Title

CONTINUOUS FEEDING OF SHREDDED SCRAP USING ''CLOSED DOOR PROCESS''

CONTINUOUS FEEDING OF SHREDDED SCRAP USING ''CLOSED DOOR PROCESS''

Authorship

M, Jorge Uyén

DOI

10.5151/2594-5300-0015

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Abstract

The paper is based on the experience developed on a 43.5 t AC-EAF with a 45 MVA transformer, equipped with Supersonic oxygen lances. The “Closed Door Process” works with 60-65% DRI or HBI continuous feeding, with a high foamy slag (1.5 – 2m) which means no limitations in the power usage. It is possible to use more than 1.1 MVA/t in flat bath with high feeding rate of DRI (40 – 50 kg/min – MW) without significant damage to the furnace panels or refractory lining. It is also possible to feed shredded scrap continuously under the same conditions as DRI or HBI ( Maximum power usage under flat bath conditions). Energy stored in foamy slag will be available to preheat cold shredded scrap when it passes through it, exchanging heat, maximizing material flow/min and minimizing “iceberg” formation. As a result, tap to tap decreases substantially under 40 minutes and electrode consumption goes around 1,2 kg/t. The process allows removing the slag with FeO content between 4 - 10%, so the metallic yield has been increased.

 

The paper is based on the experience developed on a 43.5 t AC-EAF with a 45 MVA transformer, equipped with Supersonic oxygen lances. The “Closed Door Process” works with 60-65% DRI or HBI continuous feeding, with a high foamy slag (1.5 – 2m) which means no limitations in the power usage. It is possible to use more than 1.1 MVA/t in flat bath with high feeding rate of DRI (40 – 50 kg/min – MW) without significant damage to the furnace panels or refractory lining. It is also possible to feed shredded scrap continuously under the same conditions as DRI or HBI ( Maximum power usage under flat bath conditions). Energy stored in foamy slag will be available to preheat cold shredded scrap when it passes through it, exchanging heat, maximizing material flow/min and minimizing “iceberg” formation. As a result, tap to tap decreases substantially under 40 minutes and electrode consumption goes around 1,2 kg/t. The process allows removing the slag with FeO content between 4 - 10%, so the metallic yield has been increased.

Keywords

Shredded scrap; Foamy slag.

Shredded scrap; Foamy slag.