ASTM E2296-03

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Designation:E2296–03
Standard Practice for
Silver Corrections in Metal Bearing Ores, Concentrates, and
Related Metallurgical Materials by Fire Assay Slag Recycling
and Cupel Proof Gravimetry
This standard is issued under the fixed designation E 2296; 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 Bugbee, Edward, Textbook of Fire Assaying
Smith, E.A., The Sampling and Assay of Precious Metals
1.1 This practice covers the silver loss correction, utilizing
slag recycling and cupellation of proof silver during the fire
3. Terminology
assay of metal bearing ores, concentrates and related metallur-
3.1 Definitions—For definitions of terms used in this Prac-
gical materials.
tice, refer to Terminology E 135.
1.2 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, the slag is retained
priate safety and health practices and determine the applica-
from the initial fusion and reprocessed through the fusion
bility of regulatory limitations prior to use. (See Practices E 50
procedure. The resulting lead button is combined with the
and ISO Guide 35.)
preliminary lead button during cupellation. Proof silver is
2. Referenced Documents carried through the cupellation procedure to determine the
silver losses. (See ISO 10378, Bugbee, Smith).
2.1 ASTM Standards:
E 29 Practice for Using Significant Digits in Test Data to
5. Significance and Use
Determine Conformance with Specifications
5.1 This practice is primarily intended to be used for the
E 50 Practices for Apparatus, Reagents, and Safety Precau-
3 correction of silver loss in the fire assay process. Silver
tions for Chemical Analysis of Metals
contents are determined by fire assay for the purpose of
E 135 Terminology relating to Analytical Chemistry for
metallurgical exchange between buyer and seller. It is assumed
Metals, Ores and Related Materials
that all who use this practice will be trained analysts capable of
E 882 Guide for Accountability and Quality Control in the
performing skillfully and safely. It is expected that work will
Chemical Analysis of Metals
be performed in a properly equipped laboratory under appro-
2.2 Other Documents:
priate quality control practices such as those described in
ISO 35:1989 Certification of Reference Materials- General
Guide E 882.
and Statistical Principles
ISO 10378:1994 Copper Sulfide Concentrates—
6. Apparatus
Determination of Gold and Silver Contents—Fire Assay
6.1 Assay Furnace, capable of temperatures up to 1100°C,
Gravimetric and Atomic Absorption Spectrometric
accurate to 6 5°C with draft controls.
Method
6.2 Analytical Balance, capable of weighing to 0.001 mg.
6.3 Hammer, blacksmith type.
6.4 Hammering Block, flat steel or iron.
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 . Bugbee, E. E., A Textbook of Fire Assaying, John Wiley and Sons, Inc., Third
Current edition approved June 10, 2003. Published July 2003. Ed., 1946.
2 5
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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E2296–03
TABLE 1 Slag Re-Fusion Flux
9.4 Place crucible in the fire assay furnace. Raise the
litharge 55.4 g temperature to 1060°C.After the furnace obtains that tempera-
sodium carbonate 9.3 g
ture, hold for at least 30 min. In most instances, the total
silica sand 9.4 g
furnace time will be approximately 1 h. Fusion must be in a
potassium bitartrate 7.3 g
borax 18.7 g liquid state.
NOTE 2—Inmostcases,thebestwaytoaddre-fusionfluxiswithawax
paper bag. Place the re-fusion flux into the bag, twist the top, and place on
7. Reagents and Materials
top of the original fusion slag material in the original fire assay crucible.
7.1 Purity of Reagents—Reagent grade chemicals shall be
9.5 After 1 h, carefully pour the melt into fire assay moulds,
used in all tests. Unless otherwise indicated, it is intended that
taking care to ensure that no portion is lost.
all reagents conform t
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