Suspension roasting process of vanadium-bearing stone coal: Characterization, kinetics and thermodynamics

Abstract

The thermodynamics, kinetics, phase transformation, and microstructure evolution of vanadium-bearing stone coal during suspension roasting were systematically investigated. Thermodynamic calculations showed that the carbon in the stone coal burned and produced CO2 in sufficient oxygen during roasting. The mass loss of stone coal mainly occurred within the temperature range from 600 to 840 °C, and the thermal decomposition reaction rate increased to the peak at approximately 700 °C. Verified by the Flynn—Wall—Ozawa (FWO) and Kissinger—Akahira— Sunose (KAS) methods, the thermal decomposition reaction of stone coal was described by the Ginstling—Brounshtein equation. The apparent activation energy and pre-exponential factors were 136.09 kJ/mol and 12.40 s—1, respectively. The illite in stone coal lost hydroxyl groups and produced dehydrated illite at 650 °C, and the structure of sericite was gradually destroyed. The surface of stone coal became rough and irregular as the temperature increased. Severe sintering occurred at the roasting temperature of 850 °C.