Abstract:

【Objective】Organic acid, which it’s acidity is between the carbonic acid and citric acid, reacted on eggshell calcium, and the calcium organic acids were produced. Then let it react on citric acid and the calcium citrate can be replaced.【Method】 Organic acid was screened in the experiment, then the acetic acid was chosen as an organic acid. The influencing factors during the process of experiment were studied, then the first-rank conditions for techniques were gained. The experiment adopted a design of ternary operator--regression, median and circumgyrating--in quadratic to optimize the techniques, and then purification of products was made. 【Result】 After optimization, the first-rank techniques possessed 5 characters: eggshell mix was 30% more than the normal, the ratio between solid and liquid was 1:19.8. the powder of eggshell reacted on acetic acid under 25.4℃ and lasted for 3.5 hours, citric acid reacted on acetic calcium under 50℃ and lasted for 3 hours, citric acid mix was 25.4% less than the normal. 【Conclusion】 Under the first-rank techniques condition after optimization, the experiment on making use of eggshell to manufacture calcium citrate has a yield of 86.2% and after purification, the yield reaches 85.4% and the purity reaches 99% or more.

Key words: poultry egg, eggshell, calcium citrate, comprehensive utilization