Methods and systems for low-slag efficient smelting based on submerged supersonic gas-solid injection

A method for low-slag efficient smelting based on submerged supersonic gas-solid injection, comprising:

• in a raw material charging period, and in a scrap steel and molten iron charging stage, controlling a submerged supersonic gas-solid oxygen lance in a protective gas mode, wherein a protective gas flow rate is 10-200 m3/h;
• in a melting period, in response to determining that charging of raw material is completed, changing the submerged supersonic gas-solid oxygen lance to an oxygen supply mode, wherein the submerged supersonic gas-solid oxygen lance is extended into a slag layer, and an oxygen flow rate is 600-3000 m3/h;
• in response to determining that the oxygen flow rate reaches a preset value, changing the submerged supersonic gas-solid oxygen lance to a gas-solid injection mode, wherein an outlet of the submerged supersonic gas-solid oxygen lance includes, from inside to outside, a gas-solid channel, a first annular oxygen channel, an annular combustion channel, and a second annular oxygen channel, a flow rate of slag-forming material of the gas-solid channel is 30-200 kg/min, the oxygen flow rate is 600-3000 m3/h, the oxygen flow rate of the first annular oxygen channel is 10-200 m3/h, a methane flow rate of the annular combustion channel is 20-400 m3/h, and the oxygen flow rate of the second annular oxygen channel is 10-200 m3/h;
• in an oxidation and temperature-rising period, and in an early stage of oxidation and temperature rising, maintaining the flow rate of the slag-forming material at 50-200 kg/min;
• in a late stage of oxidation and temperature rising, controlling the flow rate of the slag-forming material to be not greater than 50 kg/min;
• after completion of slagging and dephosphorization, changing the submerged supersonic gas-solid oxygen lance to a gas supply mode, wherein the oxygen flow rate is 1500-2500 m3/h;
• in a tapping stage, in response to determining that a temperature of molten steel rises to an expected temperature, controlling the submerged supersonic gas-solid oxygen lance to stop oxygen supply and start the protective gas mode, completing smelting of the molten steel, and performing tapping.