Kosaka Smelter introduced an Outokumpu-type flash furnace in 1967. The Smelter had long treated “Black Ore” or concentrates separated from it as a metallurgical department belonging to Kosaka mine. It is distinctive feature of Kosaka Smelter that the copper smelter has a really close relationships to an adjacent lead smelter in handling intermediate to each other to recover the valuable metals from “Black Ore”. Since the second oil crisis in 1979 and the appreciation of yen in 1985, the domestic mine arround Kosaka Smelter were closed and it was difficult to open new mine.
Kosaka Smelter has been changed to a custom smelter and devoting to treat the complex sulfide copper concentrates in the world from this change. For the last decade, a progressive diversification of the smelter input has been taking place, impure and complex sulfide concentrate being introduced in increasing proportions compared with the period of “Black Ore” treatment. Kosaka Smelter is believed to be one of the most outstanding smelter, which contribute to the complex sulfide concentrates in the world, with our up-to-date metallurgical technology, this paper described about the experience of practical operation at Kosaka Smelter in the last decade.

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The only one copper smelting by green charged reverberatory furnaces in Japan has been operated since 1965 at Onahama Smelter.The severe conditions such as environmental regulation, oil crises and decreased production had been overcome each occation.
Majar improvements which were achieved in the past decade, were use of alternative fuel at reverberatory furnaces, copper concentrate injection at converters, manpower saving and energy saving at each process, etc.
And about 600, 000t of copper concentrate were smelted and 225, 000t of electlytic copper were refined in the recent operation at 1992.

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The Hitachi Smelter & Refinery changed its name to the Hitachi Refinery and started operation with establishing the Nippon Mining & Metals in November in 1992.
After the shut down of the Smelting Division in 1976, the Hitachi Refinery, mainly operating copper tank house and anode slime treatment section, established the development and production systems for new materials and valuable materials with joining various divisions of groups of our company.In the anode slime treatment section in the Saganoseki Smelter & Refinery was combined with the Hitachi Refinery in 1981.In result, the inventory of silver & gold and labor costs were reduced.
At the tank house in 1989, a pitch changeable hunger was developed and the pitch of anode to anode was reduced from 110 mm to 100mm, resulting in increasing in the monthly capacity of cathode from 10, 000t/M to 11, 000t/M and reducing the electrical power consumption.In September in 1988, the Sb-removing process (NCR-process) using chelating resin was installed.This process highly contributes the stability of tank house operation.
The reverberatory furnace, installed in 1978, for treating industrial waste is operating in good condition; furthermore a waste oil treatment plant was installed in April, 1993.Recycling Division is now planning to expand and is contributing to the maintenance of the ecological balance and environmental cleanliness of the earth.

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Tamano Smelter of Hibi Kyodo Smelting Co., Ltd.started its operation in January 1972, employing FSFE (Flash Smelting Furnace with Furnace Electrodes) for smelting and PRC (Periodic Reverse Current) for refining.
Its original production capacities were 101, 000 tonnes per year of anode copper and 84, 000 tonnes per year of electrolytic copper.
Tamano Smelter has steadily increased production capacity, improved productivity and reduced production cost.The production capacities of anode copper and electrolytic copper have been increased to 226, 300 and 161, 000 tonnes per year, respectively.
This paper describes the production capacity expansions, energy saving and the other technical improvements and developments for the last 10 years.

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The Naoshima Smelter and Refinery, which is located in the Seto Inland Sea, about 200 kilometers west of Osaka, has three major activities such as copper and lead smelting and refining, and also precious metals refining. As for the copper division, two old smelter lines, i.e. conventional reverberatory furnace line and small continuous line, were in operation during 80's. In November 1989, it was decided to replace the two old smelters with new larger continuous smelter to modernize and make more efficient the overall smelter operations. The construction work took one and half years to be completed and the operation of the new plant was started in May 1991. At the same time the existing two smelters were shutdown. Moreover the copper tankhouse was expanded by two blocks, 64 commercial cells, for the purpose to fill somewhat the gap of production capacity between smelter and refinery. By this expansion, the cathode production capacity was increased from former 13, 800 to 15, 500 mtpm including the slight increase of current density.This paper introduces the current operations of copper at Naoshima.

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The Sumitomo Toyo Smelter has been in operation since its commencement in 1971 with a pollution-free and clean smelter policy.
In recent ten years, copper production business has been suffering from the Japanese Yen having appreciated and the copper price repreciated, and when this was added to environmental pollution regulations having become progressively stricter, Toyo smelter has been obliged to make the further research and development efforts in order to survive in a copper production business, as follows.
1) Increasing the production rate with the same number of furnaces.
2) Achieving cost savings through a reduction of energy consumption, fuel conversion and personnel cuts.
3) Satisfactorily meeting the environmental protection regulations by introducing antipollution equipments and developing pollution prevention techniques.
These continued efforts make it possible to maintain and uphold the status of Toyo Smelter's position as one of the cleanest and most efficient operator in the world.

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Saganoseki Smelter & Refinery increased the annual production capacity from 240, 000 metric tons to 300, 000 metric tons in 1982, together with improvements of environmental protection and impurity removal. These made the Saganoseki smelter a pollutionless and the largest scale coastal smelter, both in name and reality. However, Saganoseki was forced to operate at low production rate for about six years since then because of the economic deterioration, facing a crisis of its existence. In 1989, Japanese economy turned to prosperity and the copper market recovered allowing Saganoseki to operate at its full capacity.In 1991, Saganoseki attained a reinforcement of its production capacity to 330, 000 metric tons per annum without the increase of the number of main smelting facilities. Technological and operational improvements made at Saganoseki for a last decade are introduced in this paper dividing into four areas of topics, that is, smelting, sulfuric acid production, electrolytic refining and utility supply.

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Hachinohe Smelting Company was established on February 1, 1967, as a joint toll smelter to take advantage of the Imperial Smelting Process.The smelter produces zinc and lead simultaneously and has been operating and performing excellently since its commencement.
In April 1988 the zinc production capacity of Imperial Smelting Furnace (ISF) was increased from 81, 000 to 101, 000 tonnes per year.The additional production in the ISF has been attributed to the utillization of the hot briquetting process adopted in 1987.Recently, many improvements and modifications have been made at Hachinohe Smelter, for example, the improvement of condensation efficiency based on the modification of the condenser design, the rotor profile etc., the reduction of energy consumption by the improvement of sinter/hot briquette/coke quality and introducing of the steam turbine driven blower for ISF etc.
According to these improvements and modifications, the furnace zinc production of Hachinohe Smelter was achieved 107, 482 tonnes in 1992 which was the best production record in the year among all ISP's in the world.
The further improvements of metallurgical performances, and the recovery of metals from ISF slag will be intended.

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Kosaka Smelter has long treated “Black Ore”, which contains many valuable metals such as silver, lead, zinc, bismuth and antimony except for copper.
The role of lead smelting and refining in Kosaka Smelter was to recover the valuable metals from “Black Ore” above-mentioned and to contribute to the stable operation of copper smelting section in Kosaka Smelter.
At the first of'80th, the smelter has treated a.lead sulfide concentrate by the electric furnace smelting with hydrometallurgical pretreatment technology.
However, the domestic mines arround the Kosaka Smelter were closed one after another since the oil crisis in 1979 and the appreciation of yen after the G5 in 1985.
As the result of these economical shock, the treatment of lead sulfide concentrate has not become economically profitable.
Since such economical change in the last decade, the role of lead smelting and refining at Kosaka Smelter should be devoted to support the copper smelting section.
That is, the policies of lead smelting section of Kosaka Smelter are;
1) to make the operation of copper smelting section stable by removing the impurities contained in the complex sulfide concentrates.
2) to recover the valuable metals in the dust produced by flash furnace.
According to this operating policy, Kosaka Smelter has established the technology of electric smelting process with hydrometallurgical dust treatment plant, and developed the profitable process.The paper described experience of practical operation for 12 years in Kosaka Smelter.

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Iijima Zinc Refinery was constructed in 1971 by Akita Zinc Co., Ltd. established as a joint venture of Dowa Mining Co. and five other zinc producing companies in Japan.
Started production in 1972 and doubled the production capacity of SHG zinc in 1974 from 6, 500 t/M to 13, 000 t/M.
Since started operation, many difficulties including not only the oil-crises of 1973 and 1978 but also the trend of drastic strong yen rate since 1985 were suffered from.
In order to overcome a rise in energy cost, Iijima Zinc Refinery has carried out various improvements for plant modernization and energy saving.
Extensive application of the computer control system to the plant operation is a typical example.
In 1984, the “Akita zinc company Total Information Control System” abbreviated to “ATICS” was developed for the pursuit of more effective operation in the plant and administration in the office.
From 1985 to 1987, digital control stations were installed to replace the analog instruments in the field control rooms.
The combination of the field side digital control stations and the host computer has brought not only the effective reduction in labor cost and energy cost, but also the significant improvements for stable plant operation.
Quality Control Circle Activity (QC Circle) has been introduced since 1980 and 55 Activity introduced in 1990, both of them have brought much fruit for every employee's motivation and morality.

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Akita Refinery of Mitsubishi Materials Corporation started its operation with capacity of 560 tons per month of electrolytic zinc.The plant had gradually expanded its capacity and reached 8, 100 tons per month in 1973.
Akita Refinery were adopted the conventional roasting, leaching, purification and electrolysis process. In 1965, Sulphate Roasting process for the acid leach residue treatment was developed and started commercial operation.
Mitsubishi Materials has its own Komata hydroelectric power station in Akita prefecture.Since 1973, electric power from Onuma geothermal power station has been supplied in addition to hydroelectric power. These power stations supplied about 40 percent of total electric power consumption at Akita refinery.
In 1980, started to treat the various zinc dross from the brass industry in addition to the zinc concentrate.
In 1989, started the commercial operation of the new zinc cell house which based on the new concept with capacity of 1, 100 tons per month of electrolytic zinc.

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The Hosokura Mine was closed in 1987, ending 1, 200 years'mining history.Simultaneously its zinc plant was shut down.But the operation of the lead plant and the acid plant are being carried on under the management of Hosokura Smelting & Refining Co., Ltd.Hosokura's operations are now producing monthly 1, 800 tonnes of electrolytic lead, 1, 300 tonnes of sulfuric acid, etc.
Lead smelting is carried out using an updraft sintering machine and a blast furnace, both with oxygen enrichment, followed by Betts electro-refining process using 180 tanks.The slimes from the tankhouse are smelted in the short rotary furnce, followed by several oxidation steps and valuable metals contained such as Sb, Bi, Au and Ag are recovered as antimony trioxide, electrolytic bismuth and crude silver.The copper bearing dross from the blast furnace and the tankhouse is treated to recover lead and copper matte in another short rotary furnace.The copper matte is sent to the Onahama smelter for copper recovery.
At the acid plant, ozone gas is used for bleaching black sulfuric acid and electric heaters are equipped to maintain the activation temperature of the converter when the sintering machine pauses.

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Annaka Refinery of Toho Zinc Company Limited, located seventy miles to northwest of Tokyo, has the annual production capacity of about 140, 000 tons of electrolytic zinc.
The plant, erected 1937 for the production of 5, 300 tons of zinc annually, had been enlarged up to the current production capacity until 1967.
For the 1970's decade, confirmted with tightening requirements for environmental control, rapidly-escalating energy prices and increasing labor costs, extensive improvements were carried out.
This paper presents these significant improvements and achieved results.

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In April, 1985, Nikko Zinc Co., Ltd.became independent from Nippon Mining Co., Ltd. as its wholly subsidiary company, and the operation of Mikkaichi Smelter and Tsuruga Plant was transferred to this company.
This paper describes the outline of our electrothermic zinc distillation process and the following improvements in the past ten years.
1) Reinforcement of the desulfurizing plants
2) Increase of the removal capacity of Cd
3) Reduction of the unit electric power consumption in the electrothermicd istillation furnaces
4) Increase of the production capacity of S.H.G. zinc in the refining process
5) Development of new products

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Kamioka Mining and Smelting Co., Ltd. became independent of Mitsui Mining and Smelting Co., Ltd. in 1986.
Kamioka's metallurgical operation consists of zinc electrolytic winning, lead smelting, and lead electrolytic refining, and the company's main products are electrolytic zinc, electrolytic lead, zinc alloy, silver, cadmium, bismuth, sulfuric acid, and liquid sulfuric anhydride.
Our metallurgical operation developed together with the mining operation at Kamioka mine, but imported ore consumption has been increasing recently with the decrease of proved ore reserve at the mine.
Our advantages are that we have both a zinc plant and a lead plant and that we receive the supply of about 70% of the necessary electric power from our own hydropower plants. To strengthen our competitive position by using these advantages, we are taking a great interest in recovery of gold, silver, platinum, palladium, and rhodium from recycled materials, and the zinc electrolysis plant was completely replaced with a new plant in March, 1993.

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Harima Works was established in July 1964 and its operation was commenced in May 1966 with a production capacity of 3, 000t/M of Zn and 1, 500t/M of Pb introducing the Imperial Smelting Process (ISP).
The plant consists of sinter, IS furnace, zinc refinery, lead refinery and cadmium refinery plant. SO₂ gas from sinter machine is sent to Sumitomo Seika Co., Ltd.which operates sulfuric acid plant.The production capacity has been increased by various improvements and developments. In 1990, the IS furnace was renewed and enlarged, SO2 gas treatment system was modified, and now production capacity is 7, 500t/M of Zn and 2, 500t/M of Pb.The pollution control system has been also improved intensively.
In order to make the works more competitive, indium and thallium recovery from raw material and scraps has been operated since 1987 and 1980 respectively.

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Lead smelter at Naoshima was previously by conducted by Mitsubishi Cominco Smelting Co., Ltd., a joint venture company between Mitsubishi Materials Corp. and Cominco Canada Ltd. At that time, the extremely clean lead concentrate from Cominco's Pine Point Mine was solely treated. Therefore pyrorefined lead with four nine grade was produced without any further processing like the electrolytic refining. However, due to depletion of the mine, Cominco withdrew from the joint venture in September 1991. The lead smelter was taken over by Mitsubishi and it started as a custom smelter to treat several foreign lead concentrates, some of them contain high levels of impurities. As the produced crude lead was required to be electrolytically refined to meet with the stringent quality demand, a lead refinery with a capacity of 40, 000 mtpy was newly constructed, and started its operation in March 1992. It was designed to be highly mechanized and has been equipped with large electrolytic cells.

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The lead bullion from Hachinohe Smelter as a major raw material and the one recovered from the secondary lead materials by smelting through a blast furnace at this Takehara Refinery are, after decopperizing and detinning at need, electro-refined together to produce electrolytic lead.
The major portion of electrolytic lead is used as material for producing lead chemicals such as white lead, red lead, litharge, etc., and the rest is for sale to the customers as lead metal.
Antimony is recovered as antimony trioxide by treating the lead slime obtained through electrolytic process and the residual lead is fed to the silver recovering process in the copper processing plant to recover rarious precious metals. As by-products, tin is also produced from this process and valuable metals are recovered as lead bullion from the residual lead carbonate processed through by solvent extraction.

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The Chigirishima Smelter of Toho Zinc Co., Ltd.is located on Chigirishima island of Hiroshima Prefecture.
This smelter is an custom lead smelter and its operation was started in 1951, at present, this smelter products 7, 200 tons per month of electrolytic lead.
This paper presents significant improvements and achieved results of late 10 years.

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Hikoshima Smelter, which is located at the southest end of Honshu, started its electrolytic zinc operation in 1970. Present zinc production is about 55, 000 tons per year, that corresponds with the Roasting plant capacity. Main products are zinc alloys for hot galvanizing and zinc anodes for electro plating. This paper presents features of the Hikoshima Smelter and improvements that have done in the two decades.

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In April 1976, lead blast furnace was shut down at Saganoseki. Since then, only electric furnaces have been operated to recover crude lead from lead sulfate residues by-produced at copper and zinc smelters of the company. The total smelting capacity is 500 metric tons per month. On the other hand, 3, 000 metric tons per month of electrolytic refining capacity has been maintained to also treat lead bullion from the zinc smelter and crude lead entrusted by other companies in order to reduce the total production cost. Therefore, monthly production of electrolytic lead has varied from the maximum 2, 700 metric tons to the recent 900 metric tons. Technical and operational details, including Indium recovery, are introduced in this paper.

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The precious metals plant at Naoshima Smelter has been in smooth operation since November 1989, which replaced an old plant at our Osaka Refinery.
In the new plant, the time required for the process steps between roasting of slimes and casting of silver anodes was shorten by one day, and various equipment and facilities for the processes such as silver electrolysis, selenium and etc.have been highly mechanized and automated.
The new plant is the most advanced one with the highest productivity and efficiency in Pan-Pacific area.

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Niihama Copper Refinery of Sumitomo Metal Mining Co., Ltd. has been producing mainly electrolytic copper and precious metals since 1919.
The production of gold has been quadrupled during the latest decade because of increasing copper concentrate smelting at Toyo smelter and starting treatment of high gold ores. The ores come from Sumitomo's Hishikari Gold Mines and contain about 80 grams gold per ton.
Copper anode slimes produced from Niihama Refinery and Toyo Refinery are decopperized with sulphuric acid, deselenized by roasting and smelted by use of an electric furnace to concentrate precious elements. Lead refinery slimes produced at Harima ISP Refining Works are also charged to the furnace.
The bunions from the electric furnace are treated and refined in a cupel after antimony and lead removal. The resulted crude silver is casted into silver anodes.
In order to cope with increasing slime production, a new method, chloridizing furnace for lead removal has been adopted and a new cupel has been introduced.
The treatment process for silver anode slimes has been improved to obtain up-grade quality of gold anodes. The productivity of gold electrolytic processes are advanced by use of the anodes.

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Mitsui Kushikino Mining Co., Ltd. has the only refinery in Japan which is capable of all slime cyanidation in the are treatment process. However, are treatment is no longer considered feasible, due to the rapid drop in the gold market, and its use is diminishing. Accordingly, operation at the refinery has undergone at change from are treatment to treatment of gold-and silver-containing scrap, semi-conductor scrap in particular.
The amount of gold-and silver-containing scrap handled at the refinery has doubled in the past decade. In contrast, the output of gold and silver has increased 1.5-fold, the amount of gold produced exceeding 70%. Such treatment has almost completely taken over are treatment.
The following discusses improvements made in treatment processes at the said refinery during the past decade, centering on the treatment of gold-and silver-scrap.

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Mochikoshi Smelter & Refinery started operations in 1939, and had been smelted the ores from three mines which were located in lzu peninsula, Seigoshi. Mochikoshi, and Yugashima. The ores were dissolved by sodium cyanide and refined by dry method. But in 1976 the great earthquake was happened and destroyed the reclaimed land of slags, so we stopped the cyanide process of extraction. On the other hand, since 1968, the electrolytic refining of gold and silver has been operated, and recovery of precious metals from urban mines started in 1971. The Smelter & Refinery has the capacity now to produce 80 kilograms of pure gold and 15 tonnes of pure silver per month.
Recovery and refining of secondary precious metals from secondary sources are have developed alongside the growth of the manifold uses of precious metals.
The materials of precious metals arise in most industries, such as photographic, chemical, electronic and electrical, jewellery trade and dentistry.
Photographic film and paper, and sludges which contained silver are burned into ashes in the incinerator which was constructed by “Cleen·Japan·Center”. Gold or silver plated frames are dissolved by sodium cyanide and gold and silver are recovered by reduction of zinc. Printing plate of computer, contained gold, are dissolved by aqua regia and reduced to gold by reducing agent. The ashes and the precipitate are melted with fluxes in the reverberatory furnace, and then refinied by cupellation. After electrowinning the fineness of gold and silver are 99, 99.

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Itomuka Refinery is located in a little hilly town, 700m above the sea in the northeast of Hokkaido.
The plant specializes in treating and recycling of mercury contained wastes with annual treating capacity of 10, 000 tons and 50 or 70 tons of mercury recovery and reproduction a year.
Its authorized facilities consist of two Herreshoff furnaces, two kilns, a rotary retort and an electric screwfurnace, each performing respective roles according to the kinds and properties of in-coming wastes.

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Tin smelting at Ikuno Plant started its operation in 1913 with reverberatory furnace smelting process. In 1950, the company replaced the reverberatory furnace with an electric furnace to improve operation efficiency and recovery. In 1987, Akenobe mine was shut down. Because the production of tin concentrates was stopped, raw materials of tin decreased to half. In 1991, the tin refining plant with new technology started operation at Ikuno Plant, while the tin refining plant at Naoshima was shut down.
At present, various tin bearing scraps are roasted, smelted and refined to produce about 97% crude tin. It is cast to anode and electrorefined with stainless cathode to 99.995+% electrolytic tin. Part of this electrolytic tin is reelectrorefined to 99.999+% high purity tin.
Annual production of crude tin metal is 720 metric tons, electrolytic tin is 660 metric tons and high purity tin is 360kg.

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Sumitomo Metal Mining Co., Ltd.(SMM) is the only producer of nickel and cobalt metal in Japan. Niihama Nickel Refinery in Besshi-Niihama District Division has been producing 22, 000 t/y of electrolytic nickel since 1970 from imported matte by nickel matte electrorefining process. Furthermore, Niihama Nickel Refinery supplies wide variety of nickel and cobalt chemicals as well as the metal.
Although the matte electrorefining is an established process and the productivity has been greatly improved in the last 20 years, SMM has intensively studied the chloride process for the nickel production. Concerned with development of the chloride technology, cobalt refining process involving solvent extractron and electrowinning from chloride solution has been practiced since 1975 and chlorine leach of anode slime was established in 1986. Based on these technology, the matte chlorine leach electrowinning (MCLE) process has been developed as an alternation to the matte electrorefining. The MCLE process offers good performance and excellent quality of the product. SMM constructed a facility for the MCLE process and the process has been in practice since 1992. The production of electrolytic nickel by the matte electrorefining process will by completely replaced by the MCLE process in the middle of 1993.

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Hyuga Smelting Co., Ltd. established by Sumitomo Metal Mining Co., Ltd. started production of ferronickel by Sintering-Electric Furnace Process in September; 1956, which is now owned by Sumitomo Metal Mining Co., Ltd.(60%), Nippon Steel Corporation (25%) and Mitsui & Co., Ltd.(15%).
In accordance with the rapid increase of the market demands, the company made a steady growth, expanding the production capacity from 30 to 200 tons of nickel per month. Because the further expansion required greater productivity and broader acres, the new plant was built at present site in the coastal industrial quarter adopting Rotary Kiln-Electric Furnace Process in 1968.
Since the improvement of the process, the development of new products and the energy curtailment of the whole plant have been achieved, Hyuga Smelter has become one of the most advanced coastal ferro-nickel smelters, boasting of most modern facilities and incompetitive technical knowledge.Production capacity is 1, 500 tons of nickel per month.

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The Oheyama plant of Nippon Yakin Kogyo Co., Ltd. was built here at Miyazu city in 1942, for treatment of low grade nickel oxide are (0.4-0.7% Ni) from nearby Oheyama mine by Krupp-Renn process. but at the end of war in 1945, the nickel smelting operation was stopped.
In 1950, the Kawasaki plant of Nippon Yakin Kogyo Co., Ltd. succeeded in producing stainless steel for the first time in Japan by oxygen top blowing in an arc-furnace, paving the way to mass production of stainless steel. This achievement quickly increased the demand for nickel, an important raw material of stainless steel, making the Oheyama plant resume its operation in 1952 by switching to higher grade nickel oxide ores imported from New Caledonia. Thus Nippon Yakin Kogyo Co., Ltd. established a vertically-integrated production process from Ni smelting to finished stainless steel products for the first time in Japan.
Since then the process of the Oheyama plant has been greatly modified and developed to establish “Nippon Yakin Oheyama Process”, the only method in the world that uses a rotary kiln for smelting nickel oxide ores.
The nickel ores are first ground by both dry and wet methods and blended well with anthracite and limestone, to be formed into briquets. They are first dried and preheated efficiently in a grate directly connected with a rotary kiln and then charged into the kiln, where all the metallurgical reactions such as dehydration, reduction, slag-formation and refining by excess air near discharge end, occur to form ferro-nickel nodules (0.3-20mm).
The Oheyama Process is considered a very useful method to obtain nickel material for stainless steel production, because its low energy cost as well as individuality of its product, easy to handle and almost free of impurities, help significantly reduce the cost of stainless steel production.
The Oheyama plant is now producing 1, 150t of Ni as ferro-nickel a month, and besides, 35, 000t of byproduct, “NAS Sand” a month from slag, which is mainly used as public works materials such as asphalt aggregate, concrete aggregate and so on.
Situated near Amano-hashidate, one of Japan's Three Famous Views, the Oheyama plant pays full attention to protecting the surrounding environment and to existing in harmony with nature.

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Takehara Plant of MMS is located in the city center of Takehara, near the National Park of Seto Inland Sea. At present, 40 different products are manufactured at our plant, including non-ferrous metals, various battery materials and chemical products.
Commercial production of Electrolysis Manganese Dioxide (EMD), begun in 1949, was small about 5 ton/month, and the plant was gradually expanded so that it had a monthly capacity of 2, 100 tons in 1982.
Our EMD is specifically used for ZnC1₂, Alkaline and Lithium batteries, therefore EMD's high quality is very important. In this paper, the outline of our process and improvement in our plants and quality are described.

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Chuo Denki Kogyo Co., Ltd. was established for producing low carbon ferromanganese in February 1934. The electrolytic manganese is produced at Taguchi Plant of Myokokogen in Niigata since 1940.
Capacity of the plant is 1, 800 t/y, but in recent years, unfortunately we have been forced to reduce the production rate, and now we are making efforts to lower the operation cost and save the energy through improvements.

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Awamura Metal Industry Co., Ltd. is well-known as the only company which produces Ferrotungsten in Japan. Besides Ferrotungsten, the company also produces Ferrovanadium, Ferromolybdenum, and Ferroboron etc. A total output amounts to about 2, 200 tons/year in recent years. The amount of Ferrotungsten produced in 1992 is 71 tons, this figure being one fourteenth of that in 1970.
Our smelting method for Ferrotungsten consists of two steps of reduction and oxidation processes, and this method can produce a very pure and uniform Ferrotungsten of a low segregation.
The flow sheet of our method, the typical composition of raw materials, the outline of our facilities and an example of our smelting results are shown. Typical analytical data for Ferrotungsten are as follows: W 77.69%, C 0.24%, Si 0.07%, Mn 0.02%, P 0.02%, S 0.01%, Sn 0.01%, Cu 0.02%, As 0.01%, Sb 0.01% Bi 0.01%, Mo 1.99%.

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Daiki Aluminum Industry Co., Ltd. founded in 1922 has supplied secondary aluminum alloy, mainly ingots for the casting and the die-casting according to the market's requirements involving the quality and the price of the products. Thus DIK has become the biggest company in the industry of recycling aluminum in the world through the contribution as a precursor.
At March 1992, DIK capitalized 5, 262 million yen had 300 employees and the annual outlet was 185, 400 tons for the secondary aluminum alloys which were produced by following four factories, Kameyama work, Shinsiro work, Yuki work and Shirakawa work.
This paper describes the existing state of the industry of recycling aluminum through DIK's operations and facilities, and some consideration on the outlooks for the future in the industry.

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Onahama Refinary of Toho Zinc Co., Ltd. employs two processes. One is roastering and sulfuric acidproducing process and the other is the Electrothermic process for producing marketable zinc oxide from Steelmaking Dust. The roaster, fluosolid reactor, treats 500 tons of Zn concentrate per day. The sulfuric acid plant has the double contact reactor.
Zinc oxide plant treats 30, 000 tons of Steelmaking Dust and is producing 16, 000 tons of zinc oxide, that is applied to cure accelerater activater for rubber, per year by American Process.

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Sotetsu Metal Co., Ltd. and Nisso Metallochemical Co., Ltd. started operation of Waelz plant for treatment of steel making dust in 1975. At present Sotetsu Metal Co., Ltd. treat 50, 000 tons of dust and recovery 17, 000 tons of crude zinc oxide annually. Nisso Metallochemical Co., Ltd. product high grade zinc oxide of 12, 000 tons and lead cake of 150 tons for smelting from crude zinc oxide.

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Sumitomo Shisaka Works has been treating EAF dust to recover zinc and lead by Waelz kiln process since its commencement in 1977. Since the commencement of operation, many technical improvements have been successfully carried out to increase the production capacity.The EAF dust charge to the Waelz kiln was increased from 35, 000 t/y (1977) to 73, 000 t/y (1991) with decreasing the number of workers.And moreover the new Waelz kiln has started the operation in July of 1992. Currently, the treating capacity of EAF dust in Shisaka Works is 120, 000 t/y with two Waelz kilns and the production capacity of zinc oxide is 40, 000 t/y. This paper will describe the above mentioned progress of operation at the Shisaka Works.

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MF is a half shaft blast furnace which has been developed at Mitsui Miike Smelter in the 1960's to treat vertical retort residue. The MF has also been tested for treatment of various recycling materials and wastes. Now various secondaries and wastes (EAF dust, zinc leaching residue, Cu-Ag sludge, etc.) are mainly treated. Powder materials are briquetted with reductant before being fed to the furnace. Products are crude zinc oxide, matte, non-hazardous slag and steam. Zinc and lead are recovered in oxide dust, and copper and silver are recovered in matte. The MF can be widely applied to many kinds of materials which contain such non-ferrous metal-valuables. In addition, the improvement in operation and technology has effectively made the unit capacity much larger. The MF now has many advantages for these treatment processes.

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Main products of Okayama Works are metal particle for magnetic recording media, iron oxide for hard ferrite application and sulfuric acid, which hold large share of each market, because of those good quality and large quantities.
Now many researchers and engineers, which is one-third of personnel of Okayama Works, have been devoting to develop new products for customers needs of the times.

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Due to the decrease of production of domestic iron pyrite concentrates, at present in Japan, Tobata Plant of Kowa Seiko Co., Ltd. is the only plant where sulphuric acid is produced from the iron pyrites.
By using the production facilities and incinerator exclusively designed for industrial waste, with the technology developed through the treatment of iron pyrites, various industrial wastes from iron/stell, chemical and other companies are treated and utilized as a raw material, fuel, etc. without disturbing the production
The total amount of the utilization of waste resouces at Tobata Plant is more than 210, 000t/y in 1991.

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Tomakomai Chemical Co., Ltd. has been established in 1971 as a sulfuric acid plant using pyrite which came from local metal mines. We have been produced a sulfuric acid and recovered some valuable metals in pyrite, such as Au, Ag, Cu, Pb and Zn. Pyrite cinder after recovered valuable metals were sent to iron making works for iron resourse.
For economical reasons, we changed sulfur source of pyrite to elemental sulfur and also reduced plant capacity in 1984. Subsequently, we challenged to new business. One is a industrial wastes management and another is a recovery of precious metals of Au, Ag and Cu from computer scraps. We recovered Au in the scraps 30kg/month.

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Since 1978, the spent hydrodesulfurizing catalysts come out from oil refineries have been processed at Ako Plant of Taiyo Koko Co., Ltd.
Our company presently produces various intermediates of the molybdenum and vanadium; ferro-alloys, chemical pure grade oxides, and ammonium salts, etc. Raw materials for these products are vanadium pentoxide and crude molybdenum trioxide, which mostly are imported from foreign countries but partly recovered from spent catalysts.
The recycling plant has been operating smoothly, and the amount of MoO₃ and V₂O₅ recovered from spent catalysts in 1991 were 690 tons, and 855 tons, respectively.

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Recycling useful metals is important to save decreasing resources and avoid environmental pollution. Presently, the percentage of recycling within the copper fabricating process is 44% in Japan. At Asio, equipment including the converter furnace (in which matte was refined) have been modified. With our technology and experience from producing blister and sulfuric acid, we currently smelt copper scrap, copper alloy scrap, and sludge of industrial waste, to produce gold, silver, and copper. However, since Asio has only one furnace, it has brought about some managerial difficulties.

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High purity metallic arsenic is produced through a process consisting of the chlorination of arsenious acid (As₂O₃), distillation and then hydrogen reduction.We combine these methods in order to produce 6N-7N5 metallic arsenic.
The purity is confirmed by analytical methods such as Emission Spectrographic, SSMS and GDMS.
High purity metallic arsenic is used for gallium arsenide (III-V compounds) and arsenic selenide (chalcogenide glass). Gallium arsenide-based devices are developed and manufactured for communications and computing machines. Chaicogenide glass is used in the photoconductor such as a copy machine.
High purity metallic arsenic is used for gallium arsenide (III-V compounds) and arsenic selenide (chalcogenide glass). Gallium arsenide-based devices are developed and manufactured for communications and computing machines.Chaicogenide glass is used in the photoconductor such as a copy machine.
Investigations on the properties of arsenic compounds such as arsine, arsenious acid and arsenic chloride have made it possible to prepare a high purity arsenic in safety.

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The tungsten refining plant in Toshiba Yokohama Metal & Components Works is our creative and original plant, which is composed of a fully automatic continuous refining process and rationalized furnaces for reduction. Our plant is made from our original empirical knowledge, added up while long manufacturing history. We have been providing our high quality material, which is manufactured by our plant, for all around the world. Recently we also began to make ultra high purified tungsten and molybdenum, used for semi-conducter.

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JNM was established in 1963, as a joint venture between Mitsubishi Materials and Awamura Mining. Over the last 30 years, JNM has made significant development in product techniques and production facilities for its range of Tungsten and Molybdenum.
Tungsten metal and carbide powders production in JNM has increased from 70 and 50 tonnes per month in 1981 to 220 and 200 tonnes in 1992, respectively by installing large fully automatic reduction furnaces designed and built in-house, and various types of carburizing furnaces for special use.
Our other products of Tungsten and Molybdenum and their main use are following. Trioxides for pigments, catalysts, electronics components. Ammonium parasalts and metasalt for catalysts. Hetero polic acid and their salts for catalysts. High purity products for electronics components. Borides and Silicides for advanced cermics. Carbide solid solution powders for hard metal. “Hardlett” powders for hard facing.

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Toho Titanium Co., Ltd.was established in 1953 and started producing titanium sponge at Chigasaki City in 1954 with a production capacity of 240 tons per year.At present, its production capacity is 10, 800 tons per year.Toho's titanium sponge is produced by the modified Kroll Process.
In 1960, a consumable electrode vacuum arc remelting furnace was installed.At present, the production capacity of titanium ingot is 7, 800 tons per year.
In 1962, Toho started producing ferrotitanium mother alloy by a high frequency induction furnace. At present, its capacity is 4, 200 tons per year.
In addition to these titanium metals, Toho produces titanium trichioride catalyst for polypropylene production and high purity titanium oxide for the electroceramics industry, etc.
Toho's production facilities have been essentially designed and operated on the basis to meet the requirements of the severe quality control, to reduce the energy consumption, to improve the productivity and etc.
The development and improvement of production of the titanium metals during recent about 10 years were reviewed in this paper.

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Sumitomo Sitix Corporation, former Osaka Titanium, started its Ti sponge production back in 1952, and the company has increased its production capacity along with increase in demand to 15, 000 tons/year, the largest in the world in 1993 except the CIS.
Sumitomo Sitix' process consists of the chlorination of TiO₂ to produce TiCl₄, its distillation, the reduction of TiCl₄ with Mg to produce Ti sponge, separating byproduced MgCl₂ from it (the Kroll Process), and the electrolysis of MgCl₂, thereby recycling Mg and Cl₂.
This process consumes a great deal of power and its productivity is not high enough because of a batch process. Thus, even now, effort continues specially in the electrolysis of MgCl₂ and in the production of Ti sponge though high-efficiency multipolar cell and the large batch combined process were developed.
This process consumes a great deal of power and its productivity is not high enough because of a batch process. Thus, even now, effort continues specially in the electrolysis of MgCl₂ and in the production of Ti sponge though high-efficiency multipolar cell and the large batch combined process were developed.

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Power Reactor and Nuclear Fuel Development Corporation (PNC) has developed the unique technique named PNC process which is one of the methods to refine and convert the uranium from uranium ore as one of the activity of PNC.
Basic development of PNC process was carried out at the test plant at Ningyo Toge Works from 1964 to 1982 and was obtained successful results.
As next step of application of PNC process, a pilot plant scale facility has been designed to obtain the pilot plant operation data for a design of commercial plant data and supply the uranium hexafluoride, as a material of uranium enrichment, to the uranium enrichment plant.
The refining and conversion facility houses a refining and conversion pilot plant as well as a conversion test facility.Their construction was completed in October 1981 and they went into operation from March 1982.
The refining and conversion pilot plant has since been in operation for six years and had obtained invaluable knowledge from the industrial point of view and it had enabled us to further improved on the PNC process.
We are planning new research and development of refining and conversion technology.

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