Preparation of Portland cement with sugar filter mud as lime-based raw material

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  • ga

    a

    Unighai

    wal. Buingthe3S f

    amount can raise the compressive strength, cut down the setting time, and promote the cement hy-dration in the initial and acceleration period. Excessive FM will lead to the decrease of compressive

    the ingy prossing ents succe et a

    reasonable technology or approach, it may be changed valuable

    pollutes the air, landll pollutes the underground water. Althoughit is fairly rich in inorganic and organic nutrients (Yaduvanshi andYadav, 1990), it nds that little is used to produce agriculture fer-tilizer (Elsayed et al., 2008). The major reason for this is the

    et al. (2008) state FM can be used as raw material to produce thec value will not bee been many ap-still have varioussugar (in 2011) isalso is dischargedhappened becauseosal. It is pressingis method should

    be the better one, and the sugar industry and environment all canbe developed sustainably.

    In recent years, sustainable development and natural resourcesreservation have become global issues (Sabine, 2013). The cementindustry, which is known as one of the important consumptiveindustry for rawmaterial and energy, has integrated these issues toits development policy (Schneider et al., 2011). Many industrial SWare reused to replace the traditional materials or fuel in the pro-duction process (Li et al., 2012; Rodriguez et al., 2013). Alternative

    * Corresponding authors. Fax: 86 21 69584723.E-mail addresses: bosomxin@126.com (H. Li), yangxiaojie@tongji.edu.cn

    Contents lists availab

    Journal of Clean

    .e ls

    Journal of Cleaner Production 66 (2014) 107e112(X. Yang).material or fuel. Public health and environment will be preventedfrom its potential threat. The appropriate disposal method for SWconsequently has been the expectance, which the enterprise,researcher and government have given their great efforts to makecome true.

    Sugar lter mud (FM) is produced after sugar juice claried, andis the main solid waste in sugar industry. Its safe disposal alwayshas been the hot topic for random stacking occupies land and

    breezeblock. The concern is that its high caloriexploited to the full in this process. There havproaches for FM utilization, but all of themdrawbacks. In China, more than 16,000,000 t ofproduced annually, and about 16,000,000 t of FMevery year. Serious environment problems haveit is stacked around the factory without safe dispto nd a new method to reuse FM reasonably. Thhealth and environmental risk. But if it is disposed with the necessary to avoid the presence of unsuitable substances. SarkaLiquid phaseMineral phasePhysical performanceHydration characteristic

    1. Introduction

    Solid waste (SW) is generated intivities such as manufacturing, enerchemical engineering and food proceassociated with hazardous constituebacteria and harmful organic substan0959-6526/$ e see front matter 2013 Elsevier Ltd.http://dx.doi.org/10.1016/j.jclepro.2013.11.003strength, the delay of setting time and prolongation of cement hydration. 2013 Elsevier Ltd. All rights reserved.

    dustrial production ac-duction, water supply,t al., and it generally ish as toxic heavy metal,l., and has a high public

    insoluble and imbalance nature of the nutrient in it. Besides, ittakes long time to decompose, and the intense heat and foul smellare generated (Sen and Chandra, 2006). It is reported that FM canbe reused to desulphurize the fuel gases (Dolignier and Martin,1997), and to prepare the octacosanol (Qu et al., 2012). Unfortu-nately, other kinds of SW are produced, and also have to bedisposed. Lime can be prepared with FM (Nikolaos, 2004). But, it isKeywords:Burnabilityresult in the new phase formation. Compressive strength, setting time and hydration characteristic ofcement all are related to the replacement ratio of limestone with FM. It is found that the proper FMPreparation of Portland cement with suraw material

    Haoxin Li a,*, Wei Xu b, Xiaojie Yang a,*, Jianguo WuaKey Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Tongjib State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Shan

    a r t i c l e i n f o

    Article history:Received 22 April 2013Received in revised form30 October 2013Accepted 2 November 2013Available online 9 November 2013

    a b s t r a c t

    The objective of this studyas lime-based raw materiacompressive strength, settshow that FM can improveis helpful to promote the C

    journal homepage: wwwAll rights reserved.r lter mud as lime-based

    versity, Shanghai 201804, PR China200092, PR China

    s to assess the preparation of Portland cement with sugar lter mud (FM)rnability of raw mix, SEM characteristic and phase component of clinker,time and hydration characteristic of cement are investigated. The resultsraw mix burnability, and increase liquid phase amount. Less than 20% FMormation, and heighten the C3S content in clinker. More than 20% FM will

    le at ScienceDirect

    er Production

    evier .com/locate/ jc lepro

  • raw materials mainly provide the necessary chemical compounds,such as CaO, SiO2, Fe2O3 and Al2O3 for cement raw mill. The mainchemical component of FM is CaO (Neha et al., 2011), which is alsothe main chemical compound of lime-based cement raw materials.

    and Sulovsky, 2002; Kolovos et al., 2001). In practical production,

    sented, and the physical performance and the hydration characteristic

    Alumina ratio IM Al2O3Fe2O3

    (3)

    All raw materials were blended with a similar set of parameters(KH 0.90, SM 3.0, IM 1.7). The difference was that thelimestone was replaced with different percentages of FM. FM1,FM2, FM3, FM4 and FM5 represent respectively the mixes in whichFM substitutes for 5, 10, 15, 20 and 40 wt % the limestone. Thechemical composition and parameter of all mixes are given inTable 2.

    All mixes were prepared with appropriate water, put into the

    H. Li et al. / Journal of Cleaner Production 66 (2014) 107e112108of cement prepared with FM are investigated in this paper.

    2. Experimental

    2.1. Materials

    Limestone and gypsum were industrial materials. Powders ofaluminum sesquioxide, silicon dioxide and ferric oxide were usedto adjust the contents of Al2O3, SiO2 and Fe2O3 in the raw mixes,and all of them are chemical reagents. FM was obtained from asugar manufacture corporation. FM and limestone were dried toconstant weight at 105 C, crushed by jaw crusher and ground toASTM 200 mesh size with a centrifugal ball mill. Chemical com-positions of FM and limestone are shown in Table 1.

    2.2. Clinker preparation

    The compositional parameters in cement chemistry are listed asfollows (Eqs. (1)e(3)).

    Lime saturation ratio KH CaO 1:65Al2O3 0:35Fe2O32:80SiO2

    (1)

    Silica ratio SM SiO2Al2O3 Fe2O3

    (2)

    Table 1Chemical compositions of FM and limestone (wt %).

    Oxides SiO2 Al2O3 Fe2O3 CaO Na2O K2O MgO SO3 P2O5

    Limestone 3.62 0.65 0.35 50.37 0.05 0.03 0.88 e ethe content of sulfate and magnesium added to the raw mix arelimited for the restrictions on the SO3 and MgO content in theclinker. Additionally, high content of P2O5 will decrease the C3S: C2Srate, and give rise to the formation of a-C2S (Lin et al., 2009).

    Although there is lot of research efforts as reported in these litera-ture, it is difcult, through them, to evaluate the preparation of Port-land cement clinker with sugar lter mud as lime-based rawmaterialbecause of the varieties of materials used in the previous researches.There still remain some important points needed to systematicallyclarify. They are crucial tomake effective use of FM in Portland cementproduction. Therefore, the raw mix burnability is discussed, themorphology and composition characteristics of the clinker are pre-Thereby, at least in theory, it can be used as the alternatives of lime-based materials for clinker production. There are also several ad-vantages of utilizing FM in the cement clinker production. The hightemperature (above 1400 C) in kiln can decompose the toxicorganic matters and the bacteria; fuel can be also saved due to highcaloric value of FM (Ribbing, 2007). But, FM also contains severalhigher contents of impurities except for the CaO, such as MgO, SO3and P2O5 as compared with the traditional lime-based raw mate-rials. Minor content of MgO, sulfur compounds and phosphatesnormally are used as mineralizers to decrease the viscosity of theinterstitial melt, stabilize different polymorphs of tricalcium silicate(C3S) and dicalcium silicate (C2S), and improve the Portland cementstrength, alone or together with other minor components (StanekFM 2.30 0.39 0.37 48.40 0.08 0.49 1.32 2.85 2.5FM5 24.08 4.91 2.96 70.04 0.09 0.30 1.50 1.65 1.45LSF 0.90cylindrical mold, and pressed to a slice with a pressure of200 MPa. Then these slices were heated to 1450 C with the rate of25 C/min, kept the temperature for 2 h in the furnace, and cooledrapidly in the air to room temperature. With 3 wt % gypsum, theclinkers were ground to ASTM 200 mesh, and the cements wereobtained.

    2.3. Testing methods

    The contents of free lime (f-CaO) in clinkers were analyzed bythe glyceroleethanol method.

    Scanning electron microscope (SEM) was carried out on aQuanta 200 FEG to observe the microcosmic characteristics of theobtained clinkers. The accelerating voltage was 20 kV, and themagnication was 2000.

    Mineral phases of clinkers and pastes were identied by a D/max 2550 X-ray powder diffractometer (XRD), and the 2q rangewas20w60, in 0.02 steps, counting by 4 s per step. The radiationwasCuKa at wavelength of 0.1541 nm (40 kV).

    Compressive strength tests were carried out according to theChinese National Standard GB/T 17671-1999. Mortars were pre-pared bymixing cements with drinking water at awater-to-cementweight ratio of 0.5 and cement-to-sand ratio of three, casted in40 mm 40 mm 160 mm molds and vibrated at the time ofcasting to remove air bubbles. The molded pastes were kept at20 20 C and relative humidity exceeding 90% for 24 h, and thenremoved from the molds. The demoulded samples were cured in awater tank at 20 2 C for the set ages and then their strengthswere measured.

    Setting time of cement was examined according to the ChineseNational Standard GB/T 1346-2001.

    An isothermal heat-conduction calorimetry (TAM air C80,Thermometric, Sweden) was used to measure the hydration heatevolution of cements. The water-cement ratio was 0.5 andexperimental temperature was 20 0.1 C. Cement and waterwere tempered for several hours before mixing, then the waterwas injected into the reaction vessel and the samples were stirredin the calorimeter for several minutes. This procedure allowedmonitoring the heat evolution from the very beginning whenwater was added to cement. Data logging was continued for about3 days.

    Table 2Chemical composition and parameter of all raw mixes (wt %).

    Oxides SiO2 Al2O3 Fe2O3 CaO Na2O K2O MgO SO3 P2O5

    Control 24.08 4.91 2.96 70.04 0.07 0.04 1.23 e eFM1 24.08 4.91 2.96 70.04 0.07 0.07 1.26 0.21 0.18FM2 24.08 4.91 2.96 70.04 0.07 0.11 1.30 0.41 0.36FM3 24.08 4.91 2.96 70.04 0.08 0.15 1.33 0.62 0.55FM4 24.08 4.91 2.96 70.04 0.08 0.17 1.36 0.82 0.72

    IM 1.70

    SM 3.0

  • 3. Result and discussion

    3.1. Burnability

    Raw mix burnability is related to the conversion rate at whichCaO combines with other chemical components in the sinteringprocess. It commonly is evaluated by the content of f-CaO in clinker.In this study, all mixes were respectively sintered at 1250 C,1300 C, 1350 C, 1400 C, 1450 C and 1500 C for 60 min, and theheating-up speed was 25 C/min. Then all clinkers were cooled toroom temperature rapidly. After ground to ASTM 200 mesh, the f-CaO contents in themwere determined. The results of free lime aregiven in Fig 1.

    Fig.1 shows that the free lime contents of clinkers prepared withFM are lower than that of control at all sintering temperatures.When more content of FM is substituted for limestone in thepreparation of cement, then it is observed that lesser is the freelime available in the clinkers. FM improves the burnability of raw

    observed, and one of them is labeled as A (shown in Fig. 2a). Large

    H. Li et al. / Journal of Cleaner Prcrystal grains are stacked together closely, and their outlines andboundary lines are visible. Crystal grains change round and smallfor the clinker produced with 5% FM (shown in Fig. 2b). Theiroutlines almost are not found, and the boundary lines are blurred.In addition, drooping-shape microstructures appear, and some ofthem are marked as the B, C, D and E. The same cases are also found

    0 10 20 30 400

    2

    4

    6

    8

    10

    12

    14

    Free

    lim

    e co

    nten

    t in

    clin

    kers

    (wt %

    )

    Sugar filter mud replacement ratios (wt %)

    1250 13001350 14001450 1500mix. The improvement is related to the presence of impurity ele-ments in FM, such as P, S, Mg, K and Na. This conclusion implies thatthe CaO conversion rate can be raised, due to the replacement oflimestone with FM. The sintering temperature or time can bedecreased or reduced, and a part of the energy, which is required tomake the f-CaO content in the clinker below 1.5%, can be saved.

    3.2. Clinker characteristic

    3.2.1. SEM observationThe initial raw materials, mineral composition and particle size

    determine the cement sintering behavior. In general, this behaviorimplies the formation of liquid phase (Anton et al., 2000). It iscrucial to the C3S formation because the reaction between CaO andC2S commonly takes place through the liquid phase. This reactionmay be accelerated as the amount of liquid phase increases and itsviscosity decreases. The liquid phases in the different clinkers wereobserved by SEM. The fracture surface micrographs of clinkers areshown in Fig. 2.

    In the control, the approximate orthogonal structures areFig. 1. The free lime content in clinkers sintered at different temperatures.in the clinker added with 10% FM (shown in Fig. 2c). Obviously, theliquid phases in FM1 and FM2 clinkers increase, compared withthat in the control.

    It is the obvious fact that the separate crystal grains almost cantbe observed, the boundary lines disappear, and the orthogonaledges of crystal grains change to the aculeated convexes in the FM3.There are several annular zones marked as H, I and J except for thedrooping-shape structure signed as G (shown in Fig. 2d). Theaculeated convexes and the annular zones disappear, and allcement phases almostmelt together into awhole (shown in Figs. 2eand f). The liquid phase amount continues to increase in the FM3,FM4 and FM5. FM raises the amount of liquid phase notably.

    3.2.2. XRD patternsAll clinker XRD patterns are shown in Fig. 3. It can be seen from

    the Fig. 3 that the major phases of the ordinary Portland cement,C3S, C2S, C3A and C4AF are all identied in each clinker. But themostimportant characteristic peaks of C3S appeared at 2q about 32, areprovided with different intensities (shown in Fig. 3b). The intensityto some extent determines the relative content of C3S in clinker.Among all clinkers, the intensity of FM2 is the strongest. The fol-lowings are FM1, FM3, control, FM4 and FM5. The C3S content inFM1, FM2 and FM3 are higher that in the control, but the situationsin FM4 and FM5 are reverse. The suitable content of P2O5...

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