Industrial process of preparing magnesia of high purity
US3980753A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 29, 1974 |
| Grant date | Sep 14, 1976 |
| Priority date | — |
| Expiry date | Nov 29, 1994 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC01P2006/80
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Magnesia of very high purity is produced industrially from a magnesite waste material wherein impurities are present in such amounts that the weight ratio of the precipitable hydroxide ions, calculated as the sum of Fe.sub.2 O.sub.3 + Al.sub.2 O.sub.3 + Cr.sub.2 O.sub.3 + Mn.sub.3 O.sub.4 to the sum of SiO.sub.2 + TiO.sub.2 + B.sub.2 O.sub.3, is at least 1 : 3. The starting material is dissolved in hydrochloric acid of 15-32% concentration, the impurities are precipitated by adjusting the pH of the acidic solution to 4 - 9, and the purified magnesium chloride solution is thermally decomposed into magnesia and hydrochloric acid gas, the latter being recycled to form the hydrochloric acid of the stated concentration for dissolving the starting material.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.