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इंटरनेट मानक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. “जान1 का अ+धकार, जी1 का अ+धकार” “प0रा1 को छोड न’ 5 तरफ” Mazdoor Kisan Shakti Sangathan Jawaharlal Nehru “The Right to Information, The Right to Live” “Step Out From the Old to the New” IS 12446 (2007): Bentonite for use in foundries [MTD 14: Foundry] “!ान $ एक न’ भारत का +नम-ण” Satyanarayan Gangaram Pitroda ““IInnvveenntt aa NNeeww IInnddiiaa UUssiinngg KKnnoowwlleeddggee”” “!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता हहहहै””ै” Bhartṛhari—Nītiśatakam “Knowledge is such a treasure which cannot be stolen” IS 12446:2007 Indian Standard BENTONITE FOR USE IN FOUNDRIES — SPECIFICATION ( First Revision ICS 81,080 @ BIS 2007 BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG NEW DELHI 110002 November 2007 Price Group 4 Foundry and Steel Casting Sectional Committee, MTD 14 FOREWORD ThisIndian Standard (FirstRevision) wasadopted bytheBureauofIndian Standtids, afterthedraft finalizedbythe FoundryandSteelCastingSectionalCommitteehadbeenapprovedbytheMetallurgicalEngineeringDivisionCouncil. This standard was first published in 1988. Foundry grade bentonite was earlier covered in IS 6186: 1971 “’Specification for bentonite’ covering the requirements and the methods of sampling andtest forbentonite for use inchemical industries, oil well drilling andfoundry.Itwasrevisedin 1986,intherevisedstandard,thematerial usedforfoundry wasdeleted. Subsequently it was felt that a separate Indian Standard should be formulated on the foundry grades of bentonite, since the foundry grades bentonite have different characteristics and problems. Bentonite is a natural product. It is ground in mills after treatment/blending to very fine powder. Bentonite is basically composed of the mineral montomorillonite which occurs in extremely fine particles. Bentonite also cvntainsbeidelite (montomorillonite family) asprincipal mineral. Bentonite ismixed withsandtoimpartplasticity and strength to it in the presence of moisture. The fine particle size and high moisture absorption, that is, high swelling property of bentonite give bonding strength or adhesion to the mass of sand grains. Thisstandardkeepsinviewthequalityofbentoniteavailableinthecountryandknowntobecommercially exploited. Sodium base bentonite deposits are available in: a) Wandh village near Manvi, Kutch, GujaraG b) Barmer, Aaklee, Visala and Hathi KiDhani, Rajasthan; and c) Mahua, Lakhnoka, Malpur and Bhawnagar region inGujarat. Calcium base bentonite deposits are available in: a) Bakuda andTinpahar inBihar, b) Rajula and Bhavnagar in Gujarat, c) Madras suburbs, and d) Kashmir. Important relative differences inproperties of sodium andcalcium based bentonites are given below: Properties Predominant Exchangeable Cation (Total.ofInterlayer and Extraneous) - / % Sodium (Na) Calcium (Ca) (1) (2) (3) Swelling High LOW Plasticity Lower Higher Rigidity of Lower Higher Absorbed water layer (first three (first four molecular layer) molecular layer) Liquid limit Higher Lower Green strength Slightly lower Higher Dry strength High Low Hot strength Veryhigh Low For the purpose of deciding whether a particular requirement of this standard is complied with the final value,observed orcalculated, expressing theresult ofatestoranalysis, shall berounded off inaccordance with IS2:1960 ‘Rules for rounding off numerical values (revised)’. The number of significant places retained inthe rounded off value should be the same asthat ofthe specified value inthis standard. IS 12446:2007 Indian Standard BENTONITE FOR USE IN FOUNDRIES — SPECIFICATION ( First Revision) 1SCOPE 5PROPERTIES This standard covers the requirements for bentonite 5.1 Bentonite is to be of uniform quality and when used asa binder for preparing the moulding sand etc tested in accordance with the methods specified in infoundries. Annex A, it is to conform with the values given in Table 1. 2REFERENCES 5.2Physical Condition The standards listed below contain provisions, which through reference in this text constitute provisions of Veryfinedry powder with creamy feel, free from dirt this standard. At the time of publication, the editions Iumps, grits, sand and other foreign materials and indicated were valid. All standards are subject to impurities. Colour iscreamy yellowish, palebuff,grey revisionandpartiestoagreement basedonthisstandard tolight grey. areencouragedtoinvestigatethepossibility ofapplying 5.3 Chemical Composition the most recent editions of the standards indicated below: Thechemical formula ofbentonite is(Al,Felc, MgO,J Si ~010(OH)2 Na plus Ca0,33and its approximate 1SNo. Title 1070:1992 Reagent grade water (thirdrevision) chemical composition in percentage is: 1387:1993 General requirements for supply of SiOz 45-65 CaO 1-5 metallurgical materials (second AlzO~ 14-25 NazO 0.4-2.51 revision) FeO +FezO~ 3-? 1$0 0.5-1.5 3018:1977 Specification forstandardsilicasand for raw material testing infoundries MgO 2-3.5 TiOz 0.8-2 10214:1982 Methods of sampling bentonite NalCa 4.55-2.5 (Nabase) 0.16-0.000 3DESIGNATION (Ca base) It isto bedesignated as; 5.4 Chemical and Physical Properties Bentonite Physical and chemical properties of all thegrades are 00 — Denotes theMBvalue (Methylene Blue given inTable 1. Valuein mg of MB/g of bentonite) 100 — Denotes the predominant action say Specific gravity 2.0-2.2 Sodium – Na and Calcium — Ca 6SUPPLY OF BENTONITE Example: General requirements relating to the supply of a) Bentonite – Na 450 – IS 12446 bentonite isto conform tothe conditions laid down in b) Bentonite - Ca 230 -IS 12446 IS 1387. 4GRADES 7SAMPLING 4.1 Sodium base bentonite is covered in two grades, 7.1 Procedure namely: Representative sample is to be drawn in accordance a) Na450 with the procedure given in IS 10214. The following b) Na 370 procedure is to be followed if agreed to between the manufacturer and the purchaser. 4.2 Calcium base bentonite is covered in one grade, namely,Ca220. 1 IS 12446:2007 Table 1Requirements for Bentonite (Clauses 5.1 and 5.4) S1No. Characteristics BentoniteGrade MethodsofTest, ~ Refto clause Sodium base Catcium base A ,- ? Na450 Na370 Ca220 (1) (2) (3) (4) (5) (6) O Fineness a) Dry Maximum percentretention by massonISsievesizes 3 3 3 A-2 125micron 63micron 7 7 7 pan 90 90 90 b) Wet Maximum percent retention byweightonISsieve 5 5 5 45micron ii) Moisture content 6-12 6-18 5-12 A-3 iii) pHat2percent suspension 9.0-10.5 9.0-10.5 8.0-9.0 A-4 iv) Liquid limit(SFSA Method) 800-900 600-800 100-200 A-5 v) Gelformation index, inml 60,Min 50,Min 30,Min A-6 vi) Freeswelling capacity, inml 36,Min 28,Min 10,Min A-7 vii) Gelling time, inmin 1,Max 2,Max 5,Max A-8 viii) Swelling index,inml 33,Min 25Min 10,A4in A-9 ix) Cation exchange capacity: a) mgofMB/g ofbentonite 450,Min 370,Min 220,Min A-lo b) meqofMB/100 gofbentonite 120,Min 98,Min 59,Min x) Conefusiontemp.‘C 1300 1300 1175-1225 A-II xi) Bonding properties Bentonite 7percent moisture percent Highsilica sandAGS-250to . 355micron CCS,g/cm2 1000,Mirr 1000, Min 800,&tin A-12 CCS,g/cm2 500,Min 500,Min 400,Min DCS,g/cm2 5000, Min 5000, Min 5000, Min Shatter index,percent 75-80 75-80 55-60 xii) Chemical composition 12.1,Repla ceable CA++ 0.7,Max 0.7,Max 1.5-3.0 A-13 asCaObymassinpercent a) Na2O,K20 3-2.5percent 3-2.5percent0.75-3 percent b) Na2O/CaO 1.0-1.7 0.1-0.4 xiii) LOI 10,Max 10,Max 10,Max A-14 xiv) Na+/Ca++ 2.5-4.5 2.5-4.5 0.001-0.4 A-13 quantities ofbantonite istobetaken andmixedthough Lot Size No. ofBags Method ofSampling toform acomplete sample of about 1kg. (Bags) tobe Selected . for Sampling 8 PACKING AND MARKING N n Up to 25 3 Nln=r 8.1 Packing 26-50 4 Bentonite is to be supplied in water/moisture proof 51-100 5 Count 1,2, 3up to rand 40 kg sealed bags of one of the following material. 101-200 6 so on where ris integral a) Polythene line hessian bag :Fresh part ofN/n, b) Polythene line hessain bag : Second hand 201 and above 8 Take all the rth bags to c) High density polyurethane :Fresh bags form the sample d) High density polyurethane :Second hand From each ofthebags selected above, aportion ofthe bags bantonite about 40 g isto bedrawn with the help of a NOTE—Emptybagsofinsecticide/pesticide supplynottobe samplinginstrument. Outoftheportion eachbag,equal used. 2 IS 12446:2007 8.2 Marking 8.2.2 BIS Certification Marking 8.2.1 All bags are to be clearly marked with the The material may also be marked with the Standard following: Mark. a) Designation; 8.2.2.1 The use of the Standard Mark is governed by b) Batch No. and lot No.; theprovisions of the Bureau of Indian Standards Act, 1986and the Rules and Regulations made thereunder. c) Brand name; The details of conditions under which the licence for d) Manufacturer’s name, trade-mark; the use of the Standard Mark may be granted to e) Net weight. Marking should not disfigure by manufacturers orproducers, maybe obtained from the water or sun-rays; and Bureau of Indian Standards. f) Manufacturing date. ANNEX A (Clause 5.1) METHODS OF TEST FOR BENTONITE A-1 BENTONITE AND REAGENTS A-1.3 QuaIity of Reagents A-1.l Bentonite Unlessspecified otherwise purechemicals anddistilled water (seeIS 1070) is tobe employed in the tests. Bentonite is.highly hydroscopic. Hence either the NOTE— ‘Purechemicals’ shall means chemicals thatdonot bentonite should betaken immediately after drying to contain impurities whichaffectstheresults ofanalysis. constant weight for the tests or the weight of the bentonite is to be adjusted for moisture in as it is A-2 FINENESS supplied condition. Therefore, wherever weight of A-2.1 Dry Fineness dried bentonite iswritten the weight istobecorrected A-2.1.1 Dry about 200 g of the bentonite in the tared formoisture andthiscorrected wei ght ofthebentonite, porcelain dish covered with a watch glass uniformly inasit issupplied condition, isto be taken. over the bottom of the dish. Keep it in air oven A-1.2 Procedure maintained at 105”C&2°C for 2 h. Cool in desicator andweightillconstant weight.Take50gfromthedried Moisture is first found out. Therefore, weight of sample and sieve it in the normal manner using 125 undried bentonite iscalculated for the weight ofdried micron, 63 micron IS sieves and pan for 15min. bentonite whch isreferred for all tests. A-2.1.2 Weightheamount ofbentonite retained onthe A-1.2.1 Calculation IS sieves 125 micron, 63 micron and pan. Report the results as percentage weight of bentonite retained on WD Ww = these sieves. moisture ~ercent “A-2.2Wet Fineness 100 A-2.2.1 Procedure where Weighaccurately about 10gofthedried bentonite and WUD=mass of undried bentonite (that is, as place itin a500-ml capacity bottle and add gradually supplied condition), in g; and 350 ml of pure distilled water (7.0 pH). Shake the mixture thoroughly in a suitable shaking machine for WD= mass ofdried bentonite, in g. aperiod of 3h,giving atleast 30 complete inversions Moisture percent = Moisture percent of the supplied to the bottle per minute. The mixture thus prepared bentonite under test (seeA-3). shall be fluid and free from lumps. 3 IS 12446:2007 A-2.2.2 Sieve this mixture through IS sieve size45 exactly 100ml of distilled water atroom temperature micron.Washtheresidue onthesieve,dryitandweigh. in a plastic beaker. Add approximately half of the Reporttheresultsaspercentage weightofthebentonite quarter (3.75 g) and mix for 90 s. Remove any dry retainedonISsievesize45micron. Drying temperature bentonite adhering tothebeaker well,addtotheslurry istobe within 105–110”C. It shall not exceed 110”C andremix for 90s. The consistency ofthe slurry may under anycircumstances. be too thin at this stage (indicated by previous experience) and ifso,carefully add more bentonite in A-3 MOISTURE CONTENT smallamounts togiveasuitable consistency, following the prescribed procedure. A-3.1 Procedure Following the 90 s mixing cycle, promptly add the Weighaccurately about 10gof the material inatared slurry to the cup with a spatuala. A good contact porcelain dish, covered with awatch glass. Spread the between the slurry and the surface of the cup is material uniformly over the bottom of the dish. Keep essential. The amount of slurry required is indicated itinairovenmaintained at 105k 2°Cfor2h.Coolthe by the line scrib~d on the inner surface of the cup. dishinadesicator end weigh. Repeat theoperation till Smooth the slurry until it is level with the line at all constant weight is obtained. points. This step, probably more than any other, will affect the reproducibility of the test. Make a groove A-3.2 Calculation with the scriber (see Note 1under A-5.2.3). Remove allthebentonite remaining onthe scriber andreturn it Loss ondrying, percent by mass = 100’~ tothebeaker.Turnthecrank atarate about2,counting UD the blows necessary to close the groove for adistance of 13cm (see Note 2under A-5.2.3). where Wt = loss in weight, ing; and If the number of blows is between 1 and 8, carefully Wu~= massoftheundried bentonite taken fortest, add 1 to 3 spatula of bentonite and repeat the 90 s ing. mixing procedure. Then again determine the number ofblowsneededtoclosethegrooveasdescribedabove. A-4 DETERMINATION OFpH VALUE Note the number of blows it between 9 and 20 and repeat until the number isconstant within +2 blows. A-4.1 Procedure Following each sequence, return asmuch oftheslurry Take2.0gofthedriedbentonite, add 100mlofdistilled as possible to the beaker. Clean the cup with a water @H= 7.0) and mix thoroughly. Determine the dampened cloth and dry thoroughly. pHofsuspensionbymeansofasuitablepH meterusing After aconstant reading of+ 2 blows is obtained (in glass electrode. The test shall be carried out at therange of 9 to 20 blows), the weight of remaining 27 ~2°C. unmixed bentonite is determined (see Note 3 under A-4.1.1 Always test distilled wa ter against buffer A-5.2.3). Subtracts thzis weight from theoriginal 30g solution before beginning any pH testing. Distilled of bentonite to determine the number of grams of water canabsorb enough COZfrom the atmosphere to bentonite added to the 100 ml of water. This value is ‘acidify. Ageing of clays will vary the pH value. The ‘B’inthe equation. Return the slurry into the beaker. calorimetric method (litmus paper, etc) is not recommended since results cannot be measured ~+ P-B precisely. W,o= 100XIOO ~ P-B -— A-5 DETERMINATION OF LIQUID LIMIT 100 A-5.1 The liquid limit of abentonite, determined with where the special device, is the water content in a bentonite slurry which will provide enough plasticity toclose a WZO = water content for (9 to 20blows); prescribed groove in 25 blows. w = mass of water used = 100g; B = mass of bentonite added, ing; and A-5.2 Procedure P = moisture content ofbentonite, inpercent. A-5.2.1 Determination of water content (WZO) of A-5.2.2 Determination of WaterContent ofBentonite bentonite requiring 20 blows to cIose the groove — Requiring 30-40 Blows to Close the Groove Accurately weigh out ofdried bentonite andsplitinto four approximately equal parts. Thoroughly mix for Carefully add 1to3more spatulas ofbentonite tothe 90 s a quarter portion (7.5 g) of the bentonite with slurry in the beaker. Experience with the particular 4 IS 12446:2007 bentonite being testing will indicate the amount dispersion of bentonite particles. The variation in required. Repeat the 90 s mixing procedure and shaking or thorough mixing and time of mixing gives determine the number ofblows necessary toclose the variations inthe results from laboratory tolaboratory. groove as described above. The number of blows A-7 FREE SWELLING CAPACITY required should be in the range of 30-40. Repeat the operation untilthenumber isconstant within* 2blows A-7.1 Procedure andnotethenumber.Determine theweightofbentonite Accurately weigh 2 g of dried bentonite powder remaining and substract this weight from the original (moisture free) and divide the quantity into more than 30gofclay todetermine thetotal weight ofbentonite added to the water. Determine the water content W40 20 approximately equal parts. Take each part by the of this more viscous mixture by means of the above tip of a spoon and sprinkle into a graduated cylinder equation. containing 100ml distilled water (PH = 7.0). Care is taken to see that every particle of bentonite is wetted A-5.2.3 Determine theLiquid Limit (W~ and settled while sprinkled each time till all the 20 Plotonsemi-logarithemic paper thewatercontentW28 partsareover.Generally thetime taken forcompleting andW40 against thecorresponding number of blows. thetestis1to2h.Theresult willberecorded afterone The number of blows is plotted on the logarithmic hour and after 24 hfrom completion of test by noting scale(ordinate). Connect thetwopoints withastraight the volume of gel formed. line.Thepoint where theaxis for 25blows crosses the The free swelling capacity is measured in terms of lineconnecting thepoints WzgandWJOcorresponds to volume, in ml, of gel formed. theliquid limit. A-8 GELLING TIME NOTES 1Thescriber supports should be adjusted sothat the scriber A-8.1 Procedure light]ytouchesthebottomof thecup,thepapergroove being onewhichexposesthebottomofthecupthrough-outitslength. Take 10 ml of distilled water in a 2.5 cm dia test Adjustmentofthecuptoprovide therequired onecentimetre tube and add 2.5 g of dried bentonite (dried to clearancebetweenthebottom ofthecupofitshighestposition constant weight at the temperature of 105-110”C). and the striking base should be done frequency taking care thatthescriberisnotoffcentre thisstriking thecupunevenly. Shake the mixture well and then add immediately 2Theclosingofthegrooveshallbetakenasthepointatwhich further 15ml of distilled water. Close the mouth of thebottomofthegroovejoints tocovertheexposedportionof test tube by rubber cork and shake well. Check the thecupfor 13cmalongthelength ofthegroove.Thegroove thixotrophy of the bentonite by tilting the test tube. I shouldnotbeexpectedtocloseentirely, thatisalongitsentire lengthofitsfulldepth.Only 13cmclosesoversothatthecup Time inminutes after which thebentonite slurry fails bottomcannotbeseen. to flow ever after keeping test tube in (-) 45° tilted 3Bythistime, approximately 14go ftheoriginat 30ghave position for 1min. beenused. A-9 SWELLING INDEX A-6 GEL FORMATION INDEX A-9.1 Procedure A-6.1 Procedure Add 0.2 g, 0.25 g, 0.3 g, 0.35 g, 0.4 g, 0.5 g, 0.6 g, Weighaccurately 1.4gofdriedbentonite powder dried 0.7 g, 0.8 g, 0.9 g and 1.00 g of dried sample of toconstant weight (at 105°C); 0.2gmagnesium oxide, bentonite (moisture free) indifferent dulymarked test A.R. quality (dried at 105”C) and 2.6 gof anhydrous tubes of 15cmdia.Add 10mlof distilled waterineach alumina, A.R. quality (dried at 105”C) in astoppered test tube. Shake the mixture well of each test tube to 100 ml measuring cylinder. Dry shake the mixture ensure fulldispersion ofbentonite. Keepthetesttubes thoroughly for5to 10min.Add50mlofdistilledwater for 24 h for full swell. The suspended material with andshakevigorously forthorough mixing.Addfurther proper ratio will not flow out of the test tube when water toread 100ml and shake vigorously for 1hour gently tilted to(-)45° and shallremain stillforatleast for the rough mixing. Allow the contents of the 1min.The swelling index istheratio ofwater (10ml) measuring cylinder to stand for 24 h. Measure the to minimum mass of bentonite (g) at which the volume of the supernatant liquid and subtract it from suspension just fails to flow. 100ml.This will give roughly the gel index value of bentonite inpercent. 100ml of water Shaking the mixture thoroughly in a suitable shaking ‘welling ‘ndex = Weight of bentonite (g) machineforthegiventimeisessential.Theshearforces applied while shaking has direct bearing on the Itisanapproximate measure ofthe limit ofhydration. 5