In order to improve and optimize the lime hydration process equipment and increase the conversion rate of calcium oxide(quicklime) to calcium hydroxide(hydrated lime), experiments were conducted on the effects of different quicklime sizes and hydration water temperature on the hydration time of locally produced lime in Jiande area.
1. Effect of quicklime sizes on hydration time
The experimental results are shown in Table 1. It can be seen from the data in Table 1 that the larger the l quicklime size, the longer the hydration time; the smaller the quicklime size, the shorter the hydration time. The effect of quicklime sizes on hydration time is shown in Figure 2
Table 1: the effect of quicklime size on hydration time
| Quicklime size /mm | Hydration time /s | Total temperature rise /oC |
| 0.15 | 50 | 100 |
| 70 | 110 | |
| 5 | 60 | 100 |
| 80 | 110 | |
| 10 | 65 | 100 |
| 89 | 110 |
2. Effect of hydration water temperature on lime hydration time.
Locally produced lime with a particle size of 10~15mm was used for hydration with water of different temperatures. The experimental data are shown in Table 2. Experimental data shows that during the hydration process of lime, the water temperature directly affects the hydration speed of lime. Under the same particle size conditions, the higher the water temperature, the shorter the hydration time of lime. At the same time, the water temperature also determines the mass, volume and weight ratio of Ca(OH) produced. The effect of hydration temperature on hydration time is shown in Figure 3
Table 2: Hydration experiments with 10~15mm quicklime and different water temperatures
| Water temperature /C | Hydration time /s | Total temperature rise /C |
| 25 | 90 | 110 |
| 50 | 60 | 110 |
| 80 | 30 | 110 |
3.Conclusion:
The above experimental data shows that the optimal particle size of lime produced in Jiande area is 10~15mm, and the hydration water temperature is 80C.
If the lime particle size is too small, impurities such as cinder and carbonic acid in the lime will be mixed into it. During the classifying process, it is difficult to separate it, thereby reducing the calcium hydroxide content. Therefore, according to the requirements of raw materials and product quality, the lime particle size should be appropriately adjusted to produce products with guaranteed quality and quantity.
If the temperature of the hydration water is too high, it will not only affect the safety of equipment and facilities, but also reduce the specific surface area of calcium hydroxide, leading to incomplete hydration.
