Experimental examination of the chemical-metallurgical roasting process for iron ore raw materials on the fire grate of a roasting conveyor machine

The results of experimental power engineering examination of operating roasting conveyor machines are presented. These machines are used for complicated energy-intensive chemical-metallurgical process of roasting of iron ore raw materials in moving dense layer with cross feed of heat-carrying gas. The studies were conducted within the temperature ranges of thermal and aerodynamic operating conditions of the existing roasting conveyor machines. The causes of insufficient power engineering efficiency of the chemical-metallurgical roasting process were revealed, qualitative analysis of thermal conditions of roasting dense layer of iron ore raw materials was carried out. The data on temperature distribution of heating gas and iron ore material in different areas of a dynamic dense layer and on a fire grate in different sections of the roasting machine were obtained. The experimental data from technological control of the roasting conveyor machine were presented, as well as the results of chemical and granulometric analyses of roasting iron ore raw materials. Essential deviations in the thermal conditions of operating roasting machine in comparison with designed parameters were found out. The data on roasting conditions of iron ore raw materials in the experimental unit - the sintering pan, which provides simulation of the roasting conditions close to designed ones, are displayed. Insufficient heating in the lower layer levels at the operating roasting machines (in comparison with the designed parameters), stipulated by low speed of heat-carrying gas sweeping in the roasting area was revealed. Temperature heterogeneity along the width of a fire grate, caused by heterogeneity of heat-carrying gas sweeping due to segregation of iron ore material by its size during its loading to the roasting conveyor machine was substantiated scientifically.