JP2006273600A - Adhesion-suppressed slaked lime - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesion-suppressed slaked lime having excellent flowability and improved adherability. <P>SOLUTION: The adhesion-suppressed slaked lime is composed of a slaked lime obtained by slaking a low-activity unslaked lime having an activity of 20-150 mL or comprises a slaked lime obtained by slaking a low-activity unslaked lime having an activity of 20-150 mL in an amount of 40 wt.% or more. Preferably, to the slaked lime is added one or more additives selected from the group consisting of glycols and ethanol amines in an amount of 0.1-5 wt.% per 100 wt.% of the slaked lime or is added one or more inorganic powders selected from the group consisting of shirasu balloon, vermiculite, and pearlite in an amount of 0.5-5 wt.% per 100 wt.% of the slaked lime. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is used as a neutralizing agent and flue gas for acid substances, as an acid removing agent in wastewater, and is generally used as a reaction alkali in various chemical industries, and has excellent fluidity compared to general-purpose slaked lime, And it is related with the adhesion suppression type | mold slaked lime which can reduce adhesiveness.

As slaked lime used for exhaust gas treatment such as acid gas generated in a garbage incineration plant, slaked lime with less problems such as adhesion to piping and blockage of piping during transportation is desired. In particular, in general-purpose slaked lime that is generally used, there are problems of adhesion to piping and the like and poor fluidity during transportation, storage, and pressure feeding. Therefore, when general-purpose slaked lime is used, many human burdens and costs are required for maintenance and management of transportation piping.
As a measure for solving the above problems, slaked lime, powdered quicklime, and at least one additive selected from glycols, glycol ethers or ethanolamines, the weight ratio of the slaked lime and powdered quicklime is 98. : 2 to 70:30 modified low adhesion slaked lime has been proposed (for example, see Patent Document 1). Moreover, the adhesive improvement slaked lime containing pearlite is proposed as an additive which improves adhesiveness (for example, refer patent document 2).
Japanese Patent No. 2963626 (Claim 1) Japanese Patent Laying-Open No. 2003-252621 (Claim 1)

However, in the slaked lime shown in Patent Document 1 or 2, a certain adhesion suppression effect is obtained, but since it is necessary to always add an additive, the cost is increased compared to general-purpose slaked lime, and depending on the use However, there is a problem that the use is limited, and further improvement has been demanded. Moreover, it cannot be said that the problem of fluidity | liquidity is fully solved in the slaked lime shown by the said patent document 1 or 2.
The objective of this invention is providing the adhesion suppression type | mold slaked lime which is excellent in fluidity | liquidity compared with general purpose slaked lime, and can reduce adhesiveness.

The invention according to claim 1 is an adhesion-inhibiting slaked lime comprising slaked lime obtained by digesting low-activity quicklime having an activity of 20 to 150 ml.
The invention according to claim 2 is an adhesion-inhibiting slaked lime comprising 40% by weight or more of slaked lime obtained by digesting low-activity quicklime having an activity of 20 to 150 ml.
In the invention according to claim 1 or 2, since slaked lime obtained by digesting low-activity quicklime with an activity of 20 to 150 ml is used, compared with general-purpose slaked lime obtained by digesting highly active quicklime. In addition, the fluidity is excellent and the adhesion can be reduced.

The invention according to claim 3 is the invention according to claim 1 or 2, wherein one or more additives selected from the group consisting of glycols and ethanolamines are added to 100% by weight of slaked lime. It is adhesion suppression type | mold slaked lime added in the ratio of 0.1 to 5 weight%.
In the invention which concerns on Claim 3, the adhesion inhibitory effect is further accelerated | stimulated by adding the said additive to slaked lime.

The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein one or more inorganic powders selected from the group consisting of shirasu balloon, vermiculite and perlite are used as slaked lime 100. It is the adhesion suppression type | mold slaked lime added in the ratio of 0.5-5 weight% with respect to weight%.
In the invention which concerns on Claim 4, fluidity | liquidity and adhesiveness are further improved by adding the said inorganic powder to slaked lime.

  The adhesion-suppressed slaked lime of the present invention uses slaked lime obtained by digesting low-activity quick lime having an activity of 20 to 150 ml as a raw material, so that the general-purpose slaked lime obtained by digesting highly active quick lime is used. Compared with the fluidity, the adhesiveness can be reduced. In addition, by adding an additive to slaked lime at a predetermined ratio, or by adding an inorganic powder to the slaked lime at a predetermined ratio, the adhesion and fluidity are further improved. Problems such as adhesion and discharge during storage can be greatly eliminated.

Next, the best mode for carrying out the present invention will be described.
The adhesion-suppressing slaked lime of the present invention is characterized by comprising slaked lime obtained by digesting low-activity quicklime having an activity of 20 to 150 ml, preferably 40 to 100 ml. The activity in the present invention means that 50 g of quick lime having a particle size of 10 to 3 mm is put into 2 liters of water in which 2 to 3 drops of phenolphthalein indicator is dropped, and 4N hydrochloric acid is continuously added dropwise with stirring. The amount of hydrochloric acid consumption (unit: ml) when 5 minutes have elapsed while maintaining a red state. It shows that activity is so high that there is much hydrochloric acid consumption in the said conditions.

  In the production of slaked lime that is widely used, it is usually produced by adding about 65% water by weight to the raw lime, which is a raw material, and hydrated. High activity with an activity of 250 ml or more is used. On the other hand, low activity quicklime having an activity of 150 ml or less is usually used as a raw material for ALC, a raw material for static crushing material, or the like. In the invention, the adhesion-suppressed slaked lime of the present invention focuses on the fact that the fluidity and adhesion of slaked lime produced with low activity quick lime is very superior to the general-purpose slaked lime produced with high activity quick lime described above. It has come. The activity is regulated within the above range because quick lime whose activity exceeds the upper limit is inferior in fluidity and adhesion of slaked lime produced using this quick lime, and when the activity is less than the lower limit, quick lime or slaked lime is produced. This is because the economic cost of time increases. In order to obtain a sufficient effect in the flowability and adhesion of slaked lime, and considering economic costs, the activity of quick lime as a raw material is preferably 40 to 100 ml.

  Quick lime, which is a raw material for slaked lime, is obtained by calcining limestone in a firing furnace such as a hard furnace or kiln, or an electric furnace, and decarboxylating. The activity of quicklime varies depending on the properties and size of the original limestone, the firing temperature, the firing time, the firing atmosphere, etc. The quicklime used as the raw material for the above-mentioned general-purpose slaked lime has a temperature of 900 ° C. or higher and lower than 1100 ° C. It is obtained by baking for 2 to 3 hours, has a small development of quick lime crystal particles and a relatively large porosity, and exhibits a high activity of about 250 to 400 ml. On the other hand, the low activity quick lime used in the present invention is obtained by firing for 1 to 3 hours at 1100 ° C. to 1200 ° C., which is higher than the above firing temperature, and the development of quick lime crystal particles is large and the porosity is small. A quick lime having a low activity of 20 to 150 ml is obtained.

  Moreover, as another adhesion suppression type | mold slaked lime of this invention, the slaked lime obtained by digesting the low activity quick lime whose activity is 20-150 ml is included in the ratio of 40 weight% or more. Slaked lime obtained by digesting low-active quicklime can be mixed with the above-mentioned general-purpose slaked lime at a predetermined ratio, and can be properly used according to the application. Among these, in order to obtain practical effects with fluidity and adhesion, it is preferable to include slaked lime obtained from low-active quicklime in a proportion of 60% by weight or more, and in a proportion of 60 to 80% by weight. Particularly preferred.

  Moreover, the ratio of 0.1-5 weight% with respect to 100 weight% of slaked lime with 1 type, or 2 or more types of additives chosen from the group which consists of glycols and ethanolamines to the adhesion suppression type | mold slaked lime of this invention May be added. By adding the additive to the slaked lime at a predetermined ratio, the adhesion suppressing effect is further promoted. Examples of glycols include diethylene glycol and ethylene glycol, and examples of ethanolamines include triethanolamine. If the amount of the additive is less than the lower limit, a sufficient adhesion suppressing effect cannot be obtained, and even if the upper limit is exceeded, the effect does not change and the cost increases. The additive amount is particularly preferably 0.5 to 1.5% by weight. The fluidity and adhesion of slaked lime can be improved by adding the additive to the slaked lime at a predetermined ratio and mixing and stirring the slaked lime to adhere to the slaked lime surface. As the mixing and stirring method, a vertical or horizontal bladed mixer, a fluidized bed type airflow stirring mixer, or the like can be used. In addition, although the improvement effect of fluidity | liquidity and adhesiveness is recognized to some extent by adding the said additive to the general purpose slaked lime mentioned above, an improvement effect is further improved by making the said additive adhere to the adhesion suppression type | mold slaked lime of this invention. Promoted. In addition, the same effect is acquired also by the addition method of the additive by adding and mixing to the digestive water used at the time of slaked lime manufacture.

In addition, in the adhesion-suppressing slaked lime of the present invention, 0.5 to 5% by weight of one or more inorganic powders selected from the group consisting of shirasu balloon, vermiculite and pearlite with respect to 100% by weight of slaked lime. You may add in a ratio. By adding the inorganic powder to the slaked lime at a predetermined ratio, fluidity and adhesion are further improved. Shirasu balloons are hollow spherical fine particles obtained by heat-treating shirasu contained in volcanic ash. Vermiculite is a flaky mineral mainly composed of SiO ₂ , MgO, Al ₂ O _3, etc., which is obtained by pulverizing or classifying a rough ore into a certain particle size and rapidly expanding it by heating in a heating furnace. . Pearlite is obtained by pulverizing pearlite mainly composed of SiO ₂ , Al ₂ O ₃ , K ₂ O, etc., and expanding it to a volume approximately 10 times that of the original ore by high heat treatment. If the addition amount of the inorganic powder is less than the lower limit value, a sufficient adhesion suppressing effect cannot be obtained, and even if the upper limit value is exceeded, the effect does not change and the cost increases. The addition amount is particularly preferably 1 to 3% by weight. A method of using these inorganic powders with slaked lime in exhaust gas treatment agents and the like is already known, but by adding these inorganic powders to the adhesion-suppressing slaked lime in the present invention, fluidity and adhesion are improved. Further improvements can be made.

Next, examples of the present invention will be described in detail together with comparative examples, but the present invention is not limited to the following examples.
<Examples 1-4 and Comparative Examples 1-3>
First, limestone was baked in an electric furnace at 1100 ° C. for 3 hours to produce quick lime having an activity of 148 ml. Next, the prepared quicklime was adjusted to a particle size of 10 mm or less, hydrated and aged by adding 65 parts by weight of water to 100 parts by weight of quicklime. Next, after the obtained digest was dried, the particle size was adjusted to 150 μm or less to obtain desired slaked lime (Example 1). Moreover, the calcination conditions of limestone were changed to the conditions shown in the following Table 1 to obtain desired slaked lime (Examples 2 to 4, Comparative Examples 1 to 3).

The adhesion strength of the obtained slaked lime was measured using a powder adhesion force measuring device shown in FIGS. As shown in FIG. 1, the sample container 11 includes two cylindrical frames, that is, a cylindrical upper frame 11a, and a lower frame 11b having the same shape and the same size as the upper frame 11a. The upper frame 11a is a lower frame. 11b is arranged so as to overlap. A flange 11c is provided at the lower part of the lower frame 11b. The sample container 11 was placed on the pedestal 12, and a plastic disc 13a and a filter paper 14a having the same diameter as the inner diameter of the frame and having a plurality of communication holes were arranged in this order on the bottom of the sample container 11. Subsequently, the obtained slaked lime is put evenly as a sample 16 until it overflows from the upper frame 11a, and lightly slicing operation is performed. Arranged in this order. Next, the piston 17 was arranged on the disk 13b, and the slaked lime sample 16 filled in the sample container 11 was compressed by applying a pressure of 6 kgf / cm ^{2 in} a direction perpendicular to the piston 17 by the press machine 18.

  Next, as shown in FIG. 2, the sample container 11 having the compressed sample 16 is fixed to the pedestal 21 with the container fixing material 22, and then one end of the wire cable 23 is connected to the upper end of the upper frame 11 a of the sample container 11. . The wire cable 23 has its transmission direction changed by pulleys 24 a and 24 b, and the other end is connected to the upper end of the water container 26. The water container 26 is held in a suspended state by a wire cable 23 at a certain distance from the pedestal 21. Subsequently, water was poured into the water container 26 from the burette 28 in which the water 27 was stored, and a tensile load was applied to the sample container 11 upward via the wire cable 23 due to the weight of the water container 26 that was poured. When the sample 16 was broken into the upper sample 16a and the lower sample 16b by the predetermined tensile load and the upper frame 11a and the lower frame 11b were separated, water injection into the water container 26 was stopped. The weight of the water container 26 and the water 27 injected into the water container 26 and the weights of the broken upper sample 16a and the upper frame 11a are both weighed, and the adhesive force is determined by the following equation (1) from each weighed weight. Asked.

Moreover, the obtained slaked lime was analyzed with a powder tester (manufactured by Hosokawa Micron Corporation), and the angle of repose was measured. The results are shown in Table 1.

  As shown in Table 1, compared with the slaked lime of Comparative Examples 1 to 3 using quick lime having a relatively high activity as a raw material, the slaked lime of Examples 1 to 4 using low activity quick lime having an activity of 150 ml or less, It can be seen that the adhesive force is reduced and the repose angle results in excellent fluidity.

<Examples 5-7, Examples 8-10, Comparative Example 4>
Using the slaked lime produced in Example 3, an additive was added to the slaked lime at a ratio shown in Table 2 below to obtain desired slaked lime (Examples 5 to 7). In addition, slaked lime was prepared in the same manner as in Example 3 except that the additive was added to digested water at the ratio shown in Table 2 below when quicklime was hydrated. After drying this slaked lime, the particle size was adjusted to 150 μm or less. Thus, desired slaked lime was obtained (Examples 8 to 10). Furthermore, the desired slaked lime was obtained by using the slaked lime produced in Comparative Example 1 and adding additives to the slaked lime in the proportions shown in Table 2 below (Comparative Example 4). Using the obtained slaked lime, adhesion force measurement and repose angle measurement were performed in the same manner as in Example 1. The results are shown in Table 2.

  As is clear from Table 2, in the slaked lime of Examples 5 to 10 to which the additive was added, adhesion and flow compared to the results of the slaked lime of Example 3 using quick lime having the same activity shown in Table 1 described above. It was found that the sex was improved. Moreover, compared with the slaked lime of the comparative example 4 using the quick lime of high activity which added the additive, adhesiveness and fluidity | liquidity were improved.

<Examples 11 to 13>
The slaked lime produced in Example 3 was designated as slaked lime A, the slaked lime produced in Comparative Example 1 was designated as slaked lime B, and these slaked lime A and B were mixed at the ratio shown in Table 3 to obtain the desired slaked lime. Using the obtained slaked lime, adhesion force measurement and repose angle measurement were performed in the same manner as in Example 1. The results are shown in Table 3.

  From the result of Table 3, in the slaked lime of Examples 11-13, if the ratio of the slaked lime A which has an adhesion inhibitory effect is 40 weight% or more, the slaked lime which reduced the adhesive force to half or less compared with the slaked lime of the comparative example 1. Could have obtained. From this, it was confirmed that the slaked lime obtained by digesting the low activity quicklime can be properly used according to the intended use by mixing with the above-mentioned general-purpose slaked lime at a predetermined ratio.

<Examples 14 to 16>
Using the slaked lime produced in Example 3, an inorganic powder was added to the slaked lime at a ratio shown in Table 4 below to obtain a desired slaked lime. In addition, the inorganic powder having an opening of 150 μm and a sieve passing rate of 90% or more was used. Using the obtained slaked lime, adhesion force measurement and repose angle measurement were performed in the same manner as in Example 1. The results are shown in Table 4.

  As is clear from Table 4, in the slaked lime of Examples 14 to 16 to which inorganic powder was added, the adhesion and the slaked lime results of Example 3 using quick lime having the same activity shown in Table 1 described above were compared. It was found that the fluidity was improved.

Sectional drawing which shows the sample container used in the Example. Sectional drawing which shows the powder adhesive force measuring apparatus used in the Example.

Explanation of symbols

11 Sample container 16 Slaked lime sample

Claims (4)

  An adhesion-inhibiting slaked lime comprising slaked lime obtained by digesting low-activity quicklime having an activity of 20 to 150 ml.   An adhesion-inhibiting slaked lime comprising 40% by weight or more of slaked lime obtained by digesting low-activity quick lime having an activity of 20 to 150 ml.   The adhesion according to claim 1 or 2, wherein one or more additives selected from the group consisting of glycols and ethanolamines are added at a ratio of 0.1 to 5% by weight with respect to 100% by weight of slaked lime. Suppressed slaked lime. 4. One or more inorganic powders selected from the group consisting of shirasu balloon, vermiculite and perlite are added at a ratio of 0.5 to 5% by weight with respect to 100% by weight of slaked lime. 2. The adhesion-suppressing slaked lime according to item 1.

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