KR101676227B1 - The method for preparing molten iron by recycling by-product emitted from coal-based iron making process - Google Patents

Abstract

The present invention relates to a method of recycling a by-product discharged from a coal-based molten iron manufacturing process, and more particularly, to a method of recycling a by-product formed in a molten iron manufacturing process by compacting a by-product to form a by- .
By employing the recycling method of the present invention, it is possible to solve the problems such as the re-loss of the by-products and the decrease in the air permeability because regeneration does not occur during the recycling.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a molten iron by recycling by-

The present invention relates to a method for recycling a by-product containing a large amount of an oil component, which is generated in the form of dust or sludge in a coal-based molten iron manufacturing process.

The FINEX line manufacturing facility in the coal-based molten iron manufacturing process consists of a fluidized-bed reduction process for reducing iron ore in the mined state, a compacting process for making the reduced iron ore into a bulk state, and a coal- And melting it in a melting furnace, and a certain amount of by-product is discharged depending on the characteristics of each process.

At this time, the discharged by-products are discharged in the form of sludge when recovered using water, and in the form of dust when recovered without using water. The above-mentioned by-products are mainly composed of useful components that are directly used in the process of manufacturing molten iron, such as iron ore, additives, and carbon-containing materials, and thus it is advantageous in terms of economics to be recycled in the molten iron manufacturing process.

However, the above-mentioned by-products have the following problems in recycling. In the case of sludge, it contains moisture, which is not easy to handle and can not be recycled without a pre-treatment process. Therefore, water must be removed to a certain level in order to be recycled, and a large amount of energy is consumed in this process.

In addition, since most of dust and sludge have a particle size of less than 100 탆, most of them are likely to be re-dispersed and lost when used directly in the process. Therefore, in order to overcome the above problems, the sludge is dried, and in the case of dust, the drying process is omitted, the sludge is compacted, and then the slurry is charged to the melting furnace process for recycling.

However, since the compacted by-products are low in room temperature strength and hot strength, they are differentiated at the moment when they are charged into a melting furnace which is differentiated during transportation or maintained at about 1,000 ° C. In this case, the differentiated particles are re-dispersed by the reducing gas generated in the melting furnace, and are lost again as dust or sludge, so that the recycling effect is halved. When the particles remain in the melting furnace, And the gas permeability is deteriorated.

In order to minimize the above problems, a method of using binder or heat treatment at a high temperature similar to the conventional pellet manufacturing process has been proposed in order to increase the bonding force between particles, but the energy consumption is increased and the manufacturing cost is increased There is a problem that the recycling effect is reduced by half.

Due to the above-mentioned problems, the recycling of by-products is limited in FINEX hot-wire manufacturing facilities, and most of them are provided free of charge to cement plants and recycled or buried as iron sources. Therefore, technology development should be carried out in the direction of minimizing energy consumption and suppressing regeneration when becoming compact.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a sludge- And the problem of re-losing the by-products during the recycling process, thereby deteriorating the air permeability.

According to an embodiment of the present invention, there is provided a method of manufacturing a molten iron manufacturing method, comprising: forming a by-product by compacting a by- And a step of compacting the pellet by mixing it with reduced iron, thereby providing a method for recycling by-products of the molten iron manufacturing process.

The by-product may be sludge, dust, or a mixture of sludge and dust.

The mixture of the sludge and the dust may be a mixture of the sludge and the dust at the same weight ratio.

The pellets may have a particle size of greater than 0 and less than or equal to 10 mm.

The water content of the pellets may be 0 to 20 wt%.

The step of forming the pellets may be performed by mixing the by-products with a mixer, molding the mixture using a flask, or rotating the mixture using a slanting pan or a drum, thereby aggregating the mixture into a spherical shape.

The step of forming the pellet may be performed by further adding at least one selected from the group consisting of water, a binder and an additive.

The binder may be an inorganic binder comprising bentonite or water glass, or an organic binder containing starch or molasses.

The additive may be a waste containing coal or carbon components to promote reduction of the iron oxide contained in the by-product, or a waste containing an ore or iron component to increase the content of the iron component.

The additive may be limestone or dolomite.

The pellets may be further subjected to a drying process, a selection process or a drying process and a selection process before being mixed with the reduced iron.

The reduced iron may be at a temperature of 550 to 850 캜.

The pellets and the reduced iron may be mixed in a weight ratio of more than 0:10 to less than 9: 1.

According to another embodiment of the present invention, a mixture of the obtained compacted pellets and reduced iron is charged into a melter-gasifier to provide a molten iron production process using recycled by-products.

Disclosure of the Invention The present invention makes it possible to solve the problems such as re-loss of by-products and deterioration of air permeability since regeneration does not occur during recycling by mixing sludge and dust, which are byproducts generated in the process of manufacturing molten iron, into compacts together with reduced iron.

Fig. 1 schematically shows an example of the recycling process of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

According to one embodiment of the present invention, there is provided a method for recycling a by-product discharged from a coal-based molten iron manufacturing process, the method comprising the steps of: forming a pellet by compacting by-products generated in a molten iron manufacturing process; And mixing and compacting.

The average particle size of sludge and dust discharged from the FINEX process is about 10 μm or less, and 90% or more is equivalent to 30 μm or less in terms of weight ratio. The major constituents are iron oxide, coal char, Ca and Mg oxide Or carbonates, it is good for compacting and has a condition that is easy to recycle because it does not accompanied rapid physical and chemical reaction even at a high temperature.

Therefore, in the recycling method of the present invention, the by-product may be used alone or in combination with sludge or dust, and it is preferable for the by-product to be used in combination for recycling.

Generally, in the case of sludge, since the moisture content is approximately 40% by weight or less, when the same amount as that of dust having little moisture content is mixed, the total moisture content becomes less than 20%, which is preferable for recycling. Therefore, the water content of the pellet formed by compacting the by-product is also preferably as small as possible, more preferably from 0 to 20% by weight.

Table 1 below shows the composition and average particle size of the sludge and dust discharged from the FINEX process. The sludge and dust are composed of iron oxide, char and additive components containing carbon components, and the like. Therefore, when the sludge and the dust are mixed at the same weight ratio, the total iron content is maintained at about 55% by weight or more, and the carbon content is also maintained at about 4%, and the carbon content and the subsidiary material are mixed in the low- Which is sufficient to be reused in the FINEX process.

Properties Sludge Dust Total Fe element (% by weight) 53.6 63.2 Metal Fe + Fe oxide (% by weight) 74.8 83.0 C element (% by weight) 8.4 2.1 CaO (% by weight) 3.9 5.1 MgO (wt%) 0.7 1.4 Balance (% by weight) 12.2 8.4 Average particle size (탆) 6.5 8.2

(* The sludge is described by analyzing only the physical properties of the solid material from which moisture is removed in an amount of about 33% by weight based on the total amount of the sludge, and the metal Fe and Fe oxides include the total Fe element (total Fe element) , And the remainder refers to a trace element compound.)

In the present invention, when the sludge and the dust are mixed and molded using a mixer such as an IR mixer, the two substances are mixed due to the moisture contained in the sludge and are agglomerated into spherical pellets.

The size of the formed pellets may vary depending on the mixing ratio of the sludge and the dust, the moisture content, and the mixing conditions, but it is preferable that the pellets have a spherical shape with an average particle size of more than 0 and less than 10 mm.

In the present invention, the method of compacting by-products to form pellets is not limited to the method of mixing and molding by using a mixer as described above, a method of compressing by applying a mechanical force, molding by using a flask such as extrusion, And a method of agglutinating by utilizing a photo fan or a drum, and the kind thereof is not particularly limited, but it is preferable to use a mixer because it can be carried out by the simplest process.

In forming the pellets, the present invention can be carried out by further adding at least one selected from the group consisting of water, a binder and additives.

In order to facilitate the mixing and agglomeration of the water, the binder may be added in order to accelerate the reduction of the iron oxide or to increase the content of the iron component in order to improve the cohesion efficiency, the room temperature strength and the hot strength.

At this time, the binding agent may be an inorganic binder such as bentonite or water glass, or an organic binder such as starch or molasses.

In addition, the additive may be a waste containing coal or a carbon component or a waste containing an ore or an iron component to increase the content of the iron component so as to promote the reduction of the iron oxide contained in the by-product. Alternatively, additives such as limestone or dolomite may be added to the byproduct to facilitate slag formation when mixing with the reduced iron and performing the melting step.

Since the byproduct contains carbon, the reduction of the iron oxide mainly constituting the by-product in the melter-gasifier is promoted, so that even when the reduced iron having a low reduction ratio is recycled, problems such as rising fuel cost can be prevented have. However, at this time, when the waste containing coal or carbon components is further added, the reduction rate of the iron oxide can be greatly improved, which is more effective in preventing the above problems.

In addition, the present invention may or may not include the drying process, the sorting process or the drying process and the sorting process in an appropriate order depending on the situation before the formed pellets are mixed with the reduced iron. At this time, the drying process may be performed using atmospheric, hot air or high temperature flue gas containing CO ₂ .

The recycling method of the present invention includes a step of forming pellets and mixing them with reduced iron, thereby solving a secondary problem such as loss and loss of air permeability due to regeneration of by-products generated during recycling in a high temperature atmosphere.

The reduced iron mixed with the pellets may be reduced and fired at a high temperature of 600 ° C or higher, and may be at a temperature of 550 to 850 ° C. Accordingly, the pellets are mixed with the reduced iron, so that the temperature rapidly increases from room temperature to about 600 ° C. However, since the moisture content in the pellets is very low and the particle size is small, the by-products constituting the pellets have already been discharged after undergoing high- , Since the physicochemical change is hardly performed at high temperature, the thermal shock is not so large, and many kinds of differentiation do not occur.

In the present invention, the pellets and the reduced iron may be mixed in a weight ratio of more than 0:10 and less than 9: 1. In the case of reduced iron, the surface of the particles is mainly reduced to iron and maintains a high temperature state at about 600 ° C, so that there is no big problem in compacting even if mixed at the above ratio. However, a mixing ratio of pellets to reduced iron of 2: 8 by weight is most preferable for solving the above-described problems.

According to another embodiment of the present invention, there is provided a process for manufacturing molten iron using a recycled by-product in which the mixture of the compacted by-product and the reduced iron through the two steps is finally charged into the melter-gasifier and the melting step is subsequently carried out.

FIG. 1 schematically shows an example of a recycling process of the present invention. Sludge 21 and dust 31 generated in a molten iron manufacturing process are stored in a sludge storage 23 and a dust storage 33, respectively, Weight ratio, and sent to the mixing / compacting facility 51. The mixing / The sludge 21 and the dust 31 are mixed with each other to increase the coagulation efficiency of the sludge 21 and the dust 31 and to accelerate the reduction of the iron component before the compacting process is performed in the mixing / The binder 41 and the additive 42 may be additionally added.

The mixture of the sludge 21 and the dust 31 is formed into spherical pellets by the compacting process and optionally the moisture can be further removed through the drying equipment 53 and the average particle size Is returned to the mixing / compacting facility 51 via the recirculation pipe 56 if it does not meet the appropriate level or is not suitable for recycling.

The formed pellet is then sent to a storage and charging facility 57 where the ore 11 is reduced and fired at the fluidized-bed reactor 13 and sent to a reduced-iron storage tank 15 where the reduced iron is stored, .

After mixing, the mixture is sent to a reducing iron compacting unit 17 to be compacted. The fine particles generated in the compacting process can be sent to the reduced iron storage 15 through the differential recycle pipe 16. And the remainder is sent to the melter-gasifier 19 where melting takes place and is discharged to the slag 61 and charter line 62.

Hereinafter, the present invention will be described more specifically by way of specific examples. The following examples are provided to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Example

[Example]

Sludge and dust generated in a FINEX molten iron manufacturing process were mixed in an amount of the same weight ratio for about 3 minutes using an IR mixer to obtain pellets having an average particle size of 2 mm . After the pellets and the reduced iron were mixed at a weight ratio of 2: 8, the 100 g of the mixed sample was stirred at 600 DEG C at a force of 150 MPa And the compressive strength of the obtained sample was measured. The measured values were obtained by averaging a total of 10 values except an ideal value, and the results are shown in Table 2 below.

[Comparative Example]

In the examples, only the same reduced iron as used in the mixing was compacted in the same manner as in Example 1 without mixing with by-products, and the compressive strength was measured. The results are shown in Table 2 below.

sample Comparative Example Example Compressive strength (kg / cm ² )  575 682

As a result of the measurement of the compressive strength, when the compressive strength of the example in which the pellets (byproducts) and the reduced iron were mixed and compacted was compared with the compressive strength of the comparative example compacted with reduced iron alone, And that it has a value equal to or greater than that of Therefore, it was found that even if the compacted material mixed with the by-product and the reduced iron is charged in the melting furnace, there is no problem in differentiation and the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be obvious to those of ordinary skill in the art.

11: minute ore 13: fluidized-bed reactor
15: Reduced iron storage tank 16: Differential recirculation pipe
17: Reduction iron compacting facility 19: Melt gasification furnace
21: sludge 23: sludge storage tank
31: Dust 33: Dust tank
41: Binder 42: Additive
51: Mixing / compacting equipment 53: Drying equipment
55: Classification facility 56: Recirculation pipe
57: Storage and charging facility 61: Slag
62: Charter

Claims (12)

Compacting a mixture of sludge and dust, which are byproducts generated in the molten iron manufacturing process, to form a byproduct compacted product having an average particle size of 2 to 10 mm;
Mixing the by-product compacted material with reduced iron and then compacting the compacted compacted material to form compacted compacted material of a by-product compacted body and a reduced iron; And
A melting step of charging the mixed compacted material into the melter-
And recycling the by-product of the molten iron manufacturing process to produce molten iron.
The method of claim 1, wherein the mixture of sludge and dust is a mixture of sludge and dust at the same weight ratio.
delete The method of manufacturing molten iron according to claim 1, wherein the byproduct irregular body has a water content of 0 to 20 wt%.
The process of claim 1, wherein the by-product compacted material is formed by mixing the by-products with a mixer, molding the mixture using a flask, rotating the mixture using a slanting fan or a drum, A method of manufacturing molten iron by recycling process by-products.
The method of claim 1, wherein the by-product compact is formed by further adding at least one selected from the group consisting of water, a binder, and an additive to recycle molten iron by-products.
The method of manufacturing molten iron according to claim 6, wherein the binder is an inorganic binder including bentonite or water glass, or an organic binder that contains starch or molasses.
7. The method of claim 6, wherein the additive is selected from the group consisting of waste containing coal or carbon components for promoting the reduction of iron oxides contained in the by-product, or waste iron containing iron or an iron component for increasing the content of iron components A method of manufacturing molten iron by recycling process by-products.
The method of manufacturing molten iron according to claim 6, wherein the additive is limestone or dolomite.
The method of manufacturing molten iron according to claim 1, wherein the by-product compacted material is recycled as a by-product of a molten iron manufacturing process which is further subjected to a drying process, a sorting process, a drying process and a sorting process before being mixed with reduced iron.
The method for producing molten iron according to claim 1, wherein the reduced iron is recycled by-product of the molten iron manufacturing process at a temperature of 550 to 850 ° C.
The method of claim 1, wherein the byproduct irons and the reduced iron are mixed at a weight ratio of greater than 0:10 and less than or equal to 9: 1 to recycle molten iron byproducts.

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