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By Pengkai Wang, Huimin Lu, Xiaoxiang Zhang

"In this paper, it was studied an electrochemical reduction process of carbon dioxide in ionic liquids such as 1-n-butyl-3-methylimidazolium hexafluorophosphate ([Bmim] PF6) as the electrolyte. The electrolysis experiments were carried out under current and potential controls. The cathode products contained carbon nanotubes, carbon nanofibers, nanographites, and amorphous carbon. To establish the actual current and potential ranges, the electroreduction of carbon dioxide dissolved in the ionic liquid was studied by cyclic voltammetry on glass-carbon (GC) electrode at room temperature. The electrochemical mechanism of carbon dioxide electroreduction was studied for explanation of all obtained results. Carbon dioxide in ionic liquids was electroreduced, similar to metals oxides being electroreduced in molten salts.IntroductionGlobal warming caused by the increase of carbon dioxide in the atmosphere has become one of the most concerning environment problems, so the solution to this greenhouse effect is very urgent. However, the carbon dioxide is also a cheap and abundant raw material that represents a potential source for the production of chemicals and fuels. Therefore, the development of the technologies that achieve simultaneous reduction and conversion of carbon dioxide to fuels is important. The electrochemical reduction of carbon dioxide is one of the effective approaches to transform CO2. Many investigations have been carried out on the electrochemical reduction of CO2 in both aqueous [1] and non-aqueous [2] electrolyte solutions with different electrodes. The solubility of CO2 in water is very low even under high pressure of CO2, and some investigators have brought focus into the electrochemical reduction of carbon dioxide in organic solvents, because they dissolved much more CO2 than water did. However, the hazardous or toxic properties of organic solvents hinder their use."

Jan 1, 2009

By Staff

The uninitiated, first-time visitor to the Copper Cliff Smelter of The International Nickel Company frequently finds it strange that the world's largest nickel producing works is located at a site seemingly named in honour of another metal. Industry-wise persons who know The International Nickel Company through its nickel producing, fabricating and sales organizations can be just as surprised to learn that Inco's annual copper production from the Sudbury area mines nearly equals that of nickel. But when the history of the mines and smelters of the Sudbury district is reviewed it is impossible to separate the stories of copper and nickel. In fact, going even further back in time (I), it was due to the similarity in appearance of the nickel bearing mineral niccolite (NiAs) to that of copper ore that led nickel to be tagged with the rather uncomplimentary name of kupfer-nickel or Old Nick's Copper - The Devil's Copper. This was in approximately 1650 and it would take another hundred years, until 1751, before Axel Cronstedt of Sweden obtained nickel in its pure form and permitted it to take its own place in the family of metals. One hundred more years passed before mining came to northern Ontario and approximately one hundred thirty before the beginnings of development of the Sudbury Basin.

Jan 1, 1976

By Marc Liebman

We present the results of a telephone survey of electric arc furnace (EAF) steel producers. This report characterizes the current status of EAF dust generation, treatment and disposal. It indicates the quantity generated, zinc content, other relevant constituents, and plans and trends that will impact on the quantity and characteristics of the dust generated. The survey covers EAF based steel producers in the United States and Canada. It identifies the processors currently employed, opinions about the use of these processors and services, as well as new technologies being considered.

Jan 1, 2000

By Pertti Koukkari, Nagendra Tripathi, Karri Penttilä, Justin Salmine

ChemSheet is a thermodynamic multi‐phase multi‐component simulation software, which is used as an Add‐in in Microsoft Excel. In ChemSheet, the unique Constrained Gibbs free energy method can be used to include dynamic constraints and reaction rates of kinetically slow reactions, yet retaining full consistency of the multiphase thermodynamic model. With appropriate data, ChemSheet models can be used to simulate reactors and processes in all fields of thermochemistry. The presentation will cover off‐line modeling of Cu‐flash smelters and advanced thermochemical simulation coupled with on‐line process control of Cu‐Ni smelting. The presentation will describe an off‐line model of Cu‐smelter based on critically assessed properties of the Al-Ca-Cu-Fe-O-S-Si –system (slag, matte and liquid metal) by using the quasichemical model. A four‐stage reactor model (shaft, settler, uptake and bath) is used for optimizing process parameters and feed particle distribution. As a second example, an advanced thermochemical model of a Ni-Cu sulphide smelting plant will be given. The on‐line model covers the operation of treating Ni-Cu-S concentrate via roasters, electric furnace and converters, producing a high grade Bessemer matte product for further refining. The model integrates the thermochemistry of the roasters and electric furnace, and predicts important process parameters such as degree of sulphur elimination in the fluid‐bed roasters, matte grade, iron metallization, slag losses and the iron to silica ratio in the electric furnace slag. Both models can be used to assist process engineers and operators in calculating the addition rates of coke, flux and air for different feed scenarios.

Jan 1, 2014

By G. L. Pedroti

With the development of industrial processes and the consequent emergence of numerous products that quickly become necessities, industrial activity has acquired an essential character today. Although its importance is unquestionable, industrial activity is responsible for generating quite a large number of residues, with different shapes and characteristics. It has been observed, in particular the grits (Kraft process in the cellulose industry) and the residue from the processing of granite. And, given the importance of Portland cement as a building material, its vast employment and waste properties that resemble components of the clinker, it was decided to produce cementitious compounds from these industrial wastes. The residues were subjected to mineralogical, chemical, physical and morphological. And, the mixing ratio between the residues in the 70% and 30% grits residue granite was sintered at 1250 ° C furnaces to burn threshold of 6 hours forming new compounds observing tri-calcium aluminate and di-calcium silicate that are compounds found in portland cement.

Jan 1, 2015

By S. Ozbilen, B. Erdogan, M. Erdogan

To study by thermal analyses the response of precipitation hardenable alloys of Al-Cu-Mg and Al-Li-Cu-Mg system to natural and artificial ageing, a series of ternary and quaternary Al-alloys with nominal compositions of Al-l.13wt%Cu-0:65wt%Mg (alloy-I), Al-1.15wt%Cu-0.57wt%Mg-0.07wt%Li (alloy-2), Al-l.19wt%Cu-0.56wt%Mg-0.75wt%Li (alloy-3), Al-2.0lwt%Cu-0.89wt%Mg (alloy-4), Al-2.14wt%Cu"0.56wt%Mg-0.07wt%Li (alloy-5) were used in the present investigation. Samples in the form of rolled sheets are subjected to water quenching at 25EC after solution treatment at 530EC for 20 min. Alloys were aged naturally at room temperature (25EC) up to 2 months and artificially at 190EC up to 2 days. By using differential scanning calorimetry (DSC) in the temperature range of25-300EC, differential thermal analysis (DTA) in the temperature range of25-600EC together with Vicker's hardness measurements, the response to natural and artificial ageing of the alloys used in the present study were investigated. It was observed that in these alloys, GPB(Cu, Mg) zones [Guinier-Preston zones with Cu and Mg] do form during water quenching at 20EC following solutionizing heat treatment. Natural ageing of the same alloys causes formation of more GPB(Cu, Mg) zones, which results in hardening in the alloys. Artificial ageing at 190EC up to l day results in GPB zone dissolution causing preliminary decrease in hardness values while two days of artificial ageing in the alloys cause S' (Al2CuMg) precipitation confirmed by DSC/DTA analyses resulting in an increase in hardness values. Li addition up to 0.75wt% helps T1 (Al2CuLi) and T 2 (Al6CuLi3) phase formation together with S' precipitation as DSC/DTA analyses show after the same heat treatment.

Jan 1, 1998

By W. G. Davenport

The offgas from flash furnaces inadvertently contains dust. The dust contains 25 to 30% Cu so it must be treated for Cu recovery. This is almost always done by recycling it back through the flash furnace*. This chapter shows how dust production/recycle is included in our matrix calculations. It then discusses the effects of dust production/recycle on flash furnace industrial oxygen and oil requirements. It concludes that re-smelting of dust requires considerable industrial oxygen and fuel, so that dust production should be minimized. Recycled dust also takes the place of new concentrate in the flash furnace feed system, decreasing Smelter productivity -another reason to minimize dust production. Compositions of industrial dusts are given in Appendix VII and Table 18.3. Industrial quantities are given in Tables 2.1, 3.1, 19.1,20.1' and Appendix VI.

Jan 1, 2001

By William Petruk

A mineralogical and image analysis study was conducted on samples of U tailings from pilot-plant runs on Midwest ore in Northern Saskatchewan. The tailings had been subjected to simulated weathering for the equivalent of 10 years in a tailings facility (lysimeter). The pH varied from 7.0 at the beginning of the test to 5.9 at the end. The results show that during the simulated weathering sane of the gersdorffite, uraninite, galena and pyrite had oxidized, with gersdorffite being the most reactive and pyrite the least. Reaction was evident at the top of the lysilleter , but was most intense at the seepage discharge. sane of the released ions precipitated as Ni, Pb, and U arsenates, sulfarsenates, sulfates and oxides on particles of all minerals. Green crystals of Ni sulfate and white crystals of ca sulfate had precipitated at the surface of the lysilleter. Clay minerals and chlorite had washed from the top of the lysirneter towards the seepage discharge.

Jan 1, 1989

By Russell E. Clemons

Coarse-crystalline granite, quartz syenite, syenite, meladiorite, and anorthosite in the Florida Mountains, southeast of Deming, New Mexico, were originally mapped as Precambrian. They were remapped in 1971 and some of them described as Mesozoic intrusives. Several subsequent papers presented Precambrian and Ordovician ages. Zinc, lead, copper, silver, gold, manganese, fluorite, and barite mineralization in the Florida Mountains invite more extensive exploration. Clarification of ages of rocks and periods of alteration and mineralization are necessary for efficient exploration. Field observations combined with petrographic studies strongly suggest that all the coarse plutonic rocks are Precambrian and most were altered extensively by late Tertiary hydrothermal activity.

Jan 1, 1982

By T. A. Venugopalan

The 'Hall-Heroult' Process of reduction of Alumina to Aluminium has remainded basically the same for over 100 years, but the technology has been undergoing drastic changes with respect to selection of materials for Cathode and Anode, and also energy consumption. The latest generation pots have a working life of about 1800-2000 days normally. After the failure of the pots, the Cathode Lining is dug out and disposed of on land. Since the lining contains objectional materials causing pollution, various processes have been tried for re-processing of this waste. However, most of the processes have been unsuccessful from the techno-economic point of view. At Hindalco a new chemical process for converting the fluorine values of the dug out material to Cryolite was developed in 1988 and a" one ton per day Cryolite production plant has been operating since 1989. This process is especially applicable where the integrated Alumina and Smelter Plants exist side by side. The experience in operating this Plant is discussed in detail in the paper.

Jan 1, 1992

By Alan P. Prosser

The heap leaching of gold ores by cyanide solution was simulated by computer program. The program uses only basic m1neralogical and chemical data; no process testwork data, such as column leach results, are required. The simulation can be used to forecast the consequences of various changes before and during the testwork, design and operation stages of a particular ore-process system. Also, data about the state of different parts of the heap at various times help create an understanding of what is happening. The effects of mineralogical and process variables on the overall performance of the ?heap leaching process are illustrated. Comparisons are made to column leach tests and production data. The potential of the simulation strategy is discussed for making better use of operating experience and for suggesting specific research objectives. It has become clear that more attention should be paid to other metals that dissolve in the solution.

Jan 1, 1989

By J. C. Agarwal

Most metals are produced from minerals containing one or more of the desired metals, some contaminating metals, silicate, oxides, carbonates, and sulfides. Therefore, in the production of metals, there is generally a gaseous effluent in pyrometallurgical processes and a liquid effluent in hydrometallurgical processes. There are also solid residues such as waste ore, tailings, dust, and slag, created by the metal recovery processes. There are two important distinctions between the effluents and the residues: I. Effluents ? gases and liquids ? affect the neighboring environment for miles from the point of emission, while residues affect only the soil on which they are stored or dumped. 2. The environmental and economic effects of effluents are known and felt essentially immediately. By contrast, the environmental effects of the residues may not be known for a long time. For these reasons, the economic impact and the potential corrective actions required are very different for effluents and residues.

Jan 1, 1992

By M. Jortikka

The smelting process of the old reverberatory furnace including its capacity has been improved over the years in different ways eg. with oxy-fuel burners, parallel reactors with the reverb or with various modifications of the reverb furnace itself. The future reverb modifications with old concepts are difficult or impossible as the increased copper losses in slag call for separate slag treatment and particularly the process modifications do not solve the environmental issues but instead mean unavoidable high capital and operating costs in gas cleaning and sulphur recovery. During the last decades improvement in process performance and increase in capacity of copper flash smelters has been achieved easily by substituting the pre-heated process air by highly oxygen enriched air. The flash furnaces of today, however, are inherently designed to operate with high oxygen enrichment. Further process improvement with a view to production costs and capacity increase as well as to the more stringent environmental requirements is possible with even higher oxygen enrichment. This, apart from the advantages it generates, requires improvements in and careful design of the feed system, concentrate burner, furnace cooling and the off-gas line as well as adaption of the flash converting instead of the conventional Peirce-Smith converters. A logical answer even for the revamping of the reverb smelters in the future is the total replacement of the reverb furnaces with flash smelting together with flash converting. This paper discusses the possibilities for future process improvements of the existing flash smelters taking into account the process concepts, equipment modifications and capital aspects not forgetting the environmental issues. The revamping of the PASAR smelter in Philippines is introduced as an example of a recent success story.

Jan 1, 1994

By F. Robert Hubbard

IMCO Recycling Inc. has developed a new, patented technology for the production of fertilizer, K-SOIL?, as a by-product of its aluminum recycling operations. This new technology can substitute for conventional technology which now results in a saltcake residue that is placed in 'landfills. Four years of research and development work by IMCO culminated in a U. S. patent issued April 5, 1994. As part of the technology development effort, IMCO engaged the services of a nationally renowned research organization and a prominent university. These two organizations have conducted in-depth agronomy studies In the laboratory, greenhouse, and the field. Results have shown K-SOIL? to be performance equivalent, on a nutrient content basis, to conventional potash fertilizer. The first field applications on commercial farms were made in the spring of 1994. K-SOIL? is a potassium-bearIng, granular solid which may find use in fertilizer blends, direct application, and other forms of fertilizer products. The overall benefit of this new technology is to create a useful by-product rather than generate a useless residue and, thereby, reduce or eliminate the amount of salt cake now placed in landfills. As such, It is a significant, step toward IMCO's ultimate goal of complete recycle.

Jan 1, 1995

By Jens Decker

"In consideration of energy savings the ideal refractory furnace lining should possess the following features:??Lowest thermal conductivity possible in order to avoid heat loss.??Single component lining in order to allow freeze plane changes caused by wear, infiltration and temperature changes of the furnace.??Resistance against mechanical wear from cleaning tools and stirring in order to allow maximum output without equipment downtime due to maintenance.??Resistance against thermo-chemical attack from aluminum and alloying elements.However, refractory materials with a low thermal conductivity typically possess a higher porosity and this leads to lower strengths and resistance against chemical attack and wear. Hence, as a compromise, multi layer linings are required in order to meet energy saving standards.In this paper we present the features of chemically phosphate bonded dense and light weight refractories and how such refractories can contribute to energy savings.IntroductionIn several reports, the U.S Department of Energy published theoretical energy requirement limits for aluminum production as a future target, with recommendations on how to reduce energy losses. The reports provide a basic description of the processes and equipment involved, their interrelationship, and their effects on energy consumed. The report uses onsite process measurements as benchmarks that industry uses to compare performance between facilities and companies [1]. The energy consumptions used in this paper are primarily based on numbers published by the Department of Energy. However, their reports do not consider the potentially significant energy losses from process interruptions due to a lack of preventive maintenance and material deterioration over time. Further, the Department of Energy reports do not consider equipment costs and availability. Energy input to metal output depends on factors beyond energy losses through the furnace wall. For instance, a focus on energy savings should consider fixed output costs due to depreciation of the equipment and the plant."

Jan 1, 2009

By Geoffrey Brooks, Ben M. Ekman, M. Akbar Rhamdhani

"Concentrated solar collectors including solar simulators have been studied to concentrate solar radiation to flux levels capable of reaching temperatures of 3000K. Currently, there are no industrial scale solar reactors used for material processing and only small research units have been tried. Various laboratory scale solar reactor designs are reviewed including their operating temperature and heat transfer efficiency. Solar reactor designs can be classed into directly or indirectly irradiated and single or double cavity construction. Thermal efficiencies of up to 40% have been achieved in experimental units while operating at 1500K. Problems are encountered that relate to the transfer of high heat flux. Hybrid reactor system should be considered in the future to overcome some of the practical issues associated with solar thermal reactors.I. INTRODUCTIONIn the high temperature processing of materials, such as the production of metals, cement, refractory or glass, the reactions are typically performed in the range of 500° to 2000°C. Metals are produced from minerals, which maybe oxides, sulphides, chlorides or silicates, and to recover the metals, these compounds have to undergo chemical reaction to liberate the metal. The thermodynamic stability of these compounds found in minerals necessitates the use of high temperatures to break down the bonds between the metals and other elements. Normally, the raw metals produced from smelting require refining, which is often carried out in the molten state. As new energy sources have been established, new furnace designs have evolved to incorporate the latest technology. Although solar energy has existed longer than all the current energy sources, it has not yet been incorporated into any industrial smelting; refining or melting processes. The solar radiation reaching the earth’s atmosphere, called the “Solar Constant” (SC), is defined as the rate at which solar energy is incident on a surface normal to the sun’s rays at the outer edge of the atmosphere when the earth is at its mean distance from the sun. The currently accepted value is 1367 W/m2 [1]. The earth intercepts only a small amount of this and 30% is reflected back into space, 47% is converted to low-temperature heat and reradiated into space and 23% powers the evaporative and precipitation cycle of the biosphere [2]. As a result, the solar energy reaching the earth’s surface is weakened considerably to about 1000 W/m2 or one sun, on a clear day and much lower on cloudy or smoggy days [3]. The thermodynamic limit for solar concentration is determined from the inverse square law [4] by the factor sin2? = 46,764 sun’s [5] where ? is the angular size of the sun and equals 0.0093 radians [7]. This would produce a steady state temperature equal to that of the sun’s surface of approximately 5800oC. In practice however much lower concentrations are achieved due to geometrical and optical imperfections, shading effects and tracking inaccuracies. Optical configurations based on parabolic-shaped mirrors are commercially available for large-scale collection and concentration of solar energy for the generation of electrical power. The most common configurations used for concentration of the sun’s energy in solar thermal applications are parabolic troughs, solar towers and parabolic dishes [8,9]."

Jan 1, 2014

By Samson Adeosun, Sanmbo Balogun, David Esezobor

"Iron and steel making processes give rise to large amounts of usable and unusable materials, the latter generally being termed wastes. It is sometimes difficult to distinguish between re-usable by-products and wastes which cannot be sold or land-filled. Much depends on circumstances such as the local market for the material. This can itself vary from time to time with by-products which cannot be used or sold becoming wastes and vice versa. This paper defines the concept of “waste-free technology”, discusses its development in the steel industry and highlights the benefits of the technology to the manufacturing sector and the environment. The paper also articulates how the “waste-free” technology could be applied in the proposed Ajaokuta integrated steel plant in Nigeria.IntroductionIn the past, nature was considered an inexhaustible store. Its resources were consequently exploited and waste products therefrom were discarded. Today, attitudes have not changed appreciably even as raw materials cost rise by the year to pose a series of socio-economic problems, which, among others, may include the rational and optimum utilization of resources, environmental protection and reduction of waste formation. Consequently, industrialists now face unexpected regulatory pressure in areas of pollution prevention, waste minimization and hazardous waste disposal.Iron and steel making processes give rise to significant amounts of usable and un-usable materials, the latter generally being termed waste. It is sometimes difficult to distinguish between re-usable by-products and wastes which cannot be sold or land-filled. Much depends on circumstances such as the local market for the material. This can itself vary from time to time with by-products which cannot be used or sold becoming wastes and vice versa. In this paper, the term waste refers to those materials that are either irrationally utilized or, land-filled and part of the byproducts that are not utilized. It includes that part of used materials which is not incorporated into the products manufactured during a process stage and which in contrast to reuseable materials, is considered not suitable for any further use, owing to technical or economic factors. In general, these materials are inorganic and parts of them are either utilized or passed to the other processes; the other part should be disposed of using well-established waste disposal practices to avoid any environmental threat.Thus, creative methods must be developed to modify the manufacturing processes to reduce emissions and process wastes by fully utilizing all resources. One method of eliminating the negative effect of waste formation is the use of purification and cleaning structures (pollution control system, PCS). These are, however, quite expensive."

Jan 1, 2008

By Versiane A. Leão

The hydrochloric leaching of chrysotile tailings and soapstone powders) is discussed. This two materials are magnesium compounds associated with carbonates and iron oxides. In this work the chemical and physical characterization of formers is presented and the thermodynamic analyses of leaching is carried out. Magnesium extraction is almost complete for chrysotile tailings while, for soapstone powders, one can be reached 60%. The behavior of iron and calcium impurities is discussed.

Jan 1, 1997

By Oszkar Bíró, Peter Mittag, Bernhard Aigner, Stefan Pirkeri, Philipp Glttleri

"This paper considers CFD modeling of processing and melting of small metallic particles by means of electrical heating. The particles fall continuously onto a liquid metal bath which is heated by an electric arc. After melting of the particles liquid metal is tapped.The charging behavior of the particles in the supply unit as well as in the reactor freeboard is studied by means of Euler-Euler granular simulations. The flow situation in the metal bath due to gas injection and magnetic fields is calculated by combining Navier-Stokes and Maxwell solvers. The macroscopic melting process occurring during the continuous charging of the particles is studied by kinetic laws for melting reactions. The temperature field is evaluated by balancing heat sources due to Joule's heating and heat losses due to latent heat of melting as well as convection and radiation.As a result of these simulations the fully three-dimensional flow fields of particles and gas in the atmosphere is obtained. Furthermore the flow field as well as the magnetic field in the metal bath can be studied. As a main result the three-dimensional concentration field of the still unsolved particles in the liquid metal can be evaluated.IntroductionIn this paper a metallurgical process for melting small iron particles is investigated by means of CFD-simulations. In a first process step the preheated and already mostly reduced iron particles fall continuously into the reactor through a vertical tube mounted at the lid of the furnace. In a second step the particles are melted in the liquid metal bath. Meanwhile the melt is heated by electric arcs to provide the heat needed for melting the incoming particles.In Figure I a sketch of the geometry setup considered in this paper is provided. The particles fall from a height of approximately 12 meters onto the bath surface in the center of the furnace. The melt is heated by electric arcs that are placed symmetrically around the center axis."

Jan 1, 2001

By J. W. Dini

Introduction The mission of the Materials Fabrication Division (MFD) is to provide fabrication services and technology in support of all programs at Lawrence Livermore National Laboratory (LLNL). MFD involvement is called for when fabrication activity requires levels of expertise, technology, equipment, process development, hazardous processes, security, or scheduling that is typically not commercially available. Customers are encouraged to utilize private industry for fabrication activity requiring routine processing or for production applications. MFD is .a large diversified service organization including approximately 400 full time employees. The group provides a wide variety of processes including all common machining and fabrications operations, laser and water jet cutting, electrical discharge machining, lapping, electron beam and laser welding, vacuum brazing, heat treating, forming, electroplating and metal finishing, optical polishing and grinding, vacuum coating, vacuum engineering and a variety of plastics operations. These operations occupy more than 1,250,000 square feet of floor space. For more detail on the many fabrication related services available from MFD, see Reference 1.

Jan 1, 1992