Separation and conversion of fluoride salts in aluminum electrolysis flue gas by one-step ammonia purification

Abstract

The presence of multiple pollutants such as fluoride, SO₂, and CO₂ in aluminum electrolysis flue gas is harmful to the environment and human beings. The current research on aluminum electrolysis flue gas purification does not involve recovering carbon resources. We propose a one-step purification technology for aluminum electrolysis flue gas purification to address this problem. It is a resource conversion technology that integrates the purification of fluoride, SO₂, and CO₂ and converts the exhaust pollutants into cryolite and compound ammonia fertilizer. This paper studies an ammonium fluoride-containing absorption solution after one-step ammonia purification of aluminum electrolysis flue gas. It generates cryolites by adding NaOH and Al(OH)₃ for chemical precipitation. The optimal operating parameters were obtained by using a fluoride ion electrode, XRD and SEM analysis and detection, under the condition of temperature of 70 °C, stirring speed of 400 r/min, reactant concentration of 0.5 mol/L, and α_k (molecular ratio of NaOH to Al(OH)₃) of 3.1.

Keywords

aluminum electrolysis flue gas / cryolite / ammonium fluoride / one-step ammonia method / the conversion of fluoride salt

References

[1] Primary Aluminium Production Institute. Aluminium Institute [EB/OL]. [2019-04-21]. http://www.world-aluminium.org/statistics/primaryaluminium-production/.

[2] Mahecha-RivasJ C, Fuentes-OrdoñezE, EpeldeE, et al. . Aluminum extraction from a metallurgical industry sludge and its application as adsorbent [J]. Journal of Cleaner Production, 2021, 310: 127374

[3] LiuZ, LiW, MaW, et al. . Comparison of deep desulfurization methods in alumina production process [J]. Journal of Central South University, 2015, 22(10): 3745-3750

[4] DuJ, ZengP, LongH, et al. . The study on the new technology of exhaust gas cascade utilization from electrolytic aluminum industry [J]. Advanced Materials Research, 2014, 1010–1012891-894

[5] GheribiA E, PoncsákS, KissL, et al. . Experimental determination of the thermal diffusivity of α-cryolite up to 810 K and comparison with first principles predictions [J]. ACS Omega, 2017, 2(5): 2224-2230

[6] CaoA, GuoL, LiJ. High temperature corrosion of prebaked anode steel-structure for aluminium reduction [J]. IOP Conference Series: Materials Science and Engineering, 2018, 382: 022033

[7] OuzilleauP, GheribiA E, ChartrandP. Prediction of CO₂/CO formation from the (primary) anode process in aluminium electrolysis using an electrothermodynamic model (for coke crystallites) [J]. Electrochimica Acta, 2018, 259916-929

[8] GuoJ, GaoF, WangZ, et al. . Correlation analysis between emission and impact factors of greenhouse gases caused by production of primary aluminum [J]. Materials Science Forum, 2014, 787: 135-143

[9] HeX, KimH C, WallingtonT J, et al. . Cradle-to-gate greenhouse gas (GHG) burdens for aluminum and steel production and cradle-to-grave GHG benefits of vehicle lightweighting in China [J]. Resources, Conservation and Recycling, 2020, 152: 104497

[10] ZhangG, DengY, JinM. Analysis of sulfur dioxide emission reduction in electrolytic aluminium production [J]. Gansu Metallurgy, 2016, 38(6): 116-117(in Chinese)

[11] StrømmenS O, BjørnstadE, WeddeG. SO₂ emission control in the aluminium industry [J]. Essential Readings in Light Metals, 2013, 2962-967

[12] QiuZ. Metallurgy [M]. Volume 2: Non-ferrous metal metallurgy, 2001, Shenyang, Northeastern University Press: 4146(in Chinese)

[13] FanX, YuZ, GanM, et al. . Combustion behavior and influence mechanism of CO on iron ore sintering with flue gas recirculation [J]. Journal of Central South University, 2014, 21(6): 2391-2396

[14] LI Long. Comprehensive harnessing of smoke pollution of aluminum electrolysis [C]//The 8th Annual Meeting of the Nonferrous Metals Society of China. 2010: 577–579. (in Chinese)

[15] XieP, LiL, HeZ, et al. . Gas-liquid mass transfer of carbon dioxide capture by magnesium hydroxide slurry in a bubble column reactor [J]. Journal of Central South University, 2019, 26(6): 1592-1606

[16] SaevarsdottirG, KvandeH, WelchB J. Aluminum production in the times of climate change: The global challenge to reduce the carbon footprint and prevent carbon leakage [J]. JOM, 2020, 72(1): 296-308

[17] GuoJ, GaoF, WangZ, et al. . Correlation analysis between emission and impact factors of greenhouse gases caused by production of primary aluminum [J]. Materials Science Forum, 2014, 787: 135-143

[18] AbramsonM J, BenkeG P, CuiJ, et al. . Is potroom asthma due more to sulphur dioxide than fluoride? An inception cohort study in the Australian aluminium industry [J]. Occupational and Environmental Medicine, 2010, 67(10): 679-685

[19] SpinelliJ J, DemersP A, LeN D, et al. . Cancer risk in aluminum reduction plant workers (Canada) [J]. Cancer Causes & Control, 2006, 17(7): 939-948

[20] WangJ, KongF. Study analysis on purification of alumina electrolytic flue gas by bag filter [J]. Applied Mechanics and Materials, 2011, 130–134: 904-907

[21] KnizhnikA V, GrigorievV G, KlyuchantsevA B, et al. . Application of modern calculation methods to optimize a dry-type gas cleaning plant design [J]. Metallurgy and Materials Science, 2018, 22(3): 209-219(in Russian)

[22] DuJ, ZengP, LongH, et al. . The study on the new technology of exhaust gas cascade utilization from electrolytic aluminum industry [J]. Advanced Materials Research, 2014, 1010–1012: 891-894

[23] XiaoS, JiangY. Statistical research on effect of desulfurated parameters on desulfurization efficiency [J]. IOP Conference Series: Earth and Environmental Science, 2018, 146012070

[24] McintoshG J, AgbenyegahG E K, HylandM M, et al. . The pivotal role of alumina pore structure in HF capture and fluoride return in aluminum reduction [J]. JOM, 2016, 68(9): 2463-2471

[25] LIU Da-jun, WANG Jia-quan. Status analysis on aluminum industry in China and countermeasures of optimization development of environmental protection [J]. Light Metals, 2014(9): 9–13. DOI: https://doi.org/10.13662/j.cnki.qjs.2014.09.002. (in Chinese)

[26] CaoX, ZhangT, LiuY, et al. . Oxidation Macrokinetics of sulfite in the zinc-based wet flue gas desulfurization process [J]. Journal of Environmental Engineering, 2021, 147(2): 04020148

[27] WelchB J, KuschelG I. Crust and alumina powder dissolution in aluminum smelting electrolytes [J]. JOM, 2007, 59550-54

[28] WangX. Research progress of flue gas desulfurization technology for electrolytic aluminum [J]. World Nonferrous Metals, 2021, 574(10): 9-10(in Chinese)

[29] HUI Jing-ming, ZHANG Jing-dong, ZHANG Yi, et al. Application of ultra-low emission technology in desulfuration, defluorination and dedusting of aluminum flue gas [J]. Light Metals, 2020(1): 34–37. DOI: https://doi.org/10.13662/j.cnki.qjs.2020.01.007. (in Chinese)

[30] ZhaoQ, ZhuX, LvG, et al. . Calcification transformation of diasporic bauxite [J]. JOM, 2016, 68(6): 1711-1716