ASTM E2295-03

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Designation:E2295–03
Standard Practice for
Fire Assay Silver Corrections in Analysis of Metal Bearing
Ores, Concentrates, and Related Metallurgical Materials by
Silver Determination in Slags and Cupels
This standard is issued under the fixed designation E 2295; 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 ISO Guide 35-1989 Certification of Reference Materials-
General and Statistical Principles
1.1 This practice covers the determination of silver correc-
ISO 10378:1994 Copper Sulfide Concentrates-
tions for fire assay of metal bearing ores, concentrates and
Determination of Gold and Silver Contents-Fire Assay
related metallurgical materials using the spent slags and cupels
Gravimetric and Atomic Absorption Spectrometric
from the fire assay process, by gravimetry and atomic absorp-
Method. Bugbee, Edward, Textbook of Fire Assaying;
tion spectrophotometry.
Smith, E.A., The Sampling and Assay of Precious Metals
1.2 The test methods appear in the following order:
Sections
3. Terminology
Gravimetric Method 10-11
Atomic Absorption Method 12-13
3.1 Definitions—For definitions of terms used in this Prac-
tice, refer to Terminology E 135.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Summary of Practice
responsibility of the user of this standard to establish appro-
4.1 In the process of fire assay fusion slags and cupels are
priate safety and health practices and determine the applica-
collected, retreated and silver is determined in them to provide
bility of regulatory limitations prior to use. (See Practices E 50
a correction value for the fire assay determination of silver (see
and ISO Guide 35: 1989.)
Guide E 1024, Test Method E 1335, ISO 10378, Bugbee,
2. Referenced Documents Smith).
2.1 ASTM Standards:
5. Significance and Use
D 1193 Specification for Reagent Water
5.1 These methods are primarily intended to be used for the
E 29 Practice Using Significant Digits in Test Data to
3 determination of silver correction in the fire assay silver
Determine Conformance With Specifications
determination. Silver assays are determined by fire assay for
E 50 Practices for Apparatus, Reagents, and Safety Precau-
4 the purpose of metallurgical exchange between seller and
tions for Chemical Analysis of Metals
buyer.
E 135 Terminology Relating to Analytical Chemistry for
4 5.2 Itisassumedthatallwhousethismethodwillbetrained
Metals, Ores, and Related Materials
analysts capable of performing skillfully and safely. It is
E 882 Guide for Accountability and Quality Control in the
4 expected that work will be performed in a properly equipped
Chemical Analysis Laboratory
laboratory under appropriate quality control practices such as
E 1024 Guide for Chemical Analysis of Metals and Metal
those described in Guide E 882.
Bearing Ores by Flame Atomic Absorption Spectropho-
tometry
6. Apparatus
E 1335 Test Methods for Determination of Gold in Bullion
4 6.1 Analytical Balance, capable of weighing to 0.01 g.
by Cupellation
6.2 Analytical Balance, capable of weighing to 0.001 mg.
2.2 Other Documents:
6.3 Assay Furnace, capable of temperatures up to 1100°C,
accurate to 6 5°C.
6.4 Atomic Absorption Spectrophotometry, AAS.
This practice is under the jurisdiction of ASTM Committee E01 on Analytical
Chemistry for Metals, Ores and Related Materials and is the direct responsibility of
Subcommittee E01.02 on Ores, Concentrates, and Related Metallurgical Materials .
Current edition approved June 10, 2003. Published July 2003. Bugbee, E. E., A Textbook of Fire Assaying, John Wiley and Sons, Inc., Third
Annual Book of ASTM Standards, Vol 11.01. Ed., 1946.
3 6
Annual Book of ASTM Standards, Vol 14.02. Smith, E. A., The Sampling and Assay of the Precious Metals, Charles Griffin
Annual Book of ASTM Standards, Vol 03.05 and Co., Ltd., Second Ed., 1947.
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E2295–03
6.5 Ring Grinder, 250 g capacity.
5. Flour—Usually4gadd
or subtract to produce an
approximately
7. Reagents and Materials
30 g lead fire assay
7.1 Purity of Reagents—Reagent grade chemicals shall be button
used in all tests. Unless otherwise indicated, it is intended that
10.2 Weigh two portions of the retreatment sample into the
all reagents conform to the specifications of the Committee on
pre-fluxed crucibles and record the weights.
Analytical Reagents of the American Chemical Society where
Sample A = 14.583 g or ⁄2 AT
such specifications are available. Other grades may be used,
SampleB=29.167gor1AT
provided it is first ascertained that the reagent is of sufficiently
NOTE 2—AT = Assay Ton, a fire assay weight system.
high purity to permit its use without lessening the accuracy of
10.3 Mix retreatment samples and flux together in the
the determination.
crucibles.
7.2 Purity of Water—Unless otherwise indicated, references
10.4 Carry out the normal fire assay fusion and pour into
to water shall be understood to mean reagent water as defined
assay molds. Separate the slag from the lead button (See
by Type I of Specification D 1193.
Bugbee, Smith).
7.3 Borax, sodium tetraborate (Na B O ), technical grade.
2 4 7
10.5 Place the lead button from the retreatment fusion into
7.4 Ammonium Chloride Solution (NH Cl 250g/L)—Add
a new preheated cupel at 900°C.
250 g of ammonium chloride to 500 mL of water in a 1-L
10.6 Cupel to finish, (a lead free doré button should be
volumetric flask. Dilute to the mark and mix.
formed).
7.5 Crucibles, standard fire assay.
10.7 Discard the retreatment samples and crucibles when
7.6 Cupels, magnesite (MgCO ) or bone ash.
analysis and correction is completed.
7.7 Flour, common baking grade.
7.8 Litharge, PbO-tech grade silver free.
NOTE 3—These materials contain lead wastes, dispose of properly.
7.9 Silica Sand (SiO ), technical grade.
10.8 Weigh the duplicate retreatment doré beads to the
7.10 Sodium Carbonate (Na CO ), technical grade.
2 3
nearest 0.001 mg and record the weights.
8. Hazards
11. Calculation
8.1 For precautions to be observed in this practice,
...