Method for stepwise extraction of silica and hydroxide from silicate substances

A method for stepwise extraction of silica and hydroxide from silicate substances, the method comprising:

• putting a raw material of silicon-containing inorganic solid waste or silicon-containing natural sand powder into a reactor, and adding mixed acid as a leaching solution composed of chlorine containing inorganic acid X, inorganic acid Y, inorganic acid Z, water-soluble alcohol and water, said leaching solution is heated and reacted under the condition of greater than or equal to 0.1 MPa, after the reaction, filtered to obtain an acidic multi-ion mixed solution and filter residue;
• heating and boiling the acidic multi-ion mixed solution and collecting with a collector silicon-containing volatile components, the silicon-containing volatile components are decomposed and deposited in the collector, and the remaining acidic multi-ion mixed solution is cooled for standby use;
• drying amorphous silica dioxide decomposed and deposited in the collector to obtain high purity silica powder;
• washing and drying the filter residue to obtain silica;
• extracting the remaining acidic multi-ion mixed solution by electrochemical deposition method to obtain hydroxide.