SURFACE MORPHOLOGY AND MICROSTRUCTURAL CHARACTERIZATION OF KCl CRYSTALS GROWN IN HALITE–SYLVITE BRINE SOLUTIONS BY ELECTRON BACKSCATTERED DIFFRACTION TECHNIQUES

In this paper, a study on the ternary NaCl–KCl–H2O system was carried out by an extractive metallurgy technique from mixed brine solutions of different compositions at room temperature (23°C). The surface morphology and microstructure were examined using a scanning electron microscope (SEM), electron backscattered diffraction (EBSD) and an energy dispersive X-ray (EDX) spectroscopy. The presence of ${\rm Na}_{ <{\rm aq}>}^{+}$ was found to reduce the stability of the solutions and increase the crystallization induction period, interfacial energy, energy of formation of the nucleus and greatly reduce the nucleation rate of KCl crystal. The surface morphology of KCl crystals is significantly changed due to presence of 5 to 10% (w/w) of NaCl as impurities in the binary solutions and shows the formation of co-crystals of different crystallographic orientation of NaCl on the KCl surface. In addition X-ray diffraction studies performed on KCl crystals grown in halite–sylvite binary solutions reveals that these crystals are cubic in nature and its lattice constant is 6.2952 Å when the NaCl concentration is small.