KR102045597B1 - 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 and a compaction facility for recycling by-products containing a large amount of useful components generated in the form of dust or sludge in a coal-based molten iron manufacturing process in the compaction production process of reduced iron, a flow reduction furnace for reducing iron ore; A reduced iron storage tank for storing reduced iron reduced in the flow reduction furnace; A forced transfer tank connected to the reduced iron storage tank through a reduced iron supply pipe and supplying reduced iron to a compaction facility; A compaction facility for compacting the reduced iron supplied from the forced transfer tank; And transfer means for transferring the by-product compacted material generated in the molten iron manufacturing process through a by-product supply pipe, wherein the by-product supply pipe is to supply the by-product compacted material to at least one selected from the reduced iron supply pipe and a forced transfer tank. Provided is a reduced iron compaction plant and a compaction method accordingly.

Description

Recycling method of by-products from coal-based molten iron manufacturing process and reduced iron compaction equipment {THE METHOD FOR RECYCLING BY-PRODUCT EMITTED FROM COAL-BASED IRON MAKING PROCESS AND EQUIPMENT FOR HOT COMPACTING IRON}

The present invention relates to a method for recycling by-products containing a large amount of useful components generated in the form of dust or sludge in a coal-based molten iron manufacturing process.

FINEX molten iron manufacturing equipment during the coal-based molten iron manufacturing process is equipped with a flow reduction process for reducing the iron ore in the powder state, a compaction process for the reduced iron ore into a bulk state, and a coal packed layer and compacted reduced ore It consists of a melting furnace process that receives and melts it in the melting furnace, and a certain amount of by-products are discharged according to the characteristics of each process.

Since the by-products are mainly composed of useful components used directly in the molten iron manufacturing process, such as iron ore, secondary raw materials, carbon-containing materials, it is advantageous from the economic point of recycling in the molten iron manufacturing process. In this case, the discharge by-product can be obtained in the form of sludge when water is used, and is recovered in the form of dust when water is not used.

However, in recycling the by-products recovered in the form of sludge as described above, since the by-products contain water, their handling is not easy, and in order to recycle the by-products, a pre-treatment process must be performed. 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, since most of the recovered by-product particles are extremely fine powder of 100 μm or less, when they are used directly in the molten iron manufacturing process, they are most likely to be scattered and lost. Therefore, in order to overcome the above-mentioned problems, it is compacted and charged into a melting furnace process and recycled.

In the charging and recycling of the furnace, by-products in the form of dust do not need to go through the drying process, and in the case of sludge, the by-products are compacted and charged after drying the water. However, such compacted by-products are low in room temperature strength and hot strength, so they are differentiated again when they are differentiated during transport or charged into a melting furnace maintained at about 1,000 ° C. The differentiated particles are halved again by the reducing gas generated in the melting furnace and are lost again to dust or sludge, and thus the recycling effect is halved. In addition, when the differentiated particles remain in the melting furnace, they have a large particle size. The problem arises that the air gap between the particles is filled up and the air permeability is deteriorated.

In order to minimize the above problems, in some cases, a method of using a binder to increase the bonding strength between particles or heat-treating at a high temperature similarly to a conventional pellet manufacturing process is proposed, but energy consumption is increased and manufacturing cost is increased. Increasingly, a problem arises in that the recycling effect is halved.

Due to the above problems, the recycling of by-products is limited in the FINEX molten iron manufacturing equipment, and the recovered by-products are mostly provided to the cement factory for free recycling or landfill. Therefore, in order to recycle by-products, it is necessary to minimize energy consumption, and when it is agglomerated, technology development should be made in a way to suppress regeneration.

The present invention is to provide a reduced iron compaction facility and reduced iron compaction method for efficiently recycling sludge and dust by mixing the sludge and dust by-products generated in the molten iron manufacturing process with reduced iron and agglomerated them together.

One embodiment of the present invention is to provide a reduced iron compaction equipment, a flow reduction furnace for reducing iron ore; A reduced iron storage tank for storing reduced iron reduced in the flow reduction furnace; A forced transfer tank connected to the reduced iron storage tank through a reduced iron supply pipe and supplying reduced iron to a compaction facility; A compaction facility for compacting the reduced iron supplied from the forced transfer tank; And transfer means for transferring the by-product compacted material generated in the molten iron manufacturing process through a by-product supply pipe, wherein the by-product supply pipe may be charged into at least one selected from the reduced iron supply pipe and a forced transfer tank. have.

The conveying means may be a gas flow, gravity or a conveying means by a mechanical device, the conveying means is a conveying means by a carrier gas, may include a gas compression device for supplying the carrier gas. At this time, the gas-solid separation means further comprises a gas-solid separation means for removing the carrier gas and supply the by-product compacted material to the by-product supply pipe, the gas-solid separation means may be a cyclone.

In addition, 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 reduced iron compaction method, comprising: a flow reduction step of reducing iron ore to reduced iron by firing in a reduction furnace under a reducing atmosphere; A storage step of discharging the reduced reduced iron and storing it in a reduced iron storage tank; Supplying the stored reduced iron to a forced transfer tank through a reduced iron supply pipe; And an agglomeration step of supplying the supplied reduced iron to an agglomeration facility to agglomerate, wherein a by-product agglomerate generated in a molten iron manufacturing process is charged into at least one of the reduced iron supply pipe and a forced transfer tank, and mixed with the reduced iron. It may further comprise a step.

The by-product compacts may be transported by gas flow, gravity or mechanical transport.

In this case, when the by-product compacted material is transferred by a gas flow, the gas may be air, nitrogen gas, molten iron manufacturing exhaust gas or a mixture thereof, and the by-product compacted material may be removed by gas-solid separation. It is preferable to mix with reduced iron later.

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

In addition, the compaction may be performed by pelletizing, extrusion or briquetting.

According to the present invention, by mixing and compacting sludge and dust, which are by-products generated in a molten iron, with reduced iron, it is possible to prevent re-differentiation of by-product compacts during recycling of by-products. For this reason, re-loss of a by-product can be prevented and the problem of air permeability deterioration in a melting furnace can be prevented.

In addition, since the supply amount of the by-product compacted material can be adjusted in real time according to the formability during the compaction process of reduced iron, it is possible to quickly perform an operation response.

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

1 is a view schematically showing a reduced iron compaction process of the present invention, a schematic process diagram showing a position for supplying the by-product compacts generated in the molten iron manufacturing process during the reduced iron compaction process.
Figure 2 is a schematic process diagram showing an example of a process for recycling the by-product compacted material generated in the molten iron manufacturing process in the reduced iron compaction process.

Hereinafter, with reference to the accompanying drawings will be described the present invention. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. In addition, the accompanying drawings may be expressed by at least partially exaggerating or reducing the example of the present invention.

In general, the by-products emitted during the molten iron manufacturing process is mainly composed of useful components used directly in the molten iron manufacturing process, such as iron ore, secondary raw materials, carbon-containing materials, it is most preferable to recycle in the molten iron manufacturing process. Thus, in the conventional recycling of the by-products by compacting the by-products and charged in the melting furnace process, these compacted materials are low in room temperature strength and hot strength, they are differentiated during transfer or recharged at the moment of charging into the melting furnace, re-scattered It caused a problem such as loss of dust or sludge or lowering of air permeability.

Therefore, the present inventors have conducted a study for the efficient recycling of by-products generated in the molten iron manufacturing process, by-products in the case of aggregating reduced iron by mixing a compacted product of sludge and dust, which are by-products generated in the molten iron manufacturing process, with reduced iron It was found that by-products can be recycled efficiently without causing problems such as sludge loss or lowering of aeration due to re-scattering.

In particular, in mixing sludge and dust with reduced iron, the moldability of compacting reduced iron can be improved by adjusting the input amount of by-product compacted material according to the input position of the by-product, thereby minimizing re-differentiation of the by-product compacted material. The present invention was completed.

By-products recycled in the present invention may be suitably used sludge and dust generated during the coal-based molten iron manufacturing process, such as Finex (FINEX) process. For example, the sludges and dusts discharged from the Finex process have components and average particle sizes 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 Balance 12.2 8.4 Average particle size (㎛) 6.5 8.2 * The sludge content is the content of solids, excluding water of about 33% by weight of the total sludge.
* Metal Fe and Fe oxide are concepts that include the total amount of Fe element (Total Fe element).
* Remainder means a compound of trace element

As can be seen from Table 1, the sludge and the dust is composed of iron oxide, carbon-containing char and secondary raw materials, etc., and is only a level in which carbon components and secondary raw materials are mixed in low-grade iron ores, and Finex (FINEX) ) Have enough useful ingredients to reuse in process.

In addition, the by-products discharged from the Finex process corresponds to an average particle size of about 10㎛ or less (90% or more in weight ratio 30㎛ or less), the main components are iron oxides and coal char and oxides or carbonic acid of Ca and Mg It consists of cargo.

In addition, the by-products can be agglomerated and recycled to prevent deterioration of workability or loss of by-products due to scattering, etc., during transportation. It is suitable for recycling and has a condition that is easy to recycle since it does not involve a rapid physicochemical reaction even at high temperatures.

On the other hand, when the mixed by-products in the ultrafine state as described above is used to reduce iron, it is known that agglomeration due to mixing with reduced iron is not performed smoothly. Therefore, in the mixing with the reduced iron as proposed in the present invention, it is preferable to harden and mix the by-products. In this case, the sludge or dust may be compacted alone to be used in combination with reduced iron, but it is more preferable to use the mixed compact with reduced iron after mixing and compacting the sludge and dust.

In general, in the case of sludge, since the moisture content is approximately 40% by weight or less, when mixing the same amount with the dust having little moisture content, the total moisture content is 20% or less, which is preferable for recycling. Therefore, compacted products formed by compaction of by-products are also preferred as the water content is smaller, and particularly preferably 0 to 20% by weight.

In the compaction of the by-products in the present invention, in the present invention, a method of mixing or molding by using a mixer, pressing by mechanical force, or molding using a mold such as extrusion, or rotating inclined pans or drums The method of aggregating and using can be used, The kind is not specifically limited. For example, the sludge and the dust may be mixed and used simply by using a commonly used mixer such as an air mixer, and due to the moisture contained in the sludge, the two materials may be mixed and agglomerated and compacted.

The formed compacted body may be performed by selecting a drying process, a screening process or a drying process and a screening process as necessary.

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

Generally, the coal-based molten iron manufacturing process includes a flow reduction process for reducing iron ore in a powder state, agglomeration process for forming reduced iron ore into compacted material, and a melting process for melting the compacted reduced ore in a melting furnace. Of these, the flow reduction process and the block formation process are schematically shown in FIG.

As can be seen from FIG. 1, the iron ore (iron ore) in the powdered state is reduced by the flow reduction furnace 110 to reduce the iron ore. The reduction process in the flow reduction furnace 110 is reduced and calcined at a high temperature of 600 ° C or higher, and thus, the reduced iron passing through the flow reduction furnace 110 has a temperature of about 550 to 850 ° C. Thereafter, the reduced iron reduced in the flow reduction furnace 110 is discharged from the flow reduction furnace 110 is transferred to the reduced iron storage tank 120 through the reduction furnace discharge pipe 115.

As shown in FIG. 1, the by-product compacted material is preferably charged in a process in which the compacted process is performed from the reduced iron storage tank 120. That is, the by-product compacted material may be charged into the reduced iron supply pipe 125, which is a pipe supplied with reduced iron from the reduced iron storage tank 120 to the reduced iron forced transport tank 130. In addition, as shown in FIG. 1, the by-product compacted material may be charged into the reduced iron forced transport tank 130.

As described above, after being supplied to the reduced iron forced transport tank 130 through the reduced iron supply pipe 125, a compaction process of the supplied reduced iron is performed. Therefore, it can be seen that the condition of the reduced iron supplied to the reduced iron supply pipe 125 and the reduced iron forced transfer tank 130 has a close effect on the compactability of the reduced iron. Therefore, the formability of the compacted material can be controlled by observing the properties of the compacted material, that is, the formability of reduced iron during the operation of the compacting process, and thereby adjusting the supply amount of the by-product compacted material, and according to the operation state. It can respond quickly, and therefore the moldability of reduced iron can be improved.

In addition, the by-product compacted material mixed with the reduced iron may minimize the differentiation of the by-product compacted material by performing the compacting process after a minimum process, thereby improving the formability of the reduced iron.

According to the present invention has the disadvantage that the compacted iron compact temperature is not sufficiently increased, but by controlling the amount of by-product compacted material as described above can improve the formability of the reduced iron, the problem caused by the low temperature will be offset Can be.

In mixing the by-product compacted material with reduced iron, the transported by-product compacted material may be directly charged to the reduced iron. In this case, the carrier gas for charging the pneumatic charge is not particularly limited, and for example, air or nitrogen may be compressed and used, and a gas generated or discharged during the Finex process may be used.

In addition, a storage bin may be installed in the middle to temporarily store the by-products, and then a method of charging a certain amount of gravity may be used. Further, for example, by-product compacts may be transferred and charged using mechanical equipment such as a bucket elevator or a conveyor belt.

The reduced iron compacted material may be obtained by supplying a mixture of the by-product compacted material and the reduced iron to the reduced iron forced transfer tank 130 and supplying the compacted iron compacted equipment 140 by the above-described process.

The compacted product thus obtained can be finally charged into a melt gasifier and provided to a molten iron manufacturing process using recycled by-products where the melting step is subsequently performed.

The by-product compacted material mixed with the reduced iron may be mixed with the reduced iron at a position as described above after being compacted by utilizing a conventional compacted equipment for recycling the by-product, and is not particularly limited in the present invention.

Figure 2 shows an example of a facility for supplying by-product compacted material obtained by using the by-product sludge and dust discharged from the Finex process to the reduced iron compaction process.

As can be seen from Figure 2, by-products compacted by mixing the solid product dust and sludge of the by-products generated in the Finex process supplied to the by-product storage tank 310 to mix, and then screw feeder 320 Exhale the compacted material through. The discharged compacted material is transferred to the by-product relay tank 330 through the bucket elevator 325, and transferred to the by-product transport tank 340, and then discharged through the rotary feeder 350 from the gas compressor 380. The carrier gas supplied is charged into the reduced iron compaction process through the by-product supply pipe 200.

In this case, when the gas is supplied together in charging the reduced iron agglomeration step, it is not preferable in the agglomeration step of the reduced iron. The carrier gas is separated from the by-product agglomerate by gas-solid separation by the cyclone 360. After removal by removing the by-product compacted material in the by-product charging tank 370 it is preferably loaded into the compaction process through the by-product supply pipe 200 by the rotary feeder 350. At this time, the charging of the by-product compacted material through the by-product supply pipe 200 is more preferably supplied by gravity or a mechanical transfer device.

2 is a by-product compacted material in the reduced iron supply pipe 125 in the process of reducing iron is reduced in the flow reduction furnace 110 and stored in the reduced iron storage tank 120 is provided to the forced transfer tank 130 through the reduced iron supply pipe (125). Although one example of a process for supplying is shown, as described above, it may be supplied to the forced transfer tank 130, may be supplied to both.

Example

Hereinafter, an Example is given and this invention is demonstrated more concretely. The following examples are examples for explaining the present invention by way of example, and the present invention is not limited thereto.

Example  One

After the reduced iron ore was reduced in the flow reduction furnace 110 at a temperature of about 750 ° C, the reduced reduced iron was discharged through the reduction 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 a composition as shown in Table 1 in the FINEX molten iron manufacturing process was mixed in a weight ratio of 1: 1 and the compacted by-product compacted material was stored in the by-product storage tank 310 as shown in FIG. .

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 was transferred to the by-product feed tank 340 and then discharged to the gas supply pipe 355 through a rotary feeder 350 in a predetermined amount. At the same time, nitrogen gas was supplied at high pressure through the gas compressor 380.

After removing the nitrogen gas by passing the by-product agglomerate conveyed through the gas supply pipe 355 through a cyclone, the by-product agglomerate of solid phase is reduced by gravity through a by-product supply pipe 200 connected to a reduced iron supply pipe. Charged into the feed pipe (125). At this time, the charged by-product compacted material was charged to about 7% of the total weight with the reduced iron.

Thereafter, compacted material was prepared by applying a mixture of reduced iron and by-product compacted material by using a reduced iron compacted equipment. The hot strength of the obtained compact was measured, and the result is shown in Table 2.

The density and hot strength of the obtained compacts are shown in Table 2 in comparison with the hot strength of the compacted compacts (HCI, Hot Compacted Iron).

The hot strength has a particle size of 2.8 mm or less that may affect the air permeability of the produced compacted material when the drum test is performed at a speed of 30 rpm for 30 minutes at 1000 ° C. The differential fraction (%) was measured and expressed as the hot strength factor.

At this time, the differential fraction of the particle size of 2.8 mm or less before the drum test of the HCI is about 10% level, and by comparing this, the degree of change in hot strength can be confirmed. It can be judged that the greater the increase in the differential fraction, the lower the hot strength.

HCI Example 1 Density (g / cm 3) 3.73 3.50 Differential fraction (%) 15 18

As can be seen from Table 2, although the compacted body obtained by the present invention contains the by-product compacted material as an impurity, it can be seen that the degree of fine fraction increase is not as large as that of the compacted iron alone compacted material. It can be seen that there is almost no decrease in hot strength.

Therefore, it can be seen that even if charged iron compacts containing by-product compacts are charged into the melting furnace, the by-products can be recycled without causing problems as in the prior art due to the regeneration of the by-products.

By using the above facilities, the compacted material produced using the sludge and dust discharged from the Finex process can be recycled in the reduced iron compaction process.

Furthermore, by loading the by-product compacted material just before the hardening revolution, it is possible to easily control the content of the by-product according to the moldability, it is possible to further increase the recycling efficiency of the by-product.

110 Flow reduction furnace 115 Reduction furnace discharge pipe
120 Reduced Iron Storage Tank 125 Reduced Iron Supply Pipe
130 Reduced iron transfer tank 140 Reduced iron hardening facility
200 By-Product Supply Pipe 310 By-Product Storage Tank
320 screw feeder 325 bucket elevator
330 By-products Jungjo-jo 340 By-products
350 Rotary feeder 355 Gas supply piping
360 cyclone 370 by-product charge tank
380 gas compressor

Claims (11)

delete delete delete delete delete delete A flow reduction step of reducing the iron ore to reduced iron by calcining in a reduction furnace under a reducing atmosphere;
A storage step of discharging the reduced reduced iron and storing it in a reduced iron storage tank;
Supplying the stored reduced iron to a forced transfer tank through a reduced iron supply pipe; And
A compaction step of supplying the supplied reduced iron to the compaction facility to compact
And a mixing step of charging the at least one by-product compacted material of the sludge and dust generated in the molten iron manufacturing process into at least one of the reduced iron supply pipe and the forced transfer tank and mixing the reduced iron with the reduced iron. Phosphorus reduced iron compaction method.
8. The method of claim 7, wherein the byproduct compact is conveyed by gas flow, gravity, or mechanical conveying means.
The method of claim 7, wherein the by-product compacted material is transferred by a gas flow, wherein the gas is air, nitrogen gas, molten iron manufacturing process exhaust gas, or a mixture thereof.
10. The method of claim 9, wherein the byproduct compact is mixed with reduced iron after removing the gas by gas-solid separation.
8. The method of claim 7, wherein said compaction step is performed by pelletizing, extrusion or briquetting.

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