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

In this paper, investigations were conducted on seed magma crystallization, which is to proceed on an industrial scale, employing an image analysis sy stem. 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 du st. The sugar drier waste air filter dust was employed for the process of c ooling crystallization (seed magma-1), its crystal size spectrum being narr owed down using a classifier. During the C-product crystallization, unclass ified sugar dust was used during a long-term test. The absolute crystal num ber, as well as the proportion of conglomerates, remained constant througho ut the process of cooling crystallization being not at all dependent on the seed material. Altogether the proportion of conglomerates was far higher i n the slurry. As causes for this occurrence, the smaller initial crystal si ze and the supersaturation maximum, which may be derived from the first sec tion of the crystallization. must be mentioned. The development of the mean crystal size of the mass distribution comes very close to the prescribed i deal according to d(3)-rule. The uniformity coefficient n, as a criterion f or the breadth of the spectrum of the crystal size, decreases gradually if slum, is utilized. On the other hand, it increases slightly if sugar dust i s the basis. The high viscosity of C-product magma complicates the sample-p reparation considerably and influences the statement of the measurement pro vided 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 durin g 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 im age analysis system, could be confirmed by a color improvement in the melt liquor of about 250 IU.