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By Vinay Kumar, Jae-Chun Lee, Abhishek Kumar, Manis Kumar Jha

However, India is rich in ores and mineral, but E-waste recycling is necessary due to the report of national and international studies, which cautioned on the generation, treatment and accumulation of e-waste in India. Current data indicate that the total domestic e-waste generation including imports is around 382979 MT, however waste available for recycling and actually recycled are 144143 MT and 19000 MT, respectively. In which recycling by non-formal and formal sector are 95% and 5%, respectively. On the other hand, India has developed expertise in handling verities of metallic wastes in an organized and safe manner. The development of individual process or combined processes for handling the e-waste is underway. Eco- friendly and energy-saving processes are necessary to comply with stringent environmental regulations. The paper includes the recent trend of e-waste generation, recycling process and its future prospects particularly in India.

Jan 1, 2011

By Javier Antoñanzas, Juan Carlos Múgica, Lourdes Yurramendi

The gasification of wastes containing an organic fraction is usually performed at low-medium temperature using different kind of catalysts. The off gas obtained is a mixture of carbon oxides, mainly carbon monoxide, and hydrogen and can be used for different energetic applications. The main problem is the production of tars in the off gas that has to be separated from the valuable gas flow and, finally, treated separately. An interesting alternative is the partial or total treatment of organics at high temperature. In this case, the off gas contains a higher content of hydrogen and elemental carbon as particulate matter. The energetic source to obtain a temperature in the range of 1,000 - 1,200 ºC is obtained by a plasma torch. In order to make de process attractive, an important issue to be considered is to commercialize the carbon obtained for different industrial applications.

Jan 1, 2008

By W. John Rankin

Professionals, technical and non-technical, working in the mineral and metal commodity industries need to understand the concept of sustainability and its implications for the industry. Undergraduate courses have not done this well in the past. Much has been written in this field, and there have been great advances in understanding. However, much of what has been published is superficial and sometimes misleading, and there is as yet no coherent, single account that can serve as an introduction or overview for mineral industry graduates. This paper presents an outline which can guide readers in developing an understanding of the topic and its relevance to their work. Key references are provided, particularly those accessible on the internet, which will serve to introduce the reader to the important principles and understandings. The guide should also be useful to academics preparing students to work in the minerals and metal production sectors.

Jan 1, 2010

By P. Umadevi

In the light of the discovery of the new super-conducting YBa2Cu3O7-x (YBCO), reactions in the Y2O3¬CuO-BaO system at 1300°C was investigated. The search was for any new phase that may be formed in the system at 1300°C (only 950°C reactions are known so far). 35 mixtures of different compositions were prepared and heated at 1300°C. No new phase was obtained. It was found that YBCO is decomposed at this temperature and Y2O3 and BaCO3 are the major components in the solid obtained after firing in air. However, on cooling the melt slowly and annealing at 950°C YBCO reforms. Such reactions on cooling might have implications on processing of the superconductor YBCO for practical applications as well as on its crystal growth by flux method.

Jan 1, 1989

By John O. Marsden

In early 1998, Phelps Dodge embarked upon a program to investigate alternative technology for the extraction and recovery of copper, and other metal values, from copper concentrates. A review of all of the available process alternatives indicated that many were unsuitable for large-scale commercial application and others were clearly targeted at niche applications where contaminants (and consequently smelter penalties) were driving the decision-making. The result of this development program is the world?s first commercial application of high temperature pressure leaching of chalcopyrite concentrate at Bagdad, Arizona, which was commissioned in the second quarter of 2003. Other related processes are in various stages of development. In addition to the obvious considerations, the economic aspects of this technology have been considered in detail at each step in the development of the program. The technology developments in this area are reviewed with emphasis on the economic viability and commercial application.

Jan 1, 2003

By Weyman Dunaway

This paper will present a description of the development and commissioning of the world?s most efficient process for manufacturing high purity aqueous zinc bromide. The method for making aqueous zinc bromide from metallic zinc and bromine comprises contacting zinc with bromine dissolved in a reaction solvent containing a metal halide salt. The reaction temperature is maintained at less than 60°C. The reaction solvent preferably comprises an alkali, alkaline earth, or transition metal halide; the halide salt preferably comprises a chloride or a bromide. One preferred method includes the step of recirculating the zinc bromide product stream back to the reaction vessel. The reaction vessel can be either a one stage or a multiple stage reactor. The resulting product stream is a high density aqueous zinc bromide solution. The process is so novel that Tetra Technologies, Inc. was awarded US Patent Number 6,036,937.

Jan 1, 2006

By E. A. Román

An ion exchange pilot plant, provided by Mesco Inc., was tested for antimony control in the electrolyte at three Chilean tankhouses for copper electrorefining: Chuquicamata, Potrerillos and Enami -Ventanas. The pilot plant, with a nominal extraction capacity of 1.2 kg Sb/day, worked connected to both experimental and commercial circuits, performing a total of 310 loading and elution cycles. An innovation in this process is the use of a chelating organic elution reagent, which presents some advantages over the traditional 6N HCI. This new eluent is amenable to continuous regeneration and recycling with high recovery efficiency. Antimony removal starting at initial, concentrations of 0.5 to 0.6 g/l of Sb down to steady concentrations of 0.1 to 0.0.6 g/l Sb, resulted in the production of High Grade copper cathodes with Sb contents below 0.1 ppm. Anodic slimes showed Sb contents below 1%.

Jan 1, 1999

By Naoki Hiroyoshi

It is generally accepted that ferric ions are effective for leaching chalcopyrite as an oxidant and ferrous ions contribute to the leaching only as a source of the oxidant ferric ions. However, this paper shows that ferrous ions are more useful for leaching chalcopyrite than oxidant ferric ions in sulfuric acid solutions in air at ambient temperatures. Leaching experiments and dissolved oxygen consumption measurements were carried out with a very pure chalcopyrite and 0.001 - 1 mol dm-3 sulfuric acid solutions containing 0 - 0.1 mol dm-3 ferric or ferrous ions at 303 K. Chalcopyrite oxidation with dissolved oxygen was promoted by ferrous ions but suppressed by ferric ions. As a result, the amount of extracted copper was larger with ferrous ions than with ferric ions. Effects of Thiobacillus ferrooxidans on the ferrous promoted chalcopyrite leaching were also investigated and discussed based on the experimental data.

Jan 1, 1999

By Heikki Jalkanen

Oxygen converting of hot metal (LD/BOF) is contemplated as an object of simulation. Oxygen converting is a highly complex thermo-chemical process comprising a series of matter and energy transformation and transportation steps that makes the simulation very challenging. The basic principles of CONSIM 5 oxygen converter simulator are presented. Simulator is a comprehensive combination of a physical model with several empirical submodels describing all properties and processes that affect the final result of a converter blow, final mass and composition of steel, slag, dust and converter gas as well as the end temperature of steel. CONSIM simulator is used for simulation of series of high and low carbon steel blows. Simulated steel temperatures, oxygen consumption, blow time and iron oxide content of slag are compared with measured values. Problems of simulation and requirements for quantitative simulation of oxygen converter process are discussed.

Jan 1, 2006

By L. B. Tsymbulov

Sulphide melts formed in the course of smelting of nickel and copper-nickel feed (matte) actually are sulphide-metallic melts since sulphur contained in the melts is in deficiency with respect to metals. The level of metallization is rather relevant feature of sulphide melts and is widely used in calculating material and heat balances for pyrometallurgical processes. Despite of the above parameter? importance, the investigators have no single opinion on what should be understood under metallization level and the method of its determination. In the present study we present the results of our own experimental and theoretical researches that have allowed determination of some mechanisms of sulphide melts? crystallization. Based on the mechanisms revealed new scientifically justified approach has been offered for determining level of metallization of the components present in sulphide melts. It has been demonstrated that sulphur distribution between the melts is substantially different from generally accepted concept.

Jan 1, 2006

By Joël P. T. Kapusta

Although Peirce-Smith converting remains the workhorse in matte converting, the copper and nickel industries are still confronted with production hindrances such as tuyere blockage, excessive refractory wear and limits in the oxygen enrichment levels of the blast air. The knowledge acquired on high-pressure gas injection technology as well as the invention of the concentric tuyere for steelmaking led to the development of the Air Liquide Shrouded Injector (ALSI) technology for copper and nickel converting. Following a technology demonstration in 1997-98 with four shrouded injectors installed in a Peirce-Smith converter, Falconbridge Limited implemented ALSI Technology on a commercial scale in May 1999 as an integral part of its new Slag Make Converter at Sudbury, Ontario, Canada. The paper presents the various aspects of commissioning ALSI Technology, as well as the operating changes and injector design modifications over the five years the shrouded injectors have been in operation.

Jan 1, 2005

By Jose Luis Lopez Mendez

In May 1992, MEXICANA DE CANANEA, S.A. DE C.V. finalized the life of its Reverberatory Furnace which lasted 16 years. This created the need to prepare the Smelter for the next campaign.

Jan 1, 1994

By Z. Sun, H. A. Davies

"Current understanding of the mechanisms by which glassy and crystalline thin ribbons are formed in high speed continuous casting processes is considered. A computer model of the combined heat and momentum transfer during melt spinning has been developed. The influence of roll velocity and of heat transfer coefficient (between the melt and the roll) on the temperature and velocity distributions within the melt puddle is analysed and the thickness of the extracted ribbon computed. The relative importance of heat and momentum transfer under different conditions is assessed and differences between the casting of crystalline and amorphous strip highlighted.IntroductionHigh speed continuous casting of thin metallic ribbon and strip is currently of considerable interest both to metal processers and to those studying process mechanisms. The practical interest arises both from the potential economic benefits to be gained from a shorter and more energy-efficient production route and from the ability to obtain extended and uniform thin strip having a metastable microcrystalline or amorphous structure with enhanced or unique properties. The latter arise from the rapid solidification associated with the cooling of very thin sections of melt brought into intimate thermal contact with one or two rapidly moving heat sinks.The principal processes for casting thin strip include free jet, chill-block melt-spinning (GBMS) (1), melt drag (MD) (2), planar flow casting (PFG) (3) and twin-roll casting (TRG) (4). For the first three of these, all essentially variants of melt-spinning, melt flows through a nozzle onto the circumferential surface of a rapidly rotating roll, whereas for TRG the melt passes into the nip between two contra-rotating rolls. We shall be concerned in this paper with the single-roll melt spinning processes only. For these, a puddle is established where the melt contacts the roll surface and the length of this puddle l is a function of the process conditions, notably the circumferential velocity of the roll Us and the volumetric flow rate of the melt Q. The contact time between any point on the roll surface and this puddle, or residence time eR(= l /Us) determines the thickness of ribbon t extracted from the puddle. This thickness, in turn, partly governs the cooling rate T and the amount of undercooling in the melt and thus the microstructure of the solidified ribbon."

Jan 1, 1986

By Neng-Wen Yu, Shau-Jun Zhu, Ji-He Wei

The desulfurization process by powder injection and blowing in the RH refining of molten steel and its mechanism have been considered and analyzed. Based on the two-resistance mass transfer theory and the mass balance of sulfur in the system, a kinetic model for the process has been developed. The related parameters of the model, including the mass transfer coefficients and the effective amount of powder in the molten steel being treated for desulfurization, have been more reasonably determined. Modeling and predictions of the process of injecting and blowing the lime-based powder flux under assumed operating modes with the different initial contents of sulfur and amounts of powder injected and blown in a RH degasser of 300 t capacity have been carried out using the model. The relevant circulation rate of the liquid steel and the powder injection and blowing rate were taken to be 100 t/min and 150 kg/min, respectively. The initial contents of sulfur in the liquid steel to be treated and the amounts of powder injection and blowing were respectively assumed to be 0.007, 0.006, 0.005, 0.004, 0.003, 0.002 mass-% and 10, 8, 6, 5, 4, 3 kg/t-steel. The total treatment time for desulfurization under each mode was set up at 24 min, equivalent to eight circulation cycles of the liquid steel to be treated. The results indicated that the predictions made with this model are in good agreement with some data of the industrial experiments and practice. Injecting and blowing the lime-based powder flux with the composition of 85 mass-% lime (CaO) + 15 mass-% fluorspar (CaF2) of 3-5 kg/t-steel, it is possible to decrease the sulfur content in the molten steel to ultralow level below (5-10)x10·4 mass-% from (60-80)x 10·4 mass-%. The total treatment time needed will appropriately be 12-20 min. Intensifying the powder injection and blowing operation and increasing the circulation rate of the liquid steel may effectively' raise the rate of the process in RH refining. The model may be expected to offer some useful information and a reliable basis for determining the reasonable process parameters and help in optimizing the technology of desulfurization by powder injection and blowing in the RH refining of molten steel.

Jan 1, 2000

By James M. Fragomeni

"The mechanical behavior of an Al-Li alloy was studied and related to the extrusion processing parameters, the plastic metal flow during defonnation, the anisotropy, and the microstructure. The extrusion temperatures, strain rates, extrusion ratios, billet temperatures, and extrusion geometries were varied during processing and correlated with the microstructure and properties. The extrusion processing variables were related to the mechariicar behavior, anisotropy, and microstructure through the ZenerHollomon parameter i.e., the temperature compensated strain rate. Based on optical and electron microscopy studies it was found that regardless of the extrusion conditions, the various microstructures for the most part were unrecrystallized for both the as-extruded and the solution heat-treated conditions. Smaller grain sizes were correlated to larger Zener-Hollomon parameters. The extrusion temperature and ratio did not significantly affect the strength or ductility as did the section geometry, which had a large affect on these mechanical properties. The anisotropy of the properties varied substantially when comparing the extruded longitudinal versus transverse grain orientations.IntroductionThe extrusion process also has a substantial influence on: the microsfructure and mechanical properties of a material that is Athens, Ohio, 45701 fonned The plastic defonnation that occurs during the extrusion process alters the grain size, crystallographic texture, anisotropy, subgrain size, dislocation density and various other microstructural features. Often the material being extruded is not homogeneous, therefore variations in the microstructure and properties occur across the cross-section of the final extruded product. The mechanical properties and microstructure can also vary with length since it is hard to maintain a constant temperature throughout the extrusion process. The extrusion temperature often varies from the heat generated during the extrusion process. The demonstration material that was extruded for this .study was an aluminum alloy containing 2.6wt, % lithium and 0.09wt.% zirconium. This alloy was strengthened by heat treatment causing nucleation, growth, and coarsening of coherent metastable o' (Al3Li) precipitates in the microstructure. The ? precipitates which are a consequence 9f artificially aging the AlLi alloy, are spherical, ordered, and coherent with the aluminum matrix and impede the dislocation glide inotion during plastic defonnation. Theo particles grow homogeneously in the matrix, and have the Cu3Au (L 12)"" superlattice crystal structure. Aluminum-lithium alloys are used primarily for aerospace structural applications since they have attractive properties such as a lower density and higher elastic modulus than conventional 2XXX and 7XXX alloys."

Jan 1, 2000

By M. Neises, M. Roeb, C. Sattler, S. Stenger

"A two-step thermo-chemical cycle process has been developed and investigated. It is based on metal oxide redox pair systems, which can split carbon dioxide as well as water molecules by extracting oxygen atoms and reversibly incorporating them into their lattice. If concentrated solar radiation is used as the heat source, a promising method exists to produce synthesis gas from water and CO2. An easy way of operation is gained by the combination of a ceramic substrate as the absorber structure, which can be heated to high temperatures with concentrated solar radiation, and of a metal oxide coating which is capable to carry out the redox reactions. The performance and kinetics of a ferrite based redox material coated on ceramic substrates were investigated in a laboratory set-up. CO2 could be reduced with significant conversions. In addition, several side reactions were observed like the formation of carbon and like the Boudouard reaction.IntroductionThe search for alternative energy carriers and for processes able to reuse carbon dioxide stimulates the research for sustainable routes of alternative fuel production. In the scope of this search thermo-chemical processes combined with sources of concentrated solar energy have become more and more attractive. Ideally, the only raw materials for such processes are water (H2O) and carbon dioxide (CO2) enabling not only a process free of emissions, but also allow to reduce emissions of other processes by reusing CO2 to provide synthesis gas, which itself can be applied to produce chemical commodities or even better synthetic fuels like methanol or petrol.In contrast to the direct splitting of those raw materials, thermochemical cycles split water and CO2 in several steps and enable hydrogen (H2) and carbon monoxide (CO) generation at temperatures controllable by today’s technical equipment. One of the most interesting thermochemical cycles is a two-step process using metal oxide based redox systems. During the first step of this cycle (the regeneration step) the metal oxide is reduced setting some of its lattice oxygen free according to reaction (1). In the next step (the splitting) the reduced and activated material is oxidised by withdrawing oxygen from water and CO2 and at the same time hydrogen and CO is set free according to reactions (2a) and (2b) respectively."

Jan 1, 2011

By L. M. Abrantes, A. P. Paiva

"A brief review of some innovative methods for the direct recovery of metals from loaded organic phases is presented; emphasis is given to electroreductive stripping and cementation, which are described and illustrated by examples: of current research. The recovery of silver using a two-phase electrolysis - by direct application of an electrical potential to a mixture of a metal loaded organic phase· containing Cyanex 471X, obtained by solvent extraction, and a stabilized sodium thiosulfate solution - is more extensively discussed. The overall efficiencies are analyzed and compared with data obtained by conventional stripping procedures. Some preliminary results achieved for the recovery of the precious metal using galvanic stripping, applied directly to similar organic solutions and involving zinc and iron powders as reducing agents, are also evaluated.Introductory ReviewThe application of hydrometallurgical methods to the recovery of metal values from ores and concentrates has been receiving a growing interest, either from researchers or from the mining industry [1].For the concentration / purification of the relatively low concentrated metallic solutions resulting from the leaching of those raw materials, solvent extraction (SX) is a well established technique [2]; the loaded organic solvent is then conventionally contacted with a suitable aqueous solution, the metal in its final form being usually recovered from this solution by electrowinning.As an efficient and / or selective stripping is sometimes difficult to achieve, depending on the specific characteristics of the system under consideration, some alternative procedures have been analyzed in order to overcome this problem. One of the chosen routes, mainly developed by Hirai and Komasawa, is to promote the reduction of the desired metal species in the organic phase, in such a way that the stripping stage becomes feasible; for the selective stripping of vanadium from a solvent containing a mixture of vanadium and molybdenum, the authors successfully used reductive [3], electro-reductive [4,5] and photo-reductive [6] techniques. The two latter methodologies have also been applied to the recovery of europium from a solvent containing europium, samarium and gadolinium [7,8].However, further processing is necessary to recover the metal in its solid state; therefore, methods causing the direct reduction of the metal species in the organic phase to their fmal metallic form would be of interest, as an intermediate step would be avoided"

Jan 1, 1997

By S. C. Flood, J. D. Hunt

"The columnar-equiaxed transition (CET) has been studied numerically under unsteady-state conditions using mathematical models that: (i) include a non-equilibrium undercooling at the columnar front;and(ii) describe the simultaneous evolution of the columnar and equiaxed zones.The results are discussed and compared with those produced by a steady-state analysis.IntroductionThe majority of the previous work on the columnar-equiaxed transition (CET) has concentrated on the production of equiaxed nuclei, regarding this as being the critical step in the formation of an equiaxed zone. Recently, the growth of equiaxed grains has been considered and this is not unreasonable because, for an equiaxed zone to be present, the grains must grow as well as nucleate. Since the growth rate of the grains will be determined by the thermal environment at and ahead of the columnar tips, it was decided to model the liberation and flow of heat during solidification to discover whether the various trends in the columnar range might be explained by their effect on the temperature profile throughout the casting. The models presented here for the solidification of a casting are the first to include the latent heat liberated ahead of the columnar front. Burden and Hunt (1) consider its effect only qualitatively, and although Lipton et al (2) adopt a criterion for the CET which is based on the thermal interaction of the columnar and equiaxed grains, they do not actually include the latent heat in their calculations.It can be argued that the latent heat liberated by the equiaxed grains in the bulk will retard the columnar dendrites in a casting: once the equiaxed grains are sufficiently well-established, the latent heat that they evolve could slow down the columnar growth to such an extent that the equi axed would dominate. Alternatively, the latent heat produced by the equiaxed grains might suppress further equiaxed solidification by raising the bulk temperature. The nature of the thermal interaction between columnar and equiaxed growth is not obvious, and because it is dependent on the material parameters and the dimensions of the system, it cannot be considered effectively in a qualitative way but has to be studied quantitatively: hence the need for the mathematical models discussed in the following pages. The results of the models are discussed in the light of a steady state analysis."

Jan 1, 1986

By Edilson Marques Magalhães, Danielly Da Silva Quaresma, José Antônio da Silva Souza, João Nazareno Nonato Quaresma, Emanuel Negrão Macêdo

"The production of alumina from bauxite using the Bayer process generates the residue known by red mud. This material can be used as a source for concentration and recovery of valuable metals such as titanium. The greatest difficulty of concentrating titanium compounds is the large amount of iron oxide present in red mud > 30% by weight. This paper shows the extraction of the iron oxide, increasing the concentration of the titanium compounds. The red mud is leached with H2SO4 at 30% concentration and temperature range of 60°C, 80°C and 90°C. Analysis of the leached and concentrated was made to verify the effectiveness of the iron oxide extracting process and the titanium compounds concentration viability.2- IntroductionIn the state of Para is located the Industrial Unit Alumina of North of the Brazil S/A (Alunorte), created to produce and commercialize alumina, aluminum oxide, Al2O3. The ALUNORTE with Aluminum Brasileiro S/A (Albras) and Mining Rio do Norte S/A (MRN) complete the production cycle of aluminum in the state. Although the production of alumina has a importance great for the socio-economic status, as in any area other, generates a amount large of waste, thus causing environmental impacts. Pará State has produced 25 million tons of bauxite (Pinto, 2010), of which 60% were transformed into alumina plant in Pará and Maranhão by ALUNORTE by ALCOA, generating approximately 9,000,000 tons of waste known as Red Mud (RM). Due to the high reactivity this material is considered dangerous, and currently there is no operating process capable of reuse all the material produced at any refinery. The search for industrial processes in order to reuse these wastes can contribute to reducing the overall impact of the production process of alumina. In this context, this paper estudied, within the research line of Solid Waste valorization the mining industry and metallurgy, a process that makes possible the red mud as a source of raw material, in other words, seeks to maximize the use of red mud as raw material for concentration and or recovery of titanium compounds in both the crystalline form of anatase, rutile and ilmenite, avoiding the predatory extraction of natural resources of these materials. Applying definitely the concept of self-sustainability of the mining industry and metallurgy."

Jan 1, 2012

By Kimio Itagaki, Torn Matsumoto, Makoto Ohtsuka, Kentarou Harada

"The structure and hydrogen-absorption properties of LaNis thin films were investigated in the present study. LaNis thin films were prepared by a sputtering method with a radio-frequency power, Ws, of 50 -400 Wat substrate temperature, Ts, of323 -573 K. Nickel content of the films decreased with increasing Ws, however, there was no dependence on Ts. At low Ws and low Ts, amorphous films were deposited. In other conditions, the films were polycrystalline. The films prepared at high Ws and low Ts, or at low Ws and high Ts, exhibited only a (h k · 0) peak in the X-ray diffraction profiles. This indicates that the c-axis of crystalline films was oriented parallel to the substrate plane. At high Ws and high Ts, the films with columnar structure were obtained. Hydrogen-absorption capacity of the thin films increased with increasing Ws. The pressure plateau did not appear on the pressure-composition isotherms. The films deposited at high Ts represented a higher equilibrium pressure.IntroductionThin films of hydrogen storage alloys can be applied for an electrode of rechargeable battery or fuel cell, a filter for H1 purification and various kind of sensor. Some studies on the preparation of the thin films of LaNi5 intermetallic compound, which is a typical hydrogen storage material, have been done hitherto. Adachi et al. , 2) and Sakaguchi et al. 3) prepared amorphous and crystalline LaNi5 thin films using flash evaporation of alloy powders and measured the pressure-composition isotherm for the prepared film utilizing a quartz crystal mass monitoring (QC:MM) method. It was found that the prepared amorphous film absorbed hydrogen without disintegrating into the powders and the hydrogen-absorption capacity of the films increased with the degree of crystallinity. Sakai et al. 4) reported that the maximum hydrogen storage capacities of amorphous and crystalline LaNi5 thin films, fabricated by a RF sputtering method using combination targets, were about 40 mA h g-1 (LaNisHo.7) and 160 mA h g-1 (LaNi5H2.6), respectively. Uchida et al. 5, 6) prepared LaNi5 thin films using flash evaporation of alloy powders and measured volumetrically the pressure-composition isotherm for the prepared film. It was reported that the hydrogen-absorption capacity of the films changed by the annealing treatment."

Jan 1, 1998