A method for making reduced iron using blast-furnace sludge is provided. The method includes a mixing step of mixing the blast-furnace sludge and an iron-oxide-containing powder to prepare a mixed material, an agglomerating step of agglomerating the mixed material to form agglomerates, a feeding step of feeding the agglomerates onto a continuously moving hearth, and a reducing step of heating the agglomerates to remove zinc and reduce the agglomerates.

A method of producing stainless steel includes the steps of melting a raw material in an electric furnace to form molten steel, and then refining the molten steel by a refining furnace to produce stainless steel in a stainless steel producing process. In the method, a carbonaceous reducing agent is added to a zinc-containing waste material produced in the stainless steel producing process, the resultant mixture is agglomerated by a briquette press to form agglomerates incorporated with a carbonaceous material, the agglomerates incorporated with the carbonaceous material are heated in a rotary hearth furnace to reduce and evaporate zinc to form dezincified agglomerates, and then the dezincified agglomerates are charged as a coolant in an oxidation period of the refining furnace.

In a method of producing metallic iron by reducing and melting a raw material, which contains an iron oxide-containing material and a carbonaceous reducing agent, by heating, the raw material for producing metallic iron is supplied after a powder and granular atmosphere control carbonaceous material is spread on a hearth of a heat-reducing furnace. In this case, a non-resolidificable carbonaceous material is used as the atmosphere control carbonaceous material, and thus a phenomenon that the powder and granular carbonaceous material is resolidified into a rice-cracker-like shape can be suppressed, thereby permitting solid-phase reduction with high efficiency and stable operationality.

The prevent invention provides a method for producing a feed material for molten metal production and a method for producing a molten metal capable of sufficiently carbonizing biomass and effectively using carbonized biomass as a reducing agent. In the method for producing a feed material for molten metal production, a mixture containing an iron oxide-containing material and biomass is heated in a heating furnace substantially isolated from oxygen to carbonize the biomass in the mixture and obtain a feed material for molten metal production, or the mixture is charged in a reducing furnace to reduce the iron oxide-containing material after being heated in the heating furnace. In the method for producing a molten metal, the feed material for molten metal production obtained by the method for producing a feed material for molten metal production is charged in a melting furnace to obtain a molten metal.

A method for making molten iron includes the steps of feeding a raw material mixture containing an iron oxide material and a carbonaceous reductant into a heating reduction furnace to reduce iron oxide in the raw material mixture with the carbonaceous reductant into solid reduced iron; transporting the solid reduced iron to a melting furnace; and combustion of a carbonaceous material supplied as fuel to melt the solid reduced iron in the melting furnace for producing molten iron. After the metallization of the solid reduced iron is enhanced to at least 60%, the solid reduced iron is transported to the melting furnace. The amounts of oxygen and the carbonaceous material supplied to the melting furnace are controlled so that the secondary combustion ratio of CO gas in the melting furnace is reduced to 40% or less. The heat transfer efficiency of the secondary combustion heat to the molten iron is preferably increased to at least 60%.