Extraction method of rare earth elements in magnesium salt rare earth enrichment and acid soluble slag

The invention discloses a method for extracting rare earth elements in magnesium salt rare earth enrichment and acid soluble slag. Rare earth elements in magnesium salt rare earth enrichment and acid dissolution slag are extracted or recycled through the procedures of sulfuric acid dissolution, magnesium salt rare earth enrichment callback, acid dissolution slag callback and magnesium oxide neutralization and impurity removal. The content of rare earth in the magnesium salt rare earth enrichment and the acid soluble slag obtained through treatment according to the recycling method is smaller than 0.5%, the concentration of the rare earth in the sulfuric acid rare earth feed liquid is not lower than 20 g/L, Al2O3/REO is smaller than 1%, the content of Si is lower than 20 mg/L, the content of Fe is lower than 2 mg/L, and the comprehensive yield of rare earth elements is 90% or above. The recovery treatment method provided by the invention is simple and easy to operate, and is suitable for industrial popularizat