| 摘要 |
The invention relates to a method for producing an expanded granulate made of a sand grain-shaped mineral material (1) using a propellant, wherein the material (1) is fed to a substantially upright furnace (2); the material (1) is transported along a transport path (4) through multiple vertically separated heating zones (5) in a furnace shaft (3) of the furnace (2), each heating zone (5) being heatable by at least one independently controllable heating element (6); and the material (1) is heated to a critical temperature at which the surfaces (7) of the sand grains (1) plasticize, and the sand grains (1) are expanded on the basis of the propellant. According to the invention, the material (1) is fed from the bottom together with an air quantity; the material (1) is transported from the bottom to the top along the transport path (4) by means of the air quantity which flows from the bottom to the top in the furnace shaft (3) and forms an airflow (14); and the sand grains (1) are expanded in the upper half of the transport path (4). |
