The invention discloses a method for separating
selenium and mercury from acid mud of a
copper-lead-
zinc smelting sulfuric acid system. The method includes the steps of 1) leaching the
selenium and solidifying the mercury from the acid mud by adopting the
oxygen pressure-alkaline leaching process, specifically, mixing the acid mud,
sodium hydroxide and
lime to form
slurry, adding the mixture into a reaction kettle according to a proportion, then, injecting
oxygen-enriched gas into the reaction kettle, increasing the pressure to reach 1.7-2.2MPa, namely 17-22atm, carrying out heating to reach 160-220 DEG C, then carrying out
oxygen pressure-alkali leaching for 1-4 hours, and condensing
tail gas of the reaction kettle to remove mercury steam through a condensation tank, wherein
condensed water returns to the reaction kettle to be recycled as a liquid for a alkali leaching mixture; 2) carrying out
solid-liquid separation; 3) sealing and storing alkali leaching residues in the step 2), and sending the alkali leaching residues to a mercury factory to recover the mercury in a centralized mode; and 4) carrying out efficient reduction to prepare crude
selenium, specifically, purifying alkali
leachate in the step 2) and then carrying out reduction to recover the selenium. Compared with an existing technology for calcinating the acid mud by adding the
lime, the method for separating the selenium and the mercury from the acid mud of the
copper-lead-
zinc smelting sulfuric acid system has the advantages that the
reaction temperature is greatly reduced, the oxygen-enriched gas is used for oxidation, other oxidizing agents do not need to be added, the treatment cost is saved, and the
leaching rate of the selenium is increased.