|Budget Amount *help
¥5,800,000 (Direct Cost : ¥5,800,000)
Fiscal Year 1991 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1990 : ¥5,000,000 (Direct Cost : ¥5,000,000)
Crystallization phenomena of l-SCMC(s-carboxymethyl-cysteine)in supersaturated solution of dl-SCMC in the presence of sodium chloride was studied from the point of view of industrial purpose. Especially, sticking phonomena of fines on l-SCMC seed crystal and secondary nucleation by it were focused and discussed by suspended seed crystal in a batch crystallizer. In these tests, the marked seed crystal was also suspended and populations of fines found on a crystal surface were also observed, following results were obtained.
1)Population of fines suspended in supersaturated solution were almost constant for initial period of batch operation. On a surface of seed crystal, fines were hardly found, but population of fines stuck on seed increased with increase of growth period of seed crystal. On these conditions, population were different by degree of supersaturation and fines were of l-SCMC. From the observation of seed surface rharked, behavior of stuck fines were modeled, and linear correlation between population rate of suspended fines and sticking rate of fines, observed were explained theoretically. When surface area of seed crystal covered by fines became about fifty percents, plots between amount of stuck fines and growing period, became deviated from theoretical line.
2)Amount of d-SCMC stuck on crystal surface were observed. For initial period that fines of d-SCMC appeared on l-SCMC seed, amount of stuck d-SCMC fines increased with fourth power of operating period. After 1.5 h after d-SCMC was observed on seed surface, d-SCMC was observed in the suspended fines. From this results, heterogeneous nucleation model of d-SCMC was proposed.
Fines are generally considered to be suspended in a supersaturated solution in an industrial crystallizer and affect on growth rate and quality of product crystal. When optimum design for produce of desired crystal in a crystallizer is studied, sticking phenomena of fines on growing crystal is considered important.