Microwave heating can achieve selective heating, heating speed. Most sulphides and some oxides (such as MnO, NiO, etc.) can absorb microwaves in large quantities, and these substances can rise to several hundred degrees Celsius or even thousands of degrees Celsius after irradiation of micro-waves for 1 to 2 minutes, and some substances (such as CaO, SiO2, etc. cannot absorb microwaves in large amounts and cannot be heated to very high temperatures under microwave irradiation.