| 摘要 |
<p>Refractory mortar, mortar comprising calcined fire clay, calcined bauxite, chrome ore or magnesite, or a mixture of these, and a suitable binder, may be used for these bricks which comprise partial rings (12-19) between the electrode ports (22,23,24) at the centre of the roof. These partial rings are surrounded by complete adjacent rings (1-11) produced from metal-encased bricks. The majority of these are situated under a contour-controlling hold-down structure and can expand upon heatup of the roof. The latter is particularly advantageous with electric furnaces and is skirted by a band containing the concentric rings of bricks.</p> |
