Preparation method of organic flocculant for efficiently treating sand washing wastewater

The invention relates to a preparation method of an organic flocculant for efficiently treating sand washing wastewater, the organic flocculant is applied to efficient flocculation of sand washing wastewater in the sand making industry, and the compound flocculant is efficiently synthesized from polyacrylamide polymers of different specifications, an amination reagent, an aldehyde reagent and a blending buffer reagent through a low-temperature Mannich reaction. The synthesized organic flocculant has the characteristics of strong adaptability in sandstone wastewater (being capable of treating sandstone wastewater with different finenesses), high settling velocity, few flocculant residues in water, strong salt resistance, low water content of formed sludge and the like, and the surfaces of sandstones washed by the flocculant have few organic residues, so that the flocculant has the advantages of environmental protection and the like. The method can effectively reduce the influence of the polymer on the performa