US 9,809,495 B2 · Method for the closed-cell expansion of mineral material

Abstract

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.

Claims33

Dependent claims

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 in an isenthalpic manner, 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 in the drop section after the two successive positions depending on the critical temperature.

1 more element

An apparatus for producing an expanded granulate, the apparatus comprising:

a vertically upright furnace plus furnace shaft, comprising a feed opening at an upper end of the furnace shaft for feeding a sand grain-shaped material and a discharge opening at a bottom end of the furnace shaft, and
a drop section situated between the feed opening and the discharge opening in the furnace shaft, in which the drop section leads through several heating zones which are vertically separated from each other, wherein the several heating zones each comprise one or more heating elements which are controllable independently from each other in order to heat the sand grain-shaped mineral material to a critical temperature at which the sand grain-shaped material is expanded by a propellant in an isenthalpic manner, and comprising at least one of
several temperature sensors for direct or indirect measurement of the temperature of the material and
means for determining a power of the one or more heating elements of the several heating zones,
wherein a control unit is connected to at least one of the several temperature sensors and
the means for determining a power of the one or more heating elements of the several heating zones and to the one or more heating elements of the several heating zones in order to detect a first decrease in the temperature of the sand grain-shaped mineral material, between two successive positions along the drop section, and
the one or more heating elements are controllable depending on the critical temperature by the control unit.

4 more elements

Dependencies are inferred from the claim text.

Method for the closed-cell expansion of mineral material

Life of this patent

Method for the closed-cell expansion of mineral material

Life of this patent

Abstract

Claims33