A method of operating an ironmaking or steelmaking plant with low CO.sub.2-emissions is provided. Hydrogen and oxygen are generated by water decomposition and at least part of the generated hydrogen is injected as a reducing gas into one or more ironmaking furnaces with off-gas decarbonation and reinjection into the furnaces of at least a significant part of the decarbonated off-gas and at least part of the generated oxygen is injected as an oxidizing gas in the one or more ironmaking.

Disclosed are methods useful in applications relating to blast furnace processes. The methods of the present invention provide enhanced deposition inhibition of particulate matter in top-pressure recovery turbines. The methods of the present invention comprise adding nitrogen-containing compounds to a top-pressure recovery turbine, inhibiting deposition of solids formed from blast furnace gas on top-pressure recovery turbine components.

Disclosed are methods useful in applications relating to blast furnace processes. The methods of the present invention provide enhanced deposition inhibition of particulate matter in top-pressure recovery turbines. The methods of the present invention comprise adding nitrogen-containing compounds to a top-pressure recovery turbine, inhibiting deposition of solids formed from blast furnace gas on top-pressure recovery turbine components.

The invention relates to a plant complex for steel production comprising a blast furnace for producing pig iron, a converter steel mill for producing crude steel and a gas-conducting system for gases that occur in the production of pig iron and/or in the production of crude steel. According to the invention, the plant complex additionally has a chemical or biotechnological plant connected to the gas-conducting system and a plant for producing hydrogen. The plant for producing hydrogen is connected to the gas-conducting system by a hydrogen-carrying line. Also the subject of the invention is a method for operating the plant complex.

The invention relates to a plant complex for steel production comprising a blast furnace for producing pig iron, a converter steel mill for producing crude steel and a gas-conducting system for gases that occur in the production of pig iron and/or in the production of crude steel. According to the invention, the plant complex additionally has a chemical or biotechnological plant connected to the gas-conducting system and a plant for producing hydrogen. The plant for producing hydrogen is connected to the gas-conducting system by a hydrogen-carrying line. Also the subject of the invention is a method for operating the plant complex.

A process for operating an oxidizable combustion gas cleaning unit in a metallurgical plant, including the steps of: (a) passing an oxidizable combustion gas from a metallurgical reactor, in particular a blast furnace gas from a blast furnace, in a packed bed scrubber arrangement through a packed bed in countercurrent with a washing water or in a spray scrubber arrangement to remove cyanide compounds, in particular hydrogen cyanide, and to increase the removal of chloride compounds, in particular hydrogen chloride, from the combustion gas by solubilizing the cyanide and chloride compounds in the washing water, (b) collecting the washing water containing solubilized cyanide and chloride compounds at a bottom end of the packed bed or spray scrubber arrangement, and (c) collecting a cleaned oxidizable combustion gas at a top of the packed bed or spray scrubber arrangement, wherein a base is added to the washing water before step (a).

The present blast furnace and method for operating a blast furnace are able to reduce CO.sub.2 production and the amount of applied additives and heating material. The method for metal production of metal ores comprising the following steps: reducing a metal ore, particularly a metal oxide, and thereby producing furnace gas containing CO.sub.2 in a blast furnace shaft; discharging the furnace gas from the blast furnace shaft; directing at least a portion of the furnace gas into a CO.sub.2 converter and reducing the CO.sub.2 in the furnace gas into CO; directing at least a portion of the CO from the CO.sub.2 converter into the blast furnace shaft. The method produces CO as a gaseous reduction agent which may be easily introduced into the blast furnace shaft. Further, a blast furnace for metal production by reducing a metal ore designed for operating according to the method is described.

The present blast furnace and method for operating a blast furnace are able to reduce CO.sub.2 production and the amount of applied additives and heating material. The method for metal production of metal ores comprising the following steps: reducing a metal ore, particularly a metal oxide, and thereby producing furnace gas containing CO.sub.2 in a blast furnace shaft; discharging the furnace gas from the blast furnace shaft; directing at least a portion of the furnace gas into a CO.sub.2 converter and reducing the CO.sub.2 in the furnace gas into CO; directing at least a portion of the CO from the CO.sub.2 converter into the blast furnace shaft. The method produces CO as a gaseous reduction agent which may be easily introduced into the blast furnace shaft. Further, a blast furnace for metal production by reducing a metal ore designed for operating according to the method is described.

The invention relates to a process for preparing ammonia gas and CO.sub.2 for urea synthesis. In the process of the invention, a process gas containing nitrogen, hydrogen and carbon dioxide as main components is produced from a metallurgical gas. The metallurgical gas consists of blast furnace gas, or contains blast furnace gas at least as a mixing component. The process gas is fractionated to give a gas stream containing the CO.sub.2 component and a gas mixture consisting primarily of N.sub.2 and H.sub.2. An ammonia gas suitable for the urea synthesis is produced from the gas mixture by means of ammonia synthesis. CO.sub.2 is branched off from the CO.sub.2-containing gas stream in a purity and amount suitable for the urea synthesis.

The invention relates to a process for preparing ammonia gas and CO.sub.2 for urea synthesis. In the process of the invention, a process gas containing nitrogen, hydrogen and carbon dioxide as main components is produced from a metallurgical gas. The metallurgical gas consists of blast furnace gas, or contains blast furnace gas at least as a mixing component. The process gas is fractionated to give a gas stream containing the CO.sub.2 component and a gas mixture consisting primarily of N.sub.2 and H.sub.2. An ammonia gas suitable for the urea synthesis is produced from the gas mixture by means of ammonia synthesis. CO.sub.2 is branched off from the CO.sub.2-containing gas stream in a purity and amount suitable for the urea synthesis.