A method and system for the co-recovery of mercury and selenium from acid sludge based on the coupling of Fe(III) / Fe(II)-O2 catalytic cycle and selective oxidation.

By using Fe(III)/Fe(II)-O2 homogeneous catalytic cycling and Cl- complexation, the problem of efficient recovery of mercury and selenium from smelting acid sludge was solved, realizing the high-value separation of mercury and selenium under normal pressure, reducing energy consumption and hazards, and achieving the effect of green production.

CN122303598APending Publication Date: 2026-06-30GUIZHOU UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
GUIZHOU UNIV
Filing Date
2026-05-09
Publication Date
2026-06-30

AI Technical Summary

Technical Problem

Existing technologies for recovering mercury and selenium from smelting sludge suffer from problems such as high energy consumption, dangerous operation, introduction of many impurities, complex processes, and low recovery rates. In particular, it is difficult to achieve efficient synergistic leaching and high-value separation of mercury and selenium under normal pressure and mild conditions.

Method used

A homogeneous catalytic cycle system of Fe(III)/Fe(II)-O2 was adopted, using oxygen in the air as an oxidant. By constructing a homogeneous catalytic cycle of Fe(III)/Fe(II)-O2 and combining it with Cl- complexation, selective oxidation and efficient leaching were achieved to form a soluble Se(IV) chloride complex that stabilizes mercury. High-purity metallic mercury was then recovered by electrochemical methods.

Benefits of technology

The efficient synergistic leaching of mercury and selenium was achieved under normal pressure and mild conditions, which reduced oxidant consumption, simplified the process, improved the recovery rate, and reduced the generation of wastewater and waste salt, thus achieving the goal of green and low-carbon production.

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Abstract

This invention provides a method and system for the synergistic recovery of mercury and selenium from acid sludge based on a Fe(III) / Fe(II)-O2 catalytic cycle coupled with selective oxidation. The method includes the following steps: mixing acid sludge, sulfuric acid solution, Fe(III) salt, and chloride to form a redox pair containing Fe(III) and Fe(II) and Cl... ‑ The slurry is leached in the presence of oxygen-containing gas by adding an oxidation initiator and heating to form a catalytic oxidation cycle, thereby obtaining the leaching product. The leaching product is then subjected to solid-liquid separation to obtain leaching residue and a leachate rich in Se(IV) and mercury chloride complex. A reducing agent is added to the leachate to reduce Se(IV) to elemental selenium, and crude selenium product and mercury-containing mother liquor are separated. The mercury-containing mother liquor is then subjected to electrochemical reduction treatment to deposit mercury in the form of elemental metal on the cathode, and the mercury-poor solution is recovered.
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