Particle classification of ground Ocimum Americanum seeds with fluidized technique

Abstract

Fluidized technique was introduced for classification of ground ocimum seed powder because of its prohibiting nature to other separation process by powder itself. The purpose of this study is to investigate the classification phenomena of ground ocimum seed powder by mean of elutriation, and to collect data for further design and operation. Physical characteristics of this powder concerning fluidization were investigated. It contains three species of particles that are fractions of seed coat, swelling substance and seed core. All species possess nearly the same density of about 1400 kg/m3 after drying at 70C for 1 hour. The particles size of this powder are ranging from 0-840 m with the average diameter of about 150 m. It was planned to remove the particles which were smaller than 125 m (120 mesh) by elutriation from batch fluidization process. Study of particle classification revealed that elutriation rate deviated from first order correlation, especially the intermediate particles of 74-150 m. Superficial gas velocity was the most important factor on elutriation. When freeboard was provided over 1 m high, little effect was observed on elutriation of intermediate particles. The rate was, however, increased while freeboard was lower than TDH. In addition, elutriation of particles smaller than 44 m was independent of freeboard height. For system of ocimum seed powder, It was evident that bed hydrodynamics may also involve in the elutriation process. This might due to the fine nature of powder itself and particlulate interaction of different particle species. Results of this study showed that this method was suitable for classification of ocimum seed powder in the pharmaceutical industry. Based on this experiment, for the specified size range, the pilot scale process could be performed under the freeboard height of 1.5 m and gas velocity of 1.15 m/s. for each batch of operation, it took only about 30 minutes time to yield 0.3 kg product, and approximately 0.15 kw-hr energy was required.