GB442437A - Improvements in manufacture of sulphur dioxide - Google Patents

Abstract

Sulphur dioxide; iron oxides; furnaces.--In obtaining sulphur dioxide by oxidizing fine particles of iron pyrites in suspension in a roaster having a throat opening into the combustion zone, the material is shaken through a screen in the form of a shower of fine particles into the throat separately from the air for oxidizing, and by applying suction to a remote portion of the combustion zone the air for oxidizing is induced to flow into the combustion zone in two independently regulatable streams, one entering the throat and mixing uniformly with the shower of pyrites and the other entering in annular form about the throat, uniformly surrounding and combining with the shower of pyrites. As shown in Fig. 2, finely divided pyrites is fed from a conveyer 6 on to a power operated vibrating screen 12 which shakes the material through a screen 13 into a feeding funnel 14. One stream of air for combustion is drawn through regulatable openings 16 into the funnel and the other through regulatable openings 17 about the <PICT:0442437/III/1> <PICT:0442437/III/2> funnel by means of a fan connected to the gas outlet 10. The combustion may be initiated by a burner ring 22. The walls of the combustion chamber are corrugated as shown at 24 and are surrounded by a water jacket 25 to provide cooling. The oxides collect at the bottom of the roaster in a dry seal formed between the conical bottom of the furnace and the conical bottom 28 of a water space 34. The annular top of the water space is covered by a cap 37 which has a conical top, and sides which extend downwardly over the water jacket to form an annular channel 39. The gases travel to the bottom of the furnace, make a sharp turn into the channel 39, and pass out of the roaster through a central channel 31 and the lateral outlet 10. Oxides deposited in the channel 31 pass through a contracted opening 32 into the dry seal. The water space 34 communicates with the water jacket 25 by means of pipes 35 and 36. The magnetic oxides still remaining in suspension in the gas are separated by cooling followed by magnetic separation. The gas conduit may be forked, a magnetic separator being interposed in each fork so that one may be cleared while the other is in use. The sulphur trioxide content of the gas may be kept at a minimum by a speedy flow of the gases through the critical temperature zone. Magnetic separators.--Each magnetic separator employed as above may comprise of alternately arranged overlapping magnetizable plates 42, 43, Fig. 4, extending respectively downwardly from the roof and upwardly from the floor and downwardly opening hinged discharge doors 44.