A method for manufacturing molten iron by melting a cold iron source in an electric arc furnace having a carbonaceous material-injecting device. The method includes, in the carbonaceous material-injecting device, while a carbonaceous material is injected with a carrier gas through a central portion of the carbonaceous material-injecting device, injecting a fuel and a combustion-supporting gas through respective outer peripheral portions of the carbonaceous material-injecting device. The carbonaceous material injected through the central portion passes through a cylindrical combustion flame generated by a combustion reaction between the fuel and the combustion-supporting gas and is injected into molten slag and molten iron.

A method to control slag foaming in a smelting process in a vessel for smelting an iron-containing feed material including the steps of: measuring vibration of the metallurgical vessel with an accelerometer at one or more positions on the vessel, comparing values derived from accelerometer data with a threshold value which indicates the onset of a slag foaming incident, and adjusting the smelting process if the value derived from the accelerometer data passes a predefined alarm value, wherein the smelting process is adjusted by adjusting the amounts of the gaseous and/or the solid components injected in the smelting process.

A method for manufacturing molten iron by melting a cold iron source in an electric arc furnace having a carbonaceous material-injecting device. The method includes, in the carbonaceous material-injecting device, while a carbonaceous material is injected with a carrier gas through a central portion of the carbonaceous material-injecting device, injecting a fuel and a combustion-supporting gas through respective outer peripheral portions of the carbonaceous material-injecting device. The carbonaceous material injected through the central portion passes through a cylindrical combustion flame generated by a combustion reaction between the fuel and the combustion-supporting gas and is injected into molten slag and molten iron.