PbSO 4 is the main component of lead paste, lead smoke and other lead-containing solid wastes. It usually matches with the primary lead concentrate to co-smelt for lead extraction, mostly in the oxidation smelting stage. The lead waste quickly experiences different temperature and atmosphere fields from feeding the furnace to the completion of the reactions. This work investigated PbSO 4 decomposition kinetic and phase transformation mechanism during lead waste pyrometallurgical recycling. The results show that the activation energy of the decomposition reaction of PbSO 4 at 800 ℃∼1000 ℃ in Ar atmosphere is 121.35 kJ/mol. The PbSO 4 decomposition reaction in Ar and Air is a multi-step decomposition process, which may undergo PbSO 4 → PbO·PbSO 4 → 2PbO·PbSO 4 → 4PbO·PbSO 4 → PbO. PbO is not generated through direct decomposition of PbSO 4 . The results are expected to provide guidance for the lead wastes co-smelting process to achieve a target PbSO 4 decomposition product.
At present, lead-containing wastes have increasingly become the raw materials together with primary lead concentrate for lead production to meet the ever-increasing lead demand market. PbSO 4 is the dominant component in the lead-containing wastes, nevertheless, its reaction behavior during lead smelting is not sufficiently investigated. This study investigated PbSO 4 decomposition behaviors and phase transformation mechanisms at oxidizing and reductive atmospheres and various gas flow rates. The investigations reveal that increasing the temperature and decreasing the oxygen partial pressure of the decomposition atmosphere can accelerate PbSO 4 decomposition degree. PbSO 4 decomposition intensity under different atmospheres follows the order of reducing atmosphere > inert atmosphere > oxidizing atmosphere. PbSO 4 decomposition path was identified: at a non-reductive atmosphere, the decomposition of PbSO 4 belongs to a multi-step decomposition process, PbSO 4 gradually decompose into xPbO·PbSO 4 (x = 1, 2, 4 in turn) and finally PbO. At a reductive atmosphere, the multi-step decomposition process was accelerated significantly, at the same time, the reduction decomposition path PbSO 4 → PbS was increasingly dominant with the extension of decomposition time. PbS and Pb were generated successively. Therefore, a suitable reducing atmosphere is suggested to co-smelt PbSO 4 -bearing wastes in primary lead smelting furnace.
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