Characteristics of Prepared Coke–biochar Composite and Its Influence on Reduction of NO_x Emission in Iron Ore Sintering

Abstract

Substituting biofuel for coke breeze in the iron ore sintering process has become increasingly attractive. However, coke breeze and straw char separately distributed in the sinter bed lead to poor-quality sinter because of their different combustibilities. In this investigation, a coke–biochar composite (CBC) is produced from coking coal and raw straw, and its behaviour when used as a fuel for sintering is investigated. The results show that the coke and straw char in the CBC interpenetrate and adhere together. Compared with separately distributed coke breeze and straw char, this structure effectively restrains separate combustion of the CBC components. A CBC with 40–60% straw char is recommended as a replacement for coke breeze, with only small changes in sinter quality. The fuel nitrogen conversion rate is decreased by 8.3% during CBC combustion, possibly owing to reducing reactions between C (CO) and NO_x, which further decrease NO_x emission.