Patent ID: 8383808

Claim:
A method to prepare D-glucosamine hydrochloride, comprising following steps: (1) hydrolysis: pump a hydrochloride with introducing hydrochloric acid having a mass concentration of 30% to 35% into a reactor, heating the hydrochloric acid to 60° C. to 70° C. with steam, introducing a citric acid residue into the reactor to form a first mixture, heating the first mixture to 90° C. to 105° C. with steam, maintaining at 90° C. to 105° C. for 2 to 5.5 hours, wherein citric acid residue:hydrochloric acid (weight ratio)=1:1.6 to 2.5; (2) suction filtering: filtering a material resulting from Step (1) in a suction filtering barrel, and rinsing a filter residue resulting from the suction filtering with running water for 2 to 3 times, and then washing the filter residue with a dilute alkali of 1% to 3% of mass concentration to obtain a neutral or slightly acidic material, and mixing a suction filtering mother solution and washings to obtain a first mother solution; (3) concentrating: distilling the first mother solution to reduce its weight by 80%, moving the post-distillation first mother solution into a cooler for natural cooling to 25° C. to 35° C., and transfer the cooled solution into a centrifugal machine for centrifugal separation to obtain a solid substance, which is crude D-glucosamine hydrochloride.