Effects of additives on stabilization and inhibition of mercury re-emission in simulated wet gas desulphurization slurry

In view of the problem of mercury re-emission in wet flue gas desulfurization system, Na₂S, 2, 4, 6-trimercaptotiazine trisodium (TMT-18), sodium dithiocarbamate (DTCR-2) and Fenton reagents were added into the desulfurization slurry to study their effects on mercury re-emission. The results show that the 4 additives could effectively inhibit the mercury re-emission. 1.0 time stoichiometric ratio of Na₂S is enough to combine with Hg²⁺ in the slurry into HgS. Thereby the ratio of mercury re-emission reduces to 5.27%. The optimum dosage of heavy metal chelating agents TMT-18 and DTCR-2 are 3.0 and 1.0 time stoichiometric ratio. They combine with Hg²⁺ to form organic chelate mercury and then fix it. So the ratio of mercury re-emission reduces to 5.09% and 4.62%, respectively. After adding Fenton reagent with a strong oxidizing into the slurry, the ratio of reduced mercury reduces to only 2.31% when H₂O₂ concentration is 0.3 mol/L and the ratio ofFe²⁺/H₂O₂ is 1:8. Fenton reagent has the best effect on mercury re-emission in the simulated wet gas desulphurization slurry among 4 additives.