GB807433A - Improvements in and relating to the manufacture of briquettes from coal and other material - Google Patents

Abstract

807,433. Making briquettes. COAL INDUSTRY (PATENTS) Ltd. Nov. 24, 1954 [Nov. 24, 1953 ; Feb. 12, 1954], Nos. 32592/53 and 4257/54. Class 87(2). Coal dust and other powdered material is briquetted by a method wherein the mass of particles under pressure is caused to undergo angular shear strain of predetermined magnitude and distribution. The angular shear strain is expressed as a mathematical formula and its characteristics in an experimental briquette are first found by dividing the briquette into layers and superposing them in a mould with deformable pellets, e.g. lead balls, arranged along the diameter of each layer. The mass is then briquetted and the ratio of maximum to minimum diameter of each pellet is measured, e.g. by X-ray photography, in the finished briquette, from which ratio the angular shear strain may be calculated. Thus the suitability or otherwise of the material may be decided experimentally and the conditions, e.g. of pressure, to produce the required angular shear strain may be found. Such conditions attend various briquetting methods described. The material 34, Fig. 2, may be compressed between oblique-ended plungers 31, 32 in a circular mould 33 with relative rotation between the mould and plungers. Further pressure may be applied to powder, already compacted in a mould 41, Fig. 4, by a second plunger with a projection from its face. A two-part plunger, Fig. 13, may be used, the inner and outer parts 22, 21 first moving together till a certain pressure is reached and the part 22 then continuing alone and pressing a protrusion of the material into the main body. An extrusion die of variable crosssection, e.g. a circle to an ellipse, may be used ; also double roller or ring roller briquetting presses. The mould may be hemispherical. whereby the surface of the brquette follows a line of distribution of equal angular shear strain. Binderless black coal briquettes may be produced by the invention, but the use of a binder is not excluded. The particles may be preheated. They should have no surplus moisture. Other powdered materials which may be briquetted by the invention are metals, e.g. aluminium and copper, and catalysts of the alumina silica type. Numerical examples are given. Specification 616,857 [Group XII] is referred to.