Process for producing geothermal power, selective removal of silica and iron from brines, and improved injectivity of treated brines

A method for producing geothermal power using geothermal brines and producing a brine with reduced silica and iron concentrations having improved injectivity, the method comprising:

• providing a geothermal brine comprising silica and iron (II);
• flashing the geothermal brine to generate electrical power, wherein the flashing produces precipitated silica and a flashed brine having a reduced silica concentration;
• separating the precipitated silica from the flashed brine and returning the precipitated silica to the flashing step;
• reducing a temperature of the flashed brine to less than 150° C.;
• oxidizing the flashed brine to oxidize iron (II) to iron (III) to produce an oxidized brine, wherein the oxidized brine comprises less than 20 ppm of silica and less than 20 ppm of iron;
• adding a base to the oxidized brine to react the iron (III) and silica to produce precipitated silica-iron solids;
• separating the precipitated silica-iron solids from the oxidized brine, wherein the oxidized brine comprises less than 20 ppm of silica and less than 20 ppm of iron;
• and
• injecting the oxidized brine underground.