KR101610648B1 - Blast furnace slag agent - Google Patents

Abstract

More particularly, the present invention relates to a blast furnace slag fine powder composition, which is obtained by blending a blast furnace slag having a pH of 11.5 or more with natural anhydrous gypsum and having a specific surface area of 3,500 to 10,000 cm ² / g, To a blast furnace slag fine powder composition capable of improving initial strength.
The blast furnace slag fine powder composition capable of improving the neutralization resistance and initial strength according to the present invention comprises 1 to 20 parts by weight of Petro coke oven material and 0.5 to 10 parts by weight of natural anhydrous gypsum based on 100 parts by weight of blast furnace slag, And a specific surface area of 3,500 to 10,000 cm ² / g.

Description

[0001] BLAST FURNACE SLAG AGENT [0002] The present invention relates to a blast furnace slag fine powder composition capable of improving neutralization resistance and initial strength,

More particularly, the present invention relates to a blast furnace slag fine powder composition, which is obtained by blending a blast furnace slag having a pH of 11.5 or more with natural anhydrous gypsum and having a specific surface area of 3,500 to 10,000 cm ² / g, To a blast furnace slag fine powder composition capable of improving initial strength.

Approximately 8% of CO ₂ emissions, which account for 55% of greenhouse gases, are emitted in Portland cement manufacturing. Portland cement consumes a large amount of energy because it is produced through melting process at high temperature (about 1,450). When 1 ton of Portland cement is manufactured, about 1.13 tons of limestone is consumed and about 130 kg of bituminous coal needed for calcining of clinker is consumed do. The resulting carbon dioxide emissions are about 0.50 tonnes in the calcining stage of limestone, about 0.40 tonnes in the calcining process through the burning of fossil fuels, resulting in about 0.9 tonnes of carbon dioxide per tonne of Portland cement produced.

Therefore, the future greenhouse gas reduction will become the biggest issue in the portland cement industry.

As a countermeasure against this problem, it is necessary to develop technology that can minimize the amount of portland cement by utilizing a large amount of blast furnace slag, which is generated as a byproduct of the steel industry. Generally, a blast furnace slag fine powder produced by finely grinding blast furnace slag is partially used in portland cement. The blast furnace slag fine powder is potentially hydraulic and has a weak curing property. That is, when mixed with Portland cement, after the calcium hydroxide which is the hydration product of the cement is produced, the granulated blast furnace slag is cured by the stimulation. As a result, the reaction of blast furnace slag fine powder starts secondarily. Therefore, when blast furnace slag fine powder is mixed with Portland cement, problems such as delayed coagulation, initial strength reduction, and neutralization are caused.

Due to such a phenomenon, there may arise problems such as delays in form demoulding, deterioration of initial strength quality, deterioration of long-term durability due to neutralization, etc., and the content of blast furnace slag fine powder is adjusted to 20 to 40 wt% with respect to 100 wt% of Portland cement have.

Therefore, if the existing problems of blast furnace slag fine powder can be remedied, it is expected that not only the production cost will be reduced due to the reduction of the cement usage amount, but also the natural resource and energy exhaustion problem and the environmental pollution problem due to the carbon dioxide emission can be solved at the same time.

On the other hand, as the demand for refined petroleum products increased, the potential for growth continued, and the gradual quality deterioration of crude oil led to the need for more petroleum coke raw materials, the production of petrol coke combustion desulfurization process by- This study is needed to find out how to utilize. Petro coke ovens are a by-product of the mixed combustion of petroleum coke and limestone in a combined heat and power plant operating a fluidized-bed boiler for in-furnace desulfurization. As a by-product of decarboxylation and desulfurization of limestone, CaO and CaSO ₄ , It is a strong alkaline substance with a pH of 11.5 or higher and can be used as a binder and a stimulant when used together with blast furnace slag.

Recently, a technique using an alkali activated slag to reduce the use of portland cement has recently been proposed. This technique stimulates the amorphous material that can be activated, such as blast furnace granulated slag and fly ash in a strong alkali chemicals such as NaOH, KOH, Na ₂ CO _3, Na ₂ SiO _3, and exhibited the same characteristics as normal cement, high water-tightness and heat resistance Studies have been reported that binders can be made. However, such an alkali-activated slag is poor in economical efficiency because the drug used as a stimulant is too expensive, is easily carbonated due to the characteristics of its strength-inducing mechanism, is poor in durability, and has strong irritating strong alkali to such an extent that the pH of the irritant exceeds 13 Therefore, it is difficult to treat as a powder as a raw material having high deliquescence which is easily dissolved when exposed to the atmosphere, and therefore has a problem that it must be liquefied and used.

In order to improve the problem of the above-mentioned alkali chemical irritant and to secure economical efficiency by utilizing industrial byproducts, Korea Patent No. 10-1223888 discloses that 70-90 parts by weight of blast furnace slag powder, 5-25 parts by weight of desulfurization slag, By weight based on the total weight of the blast furnace slag.

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a blast furnace slag, which is obtained by mixing petroleum coke oven material and natural anhydrous gypsum having a pH of 11.5 or more and having a specific surface area of 3,500 to 10,000 cm ² / To thereby improve the neutralization resistance and the initial strength of the blast furnace slag.

In order to solve the above technical problem, a blast furnace slag fine powder composition capable of improving neutralization resistance and initial strength according to the present invention comprises 1 to 20 parts by weight of a Petro coke oven material, 100 parts by weight of natural anhydrous gypsum, 0.5 to 10 parts by weight, and a specific surface area of 3,500 to 10,000 cm ² / g.

The granulated blast furnace slag has SiO ₂ 20 ~ 40 _{wt%, Al 2 O 3 10 ~} 25 wt%, CaO 35 ~ 48 wt%, MgO 2 ~ 12% by _{weight, Fe 2 O 3 0.01 ~ 2.0} % by weight, SO ₃ 0.01 To 5% by weight.

In addition, the Petro coke oven material is generated in a desulfurizing process of a fluidized-bed boiler using petro coke as fuel, and has a loss on ignition of 10% or less, 0.01 to 4.0 wt% of SiO _2, 0.01 to 3.0 wt% of Al ₂ O ₃ , To 80 wt%, MgO 0.01 to 3.0 wt%, Fe ₂ O ₃ 0.1 to 3.0 wt%, and SO ₃ 15 to 30 wt%.

In addition, the natural anhydrite is SiO ₂ 0.01 ~ 3% by weight, Al ₂ O ₃ 0.01 ~ ₂ wt%, CaO 35 ~ 48% by weight, MgO 0.01 ~ 3% by weight, Fe ₂ O ₃ 0.01 ~ 1.5 wt%, SO ₃ By weight and 45 to 60% by weight.

And further comprising 1 to 10 parts by weight of a strength-improving agent for improving the strength of 100 parts by weight of the blast furnace slag, wherein the strength-improving agent is selected from the group consisting of silica, feldspar, granite, limestone, dolomite, It is preferably one or a mixture of two or more selected.

According to the present invention, it is possible to solve the problems such as the delay of congealing, initial strength reduction, and neutralization of concrete caused by incorporation of a large amount of blast furnace slag fine powder.

In addition, it can reduce production cost by reducing cement usage, solve natural resource and energy depletion problem, and solve environmental pollution problem by carbon dioxide emission.

Hereinafter, the binder according to the present invention will be described in detail.

The blast furnace slag fine powder composition capable of improving the neutralization resistance and initial strength according to the present invention comprises 1 to 20 parts by weight of petroleum coke oven material and 0.5 to 10 parts by weight of natural anhydrous gypsum based on 100 parts by weight of blast furnace slag, Blast furnace slag, petro coke oven material and natural anhydrous gypsum at a specific surface area of 3,500 to 10,000 cm ² / g.

 The blast furnace slag is a by-product obtained by quenching the slag in a hot molten state, which is generated as a by-product in a steel blast furnace process. The blast furnace slag fine powder obtained by pulverizing the blast furnace slag is formed into an amorphous coating upon contact with water, so that the blast furnace slag fine powder is referred to as a latent hydraulic material because it does not react hydration by itself. The amorphous coating must be destroyed in order for the latent hydraulic properties to be exerted.

The granulated blast furnace slag has SiO ₂ 20 ~ 40 _{wt%, Al 2 O 3 10 ~} 25 wt%, CaO 35 ~ 48 wt%, MgO 2 ~ 12% by _{weight, Fe 2 O 3 0.01 ~ 2.0} % by weight, SO ₃ 0.01 To 5% by weight.

The petro coke oven material is produced in the furnace desulfurization process by mixing petroleum coke with petroleum coke or coal with limestone in a pressurized fluidized bed boiler using fuel as a fuel.

In the desulfurization process of a circulating fluidized bed boiler using petro coke as a fuel, limestone is injected into the combustion chamber and burned together with the fuel, so that sulfur dioxide and limestone in the combustion gas react in the furnace to remove sulfur in the combustion gas and produce anhydrous gypsum. And unreacted limestone is decarboxylated and transferred to the quicklime component and discharged. As a result, the PetroCox desulfurization process by-product is composed of CaO and CaSO ₄ components and is a strong alkaline substance having a pH of 11.5 or more. When used as blast furnace slag, it has a property of simultaneously acting as a binder and a stimulant.

When water is introduced into a conventional blast furnace slag, an amorphous film is formed on the surface, and the internal Ca ^{2 +} , Al ^{3 +} and the like are not eluted. However, when water is added after mixing petroleum coke oven material, the CaO component contained in the petroleum coke combustion material reacts with water to convert it into Ca (OH) ₂ , resulting in OH ^- and SO ₄ ^{2 -} The component breaks down the amorphous film of the blast furnace slag, thereby facilitating elution of Ca ^{2 +} , Al ^{3 +} , and the like, and the elution ions generate CaO-SiO ₂ -H ₂ O-based hydrate and the like, excess sulfur oxides eth- Lin gayiteu hydrated product having a structure of needle shaped (3CaO · Al ₂ O ₃ CaSO _{4 ·} 2H ₂ O) generated by the densification of the body inside the tissue hydration may enhance the compressive strength of the cured product.

In addition, the petro coke oven material has a CaO content of 50% or more, which is converted into Ca (OH) ₂ by reaction with water and plays a very important role in preventing the neutralization of the blast furnace slag. When the Ca (OH) ₂ component is insufficient, the generation of CSH hydrate is reduced in the long-term action, and the compressive strength is lowered, and the neutralization of the concrete is accelerated and the neutralization resistance function necessary for preventing corrosion .

In addition, the pure CaO present in petro coke oven material reacts with water, absorbs, exotherms and expands to form Ca (OH) _2. The reaction equation is as follows. The volume expands about 1.99 times.

CaO + H ₂ O-> Ca (OH) ₂ + 15.6 kcal mol ^-1

Therefore, the pure CaO component reacts with water to convert it to calcium hydroxide and also acts as an alkali stimulant of blast furnace slag. However, due to the increase in temperature due to heat generation, the hydration reaction of blast furnace slag is promoted and the effect of compensating the volume shrinkage of the hardened body, .

The petroleum coke oven material is preferably mixed with 1 to 20 parts by weight of petroleum cokes based on 100 parts by weight of the blast furnace slag. When the amount is less than 1 part by weight, the effect is not exhibited. When the amount is more than 20 parts by weight, The number of ingredients may increase and excessive heat and swelling may occur.

Petro coke oven should be used with a loss on ignition of 10% or less. Usually, when the blower of the boiler is operated at a slow speed, the air supply rate is reduced to lower the combustion efficiency of the petro coke and produce a combustion material having a large amount of unburned carbon. Such a soft material is relatively porous and has an amorphous nature such as activated carbon So it adsorbs air entraining agent (AE agent). Therefore, the use of Petro coke oven material with ignition loss exceeding 10% is very disadvantageous in terms of economical efficiency since the amount of air entraining agent must be increased in order to make the amount of air to be conveyed constant when manufacturing AE concrete. Also, when the ignition loss exceeds 10%, there is a large amount of unburned carbon powder, which is black when mixed with water and may give a disgust in the field.

The petroleum coke oven may further contain 0.01 to 4.0 wt% of SiO _2, 0.01 to 3.0 wt% of Al ₂ O ₃ , 50 to 80 wt% of CaO, 0.01 to 3.0 wt% of MgO, 0.1 to 3.0 wt% of Fe ₂ O ₃ , ₃ 15 to 30% by weight, and is preferably generated during a desulfurization process of a fluidized bed boiler using petro coke as fuel.

The natural anhydrous gypsum serves as a sulfate stimulant for the blast furnace slag. SO ₄ ² of the natural anhydrous gypsum ^- is the blast furnace to destroy the amorphous film of the granulated slag is easy to elute, such as Ca ^{2 +,} Al ^{3 +,} eluted ions are generated and the like based CaO-SiO ₂ -H ₂ O hydrate (3CaO · Al ₂ O ₃ · 3CaSO ₄ · 32H ₂ O) having a needle-shaped structure, thereby densifying the structure of the hydrated body to form hydrated products of the cured body The compression strength can be improved.

The natural anhydrous gypsum preferably contains 0.5 to 10 parts by weight based on 100 parts by weight of the blast furnace slag. If the amount is less than 0.5 part by weight, the effect is insufficient. If the amount is more than 10 parts by weight, the excess gypsum component which has not reacted with the blast furnace slag is aggregated between the hydration products to weaken the bonding strength thereof.

In addition, the gypsum can be classified into two types, ie, CaSO ₄ · H ₂ O, CaSO ₄ · 1 / 2H ₂ O, and CaSO ₄ , It is desirable to use anhydrous gypsum because it can delay the condensation of the cement when the fine powder is mixed with the Portland cement and the semi-gypsum can cause streaking.

In addition, there are various forms of gypsum such as natural gypsum, flue gas desulfurization gypsum, and chemical gypsum gypsum. However, since the flue gas desulfurization gypsum and chemical gypsum gypsum must undergo a pretreatment process such as drying and firing, they are not economical. Therefore, it is preferable to use natural anhydrous gypsum, and since it exists in a massive form, fine pulverization is possible at the same time as blast furnace slag.

In addition, the natural anhydrite is SiO ₂ 0.01 ~ 3% by weight, Al ₂ O ₃ 0.01 ~ ₂ wt%, CaO 35 ~ 48% by weight, MgO 0.01 ~ 3% by weight, Fe ₂ O ₃ 0.01 ~ 1.5 wt%, SO ₃ By weight and 45 to 60% by weight.

Further, it is preferable that the blast furnace slag, the petroleum coke oven material and the natural anhydrous gypsum are mixed and finely pulverized to have a specific surface area of 3,500 to 10,000 cm ² / g. If the specific surface area is less than 3,500 cm ² / g, the activity is lowered and the initial strength is greatly lowered. If the specific surface area is more than 10,000 cm ² / g, the activity is improved and the strength is improved. However, in the pulverization and dust- .

Also, it is preferable that 1 to 10 parts by weight of a strength-enhancing agent for improving the strength is further added to 100 parts by weight of the blast furnace slag, and then the mixture is finely pulverized. The strength enhancer is preferably selected from silica, feldspar, granite, limestone, dolomite, It is preferably one or a mixture of two or more selected from the group consisting of calcium hydroxide, calcium hydroxide, calcium hydroxide, calcium hydroxide and calcium carbonate.

It is economically preferable that the strength-enhancing agent serves as a stimulant and filler for the blast furnace slag, and the mill-shaped product is finely pulverized at the same time as the blast furnace slag.

Hereinafter, preferred embodiments and comparative examples of the present invention will be described. The following examples are intended to illustrate the invention and should not be construed as limiting the scope of the invention.

Comparative Example

Only blast furnace slag was pulverized to prepare a blast furnace slag having a specific surface area of 4,260 cm ² / g. 100 parts by weight of the blast furnace slag cement prepared by mixing the blast furnace slag fine powder thus prepared with one kind of ordinary Portland cement in a weight ratio of 1: 1 was mixed with 300 parts by weight of ISO standard yarn of 50 parts by weight to prepare a cement- The compressive strength was measured according to time and is shown in Table 1. At this time, the molded product preparation and the strength evaluation method in each of the above examples were evaluated in accordance with KS L ISO 679 "Cement Strength Test Method ", and the compressive strengths were measured at 3 days, 7 days and 28 days and 90 days. The average value of the three test specimens measured on the day of measurement was expressed as the compressive strength value. In order to measure the neutralization resistance, the cured product of aged 28 days was set to 20 ± 3 ° C, relative humidity of 60 ± 5% and CO ₂ concentration of 10 ± 2% Are shown in Table 2.

Example  One

10 parts by weight of petroleum cokes and 5 parts by weight of natural anhydrous gypsum were homogeneously mixed and finely pulverized with respect to 100 parts by weight of blast furnace slag to prepare a blast furnace slag fine powder having a specific surface area of 4,260 cm ² / g. 100 parts by weight of the blast furnace slag cement prepared by mixing the blast furnace slag fine powder thus prepared with one kind of ordinary Portland cement in a weight ratio of 1: 1 was mixed with 300 parts by weight of ISO standard yarn of 50 parts by weight to prepare a cement- The compressive strength was measured according to time and is shown in Table 1. The neutralization depth was measured under the same conditions as those of the comparative example, and is shown in Table 2.

Example  2

20 parts by weight of Petro coke oven material, 10 parts by weight of natural anhydrous gypsum and 10 parts by weight of limestone were homogeneously mixed with 100 parts by weight of blast furnace slag to prepare a blast furnace slag powder having a specific surface area of 4,430 cm ² / g. 100 parts by weight of blast furnace slag cement prepared by mixing 2 parts by weight of the blast furnace slag fine powder thus prepared and 1 part ordinary Portland cement were mixed with 300 parts by weight of ISO standard yarn of 50 parts by weight to prepare a cement molding, And the results are shown in Table 1. The neutralization depth was measured under the same conditions as those of the comparative example, and is shown in Table 2.

division Compressive strength 3 days
(MPa) Compressive strength 7 days
(MPa) Compressive strength 28 days
(MPa) Compressive strength 90 days
(MPa) Comparative Example 16.8 28.1 44.8 53.8 Example 1 20.2 31.2 48.6 60.2 Example 2 16.3 28.8 47.3 61.8

division Neutralization penetration depth
(mm) Comparative Example 4.4 Example 1 2.8 Example 2 4.2

As can be seen from the above Table 1, the comparative example is the compressive strength of a compact obtained by mixing fine powder of blast furnace slag produced by pulverizing only blast furnace slag with 1: 1 weight ratio of one kind of ordinary Portland cement. In Example 1, This is the compressive strength of a compact obtained by mixing powdered granulated blast furnace slag with petroleum coke mixture and natural anhydrous gypsum and finely pulverized blast furnace slag and 1 kind of ordinary portland cement in a 1: 1 weight ratio. In the case of Example 1, the compressive strength at 3 days ages showed an initial strength as high as about 20% as compared with Comparative Example 1, and higher strength than Comparative Example 1 at all ages after 7 days. It can be seen that when the blast furnace slag is mixed with petrocosus and natural anhydrous gypsum, the blast furnace slag powder is very effective in improving not only the initial strength but also the long term strength.

Example 2 is the compressive strength of a molded product obtained by mixing a blast furnace slag fine powder obtained by mixing petroleum coke oven material and natural anhydrous gypsum with blast furnace slag and finely pulverized and one kind ordinary Portland cement at a ratio of 2: 1 by weight. Although the blending amount of blast furnace slag powder was further increased and the amount of one kind of ordinary Portland cement was reduced, the strength was similar between 3 days and 7 days as compared with the comparative example. Able to know.

The depth of neutralization was smaller in the neutralization depth than in the comparative example in the case of Example 1 in which the present invention was applied and in the case of Example 2 the mixing amount of the blast furnace slag fine powder was higher than that of Comparative Example, And exhibited the same neutralization depth. This means that the neutralization resistance of the blast furnace slag fine powder is improved by the incorporation of Petro coke soft material having high pH.

Accordingly, in the case of having the composition of the present invention, even if the blast furnace slag is contained in a high content, the initial strength can be exhibited in a level similar to that of the one kind ordinary portland cement, and the neutralization resistance is improved. In addition, it is possible to reduce the amount of CO ₂ generated at the time of cement production, increase the amount of cheap blast furnace slag, and effectively recycle by-products of petrocoke desulfurization process.

Claims (5)

With respect to 100 parts by weight of blast furnace slag,
1 to 20 parts by weight of petroleum cokes,
0.5 to 10 parts by weight of natural anhydrous gypsum,
A specific surface area of 3,500 to 10,000 cm ² / g,
The granulated blast furnace slag has SiO ₂ 20 ~ 40 _{wt%, Al 2 O 3 10 ~} 25 wt%, CaO 35 ~ 48 wt%, MgO 2 ~ 12% by _{weight, Fe 2 O 3 0.01 ~ 2.0} % by weight, SO ₃ 0.01 To 5% by weight,
The petro coke ash is a by to or only petro cokes as fuel mixing petro coke and coal dual fuel and limestone in the pressurized fluidized-bed boiler the fuel is generated in the furnace desulfurization process, ignition loss is _{1 ~ 10%, SiO 2 0.01} ~ Al ₂ O ₃ 0.01 to 3.0 wt%, CaO 50 to 80 wt%, MgO 0.01 to 3.0 wt%, Fe ₂ O ₃ 0.1 to 3.0 wt%, and SO ₃ 15 wt% to 30 wt%
The natural anhydrite is SiO ₂ 0.01 ~ 3 _{wt%, Al 2 O 3 0.01 ~} 2 wt%, CaO 35 ~ 48 wt%, MgO 0.01 ~ 3% by weight, Fe ₂ O ₃ 0.01 ~ 1.5 wt%, SO ₃ 45 To 60% by weight based on the total weight of the blast furnace slag.

delete delete delete delete