An Experimental Study on the Formation of Lead Aerosols

Abstract

Lead aerosols were prepared by condensation method, employing argon, nitrogen or carbon dioxide as carrier, whereby the metal was heated in an electric furnace at various temperatures between 950° and 1150°C and the carrier was passed through the furnace at several rates of flow ranging from 0.5 to 4.5l/min. By using a Cottrell precipitator, the aerosols were sampled to determine the lead content as well as photographed by an electron-microscope to make the size distribution.The findings are as follows: (1) The weight concentration as well as the particle size goes through a maximum with the rate of flow of the carrier, whereas the number concentration a minimum. (2) The degree of dispersion is affected by the temperature of generation of the vapor and the rate of flow of the carrier, the aerosols being found to be of the highest monodispersity under the conditions of temperature 1100°C and rate of flow 1.5l/min in argon, and some temperature over 1150°C and a rate of flow near 1.5l/min in carbon dioxide.Some consideration has been given of these results, taking account of the rates of (1) the vaporization of metal, (2) the flow of carrier and (3) the thermal precipitation and mutual coagulation of particles.