TWI606976B - Preparation method of calcium oxide - Google Patents

Description

Method for preparing calcium oxide

The invention relates to a preparation method of calcium oxide powder, in particular to a preparation method of eggshell calcium oxide powder.

Generally, eggshells account for about one-tenth of the weight of whole eggs. The main component of eggshells is calcium carbonate, which accounts for 91% to 95% of the weight of whole eggshells. It is contained in pearls, oysters, beef bones, and dried fish. Calcium is the same source and is a good source of calcium; in addition, the eggshell contains about 5% of magnesium carbonate, and 2% of calcium phosphate and gum.

Eggs are widely used in the food industry. Taiwan has about 36.5 million hens per year, with an annual output of 6.7 billion eggs. The average person consumes 290 eggs per year. If such a large eggshell is not properly handled, it may Due to environmental pollution, many egg producers even need to use waste disposal sites to accumulate waste eggshells. At present, the application of waste eggshells is mainly based on fertilizers or feeds. If the application range of waste eggshells can be expanded, not only can garbage be effectively solved. The problem can also open up another business opportunity.

Therefore, in recent years, studies have shown that after mixing the eggshell and water after calcination, the mixture has a good inhibitory effect on the growth of microorganisms, mainly due to the oxidation formed by calcium carbonate in the eggshell after high temperature calcination. Calcium has a bacteriostatic effect;

However, calcium oxide prepared from eggshells by conventional technical methods still has many unsatisfactory defects, such as poor purity, uneven particle size, difficulty in processing, inconvenient use, high cost, etc. All kinds of shortcomings, these shortcomings require the joint efforts of members of the modern industry to overcome and solve together.

Therefore, there is an urgent need to develop a calcium oxide powder which not only retains the original characteristics of the calcium oxide powder, but also has high purity, uniform particle size, low manufacturing cost, and easy processing.

In view of the above, the present inventors have diligently studied and searched for various possible solutions for solving the above problems of the conventional technology, and have developed a problem that not only improves the above problems of the conventional technology, but also retains the original calcium oxide powder. In addition to the characteristics, the invention also has the advantages of high purity, uniform particle size, low manufacturing cost, easy processing, and high economical efficiency of calcium oxide powder, and thus the present invention has been completed.

In other words, according to an embodiment of the present invention, a method for preparing calcium oxide can be provided, which comprises:

(1) Washing step: after cleaning the eggshell by ultrasonic wave, continue washing with detergent, then take it out and wash it thoroughly with running water to remove residual washing liquid, which includes self-calcium ion powder and natural At least one selected from the group consisting of sea salt, sodium percarbonate, sodium citrate, and mixtures thereof;

(2) drying step: for the above-mentioned washing step (1), the washed eggshell is dried at a temperature of 70 ° C to 140 ° C to dry the inner and outer surfaces of the egg shell;

(3) calcination step: calcining the dried eggshells treated by the above drying step (2) at a first temperature (T1), a second temperature (T2), and a third temperature (T3) for a first time ( X), second time (Y), third time (Z) to obtain calcium oxide, wherein T1, T2, T3, X, Y, Z meet the following relationship: 100 ° C ≦ T1 ≦ 400 ° C; 200 ° C ≦ T2≦700°C; 400°C≦T3≦900°C; T1≦T2; T2≦T3; 90 minutes≦X+Y+Z≦600 minutes; and X, Y, Z are not zero at the same time.

Further, according to a specific embodiment, the present invention also provides a method for preparing calcium oxide, wherein the low temperature drying time is in the range of 10 minutes to 50 minutes.

Secondly, according to still another specific embodiment, the present invention further provides a method for preparing calcium oxide, which is gradually heated to a temperature of 30 seconds to 100 minutes after the calcination is completed at the first temperature (T1). Second temperature (T2).

Furthermore, according to another specific embodiment, the present invention also provides a method for preparing calcium oxide, which is gradually heated for 30 seconds to 100 minutes after the calcination is completed at the second temperature (T2). To the third temperature (T3).

In addition, according to another specific embodiment, the present invention also provides a method for preparing calcium oxide, which is cooled rapidly after 30 seconds to 10 minutes after the completion of calcination at the third temperature (T3). Second temperature (T2).

In addition, according to still another specific embodiment, the present invention further provides a method for preparing calcium oxide, which is followed by calcination at a third temperature (T3), and then continues to rapidly cool down to 30 seconds to 10 minutes. A temperature (T1).

Moreover, according to another specific embodiment, the present invention further provides a method for preparing calcium oxide, wherein the calcining step (3) comprises further calcining for a fourth time (V) at a fourth temperature (T4), Wherein T4 and V satisfy the following relationship: T3≦T4; and 600°C≦T4≦1200°C; and 90 minutes ≦V+X+Y+Z≦600 minutes; and V is not zero with X, Y, Z at the same time.

Secondly, according to still another specific embodiment, the present invention further provides a method for preparing calcium oxide, wherein the calcining step (3) further comprises calcining the fifth time (W) at a fifth temperature (T5 ° C), Wherein T5 and W satisfy the following relationship: T3≦T5; and 600°C≦T5≦1200°C; 90 minutes≦W+X+Y+Z≦600 minutes; and W is not zero with X, Y, Z at the same time. The eggshell may be an eggshell produced by any poultry, generally an eggshell, a duck eggshell or a gooseshell, preferably an eggshell.

The above preparation method, wherein the addition weight of the washing liquid is in the range of 50 mg to 300 mg.

Furthermore, according to another embodiment of the present invention, a calcium oxide may be additionally provided, wherein the first heating temperature T1 is in the range of 100 to 400 ° C, and/or the first calcination time is in the range of 60 to 150 minutes. Preferably, the first heating temperature T1 is in the range of 125 to 350 ° C, and/or the first calcination time is in the range of 70 to 140 minutes; more preferably, the first heating temperature T1 is in the range of 150 to 150 The range of 300 ° C, and / or the first calcination time is in the range of 80 to 130 minutes; particularly preferred is: the first heating temperature T1 is in the range of 175 to 250 ° C, and / or the first calcination time is in 85 Up to 120 minutes.

Further, according to another embodiment of the present invention, a calcium oxide may be further provided, wherein the second heating temperature T2 is in the range of 200 to 700 ° C, and/or the second calcination time is in the range of 60 to 150 minutes; Preferably, the second heating temperature T2 is in the range of 250 to 650, and/or the second calcination time is in the range of 70 to 140 minutes; more preferably, the second heating temperature T2 is in the range of 300 to 600 °C. The range, and/or the second calcination time is in the range of 80 to 130 minutes; particularly preferably, the second heating temperature T2 is in the range of 350 to 550 ° C, and/or the second calcination time is in the range of 85 to 120 The range of minutes.

Further, according to another embodiment of the present invention, a calcium oxide may be additionally provided, wherein the third heating temperature T3 is in the range of 400 to 900 ° C, and/or the third calcination time is in the range of 60 to 150 minutes; Preferably, the third heating temperature T3 is in the range of 450 to 850, and/or the third calcination time is in the range of 70 to 140 minutes; more preferably, the third heating temperature T3 is in the range of 500 to 800 °C. The range, and/or the third calcination time is in the range of 80 to 130 minutes; particularly preferably, the third heating temperature T3 is in the range of 550 to 750 ° C, and/or the third calcination time is in the range of 85 to 120 The range of minutes.

According to another embodiment of the present invention, a calcium oxide may be additionally provided, wherein the fourth heating temperature T4 is in the range of 600 to 1200 ° C, and/or the fourth calcination time is in the range of 60 to 150 minutes; preferably. The fourth heating temperature T4 is in the range of 650 to 1150 ° C, and / or the fourth calcination time is in the range of 70 to 140 minutes; more preferably, the fourth heating temperature T4 is in the range of 700 to 1100 ° C The range, and/or the fourth calcination time is in the range of 80 to 130 minutes; particularly preferably, the fourth heating temperature T4 is in the range of 750 to 1050 ° C, and/or the fourth calcination time is in the range of 85 to 120 minutes. The scope.

According to another embodiment of the present invention, a calcium oxide may be additionally provided, wherein the fifth heating temperature T5 is in the range of 1000 to 1500 ° C, and/or the fifth calcination time is in the range of 90 to 150 minutes; preferably. The fifth heating temperature T5 is in the range of 1050 to 1450 ° C, and / or the fifth calcination time is in the range of 95 to 145 minutes; more preferably, the fifth heating temperature T5 is in the range of 1100 to 1400 ° C The range, and/or the fifth calcination time is in the range of 100 to 140 minutes; particularly preferably, the fifth heating temperature T5 is in the range of 1150 to 1350 ° C, and/or the fifth calcination time is in the range of 115 to 135 minutes. range.

The preparation method as described above, wherein the calcium oxide obtained has an average particle diameter in the range of from 1 nm to 600 nm.

The above preparation method further comprises (4) a fine grinding step of grinding the calcium oxide by a grinder to obtain a calcium oxide powder having an average particle diameter of 15 nm or less.

In the following, various embodiments of the present invention will be described and illustrated in detail in order to provide a more complete and easy understanding of the spirit and scope of the present invention; however, those of ordinary skill in the art should understand The invention is of course not limited to such examples, and other equivalent or equivalent functions and order of steps may be utilized to achieve the invention.

In addition, the scope of the invention may be further exemplified by the following specific examples, which are not intended to limit the scope of the invention. "Embodiment 1"

First, the egg shell is placed in an ultrasonic cleaner for 20 minutes to remove surface impurities; then, the detergent is further washed for 30 minutes, and finally taken out and washed thoroughly with flowing water to remove the residual washing liquid; wherein the detergent is 100 mg of S1, 50 mg of S2, 50 mg of S3, and 50 mg of S4.

After the eggshell is cleaned, as shown in Table 1, the washed eggshell is transferred to a low temperature drying chamber preheated to 110 ° C for 20 minutes to dry the inner and outer surfaces of the eggshell, as shown in Figure 1; After the dried eggshell is placed in the ashing furnace, a calcination process is performed, which comprises: first, calcining at a first temperature (300 ° C) for a first time (240 minutes); then, at a second temperature (600 ° C) The calcination is carried out for a second time (210 minutes), and the obtained eggshell powder is as shown in FIG. 2; then, calcination is carried out at a third temperature (800 ° C) for a third time (90 minutes); after the calcination is completed, oxidation can be obtained. Calcium powder, as shown in Figure 3. Next, the eggshell powder obtained above was subjected to measurement of the content of calcium oxide by potassium permanganate titration. Specifically, first, the fine scale eggshell powder is placed in a 250 ml beaker, and 1 ml of 36% hydrogen chloride (HCL) and 20 ml of pure water are added, and after heating and dissolved, the filtrate is transferred to a beaker, and then 50 ml is added. 5% solution of (NH ₄ ) ₂ C ₂ O ₄ , if precipitation occurs, dissolve it by adding hydrogen chloride (HCL); then continue heating to 70~80 ° C, then add 2~3 drops of methyl orange The solution is red reacted, 10% NH ₄ OH is added dropwise, stirring is continued until the solution turns yellow, and calcium oxalate (CaC ₂ O ₄ ) precipitates and the ammonia taste overflows; after filtration, the calcium oxalate is filtered. After the (CaC ₂ O ₄ ) precipitate is washed 2 to 3 times with pure water, the precipitate is taken out and dissolved in a triangular flask with dilute sulfuric acid, and then washed 1 to 2 times with pure water; the solution is heated to 70~ At 80 ° C, using a 0.02 M KMnO ₄ standard solution titration is a reddish reaction and remains unchanged for 30 seconds, which is the end point; then, calculate the content of calcium oxide (CaO) contained in the eggshell powder per unit weight. The ratio is expressed as a percentage; the results are reported in Table 1.

Then, the average particle diameter and the particle size distribution of the calcium oxide powder obtained above were measured by a laser light scattering type particle size analyzer to measure the average particle diameter and the particle size distribution, and the results are shown in Table 1. <<Example 2-6>>

Calcium oxide powder was prepared in the same manner as in Example 1 except that the preparation conditions described in Table 1 were carried out. The results are shown in Table 1.

Table 1         <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> </td><td> </td><td> </td><td> Example 1 </td><td> Example 2 </td><td> Example 3 </td><td> Example 4 </td><td> Example 5 </td><td> Example 6 </td></tr><tr><td> Eggshell Source</td><td> </td><td> </td><td> Egg Shell</td><td> Egg shell</td><td> duck eggshell</td><td> duck eggshell</td><td> goose eggshell</td><td> goose eggshell</td></tr><tr ><td> Cleaning Agent</td><td> S1 </td><td> (mg) </td><td> 100 </td><td> 50 </td><td> 50 </ Td><td> 50 </td><td> 50 </td><td> 50 </td></tr><tr><td> S2 </td><td> (mg) </td ><td> 50 </td><td> 100 </td><td> 100 </td><td> 50 </td><td> 50 </td><td> 50 </td>< /tr><tr><td> S3 </td><td> (mg) </td><td> 50 </td><td> 50 </td><td> 50 </td><td > 100 </td><td> 50 </td><td> 50 </td></tr><tr><td> S4 </td><td> (mg) </td><td> 50 </td><td> 50 </td><td> 50 </td><td> 50 </td><td> 100 </td><td> 100 </td></tr>< Tr><td> drying temperature</td><td> 80°C </td><td> (min) </td><td></td><td> 20 </td><td> < /td><td> </td><td> </td><td> </td></tr><tr><td> 90°C </td><td> (min) </td><td></td ><td> </td><td> 20 </td><td> </td><td> 20 </td><td> </td></tr><tr><td> 100°C </td><td> (min) </td><td></td><td> </td><td> </td><td> 20 </td><td> </td> <td> 20 </td></tr><tr><td> 110°C </td><td> (min) </td><td> 20 </td><td> </td>< Td> </td><td> </td><td> </td><td> </td></tr><tr><td> calcination temperature T1 </td><td> 150°C < /td><td> (min) </td><td></td><td> </td><td> </td><td> 240 </td><td> 120 </td> <td> </td></tr><tr><td> 300°C </td><td> (min) </td><td> 240 </td><td> 200 </td>< Td> 150 </td><td> </td><td> </td><td> </td></tr><tr><td> 450°C </td><td> (min) </td><td></td><td> </td><td> </td><td> </td><td> </td><td> 150 </td></tr ><tr><td> Calcination temperature T2 </td><td> 450°C </td><td> (min) </td><td></td><td> </td><td> </td><td> </td><td> 250 </td><td> </td></tr><tr><td> 600°C </td><td> (min) </ Td><td> 210 </td><td> 150 </td><td> 250 </td><td> </td><td> </td><td> </t d></tr><tr><td> 750°C </td><td> (min) </td><td></td><td> </td><td> </td>< Td> 210 </td><td> </td><td> 150 </td></tr><tr><td> calcination temperature T3 </td><td> 700°C </td><td > (min) </td><td></td><td> </td><td> </td><td> </td><td> 180 </td><td> </td ></tr><tr><td> 800°C </td><td> (min) </td><td> 90 </td><td> 120 </td><td> 150 </td ><td> </td><td> </td><td> </td></tr><tr><td> 900°C </td><td> (min) </td><td ></td><td> </td><td> </td><td> 90 </td><td> </td><td> 90 </td></tr><tr>< Td> average particle size</td><td> </td><td> (nm) </td><td> 245±38 </td><td> 258±25 </td><td> 255 ±46 </td><td> 248±38 </td><td> 261±29 </td><td> 288±32 </td></tr><tr><td> calcium oxide content </td><td> (CaO) </td><td> (%) </td><td> 84.83 </td><td> 85.24 </td><td> 86.75 </td><td > 88.92 </td><td> 72.32 </td><td> 89.16 </td></tr></TBODY></TABLE> Note: 1. Cleaning agent S1: from 100 mg of calcium ion powder, 75mg of natural sea salt, 50mg of sodium percarbonate, 25mg of sodium citrate. 2. Cleaning agent S2: consists of 100 mg of calcium ion powder, 50 mg of natural sea salt, 75 mg of sodium percarbonate, and 25 mg of sodium citrate. 3. Cleaning agent S3: consists of 100 mg of calcium ion powder, 25 mg of natural sea salt, 50 mg of sodium percarbonate, and 75 mg of sodium citrate. 4. Cleaning agent S4: consists of 100 mg of calcium ion powder, 25 mg of natural sea salt, 75 mg of sodium peroxycarbonate, and 50 mg of sodium citrate.       

From the results of the above Table 1, it is apparent that the calcium oxide powders obtained in the above Examples 1 to 6 have an average particle diameter measured in the average particle diameter analysis of 245 nm to 288 nm. Between the values of ±25 nm to ±46 nm, the display has good particle size uniformity and can be easily processed. <<Example 7》

First, the egg shell is placed in an ultrasonic cleaner for 20 minutes to remove surface impurities; then, the detergent is further washed for 30 minutes, and finally taken out and washed thoroughly with flowing water to remove the residual washing liquid; wherein the detergent is 100 mg of S1, 50 mg of S2, 50 mg of S3, and 50 mg of S4.

After the eggshell is cleaned, as shown in Table 2, the washed eggshell is transferred to a low-temperature drying chamber preheated to 110 ° C for 20 minutes to dry the inner and outer surfaces of the eggshell; and the dried eggshell is placed. After entering the ashing furnace, a calcination process is performed, which comprises: first, calcining at a first temperature (200 ° C) for a first time (90 minutes); then, calcining at a second temperature (600 ° C) for a second time Time (120 minutes); then, calcination at a third temperature (800 ° C) for a third time (80 minutes); then, at a fourth temperature (950 ° C) for the fourth time (80 minutes); finally, The calcination was carried out at the fifth temperature (1100 ° C) for the fifth time (80 minutes); after the completion of the calcination, calcium oxide powder was obtained, as shown in FIG.

Next, the eggshell powder obtained above was subjected to measurement of the content of calcium oxide by potassium permanganate titration. Specifically, first, the fine scale eggshell powder is placed in a 250 ml beaker, and 1 ml of 36% hydrogen chloride (HCL) and 20 ml of pure water are added, and after heating and dissolved, the filtrate is transferred to a beaker, and then 50 ml is added. 5% solution of (NH ₄ ) ₂ C ₂ O ₄ , if precipitation occurs, dissolve by adding hydrogen chloride (HCL); then continue heating to 70~80 ° C, then add 2~3 drops of methyl orange The solution is red reacted, 10% NH ₄ OH is added dropwise, stirring is continued until the solution turns yellow, and calcium oxalate (CaC ₂ O ₄ ) precipitates and the ammonia taste overflows; after filtration, the calcium oxalate is filtered. After the (CaC ₂ O ₄ ) precipitate is washed 2 to 3 times with pure water, the precipitate is taken out and dissolved in a triangular flask with dilute sulfuric acid, and then washed 1 to 2 times with pure water; the solution is heated to 70~ At 80 ° C, using a 0.02 M KMnO ₄ standard solution titration is a reddish reaction and remains unchanged for 30 seconds, which is the end point; then, calculate the content of calcium oxide (CaO) contained in the eggshell powder per unit weight. The ratio is expressed as a percentage; the results are reported in Table 2.

Then, the average particle diameter and particle size distribution of the calcium oxide powder obtained above were measured by a laser light scattering type particle size analyzer to measure the average particle diameter and the particle size distribution, and the results are shown in Table 2. <<Examples 8-12>>

The eggshell calcium oxide powder was prepared in the same manner as in Example 7 except that the preparation conditions described in Table 2 were used. The results are shown in Table 2. 5 is a photograph of an eggshell powder calcined at 900 ° C in Example 10; FIG. 6 is a photograph of an eggshell powder calcined at 1000 ° C in Example 12; and FIG. 7 is a calcination at 1200 ° C in Example 12. Photo of the eggshell powder.

Table 2         <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> </td><td> </td><td> </td><td> Example 7 </td><td> Example 8 </td><td> Example 9 </td><td> Example 10 </td><td> Example 11 </td><td> Example 12 </td></tr><tr><td> Eggshell Source</td><td> </td><td> </td><td> Egg Shell</td><td> Egg shell</td><td> duck eggshell</td><td> duck eggshell</td><td> goose eggshell</td><td> goose eggshell</td></tr><tr ><td> Cleaning Agent</td><td> S1 </td><td> (mg) </td><td> 100 </td><td> 50 </td><td> 50 </ Td><td> 50 </td><td> 50 </td><td> 50 </td></tr><tr><td> S2 </td><td> (mg) </td ><td> 50 </td><td> 100 </td><td> 100 </td><td> 50 </td><td> 50 </td><td> 50 </td>< /tr><tr><td> S3 </td><td> (mg) </td><td> 50 </td><td> 50 </td><td> 50 </td><td > 100 </td><td> 50 </td><td> 50 </td></tr><tr><td> S4 </td><td> (mg) </td><td> 50 </td><td> 50 </td><td> 50 </td><td> 50 </td><td> 100 </td><td> 100 </td></tr>< Tr><td> drying temperature</td><td> 80°C </td><td> (min) </td><td></td><td> 20 </td><td> < /td><t d> </td><td> </td><td> </td></tr><tr><td> 90°C </td><td> (min) </td><td>< /td><td> </td><td> 20 </td><td> </td><td> 20 </td><td> </td></tr><tr><td> 100°C </td><td> (min) </td><td></td><td> </td><td> </td><td> 20 </td><td> </ Td><td> 20 </td></tr><tr><td> 110°C </td><td> (min) </td><td> 20 </td><td> </td ><td> </td><td> </td><td> </td><td> </td></tr><tr><td> calcination temperature T1 </td><td> 150 °C </td><td> (min) </td><td></td><td> </td><td> </td><td> 150 </td><td> </td ><td> </td></tr><tr><td> 200°C </td><td> (min) </td><td> 90 </td><td> 120 </td> <td> 150 </td><td> </td><td> </td><td> </td></tr><tr><td> 250°C </td><td> (min ) </td><td></td><td> </td><td> </td><td> </td><td> 90 </td><td> 120 </td>< /tr><tr><td> Calcination temperature T2 </td><td> 450°C </td><td> (min) </td><td></td><td> </td>< Td> </td><td> 150 </td><td> </td><td> </td></tr><tr><td> 600°C </td><td> (min) </td><td> 120 </td><td> 150 </td><td> 150 </td><td> </td><td> </td><td> </ Td></tr><tr><td> 750°C </td><td> (min) </td><td></td><td> </td><td> </td>< Td> </td><td> 120 </td><td> 150 </td></tr><tr><td> calcination temperature T3 </td><td> 700°C </td><td > (min) </td><td></td><td> </td><td> </td><td> 120 </td><td> </td><td> </td ></tr><tr><td> 800°C </td><td> (min) </td><td> 80 </td><td> 120 </td><td> 160 </td ><td> </td><td> </td><td> </td></tr><tr><td> 900°C </td><td> (min) </td><td ></td><td> </td><td> </td><td> </td><td> 80 </td><td> 120 </td></tr><tr>< Td> calcination temperature T4 </td><td> 900°C </td><td> (min) </td><td></td><td> </td><td> </td>< Td> 120 </td><td> </td><td> </td></tr><tr><td> 950°C </td><td> (min) </td><td> 80 </td><td> 120 </td><td> 160 </td><td> </td><td> </td><td> </td></tr><tr>< Td> 1000°C </td><td> (min) </td><td></td><td> </td><td> </td><td> </td><td> 80 </td><td> 120 </td></tr><tr><td> calcination temperature T5 </td><td> 1150°C </td><td> (min) </td><td ></td><td> </td><td> </td><td> 120 </td><td> </td><td> </td> </tr><tr><td> 1100°C </td><td> (min) </td><td> 80 </td><td> 120 </td><td> 160 </td> <td> </td><td> </td><td> </td></tr><tr><td> 1200°C </td><td> (min) </td><td> </td><td> </td><td> </td><td> </td><td> 80 </td><td> 120 </td></tr><tr><td > average particle size </td><td> </td><td> (nm) </td><td> 150±5 </td><td> 168±9 </td><td> 188± 11 </td><td> 178±8 </td><td> 165±9 </td><td> 154±15 </td></tr><tr><td> calcium oxide content< /td><td> (CaO) </td><td> (%) </td><td> 89.87 </td><td> 90.56 </td><td> 91.43 </td><td> 88.76 </td><td> 92.82 </td><td> 93.16 </td></tr></TBODY></TABLE> Note: 1. Cleaning agent S1: 100 mg calcium ion powder, 75 mg It is composed of natural sea salt, 50 mg of sodium percarbonate and 25 mg of sodium citrate. 2. Cleaning agent S2: consists of 100 mg of calcium ion powder, 50 mg of natural sea salt, 75 mg of sodium percarbonate, and 25 mg of sodium citrate. 3. Cleaning agent S3: consists of 100 mg of calcium ion powder, 25 mg of natural sea salt, 50 mg of sodium percarbonate, and 75 mg of sodium citrate. 4. Cleaning agent S4: consists of 100 mg of calcium ion powder, 25 mg of natural sea salt, 75 mg of sodium peroxycarbonate, and 50 mg of sodium citrate.       

From the results of the above Table 2, it is apparent that the calcium oxide powders obtained in the above Examples 7 to 12 have an average particle diameter measured in the average particle diameter analysis of from 150 nm to 188 nm. The deviation between ±5 nm and ±15 nm shows good particle size uniformity and can be easily processed.

As exemplified in the first embodiment to the twelfth embodiment, it can be confirmed that, according to the preparation method of the present invention, it is possible to develop a problem that not only improves the above-mentioned problems of the conventional technology, but also not only retains the original characteristics of the calcium oxide powder, but also At the same time, it also has calcium oxide powder with high purity, uniform particle size, low manufacturing cost, easy processing and high economic benefit.

Although the content of the present invention has been described in detail by way of examples as described above, the present invention is not limited to the embodiments. Therefore, the scope of protection to be covered in this case also includes the scope of the patent application described below and the scope defined by it.

A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention; for example, combining or modifying the technical contents exemplified in the foregoing embodiments. As a new embodiment, these embodiments are of course considered as belonging to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a photograph showing the dried eggshell in Example 1 of the present invention. Fig. 2 is a photograph showing the eggshell powder after calcination at 600 °C in Example 1 of the present invention. Fig. 3 is a photograph showing the eggshell powder after calcination at 800 °C in Example 1 of the present invention. Fig. 4 is a photograph showing the eggshell powder after calcination at 1,100 °C in Example 7 of the present invention. Fig. 5 is a photograph showing the eggshell powder after calcination at 900 °C in Example 10 relating to the present invention. Fig. 6 is a photograph showing the eggshell powder after calcination at 1000 °C in Example 12 of the present invention. Fig. 7 is a photograph showing the eggshell powder after calcination at 1200 ° C in Example 12 of the present invention.

no

Claims (8)

A method for preparing calcium oxide, comprising: (1) a washing step: after ultrasonically washing the eggshell, and then feeding the detergent to continue washing, then taking out and washing thoroughly with flowing water to remove the residual washing liquid, wherein The detergent comprises at least one selected from the group consisting of calcium ion powder, natural sea salt, sodium percarbonate, sodium citrate, and mixtures thereof; (2) drying step: washing for the above washing step (1) The netted eggshell is dried at 70 ° C to 140 ° C to dry the inner and outer surfaces of the eggshell; (3) calcination step: the dried eggshell treated by the above drying step (2) is sequentially A temperature (T1), a second temperature (T2), and a third temperature (T3) are subjected to three-stage calcination for each of the first time (X), the second time (Y), and the third time (Z), thereby obtaining one Calcium oxide, wherein after the calcination is completed at the first temperature (T1), the temperature is further increased to the second temperature (T2) for 30 seconds to 100 minutes; after the calcination is completed at the second temperature (T2) And continue to heat up to the third temperature (T3) for 30 seconds to 100 minutes; and T1, T2, T3, X Y, Z meet the following relationship; 100 ° C ≦ T1 ≦ 400 ° C; 200 ° C ≦ T2 ≦ 700 ° C; 400 ° C ≦ T3 ≦ 900 ° C; T1 ≦ T2; T2 ≦ T3; 90 minutes ≦ X + Y + Z ≦ 600 Minutes; and X, Y, and Z are not zero at the same time. The method for preparing calcium oxide according to claim 1, wherein the eggshell is an egg shell, a duck egg shell or a goose egg shell. The method for producing calcium oxide according to claim 1, wherein the drying time is in the range of 10 minutes to 50 minutes. The method for preparing calcium oxide according to claim 1, wherein after the calcination is completed at the third temperature (T3), the temperature is further lowered to the second temperature (T2) for 30 seconds to 10 minutes. The method for preparing calcium oxide according to claim 1, wherein after the calcination is completed at the third temperature (T3), the temperature is further lowered to the first temperature (T1) for 30 seconds to 10 minutes. The method for preparing calcium oxide according to claim 1, wherein the calcining step (3) comprises further calcining for a fourth time (V) at a fourth temperature (T4), wherein T4 and V satisfy the following relationship: T3≦T4 And 600 ° C ≦ T4 ≦ 1200 ° C; 90 minutes ≦ V + X + Y + Z ≦ 600 minutes; and V is not zero with X, Y, Z at the same time. The method for preparing calcium oxide according to claim 6, wherein the calcining step (3) further comprises calcining at a fifth temperature (T5) for a fifth time (W), wherein T5, W satisfy the following relationship: T3≦T5 And 600 ° C ≦ T5 ≦ 1200 ° C; 90 minutes ≦ W + V + X + Y + Z ≦ 800 minutes; and W is not zero with V, X, Y, Z. The method for producing calcium oxide according to claim 1, further comprising (4) a fine grinding step of grinding the calcium oxide with a grinder to obtain fine calcium oxide powder having an average particle diameter of 15 nm or less.