| 摘要 |
<p><PICT:0836823/III/1> Alkali and alkaline-earth metal cyanides are prepared by reacting gaseous hydrogen cyanide, or gases containing hydrogen cyanide, with an alkali or alkaline-earth metal oxide or carbonate, including the bicarbonate, and especially the carbonate, at elevated temperatures, wherein the particles are continuously subjected to individual movements in opposition to the force of gravity throughout the action of the hydrogen cyanide, and are more especially maintained in the freely suspended state, for example in a fluidized bed or on a vibrating conveyer. The waste gas may be dried and the hydrogen cyanide separated from carbon dioxide by adding it to a mixture of hydrocyanic acid and pentaerythritol. In the preferred embodiment, sodium carbonate is fed from a hopper 11 to the lower end of a vibrating spiral support in a heatable container 16. A gas containing hydrogen cyanide enters 16 at 17 and moves downwardly in countercurrent to the sodium carbonate. The partially reacted carbonate leaves 16 at 17 and passes into the bottom of fluidized bed 114, surrounded by heating jacket 113. Fresh gas containing hydrogen cyanide enters at 112 and 111. The completely reacted carbonate and the partially exhausted gas leave at 115, and are separated in the cyclone 116, from which the gas is passed to 16 via line 118. The sodium carbonate may be obtained by calcining sodium bicarbonate, for which purpose waste heat from the cyaniding process may be employed, or the calcination and cyanide formation may be carried out in the same apparatus, for example by calcining in the bottom of container 16.</p> |
