First, the degreasing of the pig hair in the container, first put about 1/2 volume of water, then add 1/10 volume of 30% NaOH solution, add and stir while controlling the PH value of 8.5-9. Then, a certain amount of pig hair is added to make it submerged, and the mixture is continuously stirred for 1-2 hours. The sewage is filtered off, washed repeatedly with tap water several times until the washing liquid is neutral, and placed and set aside. Second, the hydrolysis of pig hair Weigh a certain amount of skim pig hair in the reactor, in accordance with the weight ratio of pig's hair and concentrated hydrochloric acid 1:2, add about 30% of industrial hydrochloric acid, start the stirrer, heat reflux, control the temperature At 114-118°C, the reflux time was controlled at 10-12 hours. When reflux reached 9 hours, sampling was started from the reactor until the hydrolysis was complete. After the determination of complete hydrolysis, the reflux was stopped. When the temperature dropped to 905°C, nitrogen gas was introduced into the reactor to remove excess HCI gas from the hydrolyzate and rush out for 0.5-1 hour to drive out the deionized water for HCI gas. absorb. Cooling, cooling, when the temperature dropped to about 80 °C, hot filter, remove black rot, filter residue washed with 2-3 times 10% hydrochloric acid, and the washing solution and the filtrate. If the viscosity of the filtrate is large, it may be diluted with an appropriate amount of distilled water. 3. In a single pass, slowly and uniformly pass liquid ammonia into the filtrate, and turn on the stirrer at the same time. The time is controlled within 8-10 hours. When the pH of the system is close to 2, the stirring speed is appropriately slowed, and the rate of liquid ammonia is also slowed down until the PH value reaches about 4.8. Stirring was continued for 30 minutes. If the pH value was not changed, it was stirred for another 30 minutes, then allowed to stand for 10 to 12 hours, and suction-filtered. The filtrate was crude (I). The filtrate is decolored and concentrated by evaporation to obtain a mixture of other amino acids and salts, which is a very good feed additive. If a small amount of inorganic salt or rare earth mineral or mixed rare earth compound is added to the filtrate, a rare-earth complex of amino acids can be prepared after being subjected to a certain process treatment, which can be used as fungicides and plant growth regulators. Throughout the neutralization process, the pH of the solution is constantly measured, and the stirring and ammonia exchange rates are adjusted at any time. IV. Decolorization Add one batch of cystine crude product (I) obtained in the neutralization to the reactor and add 6-10% dilute hydrochloric acid to the container at 3-4 times the weight of the crude product (I) to raise the temperature and control the temperature. After stirring for 1-2 hours at 80-85°C to dissolve them completely, add the activated carbon for secondary decolorization before the batch, stir for 15-30 minutes, and then add crude product (I) 8-10% by weight of activated carbon for sugar After fully stirring and decoloring for 2 hours, cool down to 60°C and filter and recover the activated carbon. The recovered activated carbon was washed 2-3 times with a certain amount of 6% diluted hydrochloric acid, and the washing solution was combined with the above filtrate. If the color of the filtrate is too deep, the filtrate must be returned to the vessel and a certain amount of activated carbon must be added, and the temperature should be increased to 80-85°C for decolorization. Fifth, the second neutralization will be a bleached filtrate, placed in a container, start the stirrer, control the temperature at 58-60 °C, slowly and evenly into the 12-14% ammonia, in order to neutralize the solution of HC1, When the pH is close to 3, the rate of addition of ammonia and stirring is slowed down. The endpoint pH is controlled between 4.5 and 4.8. The whole process is controlled for 6-8 hours. After reaching the end point, the stirrer was turned on for half an hour, allowed to stand for 6 hours, and then filtered to obtain crude cystine (II). Second, the second decolorization The crude cystine (II) was weighed and placed in a container, 3-4 times its weight was added 6% dilute hydrochloric acid, stirring to fully dissolve, so that the PH value of the solution is less than 0.5. Then add 5% medical grade charcoal powder (or sugar activated charcoal), raise the temperature to 70°C, add 2% EDTA to remove iron, stir for 1 hour, until the solution becomes colorless and transparent, and then leave it still, filter, and use the filter residue. Diluted hydrochloric acid was washed 2-3 times and the washing solution was incorporated into the filtrate. 7. Refining The second decolorizing filtrate is placed in a container. The liquid ammonia is made up with 8-10% dilute ammonia water with non-ionized water. The diluted ammonia water is slowly and uniformly introduced into the container to neutralize the mixture, and the temperature is strictly controlled. At 60-65°C, when the pH value reached 1.5 or so, when more fine crystals were observed to be precipitated, ammonia water was stopped and stirred for 0.5-1 hour to fully crystallize. Ammonia was then slowly passed through, and the pH was controlled at 3.5-4.0. The neutralization time was about 5 hours. After reaching the end point, stop adding dilute ammonia and stop stirring. Allow to stand for 5-6 hours, cool and crystallize, then remove the supernatant water, add deionized water at 65°C, turn on the stirrer for half an hour, filter while still hot, and repeatedly rinse with deionized water during the filtration process until the test is completed. No chlorine ions. VIII. Drying and Packing Place the obtained cystine into fine plates, each layer is about 5cm thick, put into a constant temperature oven, keep the temperature at 602°C, bake it to constant weight, and then crush it and sieve it. , Packaging and storage, that is, products. (Li Zhonghe excerpts)
