KR102220541B1 - A manufacturing method of substitutional goods of limestone for sintering steel using shells - Google Patents

Abstract

The present invention relates to a manufacturing method of a substitute of limestone for sintering steel using waste shells such as oyster shells, and more specifically, to the manufacturing method of a substitute of limestone for sintering steel using shells, which includes the following: a process of crushing waste shells; a process of removing impurities including plastic and cone coating sand in crushed waste shells; a process of sorting the waste shells while spraying washing water from a vibrating body; and a process of dewatering shell particles whose particle size is controlled by sorting.

Description

A manufacturing method of substitutional goods of limestone for sintering steel using shells}

The present invention relates to a method of manufacturing a limestone substitute for sintering steel by using discarded shells such as oyster shells,

In more detail, the process of crushing the waste shell, the process of removing the primary impurities of the coating company, the process of removing the primary impurities of the coating company, the process of crushing the scraped shell, Limestone replacement material that can be used as a substitute for limestone for steel sintering, including the process of removing secondary impurities, the process of washing and sorting waste shells by spraying washing water from a vibrating body, and dehydrating shell particles whose particle size has been sorted. It relates to a method of manufacturing.

Conventionally, a method of manufacturing agricultural fertilizers by pulverizing shells has been mainly used, and it has been common to wash and pulverize shells, and to prepare fertilizers as they are or through massing of pellets.

In the case of the conventional fertilizer limestone manufacturing method, there is a problem that production efficiency is degraded and product uniformity is difficult to maintain because only surface deposits are removed by simple water washing or high pressure washing when washing raw shell materials.

On the other hand, in general, sintered ore is used as a raw material in the blast furnace of a steel mill, and the iron ore blending raw material used in the manufacture of the sintered ore contains powdered iron ore of about 10 mm or less, and as an auxiliary material, CaO such as limestone and quicklime having a particle size smaller than that of ordinary iron ore. It contains raw materials and _{silica stone containing SiO 2} as a main component, and solid fuels such as coke and anthracite.

These blended raw materials are removed by a certain amount from the raw material storage bin according to the blending ratio after the blending ratio is determined in consideration of the quality and composition of the sintered ore, and they are mixed in a mixer and added to a suitable amount of moisture to assemble into a particle size suitable for sintering.

Sintered ore is calcium ferrite (CaO-Fe ₂ O ₃ ), magnetite (Fe ₃ O ₄ ), hematite (Fe ₂ O ₃ ), and glassy silicate slag with weak strength. It is composed of materials. Among the sintered ores, their relative composition ratio greatly varies depending on the fuel ratio in the blended raw materials, the chemical composition of the raw materials, the raw material particle size, and the operating conditions of the sintering machine, and accordingly, the quality characteristics such as productivity and strength of the sintered ore vary greatly.

The particle size of the raw materials used when manufacturing the sintered ore is generally less than 4 to 6 mm of limestone, which is the source of CaO. Since the sintered ore is heated in a state in which ore particles containing other components are mixed, when it reaches a temperature around 1,200 ℃, the melt is _{mainly formed by the reaction of Fe 2} O _{3 and CaO components from the surface where the mixed ore particles are in contact.} Begins to be created.

In order not to weaken the strength of the sintered ore while reducing the amount of slag in the sintered ore, conventionally, there is a method of minimizing the particle size of an auxiliary material such as limestone added as a sintering material.

However, if the particle size of these limestone sub-materials is miniaturized, the strength of the sintered ore can be maintained by increasing the amount of molten material produced under the same conditions than when using relatively coarse particles. Thus, there is a problem of reducing the sintering productivity. In addition, even if the amount of slag in the sintered ore is reduced and the input fuel cost is increased, the strength maintenance effect is exhibited by increasing the melt, but it causes a problem of lowering sintering productivity due to a relatively increase in fuel cost and a decrease in high temperature ventilation during the sintering process.

If the quality of sintered products is deteriorated, it causes the following unfavorable operating effects, reprocessing of sintered ore, deterioration of the sintered ore ventilation and strength, leading to deterioration of the blast furnace operation, and an increase in the manufacturing cost of the sintering and blast furnace operation. And the sintered ore manufacturing absolutely requires strict specifications _{of limestone (CaCO 3 ).}

So far, in the sintering process of domestic steel mills, there has been no case of using shells as a substitute for limestone for sintering operations.

Korean Patent Registration 10-1008694 (Registration date January 10, 2011) Republic of Korea Patent Publication 10-1999-0000001 (Publication date January 1, 1999)

The present invention is to provide a limestone replacement material necessary for manufacturing sintered ore for blast furnace operation by using discarded shells such as oyster shells as a raw material, and steelmaking using shells including processes such as crushing, sorting, washing, and particle size control of waste shells. It is an object of the invention to provide a method of manufacturing a limestone substitute for sintering.

To achieve the above object,

The present invention comprises a first step (S10) of crushing the closed shell,

A second process (S20) of removing primary impurities from plastics and coating companies contained in the crushed waste shell,

A third step (S30) of neutralizing the closed shell that has passed through the second step,

A fourth step (S40) of removing the residual amount of secondary impurities contained in the heavy-chain waste shell,

A fifth step (S50) of adjusting the particle size by washing and sorting while spraying washing water by putting the waste shells that have passed through the fourth step into a vibrating body,

It provides a method of manufacturing a limestone substitute for sintering steel using a shell, characterized in that it comprises a sixth step (S60) of dehydrating the shell particles whose particle size has been selected and adjusted.

The method of manufacturing a limestone substitute for sintering steel using a shell according to the present invention has the following effects.

first. We propose a method for cleaning waste shells that can improve the uniformity of shell quality and production efficiency of shell powder for sintering limestone replacement, and achieve subdivision and characterization of shells.

second. Limestone substitutes based on shells, a natural resource material, can be added to the iron ore blending material to maintain the proper grain size of the sintered ore and increase the sintering speed, strength, and ventilation. This improves the sintering productivity and quality required in the blast furnace operation, thereby increasing the crude steel production of the blast furnace.

third. The limestone substitute for sintering according to the present invention does not contain elements such as K and Na harmful to steel, and improves air permeability of the sintered layer, promotes bonding and crystallization during the sintering process, thereby reducing the sintering time, thereby reducing fuel costs. Have.

fourth. Since the discarded shells can be used to replace the limestone component, there is an effect of securing depleted resources and improving the natural environment.

1 is a process flow chart according to the manufacturing method of a limestone substitute for sintering steel using the shell of the present invention.
Figure 2 is a photograph showing the shell crushing process during the manufacturing process of the limestone substitute for sintering steel using the shell of the present invention.
3 is a view illustrating a relationship between the frequency of the vibrating body and the angle of the rotating body when washing is performed during the manufacturing process of the limestone substitute for sintering steel using the shell of the present invention.

Hereinafter, a detailed technical configuration for a method of manufacturing a limestone substitute for sintering steel using the shell of the present invention will be described with reference to the drawings.

As shown in Figure 1,

The method of manufacturing a limestone substitute for sintering steel using a shell according to the present invention

A first step (S10) of crushing the lung shell,

A second process (S20) of removing primary impurities from plastics and coating companies contained in the crushed waste shell,

A third step (S30) of neutralizing the closed shell that has passed through the second step,

A fourth step (S40) of removing the residual amount of secondary impurities contained in the heavy-chain waste shell,

A fifth step (S50) of adjusting the particle size by washing and sorting while spraying washing water by putting the waste shells that have passed through the fourth step into a vibrating body,

It includes a sixth step (S60) of dehydrating the shell particles whose particle size has been selected and adjusted.

The shell applied to the present invention refers to the shell of a clam, and is a form in which the stratum corneum layer of the organic component and the stratum corneum layer of the inorganic component are mixed with each other. As the shell, the shells of tribes (clam) including oysters, clams, eardrums, lilies, clams, jejunom, clams, etc. and gastropods including conch, abalone, and the like may be used.

In order to use the shell as a raw material for the sintering reinforcing agent, the shell must be separated, crushed, washed, and dried to have a certain particle size and shape.

The shell is mainly composed of calcium carbonate. For example, the content (unit: wt%) of the main components constituting the shell is shown in Table 1 below.

CaCO ₃ SiO ₂ P ₂ O ₅ Na ₂ O MgO B ₂ O ₃ Mn Zn Cu Organic matter 95.0 0.1 0.14 0.05 0.17 0.003 0.013 0.016 0.001 4.0

As shown in Table 1, the shell contains calcium carbonate as a main component, and _{contains organic matter and trace amounts of silica sand, P 2} O ₅ , and the like.

These shells _{inhibit the bonding of Fe 2} O ₃ and SiO ₂ and promote the formation of calcium ferrite during sintering due to the combination of _{CaO and SiO 2} , which serves as the bonding role of the sintered ore, and makes the structure of the sintered ore dense. It improves the strength of the sintered ore.

As described above, the present invention has the effect of securing depleted resources and improving the natural environment by replacing the conventional limestone component using the discarded shell.

Typically, iron ore blending raw materials used in the manufacture of sintered ore are made of powdered iron ore of about 10 mm or less as the main raw material, and limestone, quicklime, silica, and solid raw materials such as coke or anthracite are used as auxiliary raw materials.

For example, the iron ore blending material is composed of 75.0 wt% of iron ore, 1.0 wt% of silica sand, 10.0 wt% of limestone, 1.5 wt% of quicklime, 5.0 wt% of solid fuel mixed with coke and anthracite at the same weight ratio, and 7.5 wt% of moisture .

As described above, various shells of gastropods including tribes (shells) including oysters, clams, eardrums, and lilies among mollusks and gastropods such as conch and abalone can be used, but in the present invention, oysters A method of manufacturing limestone for sintering steel will be described using shells as raw materials.

[The first step of crushing the closed shell (S10)]

The structural properties of the shell tissue also affect the properties of the pulverized particles. The nacre appears as elongated rod-shaped and elliptical particles.

The first process of coarse pulverization is a preparation process for removing the waste coated sand by crushing the washed waste shells into particles of a certain size or less using a coarse pulverization device to produce a first pulverized material of 40 mm or less.

As a specific example of the coarse grinding device, a hammer mill with a screen or a dry blade mill is used. In addition, other methods such as a jaw crusher, a gyratory crusher, and a crushing roll may be used.

In the first process of coarse pulverization, a hammer mill with a screen is used to rotate at high speed, and the degree of crushing of the shell can be controlled by adjusting the screen hole size and rotation speed of the bottom.

Table 2 below shows the grinding characteristics according to the grinding speed of the coarse grinder.

Grinding strength 3,500 rpm 5,250 rpm 7,000 rpm


result


The crushing speed is too slow, causing the shell to get caught in the blade and the machine to stop.
The crushing speed is adequate, and the shell does not get caught or stopped in the blade.
The crushing speed is rather fast, the shell does not get caught or stopped in the blade, and the difference is not large from the case of 5,250 rpm.

As can be seen from Table 2, it is appropriate to perform the grinding speed of the coarse grinder at 5,000 to 5,500 rpm.

[The second step of removing the primary impurities (S20)]

The first impurity removal step, which is the second process, includes simple adhesion foreign substances such as soil and sand attached to the crushed shell or waste shell, and moss; Plastics such as coated yarn; This is a process of removing salt, organic matter, and colored metal components remaining in the shell tissue.

The waste shell after the second process may be deodorized by spraying water containing sodium hypochlorite (NaOCl) or EM (Effective Microorganisms) onto the waste shell for the purpose of deodorization.

[The third process of crushing the closed shell (S30)]

The third step is a step of obtaining a second pulverized material of 30 mm or less by pulverizing the scrapped shell from which the primary impurities have been removed.

As described above, in the present invention, it is possible to manufacture a limestone substitute that can be subdivided for each use by going through the pulverization process of the waste shell including the crushing and heavy crushing process.

[The 4th step of removing secondary impurities (S40)]

The fourth step is a step of completely removing the residual amount of impurities contained in the waste shell that has been heavy chained through the third step.

[The 5th process of washing and sorting the waste shell (S50)]

The cleaning of the scrapped shell goes through the first and second cleaning processes.

In the first washing, the shell is washed by spraying water containing a deodorizing substance of sodium hypochlorite (NaOCl) or EM (Effective Microorganisms).

At this time, washing water is sprayed up and down while vibrating the inclined dong screen, and at this time, using microbubble water, it is possible to wash even the corners of the shell.

It was found that the shells that passed the first cleaning had a high cleaning effect of 95% or more when compared to the conventional spray cleaning method.

The shell after the first washing process is subjected to the second washing process.

In the second washing, the shells injected into the inclined dong screen are washed using a microbubbler. The secondary washing is a process of washing the prismatic layer of the shell and the colored layer on the surface of the shell using microbubbles. Secondary cleaning can further improve the whiteness and quality of limestone substitutes.

FIG. 3 is a diagram illustrating a relationship between a vibration frequency and an inclination of a vibrating screen when secondary cleaning is performed according to an embodiment of the present invention.

If the vibration frequency and inclination of the vibrating screen are too high, the cleaning effect of the shell decreases as the time for the shell to fall is accelerated.

If the vibration frequency and inclination of the vibrating screen are too low, the polishing time becomes longer, and accordingly, the amount of shells that are worn out and lost increases.

Therefore, as the vibrating body, the vibration frequency of the vibrating screen is 10 to 40 times/minute, and the inclination is preferably maintained at 15 to 45°. And the vibrating body is used to have a mesh hole size of 4 mm ~ 5 mm to be used for the sintered shell.

In addition, when only simple washing water is used, it is difficult to remove foreign substances in the curved portion of the shell, and foreign substances remain. Therefore, effective shell cleaning is possible by mixing and using microbubbled water.

And, while going through such a washing process, the particle size is separated by the vibrating screen. At this time, the average particle size (mm) of the shell particles whose particle size was adjusted is 16.0 ~ 17.60 mm.

[Sixth step of dehydrating, drying and crushing shell particles (S60)]

As the last step, the shell particles are dehydrated, dried, and crushed to produce fertilizer and cement; For iron sintering; A limestone substitute for quicklime production; is completed.

Hereinafter, the experimental results for the quality evaluation of the limestone substitute prepared according to the present invention will be described.

1. Experimental materials

The shell limestone substitute according to the present invention was added to the sintered ore blending material and then mixed to prepare five test samples.

And only iron ore blended raw materials containing natural limestone were used as comparative samples for comparison with the test samples.

The iron ore blending material used in the experiment consists of 75.0 wt% of iron ore, 1.0 wt% of silica sand, 10.0 wt% of limestone, 1.5 wt% of quicklime, 5.0 wt% of solid fuel mixed with coke and anthracite at the same weight ratio, and 7.5 wt% of moisture. .

2. Experiment method

A sintering experiment was conducted by self-manufacturing a pot tester machine equipped with a direct-fire LPG burner and a capacity of 14 kg.

The samples were charged into the port of the sintering machine and ignited to sinter the samples, and the following items were measured.

(1) Characteristic recovery rate and average particle size

The sintered sintered ore is subjected to a drop test four times in a row at a height of 2 m using a drop strength tester, and then screen-tested and classified into a particle size of 30 mm, 20 mm, 15 mm, 10 mm, 5 mm, and a particle size less than 5 mm. I did. And the weight percentage (weight of each particle size/total weight) for each particle size was calculated.

The property recovery rate was measured as the recovery rate of the sintered ore of 5 mm or more, that is, the property (particle size of 5 mm or more) from the entire sintered ore.

Property recovery rate (%) = (weight of property/total weight)×100

Meanwhile, the average particle size was calculated as follows.

Average particle size (mm)=[(30mm×percentage(30mm particle size))+(20mm×percentage(20mm particle size))+(15mm×percentage(15mm particle size))+(10mm×percentage(10mm particle size))+(5mm× Percentage (5mm particle size))]/80

(2) sintering rate

The sintering rate was calculated by checking the point in time when the exhaust gas temperature reached the highest point after ignition in the sintering machine.

Sintering speed (mm/min)= D/T, (T=time required to reach the peak of exhaust gas temperature, D=port length)

(3) Sintering productivity

The sintering productivity was calculated by measuring the amount of properties produced per day per port unit area of the sintering machine.

Sintering productivity (ton/day·m ² )=T/D·A, (T = quantity of quality, D = number of days, A = image cross section of port)

(4) shrinkage rate

It was calculated by measuring the shrinkage distance of the sintered layer after sintering was completed at the port of the sintering machine.

Shrinkage (%)=[(H ₀ -H ₁ )/H ₀ ]×100, (H ₀ = height of the sample loaded into the port before sintering, H ₁ = height of the sintered material loaded into the port after sintering)

3. Results

(1) Test sample 1

The experimental results for Test Sample 1 are shown in Table 3 below.

division Comparative sample Test sample 1 Test sample 2 Test sample 3 Test sample 4 A=contraction rate (%) 10.2 11.5 13.7 14.4 14.8 B=average particle size (mm) 12.5 16.8 16.7 16.4 17.2 C=sintering speed (mm/min) 23.2 25.5 25.2 25.5 25.0

Among the experimental results, test sample 3 was found to be the best in terms of sintering speed, sintering productivity, and property recovery rate. Therefore, the sintering test was performed three times in a row using Test Sample 3, and the average values for each item are shown in Table 4 below.

division Comparative sample Test sample 1 Test sample 2 Test sample 3 Test sample 4 A=contraction rate (%) 10.2 14.43 13.7 14.4 14.8 B=average particle size (mm) 12.5 17.53 16.7 16.4 17.2 C=sintering speed (mm/min) 23.2 25.43 25.2 25.5 25.0 D=sintering productivity (T/D·㎡) 36.66 41.87 41.52 41.87 40.5 E=characteristic recovery rate (%) 68.8 75.56 75.1 75.7 75.0

Referring to Table 4, the average value of the three times of test sample 3 was found to be superior to the comparison sample value in all items.

As described above, it can be seen that the sintered limestone substitute for the shell of the present invention can be added to the iron ore blending material to maintain the appropriate particle size of the sintered ore and increase the sintering rate, strength, and air permeability. Therefore, it is expected that the production of crude steel in the blast furnace can be greatly increased by improving the sintering productivity and quality required in the blast furnace operation.

Among the limestone substitutes produced according to an embodiment of the present invention, it was found that the sinterability was excellent, and the purity and particle size distribution were excellent.

The limestone substitute produced according to an embodiment of the present invention can be efficiently used for a user's desired purpose by mixing and using an appropriate ratio according to need for each particle size.

In the above, the embodiments of the present invention have been described in detail. The scope of protection of the present invention is not limited to the above-described embodiments, and anyone of ordinary skill in the art can easily see that various modifications and variations are possible within the limits not departing from the spirit and scope of the invention indicated by the claims. will be.

The limestone substitute for sintering according to the present invention does not contain elements such as K and Na harmful to steel, and improves air permeability of the sintered layer, promotes bonding and crystallization during the sintering process, thereby reducing the sintering time, thereby reducing fuel costs. Have,

By adding a limestone substitute based on the shell of a natural resource to the iron ore blending raw material, it can maintain the proper grain size of the sintered ore and increase the sintering speed, strength, and air permeability. It has great industrial applicability as it can increase production.

Claims (7)

A first step (S10) of crushing the lung shell,

A second step (S20) of deodorizing the waste shell through water containing EM (Effective Microorganisms) after removing primary impurities from the plastic and coating yarn contained in the crushed waste shell,

A third step (S30) of neutralizing the closed shell that has passed through the second step,

A fourth step (S40) of removing the residual amount of secondary impurities contained in the heavy-chain waste shell,

Including EM (Effective Microorganisms) by putting the closed shell through the fourth process in a vibrating body that has a mesh hole size of 4 mm to 5 mm and maintains a frequency of 10 to 40 times/minute inclination of 15 to 45°. The fifth step (S50) of adjusting the particle size to 16.0 ~ 17.6 mm by washing and selecting while spraying the washing water,

Method for producing a limestone substitute for sintering steel using a shell, characterized in that it comprises a sixth step (S60) of dehydrating the shell particles whose particle size has been selected by selecting.





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