| 摘要 |
1,239,646. Complex fluorides. G. L. FLEMMERT. 18 Dec., 1968 [12 Jan., 1968], No. 60157/68. Heading C1A. The composition of the solid complex fluorides sodium fluosilicate (into sodium fluoride and silicon tetrafluoride) and sodium bifluoride (into sodium fluoride and hydrogen fluoride) is effected by entraining particles of the complex fluoride, having an average particle diameter of less than about 1 mm., in a turbulent stream of preheated non-reactive gas at a Reynolds Number within the range 10<SP>4</SP> to 10<SP>6</SP>, heating at a temperature within the range 250-750‹ C. but below the softening temperature of sodium fluoride or the sodium fluoride/sodium fluosilicate eutectic mixture, and then separating the sodium fluoride and decomposition gases thereby obtained. If the complex fluoride is sodium fluosilicate, then the decomposition temperature is within the range 550‹ to 750‹ C.; if it is sodium bifluoride, then it is within the range 250‹ to 500‹ C. The complex fluoride may be brought to the decomposition temperature at least twice and held there for between 0À5 and 5 seconds. After decomposition the gaseous products may be recycled at least once and mixed with the non-reactive gas stream. In order to prevent plugging of the apparatus with solid material during operation, 10-20% of sodium fluoride or up to 5% of silica or up to 5% of carbon black may be mixed with the particles of complex kuoride. Apparatus is specified for carrying out the invention. |
