Patent ID: 7037476
Filing Date: 2006-05-02
Classification: C01B

Abstract:
1. A process for preparing amorphous silica from Kimberlite tailings, the process comprising: (i) treating Kimberlite tailings with a mineral acid and washing acid treated tailings; (ii) reacting the acid treated and washed Kimberlite tailings with caustic soda solution to obtain a reaction mass; (iii) filtering reaction mass obtained in step (ii) to obtain sodium silicate solution as filtrate; (iv) diluting the sodium silicate solution obtained in step (iii); (v) diluting mineral acid to a concentration range of 2 to 15 N for use as an acidifying agent; (vi) adjusting Na (vii) heating the diluted sodium silicate solution; (viii) adding the diluted acid of step (v) to the heated sodium silicate solution of step (vii) to partially neutralize alkali in the silicate solution; (ix) intermittently aging the partially neutralized silicate solution obtained in step (vii) for a time ranging from 5 to 20 minutes under stirring; (x) adding the remaining acid to complete neutralization of alkali present in sodium silicate solution; (xi) bringing final pH of solution to range of 2 to 6 to completely precipitate silica; (xii) filtering the solution to obtain a cake and washing the obtained cake until it is free from sulfate ions, drying and pulverizing dried cake to obtain fine silica powder.