Co-injection of Noncoking Coal and Natural Gas in Blast Furnace.

The most radical method for saving coke in ironmaking is to inject gaseous, Iiquid and solid substitutes into the blast furnace (BF) hearth by means of tuyeres.Use of one or another type of auxiliary fuel depends on the ratio of their prices, their deposits and the peculiarity of the technology.This paper presents the basic theoreticai proposals of a technology for the simultaneous injection by tuyeres of natural gas (NG) and pulverized coal (PC) with any ratio up to complete exception of one of them.A Iaboratory study has been carried out of the thermal decomposition and gasification of different types of coals, Determination has been made of the softening temperature and melting temperature of the ash of these coals.These temperatures p]ay an important role in optimizing the tuyere assembly design.raceway processes and slag regimes.The factors which determine the oxidizing potential of the raceway have been established.A study has been made of the comparative estimation of NG and PCand the compensation rates for BF operational conditions with simultaneous injection ranges of 0-1 OO m'/tHM NGand 0-200 kg/tH M PC, at a flame temperature of 1 950-2150'C and maintaining other blast and burden parameters constant.The rates automatically compensate th~ch~nges in temperature and the therma] and oxidizing potential in the racewa y, This technology and tuyere assembly design are successfully used at two BFs.