Method to Calculate the Limiting and Optimal Conditions of the Chemical and Energy Engineering Process of Calcination of Lump and Pelletized Phosphate Ore Raw Materials on the Grate of a Traveling-Grate Roasting Machine

A method and a mathematical model were proposed to calculate the chemical and energy engineering process of roasting of phosphate ore raw materials in a moving dense bed on the grate of a traveling-grate roasting machine. The results of computational experiments on the developed computer model were used to analyze the limiting and optimal conditions of drying and roasting of lump and pelletized phosphate ore raw materials on the traveling grate of the roasting machine. The limiting conditions for the calcination of lump and pelletized ore raw materials loaded as a monolayer bed of lumps, for co-roasting, and as a bed of phosphorite pellets were determined taking into account the technological restrictions on the existing traveling-grate roasting machines. For phosphate ore raw materials, it was determined that the maximum achievable degree of decarbonization in high-temperature roasting of lumps in the traveling-grate roasting machine is 60%, whereas the pellets can be roasted to a degree of decarbonization of 80%. The method of thermophysical and kinetic studies that was proposed in this paper can be extended to study the laws of thermally activated endothermic chemical-metallurgical calcination processes in a wide class of iron ore raw materials. The presented computer model for calculating the limiting and optimal conditions for the operation of traveling-grate roasting machines is used for the rapid adaptation of industrial plants to the periodically changing properties of ore raw materials supplied for heat treatment.