Abstract The coke quality depends on the characteristics of coal blend, pre-carbonization techniques adopted such as stamping, vibro-compaction etc., and coking conditions. Out of these properties, coal blend is an important role in the production of quality coke. Also, the quality of the blend depends on the quality of individual coals and their interaction during carbonization. The coals are in contact with air for periods of time during transportation and stockpiling, which sometimes may exceed several months. In these periods, reaction of coals with oxygen in the presence of water, sunlight and possibly raised the temperatures. The resulting weathered coal suffers some alteration in its technological properties, which in turn affects coke quality for blast furnace operation adversely. In this work, two coals belong to prime hard coking categories, namely Coal A and Coal B, were selected and kept in a separate stock pile for a period of 120 days. These coals were characterized in terms of proximate, rheological and petrography properties at a regular frequency. This paper summarizes the impact of weathering on the coking behavior of these two coals in terms of properties as mentioned above. However, the rate of loss depends on coal rank and storage conditions. Deterioration of rheological and petrographic properties were seen higher for Coal B compared to Coal A. Low-rank coal deteriorates at a faster rate because low-rank coal is dominated by free radicals that easily react with oxygen, resulting in the creation of various carbonyl groups and weathered vitrinite. Based on the results obtained in this study, size of stock piles for different coals to be maintained, at a specific time, can be determined and recommended, so that target coke quality is always achieved.
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