Patent ID: 6582492
Filing Date: 2003-06-24
Classification: C21B,C21C,Y02P

Abstract:
Method for producing molten pig iron comprising the following steps:(a) reduction of iron ore particles to form pre-reduced iron containing surplus free carbon, said reduction step comprising the following steps: (a1) iron ore is introduced into a multiple-hearth furnace with several superimposed hearths and it is deposited on the uppermost hearth of the multiple-hearth furnace, (a2) the iron ore is gradually transferred to the lower hearths, (a3) a carbon-containing reducing agent is added to one or more of the lower hearths in sufficient amounts to reduce the iron ore and to ensure that there is surplus free carbon, (a4) the multiple-hearth furnace is heated and the iron ore is reduced on contact with the carbon-containing reducing agent and the gases produced by the carbon-containing reducing agent at adequate temperatures, (a5) the excess gas produced by the carbon-containing reducing agent is burnt in the upper part of the multiple-hearth furnace and advantage is taken of the resultant heat to dry and pre-heat the iron ore, (b) transfer while hot of the pre-reduced iron to a melting furnace, (c) melting of the pre-reduced iron in a melting furnace in order to obtain the molten pig iron, wherein the gases from the melting furnace are not injected into the multiple-hearth furnace.