13 - Preparation of ultrafine powders by reaction-precipitation in impinging streams I: “Ultrafine” white carbon black

Abstract

This chapter investigates the preparation of ultrafine white carbon black powders by reaction-precipitation in impinging streams the submerged circulative impinging stream reactor (SCISR) is used for the preparation of “ultrafine” white carbon black. The experimental investigation include experiments for optimizing the operating conditions for the SCISR in semi-batch operation mode; experiments in the SCISR operated continuously under optimized conditions; and comparative experiments for the SCISR and the stirred tank reactor (STR). The major goal of the semi-batch experiments with the SCISR as the reaction-precipitation equipment is to determine the optimal conditions. Several factors influence the preparation of ultrafine white carbon black powders such as reaction temperature, rotary speed of propellers, concentration of the solutions used, and feeding position. Results suggest that CISR can be operated continuously in the preparation of ultrafine white carbon black by the common (one-step) precipitation process, and the average size of the particles in the product is essentially the same as those obtained by semi-batch operation. The results of the comparative experiments operated in semi-batch mode indicate that the product prepared with the SCISR is finer and with a narrower distribution than that from the STR. Study of the final treatment of the precipitate from the continuous operations of the SCISR with the help of spray drying experiment of the reacted wet precipitate revealed that the particle sizes of particles in the final product are stable. There is no coalescence of particles during the final treatment of the reacted wet-precipitate.