Recycling of By‐Product Pellets as Burden in the Blast Furnace Process: A Lab and Pilot Scale Investigation

• Published in: steel research international
• Main Authors: Robinson, Ryan, Sundqvist Ökvist, Lena
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2004
• Subjects: Luleå
• Online Access: http://dx.doi.org/10.1002/srin.200405934; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fsrin.200405934; https://onlinelibrary.wiley.com/doi/pdf/10.1002/srin.200405934

Cold bonded by‐product briquettes have been recycled in the blast furnace at SSAB Tunnplåt in Luleå since 1993. Recently, much effort has been made to increase the recycling of by‐products. One such project deals with the development of a cold bonded by‐product pellet (CBP) agglomerated from very fine dusts. The pellets used in these tests are produced from a blend containing BF flue dust, filter dust, briquette fines and BOF coarse dust as well as cement binder. The pellets were tested in the laboratory by reduction tests, softening and melting tests, thermo gravimetric analysis, differential thermo analysis, and mass spectrometry measurements. The test results indicate that the CBPs can disintegrate during reduction in the BF shaft, are self‐reducing to a high extent and, as a supplement to the normal ferrous burden, they show quite good softening and melting properties. A pilot scale test in LKAB's experimental blast furnace was performed. CBPs were charged with rates of 150 kg/tHM, 299 kg/tHM and 344 kg/tHM respectively during test periods 1, 2 and 3. The blast furnace operation was very stable during test period 1 with 150 kg CBP/tHM, but the burden descent and gas distribution were disturbed during the periods with greater CBP burden content. The rate of reducing agents was significantly decreased and slag amount was increased when CBPs were charged.