MVR (Mechanical Vapor Recompression) hot-method nitre extraction process

The invention relates to a process method for preparing salt, in particular to an MVR (Mechanical Vapor Recompression) hot-process saltpeter extraction process in a salt preparation process, and belongs to the technical field of chemical engineering. Original brine or refined brine is sequentially preheated and heated, then enters salt evaporation tanks 210 and 210, generated salt slurry is discharged into a salt collecting box, is washed by a salt washing device and then is subjected to centrifugal dewatering and drying, and secondary steam generated by the salt evaporation tank 210 enters the salt evaporation tank 210 again after being washed by a steam washing device and compressed by a compressor; the old brine subjected to salt leaching by the salt leaching device enters a settler, clear liquid of the settler is preheated and heated and then enters a nitrate tank 310 for salting-out and nitrate precipitation, salt and nitrate mud at the bottom of the settler are also pumped into the nitrate tank 310, nit