Patent ID: 11958749
Assignee: GEO40 LIMITED
Field: Chemical engineering (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 14:
15. A method of producing a colloidal silica concentrate from a geothermal fluid comprising silica, the geothermal fluid having a silica concentration of at least 300 ppm and an initial temperature of at least 85° C., the method comprising:
a. cooling the geothermal fluid from the initial temperature to a nucleation temperature to cause the silica saturation point to be reached and exceeded such that the silica saturation index achieved is at least 1.5 to initiate growth of silica colloid particles;
b. curing the geothermal fluid after cooling, for a period which is sufficient to decrease the concentration of monomeric silica in the geothermal fluid to near the saturation point, to produce an ultrafiltration (UF) feed;
c. treating the UF feed using ultrafiltration to yield a UF retentate;
d. diafiltering the UF retentate during or after ultrafiltration to produce a colloidal silica concentrate;
wherein the UF retentate comprises a silica concentration of between about 1 mass % and about 15 mass %, and wherein the UF retentate is treated using heat curing to increase the mean silica colloid size.