A known direct smelting process, which relies principally on a molten bath as a reaction medium, and is generally referred to as the HIsmelt process, is described in International application PCT/AU96/00197 (WO 96/31627) in the name of the applicant.
The HIsmelt process as described in the International application in the context of producing molten iron includes:
(a) forming a bath of molten iron and slag in a vessel;
(b) injecting into the bath:                (i) a metalliferous material, typically iron oxides; and        (ii) a solid carbonaceous material, typically coal, which acts as a reductant of the iron oxides and a source of energy; and        
(c) smelting metalliferous material to iron in the molten bath.
The term “smelting” is herein understood to mean thermal processing wherein chemical reactions that reduce metal oxides take place to produce molten metal.
The HIsmelt process also includes post-combusting reaction gases, such as CO and H2 released from the bath, in the space above the bath with oxygen-containing gas and transferring the heat generated by the post-combustion to the bath to contribute to the thermal energy required to smelt the metalliferous materials.
The HIsmelt process also includes forming a transition zone above the nominal quiescent surface of the bath in which there is a favourable mass of ascending and thereafter descending droplets or splashes or streams of molten metal and/or slag which provide an effective medium to transfer to the bath the thermal energy generated by post-combusting reaction gases above the bath.
In the HIsmelt process the metalliferous material and solid carbonaceous material is injected into the molten bath through a number of lances/tuyeres which are inclined to the vertical so as to extend downwardly and inwardly through the side wall of the smelting vessel and into a lower region of the vessel so as to deliver at least part of the solids material into the metal layer in the bottom of the vessel. To promote the post-combustion of reaction gases in the upper part of the vessel, a blast of hot air, which may be oxygen enriched, is injected into an upper region of the vessel through a downwardly extending hot air injection lance. Off gases resulting from the post-combustion of reaction gases in the vessel are taken away from the upper part of the vessel through an off gas duct. The vessel includes refractory-lined water cooled panels in the side wall and the roof of the vessel, and water is circulated continuously through the panels in a continuous circuit.
The HIsmelt process enables large quantities of molten iron to be produced by direct smelting of metalliferous material. To enable such levels of production, large quantities of both metalliferous material and carbonaceous material must be supplied to the vessel.
One example of the construction of a solids injection lance for use in a direct smelting vessel can be found in U.S. Pat. No. 6,398,842 (assigned to the present applicant). This form of lance can be used to inject solid particulate material, such as metalliferous material or carbonaceous material, into the direct smelting vessel. In that construction, the solid particulate material is passed through a central core tube which is fitted closely within an outer annular cooling jacket. A forced internal cooling water system is provided within the outer annular cooling jacket to allow the lance to operate successfully when exposed to the high temperatures encountered within a direct smelting vessel, which can be in excess of 1400° C.
Metalliferous material and carbonaceous material can be particularly abrasive. When the direct smelting vessel is used to produce molten iron, typically the metalliferous material comprises iron ore fines. It is desirable that the components of the direct smelting plant can withstand exposure to these abrasive materials over a smelting campaign, which can be 12 months or longer.
The present invention provides an effective and reliable solids injection lance for the injection of metalliferous material and/or carbonaceous material into a direct smelting vessel.