Efficient long-service-life blowing method and system for vanadium extraction-decarburization duplex converters

A method for vanadium extraction from molten iron, comprising:

• smelting a molten iron in a vanadium extraction converter;
• smelting a vanadium-depleted molten iron from the vanadium extraction converter in a decarburization converter;
• combustion on combusting a flue gas from the vanadium extraction converter to obtain a first CO2—N2 mixed gas having a first purity;
• combusting a flue gas from the decarburization converter to obtain a second CO2—N2 mixed gas having a second purity;
• combusting a flue gas from the decarburization converter flue gas to obtain an O2—CO2—N2 mixed gas;
• purifying a first portion of the second CO2—N2 mixed gas in a purification device to obtain a CO2 gas;
• bottom blowing the vanadium extraction converter with the first CO2—N2 mixed gas;
• blowing iron ore powder into the vanadium extraction converter with a second portion of the second CO2—N2 mixed gas;
• and
• bottom blowing the decarburization converter and/or bottom injecting lime powder into the decarburization converter with a mixture of a third portion of the second CO2—N2 mixed gas, the O2—CO2—N2 mixed gas, and the CO2 gas.