Investigation of evaporating crystallization using a seed magma with an image analysis system – First experiences under technical conditions

Arend, Wittenberg; Rudolf, Schick; Werner, Mauch; Lutz-Günther, Fleischer

In this paper, investigations were conducted on seed magma crystallization, which is to proceed on an industrial scale, employing an image analysis system. At the forefront of the study was the production of both seed magma-1 and C-product seed magma-2 based on the seed materials slurry and sugar dust. The sugar drier waste air filter dust was employed for the process of cooling crystallization (seed magma-1), its crystal size spectrum being narrowed down using a classifier. During the C-product crystallization, unclassified sugar dust was used during a long-term test. The absolute crystal number, as well as the proportion of conglomerates, remained constant throughout the process of cooling crystallization being not at all dependent on the seed material. Altogether the proportion of conglomerates was far higher in the slurry. As causes for this occurrence, the smaller initial crystal size and the supersaturation maximum, which may be derived from the first section of the crystallization, must be mentioned. The development of the mean crystal size of the mass distribution comes very close to the prescribed ideal according to d3 rule. The uniformity coefficient n, as a criterion for the breadth of the spectrum of the crystal size, decreases gradually if slurry is utilized. On the other hand, it increases slightly if sugar dust is the basis. The high viscosity of C-product magma complicates the sample-preparation considerably and influences the statement of the measurement provided by the image analysis system. The use of sugar dust as an alternative to slurry also led to a reduction in the proportion of conglomerates during C-product crystallization. Within the framework of a long-term test, the improvement of the C-seed quality, which has been achieved by way of the image analysis system, could be confirmed by a color improvement in the melt liquor of about 250 IU.

Year: 2001
Volume: 126
No.: 1
Page: 42-50

Language: de

pdf download: 2001-42-50.pdf