To Establish the Feasibility of IR Thermography for Sorting of Iron Ores for Identifying & Rejecting Alumina Rich Ores

Abstract

Indian Iron & Steel Industry is nearly a century old & growing at a rapid pace which has become the world‘s fifth-largest producer of crude steel. India has large reserves of relatively high quality iron ore of which 60% is hematite but generally contains high alumina as an impurity. The alumina content in Iron-ore fines used in sinter making all over the world is less than 1% in contrast to Indian ore fines are as high as 3% which leads to increased slag viscosity, more coke consumption & CO2 emission above international benchmarks resulting in reduced blast furnace productivity. To increase the blast furnace productivity, iron content should be more than 65%, alumina content should be less than 2% and alumina/silica ratio should be less than 1. Hence, in order to enhance the competitive edge of Indian iron & steel industry, an efficient alumina rich ore removal technology is essential. The present work aims to establish the feasibility of Infrared Thermography for the same. The work is directed towards active excitation of iron ores using infrared lamp followed by recording thermographic image which clearly distinguishes high iron & rich alumina content ores. The image is analyzed by software which on the basis of a threshold temperature rejects the high alumina content ores as they reached lower temperature than high iron content ore during the same period of excitation. The present system can be automated for continuous online monitoring while the ore runs on conveyer belt. According to one estimate, if alumina content in the sinter is reduced to less than 2% will improve the RDI (Reduction-degradation index) by at least six points, lower blast furnace coke rate by 14kg per tonne of hot metal & increase its productivity by about 30% under Indian operating conditions.