Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Reexamination Certificate
2000-10-12
2002-04-30
Kastler, Scott (Department: 1742)
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
C075S501000, C075S502000
Reexamination Certificate
active
06379424
ABSTRACT:
The present invention relates to an apparatus and a process for producing molten metal (which term includes metal alloys), in particular although by no means exclusively iron, from metalliferous feed material, such as ores, partially reduced ores and metal-containing waste streams, in a metallurgical vessel containing a molten bath.
The present invention relates particularly to a molten metal bath-based direct smelting apparatus and a process for producing molten metal from a metalliferous feed material.
A process that produces molten metal directly from ores (and partially reduced ores) is generally referred to as a “direct smelting process”.
One known direct smelting process, which is generally referred to as the Romelt process, is based on the use of a large volume, highly agitated slag bath as the medium for smelting top-charged metal oxides to metal and for post-combusting gaseous reaction products and transferring the heat as required to continue smelting metal oxides. The Romelt process includes injection of oxygen enriched air or oxygen into the slag via a lower row of tuyeres to provide slag agitation and injection of oxygen into the slag via an upper row of tuyeres to promote post-combustion. In the Romelt process the metal layer that forms below the slag is not an important reaction medium.
Another known group of direct smelting processes that are slag-based is generally described as “deep slag” processes. These processes, such as DIOS and AISI processes, are based on forming a deep layer of slag. As with the Romelt process, the metal layer below the slag layer is not an important reaction medium.
Another known direct smelting process which relies on a molten metal layer 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 comprises:
(a) forming a molten bath having a metal layer and a slag layer on the metal layer in a vessel;
(b) injecting into the bath:
(i) a metalliferous feed material, typically metal oxides; and
(ii) a solid carbonaceous material, typically coal, which acts as a reductant of the metal oxides and a source of energy; and
(c) smelting the metalliferous feed material to metal in the metal layer.
The HIsmelt process also comprises post-combusting reaction gases, such as CO and H
2
, 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 feed materials.
The HIsmelt process also comprises forming a transition zone above the nominal quiescent surface of the bath in which there are ascending and thereafter descending droplets or splashes or streams of molten metal and slag which provide an effective medium to transfer to the bath the thermal energy generated by post-combusting reaction gases above the bath.
A preferred form of the HIsmelt process is characterized by forming the transition zone by injecting carrier gas, metalliferous feed material, solid carbonaceous material and optionally fluxes into the bath through lances that extend downwardly and inwardly through side walls of the vessel so that the carrier gas and the solid material penetrate the metal layer and cause molten material to be projected from the bath.
This form of the HIsmelt process is an improvement over earlier forms of the process which form the transition zone by bottom injection of carrier gas and solid carbonaceous material through tuyeres into the bath which causes droplets, splashes and streams of molten material to be projected from the bath.
The applicant has carried out extensive pilot plant work on the above-described preferred form of the HIsmelt process in a pilot plant vessel having a hearth diameter of 2.74 m. The size of pilot plant vessel, whilst rated to produce 100,000 tonnes of molten metal per year, is smaller than that of a commercial size vessel. A commercial size vessel is one that is capable of producing at least 500,000 tonnes of molten metal per year. Typically, a commercial size vessel is one that is capable of producing 1-1.5 million tonnes of molten metal per year. Necessarily, such a commercial size vessel would have a hearth diameter that is larger than 2.74 m. During and subsequent to the pilot plant work the applicant has carried out development work on a vessel for a commercial operation. The present invention was made in the course of that development work.
According to the present invention there is provided a vessel which produces metal from a metalliferous feed material by a direct smelting process, which vessel contains a molten bath having a metal layer and a slag layer on the metal layer and has a gas continuous space above the slag layer, which vessel includes:
(a) a shell;
(b) a hearth formed of refractory material having a base and sides in contact with the molten bath.
(c) side walls which extend upwardly from the sides of the hearth and are in contact with the slag layer and the gas continuous space
(d) one or more than one lance/tuyere extending downwardly into the vessel and injecting an oxygen-containing gas into the vessel above the metal and slag layer;
(e) a plurality of pairs of lances/tuyeres extending downwardly and inwardly into the vessel and injecting feed material which includes metalliferous feed material and carbonaceous material with a carrier gas into the molten bath so as to penetrate the metal layer and generate a bath-derived gas flow which carries molten material upwardly from the metal layer and the slag layer as splashes, droplets and streams of molten material and forms a transition zone in the gas continuous space, the pairs of lances/tuyeres being spaced around the circumference of the vessel, one lance/tuyere of each pair injecting feed material, primarily metalliferous feed material, at a temperature of at least 200° C. (hereinafter referred to as the “hot” lance/tuyere), and the other lance/tuyere of each pair injecting feed material, primarily carbonaceous material, at a temperature less than 200° C. (hereinafter referred to as a “cold” lance/tuyere); and
(f) a means for tapping molten metal and slag from the vessel.
Preferably the vessel is a commercial size vessel that is capable of producing at least 500,000 tonnes of molten metal per year.
Preferably the hot lance/tuyere injects feed material at a temperature of at least 600° C.
The term “primarily” in the context of a nominated feed material is understood to mean that at least 50% by weight of the feed material injected through a given lance/tuyere is the nominated feed material.
Preferably the feed material is in a solid state. The feed material may be in liquid or gas state as well as solid state. By way of example, the carbonaceous material may be in solid, liquid or gas state.
Preferably the hot lance/tuyere injects no volatile carbonaceous material.
The hot lance/tuyere may inject non-volatile carbonaceous material, such as char.
Typically, the host lance/tuyere injects metalliferous feed material and non-volatile carbonaceous material at the temperature of at least 200° C.
The injection of feed material through the cold lance/tuyere is not confined to carbonaceous material and, by way of example, may include plant reverts.
Preferably the lances/tuyeres of any given pair of lances/tuyeres are positioned with respect to each other so that the lances/tuyeres inject feed material towards a point spaced from the pair of lances/tuyeres.
The term “smelting” is understood herein to mean thermal processing wherein chemical reactions that reduce metal oxides takes place to produce liquid metal.
The term “metal layer” is understood herein to mean that region of the bath that is predominantly metal. Specifically, the term covers a region or zone that includes a dispersion of molten slag in a metal continuous volume.
The term “slag layer” is understood herein to mean that region of the bath that is predominan
Kastler Scott
Merchants & Gould, P.C.
Technological Resources Pty. Ltd.
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