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By Hiroshi Tabuchi, Akihiko Takahashi

"High strength aluminum matrix composites were prepared and studied using as reinforcement newly developed nearly mono-dispersed a-alumina single crystal particles each of which has a regular polyhedral shape. The composites were formed by centrifugal casting using aluminum casting alloys (Al-Si and Al-Cu-Mg) as the matrices, followed by heat treatment. The volume fraction of the alumina particles was as high as 60%. The same matrix composites reinforced by conventional crushed fused alumina particles were similarly prepared as the reference. The bending strength and tensile strength of the Al-Cu-Mg matrix composites reinforced by the novel alumina particles of 10 µm in average diameter are as high as 1020 MPa and 560 MPa, respectively, which are higher than those of the conventional alumina composites. Furthermore, the bending strength of the novel alumina composites degraded less than that of the conventional alumina composites after thermal fatigue tests. The number of cracks in the matrix seemed to influence the thermal fatigue property because many cracks were observed in the conventional alumina composites, whereas only a few cracks were observed in the novel alumina composites. This was confirmed by SEM observation of the sample composites before and after the thermal fatigue tests.IntroductionAluminum matrix composites strengthened by dispersed reinforcements are of interest for various applications due to their improved properties, such as high specific strength and stiffness, wear resistance, etc .. A large number of investigations have been made concerning fabrication processes and properties of these composites. With regard to the fabrication processes, powder metallurgy has been well-known as a solid phase process, and recently many liquid phase processes such as a compocasting, a squeeze casting, the Lanxide process, and the Osprey process have been studied and developed.(1)"

Jan 1, 1998

By R. E. Johnson

The No. 3 reverberatory furnace at Phelps Dodge. Corporation's Morenci, Arizona copper smelter first received oxygen from a new oxygen plant during October 1982 and began operation with oxygen-fuel and oxygen sprinkle smelting burners which burn concentrate with oxygen. The furnace was completely converted to roof-mounted oxygen-fuel firing in October 1982. All conventional air-fuel bridge wall burners were extinguished at that time. The novel arch-mounted oxygen sprinkle smelting system began continuous operation April 1983. Since startup, unit fuel requirements decreased and furnace throughput significantly increased. Furnace off gas SO2 strength increased from an average of 1.5% SO2 to an average of 20% using only oxy-fuel burners. Oxygen sprinkle burner operation also has given excellent results, with the furnace off gas strength increasing to 35%-60% S02. There has been a reduction in overall arch temperatures, an increase in matte and slag temperatures, and a lowering of furnace bottom buildup with oxygen smelting. Furnace off gas is blended with converter off gas and treated in a sulfuric acid plant.

Jan 1, 1983

By M. Kobashi, T. Choh, N. Kanetake

"A new processing route, which enables the cost-effective and energy- saving fabrication of metal matrix composites, have been proposed. The pressureless infiltration of the reactive powder blend with molten aluminum was investigated in this work. The molten aluminum infiltrated into the [Ti + C] powder blend spontaneously, whereas the spontaneous infiltration into the TIC powder phase did not occur under the same experimental condition. The processing time was shortened and· the processing temperature was .lowered by adding the aluminum powder in the [Ti + C] powder. The differential thermal analysis revealed that the aluminum powder in the powder blend melted at 933K and then ignited the reaction between titanium and ·carbon. However there was an .optimum additional amount of aluminum in the powder blend. The TiC formed in situ had three-dimensionally continuous morphologyIntroductionThe squeeze casting process has been used as one of the processing routes for aluminum matrix composites. [1, 2]. Non-reactive metal-ceramic systems have been, generally, used in this technique in order to prevent the degradation of the ceramic phase. Materials obtained by this process basically consist of a continuous metal matrix and discontinuously dispersed ceramic particles. Reactive systems have begun to be introduced into the infiltration process· recently [3A]. Since the ceramics are synthesized in-situ, this process can provide a continuous ceramic matrix [5]. This is one of the outstanding features of this technique in that a bulk ceramic-can be synthesized at relatively lower temperatures in a short time. Another advantage is that the highly reactive combination of a ceramic with a molten metal is in many cases wettable [6], which enables a spontaneous infiltration."

Jan 1, 2000

By A. V. Tarasov, A. D. Besser

A processing flowsheet has been developed for treating substandard lead-containing polymetallic bulk concentrates and intermediate flotation products containing precious metals, which comprises oxidizing roasting in a calcination kiln and electrothermic smelting generating low volumes of off-gas. The proposed flowsheet also incorporates a dust collection system and sulfur dioxide recovery from off-gas. It is proposed to implement this process by using a reaction smelting technique. For this purpose, the charge to be fed to the smelting furnace after its calcination in a drum-type rotary kiln must have a ratio of sulfide sulfur to sulfate sulfur of at least 1 :2. Electric smelting makes it possible to produce lead bullion that also collects the precious metals contained in the feed, as well as copper-lead matte and slag containing zinc. The recovery of lead into lead bullion and into matte is approximately 83% and 14%, respectively (thus the overall recovery is 97%); the total recovery of gold and silver into lead bullion and matte is 98%; th\lt of copper into matte is 89%; the recovery of zinc into slag is 96%; and that of sulfur into sulfuric acid or gypsum is 90%. After the recovery of zinc from slag, the latter can be utilized in the construction industry.

Jan 1, 2000

By Shuqiang Guo, Gonghui Yang, Xingxing Zhang, Yuyang Bian, Song Chen, Weizhong Ding, Yinhe Liu, Lan Jiang

One of the most promising refractory materials for application is zirconia in melting superalloy. In this work, the properties and phase composition of magnesia partially stabilized zirconia ceramics (MgO-PSZ) under different sintering temperatures were systematically investigated. Commercial magnesia partially stabilized zirconia (MgO-PSZ) powders were selected as the starting materials. The magnesia partially stabilized zirconia phase composition was measured by X-ray diffraction (XRD), the density of sintered samples was tested by vacuum density instrument, the thermal expansion were obtained by thermal dilatometer from ambient temperature up to 1450°C, and the microstructures of MgO-PSZ were characterised by scanning electron microscope (SEM). The results indicated that the properties of thermal expansion, densification, microstructures and phase composition were significantly affected by sintering temperature. Densification was consistent with SEM micrographs of MgO-PSZ at different sintering temperatures.

Jan 1, 2015

By Sungdon Kim, Chuljoo Kim, Joonsoo Kim, Hosung Yoon

"This study was performed to establish the optimum leaching condition through the experiments for the oxidized roasting followed by leaching of fluorocarbonate rare earth mineral (bastnasite) using sulfuric acid, and to establish the optimum condition for the recovery of cerium by ion- sieve method from the leached solution of bastnasite. The optimum conditions for the sulfuric acid leaching by the oxidizing roasting of bastnasite concentrates are that the roasting temperature is 550 -600 °C, the roasting time is 2 hrs, the concentration of sulfuric acid is 6N, the leaching temperature is S0°C and the leaching time is 3 hrs. At this time, the leaching yield of total rare earth oxides in the leaching of bastnasite concentrates is about 91%. When cerium is recovered by ion-sieve method from the solution obtained by the sulfuric acid leaching of the roasted bastnasite, the optimum conditions are that the TREO(total rare earth oxide) of leached solution is below 70 g/l, the flow rate of leached solution is 9.6 ml/min and the ratio of height to diameter of resin packed in column is above 9. In these conditions, the recovery of cerium of yield 85% and purity 96% is possible.IntroductionThe rare earths are generally called to Lanthanides, which are totally 17 elements including Scandium of atomic number 21 and Yttrium of atomic number 39 in addition to 1 S elements from Lanthanum of atomic number 57 to Lutetium of atomic number 71. Since the separation to each element is very difficult because of their similar chemical properties, the rare earths were used as the mixed rare earths and the mischmetal without separating to each element. However, the high purity rare earths are recently produced commercially to each element so that they are used as the materials for high tech. industry such as electric and electronic materials, catalysts, optical materials, special alloy and 8Uperconductive materials, and their consumption is rapidly increasing. Therefore, the purpose of this study is firstly to prepare leached solution by using the series of process of the oxidation-roasting and leaching by sulfuric acid. Next, second purpose is the separation and recovery of cerium by ion-sieve method."

Jan 1, 1998

By Osamu Iida

Since 'start-up of the larger Mitsubishi Continuous Copper Smelting Process in 1991, furnace relining campaign was gradually prolonged to once every 2 years according to deregulation of governmental boiler inspection. On the other hand, in 1998 Naoshima smelter embarked on an intermediate strategic expansion plan to strengthell its international competitiveness. As part of this plan, modifications were implemented in the copper smelter designed to increase output of anodes from new charge source to 270,000 tpa. In May 1998, treatment of dried neutralized residue was started in C furnace, and during the shutdown for brick relining in April 1999, intensive modifications to the boilers as well as the installation of new spray coolers for furnace off gas treatment were implemented. Finally, the new larger oxygen plant was commenced its operation in May 2000 and the expansion was achieved around 30% increase of anode production from original design.

Jan 1, 2001

By Xiaobing Yang, Abhishek Lahiri, Animesh Jha

"In the FFC-Cambridge process, the cathodic dissociation of oxide and CO/CO2 production on carbon anode is the basis for metal production in a CaCl2 bath. By using an inert intermetallic anode, the CO2 evolution can be eliminated altogether with acceleration in the electro-reduction kinetics. At present the process suffers from slow reduction kinetics of TiO2 to Ti metal, which can be enhanced significantly by the incorporation of alkali species in the TiO2 pellet at the cathode and in the CaCl2 bath in the presence of an intermetallic inert anode. Nearly full metallization with greater than 99% of Ti metal containing 1500 ppm of oxygen is possible to achieve in less than 16 hours of electro-reduction. Analyses of phase composition and the microstructures morphology in fully metallized pellets revealed the presence of localized solidified Ti layer, indicating that fast reduction process also involved formation of liquid phase as middle stage reaction. In addition, in situ creation of porosity and maintain higher current level during electrolysis process were two key factors to fully reduction of TiO2.IntroductionDuring cathodic dissociation of TiO2 in a CaCl2 bath and anodic evolution of CO2 on a carbon anode, which is the basis for the FFC Cambridge process [1], the rate of metallization slows down due to the formation of CaTiO3 at the reaction interface. Calcium and alkaline earth perovskites are known for their poor electrical conductivity which adversely affects the overall electro-reduction. One of the ways to increase the porosity is via the addition of polyethylene precursors in the pellet or by directly starting from perovskite [2, 3]. The experimental evidences shown in the literature confirm although the speed of reaction increases, but a complete or near complete metallization is not possible by enhancing the in-situ porosity alone, as the insulating perovskite is very slow to decompose under the equilibrium that prevails in the cell. Plethoric evidences on carbon anode show with the current decrease gradually, and finally stabilize at a very low value between 0.2 and 0.4 A, which is a testimony of the presence of perovskite insulating barrier in the current path. Our aim in this paper is to demonstrate the mechanism of enhanced electro-reduction when alkali ions are present in the oxide pellet at cathode and in the bath. We also show for the first time the use of an intermetallic anode for Ti-metal production using the FFC Cambridge process."

Jan 1, 2009

By Hua-qing Li

Electromagnetic stirring process effectively improves the casting quality of metals. In this paper, the physical simulation experiment, in which the molten copper is displaced by mercury, was designed. The factory test parameters were determined according the simulated data. The flow behavior of the mercury to be stirred as well as the relations between the microstructure of plate blanks and the current parameters were analyzed. With an appropriate electromagnetic stirring, the inverse segregation of tin for C51900 alloy plant blank reduces from 15 % ~ 30 % to about 5 %, and the proportion of equiaxed grain rises to larger than 30%.

Jan 1, 2009

By Yuanbo Zhang, Qian Li, Helei Zhang, Heng Yu, Guanghui Li, Tao Jiang

"Large reserves of specularite iron ores have been found all over the world, which is characterized by high total iron grade, low gangues content, as well as low commercial price. However, it has not been widely used in sinter or pellet production due to its inferior sintering and roasting behaviors. It has shown that the proportion of specularite ores was increased as high as 40%~50% and good results was achieveed by using Composite Agglomeration Process (CAP), an innovative agglomeration process invented by Central South University. But the mineralization of specularite is still unknown during composite agglomeration processing. In this paper, the induration characteristic of specularite ore is studied by simulating CAP in laboratory, as well as microstructure analysis of CAP product. The results show that specularite pellet is mainly indurated through recrystallization of Fe2O3, calcium ferrite within high basicity sinters matrix interweaves with the recrystallized Fe2O3 on the surface of the pellet, which forms an integral microstructure, and ensures high strength of CAP product for ironmaking.IntroductionLarge reserves of specularite iron ores have been found all over the world, especially in Minas Gerais of Brazil, Xuanhua city and Anshan city of China, Elba island of Italy, St.Gotthard of Switzerland, Cumberland of Britannic, and so on. The specularite ores have a smooth surface, as well as a good crystallization and dense texture. When specularite is used to produce pellets, the specularite ore grains are difficult to adhere onto green ball due to its poor ballability. Moreover, specularite pellet requires high roasting temperature over 1300°C [1]. When specularite ore is used in sintering, the permeability of sintering bed gets bad and the quality of sinter is diminished. The practice in a few sintering plants finds that the output and strength of sinter decrease with the increase of specularite proportion, and the consumption of coke increases [2-4]. Therefore, the utilization of specularite has been limited. Composite Agglomeration Process (CAP) is an innovative technology invented by Central South University [5-7]. The process has the following merits: making reasonable utilization of different iron ore resources; improving the quality and output of sinters; manufacturing sinters with low basicity; significantly reducing energy consumption, etc[8-9]. It has been shown that large proportion specularite ores, as high as 40%~50% can be used well by CAP [10], but the mineralization of specularite pellet is still unknown during composite agglomeration processing. In this investigation, the induration characteristics of specularite ore pellets is studied by simulating CAP in laboratory, and the phase composition and microstructure of CAP product are also characterized by using microscope and Leica image analyzer (Germany, Leica DM RXp)."

Jan 1, 2011

By Yasuo Kudo, Wu, Hayato Sato, Hiroshi Nakazawa, Shouming

"In order to recover copper from a waste nickel condenser powder, bioleaching experiments were carried out using Thiobacillus ferrooxidans in a shaking flask. The content of nickel and copper in the waste nickel condenser powder in this study were 8.0% and 3.5%. X ray analysis showed the peak of barium titanate. In the preliminary study using metal nickel and copper powders , the dissolutions of nickel and especially copper were accelerated with the addition of ferric iron in the bioleaching of nickel and copper powders while not in the absence of ferric iron. Ferric iron oxidizes both metals, and Thiobacillusferrooxidans oxidizes ferrous iron resulting from the oxidation of metals, whereby the dissolutions of metals proceeds. The dissolution rates of nickel and copper increased with increase in the concentration of ferric iron in the bioleaching of the waste nickel condenser powder.1. IntroductionNickel condensers rejected from manufacturing plants are crushed and landfilled. Waste nickel condensers contain nickel and copper and could be considered as nickel and copper ores. Since the capacity of landfills is diminishing, it is required to recycle metals of waste nickel condensers in order to reduce the amount of wastes landfilled. Conventionally, metals in the waste were recovered by dry metallurgy after the incineration.Nickel has been refined by solvent extraction - electrowinning method (SX-EW method). Recently the amount of copper refined by SX-EW method has increased (Takahashi, et al. 1994). This method is cleaner and consumes less energy than conventional methods. Nickel dissolved well in acid solutions, but copper is not. If copper is leached efficiently from a waste nickel condenser powder, SX-EW method will be applied to recover copper from them"

Jan 1, 2000

By Gordon Irons, Kevin Graham, Krishnakumar Krishnapisharody

Ladle or secondary metallurgy in steelmaking is an essential process step for the production of high-quality steel. Professor David Robertson was a pioneer in the modeling of these processes, in particular gas-metal fluid dynamic interactions and the rates of slag-metal reactions. This is now a highly active area of research, and some of the recent developments in this area will be reviewed.

Jan 1, 2014

By Ali P. Gordon, James Williams

Joints gasketed with viscoelastic seals often receive an application of a secondary torque, i.e., retorque, in order to ensure joint tightness and proper sealing. The motivation of this study is to characterize and analytically model the load and deflection re-torque response of a single 25% glass-fiber reinforced polytetrafluorethylene (PTFE) gasket-bolted joint with serrated flange detail. The Burger-type viscoelastic modeling constants of the material are obtained through isolating the gasket from the bolt by performing a gasket creep test via a MTS electromechanical test frame. The re-load creep response is also investigated by re-loading the gasket after a period of initial creep to observe the response. The modeling constants obtained from the creep tests are used with a Burger-type viscoelastic model to predict the re-torque response of a single boltgasket test fixture in order to validate the ability of the model to simulate the re-torque response under various loading conditions and flange detail.

Jan 1, 2015

By S. K. Kawatra, T. C. Eisele

"Recent advances in microbiology have made the application of biotechnology to metallurgical processes possible. Hydrometallurgy stands to gain the cost from the use of microorganisms, as they are useful for both dissolution aids and for removing metals from solution. The development of genetic engineering techniques promises to greatly increase the importance of bioprocessing of metals and minerals by the year 2000.In this paper, the basic effects of microorganisms on metallurgical processes are reviewed, and the applications which are currently either in use or near being used are presented. Representative data collected at Michigan Technological University is also given.IntroductionMany hydrometallurgical operations exist which are thermodynamically possible, but which are industrially impractical due to slow kinetics, high reagent costs, or the need for a highly corrosive environment. However, recent discoveries in microbiology indicate that in many cases these difficulties can be reduced greatly by the action of bacteria and other microorganisms (1-8).A major advantage of using living organisms in hydrometallurgy is that once the culture is established the microorganisms produce their own reagents either from the material being processed or from low-cost nutrient supplements. They thus allow extremely complex chemical reactions to be carried out at reasonable cost. The major drawback of using microorganisms is their inability to tolerate extremely high temperatures, excessive concentrations of toxic metals, or very highly acidic, alkaline, or corrosive conditions. However, the complex reactions which bacteria make possible frequently eliminate the need for such extreme conditions. Also, in recent years a number of organisms have been isolated from such exotic environments as hot springs and deep-ocean vents which can tolerate temperatures higher than was previously thought possible for any organism, and can catalyze a number of metallurgically important reactions (8)."

Jan 1, 1988

By Lv Guozhi, Niu Liping, Liu Yan, Zhao Qiuyue, He Jicheng, Zhang Ting’an, Dou Zhihe

"This paper proposed a new method of Mg and Cl2 circulating for titanium sponge production by direct pyrolysis and thermal reduction process. Effects of pyrolysis temperature, pyrolysis time and partial pressure of oxygen on pyrolysis efficiency were researched, and the crystallite structural transformation of MgO productions at different pyrolysis temperature and time were analyzed by XRD. The experimental results indicates that the pyrolysis temperature and time effects the pyrolysis efficiency obviously, and the reasonable pyrolysis conditions by using MgCl2 in molten state are as follows: the pyrolysis temperature is 1100?, pyrolysis time is 60min and the partial pressure of oxygen is 100%, the pyrolysis efficiency get above 95% at this conditions. The dynamic analysis of molten magnesium chloride pyrolysis reaction shows that, as a chemical reaction process control, the response of the apparent activation energy Ea=70.4 kJ/mol.IntroductionTitanium is a young metal, it is applied in industrial until the Second World War. It is 160 years from the discovery of titanium to the industrial production of ductility titanium by magnesium reduction method in the United States in 1948. As a new kind of metal, titanium and titanium material are better than the traditional metal materials in mechanical properties, heat resistance and thermal conductivity. Titanium is a kind of landmark structure and function material, which is called “space metal”, “Marine metal”, “Intelligent metal” [1-3]. Although the study of new methods of titanium melting get more at present, Kroll method and Hunter method are really applied to industrial production methods for titanium smelting, and Hunter method is already discontinued because of costs at present. The core technology in Kroll method of sponge titanium production process can be ome down to two circulation, namely the cycle of magnesium and chlorine in preparation-process of titanium sponge. In the traditional Kroll method, the cycle is realized through magnesium chloride which is produced by the electrolytic magnesium reduction process in hot molten state. But because investment of equipment for electrolysis method is too high, this method has not been used by most titanium sponge production enterprise in China. At present most titanium sponge production enterprise in China produce titanium sponge by the outsourcing of titanium tetrachloride, but the main disadvantage of this method is that the by-product of magnesium chloride is difficult to deal with."

Jan 1, 2012

By Toshiaki Tsuru, Takeshi Ohgai, Hisaaki Fukushima, Shigeo Kobayashi, Tetsuya Akiyama

"Electrodeposition behavior of Zn-Cr alloys from the methanol baths was investigated. In the methanol baths of low Cr3+ concentration, Cr (III) compound was incorporated in the deposits and no lusfrous Zn-Cr alloys was deposited. However, Cr was existed as metallic state in the deposits obtained from the baths of higher Cr3+ concentration. With an increase in water content in the baths, the chemical state of Cr in the deposits changed from metallic to trivalent state. Under the condition that metallic Cr can be electrodeposited, Zn deposition was significantly polarized to the potential of Cr deposition.INTRODUCTIONAn attention has been paid to Zn-Cr alloy plated steel sheet because of its excellent properties for body panels of automobile and electrical appliances [1]-[4]. This plating process can be operated using the sulfate solutions containing Cr3+ ion [1] - [6].In decorative single Cr plating, on the other hand, many attempts have been made to electroplate Cr from trivalent electrolytes, which is motived by environmental deficiencies of the presently used hexavalent process [7]. [8]. However, it has been reported that in the aqueous solutions the behavior of the electroreduction of 0 3+ is atypical due to the complicated nature of the chemistry and electrochemistry of cr3+ species [9]-[11]. Even in Zn-Cr alloy plating, it is difficult to codeposit metallic Cr with Zn in simple sulfate electrolytes [l]-[4], [12]. Therefore, it can be expected that the electrodeposition behaviors of Zn-Cr alloys as well as Cr are significantly changed when the electrodeposition is conducted in non-aqueous plating solutions.In this study, the electrodeposition of Zn-Cr alloy was conducted from methanol solutions to clarify the electroreduction mechanism of Cr3·-Cr0 in the alloy deposition process."

Jan 1, 2000

By Bernd-Arno Behrens, Klaus-Georg Kosch

"In times of increasing energy costs automotive lightweight construction is gaining in importance. This paper deals with the production of hybrid steel-aluminum compounds by forging. The compound forging process is a promising method to successfully manufacture functional parts by applying resource-saving process steps. Nevertheless, challenges resulting from different material properties must be solved.The heating of hybrid material work pieces made of steel and aluminum is a great challenge. Steel is forged at a temperature of at least TSt =900 °C, while aluminum should not exceed a temperature of TA1= 500 °C. For achieving the required temperature gradient extensive experimental investigations have been carried out. Intermetallic phases form during the manufacturing process and can influence the bonding and the global part quality. In addition, methods for the characterization of the joining zone between the materials steel and aluminum are analyzed and the factors influencing the formation of intermetallic phases are determined experimentally.IntroductionIn times of increasing energy costs and stricter conditions relating to environmental protection, automotive lightweight construction is gaining in importance. The production of hybrid compounds by forging is a promising method to manufacture functional parts by applying resource-saving process steps. In compound forging a hybrid raw part consisting of a solid core, which is enclosed by a hollow casing, is joint in the forming process. This results in a graded material structure in the part in which the mechanical properties can be specifically adapted to the requirements. Compound forging is the form joining and/or firmly bonded joining of at least two different materials while plastic shape forming occurs (Figure 1)."

Jan 1, 2012

By V. Ramachandran

The Amarillo Copper Refinery, the newest and most modern copper refinery in the world, has been in operation for the last eleven years and has a rated capacity of 460,000 st/yr. The tankhouse - a structure that covers 500,000 ft2 under one roof - extends one-half mile in length and is a model of materials-handling efficiency. The use of recently developed and patented* reagent control technology, termed "Reatrol Process", has increased current efficiencies to an average of 98% and has considerably improved the physical and chemical quality of the cathode deposit. The present paper describes the current operations at the Amarillo Copper Plant with special emphasis on tankhouse operation.

Jan 1, 1987

A new technology for the treatment of copper nickel-containing concentrate after high-grade matte flotation to blister copper with the production of liquid silicate slags in a vertical autogenous unit with upper oxygen blow has been considered. The copper and nickel behavior in the process of sulphide copper concentrate interaction with silicate melt containing oxide copper has been studied. The general mechanisms of such interaction are found.

Jan 1, 2003

By Fumio Hashiuchi, Yushiro Hirai, Masatoshi Maeda, Toshihiro Nagata

"Increase in the copper smelting capacity at Saganoseki Smelter & Refinery was attained through various improvements in the PSconverters and the flash furnace. Two of the major innovations in the converting process were: a new operational technology which avoids increase in the copper content in the converter slag even when higher copper grade matte (65%) are treated in the slag making stage and a technology which shortens the operational interruption time which is caused by coolant charging. The latter was realized by introducing a new automated coolant charging system with which it was made possible to charge the coolant without stopping the blowing into the converter. These improvements brought about a remarkable increase in · the production capacity per converter and an annual production of 450,000 tons of copper without adding new furnaces was made possible. In addition, good results have been obtained of the tests with modified tuyeres to further increase the production.IntroductionIn a bid to renovate its Saganoseki Smelter & Refinery and to establish a leading production unit in terms of global competitiveness, Nippon Mining & Metals undertook major restructuring efforts since 1994. One of its themes was the shift from· a two-flash furnaces operation to a single-flash furnace operation. The shift was successfully completed in 1996 while maintaining the production at the same level (330,000 tons per annum of copper). Then, the productivity was enhanced to 450,000 mtpy without adding new furnaces through technological and operational improvements. It is now planned to increase the smelting capacity further to 470,000 mtpy this year.Some technological and operational improvements in the matte converting process and the new plan resulted from the tests with modified tuyeres are presented in this paper."

Jan 1, 2000