research article an alternative to clay in building...

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2013 Article ID 757923 7 pageshttpdxdoiorg1011552013757923

Research ArticleAn Alternative to Clay in Building Materials Red Mud SinteringUsing Fly Ash via Taguchirsquos Methodology

Suchita Rai12 Dilip H Lataye3 M J Chaddha1 R S Mishra1 P Mahendiran1

J Mukhopadhyay4 ChangKyoo Yoo5 and Kailas L Wasewar25

1 Jawaharlal Nehru Aluminium Research Development and Design Centre Wadi Amravati Road Nagpur India2 Advanced Separations and Analytical Laboratory Department of Chemical EngineeringVisvesvaraya National Institute of Technology (VNIT) Nagpur Maharashtra 440011 India

3 Department of Civil Engineering Visvesvaraya National Institute of Technology (VNIT) Nagpur Maharashtra 440011 India4 Indian Institute of Technology Gandhinagar Gujarat India5 Environmental Management amp Systems Engineering Lab (EMSEL) Department of Environmental Science and EngineeringCollege of Engineering Kyung Hee University Seocheon-dong 1 Giheung-gu Gyeonggi-do Yongin-si 446-701 Republic of Korea

Correspondence should be addressed to ChangKyoo Yoo ckyookhuackr and Kailas L Wasewar k wasewarrediffmailcom

Received 29 May 2013 Revised 6 September 2013 Accepted 6 September 2013

Academic Editor Markku Leskela

Copyright copy 2013 Suchita Rai et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

ldquoRedmudrdquo or ldquobauxite residuerdquo is a highly alkalinewaste generated from alumina refinerywith a pHof 105ndash125which poses seriousenvironmental problems Neutralization or its treatment by sintering in presence of additives is one of the methods for overcomingthe caustic problem as it fixes nearly all the leachable free caustic soda present in redmud In the present study feasibility of reducingthe alkaline nature of red mud by sintering using fly ash as an additive via Taguchi methodology and its use for brick productionas an alternative to clay is investigated The analysis of variance (ANOVA) shows that sintering temperature is the most significantparameter in the process A pHof 89 was obtained at 25ndash50 of redmud and 50ndash75 fly ashwith water and temperature of 1100∘CAlternatively 50 of red mud can be mixed with 50 of fly ash with water at temperature of 1200∘C to get a pH of about 84 Themechanism of this process has been explained with also emphasis on chemical mineralogical and morphological analysis of thesintered red mud The results would be extremely useful in utilization of red mud in building and construction industry

1 Introduction

The Bayer process of extraction of alumina from bauxiteremains the most economical process till date In the Bayerprocess the insoluble product generated after bauxite diges-tion with sodium hydroxide at elevated temperature andpressure to produce alumina is known as ldquored mudrdquo orldquobauxite residuerdquo which is highly alkaline in nature with a pHof 105ndash125 Red mud is a mixture of compounds originallypresent in bauxite and of compounds formed during theBayer cycleThemain reaction of aluminumoxide dissolutionin the Bayer process is as follows

2NaOH + Al2O3sdot 3H2O 997888rarr Na

2O sdot Al

2O3+ 4H2O (1)

Depending on the raw material processed 1ndash25 tonsof red mud is generated per ton of alumina produced [1]

An enormous quantity of red mud is generated worldwide(sim75 million tons) every year posing a major environmentalproblem In India about 471 million tonsannum of redmudis produced which is 625 of worldrsquos total generation [2]Red mud is disposed as semidry material in red mud pondor abandoned bauxite mines and as slurry having a highsolid concentration of 30ndash60 Problems associated with thedisposal of red mud waste include its high pH alkali seepageinto underground water safety in storage alkaline air bornedust emissions and the vast area of land required for disposalUp to 2 tons of liquor with a significant alkalinity of 5ndash20 gLcaustic (as Na

2CO3) accompanies every ton of dry mud

Neutralization of red mud will help to reduce the environ-mental impact caused due to storage activities of the residueand will also open opportunities for the reuse of the residuewhich till now has been prevented because of the high pH

2 Advances in Materials Science and Engineering

It will also reduce degradation of clay or synthetic liners of redmud ponds The overall risk of groundwater contaminationwould be reduced significantly by neutralizing red mud

The literature shows that red mud can be treated with anyof these methods to make it environmentally benign acidleaching CO

2treatment bioleaching seawater neutraliza-

tion and sintering A review of neutralization processes ofred mud and its utilization is given by investigators [3]

A considerable research has been done on the utilizationof red mud as a raw material for the production of a range ofbuilding products by sintering of red mud Red mud can beused as a constructionalbuilding material in bricks blockslight weight aggregates roofing tiles glass ceramics cementindustry as cements and special cements and concrete indus-try Red mud is made into useful ceramics articles by mixing51ndash90 of the weight of red mud with 10ndash49 of the weightof at least one mineral andor silicate containing materialshaping the mixture and firing it at a temperature of 950∘ndash1250∘C [4] A patent [5] claims a process for manufacturingfired bricks wherein 50ndash90wt of red mud can be usedalong with clay and a water fixing agent The raw bricks aredried with heated gases at a temperature below 70∘C andsubsequently fired at a temperature between 900∘ndash1100∘CThough all these studies are based on sintering of red mudand its use very little has been stated about the change inpHwith the sintering temperature and other parametersTheways in which these factors may interact in the neutralizationor treatment process are poorly understood

Hence the present study focuses on the study of changein pH in the sintering process due to a wide range of factorsThe treatment process involves mixing of silicate materialsuch as fly ash with red mud in presence of water Fly ash isthe by-product of burning of coal and is available from coal-based thermal power plants and other coal burning centersAn estimated availability of fly ash in India is about 80ndash100 million tons per year [6] Every thermal power plantgenerating 1000MWpower on an average produces 3500 tonsof fly ash every day [6] It is estimated that an area of about28000 ha of land will be necessary to dump all the fly ashavailable in the country The present utilization level of flyash in India is less than 10 [6] Fly ash contains l to 100 120583msuspended particulates affecting plant growth besides being ahealth hazard [7] Indian red mud is rich in titania and ironin alkali oxides while the fly ash is rich in silica and aluminaThese features contribute to the optimum composition forbrick making [7]

Hence use of fly ash has been made as a silicate materialin sintering of red mud In this way both the wastes can bemade nonhazardous and can be reused

Taguchirsquos experimental methodology has been employedto evaluate the pH values Taguchirsquos design of experimentshas been used extensively in product quality assessment andseveral other studies [8ndash12] Taguchirsquos fractional factorialdesign of experiments has been used to examine the effectof significant parameters such as weight of red mud weightof silicate material added volume of water and reactiontemperature on the response characteristic (pH of red mudslurry) The average values and the signal to noise (119878119873)ratio of the quality response characteristic for each parameter

at 3 levels of their values have been calculated from theexperimental dataThe response curves have been graphicallyrepresented to reflect any change in the quality characteristicand 119878119873 ratio with the variation in process parametersThese response curves are used to identify the effects ofvarious parameters on the response characteristic Significantparameters have been identified by using the analysis ofvariance (ANOVA) on the experimental data

2 Materials and Methods

21 Materials Red mud from an alumina refinery situatedat the eastern coast of India (18∘491015840910158401015840N 82∘5710158405210158401015840E) wasground to 100 mesh size and used for the study Chemicalcomposition of red mud is Al

2O3(16ndash175) Fe

2O3(535ndash

56) SiO2(6-7) TiO

2(5-6) Na

2O (4-5) and CaO (2-

3) Mineralogically red mud contains phases of undigestedalumina aluminosilicates and phases of iron and titaniaAlumina is in form of undigested gibbsite alumogoethiteand sodalite along with silica and sodium (sodium alu-minosilicates) iron is in form of hematite alumogoethitesiderite and ilmenite titania is in form of anatase rutile andilmenite and calcium is in form of calcite Average particlesize of red mud is less than 10 microns with specific surfaceas 2026m2g

The mineralogical composition of untreated red mud is

gibbsite Al(OH)3

sodalite Na2O Al2O3sdot2SiO2sdot2H2O

hematite Fe2O3

alumogoethite FeAlOOH

anatase TiO2

rutile TiO2

ilmenite FeTiO3

siderite FeCO3

calcite CaCO3

Sodium present in red mud (total caustic soda) is in twoforms free or soluble caustic soda and bound caustic sodaFree caustic soda is the entrained liquor in the red mudslurry which gets incorporated during digestion process andremains with red mud in spite of repeated washings Freesoda is in the form of NaOH Na

2CO3 NaAlO

2 and so

forth The pH of the red mud is due to the presence ofthese alkaline solids in red mud Bound soda is in the formof sodalite complex which can be stated as ldquoNASrdquo phases3(Na2OAl2O32SiO2)Na2X (X = CO

3

2minus 2OHminus SO4

2minus 2Clminus)(Kurdowski and Sorrentino 1997) [13] In redmud about 20ndash25 is the free or soluble caustic soda while the rest is in theform of sodalite complex

Fly ash has the following composition 57-58 SiO2

34ndash36 Al2O3 and 4ndash6 Fe

2O3 Mineralogically fly ash

contains about 75ndash80 quartz (SiO2) with remaining mullite

(2Al2O3SiO2) alumina in the form of mullite and iron as

hematite

Advances in Materials Science and Engineering 3

22 Experimental Setup Red mud fly ash and water weremixed in different proportions as per the experimentsdesigned by Taguchirsquos methodology and kept in a crucibleat different temperatures in a muffle furnace (CHEMINCOKolkata) After sintering the mixture for a fixed duration thecrucible was cooled overnight and the mixture was taken ina beaker and 100mL distilled water was added The mixturewas stirred for 30min using magnetic stirrer (EltekM S 204)The pH of the slurry was measured after each test usingLabX Light Titrator (Potentiometric Titrator)Mettler ToledoGmbH Switzerland

23 Taguchirsquos Design of Experimental Methodology DrTaguchi of Nippon Telephones and Telegraph CompanyJapan has developed a method based on ldquoorthogonal arrayrdquoexperiments which gives much reduced ldquovariancerdquo for theexperiment with ldquooptimum settingsrdquo of control parametersTaguchi methods [10] use orthogonal array distribution todesign an experiment A traditional experimental designto compare four independent variables at three differentlevels each requires a large number of individual experiments(eighty-one experiments) The logistical and resource impli-cations of this experimental design make these experimentsvery difficult to carry out By using 119871

9orthogonal array with

Taguchi method to design an experiment a study involving4 factors at 3 different levels can be conducted with onlynine individual experiments Taguchi method consists of 3phases designing the experiment running and analyzingand confirming and validating the experimental results Inan orthogonal array each array can be identified by theform 119871

119860(119861119862

) the subscript of 119871 which is designated by119860 represents the number of experiments that would beconducted using this design and 119861 denotes the number oflevels within each column which denotes how many levelscould be investigated while the letter 119862 indicates how manyfactors or variables could be included in the experiment [10]1198719orthogonal array consisting of four control parameters

(factors) A B C and D is given in Table 1 and set atminimum middle and maximum value (ie levels 1 2 and3) The parameters were decided based on the preliminaryexperimentation carried out In all nine experiments had tobe conducted Each experimental run was repeated thriceThe pH values (replicated thrice as 119877

1 1198772 and 119877

3) obtained

for each experiment of the 1198719array are shown in Table 2

Subsequently analysis of variance (ANOVA) based on theTaguchi method was carried out using the values to deter-mine the contribution of each parameter to the process ofneutralization

231 Treatment of Red Mud at High Temperature The initialpH of the red mud slurry was 107 (50 gm of red mud wasstirred with 100mL of distilled water for 30min) After eachexperimental run designed as per Taguchirsquos experimentalmethodology pH of slurry was measured The slurry samplewith the lowest pH value and close to 70 (of experimentalrun number 7) was filtered usingWhatman paper no 40Thefiltered red mud was dried and analyzed

Table 1 Experimental layout of parameters and their levels

Factors Parameters Units Level Observed value1 2 3

A Weight of red mud g 10 20 30

pHB Weight of silicatematerial g 10 20 30

C Volume of water mL 8 10 12D Temperature ∘C 900 1000 1100

Chemical constituents of red mudmix obtained after sin-tering at the optimized condition were analyzed by usingWetChemical Method Untreated red mud fly ash and sinteredred mud were analyzed mineralogically for determinationof phases using XRD X-ray diffractometer (PANalytical X-Pert Pro) using Cu K120572 radiation (120582 = 154060 A) Scanningelectron microscopy (SEM) has been conducted to study themorphology of neutralized red mud using Electron ProbeAnalyzer (MAKE JEOL Japan JXA-840A)

The slurry sample was prepared from red mud sinteredat the optimized condition of parameters (of experimentalrun number 7) and 100mL distilled water and steeredthoroughly pH rebound phenomenawere studied for 2-weektime duration with this sample of red mud slurry

232 Analysis of Experimental Data The experimental datagenerated was analyzed by analysis of variance (ANOVA)Taguchi excel sheet is used for all the analysis which is basedon Taguchi method for determination of main effects of theprocess parameters1198771015840 values are the ratio of neutral pH (7) to experimental

pH value 11987710158401

11987710158402

and 11987710158403

are the values calculated from1198771 1198772 and 119877

3 On this basis the ldquohigher-is-betterrdquo quality

characteristic was used in the analysis of experimental dataThe plot of response curves and analysis of variance for rawdata and 119878119873 ratio data was used for the analysis of resultsThe mean of the response characteristic pH (119884opt) at theoptimal condition was estimated as

119884opt =119879

119873+ (A1avg minus119879

119873) + (B

3avg minus119879

119873)

+ (C3avg minus119879

119873) + (D

3avg minus119879

119873)

(2)

where119879119873 is the overall mean of the response where119879 is thegrand total of all results and119873 is the number of experimentsand A

1avg B3avg C3avg and D3avg represent average values of

response at the first level of parameter A and third levels ofparameters B C and D respectively

In order to confirm that the optimal parametric valuesusing Taguchirsquos methodology are valid selected confirmatoryexperiments were carried out under optimal conditions Theaverage of the results of the confirmation experiment is thencompared with the anticipated average based on the optimalparameters and levels tested by Taguchirsquos methodology The119884opt value obtained is 078 and pH value of which comesout to be 8969 which is close to the optimized experimental


Table 2 1198719

table and observed values of pH

RunFactors Final pH Ratios of pH

119878119873 ratioA B C D1198771

1198772

11987731198771015840

1

1198771015840

2

1198771015840

3Weight of red mud Weight of silicate material Volume of water Sintering temp1 20 30 8 1000 912 925 93 077 076 075 minus2402 20 20 12 900 107 1065 1054 065 066 066 minus3633 30 10 12 1000 965 962 959 073 073 073 minus2764 10 20 10 1000 958 932 931 073 075 075 minus2565 30 20 8 1100 910 915 918 077 077 076 minus2326 30 30 10 900 1068 1055 1061 066 066 066 minus3627 10 30 12 1100 89 892 888 079 078 079 minus2098 20 10 10 1100 927 925 93 076 076 075 minus2439 10 10 8 900 1069 106 10582 065 066 066 minus362

Table 3 Average and main effects of ratios of pH valuesmdashRaw and 119878119873

Factors Raw data average value Main effects 119878119873 data average value Main effects (119878119873 data)1198711

1198712

1198713

1198712

-1198711

1198713

-1198712

1198711

1198712

1198713

1198712

-1198711

1198713

-1198712

A 074 073 071 minus001 minus002 minus149 minus280 minus301 minus130 minus021B 072 072 074 000 002 minus292 minus289 minus270 003 019C 072 073 072 001 000 minus289 minus279 minus283 010 minus004D 066 075 076 009 001 minus362 minus252 minus237 111 015

value of 88ndash892 in run 7 The deviation between actual anddetermined pHbyTaguchirsquosmethodology ismuchwithin 5and hence it is confirmed that the optimal parametric valuesdetermined by Taguchirsquos design are valid

24 Utilization of Red Mud Red mud was used as analternative to clay in making bricks Four standard size brickswere made by mixing suitable proportions of red mud flyash and water The bricks were made in commercial flyash brick factory machine that is Brickman machine Theywere pressed at sim200 kgcm2 dried overnight in an oven at110∘C and sintered at 1100∘C for 2 hours The compositionof the raw materials used and the properties of the bricksobtained are given in Table 6 The brick samples were testedfor cold compressive strength (CCS) water absorption (WA)efflorescence and bulk density

3 Results and Discussion

31 Effect of the Process Parameters on pH Table 3 providesthe raw data for the average value ratios of pH and 119878119873ratio for each parameter at levels 1 2 and 3 The sinteringtemperature from level 1 to level 2 has the greatest influenceon value of pH The difference between the levels also showsthe same trend Figure 1 shows the response curves of theindividual parameters on the ratio of pH values that is 1198771015840values (7experimental pH value) and 119878119873 ratio

FromFigure 1 it can be seen that the ratio of pHdecreaseswith the increase in the weight of red mud (factor A) Itis due to the increase in free caustic soda in the slurrywith the increase in quantity of red mud There is a sharpdecrease in the ratio of pH values when factor A changes

1

09

08

07

06

05

04

03

02

01

0

Ratio

of p

H

10 20 30 10 20 30

A B8 10 12

C

900

1000

1100

D

0

minus1

minus2

minus3

minus4

minus5

SN

ratio

pHSN ratio

Figure 1 Main effects of each factor on ratio of pH along with 119878119873ratio of treated redmud slurry (ANOVA analysis) A wt of redmud(g) B wt of silicate material (g) C vol of water (mL) D temp (∘C)

from level 1 to 2 and also when the quantity of red mudchanges from level 2 to 3 Sintering temperature (factor D)definitely decreases the pH of the slurry as a sharp increase inthe ratio of pH is observed from level 1 to 2 Further increasein the ratio of pH values (ie decrease in pH) is observedfrom level 2 to level 3 Not much change in pH is observedat 900∘C but the change is seen above this temperatureThe increase in temperature decreases the pH substantiallydue to the fusion of free soda with the silica and aluminapresent in fly ash The overall results convey that the pH


Table 4 ANOVA table

Factors Total variance of each factor Degree of freedom Variance Variance ratio Pure sum of sq Percent contributionA 0001 2 0000 105651 000062816 1090B 0002 2 0001 2982904 000189326 3079C 0000 2 0000 4087215 000020274 0422D 0060 2 0030 9154204 006005186 94480Error 0001 18 0000 1 000032836 0929Totals 0064 26 0032 100000

Table 5 Mineralogical phases in sintered red mud

Compound name Chemical formula JCPDS noCorundum Al2O3 00-046-1212Sillimanite Al2SiO5 00-038-0471Jadeite NaAlSi2O6 00-022-1338Burnt ochre Fe2O3 00-033-0664Aluminum iron oxide AlFeO3 00-030-0024Brookite TiO2 00-015-0875Calcium oxide CaO 00-037-1497Calcium silicate Ca2SiO4 00-031-0299Grossular Ca3Al2(SiO4)3 00-039-0368Sodium aluminum oxide NaAlO2 00-033-1200

of the slurry is mostly affected by the sintering temperatureThe lowest pH is obtained with the weight of red mud atlevel 1 weight of silicate material at level 3 water at level3 and temperature at level 3 (A

1B3C3D3) The contribution

of individual parameters was weighted as shown in Table 4with analysis of variance (ANOVA) to see their effect ondesired response characteristic (pH) The most significantparameters are found to be the sintering temperature with avery high contribution of 9448 followed by weight of redmud (109) andweight of silicatematerial (308) andwater(05)

32 Confirmation Experiment From Table 2 it can be seenthat the experimental condition (A

1B3C3D3) was the one

in which the lowest value of pH value was achieved (888ndash89) which was close to the neutral value of 7 in all the 3replications As per the Guidelines of Australian and NewZealand Environment and Conservation Council (ANZEX)and Agriculture and Resource Management Council ofAustralia and New Zealand (ARMCANZ) the liquor beingstrongly alkaline with a high pH requires neutralization to apH below 9 with an optimum value of 85ndash89 before becom-ing environmentally benign [14] The optimized conditionobtained from Figure 1 was A

1B3C3D3having pH value of

about 890 which is the lowest of all the values Hence theseconditions were fine-tuned by increasing the temperatureto 1200∘C and the pH achieved was 834 which is withinthe acceptable limit Hence the final optimized conditionsto achieve a pH of 89 were 25ndash50 of red mud and 50ndash75 silicate material with water (10) and a temperature of1100∘C Alternatively 50 of red mud can be mixed with 50of fly ash with water at temperature of 1200∘C to get a pH

of about 84The results are in accordancewith those obtainedby investigators [4] In absence of sintering studies carriedout at Jamaica [15] show that in neutralization of red mudwith acidic fly ash a large amount of fly ash is required withvery slow neutralization rate (approx 150 days to get a pHfrom 125 to 11)

33 Red Mud Analysis after Neutralization

331 Chemical Analysis The chemical analysis of red mudafter sintering is Al

2O3 2450 Fe

2O3 3192 SiO

2 3450

TiO2 253 Na

2O 45 and CaO 109 Sintered red mud

has high alumina content low iron content and high silicacontent due to the addition of silicate material (fly ash)and subsequent sintering of the mixture as compared to theoriginal red mud

332 Formation of Different Phases To investigate the phasestructures of the red mud the X-ray diffraction pattern wasmeasured Figure 2 shows the XRD pattern which shows awell crystallized sintered red mud powder The peaks of thered mud show the phases as shown in Table 5 Aluminapresent in redmud in the hydroxide form has been convertedinto corundumwhich is alpha phase of alumina Alumina hasalso reacted with silica from fly ash to form aluminosilicates(sillimanite) which impart strength to the fused materialCaustic soda has fused with alumina and silica to formsodium silicates and sodium aluminosilicates Some of thefree soda is still present in the sintered red mud in form ofsodium aluminate Hence pH value of above 89 is observedafter the process Calcium aluminosilicates and calciumsilicates are also formed

Some of the reactions taking place in the process are

Na2CO3+ SiO

2997888rarr Na

2SiO3+ CO2

(3)

2NaOH + SiO2997888rarr Na

2SiO3+H2O (4)

Na2SiO3+ Al2O3997888rarr Al

2O3sdot SiO2sdotNa2O (5)

3Al2O3+ 2SiO

2997888rarr 3Al

2O3sdot 2SiO

2(6)

333 Morphology of Red Mud Figure 3 shows the morpho-logical structure of original (untreated) red mud as seenin SEM which indicates scattered fine particles of about 1micron size Globular particles with smooth surface whichare formed due to the formation of sodium aluminosilicatesare observed (Figure 4) in sintered red mud


20 30 40 50 60 70 80 90

Cou

nts

0

100

200

300

400

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3

Position [∘2120579]

Figure 2 Mineralogical phases of sintered red mud mix with fly ash (XRD) Conditions red mud fly ash (1 3) with 10 water 1100∘C

Figure 3 SEM photograph of untreated red mud

334 Physical Characteristics of Red Mud Physical charac-teristics of sintered red mud improve to a large extent as fastfiltration of sintered red mud slurry is observed Also thecolor of filtrate is clear as compared to filtrate obtained withuntreated red mud

34 Utilization of Sintered Red Mud The chemical miner-alogical and morphological properties of sintered red mudshow that the material can be used in construction industryin place of clay It can be utilized as a replacement of naturallyavailable building material and for the production of newbuilding materials The developed bricks are having verygood strength with CCS ranging from 30 to 135 kgcm2with slightly more value of WA as shown in Table 6

Figure 4 SEM photograph of sintered red mud

The bricks are included in the class of 35 to 125 Thesepromising results show that technically these bricks aresuitable for construction of load-bearing walls Red mudblocks can also be made from these mixtures which can alsobe used as a low cost housing material Red mud in therange of 40ndash60 can be used for making good quality bricksEfforts have beenmade at Central building Research Institute(CBRI) India to produce burnt clay bricks by partiallyreplacing the clay with red mud lime and fly-ash [16]

35 pH Rebound The increase in pH and aluminium con-centration after the neutralization of red mud is commonlyknown as reversion or rebound No pH rebound wasobserved with the optimized sample as the pH remained


Table 6 Composition and properties of bricks

Brick composition Properties of bricksRed mud () Fly ash () CCS (kgcm2) WA () Efflorescence Bulk density (gcc) Class of brick

Composition 1 50 50 317 240 Nil 147 Class 35Composition 2 45 55 6693 2450 Nil 149 Class 5Composition 3 40 60 8673 238 Nil 150 Class 75Composition 4 35 65 13418 2410 Nil 151 Class 125

the same even after two weeks This means that there isno more caustic soda leaching after its initial leaching fromsintered red mud

4 Conclusion

The paper has discussed in detail the feasibility of sinteringof red mud to deal with the caustic soda in it using TaguchirsquosmethodologyThepHof redmud slurry reaches valueswithinthe acceptable limits after sintering red mud with a silicatematerial (fly ash) at a very high temperature of 1100ndash1200∘CThemethod of treating redmud with fly ash along with watercan be a successful process to tackle the caustic soda problemAlso the resultant material can be reused as a constructionmaterial in place of clay Taguchirsquos experimentalmethodologyis found to be a valuable tool The ANOVA analysis usingTaguchimethodology shows that themost significant param-eters are temperature of calcinations (9448) followed byweight of red mud (109) and quantity of fly ash (3079)The optimized conditions to achieve a pH value of about 89were 25ndash50 of red mud mixed with 50ndash75 of fly ash withwater (10) and a temperature of 1100∘C Alternatively about50 of red mud with 50 of fly ash and 1200∘C can be usedwhere the pH obtained is within the permissible limit of 84

The study shows that treatment of red mud with flyash at a very high temperature lowers down the pH andhence alkalinity of red mud slurry permanently without pHrebound This also modifies the physical characteristics asis evident from the morphology of red mud Sintering ofresidue can be carried out to fix all leachable soda and toachieve high strength during the sintering process Thus redmud can be used as an alternative to clay material in buildingand construction industry Both red mud and fly ash can bereused However the cost would be very high due to the highenergy consumption as an elevated temperature is requiredfor sintering But the process would certainly help in reducingpollution of soil air and water and would considerably saveresources of mother earth

References

[1] R K Paramguru P C Rath and V N Misra ldquoTrends inred mud utilizationmdasha reviewrdquoMineral Processing amp ExtractiveMetallurgy Review vol 26 no 1 pp 1ndash29 2005

[2] U V Parlikar P K Saka and S A Khadilkar ldquoTechnologicaloptions for effective utilization of bauxite residue (Red mud)mdasha reviewrdquo in International Seminar on Bauxite Residue (REDMUD) Goa India October 2011

[3] S B Rai K L Wasewar J Mukhopadhaya K Chang and HUslu ldquoNeutralization and Utilization of red mud for its betterwaste managementrdquo Archives of Environmental Science vol 6pp 13ndash33 2012

[4] F Puskas ldquoProcess for the utilization in the ceramics industryof red mud from alumina plantsrdquo US Patent 4368273 1983

[5] B Garhard ldquoMethod for producing bricks from red mudrdquo USPatent 3886244 1975

[6] K G K Warrier P Krishna Pillai P Perumal and C L VermaldquoLiquid phase sintering of flyash to produce high volume flyashceramics for a variety of applicationsrdquo CSIR News vol 54 pp13ndash14 2004

[7] Wealth from waste special Report ldquoConstruction World(Indian Edition)rdquo 2002 httpwwwconstructionupdatecomproductsconstructionworld2002jan2002010html

[8] D M Byrne and S Taguchi ldquoThe Taguchi approach to param-eter Design rdquo Quality Progress vol 20 no 12 pp 19ndash26 1987

[9] P J Ross Taguchi Techniques for Quality Engineering McGrawHill New York NY USA 1996

[10] G S Peace Taguchi Methods A Hands-on Approach Addison-Wesley 1993

[11] S B Rai K L Wasewar D H Lataye et al ldquoNeutralization ofred mud with pickling waste liquor using Taguchirsquos design ofexperimental methodologyrdquo Waste Management and Researchvol 30 no 9 pp 922ndash930 2012

[12] S B Rai K L Wasewar D H Lataye and J MukhopadhyayldquoFeasibility of red mud neutralization with Seawater usingTaguchirsquos methodologyrdquo International Journal of EnvironmentalScience and Technology vol 10 no 2 pp 305ndash314 2013

[13] W Kurdowski and F SorrentinoWaste Materials Used in Con-crete Manufacturing Edited by S Chandra William AndrewNoyes 1997

[14] C Hanahan DMcConchie J Pohl R CreelmanM Clark andC Stocksiek ldquoChemistry of seawater neutralization of bauxiterefinery residues (red mud)rdquo Environmental Engineering Sci-ence vol 21 no 2 pp 125ndash138 2004

[15] S Khaitan D A Dzombak and G V Lowry ldquoChemistry of theacid neutralization capacity of bauxite residuerdquo EnvironmentalEngineering Science vol 26 no 5 pp 873ndash881 2009

[16] A Dass and S K Malhotra ldquoLime-stabilized red mud bricksrdquoMaterials and Structures vol 23 no 4 pp 252ndash255 1990

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


It will also reduce degradation of clay or synthetic liners of redmud ponds The overall risk of groundwater contaminationwould be reduced significantly by neutralizing red mud

The literature shows that red mud can be treated with anyof these methods to make it environmentally benign acidleaching CO

2treatment bioleaching seawater neutraliza-

tion and sintering A review of neutralization processes ofred mud and its utilization is given by investigators [3]

A considerable research has been done on the utilizationof red mud as a raw material for the production of a range ofbuilding products by sintering of red mud Red mud can beused as a constructionalbuilding material in bricks blockslight weight aggregates roofing tiles glass ceramics cementindustry as cements and special cements and concrete indus-try Red mud is made into useful ceramics articles by mixing51ndash90 of the weight of red mud with 10ndash49 of the weightof at least one mineral andor silicate containing materialshaping the mixture and firing it at a temperature of 950∘ndash1250∘C [4] A patent [5] claims a process for manufacturingfired bricks wherein 50ndash90wt of red mud can be usedalong with clay and a water fixing agent The raw bricks aredried with heated gases at a temperature below 70∘C andsubsequently fired at a temperature between 900∘ndash1100∘CThough all these studies are based on sintering of red mudand its use very little has been stated about the change inpHwith the sintering temperature and other parametersTheways in which these factors may interact in the neutralizationor treatment process are poorly understood

Hence the present study focuses on the study of changein pH in the sintering process due to a wide range of factorsThe treatment process involves mixing of silicate materialsuch as fly ash with red mud in presence of water Fly ash isthe by-product of burning of coal and is available from coal-based thermal power plants and other coal burning centersAn estimated availability of fly ash in India is about 80ndash100 million tons per year [6] Every thermal power plantgenerating 1000MWpower on an average produces 3500 tonsof fly ash every day [6] It is estimated that an area of about28000 ha of land will be necessary to dump all the fly ashavailable in the country The present utilization level of flyash in India is less than 10 [6] Fly ash contains l to 100 120583msuspended particulates affecting plant growth besides being ahealth hazard [7] Indian red mud is rich in titania and ironin alkali oxides while the fly ash is rich in silica and aluminaThese features contribute to the optimum composition forbrick making [7]

Hence use of fly ash has been made as a silicate materialin sintering of red mud In this way both the wastes can bemade nonhazardous and can be reused

Taguchirsquos experimental methodology has been employedto evaluate the pH values Taguchirsquos design of experimentshas been used extensively in product quality assessment andseveral other studies [8ndash12] Taguchirsquos fractional factorialdesign of experiments has been used to examine the effectof significant parameters such as weight of red mud weightof silicate material added volume of water and reactiontemperature on the response characteristic (pH of red mudslurry) The average values and the signal to noise (119878119873)ratio of the quality response characteristic for each parameter

at 3 levels of their values have been calculated from theexperimental dataThe response curves have been graphicallyrepresented to reflect any change in the quality characteristicand 119878119873 ratio with the variation in process parametersThese response curves are used to identify the effects ofvarious parameters on the response characteristic Significantparameters have been identified by using the analysis ofvariance (ANOVA) on the experimental data

2 Materials and Methods

21 Materials Red mud from an alumina refinery situatedat the eastern coast of India (18∘491015840910158401015840N 82∘5710158405210158401015840E) wasground to 100 mesh size and used for the study Chemicalcomposition of red mud is Al

2O3(16ndash175) Fe

2O3(535ndash

56) SiO2(6-7) TiO

2(5-6) Na

2O (4-5) and CaO (2-

3) Mineralogically red mud contains phases of undigestedalumina aluminosilicates and phases of iron and titaniaAlumina is in form of undigested gibbsite alumogoethiteand sodalite along with silica and sodium (sodium alu-minosilicates) iron is in form of hematite alumogoethitesiderite and ilmenite titania is in form of anatase rutile andilmenite and calcium is in form of calcite Average particlesize of red mud is less than 10 microns with specific surfaceas 2026m2g

The mineralogical composition of untreated red mud is

gibbsite Al(OH)3

sodalite Na2O Al2O3sdot2SiO2sdot2H2O

hematite Fe2O3

alumogoethite FeAlOOH

anatase TiO2

rutile TiO2

ilmenite FeTiO3

siderite FeCO3

calcite CaCO3

Sodium present in red mud (total caustic soda) is in twoforms free or soluble caustic soda and bound caustic sodaFree caustic soda is the entrained liquor in the red mudslurry which gets incorporated during digestion process andremains with red mud in spite of repeated washings Freesoda is in the form of NaOH Na

2CO3 NaAlO

2 and so

forth The pH of the red mud is due to the presence ofthese alkaline solids in red mud Bound soda is in the formof sodalite complex which can be stated as ldquoNASrdquo phases3(Na2OAl2O32SiO2)Na2X (X = CO

3

2minus 2OHminus SO4

2minus 2Clminus)(Kurdowski and Sorrentino 1997) [13] In redmud about 20ndash25 is the free or soluble caustic soda while the rest is in theform of sodalite complex

Fly ash has the following composition 57-58 SiO2

34ndash36 Al2O3 and 4ndash6 Fe

2O3 Mineralogically fly ash

contains about 75ndash80 quartz (SiO2) with remaining mullite

(2Al2O3SiO2) alumina in the form of mullite and iron as

hematite






119860(119861119862



1 1198772 and 119877

3) obtained












pH value 11987710158401

11987710158402

and 11987710158403




119884opt =119879

119873+ (A1avg minus119879

119873) + (B

3avg minus119879

119873)


119873) + (D

3avg minus119879

119873)

(2)






Table 2 1198719



119878119873 ratioA B C D1198771

1198772

11987731198771015840

1

1198771015840

2

1198771015840




1198712

1198713

1198712

-1198711

1198713

-1198712

1198711

1198712

1198713

1198712

-1198711

1198713

-1198712







1

09

08

07

06

05

04

03

02

01

0

Ratio

of p

H

10 20 30 10 20 30

A B8 10 12

C

900

1000

1100

D

0

minus1

minus2

minus3

minus4

minus5

SN

ratio

pHSN ratio




Table 4 ANOVA table















2O3 2450 Fe

2O3 3192 SiO

2 3450

TiO2 253 Na





Na2CO3+ SiO

2997888rarr Na

2SiO3+ CO2

(3)


2SiO3+H2O (4)



3Al2O3+ 2SiO

2997888rarr 3Al

2O3sdot 2SiO

2(6)



20 30 40 50 60 70 80 90

Cou

nts

0

100

200

300

400

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3














4 Conclusion



References
























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








119860(119861119862



1 1198772 and 119877

3) obtained












pH value 11987710158401

11987710158402

and 11987710158403




119884opt =119879

119873+ (A1avg minus119879

119873) + (B

3avg minus119879

119873)


119873) + (D

3avg minus119879

119873)

(2)






Table 2 1198719



119878119873 ratioA B C D1198771

1198772

11987731198771015840

1

1198771015840

2

1198771015840




1198712

1198713

1198712

-1198711

1198713

-1198712

1198711

1198712

1198713

1198712

-1198711

1198713

-1198712







1

09

08

07

06

05

04

03

02

01

0

Ratio

of p

H

10 20 30 10 20 30

A B8 10 12

C

900

1000

1100

D

0

minus1

minus2

minus3

minus4

minus5

SN

ratio

pHSN ratio




Table 4 ANOVA table















2O3 2450 Fe

2O3 3192 SiO

2 3450

TiO2 253 Na





Na2CO3+ SiO

2997888rarr Na

2SiO3+ CO2

(3)


2SiO3+H2O (4)



3Al2O3+ 2SiO

2997888rarr 3Al

2O3sdot 2SiO

2(6)



20 30 40 50 60 70 80 90

Cou

nts

0

100

200

300

400

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3














4 Conclusion



References
























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Table 2 1198719



119878119873 ratioA B C D1198771

1198772

11987731198771015840

1

1198771015840

2

1198771015840




1198712

1198713

1198712

-1198711

1198713

-1198712

1198711

1198712

1198713

1198712

-1198711

1198713

-1198712







1

09

08

07

06

05

04

03

02

01

0

Ratio

of p

H

10 20 30 10 20 30

A B8 10 12

C

900

1000

1100

D

0

minus1

minus2

minus3

minus4

minus5

SN

ratio

pHSN ratio




Table 4 ANOVA table















2O3 2450 Fe

2O3 3192 SiO

2 3450

TiO2 253 Na





Na2CO3+ SiO

2997888rarr Na

2SiO3+ CO2

(3)


2SiO3+H2O (4)



3Al2O3+ 2SiO

2997888rarr 3Al

2O3sdot 2SiO

2(6)



20 30 40 50 60 70 80 90

Cou

nts

0

100

200

300

400

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3














4 Conclusion



References
























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Table 4 ANOVA table















2O3 2450 Fe

2O3 3192 SiO

2 3450

TiO2 253 Na





Na2CO3+ SiO

2997888rarr Na

2SiO3+ CO2

(3)


2SiO3+H2O (4)



3Al2O3+ 2SiO

2997888rarr 3Al

2O3sdot 2SiO

2(6)



20 30 40 50 60 70 80 90

Cou

nts

0

100

200

300

400

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3














4 Conclusion



References
























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




20 30 40 50 60 70 80 90

Cou

nts

0

100

200

300

400

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3

CE-26

Al 2

SiO5

NaA

lSi 2

O6 A

lFeO

3 N

aAlO

2

Fe2O3

Al 2

SiO5 C

a 2Si

O4

Al 2

SiO5

Al 2

SiO5 F

e 2O3 C

a 2Si

O4 N

aAlO

2

Al 2

O3 A

l 2Si

O5 C

a 2Si

O4 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

NaA

lO2

Al 2

SiO5 F

e 2O3 T

iO2

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 C

a 2Si

O4 N

aAlO

2

AlF

eO3 T

iO2 N

aAlO

2

Al 2

SiO5

AlF

eO3

Al 2

SiO5 N

aAlS

i 2O6 F

e 2O3 A

lFeO

3 T

iO2 N

aAlO

2

Al 2

O3 A

l 2Si

O5 F

e 2O3 T

iO2 C

a 2Si

O4 N

aAlO

2

Ca3A

l 2(S

iO4) 3

Al 2

SiO5 A

lFeO

3 N

aAlO

2

NaA

lSi 2

O6 F

e 2O3 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 F

e 2O3 T

iO2 C

aOA

l 2O3 F

e 2O3

Al 2

SiO5 A

lFeO

3 C

a 3A

l 2(S

iO4) 3

Al 2

SiO5 C

a 3A

l 2(S

iO4) 3














4 Conclusion



References
























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








4 Conclusion



References
























CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article an alternative to clay in building...

Documents