Abstract: The present invention concerns a method for melting recycled silicate starting materials. A rotating transport flow with helical flow filaments of transport air and starting material is supplied in the direction of the helix axis into the combustion chamber of a cyclone furnace. Preferably, pre-heated fresh air is used which is supplied partly into the combustion chamber as combustion air therefor and partly in the form of the transport air. Furthermore, the present invention concerns a device for melting recycled silicate starting materials. The device includes a combustion chamber where fuel and combustion air can be burnt up in the presence of the starting material. A forechamber is arranged between an admixer for generating an injector flow and the combustion chamber. The injector flow can be supplied into the forechamber through a charging conduit to generate a transport flow made up of starting material and transport air. The forechamber includes an outlet port opening into the combustion chamber.

Abstract: The melting tub for producing the molten mass from a mixture of raw material is associated with an additional melting unit by means of which a recycled molten mass is obtained from mineral wool waste largely corresponding to the molten mass obtained from the mixture of raw materials in quality and composition. The recycled molten mass is supplied to the molten mass in the melting tub through a suitable introduction device. The recycling exhaust gas from the additional melting unit is fed to the tub exhaust gas, and the mixture of exhaust gas is utilised for pre-heating combustion air and mixture of raw materials.