KR20130022843A - Non-sintering slag cement composite using byproduct of iron and steel - Google Patents

Abstract

PURPOSE: A non-sintered slag cement composite using byproducts of steel is provided to obtain excellent compressive strength without performing a plastic process by containing molten iron pretreated slag and blast furnace slag at an optimal ratio. CONSTITUTION: A non-sintered slag cement composite using byproducts of steel comprises 5-50 weight% of molten iron pretreated slag and a remaining content of blast furnace slag. The cement composite additionally includes 0.1-10 weight% of gypsum. The cement composite comprises 30-60 weight% of CaO, 20-45 weight% of SiO2, 5-15 weight% of Al2O3, 0.1-5 weight% of MgO, and 1.5-10 weight% of SO3. The molten iron pretreatment slag is a powder with the fineness of 3000-10000 cm^2/g. The molten iron pretreated slag contains 50-80 weight% of Ca(OH)2. The molten iron pretreated slag contains 0.1-10 weight% of SO3. The gypsum comprises 30-45 weight% of CaO, 30-65 weight% of SO3, and a remaining content of water. [Reference numerals] (AA) Compressive intensity(N/m^2); (BB) 7 days; (CC) 28 days; (DD) Comparative embodiment 1; (EE) Comparative embodiment 2; (FF) Embodiment 1; (GG) Embodiment 2; (HH) Embodiment 3; (II) Embodiment 4; (JJ) Embodiment 5

Description

Non-fired slag cement composition using steel by-products {NON-SINTERING SLAG CEMENT COMPOSITE USING BYPRODUCT OF IRON AND STEEL}

The present invention relates to a non-fired cement composition using by-products generated in the steel process, and more particularly to a non-fired slag cement composition that exhibits excellent strength without undergoing a firing process.

In general, in the steel manufacturing process, the main raw materials of water are divided into coal and iron ore. The blast furnace is the place where iron ore and coal reduce and remove iron from iron ore. The chemical reaction inside the blast furnace melts at high temperature simultaneously with the reduction and flows into the waste water, and other residues, ie blast furnace slag, are separated separately.

Blast furnace slag generated in such a steelmaking process is discharged into granules of less than 5mm by high pressure spray cooling when discharged, and when it is powdered, there are ways to use it as a concrete admixture and slag cement material. .

Blast furnace granulated slag fine powder when contact with water, but not the reaction directly, the hydroxyl ion (OH ^-) and sulfate _{^{(SO 4 2 -, S 2}} O 3) when making contact as is the nature of the reaction (curing) (latent hydraulic Has)

In addition, after the steelmaking process and before continuing to the steelmaking process, impurities such as sulfur components in the molten iron are removed through molten iron preliminary treatment. The slag generated at this time is called molten iron preliminary slag. The molten iron pretreated slag has high basicity, and generally contains about 50% to 60% of CaO and 3% to 5% of S. In addition, it is discharged in the form of powder because it is self-differentiated when it occurs.

In general, since the cement is subjected to high temperature firing at 1450 ° C., carbon dioxide (CO ₂ ) is generated as shown in the following reaction by decarbonation of limestone as a raw material.

Scheme: CaCO _3- > CaO + CO ₂

Such blast furnace slag and charter pre-treatment slag are generated as by-products of the steel industry, and binders capable of hydrating (curing) by reacting with water are possible when properly combined. If it can be used to produce non-calcined cement, the amount of carbon dioxide generated by about 0.85 ton per ton of cement firing can be greatly reduced.

Therefore, there is an increasing demand for cement compositions that can utilize high added value of steel byproducts and, in addition, reduce the amount of carbon dioxide generated during cement firing. However, there is no such research, and there is a need for research on non-plastic cement compositions.

According to one aspect of the invention, to provide a non-baking slag cement composition prepared by combining the by-products generated in the steel process.

The non-fired slag cement composition using steel by-products, which is an aspect of the present invention, includes molten preliminary slag: 5-50% by weight and the remaining blast furnace slag.

The cement composition may further comprise 0.1-10% by weight of gypsum.

The cement composition includes CaO: 30-60 wt%, SiO ₂ : 20-45 wt%, Al ₂ O ₃ : 5-15 wt%, MgO: 0.1-5 wt% and SO ₃ : 1.5-10 wt% It is desirable to.

The molten iron preliminary slag is in the form of a powder, the powder degree is preferably 3000-10000 cm 2 / g.

The molten iron preliminary slag preferably contains Ca (OH) ₂ : 50-80% by weight.

The molten iron preliminary slag preferably contains SO ₃ : 0.1-10% by weight.

The gypsum preferably comprises CaO: 30-45% by weight, SO ₃ : 30-65% by weight and the balance.

The cement composition, which is an aspect of the present invention, may exhibit an equivalent level or higher compressive strength even without performing a sintering process as compared with conventional general portland cement.

Overall, blast furnace slag and charter preliminary slag, which are by-products of the steel industry, can be utilized in large quantities, and cement replacement effect is possible. In addition, the amount of carbon dioxide generated by about 0.85 tonnes per tonne in cement production can be significantly reduced.

1 is a graph comparing the compressive strength of Comparative Examples 1 and 2 and Inventive Examples 1 to 5.
Figure 2 is a graph comparing the compressive strength of Comparative Example 1 and Inventive Examples 6 to 9.

The present invention is a cement composition using the molten iron pre-treated slag, blast furnace slag produced as a by-product of the steel industry, it is possible to provide a cement having excellent compressive strength without going through a firing process.

Hereinafter, the non-baking cement composition which is one side of this invention is demonstrated in detail.

The cement composition of the present invention is a composite composition including molten iron preliminary slag and blast furnace slag, and additionally gypsum, and may provide cement having a high compressive strength without performing a firing process.

As described above, the molten iron preliminary slag refers to the slag generated when the impurities such as sulfur and phosphorus are removed from the molten iron during the molten iron preliminary process after the steelmaking process. In the present invention, the molten iron pretreated slag in the total cement composition is controlled to 5-50% by weight. When the content of the molten iron pretreated slag is less than 5% by weight, there is a problem in that the reactivity with water or blast furnace slag is weak. In addition, when the content of the molten iron pre-treated slag exceeds 50% by weight, a surplus of the molten iron pre-treated slag is generated, rather the strength is lowered.

In addition, the molten iron pre-treated slag is preferably added to the powder. At this time, the fineness of the molten iron pre-treated slag powder is contained when the water input and Ca (OH) OH from the _second ^{in-production} of, thiosulfate (S ₂ O ₃₎ of the SO ₄ ^{2 -} the transition to such smooth progress It is preferable that it is 3,000 cm <2> / g-10,000 cm <2> / g in order to become. That is, when the powder of the molten iron pretreated slag powder is also 3,000 cm 2 / g or more, the reaction becomes easy, and when it exceeds 10,000 cm 2 / g, the reaction rate is too fast, exothermic phenomenon may occur, rapid condensation may appear. .

In addition, the molten iron pre-treated slag preferably contains 50 to 80% by weight of Ca (OH) ₂ . The Ca (OH) ₂ is less than 50% by weight, the OH ^- if and the extent to which stimulates blast furnace slag, even if the ions are eluted weak, is more than 80% by weight, OH ^- Since the ions are already saturated, the additional OH ^- dissolution of the ions does not proceed. In addition, the molten iron pre-treated slag preferably contains 0.1 to 10% by weight of SO ₃ .

The balance of the cement composition of the present invention is blast furnace slag. Conventional blast furnace slag forms amorphous by water spray cooling, and Ca. Si, Al ions are included. When blast furnace slag fine powder added to the water in, the amorphous film is formed on the powder surface, the internal Ca ^2+, does not elute, such as Al ^{2 +} done. If, however, the incorporation of the molten iron pre-treated slag, water and reaction, Ca, which contains the molten iron pre-treated slag (OH) The OH produced from ^_2- and thiosulfate inside (S ₂ O ₃₎ is SO ₄ ^{2 -} It is converted into a sulfate such as, to destroy the blast furnace slag amorphous coating to facilitate the elution of Ca ^{2 +} , Al ^{2 +,} etc., so that the eluted ions produce CaO-SiO ₂ -H ₂ O-based hydrates, etc. by and curing begins, excess sulfur dioxide is in by generating an ettringite (ettringite) hydration products _{(3CaO · Al 2 O 3 ·} CaSO 4 · 12H 2 O) having a structure of needle shaped densifying the internal hydrated body tissue Can be cured.

Gypsum can be replaced with a portion of the blast furnace slag to further improve the effect of the invention. The content is preferably included in 0.1-10% by weight of the cement composition. The gypsum is more preferably contained in 1-7% by weight.

And that by eluting the sulfate or the like, to destroy the amorphous film of the blast-furnace slag fine powder facilitates the dissolution such as Ca ^{2 +,} Al ^{2 +, -} the plaster is SO ₄ ² by water and the reaction of CaSO ₄ ingredients in the present invention eluting ions-SiO ₂ -H ₂ O-based CaO being to generate a hydrate, such as beginning to cure, excess sulfur dioxide is ettringite hydrated product having a structure of needle shaped _{(3CaO · Al 2 O 3 ·} CaSO 4 · 12H ₂ O) to densify the tissue inside the receiver. In addition, when the gypsum content is less than 0.1 parts by weight, the effect of the blast furnace slag fine coating is insignificant. When the content of the gypsum exceeds 10 parts by weight, the ettringite hydration product (3CaOAl ₂ O ₃ CaSO ₄ · 12H Overproduction of ₂ O) may cause expansion cracks of the cured product. Here, the gypsum preferably comprises 30 to 45% by weight of CaO, 30 to 65% by weight of SO ₃ and the balance.

As described above, the cement composition comprising the molten iron pre-treated slag and the blast furnace slag, and additionally gypsum, is based on the composition as a whole, CaO: 30-60% by weight, SiO ₂ : 20-45% by weight, Al ₂ O ₃ : 5 -15 wt%, MgO: 0.1-5 wt% and SO ₃ : 1.5-10 wt%. In the case of the above-described molten iron pre-treated slag and blast furnace slag, in addition to the gypsum can satisfy the content of CaO, SiO ₂ , Al ₂ O ₃ , MgO and SO ₃ .

The cement composition comprising the above components can be used as a cement composition even without performing the firing step, and can achieve a compressive strength equal to or greater than that of conventional cement.

Hereinafter, the present invention will be described more specifically by way of examples. It should be noted, however, that the following examples are intended to illustrate the invention in more detail and not to limit the scope of the invention. The scope of the present invention is determined by the matters set forth in the claims and the matters reasonably inferred therefrom.

(Example 1)

As shown in Table 1, 1800 g of cement composition satisfying the content of the molten iron slag and blast furnace slag, 900 g of water and 5400 g of sand were mixed to prepare cement, and the compressive strength thereof was measured and shown in Table 1 below.

In addition, as a comparative example, the compressive strength of cement prepared by mixing 1800 g of 1 type ordinary portland cement, 900 g of water, and 5400 g of sand, 1800 g of 100% blast furnace slag, 900 g of water, and 5400 g of sand was mixed. Was measured and shown in Table 1 together.

In addition, the fabrication and strength evaluation methods of the examples were evaluated according to KS L ISO 679 'Cement Strength Test Method', and the compressive strength was measured on the 7th and 28th days. The average value is expressed as the compressive strength value.

In addition, a graph comparing the compressive strengths of Comparative Examples 1 and 2 and Inventive Examples 1 to 5 is shown in FIG. 1.

division cement
(weight%) Blast furnace slag
(weight%) Charter preliminary slag
(weight%) Compressive strength (N / ㎡) 7 days 28 days Comparative Example 1 100 0 0 41 53 Comparative Example 2 0 100 0 2 4 Inventory 1 0 90 10 15 35 Inventive Example 2 0 80 20 24 39 Inventory 3 0 70 30 39 48 Honorable 4 0 60 40 43 52 Inventory 5 0 50 50 33 41

As shown in Table 1 and FIG. 1, when the molten iron preliminary slag was not mixed in the blast furnace slag fine powder (Comparative Example 2), it was confirmed that the strength was hardly expressed.

However, when 10 to 50 parts by weight of molten iron preliminary slag was replaced in the blast furnace slag powder, the compressive strength was expressed to some extent, and in Example 4 including 40 wt% of the molten iron preliminary slag, the compressive strength value similar to that of Comparative Example 1 was obtained. It could be confirmed that.

(Example 2)

In addition, as shown in Table 2, 1800g of cement composition and 900g of water and 5400g of sand were mixed to satisfy the component content of the molten iron preliminary slag and blast furnace slag to prepare cement, and the compressive strength thereof was measured. It was.

In addition, the fabrication and strength evaluation methods of Examples were evaluated according to KS L ISO 679 'Cement Strength Test Method', and the compressive strength was measured on 7 and 28 days. The average value is expressed as the compressive strength value.

In addition, a graph comparing the compressive strengths of Comparative Example 1 and Inventive Examples 6 to 9 is shown in FIG.

division cement
(weight%) Blast furnace slag
(weight%) Charter preliminary slag
(weight%) gypsum
(weight%) Compressive strength (N / ㎡) 7 days 28 days Inventory 6 0 75 20 5 38 51 Honorable 7 0 70 20 10 42 54 Inventive Example 8 0 65 30 5 43 57 Proposition 9 0 60 30 10 48 56

As shown in Table 2, when the gypsum was further included, it was confirmed that the compressive strength value is better. In FIG. 2, the compressive strength values of Comparative Example 1 and Inventive Examples 6 to 9 may be compared. It can be confirmed that the compressive strength equivalent to or higher than that of conventional cement is expressed.

Claims (7)

In the non-fired slag cement composition using steel by-products,
Hot-rolled slag: Non-fired slag cement composition comprising 5-50% by weight and the balance blast furnace slag.
The method according to claim 1,
The cement composition is a non-plastic slag cement composition, characterized in that it further comprises 0.1-10% by weight of gypsum.
The method according to claim 1,
The cement composition includes CaO: 30-60% by weight, SiO ₂ : 20-45% by weight, Al ₂ O ₃ : 5-15% by weight, MgO: 0.1-5% by weight and SO ₃ : 1.5-10% by weight Non-fired slag cement composition.
The method according to claim 1,
The molten iron pre-treated slag is in the form of a powder, the powder degree is non-fired slag cement composition, characterized in that 3000-10000cm 2 / g.
The method according to claim 1,
The molten iron pre-treated slag is Ca (OH) ₂ : non-baking slag cement composition, characterized in that it comprises 50-80% by weight.
The method according to claim 1,
The molten iron pre-treated slag is non-baking slag cement composition, characterized in that it comprises SO ₃ : 0.1-10% by weight.
The method according to claim 2,
The gypsum is CaO: 30-45% by weight, SO ₃ : 30-65% by weight and the non-fired slag cement composition, characterized in that the balance.

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