Silicon recovery from metallurgical-grade silicon refined slag by flotation using terpenic oil as surfactant

Abstract

MG-Si (Metallurgical grade silicon) refined slag is mainly composed of silicate and MG-Si. With the increased generation of MG-Si refined slag, the loss of silicon resources has become increasingly severe. Therefore, there is an urgent need to develop methods for silicon recovery from MG-Si refined slag. In this work, silicon recovery was realized by flotation using terpenic oil as the surfactant. Flotation results revealed that with the increasing concentration of terpenic oil, the recovery rate of Si increased from 20.97 ± 0.75% to 77.42 ± 4.40%. The water contact angle of the recovered silicon surface changed from 46.74° to 60.15°. This indicated that the hydrophobicity of the silicon surface increased due to the adsorption of terpenic oil. Meanwhile, the results of adsorption capacity measurements showed that terpenic oil has strong selectivity for adsorption on silicon. The thickness of the layer of terpenic oil on the silicon surface increased with the increasing concentration of the added terpenic oil. These results demonstrated that the addition of terpenic oil was strongly beneficial for the silicon recovery by flotation. This study seeks to provide a more feasible and effective technical route for the large-scale recovery of silicon from MG-Si refined slag. The development of such a route is highly significant for reducing the loss of silicon resources and the clean and sustainable development of silicon industry.