最終更新日時： 2019/01/09 10:05:32
Zinc Ingot (99.995% min.)from EAF dust by Selective Chlorination Process
We, Kinotech Corporation at Tokyo Japan, has discovered and developed the new purifying process of Zinc contained in EAF dust as a raw materials ( “KINOTECH PROCESS”)under co-works with The University of Tokyo at subsidy from New Energy and Industrial Technology Department Organization , Japan (NEDO). Now, we are looking for a partner who will develop this process for commercial plant. The PROCESS will use EAF dust as a raw materials. EAF dust is industrial waste stipulated under Basel Treaty and approx. 8,000,000 M/T per year around the world (Approx. 17 kg per 1000kg of Iron Scrap will be generated as EAF dust containing Zn of 20～35％) have been generated . EAF dust are processed to crude ZnCl2 and residues (Clinker) by Selective Chlorination. After Purification process, ZnCl2 will be separated to Zn and Cl2 by Electrolysis and Cl2 will return to Selective Chlorination Process. Clinker will be processed to Carburizer and reused at EAF companies. The Process is perfect Recycling not discharge a second waste to outside the facility.
- New Styled Zinc Smelter using EAF dust as a raw materials
In a conventional technique (the Waelz Kiln process), zinc content in EAF dust discharged during steel production is recovered as crude zinc oxide that is an intermediate raw material, whereas the residue (mainly iron oxide) being secondary industrial waste is landfilled. Our technique (the Kinotech process) can achieve perfect recycling (a recycling method free from secondary industrial waste) in which the zinc content is recovered as zinc ingot and the residue is also recovered as a carburizing material. This technique enables an electric furnace manufacturer to effectively process EAF dust that has been conventionally disposed with disposal costs. Zinc ingot is generally produced from zinc concentrates as a raw material in a zinc smelter, and the profitable plant scale is 100,000 to 200,000 tons per year and the construction cost reaches about 1 billion US dollars (US$). Further, the zinc concentrates accounts for 70% of the total manufacturing cost. Meanwhile, the Kinotech process uses EAF dust as a raw material, and therefore the material cost is "zero" and the plant scale will be 10,000 to 20,000 tons per year, which is sufficiently profitable. The Kinotech process is a chlorination process and therefore does not use any carbon material unlike the Waelz Kiln process, which contributes to CO2 reduction. Furthermore, molten salt electrolysis of zinc chloride directly electrolyzes zinc chloride (i.e., decomposes zinc chloride into zinc and chlorine and returns chlorine to a chlorination process), and therefore power consumption is smaller than that in aqueous electrolysis with zinc dilute sulfuric acid in the conventional method, thus enabling to have a compact plant. In addition, zinc is recovered as molten zinc from an electrolytic cell by being sucked with a vacuum pump. Therefore, the Kinotech process does not require "stripping process" and "re-melting process" that are conventionally needed, and is effective in manufacture of tailor-zinc for galvanize-steel plating. There is high expectancy of demands for the Kinotech process in countries that generate EAF dust, countries with no zinc smelter, and countries with construction demands of new zinc smelters. Also, the Kinotech process enables construction of distributed-type zinc smelters that utilize EAF dust as a raw material, of which transboundary movement is prohibited by the Basel Convention.
Molten salt electrolysis of zinc chloride in the Kinotech process is an invention made by joint development (2008 to 2011) of a new manufacturing method of polysilicon for solar cells (a zinc reduction method) with a major chemical manufacturer. Our technique of selectively chloridating EAF dust has been developed through joint development with Dr. Hiroyuki MATSUURA (Associate Professor, Department of Materials Engineering, School of Engineering, The University of Tokyo), which received subsidies twice from New Energy and Industrial Technology Development Organization (NEDO) in 2014 and 2016. Through the two major developments, we have established a manufacturing method of zinc ingot with a purity of 99.995% or more from EAF dust. Our next steps are large bench tests, pilot plant construction, and running tests in an operating company. The expected cost of development is about 2 billion yen and the expected development period is 3 to 4 years. Regarding the total necessary funds of commercial plant construction, its construction cost will be US$95 million for the scale of zinc production of 10,000 tons per year, US$159 million for the scale of 20,000 tons per year, and US$198 million for the scale of 30,000 tons per year. The IRR (Internal Return Rate), which is an index of economic evaluation, will be 10%, 14%, and 17% for the respective scales of zinc production. Potential buyers of our technology are in China, Taiwan, Europe, and United States, as well as Southeast Asian countries that do not have zinc smelters. Currently, the world consumption and production of zinc ingot is 14 million tons (corresponds to about US$350billion) and the generation amount of EAF dust is about 8 million tons (the amount of zinc is 2 million tons, corresponding to US$50 billion ), both increasing year by year. In the future, dust disposal in the conventional method (the Waelz Kiln process) will become difficult from the economic and environmental viewpoints, because of increase of zinc consumption in association with increase of the world’s population, closure of existing zinc mines, cost increase and restriction in the development of new zinc mines, rise in the zinc price, various problems related to dust disposal in the conventional method (landfilling, CO2 generation by the use of coke, and a low actual yield of zinc), as well as increase of the amount of iron scraps. Accordingly, we believe that, as a solution for the problems described above, construction of commercial plants employing the Kinotech process will be considered in the near future.
1) Regarding the details of technology , please refer " Publishment at The Mining and Minerals Processing Institute of Japan ,March 2018" 2) Regarding econimic evaluation , please see the attachment (EAF dust :35,000 ton , 70,000ton ,105,000ton)
- Kanto Head Office, SMRJ