METHOD FOR THE CLOSED-CELL EXPANSION OF MINERAL MATERIAL

摘要

The invention relates to a method for producing an expanded granulate from sand grain-shaped mineral material (1) with a propellant, wherein the material (1) is fed into a vertically upright furnace (2) from above and said material (1) falls along a drop section (4) through multiple heating zones (5) in a furnace shaft (3) of the furnace (2), wherein each heating zone (5) is heatable using 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 (15) plasticize and the sand grains (15) are expanded by the propellant. In order to enable setting a closed surface of the expanded granulate in a purposeful fashion, it is provided in accordance with the invention that upon detection of a first reduction in the temperature of the material (1) between two successive positions (9) along the drop section (4) the heating elements (6) are controlled along the remaining drop section (4) depending on the critical temperature.

主权项

1. A method for producing an expanded granulate from a sand grain-shaped mineral material comprising a propellant, the method comprising:
feeding the sand grain-shaped mineral material into a vertically upright furnace from above such that said sand grain-shaped mineral material falls along a drop section through multiple heating zones separated vertically from each other in a furnace shaft of the vertically upright furnace, wherein each of the multiple heating zones is outfitted with at least one independently controllable heating element; heating the sand grain-shaped mineral material to a critical temperature at which surfaces of sand grains plasticize and the sand grains are expanded by the propellant, thereby forming an expanded sand grain-shaped mineral material; and discharging the expanded sand grain-shaped mineral material at a bottom end of the vertically upright furnace, wherein upon detection of a first reduction in a temperature of the sand grain-shaped mineral material between two successive positions along the drop section, the at least one independently controllable heating element is controlled along a remaining drop section depending on the critical temperature.