摘要 |
A process of making ceramic spheroids by firing clay spheroids comprising by weight percent: FeO (3.22-5.21), Fe3O4 (3.40-5.11), SiO2 (52.49-59.42), CaO (1.99-7.96), MgO (2.81-4.69), Al2O3 (12.05-17.65), TlO2 (0.58-0.71), MnO (0.07-0.19), Na2O (0.47-0.86), K2O (1.70-2.37), P2O3 (0.13-0.19), S (0.03-0.29), CO2 (0.90-8.23), Organic C (0.22-1.04), H2O+ (4.14-7.28), H2O- (2.12-5.48) in contact with a particulate parting agent selected from aluminum oxide, magnesium oxide, and their precursors at a sufficiently high temperature and for a sufficiently long time to form a shell. Preferably, the clay spheroids are obtained from a deposit located at Hallock in Kittson County Minn., U.S.A. |