GB229158A - Improvements in or relating to the pulverization of substances - Google Patents

Abstract

229,158. Procter, H. A., Young, A. E., and Iliffe, R. J. May 17, 1924. Roller-and-ring mills. - Relates to mills for grinding or pulverizing hard substances and of the kind comprising one or more rollers or mullers carried by a revolving disc or pan bottom and adapted to crush the material against a stationary ring or wall, the fine material being withdrawn from the mill bv an air current. Means is provided whereby material which may escape through the space between the pan bottom and the ring and upwardly air-borne shall be directed inwardly or downwardly, or both, to the mill. A lip is so disposed within the pan that any material which may escape laterally from the pan in the grinding process and is upwardly air-borne shall be returned to the mill. Baffle plates or vanes preferably set an inclination to the direction of rotation of the mill or of the rollers prevent incompletelyreduced material from being thrown outside the pan. As shown, Figs. 1 and 2, the mill, comprising a pan with a rotary bottom 4 carrying movable arms 7 with rollers 6 bearing against a stationary wall 5, is disposed within a casing 1, 1<a>, the portion 1<a> consisting of two members hingedly connected by a rod 2 so that access may be readily obtained to the interior of the casing. An annular depending lip 1<b> is formed on or secured to the interior of the casing 1, and a ring 1<d> is secured to or forms part of curved baffle-plates or vanes 1<c> disposed at the back of the lip 1<b>. The pan bottom 4, which is concave and fitted with baffle-plates 13, is secured to a central shaft 8 driven through bevel gearing from a driving-shaft. The shaft 8 passes through a tubular extension 14 secured to the floor 4 and carries at its upper end a table 17 with vanes or blades 18 on its periphery. The open receptacle 15 carried by the extension 14 is provided with a number of shoots 16 the lower ends of which are positioned so that the material discharged therefrom is fed near the top of the ring 5 and falls in advance of the rollers 6. The feed-hopper 19 arranged above the discharge mouth 3 of the mill is provided with a tubular stem 20 containing a slidable tube 21 that can be adjusted by means of a hand-lever 22 to regulate the supply of the material to the table 17. Air under pressure is delivered to the casing 1 by pipes 25 and passes through openings 26, 26<a>, 27, 30 in the floor 4 and passages 28 in the shaft bearing 29 thereby carrying the pulverized coal &c. and the finer particles in the feed through the mouth 3 to a storage bin, fuel-burner, &c. Air also passes through the space 1<e> between the casing 1<a> and the rings 5, 1<d> and is directed by the lip 1<b> through the spaces between the vanes 1<c> towards the floor 4. Scoops or vanes 4a on the underside of the pan guide the air to the ports 26. In another arrangement, Fig. 7, an annular depending flange 4<b> on the pan floor 4 is disposed in a channel 1<f> in the casing 1 and carries air blades or vanes 31. Rubbing rings 5<b> are provided on the floor 4 and the lower face of the stationary wall 5. The material is fed through a lateral opening 19<a> in the casing and falls directly on to the floor 4 or on to a revolving distributor. Any material escaping from the pan through the rings 5b is carried by the air passing through the annular space 32 and is diverted by the lip 1<b> through the spaces between the vanes 1<c> towards the floor 4.