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By D. B. Dreisinger

The zinc pressure leach process developed by Sherritt Gordon, Ltd. permits the direct leaching of sulphide concentrates according to the overall reaction, ZnS +H,zS04 +402.+ZnS04+H20 +S0 The kinetics of the leach are affected by three rate controlling steps; ( l) oxygen mass transfer from the gas to the leach solution, (2) homogeneous oxidation of ferric ion to ferric ion by dissolved 011.ygen and (3) ferric ion leaching of zinc sulphide in the presence of a sulphur dispersing detergent (lignin sulphonic acid). Fundamental studies have been conducted to identify the factors that influence the kinetics of each individual rate controlling step. Oxygen mass transfer studies have been directed toward optimization of the agitator configuration for solids mixing and gas pumping from the atmosphere above the leach slurry. The rate of ferrous oxidation by molecular oxygen and the rate of zinc sulphide leaching by ferric ion have been studied over a wide range of temperature and solution compositions. The study of zinc sulphide leaching by ferric ion was supplemented by a series of interfacial tension measurements in the liquid sulphur - zinc sulphate solution system. The various kinetic studies have been summarized in terms of the importance of each rate to the performance of the process.

Jan 1, 1990

By Sergio Neves Monteiro, Nuã Simonassi, Helvio Pessanha Guimarães Santafé Jr.

"Thermoset polymers, like the polyester, become harder with increasing temperature owing to molecular crosslink formation, which is a thermal benefit for composite matrix applications. Natural lignocellulosic fibers, however, have low thermal resistance and tend to degrade with increasing temperature. Therefore, the combination of a lignocellulosic fiber, as reinforcement, with a thermoset polymer, as the matrix, results in a composite material with complex thermal behavior. In the present work, a thermal analysis was conducted on polyester composites with different amounts of coir fibers. Both TGA and DTG curves were analyzed to determine the effect of the coir fiber on the thermal resistance of the composites. It was found that the coir fiber sensibly affects the thermal behavior of the polyester matrix for fiber amounts above 10% in volume. This effect is associated with an increase in thermal degradation.IntroductionIn recent years, there has been an increase application of natural fibers as reinforcement of polymer matrix composites in several industrial sectors, with special participation in automobile components [1-3]. Figure 1 illustrates the different components of a modem BMW sedan that are fabricated with lignocellulosic reinforced polymer composites."

Jan 1, 2012

By E. T. White, Dean Ilievski

"The population balance is one of the basic relations for analysing particulate mineral processing operations. It is an exact relation. The principles of the population balance are reviewed and applications in the minerals industry discussed.IntroductionMathematical modelling has proved to be a very successful approach for improving the design and performance of mineral processes, particularly since the availability of computers to handle the complexity usually necessary to give a useful model.Mineral processes almost invariably involve particles, as either solid fragments, liquid drops or bubbles. Process performance usually is highly dependent on the behaviour of these particles. In modelling particle behaviour, the basic relation to be used is the population balance. This paper discusses the role of the population balance and the range of its applications in minerals processing.The Population BalanceThe population balance was developed for demographic studies, ego predicting the change in the population (numbers) of, say, school children between one census and the next. The first sustained application to the processing industries appears in the 1960s for crystallization. However it was recognised almost immediately that it had application to all particulate processing."

Jan 1, 1996

By Thomas Niehoff

Many industrial processes require energy. Energy is required for melting or heating purposes. The heat can be generated by electrical heating or combustion/oxidation of hydrocarbons. Oxygen supports the combustion process. Oxygen is naturally contained in air with about 21 vol.-percent. The use of technical oxygen will allow an increase to the natural oxygen concentration of combustion air. Altering the combustion process by increasing the oxygen content has various effects. These effects are described and analyzed with regard to heat transfer, emissions and energy consumption. Industrial processes requiring oxyfuel are described and discussed regarding energy aspects.

Jan 1, 2008

By V. M. Paretsky

Oxygen-flame converting of a solid ground matte containing heavy non-ferrous metals in a wide range of concentrations is one of the perspective trends meeting the demands of modern non-ferrous metallurgy. As. a result, of semicommercial tests on oxygen-flame smelting of nickel matte containing 13,5-17,5% Ni; 0,45-0,65% Co under continuous autogenous conditions a converter matte containing 68 8-75,0% Ni and 0,48-1-,0% Co and ferrite -calcium slag containing 1,4-8,4 Ni and 0,16-0,56 Co were pro¬duced. Nickel recovery in a converter-matte was 76,2%, copper - 58,'2% and cobalt recovery in. a slag was 90%. Slag cleaning in an electric furnace allowed to after-recover nickel and cobalt in an alloy to produce a dumpy slag containing 0,03% Ni and 0,02% Co. The development of modern' ecologically pure energy-saving autogenous technologies of the treatment of sulphide raw materials containing heavy non-ferrous metals makes certain demands of the perfection of a process of converting rich sulphide-metallic intermediate products obtained at autogenous smelting. These-demands were connected first of all with the fact that converting process stages because of process periodicity are more unfavourable from the point of ecology, power intensity and unit stability. Besides, during rich matte treatment the problems connected with heat shortage when using air blast and heat excess-when using top oxygen blast to treat luquid matte a-rise and when enriching air blast by oxygen up to 26% fast erosion of the brickwork of a tuyere zone takes place. The technology of Outokumpu and Kennecott companies-on solid- copper matte converting in a flash smelting furnace using air blast is not universal as its possibilities are limited by certain composition of mattes. Besides, flash smelting to produce highly basic or combined slags requires larger enrichment-of blast by oxygen or extra fuel feed. Naturally a flowsheet with continuous converting of matte of various composition up to white matte production is simple,

Jan 1, 1993

By C. Mattich, A. L. Beyzavi

The Waelz Plant at Taiwan Steel Union Co. Ltd. (TSU) was erected within nine months from September 1, 1998 to May 15, 1999. The nominal capacity of the plant is 50,000 tonnes per year of electric are furnace dust (EAFD). The plant, consisting of material handling, a waelz kiln, a waste gas cleaning system, waelz oxide leaching and waste water treatment, was commissioned within three months from July 1, 1999 until October 12, 1999. The specific problem of the plant is the high chlorine content in the EAFD pellets which is up to 6 %. Lurgi Metallurgie GmbH, Frankfurt, Germany was responsible for the engineering erection and commissioning of the plant.

Jan 1, 2000

By Ruiqing Li

It is possible to purify some liquid metals by exploiting the difference between the vapour pressure of the bulk metal and the minor constituents or impurities. The rates of purification can be improved by carrying out the process under reduced pressure, that is, so called, vacuum. Some commercial examples of vacuum refining are the purification of molten tin to eliminate trace amounts of lead and the refining of cobalt, also to remove lead. The objective of this paper is to review the basic theory behind vacuum refining technology in order to show how the feasibility of vacuum refining can be determined simply for a particular system by evaluating Olette's Volatility Refining Criteriont.

Jan 1, 1991

By Alice Barreto Bevitori, Frederico Muylaert Margem, Renan Sopeletto Carreiro, Sergio Neves Monteiro, Isabela Leão Amaral da Silva

"The ramie fiber is one of the strongest lignocellulosic fibers with applications ranging from simple items such as fabrics and ropes to engineering composites for automobile parts and building panels. Characterization of the ramie fiber has recently been conducted for physical and mechanical properties. In principle, thinner ramie fiber could be comparatively stronger and consequently more effective as a composite reinforcement. In this work an attempt to correlate the ramie fiber elastic modulus obtained in tensile test with its corresponding diameter, precisely measured by means of a profile projector, was carried out. Tensile results analyzed by the Weibul1 statistic showed a significant increase in elastic modulus with decreasing the diameter of ramie fiber. Scanning electron microscopy observation of the fracture of selected ruptured fiber revealed possible mechanisms that could justify the elastic modulus/diameter inverse dependence.IntroductionEngineering applications of natural fibers obtained from cellulose-rich plants, also known as lignocellulosic fibers, are currently being the focus of attention. In fact, they are considered an enviromnental1y correct alternative to substitute synthetic fibers such as the glass fiber, associated with an intensive intake of energy during production, as reinforcement of polymer composites [1-4]. In recent years there has been a growing tendency towards the use of lignocellulosic fiber composites in several industrial sectors from civil constructions to car making. In particular, the automotive industry is expanding the number of both interior and exterior components made of natural fiber composites [5]."

Jan 1, 2012

By B. Farouk, D. Apelian

"A numerical model has been developed to predict the temperature history of particles injected in a low pressure d.c. plasma jet. The temperature and velocity fields of the plasma jet are predicted as a free jet by solving the parabolized compressible Navier-Stokes equations using a spatial marching scheme. Particle trojectories and heat transfer characteristics are calculated using the predicted plasma jet temperature and velocity fields. Correction factors have been introduced to take into account non-continuum effects encountered in the low pressure environment. The plasma jet profiles as well as the particle/plasma interactions under different jet pressure ratios (from underexpanded to overexpanded) have been investigated.I. IntroductionIn the plasma spraying process a d.c. plasma jet is used as a heat source to melt and accelerate powder particles which subsequently impinge and solidify on a given substrate. During low pressure plasma deposition (LPPD) prooess, the plasma jet is expanded into a low pressure environment (40-80 Corr) which results in high plasma jet velocities with Mach numbers ranging from 2 to 3. Previous efforts to predict heat transfer and fluid flow in plasmas have made use of incompressible flow formulation employing turbulence models [1-3] for atmospheric plasma spraying. However, these theoretical calculations have been limited to the subsonic flow regime; hence, the compressibility effects and viscous heat dissipation were neglected. In the LPPD process, the plasma jet is operated at the supersonic flow regime, therefore, the compressibility effects and viscous heat dissipation are no longer negligible. This is the main motivation of this work.In addition, production of high quality dense deposits requires that a large fraction of the injected particles be in a molten state when they impact the substrate. An additional motivation for this work is that it is important to understand the plasma/particle heat and momentum transfer since these phenomena dictate both the particle thermal history and particle trajectory.Early computational works in supersonic nozzle field flow [4,5,6] consisted of patching methods that divided the flow field into an invisoid free stream and a viscous boundary and. mixing layers. Each was analyzed independently and coupled through appropriate boundary conditions. Later schemes [7,8] involved solving time-dependent, compressible Navier-Stokes equations over the entire computational domain. These schemes show a great promise in predicting flows with complex structure, and where the viscous effects became prevalent."

Jan 1, 1986

By Glenio F. Daniel, Vinícius O. Barbosa, André R. Gomes, Sergio N. Monteiro, Victor B. de Souza, Frederico M. Margem

Nowadays notorious technological growth is encouraging research natural materials in substitution to more usual synthetic ones. One of those initiatives is the vegetable fibers that have been studied for the replacement of glass and carbon fibers. This research addresses broadly the study of the natural fibers mechanics properties, but none study have been made with natural fabrics, such as the pure jute fabric used in Brazil to make ropes and carpets. This work aim to evaluate the mechanical behavior of jute fabric strips with different dimensions to be used as reinforcement into polymeric composites Lots of those fabric strips were subjected to tensile tests in order to obtain the tensile resistance for each strip size. The results obtained during the tests were satisfactory and indicated that 160 × 160 × 1 mm correspond to the best result and the perfect fabric strip for the composite reinforcement.

Mar 1, 2017

By Adolfo Pillihuaman Zambrano

Fe-Cr-C production is a very high electrical energy consuming process. Decrease up to 10% of this electrical energy is expected when self-reducing agglomerates are used. This research aims to understand how the synergetic effects are when stronger reductant, like Fe-Si, is substituted for coke in self reducing pellets. Brazilian chromites containing 41.2%Cr2O3 were mixed with petroleum coke and agglomerated with cement as the binder. Small amounts of 1%, 2% and 4% of Fe-75%Si were substituted for the equivalent petroleum coke, and pure silica plus hydrated lime were added for adjusting the slag composition. The mixture was pelletized, dried and submitted at 1773K up to complete the reactions. The results showed that the reduction reactions were 1.4 and 2 times faster with 1% and 2%Fe-Si addition, respectively, than with no addition. The microscopic analysis showed that it was formed a liquid phase, but the pellet did not collapse what indicates that the coalescence of the metallic phase depends on the dissolution of the pre-reduced particles of the chromites into slag.

Jan 1, 2008

By Chenhui Liu, Hong-ying Xia, Bingguo Liu, Wei Li, Jinhui Peng, Libo Zhang

"Dielectric property is an important limiting factor in the development of microwave processing of minerals and ores. In this study, we used an open-ended coaxial sensor method to measure the complex permittivity of an ilmenite concentrate (41%TiC>2) and microwave absorption properties from room temperature to 100°C. The results show that the dielectric constant, loss factor and loss tangent increase with temperature rising at 2.45GHz. Microwave absorption properties of this ore are highly dependent on temperature and frequency. Ilmenite concentrate can be used as raw materials to prepare wideband microwave absorbing material. The research will be helpful in explaining the thermal running of microwave dielectric heating the ilmenite concentrate.IntroductionAs the sources of high-grade titanic mineral are decreasing worldwide, the utilization of low-grade minerals such as ilmenite has attracted more attention [1,2]. Because Panzhihua ilmenite has complex minerals and high contents of MgO, CaO, S1O2 , it is difficult to upgrade the ilmenite to titanium-rich slag and farther produce synthetic rutile and titanium dioxide pigment [3]. Therefore, it is desirable to develop new technology for processing ilmenite ore [4]."

Jan 1, 2012

By Shinya Otsuka

Activity coefficient of oxygen in sulfide-rich and metal-rich melts in copper-sulfur binary were determined at 1423 and 1523 K by means of a modified coulometric titration technique using the following cell: 0 ( is Cu-S melts) I Zr02 (+Ca0) I air, Pt The activity coefficient values obtained in the present study increase rapidly with sulfur composition in the vicinity of xs = 0.3333. The data obtained for the matte saturated with the metal-rich melts are in good agreement with those obtained by Kuxmann and Benecke, Schmied 1, and Eguchi and Yazawa. Those obtained for the metal-rich melts are in good agreement with the results of Sano and Sakao.

Jan 1, 1983

By I. Gaballah

The kinetics of oxychlorination of pure CI-2O3 with C12+02 gas mixtures is studied by ThermoGravimetric Analysis (TGA) in non and isothermal conditions up to 1000 °C. The reaction of Cr2O3 with C12+O2 chlorination gas mixtures starts at about 550 °C and the reaction product is CrO2Cl2. The oxychlorination rate of Cr2O3 is almost proportional to the chlorine partial pressure and to the fourth root of the oxygen partial pressure in the chlorinating gas mixtures. At 800 °C, the maximum chlorination rate is obtained using a gas mixture having a C12/O2 ratio equal to 4. The apparent activation energy of the oxychlorination reaction of Cr2O3 is 87 and 46 kJ/mol at temperatures lower and higher than 650 °C, respectively. By varying the chlorine and the oxygen partial pressures of the oxychlorinating gas mixtures at temperatures higher than 550 °C, it is possible to extract selectively the chromium chlorinated compounds from the chromium bearing materials. a. Laboratoire Environnemem et Minéralurgie, BP 40, 54501 Vandceuvre, France, b. École Nationale Supérieure de Géologie, Rue du Doyen Marcel Rouhault, 54501 Vandoeuvre Cedex, France, c. Centre National de la Recherche Scientifique, 3 rue Michel - Ange, 75794 Paris Cedex, France, d. Insritut National Polytechnigne do Lorraine, Rue de la Font de Haye. 54501 Vandceuvre Cedex, France.

Jan 1, 1997

By Nicola Baldo, Marco Pasetto

"The paper presents the results of a laboratory study, conducted at the Experimental Road Laboratory of the University of Padova, in order to verify the possibility to use different types of electric arc furnace (EAF) steel slags – in substitution of the natural aggregates – in the composition of both dense graded and porous asphalt mixes for flexible road pavements. The research has been articulated in a preliminary study of the chemical, physical, and mechanical properties of the EAF steel slags, and in the following mix design and performance characterization of the bituminous concretes, through stiffness modulus tests at various temperatures and permanent deformation (creep) tests. All the mixtures with EAF slags have satisfied the requisites for acceptance standardized for the road sector, thus resulting as suitable for use in the construction of infrastructures, moreover presenting higher mechanical characteristics than those of the corresponding asphalts with full natural aggregate. IntroductionSteel is produced industrially employing two main technologies: the integral cycle, which starts from mineral iron, and the electric cycle, which uses scrap metal. A consistent amount of the steel produced in Italy (approx. 55%) comes from Electric Arc Furnaces (EAF), which every year, alongside the steel, produce approximately 2 million tons of slag. The recycling of this waste product to produce new high-quality raw materials would reduce both the exploitation of limited natural resources and the amounts of refuse. In the European Union, 60% of slag from EAF is still today disposed of in dumps. The extremely diverse origins of scrap metal (waste from mechanical manufacturing, industrial and civil demolition, car bodywork, etc.) means that the by-products generated by the smelting, slags and ashes, contain different elements, in varying composition, also depending on the type of steel to be produced and the consequent adding of binding and melting elements during the production process. For this reason, iron and steel industry electric furnace slag - unlike the blast furnace dross utilised in cement works, which has a more uniform composition as it comes from a more standardised cycle – has been viewed in the past with some diffidence and so, at least in Italy, the possibilities of its re-use have never been fully developed."

Jan 1, 2008

By Tseng. B. H.

Samples of unchlorinated and chlorinated carbonaceous concentrate from a carbonaceous gold ore were analyzed by transmission electron microscopy (TEM) for organically bonded sulfur and chlorine. The concentrate assayed 1.53 oz/t gold and 6.01% organic carbon. Much of the organic carbon occurred as sizable coarse particles up to several hundred microns in size, which showed no visible evidence of reaction with chlorine after chlorination treatment. Both the untreated and chlorinated fractions of the carbonaceous concentrate were analyzed by the TEM method, which detected organically bonded sulfur in all of the carbon particles examined in the untreated sample, ranging from about 1 to 5% organic sulfur, and averaging near 3.1%. TEM analysis of 40 carbon particles in the chlorinated sample indicated that organic sulfur was reduced significantly in the carbon and replaced in part by the chlorine, as the result of chlorination.

Jan 1, 1987

By A. R. G. Azevedo, G. C. Xavier

"This work has for objective to identify the soil of the neighborhood Codin located in a lacking area of the urban nucleus of the district of Campos dos Goytacazes - RJ, after the identification the best line was determined for the production of soil-cement blocks. In this area it happens habitational deficit and precarious constructions are also verified. The use of soil cement blocks is considered a cheaper constructive method than the conventional (ceramic block or of concrete), because one of the components of the raw material is abundant (the soil) and the constructions can be erect with certain easiness for collective effort regime. Samples of soil of this area were collected for they be characterized with relationship to the physical and chemical characteristics, with I aid of GPS the community's location it was registered. Identified the soil type, the work began the study of lines they to make possible your use in an economical and safe way. For that were made drained blocks in the format 19,5x10x5 cm, with lines containing the addition of 5% and 10% of cement in volume, and as parameter of quality the absorption of water and the resistance to the compression were measured, following the Norms of ABNT.IntroductionWe know that the use of the soil by the humanity come from the antiquity. And ifs confirmed by the archaeology places of the old civilizations of the word. The most remote constructions date from 10.000 years old in Jericoh, in the Jordan River Valley. This work became more intensive at 3.000 B.C. (Before Christ), by people who lived in those valleys with mood areas, a lot of clay and washed by the rivers.Almost all the sectors of engineering of soils choose the stability to use the local soil. Although, artificially treated, offers more economical advantages.The stability of a soil consist of endow it of the condition to resist the deformations and ruptures during the period that it is being used, because these characteristics are necessary in any construction.The application of the natural soil only is possible in places that they are of good quality and attend to the requirements of engineering to the type of previewed application. The granulemeter correction and the chemical stability include cases of inappropriate soils areas, turning the soil able to be used as construction material. Among the stability agents, usually added to the soil for stability ends, the cement is indicated."

Jan 1, 2013

By Noritaka Horii, Katsuyoshi Kakinuma, Hiroshi Yamamura

"ZrO2 and Y2O 3-doped ZrO2 gel film were obtained by spin coating of sol from Zr-n-propoxide, n-propanol, acetylacetone, nitric acid, and water on a silica glass as a substrate. ·Dried gel films crystallized to monoclinic, tetragonal, cubic and their mixed phases, depending on the chemical composition of sol, .firing temperature, and coating cycles. ZrO2 films with highly preferential orientation were successfully obtained from a solution containing a large amount of n-propanol. The highly oriented ZrO2 film was found to have high transparency compared with non-oriented 'films. Electrical conductivity of 8 mol% Y2O 3 doped ZrO2 film was also measured.Introduction3 mol% Y2O 3 doped ZrO2, which has a tetragonal symmetry is ·well known to have a strong mechanical property and a high toughness. (1) On the other hand, 8 mol % Y 2O 3-doped ZrO2 is high oxide-ion conducting material and is applied to oxygen sensor, oxygen pump, and solid oxide fuel cell (SOFC). (2) Sol-gel methods using metallic alkoxide are widely applied for synthesizing ceramics such as high-purity fine particles, thin film, and fiber. (3) For ceramics films, many reports have been made on SiO2, (4) TiO2, (5) and PZT. (6) Several case studies have been done on zirconia film based on the sol-gel method, (7) - (11) but very few on preferentially oriented film and on systematic Y zO3 doping. Almost zirconia ceramic· films reported were prepared by means of dip-coating. Kamiya et al. (12) and Ganguli et al (13) converted zirconia into fiber. Sol from Zr alkoxide is usually very unstable, and a stabilizing agent such as glycol or ß-keton is used beforehand (7) (14)."

Jan 1, 2000

By K. B. McTaggart, G. Owusu, P. J. Merrin

"This study was conducted at Hudson Bay Mining and Smelting's zinc electrowinning tankhouse to determine the effects of varying levels of antimony and continuous gelatin addition on current efficiency. The levels of antimony and gelatin were varied from 0.012 to 0.030 mg/l and 0 to 10 mg/ll2 • 31 respectively, based on neutral ZnS04 electrolyte. A non-linear mathematical model relating current efficiency with antimony and gelatin was produced. The optimum operating point for gelatin was 6.5 mg/l. On the other hand the current efficiency increased with decreasing antimony levels. An interaction term between gelatin and antimony is present but is not significant enough to improve the ability of the tankhouse to handle purification upsets in antimony. Individually, the current efficiency was linear (decreasing) with antimony, and parabolic with gelatin concentration. However, at low antimony concentrations stripping of the cathode sheet was difficult. IntroductionThe zinc electrowinning tankhouse at Hudson Bay Mining and Smelting was designed in the 1930's and consists of 120 rows with each row containing ten cells. This system cascades acid from cell to cell In a row, with neutral zinc sulphate solution added to each cell through manually controlled spigots. Animal glue additions are made manually three times per day by operations personnel. The problem with this type of cell design and operation is that feed solution flows and composition can vary from cell to cell and from row to row due to the large number of manual control points. A new system which reduces the number of manual control points was designed and tested to determine if improvement in control of cell conditions would affect current efficiency. This system mixes spent acid, neutral ZnS04 electrolyte and reagents (gelatin, antimony and strontium carbonate) in a separate mix tank, ensuring that all cells receive a uniform feed solution. Gelatin was used in the test system instead of animal glue (which is presently used) because of the poor solubility and supply of industrial animal glue. The study reported here is the first in a series of experiments designed to justify the need to modify the present cascading cell feed system (Figure 1) to the proposed feed system (figure 2)."

Jan 1, 1997

By Wankun Wang, Shixing Wang, Jinhui Peng, Zebiao Zhang

"Germanium leaching from germanium dust and fume was carried out using sulphuric acid. Response surface methodology (RSM), based on a five level, four variable central composite design (CCD), was employed to obtain the best possible combination of liquid/solid ratio (Xi: 2-10), leaching time (X2: 1-5 h), sulphuric acid concentration (X3:3.15-15.75mol/L) and leaching temperature (X4:50-90 *C) for germanium leaching. The obtained experimental data were fit to a one-order polynomial equation using multiple regression analysis and also analyzed by analysis of variance (ANOVA). The 3-D response surface plot and the contour plot derived from the mathematical models were applied to determine the optimal conditions. The optimum extraction conditions were: liquid/solid ratio of 10, leaching time of 1 h, sulphuric acid concentration of 15.75 mol/L, and leaching temperature of 87.8 'C. Under these conditions, the germanium leaching extent was 65.14%, which is in close agreement with the value predicted by the model. The samples were characterized before and after leaching using X-ray diffraction (XRD).IntroductionResponse surface methodology (RSM) is one of the relevant multivariate techniques which can deal with multivariant experimental design strategy, statistical modeling and process optimization [1-15]. It is used to examine the relationship between one or more response variables and a set of quantitative experimental variables or factors. This method is often employed after the vital controllable factors are identified. It is also used to find the factor settings that optimize the response. Designs of this type are usually chosen when a curvature in the response surface is suspected [6], The process optimization of the sulphuric acid leaching of germanium from germanium dust and fume has not been reported in the literature. Hence the present work intends to assess the effects of variables such as liquid/solid ratio, leaching time, sulphuric acid concentration and leaching temperature and to identify the optimum conditions using RSM. The characteristics of sample before and after leaching are assessed using the advanced analytical instruments such as X-ray diffraction (XRD)."

Jan 1, 2012