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By Ling-yun Yi, Yuan-bo Zhang, Bing Hu, Zhu-Cheng Huang, Zhen-yuan Liao

"Nucleation and growth mechanism of iron crystal grain in coal-based shaft furnace direct reduction process by microwave heating were investigated by optical microscope, scanning electron microscope and EDX. The results indicate that microwave has selectivity on various minerals which absorb microwaves. The high temperature in certain area of pellets and thermal stress on the interface of minerals are formed, results in the wustite grain smashed along the joints, and iron crystal grains turned out a spherical shape obviously. The iron crystal nucleus is formed firstly at the edge of wustite, on the interface between grains and in the holes in pellets, and grows gradually while reduction carries on from surface layer to inner core. Microwave heating promotes the rate of transportation and accumulation of the iron crystal grain, increases growth rate of iron crystal grain and contributes to formation of dense iron-jointed crystal texture eventually.IntroductionMicrowave energy as a new energy, which selectively heating materials through internal energy dissipation, has the advantages of heating uniformity, high thermal efficiency, fast heating, clean and pollution-free compared to conventional heating motheds. Microwave energy also has obvious superiority in increasing productivity. Thus, it has been widely used in many areas, including electronics, food processing, chemical, medicine, environmental protection, and family life etc [1]. As a rapidly developed green metallurgical method, microwave heating also has been widely recognized by areas of grinding, pretreatment, pre-reduction, drying, furnacing, metal extraction, and waste materials processing and utilization. Some research achievements are gradually putting into practice, showing great potential in chemical and metallurgical industry [2-3]."

Jan 1, 2011

By Chang-Young Choi

Korea Zinc commenced zinc production in 1978 with a capacity of 50,000 tpa. Since then, continuous investments have been made and resulted in Korea Zinc now being the biggest zinc and lead producer in the world. In the course of increasing zinc production capacity, the company management realized that the company needed a lead smelter to prevent the solid waste disposal problems by treating the lead containing solid waste. This paper begins by briefly stating the objectives and the roles of the lead smelter at Onsan. It describes the QSL process and the TSL process, and further extends the description of the TSL process, through which harmless inert solid waste could be produced for secure final disposal. It is also mentioned that the TSL process plays an important role in the integration of zinc and lead production. Throughout the paper, a positive attitude in handling the environmental issues in the non-ferrous smelting industry is emphasized. Finally, a solution for the solid waste disposal problem in the zinc and lead industry is proposed, with which the environmental issues can be an opportunity rather than a crisis. The current operation at Ousan suggests the future direction of the non-ferrous smelting technology that all of the zinc and lead producers should pursue.

Jan 1, 2003

By Faustino G. Prado

In the, quest for an economical and environmentally friendly reclamation of metallurgical dusts generated during pyrometallurgical operations, our goal has been the separation and recovery of most of the components, as well as the complete recycle of all the reagents. Effluents have been avoided, within acceptable economic parameters. This presentation, which can be applied to a large spectrum of dusts and other residual-materials-, has focused on the dusts generated by the operation of Secondary Copper Smelters. Those dusts show a wide range of components, including zinc, lead-, copper, cadmium, tin, chlorine and-alkalies. Our present work deals with the use of ammonium salts in the separation and recovery of-the above mentioned elements in a marketable form. Most of the chemistry and techniques involved have teen already confirmed in commercial scale operations. Others have gone through pilot scale tests or bench scale tests. The recycle of reagents has also been- confirmed at the same operating levels. A preliminary evaluation indicates that the chosen route, in addition to a viable economy, offers a complete and safe reclamation within the most strict environmental regulations.

Jan 1, 1995

By Zongliang Zhang

Electrowinning is a significant step in metal extraction processes. Because the nature of electrowinning is to reduce metal from its oxidized state, substantial energy consumption accompanies it. Electrowinning processes of different metals have much in common—the deposition of the metal on the cathode and the counter-reaction on the anode. An advanced model was developed that can be applied to a variety of metal electrowinning processes. A model for specific metals can be readily obtained by modifying parameters such as potential, kinetics, and side reactions in the model. The model incorporates mass transfer, gas-liquid flow, electrochemistry, and deposition, making it a comprehensive electrowinning model. The model is applied to copper, nickel, and zinc and verified with the experimental results. In addition, the parameter settings and results of different metals were compared, showing that this model has great versatility and accuracy, thereby making it an efficient and effective research tool.

By P .. R. Ammann

A two-stage pyrometallurgical process has been developed for the recovery of copper (and other non-ferrous metals) from copper smelter slags. All types of slags, including highly oxidized, converter-type slags, are cleaned in an electric furnace which employs mechanical mixers to promote magnetite reduction and copper extraction at high rates. In a 10-ton pilot furnace, it has been demonstrated that slags can be cleaned to 0.2-0.3 per cent copper with economically acceptable usage of raw materials and energy; copper is recovered as a high-grade matte. Pilot plant data have been scaled up to a commercial furnace and engineering designs have been made for a furnace to treat 60 tons per hour of slag from a Noranda Reactor and the associated converters. Plans are being formulated for the construction of a prototype slag cleaning furnace.

Jan 1, 1976

By A. C. Wadhawan

In the present context of rapid industrialization, production of Lead-Zinc metals from low grade materials, residues and wastes can make substantial contribution to the supply of these metals in India. Recovery from secondary sources also plays an important role in conservation of mineral resources and lower power consumption. Conscious effort is therefore, required to increase the secondary metals which, besides saving in energy cost will also help in waste material management and keeping environment clean. The major thrust is, therefore, needed in this direction. During all these years, the Indian Lead- Zinc industry has made sustained efforts for recovery of metals from low grade ores and from metallurgical wastes and residues. The paper identifies the treatment of low grade ores by various technologies and techniques and the treatment of metallurgical residues and wastes generated during primary Lead and Zinc smelting in India. Some of the major achievements in past decade have also been elaborated in the paper. The strategies to be followed for continuing treatment of low grade ores and waste materials by adopting newer, environmental friendly technologies, in consonance with the rigid standards being adopted by most of the countries including India. have also been dealt with in the paper.

Jan 1, 1994

By U .. C. Rojas, J .. C. Gomez

"Fire Refined Copper (EI Teniente Three Stars) has been produced at Caletones Smelter of Codelco Chile since almost the beginning of its operations.Due to changing features of the copper market, together with the targets on technical efficiency and productivity, it has become more and more relevant for copper industry to reach both, good final product quality and a proper environmental control.At present, copper refining process at Caletones Smelter takes place in two cylindrical tilting furnaces, where solid fluxes are injected through horizontal tuyeres into the molten bath. (Fig. N2 1)Solid reagents are pneumatically conveyed and injected into the liquid copper bath attaining excellent solid - liquid contact, so the impurities removal efficiencies are found to be high. Same injection tuyeres are used to introduce both oxidising agent (normal air) and reducing agent (reformed gas) into the molten bath. Air or nitrogen is used as conveying gas for solid reagents, depending on the process stage.This pap~r gives a fundamental description of the process and industrial results related to the injection of blend of sodium and calcium carbonates to remove arsenic and antimony, silica and granulated reverberatory slag to remove lead and a mixture of calcium carbonate and mineral coal to reduce the selenium content of the fire refined copper."

Jan 1, 1996

By Rauno Peippo

Horizontal Waste Heat Boiler (WHB), today's proven and dominating technology for copper smelter gas cooling, has been utilized by the industry for over half a century. During this time development has taken place in geometry, flow characteristics, cleaning technology and design details. This development has been driven by improved understanding of the specific process requirements, gained both by wide experience and by utilizing new emerging design tools, like computer flow modeling. It had to wait till mid 90's to unite effective and proven Spring Hammer cleaning technology and the process benefits gained by gas guiding vanes or baffle wall in the copper smelter WHB design. The new design has demonstrated improvement in gas cooling efficiency and the process conditions down stream in form of less dust sticking problems in the boiler and precipitators. Reduced weak acid production has also been reported as a result of the design. The theoretical aspects, computer flow modeling results and actual benefits measured in old smelting line modernization are discussed. Experience £tom modernization projects such as Phelps Dodge, Atlantic Copper, Mexicana de Cobre, and Nippon Mining, Saganoseki, are discussed. In mechanical design there has been development resulting improved gas tightness with less corrosion and better control of dust sulfation. An essential improvement is the integration of the boiler hopper and dust removing conveyor. Having no steel plate casings in the hopper and conveyor section but using of boiler tube membrane instead eliminates thermal expansion differences. The dust conveyor will be effectively cooled against hot dust lumps falling down while the acid dew point corrosion is prevented in the cooler sections of the hopper. Conceptual features are presented of a new generation Copper Flash Smelter WHB presently under construction at Boliden Mineral, Skelleftehamn, Sweden, where the latest development and innovations are adopted.

Jan 1, 1999

By B. S. Boyanov

The hydrometallurgical technology for zinc production in Bulgaria is characterized by the use of considerable quantities of imported zinc concentrates and several kinds of Bulgarian ones which are quite different in chemical, phase and granulometric compositions. In this connection, 7 sulfide zinc concentrates (Bulgarian and imported ones) were investigated by chemical analysis, DTA, TGA, X-ray diffraction analysis, sieve analysis. The accomplishment of optimal mixing of concentrates and providing stabile mix composition for a long period of time of roasting in fluid bed furnace is a task of primary importance in the technological process control in zinc hydrometallurgy. This can be achieved using mathematical optimization methods.

Jan 1, 2006

By Nexhmedin Lohja

Macro management of metallurgical industries becomes an important issue in certain situations especially when some government owned metallurgical industries are on the verge or have stopped being feasible. In these cases a government lead macro management in collaboration with domestic institutions and foreign scientific and management expert companies is decisive in order to steer them to a profitable path. This process is not necessary an easy one and incorporates many unknowns and various alternatives. In this paper the macromanagement of the metallurgical industries in Albania will be described as a particular case along with a survey of its mineral deposits, metallurgical facilities and various perspectives for future development. As a country with many mineral resources, the exploration, research, exploitation and processing work of mineral ores before 1990 constituted an important activity of its economy, especially in the exportation of various products of this industry. Since 1990 this activity slowed downs considerably for various reasons and this prompted the necessity of a government lead macromanagement in collaboration with domestic institution and foreign expert companies. This process aims at improving and renewing the technologies in the metallurgical industry in order to transform it into a feasible branch of economy. This goal is being implemented among others through proper geological surveys, rehabilitating and renewing the existing facilities through domestic and foreign investments, the transformation of the ownership or the management from state-owned to local or foreign private companies, etc. Priority is given to the raising of the processing range of the traditional minerals such as chromium, copper, nickel-iron etc. as well as developing new perspective technologies to treat new mineral deposits.

Jan 1, 2006

By Peng Jianping, Feng Naixiang, Di Yuezhong, Wang Yaowu, Pan Xijuan

A vacuum silicon thermal reduction lithium process is developed in present work which used lithium hydroxide, alumina and calcium oxide as raw materials. The process contains two steps, which are that Li5AlO4 clinker is prepared in ambient environment, and that metal lithium is extracted from Li5AlO4 clinker with ferro-silicon alloy as reductant in vacuum. On the basis of thermodynamic analysis and investigative experiments, feasibility of this process is proved. The results show that Li5AlO4 can be generated by calcination lithium hydroxide and alumina, the burning loss is above 31% under the conditions of calicination temperature above 750℃ and time more than 90min. The main phases of calcination product are Li5AlO4 and CaO. When the calcination product is reduced by ferro-silicon alloy in vacuum, the lithium reduction ratio can be over 80% under the conditions of reduction temperature 1200℃ and reduction time 60min.

Jan 1, 2014

By Brian Lightfoot

Ausmelt Technology uses a furnace/slag/lance system in a way analogous to the way a chemical engineer would use a mixed reactor. The technology is sufficiently versatile to treat materials under a very wide range of temperature and chemical conditions. At one extreme the system has been operated at temperatures high enough and oxygen potentials low enough to make iron. At the other extreme it has been operated of temperatures as low as 800°C and oxygen potentials high enough to cupel lead from silver. This versatility permits the treatment of a great variety of wastes including asbestos, mixed organic\heavy metal wastes, incinerator ash smelter residues, waste water treatment sludges, organochlorine compounds and many others.

Jan 1, 1994

By Wilhelm Brandstätter, Johannes Steiner, Alois Triessnig, Christian Redl

"The results of numerical simulations of bubble detachment from an orifice in a horizontal plate submerged in liquid are presented. The bubbles are created by forcing gas through this orifice into stagnant liquid. The simulations are performed with a two-dimensional incompressible Lattice Boltzmann (LB) scheme. In previous works the same problem was investigated by two-phase simulations in which surface tension effects were considered by an interaction potential formulation between the phases. In contrast, in the present work a volume of fluid (VOF) model consisting of a carrier fluid and a passively advected scalar function for the calculation of gravitational and surface tension forces, respectively, is used. The aims of this study are to examine the applicability of the one-phase LB method to the numerical analysis of bubble formation and to verify the theoretical and experimental predictions of the dependencies of the departure diameter on gravitational forces, surface forces and wettability effects. To this purpose the simulations were performed at different values of gravitational acceleration g, surface tension coefficient s and contact angle ß. Nonlinear fits to the data yield functional dependencies which are in good agreement with the predictions. IntroductionBubble formation behavior is an extensively studied subject, especially in chemical engineering, power industries and metallurgical processing. Knowledge of the underlying physics of bubble motion is, for example, required for the design of chemical reaction towers and agitation tanks. Another important application is the argon gas injection through the wall of the tundish nozzle into liquid steel stream to deter clogging with solid inclusions. Argon bubble motion and its effect on flow depends greatly on different parameters, e.g. gas flow rate and size of the bubbles. Thus, if these bubbles are not managed properly, they can become encapsulated upon solidification and result in undesirable impurities in the material [1, 2]."

Jan 1, 2004

By Li Zhang

A novel green technology to recovery Titanium compounds from Ti-bearing blast furnace slag under the dynamic oxidation condition was developed and tested. Air was blown into the molten slag as oxygen resource through a lance during the dynamic oxidation process, in which six important results were found: (1) The TiC, (Ti2O3), Fe and (FeO) in the slag were oxidized; (2) The temperature of slag temperature rapidly increased; (3) The viscosity of slag decreased; (4) The coalescence, growth and drop of the metallic Fe droplets in the molten slag were carried out under an air agitation condition; (5) The dispersed Ti components were selectively enriched into the perovslite phase, and the perovskite phase could be selectively precipitate and grow. And also, the perovskite phase can be separated by the dressing method. The oxidation of molten slag gives off a large amount of heat, which helps chemical reactions proceed, improve the rate of chemical reactions, and promote the precipitation and growth of the perovskite phase. The features of the technique are clean, low cost and a great capacity to deal with a large quantity of slag. It was confirmed by experiments that the precipitation of the perovskite (CaTiO3) in molten slag is obviously affected by operation factors such as temperature, chemical composition, heat-treatment, additives and so on. The precipitating kinetics and mechanism of the perovskite phase from molten slag during the dynamic oxidation processes were also investigated.

Jan 1, 2006

By S. C. Grund

In secondary copper smelting as it is performed at Hüttenwerke Kayser plant in Lünen, tin-and lead-containing flue dusts are produced as intermediate products. These flue dusts are further processed in a hearth furnace. Followed by certain refining operations a saleable tin-lead-alloy is produced. Even though the hearth furnace technology has been in use for this purpose for a long time still its performance undergoes changes in search for optimum processing conditions regarding to the increasing complexity of the raw materials and tightening economical and ecological boundaries. The use of modern statistical tools for the calculation of accurate mass balances is demonstrated for the tin-lead hearth furnace. These reliable mass balances are the basis for any further modelling of the process with the aim of optimization. Incorporating metallurgical knowledge and experience as well as different mathematical modelling techniques, further studies are planned in which the recoveries of valuable and minor elements and their dependency from various process parameters are examined. The aim of this modelling is to optimize the recoveries of the valuable elements, to minimize the energy consumption and the processing costs and thus to keep the process competitive in a harsher economical and ecological surrounding. The modelling principles are transferable to other metallurgical operations and are especially suited for ill-defined pyrometallurgical processes.

Jan 1, 1999

By Shengli Tao, Hongxu Li, Hao Bai, Yu Chen, Daqiang Cang

"China is the world's largest steel producer, in order to give environment load comprehensive analysis of steel and iron industry in china using LCA method, the life cycle inventory was compiled and assessment model based on Gabi software was also established. Environmental impact of two different routes ofBF-BOF and the EAF were analyzed respectively and intercompared. The results show that the modem EAF route is superior to the traditional BFBOF route on almost all the environmental impact indexes, which including acidification potential, eutrification potential, global warming potential, ozone depletion potential, etc. In the whole life cycle ofBF-BOF route in China, the transporting process ranks the biggest contribution part to the overall global warming potential, which can be explained by the fossil fuel burning of transporting vehicles during the long distance from Australia to China as the iron ore used are mainly imported from Australia. Apart from transporting process, Coking, blast furnace and iron mining processes could induce great environmental problems, while for the EAF route, the electricity consumption is considerable, which causing large amount ofC02 emission indirectly. Based on the analysis, several further countermeasures were proposed. Key words: Iron and steel industry, LCA, Gabi software, C02 emissionIntroductionCrude steel of china which reached 101.24 million tons in 1999 ranked the first column in the world since1999, So far has been to keep the world's largest steel output. At the year of2009, China crude steel output of 568 million tons, accounting for 46.6% of the global crude steel production, more than the total sum of crude steel production produced by 20 countries ranked behind. In 2011, China's crude steel production which is expected to be or close to 700 million tons, an increase of 12% than last year, will account for half of the global steel production.The steel industry, however, is intensive resources industry with huge consumptions of energy and water together with mineral resources. Energy consumption of the iron and steel industry has been about 10% of the total energy consumption since 1980. Coal dominants, power next and other energies share least in the energy consumption structure, for example coal accounts for 72.19%, power 23.52% and other total sums less than 5% in the steel energy consumption at year of 2002[2,3]. The consumption of coal discharges much emission of CO2, yet emissions of C02 in China steel industry, secondary only to the power and cement industry, ranked the third, and the coal dominant energy structure and its process have a close relationship. The aim of this research is to target steel production of typical blast furnace-converter (BFBOF) and electric furnace, using GABI software to evaluate and analyze resources and environment influence of LCA, directing at the existing problems in the development of China steel as well as finding the possible way to improve ability of reducing pollution and energy consumption in order to realize the sustainable development of the steel industry [ 4-7]."

Jan 1, 2012

By Manuel Zamalloa

The outstanding metallurgical performance of the Noranda continuous converter (NCv) in operation since November 1997 has allowed the company to meet production and environmental targets. This achievement positions this new technology as a strong alternative continuous converting technology for copper production. Knowledge of slag chemistry has been important in this respect. The purpose of this paper is to discuss the effect of key parameters including temperature, oxygen potential, slag composition and levels of copper oxide in slag on the conditions leading to magnetite precipitation, as well as on the conditions affecting the liquidus ranges of NCv slag. The above variables are evaluated using industrial data and thermodynamic predictions. Practical implications of customizing operational fluxing procedures to determine optimum operating windows are also discussed.

Jan 1, 1999

By Laurence Whitty-Léveillé

Proper handling of the radioactive fraction associated with the production of rare earth elements (REEs) in the mining industry is essential for a sustainable environment and human health. Actinides, such as uranium and thorium, have similar chemical properties to REEs, and are often co-dissolved in current hydrometallurgical processes. This causes radioactive contamination of the infrastructure through the extraction cycle. The present study optimizes, through experimental design, a sequential leaching procedure with Na2CO3/NaHCO3 and HCl for the rapid and selective dissolution of REEs and actinides. Optimization focuses on the main operating parameters (time, temperature, and concentration); different types of minerals, REE composites, and ores; on achieving maximal leaching yield; and on minimizing dissolution of the gangue metals (Fe, Si, and Ca). The final sequential procedure was rapid (1 h), effective, and led to the segregation of Th, U, and REEs with limited dissolution of the gangue metals.

By QinGuo, Shenghui Guo, Jinhui Peng, Linqing Dai, Libo Zhang

This paper adopts a simple and novel preparation. Taking cellulose as a template, a tubular morphology structure of micro/nano ZnO crystals was obtained by microwave roasting at high temperature. The higher the microwave roasting temperature, the larger the degree of crystallization. The experiments indicate that the best photo catalytic effect can be obtained at 850 : At this temperature, the oxidation of cellulose is complete. Large quantities of hexagonal shaped ZnO crystal can be observed, specifically the (0001) crystal face. Under ultraviolet-visible irradiation, taking long arc mercury lamp as light source, the material had good photocatalytic activity. The decomposing efficiency of methylene blue reaches 97% in 60min, which is superior to that of preparations without templates at the same temperature.

Jan 1, 2016

By Han Ilhan

This paper discusses and describes aspects of a cost effective and safe tailings impoundment selection. In light of the current low metal prices and recent tailings embankment failures around the world, it is becoming extremely more important to develop tailings impoundment design that balance cost efficiency with safety. The paper will present critical design components associated with a tailings impoundment which need to be addressed during the planning phase. Procedures for identifying various tailings impoundment alternatives, and evaluation and selection of alternatives are presented.

Jan 1, 1999