The method comprises the following steps: adsorbing, washing and desorbing
neomycin fermentation liquor through an adsorption
system, and then concentrating to obtain desorbed concentrated liquor; the preparation method comprises the following steps: washing with low-concentration
ammonia water, then dynamically adsorbing to cationic resin after
dilution, washing with low-concentration
ammonia water, then connecting weak positive resin and anion resin in series, washing with medium-concentration
ammonia water, then desorbing with high-concentration ammonia water, and finally, concentrating, carrying out salt conversion and decoloration, and carrying out
spray drying to obtain the Feramectin
sulfate. According to the method, the conventional thought of primary adsorption and gradient washing of resin is broken through, weak positive and low-particle-size resin is selected for secondary dynamic adsorption and
desorption, the better separation degree is achieved, the production cost is reduced, and the high-purity fralamectin
sulfate is prepared.