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 |