Year: 2012
Type: article
Abstract: Refining of metallurgical-grade silicon was studied using a process sequence of slag treatment, controlled cooling, and acid leaching. A slag of the Na 2 O-CaO-SiO 2 system was used. The microstructure of grain boundaries in the treated silicon showed enhanced segregation of impurities, and the formation of CaSi 2 and other Ca-rich phases. Boron and phosphorus were found in the grain boundary phases of silicon after the slag treatment and were successfully removed together with most of the metallic impurities by acid leaching. The interaction between silicon and slag and the distribution of impurities are discussed. A novel mechanism of the refining approach is proposed, based on the microstructure of silicon and the analysis of impurities at each refining step. Parallel processes of slag refining, segregation, and solvent refining were observed, which explains the relatively high efficiency of the proposed refining technology. The investigated combination of refining processes followed by acid leaching has great potential as an efficient and cost-saving route for upgrading metallurgical-grade to solar-grade silicon.
Source: JOM
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,790
Award: G7499822627
OpenAlex ID: W2010516661