KR100388312B1 - A method of manufacturing reduced iron in hot rolling mill included oily sludge by addition of sodiumcarbonate - Google Patents

Abstract

The present invention mixes hot rolled oil sludge and coke dust so that iron (Fe), which is present in the form of iron oxide, can be used as an iron source in oil-containing sludge generated in a hot rolling mill, and sodium carbonate is added, and water glass is added. The present invention relates to a method for producing reduced iron of hot rolled oil sludge by adding sodium carbonate to form reduced iron having a high iron (Fe) content by molding using a water-soluble organic binder.

1 to 5% by weight of sodium carbonate in the drying step of drying the hot rolled oil sludge, the blending step of blending the dried hot rolled oil sludge and the coke dust in a weight ratio of 8 to 20: 1, and the compounding material obtained by the blending step. A molding step of preparing a shape using a water-soluble organic binder containing 2 to 5% of water glass mixed therewith; a reducing step of reducing the molding material in a heating furnace of 1050 ° C. or higher in a nitrogen atmosphere to obtain a reducing product; It characterized in that it comprises a reduced iron manufacturing process to obtain reduced iron by cooling the water.

Description

A method of manufacturing reduced iron in hot rolling mill included oily sludge by addition of sodium carbonate}

The present invention mixes hot rolled oil sludge and coke dust so that iron (Fe), which is present in the form of iron oxide, can be used as an iron source in oil-containing sludge generated in a hot rolling mill, and sodium carbonate is added, and water glass is added. The present invention relates to a method for producing reduced iron of hot rolled oil sludge by adding sodium carbonate to form reduced iron having a high content of iron (Fe) by molding in a heated water-soluble organic binder.

In general, hot rolled oil sludge produced in a hot rolled plant has an adverse effect on the environment in various aspects, and oil-containing hot rolled sludge has a high environmental cost because it must be recycled through landfill or landfilled and treated in an environmentally stable state. It's happening.

As a related technology for treating hot rolled oil sludge, various techniques for physically recovering oil have been developed, and US Pat. No. 4,994,169 is known as a technology for recovering oil in a chemical conversion facility such as a distillation column. In addition, US Pat. No. 45,36,324 is known as a technique of separating sludge and oil by forming a vacuole using a nonionic surfactant as a chemical treatment method.

However, these methods are carried out through complicated steps, and there is a problem in that the end products obtained are disposed of by landfill.

The present invention has been invented to solve the problems in the prior art as described above, by promoting the reduction of the iron (Fe) component in hot-rolled oil sludge by the addition of sodium carbonate, iron ( It is an object of the present invention to provide a method for producing reduced iron of hot rolled oil sludge by adding sodium carbonate which can obtain reduced iron having a high Fe content.

1 is a reduced iron manufacturing process flow chart of the present invention,

2 is a graph showing the metallization rate of reduced iron prepared according to the formulation of Table 2,

3 is a graph showing the metallization rate of reduced iron prepared by adding different weight percent sodium carbonate,

4 is a graph showing the metallization rate of reduced iron prepared by adding different amounts of water glass;

Figure 5 is a graph showing the metallization rate of reduced iron produced at different temperatures.

In order to achieve the above object, the method for producing reduced iron of hot rolled oil sludge by adding sodium carbonate according to the present invention includes a drying step of drying the hot rolled oil sludge, and the dried hot rolled oil sludge and coke dust at a weight ratio of 8 to 20: 1. A molding step of mixing the compounding step to be mixed with 1 to 5% by weight of sodium carbonate to the compounding material obtained by the compounding step and producing a shape using a water-soluble organic binder containing 2 to 5% of water glass; It is characterized in that it comprises a reduction step of obtaining a reduced product by reducing the reduced temperature in a heating furnace of 1050 ℃ or more in a nitrogen atmosphere, and a reduced iron manufacturing process to obtain a reduced iron by cooling the reduced product.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the present invention.

1 is a flow chart showing a reduced iron manufacturing process of the present invention.

In the present invention, first, the drying process of evaporating and drying the moisture of the hot rolled oil sludge containing oil and water at 100 ° C. or more is carried out. In the actual process, the rotary kiln is passed within 20 minutes by maintaining a temperature of 200 ° C. or more. desirable.

Next, a blending process is performed in which the hot rolled oil sludge dried in the drying process is mixed with coke dust at a weight ratio of 8 to 20: 1, wherein the coke dust is powdered coke generated by drying coal to produce gook coke. The main chemical component of the coke dust is 84% by weight or more as carbon.

Alkali oxide + potassium oxide (Na ₂ O + K ₂ O), silicon oxide (SiO₂) and aluminum oxide (Al ₂ O ₃ ), which is an alkali component among the chemical components contained in the hot rolled oil sludge and coke dust, When producing the reduced iron, it reacts with the iron oxide to lower the melting point to induce a solid phase reaction.

When the hot rolled oil sludge is added such that the weight ratio of the hot rolled oil sludge to the coke dust is less than 8: 1, the amount of impurities contained in the reduced iron increases, which is not preferable. In addition, when the hot rolled oil sludge is added in a weight ratio of the hot rolled oil sludge to the coke dust of 20: 1 or more, a carbon (C) component necessary for the reduction during the reduction reaction may be insufficient to produce reduced iron having a normal iron content of 90% or more. none. Since the hot rolled oil sludge has a close relationship with the amount of coke dust in order to maintain an appropriate reduction state, it is necessary to combine the hot rolled oil sludge so as to satisfy the amount of carbon required for reduction without introducing excessive coke dust.

After the compounding step, 1 to 5% by weight of sodium carbonate and 95 to 99% by weight of the blended material are mixed, and a water soluble organic binder containing water glass is used to form a shape by a conventional method. The main reason for adding sodium carbonate preferentially is demonstrated through the following chemical formula.

Na ₂ CO ₃ → Na ₂ O + CO ₂

CO ₂ + C → 2CO

3CO + Fe ₂ O ₃ → 3CO ₂ + 2Fe

In Formula 1, sodium carbonate (Na ₂ CO ₃ ) generates carbon dioxide (CO ₂ ) through pyrolysis, and the carbon dioxide (CO ₂ ) reacts with carbon (C) of coke dust in Formula 2 to produce carbon monoxide (CO). Generate. Finally, the carbon monoxide (CO) gas in Chemical Formula 3 is reacted with iron oxide (Fe ₂ O ₃ ) to reduce the reduced iron.

The carbon dioxide (CO ₂ ) generated from the initial reaction of the carbon monoxide generated in the solid phase reaction of Formula 2, that is, sodium carbonate of Formula 1 has the effect of rapidly promoting the initial reaction of the reduction.

As can be seen from the above, the sodium carbonate promotes the reduction of iron oxide to reduced iron by generating carbon dioxide which is a decisive factor for the reduction.

As such, the amount of sodium carbonate which serves as a reduction promoting role is preferably 1 to 5% by weight, and the reason for this is that the amount of sodium carbonate that does not express the reduction promoting effect is less than 1% by weight. This is because sodium oxide (Na ₂ O) is included and not preferable.

In the molding process, a water-soluble organic binder is used for the blended material in which sodium carbonate is mixed, in order to increase the strength when preparing the shape. In the present invention, polyvinyl alcohol or carboxymethyl cellulose 2% and water 98% The mixed solution was used. In addition, the pellets prepared by adding 2 to 5% of water glass to the water-soluble organic binder were found to have high strength and excellent reduction effect during the reduction reaction, which is why sodium (Na) and silicon (Si) dissolved in the water glass were used. ) Played a direct role in the reduction of iron oxide by promoting low melting point. However, when the concentration of the water glass is less than 2%, the reduction reaction is inadequate, and since it does not show any further effect at 5% or more, in the present invention, it is appropriate to prepare a shape using a water-soluble organic binder to which the water glass is added 2-5%. .

After the molding process, a reducing process of reducing the molding material in a heating furnace of 1050 ° C. or higher in a nitrogen atmosphere is performed. When the temperature during the reduction reaction is lower than 1050 ° C., the ratio of reduced iron to total iron (Fe) component is reduced. Since it is less than 90%, it is preferable to perform said reduction reaction at 1050 degreeC or more.

A reduced iron manufacturing process, which is a next process, is a process of cooling the reduced product in a conventional manner to produce reduced iron.

Finally, the preferred chemical compositions of the hot rolled oil sludge, coke dust, and sodium carbonate for application to the present invention are shown in Table 1 below.

ingredient SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ FeO MnO MgO CaO Na ₂ O + K ₂ O C S Hot Rolled Oil Sludge (wt%) 0.15 to 3.5 0.10 to 0.5 40.5-47.5 42.5-48.5 0.15 to 0.32 0.01 to 0.05 0.01 to 0.3 0.01 to 0.1 1.5-8.2 0.03 to 0.3 Coke dust (wt%) 3 to 5 3 to 5 0.1 0.1 - 0.1-0.3 0.02 to 0.07 0.01 to 0.02 84-87 0.03-0.07 Sodium carbonate (wt%) 〉 0.1 〉 0.1 〉 0.1 〉 0.1 〉 0.1 〉 0.1 〉 0.1 50 to 51.8 19-21 〉 0.1

Hereinafter, the reason for numerical limitation in the present invention will be described in detail through the present invention and comparative examples.

In order to determine the weight ratio of hot rolled oil sludge and coke dust, 100 g of hot rolled oil sludge was blended with coke dust from 2.5 g to 15 g in the ratio shown in Table 2 below.

In the state where sodium carbonate was not mixed with the compounding material, 8% of a water-soluble organic binder in which 3% of water glass was added to 2% of polyvinyl alcohol was molded, and the reaction was reduced for 60 minutes at a temperature of 1100 ° C. in a nitrogen atmosphere furnace. .

division Comparative Example 1 Inventive Example 1 Inventive Example 2 Inventive Example 3 Inventive Example 4 Comparative Example 2 Hot rolled oil sludge (g) 100 100 100 100 100 100 Coke dust (g) 2.5 5 7.5 10 12.5 15 Weight ratio 40: 1 20: 1 13.3: 1 10: 1 8: 1 6.7: 1

Pellet prepared as described above was measured by the wet chemical analysis of the total iron (Fe) component contained in the pellet and the amount of reduced reduced iron to calculate the metallization rate in the following formula (4).

The results are shown in Figure 2, the metallization rate is used to determine the quality of the reduced iron, the reduced iron for practical use should be 90% or more.

In Inventive Examples 1 to 4 and Comparative Example 2 of FIG. 2, the metallization rate is maintained at 90% or more, whereas in Comparative Example 1, the metallization rate is less than about 85%, which corresponds to the amount of coke dust. Due to the lack of the carbon component necessary for the reduction is a result of not sufficiently reducing the iron oxide in the oil sludge.

In addition, in Comparative Example 2, although the sufficient metallization rate is present, the coke dust is blended with the hot rolled oil sludge because the carbon component in the reduced iron is present as it is, due to the excessive coke dust content. In this case, it can be seen that the weight ratio of 8 to 20: 1 is appropriate blending.

Next, sodium carbonate was added at 0,1,2,3,4,5,6% by weight, respectively, to examine the reduction promoting effect by the sodium carbonate.

The mixture of hot rolled oil sludge with 13.3% by weight of coke dust is mixed with the above-mentioned amounts of sodium carbonate to 100% by weight, and 8% of polyvinyl alcohol containing 3% of water glass is added to the water-soluble organic binder. After molding, the mixture was reduced for 60 minutes at a temperature of 1100 ° C. in a heating furnace of a nitrogen atmosphere.

Calculation of the metallization rate of the reduced iron prepared as described above is calculated by the formula (4) through a wet chemical analysis and the results are shown in FIG. When sodium carbonate was not added, the metallization rate was 91%, and the metallization rate rapidly increased as the amount of sodium carbonate was increased. In this phenomenon, the hot rolled oil sludge and the coke dust are low-melting by sodium carbonate, and the carbon monoxide generated by reacting with the carbon component of the pellets produced by the molding process easily reacts with iron oxide, and the reduction rate is faster, thereby reducing the reaction. It can be seen that it promotes.

In addition, when the melting point of the pellets produced by the molding process is lowered, the carbon component of the pellet and the oxygen component in the hot rolled oil sludge generate carbon monoxide in a solid phase reaction, and the carbon monoxide reacts with the iron oxide to form carbon dioxide, thereby promoting reduction. It can be seen that.

The addition effect of the sodium carbonate did not have a reduction promoting effect when the addition amount is less than 1% by weight, but the effect is greatly generated when the addition amount of the sodium carbonate is 1% by weight or more, and 5 wt.% Or less when the addition amount of the sodium carbonate is 6% by weight or more. Since there is no significant difference from the%, in the present invention, it is preferable to add 1 to 5% by weight of sodium carbonate to the hot rolled oil sludge and the coke dust mixture material to produce reduced iron.

Next, in order to check the difference in the degree of reduction according to the amount of water glass added to the water-soluble organic binder, to prepare an aqueous solution of 2% polyvinyl alcohol used as the water-soluble organic binder, 1,2,3,4,5,6 It was prepared by adding% water glass.

Other conditions include 13.3: 1 weight ratio of dried hot rolled oil sludge and coke dust, and each pellet prepared by adding the above water-soluble organic binder without addition of sodium carbonate was heated to 1050 ° C. in a nitrogen atmosphere heating furnace. Reduction was carried out for a minute. Each sample subjected to the reduction treatment was subjected to wet analysis to calculate the metallization rate using Chemical Formula 4, and the results are shown in FIG. 4.

As can be seen in Figure 4, when the water glass addition amount is less than 1% does not show a difference in the metallization rate in the reduced iron and the case of not adding water glass, above that the metallization rate is rapidly increased, which is the sodium contained in the water glass The increased carbon monoxide gas reduces the iron oxide because (Na) and silicon (Si) components soften the iron oxide during reduction, thereby increasing the contact between the iron oxide and carbon and increasing the amount of carbon monoxide (CO) gas generated. It plays a direct role in increasing the metallization rate.

In addition, when the amount of water glass added is 6% or more, the result is almost the same as when 5% is added. Therefore, in the present invention, it is preferable to add 2 to 5% of the water glass to the water-soluble organic binder.

Next, in order to derive the temperature condition of the furnace during the reduction treatment, the temperature conditions for the reduction reaction in the nitrogen atmosphere were set to 100 ° C., 1050 ° C., 1100 ° C., 1150 ° C., and 1200 ° C., respectively.

3 weight% of sodium carbonate was added to 97 weight% of the material mix | blended with the weight ratio 13.3: 1 of hot-rolled oil sludge and coke dust to be 100 weight%. Pellets were prepared by press molding using a water-soluble organic binder containing 3% water glass, and cooled after 60 minutes in a nitrogen atmosphere at the above temperature. Thereafter, the metallization rate was calculated using the chemical formula 4, and the results are shown in FIG. 5.

As can be seen in Figure 5, the metallization rate is increased according to the reduction temperature, in order to maintain the metallization rate of 90% or more, it is preferable to perform the reduction reaction at a temperature condition of 1050 ℃ or more.

When sodium carbonate is not added, heat treatment must be performed at 1100 ° C. or higher to maintain the metallization rate of 90% or more, whereas when sodium carbonate is added, a reduction reaction occurs at a lower temperature. It is preferable to limit the temperature condition of to the conditions performed at 1050 degreeC or more.

As described in detail above, by applying the method for producing reduced iron of hot rolled oil sludge by the addition of sodium carbonate of the present invention, by producing reduced iron using hot rolled oil sludge and coke dust, environmentally friendly wastes can be made in steel mills. It is also preferable in terms of recycling, and there is less risk of slag generation due to less oxygen content than the conventional method of using the hot rolled oil sludge as a steelmaking substitute without a reduction reaction. It will work.

Claims (1)

A drying process of drying the hot rolled oil sludge, A blending process of blending the dried hot rolled oil sludge and coke dust at a weight ratio of 8 to 20: 1, A molding step of producing a shape using a water-soluble organic binder containing 1-5% by weight of sodium carbonate and 2-5% of water glass mixed with the compounding material obtained by the compounding step; A reduction step of reducing the molded material in a heating furnace of 1050 ° C. or higher in a nitrogen atmosphere to obtain a reduced product; Method for producing reduced iron of hot rolled oil sludge by the addition of sodium carbonate, characterized in that it comprises a reduced iron production process to obtain the reduced iron by cooling the reduced product.