Designation: E 360 – 96 (Reapproved 2001)

Standard Test Methods for

Chemical Analysis of Silicon and Ferrosilicon1
This standard is issued under the fixed designation E 360; 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 for Determination of Chemical Composition4

1.1 These test methods cover the chemical analysis of E 50 Practices for Apparatus, Reagents, and Safety Consid-
silicon and ferrosilicon having chemical compositions within erations for Chemical Analysis of Metals, Ores, and
the following limits: Related Materials4
Element Concentration, %
E 60 Practice for Analysis of Metals, Ores, and Related
Materials by Molecular Absorption Spectrometry4
Aluminum 2.0 max E 173 Practice for Conducting Interlaboratory Studies of
Arsenic 0.10 max
Calcium 1.00 max
Methods for Chemical Analysis of Metals5
Carbon 0.50 max E 362 Test Methods for Chemical Analysis of Silicomanga-
Chromium 0.50 max nese and Ferrosilicon Manganese4
Copper 0.30 max
Manganese 1.00 max
E 363 Methods for Chemical Analysis of Chromium and
Nickel 0.30 max Ferrochromium4
Phosphorus 0.10 max E 364 Test Methods for Chemical Analysis of Ferrochrome-
Silicon 20.00 to 99.5
Sulfur 0.025 max Silicon4
Titanium 0.20 max
3. Significance and Use
1.2 The test methods appear in the following order:
3.1 These test methods for the chemical analysis of metals
Sections
and alloys are primarily intended to test such materials for
Arsenic by the Molybdenum Blue Photometric Method 9-19 compliance with compositional specifications. It is assumed
Aluminum by the Quinolinate Photometric and Gravimetric that all who use these test methods will be trained analysts
Methods 20-30
Silicon by the Sodium Peroxide Fusion-Perchloric Acid capable of performing common laboratory procedures skill-
Dehydration Method 31-38 fully and safely. It is expected that work will be performed in
1.3 This standard does not purport to address all of the a properly equipped laboratory.
safety concerns, if any, associated with its use. It is the 4. Apparatus, Reagents, and Photometric Practice
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- 4.1 Apparatus and reagents required for each determination
bility of regulatory limitations prior to use. Specific precau- are listed in separate sections preceding the procedure. The
tionary statements are given in Section 5 and 26.8.1, 27.4.1.1, apparatus, standard solutions, and certain other reagents used
and 36.3.1. in more than one procedure are referred to by number and shall
conform to the requirements prescribed in Practices E 50,
2. Referenced Documents except the photometers shall conform to the requirements
2.1 ASTM Standards: prescribed in Practice E 60.
A 100 Specification for Ferrosilicon2 4.2 Photometric practice prescribed in these test methods
E 29 Practice for Using Significant Digits in Test Data to shall conform to Practice E 60.
Determine Conformance with Specifications3 5. Safety Hazards
E 32 Practices for Sampling Ferroalloys and Steel Additives
5.1 For precautions to be observed in the use of certain
reagents in these test methods, refer to Practices E 50.
1
These methods are under the jurisdiction of ASTM Committee E01 on 6. Sampling
Analytical Chemistry for Metals, Ores, and Related Materials and are the direct
responsibility of Subcommittee E01.01 on Iron, Steel, and Ferroalloys. 6.1 For procedures for sampling the material, and for
Current edition approved April 10, 1996. Published June 1996. Originally
published as E 360 – 70 T. Last previous edition E 360 – 85 (1991)e1.
2 4
Annual Book of ASTM Standards, Vol 01.02. Annual Book of ASTM Standards, Vol 03.05.
3 5
Annual Book of ASTM Standards, Vol 14.02. Discontinued; see 1997 Annual Book of ASTM Standards, Vol 03.06.

Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.

1
 E 360
particle size of the sample for chemical analysis, refer to 13. Interferences
Practices E 32. 13.1 The elements ordinarily present do not interfere if their
7. Rounding Off Calculated Values concentrations are under the maximum limits shown in 1.1.
7.1 Calculated values shall be rounded off to the desired
14. Apparatus
number of places as directed in 3.4 to 3.6 of Practice E 29.
14.1 Distillation Apparatus, Fig. 1.
8. Interlaboratory Studies 14.2 Zirconium Crucibles, 30-mL capacity.
8.1 These test methods have been evaluated in accordance
with Practice E 173, unless otherwise noted in the Precision 15. Reagents
and Bias section. 15.1 Ammonium Bromide (NH4Br).
ARSENIC BY THE MOLYBDENUM BLUE 15.2 Ammonium Molybdate Solution (10 g/L)—Dissolve
PHOTOMETRIC METHOD 2.5 g of ammonium heptamolybdate tetrahydrate ((NH4)6-
Mo7O24·4H2O) in 40 mL of warm water. Add 128 mL of
9. Scope H2SO4 (1+3), dilute to 250 mL, and mix.
9.1 This method covers the determination of arsenic in 15.3 Ammonium Molybdate-Hydrazine Sulfate Solution—
silicon and ferrosilicon in concentrations from 0.001 to 0.10 %. Dilute 100 mL of ammonium molybdate solution to 900 mL,
10. Summary of Method add 10 mL of hydrazine sulfate solution, dilute to 1 L, and mix.
Do not use a solution that has stood more than 1 h.
10.1 Arsenic is first separated by distillation as the trivalent
15.4 Arsenic, Standard Solution A (1 mL = 0.10 mg As)—
chloride. Ammonium molybdate is added to form arsenomo-
Transfer 0.1320 g of arsenic trioxide (As2O3) to a 1-L
lybdate which is then reduced by hydrazine sulfate to form the
volumetric flask, dissolve in 100 mL of HCl, cool, dilute to
molybdenum blue complex. Photometric measurement is made
volume, and mix.
at approximately 850 nm.
15.5 Arsenic, Standard Solution B (1 mL = 0.01 mg As)—
11. Concentration Range Using a pipet, transfer 100 mL of arsenic Solution A (1
11.1 The recommended concentration range is 0.01 to 0.15 mL = 0.10 mg As) to a 1-L volumetric flask, dilute to volume,
mg of arsenic per 50 mL of solution using a 1-cm cell. and mix.
15.6 Hydrazine Sulfate ((NH2)2·H2SO4).
NOTE 1—This method has been written for cells having a 1-cm light
path. Cells having other dimensions may be used, provided suitable
15.7 Hydrazine Sulfate Solution (1.5 g/L)—Dissolve 1.5 g
adjustments can be made in the amount of sample and reagents used. of hydrazine sulfate ((NH2)2·H2SO4) in water, dilute to 1 L,
and mix. Do not use a solution that has stood more than 1 day.
12. Stability of Color 15.8 Sodium Carbonate (Na2CO3).
12.1 The color is stable for at least 2 h. 15.9 Sodium Peroxide (Na2O2).

FIG. 1 Arsenic Distillation Apparatus

2
 E 360
16. Preparation of Calibration Curve add NH4OH until the solution is alkaline to litmus, and then
16.1 Calibration Solutions: add 3 to 5 mL in excess. Heat to boiling, remove from the heat,
16.1.1 Using pipets, transfer 1, 2, 5, 10, and 15 mL of and allow the precipitate to settle. Filter on a coarse filter paper
arsenic Solution B (1 mL = 0.01 mg As) to 125-mL Erlenmeyer and wash five times with hot water. Discard the filtrate.
flasks. Remove the filter paper, carefully open it, and place it on the
16.1.2 Add 10 mL of HNO3 and evaporate the solution to inside wall of the original 800-mL beaker. Wash the precipitate
dryness on a hot plate. Bake for 30 min at 150 to 180°C. from the paper using a fine stream of water. Pass 25 mL of
Remove from the hot plate. Add 45 mL of ammonium HNO3 (1+1) over the paper, and wash well with water but do
molybdate-hydrazine sulfate solution to each flask, warm not exceed a total volume of 40 mL. Discard the paper. Warm
gently to dissolve the residue, and transfer the solution to a gently until the precipitate dissolves.
50-mL volumetric flask. Proceed as directed in 16.3. 17.1.5 Transfer the solution to the distillation flask, add 1 g
16.2 Reference Solution—Transfer 10 mL of HNO3 to a of NH4Br and 0.75 g of hydrazine sulfate. Add 20 mL of HNO3
125-mL Erlenmeyer flask and proceed as directed in 16.1.2. (1+1) to the receiving flask, and place the flask in an 800-mL
16.3 Color Development—Heat the flask in a boiling water beaker containing cold water. Assemble the apparatus (Fig. 1),
bath for 15 min. Remove the flask, cool to room temperature, heat the distillation flask, and distill into the receiving flask.
dilute to volume with ammonium molybdate-hydrazine sulfate 17.1.6 Distill until the volume is reduced to 10 mL or until
solution and mix. oxides of nitrogen are noted in the distillation flask. Remove
16.4 Photometry: the distillation flask from the heat source. Place the receiving
16.4.1 Multiple-Cell Photometer—Measure the cell correc- flask on a hot plate and evaporate the solution to dryness. Bake
tion using absorption cells with a 1-cm light path and a light for 30 min at 150 to 180°C. Add 45 mL of ammonium
band centered at approximately 850 nm. Using the test cell, molybdate-hydrazine sulfate solution to the flask, warm gently
take the photometric readings of the calibration solutions. to dissolve the residue, and transfer the solution to a 50-mL
16.4.2 Single-Cell Photometer—Transfer a suitable portion volumetric flask. Proceed as directed in 17.3.
of the reference solution to an absorption cell with a 1-cm light 17.2 Reference Solution—Carry a reagent blank through the
path and adjust the photometer to the initial setting, using a entire procedure using the same amounts of all reagents with
light band centered at approximately 850 nm. While maintain- the sample omitted, for use as a reference solution.
ing this adjustment, take the photometric readings of the 17.3 Color Development—Proceed as directed in 16.3.
calibration solutions. 17.4 Photometry—Take the photometric reading of the test
16.5 Calibration Curve—Plot the net photometric readings solution as directed in 16.4.
of the calibration solutions against milligrams of arsenic per 50
mL of solution. 18. Calculation
17. Procedure 18.1 Convert the net photometric reading of the test solution
to milligrams of arsenic by means of the calibration curve.
17.1 Test Solution:
Calculate the percentage of arsenic as follows:
17.1.1 Select and weigh a sample to the nearest 0.2 mg in
accordance with the following: Arsenic, % 5 A/~B 3 10! (1)
Arsenic, % Sample Weight, g
where:
0.001 to 0.015 0.500 A = milligrams of arsenic found in 50 mL of final test
0.01 to 0.04 0.250 solution, and
0.035 to 0.10 0.125 B = grams of sample represented in 50 mL of final test
Transfer the sample to a 30-mL zirconium crucible contain- solution.
ing 10 g of Na2O2 and 1 g of Na2CO3 if ferrosilicon, or 8 g of
Na2O2 plus 2 g of Na2CO3 if silicon metal. 19. Precision and Bias
17.1.2 Mix thoroughly with a metal spatula. Fuse carefully 19.1 Although samples covered by this method were not
over a free flame by holding the crucible with a pair of tongs available for testing, the precision data obtained for other types
and slowly revolving it around the outer edge of the flame until of alloys, using the methods indicated in Table 1, should apply.
the contents have melted down quietly; raise the temperature The user is cautioned to verify by the use of reference
gradually to avoid spattering. When the contents are molten, materials, if available, that the precision and bias of this
give the crucible a rotary motion to stir up any unattacked method is adequate for the contemplated use.
particles of the alloy adhering to the bottom or sides. Finally,
increase the temperature until the crucible is bright red for 1
min. Cool the crucible to room temperature. Transfer the TABLE 1 Statistical Information—Arsenic
crucible to an 800-mL beaker containing 60 mL of H2SO4 Repeatability Reproducibility
Ferroalloy Type Arsenic Found, %
(1+1) and 200 mL of water. Dissolve the melt; remove and (R1, E 173) (R2, E 173)
rinse the crucible. 1. No. 1, E 363 0.0015 0.0001 0.0005
17.1.3 If manganese dioxide is present, add H2SO3 drop- 2. No. 1, E 364 0.0018 0.0003 0.0003
3. No. 1, E 362 0.025 0.001 0.002
wise until the solution clears. 4. No. 2, E 362 0.039 0.001 0.002
17.1.4 Heat to boiling, and cool. While stirring vigorously,