| 摘要 |
PCT No. PCT/NO94/00145 Sec. 371 Date Mar. 4, 1996 Sec. 102(e) Date Mar. 4, 1996 PCT Filed Sep. 1, 1994 PCT Pub. No. WO95/07235 PCT Pub. Date Mar. 16, 1995In a method for manufacturing silica a leaching of natural silicates is performed with hydrochloric acid or other mineral acids, draining, drying and possibly a grinding up of the residue of the product obtained. In order to obtain a spherical silica with a controlled particle size and surface characteristics a mineral olivine with the highest possible degree of purity is employed as the basic material. This raw material is reduced to a grain size between 0.05 and 5 mm. The particles are pretreated and washed for the removal of dust on the grain surfaces and heavy materials such as spinel and at least a part of the foliar and stem-like minerals such as serpentine, talc and pyroxene are removed. The olivine particles are then leached in a controlled leaching process where the acid concentration, leaching temperature and leaching time are controlled in order to achieve the desired primary particle size, specific surface and pore volume measured according to the BET method on the extracted silica. The particle agglomerate of spherical particles thus formed with a grain size between 30 and 70 nanometers are washed and dried in the conventional manner, whereupon the agglomerate is divided into the spherical particles.
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