SYNTHESIS OF DIAMOND PARTICLES WITH AN ACETYLENE FIRED CIRCULATING FLUIDIZED-BED

For the development of a continuous diamond powder production process. a novel reactor concept, i.e., the acetylene partial combustion circu lating fluidized bed (CFB) or, in other words, a spouted bed with a sp ecial draft tube is proposed and results from fundamental investigatio ns are presented on the deposition kinetics, flame structure in terms of emission spectroscopy and the performance of a laboratory scale sma ll CFB reactor. It was found that diamond particles can be deposited e ven on ordinary carbon and/or alumina substrates. In the acetylene par tial combustion CFB reactor, diamond particles with clear 100 facets w ere obtained in a rather narrow range of the acetylene/oxygen ratio. I n the case of the deposition on carbon particles, the optimum acetylen e/oxygen ratio was found to be slightly low, indicating the gasificati on of substrate carbon itself. It has been clearly shown that diamond deposition on circulating suspension can be successfully done even if the once through contact time is small.