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By Shekhar Bhansali, Shyam Aravamudhan

"This paper reports on the design and simulation results of a silicon bulk-micromachined diaphragm-type piezoresistive pressure sensor capable of operating linearly over a wide dynamic range (0-1000 meters of water). The piezoresistor elements of the sensor are arranged in a wheat stone bridge configuration to achieve a higher output response. Simulation results (output voltage and sensitivity analysis) obtained using coupled MemPZR-MemMech module of the CoventorWare2003 Finite Element tool are presented. The effect of diaphragm size, diaphragm thickness and thickness of the piezos on output sensitivity were analyzed and optimized to get a linear response over the wide dynamic range.IntroductionThe physical and biological processes in the ocean are critically influenced by ocean parameters (pressure, salinity and temperature). Thus there is a need to develop inexpensive and reliable sensors to continuously measure large volumes of sea-space over long time spans. A key component in any such system will be a pressure/depth sensor. This sensor is routinely employed in marine applications such as wave and tide gauges, tsunami detection, platform leveling etc. More significantly, pressure measurement is needed for depth determination. Depth sensors are vital for remote operated vehicles (ROVs), profiling instruments and towed arrays.Several techniques have been routinely used in the past to measure pressure in the marine environment [1-3]. In general, the pressure sensor design is based on a flexible membrane as the spring element for the sensing pressure [4]. The deflection of the membrane, induced by the applied pressure, is converted into an electrical output through a component that is sensitive to diaphragm deflection (capacitive coupling) or associated stresses (piezoresistors, strain gauges). The temperature compensated pressure measurement can be readily converted to depth using"

Jan 1, 2004

By Yuri Gelfgat

"The report presents the results of theoretical and experimental investigations of the MHD method used for production of composite materials from immiscible melts, e.g., Al-Pb, Zn-Pb, Bi-Ga and others, which, when solidified, can be presumed as ""frozen emulsions""IntroductionThe searching of the methods for controlling the phase distribution in various liquid heterogeneous media is one of urgent tasks in modem material science. The studies [1-3] have revealed that in case of electrically conducting media the influence of electromagnetic body forces on the liquid can be a rather effective mean of such a control. The current paper investigates some physical conformities governing the behaviour of binary liquid metal systems with a immiscibility region under electromagnetic processing designated to produce ingots with homogeneous structure.The main idea of the proposed method rests upon a concept that the electromagnetic forces in the melt are similar to gravity forces due to buoyancy effects in space and have a selective ability to influence the melt components dependent on their conductivity. In crossed electric E and magnetic B fields (fig.I) each component of the medium is influence by the force density f = jXB, where the current density j is determined by the conductivity a of the component j = -oE. When this force is directed parallel or non-parallel to the gravity vector, the buoyancy of suspended particles can be controlled accordingly.This phenomenon allows one to create a situation in binary system, when the sums of all mass forces (gravity and electromagnetic) affecting every component are equal, and two components are under conditions of equilibrium with respect to each other. These conditions are called quasiweightlessness, which is generated in the melt by the electromagnetic forces."

Jan 1, 1998

By Rodríguez M. Esperanza

The efficient performance of Pachuca tanks is strongly linked to the suspension of mineral particles, which results from the motion of the liquid caused by injected gas rising, in general, through a central draft tube. This study reports a computational investigation on the effect of operating and design parameters on the suspension of particles. By extending the classical 2-phase drift-flux model to compute the gas hold-up, the three-phase (water-air-particles) system was simulated as consisting of a variable-density liquid plus the solid particles. These two phases were treated as interpenetrated continua using an Eulerian approach to set a turbulent recirculating flow model in 2-D and transient state. The model predicted adequately the measured critical superficial air velocity, uc, needed for maintaining particle suspensions, in pulps with 10-50 wt% solids. Additionally, the model was used to investigate the operation of industrial size reactors, obtaining results that agree well with the general trends reported in the literature, and highlighting important differences with respect to laboratory-scale reactors.

Jan 1, 2009

By Luis W. Pommier

The developed processes, the subject of this paper, extract the hydrocarbons, halogenated organic compounds and metal contaminants from hazardous soils, rendering them non-hazardous and ready to be placed back on the ground. The processes first segregate a non-contaminated fraction from the contaminated soil. This initial task is performed using available minerals processing technology: sizing, gravity separation, magnetic separation, froth flotation, etc. The remaining contaminated fraction, is submitted to two leaching operations for the removal of organic and metal contaminants, whenever both are present or to a single leaching operation if only one type of contaminant is present. The decontaminated soil fraction is mixed with the non-contaminated fraction and is placed back on the ground. The leaching liquors, used at neutral pH, are non- hazardous. After decontamination the liquids are processed to extract the contaminants, now valuable materials, for commercialization. Organic contaminants are removed by distillation of the solvents. The metal contaminants are precipitated in their oxide form. In both cases the regenerated solvents are recycled. The decontamination processes are economically competitive with transportation and disposal of the soils to permitted facilities for hazardous materials, and most importantly the developed processes remove the liabilities from the Responsible Parties. The law establishes that these liabilities do not disappear with either fixation nor with transportation and disposal since the environmental liabilities are of the ? cradle to grave? type.

Jan 1, 1994

By C. M. Wai

"Metal species in solid and liquid materials can be extracted by supercritical carbon dioxide containing a suitable ligand. This in situ che1ation-supercritical fluid extraction technique offers several advantages over conventional solvent extraction including minimization of organic liquid waste generation and exposure of personnel to organic vapors. One unique feature of this technique is that metal species can be removed from solid materials directly using supercritical carbon dioxide as a solvent. Several ligand systems including dithiocarbamates, B-diketones, organophosphorus reagents, and macrocyclic compounds have been tested for metal extraction in supercritical carbon dioxide. This novel extraction technique may have important applications for metal recovery and mineral processing.IntroductionSupercritical fluid extraction (SFE) offers several advantages over conventional solvent extraction including the minimization of organic liquid waste generation and exposure of personnel to organic vapors.[1] The high diffusivity, low viscosity, and T-P dependence of solvent strength are some attractive properties which make supercritical fluids excellent candidates for extraction and recovery of organic compounds from solid materials [2] Carbon dioxide is a gas of choice for SFE because of its moderate critical constants (Tc = 31 °·C and Pc = 73 atm), inertness, and availability in purified form. After extraction, the fluid phase is depressurized to separate organic solutes from CO2 gas and the gas can be recycled for repeated use. The SFE technology has been applied to industrial scale operations such as the preparation of decaffeinated coffee and hop extracts."

Jan 1, 1996

By S. I. Sobol

Completeness of cobalt recovery from slag requires decomposition of maggemite and non - ferrous metal desorption with polymerized silicon-acid. Cobalt losses are reduced in leaching tai1s up to 200 g/t of iron.

Jan 1, 1993

By A. René Silva

The separation of Fe(III) from simulated Ni(II) solutions using different ion exchange resins was studied. The resins tested included cation exchangers with sulfonic and carboxylic groups and chelating resins with iminodiacetic, aminophosphonic, and mixed sulfonic and phosphonic groups. The dosage of resins was varied from 0.1 to 0.5 g/mL to study the impact of resin type and dosage on iron separation from simulated nickel leach solution containing 25 g/L Ni(II) and 25 g/L Fe(III) at pH 1.5. Also, the effects of different metal ion concentrations, Fe (III):Ni(II) ratios in solution, pH, and adsorption times were investigated. Experimental results demonstrate that all the chelating resins selected favored the adsorption of Fe(III) over Ni(II) with high Fe(III) loading. Soft cation exchange resins also favored the adsorption of Fe(III) over Ni(II), but no significant Fe(III) loading was observed. In contrast, strong cation exchange resins did not show adsorption preferences. The most efficient separation was observed using resin with aminophosphonic groups at resin dosage of 0.2 g/mL, having a Fe(III) adsorption over 94% and Ni(II) adsorption below 5%.

By Xu-ling Chen, Qian Li, Yong-bin Yang, Zhao Jing, Tao Jiang, Guang-hui Li

"It is generally known that alkali metals are harmful to blast furnace production resulting in aggravating RDI of sinters, abnormal expansion of pellets, deteriorating blast furnace lining, etc. Sinters regarded as dominating burden of blast furnace are determined as the main source of alkali metals. In this study, the removal behavior of potassium and sodium oxides by pre-reduction sintering during the sintering process was studied. The removal ratio ofK20 and Na20 was greatly influenced by coke powder content, carbon species, coke powder adding ways, additive and so on. Under the conditions of carbon rate 12% and 5% dosage of CO supplied in the sintering process, the corresponding removal ratio ofK20, Na20 was 69.00% and 32.79%, and metallization ratio could reach 4.65%. This technology provided a novel process for reducing the content of alkali metals in sinters and dramatically improving the quality of blast furnace burden.IntroductionSinter is the main iron-bearing charge of blast furnace for iron-making in China, making up about 80% of the total burden; therefore, its quality has a significant influence on the quality of pig iron and blast furnace operation. Research and practice of numerous years prove that potassium and sodium coming from ores are brought into blast furnace and upgraded, which is one of the essential reasons that lead to blast furnace nodulation and influences its strength. Currently, effective flow sheet to remove potassium and sodium is weak magnetic separation-intensive magnetic separation-flotation [l], while iron ore concentrate is still ofhigh levels of potassium and sodium. As sintering process is also not effective to remove potassium and sodium, blast furnace in China is of high alkali burden, e.g. it reaches 5.6-6.2kg/tFe in Baotou iron making plant, which is greater than international tolerated level of2.55kgltFe [l]."

Jan 1, 2013

By Mathilde Guilpain

A wide variety of plants are able to extract nickel (Ni) from soils and accumulate this metal in their foliage. Hydrometallurgical processes have been developed to recover Ni in the form of metal or salts, starting from the plant A. murale. They include: (1) a combustion step, to obtain ash containing 15–20% Ni; (2) a leaching step; and (3) purification. That whole flowsheet has been thoroughly investigated, and the processes scaled up to the pilot scale. Another strategy is presented here, consisting of recovering Ni without burning the plant. Ni can be extracted from the dry plant by water leaching, but the leachate is a multi-element solution from which Ni has to be separated. Selective precipitation of Ni hydroxide is not possible since Ni is bound to organic ligands. In this work, the plant leachate is processed by adsorption on the chelating resin DOWEXTM M4195. The results showed that Ni was selectively retained whereas the other main cations were not. Nickel could be recovered at the elution step. This methodology needs to be further investigated but these initial results are very encouraging and open the possibility of Ni recovery by agromining.

By Saeid Pournaderi, Ahmet Geveci, Ender Keskinkilic, Yavuz A. Topkaya

"This study investigated calcination behavior of one of the Turkish laterite deposits, which was recently found in Sivrihisar region. Representative limonitic laterite samples (1.26% Ni) taken from Yunusemre Karasivritepe and Kucuksivritepe location were first subjected to drying. Removal of chemically bound water and other volatiles were then studied, in detail. In the calcination experiments, temperature and time were the main experimental variables. Thermal treatment was conducted at the specific temperatures in 250 °C - 800 °C range. The weight losses due to elimination of chemically bound water and other volatiles were reported to be approximately 10 per cent of the weight of the ore. For the particle size used in the current work, 700 °C and 40 minutes were determined to be the optimum calcination temperature and time, respectively.IntroductionThe nickel ores that are economically valuable can be grouped into two categories: sulphide type nickel ores and oxide type nickel ores, namely laterites. Over all reserves in the world, 40% are sulphide nickel ores and the remaining 60% are laterites [1]. Pyrometallurgical nickel extraction from sulphide type nickel ores is conducted via matte smelting. More recently, laterite ore bodies have been subjected to nickel extraction. Depending mainly on the chemical composition of the laterite and the process economics, various extraction techniques have been implemented: pyrometallurgical route involves ferronickel smelting. High pressure acid leaching (HPAL) is the commercial method for hydrometallurgical nickel extraction, while ammonia leaching (CARON Process) is a combination of pyrometallurgical and hydrometallurgical processes [2]. With the improvements in these processes, it is predicted that laterite’s share in the world nickel production will rise to 50% in 2012, while it was reported to be 42% in 1,200,000 tons of annual production in 2003 [3]."

Jan 1, 2011

By T. -M. Guo, M. J. Braun

"This paper presents an experimental and numerical study of melt flow near the solid-liquid interface and its effect on the interface curvature in a horizontal unidirectional solidification system with succinonitrile. Melt flow is introduced by increasing the ampoule channel thickness. Visualization techniques are employed to observe the flow field and the solid-liquid interface curvature. A numerical model is also developed to simulate the heat transfer, melt flow and phase change in the system. Quantitative information on the flow and temperature fields is generated. A good agreement is achieved between the experimental observations and model predictions. The results could be used for the study of the effect of the melt flow on interface morphology during solidification.IntroductionClassic unidirectional solidification experiments of transparent alloys are conducted with thin film samples sandwiched between two glass slides to investigate the development of interface morphology during solidification [1]. Samples with small channel thickness are usually used to suppress any melt flow due to natural convection and solidification in the channel would then be in the diffusive regime so that the solidification theory can be significantly simplified [2, 3]. Effects of melt flow, in particular due to natural convection, on solidification have also been studied extensively in those systems with large geometrical dimensions [4-6]. These studies indicate a strong effect of the melt flow on interface curvature during solidification [5, 6]. Only limited efforts were made to address the effect of the melt flow on interface morphology in horizontal unidirectional solidification, in particular for the cases when the channel thickness is not thin enough to suppress completely the natural convection [7]."

Jan 1, 2004

By Edmundo Manilla, Merete Tangstad, Daniel Davila, Eli Ringdalen

FeMn alloys are typically produced with lumpy ore or sinters. Minara Autlan, the Mexican FeMn producer, is however making Mn-nodules as a raw material for Mn-alloy production. The Mn nodules have been characterized by XRF, XRD, by wet chemical methods and by EPMA. The Mn/Fe ratio is somewhat lower compared to commercial Mn ore on the marked. The basicity of the ore is however close to 1, and additional fluxes may not be used. The Mn-nodules will be in a state of manganosite (MnO), tephroite ((Mn, Ca)2SiO4) and galaxite ((Mn,Mg)Al2O4). This leads to a low melting temperature area. A low porosity and low amount of higher Mn-oxides gives a high thermal strength to the nodules.

Jan 1, 2016

By Jose Hector Figueroa P.

Mexicana de Cananea, S.A de C.V. is a major copper producer mining a large deposit of the disseminated porphyry type considered one of the largest copper resources of the world with 2.7 billion tons of 0.60% copper for the mill plus 4.1 billion tons of averaging 0.26% copper for leaching. Mining of low grade sulfide leach ore, has been an important part of the overall production of the open pit mine which started in 1944. Before this time all the mining in Cananea was by underground methods. The leaching process in Cananea began on the 1920's with in situ operations in the underground mine and small dumps up to the 1950's. Large scale leaching operations began in 1960 and the copper solutions produced were treated in precipitation plants until 1,980 when the first SX/EW Plant was put in operation in Cananea. Leaching action is essentially ferric-bacterial, with no fiesh acid added to the leaching solutions. Traditionally, 5540% copper extraction is recovered fiom ROM, 70- 120 meter high leach dumps in 80 months of leaching. Cananea has successfully improved copper recoveries by implementing several actions that include: 1. Stripping of old dumps. 2. Leaching of old dumps through slotted casing. 3. Crushing conveying leach ore to minus 8 inch and stacking it in 30 meter lifts. As result of these actions, copper recovery has been increased' to about 70% of total copper with actions 1 and 2 and up to 85% in half the time by crushing-conveying the leach ore, based on the same solubility index of the run-of-mine ore. This paper describes the above actions that were implemented to enhance the leaching recoveries from. sulfide leach dumps and the economics of such actions.

Jan 1, 1999

By S. K. Utimurd, D. C. R. Espinosa, J. A. S. Tenório

"Waste Electrical and Electronic Equipment (WEEE) has become an environmental issue due to technological advance and waste plastic is one of the main polluters. The excessive discard of these plastics result in a difficult to dispose it to landfill and need further separation with technique in order to produce high added value plastics. There are many kinds of plastics in extensive use at the present time and the co=on are the acrylonitrile-butadiene-styrene (ABS) and high impact polystyrene (HIPS) used in the production of electric appliances. These plastics are difficult to separate because they have similar densities. Flotation of plastics is one possible separation technique and using selective wetting agents. The separation may be possible given close control at particle size and the concentration of the reagent. The process was able to produce a concentrate of HIPS with at least of 93% purity and a concentrate of ABS with 99% purity.IntroductionThe current situation of municipal solid waste (MSW) management especially in emerging economies like Brazil, the growing population and economic activity will result in a significant increase in the generation of waste in the coming decades. It is worthwhile to review and update the sources, amounts and recovery technologies of specific materials from waste, particularly from municipal solid waste (MSW).The growing impact of the current waste management practices stresses the need for a change in how waste is handled. The 2012 survey and the Brazilian Association of Public Cleaning and Special Waste Disposal Companies (ABRELPE) reports the generation of 62 Mt urban MSW in that year, which is an increase of 13% compared to 2011. It has been reported that in Brazil about 90.17% of the generated MSW is currently collected, which indicates an increase in the coverage of collection services compared to 2011 [ l]."

Jan 1, 2014

By K. S. Raja, M. Misra, S. K. Mohapatra

"Ordered arrays of TiO2 nanotubular photocatalysts were prepared by a simple anodization process. Band gap states of the TiO2 were altered by controlling the anodization electrolyte composition and thermal annealing conditions that resulted in enhanced photo activity. These nanotubes were used for reducing CO2 to methanol either by photochemical or photo electrochemical routes. Pd nano-particle loaded TiO2 nanotubes were employed for photochemical reduction of CO2 to methanol that showed a conversion rate of 12 x 10-3 mol m- 2h-1. Carbon modified TiO2-xCx type nanotubes were used as photo anode and Ti as cathode for photo electrochemical reduction of CO2. The potential of Ti cathode was maintained at -0.5 V SCE. The formation rate of methanol was determined as 13 x 10-3 mol.m-2h-1.1. IntroductionGlobal warming due to emission of carbon dioxide is a serious environmental concern. The atmospheric concentration of CO2 is about 384 ppm by volume and about 3 x 1012 tonnes by weight. Burning of fossil fuels and deforestation are the leading causes for increase in the anthropogenic CO2. More than 32 x 109 tonnes of CO2 are released per year (based on 2006 data) worldwide from the fossil fuel. Pumping CO2 from the fossil fuel power plants into deep ocean basin is one of the most discussed disposal options. The other potential option is converting this green house gas into valuable fuels.Carbon dioxide feed stock can be converted into fuels of solid, liquid or gas phase by chemical, electrolytic, photocatalytic and photo-electrocatalytic methods. Reduction of CO2 to fuel form of any phase requires energy. The reduction process should be energy efficient so that we do not spend more energy and emit more (indirect) CO2 in the process of converting CO2. From this point of view, conversion processes occurring at room temperature look attractive.Electrolytic conversion of CO2 into various forms such as methane1, ethane2, ethylene3, methanol4,5, ethanol6, n-propanol, formic acid7, and formaldehyde has been widely reported. The standard equilibrium potential (at pH: 0) for reduction of CO2 to methanol is 0.14 VSHE and to methane is 0.2 VSHE which is thermodynamically more favorable than hydrogen reduction. However, the gas phase reduction is kinetically complex requiring effective electrocatalyst. The major issues with electrolytic conversion of CO2 to useful products are:"

Jan 1, 2010

By Debbie Marshall

Nickel and cobalt in lateritic ores can be extracted by either a hydrometallurgical or a pyrometallurgical route. The high-iron limonitic fraction of a deposit is best processed' hydrometallurgically while the magnesium-rich transitional and saprolitic fractions are more suited for pyrometallurgical processing. During hydrometallurgical processing, it may be attractive, for economic reasons, to blend the limonitic component with transitional and saprolitic ores, which contain higher nickel levels. However, blending increases the concentration of magnesium in the feed, leading to increased acid demands. The decision on how much ore to process then becomes an economic one. Ore samples with different magnesium contents were prepared for the leach test program by blending limonitic and transitional ores. The ore samples were slurried in seawater and tested in the Falconbridge Hydrometallurgical Pilot Plant. As expected, acid consumption increased with increasing magnesium content of the ore. For target extractions of 95% nickel and 92% cobalt, the required residual free acid concentration increased from 30 g/L at 1.7% magnesium to 50 g/L at 2.7% magnesium. When the magnesium content was raised to 3.8% and 4.6% in subsequent pilot plant testing, the final free acid requirements did not increase beyond what was observed at 2.7% magnesium. Thus, the cut-off ore composition to maximize nickel units and minimize acid requirements is between 1.7- 2.7% magnesium. Keywords: high pressure acid leaching, laterites, magnesium

Jan 1, 2004

By Hideo Nakae, Hideki Yamaura, Toshiaki Kimura

"In 1968 J. N. Reding et al. suggested processes for fabricating composites. According to their patent, decompression atmosphere, which occurs during the reaction between magnesium and oxygen and/or nitrogen in the closed system, causes the spontaneous infiltration of melt into narrow spaces such as ceramic preforms. However, they did not report the proof of this phenomenon or the industrial manufacturing method. Therefore, this research measured the pressure change among SiC particles surrounding molten aluminum. As a result, the pressure reduction during the Mg reaction was identified. Moreover, the existence of Mg3N2, which improves the wettability between Al alloy melt and SiC particles on the interface, was observed on the surface of particles. Applying these two phenomena, a new process for the manufacturing of cast discontinuously reinforced aluminum composites (DRA) was developed. This new method is expected to produce DRA without additional pressure.IntroductionWith the increasing demands for light-weight materials in the automotive and aerospace industry in recent years, ceramic particulate reinforced aluminum matrix composites called DRA (Discontinuously Reinforced Aluminum Composite) have been receiving significant attention because of its lightness, superior abrasion resistance, high heat conductivity and low thermal expansion [1-3]. Consequently, DRA was considered for electronic parts such as heat-sinks or a base for power semiconductors, and began to be applied for automotive parts including brake drums, discs, cylinder liners, pistons and so on [4- 6]. However, high machining cost is one of the significant barriers to widespread use ofDRA. One solution to this problem is the adoption of cast DRA that can be produce to near-net shape, reducing machining cost."

Jan 1, 2000

By Chonghun Han, Tae-Hwa Choi, Young-Hwan Chu

"A statistical optimization method is proposed to maintain stable operation in a blast furnace with stave coolers. The objective of this study is to find the operating condition which maximizes productivity as well as minimizes the heat load on the stave coolers. In this method, we first analyzed historical data and calculated the heat flux of stave coolers and the burden distribution by mathematical models. In this approach, we determined the variables to optimize and manipulated variables to adjust these response variables. Next, we collected the necessary data for the data variables after preprocessing such as removal of noise and outlier. Finally, we constructed empirical models describing the patterns of response variables in terms of manipulated variables by partial least squares regression method, and then these models were used as objective functions for entire optimization problem. By using appropriate optimization algorithm, we determined the compromised optimum operating condition considering all response variables from the past operating conditions.IntroductionBlast furnace operation which is accompanied by complex physical and chemical phenomena is an essential process for steel industry. In this process, iron ore which is charged into the blast furnace from the top goes downward. It is reduced to iron by CO gas and is melted by the heat of combustion of coke and pulverized coal. The pig iron is tapped at the bottom in liquid phase after removing the slag, which floats on the pig iron.The cooling equipment of the blast furnace wall is changed from the plate type to the stave cooler recently. In order to cool the shell uniformly and eliminate shell spray cooling, Pohang No.2 blast furnace of POSCO (Pohang Iron & Steel Company) was equipped with 11 rows of stave coolers. These staves are only 350mm-thick including the 170 mm-deep refractory on the hot face."

Jan 1, 2001

By Ralph P. Hackl

Bacterial leaching of the Doe Run Company?s cobalt/nickel-containing copper concentrate at low pH (pH 1.0-1.2) and high redox potential (>750 mV vs. SHE) enabled the cobalt and nickel to be preferentially dissolved over copper and iron due to the rapid passivation of the chalcopyrite component. Selective leaching of the cobalt and nickel was achieved with a mesophilic culture comprised mainly of Leptospirillum-like bacteria and Acidithiobacillus thiooxidans. This finding led to the conception of a novel hydrometallurgical process for passivating chalcopyrite and recovering the cobalt and nickel. The bacterial leaching process was tested extensively at the bench and pilot plant scales during 1997-1998. A pilot plant containing four leaching stages processed 30-40 kg/day of chalcopyrite concentrate continuously for 87 days. The cobalt extraction ranged from 75% to 86% during 6- and 8-day retention times respectively, whereas the copper extraction was limited to about 9%

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