An efficient technology for low-grade bismuth-lead concentrate smelting is reported. In the process, two oxygen-rich side blow furnaces (OSBF) are used for oxidative smelting of the concentrate and reductive smelting of the oxidized slag from the upstream furnace, respectively. Slags are collected from the OSBFs by certain intervals during an operation period and analyzed by inductively coupled plasma-atomic emission spectrum, x-ray diffraction and scanning electron microscopy. Analysis for the oxidized slag revealed that spherical or oval metallic inclusions with sizes range from submicron to 40 mu m in diameter are randomly embedded in the glassy matrix. On the one hand, the metal content of the inclusions is close to that of the bottom metal alloy, indicating metal inclusions are physically entrained in the oxidized slag. On the other hand, metal inclusions are not identified in the reduced slag, disclosing the strong metal-slag separation ability of the OSBF. The bismuth content of the reduced slag is about 0.05 wt.%, which is 6-10 times lower than that of the traditional pyrometallurgical processes.
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