KR101165395B1 - Method for Manufacturing Lightweight Aggregate Using Hot Rolling Mill Sludge and Cold Rolling Mill Sludge - Google Patents

Abstract

The present invention relates to a method for producing artificial light aggregates containing cold rolled and hot rolled sludge and clay as a main raw material, and more specifically, cold rolled and hot rolled sludge and clay as a main raw material, and having a dry weight ratio of 0.8 to 1.5. It relates to a manufacturing method of artificial light weight aggregate, characterized in that 5 to 20%.

The artificial lightweight aggregate according to the present invention is manufactured by using artificial cold aggregate by using cold rolled and hot rolled sludge which are by-products of the steel industry as a main raw material. It has the effect of solving the environmental pollution problem by reducing.

Cold rolled and hot rolled sludge, lightweight aggregate, foamed, fired, recycled

Description

Method for Manufacturing Lightweight Aggregate Using Hot Rolling Mill Sludge and Cold Rolling Mill Sludge}

The present invention relates to a method for producing artificial light aggregates containing cold rolled and hot rolled sludge and clay as the main raw materials, and more specifically, cold rolled and hot rolled sludge and clays as the main raw materials, and have a dry weight ratio of 0.8 to 1.5. It relates to a method for producing artificial light weight aggregate, characterized in that the absorption rate of 5 to 20%.

Conventionally, in order to manufacture lightweight aggregate using natural raw materials, raw materials containing foaming agents such as expanded shale and expanded clay are required.The quality of lightweight aggregate is determined according to the distribution and content of the foaming agent. It is very important. These raw materials are limited to a few countries even in foreign countries, and there is no domestic situation. Therefore, in order to obtain high-quality lightweight aggregates, light aggregates are manufactured by artificially adding Fe ₂ O ₃ , C components to existing lightweight aggregate manufacturing raw materials or natural raw materials, which takes up a considerable proportion to the cost of lightweight aggregates. Rather, it gives a lot of constraints in manufacturing lightweight aggregate.

Recently, research is being conducted to manufacture lightweight aggregate at low cost using industrial waste.

Generally, steelmaking by-products are classified into slag (blast furnace slag, steelmaking slag), sludge (steelmaking sludge, lime sludge, cold rolled and hot rolled sludge, after-treatment sludge, drainage sludge, playing sludge), dust (sintered R). / EP dust, sintered W / EP dust, lime B / F dust, steelmaking E / P dust, steelmaking B / F dust) and incineration residues. These by-products are composed of Si0 ₂ , Al ₂ O ₃ , Fe ₂ O ₃ , CaO, MgO, Na ₂ O, K ₂ O, TiO ₂ , P ₂ O ₅ , Cr ₂ O ₃ , MnO, C, etc. Almost all of these steel by-products are recycled in the steelmaking process, but among them, cold rolled and hot rolled sludge contain impurities such as oil, and the recycling rate is very low. It is being buried. In addition, most of the constituent chemical components are made of heavy metals, which are quite harmful to the human body, there is a problem that can cause secondary environmental pollution when landfilling.

Korean Patent Publication No. 2003-0069692 discloses a lightweight aggregate having an apatite crystal structure using phosphate wastewater sludge, which manufactures lightweight aggregate by adding 5 to 15 wt% of steel sludge containing about 60% of iron as a blowing agent. Although the production method of is disclosed, when the addition amount of the steel sludge exceeds 15% by weight, there is a problem that there is a significant restriction on the amount of recycling because the black color of the resultant product is strengthened to reduce the commerciality.

In addition, Korean Patent No. 662,812 proposes a method of manufacturing artificial ultra-light aggregates by mixing 20-30 parts by weight of dry steel sludge in a dry state. The main reason for manufacturing artificial lightweight aggregate in this way is that the moisture content of raw sewage sludge is about 80%, so it is impossible to mold, so to solve this problem by mixing dry steel sludge dried to about 20 ~ 30% moisture content It is to reduce the drying cost by enabling the molding of lightweight aggregate.

The general concept of foaming of lightweight aggregate is that when the lightweight aggregate is fired, thermal desorption of organic substances occurs, and the gas and carbonic acid, sulfur dioxide and trivalent iron oxides generated by desorption of organic substances are reduced to divalent iron oxide. As the outer shell of the plastic is fired, if the gas cannot penetrate out of the plastic surface, the interior of the clay is swollen and has a more or less homogeneous porosity, thereby making it lighter. The manufacturing of artificial light aggregate using the combination of raw sewage sludge and dry steel sludge disclosed in the above-mentioned literature goes through a similar process, but more than 90% of the organic material possessed by the raw sewage sludge forms many aeration holes during the firing process. It is difficult to reduce the reaction of Fe ₂ O ₃ , and the control of the firing process such as excessively calcined or melted and adhered to the surface of the lightweight aggregate before foaming has a very difficult problem. It is difficult to secure quality uniformity.

In Korea, the steel industry accounts for a large portion of the entire industry, resulting in a large amount of waste, including sludge, but is being treated as a method of manufacturing solidified bricks and landfilling, and the treatment technology is still in its infancy. Steel sludge, etc., which is not recycled and landfilled, is likely to pollute the surrounding environment even if it is landfilled, and has serious problems such as soil pollution. In addition, the treatment of sludge involves enormous costs, which leads to an increase in manufacturing cost, thereby deteriorating a company's competitiveness.

Although the above-described inventions suggest recycling methods of industrial by-products containing iron components, specifically, they are additives for foaming rather than recycling as main raw materials in the production of lightweight aggregates, or serve as moisture control agents during molding and solidification. It is not the ultimate treatment method which requires final treatment such as brick manufacturing and pelletization after intermediate treatment.

Therefore, the recycling of sludge, which is a by-product of steelmaking, requires much research and active utilization because it helps to prevent environmental pollution and enhance national competitiveness.

Therefore, the present inventors have made intensive efforts to recycle steelmaking by-products. As a result, when manufacturing light weight aggregates, cold rolling and hot rolled sludge, which are by-products of the steelmaking industry, can be controlled as raw materials, and the foaming process can be easily controlled during firing. It was confirmed that the ratio is high, and the recycling rate of steelmaking by-products can be significantly increased, and completed the present invention.

An object of the present invention is to provide an artificial lightweight aggregate prepared by mixing cold rolled and hot rolled sludge and clay in a constant ratio in order to recycle steel making by-products containing impurities such as oil components that are difficult to recycle.

Another object of the present invention to provide a method for producing the artificial lightweight aggregate.

The present invention is prepared with cold and hot rolled sludge and clay as the main raw material, provides an artificial light weight aggregate, characterized in that the dry weight ratio is 0.8 ~ 1.5, the absorption rate is 5 to 20%.

The present invention also comprises the steps of (a) mixing 5 to 90 parts by weight of cold rolled and hot rolled sludge and 10 to 120 parts by weight of clay; (b) molding the mixture; (c) drying the molded body; And (d) it comprises a step of firing the dried body, provides a manufacturing method of artificial lightweight aggregate, the dry weight ratio is 0.8 ~ 1.5, the absorption rate of 5 to 20%.

The artificial lightweight aggregate according to the present invention is manufactured by using artificial cold aggregate by using cold rolled and hot rolled sludge which are by-products of the steel industry as the main raw materials, and do not require a separate blowing agent, and can recycle steel waste. It has the effect of solving the environmental pollution problem by reducing.

The present invention relates to an artificial light weight aggregate, which is manufactured at a consistent point with cold rolled and hot rolled sludge and clay as main raw materials, has a dry weight ratio of 0.8 to 1.5, and an absorption rate of 5 to 20%.

The present invention in another aspect, (a) mixing 5 to 90 parts by weight of cold rolled and hot rolled sludge and 10 to 120 parts by weight of clay; (b) molding the mixture; (c) drying the molded body; And (d) comprising a step of firing the dried body, the specific gravity of the construction is 0.8 to 1.5, and relates to a method for producing artificial lightweight aggregate of 5 to 20% water absorption (Fig. 1).

In the present invention, cold rolled and hot rolled sludge means sludge containing a large amount of heavy metals generated in the cold rolled and hot rolled processes of the steel manufacturing plant.

The artificial lightweight aggregate according to the present invention uses steel waste such as cold rolled and hot rolled sludge as a raw material of artificial lightweight aggregate, and the chemical components such as Fe ₂ O ₃ and C contained in a large amount in cold rolled and hot rolled sludge are as follows. Since it becomes a key component that plays a role of foaming during the firing of lightweight aggregate through the reaction, no separate blowing agent is required.

Fe ₂ O ₃ + C → 2FeO + CO ↑. ... (One)

3Fe ₂ O ₃ + C → 2Fe ₃ O ₄ + CO ↑. ... (2)

3Fe ₂ O ₃ → 2Fe ₃ O ₄ + 1/2 CO ↑. ... (3)

Therefore, the problem of securing raw materials that could not be manufactured due to the lack of foaming components in the past was solved, and at the same time, the lightweight aggregates were manufactured by using the steel waste being buried and used as raw materials for high value-added construction materials. As a result, it also contributes significantly to the reduction of environmental pollutants.

In one embodiment of the present invention, the artificial light weight aggregate is manufactured by mixing 5 to 90 parts by weight of cold rolled and hot rolled sludge and 10 to 120 parts by weight of clay, and then manufactured through a firing process in an electric furnace at 1100 to 1200 ° C. The aggregate had a dry weight of 1.0-1.5 and an absorption rate of 5-10%.

In another embodiment of the present invention, the artificial lightweight aggregate is mixed with 5 to 90 parts by weight of cold rolled and hot rolled sludge and 10 to 120 parts by weight of clay, followed by primary molding with an extruder, and then the molded body is cut and secondaryly formed, then 950 to 1100. Manufactured through a rotary kiln firing process of ℃, the artificial lightweight aggregate showed a dry weight ratio of 0.8 ~ 1.5 and the absorption rate of 12 to 20%, heavy metals were not detected as a result of the measurement of the amount of harmful substances released.

Light weight aggregates having various specific gravity can be used not only for structural materials in construction and civil engineering but also for sound absorbing materials for noise reduction in buildings, humidity control and horticulture for buildings, and thus have wide application fields.

Through the following examples will be described the present invention in more detail. These examples are only for illustrating the present invention, it will be apparent to those skilled in the art that the scope of the present invention is not to be construed as being limited by these examples.

Example 1 Measurement of Chemical Composition of Raw Material

The chemical composition of red clay (Asan Industrial Co., Ltd., Hongseong Material, Chungnam), cold rolled and hot rolled sludge (POSCO) required for the manufacture of artificial lightweight aggregate was measured according to the chemical analysis and test method of KS L 4007 (Chemical Analysis of Clay). .

As a result, as shown in Table 1, it was found that more than 70% Fe ₂ O ₃ component is contained in the cold and hot rolled sludge, and that the unburned carbon component is also contained more than 10%, these components are firing process It can supply a sufficient amount to play a heavy foaming role.

division Ig loss
Si0 ₂
Al ₂ O ₃
Fe ₂ O ₃
CaO
MgO
Na ₂ O
K ₂ O
TiO ₂
ZrO ₂
P ₂ O ₅
Cr ₂ O ₃
MnO
C Red clay 9.00 62.10 16.81 6.20 0.51 1.16 0.81 2.35 0.77 - 0.09 - - - Cold rolled and hot rolled sludge 8.61 1.26 5.13 70.22 0.82 0.04 0.01 0.01 0.02 - 0.85 0.13 0.23 12.69

Example 2: Preparation of lightweight aggregate using cold rolled and hot rolled sludge

In Experimental Example 1, 10 parts by weight of cold rolled and hot rolled sludge were mixed and 90 parts by weight of clay, and then the raw materials which had been pulverized and kneaded were molded into a ring shape by hand. The firing process of this test example was carried out in an electric furnace of about 1150 ℃. The dry weight of the lightweight aggregate prepared according to the present experimental example was 1.48, and the water absorption was 9.48%.

Experimental Example 2 by mixing 20 parts by weight of cold rolled and hot rolled sludge, 80 parts by weight of clay to prepare a molded body in the same manner as in Experiment 1. The firing process of this test example was carried out in an electric furnace of about 1150 ℃. The dry weight of the lightweight aggregate prepared according to this test example was 1.40, and the water absorption was 8.64%.

Experimental Example 3 was prepared by the same method as Experimental Example 1 by mixing 30 parts by weight of cold rolled and hot rolled sludge, 70 parts by weight of clay. The firing process of this test example was carried out in an electric furnace of about 1150 ℃. The dry weight of the lightweight aggregate prepared according to the present experiment was 1.46, and the absorption was 9.05%.

Experimental Example 4 was prepared by the same method as Experimental Example 1 by mixing 40 parts by weight of cold rolled and hot rolled sludge, 60 parts by weight of clay. The firing process of this test example was carried out in an electric furnace of about 1150 ℃. The dry weight of the lightweight aggregate prepared according to this test example was 1.08, and the water absorption was 9.59%.

In Experimental Example 5, 50 parts by weight of cold rolled and hot rolled sludge were mixed and 50 parts by weight of clay to prepare a molded body in the same manner as in Experimental Example 1. The firing process of this test example was carried out in an electric furnace of about 1150 ℃. The dry weight of the lightweight aggregate prepared according to this example was 1.16, and the water absorption was 7.44%.

Experimental Example 6 was mixed with 60 parts by weight of cold rolled and hot rolled sludge, 40 parts by weight of clay to prepare a molded body in the same manner as in Experiment 1. The firing process of this test example was carried out in an electric furnace of about 1150 ℃. The dry weight of the lightweight aggregate prepared according to this test example was 1.23, and the water absorption was 4.48%.

Experimental Example 7 was prepared by the same method as Experimental Example 1 by mixing 70 parts by weight of cold rolled and hot rolled sludge, 30 parts by weight of clay. The firing process of this test example was carried out in an electric furnace of about 1150 ℃. The dry weight of the lightweight aggregate prepared according to this test example was 1.11 and the water absorption was 5.79%.

Comparison of Specific Gravity and Absorption Rate of Lightweight Aggregate Manufactured in Electric Furnace division Cold rolled and hot rolled sludge clay Weight ratio Absorption rate (%) Experimental Example 1 10 90 1.48 9.48 Experimental Example 2 20 80 1.40 8.64 Experimental Example 3 30 70 1.46 9.05 Experimental Example 4 40 60 1.08 9.59 Experimental Example 5 50 50 1.16 7.44 Experimental Example 6 60 40 1.23 4.48 Experimental Example 7 70 30 1.11 5.79

Table 2 shows the dry weight and absorption ratio of the light weight aggregate prepared according to Experimental Examples 1 to 7. As a result of measuring and comparing the properties of the cold aggregate and hot rolled sludge mixed with clay to prepare lightweight aggregates, it was found that the lightweight aggregates produced in the above experimental examples had absorption rates of less than 1.5 and less than 10% of the dry weight ratio.

Example 3: Comparison of Properties of Lightweight Aggregate Prepared in Mass Production Process

In Experimental Example 8, 30 parts by weight of cold rolled and hot rolled sludge and 70 parts by weight of clay were mixed to form a raw material that had been pulverized and kneaded with an extrusion machine equipped with a mold having a large number of 5 to 11 mm diameter circles. At this time, the molded body was cut to a certain length using a rotary cutter, and then transferred to a rolling barrel that was rotated to secondary molding into a ring shape. After drying the molded body, a firing process was performed in a rotary kiln at about 1000 ° C. The weight ratio of the manufactured lightweight aggregates was 1.44, and the absorption rate was 13.98%.

Experimental Example 9 was prepared according to the method of Experimental Example 8 after mixing 40 parts by weight of cold rolled and hot rolled sludge and 60 parts by weight of clay. After drying the molded body, a firing process was performed in a rotary kiln at about 1000 ° C. The dry weight of the manufactured lightweight aggregate was 1.29, and the water absorption was 15.76%.

Experimental Example 10 was prepared according to the method of Experimental Example 8, after mixing 50 parts by weight of cold rolled and hot rolled sludge, 50 parts by weight of clay. After drying the molded body, a firing process was performed in a rotary kiln at about 1000 ° C. The dry weight of the manufactured lightweight aggregate was 0.90, and the water absorption was 19.80%.

The dry density and water absorption in the properties of artificial light weight aggregates prepared according to the experimental example were measured by KS F 2503 (density and water absorption test of coarse aggregate).

Comparison of Properties of Lightweight Aggregate Manufactured from Rotary Kiln Cold rolled and hot rolled sludge clay Weight ratio Absorption rate (%) Experimental Example 8 30 70 1.44 13.98 Experimental Example 9 40 60 1.29 15.76 Experimental Example 10 50 50 0.90 19.80

Table 3 shows the specific gravity and absorption rate of the light weight aggregate prepared according to Experimental Example 8 to 10. The physical properties of the lightweight aggregate prepared in the above experimental example showed that the specific gravity is 1.5 or less. Particularly, in the case of Experimental Example 10, the specific gravity was considerably low as 0.90, which is not only general lightweight structural aggregate, but also possible to manufacture ultralight aggregate that can be used for non-structural use.

The production of light weight aggregates having various specific gravitys is not limited to structural materials in the construction and civil engineering sectors, but also for sound absorbing materials requiring partitions, such as buildings, noise, etc. It can be used for the back, which means that the field of application is quite wide.

In addition, the leaching amount of harmful substances in the lightweight aggregate prepared according to Experimental Example 10 was measured by the waste process test method, and heavy metals were not detected as shown in Table 4 below.

division Hazardous Substance Dissolution (mg / L) Pb CD Cr Cu As Hg Zn Ni Experimental Example 10 Lightweight Aggregate
radish
radish
radish
radish
radish
radish
radish
radish

Example 4: Concrete compressive strength measurement using lightweight aggregate including cold rolled and hot rolled sludge

Compressive strength was measured after producing concrete using lightweight aggregate prepared according to the present invention.

Preparation Example 1 of Table 5 is a concrete produced using the lightweight aggregate of Experimental Example 9, which was prepared according to KS F 2403 (method for preparing concrete strength test specimen) and cured, and then cured with KS F 2405 (concrete compression). 28 days compressive strength was measured according to the test method).

On the other hand, Comparative Example 1 of Table 5 was used to compare the Preparation Example 1 with the general crushed stone aggregate (general aggregate material in Chungnam Gwangcheon) used in the existing concrete, the concrete manufacturing method and the test method of the compressive strength is It was done in the same way.

As a result, as shown in Table 5, when comparing the lightweight aggregate concrete containing the cold rolled and hot rolled sludge prepared in Preparation Example 1 and the concrete using the existing crushed stone prepared in Comparative Example 1, cold rolled and hot rolled sludge of Preparation Example 1 The compressive strength of the artificial lightweight aggregate concrete containing 23.5 N / mm ² , showed a compressive strength similar to or slightly higher than the compressive strength of 23.0 N / mm ² of crushed aggregate concrete of Comparative Example 1. In addition, when looking at the materials used and the mixing ratio, the amount of cement used when producing concrete from ordinary crushed aggregates is 330 kg / m ³ , whereas when concrete is manufactured using artificial light aggregate, 315 kg / m ³ of cement is used. Cost reduction of concrete is also expected.

division
Material and compounding ratio (kg / m ³ )
Aggregate Type

Compressive strength (N / mm ² )
cement Fine aggregate Coarse aggregate S / A (%) W / C (%) Comparative Example 1 330 811 918 47 55 Crushed aggregate 23.0
Production Example 1
315
827
520
47
55 Eco Artificial
Lightweight aggregate
23.5

Therefore, artificial lightweight aggregate prepared according to the method of the present invention is easy to reduce the reaction of Fe ₂ O ₃ by using the cold and hot rolled sludge containing a large amount of Fe ₂ O ₃ , C component as a blowing agent as a main raw material It is easy to control the foaming process during firing, so there is no need for a separate blowing agent, and the average firing temperature is 1000 ℃, which is about 100 ~ 200 ℃ lower than the existing firing temperature. By using more than 50% as a major raw material of the company, the recycling rate can be dramatically increased.

Having described the specific part of the present invention in detail, to those skilled in the art, such a specific description is only a preferred embodiment, whereby the scope of the present invention is not limited, it will be apparent. will be. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Figure 1 shows the manufacturing process of the artificial light weight aggregate according to the present invention.

Claims (5)

It is manufactured by containing 5 to 90 parts by weight of cold rolled and hot rolled sludge and 10 to 120 parts by weight of clay, and has a dry weight ratio of 0.8 to 1.5 and an absorption rate of 5 to 20%. A method for producing artificial light weight aggregates having a dry weight ratio of 0.8 to 1.5 and an absorption rate of 5 to 20%, including the following steps: (a) mixing 5 to 90 parts by weight of cold rolled and hot rolled sludge and 10 to 120 parts by weight of clay; (b) molding the mixture mixed in the step (a); (c) drying the molded body molded in the step (b); And (d) calcining the dried body dried in the step (c). The method of claim 2, wherein the molding of step (b) is a pelletizing molding or an extrusion molding. The method of claim 2, wherein the firing of step (d) is performed in an electric furnace or a rotary kiln. The method of claim 2, wherein the firing of the step (d) is characterized in that it is carried out at 950 ~ 1200 ℃.

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