| 266 / | HD | METALLURGICAL APPARATUS |
| 168 | DF | MEANS FOR TREATING ORES OR FOR EXTRACTING METALS {3} |
| 171 | DF | .~ By means applying heat to work, e.g., furnace {10} |
| 176 | ![]() | .~.~ With means for moving solid material to or through heating zone {4} |
| 177 | DF | .~.~.~> By means for moving charge through zone {2} |
| 182 | DF | .~.~.~> By fluid current |
| 183 | DF | .~.~.~> By power-driven means conveying solid charge into zone |
| 184 | DF | .~.~.~> Bell and hopper type |