Abstract: A process of melting silicate raw materials includes the steps of using the tank exhaust gases to heat the combustion air, using the tank exhaust gases to preheat a mixture of raw materials, removing acid gaseous aggressive media from the tank exhaust gases, then using the tank exhaust gases to preheat the combination air. Because the acid gaseous aggressive media are removed from the tank exhaust gases before the tank exhaust gases are used to preheat the combustion air, more heat can be withdrawn from the tank exhaust gases than was heretofore possible, since there is no danger of acid condensation even when the tank exhaust gases are cooled to near ambient temperature.

Abstract: Apparatus for producing mineral fibres from silicate raw materials such as basalt by blast drawing.When blast drawing is used to produce mineral fibres from basalt, there is arranged between the entry zone (26) of the chute (16) and the exit zone of the nozzle slot (10) of the blast nozzle unit (8), this slot forming the fiberization duct, a guide cell (13). The relative position of the side walls (29) of the guide cell is freely adjustable, so that desired flow conditions can be set and also the exit direction of the exit flow bundle (31) and hence the web formation can be controlled. As a consequence of a lateral distance (a) of the exit orifice (28) of the guide cell (13) relative to the entry flow bundle (27) additional secondary air is sucked in, which has a further cooling effect on the fibres.

Abstract: To produce basalt wool having a large fibre diameter of if desired 10 .mu.m with high output and low bead formation, the exit cross-section of the exit orifices (6) of the distributor tank (5), the vertical distance (vA) between the exit orifices (6) and the blow-in slits (29) for propellant gas, the horizontal width (hB) of the nozzle slot (10) and the vertical length (vL) of the nozzle slot (10) downstream of the blow-in slits (29) are dimensioned to be unusually large for an apparatus for producing rock fibres by blast drawing. As a result, it is possible to operate at a low melt temperature and a high propellant gas rate combined with a low propellant gas pressure in order, surprisingly, to obtain a coarse-fibered product with low bead formation and high output.

Abstract: A process and apparatus for controlling the operating conditions, particularly the temperature and pressure, of attenuating gas employed in the fiberization of thermoplastic materials. The arrangement disclosed provides for temperature and pressure controls of the hot attenuating gas blast used in connection with a centrifugal or spinner type of technique for making fibers from thermoplastic mineral materials such as glass.