Midrex process

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Production préréduits (DRI et HBI) par procédés Midrex HYL Charbon.svg
Midrex / Corex steel mill in South Africa ( Saldanha Steel )

The Midrex process is a direct reduction process in steel production. With an annual production of 56.5 million t, the process accounted for 64.8% of the global production of directly reduced iron in 2017.

history

The Midrex process was developed by the US conglomerate Midland-Ross and in 1975 by MIDREX Corp. patent pending in the USA. Since 1983 the MIDREX Corp. a subsidiary of Kobe Steel . In Germany, the MIDREX Corp. granted the patent in 1984. A Midrex system was built in Hamburg in the early 1970s - today the system belongs to ArcelorMittal Hamburg. There are 78 Midrex shaft furnaces in 21 countries worldwide (as of mid-2015). The most important production countries are India (17 Mt), Iran (15 Mt) and Saudi Arabia (6.5 Mt).

Process description

In the Midrex process, iron ore is reduced in a shaft furnace using the countercurrent principle with a hydrogen-rich gas. This is obtained beforehand in a reformer by splitting natural gas.

The product of the Midrex process is sponge iron , in contrast to the liquid pig iron that is obtained in the Corex and Finex processes or in the classic blast furnace .

Advantages and disadvantages compared to other methods

  • Higher output than a blast furnace
  • Low specific energy consumption compared to the blast furnace
  • Low production volumes (well suited for small plants)
  • No coal or coke required, instead using natural gas as a reducing agent
  • The profitability depends heavily on the price of natural gas.
  • As a product, sponge iron is relatively pure -> good secondary metallurgical processing is possible
  • Sponge iron oxidizes in moist air and can self-ignite -> briquetting or passivation with a carbon layer necessary.
  • There is no slag
  • Ore must be lumpy, the fine ore must be pelleted.

Individual evidence

  1. ↑ https://www.midrex.com/assets/user/news/MidrexStatsBook2017.5_.24_.18_.pdf
  2. ↑ a b Mister Midrex is coming . In: Der Spiegel . No. 3 , 1976 ( online ).
  3. ↑ a b Brigitte Horn-Helf : Condensation as a terminological principle in Russian , Gunter Narr Verlag, Tübingen, 1997, ISBN 3-8233-5348-9 limited preview in the Google book search
  4. ↑ https://www.pressebox.de/pressemitteilung/arcelormittal-germany-holding/ArcelorMittal-beauftragt-Midrex-mit-der-Planung-einer-Demonstrationsanlage-fuer-die-Wasserstoff-Stahlproduktion-in-Hamburg/boxid/973085
  5. ↑ 2014 World Direct Reduction Statistics
  6. ↑ Midrex process description  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (English)@1@ 2Template: Dead Link / midrex2010.edreamz.com  
  7. ↑ Georg Küffner: The blast furnace is far from burned out. In: FAZ.net . June 16, 2005, accessed December 17, 2014 .

Patents

  • Patent US4042226 : Method and apparatus for producing metallic iron pellets. Applied on May 19, 1975 , published August 16, 1977 , applicant: Midrex Corporation, inventor: Donald Beggs. ‌
  • Patent DE2622349 : Process for the direct reduction of iron ores. ‌