Method for separating and recovering silica, aluminum and iron from fly ash, mineral ores and mine tailings

A method comprising reacting mineral ores that include aluminum, iron and silica with sufficient fluosilicic acid and hydrogen fluoride to form fluorides and silico fluorides of iron, aluminum and silicon;

• distilling said mixture to form vaporous, aqueous silicon fluoride, and separating said aqueous, vaporous silicon fluoride from the fluorides and fluosilicates of iron and aluminum, hydrolyzing the silicon fluorides to form highly pure silicon dioxide and hydrogen fluoride, and recovering silicon dioxide substantially free of aluminum, iron and other impurities;
• recovering and recycling the hydrogen fluoride for reuse in said method;
• and separating the fluorides and fluosilicates of aluminum and iron from one another.

A method comprising reacting mine tailings that includes aluminum, iron and silica with sufficient fluosilicic acid and hydrogen fluoride to form fluorides and silico fluorides of iron, aluminum and silicon distilling said mixture to form vaporous, aqueous silicon fluoride, and separating said aqueous, vaporous silicon fluoride from the fluorides and fluosilicates of iron and aluminum;

• hydrolyzing the silicon fluorides to form highly pure silicon dioxide and hydrogen fluoride, and recovering silicon dioxide substantially free of aluminum, iron and other impurities;
• recovering and recycling the hydrogen fluoride for reuse in said method;
• and separating the fluorides and fluosilicates of aluminum and iron from one another.

A method comprising reacting solids selected from the group consisting of fly ash, mineral ores and mine tailings, said solids comprising aluminum, iron and silicon with sufficient fluosilicic acid and hydrogen fluoride to form fluoride and silico fluorides of iron, aluminum and silicon;

• distilling said mixture to form vaporous, aqueous silicon fluoride, and separating said aqueous, vaporous silicon fluoride from the fluorides and fluosilicates of iron and aluminum;
• hydrolyzing the silicon fluorides to form highly pure silicon dioxide and hydrogen fluoride, and recovering highly pure silicon dioxide substantially free of aluminum, iron and other impurities.