Study on crystal transformation process of magnesium carbonate hydrate based on salt lake magnesium resource utilization

摘要

The crystal transformation process of magnesium carbonate hydrate by the reaction of magnesium sulfate (MgSO4) with ammonium carbonate [(NBu)2 CO3] was investigated. MgSO4 is one of the main magnesium resources of the Lop Nur salt lake in the Xinjiang Autonomous Region of China. Magnesium carbonate hydrates with different chemical compositions were prepared. The transformation process of the 2 crystals, MgSO4 and (NH 4)2 CO 3 , was analyzed by Raman spectroscopy, and the associated changes in crystal morphology were observed by scanning electron microscopy. The needle-like MgCO3· 3H2O transformed into sheet-like 4MgCO3· Mg(OH)2· 4H2O when the temperature was increased from 323 K to 333 K. The changes in the relative contents of these 2 crystals during the transformation process were analyzed by thermoanalysis. The crystal transformation process is discussed from the viewpoint of the crystal plane and growth unit changes.