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By J. T. I. Poijärvi

The smelter off-gas cleaning and the weak acid treatment at Outokumpu Harjavalta Metals Oy are presented and described in this paper. The smelter consists of the copper and nickel smelters and the acid plant of three separate acid plants two of which are double contact and one single plant and of one liquid sulphur dioxide plant. The preliminary cooling and flue dust separation of the smelter off-gases from the copper and nickel flash smelting furnaces and converters in the waste heat boilers and in the hot electrostatic precipitators are described. The final cooling and cleaning of the gases in the scrubbers at the sulphuric acid plant and the treatment of the weak acid in the vacuum and in the submerged combustion evaporators for the removal of impurities are pre¬sented as well as the treatment of the condensates from the evaporators. The attention is paid to the generation of sulphur trioxide in the smelter off-gas and to the treatment of that in the weak acid bleed-off and to the utilization of the treated acid.

Jan 1, 1992

By E. Gutierrez-Miravete

Hot pressing processes are widely used to shape metallic, ceramic, and glass components. The process is an essential step in manufacturing ceramic fibre-glass matrix composites. The paper describes the use of computer simulation by the particle method, to the analysis of the deformation and flow of glass during hot pressing. The hot glass is represented by an assembly of interacting particles which deform in response to the applied pressure. The results, which should be regarded as complementary to continuum-based studies, provide useful insight about the hot pressing process.

Jan 1, 1990

By N. Tsuchida

Sumitomo Metal Mining Co. Ltd. (SMMC) is currently developing the flowsheet to treat stockpiled limonite, a type of laterite ore, at Rio Tuba on southern Palawan Island, Philippines. The new plant will be commissioned at the end of 2004. Rio Tuba Nickel Mining Corporation (RTNMC) has been mining saprolite since 1977, and the limonite ore located above the saprolite ore body has been stockpiled separately according to nickel and magnesium content. Ore from these stockpiles will be blended and used for the operation. The annual production of nickel will be 10,000 metric tons for the next twenty years. The proposed process consists of ore preparation, high pressure acid leach (HPAL), counter- current decantation wash, impurity removal and sulfide precipitation. Precipitated mixed sulfide will be processed to electrolytic nickel by the Matte Chlorine Leach Electrowinning (MCLE) process at Niihama, Japan. SMMC has established new technologies during the process development, such as zinc removal and sulfide precipitation. Applying this technology, preferential removal of zinc can be achieved by hydrogen sulfide gas with negligible loss of nickel. Precipitation of nickel by hydrogen sulfide gas is carried out at low temperature. Slow kinetics is selected for control of the particle size of the precipitated mixed sulfide. Keywords: HPAL, Zinc Removal, MS Production

Jan 1, 2004

By Cheng Fang, Zhou Lie-xing, Peng Jin-hui, Guo Sheng-hui

This article discusses the behavior of temperature and microwave thermo gravimetric analysis characteristic of ammonium paratungstate in a microwave field. Experimental results show that when 12g of material is place in a microwave with 900W of power, paratungstate’s temperature rises at 70°C/min. This results in paratungstate’s temperature being 980°C after 14 minutes. Compared with thermo gravimetric analysis characteristic, former two-step process of paratungstate microwave calcined completed ahead of schedule, after two-step process reaction is more intense,Paratungstate warming is more rapidly, the reaction time is much shorter; According to XRD and SEM, the product is high purity, the crystal particle size is uniform, and the grain size is fine.

Jan 1, 2015

By Ting Cheng, Guang-sheng Wei, Ze-shi Yang, Ling-zhi Yang, Yu-feng Guo

The application of the bottom-blowing in the steelmaking process of EAF can effectively shorten the mixing time of the molten bath, accelerate the removal of carbon, phosphorus and sulfur, and improve the production efficiency and product quality. Information about the effects of changing molten steel velocity during the smelting process would help to accurately model molten bath dynamics. In this study, numerical simulation software was employed to simulate the EAF steelmaking process under variable eccentric bottom-blowing gas flow situations. Velocity field data were obtained for the different bottom-blowing schemes. When other nozzles’ bottom-blowing gas flow rates were maintained at 133 L/min, the average velocity of molten steel in EBT (Eccentric Bottom Tapping Area) was increased from 2.8 10−3 to 3.4 10−3 m/s with the eccentric gas flow rate of bottom-blowing from 100 to 267 L/min, the average velocity of molten steel in the bath increased from 4.3 10−3 to 4.6 10−3 m/s with the eccentric gas flow rate of bottom-blowing from 100 to 267 L/min.

Mar 1, 2018

By Jun Deng, Daohong Wu, Zhicheng Cao, Jingkun Tang, Luxing Feng, Xun Xue

The effect of reducing temperature, H2/CO mole ratio, and reduction gas flow rate on the metallization rate of oxide pellets were investigated at laboratory scale, with ludwigite iron concentrate used as raw materials. The reducing temperature varied from 850 to 950 °C, the H2/CO mole ratio changed from 1.5 to 4.5, the range of reduction gas flow rate was from 2 to 5 L/min. The results indicate that the metallization degree of pellets increase with increase of the temperature, H2/CO mole ratio, and gas flow rate. However, after temperature rises to 850 °C, metallization degree increases slowly. The effect of H2/CO on the metallization degree is not very obviously with the ratio of H2/CO increasing from 1.5 to 4.5. When the gas flow rate was increased from 2 to 3 L/min, the metallization degree increased greatly from 72.2 to 92.1%. In the flow range from 3 to 5 L/min, the metallization degree was increased slowly. The results obtained could be useful for comprehensive utilization of ludwigite iron concentrate by gas-based direct reduction method.

Mar 1, 2017

By Rameshwar Sreenivasan

This paper presents a sustainability analysis of Selective Laser Sintering (SLS) from an energy standpoint. Data of electrical power consumed by the system over an entire build were acquired using a LabVIEW 8.6 circuit. The power drawn by individual subsystems was also measured, and an energy balance was performed. These data were then used to arrive at a Total Energy Indicator of the process with the help of a specific type of Environmental and Resource Management Data (ERMD) known as Eco- Indicators, which indicates the level of sustainability of the process.

Jan 1, 2010

By A. Cullaj

Several industrial sites suffer from the contamination of soils from heavy metals, which are emitted among others by anthropogenic mining and metallurgical activities. Effective and economic physicochemical technologies for remediation of these sites remain complicated and costly. A new alternative remediation technique is the so-called phytoremediation. This is based on the ability of some plants to accumulate very high concentrations of metals from soils and thus providing the basis for a remediation of the contaminated sites. This technique as an emerging branch of natural biotechnology, has several advantages compared to the sophisticated physicochemical techniques of soil remediation. It is not only environmentally friendly but also its costs are quite low since it is solar driven. Furthermore plants can accumulate metals to such levels that the mineral recovery maybe feasible even in conventional Ni refinery or smelting operations. n this work, the potential of many plants to accumulate nickel has been investigated in order to identify the species which offer the best phytoremedial potential for nickel contaminated soils in Albania. Field surveys have been made in five nickel-containing sites in order to identify the nickel tolerant species that have spontaneously grown in contaminated soils. Atomic Absorption Spectrometry measurements were carried out on 145 different plants collected. 16 of them were identified as having an hyper ability to accumulate nickel since they contained more than 10 000 mg Ni per kg (OW). Seven taxa are of Alyssum genus and one of BornmueIIera genus of Cruciferae. The highest accumulation of nickel was present in aerial parts of Alyssum murale var. chlorocarpum Hausskn (25 500 mg/kg or 2.5%) and Alyssum markgrafii O.E. Schulz (23 700 mg/kg or 2.37%). The seeds germinated are more evidenced at A.m.var. chlorocarpum, about 63%. These plants are suggested as the most promising species to be used for phytoremediation purposes in nickel contaminated soils and phytoextraction of nickel.

Jan 1, 2003

By J. S. Becker

Technology developed and first implemented in the United Kingdom enables very low grade aluminum scraps containing oils, organics, plastics and ferrous metals to be directly charged, without pretreatment, into a unique melting furnace. The system has been in full scale production for four years. The oxy-fuel-based furnace design incorporates internal afterburning in the furnace's hot zone, producing excellent thermal efficiency and very low emissions. The furnace is inherently low in NOx. This paper will provide both theoretical background and extensive operating results for this new melting concept. Applications describing both purpose built new furnaces and retrofits of existing reverberatory furnaces will be presented. Extensive operating emissions data will be presented.

Jan 1, 1997

By W. Gutmannsbauer

Thin films of TiO2 nanoparticles have been prepared by different reactive deposition methods, such as electron evaporation, ion plating and ion beam sputtering. Many properties especially the optical properties, are strongly related to the film morphology and surface roughness. Scanning force microscopy was employed to obtain information on the surface structure of as-deposited Ti(h thin films. The influence of the deposition conditions and the film thickness on the optical and structural properties has been investigated. The as-deposited films were found to be amorphous or polycrystalline with anatase structure.

Jan 1, 1995

By T. Ueno

Naoshima Smelter & Refinery of Mitsubishi Materials Crop. commissioned a new Mitsubishi continuous copper smelter in May 1991. Process offgas volume of the conventional reverberatory furnace line, one of the previous smelters having been shut down, was very large and thus two acid plants had been operated. It was expected that the offgas volume would, be reduced at the new smelter to about a half of the sum of those from previous two smelters and the sulfur dioxide strength would be increased. So various alternatives were studied to minimize the operation cost. And it was decided to utilize both of the plants with minor modifications by diluting the gas either with air or with dilute gases. The acid plants now receive off gases from the new copper smelter, a sintering machine of a lead smelter and a decomposer of waste acid. The paper discusses plant design, operation, improvements and modifications realized in relation with the retrofitting of the copper smelter.

Jan 1, 1992

By Christina V. White

An experimental study was undertaken to investigate the feasibility of utilizing vapor transport for the treatment of heavy metal contaminated smelter soils. The focus of this project was to develop process chemistries that would make incineration a viable process for the treatment these soils. The experimentation concentrated on the elimination of arsenic, cadmium, and lead, and was performed in a laboramry scale rotary kiln setup. Three soil samples from non¬ferrous smelter sites, which contained various concentrations of contaminants, were utilized in the experimentation. Three chemistries were investigated for the volatilization of the heavy metals: Chloridizing volatilization, ferric chloride vapor complex formation, and the use of oxygen potential control. The samples were analyzed for residual heavy metals so that the extractions could be determined. However, the ultimate test was the leachability of the residual arsenic, cadmium, and lead, as determined by the TCLP test. The results firmly establish that incineration is a feasible process for the treatment of metal contaminated soils. It was found that no one process chemistry is suitable for all different soil samples. A two-step process consisting of a reducing step followed by a hydro-chlorination step was required to make Soil Sample-B pass the TCLP tests for all three heavy metals. Soil Sample-A passed the TCLP tests for arsenic, cadmium, and lead using a hydro-chlorination process at a minimum temperature of 700°C. In addition to passing the TCLP mm for Soil Sample-A and Soil Sample-B, 70 to 80 percent removal of the impurities was accomplished. This demonstrates that the leachability of the impurities was decreased primarily due to the removal of a large fraction of the contaminants, Soil Sample-C possessed very high levels of cadmium and lead and only moderate extractions of the impurities were generated from this soil. The arsenic TCLP test was passed at 500'C using a process gas containing ferric chloride and at temperatures of 700°C and above using chlorination of hydro-chlorination.

Jan 1, 1996

By F. Kassabji

This publication presents the main experimental and theoretical results on the recovery of aluminum scrap (dross and Used Beverage Can) without use of any addition of fluxing salts. Dross and UBC's processing experiments have been conducted in a rotary plasma furnace operating in the transferred and non-transferred mode, using different plasma gases. The investigation involved the treatment of more than 100 kg of dross and other aluminum residues using plasma torches with less than 100 kW power. The experimental work showed that this process is .far more economical and kind to the environment than the conventional route using a salt flux. An equilibrium thermodynamic calculation at elevated temperature makes possible the prediction of by-products at various temperatures for different plasma gases.

Jan 1, 1994

By Huimin Lu, Lian Zhou, Qiang Li

"A three-dimensional mathematical model is developed for the regenerative rotary hearth furnace with 40 meters medium diameter. The influence of combustion switchover and outlet pressure on the fluctuation and distribution of temperature and pressure is studied with numerical simulation method. The results showed that the temperature field and flow field is suitable for requirement of industrial production; the fluctuation of the temperature field and pressure is acceptable; the influence of outlet pressure on the furnace pressure is great.IntroduceRotary hearth furnace which is originally utilized as heat treating and reheating industrial furnace, now is also used for carbon based DRl production. With the need of market and the concern of resource recycling and environmental issues, the DRl production from ore or from waste material by rotary hearth furnace attracts more and more attentions from steel industry [1,2].When rotary hearth furnace works, the feed pellets are charged on the hearth and rotate within an annular furnace chamber with the process of reduction. For the sake of rapid reduction, usually the depth of the pellet is one or two layers, accounting for less than 90% of the volume of furnace. As result, the exhaust gases carry away a lot of heat, so that energy utilization efficient is low [3]. Currently, in order to reduce the consumption of energy and improve the production efficiency, many methods have been adopted. The regenerative combustion technology is one of the most promising."

Jan 1, 2013

By D. M. Wyslouzil

The fundamentals of dissolving silver and silver minerals are discussed in the following sections: 1) Basic chemical reactions in the silver system 2) Leaching of pure silver minerals 3) Leaching of silver-bearing ores 4) Description of processes The basic chemical reactions of silver are an important guide to the mineral processor or the extractive metallurgist, particularly for systems in which complex formations are balanced against solubilities. The competition of other cations for free ligands can shift the equilibrium to the detriment of silver. Solubilities of pure silver minerals in specific solvents may not be a good indication of the solubility of silver minerals in ores. The abundance of silver minerals which usually appear in a typical ore precludes the selection of a single method that would result in the best extraction of silver from all minerals in the ore. Frequently, the recovery of silver from host minerals requires a destructive pretreatment such as intensive leaching, oxidation with or without elevated temperature and oxygen pressure, or roasting. The transformation of the host or the silver minerals does not always result in a leachable species? and this requires additional treatment before the precious metal can be recovered.

Jan 1, 1990

By Robert W. Bartlett

"Economic and other factors, mostly outside of metallurgy, that strongly influence applied research, development and especially successful commercial adoption of new processes for producing primary metals and other commodity materials are reviewed. These factors, which can be both positive and negative in their influence, are often too lightly regarded in the research planning stage. They include continuing imperatives that have long influenced new process development as well as more recent trends. Both are discussed. Nearly all new materials eventually become commodities--products made to standard specifications with no producer control over price. Success requires being a low cost producer on a world wide basis. Composites and other complex material assemblages are unlikely to escape this fate as they mature.INTRODUCTIONThe adoption of new processes, beginning with research and development, for primary metals and other commodity materials is particularly difficult because each new process must supplant an existing process that is already being used commercially. There are many requirements besides technical innovation and cost superiority that must be met by the new process. Consequently, few innovations make it all the way from the research laboratory to commercial success.This paper discusses some of the factors that influence success in developing new processes for primary metals and commodity materials, based on the authors experience as a research metallurgist and industrial research manager. It begins with some of the factors that are always present and constrain successful process research and development, and proceeds to current trends that are expected to continue long enough to influence processes in the year 2000. Many of these trends are contradictory in their effect on new process development, and the future remains uncertain.The prevailing importance of these trends will vary with the material, process concept and other factors intrinsic to each case. Nevertheless, an awareness of these influences can help to avoid some of the R&D pitfalls and dead ends. Such awareness is deemed to be a necessary condition to avoid failure when commercial adoption of a new process is the goal."

Jan 1, 1988

By Xingye Guo, Yeon-Gil Jung, James Knapp, Zhe Lu, Jing Zhang, Li Li

La2Zr2O7 is a promising thermal barrier coating material due to its low thermal conductivity and superior high temperature stability. In this work, Bilayer La2Zr2O7 and conventional 8 wt% yttria stabilized zirconia (8YSZ) coatings were deposited using plasma spray technique. Both singlelayer La2Zr2O7 and double-layer 8YSZ/La2Zr2O7 coating architectures were designed. Thermal cycling and thermal shock tests were used to evaluate coatings’ thermomechanical properties. All La2Zr2O7 coats were delaminated in the furnace cycle test in less than 20 cycles. This is because residual thermal stresses accumulated during thermal cycling. In the jet engine thermal shock (JETS) tests, the SCL La2Zr2O7 and DCL dense 8YSZ/La2Zr2O7 coatings were fully delaminated. In contrast, the DCL porous 8YSZ/La2Zr2O7 coating sample only partially delaminated on the edge. This is because of the porous 8YSZ layer provides strain compliance. The findings will help to propose efficient thermal barrier coating systems.

Jan 1, 2016

By H. Masuda

The lijima Zinc Refinery started operation in 1972, and has today an annual capacity of 200, 000+-Zn. The hematite process was employed for the first time and the ideal of waste-free refinery has been pursued for 30 years. In recent years, however, only half of the hematite produced would be sold to the cement industry and hence a reduction of arsenic level has been necessary in order to sell the entire amount produced, The arsenic cementation process with zinc powder, developed through a long time laboratory research was found among some options as the best for the hematite process. The construction work started in 2000 and the facility was put into operation in 200 I. As a result in the same year all hematite were sold to the cement industry. The outline of this project, present operations and technical issue are reported in this paper.

Jan 1, 2003

By Zhou Jun

Water-quenched samples were taken from a commercial flash furnace at three levels along its reaction shaft during operation at high feed rate. The samples were subjected to a series of analysis and observation. Such processes of the feed in reaction shaft as oxidation, desulfurization, melting, slag and matte formation and etc., variations of particle size along axial and radical direction of the shaft are investigated. The following smelting mechanism in reaction shaft named as “Multi-particle and multi-phase fusion model” is proposed: (1) Fragmentation and collision of concentrate particles take place simultaneously in reaction shaft with particle size growing up. Collision produces large-size “unit melt” which falls into the reaction layer in the settler bath. (2) In the settler reaction layer below the shaft, weak bath smelting reactions take place among the shaft products, producing final matte and slag which separate into two layers. (3) The processes in the shaft are all progressive along the whole height of the shaft. The predominant reaction in the shaft is oxidation, not reduction.

By Xiaojian Zuo, Yihua Han, Qingguo Xue, Jingsong Wang, Lintao Wang, Rongzong Lan

"Using the facility of reduction experiment, the low temperature reduction pulverization and reduction behavior of sinter in oxygen blast furnace (OBF) were studied. Through analyzing the results, the difference of pulverization and reduction behavior of sinter in OBF and conventional blast furnace (BF) were discussed. Furthermore, the effect laws of reduction temperature and the content of CO and H2 on reduction behavior of sinter were studied. Also the controlling step of iron oxide reduction was discussed. Compared with BF, the low temperature reduction pulverization of sinter became serious at 773 K; reduction rate became faster at 1173 K; reduction time became less and final reduction degree was increased in OBF. With increasing of H2 and CO contents, the reduction of sinter was promoted. The reduction process was controlled by interface chemical reaction at the earlier stage and by interface chemical reaction and internal diffusion at the final stage.IntroductionThe new ironmaking technology of Oxygen Blast Furnace (OBF) is most likely to be used in large-scale application process. The concept relies on the removal of the CO2 contained in the top gas of the blast furnace. Therefore the useful components, i.e. CO+H2, can be recycled back into the furnace and reused as reducing agents. In addition, injecting oxygen (O2) into the furnace instead of preheated air, removes unwanted nitrogen (N2) from the gas. Under the pressure of CO2 emissions in iron and steel making, the growing international shortage of coking coal resources and the rising price of coke, OBF has attracted attentions of both domestic and foreign researchers, because it has so many advantages such as high productivity, high PCI rate, low coke rate, high gas reducing capability and high top gas calorific value, etc [1-7]. As a result of recycling most of the top gas after CO2 removal and injecting oxygen into the furnace, the reduction capacity of blast furnace gas will be increased, so the metallurgical behavior of OBF's iron burden is different from traditional blast furnace. Therefore, it is one of the keys to develop this technology, which studies the metallurgical behavior of sinter in OBF. The purpose of this paper is to study the low temperature reduction pulverization and reduction behavior of sinter at the atmosphere of OBF, which includes the difference of low temperature reduction pulverization and reduction behavior of sinter in oxygen blast furnace and conventional Blast Furnace (BF). It will provide theoretical basis for the development of OBF."

Jan 1, 2012