SO2 emissions has begun to cause serious problems in industrialized countries. Today, various methods are used for removal of SO2 gas. SO2 gas is an important raw material for production of sulfuric acid. However, SO2 content of flue gas must be over 6% to produce sulfuric acid commercially. Flue gases, which don't have enough amount of SO2 to produce sulfuric acid commercially are harmful to the environment and human health and they must be filtered. In this study, calcined dolomite was used to remove SO2 in flue gas which doesn't have enough SO2 to produce sulfuric acid but have high emission values. Pyrite was used as SO2 source and SO2 removal efficiency of dolomite was determined for different experimental parameters. SO2 capturing system was thermodynamically modeled and SO2 capturing efficiency was determined as 77.81% in the experiments

Açma, Ercan

Başlayıcı, Serkan

Buğdaycı, Mehmet

Turan,  Ahmet

Öncel, Levent

IOP Conference Series Materials Science and Engineering

English

İstanbul Medipol University Institutional Repository

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distributionof this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Published under licence by IOP Publishing LtdEKO Varna 2019IOP Conf. Series: Materials Science and Engineering 614 (2019) 012015IOP Publishingdoi:10.1088/1757-899X/614/1/0120151      Flue Gas Desulfurization by Using Calcined Dolomite S Baslayici1,2, M Bugdayci3, A Turan3, L Oncel4 and E Acma1 ¹Istanbul Technical University, Faculty of Chemistry and Metallurgy, Metallurgical and Materials Eng. Dep., 34469, Istanbul ²Istanbul Medipol University, Vocational School, Construction Technology Dep., 34810, Istanbul, Turkey 3Yalova University, Chemical and Process Engineering Department, Yalova, 77100, Turkey 4Sinop University, Faculty of Engineering and Architecture, Department of Metallurgical and Materials Engineering, 57000, Sinop, Turkey  Abstract. SO2 emissions has begun to cause serious problems in industrialized countries. Today, various methods are used for removal of SO2 gas. SO2 gas is an important raw material for production of sulfuric acid. However, SO2 content of flue gas must be over 6% to produce sulfuric acid commercially. Flue gases, which don’t have enough amount of SO2 to produce sulfuric acid commercially are harmful to the environment and human health and they must be filtered. In this study, calcined dolomite was used to remove SO2 in flue gas which doesn’t have enough SO2 to produce sulfuric acid but have high emission values. Pyrite was used as SO2 source and SO2 removal efficiency of dolomite was determined for different experimental parameters. SO2 capturing system was thermodynamically modeled and SO2 capturing efficiency was determined as 77.81% in the experiments. 1. Introduction The increasing population of the world and industrialization leads to an increase in energy needs. Use of fuels with sulfur content has been increasing to meet the rising energy demand. Emission of air-pollutant gases has been rising for that reason [1].  Sulfur dioxide (SO2) is known as the most important air-pollutant gas. Main reasons that causes arising of SO2 are natural sources and human activities. Microbial activities, volcanic eruptions, combustion of sulfur-containing fossil fuels, molten sulfur ores and oil refineries are among the causes of SO2 formation. [2-6]. SO2 is highly soluble in water and SO2 in flue gas is used as raw material in sulfuric acid production. On the other hand, SO2 content of flue gas must be over 6% to produce sulfuric acid commercially. It is necessary to filter the flue gases containing SO2 which do not have enough SO2 amount for production of sulfuric acid commercially. It may cause serious irreversible damage if they are released directly into the nature. [7-11]. SO2 gas pollutes the nature and it also increases the risk for cardiovascular diseases and lung cancer [12-14]. Sulfur dioxide is a colorless, sour-scented, fireproof and stifling gas. Taste of SO2 can be detected when its concentration reaches to 785 µgr/m3 and SO2’s smell can be detected when its concentration reaches to 1305 µgr/m3 in the atmosphere. Sulfur dioxide is present in volcanic gases and its level is high in industrialized regions. SO2 is formed with combustion of sulfur-containing coals. This gas is condensed as a colorless liquid when cooled to -10 °C and it is solidified in white crystalline form when cooled to -73 oC [1, 15]. EKO Varna 2019IOP Conf. Series: Materials Science and Engineering 614 (2019) 012015IOP Publishingdoi:10.1088/1757-899X/614/1/0120152      Reseapollutantindustryare obtaiIn other these proMainin Turkestudies w2. ExperIn the excomposi1.   Mine((H3O)Fconcentrsphaleritparticle sCalciprocuredshown in SampleDolomitSPrchers have gases like s, gas-liquid ned by usinsituations, ccesses prod inorganic soy, dolomiteere comparimental perimental stion of pyritralogical exe3(SO4)2(OHate was pyre, digenite ize of pyritened dolomit from Kum Table 2. Ca Loss e ample yrite 3 been workiulfur dioxidreactions ang activated catalysts (genuce SO2 gas rbent used  is used as ed to the pretudies, pyrite ore is giveTFaminations )6) mineralsite and therand various was 41 µme used in eas Magnezilcined dolomTon Ignition 9.52 Fe,% 8,18 4ng on devele (SO2), nitrd gas-solid rarbon and lerally vanadas by producin this proceinorganic sovious literatue ore from Kn in Table 1able 1. Chemigure 1. XRshow that  were prese were trac silica min. xperimentalt Sanayi Coite’s mean able 2. ChemCaO% 57.59 S% C1,67 0oping cost-eogen oxide (eactions areiquid alkali ium pentoxit [19]. ss is calcite rbent in thire, where cure region  and XRD aical compoD analysis pyrite (FeSent in the e amount oerals. Acoo studies warporation. Cgrain size wical analysMgO% 31.00 u% M,58 0,ffective sysNOX) and c used for dematerials (lide) are usedbut in order s study. Resalcite and acof Turkey wnalysis resulsition of pyrof Pyrite ore2), quartz pyrite concf chalcopyrirding to pas Kutahya hemical anas 42 µm. is of dolomitFeO% 0.12 g% Ca38 0,7tems for decarbon monoxsulfurizing.me slurry an to turn SO2 to utilize larults obtainetive carbon aas used as St of pyrite oite . (SiO2) and entrate. Maite, covellinerticle size mYaylababa alysis of Yae. Al2O3% Trace % SiO27 9,3reasing levide (CO) [1 Gas-liquid d ammoniainto sulfuricge dolomited from expere used. O2 source. Cre is shown hydroniumn mineral , marcasiteeasuremendolomite anylababa doSiO2% N1.07 % K%3 0,02els of air 6-18]. In reactions ) [1, 17].  acid but  reserves rimental hemical in Figure   jarosite of pyrite , bornite, ts, mean d it was lomite is a2O% 0.0086   EKO Varna 2019IOP Conf. Series: Materials Science and Engineering 614 (2019) 012015IOP Publishingdoi:10.1088/1757-899X/614/1/0120153       Thermo Scientific XSeries 2 ICP-MS was used for chemical analyses of the samples. Bruker D8 Advance was employed for XRD analyses and mineralogical examinations. Roasting operation were carried out in a tube furnace working with 220V electricity. Samples were grinded with ring mill and dehumidified in Binder drying-oven. Samples particle size were measured with Malvern Mastersizer 2000.  In the roasting experiments, ceramic boat was weighed initially and it was weighed again after filling with pyrite. Pyrite was roasted in furnace and weight loss caused by roasting was measured by weighing. Roasting process was carried out with different times and optimum roasting time was determined. Various air flow rates were used in SO2 capturing experiments. SO2 emissions were measured after roasting process for every air flow rate used. SO2 emission measurements after roasting process were repeated for different flow rates with using dolomite for capturing SO2 gas. Then, SO2 capturing results were compared.  Titrimetric method was used in SO2 analysis. In this method, gases released from the flue were kept in the hydrogen peroxide solution which was in the washing bottle and it was converted to sulfuric acid. Concentration of SO2 was determined by titration with a base with a known normality. 100 ml. of a 1% H2O2 solution was filled in each of the two gas washing bottles, which were coupled in series. Gas exited from the flue was transferred to first gas washing bottle. SOX was oxidized to acid by H2O2 in the washing bottle. SOX gas, which didn’t react in the first washing bottle moved to second washing bottle and reacted with H2O2. After the process was completed, solutions in two washing bottles were titrated with alkali (1N Na2CO3) and equivalent SO2 quantity in the flue gas was determined. Reactions took place in this process are given in Equation 1 and Equation 2. SO2+ H2O2  SO3+H2O                                        (1)    SO3+ H2O  H2SO4            (2) Total reaction is shown in equation 3. SO2+ H2O2 H2SO4                                 (3)   Acid’s titration reaction is given in Equation 4. H2SO4+ Na2CO3  Na2SO4+H2CO3                               (4) SO2 concentration in the gas mass is calculated as shown in Equation 5. Here, N is normality of the base and S is base consumption (ml). SO2 (mg/l) = (32. NNa2CO3. SNa2CO3) / volume of air (l)                                              (5) SO2 capturing experiments were started after determining the roasting conditions in the first experimental set. Calcined dolomite was used to capture SO2 in this experimental set. Different air flow rates were used in SO2 capturing experiments. Initially, SO2 formation amounts were determined for every air flow rate used. Then, dolomite was used to capture SO2, and capturing efficiencies were compared. The amount of dolomite was determined by weighing the empty boat and then weighing the boat filled with dolomite. The resulting products were weighed and compared with roasting experiments’ results.  3.Results and Discussion In the experimental studies, quantity of theoretical air requirement for roasting of pyrite was calculated initially. Studies were carried out with two times, four times, six times and eight times of the theoretical air quantity. According to Equation 6; in order to obtain 0.0651 mole S, 0.31 mole of air is required. Table 3 represents roasting experiments’ conditions. S + O2 SO2                                   (6) EKO Varna 2019IOP Conf. Series: Materials Science and Engineering 614 (2019) 012015IOP Publishingdoi:10.1088/1757-899X/614/1/0120154      Exp. No1 2 3 Avg.154 5 6 Avg. 307 8 9 Avg. 4510 11 12 Avg. 60 Expecalculatequantity with fouprocess wFigurSO2% wSO2% am2 shows flow rate Duration(min.)  15   30   45   60  riments werd. Roasting was not enor times of thas not necee 2 shows eas increasedount remaithat optimu. Ta Flow Ra(l./min       1 e repeated experimentsugh to compe theoreticassary. ffect of roas exponentialned nearly cm roasting cFigurble 3. Roastite .) WeigRoathree times showed thalete the roal air quantitting time only when roaonstant wheonditions ofe 2. Change  ng experimeht Before sting (g.) 5.79 5.78 5.30 5.62 5.34 5.25 5.33 5.30 5.17 5.32 5.31 5.26 5.34 5.29 5.17 5.26  for all roat 1 l./min. asting procesy used and  SO2% formsting time wn roasting ti pyrite is 30 of SO2% amnts’ conditioWeight AfRoasting (3.93 3.93 3.60 3.82 3.44 3.39 3.43 3.42 3.34 3.43 3.42 3.39 3.44 3.41 3.33 3.39 sting condiir flow rate s. Roasting eit was deteration. It is as increasedme exceede minutes of ount versusns. ter g.) Differ(g.1.81.81.71.81.81.81.91.81.81.81.81.81.81.81.81.8tions and aand 2 times fficiency wamined that useen in the f from 15 md 30 minutesroasting tim time. ence ) SO2 A(m6 35 30 30 39 36 30 38 33 38 38 36 39 37 33 36 3verage valuof the theors increasedsing more igure that ainutes to 30. Table 3 ane and 1 l./m mount g./l.) 2.15 2.08 2.10 2.11 5.52 5.47 5.68 5.55 5.44 5.36 5.47 5.42 5.53 5.45 5.50 5.49 es were etical air  to 100% air in the mount of minutes. d Figure in. of air EKO Varna 2019IOP Conf. Series: Materials Science and Engineering 614 (2019) 012015IOP Publishingdoi:10.1088/1757-899X/614/1/0120155      After6.2 databwith temTwo and doloSO2 captin Table In SObetween occurrinThereforcapturingEffecwith concapturingdoesn’t pcapturingAccordinwill showWhenaverage al. obtaiTurkey mdolomitecapturedusing do roasting exase. Figureperature. FigFigure 3. Stboats were umite was churing experi4 is shared i2 capturingsolid and gg of reactioe, flue gas  result was t of temperastant air fl efficiency.rovide info efficiency g to these d insignifica all results emission valned 82% Sake dolom can be con by using calomite insteaperiments, S 3 illustratesure 3 showsandard free sed in SO2 carged in thements. SO2 n Figure 4.   experimentas is increans remain sdesulfurizatobtained as ture on SO2 ow rate. Re On the othrmation aboincreased inata, flue gant changes dare taken inues lower thO2 capturingite a good averted into lcite but regd of calcite O2 capturin standard fr that dolomienergy of doapturing exp second boatcapturing ams, better ressed at low aame but coion efficien77.76% whecapturing efsults showeer hand, higut low tempsignificantls desulfurizaue to the nato consideran 1285µg p efficiency lternative tosulfuric acieneration ois advantageg system wee energy ote will be sulomite-pyriteriments. P. Table 4 prount versusults were oir flow ratentact time cy increasen 0.4 l. /minficiency wad that temph temperatueratures likey from 77.7tion efficienrrow temperation, filterier hour, 48by using a active carbd [20]. Matf captured Sous [21].    as thermodyf dolomite alphated and e system chayrite concenesents exper time curve,btained at ls. Contact sis increaseds at low air. air flow rats investigateerature didres were use room temp6% to 77.8cies of the ature range ong with dol5 µg per dayctive carbonon.  In this hieu et al.’sO2 is not ponamically mnd pyrite copyrite will bnging with trate was chaimental para which was ow air flowurface area,  with using flow ratese was used. d by using dn’t have a d in experimerature. Figu1% with inccompanies uf the flue gaomite is sui and 214 µg but large study, SO2 w study showssible in thiodeled via ncentrates e oxidized a temperaturerged in the meters and created by u rates. Conwhich is ne low air flo. The optim ifferent temsignificant eental studire 4 shows reasing temsing sulphuses. table for pla per year. Mdolomite rehich is caped that SOs method. TFactSage changing t 600 ºC. . first boat results of sing data tact time eded for w rates. um SO2 peratures ffect on es and it that SO2 perature. rous fuel nts with angun et serves in tured by 2 can be herefore, EKO Varna 2019IOP Conf. Series: Materials Science and Engineering 614 (2019) 012015IOP Publishingdoi:10.1088/1757-899X/614/1/0120156           Table 4. Conditions and results of SO2 capturing experiments. Exp. No Temperature, ºC Flow Rate, lit./min Weight Before Roasting, g. Weight After Roasting, g. SO2 Amount, mg./lt. SO2 Capture, % 1                        600                         1.0 1.07  0.68  25.60    -   2 1.07  0.69  26.67  -   3 1.09  0.70  25.60  - Avg. 1.07  0.69  25.95  -       4                        600                         1.0 1.00  0.64  7.46  71.25       5 1.21  0.77  7.46  71.25       6 0.99 0.64  6.93  73.29    Avg. 1.06 0.68  7.28  71.93 7                        600                         0.8 1.06  0.68  33.33  - 8 1.15  0.73  33.33  - 9 1.05  0.68  32.67  - Avg. 1.08  0.69  33.11  - 10                        600                         0.8 1.07  0.69  8.67      73.81 11 1.09  0.70  8.67      73.81 12 1.02  0.66  9.33  71.82 Avg. 1.06  0.68  8.89  73.14 13                        600                         0.6 1.16 0.75 44.44 - 14 1.04 0.66 44.89 - 15 1.10 0.71 44.89 - Avg. 1.10 0.70 44.59 - 16                        600                         0.6 1.10 0.71 10.67 76.15 17 1.00 0.64 11.11 75.16 18 1.02 0.65 10.22 77.15 Avg. 1.04 0.66 10.66 76.15 19                        600                         0.4 1.06 0.68 64.00 - 20 1.12 0.71 64.00 - 21 1.01 0.65 64.00 - Avg. 1.06 0.68 64.00 - 22                        600                         0.4 1.02 0.67 14.67 77.07 23 1.11 0.70 14.67 77.07 24 0.99 0.63 13.34 79.15 Avg. 1.04 0.66 14.22 77.76 25                        700                         0.4 1.05 0.67 64.00 - 26 1.05 0.68 61.34 - 27 1.05 0.68 64.00 - Avg. 1.05 0.67 63.11 - 28                        700                         0.4 1.09 0.70 14.67 76.75 29 1.11 0.68 13.67 78.34 30 1.03 0.66 13.67 78.34 Avg. 1.07 0.68 14.00 77.81 EKO Varna 2019IOP Conf. Series: Materials Science and Engineering 614 (2019) 012015IOP Publishingdoi:10.1088/1757-899X/614/1/0120157      4.ConcluThe worindustrieemissiondevelopeterm. Becauenough authoritiIn exThen, thExperimRoastquantity times ofconditionthe theorIn thconditionflow rate5. Refer[1] Ba[2] Li[3] Fo[4] Hu[5] Li[6] MFiguresion ld’s energy s. High SO values ared countries.se of the haamount of es must be fperimental ermodynamients showeding conditiorequired wa the theorets vary accoetical amoune experimens. Howevers. ences slayici S 2Istanbul Te N, Wang Z wler D and  K, Bai G, L P, Wang XRes 18 (7) ajernik O an 4. Effect ofrequirement2 emissions  high in Tu SO2 emissirmful effectSO2 to proiltered. studies, minc calculation how theoretns of pyrits calculatedical air quanrding to the t of air. ts, SO2 cap, it is predic014, Flue chnical Univand Zhang ZUnsworth Mi W, Yan H, Allinson G1090-1097. d Mansfield temperature has been incaused by rkey and iton values ofs of SO2 gasduce sulfurieralogical as were carriical calculate concentra theoreticalltity was encontent of thturing efficted that effGas Desulpersity, Turk 2018, Envi H 1977, Qu, Hu, Li L a, Li X, Stag T A 1970, N and air flowcreasing beuse of fuels continues  Turkey sho on nature anc acid comnalysis of Yed out and iions were wte were dety and determough and the concentraiency of doiciency valuhurization bey. ron Sci Pollart. J. R. Mnd Zhang H nitti F, Murature 227 3 rate on SOcause of the with sulfuto increase uld be reducd human hemercially baylababa dt was seen thorking in praermined byined in praere was no te and it canlomite was e may decrey Using Cut Res 25 (3et. SOC 1052014, Plant ray F and X77-378.  2 capturing a developmer content mdespite the ed in the shalth, flue gaut above tholomite wasat dolomite ctice.  experimentctice. It wasneed to use be specifiedreached to ase in smallalcined Dol5) 35099-35 767-783. Growth Regiong X 201mount. nt in technoust be redudownward ort term andses which de limits se performed can capture s. The opti seen that u more air. O as two to fo77.76% at  amounts atomite, MSc108. ul 75 (1)  271, Environ S logy and ced. SO2 trend in  the long on’t have t by the initially. SO2 gas. mum air sing four ptimum ur times optimum  high air  Thesis, 1-280. ci Pollut    EKO Varna 2019IOP Conf. 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Flue gas desulfurization by using calcined dolomite

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Flue gas desulfurization by using calcined dolomite

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