| 摘要 |
1,228,241. Evaporators; separation of solids from solutions and slurries; coating apparatus; coated particles. DOW CHEMICAL CO. 11 March, 1968 [13 March, 1967], No. 11789/68. Headings BIB, B2E and B2L. [Also in Divisions C1 and F4] Solids are obtained from liquid mixtures comprising solid material and evaporable liquid, by forming a moving (e.g. fluidised) bed of particles in a chamber 16 by passing heated drying gases upwardly therethrough from plenum 26, pneumatically conveying particles from a lower chamber portion through a tube assembly 50 external to the chamber, to an upper chamber portion, spraying the particles in the assembly 50 with a liquid mixture from a nozzle 66 to coat the particles and drying the coated particles in chamber 16. The dried coated particles may be intermittently removed from the chamber through an air lock and control valve 40 and screen classified at 42. Air from inlet 90 may be passed through a perforated plate 64 surrounding the nozzle 66, to assist in conveying the particles through the assembly 50. The chamber 16 may have one or more than one tube assembly 50 associated therewith. The openings communicating the chamber 16 with each assembly 50 may be closed by slide gates 54. The spray nozzle 66 (Fig. 11) may comprise a central passage 80 for the liquid mixture and an annular passage 82 for gas to atomise the liquid. The liquid mixture may be a solution or slurry and the evaporable liquid may be an evaporable molten material. Pellets of calcium chloride can be prepared by coating calcium chloride particles with calcium chloride solution. Similarly pellets of sodium hydroxide, sodium carbonate, iron chloride, ferric oxide, sodium bromide, magnesium sulphate, sodium salicylate, sodium trichloroacetate, and the potassium salt of 2, 4-dichloro-4- pyridinol can be prepared. |
