Title

REDUÇÃO DE PERDAS EM MISTURAS DE GRAUS DE AÇO EM DISTRIBUIDORES DE MÁQUINAS DE LINGOTAMENTO CONTÍNUO

MINIMIZATION OF HYBRID PRODUCTION DURING STEEL GRADE INTER-MIXING IN THE TUNDISH

Authorship

Heaslip, Lawrence (Larry); Dorricott, James (Jim); Richaud, Johan; Rogler, John; Alves, Wender Andrade

Heaslip, Lawrence (Larry)

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Dorricott, James (Jim)

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Richaud, Johan

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Rogler, John

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Alves, Wender Andrade

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DOI

10.5151/2594-5300-0039

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Abstract

O Lingotamento contínuo de misturas de grau de aço é o resultado de transição química de graus dentro de um mesmo seqüencial, podendo representar uma parcela significativa do custo operacional. Apesar disso, esta é uma prática comum que tem por finalidade a redução de tempo ocioso de máquinas de lingotamento contínuo e de consumo de distribuidores. O custo das transições pode ser severamente reduzido se a quantidade de aço de transição for reduzida. Neste artigo é apresentada a influência de projeto de distribuidor, práticas operacionais e utilização de software de predição e controle químico na diminuição de massa de aço de transição. Hybrid Steel Reduction and Tracking Software (HYTRK) foi desenvolvido para uso em tempo real na metalurgia secundária para ajuste químico e redução de perdas, além do uso no próprio lingotamento para apontamento e predição das transições químicas.

The continuous casting of steel semis, such as slabs or blooms, with hybrid chemistry as a result of steel grade intermixing in the tundish, can be a significant cost factor in continuous caster operations, particularly if tundish grade mixing occurs regularly. Grade mixing is often practiced to avoid lost production time and reduce tundish consumption by eliminating tail-outs or tundish flys when the production schedule includes a high proportion of short runs of the same grade. The cost of grade mixing in the tundish can be significantly reduced if the quantity of hybrid chemistry product (i.e. product that fits neither the outgoing nor the incoming chemical grade specifications) can be reduced. In this paper it is shown that tundish design, caster operations, and the use of chemical intermix prediction and control software can be highly beneficial in reducing the amount of hybrid steel produced during tundish grade mixing. Tundish design factors, including tundish flow control furniture, and caster operations, such as tundish level practice, are shown to have a significant influence in promoting a shorter transition. Hybrid steel reduction and tracking software (HYTRAK) is also shown to be of great assistance in improving steel yields during tundish grade mixing. HYTRAK has been developed for use in real-time at ladle metallurgy to adjust heat chemistries to reduce hybrid steel production and for use on the caster to predict and track the changing steel chemistry of the casting strand.

Keywords

Lingotamento contínuo; Análise de fluxo; Mistura de aços; Rendimento metálico.

Hybrid steel tracking; Grade transition; Flow analysis; Continuous casting.