Application of High Gradient Magnetic Separation for Recovery of Magnetic Micro-nano Particles
Date Issued
2011
Date
2011
Author(s)
Tu, Cheng-Wen
Abstract
This study investigated the recovery of magnetic micro-nano particles using high-gradient magnetic separator (HGMS). The major system parameters examined, include: inlet concentration of magnetic particles (MP) in the solution (CLF,i), volumetric flow rate (QL), magnetic field gradient (▽H), particle size (dp) and other parameters, such as packing density of magnetic media filled in the magnetic separation chamber (ρF). The separation efficiency(ηM), effective separation time (tB) and saturation time of separation chamber by the system parameters were evaluate.
The mainly target particles studied were superparamagnetic particles of SM (SiO2/Fe3O4). For exploring the effects of particle size ,the magnetic Fe3O4 particles with sizes of 5-20,20-30 and 40-60 nm were employed. The magnetic SM particles were prepared using the sol-gel method, yielding the saturation magnetization of 23.19 emu g-1and particle size of 70-80 nm.
The results indicate that a lower QL offers a longer tB and a better ηM for the HGMS. Also, a lower CLF,i of MP allows a large capture radius of magnetic media (rCF), resulting in a longer and a better ηM.The magnetic separation chamber filled with the magnetic media with a high ρF, provides higher magnetic field strength H and magnetic field gradient ▽H for the external magnetic field, and thus a higher ηM. Further, the capture of magnetic particles size with larger tends to reach saturation more easily. Therefore, the limitation of particle size should be considered for the capture of MP using HGMS.
The multi-wire dynamic model was employed to simulate the performances of HGMS. Comparisons of experimental data and prediction indicate satisfactory agreement. The model can be used to predict the tB, optimum QL and other operating parameters, as well as the breakthrough curves. The results illustrate that the saturated magnetic matrix capacity of separation chamber is inversely proportional to the QL and CLF,i, however, is proportional to the magnetic field gradient.
In practice, the model can be applied to simulate the real plant operation. The results may be used for the proper control of switching the magnetic field, thus avoiding the excessive loss of magnetic particles, and the secondary pollution to the environment.
Subjects
High-gradient magnetic separation
magnetic particle
Micro-nano particles
superparamagnetic
SDGs
Type
thesis
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