Blast furnace operation methods

Abstract

A method for operating a blast furnace involves blowing hydrogen-based reducing gas into the blast furnace; separating and removing CO2 and H2O gases from the top exhaust gas to generate modified top circulating gas; and blowing the modified top circulating gas into the blast furnace. The method is characterized by including: obtaining a target range for the milling ratio during operation based on a pre-obtained relationship between the amount of hydrogen-based reducing gas blown in and the total pressure loss; and adjusting the operating conditions so that the milling ratio falls within the target range during operation.

Claims

1. A method for operating a blast furnace, comprising: blowing hydrogen-based reducing gas into the blast furnace; separating and removing CO2 gas and H2O gas from the top exhaust gas to generate modified top circulating gas; and blowing the modified top circulating gas into the blast furnace; the method for operating the blast furnace is characterized by comprising: obtaining a target range of milling ratio during operation based on a prior obtained relationship between the amount of hydrogen-based reducing gas blown in and the total pressure loss; and adjusting the operating conditions so that the milling ratio during operation falls within the target range of the milling ratio.

2. The blast furnace operation method as described in claim 1, wherein when the aforementioned hydrogen-based reducing gas injection rate is kept constant at 600 Nm3 / t, the aforementioned discharge-milling ratio range is set to be greater than 2.7 t / d / m3 and less than 3.7 t / d / m3.

3. The blast furnace operation method as described in Request 2, wherein the aforementioned output-to-milling ratio range is set to below 3.0 t / d / m3.

4. The blast furnace operation method as described in any of the requests 1 to 3, wherein the combustion temperature at the tuyeres outlet is maintained above 2100°C.

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