MXPA00012893A - A direct smelting process - Google Patents

Abstract

A direct smelting process for producing metals from a metalliferous feed material is disclosed. The process includes forming a molten bath having a metal layer (15) and a slag layer (16) on the metal layer in a metallurgical vessel, injecting metalliferous feed material and solid carbonaceous material into the metal layer via a plurality of lances/tuyeres (11), and smelting metalliferous material to metal in the metal layer. The process also includes causing molten material to be projected as splashes, droplets, and streams into a top space above a nominal quiescent surface of the molten bath to form a transition zone (23). The process also includes injecting an oxygen-containing gas into the vessel via one or more than one lance/tuyere (13) to post-combust reaction gases released from the molten bath, whereby the ascending and thereafter descending splashes, droplets and streams of molten material in the transition zone facilitate heat transfer to the molten bath, and whereby the transition zone minimises heat loss from the vessel via the side walls in contact with the transition zone. The process is characterised by controlling the process by maintaining a high slag inventory.

Description

DIRECT FUSION PROCESS BACKGROUND OF THE INVENTION The present invention is concerned with a process for producing molten metal (such term includes metal alloys), particularly though by no means exclusively iron, from metalliferous feedstock, such as ores, partially reduced ores and waste streams containing metal, in a metallurgical vessel containing a molten bath. The present invention is concerned in particular with a direct melt-based process of molten metal to produce molten metal from a metalliferous feedstock. The most widely used process for producing molten metal is based on the use of a blast furnace or furnace. The solid material is loaded to the top of the furnace and the molten iron is derived from the soul. The solid material includes iron ore (in the form of sinter, lump or pellet), coke and alkaline fluxes and forms a permeable charge that moves downward. Preheated air, which can be enriched with oxygen, is injected to the bottom of the kiln and moves up through the permeable bed and generates carbon monoxide and heat by coke combustion. The result of these reactions is to produce molten iron and slag. Ref: 125480 A process that produces iron by reducing iron ore at a temperature lower than the melting point of the iron produced is generally classified as a "direct reduction process" and the product is referred to as DRI. The FIOR process (Reduction of Fluid Iron Ore) is an example of a direct reduction process. The process reduces iron ore fines as the fines are fed by gravity through each reactor in a series of fluid bed reactors. The fines are reduced by compressed reducing gas that enters the bottom of the reactor lower in the series and flows countercurrent to the downward movement of the fines. Other direct reduction processes include processes based on a blast furnace with a mobile axis, processes based on a blast furnace with a static axis, processes based on a rotating hearth, processes based on a rotary kiln and processes based on a retort. The COREX process produces cast iron directly from coal without the requirement of coke from the melting furnace or blast furnace. The process includes a 2-stage operation in which: (a) DRI is produced in a blast furnace or furnace from a permeable bed of ore (or ore) iron (in the form of lump or pellet), coal and alkaline fluxes and (b) then the DRI is charged without cooling to an attached fuser gasifier. The partial combustion of the coal in the fluidized bed of the melter gasifier produces reducing gas for the blast furnace. Another known group of processes for producing molten iron is based on cyclone converters in which the iron ore is melted by combustion of oxygen and reducing gas in an upper melting cyclone and is melted in a lower melter containing a water bath. molten iron. The lower melter generates the reducing gas for the upper melting cyclone. A process that produces molten metal directly from ore is generally referred to as a "direct melting process". A known group of direct fusion processes is based on the use of electric furnaces as the main source of energy for fusion reactions. Another direct melting process, which is referred to in general as the Romelt process, is based on the use of a large volume of highly agitated slag bath as the means for melting metal oxides charged to the metal to the top and for the post combustion of gaseous reaction products and transfer heat as required to continue to fuse metal oxides. The Romelt process includes injection of air enriched with oxygen or oxygen to the slag via a lower row of nozzles to provide agitation of the slag and injection of oxygen into the slag via an upper row of nozzles to promote post-combustion. In the process of Romelt, the metal layer is not an important reaction medium. Another known group of direct melt processes that are slag based are generally described as "deep slag" processes. These processes, such as the DIOS and AISI processes, are based on the formation of a deep layer of slag with 3 regions, that is: an upper region for the post-combustion of reaction gases with injected oxygen; a lower region for the fusion of metal-to-metal oxides and an intermediate region separating the upper and lower regions. As with the Romelt process, the metal layer below the slag layer is not an important reaction medium. Another known direct fusion process that depends on a layer of molten metal as a reaction medium and is generally referred to as the Hismelt process, is described in the international patent application PCT / AU00197 (WO 96/31627) in the name of the applicant.

The Hlsmelt process as described in the international application comprises: (a) forming a bath of molten iron and slag in a container; (b) injecting into the bath: (i) metalliferous feed material, usually metal oxides and (ii) a solid carbonaceous material, usually carbon, which acts as a reductant of metal oxides and a source of energy and (c) melt the metal-to-metal feed material in the metal layer. The Hlsmelt process also comprises subjecting to post-combustion the 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 melt the metalliferous feedstocks. The Hlsmelt process also comprises forming a transition zone above the normal quiescent surface of the bath in which there is a favorable mass of droplets or ascending spills and thence descending of molten metal and / or slag which provide an effective means for transferring to the bath the thermal energy generated by the post-combustion of the reaction gases above the bath. The Hlsmelt process as described in the international application is characterized by the formation of the transition zone by injecting a carrier gas and metalliferous feed material and / or solid carbonaceous material and / or other solid material into the bath through a section of the side of the container that is in contact with the bath and / or from above the bath, in such a way that the carrier gas and the solid material enter the bath and cause the molten metal and / or slag to be projected into the space above the surface of the bathroom. The Hlsmelt process as described in the international application is an improvement over previous forms of the Hlsmelt process which forms the transition zone by injection to the bottom of the gas and / or carbonaceous material to the bath, which causes drops and splashes and streams of molten metal and slag are projected from the bath. The applicant has carried out extensive pilot plant work on the Hlsmelt process and has made a number of significant findings in relation to the process. In general terms, the present invention is a direct melting process for producing metals from a metalliferous feedstock that includes the steps of: (a) forming a molten bath having a metal layer and a slag layer on the metal layer in a metallurgical vessel; (b) injecting metal feed material and solid carbonaceous material into the metal layer via a plurality of lances / nozzles; (c) melting the metalliferous material to metal in the metal layer; (d) causing the molten material to be projected as splashes, droplets and streams into a space above a normal quiescent surface of the molten bath to form a transition zone and (e) injecting an oxygen containing gas into the vessel via one or more of the lance / nozzle for post-combustion of the reaction gases released from the molten bath, whereby splashes, drops and upward and then downward currents of molten material in the transition zone facilitate the transfer of heat to the molten bath and whereby the transition zone minimizes the heat loss of the container via the side walls in contact with the transition zone; and includes the stage of controlling the process by maintaining a high slag inventory. It is understood herein that the term "melting" means thermal processing, wherein chemical reactions are carried out that reduce the metalliferous feedstock to produce the liquid metal. It is understood that the term "quiescent surface" in the context of the molten bath means the surface of the molten bath under process conditions in which there is no gas / solids injection and therefore, no agitation of the bathroom. The space above the nominal quiescent surface of the molten bath is hereinafter referred to as the "upper space". A significant result of the work in the pilot plant is that it is important to maintain high levels of slag in the container and more particularly in the transition zone in order to control the heat losses of the container and the transfer of heat to the metal layer . The importance of slag to the Hlsmelt process is a significant departure from previous work on the HIsmelt process. In the previous work, the amount of slag was not considered important for the process.

The concept of a "high slag inventory" can be understood in the context of the depth of the slag layer in the container. Preferably, the process includes maintaining the high slag inventory by controlling the slag layer in such a way that it is 0.5 to 5 meters deep under stable operating conditions. More preferably, the process includes maintaining the high slag inventory by controlling the slag layer in such a way that it is 1.5 to 2.5 meters deep under stable operating conditions. It is particularly preferred that the process includes maintaining the high slag inventory by controlling the slag layer in such a manner that it is at least 1.5 meters deep under stable operating conditions. The concept of a "high slag inventory" can also be understood in the context of the amount of slag compared to the amount of metal in the container. Preferably, when the process is put into operation under stable conditions, the process includes maintaining the high level of slag by controlling the proportion by weight of metal: slag in such a way that it is between 4: 1 and 1: 2.

More preferably, the process includes maintaining the high slag inventory by controlling the weight ratio of metal: slag in such a way that it is between 3: 1 to 1: 1. It is particularly preferred that the process includes maintaining the high slag inventory by controlling the weight ratio of metal: slag in such a way that it is between 3: 1 and 2: 1. The amount of slag in the vessel, that is, the slag inventory, has a direct impact on the amount of slag that is in the transition zone. The relatively low heat transfer characteristics of slag in comparison with the metal is important in the context of minimizing the heat loss of the transition zone to the side walls and of the container via the side walls of the container. By appropriate process control, the slag in the transition zone can form a layer or layers on the side walls that adds resistance to the heat loss of the side walls. Therefore, by changing the slag inventory, it is possible to increase or decrease the amount of slag in the transition zone and on the side walls and consequently control the heat loss via the side walls of the container.

The slag can form a "wet" layer or a "dry" layer on the side walls. A "wet" layer comprises a frozen layer that adheres to the side walls, a semi-solid layer (soft mass) and an outer liquid film. A "dry" layer is one in which substantially all of the slag is frozen. The amount of slag in the container also provides a measure of control with respect to the extent of post-combustion. Specifically, if the slag inventory is too low there will be an increased exposure of the metal in the transition zone and consequently increased oxidation of metal and carbon dissolved in the metal and the reduced post-combustion potential and sequential post-combustion decrease, notwithstanding the positive effect that the metal in the transition zone has on the transfer of heat to the metal layer. In addition, if the slag inventory is too high, one or more of a gas injection nozzle / nozzle containing oxygen will be buried in the transition zone and this minimizes the movement of the reaction gases from the upper space to the extreme the or each spear / nozzle and as a consequence, reduces the potential for post-combustion. The amount of slag in the vessel, that is, the slag inventory, measured in terms of the depth of the slag layer or the weight ratio of metal: slag, can be controlled by the slag and metal bypass rates. The production of slag in the container can be controlled by making the feed rates of the metalliferous feed material, carbonaceous material and alkaline fluxes to the container and operating parameters such as gas injection velocities , contains oxygen. The process of the present invention is characterized by the control of the heat transfer via the transition zone to the metal layer and the control of the heat loss of the container via the transition zone. As indicated above, in particular the present invention is characterized by the control of the process by maintaining a high slag inventory. Furthermore, the present invention is preferably characterized by process control by means of the following process characteristics, separately or in combination: (a) locating or locating one or more of a gas injection nozzle / nozzle containing oxygen and injecting the oxygen-containing gas at a flow rate, such that: (i) the oxygen-containing gas is injected into the slag layer and enters the transition zone and (ii) the gas stream that contains oxygen deviates splashes, drops and streams of molten material around a lower section of the or each nozzle / nozzle and a gas continuous space, described as a "free space" is formed around the end of the or each nozzle / nozzle; (b) controlling the heat loss of the container by predominantly slag slag on the side walls of the container in contact with the transition zone by adjusting one or more of: (i) the amount of slag in the molten bath; (ii) the injection flow rate of the oxygen-containing gas through one or more of a gas injection nozzle / nozzle containing oxygen and (iii) the flow velocity of the metal feed material and carbonaceous material through the spears / nozzles. In situations where the metalliferous feedstock is an iron-containing material, the present invention is also preferably characterized by controlling the process by controlling the level of dissolved carbon in the molten iron, so that it is at least 3% by weight and keeping the slag in a strongly reducing condition leading to U Fe levels of less than 6% by weight, more preferably less than 5% by weight in the slag layer and in the transition zone. Preferably, the metallurgical vessel includes: (a) the one or more of a lance / nozzle described above for injecting oxygen containing gas and the lances / nozzles for injecting solid materials, such as metalliferous material, carbonaceous material (usually carbon) and alkaline fluxes, to the container; (b) outlets for discharging molten metal and slag from the container and (c) one or more release gas outlets. In order to put the process into operation, it is essential that the vessel contains a molten bath having a layer of metal and a layer of slag on the metal layer. In the present, it is understood that the term "metal layer" means that region of the bath that is predominantly of metal. In the present, it is understood that the term "slag layer" means that region of the bath that is predominantly slag. An important aspect or feature of the process of the present invention is that the metalliferous material is molten to metal and at least predominantly in the metal layer of the molten bath. In practice, there will be a proportion of the metalliferous material that is molten to metal in other regions of the container, such as the slag layer. However, the purpose of the process of the present invention and an important difference between the process and the processes of the prior art, is to maximize the fusion of the metalliferous material in the metal layer. As a consequence of the above, the process includes injecting metalliferous material and carbonaceous material, which acts as a source of reducing agent and as an energy source, to the metal layer. One option is to inject metalliferous material and carbonaceous material via lances / nozzles positioned above and extending downward towards the metal layer. Normally the nozzles / nozzles extend through the side walls of the container and are angled inwards and downwards towards the surface of the metal layer. Another option, although by no means the only other option, is to inject metalliferous material and carbonaceous material via nozzles to the bottom of the container or to the side walls of the container that come into contact with the metal layer.

The injection of metalliferous material and carbonaceous material can be through the same lances / nozzles or separate lances / nozzles. Another important aspect or feature of the process of the present invention is that it causes the molten material, usually in the form of splashes, drops and currents, to be projected upwardly from the molten bath to at least part of the upper space above the surface Quiescent of the bathroom to form the transition zone. The transition zone is quite different from the slag layer. By way of explanation, under stable operating conditions of the process, the slag layer comprises gas bubbles in a liquid continuous volume, while the transition zone comprises splashes, drops and streams of molten material in a continuous gas volume. Preferably, the process includes: causing the molten material to be projected as splashes, drops and streams into the upper space above the transition zone. Another important aspect or characteristic of the present invention is that it undergoes post-combustion the reaction gases, such as carbon monoxide and hydrogen, generated in the molten bath, in the upper space (which includes the transition zone) above the nominal quiescent surface of the bath and transfer the heat generated by the post-combustion to the metal layer to maintain the bath temperature - since it is essential in view of the endothermic reactions in that layer. Preferably, the oxygen-containing gas consists of air. More preferably, the air is pre-heated. Normally, the air is pre-heated to 1200 ° C. The air can be enriched with oxygen. Preferably, the post-combustion level is at least 40%, where the post-combustion is defined as: [C02] + [H20] [C02] + [H20] + [CO] + [H2] where: [C02] in volume of C02 in the release gas; [H20] by volume of H2O in the release gas; [CO] in volume of CO in the release gas; [H2] by volume of H2 in the release gas.

The transition zone is important for 2 reasons: First, splashes, drops and upward and then downward currents of molten material are an effective means to transfer to the molten bath the heat generated by post-combustion of the exhaust gases. reaction in the upper space above the quiescent surface of the bath. Secondly, the molten material, and in particular the slag, in the transition zone is an effective means for minimizing heat loss via the side walls of the container. A fundamental difference between the process of the present invention and the processes of the prior art is that in the process of the present invention the main fusion region is the metal layer and the main oxidation region (ie, heat generation). it is above and in the transition zone and these regions are spatially well separated and the heat transfer is via the physical movement of the molten metal and slag between the two regions. Preferably, the transition zone is generated by injecting metalliferous material and carbonaceous material into a carrier gas through lances / nozzles extending downward towards the metal layer.

More preferably, as indicated above, the nozzles / nozzles extend through the side walls of the container and are angled inwards and downwards towards the metal layer. This injection of the solid material to and from this into the metal layer has the following consequences: (a) the momentum (or momentum) of the solid material / carrier gas causes the solid material and gas to penetrate the metal layer; (b) the carbonaceous material, usually carbon, is devolatilized and thereby produces gas in the metal layer; (c) coal dissolves predominantly in the metal and partially remains as a solid; (d) the metalliferous material is fused to metal by the carbon derived from the injected carbon as described above in Item (c) and the fusion reaction generates carbon monoxide gas and (e) the gases transported to the metal layer and generated via devolatilization and melting produce a significant buoyance lift of the molten metal, solid carbon and slag (which is attracted to the metal layer as a consequence of the solid / gas injection) of the metal layer, which results in a Upward movement of splashes, drops and currents of molten metal and slag and these splashes, drops and currents carry additional scourge as they move through the slag layer. Another important aspect of the present invention is that the situation (or location) and the operator parameters of the one or more of a lance / nozzle that injects the oxygen-containing gas and the operating parameters that control the transition zone are selected. in such a way that: (a) the oxygen-containing gas is injected into the slag layer and enters the transition zone; (b) the stream of oxygen-containing gas deflects splashes, drops and streams of molten metal in such a way that, in effect: (i) the transition zone extends upwardly around the lower section of the one or more of a lance / nozzle and (ii) a gas continuous space described as a "free space" is formed around the end of one or more of a lance / nozzle. The formation of the free space is an important aspect because it makes it possible for the reaction gases in the upper space of the container to be extracted to the end region of the one or more of a gas injection nozzle / nozzle containing oxygen and are subjected to post-combustion in the region. In this context, it is understood that the term "free space" means a space that practically does not contain metal and slag. In addition, the above described deviation of molten metal shields to some degree the side walls of the combustion zone generated at the end of the or each lance / nozzle. It also provides a means to return more energy to the bath of the gases subjected to post-combustion in the upper space. Preferably, the process includes injecting the oxygen containing gas into the container in a swirling motion. The present invention is further described by way of example with reference to the accompanying drawing which is a vertical section through a metallurgical vessel schematically illustrating a preferred embodiment of the process of the present invention. The following description is in the context of iron ore (or mineral) melting to produce molten iron and it will be understood that the present invention is not limited to this application and is applicable to any ores (or minerals) and / or appropriate metal concentrates - including partially reduced metal ores and waste recovery materials.

The container shown in the figure has a core including a base 3 and sides 55 formed of refractory bricks; side walls 5 forming a generally cylindrical barrel extending upwardly from the sides 55 of the core and including an upper barrel section 51 and a lower barrel section 53; a roof 7; an outlet 9 for the release gases; a forehearth 57 for discharging molten metal continuously; and a purge hole 61 for discharging the molten slag. In use, the container contains a molten iron and slag bath including a layer 15 of molten metal and a layer 16 of molten slag on the metal layer 15. The arrow marked with the number 17 indicates the position of the nominal quiescent surface of the metal layer 15 and the arrow marked with the number 19 indicates the position of the nominal quiescent surface of the slag layer 16. It is understood that the term "quiescent surface" means the surface when there is no injection of gas and solids at the container. The container also includes 2 solids injection nozzles / nozzles extending downward and inward at an angle of 30-60 degrees relative to the vertical through the side walls 5 and the slag layer 16. The position of the nozzles / nozzles 11 are selected in such a way that the lower ends are above the quiescent surface 17 of the metal layer 15. In service, ore (mineral) iron, solid carbonaceous material (usually carbon) and alkaline fluxes (typically lime and magnesia) entrained in a carrier gas (usually N2) are injected into the metal layer 15 via the nozzles / nozzles 11. The moment (momentum) of the solid material / carrier gas causes the solid material and gas penetrate the metal layer 15. The carbon is devolatilized and by this produces gas in the metal layer 15. The carbon partially dissolves to the metal and partially remains as solid carbon. The ore (ore) of iron is fused to metal and the fusion reaction generates carbon monoxide gas. The gases transported to the meta layer 15 and generated via devolatilization and melting produce a significant buoyant lift of the molten metal, solid carbon and slag (attracted to the metal layer 15 as a consequence of the solid / gas injection) of the coating. metal 15 which generates an upward movement of splashes, drops and currents of molten metal and slag and these splashes and droplets and streams entrain slag as they move through the slag layer 16. The rise of molten metal, Solid carbon and slag causes substantial agitation in the metal layer 15 and the slag layer 16, with the result that the slag layer 16 expands in volume and has a surface indicated by the arrow 30. The agitation extension is such that there is a reasonably uniform temperature in the metal and slag regions - usually 1450 ° C - 1550 ° C, with a temperature variation of the order of 30 ° C In each region. In addition, the upward movement of splashes, drops and streams of molten material caused by the lifting of buoyant molten metal, solid carbon and slag extends to the upper space 31 above the molten bath in the container and (a) forms a transition zone 23 and (b) project some molten material (predominantly slag) beyond the transition zone and over the part of the upper barrel section 51 of the side walls 5 which is above the transition zone 23 and on the roof 7. Generally speaking, the slag layer 16 is a continuous volume of liquid, with gas bubbles therein and the transition zone 23 is a continuous volume of gas with splashes., drops and currents of molten metal and slag. The container further includes a lance 13 for injecting an oxygen containing gas (usually oxygen enriched, preheated air) which is located or centrally located and extends vertically downward to the container. The position of the lance 13 and the velocity of: gas flow through the lance 13 are selected such that the oxygen-containing gas penetrates the central region of the transition zone 23 and maintains a free space essentially free. metal / slag around the end of the lance 13. The lance 13 includes an assembly or assembly that causes the oxygen-containing gas to be injected in a swirling motion into the container. The injection of the oxygen-containing gas via the lance 13, post-combustion reaction gases CO and H2 in the transition zone 23 and in the free space around the end of the lance 13 and generates high temperatures of the order of 2000 ° C or higher in the gas space. The heat is transferred to the splashes, drops and up and down streams of molten material in the gas injection region and the heat is then partially transferred to the metal layer 15 when the metal / slag returns to the metal layer 15. The free space 25 is important to obtain high levels of post-combustion because it allows the entrainment of gases in the space above the transition zone 23 to the end region of the lance 13 and thereby increases the exposure of the Reaction gases available for post-combustion.

The combined effect of the position of the lance 13, the gas flow velocity through the lance 13 and the upward movement of the splashes, drops and streams of molten material is to conform the transition zone 23 around the lower region of the lance 13 identified in general by the number 27. This formed region provides a partial barrier to the transfer of heat by radiation to the side walls 5. In addition, the drops, splashes and up and down streams of material are an effective means for transferring heat from the transition zone 23 to the molten bath, with the result that the temperature of the transition zone 23 in the region of the side walls 5 is of the order of 1450 ° C - 1550 ° C. The container is constructed with reference to the levels of the metal layer 15, the slag layer 16 and the transition zone 23 in the container when the process is in operation and with reference to splashes, drops and streams of molten metal and slag which are projected into the upper space 31 above the transition zone 23 when the process is in operation, such that: (a) the core and the lower barrel section 53 of the side walls 5 which come into contact with the metal / slag layers 15/16 are formed of refractory material (indicated by the cross hatch in the figure); (b) at least part of the lower barrel section 53 of the side walls 5 is reinforced by water-cooled panels 8 and (c) the upper barrel section 51 of the side walls 5 and the roof 7 that are put in place. contact with the transition zone 23 and the upper space 31 are formed of water-cooled panels 57, 59. Each water-cooled panel 8, 57, 59 in the upper section 10 of the side walls 5 has parallel upper and lower edges and Parallel lateral edges and is curved to define a section of the cylindrical barrel. Each panel includes an internal water cooling tube and an external water cooling tube. The tubes are formed in a coil configuration with horizontal sections interconnected by curved sections. Each tube also includes a water inlet and a water outlet. The tubes are displaced vertically, so that the horizontal sections of the outer tube are not immediately behind the horizontal sections of the inner tube when viewed from an exposed face of the channel, that is, the face that is exposed to the interior of the container. Each panel also includes a compacted refractory material that fills the spaces between the adjacent horizontal sections of each tube and between the tubes. The water inlets and the water outlets of the pipes are connected to a water supply circuit (not shown) which circulates the water at high flow velocity through the pipes. In service, the operating conditions are controlled in such a manner that sufficient slag is brought into contact with the water-cooled panels 57, 59 and sufficient heat extraction of the panels to accumulate and maintain a slag layer on the panels. The slag layer forms an effective thermal barrier for heat loss via the transition zone and the remainder of the upper space above the transition zone. As indicated above, the following process characteristics have been identified, in pilot plant work that, separately or in combination, provide effective control of the process. (a) control of the slag inventory, that is, the depth of the slag layer and / or the proportion of metal / slag, to balance the positive effect of the metal in the transition zone 23 on the heat transfer with the effect negative metal in the transition zone 23 over post-combustion due to subsequent reactions in the transition zone 23. If the slag inventory is too low, the exposure of the metal to oxygen is too high and there is a reduced potential for post-combustion . On the other hand, if the slag inventory is too high, the spear 13 will be buried in the transition zone 23 and there will be a reduced entrainment of gas into the free space 25 and reduced post-combustion potential. (b) control of the level of dissolved carbon in the metal, such that it is at least 3% by weight and maintain the slag in a strongly reducing condition leading to FeO levels of less than 6% by weight in the layer slag 16 and in the transition zone 23. (c) select the position of the lance 13 and control the injection rates of the gas containing oxygen and solids via the lance 13 and lances / nozzles 11 to keep the region essentially free of metal / slag around the end of the lance 13 and forming the transition zone 23 around the lower section of the lance 13. (d) control of the heat loss of the container by splattering the side walls of the container that are in contact with the transition zone 23 or that are above the transition zone 23 by adjusting one or more of: (i) the slag inventory and (ii) the injection flow velocity through the lance 13 and the lance / nozzles 11. Work The pilot plant referred to above was carried out as a series of extensive campaigns by the applicant at its pilot plant in Kanane, Western Australia. The work in the pilot plant was carried out with the container shown in the figure and described above and in accordance with the process conditions described above. The work in the pilot plant evaluated the container and investigated the process under a wide range of different: (a) food materials; (b) solids and gas injection speeds; (c) slag inventories - measured in terms of the depth of the slag layer and the proportions of slag: metal; (d) operating temperatures and (e) device settings. Table 1 below summarizes the relevant data during startup and stable operating conditions for work in the pilot plant.

The source of ore (ore) iron was Hamersley as a normal fine direct boarding ore and contained 64.6% iron, 4.21% SiO2 and 2.78% A1203 on a dry basis. An anthracite coal was used as a reducer and as a source of carbon and hydrogen to combust and supply energy to the process. The coal had a calorific value of 30.7 MJ / Kg, an ash content of 10% and a volatiles level of 9.5%. Other characteristics included 79.82% of total carbon, 1.8% of H2O, 1.59% of N2, 3.09% of 02 and 3.09% of H2. The process was put into operation to maintain a slag basicity of 1.3 (ratio of CaO / SiO2) using a combination of alkaline fluxes of lime and magnesia. Magnesia contributed to the MgO thereby reducing the corrosivity of the slag to the refractory by maintaining appropriate levels of MgO in the slag. Under starting conditions, the pilot plant operated with: a hot air blast speed of 26,000 Nm3 / hour at 1200 ° C; a post-combustion rate of 60% ((C02 + H20) / (CO + H2 + C02 + H20)) and an iron ore fines feed rate of 5.9 t / h, a carbon feed rate of 5.4 t / h and an alkaline flux feed rate of 1.0 t / h, all injected as solids using N2 as the carrier gas. There was little or no slag in the container and there was not enough opportunity to form a frozen slag layer on the side panels. As a consequence, the heat loss of the cooling water was relatively high at 12 MW. The pilot plant operated at a production rate of 3.7 t / h of hot metal (4.5% by weight of C) and the coal velocity of 1450 kg of carbon / t of hot metal produced. Under stable conditions, with slag inventory control and a frozen slag layer on the water cooling panels forming the side walls, relatively few 8 MW heat losses were experienced. The reduction of heat loss to the water cooling system allowed an increased productivity of 61. t / h of hot metal. Increased productivity was obtained at the same hot air burst rate and post-combustion as at start-up. The injection rates of the solid were 9.7 t / h of mineral fines and 6.1 t / h of coal along with 1.4 t / h of alkaline flux. The improved productivity also improved the speed of the coal to 1000 Kg of coal / t of hot metal obtained. Many modifications can be made to the preferred embodiments of the process of the invention as described above without deviating from the spirit and scope of the present invention. It is noted that, in relation to this date, the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention:

Claims (13)

1. CLAIMS Having described the invention as above, it is claimed as property, contained in the following claims: 1. A direct melting process to produce metals from a metal feed material, characterized by including the steps of: (a) forming a molten bath having a metal layer and a slag layer on the metal layer in a metallurgical vessel; (b) injecting metal feed material and solid carbonaceous material into the metal layer via a plurality of nozzles / nozzles and causing the molten material to be projected as splashes, drops and streams into an upper space above a nominal quiescent surface of the molten bath to form a transition zone; (c) melting the metalliferous material to metal in the metal layer and (d) injecting an oxygen-containing gas into the vessel via one or more of a lance / nozzle to subject to post-combustion the reaction gases released from the molten bath, whereby the splashes, drops and upward and then downward currents of molten material in the transition zone facilitate the transfer of heat to the molten bath and by this the transition zone minimizes the heat loss of the container via the side walls in contact with the transition zone; such process includes the step of controlling the process by maintaining a high slag inventory.
2. 2. The process in accordance with the claim 1, characterized in that it includes maintaining the high level of slag by controlling the slag layer in such a way that it is from 0.5 to 4 meters.
3. 3. The process in accordance with the claim 2, characterized in that it includes maintaining the high level of slag by controlling the slag layer in such a way that it is 1.5 to 2.5 meters deep.
4. 4. The process according to claim 1, characterized in that it includes maintaining the high level of slag by controlling the slag layer in such a way that it is at least 1.5 meters deep.
5. 5. The process according to claim 1, characterized in that it includes controlling the proportion by weight of metal: slag in such a way that it is between 4: 1 and 1: 2.
6. The process according to any of the preceding claims, characterized in that it includes controlling the weight ratio of metal: slag in such a way that it is between 3: 1 and 1: 1 under stable operating conditions of the process.
7. The process according to claim 6, characterized in that it includes maintaining the high level of slag by controlling the weight ratio of metal: slag in such a way that it is between 3: 1 and 2: 1 under stable operating conditions of the process.
8. The process according to any of the preceding claims, characterized in that step (c) includes melting the metalliferous material to metal, at least predominantly in the metal layer.
9. 9. The process according to any of the preceding claims, characterized in that it includes placing or locating the one or more of a spear / gas nozzle containing oxygen and injecting the oxygen-containing gas at a flow rate in such a way that: (a) the oxygen-containing gas is injected into the slag layer and penetrates the transition zone and (b) the stream of oxygen-containing gas deflects splashes, drops and streams of molten material around a lower section of the or more than one lance / nozzle and a continuous gas space is formed around the end of one or more of a lance / nozzle.
10. The process according to any of the preceding claims, characterized in that it includes controlling the heat loss of the container by splashing predominantly slag to the side walls of the container that are in contact with the transition zone and on the roof of the container when adjusting. one or more of: (i) the amount of slag in the molten bath; (ii) the injection flow rate of the oxygen-containing gas through one or more of a gas injection nozzle / nozzle containing oxygen and (ii) the flow velocity of the metalliferous feed material and carbonaceous material to through the spears / nozzles.
11. The process according to any of the preceding claims, characterized in that step (b) of claim 1 includes locating the plurality of lances / nozzles above and extending downwardly of the metal layer.
12. 12. The process according to any of the preceding claims, characterized in that it includes feeding metalliferous feedstock and solid carbonaceous material into an inert carrier.
13. 13. The process according to claim 12, characterized in that it includes locating the plurality of lances / nozzles above and extending downward toward the metal layer.