Phase Evolution oF Tin Oxides Roasted Under CO–CO₂ Atmospheres in the Presence of Na₂CO₃

ABSTRACT

High-purity Na₂SnO₃ has been prepared by a novel process of roasting SnO₂ and Na₂CO₃ in a solid state under CO–CO₂ mixed gas. In the current study, the phase evolution of tin oxides and Na₂CO₃ roasted under various CO–CO₂ atmospheres was investigated by chemical and X-ray diffraction analysis. Under the CO content of 5–20 vol% and temperature over 800°C, Na₂CO₃ can react with SnO₂ and the intermediate products of SnO and Sn to form Na₂SnO₃. SnO would be decomposed into SnO₂ and Sn at temperatures below 800°C; however, the decomposition reaction was effectively restrained by Na₂CO₃ over 800°C. Na₂CO₃ apparently inhibits the volatilization of SnO. The reaction mechanism of SnO and Na₂CO₃ under reductive atmosphere was clarified.

KEYWORDS:

• CO–CO₂ atmosphere
• Na₂SnO₃
• phase evolution
• roasting
• tin oxides

Funding

The authors wish to express their thanks to the National Natural Science Foundation of China (No. 51574283), the Natural Science Foundation of Hunan Province, China (No. 2016JJ2143), the Co-Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources and the Hunan Provincial Innovation Foundation for Postgraduate Studies (No. CX2015B054).

Additional information

Funding

The authors wish to express their thanks to the National Natural Science Foundation of China (No. 51574283), the Natural Science Foundation of Hunan Province, China (No. 2016JJ2143), the Co-Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources and the Hunan Provincial Innovation Foundation for Postgraduate Studies (No. CX2015B054).