DE2422641C2 - Process for shaft furnace ore reduction - Google Patents

Description

The invention relates to a method for shaft furnace ore reduction in the preamble of the claim 1 designated Art.

A method of this type is known from DE-OS 077 such that hot, reducing gases are blown into the reserve zone, while the non-oxidizing gases in the form of reducing agents at a temperature between 1700 ^° C. and 2400 ^° C. approximately at the level of the main blow molds are to be blown. Accordingly, the latter gases participate in the reduction.

The person skilled in the art is basically familiar with the generation of hot gases, for example according to the BE-PS 67 879, according to which hot reducing gases should be blown into the blast furnace instead of the hot blast, they are heated by heat exchangers or electrically, in particular also by plasma torches.

According to DE-OS 21 09 316, the operation of a blast furnace with pre-reduced pellets was also known. The pellets are preheated by hot gas before they enter the melting zone, which is essentially consists of nitrogen or carbon monoxide. It is essential to inject the gas with a Temperature above that in the area of the Einblasstdle of the blast furnace is the prevailing temperature, so that the pellets or, if necessary, the To heat up scrap.

The above-mentioned, known processes serve to reduce the consumption of coke in the production of pig iron. The reaction processes summarized below are decisive for this:

The reduction of iron oxides in the blast furnace is mainly effected either directly (FeO + C = Fe + CO) or indirectly (Fe ₁ O ^. + YCO = XFe + yCO ₂ )

In conventionally operating blast furnaces, coke plays a multiple role, which are briefly described as follows leaves:

a) The wind reacts very quickly with the coke on the shaped trunk according to C + V ₂ O ₂ = CO. The hot gas generated on the mold trunk is used to perform thermal tasks, part of which is used for the reduction process. The amount of coke burned in this way is of the order of 60 to 70% of the coke consumption.

b) The rising hot gas is not sufficient to completely remove the oxides contained in the batch burn. It follows from this that some of these oxides are reduced directly by the coking carbon will. This amount of coke, which is additionally required in the classic process, is called "direct reduction coke" designated

c) For iron, which forms stable carbides, one is used small amount of coke used to carburize the molten metal. The by this carburization The amount of coke consumed is of the order of 10% of the coke consumption.

Generally speaking, the total coke consumption in a blast furnace is the sum of the partial consumption quantities the three processes described above.

In addition, the coke plays an important mechanical role in the formation of a solid support Experts called "coke lattice", which controls the movement of gases and liquid media (slag, Pig iron) in countercurrent. In principle, this function takes place without the consumption of coke.

The method that has become known initially means that additional liquid or gaseous ones are used Hydrocarbons the coke consumption has been reduced by 5 to 20%. By increasing the Wind temperature or the oxygen content of the wind, the savings could be increased up to 25%. Yet further increases in the order of magnitude of 30 to 45% in coke consumption could be achieved through the introduction process described, forming the starting point of the present invention.

Proceeding from this, the object of the invention is to further reduce the consumption of coke.

This problem is solved by the proposal according to the characterizing part of the patent claim 1, for which the dependent claims 2 to 5 provide advantageous further developments.

Accordingly, according to the invention, a method with double injection is achieved, by means of which practically any coke combustion on the mold trunks is suppressed, so that the need for direct reduction coke is eliminated and the coke contained in the charge is limited to exactly the amount required for the meta bath to cool up as well as for the formation of the coke lattice is required.
The high temperatures of the rack level

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■ {and preferably in the plane of the main blow molds • 0 I can be injected with any known gas I means, for example with a torch burner, one 5 electric arc torch or preferably a I nem arc plasma torch. 5 1 According to the invention, the \ bubbled non-oxidizing gas from a chemically inert \ th gas, preferably nitrogen. Ϊ Here, chemically inert gas means an industrial one I generated gas that does not contain any chemically active substances other than 10 > Contains contaminants \ The ones to be blown into the shaft furnace are called \ duction gases are appropriately those gases that jj mainly contain CO and H2, for example s recovery gases from a partial oxidation or a 15 'a catalytic cracking of hydrocarbon, for I example in the presence of steam, or a 1 pyrolysis. 1 ^2o I. j * 30th

Claims (5)

Patent claims: 1. A method for shaft furnace ore reduction, in particular of iron ores in a blast furnace, with hot, reducing gases ^{being blown into the shaft for the reduction of the charge located there and below the same non-oxidizing gases at a temperature above 1700 0} C at rack height, characterized in that, that the hot reducing gases are blown in with a temperature between 800 ⁰ C and 1200 ⁰ C at the lower end of the shaft with the stipulation of the maximum reduction of the charge, and that the non-oxidizing gas is an inert gas with a ^{temperature of up to 2500 0} C such that the metal and the slag are melted and overheated and the remaining reactions, such as the reduction of silicon, manganese and phosphorus as well as small residual amounts of the insert, take place. 2. The method according to claim 1, characterized in that the injection of the hot reducing gases at the lower end of the shaft in a below the so-called reserve zone lying level takes place 3. The method according to claims 1 or 2, characterized in that the injection of the non-oxidizing Gas takes place at rack height in the plane of the main blow molds 4. Process according to claims 1 to 3, characterized in that the high temperatures of the gas to be injected at the height of the frame with the help of a flare burner, an electric arc burner or preferably an arc plasma torch can be generated. 5. The method according to claims 1 to 4, characterized in that the blown in frame height Inert gas is nitrogen.