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By A. N. Lasseigne

Hydrogen storage capabilities of LaNi5 intermetallic compounds were investigated utilizing the combination of thermoelectric power, Beeghly Ester-Halogen digestion, and Leco hydrogen determination. Thermoelectric power has demonstrated a rapid hydrogen assessment capability and can achieve the equivalent of the pressure-composition-temperature (activity) diagram. Effective use of hydrogen storage materials occurs in the two-phase, alpha+beta region of the PCT diagram. A thorough assessment of the content of each phase in this two-phase region to optimize performance of the hydrogen storage materials is described. Practices using the combination of these three analytical practices for rapid characterization of LaNi5intermetallic alloys are discussed.

Jan 1, 2006

By David B. George

Kennecott recently completed an $880 million modernization and expansion of its smelter and refinery to process all concentrates from the Bingham Canyon mine. This is the first application of Kennecott-Outokumpu Flash Converting. Molten material movement by overhead cranes is eliminated and high levels of oxygen enrichment result in very low process gas volumes and exceptionally control of sulfur oxide emissions. All existing in-plant hygiene, safety, and environmental regulations will be met and the smelter is positioned for anticipated more stringent future regulations. Sulfur capture is 99.9 percent resulting in sulfur dioxide emissions less than the 112 kg/hr Air Permit limit, making the smelter the cleanest in the world.

Jan 1, 1996

By J. C. DeSantis

Thin, highly reflective rhodium films with metal compositions greater than 98% (elemental -weight percentage) have been deposited by chemical vapor deposition using Rh(allyl)3 (ally1 = q3-C3H5) in the presence of a hydrogen plasma. Uniform, crystalline films that adhere well to several types of substrates result from depositions at temperatures as low as 150°C. Depositions using H2 (no plasma), or an argon plasma yields material that is amorphous, contains a significant amount (>14%) of residual carbon, and has a dramatically slower growth rate. The composition of these materials does not vary significantly from that of the materials obtained from the in vacuo thermal deposition with Rh(allyl)3.

Jan 1, 1992

By Manabu lshimaru

Solid-liquid interfaces as well as defect formation processes during crystallization of melted silicon (Si) have been examined by using molecular-dynamics (MD) simulations. The ordinary Langevin equation employing the Tersoff interatomic potential was used for the calculation of the atomic trajectories. A solid-melt interface has a tendency to form {]] I} microfacets during the crystal growth in the [001] direction, while it is essentially flat during the (Ill) crystallization. Because of the difference of the interfacial structures, the structures of grown-in defects and defect evolution depend strongly on the growth direction. We discuss defect structures and their formation processes within the context of our results as well as previous experimental observations.

Jan 1, 2001

By D. C. Azubike

Wolframite (FeWO4) usually having cassiterite (SnO2) as a major impurity is a primary source of tungsten. Its direct reduction/carburisation with carbon in the temperature range 1000-1400°C, and with hydrogen at 600-900°C followed by carburisation with CO at 900°C are described. Depending on the conditions and reactants employed, Fe, Fe2W, B-Sn,WC, W2C, Fe3W3C and Fe6W6C are the products. Tin was found to inhibit the overall reduction and carburisation reactions significantly. The potential for either efficient separation of iron and tungsten or a one-stage production of an iron-based metal carbide composite is discussed.

Jan 1, 1992

By Junji Shibata

Extraction behavior of Ti(IV) and other metal ions, such as Fe(III), Fe(II), Cu(II), Zn(I1) and Co(I1) from acidic solutions like sulphuric acid and hydrochloric acid was studied in order to recover titanium from the waste solution in Ti02 production. Extractant used was tri-alkyl phosphine oxide whose trade name was Cyanex 923. Then, a study was made of the idea of simulating a countercurrent multistage extraction system, using the results of batch extraction. The simulation was camed out on extraction and saipping behavior for a Ti(1V)-H$O,-Cyanex 923 system. From the simulation result., the optimum operating condition of the system was considered.

Jan 1, 1994

By Seung-Chul Lee

Transparent conducting tin(1V) oxide thin films have been studies and developed for the electrode materials of solar cell substrate. Fabrication of tin oxide thin films by sol-gel method is process development of lower cost photovoltaic solar cell system. The research is focused on the establishment of process condition and development of precursor. The precursor solution was made of tin isopropoxide dissolved in isopropyl alcohol. The hydrolysis rate was controlled by addition of triethanolamine. Dip and spin coating technique were applied to coat tin oxide on borosilicate glass. The resistivity of the thin film was lower than 0.18-cm and the transmittance is higher than 90% in a visible range.

Jan 1, 1999

By P. Louis

Although cobalt is known and used for its hardness and wear resistance, ductile cobalt can be obtained by electrolysis in chloride solutions, under the following conditions : pH : 1.5 - 2, Co++ : 30 - 60 g/l, current density : 100 - 500 A/m2, temperature 40 - 70°C. No explanation was found for the ductility of the deposit under these conditions. Indeed the ductile P (FCC) cobalt and the hydrogen contents in the cobalt deposits are nearly the same as those obtained in a sulfate media, which gives brittle depo¬sits under equivalent electrolysis conditions. Malleable cobalt sheets can be easily obtained under the proposed conditions which could lead to new applications for cobalt.

Jan 1, 1988

By C. M. Iheagwara

This paper has addressed the issues that constitute major obstacles to the cost- effective and efficient operation of metallurgical vessels from the refractory standpoint. Refractories generally withstand severe conditions of high temperature reactions as well as physical loading/impingement and hence degenerate and need replacement. Scarcity of some refractory materials especially high alumina and magnesite ores in some places, the prohibitive cost and the frequency of replacement of damaged refractories threaten the continued support for metallurgical operations. Some of the causes, prevention and cure for refractory wear have been discussed and rational strategies (short and long term) have been recommended which if implemented should go a long way towards arresting the perennial problems they portend.

Jan 1, 1991

By Patrick M. Eduafo, Brajendra Mishra, Mark L. Strauss

Direct acid leaching of rare earth metals (REMs) from waste lamp phosphors is non-selective, leading to co-dissolution of impurities mainly calcium, phosphorus, silicon, iron and zinc. Calcining the phosphor powder at different temperatures followed by leaching with HCl isn’t efficient for the extraction of all the chief rare earths especially cerium (Ce), lanthanum (La) and terbium (Tb). Therefore, multi-stage leaching operations are required for the separation of the REMs in phosphor dust. This paper will outline a new process for extracting Ce, La, Tb, Eu and Y from waste fluorescent lamps using a three-stage leaching and separation process. A flowsheet has been developed which shows this process is selective and efficient.

Jan 1, 2015

By T. Inami

The chlorine leach of the anode slime was studied in order to improve the treatment process at the Niihama Nickel Refinery. The anode slime originates from the nickel matte electrorefining and, contains 3-5% of nickel as sulfides. A comparative study has been conducted on the filter cake resulting from the sulfur filtration of the molten anode slime. The kinetic factors of the chlorine leach such as temperature, grain size were defined. Under the optimized condition, 70-80% of the nickel is recovered from the slime or filter cake. On the basis of these results, the chlorine leach process for the treatment of anode slime has been established. The leaching plant has been installed and successfully operated since 1986.

Jan 1, 1988

By Tim B. Vanderwood

The mineralogy of dusts from several locations in a lead smelting plant, remotely collected dusts and soils near the lead smelter, and dusts from a secondary copper smelter were examined by reflected light microscopy (RLM) to determine their m1neralogy, texture, and origins. Individual grams were further analyzed by microbeam techniques. Detailed petrographic analysis of the dust has been supplemented by automated scanning electron microscopy combined with energy dispersive x-ray spectroscopy (ASEM-EDS). This technique allows the rapid sizing and chemical analysis of thousands of individual particles in a dust sample, producing particle size distributions as well as statistically meaningful breakdown of a sample into chemical types (e.g., proportion of galena vs chalcopyrite).

Jan 1, 1992

By George R. St. Pierre

A method for the quantitative description of activity interactions between solutes in a metallic solvent which is consistent with stalistical thermodynamic principles is presented. The chemical potential of a solute in an alloy is derived from the weighted mean of its values in the individual solvent components, µi = S?jµi(i). The weighting factors, ?j, are obtained from the distribution functions. The resulting equation contains far fewer adjustable parameters than the Epsilon Formalism and because of its correct functional form it provides an improved fit to the available data on a variety of alloy systems containing oxygen, carbon, sulfur, nitrogen, and hydrogen. For a binary metallic solvent ( A, B ) containing a solute (i), it is shown that

Jan 1, 1995

By H. Fukushima, T. Ohgai, N. Baba

The electrodeposition behavior of Zn and the morphology of the deposited Zn were studied in electrowinning solutions containing polymer additives such as gelatin and polyethylene glycol (PEG). The cathode potential was shifted in a less noble direction and the polarization resistance for Zn deposition increased with increasing concentrations and molecular weights of both gelatin and PEG added to the electrolytic solutions. However, when the molecular weights of these additives exceeded about lxlO4, the cathode was depolarized and the polarization resistance for Zn deposition decreased with increasing molecular weight. The crystal grain size and the (002) orientation of the deposited Zn became smaller when the concentration and molecular weight of the additives increased, and the cathode was polarized.

Jan 1, 2000

By L. Salinas

Lance injection of gas and particles into a molten bath is currently practised in metallurgical processes (Mitsubishi lances for example). Several experimental and theorical studies have been conducted in the past on this topic. However, neither detailed calculations nor experimental studies of local flow patterns have been published. In the present work, a numerical simulation of the interaction of a gaseous vertical descending jet and a liquid surface was done, using the turbulence k-e model. There is a fair agreement between the calculated and the experimental values. The results of this study demonstrate that it is crucial that the gas jet velocity profile and turbulent characteristic are correctly formulated in order to correctly simulate the system.

Jan 1, 1999

By Y. Sako, E. Nomura, K. Muraguchi, K. Shibata

In 1998, Mitsui Mining & Smelting Co., Ltd. (MMS) produced 70,000 tonnes of lead, 231,000 tonnes of zinc and 214,000 tonnes of copper. MESCO, Inc. has been in charge of the automation and mechanization of smelting facilities promoted by MMS as well as the construction of facilities for chemical production and electronics materials plants, by which MESCO has contributed to the development of MMS. Initially, MESCO developed a casting machine for refined lead in the early 1960's, and thereafter, it developed a casting machine for refined zinc, a stripping machine for zinc tankhouses and energy saving facilities. In the field of copper smelting, it has also developed automation and mechanization facilities.

Jan 1, 2000

Copper and gangue mineralogy constitute the most critical parameters for the hydrometallurgical processing and cost-efficient extraction of copper. Minor changes in copper-, rock-, or alteration mineralogy can severely impact the comminution efficiency, curing, agglomeration, acid consumption, copper extraction and PLS impurity loading. Further, copper leach operations, particularly in the southwestern United States, are increasingly challenged by a combination of low grades and semi-refractory copper. This paper discusses the metallurgical and economical benefits of continuous mineralogical analyses in order to establish and operate a mineralogical data base in copper leach operations. Troubleshooting for copper extraction, integration of process mineralogy into production forecasting, and process optimization will be illustrated with operational experiences from Chile and the United States.

Jan 1, 1999

By Seiji Yokoyama

As a series of fundamental study on the gas evaporation method, a levitation-melted aluminum was evaporated in the gas mixture of argon and ammonia to synthesize ultrafine particles of aluminum nitride. When the ammonia partial pressure were more than 2kPa, the formation ratio of aluminum nitride was about 95%. The particles of aluminum nitride were mainly hexagonal. The mean size of the particles of aluminum nitride was about 57 nm, and it was constant without depending on the temperature of the levitated aluminum and the partial pressure pf ammonia. The aluminum nitride was formed by the reaction between ammonia and condensed liquid aluminum particle whose size was relatively small.

Jan 1, 2006

By Barry T. Kilbourn

A dominant characteristic of many derivatives of the lanthanides is stability at high- temperatures. Combine this with novel solid-state behavior under those conditions and there is the potential for new materials that can not only improve existing applications but also help create new technologies. These property themes will be traced through new uses ranging from efficient energy generation and raw material conversion to control of environmental emissions and temperature measurement. Conducting ceramics, methane conversion catalysts, sulfur oxide capture agents and phosphor hosts will be described. Some categories will account in the future for significant lanthanide consumption whereas others will remain commercially negligible but technologically vital. All uses will illustrate the versatility of those elements inappropriately termed rare.

Jan 1, 1992

By D. G. C. Robertson

The thermodynamics and kinetics of the reactions involved in fuming zinc from oxide slags using coal or coke were first studied in 1955 and have been the subject of many investigations since that time. The key reaction is ZnO(in slag) + CO Zn(g) + COl. This paper will review the some of the recent work, and will add new insights obtained in experiments carried out by the authors. In the first series of experiments it was shown that the reaction 2Fe2+ + ZnO = 2Fe3+ + Zn(g) or 2FeO + ZnO = Fe2O3 + Zn(g) does not occur at an appreciable rate, as is expected from thermodynamic considerations. In the second series of experiments it was shown that zinc does not fume from the slag at a significant rate unless a reductant has been added. This again is in accord with thermodynamic considerations, but is in contradiction to some of the experimental results reported in the literature. A third series of experiments was carried out with excess coke being present, so that the rate of supply of reductant was not in any way controlling the rate. The kinetics of zinc oxide reaction were then found to be independent of the zinc oxide concentration, but increased with increasing basicity, and temperature. The presence of high concentrations of FeO in the slag also improves the kinetics. At low zinc oxide concentrations iron oxide reduction occurred in parallel with zinc oxide reduction. We propose that (under the conditions of this work) the kinetics were controlled by a chemical step, namely the rate of desorption of an adsorbed CO2 species. This is the same mechanism as reported by Belton and co-workers for the kinetics of the reduction of FeO. This explains why the reduction of metal oxides in slags by hydrogen is often faster than by CO.

Jan 1, 2003