铝酸钠(钾)溶液种分过程的分解率和粒度分布

Precipitation rate and particle size distribution of seeded precipitation proceeding in sodium and potassium aluminate solutions

采用等温间歇式反应器研究了纯铝酸钠和铝酸钾溶液在种分过程的分解率、粒度分布(PSD)的变化规律,同时对分解产品进行了XRD、SEM和TG/DTG分析。结果表明,在相同的分解条件下,铝酸钾溶液的分解率大于铝酸钠溶液;铝酸钠和铝酸钾溶液中颗粒的粒度分布随时间变化具有显著差异;产品的XRD显示,分解过程中铝酸钾比铝酸钠溶液中的晶体结晶度完整,但产品的TG/DTG曲线却没有明显的差别。对于不同αk值的铝酸钠和铝酸钾溶液,这些差异是相似的。铝酸钾与铝酸钠溶液在种分过程中的成核速率不同可能是引起分解率和粒度分布产生差异的原因。

The precipitation rate and particle size distribution(PSD)for pure sodium aluminate solution and potassium aluminate solutions were investigated. The XRD, SEM and TG/DTG curves were used to study the products of sodium aluminate solution and potassium aluminate solution. The results show that the precipitation rate of potassium aluminate solution is larger than that of sodium aluminate solution, and the rate increases with the decrease of (original) α_k of caustic aluminate solution under the same conditions. There are dramatic discrepancies of PSD during the same seeded precipitation condition between sodium aluminate solution and potassium aluminate solution. The XRD patterns of products show that the crystals of potassium aluminate solution have better crystallinity than that of sodium aluminate solution, but the TG/DTG curves of products of sodium aluminate solution and potassium aluminate solution have no obvious difference. These discrepancies are similar in solutions of different α_k(1.45, 1.55, 1.65). It is considered that the difference of nucleation rate between sodium aluminate solution and potassium aluminate solution is the reason for the discrepancy of precipitation rate and PSD during seeded precipitation.