Zhejiang University

Zhejiang Nhu Company Ltd.

Shandong Nhu Amino Acid Co., Ltd.

Shandong Nhu Amino Acids Co., Ltd.

Cunchao Wang

Zhirong Chen

Yin Yan Li

Cong Chen

Zhixuan Wang

Zhengjiang Wang

Chengfeng Zhang

Tao Long

Zhixiang Zhang

Xinhong Liu

Chuqiu Zhao

Sujuan Wang

The present disclosure relates to a method for continuous preparation of high bulk density methionine crystals. The process of the method is as follows: a hydrolysate solution, which is obtained from a reaction of 5-(&#x3b2;-methylmercaptoethyl) hydantoin and a potassium carbonate solution, is mixed with an external circulation material from a DTB neutralization crystallizer having a gas phase neutralization section; after being cooled, the mixture enters a liquid distributor of a neutralization region in the upper part of the crystallizer and is sprayed in the form of liquid droplet or trickle into carbon dioxide gas for neutralization reaction, and then naturally falls into a crystallization region in the lower part to be mixed with a material in the region; the obtained mixture grows on fine crystals in a system to form crystals having larger particle diameters, and meanwhile new crystal nucleuses are formed; in a deposition area in the middle part of the crystallization region, the crystals having larger particle diameters deposits into an elutriation leg, while the fine crystals circulate with the external circulation material, and a part of the external circulation material is used to elutriate the crystals in the elutriation leg, while another part of the same is used to be mixed with the hydrolysate solution; and the crystals in the elutriation leg are separated, washed and dried to obtain the high bulk density methionine product.

Method for continuous preparation of high bulk density methionine crystal

The present invention discloses a clean method for preparing a D,L-methionine comprising the steps of: preparing a potassium cyanide solution using a crystallized mother solution containing potassium carbonate as an absorbing liquid to absorb hydrocyanic acid, then reacting the potassium cyanide solution with 3-methylthio propionaldehyde and an ammonium bicarbonate solution at 50-150&#xb0; C. for 3-15 minutes so as to obtain a 5-(&#x3b2;-methylthioethyl)glycolyurea solution, then bring the 5-(&#x3b2;-methylthioethyl)glycolyurea solution to a temperature of 140-220&#xb0; C. and subjecting to a saponification reaction for 2-5 minutes, after the completion of the saponification, reducing the temperature to 0-40&#xb0; C., extracting with an organic solvent, neutralizing the water phase with COand crystallizing, then filtering, washing, and drying to obtain an acceptable D,L-methionine product; bring the crystallized D,L-methionine mother solution from filtration to a temperature to 110-160&#xb0; C. to remove CO, which are all then circulated and used as a hydrocyanic acid-absorbing liquid. The process route of the present invention is a route suitable for a continuous and clean production, substantially without producing waste water and waste gas.

Clean method for preparing D,L-methionine

Growing community of inventors

Weifang, China

Cunchao Wang