International method for determining the activity of quicklime
The activity of quicklime (CaO) is an important indicator for measuring its chemical reactivity, which directly affects its application effects in metallurgy, environmental protection, and building materials. There are certain differences in the international methods for determining the activity of quicklime, mainly divided into three mainstream methods: hydration reaction method, hydrochloric acid neutralization method, and temperature rise method, each with its own characteristics.
1. Hydration reaction method (commonly used in Europe)
This method is based on the rate of reaction between quicklime and water, and evaluates activity by measuring temperature rise or reaction completion over a certain period of time. The European standard (EN 459-2) uses this method to mix quicklime samples with water and record the temperature rise curve during the reaction process to determine the activity level. Its advantage is that it intuitively reflects the hydration performance in practical applications, but it is greatly affected by environmental temperature.
2. Hydrochloric acid neutralization method (commonly used in China and the United States)
China (GB/T 5762) and the United States (ASTM C110) use hydrochloric acid neutralization method, which involves reacting quicklime with water under constant temperature conditions, and maintaining pH stability through hydrochloric acid titration. The amount of hydrochloric acid consumed within 10 minutes (ml) is recorded as the activity index. This method is easy to operate, has good reproducibility, and is suitable for industrial quality control, but it cannot reflect the actual reaction situation at different temperatures.
3. Temperature rise method (commonly used in Japan)
The Japanese Industrial Standard (JIS R9001) uses the temperature rise method to measure the highest temperature and time to reach that temperature after the reaction between quicklime and water, in order to calculate the activity level. This method is closer to actual industrial application scenarios, but is greatly affected by initial water temperature and environmental heat dissipation.
Different countries have their own emphasis on measurement methods, with European and Japanese methods being closer to practical applications, while Chinese and American methods are more conducive to standardized testing. In the future, with the development of global trade, establishing a unified international measurement standard will help improve the quality comparability and market circulation efficiency of quicklime products.
