IS 1760-6: Chemical Analysis of Limestone, Dolomite and Allied Materials, Part 6: Determination of Free Silica

8 Pages·2001·0.97 MB·English

by  Bureau of Indian Standards

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IS 1760-6 (2001): Chemical Analysis of Limestone, Dolomite
and Allied Materials, Part 6: Determination of Free Silica
[MTD 13: Ores and Raw Materials]
“!ा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””ै”
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Indian Standard
CHEMICAL ANALYSIS OF LIMESTONE,
DOLOMITE AND ALLIED MATERIALS
PART 6 DETERMINATION OF FREE SILICA
( First Revision)
ICS 81.080

0 BIS 2001
BUREAU OF IN DIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002

May 2001 Price Group 1
/
Methods of Chemical Analysis of Ores, Minerals and Allied Materials for Metallurgical Industry Sectional
Committee, MTD 29
FOREWORD
This Indian Standard (Part 6)(First Revision) wasadopted bytheBureau ofIndian Standards, after the draft
finalized bytheMethods ofChemical AnalysisofOres,MineralsandAlliedMaterials forMetallurgical Industry
Sectional Committee had beenapproved bytheMetallurgical Engineering Division Council.
IS 1760 was first published in 1962. It covers the determination of different elements in various grades of
minerals likelimestone, dolomite, calcite andmagnesite. Italsocovers themethods formagnesite refractories.
The committee decided torevise this standard intodifferent parts covering determination ofeach element ina
separate part, which onpublication would supersede thedetermination of thatelement given inIS 1760:1962.
ThisPartcovers determination offreesilicabygravimetric method. The otherpartsintheseriesareasfollows:
Part 1 Loss onignition
Part 2 Determination of silica
Part 3 Determination of iron oxide, alumina, crdciumoxide and magnesium oxide
Part 4 Determination of carbon dioxide
Part 5 Determination ofchlorides
For thepurpose ofdeciding whether aparticular requirement ofthisstandard iscomplied with, thefinal value,
observed or calculated, expressing the result of a testoranalysis, shallberounded off inaccordance with
IS 2:1960 ‘Rulesforrounding offnumericrdvalue(revised)’. Thenumber ofsignificant places retained inthe
rounded off value should bethesameasthatofthe specified value inthis standard.
.
IS 1760 (Part 6) :2001
Indian Standard
CHEMICAL ANALYSIS OF LIMESTONE,
DOLOMITE AND ALLIED MATERIALS
PART 6 DETERMINATION OF FREE SILICA
(First Revision)
1 SCOPE isdissolved inahotsolution ofsodium hydroxide but
thefree silicaisunaffected.
This standard (Part 6) describes the method for
determination offreesilicainlimestone, dolomite and 5.2 Reagenta
allied materials.
5.2.1 Dilute Hydrochloric Acid, 1:1 (v/v).
2 REFERENCES
5.2.2 Potassium Bisulphate or Potassium
The following standards contain provisions which Pyrosulphate, solid.
through reference in this text, constitute provision of
5.2.3 Sodium Hydroxide, pellets.
this standard. At the time of publication, the editions
were valid. All standards are subject torevision ,and 5.2.4 Dilute Sulphuric Acid, 1:1 (v/v).
parties to agreements based on this standard are
5.2.5 Hydrojluoric Acid, 40 percent (v/v).
encouraged to investigate the possibility of applying
the most recent editions of the standards indicated 5.3 Procedure
below:
5.3.1 Weigh approximately 5.0 g (accurately
ISNo. Title weighed upto fourth decimal place) of the prepared
sample ina400 mlbeaker, moisten itwith little water
1070:1992 Reagent grade water(third revision)
and add25mlofdilute hydrochloric acid (1: 1),and
2109:1982 Methods of sampling of limestone,
heattoboil. Filtertheinsoluble matter including silica
dolomite and allied materials
and wash several times with hot water. Discard the
3 SAMPLING filtrate. ,

3.1 The sample shall be drawn and prepared in 5.3.2 Transfer the paper containing the insoluble
accordance with IS 2109. matter in a platinum crucible and char the paper
without inflaming at low heat. Increase the
3.2 Grind 5to 10gofthe sample3.1 sothat itpasses
temperature tobum off thecarbon, but do notexceed
through IS sieve 150 microns opening. Dry to
600 * 50°C. Cool and add approximately 3-5 g of
constant mass at 105* 2°C and useitfor thepurpose
fused and powdered potassium bisulphate or
ofchemical analysis.
potassium pyrosulphate in the platinum crucible, and
4 QUALITY OF REAGENTS blend thoroughly with a small spatula. Fuse
thoroughly over agasburner, first bygradual heating
Unless specified otherwise, analytical grade reagents
toprevent lossofsulphur trioxide andthentoahigher
and reagent grade water (see IS 1070) shall be
temperature withoccasional stirring tilltheclear melt
employed for the test.
isobtained (seeNote).
5 DETERMINATION OF FREE SILICA BY NOTE—Donotcontinueheatingtoapointwheresaltsbegin
GRAVIMETRIC METHOD tofreezeon topof the melt andon thesidesofthecrucible
becauseofthedifficulty ofsubsequentsolution.
5.1 Outline ofthe Method
5.3.3 Cool thecrucible and itscontents and dissolve
After dissolution of a large sample of limestone or the melt by heating with 150to 200 ml of water ina
dolomite, in the acid, the insoluble matter including 400 ml beaker. To the warm solution cautiously and
silica is separated, ignited at low temperature and slowlywithstirring addapproximately 12gofsodium
residueleftisfusedwithpyrosulphate. Thesilicicacid hydroxide pellets, a few at a time to dissolve the
liberatedfromtheclayminerals intheinsoluble matter precipitated silicic acid (see Note). Digest on a hot
plate for 30minutes at80to 90”C.

1
.. , ,.,
IS 1760 (Part 6): 2001
NOTE—Freesilicaisnottransformedtosilicicacidbyfision havebeen improperly accomplishedand hencediscard and
andisnotaffectedbythecaustictreatment. repeattheprocedm specifiedin5.3.1to5.3.4.
2 Ckmsionatly thefreesilicaiscontaminated bycompounds
5.3.4 Filter quickly, using a close-textured filter notdecomposedduringfusionordissolvedinthesubsequent
paper.Thoroughly scrubandwashthebeaker withhot treatment. Theresiduethenistreatedwith hydrofluoricacid
water. Wash thefilter paper anditscontentstentimes andsulphuricand silica expelled.
withhotwater,fivetimes withhotdilutehydrochloric 5.4 Calculation
acid(1:1),todissolve ironandother contaminants of
Calculate thepresent free silica asfollows:
the’freesilica andfinally five times withhotwateror
A–B)x1OO
until free of acid. Transfer the paper and residue toa Free silica, percent bymass= ~
taredplatinum crucible. Ignite at 1000”C toconstant m
mass,Cool in adesiccator andweigh (A). where
A= mass in g, of crucible and insoluble
535 To the ignited and weighed residue (A) add 2
residue,
dropsofdilutesulphuric acid(l: 1)andapproximately
10 ml of hydrofluoric acid. Evaporate to dryness, B= mass in g, of crucible after
igniteand weigh (B)(.reeNotes 1and 2). hydrofluorization; and
NOTES m= massing,ofthe sample taken<
1 Ifthemassoftheresidueexceed0.001g@ennination may

2
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This Indian Standard has been developed from Doc : No. MTD 29(3896)
.
Amendments Issued Since Publication
Amend No. Date of Issue Text Affected’
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