Process and an apparatus for the division of melts

A process for the manufacture of mineral fibers by use of the nozzle, wherein

• (a) the contour of the nozzle inlet from the upper edge of the nozzle passes initially inside a radius R.sub.1 =40% of the narrowest cross-sectional dimension d of the drawing nozzle and then runs parallel to, or diverges by up to 2.degree. from the drawing nozzle axis up to a depth below the upper edge of the drawing nozzle which is not greater than the narrowest cross-sectional dimension d of the drawing nozzle;
• (b) the nozzle inlet is immediately adjoined by the drawing-out part, the upper cross-sectional dimension of which is from 1.5 to 2.4 times as wide as the narrowest cross-sectional dimension d of the drawing nozzle;
• (c) the drawing-out part widens over a length of at least 6 times the narrowest cross-sectional dimension d of the drawing nozzle with a widening angle of from 1.degree. to 2.4.degree. and,
• (d) in the intermediate cross section between the lower edge of the nozzle inlet and the upper edge of the drawing-out part, there are provided propulsion jet nozzles, the axis of which is inclined by from 5.degree. to -2.degree. to the drawing nozzle, wherein a desired pressure of from 0.25 to 0.4 of the ambient pressure upstream of the inlet of the drawing nozzle is predetermined in the lower third of the drawing-out part, the pressure is measured at least periodically and, if the pressure which has been measured deviates from the desired pressure, suitable parameters are changed such that the desired pressure is reproduced.