Method for leaching and purifying selenium under normal pressure

The invention discloses a method for leaching and purifying selenium under normal pressure, which comprises the following steps: mixing crude selenium, a leaching agent and water, transferring the mixture into a reaction container, and carrying out leaching reaction at the temperature of 100-115 DEG C to obtain a first reaction product; the first reaction product is taken out for vacuum filtration, and a leaching solution is obtained; transferring the leachate to a directional precipitation tank, and dropwise adding sulfuric acid into the precipitation tank under a stirring condition for reaction to obtain a second reaction product; and carrying out vacuum filtration on the second reaction product to obtain a precipitate, and washing the precipitate to obtain 3N selenium. Wherein the leaching agent is selected from one of ammonium sulfate, potassium sulfite, sodium sulfite and calcium sulfite. The method has the characteristics of low production cost, high leaching efficiency and high purity of the obtained 3