MXPA96002824A - Method and apparatus to produce arrabio by fusion reduction and method to obtain such pla - Google Patents

Abstract

The present invention relates to: A plant for a melt reduction process for the production of pig iron, using charcoal and oxygen-containing gas, is obtained by converting an existing blast furnace plant by replacing the blast furnace (1) with an apparatus that includes at least one metallurgical vessel (8) for carrying out the melt reduction process, while at least partially retaining at least one of the following components of the existing blast furnace plant: i) storage vessels ( 4) for the mineral iron ii) storage containers (5) for the coke, as storage tanks for the charcoal iii) a drainage housing (18) for emptying or pouring the metallurgical container iv) a discharge system (23) ) of gas, for the hot gas, including a means for removing dust (24), v) a system (25) for supplying cooling water

Description

METHOD AND APPARATUS TO PRODUCE ARRABIO BY REDUCTION BY FUSION AND METHOD TO OBTAIN SUCH PLANT.

The invention relates to a method for obtaining a plant for the production of pig iron from iron oxides by the melt reduction process, in which the iron oxides are reduced by means of charcoal and oxygen-containing gas. The invention also relates to the plant obtained by the method and to a method for producing the pig iron carried out in such a plant. For years, pig iron has been produced using the blast furnace process known in a blast furnace, in which the iron oxides in agglomerated form, such as agglutinated or in granules are reduced essentially with the help of coke and hot wind (air ). The blast furnace is a metallurgical vessel that is part of a substantial blast furnace plant, including, for example, vessels for the storage of mineral iron and coke, a bucket forklift to supply iron ore and coke in the blast furnace, hot blast furnaces, a casting housing with a means for casting the molten metal of pig iron and slag, a gas discharge system from the blast furnace, with a system of dusting and cooling with water to cool the refractory lining of the blast furnace. The coke is made in a coking plant from charcoal by dry distillation at approximately 1,000 ° C. This causes the volatile constituents to escape from the coal and produce coke, which provides a porous, strong structure in the blast furnace. The manufacture of coke is expensive and environmentally dangerous. A modern blast furnace usually has a melting chamber diameter of 12 to 14 m, a production of 3 to 4 million tons of pig iron per year and when it is newly built, it requires an invention of 1 billion FL (approximately $ 600 millions of dollars) . A blast furnace is operated continuously during a work campaign which for a blast furnace with a modern refractory lining, can last for 10 years, the end is determined by the need to replace the refractory lining. At the end of the work term, the blast furnace is off and repaired (reinforced). In several places in the world, work has continued for some decades in the development of alternative processes to produce pig iron by melt reduction in which the iron oxides are reduced essentially with charcoal and oxygen or a gas containing oxygen. In the specialist literature, such processes are known by the names (trademarks) AISI Direct Iron aking, CCF, Corex, GOD and Hismelt. The advantage of these processes is that no coke is needed for the production of pig iron and that in some of the processes, namely CCF, GOD and Hismelt, the process of mineral preparation by agglomeration (granule formation) can be omitted. The AISI Direct Ironmaking, CCF and GOD are the so-called molten slag bath reduction processes, in which the final reduction of the mineral iron takes place in a slag layer that floats on the liquid pig iron. The CCF process is described in EP-A-690136, EP-A-686703 and European Patent Applications 96200246, and 96200774, which will be published soon, to which reference should be made for the details. Hismelt is the so-called process of reduction of the bath of cast iron. To date, only the Corex process has been used on an industrial scale. However, the process has high carbon consumption and produces a lot of gas. Although promising results have been obtained from the development of the other mentioned processes, to date a gap towards industrial application, partially due to the investment cost of a facility for these processes, is not significantly lower than for the installation of a blast furnace and The price of the cost of pig iron is not less than with a blast furnace.

The experimental work in the CCF process is described in "Steel Times" (published in the United Kingdom), May 1993, page 220. In a first attempt to direct the melting of the mineral iron in a blast furnace, it was converted by tests of direct reduction, using charcoal instead of coke, but charcoal was in agglomerated form. To avoid the need for agglomerated ore, a new furnace known as a cyclone furnace and converter (CCF) was designed, having a total reduction vessel, similar to a converter in shape, as its bottom and a cyclone reactor mounted immediately above him. The ore is pre-reduced in the cyclone reactor by a reducing process that causes gas in the lower vessel. In the lower container, the mineral is finally reduced by means of charcoal and oxygen. The oxygen effects the post-combustion of the gas in the lower vessel to provide heat. It was also mentioned that DE-A-3608150 and DE-A-3720648 describe processes and vessels for direct reduction of oxides. In particular, DE A-3720648 proposes the adaptation of a blast furnace by adding openings for air injection at two levels. The object of the invention is to provide a method for obtaining a plant, and a plant and a method for producing pig iron by melt reduction with a lower investment cost and a lower cost price of pig iron than with a blast furnace. According to the invention in one aspect, there is provided a method for obtaining a plant for a melt reduction process for the production of pig iron, in which the iron oxides are reduced by means of charcoal and an oxygen-containing gas , which comprises the stage of converting an existing blast furnace plant into the plant for the process by melt reduction, replacing the blast furnace in the blast furnace plant by an apparatus that includes at least one metallurgical vessel, suitable to carry the melting reduction process, while at least partially retaining at least one of the following components of the existing blast furnace plant: i) storage tanks for the mineral iron to be supplied to the metallurgical vessel, ii ) storage containers for the coke, as storage containers for the charcoal to be supplied to the metallurgical vessel, iii) a casting housing having a means for casting pig iron and slag, for casting the metallurgical vessel, iv) a gas discharge system for hot gas from the blast furnace including a dusting means, for gas handling discharge from the melt reduction process, and v) a cooling water supply system for the blast furnace, such as a cooling water supply system for the metallurgical vessel. Any combination of two or more of the above components of the existing blast furnace plant can be retained in the new plant. In another aspect, the invention provides a plant obtained by the above method of the invention. The invention further comprises a method of producing pig iron, using charcoal and oxygen-containing gas, in a plant obtained by the above method of the invention. Preferably, in the invention the melt reduction process is of a type comprising a process of pre-reduction of iron oxides, using a reducing process gas and a final reduction process of pre-reduced iron oxides , in which "the pre-reduced iron oxides are finally reduced in a final reduction vessel, mainly with the help of charcoal and oxygen, in which the reducing process gas originates. final reduction, in which the final reduction process is carried out, a production rate of pig iron is applied per unit cross-sectional area of final reduction vessel in the range of 40-120 ton / m2 / 24h. AISI Direct Ironmaking, CCF, GOD and Hismelt are suitable for this. The Corex process has a lower production speed. For these processes, the average vertical flow velocity of the process gas through the empty internal cross section of the final reduction vessels is, for example, 1-5 m / s. Preferably, the production rate of the pig iron in the final reduction vessel, which is used in place of the blast furnace, is at least equal to the production rate of the blast furnace relative to the cross section of the blast chamber of the blast furnace and is greater than 60 ton / m2 / 24h. AISI Direct Ironmaking, CCF and GOD are suitable for this. In terms of the design of the final reduction vessel, the Hismelt process is less suitable to be used in place of a blast furnace. Preferably, a pre-reduction process of the iron oxides is applied in a melting cyclone in which, with oxygen that is supplied, a combustion is maintained in the gas of the reduction process (the CCF process). The CCF process is particularly suitable due to the compactness of the pre-reduction. The DIOS and AISI Direct Ironmaking processes are less suitable due to the size and complexity of their pre-reduction, which is probably less easy to accommodate in a blast furnace installation. Surprisingly it was arrived at the point of view that in terms of production speed, the blast furnace process and the fusion reduction process are to a certain extent, compatible and that significant advantages can be obtained by converting the installation of a blast furnace for the reduction by fusion. The conversion can be carried out at the end of a working term of the blast furnace or earlier. With a somewhat equivalent production speed, the supply quantities of mineral iron and charcoal or coke and the installation parts for the storage and supply of them are also compatible. These parts of the installation to discharge the pig iron, slag and gas from the process are also compatible. With this invention, a significantly lower cost price of up to 50.00 FL (approximately $ 30.00 dollars) per ton of pig iron less than with the blast furnace process, can be obtained without coke and using certain melt reduction processes, without granules for a cost very low investment, which is comparable to the costs of furnace repair.

Preferably, the pressure in the final reduction vessel is in the range of 1-5 atmospheres. This pressure is chosen appropriately depending on the desired production speed. In this way, in certain cases, the production speed of the fusion process can be done to be virtually the same as that of the blast furnace, in such a way that both processes and installations are virtual and completely compatible. Preferably, the actual production speed of the pig iron remains lower than the production speed of the pig iron that has the lowest possible charcoal consumption, per ton of pig iron produced in the plant used and the real production speed of the gas of the reduction process is increased in relation to the speed of production of the same, which corresponds to this speed of production of pig iron that has the lowest possible consumption of charcoal. In this way, the actual production speed of the pig iron can be lower than the * Speed of production of pig iron that has the lowest possible charcoal consumption of 0 to 30%, and the real production speed of the gas of the reduction process can be greater than the production speed of the same, which corresponds to the speed of production of pig iron that has the lowest possible charcoal consumption of 0 to 30%.

With a blast furnace, the purpose is to achieve by all types of media, such as carbon-powder injection, the lowest possible consumption of coke, because coke is a very expensive material. However, a minimum quantity of 300 kg of coke / tonne of pig iron is needed for the process in the blast furnace. With the processes of reduction by fusion and in particular with the CCF process, there is the possibility to increase the consumption of charcoal in relation to a minimum charcoal consumption of 500-640 kg / ton (gasification of coal). This reduces the production speed and increases the amount and energy content of the process gas that leaves the melting reduction facility, which process gas can be used to generate energy. As indicated above, preferably the metallurgical vessel, which replaces the blast furnace, comprises a final reduction vessel and a melting cyclone, directly above the final reduction vessel and in open communication therewith. Where the blast furnace plant includes a steel structure, around the blast furnace, the metallurgical vessel is preferably installed inside the steel structure, which is retained. If the apparatus for carrying out melt reduction includes a kettle, in which the water is heated by the discharge gas, from the melt reduction process, the kettle can also be installed inside the steel structure. The metallurgical vessel may thus comprise a final reduction vessel having a characteristic larger diameter, which is not greater than the largest characteristic diameter of the blast furnace which is replaced. In this way, the conversion work of the blast furnace plant can be made not very expensive and the cost of the investment can be kept low. Depending on the particular melt reduction process used in the invention, the oxygen-containing gas may be air, air enriched with oxygen or oxygen. For the CCF process, oxygen is required, which can be obtained by the addition of an oxygen fabricating device during the conversion of the blast furnace plant. Oxygen is used in the manufacture of steel, in such a way that the iron and steel factory already has the capacity to manufacture oxygen, but the strict requirement for the low content of nitrogen in oxygen for the manufacture of steel does not apply to the production of pig iron by the CCF process. Therefore, a lower grade oxygen manufacturing facility can be conveniently added to the blast furnace plant that is converted according to the invention.

In this way, where the oxygen-containing gas is oxygen and the metallurgical vessel comprises a final reduction vessel and a melting cyclone to which the oxygen is fed, the conversion method may include adding an oxygen-producing plant to the installation. existing blast furnace. One embodiment of the invention will now be described by way of non-limiting example with reference to the drawing in which Figure 1 is a schematic and diagrammatic side view of a plant producing pig iron exemplifying the invention. Figure 1 shows schematically the situation after the conversion of an existing blast furnace plant, in which, for the production of pig iron, the blast furnace process is replaced by the melt reduction CCF process. However, the invention is not limited to this melt reduction process and also applies to other melt reduction processes, such as those discussed in the foregoing. The dotted lines in Figure 1 indicate those parts of the existing blast furnace plant, which are no longer necessary after the conversion and are removed. The new plant parts added in the conversion are highlighted. In the existing plant, the blast furnace 1 is supplied, by means of a bucket loading 2, and a bell 3, with iron ore in the form of agglutination or granules of the storage tanks 4 of the existing material and with coke the storage containers 5 of the existing material. The hot wind (air) is supplied from the hot-air furnaces 6 and by means of the main hot wind 7. In the conversion of the blast furnace 1, it is replaced by a metallurgical vessel 8 for the melt reduction of iron compounds. Figure 1 shows that this vessel for melt reduction is of the CCF (Cyclone Converter Oven) type, having a cyclone reactor 9 in which the pre-reduction and melting of the iron oxides are carried out and a vessel 10 of final reduction in which there is a molten pig iron 11 with a layer 12 of slag, floating on top of it. The cyclone reactor 9 is immediately above the final reduction vessel 10, to form a single unit, and the two are in direct open communication with each other. The iron * oxides are supplied from the container 4 of existing material by means of the feed system 13 to the container cyclone reactor 9 CCF. These iron oxides may consist of both conglomerate iron ore and blast furnace dust or converter powder. In the case of a CCF process, iron ore can be supplied without agglomeration.

The charcoal is supplied from the containers 5 of existing material by means of a feed system 14 to the final reduction vessel 10. The oxygen is fed via the supply line 15 to the cyclone reactor 9, and by means of the supply line 16 to the final reduction vessel 10, both supplies originate from the new oxygen plant 17. Great advantages of the invention in the investment cost are obtained because, after conversion, continuous use is made of many parts of the existing blast furnace plant, which may not require much adaptation. Retained from the existing plant in this case, are the emptying housing 18 with its means for casting the pig iron 19 and the slag 20, and the cooling water supply system 25 now. it is adapted to cool the cyclone 9 and the final reduction container 10, as well as the storage containers 4, 5. In addition, the cyclone 9, and the final reduction vessel 10, are installed within the steel structure 21 of the original blast furnace 1. The process gas generated during the direct reduction is discharged at a temperature of 1,400 ° C to 1,800 ° C, from the cyclone by means of a new water heating boiler 22 and by means of the gas discharge system 23 of the blast furnace existing with a means 24 of removing dust.

Having described the invention as above, property is claimed as contained in the following:

Claims (14)

1. A method for obtaining a plant for a melt reduction process for the production of pig iron, in which the iron oxides are reduced by means of charcoal, and oxygen-containing gas, characterized in that it comprises the step of converting a plant of iron. existing furnace in the plant for the melt reduction process replacing the blast furnace in the blast furnace plant by the apparatus that includes at least one metallurgical vessel, suitable to carry out the melt reduction process, while retaining at least partially, at least one of the following components of the existing blast furnace plant: i) containers of. storage for mineral iron ii) storage containers for coke, as storage containers for charcoal iii) a disposal housing that has a means for casting pig iron and slag, for casting the metallurgical vessel iv) a discharge system of gas for the hot gas from the blast furnace, which includes a means to remove the dust, to manipulate the discharge gas from the melt reduction process v) a cooling water supply system for the blast furnace, as a cooling water supply system for the metallurgical vessel.

2. The method according to claim 1, characterized in that the metallurgical vessel comprises a final reduction vessel and a melting cyclone directly above the final reduction vessel and in open communication with it.

3. The method according to claim 1 or 2, characterized in that the blast furnace plant includes a steel structure around the blast furnace and the metallurgical vessel is installed inside the steel structure, which is retained.

4. The method according to claim 3, characterized in that the apparatus for carrying out melt reduction includes a boiler, in which the water is heated by the discharge gas, from the melt reduction process, the boiler that It is installed inside the steel structure.

5. The method according to any of claims 1 to 4, characterized in that the metallurgical vessel comprises a final reduction vessel having a characteristic larger diameter, which is larger than the largest characteristic diameter of the blast furnace, which is replaced.

6. The method according to any of claims 1 to 5, wherein the oxygen-containing gas is oxygen, and the metallurgical vessel comprises a final reduction vessel, a melting cyclone to which oxygen is fed, the method is characterized in that includes the stage of adding a plant that produces oxygen to the existing blast furnace plant.

7. The plant for carrying out a melt reduction process for the production of pig iron, obtained by a conversion method according to any of claims 1 to 6.

8. The method for producing pig iron by performing a reduction by melting iron oxides, using charcoal and an oxygen-containing gas, which method is characterized in that it is carried out in a plant according to claim 7.

9. The method for producing pig iron according to claim 8, wherein the metallurgical container of the plant comprises a final reduction vessel, and a fusion reduction, the method is characterized in that it comprises the steps of: -reduction of the iron oxides by means of a reduction process gas obtained in step (b) below, and (b) performing a final reduction of the pre-reduced oxides of stage (a), the final reduction being It takes place in the final reduction vessel to which charcoal and oxygen are fed and in which the gas from the reduction process is produced.

10. The method for producing pig iron according to claim 9, characterized in that in the final reduction vessel, the final reduction of step (b) has a production rate of pig iron, per unit cross-sectional area of the reduction vessel. final in the range of 40 to 120 ton / m2 / hour.

11. The method for producing pig iron according to claim 9 or claim 10, characterized in that the metallurgical container of the plant further comprises of the final reduction vessel a melting cyclone, the pre-reduction of step (a) which is takes place in the melting cyclone with oxygen supply to it, in such a way that combustion is maintained in the gas of the reducing process.

12. The method for producing pig iron according to any of claims 9 to 11, characterized in that a pressure in the range of 1 to 5 atmospheres, the final reduction vessel is maintained.

13. The method for producing pig iron according to any of claims 8 to 12, characterized in that the actual production rate of pig iron is kept lower than the production rate of pig iron that has the lowest possible consumption of charcoal per ton of pig iron produced , and the real production speed of the gas from the reduction process is increased, in relation to its production speed, which corresponds to the production speed of the pig iron that has the lowest possible consumption of charcoal.

14. The method according to claim 13, characterized in that the actual production rate of pig iron is lower than the production rate of pig iron that has the lowest possible charcoal consumption by 0 to 30% and the real production speed of the gas The reduction process is greater than its production speed, which corresponds to the production speed of the pig iron that has the lowest possible charcoal consumption by 0 to 30%. RBgfMgN PE THE INVEWgIQN A plant for a fusion reduction process for the production of pig iron, using charcoal and oxygen-containing gas, is obtained by converting an existing blast furnace plant by replacing the blast furnace (1) with an apparatus that includes at least one container (8) metallurgical to carry out the melt reduction process, while retaining at least partially at least one of the following components of the existing blast furnace plant: i) storage tanks (4) for the mineral iron ii) storage containers (5) for the coke, such as storage tanks for the charcoal iii) a drain housing (18) for emptying or pouring the metallurgical vessel iv) a gas discharge system (23), for the hot gas, including a means for removing the dust (24); v) a cooling water supply system (25).