Process method and system for recovering hydrogen fluoride from iron trifluoride-containing mixture

The invention belongs to the technical field of titanium dioxide production by a fluorination method, and particularly relates to a process method and system for recovering hydrogen fluoride from a mixture containing ferric fluoride. The method at least comprises the following steps: 1) firstly heating solid residues containing FeF3 through a solid residue preheater; (2) carrying out pyrohydrolysis reaction on the preheated solid residues and high-temperature steam in a pyrohydrolysis furnace; and (3) discharging a solid-phase product Fe2O3 after the pyrohydrolysis reaction into a Fe2O3 cooler for cooling. Solid residues mainly containing FeF3 are heated by a solid residue preheater and then enter a thermal hydrolysis furnace, and Fe2O3 and hydrogen fluoride gas can be generated after the solid residues react with high-temperature steam in the thermal hydrolysis furnace. And then the solid material Fe2O3 discharged from the pyrohydrolysis furnace can be stored after being cooled by a Fe2O3 cooler. And the gas