Abstract: A more efficient utilization of geothermal energy by allowing flashing of the produced water to a lower temperature. This is accomplished by causing additional quantities of silica to precipitate out of the geothermal water as particles rather than as scale on process equipment. These particles are tertiary aggregate amorphous silica of Type I, II or III, which have high surface areas, good oil absorption and high reflectivity. They are useful as additives and opacifiers for paper, paints, rubbers, and plastics; as thixotropic thickening agents; and as absorbents. The improved energy recovery is accomplished by utilizing the addition (including recycle) of previously produced particles of amorphous tertiary aggregate silica of a selected Type I, II or III, as a heterogeneous precipitation agent, alone or in combination with other more conventional precipitation agents.

Abstract: A method of obtaining precipitated amorphous silicas with substantially a tertiary aggregate structure (whether as an aqueous slurry, as cake, gel or otherwise) useful for coating and/or incorporation in paper and other substrates (e.g. rubber, plastics and the like) from a geothermal fluid (naturally or artificially generated--natural, including water infusion into geothermal systems) having sufficient silicic acid concentration, said method comprising:A. ageing the fluid to effect polymerization, thus establishing a silica sol, ageing meaning a process in which the source fluid after being made supersaturated with respect to amorphous silica is held for a period of time,B. optionally (prior to, with and/or after step A--preferably prior to in order to reduce arsenic adsorption) reducing the temperature of the geothermal fluid and/or sol as the case may be,C. inducing precipitation of amorphous silica from the sol under conditions that will provide the tertiary aggregate structure, andD.