Title

Heating of FeNi Alloy in Ladle Furnace by electrical energy + chemical energy

Heating of FeNi Alloy in Ladle Furnace by electrical energy + chemical energy

Authorship

P., FERNANDO HERNÁNDEZ; U., HECTOR BELLO; C., CLIMACO CARABALLO; C., JORGE DÍAZ

P., FERNANDO HERNÁNDEZ

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U., HECTOR BELLO

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C., CLIMACO CARABALLO

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C., JORGE DÍAZ

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DOI

10.5151/2594-5300-31Aciaria-321-332

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Abstract

At Cerro Matoso S.A., ferronickel (Ni 45% and S 0.40%), is tapped from the reduction electric arc furnace at 1440 ± 10 °C. A process of secondary refining for achieving the chemical specification and the temperature for casting granules (1630 ± 10 °C), is needed. The crude FeNi is tapped into a 55 tons ladle. A refining process by ladle furnace, is required with three phases. Heating, desulphurisation and adjustment of the final chemical composition. Before desulphurisation phase, FeNi is heated until 1610 ± 10 °C, with an electrical furnace (6 MVA). The best efficiency by furnace was 3.5°C/min, but this efficiency was not sufficient to standardize the refining cycle in less than 3 hours. To reduce the heating time, FeNi was submitted to a pirometallurgical process with aluminothermia (Al+O₂) as a source of energy to raise the temperature. After July 1998, we decided at the same time to raise temperature by electric arc and aluminothermia in order to minimize the heating time in this phase. This practical work shows the advantages when we use simultaneously "electrical energy + chemical energy" in order to reduce the cycle time of refining FeNi alloy, to achieve a heating rate greater than 11 °C/min.

At Cerro Matoso S.A., ferronickel (Ni 45% and S 0.40%), is tapped from the reduction electric arc furnace at 1440 ± 10 °C. A process of secondary refining for achieving the chemical specification and the temperature for casting granules (1630 ± 10 °C), is needed. The crude FeNi is tapped into a 55 tons ladle. A refining process by ladle furnace, is required with three phases. Heating, desulphurisation and adjustment of the final chemical composition. Before desulphurisation phase, FeNi is heated until 1610 ± 10 °C, with an electrical furnace (6 MVA). The best efficiency by furnace was 3.5°C/min, but this efficiency was not sufficient to standardize the refining cycle in less than 3 hours. To reduce the heating time, FeNi was submitted to a pirometallurgical process with aluminothermia (Al+O₂) as a source of energy to raise the temperature. After July 1998, we decided at the same time to raise temperature by electric arc and aluminothermia in order to minimize the heating time in this phase. This practical work shows the advantages when we use simultaneously "electrical energy + chemical energy" in order to reduce the cycle time of refining FeNi alloy, to achieve a heating rate greater than 11 °C/min.

Keywords

Ferroniquel alloy, Ladle furnace Process, Alloy

Ferroniquel alloy, Ladle furnace Process, Alloy