Foseco International Limited

Evan Thomas Jones

Robert Anthony Fishburn

John K Batham

Paul I Fontaine

Alan G Fox

A particulate flux composition suitable for desulphurizing and/or dephosphorizing molten ferrous metals and for use as a mould flux comprises prefused particles comprising calcium oxide and at least one other component, such as alumina, iron oxide, calcium fluoride, magnesium fluoride, sodium fluoride, silica, sodium oxide, zirconium oxide, titanium oxide or sodium borate, and in which each particle has a substantially vitreous amorphous structure. The composition is highly resistant to hydration and does not introduce hydrogen into the molten metal.

Calcium oxide based flux compositions

Treatment agents for steel suitable for desulphurizing molten steel comprise granules containing both magnesium oxide and/or carbonate and aluminium, the proportion of aluminium in the surface of the granules being substantially less than the overall proportion of aluminium in the granules. The granules are suitable for application into the molten steel via injection techniques.

Treatment agents for molten steel

Method of desulphurizing a ferrous melt comprises injecting into the melt lime-containing particles having smooth surfaces, a low tendency to absorb moisture and blocked pores formed by solidification of molten inorganic matter in the pores of the lime. Method of making a desulphurization agent for the desulphurizing method comprises calcining limestone with, for example, sodium carbonate, calcium fluoride or siliceous matter. Desulphurization agents per se are also described.

Desulphurization of ferrous melts

The invention provides a slag conditioner for use in electric arc steelmaking which comprises 30 to 80% by weight of alumina, 10 to 30% by weight of aluminium 5 to 40% by weight fluorspar and 0 to 20% by weight of alkali metal carbonate. The conditioner is added with lime to deoxidized steel suitably in an amount of from 5 to 15 Kg/tonne of steel to promote rapid reduction of the initial refining slag iron oxide content together with increased slag fluidity and a faster rate of lime dissolution to form a reactive slag.

Arc steelmaking

The invention is concerned with the desulphurizing of molten ferrous metal by the use of a lime-based flux composition. The composition comprises, by weight, at least 60% of lime and includes from 1 to 20% of sodium carbonate, from 5 to 30% of an alkali metal or alkaline earth metal fluoride, typically fluorspar, and from 5 to 20% of alumina. To desulphurize molten metal the flux is added to the molten metal in a vessel, typically by injecting the flux in particulate form into the molten metal.

Manufacture of steel

The invention is concerned with the desulphurizing of molten steel by the use of a lime-based flux. In addition to lime the flux includes sodium carbonate, an alkali metal or alkaline earth metal fluoride, typically fluorspar, alumina and a metallic reducing agent. In particular, the reducing agent is aluminium or an alloy thereof and is present in an amount of 2 to 15% by weight. To desulphurize molten metal the flux is added to the molten metal in a vessel, typically by injecting the flux in particulate form into the molten metal.

In steelmaking, the formation of a lime-based desulphurising slag is promoted by adding, with the lime, an additive including at least 20% by weight Al.sub.2 O.sub.3 and including one or more of oxide of iron, magnesium, manganese and titanium, and melting below 1600.degree.C.

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Birmingham, United Kingdom

Evan Thomas Jones