ASTM C146-94a(2009)
(Test Method)Standard Test Methods for Chemical Analysis of Glass Sand
Standard Test Methods for Chemical Analysis of Glass Sand
SIGNIFICANCE AND USE
These test methods can be used to ensure that the chemical composition of the glass sand meets the compositional specification required for this raw material.
These test methods do not preclude the use of other methods that yield results within permissible variations. In any case, the analyst should verify the procedure and technique used by means of a National Institute of Standards and Technology (NIST) standard reference material or other similar material of known composition having a component comparable with that of the material under test. A list of standard reference materials is given in the NIST Special Publication 260, current edition.
SCOPE
1.1 These test methods cover the chemical analysis of glass sands. They are useful for either high-silica sands (99 % + silica (SiO2)) or for high-alumina sands containing as much as 12 to 13 % alumina (Al2O3). Generally nonclassical, the test methods are rapid and accurate. They include the determination of silica and of total R2O3 (see 11.2.4), and the separate determination of total iron as iron oxide (Fe2O3), titania (TiO2), chromium oxide (Cr2O3), zirconia (ZrO2), and ignition loss. Included are procedures for the alkaline earths and alkalies. High-alumina sands may contain as much as 5 to 6 % total alkalies and alkaline earths. It is recommended that the alkalies be determined by flame photometry and the alkaline earths by absorption spectrophotometry.
1.2 These test methods, if followed in detail, will provide interlaboratory agreement of results.
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Designation: C146 − 94a(Reapproved 2009)
Standard Test Methods for
Chemical Analysis of Glass Sand
This standard is issued under the fixed designation C146; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 These test methods cover the chemical analysis of glass
responsibility of the user of this standard to establish appro-
sands. They are useful for either high-silica sands
priate safety and health practices and determine the applica-
(99%+silica (SiO )) or for high-alumina sands containing as
bility of regulatory limitations prior to use.
much as 12 to 13% alumina (Al O ). Generally nonclassical,
2 3
the test methods are rapid and accurate. They include the
2. Referenced Documents
determination of silica and of total R O (see 11.2.4), and the
2 3
2.1 ASTM Standards:
separate determination of total iron as iron oxide (Fe O ),
2 3
C169Test Methods for Chemical Analysis of Soda-Lime
titania (TiO ), chromium oxide (Cr O ), zirconia (ZrO ), and
2 2 3 2
and Borosilicate Glass
ignition loss. Included are procedures for the alkaline earths
C429Test Method for Sieve Analysis of Raw Materials for
and alkalies. High-alumina sands may contain as much as 5 to
Glass Manufacture
6% total alkalies and alkaline earths. It is recommended that
D1193Specification for Reagent Water
the alkalies be determined by flame photometry and the
E11Specification forWovenWireTest Sieve Cloth andTest
alkaline earths by absorption spectrophotometry.
Sieves
1.2 These test methods, if followed in detail, will provide
E50Practices for Apparatus, Reagents, and Safety Consid-
interlaboratory agreement of results.
erations for Chemical Analysis of Metals, Ores, and
NOTE 1—For additional information, see Test Methods C169 and Related Materials
Practices E50.
E60Practice for Analysis of Metals, Ores, and Related
Materials by Spectrophotometry
1.3 The test methods appear in the following order:
2.2 Other Documents:
Procedures for Referee Analysis: Section
NISTSpecial Publication 260
Silica (SiO )—Double Dehydration 10
Total R O —Gravimetric 11
2 3
3. Significance and Use
Fe O ,TiO ,ZrO ,Cr O , by Photometric Methods and 12-17
2 3 2 2 2 3
Al O by Complexiometric Titration
2 3
3.1 These test methods can be used to ensure that the
Preparation of the Sample for Determination of Iron 12
chemical composition of the glass sand meets the composi-
Oxide, Titania, Alumina, and Zirconia
Iron Oxide (as Fe O ) by 1,10-Phenanthroline Method 13
2 3 tional specification required for this raw material.
Titania (TiO ) by the Tiron Method 14
Alumina (Al O ) by the CDTA Titration Method 15
3.2 These test methods do not preclude the use of other
2 3
Zirconia (ZrO ) by the Pyrocatechol Violet Method 16
methodsthatyieldresultswithinpermissiblevariations.Inany
Chromium Oxide (Cr O ) by the 1,5-Diphenylcarbo- 17
2 3
case, the analyst should verify the procedure and technique
hydrazide Method
used by means of a National Institute of Standards and
Procedures for Routine Analysis:
Technology(NIST)standardreferencematerialorothersimilar
material of known composition having a component compa-
Silica (SiO )—Single Dehydration 19
Al O , CaO, and MgO—Atomic Absorption Spec- 20–25 rable with that of the material under test. A list of standard
2 3
trophotometry
reference materials is given in the NIST Special Publication
Na O and K O—Flame Emission Spectrophotometry 26-27
2 2
260, current edition.
Loss on Ignition (LOI) 28
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
These test methods are under the jurisdiction of ASTM Committee C14 on contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Glass and Glass Products and are the direct responsibility of Subcommittee C14.02 Standards volume information, refer to the standard’s Document Summary page on
on Chemical Properties and Analysis. the ASTM website.
Current edition approved Nov. 1, 2009. Published January 2010. Originally Standard samples available from the National Institute of Standards and
approved in 1939 . Last previous edition approved in 2004 as C146–94a(2004). Technology are listed in U.S. Dept. of Commerce, NIST, Special Publication 260
DOI: 10.1520/C0146-94R09. (current edition), Washington, DC 20234.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C146 − 94a (2009)
4. Photometers and Photometric Practice 8.2 Thelaboratorysampleisreducedforanalysisto10to20
g by use of a small riffle with openings preferably of 6.4-mm
4.1 Photometers and photometric practice prescribed in
( ⁄4-in.) size. The analytical sample is then ground in an agate
these test methods shall conform to Practice E60.
mortar to pass a 150-µm (No. 100) sieve. If the laboratory
sampleasreceivedcontainsanylargeparticlesthatareretained
5. Purity of Reagents
on a 850-µm (No. 20) sieve, these shall be sieved out, crushed
5.1 Reagent grade chemicals shall be used throughout.
(withoutcontamination)soastopassthesieve,andthenmixed
Unless otherwise indicated, it is intended that reagents shall
back into the laboratory sample before riffling.
conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society, where such
9. Precision and Bias
specifications are available. Other grades may be used, pro-
9.1 Precision—The probable precision of results that can be
vided it is first ascertained that the reagent is of sufficiently
expected by the use of procedures described in these test
high purity to permit its use without lessening the accuracy of
methods is shown in the following tabulation. Precision is
the determination.
given as absolute error and is dependent on the quantity of the
5.2 Unless otherwise indicated, references to water shall be
constituent present as well as the procedure used.
understood to mean reagent water as defined by Type I, II, or
Probable Precision of Results, Weight %
III of Specification D1193.
Constituent Referee Analysis Routine Analysis
SiO (99 %) ±0.1 ±0.25
6. Concentration of Acids and Ammonium Hydroxide
SiO (85–90 %) ±0.1 ±0.25
(NH OH) R O (1 %) ±0.05 ±0.10
4 2 3
R O (10–15 %) ±0.1 ±0.15
2 3
6.1 When acids and ammonium hydroxide are specified by
Al O (1 %) ±0.05 ±0.10
2 3
Al O (10–15 %) ±0.1 ±0.1
name or chemical formula only, concentrated reagents of the
2 3
Fe O ±0.003 .
2 3
following percent concentrations are intended:
TiO ±0.005 .
Sp Gr % ZrO ±0.001 to 0.005 .
Cr O ±0.0001 to 0.001 .
2 3
Hydrochloric acid (HCl) 1.2 36 to 38 CaO . ±0.001
Hydrofluoric acid (HF) 1.2 48 to 51 MgO . ±0.001
Nitric acid (HNO ) 1.4 69 to 71 Na O . ±0.001
Perchloric acid (HClO ) 1.8 70 to 72 K O . ±0.001
4 2
Sulfuric acid (H SO ) 1.8 95 to 98
2 4
9.2 Bias—Standard reference materials or other similar
Ammonium hydroxide (NH OH) 0.9 28 to 30
materials of known composition should be analyzed whenever
6.2 Concentrations of diluted acids and NH OH, except
possible to determine the bias of the results.
when standardized, are specified as a ratio stating the number
of volumes of the concentrated reagent to be added to a given
PROCEDURES FOR REFEREE ANALYSIS
number of volumes of water, as in the following example: HCl
(1+99) means 1 volume of concentrated HCl (sp gr 1.19)
10. Silica (SiO ) by the Double Dehydration Method
added to 99 volumes of water.
10.1 Weigh 1.000 g of the powdered sample and 2.0 g of
anhydrous sodium carbonate (Na CO ) into a clean 75-mL
2 3
7. Filter Papers 6
platinumdish(Note2);mixwellwithaplatinumorNichrome
7.1 Throughout these test methods, filter papers will be
wire.Tap the charge so it lies evenly in the bottom of the dish.
designated as “coarse,” “medium,” or “fine” without naming Cover evenly with an additional 1.0 g of Na CO . Cover with
2 3
brands or manufacturers. All filter papers are of the double-
the platinum lid and heat first at a dull red heat over a clean
acid-washed ashless type. “Coarse” filter paper refers to the oxidizing flame; gradually raise the temperature until a clear
porositycommonlyusedforthefiltrationofaluminumhydrox-
melt is obtained. Properly carried out, little or no spattering
ide. “Medium” filter paper refers to that used for filtration of
should occur, and the fusion can be performed in 3 to 4 min.
calcium oxalate, and “fine” filter paper to that used for barium
When melted, rotate the melt to spread it evenly over the
sulfate.
bottom and lower sides of the dish, gradually withdrawing
from the flame. Cover and cool to room temperature. During
8. Preparation of Sample
fusion, the dish should be handled at all times with platinum-
tipped tongs and the fusion performed with a platinum (pref-
8.1 General Considerations—The acquisition and prepara-
erably 90% platinum and 10% rhodium alloy) or silica
tion of the sample shall follow the principles stated in Test
triangle.
Method C429.
NOTE 2—To obtain accurate repeat weighings, platinum ware must be
kept scrupulously clean on the outside of the vessel as well as on the
inside. It should be polished brightly with fine, round grain sand and
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia Requirements for sieves are given in ASTM Specification E11.
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, NichromeisaregisteredtrademarkoftheDriver-HarrisCo.,308MiddlesexSt.,
MD. Harrison, NJ 07029.
C146 − 94a (2009)
protected from dirty surfaces. It is recommended that porcelain plates be
determined separately. It also helps to identify an unknown
usedforcoolingfusions,andthatplatinumbesetonpapertowelsorother
sand as a low- or high-alumina type.
clean material during filtration.
11.2 Procedure:
10.2 Add 20 to 25 mL of HCl (1+1) under the platinum
11.2.1 Weigh a suitable weight of sample into an 80- to
cover and digest on a steam bath or hot plate until the melt has
100-mLplatinumdish,moisten,andadd10mLofHFforeach
completelydisintegrated;itisalsopossibletodigestthemeltin
gram of sample taken; add 4 mL of H SO (1+1) and
2 4
the cold HCl overnight. Police and rinse the lid with a fine jet
evaporate to the first fuming of H SO (Note 3). Cool,
2 4
of water; rinse down the sides of the dish and evaporate to
carefully wash down the sides of the dish with a minimum of
dryness on a steam bath or under an infrared lamp. Keep the
water, and evaporate to the cessation of H SO fumes. Cool,
2 4
dish covered with a raised cover glass during evaporation.
add10to15mLofHCl(1+1),20mLofhotwater,anddigest
When evaporation is complete (absence of HCl), cool, drench
hotuntilthesaltsareinsolution.Iftheydonotdissolvereadily,
theresiduewith5mLofHCl,andthenadd20mLofhotwater.
transfer to a beaker, police the dish, and boil the solution until
Digestfor5minandfilterthrougha9-cmmediumfilterpaper.
the sulfates have dissolved (Note 4).
Catch the filtrate in a 250-mL platinum dish. Transfer the
NOTE 3—Some sands may contain small amounts of organic matter as
precipitated silica to the filter with the aid of a policeman and
shown by the presence of carbon or carbonaceous material in the
a bit of paper pulp, and wash the precipitate and paper twelve
concentrated H SO . If this is the case, add 2 to 3 mLof HNO and 10 to
2 4 3
times with hot 2% HCl. Transfer the paper and precipitate to
15 drops of HClO , and proceed.
the dish used for fusion and dehydration and reserve for
NOTE 4—High-alumina sands are generally mixtures of quartz and
subsequent ignition. Wipe the stirring rod and the periphery of aluminum silicates of the feldspar group. Some of these silicates can
contain barium. If a fine, white, insoluble precipitate persists, it is
thefunnelwithapieceofdampfilterpaper,andaddtothedish
probably barium sulfate. In this case, partially neutralize the HCl until the
containing the precipitate for ignition.
solutionisabout1to2%acid,addabouttendropsofH SO (1+1)and
2 4
boil gently for about 30 min. Cool, and after 1 to 2 h, filter the solution
10.3 Evaporate the filtrate to dryness on the steam bath or
through a fine paper. The precipitate may be ignited and weighed and
under an infrared lamp.When dry, cool, drench with 10 mLof
subsequently tested for barium. If the precipitate is not barium sulfate, it
HCl (1+1), and again evaporate just to dryness; then bake in
should be tested for silica. If the precipitate is neither of these, it can be
a drying oven at 105°C for 30 min. Cool, drench with 5 mLof
considered R O and added to the R O found by ammonia precipitation.
2 3 2 3
HCl, and add 20 mLof hot water and a small bit of filter pulp.
11.2.2 If the expected R O is about 10 mg, dilute the
2 3
Digesthotfor5minandfilterthrougha7-cmfinepaper.Police
sample to about 75 to 100 mL; if much larger, dilute to about
thedishwiththeaidofabitofpaperpulpandwashprecipitate
200 to 250 mL. Add approximately2gofNH Cl, heat to
andpapereighttimeswithhot2%HCl.Transferthepaperand
boiling,addthreetofourdropsofmethylredindicatorsolution
precipitate to the dish containing the initial precipitation.Wipe
and precipitate the R O with the addition of NH OH (1+1).
2 3 4
the stirring rod and the periphery of the funnel with a piece of
Add the NH OH slowly, stirring to obtain a sharp end point;
dampfilterpaper,andaddtothedishcontainingtheprecipitate
finally add about four drops in excess for small amounts of
for ignition.
precipitate and up to eight drops for large amounts. Boil the
solutionforabout2minandfilterthroughacoarsepaper;there
10.4 Partially cover the dish with its platinum lid, but leave
enoughspacesoaircancirculateduringignition.Placethedish is no need to transfer quantitatively all the precipitate at this
time. Wash the precipitate three to four times with hot 2%
in a cold muffle furnace, and bring the temperature to 1200°C
for 30 min. Carefully and completely cover the dish before NH Cl made neutral to methyl red. Transfer the precipitate
back into the beaker and add 10 to 15 mL of HCl (1+1) and
removing it from the furnace and transfer to a desiccator. Cool
toroomtemperatureandweighthecovereddish(W ).Moisten digest to disintegrate the paper and dissolve the precipitate.
Dilute to approximately the same volume used for the
...
This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:C146–94a (Reapproved 2004) Designation:C146–94a (Reapproved 2009)
Standard Test Methods for
Chemical Analysis of Glass Sand
This standard is issued under the fixed designation C146; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 These test methods cover the chemical analysis of glass sands. They are useful for either high-silica sands (99%+silica
(SiO ))orforhigh-aluminasandscontainingasmuchas12to13%alumina(Al O ).Generallynonclassical,thetestmethodsare
2 2 3
rapid and accurate.They include the determination of silica and of total R O (see 11.2.4), and the separate determination of total
2 3
ironasironoxide(Fe O ),titania(TiO ),chromiumoxide(Cr O ),zirconia(ZrO ),andignitionloss.Includedareproceduresfor
2 3 2 2 3 2
the alkaline earths and alkalies. High-alumina sands may contain as much as 5 to 6% total alkalies and alkaline earths. It is
recommended that the alkalies be determined by flame photometry and the alkaline earths by absorption spectrophotometry.
1.2 These test methods, if followed in detail, will provide interlaboratory agreement of results.
NOTE 1—For additional information, see Test Methods C169 and Practices E50.
1.3 The test methods appear in the following order:
Procedures for Referee Analysis: Section
Silica (SiO )—Double Dehydration 10
Total R O —Gravimetric 11
2 3
Fe O ,TiO ,ZrO ,Cr O , by Photometric Methods and 12-17
2 3 2 2 2 3
Al O by Complexiometric Titration
2 3
Preparation of the Sample for Determination of Iron 12
Oxide, Titania, Alumina, and Zirconia
Iron Oxide (as Fe O ) by 1,10-Phenanthroline Method 13
2 3
Titania (TiO ) by the Tiron Method 14
Alumina (Al O ) by the CDTA Titration Method 15
2 3
Zirconia (ZrO ) by the Pyrocatechol Violet Method 16
Chromium Oxide (Cr O ) by the 1,5-Diphenylcarbo- 17
2 3
hydrazide Method
Procedures for Routine Analysis:
Silica (SiO )—Single Dehydration 19
Al O , CaO, and MgO—Atomic Absorption Spec- 20–25
2 3
trophotometry
Na O and K O—Flame Emission Spectrophotometry 26-27
2 2
Loss on Ignition (LOI) 28
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
C169 Test Methods for Chemical Analysis of Soda-Lime and Borosilicate Glass
C429 Test Method for Sieve Analysis of Raw Materials for Glass Manufacture
D1193 Specification for Reagent Water
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
These test methods are under the jurisdiction of ASTM Committee C14 on Glass and Glass Products and are the direct responsibility of Subcommittee C14.02 on
Chemical Properties and Analysis.
Current edition approved Oct. 1, 2004. Published October 2004. Originally approved in 1939 . Last previous edition apporved in 1999 as C146–94a(1999). DOI:
10.1520/C0146-94AR04.
Current edition approved Nov. 1, 2009. Published January 2010. Originally approved in 1939 . Last previous edition approved in 2004 as C146–94a(2004). DOI:
10.1520/C0146-94R09.
ForreferencedASTMstandards,visittheASTMwebsite,www.astm.org,orcontactASTMCustomerServiceatservice@astm.org.For Annual Book ofASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C146–94a (2009)
E50 PracticesforApparatus,Reagents,andSafetyConsiderationsforChemicalAnalysisofMetals,Ores,andRelatedMaterials
E60 Practice for Analysis of Metals, Ores, and Related Materials by Molecular Absorption Spectrometry
2.2 Other Documents:
NIST Special Publication 260
3. Significance and Use
3.1 These test methods can be used to ensure that the chemical composition of the glass sand meets the compositional
specification required for this raw material.
3.2 These test methods do not preclude the use of other methods that yield results within permissible variations. In any case,
the analyst should verify the procedure and technique used by means of a National Institute of Standards and Technology (NIST)
standard reference material or other similar material of known composition having a component comparable with that of the
material under test. A list of standard reference materials is given in the NIST Special Publication 260, current edition.
4. Photometers and Photometric Practice
4.1 Photometers and photometric practice prescribed in these test methods shall conform to Practice E60.
5. Purity of Reagents
5.1 Reagent grade chemicals shall be used throughout. Unless otherwise indicated, it is intended that reagents shall conform to
the specifications of the Committee on Analytical Reagents of the American Chemical Society, where suchspecifications are
available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use
without lessening the accuracy of the determination.
5.2 Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type I, II, or III
of Specification D1193.
6. Concentration of Acids and Ammonium Hydroxide
(NH OH)
6.1 When acids and ammonium hydroxide are specified by name or chemical formula only, concentrated reagents of the
following percent concentrations are intended:
Sp Gr %
Hydrochloric acid (HCl) 1.2 36 to 38
Hydrofluoric acid (HF) 1.2 48 to 51
Nitric acid (HNO ) 1.4 69 to 71
Perchloric acid (HClO ) 1.8 70 to 72
Sulfuric acid (H SO ) 1.8 95 to 98
2 4
Ammonium hydroxide (NH OH) 0.9 28 to 30
6.2 Concentrations of diluted acids and NH OH, except when standardized, are specified as a ratio stating the number of
volumesoftheconcentratedreagenttobeaddedtoagivennumberofvolumesofwater,asinthefollowingexample:HCl(1+99)
means 1 volume of concentrated HCl (sp gr 1.19) added to 99 volumes of water.
7. Filter Papers
7.1 Throughout these test methods, filter papers will be designated as “coarse,” “medium,” or “fine” without naming brands or
manufacturers.All filter papers are of the double-acid-washed ashless type. “Coarse” filter paper refers to the porosity commonly
usedforthefiltrationofaluminumhydroxide.“Medium”filterpaperreferstothatusedforfiltrationofcalciumoxalate,and“fine”
filter paper to that used for barium sulfate.
8. Preparation of Sample
8.1 General Considerations—The acquisition and preparation of the sample shall follow the principles stated in Test Method
C429.
8.2 The laboratory sample is reduced for analysis to 10 to 20 g by use of a small riffle with openings preferably of 6.4-mm
( ⁄4-in.) size. The analytical sample is then ground in an agate mortar to pass a 150-µm (No. 100) sieve. If the laboratory sample
as received contains any large particles that are retained on a 850-µm (No. 20) sieve, these shall be sieved out, crushed (without
contamination) so as to pass the sieve, and then mixed back into the laboratory sample before riffling.
Standard samples available from the National Institute of Standards and Technology are listed in U.S. Dept. of Commerce, NIST, Special Publication 260 (current
edition), Washington, DC 20234.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
Requirements for sieves are given in ASTM Specification E11.
C146–94a (2009)
9. Precision and Bias
9.1 Precision—The probable precision of results that can be expected by the use of procedures described in these test methods
isshowninthefollowingtabulation.Precisionisgivenasabsoluteerrorandisdependentonthequantityoftheconstituentpresent
as well as the procedure used.
Probable Precision of Results, Weight %
Constituent Referee Analysis Routine Analysis
SiO (99 %) 60.1 60.25
SiO (85–90 %) 60.1 60.25
R O (1 %) 60.05 60.10
2 3
R O (10–15 %) 60.1 60.15
2 3
Al O (1 %) 60.05 60.10
2 3
Al O (10–15 %) 60.1 60.1
2 3
Fe O 60.003 .
2 3
TiO 60.005 .
ZrO 60.001 to 0.005 .
Cr O 60.0001 to 0.001 .
2 3
CaO . 60.001
MgO . 60.001
Na O . 60.001
K O . 60.001
9.2 Bias—Standard reference materials or other similar materials of known composition should be analyzed whenever possible
to determine the bias of the results.
PROCEDURES FOR REFEREE ANALYSIS
10. Silica (SiO ) by the Double Dehydration Method
10.1 Weigh 1.000 g of the powdered sample and 2.0 g of anhydrous sodium carbonate (Na CO ) into a clean 75-mLplatinum
2 3
dish(Note2);mixwellwithaplatinumorNichrome wire.Tapthechargesoitliesevenlyinthebottomofthedish.Coverevenly
with an additional 1.0 g of Na CO . Cover with the platinum lid and heat first at a dull red heat over a clean oxidizing flame;
2 3
gradually raise the temperature until a clear melt is obtained. Properly carried out, little or no spattering should occur, and the
fusion can be performed in 3 to 4 min. When melted, rotate the melt to spread it evenly over the bottom and lower sides of the
dish, gradually withdrawing from the flame. Cover and cool to room temperature. During fusion, the dish should be handled at
alltimeswithplatinum-tippedtongsandthefusionperformedwithaplatinum(preferably90%platinumand10%rhodiumalloy)
or silica triangle.
NOTE 2—To obtain accurate repeat weighings, platinum ware must be kept scrupulously clean on the outside of the vessel as well as on the inside.
It should be polished brightly with fine, round grain sand and protected from dirty surfaces. It is recommended that porcelain plates be used for cooling
fusions, and that platinum be set on paper towels or other clean material during filtration.
10.2 Add 20 to 25 mL of HCl (1+1) under the platinum cover and digest on a steam bath or hot plate until the melt has
completely disintegrated; it is also possible to digest the melt in the cold HCl overnight. Police and rinse the lid with a fine jet of
water; rinse down the sides of the dish and evaporate to dryness on a steam bath or under an infrared lamp. Keep the dish covered
with a raised cover glass during evaporation.When evaporation is complete (absence of HCl), cool, drench the residue with 5 mL
of HCl, and then add 20 mL of hot water. Digest for 5 min and filter through a 9-cm medium filter paper. Catch the filtrate in a
250-mL platinum dish. Transfer the precipitated silica to the filter with the aid of a policeman and a bit of paper pulp, and wash
the precipitate and paper twelve times with hot 2% HCl. Transfer the paper and precipitate to the dish used for fusion and
dehydration and reserve for subsequent ignition. Wipe the stirring rod and the periphery of the funnel with a piece of damp filter
paper, and add to the dish containing the precipitate for ignition.
10.3 Evaporate the filtrate to dryness on the steam bath or under an infrared lamp. When dry, cool, drench with 10 mLof HCl
(1+1), and again evaporate just to dryness; then bake in a drying oven at 105°C for 30 min. Cool, drench with 5 mLof HCl, and
add 20 mL of hot water and a small bit of filter pulp. Digest hot for 5 min and filter through a 7-cm fine paper. Police the dish
with the aid of a bit of paper pulp and wash precipitate and paper eight times with hot 2% HCl.Transfer the paper and precipitate
tothedishcontainingtheinitialprecipitation.Wipethestirringrodandtheperipheryofthefunnelwithapieceofdampfilterpaper,
and add to the dish containing the precipitate for ignition.
10.4 Partially cover the dish with its platinum lid, but leave enough space so air can circulate during ignition. Place the dish
inacoldmufflefurnace,andbringthetemperatureto1200°Cfor30min.Carefullyandcompletelycoverthedishbeforeremoving
it from the furnace and transfer to a desiccator. Cool to room temperature and weigh the covered dish (W ). Moisten the silica
with 1 to 2 mLof water and add 4 to 5 mLof HF and 0.5 g of oxalic acid crystals. Evaporate to dryness on a sand bath or under
an infrared lamp. Carefully sublime any remaining oxalic acid, cover the dish with its platinum cover, heat to 1000°C for 2 min,
cool, and weigh (W ) as before.
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C146–94a (2009)
10.5 Calculation—Calculate the percent of SiO as follows:
(1) SiO2,% 5 ~W1 2 W2! 3100sampleweight
11. Total R O by Ammonium Hydroxide (NH OH) Precipitation
2 3 4
11.1 General Considerations—The weight of sample taken for analysis is governed by the amount of Al O known or
2 3
suspectedtobepresent.SandslowinAl O (0.05to0.5%)requirea5-to10-gsample;sandswithlargeramountsofAl O require
2 3 2 3
a 0.5- to 1.0-g sample. Usually experience or prior information will indicate a satisfactory sample weight. The total R O serves
2 3
as a check on the sum of the R O oxides determined separately. It also helps to identify an unknown sand as a low- or
2 3
high-alumina type.
11.2 Procedure:
11.2.1 Weigh a suitable weight of sample into an 80- to 100-mL platinum dish, moisten, and add 10 mL of HF for each gram
of sample taken; add 4 mL of H SO (1+1) and evaporate to the first fuming of H SO (Note 3). Cool, carefully wash down
2 4 2 4
the sides of the dish with a minimum of water, and evaporate to the cessation of H SO fumes. Cool, add 10 to 15 mL of HCl
2 4
(1+1),20mLofhotwater,anddigesthotuntilthesaltsareinsolution.Iftheydonotdissolvereadily,transfertoabeaker,police
the dish, and boil the solution until the sulfates have dissolved (Note 4).
NOTE 3—Some sands may contain small amounts of organic matter as shown by the presence of carbon or carbonaceous material in the concentrated
H SO . If this is the case, add 2 to 3 mL of HNO and 10 to 15 drops of HClO , and proceed.
2 4 3 4
NOTE 4—High-aluminasandsaregenerallymixturesofquartzandaluminumsilicatesofthefeldspargroup.Someofthesesilicatescancontainbarium.
If a fine, white, insoluble precipitate per
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