METAL MINING TECHNOLOGY in JAPAN 8 Contents
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METAL MINING TECHNOLOGY IN JAPAN 8 Contents 1. Foreword 1 2. Brief history of fl ash furnace 1 3. Résumé of fl ash furnace 2 4. Technological features of fl ash furnace 6 5. Worldwide diffusion of fl ash furnace 6 6. Improvement of fl ash furnace operation in Japan 8 6.1 Kosaka Smelter of Dowa Mining Co., Ltd. 9 6.2 Saganoseki Smelter of Nippon Mining Co., Ltd. 11 6.3 Toyo Smelter of Sumitomo Metal Mine Co., Ltd. 13 6.4 Tamano Smelter of Hibi-Kyodo Smelting Co., Ltd. 15 6.5 Utilization of oxygen 17 6.6 Environmental countermeasures 19 7. References 21 1. Foreword The Ministry of International Trade and Industry (MITI), of the Government of Japan, has decided to create Mining Expert Training materials for the technical cooperation program of fi scal year 1991. MITI has assigned this project to the Metal Mining Agency of Japan (MMAJ). This text, together with pictures (video tape and slides), was planned by the MMAJ, and produced by the Japan Mining Industry Association in collaboration with the copper-producing fi rms in Japan. Without the permission of the JOGMEC, any copying or use other than for the purpose of Mining Expert Training is strictly prohibited. 2. Brief history of fl ash furnace 3. Résumé of fl ash furnace Turning heat of oxidation of sulphides to full The main metallurgical process for copper smelting account, the fl ash furnace requires almost none or is shown in Fig.1. Reaction formulas for each the far lesser amount of extrinsic fuels, compared process can be written as follows; with blast furnace, reverberatory furnace or electric furnace. The fl ash furnace process is classifi ed into [matte smelting process] two types by the structure and the sort of gas applied; Outokumpu fl ash smelting process and INCO oxygen 2CuFes2 → Cu2S + FeS + FeS2 fl ash smelting process. Nowadays, the Outokumpu FeS2 + O2 → FeS ＋ SO2 fl ash smelting process stays in the mainstream of 2FeS + 3O2 → 2FeO + 2SO2 fl ash smelting process that has a dominace among 2FeO + SiO2 → 2FeO・SiO2 copper smelting processes worldwide. The fi rst fl ash furnace was built at Harjavalta Smelter of [converting process] Outokumpu Oy, Finland, in 1949. [slagging stage] In Japan, the fi rst fl ash furnace for copper smelting was installed at Ashio Smelter of Furukawa Co., in 2FeS ＋ 3O2 → 2FeO ＋２SO2 April 1956, introducing the Outokumpu's technology. xFeO ＋ ySiO2 → xFeO・ySiO2 This furnace was the second to the Harjavalta in the world. Hitherto, many innovations were made in [blister making stage] the fl ash furnace process, and as a consequence of which, the fl ash furnaces were further introduced Cu2S + O2 → Cu2O + SO2 into such smelters as Kosaka, Saganoseki, Toyo and Cu2S ＋ 2Cu2O → 6Cu + SO2 Tamano. Today, the fl ash furnace produces about seventy percent of copper in Japan. Worldwide, [electrorefi ning] twenty three copper smelting fl ash furnaces are in operation at twenty two smelters. [anode reaction] Cu → Cu2+ + 2e- [cathode reaction] Cu2+ +2e- → Cu 1 Fig.1. Main processes for extracting copper from sulphide ores. 2 A fl ash furnace process is one of the matte smelting air, or a preheated oxygen-enriched blast. On the other processes which convert sulphide copper to matte. hand, in the case of an INCO type fl ash furnace, Notwithstanding its short application concentrate is blown in horizontally at both ends of history, the fl ash furnace has become a mainstay of furnace using pure oxygen instead of air. Off-gas is matte smelting due to its superior characteristics. discharged from the central duct. Fig.2 and Fig.3 show outlines of two fl ash furnace Furthermore, MI furnace (Fig.4) and Noranda types schematically. Regarding an Outokumpu furnace have come on the scene as a furnace of type fl ash furnace, desiccated copper concentrate is high productivity and a modern smelting process injected at the top of reaction shaft with a preheated suited for the acid production due to its high SO2 concentration of off-gas. Fig.2 Cutaway view of Outokumpu preheated air fl ash ash smeltingsmelting furnacefurnace Fig.3 Cutaway view of INCO oxygen fl ash smelting furnace 3 Fig.4 Mitsubishi continuous copper smelting 4. Technological features of fl ash furnace 5. Worldwide diffusion of the fl ash furnace process In contrast with the iron metallurgy, the oxidation of sulphide minerals proceeds as an exothermic Since the fi rst fl ash furnace was installed at reaction. The heat thus generated within a furnace Harjavalta Smelter of Finland in 1949, thirty fi ve is utilized to some extent even in the case of blast Outokumpu type fl ash furnaces have been built furnaces. The fl ash furnace makes use of the heat of worldwide before now. Except for nickel or pyrite reaction to the utmost, and utilizes it to melt matte processing furnaces and the ones ceased from and slag. In order to achieve this, the Outokumpu operation, twenty three fl ash furnaces are in operation type fl ash furnace applies a preheated air, or a at the twenty two copper smelters (Saganoseki preheated oxygen-enriched air, and the INCO type Smelter has two fl ash furnaces). Tab.1 and Fig.5 uses pure oxygen as an oxidant. As a consequence, show whereabouts of these copper smelting fl ash the emission of combution gas is suppressed due to furnaces in operation. the decrease of extrinsic fuels, and the amounts of heat and dust accompanied to off-gas are diminished due to the decrease of nitrogen intake. Besides, the effi ciency of sulfuric acid production is raised 6. Improvements of fl ash furnace as a result of elevated levels of sulphur dioxide operation in Japan concentration of the off-gas, thus achieving the highest levels of recovery and fi xing of sulphur. Furukawa Co., Ltd. introduced to Ashio Mine the The fl ash furnace, however, has such a drawback as technology of the fl ash furnace which had come a diffi culty with lowering the copper grade of slag, into fi rst operation at Finland in 1949 and were in which necessitates the reprocessing of slag by slag its infancy technically then, and commenced its cleaning furnace, or the application of a fl ash furnace operation in 1955. Hitherto, Furukawa Co., Ltd. fi tted with söderberg type electrodes, that is "a fl ash has improved a drying process of concentrates, the furnace with furnace electrodes" to lower the copper structure of furnace, the cooling system of furnace, content of slag. the structure of concentrate burner and the slag cleaning furnace, and proved that the fl ash furnace processing were optimal to the copper smelting in future. 4 Tab.1 List of fl ash furnaces in operation for copper smelting worldwide Key Name, location Company Capacity Start-up (T/D) 1. Harjavalta, Finland Outokumpu Oy 1,440 1949 2. Baia Mare, Romania Comb. Chimico Metalurg. 1956 3. Kosaka, Japan Dowa Mining Co.Ltd. 1,200 1967 4. Saganoseki, Japan Nippon Mining Co.Ltd. 1,800 1970 5. Toyo, Japan Sumitomo Metal Mine Co.Ltd. 1,600 1971 6. Ghatsila, India Hinustan Copper Ltd. 1971 7. Tamano, Japan Hibi Kyodo Smelting 1,900 1972 8. Hamburg, Germany Norddeutsche Affi nerie 1,900 1972 9. Samsun, Turkey Blach Sea Copper Works 800 1973 10. Saganoseki, Japan Nippon Mining Co.Ltd. 1,800 1973 11. Khetri, India Hinustan Copper Ltd. 1974 12. Huelva, Spain Rio Tinto Minera 1,300 1975 13. Playas, USA Phelps Dodge Corp. 2,200 1976 14. Glogow, Poland K.G-H, Miedzi 1,900 1978 15. Onsan, South Korea Korea Mining & Smelting 1,000 1979 16. Norilsk, CIS Norilskii G-M. Kombinat 1981 17. Camacari, Brazil Caraiba Metals S.A. 1982 18. Isabel, Philippines Pasar 1,800 1983 19. Guixi, China Jianxi Copper Corp. 1,250 1985 20. El Tajo, Mexico Mexicana de Cobre S.A. 2,500 1986 21. Chuquicamata, Chile Codelco-Chile 2,062 1988 22. San Manuel, USA Magma Copper Co. 2,700 1988 23. Olympic Dam, Aus. Roxby Mgt Services 336 1988 Fig.5 Location of Outokumpu type fl ash ash furnacesfurnaces forfor coppercopper smelting.smelting. Key numbers refer to data in Table 1. 5 The then copper smelters in Japan were applying copper concentrates. These elements are enriched blast furnaces to copper matte smelting, but in metallurgical dusts to multiply their amounts. converted to the fl ash furnace to boost the At the commencement of operation, the whole dust copper production against the surging demand, from the fl ash furnace had been circulated to the in collaboration with Furukawa, Co., Ltd. On the fl ash furnace. In 1967, however, the dust was shifted occasion of its introduction, each fi rm made efforts to the treatment in a rotary furnace to separate into to create a characteristic fl ash furnace by adjoining crude lead and copper matte, this being treated in an original technology of its own, and rationalized a converter, for the circulation to dust to the fl ash its operation by applying the fuel conversion to cope furnace created dust troubles in the waste heat boiler. with the "energy crisis" emerged afterwards. The But the volume of copper matte increased due to the outlines of each improvement are given as follows. high copper content of fl ash furnace dust, to raise the loads in the pertinent converters. Then in 1975, a new plant for hydrometallurgical processing of dust 6.1 Kosaka Mine of Dowa Mining Co., Ltd. was installed. This plant was to treat the converter dust and the other precipitates from sulfuric acid The northern district of Akita Prefecture bears plant as well as the dust from the fl ash furnace, and the most prominent black ore deposits in Japan, to separat them into copper sulphide, lead sulphate and the copper concentrates extracted from black and zinc hydroxide to facilitate the recovery of each ores contain the greater amount of impurities such metal.