Abstract
The efficiency of acid leaching as a low-cost refining method of metallurgical grade silicon (MG-Si) is determined by the microstructure of silicon. In the present work the influence of microstructure of MG-Si on its leaching behaviour was studied in order to explore the potential of this method in achieving solar grade purity of silicon. The microstructure of silicon was modified by alloying with 3–10 wt-% of calcium, and the influence of the concentration of alloying elements and the solidification conditions on the leaching efficiency was evaluated. It was shown that the major impurity and its location determine the preferred leaching agent. A mechanism of removal of metallic and non-metallic impurities was proposed. Control of the alloying process resulted in enhanced removal of the major part of the impurities, including phosphorus.
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