制备条件对硅藻土助滤剂振实密度影响研究

振实密度是表征硅藻土助滤剂孔隙度的重要指标，文章考察了助熔剂种类、助熔剂添加量、升温速度、焙烧温度、焙烧时间及硅藻土焙烧前的入料细度对硅藻土助滤剂振实密度的影响。试验结果表明，对于临江硅藻土，NaCl、Na2CO3、NaOH、KCl作为助熔剂时获得的硅藻土助滤剂的振实密度比较理想，其中Na2CO3综合指标最优；硅藻土助滤剂产品的振实密度随着助熔剂添加量的增加而逐渐增大，Na2CO3添加量为7%时，助滤剂综合指标最佳；提高焙烧温度和延长焙烧时间对助滤剂振实密度的影响规律相同，都使其增大，考虑助滤剂综合指标 ，温度1 000 ℃，焙烧时间1.5 h效果最优；随着升温速度的增加，助滤剂振实密度呈现先降低后增加的趋势，在5 ℃/min时振实密度最低；随着入料粗颗粒的逐渐加入，助滤剂产品的振实密度先降低后增加，入料细度-150 μm时，振实密度最低。

Effects of preparation condition on tap density of diatomite filter aids

Tap density is an important indicator of diatomite filter aid porosity. The effects of flux type, flux addition, heating rate, calcination temperature, heating preservation period and particle size of raw diatomite on tap density of diatomite filter aid were investigated. The results showed that for Linjiang diatomite, appropriate tap density of diatomite filter aid was obtained when NaCl, Na2CO3, NaOH, and KCl were added as flux, and Na2CO3 was the optimal one. With the increasing of flux addition, the tap density of diatomite filter aid products increased as well, when the Na2CO3 addition was 7%, the comprehensive indexes were the optimal. When the calcination temperature and heat preservation period increased, there was a similar rule on the tap density of diatomite filter aid. Considering the filter aid comprehensive index, the optimal condition was temperature 1 000 ℃ and calcination time 1.5 h. The tap density of diatomite filter aid firstly decreased and then increased with the increase of heating rate, and the lowest tap density was acquired with the rate of 5 ℃/min. With the addition of coarse particles, the tap density of diatomite filter aid reduced in the beginning, but rose at the end, and -150 μm was the optimum particle size.