Abstract:
A fluidized-bed method of roasting sulfidic materials containing arsenic and/or antimony with a gas containing oxygen with separate supply of the gas containing oxygen for the preroasting in a first stage and for the afterroasting in the second stage and with separate withdrawal of the roaster gas from the preroasting stage and from the afterroasting stage. The dusty portion of the roasted intermediate product from the first stage is introduced periodically into the fluidized bed of the second stage and, in timed relationship with this periodic introduction of the roasted intermediate product, air is periodically introduced into the gas space above the fluidized bed in the second layer in such an amount that it is adequate for complete roasting of the dusty roasted intermediate products suspended in this gas space.