Laboratory of Inorganic Materials, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086, Estonia.
J Hazard Mater. 2011 Nov 15;195:139-46. doi: 10.1016/j.jhazmat.2011.08.019. Epub 2011 Aug 12.
In this paper, a method for converting lime-containing oil shale waste ash into precipitated calcium carbonate (PCC), a valuable commodity is elucidated. The mechanism of ash leachates carbonation was experimentally investigated in a stirred semi-batch barboter-type reactor by varying the CO(2) partial pressure, gas flow rate, and agitation intensity. A consistent set of model equations and physical-chemical parameters is proposed to describe the CaCO(3) precipitation process from oil shale ash leachates of complex composition. The model enables the simulation of reactive species (Ca(2+), CaCO(3), SO(4)(2-), CaSO(4), OH(-), CO(2), HCO(3)(-), H(+), CO(3)(2-)) concentration profiles in the liquid, gas, and solid phases as well as prediction of the PCC formation rate. The presence of CaSO(4) in the product may also be evaluated and used to assess the purity of the PCC product. A detailed characterization of the PCC precipitates crystallized from oil shale ash leachates is also provided. High brightness PCC (containing up to ∼ 96% CaCO(3)) with mean particle sizes ranging from 4 to 10 μm and controllable morphology (such as rhombohedral calcite or coexisting calcite and spherical vaterite phases) was obtained under the conditions studied.
本文阐述了一种将含石灰油页岩废渣转化为沉淀碳酸钙（PCC）的方法，PCC 是一种有价值的商品。通过在搅拌式半分批鼓泡塔式反应器中改变 CO(2)分压、气体流速和搅拌强度，对灰渣浸出液碳酸化的机理进行了实验研究。提出了一组一致的模型方程和物理化学参数，用于描述从组成复杂的油页岩灰浸出液中沉淀碳酸钙的过程。该模型能够模拟液体、气体和固体相中反应物种（Ca(2+)、CaCO(3)、SO(4)(2-)、CaSO(4)、OH(-)、CO(2)、HCO(3)(-)、H(+)、CO(3)(2-)）浓度分布，并预测 PCC 的形成速率。还可以评估产品中 CaSO(4)的存在，并用于评估 PCC 产品的纯度。此外，还对油页岩灰浸出液结晶得到的 PCC 沉淀物进行了详细的表征。在研究条件下，可得到高亮度 PCC（含有高达 ∼96%的 CaCO(3)），其平均粒径范围为 4 至 10 μm，且形貌可控（如菱面体方解石或共存的方解石和球霰石相）。
