Vanadium slag refers to the slag containing vanadium oxide obtained from the oxidation and smelting of vanadium-containing molten iron in the process of vanadium extraction or the wet extraction of vanadium from vanadium-containing iron concentrate. It is the raw material for smelting and making vanadium alloy and metal vanadium. Generally, the content of iron oxide in vanadium slag is very high, generally more than 30%. If the content of iron oxide in vanadium slag is too high, it will increase the iron consumption during vanadium extraction, and make the subsequent processing of vanadium slag more complex. Under the condition that vanadium has a high oxidation rate, the higher the content of iron oxide in vanadium slag is not the better.