A CHEMICAL METHOD FOR SEPARATION OF AMORPHOUS SILICA FROM QUARTZ AND SUBSEQUENT DETERMINATION OF THE QUARTZ PHASE

A new method is presented for the chemical separation of amorphous sil ica from free silica (quartz phase) and the subsequent determination o f the latter. The mixture of the two phases of silica was treated with 1.5% HF at a temperature of less-than-or-equal-to 15-degrees-C for 5 min and thereafter the adverse effect of hydrofluoric acid was inhibit ed by adding a saturated solution of boric acid. The insoluble residue of quartz was filtered and determined by following the conventional m ethod of hydrorfluorisation. Knowledge of the quartz content in cerami c raw materials is essential in making refractory blocks for glass tan k furnaces, vitreous tablewares, etc. The merit of the method is judge d by its simplicity and the reproducibility of the results as shown by the standard deviation.