Study on the Briquetting of the Siderite- Based Direct Reduced Iron and Factor Affecting its Briquettes' Quality

Aris Hadyo Wicaksono

Research output: ThesisMaster's Thesis

Abstract

Most direct reduced iron (DRI) in the world is produced from hematite or magnetite ore. Siderite is rarely used as main raw material for ironmaking and steelmaking industries. However, as one of the biggest producer of iron ore concentrate (IOC) from siderite, VA Erzberg GmbH focuses to conduct some researches to produce DRI from new emerging process named Hydrogen Based Fine-Ore Reduction (HYFOR). Unlike conventional direct reduction process (DRP), HYFOR generates DRI in smaller size, which is below 6.3 mm. In this study, it is found that almost 53.5% of the siderite-based DRI product from HYFOR is in the size below 0.5 mm. Considering that the fine size of DRI is quite susceptible to undergo re-oxidation due to its high porosity and is not suitable for direct charging to electric arc furnace (EAF) or direct shipment to foreign steel industries, briquetting process, either cold or hot briquetting, of siderite-based DRI will be exercised. Chemical characterization shows that the sample of siderite-based DRI (HYFOR, <7500C) used in this study contains low metallic iron content (19.54 wt%). It is found that upgrading metallic iron of the siderite-based DRI is applicable by reducing the feed size from -6.3 into 100% below 1 mm and separating it using magnetic separation before the briquetting is performed. The study also shows that direct use of the feed without magnetic separation with size -6.3 and -1 mm (HYFOR feed) into briquetting process is also possible at the room temperature (cold briquetting). Without the addition of water and binder, the cold briquetting already achieves the apparent density required by the MO maritime Safety Committee, International Maritime Solid Bulk Cargoes (IMSBC) which is 2.5 gr/cm3 by using 105-107 MPa as the briquetting pressure. Beside the apparent density, its porosity volume fraction also decreases by 42%. However, in order to achieve better compressive strength, direct use of HYFOR feed or the upgraded HYFOR is not sufficient. Specific amount of binder and water shall be used to improve the mechanical properties in the cold briquetting step. In general, the briquette formed by the upgraded HYFOR (high metallic iron) with binder and water has better strength compared to its counterpart that is made of HYFOR feed. Particle size distribution also has effect to the briquette¿s strength and compressibility. HYFOR material with higher feed size (-6.3) produces lower strength briquette than the HYFOR feed -1 mm although it has a good compressibility. Another factor is compaction pressure. The higher the pressure, the better compressive strength of the briquette. In terms of hot briquetting, the experimental work shows that the usage of high temperature during compaction can increase the strength and compressibility although the preliminary results obtained in this study do not fulfil the expectation. Further improvements in the test setup are necessary.
Translated title of the contributionStudie über die Brikettierung von direkt reduziertem Eisenerz auf Sideritbasis und Faktoren, die die Qualität seiner Briketts beeinflussen
Original languageEnglish
Awarding Institution
  • Montanuniversität
Supervisors/Advisors
  • Böhm, Andreas, Supervisor (internal)
Award date28 Jun 2024
Publication statusPublished - 2024

Bibliographical note

embargoed until 31-05-2029

Keywords

  • Direct Reduced Iron (DRI)
  • siderite-based DRI
  • briquetting
  • porosity
  • compressibility
  • compressive strength

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