In order to recover silicon from diamond wire sawing waste, silicon extraction and boron removal are two key issues that need to be addressed. In this study, a combined process of pressure-less sintering and CaO−SiO 2 slag treatment was proposed. Low -boron silicon was prepared and considered as raw materials in solar cell production. The results confirmed that pressure-less sintering was beneficial for the digestion of the silicon oxide layer, and the molar percentage of oxygen in silicon kerf was reduced from 14.83 to 7.24% after pressure-less sintering at 1400 °C for 2 h. The effect of slag composition on boron removal was investigated. It was found that an optimum boron removal efficiency of 86.91% was obtained when the optical basicity reached 0.68 and no CaF 2 was added; the CaO−SiO 2 mass ratio was 1.2, the holding time was 40 min, and the slag to silicon mass ratio was 1. Although the addition of CaF 2 can decrease the viscosity, it affects the activity and the oxygen potential of slag.
TC4
(Ti–6Al–4V) nanoparticles (TC4NPs) and silicon
nanoparticles (SiNPs) with a median size of 146 and 51 nm were prepared
by sand milling from scrap produced by refining silicon and TC4. The
SiNPs and TC4NPs are mixed, carbonized, and leached in different proportions
to obtain Si@C/TiO2@C/Hollow-C anode materials. The special
structure of the anode materials provided more space for the volume
expansion of silicon. The anatase TiO2 in TC4NPs relieves
the volume expansion and reduces the transfer impedance, and the lithiated
TiO2 can promote the electrical conductivity of the Si@C/TiO2@C/Hollow-C anode during the charge/discharge process. Furthermore,
the Si@C/TiO2@C/Hollow-C (SiNPs/TC4NPs = 2:1) electrode
delivers excellent rate performance; after cycling at a series of
higher current densities, 92% of the original level of the reversible
capacity can be maintained. The Si@C/TiO2@C/Hollow-C (SiNPs/TC4NPs
= 2:1) anode retains 558 mA h·g–1 after 400
cycles with a large current density of 1000 mA·g–1. The synthesis method of the Si@C/TiO2@C/Hollow-C anode
is a low-cost, facile, and nontoxic process, endowing it with the
potential for application as energy materials for mass production.
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