KR20050031237A - Method for preparing of aggregate by using nutralization sludge - Google Patents

Abstract

Provided is a method for manufacturing aggregates used as constructional exterior materials by using reduced slag and neutralization sludge generated from the steelmaking process. The aggregates using industrial wastes as raw materials are manufactured by the following steps of: mixing reduced slag and neutralization sludge in a weight ratio of 30-90 : 70:10, wherein the reduced slag is pre-treated by removing iron and sieving to be up to 100mesh powder and the neutralization sludge, used without pre-treatment, contains 50-90% of moisture acting as a binder; forming the mixtures to an effective shape like pellet through extruder or cup mixer; curing formed aggregates at room temperature and more than 90% of relative humidity. The resultant aggregates have more than 40kg/cm^2 of compression strength.

Description

Method for preparing aggregate using special steel pickling sludge {Method for preparing of aggregate by using nutralization sludge}

The present invention relates to a method for producing aggregates used in the manufacture of building materials, such as building exterior materials, and more particularly, to produce aggregates by mixing the reducing slag generated in the steelmaking process and the pickling sludge generated during the pickling process. It is about how to.

In general, by-products generated in a factory for manufacturing special steel include dust, slag and sludge. Slag is divided into oxidizer slag and reducing slag according to the detailed process that occurs.

Among them, oxidized slag is used for civil engineering aggregates such as road aggregates and fillers because its shape is crushed gravel and blocks. However, reducing slag is a powder form in which a large amount of powder is present, and it is difficult to recycle, so there is no special use.

Therefore, the reducing group slag is stored in the field by mixing with the oxidizer slag, but is used as a civil aggregate, etc., but due to the inherent characteristics of the reducing group slag, many problems occur. That is, reducing slag is mostly made of powder, so dust is generated at the site of storage, transportation, and utilization. Especially, in order to prevent scattering dust, alkaline leachate is used when water is sprayed or directly contacted with water such as rainwater. The problem is serious because it causes them.

On the other hand, in manufacturing a product from the manufactured special steel, a process that must necessarily go through is a pickling process. That is, the acidic wastewater generated during the pickling process to clean the surface of the product, such as steel pipes or coils, is subjected to neutralization treatment, in which sludge is generated. The pickling wastewater treatment sludge is currently being entrusted to an off-site waste treatment company, which is a significant expense, and the sludge treatment company has many problems in the sludge treatment process. A general sludge treatment process is as follows.

First, the sludge is transported to a treatment plant, which contains about 50 to 90% of water, which causes many difficulties in transportation. The sludge transported to the treatment plant is heat-treated in a high temperature furnace of about 1000 ^o C and evaporated to produce moisture as aggregate. The aggregates are sold to building facade manufacturers, and the amount of aggregate produced is less than half the amount of sludge because the moisture contained in the sludge that has been transported is removed. Therefore, the amount of aggregate that can be recycled and sold is very small.

In addition, despite the neutralization treatment of the pickling wastewater sludge, since a small amount of residual acid is present in the contained water, the burden of separately collecting and treating the acidic vapor generated in the heat treatment process is increased. Problems are also likely to occur.

In this technical field, various aggregate production methods have been developed that can be used as building materials while at the same time recycling waste generated in steel making processes.

Patent Publication No. 2003-0011757 discloses a light weight comprising the step of combining at least two wastes selected from a group of wastes consisting of coal ash, EAF dust, steel slag, sewage sludge ash, stone powder, paper sludge incineration ash and aluminum dross according to chemical composition. The present invention relates to a method for preparing an aggregate composition, wherein the lightweight aggregate refers to an aggregate having a dry weight ratio of 2.5 or less.

In addition, Japanese Patent Application Laid-Open No. 1998-0014322 discloses a method for producing a lightweight aggregate using sintered dust and silica produced in a large amount in the manufacturing process of sintered ore.

Patent Publication No. 2002-0074430 provides a method and apparatus for manufacturing aggregate using steelmaking slag that can be used by installing steelmaking slag recycling facility to crush the steelmaking slag and to remove sulfur by aging a product that has removed mixed substances for a certain period of time. It is starting.

It is an object of the present invention to provide a method for producing aggregates used in the manufacture of building materials, such as building exterior materials, using acid sludge and reducing machine slag, which are problematic during processing.

The present invention

Homogeneously mixing the reducer slag and the acid sludge at a weight ratio of 30 to 90:70 to 10;

Shaping the mixed blend; And

Curing the molded formulation at a relative temperature of 90% or more at room temperature

It relates to a method for producing aggregate using a reducing machine slag and acid sludge containing.

Hereinafter, the present invention will be described in more detail.

First, the reducing element slag components generated in the steelmaking process is shown in Table 1 below.

TABLE 1

Constituents of Reducing Slag (Unit: wt%)

CaO MgO T-Fe SiO ₂ MnO TiO ₂ Cr ₂ O ₃ ZnO P ₂ O ₅ 42-53 6.0-18.0 0.1-6.9 4.5-20.0 0.1-1.8 0.2-0.8 0.5-2.7 0.1-0.2 0.01 ~ 0.2

In the present invention, the production of aggregates used in building construction materials by mixing the reducing machine slag generated in the steelmaking process and the pickling sludge generated in the pickling process during the production of special steel products in a constant mixing ratio.

As a result of analyzing the components of the reducing group slag, it can be seen that the main components are calcium oxide and silicate, and since the amount of calcium oxide is the highest, it is alkaline when reacted with water. In addition, the analysis of the crystalline phase constituting the reducing group slag through X-ray diffraction analysis shows that a large amount of hydraulic phases such as calcium silicate, mayenite, gelenite, etc. are present.

Reducing group slag used in the present invention is preferably prepared by powder separation or less than 100 mesh through the sieving process to remove the iron powder as much as possible before mixing with the acid sludge.

When the powder reducing group slag is mixed with acid sludge, the reducing group slag powder acts as a binder while absorbing the moisture of the acid sludge. Accordingly, as the amount of reducing group slag increases, the strength of the aggregate produced increases. It is understood.

In the pickling sludge used in the production of the aggregate of the present invention, the solid components of the sludge generated in the pickling treatment process such as special steel pipes and coils are shown in Table 2 below.

TABLE 2

Components of Special Steel Pickling Process Wastewater Treatment Sludge (Unit: wt%)

Ca Mg Fe Al Cr Ni Na Si Mn 10-27 0.2-0.9 15-28 0.1-3.2 2.0 ~ 11 1.0 ~ 4.0 0.1-0.5 0.3-2.2 0.2-9.7

Pickling sludge used in the present invention contains about 50 to 90% of moisture, and the main acid component is derived from hydrochloric acid, sulfuric acid, and the like. Generally, pickling sludge for use as aggregate is produced by heat treatment at a high temperature of 1000 ° C. or higher to evaporate moisture and is produced through a sintering process. In the present invention, the pickling sludge generated in the pickling process without any pretreatment may be used as it is.

The reduced slag and acid sludge treated as described above are mixed into any mixer such as a cup mixer or a refining machine at a desired mixing ratio, and then formed into pellets or any shape. After molding the blend as described above to cure at room temperature with a relative humidity of 90% or more to prepare an aggregate.

Aggregate prepared by mixing the reducing machine slag and the acid sludge according to the present invention has a compressive strength of 40kg / cm ² or more after curing, which satisfies the strength of the aggregate for building exterior materials.

The numerical limitation will now be described.

Reducing group slag used in the production of the present invention is 30 to 90% by weight of the total weight, when the reducing group slag is 30% by weight or less, the strength of the aggregate is weakened, when the reducing group slag is 90% by weight or more The treatment of acid sludge to be neutralized is not easy, and the alkalinity becomes high, which is a problem.

In order to manufacture the aggregate of the present invention, after curing the mixture, it is preferable to cure at a relative humidity of 90% or more. The higher the relative humidity is preferable, the less than 90% has a disadvantage in that the curing rate is slow and productivity is lowered. Of course, natural curing is not impossible, but it takes a long time and there is a fear that the curing rate becomes uneven according to the climate and the defective rate is high.

As described above, after molding the blended mixture at a specific blending ratio, it can be cured at 90% or higher relative humidity to obtain an aggregate that satisfies the strength as a building construction material.

Through the following examples will be described the present invention.

Example 1

First, by reducing the slag of charcoal slag to remove iron as much as possible, through the sieve process to produce a powder of less than 100mesh. Pickling sludge containing about 60% of water was mixed homogeneously using a kneader in accordance with the mixing ratio of Table 3 and the reducing slag prepared by weighing with water. The mixture was molded into 5 × 5 × 5 cm cubes, and the compressive strength was measured after curing at 23 degrees Celsius for 90 days at 90% relative humidity.

TABLE 3

Reducing device slag (weight ratio) Pickled sludge (weight ratio) Compressive Strength (Kg / cm ² ) 1 2 3 4 5 98765 5.1422.141.757.470.2

According to the results, the reducing group slag is 30% by weight or more, and when combined with acid sludge, when cured, the compressive strength can be 40 Kg / cm ² or more, which satisfies the strength standards of aggregates for building exterior materials will be.

Example 2

The molded product prepared in Example 1 was crushed to make a sample of 0.5 to 5 mm, and the weight ratio of the sample to distilled water was 1:10. After shaking for 6 hours, the pH was measured.

    TABLE 4

Reducing device slag (weight ratio) Pickled sludge (weight ratio) pH 1 2 3 4 5 98765 8.488.999.2610.2110.43

The pH of the pickling sludge generated in the neutralization process of pickling wastewater is almost in the neutral region.However, when the aggregate is manufactured through the sintering process, the unreacted acid solution is concentrated in the evaporated vapor, which is acidic enough to be treated separately. have. However, when the aggregate is prepared using the reducing machine slag as in Example 2, the aggregate shows that the eluate is alkaline.

Compared with the conventional sintering process, the energy cost can be greatly reduced, very inexpensive in terms of equipment, and no acidic steam treatment equipment is required. In addition, it can be said that it is an environmentally friendly method in that it can be used together with the acid sludge and the reducing group slag disposed in the prior art without a suitable use.

Claims (1)

Homogeneously mixing the reducer slag and the acid sludge at a weight ratio of 30 to 90:70 to 10; Shaping the mixed blend; And Curing the molded formulation at a relative temperature of 90% or more at room temperature Aggregate manufacturing method using acid sludge and reducing machine slag comprising