GB190913625A - Improvements in Roasting Furnaces. - Google Patents

Abstract

13,625. Merton, T. D., and Ridge, H. M. June 10. Roasting - furnaces ; charges; agitating.-Relates to furnaces for roasting pyrites, concentrates, slimes, or spent oxide obtained from gas works and employed in the manufacture of sulphuric acid. The furnace, which may be constructed with superposed hearths, is provided above the roof with a dust chamber, and is furnished with special means for discharging the material. The rabble shafts are arranged so that the hearth is divided into zones, and the rabble arms of adjacent zones are arranged to overlap only a short distance. As shown in Figs. 1, 2, and 3, where the number of rabbles in the five zones is one, two, three, two, one, respectively, the rabble arms within a zone cut deeply into the fields of adjacent arms, while the rabble arms at the end of a zone cut only slightly into the field of the arms in an adjacent zone. The ore is passed from one zone to another by oblique rabbles 52 on the ends of the arms of the zones to which the ore is to be transposed. When only two rabble shafts are employed, the fields of the arms slightly overlap at the centre of the hearth. Each rabble shaft K is protected in the dust chamber by a fire-clay casing 80 and is mounted in a jack foot-step 82 so that it is vertically adjustable. Seals 81 are arranged to prevent egress of gases or ingress of air. The material is fed to each hearth by screw conveyers M, and to discharge the ore an archimedean screw 70, Fig. 8, is enclosed in an iron case N, which is provided with a top slide 55 and a discharge shoot 63 having counterbalanced double doors 64<b>. A slide 55<a> at the bottom of the case may be arranged to close the shoot 63 and to allow the ore to pass to the hearth below through an outwardly bevelled opening 68<a>. From the upper compartment of the furnace the gases pass upwards through flues 75, 75<a>, 75<b>, to the dust chamber, which is provided with partitions 77 having staggered openings 78. The dust may be removed through doors 74 or raked through openings 76 into the compartment below.