Method for rapidly recycling chrome from chroming waste liquor by alkali precipitation

The invention discloses a method for recovering chrome by the fast alkali precipitation of chrome tannage waste fluid, belonging to the clean production technology and recycling technology in the technical field of leather production. After the collection of chrome tannage waste fluid in the invention, the solid impurities are removed by filtering, with the temperature adjusted, magnesium oxide or other alkali matters are added; and after the full stirring and alkalization, little polyacrylamide or other flocculants are added for fast precipitation to remove supernatant liquor; and chromic hydroxide precipitate is obtained after further removing the water of the underlayer flocculent precipitate with a centrifuger. With the adoption of the method, the concentration of dichromium trioxide in the waste fluid can reduce to below 0.05g/l from 2-4g/l, the removal rate reaches over 97 percent, and the addition of the flocculants can realize the fast precipitation of chromic hydroxide in 20 minutes, the precipitation volume is lower than 15 percent of the total volume, and the precipitate has good hydrophobic nature and can be recovered conveniently. The method provides a new way for the precipitation and recycling of waste chrome liquor in a tanyard.