Apparatus for sulfatizing roasting of a finely-divided selenium-bearing raw material

An apparatus for the sulfatizing roasting of selenium-containing raw material, especially anode slime from copper electrolysis, with sulfuric acid at a raised temperature, the apparatus comprising:

• a furnace chamber having an inlet for a slurry of finely-divided, selenium-containing raw material and sulfuric acid, an outlet for withdrawing roasted solid from the furnace chamber, an outlet for discharging selenium-bearing gases produced during the sulfatizing roasting, means for heating the slurry in the furnace chamber, and at least one combination of a tray supporting the slurry and a scraper scraping the tray for transferring, as a layer, the slurry fed into the furnace chamber from the slurry inlet towards the outlet for solid, at least some of the slurry-heating means being mounted in one tray in order to heat it, wherein the slurry inlet is a pipe bent to the side at its lower end and fitted through the top of the furnace chamber and concentrically rotatable with the trays or scrapers in order to distribute the slurry onto a topmost tray.