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By V. A. Bryukvin

A characteristic feature of the macrokinetics of the interaction process is the presence of two specifically defined areas of oxidation which had a linear time dependence. The effect of variables, such as residual sulphur content of the melt, temperature and the oxidation potential of the gas phase, on the macrokinetics of oxidation are investigated. Phase composition and structure of products of solidification of partially oxidised melts and thermodynamic properties pentaining to Cu-S-O melts are used to analyze the macrokinetic behaviour and mechanisms of the interaction. The process of interaction of sulfide copper melts with oxygen may be considered as a disproportional absorption process and its mechanism is based on localized interaction on the surface and inside the melt volume. Superficial processes include also the process of primary chemisorption of oxygen by melts at place of metal-metal donor bonds proceeding with formation of oxysulfide liquid solutions and volumetric decomposition of the latter accompanied by evolution of sulfur dioxide and metallization of sulfide melts. It is the degree of dynamic balance of such interaction processes that determines specific individual features of the macro-kinetics and mechanism of oxidation of sulfide copper solutions with oxygen in the gas phase.

Jan 1, 2006

By Laila A. Guirguis

Impurities are removed from crude phosphoric acid (57.75% P2O5) with a mixture of low and high molecular weight alcohols, one of which is hydrophilic and the other is hydrophobic i.e. methanol and hexanol. In a single stage, the phosphate values segregate to the high molecular weight alcohol fraction and the impurities segregate to the low molecular weight alcohol fraction. The optimum ratio for the extraction is found to be 0.5 part methanol, one part impure acid and four parts hexanol where an extraction percent of more than 95% is achieved. Re-extraction of the phosphate value from the solvent is obtained by 6% phosphoric acid and the different factors affecting the re-extraction process have been studied. Finally, the purified acid is concentrated under reduced pressure and passed through activated carbon column, whereas the alcohols are re-circulated. The produced phosphoric acid was found to be in good match with the international specifications of food grade quality acid. A technological flow sheet is elucidated.

Jan 1, 2006

By Y. W. Miao

Along the south-west coast of Taiwan is about 550,000 metric tons of heavy sand deposit containing about 10 % black monazite. The Institute has developed a separation process to recover the individual rare earths and the developed process has been commercialized by a local private company. The decomposition of the local black monazite by sodium hydroxide through hydrothermal and fusion methods has been investigated. In the hydrothermal process 4.5 wt. % of aqueous alkali solution was used in an autoclave. In the fusion process, caustic soda (9.8% NaOH) was employed in am open cylindrical reactor. The same product of hydrous rare earth oxides were obtained and then dissolved by hydrochloric acid and the p-H adjusted in order to separate the thorium from the rare earths. After filtration, the filtrate contained rare earth chloride and the cake contained mainly the silica and thorium hydroxide. Both methods give a yield of 90 % with respect to the rare earths recovery. A detailed description of operation and comparison of the two methods are given.

Jan 1, 1989

By Yang Tian-zu

The separation of precious metals from base metals containing in gold-antimony alloys by selective chlorination leaching under controlling potential was studied in this work. The effects of the consumption of hydrogen peroxide, the concentration of hydrochloric acid, the concentration of sulfuric acid, leaching temperature, leaching time and the liquid-solid ratio in hydrochloric acid system on the leaching efficiencies of the base metals have been investigated. The optimal leaching conditions of the gold-antimony alloys are as follows: hydrochloric acid concentration 4.0mol?L-1, sulfuric acid concentration 1.2mol?L-1, liquid-solid ratio L:S=7.5:1, the leaching temperature 80 0C, leaching time 2h, and the oxidation potential of the leaching system 400±20mV( vs SCE).The leaching efficiencies of copper, nickel and antimony are more than 99% and the gold leaching efficiency is about 0.042% under the above leaching conditions. The base metals containing in the gold-antimony alloy are separated from the precious metals thoroughly.

Jan 1, 2006

By D. G. Schmidt

Tests were conducted on C86200 high-strength yellow brass in order to ascertain the effect of a low level of nickel on the mechanical properties on this alloy. A series of two alloys was studied, one of which had a nickel content of 0.85% and the other with <0.05% nickel. Copper and aluminum content ranged from 62.5% to 64% and 3.2% to 4.6%, respectively. When compared by zinc equivalents, a nickel addition of 0.75% in high-strength yellow brass does not act like copper but raises the tensile strength, 0.5% yield strength and BHN while lowering the elongation.

Jan 1, 1999

By Lauri Pajunen

DSA-anodes are widely used in metal electrowinning. In zinc electrowinning the electrolyte solution contains manganese ions, and the deposition of manganese dioxide happens on the anode. This manganese dioxide layer cannot be removed without losing the active coating of the DSA-anode. The same problem can be found with hybrid anodes. In hybrid anodes mixed metal oxide coated titanium mesh is attached to a lead base material. In this study, the effect of dissolved manganese on anode behaviour is studied with three different anodes. These anodes are lead anode with 0.6% silver, hybrid anode and DSA-mesh. Methods of study include polarization, galvanostatic and potential mapping experiments.

Jan 1, 2003

By Jian Wang, Hongyang Cao, Binxiu Wu, Junhong Li, Jimin Wang

"The enrichment and separation of scattered metal indium component in the pressure leaching solution with sulfuric acid from vacuum furnace germanium slag were studied by iron substitute and P204 extraction, which is supplied by shaoguan smelter. The experimental results show that the extracting power of P204 for indium from pressure leach solution is powerful. The optimal technological condition were the ratio of P204 and sulphonating serosene 3:7, phase ratio 1:3, solution pH 1.2, and extracting 5 minute. The enrichment indium solution of 21.7 g/L In at 95.2% recovery ratio was obtained by three-stage counter flow extraction and four- stage counter flow stripping.IntroductionScattered metals, such as Indium and germanium, were inriched as intermediate product or by-product during the metallurgy process of other non-ferrous metals, such as lead, zinc, copper and tin. For example, the indium and germanium were inriched in vacuum furnace germanium slag, which is the by-product of zinc vacuum distillation operation from hard zinc. It is difficult to recovery the indium from the vacuum furnace germanium slag, because the indium content is low, and the chemical composition and phase compositon were complex.Recovery indium from bearing indium zinc slag was researched extensively, such as pressure acid leaching, high temperature evaporation, solvent extraction method[l-7], acid leaching method has the advantages of high leaching rate, which can be separated hydrochloric acid, sulfuric acid and silicon fluoride acid systems. Solvent extraction method has the advantages of low production cost, fast reaction speed, high enrichment ratio, and simple operation."

Jan 1, 2013

By Michael A. Krstich

A soil washing pilot plant to treat soils at the U.S. Department of Energy (DOE) owned Fernald Environmental Management Project (FEMP), was designed based on extensive bench-scale testing. The system&apos;s design incorporated a combination of physical separation and&apos; chemical extraction processes and was tested on two soils. The textural composition of the two soils was approximately 20 percent sand, 60 percent silt, and 20 percent clay. Since this grain size distribution was not considered optimum for physical separation techniques, thesoil washing pilot plant had to be designed with selected equipment to provide specific soil size fractions during processing operations. A trommel, vibrating screen deck, centrifuge, and attrition scrubber were used in the system to selectively separate specific soil size fractions at 4.75, 2, 0.3, and 0.02 millimeters (mm). The trammel used high pressure water [1000 pounds per square inch (psi)] during the initial step of the process to reduce soil aggregates to single grain composition, separate out greater than 4.75 mm gravel, and dislodge chemical contaminants from the individual soil particles. The vibrating double-screen deck provided 2 - 4.75 and 0.3 - 2 mm soil fractions that, when combined, averaged greater than 75 percent solids for both soils. The centrifuge was designed to take the less than 0.3 mm soil slurry from the screen deck and produce a particle size of 0.02 mm. The centrifuge produced a high solids stream that averaged greater than 70 percent solids for both soils. These 0.02 to 0.3 mm soil solids from the centrifuge were combined with the 0.3 to 4.75 mm soil solids from the screen deck and processed through the attrition scrubber. The data collected from the pilot-plant operation was used to aid in the design of a full-scale system and was instrumental in formulating full-scale process operations and the selection of equipment.

Jan 1, 1995

By F. Kongoli

A computerized thermophysicochemical database is being developed for various processes involved in nickel smelting and converting. This database includes optimized models for slag, matte, liquid and solid alloys in the multicomponent system(s) as applied to batch and continuous nickel smelting and converting processes. This database can be used to quantify the multicomponent and multiphase slag/matte/alloy/gas equilibria, liquidus and solidus surface, tie-lines, solubility and/or losses of nickel and other components in the slag, distribution coefficients, components activities, heat and mass balance, etc. The database also includes optimized models for the viscosity of the slags associated with any of the above processes. Both databases are coupled and this constitutes a very effective method to quantify the effect of each component on several parameters of the smelting and converting processes and to diffuse the confusion that exists in the literature. Several application examples have been given to demonstrate the usefulness of this database for quantitative prediction of the thermophysicochemical properties of the phases involved in actual or developing processes, even in the areas where experiments are difficult or impossible. The considerable cost reduction that results ftom the use of this database as compared to other methods in the improvement of existing technologies or in the development of new ones is discussed along with continuing new developments of this database.

Jan 1, 2002

By Hongbo Zhao, Jun Wang, Wenqing Qin, Guanzhou Qiu

Jan 1, 2015

By Pradeep kumar Jha, Manas Mohan Mahapatra, Sabin Kumar Mishra, Satish Kumar Ajmani, Satish C. Sharma

"Due to mechanical/ electrical failure in the C.C. line or inadequate availability of molten steel from coming ladle, sometimes one/two outlets of a multi-strand tundish in continuous casting unit is closed. Closing any of the outlets affects the flow distribution inside the tundish which in turn governs the quality of steel coming out. Hence it is important to study which of the outlets should be closed to have proper results in terms of flow behavior and inclusion removal inside the tundish. Present study aims at finding the effect of closing one or two outlets on flow behavior and inclusion removal in a multi strand tundish. It was found that closing the near outlet (outlet near to the inlet) increases the inclusion removal tendency than closing the other two outlets in a six-strand billet caster tundish (only three outlets are considered because of symmetry).IntroductionContinuous casting process transforms molten metal into solid on a continuous basis. This process is the most efficient way to solidify large volumes of metal into simple shapes for subsequent processing [1]. Molten metal is tapped into the ladle from furnaces. From the ladle, the hot metal is transferred via a refractory shroud (pipe) to a holding bath called a tundish. The tundish allows a reservoir of metal to feed the casting machine while ladles are switched, thus acting as a buffer of hot metal as well as smoothing out flow, regulating metal feed to the moulds and cleaning the metal [2]."

Jan 1, 2012

By Georgeta Rata, Cornelia Petroman, Ioan Petroman

"Proper training and education in the field of recycling and waste treatment are inconceivable without the proper teaching of the terminology specific to both recycling (aerospace products recycling, automotive recycling, general recycling, recycling behaviour, recycling schemes, recycling systems, and waste recycling) and waste (characterization of waste, electronic waste, heavy-metal containing waste, monitoring of waste, radioactive waste, solid waste, waste collection, waste conversion, waste recycling, waste reutilization, waste stabilization, waste storage, and waste treatment) in both the students’ mother tongue and in English for Special Purposes (ESP) as a second language (with focus on the structuring of the specific terminology). Including linguistic approaches among the possible approaches of environmental protection and material sustainability means including linguistics among the various disciplines addressing energy supply, cement and building materials, metallurgy, chemistry, glassware, pulp and paper industry, machinery, automobile and electronic industries, collection, and sorting, further treatment and final disposal of post-consumer material.IntroductionCultural and technical changes have produced more novel artefacts than novel activities or novel properties, generating new vocabulary needs that are readily answered by new words (nouns).The purpose of this research is to show that ‘waste words’ – phrasal words (items that have the internal structure of phrases but function syntactically as words, e.g., cattle waste) and particularly compound nouns (words formed by combining roots, that tend to have a meaning that is more or less idiosyncratic or unpredictable, e.g., wastepaper ‘discarded paper’) – used in the study of the English of recycling, waste treatment, and clean technologies can be misleading for both native and non-native students and/or users of English because their structure alone does not allow instant, proper understanding of their meaning.Our hypothesis is that this inconvenient can be overcome by getting to reach the proper meaning of these new words. Or, arriving at the precise meanings of the ‘waste words’ depends on our knowledge of the world (for example, wastepaper indicates that some used paper is discarded and not wasted) rather than on purely linguistic knowledge."

Jan 1, 2008

By Amy Nelson

In the electrolytic production of zinc, cobalt is removed from the zinc electrolyte by cementation with zinc dust prior to electrowinning. Although the thermodynamics for this reaction are favourable, kinetic barriers to cobalt reduction render the method almost useless in practice unless activators such as copper and antimony or arsenic are added. There is a large body of work studying the effect of these additives, yet the mechanism by which they act is still poorly understood. Even when the target conditions are met, zinc dust consumption is excessively high: satisfactory operation requires up to 300 times the stoichiometric amount of zinc dust. The objective of this work is three-fold: (1) to examine the effects of activators and elucidate the characteristics that make a good activator; (2) to identify new additives that could lead to a more efficient purification process; and (3) to test the new additives with synthetic and real electrolyte solutions. The present paper gives a status report on this project.

Jan 1, 1998

By Kim Fagerlund

A novel apparatus for studying refractory infiltration and dissolution/degradation under a temperature gradient was developed. To supersede conventional isothermal refractory testing, a new temperature gradient technique, based on a crucible equipped with a cooling element, has been developed to provide practical information on the penetration and dissolution of refractory materials under cooled conditions. This technique was adopted and applied to several refractory-slag systems. Commercially available magnesia chrome refractory bricks against a copper-containing calcium ferrite type of slag were tested and compared using both a conventional crucible test and the new temperature gradient method. The experiments were conducted at 1300-1420°C under a controlled atmosphere of nitrogen or air. It was noticed that the type of porosity has a significant effect on infiltration of magnesia chrome refractories. Furthemore, the copper-containing calcium ferrite slag caused a severe slag attack and refractory failure in some cases, due to its fluidity and corrosive nature.

Jan 1, 2002

By Alan J. Hurd

"New insights into the development of microstructure in sol-gel films have recently been revealed by several diagnostic techniques, including imaging ellipsometry, ""chemical imaging"" by fluorescent tracers, light scattering from capillary waves, and finite-element modeling. The evolution of porosity during the continuous transition from dilute sol to porous solid in restricted geometries such as films and fibers is becoming clearer through fundamental understanding of evaporation dynamics and capillarity.IntroductionWith sol-gel processing, the full flexibility of solution chemistry can be exploited to make ceramic films and fibers with well controlled compositional characteristics. No less important is the ability to tune porosity and connectivity for specific applications such as optical and electrical coatings and membranes. Since the chemical and physical factors that determine the microstructure are not entirely understood, new diagnostics applied to sol-gel processing are welcome.Sol-gel films and fibers are distinguished by processing that takes a sol through continuous stages of increasing concentration and connectivity of a solid precursor. The liquid carrier is usually volatile or, at least, volatilizable through heat treatment. During deposition through states of increasing solids concentration, this sol might gel, as in bulk sol-gel processing, however, the gel state may be a fleeting transient that quickly empties of liquid. Nevertheless, the structures formed in solution during this stage influence the structure of the final solid. In particular, porosity is likely to be a remnant of networks formed in the sol-to-gel transition. Here we report on experiments whose goal is to discover the factors involved with porosity development."

Jan 1, 1994

By Ashok D. Dalvi

Production of nickel from laterite ores has occurred for over 100 years beginning with processing of garnieritic ores from New Caledonia. However, until now the world nickel supply has been predominantly from sulfide sources. Going forward, the authors project that the production of nickel from sulfide ores will remain more or less constant. Most of the expansion in nickel production capacity over the next ten years will come from processing of laterite ores. Thus the capital and operating costs of new laterite projects will have significant impact on the nickel supply and therefore price. The authors have reviewed the history and capital and operating costs of various recent laterite projects and capital and operating costs of these projects and those "on the drawing board". The authors have also evaluated the risk associated with such projects. The paper will discuss the impact of this and the recent history on the future development of laterite nickel projects.

Jan 1, 2004

By Y. Maeda

Non-ferrous smelting furnaces generally install a gas cooling system for treatment of waste gas containing SO2,. From the point of view of corrosion resistance and recovery of waste heat, the high pressure boiler system is the best way to cool gas, however this system requires high initial investment and relatively higher operating costs. Because the feasibility of this boiler system greatly depends on the smelting process and scale, other lower temperature systems, e.g. water-cooled jacket system, are more suitable if the smelting process does not produce enough steam nor generate enough electricity to compensate operating cost. In additton, the water-cooled jacket system is simple in structure and easy to operate. For those reasons, it is applied widely. A new smelting furnace was planned in our factory and it was necessary to install waste gas cooling equipment. In our case, a water-cooled jacket system was more feasible because of the low gas volume and high dust content. It was also expected to operate without maintenance for ten years. On the other hand, some leakage problems with the water-cooled jacket had been experienced in the past. That is because SO2 In the waste gas changed into sulfuric acid which corroded the jacket material. As the first step, several data from actual&apos; usage were reviewed to throw light on the corrosion process, and an appropriate procedure to determine the operating temperature of cooling water was obtained. For the basis of this study, a water-cooled jacket system was newly designed and tested for three months in a pilot plant. After this system&apos;s performance was confirmed, it was installed in a new furnace as a commercial plant. After one year of operation, the initial thickness of carbon steel jacket remains almost the same.

Jan 1, 1992

By Antonio Luraschi

The constituents iron, oxygen, silica and cop- per are of principal interest in slags utilized in pyrornetallurgical processes for producing copper. Accordingly, phase relationships in the.Cu-Fe-0-SiO2 system are important when one considers the physico- chemical behavior of slags. These phase relation- ships for the quaternary and constituent ternary systems are developed from available information. Isothermal composition and composition-oxygen potential diagrams, and oxygen potential-temperature diagrams are utilized to describe the&apos; important relationships.

Jan 1, 1976

By Kliment Y. Hakobyan

A new technology for treating molybdenum sulfide concentrates has been developed. It includes roasting the concentrate in a special regime with water vapor, cooling and neutralizing exit gas, oxidation roasting of rhenium containing MoO2, and the extraction of rhenium from exit gases. This technology allows economically efficient and environmentally safe processing of molybdenum concentrates: The degree of molybdenum extraction is 98.8%, rhenium-90%, sulphur-98.4%. The technology also ensures high extents of extraction of selenium and tellurium as well as the fixation of sulfur in the form of sodium sulfide or elemental sulfur.

Jan 1, 2006

By Subagyo

The condition of slag in a pyrometallurgical reactor is vital to ensuring control of the process. A new technique based on multivariate image analysis (MIA) of digital images has been developed to provide an online measurement of important slag characteristics, such as the presence of exposed metal, the presence of solid phases, and temperature. This paper shall describe the technique and provide some results from analysis using industrial plant data.

Jan 1, 2003