A Study on Gas-Solid and Solid-Solid Reactions Using a New TG Setup

摘要

A new thermogravimetric setup was designed to perform well-controlled investigation of kinetics of gas-solid and solid-solid reactions. Comparison of the conventional thermogravimetric procedure with the present method was carried out. Variations in reducing gas concentration during the initial steps of reaction were avoided in this setup. Thus, the rates of gaseous reduction of Fe_2O_3 by the new method were higher than the conventional TGA technique. It was also possible to perform isothermal solid-solid reactions in this system. Influence of temperature, gas flow rate and pellet density on reduction of Fe_2O_3 pellets by H_2-CO mixtures was studied. Higher temperatures enhanced the reduction rates. Using high gas flow rates at low temperatures decreased reduction rates. Slow diffusion of gases in pellets with higher densities lowered the reduction rates. Feasibility of using graphite for selective reduction of iron oxide in the zinc ferrite was investigated. The reaction rates were low and at 1073 K zinc was evaporated.