Method of production of a silica concentrate
AssigneeGeo40 Limited
InventorsAndrew W. Mitchelmore, Michael T. O'Sullivan, John Lea
Life of this patent
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Abstract
The invention relates to methods of production of a silica concentrate from geothermal fluids. More particularly, although not exclusively, the invention relates to the production of a colloidal silica concentrate, colloidal silica or precipitated silica from high temperature geothermal fluids by ultrafiltration to produce size-specific silica colloids and step-wise concentration of silica to avoid precipitation or gelling.
Claims16
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 for silica colloids of a desired pa size to form from monomeric silica present in the geothermal fluid, to produce an ultrafiltration (UF) feed,
- wherein the silica colloids of the desired particle size have a mean silica colloid particle size of between about 3 nm and about 8 nm;
- c. treating the UF feed using ultrafiltration to yield a UF retentate;
- and
- 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 particle size.
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.
Dependencies are inferred from the claim text.