Membrane Method of Colloidal Silica Extraction from Hydrothermal Heat Carrier

Abstract

Experiments on colloidal silica extraction from hydrothermal solution by using membrane filters were carried out. Millipore’s membrane filters with pore diameters of 0.1-0.45 ?m and ceramic filters with pores diameters of 0.2 ?m were used. Cations of Al3+ were added to the solution before filtration through the filters. Cations were added for the formation of aggregates of colloidal particles. The temperature of solution in the laboratory experiments was about 20 0C. The ceramic membrane filter was tested in a pilot plant at Verhne-Mutnovsky GeoPP. The temperature of hot solution in that test was about 80 0C. A high degree of colloidal silica extraction 75-90 % in filtrate was achieved in our experiments. Silica consentration SiO2 of more than 5 g/l was obtained in the water recycled through the filters. Such silica hydrosol can be utililized in the chemical industry, for example, for production of zeolites, catalysts, polysilicates.