Making quality agglomerates using lean iron ores for sustainable iron-making

Abstract

For sustainable iron making and hassle-free operation of large blast furnaces (BF) and direct reduced iron (DRI) units, a more prepared burden in the form of good quality agglomerates is required. However, the situation is becoming more and more challenging owing to the faster depletion of high-grade iron ore, increased fines generation due to mechanized mining, wide variations in chemistry & mineral characteristics, high content of gangue minerals, and poor liberation characteristics. The growing demand for steel of iron ores has necessitated the utilizationof low-grade iron ores for steel production. The challenges lie in the economic extraction of lean ores and their conversion into quality agglomerates for use in iron making. The utilization of low-grade iron ores has assumed greater significance for the optimal utilization of natural resources and the sustainability of the steel industry. The beneficiated concentrate of banded hematite quartzite (BHQ) iron ore from the Sandur schist belt is used for the pellets. Green pellets with 1.21 ​kg/pellet green compressive strength (GCS) and drop strength of 12 drop number were producedat an optimum binder of 1.2​% and moisture of 9.5​%. Induration of green pellets at a firing temperature of 1300​°C has resulted in adequate pellet properties of 237 ​kg/pellet of cold crushing strength (CCS), 91.87​% tumbler index (TI), 7.41​% reduction degradation index (RDI), and 22.56​% porosity. An attempt is made to produce pellets suitable for iron making by optimizing various raw materials and operating parameters. This will reduce dependency on high-grade ores and effectively utilize low-grade iron ore to produce good-qualityiron-making pellets.