Microwave-assisted infrared thermography: A tool for quality assessment of blast furnace feeds

Abstract

Infrared thermography is a ubiquitous technique for surface non-contact temperature profile analysis and monitoring. The generated thermograms offer a plethora of applications in non-destructive evaluation (NDE) for detecting inhomogeneities in engineering structures. However, the potential of this technique is still in its infancy for quality assessment of minerals and ores. In steel plants, iron ore and coke are the most important raw materials fed into the blast furnace. The alumina content in iron ore and moisture percentage in coke play a significant role in determining ultimate product quality and blast furnace efficiency. Till date, plant operators have relied on time-consuming and cumbersome chemical analysis methods for quality analysis of ores. The present investigation reveals a microwave-assisted infrared thermography based non-invasive technique for fast and accurate quality evaluation of blast furnace feed material, in terms of alumina content in iron ores and moisture content in coke. The estimation of alumina content is based on the difference in dielectric constants of various iron ore constituents. Moisture analysis in coke involves the utilization of well-known black body radiation. The co-relation factor for the alumina content in iron ore is slightly lower than the moisture content in coke. The basic difference occurs owing to inherent limitation of the technique for two different substances. Such type of novel approach is scanty in open domain literature. This non-invasive, real time, precise and fast technique proved its enormous potential during validation for random plant samples and thus promising to improve feed quality and blast furnace efficiency.