非均质矿层CO_(2)+O_(2)地浸采铀溶浸过程数值模拟与调控

砂岩型含铀储层介质呈空间非均质性,易产生溶浸死角,是造成铀资源浸出率低的主要因素。定量刻画矿层非均质性,评价非均质条件下,地浸采铀水动力和铀浸出过程,以动态调整溶浸剂注入方式控制矿层内部浸铀行为。该文以北方某砂岩型铀矿局部CO_(2)+O_(2)地浸单元为研究对象,采用基于转移概率的地质统计法建立地浸矿层随机岩性结构模型,嵌入CO_(2)+O_(2)地浸采铀反应性溶质运移模型中,采用随机模拟和不确定性分析研究含矿储层介质非均质性对浸铀水动力、溶浸范围和铀浸出过程的影响,基于模拟结果设计抽/注单元布置方案。结果表明:岩性结构的非均质性控制着溶浸过程中地下水位和浸铀浓度的变幅区间,影响铀浸出浓度峰值和峰值到达时间;基于数值模型进行地浸方案的优化调整,可缩短铀矿与溶浸液接触反应时间,提升反应比表面积,以达到提高铀浸出效率的目的。该研究可为开展采区尺度CO_(2)+O_(2)浸出过程的精准模拟和调控提供技术支撑。

Cooling Rate Sensitivity of RE-Containing Grain Refiner and Its Impact on the Microstructure and Mechanical Properties of A356 Alloy

The cooling rate sensitivities of A1TiB, RE and A1TiB-RE refiners were investigated using laboratory experiments and the actual industrial applications of A356 automotive wheel via low pressure die casting technology. Their impact mechanisms on the microstructure and mechanical properties of the A356 alloy were discussed. The results demonstrated that the AITiB-RE refiner possessed most effective and synergetic refinement effects compared to the individual A1TiB or RE refiners. The A1TiB-RE refiner exhibited the least sensitivity to the cooling rate changes than the other refiners. The comprehensive properties of alloy wheel refined by the A1TiB-RE refiner were improved significantly. The tensile strength, yield strength, and elongation of wheel spoke improved by approximately 11.3%, 10.8% and 44.1%, respectively. The property difference values of the tensile strength, yield strength, and elongation in different positions of the wheel decreased from 14.8%, 31.2% and 47.7% to 8.6%, 27.1% and 30.9%, respectively.