Method for separating and removing heavy-metal thallium from sintering flue gas desulfurization wastewater of ferrous metallurgy by emulsion liquid membrane

Abstract

The invention discloses a method for separating and removing heavy-metal thallium from sintering flue gas desulfurization wastewater of ferrous metallurgy by an emulsion liquid membrane. The method comprises the steps of firstly, preparing the emulsion liquid membrane prepared from a solvent, a surfactant, a carrier, membrane auxiliaries, an internal-phase solution and the like, then, enabling the sintering flue gas desulfurization thallium-containing wastewater to be in contact with the emulsion liquid membrane for mass transfer, then, carrying out natural settlement separating, discharging obtained wastewater after reaching standards, subjecting an emulsion phase to demulsifying treatment, recycling an obtained oil phase to the preparation of the emulsion liquid membrane, subjecting an obtained aqueous phase to retreatment by methods such as chemical precipitation and salting-out, then, returning a small volume of wastewater to a sintering flue gas desulfurization system for cyclic utilization, and subjecting obtained solids to dangerous waste treatment and disposal. According to the method, heavy-metal pollutants in the sintering flue gas desulfurization wastewater of ferrous metallurgy are removed and treated by using an emulsion liquid membrane separation technology, the removal effect is good, and particularly the removal rate of thallium is close to 100%; and the method has the characteristics of simple process and equipment, convenience in operation, low cost and energy consumption, and the like and has a good industrial application value.

Description

technical field [0001] The invention relates to the technical field of water treatment, in particular to a method for removing heavy metal thallium in iron and steel metallurgy sintering flue gas desulfurization wastewater by using emulsion liquid membrane separation. Background technique [0002] In the iron and steel metallurgical production process, because some iron ores contain traces or traces of thallium (Tl) compounds, when the iron ores are sintered at high temperature, these thallium-containing compounds will be accompanied by high-temperature flue gas due to gasification or sublimation. Together into the sintering flue gas desulfurization system. Although the relatively mature and widely used sintering flue gas limestone-gypsum wet desulfurization process has a certain precipitation and removal effect on these thallium-containing compounds, due to the ion balance limitation of the precipitation reaction itself (that is, the solubility product limitation of chemica...

AI Technical Summary

Problems solved by technology

Among them: precipitation or strong oxidation coagulation precipitation method is to generate TlOH or Tl from monovalent thallium that exists stably in wastewater under alkaline conditions. 2 S precipitates, or oxidizes monovalent thallium to unstable trivalent thallium, and then makes it generate Tl(OH) under alkaline conditions 3 and Tl 2 o 3 Precipitation, the process mainly includes pH adjustment, strong oxidation, coagulation / flocculation and other steps, the treatment process is cumbersome, time-consuming, and consumes a lot of chemicals. At the same time, the trivalent thallium formed by the oxidation method is more toxic and poor in stability, making this It is difficult for the technology to be widely used in industry; although the ion exchange method is recommended by the U.S. Environmental Protection Agency as one of the treatment methods for thallium-polluted water bodies, it is due to the high concentration of Na in the sintering flue gas desulfurization wastewater. + 、K + , Ca 2+ , Mg 2+ cations, so that the resin has a poor selective competitive exchange ability for trace Tl ions. At the same time, due to the small adsorption exchange equilibrium / saturation capacity of the resin, its removal efficiency is low, and Tl ions in the treated wastewater are difficult to reach the standard, and wastewater treatment The cost is high; although the adsorption method has the advantages of simple process and convenient operation, but the amount of adsorbent is large, the regeneration is troublesome, the treatment effect is not ideal and the cost is high; the salting-out method is to add a large amount of NaCl to the wastewater. where Tl + Removed by precipitation in the form of TlCl

However, the large-scale use of NaCl will increase the salinity and corrosiveness of wastewater, and at the same time, it is difficult to recycle or reuse wastewater with high salinity.

Images