Process and apparatus for agglomerating pulverulent materials and products thereof

摘要

Pulverulent material such as ammonium sulphate and sodium hexametaphosphate, is agglomerated by continuously dispersing the material so as to fluidize the particles of the material and form a fluidized bed in which the particles are dispersed and suspended in intimate relationship and make repeated contact with one another, maintaining the material within the confines of the bed while moving the bed over a supporting medium, and subjecting the fluidized particles of at least a part of the moving bed to a condition changing agent, such as the condensation from superheated vapour or vapour-gas mixture, so as to form adhesive agglomerating surfaces on the particles and thereby effect the agglomeration. The preferred procedure is depicted in Fig. 4. Dry pulverulent material from a hopper 10, Fig. 2, is kept in a fluidized state as it moves over 60-400 mesh glass cloth screens 16, 18, 19 and 20 by the circulation of gaseous media as follows: air at room temperature between chambers 26-29 for initiating the fluidization of the material, hot air and superheated steam between chambers 31-33a for agglomeration of the material (as depicted in Fig. 4), hot air between chambers 35-38 to dry the agglomerates and unheated air between chambers 40-43 to cool the dried agglomerates. Finally the cooled agglomerates are sized on a screen 21, the undersized being collected from a separate shoot 46. The apparatus is mounted on struts 78 so that a rapid vibratory movement may be imparted to it through a reciprocating arm 82. Examples are directed to agglomerating the following materials: (1 and 6) mixes suitable for angel food cake consisting of about 32% dried egg albumen and 68% powdered sugar, anhydrous monocalcium phosphate being employed as a pH control agent in Example 1, (2) a mixture of 20% cocoa powder and 80% finely ground sugar, (3) various mixtures of flour and powdered sugar, (4) powdered sugar alone, (5) ground ammonium sulphate, and (7) ground sodium hexametaphosphate. The agglomerates were free flowing and quickly dispersible in cold liquid. Other materials mentioned are lard flakes and glyceryl monostearate.