2. Materials and methods
2.1. Materials used
In all the coating experiments seeded anhydrous sodium sulphate cores sieved into a fraction with diameters between 200 and 300 mm were coated with aqueous solutions of crushed sodium sulphate using Dextrin (bulk density ~ 0.8 g/cm3) as binder. The moisture contents of the sodium sulphate cores were determined to be less than 0.4 w/w% (inclusive crystal water) and the average porosity of the cores was determined to 20.7% using mercury intrusion/extrusion porosimetry. From this analysis it was further seen that the pore size distribution was narrow and unimodal having an average pore diameter of 1.29 mm. SEM analysis of the Na2SO4 cores showed rather smooth core surfaces with few but large pores. A typical SEM picture of an uncoated Na2SO4 core can be seen in Fig. 1.