An efficient process of separating silicon and SiC in silicon wire-saw waste was studied. According to the different surface properties of Si and SiC in silicon wire-saw waste, SiC was absorbed by emulsified diesel to achieve the goals of separating Si/SiC. Centrifugal force was applied to the emulsified slurry to enhance the separation of oil?water phase during phase separation process, so the time required of oil?water phase separation was shortened. Adjusting pH of the slurry to change zeta potential of particles, and then to control oil drops size. The relationships of Si/SiC separation effect and phase separation time with slurry pH value were studied respectively. The relationship between the apparent density of oil drops with SiC and the diameter of oil drops was found. Stress analysis of SiC on oil drops surface in centrifugal field was studied, and the movement of SiC on the surface of oil drops in centrifugal field was analyzed. The results showed that the smaller size of oil drops, the longer time of phase separation and better results of removal SiC at normal gravity field. The content of SiC in silicon powder was 4.23wt% at the pH of 7. When the oil drops diameter less than 64 μm, the oil droplets could not float in the slurry. Applying centrifugal force with a gravity coefficient of 10, 50, 100, 150, and 200 to the emulsified slurry, the effect of phase separation and Si/SiC separation with 2 min of centrifugal were investigated. When the gravity coefficient was 100 and pH was 7, the content of SiC in silicon powder was 5.47wt%, the separation time decreased from 460 min to 2 min. It was confirmed that the centrifugal force made SiC moved along the surface of the oil drops to the direction of centrifugal force, which resulted in a decreased of adsorption force.
Zhankui WANG Dong WANG Zhi WANG Wenhui MA Xiaohan WAN
. Centrifugal field enhanced oil-water phase separate in Si/SiC separation process of silicon wire-saw waste[J]. The Chinese Journal of Process Engineering, 2019
, 19(1)
: 118
-125
.
DOI: 10.12034/j.issn.1009-606X.218175
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