ABSTRACT Experimental and thermodynamic studies on thermal plasma processing of zircon-carbon mixtures are reported in this paper. Plasma processing of zircon-carbon mixtures to convert the silicate mineral to zirconium dioxide with concurrent removal of silica was studied. Zircon sand was mixed with carbon powder and processed in a specially designed nontransferred arc plasma reactor operated using air as plasma medium. Addition of carbon to zircon facilitated in situ reduction of silica to SiO gas, which escaped with the exhaust gas. More than 96% product purity could be obtained by in-flight removal of silica by processing zircon mixed with sufficient amount of carbon at 25 kW input power. Microstructure analysis showed that in-flight removal of silica facilitated the hexagonal growth pattern and irregularly shaped bulk zirconia crystal structures of monoclinic zirconia. Thermodynamic analysis of in-situ removal of silica by carbo-thermal reduction showed that the amount of carbon had a significant effect. The studies showed that controlled addition of carbon could lower the reaction temperature by more than 500 K and facilitated in situ removal of silica. The studies are technologically relevant and offer useful guidance for making the plasma process economically viable.

中文翻译：

---

通过热等离子体处理从锆石矿物中提取无硅氧化锆

摘要 本文报道了锆石-碳混合物热等离子体处理的实验和热力学研究。研究了锆石-碳混合物的等离子体处理以将硅酸盐矿物转化为二氧化锆，同时去除二氧化硅。锆英砂与碳粉混合，在专门设计的非转移电弧等离子体反应器中处理，使用空气作为等离子体介质。将碳添加到锆石中促进了二氧化硅原位还原为 SiO 气体，该气体随废气逸出。通过在 25 kW 输入功率下处理与足够量碳混合的锆石，在飞行中去除二氧化硅，可以获得超过 96% 的产品纯度。微观结构分析表明，在飞行中去除二氧化硅促进了单斜氧化锆的六边形生长模式和不规则形状的块状氧化锆晶体结构。通过碳热还原原位去除二氧化硅的热力学分析表明，碳量有显着影响。研究表明，控制添加碳可以将反应温度降低 500 K 以上，并有助于原位去除二氧化硅。这些研究在技术上是相关的，并为使等离子工艺在经济上可行提供了有用的指导。研究表明，控制添加碳可以将反应温度降低 500 K 以上，并有助于原位去除二氧化硅。这些研究在技术上是相关的，并为使等离子工艺在经济上可行提供了有用的指导。研究表明，控制添加碳可以将反应温度降低 500 K 以上，并有助于原位去除二氧化硅。这些研究在技术上是相关的，并为使等离子工艺在经济上可行提供了有用的指导。