KR20170015679A

KR20170015679A - Manufacturing Method of High Reactive Calcium Hydroxide Using Dry Hydration method

Info

Publication number: KR20170015679A
Application number: KR1020150107981A
Authority: KR
Inventors: 조진상; 조계홍; 최문관; 문기연; 안지환
Original assignee: 한국석회석신소재연구재단
Priority date: 2015-07-30
Filing date: 2015-07-30
Publication date: 2017-02-09

Abstract

The present invention relates to a method for producing a high specific surface area calcium hydroxide using ethylene glycol as a hydration reaction retarder. The method of the present invention has an effect of uniformly hydrating the granulated quicklime by granulating the ethylene glycol and the quicklime powder and imparting an appropriate inducing agent thereto. After the hydration reaction is completed, the high temperature drying is performed, And the specific surface area of the film is remarkably improved. In addition, since the manufacturing method of the present invention uses a dry hydration reaction, there is an effect of improving productivity and energy efficiency of a product because a grinding process for producing a calcium hydroxide powder product is not required.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for producing highly reactive calcium hydroxide using a dry hydration reaction,

The present invention relates to a process for preparing highly reactive calcium hydroxide using a dry hydration reaction.

Calcium hydroxide (calcium hydroxide (Ca (OH) ₂ ) can be produced by crushing limestone and then performing heat treatment at a temperature range of about 900 to 1100 ° C and reacting the calcium oxide with water. Such calcium hydroxide is used in various industries such as environmental purification, chemical industry, food additive, leather, and various fillers. The quality of prepared calcium hydroxide may be affected by the quality of quicklime, the type of hydration and the conditions of synthesis, and the particle size, particle shape, specific surface area and pore volume of the quality characteristics may be different. The hydration process can be roughly classified into wet hydration reaction and dried hydration reaction. The synthesis conditions include the temperature of water, the content of water, the kind and content of additives for controlling the hydration rate, Temperature and time. In addition, the most important property of quicklime affects the manifestation of the characteristics of slaked lime depending on the content of calcium oxide (CaO), which is a main mineral, and the degree of fine pulverization of quicklime.

In recent years, related policies for the conservation of natural environment and prevention of pollution have been announced and implemented around the world, and the emission standards of harmful gas emitted from various manufacturing processes, incinerators and power plants are strengthened. Calcium hydroxide has been widely used for the purification of harmful gas and it has been increasingly demanded for high functional calcium hydroxide which has high removal efficiency of harmful gas components compared to the unit usage amount due to the strengthening of environmental standards. The harmful gases that can be removed include SOx, NOx, HCl, and HF. In order to improve removal of these components, the pore volume is increased to increase the specific surface area of calcium hydroxide. Many studies have been conducted on the technology for manufacturing such a high specific surface area calcium hydroxide. The main synthesis factors are many synthesis methods depending on the type and amount of additive used. Generally, the specific surface enhancement technique has been introduced by wet hydration process using digestion water which is 4 times or more of the theoretical yield of calcium hydroxide production, 32%.

The patent documents and references cited herein are hereby incorporated by reference to the same extent as if each reference was individually and clearly identified by reference.

Korean Patent No. 10-0380983

As a result of efforts to develop a process for producing calcium hydroxide excellent in reactivity, the present inventors have found that when dry lime is dry-mixed with ethylene glycol, dry hydration reaction and high temperature drying are performed, the specific surface area is increased and calcium hydroxide having excellent reactivity can be produced The present inventors have completed the present invention.

Accordingly, an object of the present invention is to provide a method for producing calcium hydroxide having a high specific surface area.

Other objects and technical features of the present invention will be described in more detail with reference to the following detailed description, claims and drawings.

According to one aspect of the present invention, the present invention provides a method for producing calcium hydroxide having a high specific surface area comprising the steps of:

(a) adding ethylene glycol to the quicklime powder and mixing to prepare a mixture of ethylene glycol and quicklime powder;

(b) adding water to the mixture of ethylene glycol and quicklime to perform a hydration reaction; And

(c) drying the hydrated product.

The term " quicklime " in the present invention means produced by pulverizing and heat-treating limestone appropriately. In the quicklime, residual limestone (CaCO ₃ ), which remains as impurities without participating in the reaction during the heat treatment of limestone, may be present. The residual CaCO ₃ can act as a cause of reducing the specific surface area of calcium hydroxide in the process of preparing calcium hydroxide using quicklime. Therefore, in order to produce high-quality calcium hydroxide having high reactivity, it is preferable to remove the residual limestone, which is the impurity, and use the calcium oxide powder of high purity. As a pretreatment for removing the remnant limestone, a sieve with a mesh may be used and further pulverized for this purpose.

According to an embodiment of the present invention, the quicklime powder of the step (a) produced through the sieving process has a particle size of 200 mesh or less. Preferably, the quicklime powder has a particle size of 270 mesh or less. More preferably, the quicklime powder has a particle size of 325 mesh or less.

The most important point in the process of preparing calcium hydroxide through the hydration reaction of quicklime is to allow the hydration reaction to proceed at a uniform rate throughout the reactor. When the hydration reaction is carried out using massive lime, the rate of the hydration reaction may not be uniform depending on the state of the massive quicklime introduced into the reactor. The non-uniform reaction rate is disadvantageous in that the particles are excessively grown or the particle size of the burnt lime is not homogenized, so that sufficient pores are not formed in the calcium hydroxide. Therefore, in order to obtain calcium hydroxide having an increased specific surface area with sufficient pores, it is important to make the contact time of the quicklime and digestion water as uniform as possible and pulverize the quicklime so that hydration can be completed in a short time. However, since the homogenization of the hydration reaction is limited even with the powder particles, adding hydration reaction retarder and inducing period can provide a uniform hydration reaction as a whole. In the present invention, the term " derivative " means a period during which the hydration reaction does not progress visually for a certain period of time after initiation of the hydration reaction. The induction unit has an effect of providing a sufficient time for the digested water to sufficiently contact with the burnt lime, and has an effect of allowing equal hydration reaction to occur at the same time as possible.

In the present invention, ethylene glycol is used as a hydration reaction retarder. As the hydration reaction retarder in the prior art, a substance included in the saccharide series, the organic acid series, the boric acid series, and the sodium fluoride series fluoride salts series is used. One of the technical features of the present invention is that ethylene glycol is used as a hydration reaction retarder in the production of calcium hydroxide. Ethylene glycol has the advantage of being easily mixed with water, so if you choose the proper mixing method, it can be easily mixed with quicklime powder. The mixing method of ethylene glycol with quicklime powder can be divided into a wet mixing method and a dry mixing method depending on whether it is mixed first with digested water or before mixing with limestone powder. The wet mixing method of ethylene glycol in the present invention means a method in which ethylene glycol is first mixed with digested water (water), followed by addition of quicklime powder. The dry mixing method of ethylene glycol means a method in which ethylene glycol is first added to the calcium oxide powder and mixed to prepare a mixture of ethylene glycol and calcium oxide powder, followed by adding water (digestion water) to hydrate the mixture. The wet mixing method has an effect of providing an induction machine capable of sufficiently bringing the digested water into contact with the burnt lime powder, but has a disadvantage in that the mixing uniformity of the burnt lime powder and the ethylene glycol is poor. The dry mixing method has an advantage that the hydration reaction retardant uniformly coats the quicklime powder, so that not only an induction device can be provided for the hydration reaction, but the hydration reaction can be maximally uniformed at the same time.

In the present invention, the mixing method of the ethylene glycol with the calcium oxide powder is performed by the dry mixing method.

According to an embodiment of the present invention, in the step (a), the ethylene glycol is added at a ratio of 4-8 wt% to the quicklime powder. Preferably 4 to 6% by weight, more preferably 4% by weight, based on the quicklime powder.

In the present invention, the hydration reaction is performed by adding digested water to the mixture of ethylene glycol and quicklime.

Hydration reaction for the preparation of calcium hydroxide can be divided into wet hydration reaction and dry hydration reaction depending on the amount of digested water for the quicklime powder. In the present invention, the wet hydration reaction is performed by adding 100 wt% or more of digested water to the quicklime powder, and a large amount of water reacts with quicklime to produce calcium hydroxide in a cake state. The dry hydration reaction refers to a reaction in which water is added to the calcium oxide powder in an amount of less than 100% by weight, and the aggregation phenomenon between the particles is remarkably reduced, so that the calcium hydroxide is produced in a small agglomerate state .

According to an embodiment of the present invention, in the step (b), the digestion water is added so that the weight ratio of digestion water: burnt lime powder is 0.5 - 0.9: 1. Preferably, the digestion water is added so that the weight ratio of digestion water: burnt lime powder is 0.5 - 0.7: 1, and more preferably, the weight ratio of digestion water: burnt lime powder is 0.5: 1.

The digestion water can be used without restriction as long as it can hydrate the quicklime. Generally, the water used as the digestion water is tap water or ground water. When the temperature of the extinguishing water is raised, the activation energy necessary for the hydration reaction can be further supplied, so that the hydration activity is improved.

According to an embodiment of the present invention, the temperature of the digested water in the step (b) is 40-80 ° C. More preferably, the reaction water is at a temperature of 45-70 ° C, and more preferably at a temperature of 50-60 ° C.

Excessive hydration reaction may cause excessive growth of the crystal grains and form a relatively dense structure to produce calcium hydroxide having a significantly reduced specific surface area. Therefore, the hydration reaction can produce calcium hydroxide having a low pore size due to a low density of the pores and should be experimentally determined in consideration of the evaporation of the ethylene glycol and the digestion water used in the hydration reaction.

According to an embodiment of the present invention, in the step (b), the hydration reaction is performed for 10 to 30 minutes. Preferably, the hydration reaction is carried out for 15 to 20 minutes.

In the present invention, the hydration-completed product is dried.

When the hydration reaction-completed product is dried in a high-temperature environment, the specific surface area of calcium hydroxide is remarkably increased. This is because it quickly removes the excess moisture remaining after the drying moisture hydration reaction in the high-temperature environment, thereby suppressing the densification of the tissue due to the additional hydration reaction. In the present invention, the drying step is effective only in the hydration reaction such as the hydration reaction of the present invention. This is because, in the wet hydration reaction, the excess water remaining after the reaction can not be completely removed. Therefore, when the above-mentioned high-temperature drying is performed, water is not removed, but rather the hydration reaction is performed to generate calcium hydroxide having a more dense structure to be.

According to an embodiment of the present invention, drying in step (c) is performed at 180 to 400 ° C for 0.5 to 24 hours. Preferably at 200 DEG C for 24 hours or at 350 DEG C for 30 minutes.

The features and advantages of the present invention are summarized as follows:

(I) The present invention relates to a process for preparing high-surface-area calcium hydroxide using ethylene glycol as a hydration-retarding agent.

(Ii) The production method of the present invention has an effect of uniformly hydrating the raw lime powder by granulating the lime powder by dry mixing the ethylene glycol and the quick lime powder to give an appropriate induction agent.

(Iii) The production method of the present invention has an effect of significantly improving the specific surface area of calcium hydroxide by performing high-temperature drying after completion of the dry hydration reaction.

(Iv) Since the production method of the present invention uses a dry hydration reaction, there is no need for a dehydration, drying and crushing process for producing a calcium hydroxide powder product as compared with a wet hydration reaction process, thereby improving productivity and energy efficiency of a product have.

Fig. 1 shows the X-ray diffraction analysis results of the particle size of the quicklime produced in Korea.
Fig. 2 shows the results of the specific surface area measurement of calcium hydroxide according to the production method. Sample 1 shows dry hydration reaction by wet mixing of quicklime and ethylene glycol, followed by drying at 200 ° C for 24 hours. Sample 2 shows dry hydration reaction by wet mixing of quicklime and ethylene glycol, followed by drying at 350 ° C for 30 minutes. Sample 3 shows dry hydration reaction of dry lime and ethyleneglycol, followed by drying at 200 ℃ for 24 hours. Sample 4 shows dry hydration reaction by dry mix of quicklime and ethylene glycol, followed by drying at 350 ° C for 30 minutes. All of the above tests were carried out using quicklime having a size of 200 mesh or less.

Example

Experimental Method

1. Raw materials

FIG. 1 shows X-ray diffractometry (XRD) analysis results of the particle size of calcium oxide produced in Korea. In the case of quicklime having a diameter of 1 mm or less, it can be seen that unreacted limestone (CaCO ₃ ) remained because the heat treatment was not sufficiently performed in the calcining furnace (FIG. 1). Most of the unreacted CaCO ₃ was removed in the case of the fine powder having a size of 1 mm or less and screened with 200 mesh sieves (FIG. 1). In this experiment, hydration efficiency was measured according to the hydration temperature, water (digestion water) / quick lime ratio and ethylene glycol content by using quicklime of 1 mm or less in size. Based on the results, quicklime fine powders The reaction conditions were as follows: sample synthesis, drying conditions and reaction time. In this experiment, ethylene glycol used as a hydration reaction retardant was commercially available for industrial use.

2. Manufacturing method of calcium hydroxide

Ethylene glycol was used as a hydration reaction retardant to prepare calcium hydroxide. Water and quicklime were used at a weight ratio of water: quicklime = 0.5 - 0.9: 1.0, and the temperature of digested water was used at room temperature (25 ℃) - 85 ℃. The content of ethylene glycol was 1 wt%, 4 wt% or 8 wt%, respectively, based on the quicklime. The method of using ethylene glycol used as a hydration reaction retarder in the hydration reaction is a wet mixing method in which ethylene glycol is first mixed with water and then mixed with calcium oxide powder and ethylene glycol is mixed with calcium oxide powder And a dry mixing method in which water was added. After the hydration reaction, drying was carried out at 200 ° C and 350 ° C, and drying time was performed for 0.5 - 24 hours.

In the following, experimental methods of Comparative Examples and Examples will be described in detail.

In Examples 1 to 14, calcium hydroxide was prepared by subjecting hydrated lime powder having a size of 1 mm or less to water hydration reaction at different mixing ratios of water / quick lime, content of ethylene glycol (wt%) and temperature of digestion water The specific surface area of the calcium hydroxide was measured. Ethylene glycol was added to the hydration water by mixing with water to be used (wet mixing method). Crushed lime was crushed to a size of 1 mm or less and the digestion water temperature was 25 ° C, 45 ° C, 65 ° C or 85 ° C. The water / quicklime ratio was 0.5 and 0.6. After the hydration reaction, aging was carried out at room temperature for 24 hours.

In Examples 15 to 18, calcium hydroxide was prepared by varying the mixing ratio of water / quicklime, wet mixing by weight (wt.%), And digestion water using calcium oxide powder having a size of 200 mesh or less The specific surface area of the prepared calcium hydroxide was measured. After the hydration reaction, aging was carried out at room temperature for 24 hours.

In Examples 19 to 21, calcium hydroxide was prepared by varying the mixing ratio of water / quicklime, wet mixing by weight (% by weight), and digestion water by using quicklime powder having a size of 325 mesh or less The specific surface area of the prepared calcium hydroxide was measured. After the hydration reaction, aging was carried out at room temperature for 24 hours

In each of Examples 1-21, quicklime and ethylene glycol were mixed by a wet mixing method to prepare a mixture of quicklime powder, and dry water hydration was performed by adding digested water to the mixture.

Comparative Examples for Examples 1-21 were prepared by mixing a mixture of ethylene glycol and quicklime powder by a wet mixing method (mixed with digested water by ethylene glycol content for 10 minutes) and performing a dry hydration reaction under the same conditions as the corresponding examples Respectively.

In Examples 22-25, calcium hydroxide was prepared by dry hydration reaction by wet or dry mixing of burnt lime powder having a size of 200 mesh or less and ethylene glycol, followed by drying at 200 or 350 ° C for 24 hours or 30 minutes respectively. The specific surface area of the calcium hydroxide thus prepared was measured.

&Lt; Example 1 >

Without adding ethylene glycol to the quicklime powder having a size of 1 mm or less, digestion water at 25 ° C was added so that the digestion water / quicklime ratio was 0.5, followed by hydration for 15 minutes.

&Lt; Example 2 >

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added to 1% by weight of the quicklime and mixed. Digestion water at 25 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, mixed, The reaction was carried out.

&Lt; Example 3 >

Without adding ethylene glycol to the quicklime powder having a size of 1 mm or less, the digestion water at 65 ° C was added to the digestion water / quicklime ratio of 0.5, and the hydration reaction was performed for 15 minutes.

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added to 4% by weight of the quicklime and mixed. Digitized water at 65 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, mixed, The reaction was carried out.

&Lt; Example 5 >

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added to 8% by weight of the quicklime and mixed. Digitized water at 65 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, mixed, The reaction was carried out.

&Lt; Example 6 >

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added in an amount of 4% by weight based on the quicklime and mixed. The digested water at 85 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, mixed, The reaction was carried out.

&Lt; Example 7 >

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added to the quicklime in an amount of 8% by weight based on the weight of the quicklime, and the digested water at 85 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, mixed, The reaction was carried out.

&Lt; Example 8 >

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added to 4% by weight of the quicklime and mixed. Digitized water at 25 캜 was added thereto so that the digestion water / quicklime ratio was 0.6, mixed and hydrated for 15 minutes The reaction was carried out.

&Lt; Example 9 >

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added to the quicklime so as to have a concentration of 8 wt%, and the digested water at 25 캜 was added thereto so that the digestion water / quicklime ratio was 0.6, The reaction was carried out.

&Lt; Example 10 >

Without adding ethylene glycol to the quicklime powder having a size of 1 mm or less, digestion water at 65 ° C was added to the digestion water / calcium hydroxide ratio of 0.6, followed by hydration for 15 minutes.

&Lt; Example 11 >

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added in an amount of 1% by weight based on the quicklime, mixed with digested water at 65 캜 so as to have a digestion water / quicklime ratio of 0.6, The reaction was carried out.

&Lt; Example 12 >

To the quicklime powder having a size of 1 mm or less, ethylene glycol was added to the quicklime in an amount of 8 wt% and mixed. Digitized water at 65 캜 was added thereto so as to have a digestion water / calcium lime ratio of 0.6, mixed, The reaction was carried out.

&Lt; Example 13 >

Without adding ethylene glycol to the quicklime powder having a size of 1 mm or less, the digestion water at 85 ° C was added to the digestion water / calcium hydroxide ratio of 0.6, followed by hydration for 15 minutes.

&Lt; Example 14 >

Ethylene glycol was added to the quicklime having a size of 1 mm or less to make 1% by weight of the quicklime, and the digested water at 85 캜 was added thereto so as to have a digestion water / quicklime ratio of 0.6. The resulting mixture was mixed for 15 minutes The reaction was carried out.

&Lt; Example 15 >

Without adding ethylene glycol to the quicklime powder having a size of 200 mesh or less, digestion water at 45 ° C was added to digestion water / quicklime ratio of 0.5, followed by hydration for 15 minutes.

&Lt; Example 16 >

Without adding ethylene glycol to the quicklime powder having a size of 200 mesh or less, digestion water at 65 ° C was added to the digestion water / quicklime ratio of 0.5, and hydration reaction was performed for 15 minutes.

&Lt; Example 17 >

Without adding ethylene glycol to the quicklime powder having a size of 200 mesh or less, digestion water at 65 ° C was added to the digestion water / calcium lime ratio of 0.9, and the hydration reaction was performed for 15 minutes.

&Lt; Example 18 >

To the quicklime powder having a size of 200 mesh or less, 4 wt% of ethylene glycol was added to the quicklime and mixed. The digested water at 45 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, Minute hydration reaction was carried out.

&Lt; Example 19 >

Without adding ethylene glycol to the quicklime powder of 325 mesh or less in size, digestion water at 45 ° C was added to the digestion water / quicklime ratio of 0.5, and hydration reaction was performed for 15 minutes.

&Lt; Example 20 >

4% by weight of ethylene glycol was added to the quicklime and mixed with the quicklime powder having a size of 325 mesh or less, and the digested water at 45 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, Minute hydration reaction was carried out.

&Lt; Example 21 >

Without adding ethylene glycol to the quicklime powder having a size of 325 mesh or less, digestion water at 45 ° C was added to the digestion water / calcium lime ratio of 0.9, and the hydration reaction was performed for 15 minutes.

&Lt; Example 22 >

The quicklime and the ethylene glycol of 4 weight% were wet-mixed into the quicklime powder having a size of 200 mesh or less and the digestion water at 45 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, Hydration reaction was carried out. After the hydration reaction, the prepared calcium hydroxide was dried at 200 ° C for 24 hours.

&Lt; Example 23 >

The quicklime and the ethylene glycol of 4 weight% were wet-mixed into the quicklime powder having a size of 200 mesh or less and the digestion water at 45 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, Hydration reaction was carried out. When the hydration reaction was completed, the prepared calcium hydroxide was dried at 350 DEG C for 30 minutes.

&Lt; Example 24 >

The quicklime and the ethylene glycol of 4 wt% were dry-mixed into the quicklime powder having a size of 200 mesh or less, and the digested water at 45 캜 was added thereto so that the digestion water / quicklime ratio was 0.5, Hydration reaction was carried out. After the hydration reaction, the prepared calcium hydroxide was dried at 200 ° C for 24 hours.

&Lt; Example 25 >

Quick lime and 4 wt% ethylene glycol were dry mixed into calcium lime powder having a size of 200 mesh or less, and digested water at 45 캜 was added thereto so that the digestion water / quick lime ratio was 0.5, followed by mixing for 15 minutes The dry hydration reaction was carried out. When the hydration reaction was completed, the prepared calcium hydroxide was dried at 350 DEG C for 30 minutes.

Experiment result

1. Characterization of calcium hydroxide produced by using quicklime powder with a particle size of 1 mm or less

Table 2 shows the results of measurement of the specific surface area of calcium hydroxide prepared according to Examples 1 to 14. When ethylene glycol was not added, the specific surface area was measured in the range of 10.4 m ² / g to 13.2 m ² / g according to the hydration reaction conditions. As the content of ethylene glycol increased in each condition, the specific surface area was increased. However, there was no significant difference according to the change of the water cost. The results of the measurement according to the temperature of digestion water showed no significant difference when ethylene glycol was not added. When ethylene glycol was added in various amounts and the temperature was changed, the specific surface area was increased as a whole. From the above results, it was found that the conditions of water / quick lime ratio = 0.5, ethylene glycol content = 4 wt% relative to calcium oxide, and digestion water temperature = 45 DEG C - 65 DEG C were optimum.

Types of quicklime Ethylene glycol content (% by weight) Water temperature (℃) Digestion water / quicklime ratio Specific surface area (m ² / g) Example 1 Size less than 1 mm 0 25 0.5 10.4 Example 2 Size less than 1 mm One 25 0.5 13.7 Example 3 Size less than 1 mm 0 65 0.5 12.3 Example 4 Size less than 1 mm 4 65 0.5 15.6 Example 5 Size less than 1 mm 8 65 0.5 17.0 Example 6 Size less than 1 mm 4 85 0.5 16.2 Example 7 Size less than 1 mm 8 85 0.5 15.0 Example 8 Size less than 1 mm 4 25 0.6 14.7 Example 9 Size less than 1 mm 8 25 0.6 20.0 Example 10 Size less than 1 mm 0 65 0.6 12.2 Example 11 Size less than 1 mm One 65 0.6 11.4 Example 12 Size less than 1 mm 8 65 0.6 15.3 Example 13 Size less than 1 mm 0 85 0.6 13.2 Example 14 Size less than 1 mm One 85 0.6 14.5

2. Characterization of calcium hydroxide prepared by using quicklime powder having a particle size of 200 mesh or less and 325 mesh or less

In order to remove impurities such as undissolved CaCO ₃ contained in the quicklime powder, calcium hydroxide production experiments were carried out according to the above production conditions using a sample having a mesh size of 200 mesh and 325 mesh. Experiments were also carried out in the case of water / calcium oxide = 0.9 in order to see the effect of addition of water when using quicklime powder. Table 3 shows the experimental results for each condition.

Types of quicklime Content of ethylene glycol (% by weight) Temperature of digested water (℃) Digestion water / quicklime ratio Specific surface area (m ² / g) Example 15 Size less than 200 mesh 0 45 0.5 23.0 Example 16 Size less than 200 mesh 0 65 0.5 23.0 Example 17 Size less than 200 mesh 0 65 0.9 26.5 Example 18 Size less than 200 mesh 4 45 0.5 24.0 Example 19 Size less than 325 mesh 0 45 0.5 20.3 Example 20 Size less than 325 mesh 4 45 0.5 24.5 Example 21 Size less than 325 mesh 0 45 0.9 25.1

Types of quicklime Content of ethylene glycol (% by weight) Mixing method Temperature of digested water (℃) Digestion water / quicklime ratio Drying method Specific surface area (m ² / g) Example 22
(sample1) Size less than 200 mesh 4 Wet 45 0.5 200 ° C / 24 hours 22.5 Example 23
(sample2) Size less than 200 mesh 4 Wet 45 0.5 350 ° C / 30 min 24.1 Example 24
(sample3) Size less than 200 mesh 4 deflation 45 0.5 200 ° C / 24 hours 31.8 Example 25
(sample4) Size less than 200 mesh 4 deflation 45 0.5 350 ° C / 30 min 39.1

As shown in the above results, even when ethylene glycol was not added, the specific surface area was increased to 26.5 m ² / g depending on the amount of water added. This result seems to be due to the uniformity of the overall reaction rate of the particles by pulverizing the raw quicklime, which is probably due to the removal of impurities in the screen process. As a result of the preparation of calcium hydroxide by wet mixing of ethylene glycol, the specific surface area was slightly increased, but the effect was not significant. This is probably due to the aging time of the calcium hydroxide. The aging time was sampled at room temperature for 24 hours, and it was judged that the large effect was not exhibited due to excessive crystal growth during the aging time.

Therefore, a sample was prepared by varying the drying conditions at 200 ° C for 24 hours and at 350 ° C for 30 minutes immediately after setting the hydration reaction time to 15 minutes. The hydration conditions were water / lime = 0.5, ethylene glycol content = 4 wt% and the temperature of the digestion water = 45 ° C. In addition, the mixing method of ethylene glycol was changed to dry and wet to prepare calcium hydroxide. Fig. 2 shows the results of the specific surface area measurement of the calcium hydroxide produced according to the above conditions. 200 ℃ 24 hours of drying wet mixing a sample case of the calcium hydroxide (embodiment 2 of Sample 1, Example 22) was 22.5 m ² / g, dry mixing a sample (Sample 3 of Fig. 2, Example 24) was 31.8m ² / g (Fig. 2). Further, in the case of calcium hydroxide after drying at 350 ° C for 30 minutes, it was similar to drying at 200 ° C after wet mixing at 24.1 m ² / g of wet mixed sample (Sample 2 of Example 2 in FIG. 2) And the specific surface area increased remarkably to 39.1 m ² / g at the time of production (Sample 4-Example 25 in FIG. 2) (FIG. 2).

The specific embodiments described herein are representative of preferred embodiments or examples of the present invention, and thus the scope of the present invention is not limited thereto. It will be apparent to those skilled in the art that modifications and other uses of the invention do not depart from the scope of the invention described in the claims.

Claims

A process for producing calcium hydroxide with increased specific surface area comprising the steps of:
(a) adding ethylene glycol to the quicklime powder and mixing to prepare a mixture of ethylene glycol and quicklime powder;
(b) adding water to the mixture of ethylene glycol and quicklime to perform a hydration reaction; And
(c) drying the hydrated product.

The method according to claim 1, wherein the particle size of the quicklime powder in step (a) is 200 mesh or less.

The method according to claim 1, wherein in step (a), the ethylene glycol is added at a ratio of 4-8 wt% to the quicklime powder.

The method according to claim 1, wherein in step (b), the digestion water is added so that the weight ratio of digestion water: burnt lime powder is 0.5 - 0.9: 1.

The method according to claim 1, wherein the temperature of the extinguishing water in step (b) is 40-80 ° C.

The method of claim 1, wherein the hydration reaction is performed for 10 to 30 minutes in step (b).

The method according to claim 1, wherein drying in step (c) is performed at 180-400 ° C for 0.5-24 hours.