The separation of inorganic precipitates with similar solubility products is a challenging task in chemical engineering. We present a computational fluid dynamics study of a precipitation reaction in a flow-driven reactor. For a reference study, the cobalt(II)-copper(II)-oxalate system is selected, where precipitation occurs simultaneously and the difference in solubility is within an order of magnitude as shown experimentally. For general description of two metal ions competing for one common anion, several parameters have been varied to identify the factors responsible for spatial separation. Two new quantities, the mean position of sedimented particles and the precipitation excess, are introduced to characterize the extent of separation. The calculations have shown that complex formation prior to nucleation makes the separation feasible for a wide range of thermodynamic or kinetic parameters. The injection rate can be used for fine tuning both the amounts of precipitate and their spatial separation when complexes are present.

分离具有相似溶度积的无机沉淀物是化学工程中的一项具有挑战性的任务。我们提出了流动驱动反应器中沉淀反应的计算流体动力学研究。作为参考研究，选择了钴 (II)-铜 (II)-草酸盐体系，其中沉淀同时发生，溶解度差异在一个数量级内，如实验所示。对于竞争一种共同阴离子的两种金属离子的一般描述，已经改变了几个参数以识别导致空间分离的因素。引入了两个新量，即沉降颗粒的平均位置和过量降水，以表征分离程度。计算表明，成核前的复杂形成使得分离对于广泛的热力学或动力学参数是可行的。当存在复合物时，注入速率可用于微调沉淀物的量及其空间分离。