苦汁・かん水処理に関する研究主として結晶成長について
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概要
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In manufacturing process with chemical reaction in aqueous solution, it is mostly important that products are pure and easily seperated from the mother liquor. To meet such requirments of the process, treating conditions have to be determined by considering the conditions of crystal growth of products. In this study, conditions of recovering the constituents of bittern or brine as gypsum or magnesinm hydroxide have been determined from the standpoint of crystallisation, namely, concerning the theories of crystallistion in aqueous solution proposed up to now, analysing the change of supersaturation in a crystallizer, and delivering the relation between the rate of crystal growth and the treating capacity of a crystallizer (or a reactor) as follows. In Chap. 1, an outline of the theories of crystallisation in aqueous solution were stated. Namely, there were the theories of crystal growth, from Miers theorem, through the diffusion theory, to Kossel, Stranskie and Brand theory, (among which the diffusion theory has been considered proper to determine the treating capacity of a crystallizer), and the recent theory of nucleation proposed by Volmer, Stranskie and Frenkel. From these, it was shown that the rates of crystal growth and of nucleation were expressed as a function of supersaturation and therefore it was necessary in order to obtaine the crystalline products to control the supersaturation concentration of the solution. In Chap. 2, the crystallizer was classified by the way of maintaining supersaturation of solution, and the change of the supersaturation concentration with the conditions of operating the crystallizer were analysed, namely the relationhships between the conditions of operation and the rate of crystal growth were determined. Then the conditions of crystallisation with chemical reaction were considered in the same way, and the relationships between the treating capacity and the rate of crystal growth of products was discussed on the case of batch or continious seeding process and of spontaneous nucleation. For treating the products, of which it was difficult to measure the rate coefficient of crystal growth, the capacity of a crystallizer was considerd from the linear crystal growth, which was determined from the change of distribution of the crystal size. In Chap 3, and 4, the treating conditions of bittern and brine to recover sulfate- and Mg++-ion as gypsum and magnesium hydroxide were determined by considering the conditions of crystallisation described in previous chapters. On recovering the gypsum there were determined the solubilities, the stable regions (or the transition points) and the rate coefficients of crystal growth, of modifications di-,hemihydrate) of calcium sulfate in magnesium chloride or sodium chloride solution. Then the conditions of continuous operation and the relationship between a treating capacity and a crystal form of gypsum produced were determined. On recovering magnesium hydroxide, for which measurement of the rate coefficient of crystal growth was difficult on account of the poor solubility, the continious operation was carried out in order to measure the linear velocity of crystal growth, from which the treating capacity was estimated.
- 山形大学の論文
- 1960-03-30