Desulphurization of ferrous materials using glass cullet

Abstract

The invention relates to a method for the preparation of a sodium-based reactive desulphurizing agent for use in molten ferrous materials. The source of sodium in the reactive desulphurizing agent is a glass cullet, a composition comprising of at least Na₂O and SiO₂. In a second embodiment of the invention, the glass cullet reactive desulphurizing agent also comprises of an alkali or an alkaline material or other materials, such as oxides of calcium, aluminum and magnesium. Preferred raw materials for the oxides of calcium, aluminum and magnesium are, respectively, lime, alumina and dolomite. The premixed solid reactive desulphurizing agent is brought in contact with the molten ferrous material, allowing the desulphurization or the double replacement of the iron sulphur to take place and produce a ferrous oxide. The sodium in the reactive desulphurizing agent is rendered resistant to combustion or evaporation on contact with the molten ferrous materials by the flux activity of the silica. A metallic solid, such as aluminum, is introduced into the molten ferrous material to complete the reduction of the ferrous oxide.

Description

FIELD OF THE INVENTION [0001] The present invention relates to (1) the use of glass cullet as the primary desulphurizing reactant in a reactive desulphurizing agent, (2) the option of including other desulphurizing reactants obtained from other reactive alkali oxides, alkaline oxides or other chemical compounds and metallic solids, (3) the application of a glass cullet based reactive desulphurizing agent to a molten ferrous material and (4) the deoxidation or reduction of the iron oxide in a molten ferrous material. BACKGROUND OF THE INVENTION [0002] Ample agreement exists on the growing need for low sulphur steels. In most types of steels, the presence of sulphur above 0.015% is undesirable. The increasing stringent requirement for better desulphurization of steel is attributed to the need for producing high strength low alloy steel and steels resistant to hydrogen induced cracking. In addition, even minute contents of sulphur has pernicious effects on the manufacturing and finishi...

AI Technical Summary

Benefits of technology

[0010] A method is disclosed for removing sulphur in molten ferrous materials using a sodium-based as a reactive desulphurizing agent. The preferred source for the sodium-based reactive desulphurizing agent is glass cullet. A lime, dolomite, an alumina or mixtures thereof, may optionally be added to enhance the replacement of the sulphur and control of the fluidity of the spent reactants in the molten ferrous materials.

Problems solved by technology

In most types of steels, the presence of sulphur above 0.015% is undesirable.

In addition, even minute contents of sulphur has pernicious effects on the manufacturing and finishing of steel products, such as brittle fractures in welding and fabrication, a tendency to separate along grain boundaries when stressed or deformed at temperatures near the melting point during the hot rolling phase in sheet steel processing, and even the influences on as-cast and the processing characteristics of the steel in terms of the workability of surface finish.

However, because of its high reactive property, metallic sodium is highly unstable at ambient temperatures and violently reactive at the temperatures of molten ferrous material and thus would vaporize explosively on contact with molten ferrous materials, hence metallic sodium, by itself, is ineffectual as a desulphurizer.