Patent EP-2708517-A1 (EP)
Inventor: BRUNNMAIR ERNST ERWIN
IPC: C03B19/10
Filed: 2013-09-12
Abstract: The process comprises swelling granulated particles including initial mixture of glass dust grains such as waste glass powder particles and binder such as water glass, and thermally treating the particles having carbon dioxide and crushed grain minerals as propellant in an oven (4). The swelling step comprises conveying the particles in a shaft of a furnace along a conveying path by heating zones (7) separated from each other and arranged along conveying section by force of gravity, and heating the particles. The process comprises swelling granulated particles including initial mixture of glass dust grains such as waste glass powder particles and binder such as water glass, and thermally treating the particles having carbon dioxide and crushed grain minerals as propellant in an oven (4). The swelling step comprises conveying the particles in a shaft of a furnace along a conveying path by heating zones (7) separated from each other and arranged along conveying section by force of gravity, heating the particles to a critical temperature of the crushed grains minerals or greater than a softening temperature of the particles, and discharging the bulked particles from the furnace. The crushed grain minerals are plastic at the critical temperature, and form a closed surface of the particles at the softening temperature. Heating elements (8) along the remaining conveying section in dependence of the critical temperature of the crushed grain minerals and/or the softening temperature of the particles are regulated upon detection of a first reduction in temperature of the particles between two successive positions along the conveying section. A power of the heating elements along the entire remaining conveying section is set to zero. The particles have a softening temperature of 70-110%. The temperature of the particles is measured at the furnace shaft to detect the first reduction in temperature of the particles of 100[deg] C between two successive positions along the conveying section. A change of the heat flowing to the particles is determined by the heating elements and determined the between the heating zone and a next heating zone. The detection of the first reduction in temperature of the particles between two successive positions along the conveying path occurs by detecting a heat flux increased in the heating zone to the next heating zone. The method further comprises drawing the particles with a first process air through the shaft, and supplying cooling air such as chilled fluid to the particles below a temperature of 80[deg] C after discharging step. The first process air flows at a constant speed through the furnace shaft. The particles are transported at a constant speed through the furnace shaft. A rate of transportation of the particles is dependent on their diameter. The first process air is drawn with a direction component against gravity through the furnace shaft. The particles, after discharge, are transported into a storage container by a pneumatic entrainment support so that the particles are cooled in the storage container at a room temperature. An amount of water or carbon dioxide in the particles is 0.3-6 wt.%.