Reduction of Ilmenite and Preparation of Titanium-Based Carbides in the CH4-H2 System

Abstract

Titanium carbide, which exhibits extensive applications across diverse fields, is the focus of this study on its synthesis from low-grade ilmenite in the CH₄-H₂ system. Taking the reduction temperature range of 1100 °C to 1350 °C as a starting point, a distinct "M"-shaped relationship between temperature and the carburizing rate is observed. Metallic iron is recognized as a crucial factor influencing the synthesis of titanium-based carbides from ilmenite, with its accumulation closely linked to the carburizing rate of the reduction products. At 1100 °C -1200 °C, increasing the temperature promotes the aggregation and growth of iron, resulting in an increased carburizing rate of the products. At 1225 °C -1300 °C, most of the metal iron dissolved carbon and transformed into molten state. As the temperature increases, the fluidity of the molten iron improves, allowing it to accumulate and grow, thereby reopening the pores in the matrix and rebounding the carburizing rate. At 1350 °C, the dripping of molten iron causes the pellets to soften and fall, leading to a sudden decrease in the product's carburizing rate. The morphological characteristics of reduced ilmenite pellets demonstrate that as the temperature increases, the wettability of metallic iron and carbide shifts from a non-wetting to a wetting. The reduced product-metallic iron-interconnects and aggregates the dispersed reduced ilmenite into a cohesive mass that encases the TiC_xO_1-x, which results in the incomplete carburization of the ilmenite. This study provides theoretical support for the preparation of carbides by gas-based reduction of ilmenite.