ASTM E508-98
(Test Method)Standard Test Method for Calcium and Magnesium in Iron Ores by Atomic Absorption Spectrometry
Standard Test Method for Calcium and Magnesium in Iron Ores by Atomic Absorption Spectrometry
SCOPE
1.1 This test method covers the determination of calcium and magnesium in iron ores, concentrates, and agglomerates in the concentration range from 0.05 to 5% of calcium and 0.05 to 3% of magnesium.
1.2 This standard does not purport to address all of the safety problems, 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: E 508 – 98
Standard Test Method for
Calcium and Magnesium in Iron Ores by Atomic Absorption
Spectroscopy
This standard is issued under the fixed designation E 508; 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 magnesium, the sensitivity is decreased by a factor of about three.
If an air-acetylene burner is used for the determination of calcium,
1.1 This test method covers the determination of calcium
several elements, if present in percent amounts, interfere with the calcium
and magnesium in iron ores, concentrates, and agglomerates in
determination. Also, lanthanum chloride must be employed and the
the concentration range from 0.05 to 5 % of calcium and 0.05
sensitivity is decreased by a factor of about two.
to 3 % of magnesium.
4. Significance and Use
1.2 This standard does not purport to address all of the
safety problems, if any, associated with its use. It is the
4.1 This test method is intended as a referee method for
responsibility of the user of this standard to establish appro- compliance with compositional specifications for impurity
priate safety and health practices and determine the applica-
content. It is assumed that all who use this procedure will be
bility of regulatory limitations prior to use. trained analysts capable of performing common laboratory
practices skillfully and safely. It is expected that work will be
2. Referenced Documents
performed in a properly equipped laboratory and that proper
2.1 ASTM Standards:
waste disposal procedures will be followed. Follow appropriate
E 50 Practices for Apparatus, Reagents, and Safety Precau-
quality control practices such as those described in Guide
tions for Chemical Analysis of Metals
E 882.
E 276 Test Method for Particle Size or Screen Analysis at
5. Interferences
No. 4 (4.75-mm) Sieve and Finer for Metal-Bearing Ores
and Related Materials
5.1 None of the elements normally found in iron ores
E 663 Practice for Flame Atomic Absorption Analysis interfere with this test method (Note 1).
E 882 Guide for Accountability and Quality Control in the
3 6. Apparatus
Chemical Analysis Laboratory
6.1 Atomic Absorption Spectrometer, meeting the following
3. Summary of Test Method
criteria:
3.1 The sample is dissolved in hydrochloric acid with the
6.1.1 Minimum Sensitivity—The absorbance of the highest
addition of a small amount of nitric acid. After evaporation and calibration solution (see 7.3) must be at least 0.3.
dehydration, any insoluble residue is filtered, treated for the
6.1.2 Curve-Linearity—The difference between the read-
recovery of calcium and magnesium, and added to the main ings of the highest calibration solutions (40 to 50 mL) must be
solution. The solution is aspirated into the flame of the atomic
more than 1.4 times the difference between the readings for the
absorption spectrometer. For calcium, a nitrous oxide- zero solutions and the lowest calibration solution (0 to 5 mL).
acetylene burner is used, for magnesium, an air-acetylene
6.1.3 Minimum Stability—The coefficient of variation of a
burner is preferred (Note 1). The absorbed energy at the number of measurements of the highest calibration solution
resonance line of the spectrum of calcium or magnesium, or
and of the zero calibration solution must be less than 1.5 % and
both, is measured by atomic absorption spectroscopy and 0.5 % respectively, relative to the measurement of the highest
compared with that of the calibration solutions of the two
calibration solution.
elements.
NOTE 2—Use of a strip chart recorder or digital readout device, or both,
is advisable.
NOTE 1—If a nitrous oxide burner is used for the determination of
NOTE 3—Instrument parameters will vary with each instrument. The
following parameters were successfully used in several laboratories and
This test method is under the jurisdiction of ASTM Committee E-1 on
they can be used as guidelines. In the case of calcium, solutions were
Analytical Chemistry for Metals, Ores, and Related Materials and is the direct
aspirated into a nitrous oxide-acetylene flame of a premix burner. For
responsibility of Subcommittee E01.02 on Ores, Concentrates, and Related Metal-
magnesium an air-acetylene burner was used.
lurgical Materials.
Ca Mg
Current edition approved May 10, 1998. Published July 1998. Originally
Hollow cathode lamp, mA 15 15
published as E 508 – 73. Last previous edition E 508 – 93.
Wavelength, l, Å 4227 2852
Annual Book of ASTM Standards, Vol 03.05.
Nitrous oxide flow rate, L/min 13.8 .
Annual Book of ASTM Standards, Vol 03.06.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
E 508
mg. The difference between the two weights is the weight of
Air flow rate, L/min . 22
Acetylene flow rate, L/min 6.6 4.2
the sample taken for analysis.
9.2 Carry a reagent blank through all steps of the procedure
7. Reagents
starting with 9.3.
7.1 Purity and Concentration of Reagents—The purity and
9.3 Decomposition of Sample—Moisten the sample with a
concentration of the common chemical reagents used shall
few millilitres of water, add 25 mL of HCl, cover, and digest
conform to Practices E 50. Special apparatus and reagents
below the boiling point until no further attack is apparent. Add
required are located in separate sections preceding the proce-
2mL ofHNO and digest for several minutes. Remove the
dure.
cover and evaporate the solution to dryness. Heat the salts on
7.2 Calcium, Standard Solution (1 mL=25μgCa)—
a hot plate at 105 to 110°C for 15 min. Add 5 mL of HCl, cover
Dissolve 1.2487 g of anhydrous calcium carbonate in 100 mL
the beaker, and warm for several minutes. Add 50 mL of water
of dilute hydrochloric acid (HCl) (1+3). When solution is
and warm until soluble salts are in solution. Filter on a
complete, cool and dilute to 1 L in a volumetric flask. Transfer
fine-textured paper, and collect the filtrate in a 250-mL beaker.
10 mL of this solution to a 200-mL volumetric flask. Dilute to
Transfer the residue quantitatively to the filter paper. Wash
volume, and mix.
alternately three times with hot HCl (1+9) and hot water until
7.3 Calcium and Magnesium Calibration Solutions—Using
the yellow color of ferric chloride is no longer apparent.
pipets, transfer, 5.0, 10.0, 20.0, 40.0, and 50.0-mL portions of
Transfer the paper and residue to a platinum crucible. Reserve
the standard calcium and magnesium solutions to 200-mL
the filtrate.
volumetric flasks (Note 4). Dilute to 100 mL, add 6 mL of HCl
9.4 Treatment of Residue—Ignite the paper and residue in
(sp gr 1.19), 60 mL of background solution, and 40 mL of
the platinum crucible. Cool, moisten with several drops of
lanthanum ch loride solution. Dilute to volume, and mix.
water, add 3 or 4 drops of dilute sulfuric acid (H SO , 1+1) and
2 4
7.4 Iron, Background Solution (10 g/L)—Dissolve 10 g of
10 mL of hydrofluoric acid (HF). Evaporate slowly to expel
high-purity iron in 50 mL of HCl, (sp gr 1.19) and oxidize by
silica and then fume off the excess of H SO . Finally ignite at
2 4
the dropwise addition of nitric acid (HNO , sp gr 1.42).
about 700°C. Add1gof anhydrous sodium carbonate
Evaporate to a syrupy consistency. Add 20 mL of HCl (sp gr
(Na CO ) to the residue, cover the crucible, and fuse over a
2 3
1.19) and dilute to 200 mL with water. Add 20 g of sodium
burner or in a muffle furnace until a clear melt is obtained.
chloride (NaCl) dissolved in 200 mL water and dilute to 1 L
Dissolve the cool melt in the reserved filtrate f
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.