EUROPEAN STEEL TECHNOLOGY AND APPLICATION DAYS 2017 - ESTAD 2017

The aim of the BOF (Basic Oxigen Furnace) process is to convert carbon-rich liquid hot metal from the blast furnace to low-carbon steel, which may be refined in the secondary steelmaking shop. Fluxes are needed in this process to remove impurities from the liquid hot metal and form an appropriate slag which could be easily separated from the steel. These fluxes could require low melting points to reduce the energy consumption, to fluidize the slag at lower temperatures and remove impurities from steel. It is necessary for the fluxes to have an appropriate granulometric distribution, good tumbler index to reduce fines generation which could obstruct the blowing plugs, so a homogenous flux is desired. A homogeneous chemical composition that allows basicity control (Si and MgO levels) and high absorption characteristics to combine the flux with P, S, Si, etc. are needed. PASEK Dunite is an ultramaphic rock exploited in the north of Spain with a basic chemical classification, being olivine and serpentine its principal minerals. It is formed by orthopyroxene, clinopyroxene and olivine in variable proportions. An important parameter in this kind of process is the ratio pig iron/scrap (Hot Metal Ratio, HMR). This parameter shows the thermal balance of the process and measures the consumption of pig iron per tonne of liquid steel. With high hot metal ratio, more phosphorus amount is necessary to remove in comparison with a low hot metal ratio, so it is necessary to increase the slag amount maintaining the basicity and the MgO level. In this case is recommended to use Dunite for increase the slag quantity and the dephosphorization percentages. PASEK Dunite is a good flux for BOF process and its use is recommended when the BOF produces low silicon content slag and high levels of slag are needed, maintaining its basicity and MgO content, as well as if the process works with a high hot metal ratio (high phosphorus amount to remove). Keywords: Fluxes; Dunite; Hot Metal Ratio; BOF; Magnesium Silicate