中试工艺制备微-纳米碳酸钙复合粉体的动力学及其反应终点判定研究

Dynamics and end point of preparation reaction of micro-nano calcium carbonate composite powder by pilot-scale process

在小试确定的最佳工艺条件下,采用中试工艺制备微-纳米碳酸钙(CaCO3)复合粉体,利用pH计、温度计和电导率仪测量了反应体系的酸度、温度和电导率,并分析了其变化规律。研究结果表明,反应体系的起始pH约12,在较长一段时间里保持相对平稳、缓慢下降和迅速下降阶段,反应结束时pH约为7;500目、1250目、5000目、7000目反应体系pH出现拐点的反应时间分别约70、90、100和80min;反应体温度出现拐点的反应时间分别约100、90、100和100min;反应结束后温度上升分别约8、8、6和2℃;电导率出现拐点的反应时间分别约90、90、100和80min。可以根据酸度、温度和电导率值出现拐点,尤其是电导率的拐点,来判断反应结束,研究结果对工业化生产具有指导作用。

The spilot-scale process was used to prepare the micro-nano calcium carbonate composite powder under the experimental conditions determined by the small scale process.The acidity,temperature and conductivity of reaction system were measured by pH meter,thermometer and conductivity meter（TDS）,and their change laws were analyzed.The results showed that the initial value of pH was about 12,and relatively remained stable and declined very slowly for a long time during the reaction,then declined fast,at last declined slowly,the pH was about 7 at the end of the reaction.The pH inflection points of 500,1250,5000 and 7000 mesh reaction systems were about 70,90,100,80 min,respectively.The temperature inflection points were about 100,90,100,100 min,respectively.The conductivity inflection points were 90,90,100,80 min,respectively.The inflection points of curves of acidity,temperature and conductivity of reaction system,especially the curve of conductivity could be used to judge the reaction end point.The investigating results were very important guidance roles for industrial production.