Effect and influence factors of sulfur removal in coal with fungus

Vol, 12 Suppl. 1J. CENT. SOUTH UNIV. TECHNOL.Oct.2005Article d:1005-9784(2005)S1-0098-04Effect and influence factors of sulfur removal in coal with fungusHE De-wenc何德文), JIN Yan(金艳), CHAl Li-yuan(柴立元),JANG Rui(黄锐), PENG Bing(彭兵), WANG Yun-yan(王云燕)( College of Metallurgical Science and EngineeringCentral South University, Changsha 410083, ChinaAbstract: The influence of coal desulfurization by fungus was experimentally studied. The results suggest that fun-gus can effectively remove inorganic and organic sulfur in coal, and main influences of desulfurization by fungus ofpH value, temperature, coal slurry concentration and coal granularity were studied by orthodox experiment and theoptimal experimental conditions are/as follows: ph value 6, temperature 45 C, coal slurry concentration 10% andcoal granularity 100 um. Under above conditions, fungus can remove up to 44. 96% total sulfur and 54. 87% inor-ganic sulfur within two days, and their desulfurization rates will increase along with time. Compared with sulfolo-bas, desulphurization by fungus is steady and more effective, and has advantage of high speedKey words: fungus: desulfurization; coal; orthodox experimentCLC number: X7013Document code: A1 INTRODUCTION2 EXPERIMENTALHigh sulfur coal, which lets out poisonous 2.1 Experimental bacteriumand harmful gaalfur dioxide in theThe experimental original bacterium, pickedprocess of coal combustion, is a main factor to form punk wood, was enriched and brought up inform great area acid rain and occupies one third of culture medium, and then was separated to obtainreserves of total coal in China[i]. People has paid fungus. Subsequently the bacterium mycelium wasmuch attention to serious environment pollution made for the next experiment by purification andmade by sulfur in coal and searched for a speed, breeded in relative culture medium.low-cost and effective technology of desulphurizetion,which has become a significant environment 2.2 Coal samples preparationprotection task nowadays aCoal samples, picked from Chongqing areaoal desulfurization can be sorted into fore- were high sulfur coal with 2. 45% total sulfurburning, aflame-burning and after-burning by 1. 87% inorganic sulfur and 0. 58%organic sulfurburning processl3-53. and also sorted into physics, and were crashed and screened out into differentchemistry and biology method by different meascoal powders of 60, 100 and 160 umuresL6-9. Of all desulfurization methods, fore-burning desulfurization by microorganism, which 2.3 Desulfurization conditionscan remove sulfur in coal accompanied by oxida- 2. 3. 1 Soaking by rocking bottletion-reduction reaction at normal temperature andAbove coal powders were gotten and made intopressure, has more notable advantages of usin100 mL coal slurry in 250 mL triangle flask, and thenless energy, fewer operational cost. So researches cultivated bacterium was filtrated through 0. 2 um filmon coal desulfurization by microorganism drand throwed into coal slurry. The triangle flask wascholars more attention all over the world(. 11], placed into SHZ-88 model water-bathing vibrator tolow sulfolobus were used to remove sulfur and its breed microorganism under the condition with differentdesulfurization rate would be lower( 12)temperatures and rotating speed of 120 r/min. To aThe factors of desulfurby furnrus arevoid water vapor, distilled water was added at intervaltime to keep coal slurry to be 100 mlcould provide any guidance of key technology prob- 2. 3. 2 Post-treatment of coal sampleslem and industrialization experiment feasibilityCoal samples to be desulfurizated by microbe中国煤化工CNMHGo Foundation item: Project(2002AA649220) supported by Hitech Research and Development Programe: project( 1667)supported by the10: Accepted date: 2005-07-10Correspondence: HE De-wen, Associate Professor, PhD; Tel: +86-731-8830875: E-mail hedewen@mail, csu, edu.enHE De-wen, et al: Effect and influence factors of sulfur removal in coal with funguswere soaked with 4 mol/L hydrochloric acid after Fig 3 and Fig. 4 show that, coal desulphurizationcentrifugal separature. Super clear liquid was dis- is certainly affected by coal granularity and coalarded, and deposits was washed to neuter by dis- slurry concentration, and desulphurization rate oftilled water and dried at 70-100 C for analysis.total sulfur obviously ascends with small coal granularity and coal slurry concentration. But with ex-2. 4 Analysis methodscessive decrease of coal granularity(60 um), desulTotal sulfur in coal was determined by oxida- phurization rate of total sulfur and inorganic sulfurtion-reduction method, and inorganic sulfur was would fall compared with that of 100 um. The readetermined by colorimetry method. The amount of son is that microorganisms lie in coal slurry withorganic sulfur having complex and less component, two ways of adsorption and dissociation, and adequals to the difference between total sulfur and in- sorptive microorganism has more effective desulorganic sulfur[i3]phurization than dissociative microorganism be-cause there are much more adsorptive microorgan3 RESULTS AND DISCUSSIONisms on greater exterior area with finer coal granu-larity. While coal granularity is too fine, unit3. 1 Influencing factors of desulfuration by fungus amounts of bacterium on surface area would de3. 1. 1 Influence of pH value and temperaturecreasedesulphurization rate would fall. On thewhen keeping 10 coal slurry and 100 um coal otherdesulphurization rate would decreasegranularity, Fig. 1 and Fig. 2 show that, fungus with high coal slurry concentrationhave good effects of desulfuration under the condi- fewer microorganism amounton of ph=6 and 45 C because fungus activitywill augment alone with temperature, but too hightemperature will harm microbe. On the otherhand, acid medium would be brought out on theprocess of fungus biodegradation, so high ph value makes for rate of desulfuration i4. Its biodegradation equation4FeS2+15O2+2H2O=2Fe2(SO4)3+2H2SO4一 Total sulfur3. 1. 2 Influence of coal slurry and granularityKeeping pH-6 and temperature at 45CCoal slurry/%Fig 3 Influence of coal slurryon desulfuration.-Inorag anic snFig 1 Influence of pH value on desulfuration二 Total sulfurInorganic sulfurCoal granularity/umFig 4 Influence of coal granularity中国煤化工CN MHGfluencing factorsConsidering vanous kinds of factors, orthodoxexperiment table is designed according to four fac-tors at three level of Lg(3 ), which is listed in TaFig2 Influence of temperature on desulfuration ble 1 and Table 2Journal CSUT Vol 12 Suppl. 1 2005Table 1 Orthodox experiment factor tabletion. The optimum conditions of removing totalr are afollows: pH value 6, temperature 45Level Coal slurryC, coal granularity 150 um and coal slurry concen-concentration/ granularity/ pH emperature/tration 10%. At two levels of 150 and 100 um coalgranularity, there are almost no differences. Sothe optimum coal granularity is adopted to be 10015um for less cost.According to Table 4, all kinds of faremoving inorganic sulfur are ordered as ph valuetemperature or coal granularity, coal shurry conThe orthodox experiment results of desulfu- centration. The optimum conditions of removingrization are listed in Table 2. Fungus can effective- inorganic sulfur are as follows: pH value 6,temly remove total sulfur and inorganic sulfur, and themaximum desulfurization rate can reach 48. 53% perature 45C, coal granularity 100 um and 15%coal slurry concentration. At two levels of 15%and 41. 36% respectively. Desulphurization rates and 10%nd 10% coal slurry concentration, there are al-are influenced by many kinds of factors. Under the most no differences, So optimum experiment consame condition, removing rate of total sulfur is dition 10% coal slurry concentration is adoptedbetter than that of inorganic sulfur because fungushas good adaptability to organic sulfur.According to analytical method of orthodox 3.3 Effects of desulphurization by fungus alongexperiment, the data of total sulfur in Table 2 areUnder above optimal experimental condit4. where k,, k,, k, stand for correlative coeffi- keeping pH value 6, temperature 45C, coal slurrycients of four factorsconcentration 10%and coal granularity 100 umIn Table 3, all kinds of factors of removing tefects of desulphurization by fungus along withtal sulfur are ordered in turn as pH value, temper- time are studied and experimental results are listedature,coal granularity and coal slurry concentrain Table 5Table2 Removing rate of total sulfur and inorganic sulfur by fungusCoal slurryTemperature/concentration/%18.234544.58604532.898838.786048.4939.9334.87Table 3 Optimum qualification of total sulfurIndexCoal slurry concentration/%Coal granularity/pmTemperature/℃40.5847.3245.09Table 4 Optimum qualification of inorganic sulfurIndexCoal slurry concentration/%Coal granularity/中国煤化工 Temperature/tkCNMHG49.9645.8.112.39HE De-wen, et al: Effect and influence factors of sulfur removal in coal with fungusTable 5 Effects of desulphurizationmay remove more sulfur in coal within two daysby fungus along with timeand their desulfurization rates will increase alongTime/d Removal rate ofRemoval rate ofwith time. Compared with other microorganisms,inorganic sulfur/%desulphurization by fungus is steady and more ef-fective, and has advantage of high speed.15.8419.47124643.7554.84REFERENCE4555.7746.6457.12[1] CHEN Peng. Characteristics and distribution of sulfurin Chinese coals and desulfurization [J]. Coal Conversion, 1994, 17(2):1-9. ( in Chinese)Table 5 shows that, fungus can effectively re- [2] Karavaiko G I, Lobyreva L B. An overview of the bac-move sulfur in coal up to 43. 75% total sulfur andteria and archaea involved in removal of54.84% inorganic sulfur within two days, andorganic sulfur compounds from coal[J]. Fuel Process1994,40(2):167-182their desulfurization rate will increase along with [3] Garoia F. Blazquez M L. A comparative study of thetime. On account of benefit and feasibility of in-biodesulfurization of two spanish coals with thiobaciI-dustry application, two day are chosen for fungulus and sulfolobus]. 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(in Chinese/dustry in China. 1996,(6):342)The desulfurization effects by fungus areinfluenced by pH value, temperature, coal slurryPENG Chang-hong, WANG Yun-yan,timum condition of desulfurization by fungus is pHMLence factors on desulfurization of coal byvalue 6, 45C, 10% coal slurry, and 100 um coal中国煤化工 ral South University ofgranularity.C N MH Gted by YaNG Bing)3)Compared with other microbes, fungus