GB1043815A - Process and apparatus for the manufacture of hydrated lime - Google Patents

Abstract

<PICT:1043815/C1/1> Hydrated lime is made in a continuous process by applying water to particulate burnt lime, passing the resulting mixture across a plurality of drying tables, passing a gaseous drying medium through each drying table in countercurrent to the mixture, and collecting the hydrated lime so obtained. Preferably, from 0.6 to 0.7 kilogram of water, which may be applied in the form of a spray, is added per kilogram of burnt lime. The gaseous drying medium, which may be air-heated by the heat evolved in the reaction of the water and burnt lime is preferably made to pass through an inclined porous top of each of the tables. The slaking process may take place in apparatus, Fig. 1, in which burnt lime is raised by elevator 1, discharged through conduit 1a into hopper 2, and introduced by feeder 3 into screw conveyer mixer 4. Water from supply tank 5 is raised by pump 6 through pipe 6a to spraying device 12 situated in spray tower 13, and falls as a spray through heat exchanger 7 and delivery portion 7a upon the burnt lime passing through the mixer in which the lime and water are mixed. Steam resulting from the hydration of the lime rises from the mixer into a second heat exchanger 14 which contains coiled pipe 8. Air, introduced by a blower through entrance 15, passes through the pipe and conduit 9 and into hydrating device 10 which contains a series of porous tables 19 arranged in a vertical row in spaced staggered relationship so that each table extends over part only of the next table. Preferably, the porous tables are slabs of highly porous ceramic material, for example fire-brick. The water-lime mixture passes from the mixer to the hydrating device, through which it descends, passing by gravity successively across the tables through which the heated air is passed in countercurrent. Hydrated lime passes via exit 16 to separator 11, product of a desired size range being obtained via exit 17 and particles outside this size range being expelled via exit 18.