Liquid-liquid extraction intensification by micro-droplet rotation in a hydrocyclone

• Published in: Scientific reports 2017-06, Vol.7 (1), p.2678-8, Article 2678
• Main Authors: Huang, Yuan, Wang, Hua-lin, Chen, Yu-quan, Zhang, Yan-hong, Yang, Qiang, Bai, Zhi-shan, Ma, Liang
• Format: Article
• Language: English
• Subjects: 639/166/898; 639/166/988; 704/172/169; Acids; Eddy diffusion; Humanities and Social Sciences; Kerosene; Mass transfer; Mathematical models; multidisciplinary; Nitrates; Reynolds number; Science; Science (multidisciplinary); Simulation; Solvents; Spheres; Turbulence; Velocity
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-017-02732-x

The previous literature reports that using a hydrocyclone as an extractor intensifies the mass transfer and largely reduces the consumption of extractant from 1800–2000 kg h −1 to 30–90 kg h −1 . However, the intensification mechanism has not been clear. This paper presents experimental and numerical methods to study the multi-scale motion of particles in hydrocyclones. In addition to the usually considered translational behavior, the high-speed rotation of dispersed micro-spheres caused by the anisotropic swirling shear flow is determined. The rotation speeds of the tested micro-spheres are above 1000 rad s −1 , which are much larger than the instantaneous rotation speed in isotropic turbulence. Due to the conical structure of a hydrocyclone, the rotation speed maintains stability along the axial direction. Numerical results show that the particle Reynolds number of micro-droplets in a hydrocyclone is equal to that in conventional extractors, but the particles have high rotation speeds of up to 10,000 rad s −1 and long mixing lengths of more than 1000 mm. Both the rotation of micro-droplets along the spiral trajectories and the intense eddy diffusion in a hydrocyclone contribute to the extraction intensification.