ASTM E246-95

Standard Test Methods for Determination of Iron in Iron Ores and Related Materials by Dichromate Titration

SCOPE
1.1 These test methods cover the determination of total iron in iron ores, concentrates, and agglomerates in the concentration range 30 to 95 % iron.
1.2 The test methods in this standard are contained in the sections indicated as follows:
Test Method A--Iron by the Hydrogen Sulfide Reduction Dichromate Titration Method (30 to 75 % Fe)
Test Method B--Iron by the Stannous Chloride Reduction Dichromate Titration Method (35 to 95 % Fe)
Test Method C--Iron by the Silver Reduction Dichromate Titration Method (35 to 95 % Fe)
1.3 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. Specific hazards statements are given in Section 5 and in special "Warning" paragraphs throughout these test methods.

General Information

• Status: Historical
• Publication Date: 09-May-2001
• ICS: 73.060.10 - Iron ores
• Technical Committee: E01 - Analytical Chemistry for Metals, Ores, and Related Materials
• Drafting Committee: E01.02 - Ores, Concentrates, and Related Metallurgical Materials

Relations

• Replaced By: ASTM E246-01 - Standard Test Methods for Determination of Iron in Iron Ores and Related Materials by Dichromate Titration
• Effective Date: 10-May-2001

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 246 – 95
Standard Test Method for
Iron in Iron Ores and Related Materials by Hydrogen Sulfide
Reduction and Dichromate Titration
This standard is issued under the fixed designation E 246; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope mate solution using sodium diphenylamine sulfonate as the
indicator.
1.1 This test method covers the determination of total iron
in iron ores, concentrates, and agglomerates in the concentra-
4. Significance and Use
tion range from 30 to 75 %.
4.1 This test method is intended to be used for compliance
1.2 This standard does not purport to address all of the
with compositional specifications for iron content. It is as-
safety concerns, if any, associated with its use. It is the
sumed that all who use these procedures will be trained
responsibility of the user of this standard to establish appro-
analysts, capable of performing common laboratory procedures
priate safety and health practices and determine the applica-
skillfully and safely. It is expected that work will be performed
bility of regulatory limitations prior to use.
in a properly equipped laboratory and that proper waste
2. Referenced Documents disposal procedures will be followed. Appropriate quality
control practices must be followed, such as those described in
2.1 ASTM Standards:
2 Guide E 882.
D 1193 Specification for Reagent Water
E 276 Test Methods for Particle Size or Screen Analysis at
5. Interferences
No. 4 (4.75-mm) Sieve and Finer for Metal Bearing Ores
3 5.1 None of the elements normally found in iron ores
and Related Materials
interfere with this test method. These include vanadium,
E 877 Practice for Sampling and Sample Preparation of Iron
4 copper, and small amounts of molybdenum, which occasion-
Ores and Related Materials
ally occur in iron ores.
E 882 Guide for Accountability and Quality Control in the
Chemical Analysis Laboratory
6. Apparatus
3. Summary of Test Method 6.1 Analytical Balance and Weights—The balance used to
weigh the sample shall be sensitive to 0.05 mg and shall have
3.1 The sample is dissolved in hydrochloric acid. The
a precision of 0.1 mg. Analytical weights shall be of precision
insoluble residue is removed by filtration, ignited, and treated
grade or calibrated against a set of certified standard weights.
for the recovery of iron, and added to the main solution. To this
6.2 Buret—The buret used to titrate the reduced solution
solution containing all the iron, sulfuric acid is added and the
shall be of precision grade, calibrated to tenths of a millilitre,
solution evaporated to fumes to expel chlorides. The salts are
and shall be read to 0.05 mL.
dissolved in water, the solution heated to boiling, and the iron
6.3 Hydrogen Sulfide Generator—Hydrogen sulfide shall be
reduced by a rapid stream of hydrogen sulfide. The precipitated
obtained from a cylinder of the compressed gas or from a Kipp
sulfides are filtered and washed with an acid-sulfide wash
generator. A consistent flow of 1 L/min shall be maintained and
solution until free of iron. The filtrate is then boiled to expel the
the gas passed through a water trap to remove any salts.
hydrogen sulfide, cooled, and titrated with potassium dichro-
6.4 Glassware—Beakers or flasks used in the analysis of the
sample shall be of chemical-resistant glass and free of etched
This test method is under the jurisdiction of ASTM Committee E-1 on
surfaces. Before using, all glassware shall be cleaned in hot,
Analytical Chemistry for Metals, Ores, and Related Materials and is the direct
dilute hydrochloric acid and thoroughly rinsed in water.
responsibility of Subcommittee E01.02 on Ores, Slags, Refractories, Cement, and
Related Oxide Materials.
7. Reagents and Materials
Current edition approved April 15, 1995. Published June 1995. Originally
published as E 246 – 64 T. Last previous edition E 246 – 68 (1989).
7.1 Purity of Reagents—Reagent grade chemicals shall be
Annual Book of ASTM Standards, Vol 11.01.
used in all tests. Unless otherwise indicated, it is intended that
Annual Book of ASTM Standards, Vol 03.05.
Annual Book of ASTM Standards, Vol 03.06.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 246
TABLE 1 Precision Data
Repeatability Reproducibility
Number of Iron Found
Sample
R R
I 2
Laboratories %
s s
r R
(2.8 s ) (2.8 s )
r R
Seine River Ore 9 57.52 0.125 0.35 0.126 0.35
Knob Lake Ore 9 58.45 0.097 0.27 0.136 0.38
NBS 27d (64.96 % Fe) 6 65.01 0.057 0.16 0.085 0.24
Chilean Iron Ore 9 66.11 0.102 0.29 0.172 0.48
A
Pooled standard deviations 0.101 0.137
A
Weighted by degrees of freedom, n for s and (n − 1) for s where n 5 number of laboratories.
r R
all reagents shall conform to the specifications of the Commit- 7.12 Sodium Diphenylamine Sulfonate Indicator Solution—
tee on Analytical Reagents of the American Chemical Society, Dissolve 0.3 g of sodium diphenylamine sulfonate in 100 mL
where such specifications are available. Other grades may be of water. Store in a dark-colored bottle.
used, provided it is first ascertained that the reagent is of 7.13 Sodium Pyrosulfate (Na S O ).
2 2 7
sufficiently high purity to permit its use without lessening the 7.14 Sulfuric Acid (1 + 1)—Carefully mix 1 volume of
accuracy of the determination. concentrated sulfuric acid (H SO , sp gr 1.84) with 1 volume
2 4
7.2 Purity of Water—Unless otherwise indicated, references of water.
to water shall be understood to mean reagent water conforming 7.15 Sulfuric Acid (1 + 19)—Carefully mix 1 volume of
to Specification D 1193. concentrated sulfuric acid (H SO , sp gr 1.84) with 19 volumes
2 4
7.3 Ferrous Ammonium Sulfate Solution (approximately of water.
0.10 N)—Dissolve 40 g of ferrous ammonium sulfate 7.16 Sulfuric Acid-Hydrogen Sulfide Wash Solution—Add
(FeSO ·(NH ) SO ·6H O) in sulfuric acid (1 + 19). Transfer to 20 mL of concentrated sulfuric acid (H SO , sp gr 1.84) to 900
4 4 2 4 2 2 4
a 1-L flask and dilute to volume with the same acid. When the mL of water, cool, dilute to 1 L, and pass a rapid stream of H S
sample solution is ready for titration, standardize the through it for at least 10 min.
FeSO ·(NH ) SO ·6H O solution against the standard potas-
4 4 2 4 2
8. Sampling, Test Specimen, and Test Unit
sium dichromate (0.1000 N), as described in 9.5. Calculate the
8.1 The test unit shall be collected and prepared in accor-
millilitres of standard potassium dichromate equivalent to 1
dance with Practice E 877.
mL of the FeSO ·(NH ) SO ·6H O solution.
4 4 2 4 2
8.2 The test unit shall be pulverized or ground so that at
7.4 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
least 95 % passes a No. 100 (150 μ-m) sieve in accordance with
chloric acid (HCl).
Test Method E 276.
7.5 Hydrochloric Acid (1 + 50)—Mix 1 volume of HCl (sp
gr 1.19) with 50 volumes of water.
NOTE 1—Some ores, such as specular hematities, may require finer
7.6 Hydrofluoric Acid (48 %)—Concentrated hydrofluoric
grinding to pass a No. 200 (75-μm) sieve.
acid (HF).
9. Procedure
7.7 Hydrogen Sulfide (H S).
7.8 Nitric Acid (85 %)—Concentrated nitric acid (HNO ).
9.1 Transfer approximately 0.50 g of the test specimen to a
7.9 Phosphoric Acid (sp gr 1.69)—Concentrated phosphoric
small weighing bottle previously dried at about 105°C. Dry the
acid (H PO ).
bottle and contents for1hat105 to 110°C (Note 2). Cap the
3 4
7.10 Potassium Dichromate, Standard Solution (0.1000
bottle and cool to room temperature in a desiccator. Momen-
N)—Transfer 4.9035 g of primary standard grade potassium
tarily release the cap to equalize the pressure and weigh the
dichromate (K Cr O ), previously ground in an agate mortar,
capped bottle and sample to the nearest 0.1 mg. Repeat the
2 2 7
and dried at 105 to 110°C, to a 1-L volumetric flask. Dissolve
drying and weighing until there is no further weight loss.
in water and dilute to 1 L. If preferred, this solution may be
Transfer the test specimen to a 250-mL
...