hrvatski

Seed properties effect on granulometric characteristics of borax in batch cooling crystallization

In this work influence of seed surface area and shape factor on granulometric properties of disodium tetraborate decahydrate (borax) obtained by batch cooling crystallization were investigated. In the crystallizer with the volume of 2.14 dm3, mixing was performed by straight blade turbine impeller (abbrev. SBT). In all experiments impeller speed was kept constant (N = 350 rpm) in order to ensure the state of complete suspension in the system. Mother liquor, saturated at temperature of 30 °C, was cooling down at rate of 6 °C h-1. In the first part of the work, unseeded batch cooling crystallization was carried out in order to determine metastable zone width, granulometric properties of crystal product and to define conditions under which seeded crystallization will be performed. Afterwards, the influence of seed surface area and shape factor on the crystal size distribution and agglomeration ratio of final product was investigated. Crystals of borax with needle and plate like morphology, in size range from 45 to 142 m, were used as seed. In order to examine the effect of seed surface area, different masses of crystals of defined size and shape factor were added to the mother liquor. Analysis of crystal size distribution and agglomeration ratio of final crystal product obtained for each examined seed surface area was carried out. Obtained data were compared in details. Seed that results in borax crystal product with a narrower crystal size distribution, larger weight mean diameter and lower agglomeration ratio, could be considered as optimal option.

Disodium tetraborate decahydrate ; seeded crystallization ; seed surface ; crystal size distribution

nije evidentirano