WO1991002822A1

WO1991002822A1 - Novel blast furnace process with economical iron and stell production

Info

Publication number: WO1991002822A1
Application number: PCT/AT1989/000072
Authority: WO
Inventors: Gottfried Hochegger
Original assignee: Gottfried Hochegger
Priority date: 1989-08-22
Filing date: 1989-08-22
Publication date: 1991-03-07

Abstract

The purpose of the invention is to reduce the relatively high carbon content in the traditional blast furnace by suitable means in such a way that steel melts meeting the EUROSTANDARDS are produced. Structurally, the suitable means are the provisions of a free pan or crucible-like handling area in the region of the boshes, a coking plant using coal or lignite at about the middle of the furnace and an inclined blow mould plane with blow smelting. The handling area is intended for direct iron reduction without the generation of undesired iron carbide and for the use of a refining process at the edge of the frame or through and adjacent reaction chamber. The arrangement of the coking plant inside the furnace is such that the brightly glowing coke and the highly heated reduction material meet in the handling area, resulting in shock reduction with a short reaction time in the blow mould plane without the undersired formation of iron carbide.

Description

Novel blast furnace process with economical iron and steel production

The invention relates to a method for economical iron and steel production in the blast furnace. The state of the art in the blast furnace process is characterized by the melting of a pig iron with a carbon content of, for example, 4%, which is subsequently processed in the steel plant to form the iron material steel with a maximum of 2% carbon. The delimitation of pig iron from steel is laid down in EURONORMEN 1 and 20.

The higher carbon content of iron in the blast furnace process is formed from around 900 ° C and in the area of direct reduction.

The object and aim of the invention is not to produce the relatively high carbon content in the pig iron of the traditional blast furnace process, but rather to obtain a carbon content by that of the steel by means of suitable measures and to produce a melting product which is the same as that of the steelworks.

The object of the invention is the structural and thereby also meta-lurgical change in the rest of a blast furnace to a free pan-like training, to the so-called manipulation room un the mixed exposure of ore, aggregate and fuel performed in traditional blast furnace construction so that in the middle part d blast furnace up to At the beginning of the rest, we installed a coke production furnace on hard coal or lignite with constant operation. The concentration of steel production and also coke production in the blast furnace according to the invention evidently has high economic advantages.

The change of the rest to a pan-like and crucible-like manipulation room for iron reduction without unwanted iron carbide and for the use of a fresh process is an internal separation of two reaction processes between the shaft and the rest. In patents AT-376241, DE-OS 2843303, DE-OS 3026949 and US Pat. No. 3,038,795, two reaction spaces for the reduction of iron ores are probably performed separately, but not according to the invention internally but as an external version.

It is known that in the traditional blast furnace, the reduction of iron oxides in the temperature range of 500 to 1200 ° C in the shaft and to the Beg ^• -inn the detent as the reducing reaction F.n0m + = m.CO

= n.Fe + m.CO- takes place, which is named as an indirect reduction. The effect of carbonic acid on the declining coke at around 900 ° C corresponds to the Boudourd reaction CO_ + C S-i 2.CO. The direct reduction with the reduction equation FeO + C »SÄ Fe + CO takes place in the lower half of the rest and the uppermost parts of the frame in the temperature range 900 to 1200 ° C.

The Lubatti process known in the smelting of iron ores for obtaining a steel-like melt is metallurgically an iron reduction in a phase of ore and slag, which can be a secondary effect in the process according to the invention.

The invention has for its object to maintain the indirect and direct iron reduction taking place in the traditional blast furnace and to achieve the course of a shock reduction through the pan-like and crucible-like manipulation = as well as through the central supply of glowing coke to reduce the undesirable formation of iron carbide 3Fe + 2C0 »Fe., C to prevent.

The following three shock model methods can be specified:

1) Indirect reduction and direct shock reduction:

As in the traditional blast furnace process, the indirect iron reduction can be carried out by the gases generated above the rest or the gas in the manipulation room is extracted, the CO is fractionated from it and fed to the furnace shaft from below. The direct iron reduction can be done as with traditional

The blast furnace process is carried out by burning coke with a hot wind and adding oxygen, the process also being able to use oxygen alone and another suitable fuel. To increase the CO content in the manipulation room, the CO_ gas contained in the blast furnace gas, manipulation room and coke oven gas can be fractionated and split into CO in the focal point of the blow molds.

The shock reduction to prevent the undesired iron carbide formation is achieved in that the direct ice reduction takes place so quickly when the highly heated indirectly reduced iron comes together with the coke heated to 1200 to 1400 ° C. that the indirect and direct reduction from agglomerated iron particles and the zone overcome iron carbide formation due to the too short iron carbide reaction time. This process can be intensified by forming a downward bath flow and by arranging a magnetic field for rapid iron sedimentation near the base of the frame. For the implementation of this process, a freely falling mixture of coke and reducing material is appropriate in the manipulation room because this means that fuel and reducing material only come together in the mold plane. The traditional LD process is preferred for complete steel production. carried out either on one side of the frame or in an attached reaction chamber. In the case of a satisfactory fresh process on one side of the frame, the attached reaction chamber is used for secondary metal surgery.

2) The full direct shock reduction:

In the process according to the invention, the direct iron reduction of traditional blast furnace processes is carried out with a shorter reaction time, only the reduction down to the iron oxide FeO being carried out in the furnace shaft in order to avoid the undesired iron carbide reaction due to the absence of free iron particles at the beginning of the path to the blow mold level. The direct reduction is carried out so quickly that the undesired combination of free iron, obtained from the direct reduction, cannot take place with the carbon. Due to the lack of free iron from indirect reduction, this part of iron carbide formation is not present. This process can be reinforced by forming a downward facing bath Current and by arranging a magnetic field near the base of the frame for rapid ice sedimentation. A freely falling or closed mixture of coke and reducing material is appropriate for carrying out this process, depending on whether a complete or incomplete indirect iron oxide production is to be achieved. For a complete fresh process, the traditional D process is preferably carried out either on one side of the frame or in an attached reaction chamber. If the fresh process on one side of the frame is satisfactory, the attached reactor chamber is used for secondary metallurgy. 3) The gas burner shock process:

The gas burner melting process is the same as process 1) except for a reduction in the amount of coke or other suitable reduction means and the greatest possible replacement of the hot wind for combustion by a gas burner to generate the heat of fusion. The reduction in carbon in the focal spot and only for use as a reduction carbon reduces the undesirable formation of iron carbide. The fuel gas for the gas burner is obtained internally as coke oven gas and is also used to melt the scrap in the manipulation room.

In the three shock methods mentioned, the inflation melt selected in the invention was used. However, the three shock processes mentioned can also be carried out by the blow mold melting used in the traditional blast furnace process.

An environmental economic advantage when laying the fresh process in the blast furnace is also given by the elimination of the LD dust and the dedusting systems, because the iron oxide dusts that are created in the manipulation room are filtered and melted down in the furnace shaft.

The invention is explained in more detail below with the aid of a process diagram shown schematically in the drawing: FIG. 1 describes the structural subdivisions and the temperature profile of a traditional blast furnace. The object of the invention is illustrated in FIGS. 2 and 3.

The indirect —1— and direct —2— iron reduction according to FIG. 1 carried out in the traditional blast furnace is also used in the subject matter of FIGS. 2 and 3. According to FIGS. 2 and 3, the coking plant in the middle of the furnace —3— with the roller “discharge —11— in the manipulation room —4— brings together the glowing coke and iron reduction material in a freely falling mixture —5— or closed mixture —6—. In the inclined blow mold plane —9—, in which the direct iron reduction —2— takes place, the sudden increase in temperature reduces the material to be reduced to iron in such a way that undesired iron carbide formation does not take place. In order to quickly leave free iron particles from the zone of iron carbide formation, a bath flow downwards is achieved through the focal spot and rapid sedimentation of the free iron particles is achieved by a magnet arrangement. A subsequently necessary fresh process —7— according to the known LD process takes place on one side of the frame or in an attached reaction chamber —8—. To reinforce the fresh process, scrap is brought into the manipulation room -4 from the outside by means of a lock -5. The inclined blow mold —9— designed as an inflation melt can also be a horizontal blow mold —10— after the traditional blast furnace. The vertical chamber coke oven —3— has the lock —13— with the coal bunker --14— in the upper end. The steel produced in the blast furnace according to the invention, as well as the slag, constantly leave the frame in the forms —15— and —16—.

Claims

Patent claims

1. Blast furnace process for the continuous melting of a steel specified in the Euro standards, characterized in that the furnace has a free ladle or crucible-like manipulation space —4—, a furnace-type coking plant on hard coal or lignite —3— and in the rest an inclined blow mold level with inflation melting - 9— receives. This makes it possible to combine a bright red coke or other suitable fuel with the reducing material in such a way that a so-called shock reduction takes place in the event of a sudden temperature transition from <800 to 1200 ° C and melting> 1200 ° C or from ~ 1000 to 1600 ° C = finds, which prevents the undesired formation of iron carbide due to the special temperature curve and the short reaction time, which causes the increased carbon in the raw iron in the traditional blast furnace. Furthermore, for a complete fresh process, the preferably traditional LD process is carried out either on one side of the frame or in an attached reaction chamber. In the case of a satisfactory fresh process on one side of the frame, the attached reaction chamber is used for secondary metallurgy.

2. The method according to claim 1, characterized by a shock reduction which rapidly agglomerates iron particles of indirect —1— and direct —2— iron reduction and overcomes the zone of iron carbide formation due to the higher weight.

3. The method according to claims 1 and 2, characterized by the absence of indirect —1— free iron, so that in the shock reduction of the direct reduction —2— there is less the possibility of undesired iron carbide formation. The shock reduction results in a short direct reaction time, which prevents iron carbide formation.

4. The method according to claim 1 to 3, characterized by a shock reduction, the smaller amount of light-glowing coke or other suitable reducing agent only for iron reduction and a fuel gas is used to generate the heat of fusion. The lower amount of combustion carbon prevents the possibility of undesired iron carbide formation.

5. The method according to claim 1 to 4, characterized by the process of a downward-acting bath flow in the area of the shock reduction, which causes the iron particles to leave the zone of the iron carbide charge quickly.

6. The method according to claim 1 to 5, characterized by an order of a magnetic field —12— in the vicinity of the base of the frame, which also causes a faster exit by sedimentation of the iron particles from the zone of iron carbide formation.

7. The method according to claim 1 to 6, characterized by a free —5— or closed —6— mixture of brightly glowing coke and reducing material in the manipulation space -4 to select a stronger prevention of iron carbide formation.

8. The method according to claim 1, characterized by suction of the gas from the manipulation room —4— and fractionation of the CO gas for the indirect reduction —1— supplied from below in the pit.

9. The method according to claim 1 and 8, characterized by increasing the CO content in the manipulation room -4- by fractionation of the CO_ gas from the blast furnace gas, manipulation room and a the coke oven gas and subsequent CO splitting in the focal spot of the blow molds.

10. The method according to claim 1, characterized by the use of the top gas for heating the coke oven.

11. The method according to claim 1 and 10, characterized by the use of the internally generated coke oven gas as fuel gas in the manipulation room -, 4 - for melting the scrap -5 or for the melting process in the direct iron reduction.

12. The method according to claim 1 and 5, characterized by the reinforcement of the fresh process with the scrap brought into the manipulation space —4— —5— from the outside.

13. The method according to claim 1, characterized by the environmentally friendly and economical relocation of the fresh process in the blast furnace, whereby also the LD dust and the dedusting systems are eliminated, since the iron oxide dust produced in the furnace shaft is filtered and melted back due to the process.