KR100880128B1 - Method for making lime slurry with high-speed agitation - Google Patents

Abstract

A manufacturing method of lime slurry is provided to manufacture lime slurry of the high quality using a simple method in a short time by proceeding hydration and crushing together at a high temperature using a frictional heat due to high speed-mixing and a reaction heat. A manufacturing method of lime slurry comprises steps of: mixing water 70~80 weight% and quicklime 20~30 weight% into a hydration tank; mixing a mixture for 10-30 minutes at 1,500 to 2,700 rpm and hydrating and crushing the mixture and obtaining the lime slurry; distributing the hydrated and pulverized lime slurry through sheave of 200~325 mesh.

Description

Method for making liquid slaked lime through high speed stirring {Method for making lime slurry with high-speed agitation}

The present invention relates to a method for producing liquid slaked lime through high speed stirring, and more particularly, to a method of manufacturing high quality liquid slaked lime by performing hydration and grinding together with high speed stirring.

In general, calcined lime (Ca (OH) ₂ ) is an alkaline substance produced by reacting quicklime (CaO) with water, and as a neutralizer to remove acid gases generated in an incinerator and causing acid rain in recent years, or factory wastewater. It is widely used as a neutralizer to neutralize industrial wastes.

Slaked lime is produced by reacting quicklime with water, and reacting quicklime (CaO) with water is called hydration. The slaked lime is used in the form of powder or liquid slaked lime, which is inconvenient to handle and requires a lot of manpower. Especially, the slaked lime causes the respiratory and skin diseases to workers due to scattering of the slaked lime powder, and the working environment is poor due to dust. have. In addition, powder slaked lime is used in the form of a powder, and thus has low reactivity with harmful substances, and various problems such as clogging of the tip of the spray nozzle due to coarse particles mixed therein occur.

On the other hand, liquid slaked lime has improved various disadvantages of powdered slaked lime, but when produced by the conventional liquid slaked lime production method, it is difficult to obtain high quality liquid slaked lime with high reactivity, and also has low economic efficiency and low economic efficiency. have.

That is, according to the conventional method for producing liquid lime, the liquid lime produced may be subjected to a hydration reaction for about 30 to 60 minutes by mixing a powder or agglomerate product having a content of about 80% of quicklime with water, and hydrated quicklime (slurry) and hydration. Undiluted quicklime lumps and residues are separated and stirred again to produce liquid calcined lime after a long time of aging. However, when the liquid slaked lime is produced in this way, the particle size of the slaked lime is large and the dispersion volume is low, thereby reducing the reactivity with harmful substances. In addition, a lot of production site and manpower is required to go through several stages of the production process, the manufacturing time is long, there is a problem that the economy is poor.

As described above, in order to improve the problem that the conventional liquid lime is inferior in reactivity with harmful substances, hydrated quicklime to obtain calcined lime, wet grinding it, and then wet classifying the wet ground calcined lime in a highly reactive liquid phase. A method of preparing slaked lime (Patent No. 10-0292139) has been disclosed. However, the method is filled with water in the hydration tank and added quicklime, left for 30 to 60 minutes, and then hydrated by stirring for 30 minutes at a speed of 10 to 20 rpm, and then crushed using a wet grinding machine to disperse, As such, it takes a long time to hydrate and has to go through a wet grinding step in a separate wet grinding machine, which has a disadvantage in that productivity and economy are inferior.

In the present invention, in order to improve the manufacturing method of the conventional liquid slaked lime, while generating a high heat through a high speed stirring in the hydration tank filled with crushed media, by integrating hydration and wet grinding (grinding) in one process, The present invention leads to the production of high quality liquid slaked lime with improved high normal concentration and dispersion volume.

In other words, when reacting quicklime with water in the process of making liquid calcined lime, when the thermal reaction is carried out at a high temperature, the dispersing capacity or normal concentration is higher than when it is not. However, when heat is injected in a separate process, energy costs are high, resulting in low economic efficiency.

In the present invention, the higher the concentration of quicklime, the more intense reaction heat is generated when reacting with water, and when wet grinding with strong rotational force, it is possible to obtain a stronger reaction heat. High-speed stirring can cause a stronger exothermic reaction due to friction and impact, thereby providing a method of obtaining high quality liquid slaked lime having excellent normal concentration and dispersion volume by proceeding with hydration and pulverization at such a high temperature.

It is an object of the present invention to provide a method for producing high quality liquid slaked lime having high production efficiency.

Another object of the present invention to provide a high-quality liquid slaked lime having a high normal concentration and even dispersion characteristics according to the production method.

In order to achieve the above object, the present invention comprises the steps of mixing water and quicklime in a hydration tank filled with a grinding media, hydrating and pulverizing the mixture by high speed stirring to obtain a liquid hydrated lime, and the hydrated and pulverized It provides a method for producing liquid slaked lime comprising the step of passing the liquid slaked lime through a sieve. In addition, the present invention provides a high-quality liquid calcined lime prepared by the above production method.

According to the present invention, by using hydration and grinding at high temperature by using frictional heat and reaction heat due to high speed stirring, there is an advantage that a high-quality liquid slaked lime can be manufactured in a simple manner in a short time, and using the manufacturing method of the present invention. As a result, the production efficiency of the liquid slaked lime per hour can be increased and manufacturing costs can be reduced. In addition, the liquid slaked lime of the present invention has a high normal concentration and has a characteristic that particles are finely dispersed evenly, and thus, when the liquid slaked lime of the present invention is used, it is excellent in reactivity and prevents problems such as clogging of the nozzle. There is this.

Hereinafter, the present invention will be described in detail.

The present invention comprises the steps of mixing water and quicklime in a ratio of 70 to 80% by weight: 20 to 30% by weight in a hydration tank filled with a grinding media corresponding to 10 to 30% of the capacity of the hydration tank (step 1); Stirring the mixture at high speed at 1,500 to 2,700 rpm for 10 to 30 minutes to hydrate and grind together to obtain liquid slaked lime (step 2); And it provides a method for producing a liquid calcined lime comprising the step (step 3) of the hydrated and pulverized liquid calcined lime passed through a sieve of 200 ~ 325 mesh (step 3).

Step 1 is a step of mixing water and quicklime in a ratio of 70 to 80% by weight: 20 to 30% by weight in a hydration tank filled with a grinding media corresponding to 10 to 30% of the capacity of the hydration tank.

Here, the pulverized media is used not only for making the particle size of the liquid slaked lime of the present invention fine, but also for inducing frictional heat. The grinding media is not particularly limited as long as it can pulverize lime, but may be glass beads, zirconium beads, silica sand or stainless steel beads, and preferably glass beads. The size of the pulverized media varies depending on the media, but the size is preferably 2.5 to 3.5 mm, and the smaller the size of the pulverized media is, the smaller the size of the produced slaked lime particles.

The grinding media may be filled with 10 to 30% of the capacity of the hydration tank, and may be filled with 15%, in order to prevent the overflow phenomenon during high-speed stirring.

On the other hand, the size of the hydration tank used in the present invention may vary depending on the amount of hydrated lime, it is preferable to use a hydration tank capable of stirring about 3,000 rpm for high speed stirring, which is a feature of the present invention. In addition, the hydration tank is provided with a stirrer. Here, the hydration tank is a round bottom shape, the stirrer is preferably a disk-type impeller stirrer.

In the present invention, water and quicklime are mixed in a hydration tank filled with the grinding media. The quicklime is not particularly limited, but in order to increase the hydration reactivity, it is preferable to use powdered quicklime having a CaO content of 90% by weight or more and a small particle size of 200 mesh or more, such as a particle size of 200 to 325 mesh.

On the other hand, the mixing ratio of water and quicklime can be adjusted, but 70-80% by weight of water and quicklime in order to proceed hydration and pulverization while generating high reaction heat and frictional heat by reacting water and quicklime violently through high-speed stirring It is preferable to mix in the ratio of 20-30 weight%.

In the preparation method of the present invention, step 2 is a step of hydrating and pulverizing the mixture of step 1 at a high speed for 10 to 30 minutes at 1,500 rpm or more.

Step 2 is characterized in that the hydration and grinding process together in a high temperature state with high speed stirring. That is, when high-speed stirring by strong rotational force in a hydration tank filled with crushed media, strong impact is applied between the quicklime particles and pulverized, reaction heat is generated by collision of the particles, and friction heat with the crushed media is generated. do. As a result, a natural temperature rise occurs due to high speed stirring, and hydration and pulverization are promoted at a high temperature, thereby making it possible to produce liquid slaked lime having a high normal concentration and evenly dispersed fine particles.

The high speed stirring speed may be 1,500 rpm or more, preferably 1,500 to 2,700 rpm range. At this time, if the stirring speed is less than 1,500 rpm, the heat of reaction is low and the efficiency is lowered. If the stirring speed is higher than 2,700 rpm, the improvement effect of the quality of the liquid calcined lime is weak. In addition, the stirring time can be made in the range of 10 minutes to 30 minutes, less than 10 minutes does not occur sufficient hydration and grinding, more than 30 minutes is not preferable in terms of production efficiency.

Here, when the stirring speed is high, the stirring time may be adjusted to be somewhat short, and at low stirring speed, the stirring time may be increased. In the production method of the present invention, the stirring speed and the stirring time were preferably 2,200 rpm and 15 minutes (see Experimental Example 1).

In the manufacturing method of the present invention, step 3 is a step of wet classification by passing the liquid hydrated lime hydrated and pulverized in step 2 through a sieve of 200 to 325 mesh. At this time, impurities such as crushed media, unhydrated material and residues are separated and removed.

The sieve is preferably 200 to 325 mesh, and more preferably 325 mesh or more in order to produce liquid calcined lime of finer particles.

The manufacturing method of the present invention may further include adjusting the content of the solid content to 15 to 25% by weight after mixing the additional water to the liquid calcined lime that was wet-classified in the third step after the three steps.

In the present invention, the liquid hydrated lime was prepared by varying the stirring speed to 1,500 to 2,700 rpm (see Table 1), and the stirring speed of 2,200 rpm was optimal when considering the stirring efficiency and power consumption. Judging. Thus, the liquid calcined lime produced by varying the stirring speed was in the range of normal concentration of 6.87 to 8.2, and the dispersion volume of 58 to 98%.

On the other hand, when the high speed stirring without using the grinding media, the normal concentration was 5.32, the dispersion volume was 39%, it was confirmed that the quality of the liquid slaked lime compared to the case of using the grinding media (see Table 2). As such, when high-speed stirring using the grinding media, it is possible to obtain high quality liquid slaked lime due to the generation of frictional heat and grinding by strong impact.

Hereinafter, a concrete embodiment of the present invention will be described in detail. However, the scope of the present invention is not limited by these examples.

Example  1: Preparation of Liquid Limestone

Step 1: Crushed Media  Charged In a hydration tank  Water and Quicklime Mix

Filling the hydration tank filled with glass beads (particle size 2.5 ~ 3.5mm) to 15% of the capacity of the hydration tank, 2,400 kg of water at 25 ° C was filled and the powder quicklime (200 mesh or more; CaO 90) of Taeyoung IMC Co., Ltd. 600 kg) was added to mix water and quicklime.

Step 2: High speed stirring  Hydration and Crushing Through

The speed of the stirrer was increased to 1,500 rpm, and the mixture of Step 1 was stirred for 15 minutes to proceed with hydration and pulverization to obtain liquid slaked lime.

Step 3: liquid hydrated lime Wet classification

The hydrated and ground liquid calcined lime of step 2 was wet classified into 325 mesh sieves. At this time, impurities such as crushed media, unhydrated substances, residues, and the like were separated and discharged from the liquid calcined lime.

Step 4: Adjusting Liquid Limestone Content

Water was added to the liquid slaked lime of Step 3 to adjust the liquid slaked lime solid content to 20 to 25% by weight.

Example  2: Preparation of Liquid Limestone

Liquid calcined lime was prepared in the same manner as in Example 1 except that the stirring speed was set to 1,800 rpm in Step 2 of Example 1.

Example  3: Preparation of liquid slaked lime

Liquid calcined lime was prepared in the same manner as in Example 1 except that the stirring speed was set to 2,000 rpm in Step 2 of Example 1.

Example  4: Manufacture of liquid slaked lime

Liquid calcined lime was prepared in the same manner as in Example 1, except that step 2 of Example 1 was performed at a stirring speed of 2,200 rpm.

Example  5: Preparation of Liquid Limestone

Liquid calcined lime was prepared in the same manner as in Example 1 except that the stirring was performed at 2,500 rpm in Step 2 of Example 1.

Example  6: Preparation of liquid slaked lime

Liquid calcined lime was prepared in the same manner as in Example 1, except that step 2 of Example 1 was performed at a stirring speed of 2,700 rpm.

Experimental Example  One: At the stirring speed  Quality Evaluation of Liquid Limestone

In the present invention, the normal concentration and the dispersion volume of the liquid calcined lime (Examples 1 to 6) prepared at different stirring rates were measured, respectively.

For the normal concentration, take a 10 mL sample by pipette into a 500 mL beaker, add 400 mL of distilled water, and check the pH with a pH meter while stirring with a Jar-Tester. It was calculated | required by titrating to pH 7.0 with sulfuric acid (6-7N sulfuric acid is suitable). The dispersion volume was obtained by adjusting the concentration of liquid slaked to 20% by weight, filling 100 mL of cylinder, and measuring the volume precipitated after 6 hours. The numerical value of the dispersion volume indicates a volume in which solid particles are uniformly dispersed in the slurry, and the larger the value is, the more preferable. In addition, it can be said that the higher the normal concentration, the higher the quality of the liquid calcined lime.

Table 1 shows the preparation conditions of Examples 1 to 6 and the results of normal concentration and dispersion volume of the liquid slaked lime prepared accordingly.

Hydration / Pulverization Stirring Speed (rpm) Temperature N concentration Distributed volume Example 1 Concurrent 1,500 55 ℃ 6.87 58% Example 2 Concurrent 1,800 65 ℃ 6.9 67% Example 3 Concurrent 2,000 68 ℃ 7.1 73% Example 4 Concurrent 2,200 75 ℃ 7.9 95% Example 5 Concurrent 2,500 79 ℃ 8.0 96% Example 6 Concurrent 2,700 85 ℃ 8.2 98%

As shown in Table 1, it can be seen that as the stirring speed is increased, the temperature increases due to the reaction heat and frictional heat due to the wet impact. In addition, the hydration and crushing efficiency also increases with increasing temperature, it can be seen that the normal concentration and dispersion volume of the prepared liquid slaked lime increased.

From the above results, when the stirring speed was 2,200 rpm or more, a higher quality liquid calcined lime could be obtained, and Example 5 and Example 6 had a slight difference in effect due to the difference in stirring speed, which was performed in view of power consumption and agitation efficiency. Example 4 was deemed desirable.

Experimental Example  2: Crushed Media  Review efficiency with addition

In order to examine the efficiency of the liquid hydrated lime production method of the present invention, without the pulverized media in the conditions of Example 4, hydrated and pulverized for 15 minutes at a stirring speed of 2,200 rpm to prepare a liquid hydrated lime (hereinafter, Referred to as Comparative Example 1)

The normal concentration and the dispersion volume of the liquid slaked lime prepared in Example 4 and Comparative Example 1 were measured and compared, and the measurement results are shown in Table 2 below.

Examination of Efficiency of Manufacturing Method by Using Grinding Media Hydration / Pulverization Stirring Speed (rpm) Temperature Whether to use grinding media Normal concentration Distributed volume Example 4 Concurrent 2,200 75 ℃ use 7.9 95% Comparative Example 1 Concurrent 2,200 51 ℃ Do not use 5.32 39%

As can be seen in Table 2, the temperature is increased up to 75 ℃ when the pulverized media is filled with stirring at the same stirring speed, but the temperature is increased only up to 51 ℃ when stirred without filling the grinding media It was found out. This means that during high-speed agitation, the grinding media generate high temperature heat due to the strong friction with each other, the impact of rubbing with the powdered lime, and the grinding.

In addition, when the pulverized media is not used, the normal concentration and the dispersing volume of the prepared liquid slaked lime are 5.32 and 39%, respectively, indicating that the quality is significantly lower than that of the pulverized media.

Therefore, in the case of high speed stirring in the state of filling the grinding media, it is possible to induce a temperature rise of 20 ° C. or more compared to the state of not using the grinding media without adding additional heat, thereby increasing the hydration and grinding efficiency, High quality liquid slaked lime can be produced.

Experimental Example  3: Examine the efficiency of the manufacturing method of the present invention

The manufacturing method of the present invention is that in the hydration tank filled with crushed media, it is possible to produce high-quality liquid slaked lime in a short time by performing hydration and pulverization by using reaction heat and frictional heat through high speed stirring. The efficiency of the preparation method of the present invention was compared with that of the method for preparing liquid calcined lime (hereinafter referred to as Comparative Example 2) disclosed in Patent Registration No. 10-0292139.

In Comparative Example 2, the hydration tank was filled with water, quicklime was added, allowed to stand for 30 to 60 minutes, stirred for 30 minutes at a speed of 10 to 20 rpm, and hydrated under a condition of 7 minutes of residence time in the wet mill. After wet grinding, the wet milled hydrated lime oil is wet classified to obtain liquid hydrated lime.

Comparing the liquid slaked lime (Comparative Example 2) prepared above and the liquid slaked lime of the present invention, the preparation time of each step is shown in Table 3 below.

The present invention Comparative Example 2 Sign Language 10-30 minutes 60 to 90 minutes (30 minutes to 60 minutes after stirring, 30 minutes stirring) Grinding (crushing) 7 minutes Sum 10-30 minutes 67-97 minutes

In the case of the production method of the present invention, by hydrating and pulverizing together by using high-temperature reaction heat and frictional heat by high speed stirring, it took only 10 to 30 minutes in the hydration and crushing step. On the contrary, in Comparative Example 2, it took 60 to 90 minutes in the hydration step and 7 minutes in the grinding (grinding), and 67 to 97 minutes in the hydration and grinding step.

From Table 3, it can be seen that using the production method of the present invention, the production time of the liquid calcined lime can be significantly shortened at least two times or more in the hydration and pulverization step compared with the conventional production method (Comparative Example 2).

Thus, using the production method of the present invention it is possible to produce a high quality liquid hydrated lime in a much shorter time through a simple process than the conventional method for producing liquid lime. Therefore, by using the production method of the present invention, it is possible to produce a large amount of high-quality liquid slaked lime in a short time, and the liquid slaked lime production efficiency is very excellent and it is possible to obtain an economic effect of reducing the manufacturing cost.

Claims (6)

Mixing water and quicklime in a ratio of 70 to 80 wt%: 20 to 30 wt% in a hydration tank filled with a grinding media corresponding to 10 to 30% of the capacity of the hydration tank; Stirring the mixture at high speed at 1,500 to 2,700 rpm for 10 to 30 minutes to hydrate and grind together to obtain liquid slaked lime; And Method for producing a liquid slaked lime comprising the step of passing through the hydrated and pulverized liquid calcined lime through a sieve of 200 ~ 325 mesh. The method of claim 1, The pulverized media is glass beads, zirconium beads, silica sand or stainless steel beads, characterized in that the manufacturing method of the liquid slaked lime. The method of claim 2, The pulverized media is a method for producing liquid slaked lime characterized in that it has a particle size of 2.5 to 3.5 mm. The method of claim 1, The high speed stirring is a method for producing liquid slaked lime, characterized in that consisting of 2,200 rpm. The method of claim 1, The quicklime has a CaO content of more than 90% by weight, the method for producing liquid slaked lime characterized in that the powder quicklime of 200 ~ 325 mesh. The method according to any one of claims 1 to 5, Mixing additional water to the wet-classified liquid slaked lime further comprises the step of adjusting the content of solids to 15 to 25% by weight of liquid slaked lime.