| 摘要 |
PURPOSE:To readily increase temperature in a short time and continuously obtain the titled B2O3 with excellent thermal efficiency, by introducing boric acid liquefied in a low-temperature heating vessel into a crucible in an aslant installed heating furnace having a specific temperature gradient and flowing down the boric acid while heating. CONSTITUTION:Powdery boric acid is introduced from a raw material charging inlet 11 into a low-temperature heating vessel (A'), heated to 150-200 deg.C with heaters (B) and liquefied. The resultant liquefied boric acid is then introduced through a liquid feed pipe 15 into an aslant installed and top-opened crucible 2 made of stainless steel, etc., in a heating furnace (A), heated and concentrated with heaters 8 provided at the ceiling 1 of the heating furnace (A) so as to give 150-350 deg.C at a position (a), 250-450 deg.C at a position (b) and 600-700 deg.C at a position (c) near the back end, overflowed and flowed down from the crucible 2, successively heated and converted into B2O3 of a bubble form 4 and then thick malt syrup form 5. Thereby the titled B2O3 is continuously obtained from a B2O3 flowing down and taking outlet 6 as indicated by an arrow. On the other hand, steam generated by dehydration in this process is discharged from an air vent hole 7 provided at the ceiling 1 to the outside of the furnace (A).
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