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US 2026/0185172 A1Published application
Method for manufacturing direct reduced iron with a low carbon content
OwnerDmitri BOULANOV, Mahdi FARAHANI +1inventors
InventorsDmitri BOULANOV, Mahdi FARAHANI, Marcelo ANDRADE
Life of this patent
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Abstract
A direct reduction method to manufacture a direct reduced iron product 12 having a carbon content less than 1.8% by weight and a shaft furnace exit temperature lower than 65° C. A carbon-containing cooling gas 30 is introduced into the cooling zone 3 of the shaft furnace 1 with a flow rate higher than 800 Nm3/ton of Direct Reduced Iron produced.
Claims16
1-15. (canceled)
16:
- A method for manufacturing a direct reduced iron product in a shaft furnace having a reduction zone and a cooling zone, the method comprising:
- injecting a reducing gas into the shaft furnace to reduce iron ore, a top gas exiting the shaft furnace, and
- introducing a carbon-containing cooling gas into the cooling zone of the shaft furnace with a flow rate higher than 800 Nm3/ton of direct reduced iron produced, the direct reduced iron product having a carbon content less than 1.8% by weight and a temperature at an exit of the shaft furnace lower than 65° C.
17:
- The method according to claim 16 wherein the direct reduced iron product has a carbon content below 1.5% in weight
18:
- The method according to claim 16 wherein the direct reduced iron product has a carbon content below 1.2% in weight.
19:
- The method according to claim 16 wherein the carbon-containing cooling gas includes up to 20% in volume of CH4.
20:
- The method according to claim 16 wherein the carbon-containing cooling gas includes the top gas, a reformed gas, the reducing gas, natural gas, or carbon dioxide.
21:
- The method according to claim 20 wherein the top gas is subjected to a water removal step before being used as cooling gas.
22:
- The method according to claim 20 wherein the top gas is subjected to a CO2 removal step before being used as cooling gas.
23:
- The method according to claim 16 wherein, before injection into the shaft furnace, the cooling gas has a temperature from 40 to 80° C.
24:
- The method according to claim 16 wherein:
- a. a target of carbon content of the direct reduced iron product is defined,
- b. the gas composition to be provided in the cooling zone of the shaft furnace is determined,
- c. the flow rate of the cooling gas is controlled so as to reach the defined target of carbon content in the direct reduced iron product, based on the determined composition of the gas.
1 more element
25:
- The method according to claim 16 further comprising:
- defining a minimum temperature in the reduction zone of the shaft furnace,
- determining the temperature and the volume of gas in a transition zone of the shaft furnace between the reduction zone and the cooling zone,
- controlling the temperature of the reducing gas before its injection into the shaft furnace, based on the determined temperature and volume of the gas in the transition zone so that the temperature in the reduction zone is above the defined minimum temperature.
1 more element
26:
- The method according to claim 16 wherein after introduction in the cooling region of the shaft furnace the cooling gas upwardly flows through a part of the transition zone of the shaft furnace where the cooling gas is recovered and the recovered cooling gas is cooled, cleaned, and mixed with a make-up gas stream to form a new cooling gas to be injected in the cooling zone of the shaft furnace.
27:
- The method according to claim 26 wherein the make-up gas stream is chosen among the top gas, the reducing gas, a reformed gas, hydrogen, nitrogen, carbon dioxide, ammonia, or a combination of any of those gases.
28:
- The method according to claim 26 wherein the make-up gas stream is added to the recovered cooling gas at a flow rate from 60 to 130 Nm3/ton of direct reduced iron produced.
29:
- The method according to claim 16 further comprising varying a gas temperature at an outlet of the top gas scrubber in the range of 30-80° C.
30:
- The method according to claim 16 further comprising varying a CO2 amount present after the CO2 removal unit.