Impurities removal process for highpurity silica production from diatomite
Shown in Fig. 1 is the flow sheet of the complete purification procedure. At first, an acid leaching stage was used to remove small quantities of impurity minerals prior to silica extraction from diatomite. 10 g of raw diatomite sample were leached in M HNO 3 acid solution at 60 °C for threehours under constant stirring. HNO 3 quantity was added gradually during the threehours of leaching.