Experiments on Silica Concentration in Hydrothermal Solutions by Ultrafiltration

Abstract

The experiments on silica concentration in hydrothermal solutions by ultrafiltration were carried out. Membrane filters of different sizes were tested. Ultrafiltration membranes made of polyacrilonitril and polyethersulfone were used in our experiments. Temperature of solution was varied from 20 to 72 0C. Hydrothermal solutions with different chemical compositions were tested, pH was varied from 5.0 to 9.2. Mass rate of filtrate through membrane filter was from 40 to 3000 liters per hour. Selectivity of membrane layers with respect to colloidal silica particles and molecules of orthosilicic acid was determined in the experiments. Concentrated silica sols with SiO2 content from 4 up to 150 g/liter were obtained in our experiments by ultrafiltration. Charateristics of sols produced by membrane concentration were investigated: density, viscosity, sizes of silica particles, stability. Silica sols can be utililized in the chemical industry for production materials.