Process for the production of sponge iron

Claim 2

In a process for the production of sponge iron from iron ore, wherein the iron ore is introduced into the head of a shaft furnace and reduced iron is removed from the bottom thereof as sponge iron, the iron ore being contacted during its descent in the furnace with hot reduction gas produced from a carbon-containing energy carrier and consisting predominantly of carbon monoxide and hydrogen, the improvement wherein: a. said reduction gas is formed a 1 . in part by a desulfurized fresh gas produced by a partial oxidation of a hydrocarbon and desulfurization, and a 2 . in part by recirculated exhaust gas drawn from the head of said furnace having its carbon oxide content reduced by about 10 volume percent; b. said fresh gas is mixed with said exhaust gas in a volume ratio of fresh-gas/exhaust-gas of 0.8 : 1.0 to produce a cold mixed gas having the following composition: ______________________________________ Hydrogen about 45 volume percent Carbon Monoxide about 44 volume percent Water Vapor about 3 volume percent Carbon Dioxide about 6 volume percent Balance, in trace amounts: lower hydrocarbons, nitrogen and impurities; ______________________________________ c. said mixed gas is heated to a temperature of about 1000° C. directly before being introduced into said shaft furnace as said reductin gas; and d. a heated mixed gas is introduced into the shaft furnace at the latter temperature.

Claim 3

The improvement defined in claim 1 wherein said fresh gas is desulfurized in step (a 1 ) by washing sulfur from the gas produced by partial oxidation of said hydrocarbon.

Claim 4

The improvement defined in claim 2 wherein said recirculated exhaust gas has its carbon-oxide content reduced in step (a 2 ) by a deacidification washing of the recirculated exhaust gas.

Claim 5

In a process for the production of sponge iron from iron ore, wherein the iron ore is introduced into the head of a shaft furnace and reduced iron is removed from the bottom thereof as sponge iron, the iron ore being contacted during its descent in the furnace with hot reduction gas produced from a carbon-containing enery carrier and consisting predominantly of carbon monoxide and hydrogen, the improvement wherein: a. said reduction gas is formed a 1 . in part by a desulfurized fresh gas produced by a partial oxidation of a hydrocarbon consisting of sulfur-containing heavy oil and desulfurization, the partial oxidation being effected with an oxidating agent selected from the group consisting of pure oxygen-enriched air, air and water vapor, and a 2 . in part by recirculated exhaust gas drawn from the head of said furnace having its carbon oxide content reduced by about 10 volume percent; b. said fresh gas is mixed with said exhaust gas in a volume ratio of fresh-gas/exhaust-gas of 0.8 : 1.0 to produce a cold mixed gas; c. said mixed gas is heated to a temperature of about 1000° C. directly before being introduced into said shaft furnace as said reduction gas; and d. the heated mixed gas is introduced into the shaft furnace at the latter temperature, said fresh gas having, after desulfurization, the following approximate composition: ______________________________________ Hydrogen 48% by volume Carbon Monoxide 49% by volume Water Vapor 2% by volume Balance, in trace amounts: carbon dioxide, lower hydrocarbons, nitrogen and impurities. ______________________________________

Claim 6

In a process for the production of sponge iron from iron ore, wherein the iron ore is introduced into the head of a shaft furnace and reduced iron is removed from the bottom thereof as sponge iron, the iron ore being contacted during its descent in the furnace with hot reduction gas produced from a carbon-containing enery carrier and consisting predominantly of carbon monoxide and hydrogen, the improvement wherein: a. said reduction gas is formed a 1 . in part by a desulfurized fresh gas produced by a partial oxidation of a hydrocarbon consisting of sulfur-containing heavy oil and desulfurization, the partial oxidation being effected with an oxidating agent selected from the group consisting of pure oxygen-enriched air, air and water vapor, and a 2 . in part by recirculated exhaust gas drawn from the head of said furnace having its carbon oxide content reduced by about 10 volume percent; b. said fresh gas is mixed with said exhaust gas in a volume ratio of fresh-gas/exhaust-gas of 0.8 : 1.0 to produce a cold mixed gas; c. said mixed gas is heated to a temperature of about 1000° C. directly before being introduced into said shaft furnace as said reduction gas; and d. the heated mixed gas is introduced into the shaft furnace at the latter temperature, said fresh gas having, after desulfurization, the following approximate composition: ______________________________________ Hydrogen 48% by volume Carbon Monoxide 49% by volume Water Vapor 2% by volume Balance, in trace amounts: carbon dioxide, lower hydrocarbons, nitrogen and impurities. ______________________________________

Claim 7

The improvement defined in claim 4 wherein said recirculated exhaust gas, after reduction of the carbon-oxide content thereof, has the following approximate composition: ______________________________________ Hydrogen 42% by volume Carbon Monoxide 40% by volume Water Vapor 5% by volume Carbon Dioxide 12% by volume Balance, in trace amounts: lower hydrocarbons, nitrogen, and impurities. ______________________________________

Claim 8

In a process for the production of sponge iron from iron ore, wherein the iron ore is introduced into the head of a shaft furnace and reduced iron is removed from the bottom thereof as sponge iron, the iron ore being contacted during its descent in the furnace with hot reduction gas produced from a carbon-containing energy carrier and consisting predominantly of carbon monoxide and hydrogen, the improvement wherein: a. said reduction gas is formed a 1 . in part by a desulfurized fresh gas produced by a partial oxidation of a hydrocarbon and desulfurization, and a 2 . in part by recirculated exhaust gas drawn from the head of said furnace having its carbon oxide content reduced by about 10 volume percent; b. said fresh gas is mixed with said exhaust gas in a volume ratio of fresh-gas/exhaust-gas of 0.8 : 1.0 to produce a cold mixed gas; c. said mixed gas is heated to a temperature of about 1000° C. directly before being introduced into said shaft furnace as said reduction gas; and d. the heated mixed gas is introduced into the shaft furnace at the latter temperature, soot formation being reduced during heating of the mixed gas in step (c) by introduction of a small quantity of hydrogen sulfide to the mixed gas during the heating thereof.

Claim 9

In a process for the production of sponge iron from iron ore, wherein the iron ore is introduced into the head of a shaft furnace and reduced iron is removed from the bottom thereof as sponge iron, the iron ore being contacted during its descent in the furnace with hot reduction gas produced from a carbon-containing energy carrier and consisting predominantly of carbon monoxide and hydrogen, the improvement wherein: a. said reduction gas is formed a 1 . in part by a desulfurized fresh gas produced by a partial oxidation of a hydrocarbon and desulfurization, and a 2 . in part by recirculated exhaust gas drawn from the head of said furnace having its carbon oxide content reduced by about 10 volume percent; b. said fresh gas is mixed with said exhaust gas in a volume ratio of fresh-gas/exhaust-gas of 0.8 : 1.0 to produce a cold mixed gas; c. said mixed gas is heated to a temperature of about 1000° C. directly before being introduced into said shaft furnace as said reduction gas; and d. the heated mixed gas is introduced into the shaft furnace at the latter temperature, soot formation being reduced during heating of the mixed gas in step (c) by introduction of a small quantity of hydrogen sulfide to the mixed gas during the heating thereof.

Claim 10

In a process for the production of sponge iron or, wherein the iron ore is introduced into the head of a shaft furnace and reduced iron is removed from the bottom thereof as sponge iron, the iron ore being contacted during its descent in the furnace with hot reduction gas produced from a carbon-containing energy carrier and consisting predominantly of carbon monoxide and hydrogen, the improvement wherein: a. said reduction gas is formed a 1 . in part by a desulfurized fresh gas produced by a partial oxidation of a hydrocarbon and desulfurization, and a 2 . in part by recirculated exhaust gas drawn from the head of said furnace having its carbon oxide content reduced by about 10 volume percent; b. said fresh gas is mixed with said exhaust gas in a volume ratio of fresh-gas/exhaust-gas of 0.8 : 1.0 to produce a cold mixed gas: c. said mixed gas is heated to a temperature of about 1000° C. directly before being introduced into said shaft furnace as said reduction gas; and d. the heated mixed gas is introduced into the shaft furnace at the latter temperature, soot formation is limited during the heating of said mixed gas in step (c) by carrying out the heating of said mixed gas at a relatively low temperature below 400° C. in a metallic recuperator and thereafter rapidly heating the initially reheated gas to a temperature of 400° to 800° C. in a cowper-type regenerator composed of refractory material.

Claim 11

In a process for the production of sponge iron or, wherein the iron ore is introduced into the head of a shaft furnace and reduced iron is removed from the bottom thereof as sponge iron, the iron ore being contacted during its descent in the furnace with hot reduction gas produced from a carbon-containing energy carrier and consisting predominantly of carbon monoxide and hydrogen, the improvement wherein: a. said reduction gas is formed a 1 . in part by a desulfurized fresh gas produced by a partial oxidation of a hydrocarbon and desulfurization, and a 2 . in part by recirculated exhaust gas drawn from the head of said furnace having its carbon oxide content reduced by about 10 volume percent; b. said fresh gas is mixed with said exhaust gas in a volume ratio of fresh-gas/exhaust-gas of 0.8 : 1.0 to produce a cold mixed gas: c. said mixed gas is heated to a temperature of about 1000° C. directly before being introduced into said shaft furnace as said reduction gas; and d. the heated mixed gas is introduced into the shaft furnace at the latter temperature, soot formation is limited during the heating of said mixed gas in step (c) by carrying out the heating of said mixed gas at a relatively low temperature below 400° C. in a metallic recuperator and thereafter rapidly heating the initially reheated gas to a temperature of 400° to 800° C. in a cowper-type regenerator composed of refractory material.