Abstract: Tunnel furnace for foaming glass material, comprising heating elements chosen among electrical and gas based heating elements. The tunnel furnace comprises at least the following temperature zones: a preheating zone (8) suitable for heating the feed material to a temperature in the range 400-900° C. and a foaming zone (9) suitable for heating the glass material to a temperature above 900° C. The furnace also typically comprises a cooling zone (10) suitable for reducing the temperature from the elevated temperature in the foaming zone. According to the present invention the preheating zone (8) is at least 15% longer than the foaming zone (9).

Abstract: Thermally insulating recycle glass material functioning as a capillary water suction barrier and method for its manufacture. The glass raw material (2, 3) contains impurities from the group comprising ceramics, porcelain, stone, plastic, and paper, in the presence of an activator to facilitate foaming of the glass. The method comprises at least two steps, namely a preheating step (8) in which the raw material is heated to a temperature in the range 500-700 ° C. to reduce the amount of detrimental contaminations and a foaming step (9) in which the material is heated to a temperature in the range 900-980 ° C. in which the glass is foamed and forms a structure of closed pores. Impurities/ contaminations can be present in an amount of up to 10% by weight of the glass. Preferably the method comprises a tempering step (7) prior to the preheating step (8).

Abstract: Method for neutralizing waste, such as powder from luminescent tubes and similarly, residue from incineration of household waste, optionally comprising environmentally hazardous components, such as Hg, Cd, Zn, Co or Ba. The waste is fed into a melting furnace in conjunction with an SiO.sub.