Efficient Removal of SO₂ from Flue Gas with Phosphate Rock Slurry and Investigation of Reaction Mechanism

Abstract

Wet flue gas desulfurization is now a widely used method for SO 2 abatement, but an efficient adsorbent with low cost is recognized as being an important prerequisite for its industrial application. Herein, wet flue gas phosphate rock desulfurization technology is reported to eliminate SO 2 from phosphorus chemical processes, and the technology has been employed in industrial application successfully. Because phosphate rock was chosen as the raw material from the phosphorus chemical process, its application can reduce the desulfurization cost. In addition, the produced sulfuric acid in the present desulfurization system can provide replacement of sulfuric acid required in typical phosphorus chemical activity. Accordingly, this desulfurization technology is of environmental and economic importance and also exhibits potential in treating other industrial SO 2 pollution processes. Characterizations of the fresh and spent phosphate rock samples as well as analysis of the spent solution were conducted. Subsequently, the reaction processes, the desulfurization mechanism, and the deactivation of the phosphate rock adsorbent were proposed.

Mutual promotion effect of SO2 and NOx during yellow phosphorus and phosphate rock slurry adsorption process

“…It can be observed from Figure S5A that the CaMg(CO 3 ) 2 gradually disappears as the reaction time increases due to its better reactivity 22 . The SO 2 was absorbed to form CaSO 4 •2H 2 O that was detected in the spent phosphate rock, which is consistent with our previous results 21‐23 . The NO is oxidized to high valence nitrogen oxides (NO 2 and N 2 O 5 ) with ozone induced by yellow phosphorus, and then dissolved in the slurry to form nitrite and nitrate.…”

“…Especially for NOx, the removal efficiency is significantly enhanced. In general, higher pH value can obtain greater absorption capacity of SO 2 and NOx, which has been proved in our previous works 20,21 . Thus, the pH value of absorption solution along the absorption time was determined, and the result is demonstrated in Figure 2D.…”

Simultaneous NOx and SO2 removal during wet flue gas desulfurization, using copper smelter slag slurry combined with yellow phorphorus

“…In recent years, a great many industrial waste solids, such as red mud, [ 7 ] fly ash, [ 8 ] and steel slag [ 9 ] were used as alternative wet absorbents for the simultaneous removal of SO 2 and NO x due to slags containing free‐CaO and free‐MgO leading to alkaline in aqueous solution. [ 7,9,10 ] Compared to traditional WFGD technology in SO 2 and NO x removal, the slag slurry methods have several merits, such as using slags produced from smelting plants as a desulphurizing agent (versus purchasing a desulphurizing agent), without production of gypsum, [ 4 ] high‐added‐value by‐products such as MnSO 4 · H 2 O, and low investment. [ 3,11,12 ] Hence, this improved WFGD method (the slag slurry method) can be effectively applied to purifying low‐concentration SO 2 and NO x from acid‐making tail gas.…”

Leaching of iron from copper tailings by sulfuric acid: behavior, kinetics and mechanism

“…The absorption peaks at around 1640 cm −1 are ascribed to O–H bending vibrations, peaks at around 1097 cm −1 correspond to the symmetrical stretching vibrations of Si–O–Si, and peaks at about 798 and 467 cm −1 correspond to the symmetrical stretching vibrations of Si–O. 38,39 After leaching, the intensity of the Si–O stretching vibration peak slightly weakened, while the other main peaks remained almost identical. This is consistent with the dissolution of Fe 2 SiO 4 , while the other main structures of the copper tailings were stable during the leaching.…”