7. Liquid flotation

7. Liquid flotation
    • Cleaning by flotation relies on the principle that the density of the seed of a given species is specific both for filled and ill filled seed. In this method, liquids with a density or specific gravity between that of the full and empty seed are used.
    • The specific gravity of the liquids used is such that the full seed sinks and the empty seed and light debris float.
    • The following factors to be taken in to consideration when designing a seed – cleaning plant:
    1. Handling and cleaning of the seeds should be possible without mixing or damaging seed with a minimum of equipment, personnel and time.
    2. Seed separators, elevators, conveyors and storage bins should be arranged so that seeds can flow continuously from beginning to end, yet be flexible enough to bypass a machine or return part for recleaning.
    3. Other factors to be considered are kinds of crop seeds to be cleaned, nature of contaminants and weed seeds, volume of seed to be handled, method of handling, type of conveying system and location of shipping and receiving facilities
    • Cleaning usually requires a succession of operations, which can be regarded as proceeding in three stages
    1. Conditioning or pre-cleaning,
    2. Basic cleaning and
    3. Separation and grading.

Last modified: Wednesday, 18 January 2012, 11:18 PM