| 摘要 |
1. Method of obtaining high-grade silicas from waste amorphous silicas, characterized in that waste amorphous silicas are defluorinated by washing several times with water, preferably warm, and finally with a soda solution with a concentration of 0.5 to 5.0% by weight, preferably 1%, and then it is solubilized in sodium or potassium lye at a temperature of approximately 150 degrees C at a pressure of at least 0.3 MPa, and subjected to final defluorination using chloride or phosphate of calcium or magnesium.
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