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2011-Sustainable Industrial Processing Summit
|Flogen Star OUTREACH
|2291-1227 (Metals and Materials Processing in a Clean Environment Series)
Almost all the palletizing plants in the world which process iron ores containing hematite now add carbon (anthracite, coke breeze or petroleum coke) to the green pellet mixture. The carbon in this solid fuel reduces the hematite to magnetite. When the magnetite produced is re-oxidised in the pelletising process it produces heat inside each pellet. This form of heat transfer inside the pellet is much more efficient than the transfer from hot process gases heated by external burners.This results in higher production rates with lower total energy consumption and with higher effective capacity of the process fans.This technology works particularly well together with the deep pelletising bed practice that is being introduced into MSCo.The benefits from carbon addition is summarised as fallow:1) Increase in production rate of indurations machine (typically 20 % without modification or increase of grate area or process fan capacity.2) Reduced overall energy consumption (natural gas and electricity) of at least 20%3) More uniform firing with less quality difference between pellet at the top and bottom of the bed on the grate.4) Lower temperature in the grate bars, pellet cars and wind boxes (about 90-110 oC).This gives increased life of expensive equipment, lower maintenance cost and less stoppage time for pallet car changes.For Mobarakeh the addition of carbon (less than 0.65 %) to the green pellets has allowed the new required production levels to be more easily achieved and sustained with an overall decrease in operating cost and with more consistent pellet quality.Usage of solid carbon inside the green pellet also has showed increase the production of a further 0.9 Mtpa of pellet for internal use or sale.