Treatment method of waste acid generated in copper smelting

摘要

PROBLEM TO BE SOLVED: To provide a method of treating waste acid capable of reducing the amount of cadmium repeated in the smelting process and reducing the amount of water carried in to reduce the drying cost.;SOLUTION: The method of treating waste acid includes: a first sulfurization step of carrying out solid-liquid separation into the first sulfurized sediment and the first clear liquid after adding a sulfurizing agent to a waste acid containing a heavy metal and a sulfuric acid component, and then sulfidizing the heavy metal; a gypsum production step of carrying out solid-liquid separation into gypsum and gypsum final solution after adding a calcium-based neutralizing agent to the first clear liquid and then producing gypsum from the sulfuric acid; and a second sulfurization step of carrying out solid-liquid separation into a second sulfurized precipitate containing cadmium and a second clear liquid after adding a sulfurizing agent to the gypsum final solution and sulfidizing remaining heavy metal. When the cadmium grade of the second sulfurized precipitate is less than 40 mass%, the addition amount of the sulfurizing agent is increased in the second sulfurization step, and when the cadmium grade of the second sulfidation precipitate exceeds 50 mass%, the amount of the sulfurizing agent is decreased in the second sulfurization step.;SELECTED DRAWING: Figure 1;COPYRIGHT: (C)2019,JPO&INPIT