硼酸重结晶过程影响因素研究

研究H3BO3-H2O简单体系中,在无外加影响因素的条件下,硼酸质量分数、结晶温度、结晶时间及搅拌速度对硼酸重结晶的影响规律.在相同的结晶温度和结晶时间的条件下,硼酸的质量分数控制在28.5%~31.0%,结晶率可达88%以上.结晶温度选择5~10℃之间,不同的降温方式对硼酸的结晶率影响不大.采用在高温时快速冷却,待降至一定温度后,再慢速冷却降温,可以保证硼酸结晶体多数为具有一定粒度的颗粒.在实验室现有条件下,硼酸的结晶时间在15 h附近为宜.选择硼酸质量分数为28.5%,最终结晶温度为10℃,恒温时间为15 h的实验条件下,慢速搅拌有助于硼酸晶体的生成.

On the Influencing Factors on H_3BO_3 Recrystallization

Discusses emphatically some influencing factors on the recrystallization of H3BO3, such as the solution concentration, crystallization temperature/time and stirring speed in the solution of H3BO3-H2O system. The rate of crystallization can be up to over 88% if the crystallization temperature/time is constant and the boric acid concentration is controlled within 28.5%~31.0%. And if the crystallization temperature is selected in the range of 5~10°C, the different cooling ways all effect slightly the crystallization rate of boric acid. But, if a quenching is implemented during high temperature with the temperature cooled to a certain extent and then cooled slowly, most of boric acid crystals are provided with a certain grain size. In our lab the proper crystallization time is about 15 h. If the boric acid solution concentration is 28.5%, and final crystallization temperature is 10°C that is held for 15 h, the slow stirring speed benefits the formation of boric acid crystals.