Method for preparing rare-earth-waste-residue coagulant

technical field [0001] The invention relates to a preparation method and specific steps of an alkaline rare earth waste slag coagulant for water treatment. Background technique [0002] In recent years, there have been more and more studies on the application of rare earths in the field of water treatment. For example, ZL 2009 1 0142775.1 and ZL 2011 1 0020432.5 disclosed that rare earth concentrates were mixed with hydrochloric acid and sodium hydroxide in corresponding proportions to prepare water treatment products. Rare earth coagulant. Because the reaction amount of rare earth in its preparation is very small, although the residue after the reaction can be reused, it will be affected. Therefore, although they have good coagulation effect, their application is limited due to the high production cost. During the Baotou wet-type acid rare earth extraction process, in order to eliminate the influence of sulfate ions on subsequent rare earth extractants, it is necessary to...