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.