GB574421A - Improved method and means for processing or calcining materials - Google Patents

Abstract

574,421. Processing materials. ELLERBECK, T. R. April 8, 1943, No. 5595. Convention date, April 7, 1942. [Class 34 (ii)] [Also in Group XII] In the processing of organic and inorganic materials such as limestone, ores, coal and the like by passing them by gravity through a treatment zone, the material is discharged variably at the base of the treatment zone throughout the length and breadth thereof in accordance with the different intensities of treatment it has undergone at different locations in the treatment zone. In the apparatus shown in Figs. 1, 2, material such as limestone is fed from a hopper 150 through telescopic shoots 115 into a shaft 110 provided with horizontal rows of staggered baffles 125 which form with the material to be treated horizontal channels 222, 223, 224 into which tempered gases from a combustion chamber 121 are supplied through openings 122, 123, 124 in the furnace wall. The combustion chamber is supplied with fuel from burners or an underfeed stoker and the gases are directed to the openings 122, 123, 124 by baffles 37, 40. The gases are withdrawn from the upper part of the shaft by a fan 45 and part of the gases are returned to the combustion chamber 121 through conduit 46 and passages 48 for tempering the furnace gases. Air may also be admitted to the combustion chamber for tempering the gases. The material passes down the shaft between baffles 58 to discharge openings 31 where the discharge of material throughout the cross sectional area of the shaft is controlled by reciprocating transverse bars 65 arranged above plates 64 spaced from the discharge openings 31. The bars 65 rest in slots in fixed frame members 67 and also extend into slots 73, Fig. 5, in a reciprocating frame 60 which carries vertically adjustable dogs 68 provided with V-shape recesses the sides of which engage with the ends of the bars 65 when the frame is reciprocated and cause the material to be discharged over the edges of the plates 64. By varying the height of the individual dogs 68 the traverse of the bars 65 above the plates 64 may be varied and the discharge of material regulated as required. The contour and cross sectional area of the bars 65 may take different forms to further assist the regulations of the discharge. Figs. 16 and 17 show a modified form of discharge device consisting of rows of rotary members 100 arranged on transverse shafts 101 in a fixed frame beneath the discharge openings 31. The rotary members may be given various degrees of oscillation to vary the discharge by means of vertically adjustable bars 105 mounted on a reciprocating frame 107 and adapted to contact the walls of V-shape recesses 104 in the lower parts of the rotary members. When it is desired during the calcination of limestone to recover the carbon dioxide produced, the lower row of openings leading from the combustion chamber 121 into the furnace are blocked off as shown at 80, Fig. 9, air is admitted for cooling purposes to the lower part of the shaft through passages 81 and withdrawn through passages 82 by a fan 84 whilst air is also withdrawn through pipes 88, 87, 89 by the fan 84 from the lower part of the hopper 150. The carbon dioxide gases are withdrawn from the upper part of the shaft by the fan 45. Instead of employing a separate combustion chamber, coke and limestone may be fed in layers into a hopper 161, Figs. 13 and 14, provided with rows of staggered baffles 168-172 and the fuel and limestone are delivered into the processing shaft 160. Air is supplied to and extracted from the lower part of the shaft and from the lower part of the hopper while carbon dioxide is withdrawn at 167. Specification 574,444 is referred to.