 K when carbon activity increased to 3–5; and at 873 K when carbon activity was 10. Formation of cementite at 973–1073 K proceeded through metallic iron; however, in the reduction of hematite at 873 and 923 K, iron was not observed; cementite apparently was formed directly from wüstite. XRD spectra were used to estimate concentration of carbon in austenite in the process of cementite fromation.

By Shadia J. Ikhmayies

Nanocrystalline CdS:In thin films with particle size in the range (3-36 nm) were produced by the spray pyrolysis technique on glass substrates. The films were characterized by investigating their X-ray diffractograms (XRD), scanning electron microscope images (SEM), transmittance curves and photoluminescence (PL) spectra. The size of the nanocrystallites was estimated from XRD difractograms and then from the hyperbolic band model and the bandgap energies of the nano- particles, which were calculated from the positions of the minima in the first derivative curve of the absorbance. Fine-structured PL spectra confirmed the nanocrystalline nature of the films.

Jan 1, 2010

By K. R. Robilliard

An outline is given of the problems facing tlile lead and zinc industry from the viewpoint of the range of residues currently produced from electrolytic zinc, blast furnace and other processes. Smelting approaches available using top submerged lancing technology are discussed and analysed. Pilot plant results for a range of lead and zinc-bearing materials are presented.

Jan 1, 1992

By Daguang Lu

The section of sintering and BF (blast furnace) is very important in iron-making process. In practice, the scheduling is so extensive that three faults unfavorable to continuous product will be easier to happen. This paper introduces the integration Petri Net and GA (genetic algorithm) as suitable tools for simulation and optimization of scheduling to section of sintering- BF under a certain hot iron or-der. The situation of the iron plant Chongqing Iron and Steel Company is researched in approach above mentioned. By analysis, the conclusion is drawn that scheduling with optimized values can maintain continuity of key operations , can satisfy order of hot iron in maximal degree and can keep the best stability of key storages.

Jan 1, 2009