KR20150111487A - The method for recycling by-product emitted from coal-based iron making process and equipment for hot compacting iron - Google Patents

Abstract

The present invention relates to a method for recycling byproducts containing a large amount of useable components and generated in a coal-based molten iron producing process by a form of dust or sludge for a reduced iron solidifying process and solidifying equipment. The present invention includes a movable reducing furnace reducing iron ore; a reduced iron storing tank storing the reduced iron reduced in the movable reducing furnace; a compulsive-transferring tank connected to the reduced iron storing tank through a reduced iron supply pipe and supplying the reduced iron to the solidifying equipment; the solidifying equipment solidifying the reduced iron supplied from the compulsive transferring unit; and a transferring means transferring the byproduct-solidified object generated in the molten iron producing process through a byproduct supply pipe. The byproduct supply pie supplies the byproduct-solidified object to at least one selected between the reduced iron supply pipe and the compulsive transferring tank.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recycling by-products discharged from a coal-based molten iron manufacturing process and a reduced-

The present invention relates to a method for recycling a byproduct 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, in a compacting process of reduced iron.

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 a melting furnace process in which it is melted in a melting furnace. Depending on the characteristics of each process, a certain amount of by-products are discharged.

The discharged by-products are mainly composed of useful components directly used in a molten iron manufacturing process, 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. At this time, the discharged by-product can be obtained in the form of sludge when water is used, and in the form of dust when water is not used.

However, in the recycling of the by-products recovered in the sludge form as described above, since the by-product contains moisture, its handling is not easy. In order to recycle the by-product, a pre-treatment process is required. Therefore, in order to recycle sludge by-products, it is necessary to remove water to a certain level, and a large amount of energy is consumed in this process.

On the other hand, most of the recovered by-product particles have a particle size of less than 100 탆, and therefore, when they are directly used in a molten iron manufacturing process, they are largely re-dispersed and are likely to be lost. Therefore, in order to overcome the above-mentioned problem, it is compacted and then charged into a melting furnace process for recycling.

In the case of recycling by charging into the melting furnace process, the by-products of dust form do not need to be subjected to a drying process, and in case of sludge, the byproducts of each by-product are loaded after moisture is dried. However, since such compacted by-products are low in room temperature strength and hot strength, they are differentiated in the moment of being injected into a melting furnace that is differentiated during transportation or maintained at about 1,000 ° C. Since the differentiated particles are re-dispersed by the reducing gas generated in the melting furnace and are lost to dust or sludge again, the recycling effect is reduced by half. Further, when the differentiated particles remain in the melting furnace, There arises a problem that the air gap between the particles is filled to deteriorate the gas permeability.

In order to minimize the above problems, some methods have been proposed in which a binder is used to increase the bonding force between particles, or a heat treatment is performed at a high temperature similarly to the conventional pellet manufacturing process. However, energy consumption is increased, And the recycling effect is reduced by half.

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

The present invention provides a reduced iron compacting system and a reduced iron compacting system for efficiently recycling sludge and dust by mixing sludge and dust-form by-products generated in a molten iron manufacturing process with reduced iron and compacting them together.

An embodiment of the present invention provides a reduced iron compacting plant, comprising: a fluidized-bed reactor for reducing iron ore; A reduced iron storage tank storing the reduced iron reduced in the fluidized-bed reactor; A forced feed tank connected to the reduced iron storage tank through a reduced iron supply pipe and supplying the reduced iron to the compacting facility; A compacting system for compacting the reduced iron supplied from the forced feed tank; And a transfer means for transferring the byproduct compacted material generated in the molten iron manufacturing process through the byproduct supply pipe, wherein the byproduct supply pipe is charged with at least one selected from the reduced iron supply pipe and the forced transfer bath have.

The conveying means may be a conveying means by gas flow, gravity or a mechanical device, and the conveying means may be conveying means by a carrier gas, and may include a gas compression device for supplying the carrier gas. The gas-solid separating means may be a cyclone, wherein the gas-solid separating means removes the carrier gas by gas-solid separation and supplies the by-product compacted material to the by-product supplying pipe.

Further, when the conveying means is a conveying means by a mechanical device, the mechanical device may be a bucket elevator or a conveyor belt.

The present invention also relates to a reducing iron compacting method comprising: a fluidized-bed reduction step of reducing iron ore with reduced iron by firing in a reducing furnace under a reducing atmosphere; A storage step of discharging the reduced reduced iron and storing the reduced reduced iron in a reduced iron storage tank; A supply step of supplying the stored reduced iron to a forced feed tank through a reduced iron feed pipe; And a compacting step of supplying the reduced iron to the compacting equipment to compact the compacted material so as to compact the byproduct compacted material produced in the molten iron manufacturing process into at least one of the reduced iron feed pipe and the forced feed tank to mix the reduced iron with the reduced iron Step < / RTI >

The by-product compact may be conveyed by a gas flow, gravity or mechanical transfer device.

In this case, when the by-product compacted material is transported by gas flow, the gas may be air, nitrogen gas, exhaust process flue gas, or a mixed gas thereof. The by-product compacted material may be a gas- It is then preferable to mix with reduced iron.

In addition, the by-product compact may be sludge, dust, or a mixture of sludge and dust.

In addition, the compacting can be performed by pelletizing, extrusion, or briquetting.

According to the present invention, sludge and dust, which are byproducts generated in a molten iron manufacturing process, are mixed with reduced iron and compacted to prevent regeneration of the byproduct compacted material during recycling of the byproduct. As a result, re-loss of the by-products can be prevented, and the problem of lowering the air permeability in the melting furnace can be prevented.

In addition, since the amount of the byproducts of the byproducts can be controlled in real time according to the formability during the compacting process of the reduced iron, the response to the operation can be performed quickly.

Furthermore, since the residence time of the by-product compact can be shortened in the process, the differentiation of the by-product compact can be minimized.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a reduced iron compacting step of the present invention, and is a schematic process diagram showing a position for supplying a byproduct compacted material produced in a molten iron manufacturing step during the reducing iron compacting step. Fig.
FIG. 2 is a schematic process diagram showing an example of a process of recycling the by-product compacted material produced in the molten iron manufacturing process in the reduced iron compacting process.

Hereinafter, 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. Further, the accompanying drawings may be expressed by exaggerating or reducing at least part of an example of the present invention.

In general, the by-products discharged during the molten iron manufacturing process are mainly composed of useful components directly used in the molten iron manufacturing process, such as iron ore, additives, and carbon-containing materials, and therefore, it is most preferable to recycle them in the molten iron manufacturing process. In the past, the byproducts have been compacted in the recycling of the by-products and charged to the melting furnace process. However, such compacted materials are low in room temperature strength and hot strength, are differentiated during transportation or charged into the melting furnace, Resulting in problems such as loss of dust or sludge or lowered air permeability.

The present inventors have repeatedly conducted researches for efficient recycling of by-products generated in the process of manufacturing molten iron. As a result, in the case of compacting the reduced iron by mixing the compacted sludge and the compacted material of the sludge, which are byproducts generated in the molten iron manufacturing process, The byproducts can be efficiently recycled without causing problems such as sludge loss or reduced air permeability due to re-scattering of the byproducts.

Particularly, in mixing sludge and dust with reduced iron, it is possible to improve the formability to compact the reduced iron by controlling the amount of the by-product compacted material depending on the position of the by-product, thereby minimizing the regeneration of the by-product compacted material And completed the present invention.

The by-products to be recycled in the present invention may suitably be sludge and dust generated and discharged during the manufacturing process of coal-based molten iron such as FINEX process. For example, the sludge and dust exiting the FINEX process have the components and average particle size as shown in Table 1.

Properties Sludge Dust

content
(weight%) Total Fe element 53.6 63.2 Metal Fe + Fe oxide 74.8 83.0 C element 8.4 2.1 CaO 3.9 5.1 MgO 0.7 1.4 Remainder 12.2 8.4 Average particle size (탆) 6.5 8.2 * The sludge content is about 33% by weight of the total amount of the sludge excluding the water content.
* Metals Fe and Fe oxides contain the total amount of Fe elements (Total Fe element).
* The remainder refers to a trace element compound

As can be seen from Table 1, the sludge and the dust are composed of iron oxide, char and a subsidiary material component containing a carbon component, etc., and only a level in which a carbon component and an additive are mixed in low-grade iron ore, ) Process. ≪ / RTI >

The by-products discharged from the FINEX process correspond to an average particle size of about 10 μm or less (90% or more by 30 μm or less in terms of weight ratio), and the major constituents are iron oxide and coal char and oxides of Ca and Mg, Cargo.

In addition, the by-product can be reduced in size and recycled to prevent workability and loss of by-products due to scattering during transportation. By-products discharged from the FINEX process can be made compact by the above- And does not involve a rapid physicochemical reaction even at a high temperature, so that it has an easy condition for recycling.

On the other hand, it is known that when the byproducts in the above-mentioned minute state are mixed with reduced iron, compacting due to mixing with reduced iron is not smoothly performed. Therefore, as suggested in the present invention, when mixing with reduced iron, the by-product is preferably compacted and mixed. At this time, the sludge or dust can be used alone or in combination with reduced iron, but it is more preferable to mix the sludge and dust and compact the compacted material after mixing with the reduced iron.

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 compacted material formed by compacting the by-product is also preferable as the moisture content is low, and it is particularly preferably 0 to 20% by weight.

In the present invention, in order to compact the by-product, the present invention may be carried out by mixing or molding by using a mixer, compressing by applying a mechanical force, molding by using a flask such as extrusion, And the like, and the kind thereof is not particularly limited. For example, a commonly used mixer such as an IR mixer can be used to mix the sludge and the dust, and the sludge can be easily compacted. The moisture contained in the sludge can cause the two materials to mix and aggregate.

The formed compacted material may be subjected to a drying process, a sorting process, a drying process, a sorting process, and the like, as required.

The formed byproduct compacted material can be recycled by mixing with the reduced iron during the process for compacting the reduced iron. As such, the by-products are mixed with reduced iron and compacted and charged into the melting furnace, thereby solving the secondary problem such as loss and loss of air permeability due to regeneration of by-products generated during recycling in a high temperature atmosphere.

Generally, the coal-based molten iron manufacturing process includes a fluidized-reduction process for reducing iron ore in minute state, a massification process for forming reduced iron ore as a compacted material, and a melting process for melting the massive reduced light in a melting furnace. The flow reduction process and the bulking process are schematically shown in FIG.

As can be seen from Fig. 1, the iron ore (iron ore) in the minute state is reduced by the fluidized-bed reduction reactor 110 to reduce the iron ore. The reduction process in the fluidized-bed reactor 110 is reduced and fired at a high temperature of 600 ° C or higher, and thus the reduced iron passing through the fluidized-bed reactor 110 has a temperature of about 550 to 850 ° C. Thereafter, the reduced iron reduced in the fluidized-bed reactor 110 is discharged from the fluidized-bed reactor 110 and transferred to the reduced-iron storage tank 120 through the reducing-agent discharge pipe 115.

As shown in FIG. 1, the by-product compacted material is preferably charged during the process of performing the compacting process from the reduced-iron storage tank 120. That is, the by-product compact body can be charged to the reduced-iron feed pipe 125, which is a pipe through which the reduced iron is supplied from the reduced-iron storage tank 120 to the reduced-iron forced transfer tank 130. Also, as shown in FIG. 1, the by-product compact body may be charged into the reduced-iron forced convection bath 130.

After the reducing iron is supplied to the reduced-iron forced convection tank 130 through the reduced-iron supply pipe 125 as described above, the supplied reduced iron compacting process is performed. Therefore, it can be understood that the condition of the reduced iron supplied to the reduced iron feed pipe 125 and the reduced iron forcible feed tank 130 has a close relationship with the compacted formability of the reduced iron. Therefore, it is possible to control the formability of the compacted irons by observing the properties of the compacted irons during the operation of the compacting step, that is, the degree of formability of the reduced iron, and thereby controlling the amount of the byproducts of the byproducts. Therefore, the moldability of the reduced iron can be improved.

Also, the by-product compacted material mixed with the reduced iron is minimized and then subjected to the compacting process, thereby minimizing the differentiation of the by-product compacted material, thereby further improving the formability of the reduced iron.

According to the present invention, there is a disadvantage in that the compacted body temperature of the reduced iron is not sufficiently increased. However, by controlling the loading amount of the by-product compacted material as described above, the formability of the reduced iron can be increased, .

When the by-product compacted material is mixed with the reduced iron, the transferred by-product compacted material can be directly fed to the reduced iron. At this time, the carrier gas for carrying charge is not particularly limited, and for example, air or nitrogen can be compressed and used, and gas generated or discharged during the FINEX process can be used.

Alternatively, a storage bin may be provided in the middle to temporarily store the by-product, and then a predetermined amount may be charged by gravity. Further, the by-product compacted material may be fed and charged using, for example, mechanical equipment such as a bucket elevator or a conveyor belt.

The mixture of the by-product compacted material and the reduced iron is supplied to the reduced iron forcing conveyer 130 by the above-described process and then supplied to the reduced iron compacting facility 140 to compact the reduced iron compacted material.

The compacted material thus obtained can be supplied to a molten steel making process using a recycled by-product which is finally charged into a melter-gasifier and a melting step is subsequently carried out.

The by-product compacted material to be mixed with the reduced iron can be mixed with the reduced iron at the above-mentioned position after compacting the compacted material for recycling by-products of the prior art as it is, and is not particularly limited in the present invention.

FIG. 2 shows an example of a facility for supplying and recycling a by-product compacted material obtained by using sludge and dust, which are by-products discharged from the FINEX process, into a reduced iron compacting process.

As can be seen from FIG. 2, the by-product compacted material obtained by mixing dust and sludge, which are solid products, among the by-products generated in the FINEX process is supplied to the byproduct storage tank 310 and mixed, And discharges the compacted material through it. The discharged compacted material is conveyed to the byproduct relay vessel 330 through the bucket elevator 325 and is conveyed to the byproduct conveying vessel 340 and then discharged through the rotary feeder 350, And is charged into the reduced iron compacting process through the by-product supply pipe 200 by the supplied carrier gas.

At this time, when the gas is fed together in the reducing iron compacting step, it is not preferable in the compacting step of the reduced iron, and the carrier gas is separated from the byproduct compacted material by the gas-solid separation by the cyclone 360 It is preferable that the byproduct compacted material is stored in the byproduct charging container 370 and then charged into the compacting process through the byproduct supply pipe 200 by the rotary feeder 350. [ At this time, it is more preferable to supply the byproduct compacted material through the byproduct supplying pipe 200 by gravity or a mechanical transfer device.

2 is a schematic view showing a state where the reduced iron stored in the reduced-fluid reducing furnace 110 is supplied to the forced feed tank 130 through the reduced-iron feed pipe 125, As described above, it may be supplied to the forced feed tank 130 or both of them.

Example

Hereinafter, the present invention will be described more specifically by way of examples. The following examples are illustrative of the present invention, but the present invention is not limited thereto.

Example  One

Min iron ore is reduced in a fluidized-bed reactor 110 at a temperature of about 750 ° C and then the reduced iron is discharged through a reducing furnace discharge pipe 115 and supplied to the reduced iron storage tank 120 by a pressure difference.

On the other hand, the sludge and dust having the composition shown in Table 1 generated in the FINEX molten iron manufacturing process were mixed at a weight ratio of 1: 1 and the compacted by-product compacted material was stored in the byproduct storage tank 310 as shown in FIG. 2 .

The stored by-product compacted material was discharged through the screw feeder 320 and the by-product compacted material was transferred to the by-product relay tank 330 through the bucket elevator 325.

Subsequently, the by-product compacted material is transported to the byproduct transporting tank 340 and discharged through the rotary feeder 350 to the gas supply pipe 355 at a predetermined amount. At the same time, nitrogen gas was supplied at high pressure through the gas compression unit 380.

The byproduct compacted material sent through the gas supply pipe 355 is passed through a cyclone to remove nitrogen gas and then the solid byproduct compacted material is discharged to the reducing steel pipe 351 by gravity through a byproduct supply pipe 200 connected to the reduced iron pipe, And supplied to the supply pipe 125. At this time, the charged byproduct compacted material was charged so as to be about 7% with respect to the total weight with reduced iron.

Thereafter, the mixture of reduced iron and the byproduct compacted material was pressed by means of reduced iron compacting equipment to produce compacted compacts. The hot strength of the obtained compacted material was measured, and the results are shown in Table 2.

Table 2 shows the density and hot strength of the compacted material obtained in comparison with the hot strength of compacted irons (HCI, Hot Compacted Iron) only with reduced iron.

The hot strength was measured by a drum test at a rotation speed of 30 rpm for 30 minutes at a temperature of 1000 캜 and a particle size of 2.8 mm or less which can affect the air permeability of the produced compacted material The differential fraction (%) was measured and expressed as a hot strength factor.

At this time, the differential fraction of the grain size of 2.8 mm or less before the drum test of the HCI is about 10%, and the degree of change of the hot strength can be confirmed by comparing it with the reference. It can be concluded that the larger the increase in the differential fraction is, the lower the hot strength is.

HCI Example 1 Density (g / cm3) 3.73 3.50 Differential fraction (%) 15 18

As can be seen from the above Table 2, although the compacted material obtained by the present invention contains the by-product compacted material as an impurity, it can be seen that the degree of increase of the differential fraction is not greater than that of the compacted material having the reduced iron alone. It can be seen that there is almost no reduction in hot strength.

Therefore, even if the reduced iron compact body containing the byproduct compacted material is charged into the melting furnace, the by-product can be recycled without causing the conventional problems caused by the regeneration of the by-product.

By using the above-described equipment, the compacted material produced using the sludge and dust discharged from the FINEX process can be recycled in the reduced iron compacting process.

Furthermore, by charging the byproduct compacted material immediately before compacting, it is possible to easily control the content of the byproducts according to the formability, and the recycling efficiency of the byproduct can be further improved.

110 Flow Reduction Furnace 115 Reduction furnace discharge pipe
120 Reduction iron storage tank 125 Reduction iron supply pipe
130 Reduction iron Forced feeder 140 Reduction iron compacting plant
200 Byproduct supply piping 310 Byproduct storage tank
320 Screw Feeder 325 Bucket Elevator
330 Byproduct Relay Joe 340 Byproduct transportation
350 Rotary feeder 355 Gas supply line
360 Cyclone 370 byproducts bins
380 gas compression device

Claims (12)

A fluidized-bed reactor for reducing iron ore;
A reduced iron storage tank storing the reduced iron reduced in the fluidized-bed reactor;
A forced feed tank connected to the reduced iron storage tank through a reduced iron supply pipe and supplying the reduced iron to the compacting facility;
A compacting system for compacting the reduced iron supplied from the forced feed tank; And
A conveying means for conveying the by-product compacted material occurring in the molten iron manufacturing process through the byproduct supplying pipe
Wherein the byproduct material piping is charged into at least one selected from the reduced iron feed pipe and the forced feed tank.
The reduced-iron compacting system according to claim 1, wherein the conveying means is a conveying means by means of a gas, gravity or a mechanical device.
The reduced-iron compacting system according to claim 1, wherein the conveying means is a conveying means with a carrier gas, and a gas compression device for supplying the carrier gas.
4. The reduced-iron compacting system according to claim 3, further comprising a gas-solid separating means for removing the carrier gas by gas-solid separation and supplying the by-product compacted material to the by-product supply pipe.
The reduced-iron compacting system according to claim 4, wherein the gas-solid separation means is a cyclone.
The reduced-iron compacting system according to claim 1, wherein the conveying means is conveying means by a mechanical device and is a bucket elevator or a conveyor belt.
A fluidized-bed reduction step of reducing iron ore with reduced iron by firing in a reducing furnace under a reducing atmosphere;
A storage step of discharging the reduced reduced iron and storing the reduced reduced iron in a reduced iron storage tank;
A supply step of supplying the stored reduced iron to a forced feed tank through a reduced iron feed pipe; And
A compacting step in which the supplied reduced iron is supplied to a compacting plant to be compacted
Further comprising a mixing step of charging the byproduct compacted material produced in the molten iron manufacturing process into at least one of the reduced iron supply pipe and the forced transfer bath and mixing the reduced compacted iron with the reduced iron.
8. The method of claim 7, wherein the by-product compact is conveyed by gas flow, gravity or mechanical transport means.
8. The method of claim 7, wherein the by-product compacted material is conveyed by a gas flow, wherein the gas is air, nitrogen gas, a molten iron manufacturing process exhaust gas, or a mixture thereof.
10. The reduced iron compacting method according to claim 9, wherein the by-product compacted material is removed by gas-solid separation and then mixed with reduced iron.
The method according to claim 7, wherein the by-product compact is a mixture of sludge, dust or sludge and dust.
8. The method according to claim 7, wherein the compacting is carried out by pelletizing, extrusion or briquetting.

Images