Continuous basalt fibers: production aspects and simulation of forming processes. II. Optimizing the fiber production technology through simulation of heat-exchange processes in bushing nozzles

Methods for determining the rheological and crystallization properties of basalt melts are considered. The physical properties of basalt melts suitable for the production of continuous fibers are compared with those of E-glass melts. It is established that the shape of the melt stream characterizes the fiber-forming area and depends on the production parameters and melt properties. A mathematical model is proposed to describe heat exchange during slow flow of basalt melt through a short nozzle into air and during its cooling. The longitudinal temperature distribution in both the melt and nozzle wall is calculated for various structural and processing parameters. It is shown that the melt is cooled to the greatest extent at low flow velocities (high viscosity) in longer nozzles with large internal diameter (small wall thickness). The results may be used to calculate temperature of the melt in a free stream flowing out of a nozzle and to optimize the continuous basal fiber technology.