首页> 外文会议>14th international symposium on industrial crystallization : Abstracts of papers >INFLUENCE OF CRYSTALLIZATION CONDITIONS ON THE CRYSTAL GROWTH MECHANISM AND CRYSTAL GROWTH RATE OF YTTRIUM OXALATE
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INFLUENCE OF CRYSTALLIZATION CONDITIONS ON THE CRYSTAL GROWTH MECHANISM AND CRYSTAL GROWTH RATE OF YTTRIUM OXALATE

机译:结晶条件对草酸钇晶体生长机理及晶体生长速率的影响

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In the seed crystallization of yttrium oxalate in metastable supersaturation thernmodification of the growth mechanism by crystallization coditions of agitationrnspeed and additive was observed. From the desupersaturation curve the crystalrngrowth rate was expressed with a power law of supersaturation (RT=K_g△C~p).rnWithout on additive the growth rate coefficient, Kg, increased with increasing thernagitation speed but the growth rate order, p, was slightly dependent on the agitationrnspeed. When an additive of sodium tripolyphosphate was used, therndesupersaturation in the solution was much retarded due to inhibition of the crystalrngrowth and the growth rate order was varied up to about 2.6 with increasing thernadditive concentration.rnBy using a two-step growth model for discription of the crystal growth mechanism itrnwas obtained that the surface integraiton rate was proportional to a square ofrnsupersaturation and the mass transfer coefficient increased with increasing thernagitation and the surface integration coefficient was independent of the agitationrnspeed. However, as the additive concentration in the solution increased, the surfacernintegration coefficient was reduced but the mass transfer coefficient was almostrninvariant. The shift of the rate-determining step by the additive was examined withrnthe effectiveness factor. The effect of the additive on the surface integration wasrndepicted with Langmuir isotherm.
机译:在亚稳态过饱和中草酸钇的晶种中,观察到通过搅拌速度和添加剂的结晶条件对生长机理的改变。从过饱和曲线可知,结晶生长速率以过饱和幂定律表示(RT = K_g△C〜p)。取决于搅拌速度。当使用三聚磷酸钠的添加剂时,由于抑制了晶体的生长,溶液中的超饱和度被大大抑制,并且随着添加剂浓度的增加,生长速率的阶数变化到大约2.6。rn使用两步生长模型描述晶体生长机理表明,表面积分速率与过饱和度的平方成正比,且传质系数随熔融度的增加而增加,且表面积分系数与搅拌速度无关。但是,随着溶液中添加剂浓度的增加,表面结合系数降低,而传质系数几乎不变。考察了添加剂决定速率的步骤的变化,并采用了有效因子。用Langmuir等温线描述了添加剂对表面整合的影响。

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