A method for stepwise separation and recovery of selenium and mercury from acid sludge

Abstract

The present application relates to non-ferrous metallurgy and secondary resource comprehensive utilization field, disclose a kind of acid mud selenium and mercury cascade separation and recovery method, by adjusting acid mud leaching solution total chloride concentration to 3.5 to 4.5mol / L, using coordination effect will mercury ion be converted into stable mercury chloride complex ion, significantly negative shift mercury's conditional electrode potential;Crude selenium seed and modified sodium lignosulfonate are introduced into the system, and an organic modification layer with steric hindrance effect is constructed on the surface of the seed;By adding reducing agent in stages and combining online ORP feedback control, induce elemental selenium to heterogeneously precipitate under the guidance of the modification layer, and convert from amorphous red selenium to hexagonal gray selenium through high-temperature curing;After solid-liquid separation, dilute the selenium-removed solution to promote the dissociation of mercury chloride complex ion, and then adjust the acidity and precipitate and recover mercury. The present application realizes the selective and deep separation of selenium and mercury, improves the product purity and the material filtration performance, and realizes the closed circuit circulation of process materials.

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