Method for extracting rare earth from magnesium salt rare earth enrichment and acid-soluble slag

The invention provides a method for extracting rare earth from magnesium salt rare earth enrichment and acid soluble slag, and relates to the technical field of rare earth hydrometallurgy. The method comprises the following steps: adding water into magnesium salt rare earth enrichment and/or acid soluble slag for size mixing, adding acid into the obtained slurry for optimal dissolution until the pH value is 2.8-3.5, and carrying out solid-liquid separation on the obtained material liquid to obtain filtrate and first filter slag; adding magnesium salt rare earth enrichment into the filtrate to adjust the pH value to 4.2-4.8, and carrying out solid-liquid separation to obtain second filter residues and sulfuric acid rare earth feed liquid; washing the first filter residues with water to obtain qualified waste residues. In order to solve the problems of low rare earth recovery rate, large slag quantity and high rare earth residual quantity in slag in rare earth extraction of magnesium salt rare earth enrichment