The rotary top-blown Kaldo furnace is used to process decopperized lead anode slime after pressure leaching and drying. Silver-bearing anode slime is mixed with reducing agents and auxiliary materials, then charged into the furnace in batches. The process sequentially completes reduction, converting, and refining, producing gold-silver alloy, smelting slag, and off-gas.
This furnace operates in batch mode. The charge is preheated from room temperature to 1000°C, then heated further to 1200°C to 1250°C for oxidation-reduction converting. The furnace rotation speed is 1-6 r/min. Each furnace cycle is divided into three stages: smelting, converting, and refining, with a full cycle time of 24-26 hours.
The wear rate of the refractory lining in the gas-phase zone is significantly higher than that in the molten bath zone. Magnesia-chrome bricks with 20%-22% Cr2O3 content are recommended for the gas-phase zone; magnesia-chrome bricks with 18%-20% Cr2O3 content are used for the molten bath zone; and magnesia-chrome bricks with 16%-18% Cr2O3 content are used for the furnace roof/cover area.
