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By Matthias Schnitzler, Herbert Pfeifer, Ralf Bolling

"To transform metals high temperatures are usually needed. A fast and efficient heating can reduce the C02 emitted. The fastest way to heat metals is called direct flame impingement (DFI). The flame impinges upon the item being heated. For this method it is important to know the shape and length of the flame. Laser-induced fluorescence (LIF) technology allows measurements of a two-dimensional field without influencing the reaction or the flow. Commonly used is the measurement of OH-radicals, an indicator of the reaction zone.In the presented study measurements of a turbulent diffusion flame are shown. The position of the reaction zone and the influence of the distance between the item being heated and the burner are investigated. Conventional measurements and LIP-measurements are compared and the potential of DFI to increase the efficiency of heating metals is discussed.IntroductionDuring industrial heating processes a fast and efficient heating technology is required. Two important aspects are the NOx emission and the energy efficiency. The direct flame impingement (DFI) technology has the highest heat transfer rate possible with a gas/air flame. The turbulent high velocity flame jet impinges upon the item being is heated [ 1]. Due to the high heat transfer rate furnace and exhaust gas temperatures are lower. Therefore the energy efficiency is increased and the amount of NOx emitted is reduced.Hydroxyl- (OH-) radicals are an intermediate product that is generated during the combustion of hydrocarbons [2]. They are commonly considered as an indicator for the reaction zone and position of heat release. Figure 1 shows the hydroxyl-mole fraction in dependence of the distance along the gas flow. The figure clearly shows how fast the OH-concentration increases in the reaction zone. Figure 1 also shows that OH-radicals are present in the post combustion region, however in smaller concentration [3].The laser-induced fluorescence technology serves to measure the spatial distribution of OH-radicals in a two dimensional cross-section area of the flame. Therefore the flame dimensions and location can be determined with high spatial resolution without influencing the flow or the reaction [ 4,5]."

Jan 1, 2012

By Ximena Diaz

Mercury is one of the most undesirable contaminants in gold bearing ores. During cyanidation mercury cyanide compounds accompany gold in all the extraction and recovery processes. Of course mercury in the carbon eluates creates environmental problems in subsequent refining steps. One possible process alternative for the separation of gold from mercury in such concentrated alkaline cyanide solutions is the selective solvent extraction of gold by undiluted Dibutyl Butyl Phosphonate (DBBP). In order to describe the behavior of mercury during extraction by DBBP, the results from a preliminary research program are presented. In this study, temperature and cyanide concentration have been found to be the most significant variables which influence the separation of gold from mercury by solvent extraction using DBBP. It was found, using plant eluate from a carbon strip, that excellent separation of gold from mercury can be obtained at 60' C with 98% gold recovery and complete mercury rejection in a single stage of extraction. The influence of pH is also discussed in terms of the extraction chemistry. These results complement previous research which described the DBBP solvation extraction of an aurocyanide ion pair. In addition, these results extend our understanding of the alkyl phosphorous ester extraction systems by illustrating that neutral ionic species such as Hg(cN)02sq, can be extracted at low cyanide concentrations, a phenomenon which had not been observed previously for other cyanoanions.

Jan 1, 1993

By A. G. Raraz

Reactive metal electrorefining presents a number of problems that pose obstacles to commercial operation. Cerium has been chosen as the surrogate for certain reactive metals because of its thermodynamic and electrochemical characteristics. A comparative review of the properties for cerium and plutonium has been presented to justify the choice of cerium as the surrogate metal for studying electrorefining. This review has addressed the electrochemical, thermodynamic, and kinetic parameters of molten salt electrorefining of cerium metal to provide an insight to this extremely important process. The cell components and configuration, current efficiency of the process, purity of the cathodically deposited metal and the power requirement of the system are evaluated for a molten CaCl2-MgCl2 salt electrolyte using a molten, stirred impure anode. Crucible designs, salt electrolyte, cell temperature and electrode materials are also evaluated. Selection of the salt electrolyte and the cell temperature have been suggested from this study.

Jan 1, 1992

By Leonard J. Friedman

The contact process for the production of sulfuric acid has been used commercially since before the turn of the century (1880?s), and rapidly replaced the chamber process after the development of vanadium catalysts in the early 1900's (1910's - 1920's). Plant size has increased from a few tons per week to single train units in excess of 4,000 tons per day. Much of the history of the contact process is in the minds of the few remaining early process pioneers that started in the industry in the 1920's and 1930?s, and in sulfuric acid industry books published in 1921, 1925, 1936, and the last Deucker and West in 1959. Since those not familiar with history are doomed to repeat the failures and mistakes of the past, this paper includes a brief history of the contact process along with the history and development of equipment and materials in each equipment area of the process. The main focus of the paper is to present the development and analysis of equipment and materials in the contact section of the sulfuric acid plant - from the dry tower to stack.

Jan 1, 1999

By Joo Hyun Park

A history of the research regarding the spinel in the community of the stainless steels has simply been reviewed, followed by the recent studies for the formation mechanism of the spinel in the ferritic stainless steel melts equilibrated with the highly basic slags and the crystallization behavior of spinel phase in the calcium aluminosilicate melts containing MgO and CaF2 during slow cooling cycles. It has been proposed that the content of aluminum and calcium in the steel melts as well as the basicity and the content of MgO and Al2O3 in the slags are quite important factors affecting the spinel formation in view of the formation mechanism based on the reduction of MgO (or CaO) and Al2O3 in the slags by the aluminum and silicon added to deoxidize the molten steel. The use of magnesia refractory was also recommended. The formation mechanism of spinel from the MgO inclusions readily formed in the steel melts equilibrated with the highly basic slags has newly been proposed on the basis of the ionic exchange reactions at the inclusion/metal interface and the crystal chemistry of oxides. The crystallization behavior of the spinel phase in the calcium aluminosilicate melts was enhanced by the Al2O3 based on the ionic reaction of spinel formation in the oxide melts, while the size of the spinel crystals in the oxide melts decreased by addition of CaF2.

Jan 1, 2006

By Victor Bredykhin

The report is devoted to the investigation and improvement of processes taking place at contact of large quantities of water insoluble liquid and particles of solid phase in a pulp. Theoretical analysis and simulation of acting conditions have allowed to determine that after attaching of oleophilic particles on the «water-reagent» separation surface the break of a formed complex is taking place according to the reagent volume and for oleophobic minerals along the «solid-reagent» separation surface. As a result particles are selectively treated if the magnitude of the reagent adhesion to the surface of solid phase in water is great. The results of dispersion are influenced significantly by availability of sharp edges on the surface of real particles. They keep tree phase perimeter of moistening. It is possible to fix reagent in the form of lens whose contact angle is significantly smaller in comparison to the thermodynamic angle. In adhesion dispersion the reduction of reagent volume, covering the equal area of particles surface is possible when the reagent is in a pulp in the form of thin films on the «water-gas» separation border. The process is tested in laboratory conditions as well as at pilot concentrating mills in flotation of sulfide ores, non-ferrous metals (copper-molybdenum ore), native sulfur and coal.

Jan 1, 2006

By G. A. Brooks, R. W. Matusewicz, Nazmul Huda

"A computational fluid dynamic (CFD) model of a conventional tuyere blown slag fuming furnace has been developed in Eulerian multiphase flow approach. The model was developed by coupling CFD with kinetics equations developed by Richards et al. for zinc fuming furnaces. The model integrates submerged coal combustion and chemical reactions with the heat, mass and momentum interfacial interaction between the phases in the system. The model predicts the velocity, temperature field of the molten slag bath, generated turbulence, vortex and coal utilization behavior from the slag bath. The highest coal penetration distance was found to be at l/L = 0.2, where / is the distance from the tuyere tip and L is the total length (2.44m) of the modeled furnace. The model also predicts that 10% of the injected coal bypasses the tuyere gas stream un-combusted and carried to the free surface, which contributes to ZnO reduction near the free surface.IntroductionSignificant metal values are often discarded with slag in the form of metal oxide produced by the smelting industries. These metal values can be recovered from the slag by proper treatment. Zinc slag fuming is such a process, where a reductant source (usually coal) is injected in the molten slag bath to reduce dissolved ZnO from the bath into metallic zinc vapour. The process can be carried out in either conventional tuyere blown furnace or top submerged lance (TSL) smelting furnace. Conventional slag fuming processes are carried out on batch basis in a rectangular tuyere blown furnace. Approximately 50 tonnes of charge (either molten slag or solid slag) is fed to the furnace at the beginning of each fuming cycle. Two opposing sets of submerged tuyeres are employed to inject air and pulverized coal into the molten slag bath to carry out combustion and reducing reactions."

Jan 1, 2012

By G. J. Shiflet

This paper will review work done in our laboratory on the formation, thermodynamics and crystallization of aluminum based metallic glass with the addition of rare earth elements. The results demonstrate that the metallic glasses are truly amorphous and not microcrystalline and that they are unusual in their formation because the alloys contain 90 at. % aluminum and there is no deep eutectic present in the phase diagram. Tensile strengths that exceed 900 MPa are obtained for several of the compositions and exceed 1000 MPa after partial crystallization.

Jan 1, 1992

By Helena Byrdziak

KGHM Polska Miedz S.A. is a significant European copper producer with production of 447,000 mtpy, operating three underground mines and three smelters. The company has been involved for years in environmental activity, which was stimulated not only by the company itself, but by the development of environmental regulations as well. The first set of regulations, concerning water protection, was' established in Poland' in 1974, while a comprehensive environmental law was passed in 1980. This law in general requires industry to submit all data of environmental significance to the local authorities. Based on this data, they establish limits concerning emissions into the air, water and ground, the amount of wastes produced and the means of their disposal. A company has to pay fees for each tonne of emitted substances and stored wastes. When the emission of a substance exceeds the limit, the company has to pay a penalty which is about ten times higher than the fees. This approach in general is effective because it forces companies toward: reduction of their emissions. The problem is that the law is constantly subject to change and is becoming not only more restrictive but is involving more and more bureaucracy.

Jan 1, 1999

By Sacha Neven

Submerged lance technologies combine high intensity processing characterized by rapid mixing and reaction rates using a simple reactor design. The Isasmelt technology uses a central submerged lance to inject oxygen-enriched air and fuel into a bath thus creating large gas bubbles and intensive turbulence and splash. The lance is equipped with swirlers to increase gas velocity and heat transfer. This enables the formation of a frozen slag layer on the lance which protects it from the aggressive environment. Water models as well as high temperature reactors were used to validate the Davidson-Schiiler model on bubbling. Frequencies and pressure amplitudes were measured in a wide range of gas flow rates: from m3/sec using a water model to more than 30 m3/sec in an industrial process. Agreement with the model was satisfactory. The experiments however also clearly showed that cross-flow and bubble wake induce slightly higher frequencies. No influence of the use of swirlers on the bubbling frequency was observed in the water models.

Jan 1, 2002

By Mahesh C. Jha

Molybdenum, a major refractory metal, is widely used as an alloying element in steels and superalloys to improve their corrosion resistance, physical properties and mechanical strength, particularly at elevated temperatures. The current worldwide production and consumption is estimated at about 130,000 tons contained molybdenum per year. Molybdenum occurs in nature as molybdenite mineral and is recovered by a flotation process as a primary concentrate at molybdenum mines and as a byproduct concentrate at copper mines. The concentrate is roasted to a technical-grade molybdic oxide (tech oxide) in multiple-hearth roasters. About 80 percent of the tech oxide is sold, as such or after conversion to ferromolybdenum, for addition to iron and steel. The remainder is further refined to pure oxide and molybdate chemicals that are used in the manufacture of catalysts, specialty chemicals, molybdenum metal and superalloys. This paper discusses the various steps in the extractive metallurgy of molybdenum, from flotation of sulfide concentrate to reduction of pure oxide to molybdenum metal.

Nov 26, 1999

Lance based copper-nickel matte converters have become an established technology in the field of base metal sulphide smelting and converting. An Ausmmelt® converter is currently being constructed at Anglo Platinum in South Africa to convert a nickel-copper rich matte containing platinum group metals (PGM's). The accurate prediction of the matte chemistry is required to control the composition at the endpoint which influences segregation of PGM's during the subsequent slow cooling and magnetic separation processes. A hybrid modelling approach is introduced in this paper that incorporates both the effect of thermochemistry and system dynamics. It will be shown how the model relates to fundamental conservation laws, while still providing enough flexibility to adapt to changing operating conditions. It will also show how off-line modelling can be incorporated into a robust on-line model. Based on the data from many pilot plant trials, the model prediction performance is shown to be within the accuracy requirement set by industry and therefore constitutes a reliable basis for model based control. The final generic model structure takes on the form of an thermodynamically integrated ARMAX hybrid model. The final model has the advantages of being dynamic, adaptive, robust and it can be related to thermochemical fundamentals.

Jan 1, 2002

By Paul B. Queneau

U.S. plants solely devoted to recovering values from metal-rich wastes have established market niches based on one or more competitive advantages: superior process technology, access to key feedstocks, unique equipment, special knowledge of markets, and an appropriate exit for outfall water. Plant methodology, competitiveness, environmental factors, and economics are examined, with particular attention to feedstocks, technologies, products, and outputs.

Jan 1, 2003

By Michael L. Sorokin

The metallic nickel production by converting of nickel matte is analysed from the thermodynamic point of view using earlier developed thermodynamic models for sulphide, metal and slag phase. Three-suffix Margules equations are used to calculate thermodynamic properties of melts. Potential diagrams of Ni-FeS-OSiO2 system are calculated for various temperatures and Fe to Ni ratios. The diagrams used for consideration about possibilities of the direct one-stage metallic nickel production.

Jan 1, 1995

By V. M. Paretsky

Recent developments made in the Gintsvetmet Institute in the field of autogenous smelting processes have confirmed that autogenous smelting continues to be the main prospective technology for pyrometallurgical processing of sulfide raw materials. This technology ensures energy conservation and environmental safety conforming to the current world standards for production of heavy non-ferrous metals. Two alternative processes of single-stage autogenous smelting producing white metal as well as high-basic ferrite-calcium slags have been developed and can be recommended for technical modernization of Russian copper smelters.

Jan 1, 2002

By M. Kawakami

In order to make titanium ingot directly from molten slag, the metal pool was tried to form and used as the cathode. The electro-slag remelting (ESR) unit was used for the purpose. The unit is composed of water-cooled copper mold and the DC power source of 2000 A and 100V. The graphite electrode was used for anode and the base plate was used for cathode. The commercial and re-melted slag of CaO-CaF2 was melted in the mold with the addition of TiO2. The following reactions are expected to occur. Ti4+ + 4e = Ti at cathode 2O2- + 2C = 2CO + 4e at anode During the process, large amount of molten slag splashed out from the mold, showing the CO evolution at anode. The metal deposit was obtained but in the form of block and piled up on the base plate. The metal pool was not obtained perfectly because of shortage of heat supply. The cathodic current efficiency was 60 % at maximum. The metal deposit contained much impurity. In order to reduce the impurity and increase the current efficiency, the effect of electrode distance was examined. The electro-slag re-melting of titanium was tried in order to examine the condition to make metal pool.

Jan 1, 2006

By Lucas Lopes da Costa

Bamboo fibers were characterized in terms of diameter distribution and tensile properties. Polyester matrix composites reinforced with these fibers were investigated for their flexural mechanical behavior. Specimens with up to 30% in volume of continuous and aligned bamboo fiber composites were bend-tested until fracture. The results showed an improvement in the composite strength and stiffness with the amount of bamboo fiber. A microstructure analysis by scanning electron microscopy revealed a reasonable adhesion between the fiber and the polyester matrix which justifies the improved mechanical properties of the composites.

Jan 1, 2010

By Antonio Martin, Jesus Hurtado, Francisco Jimenez

"Atlantic Copper is one of the largest copper producers in Europe. Its production facilities, including a primary copper smelter and an electrolytic refinery, are located in Huelva, on the southwest coast of Spain. These installations enable the smelting of over 1 million tpy concentrates to produce up to 260,000 tons per year of cathodes and 900 ktpy of sulphuric acid.Since 1970, several improvements have been made at the Converters Area such as modifications of primary hoods, operations with an OPC system, installation of scrap chargers, the recent installation of the secondary hoods and other environmental projects. All these modifications have been aimed at increasing the capacity of our smelter while keeping our continuous environmental commitment.This paper describes the modifications and improvements carried out at the converters area and our proposals for future developments."

Jan 1, 2012

By Pertti Pekkala

Outokumpu has 25 years of experience in the SX area. The development of the solvent extraction plants responds to an ever increasing demand for lower operational costs wd for adaptability to process disturbances with minimized risks. In this paper the features of the VSF ("Vertical Smooth Flow") SX technology are described, such as the separated pumping and mixing, the homogenous gentle mixing, the droplet coalescence and the ultra pure settling. A major advantage of the mixing technology is the high stage efficiency of above 99 per cent. The connection between this and some features of the settler front section is clarified. The present design of VSF plants is based on experience of existing operations at, for example, Zaldivar, Radomiro, Morenci, Kokkola and Harjavalta. These production plants cover a unit capacity range of 60 to 3,600 m3/h expressed as a total flow. It is evident that there are no restrictive factors to increase the total flow up to 5,000-6,000 m3/h by introducing the VSF technology. The copper SX technology has a long history reflecting many individual features of the separate copper SX plants. Still it is necessary to verify all actual running parameters by pilot tests taking into account impurities, chemicals used etc. The design of SX plants is not only about the delivery of equipment but also a process concept, and it is best tailor-made and adapted to specific local requirements.

Jan 1, 1999

By Dachun Liu, Wenlong Jiang, Baoqiang Xu, Yongnian Dai, Bin Yang

"In the traditional method for refining of indium, glycerin-KI and glycerin-NH4Cl are used as electrolytes to remove Cd and Tl by electrolytic refining, which produces In with a purity of 99.995%. Large quantities of polluted industrial waste water are the result. It is calculated that the saturated vapor pressure of Cd and Tl are between 1-200 Pa, which is much larger than the vapor pressure of In. Thus, the study of removing Cd and Tl was carried out over the temperature range between 700-950 °C and pressures between 1-15 Pa. After vacuum distillation the contents of Cd and Tl in crude indium could sharply fall below 1 ppm..IntroductionIndium is a is a pale blue and silver white metal, and has high ductility [1-2]. Pure indium is generally used as a raw material to produce semiconductor compounds, fluorescent material and ITO targets [3]. Sublimation, zone melting and electrolytic refining are major methods to produce pure indium from crude indium. Electrolytic refining is the main method to product pure indium at present. High productive efficiency, simplicity of operation and short cycle of production are major advantages. However, glycerin-KI and glycerin-NH4Cl are used to remove Cd and Tl in electrolysis method. Large quantities of polluted industrial waste water are the result[4]."

Jan 1, 2012