YS/T 521.2-2009 English PDF (YST521.2-2009)

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YS/T 521.2-2009: Methods for chemical analysis of blister copper. Part 2: Determination of gold and silver contents. Fire assay method
YS/T 521.2-2009
NONFERROUS METALS INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.30
H 13
Replacing YS/T 521.3-2006
Methods for chemical analysis of blister copper -
Part 2: Determination of gold and silver contents -
Fire assay method
ISSUED ON: DECEMBER 4, 2009
IMPLEMENTED ON: JUNE 1, 2010
Issued by: Ministry of Industry and Information Technology of the
People’s Republic of China.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Method summary ... 5 
3 Reagents ... 5 
4 Instruments and equipment ... 6 
5 Analytical procedure ... 6 
6 Calculation of analysis results ... 9 
7 Precision ... 11 
8 Quality assurance and control ... 12 
Foreword
YS/T 521-2009 Methods for chemical analysis of blister copper is divided into
6 parts:
— Part 1: Determination of copper content - Iodimetry
— Part 2: Determination of gold and silver contents - Fire assay method
— Part 3: Determination of arsenic content
Method 1 Hydride generation - atomic fluorescence spectrometric
method
Method 2 Potassium bromate titration
— Part 4: Determination of lead, bismuth and antimony contents - Flame
atomic absorption spectrometry
— Part 5: Determination of zinc and nickel contents - Flame atomic
absorption spectrometry
— Part 6: Determination of arsenic, antimony, bismuth, lead, zinc and
nickel contents - Inductively coupled plasma-atomic emission
spectrometry
This Part is Part 2 of YS/T 521.
This Part replaces YS/T 521.3-2006 Methods for chemical analysis of blister
copper - Determination of gold and silver contents (original GB/T
5120.3-1995). Compared with YS/T 521.3-2006, this Part has the following
changes:
— The text format was modified;
— Precision as well as quality assurance and control provisions were
supplemented.
This Part was proposed by and shall be under the jurisdiction of the National
Technical Committee for Standardization of Nonferrous Metals.
Responsible drafting organization of this Part: Daye Nonferrous Metals Group
Holdings Co., Ltd.
Participating drafting organizations of this Part: Beijing General Research
Institute of Mining and Metallurgy, Jiangxi Copper Co., Ltd., and Jinchuan
Group Ltd.
Methods for chemical analysis of blister copper –
Part 2: Determination of gold and silver contents -
Fire assay method
1 Scope
This Part of YS/T 521 specifies the method for determining gold and silver
contents in blister copper.
This Part applies to the determination of gold and silver contents in blister
copper. Determination range: gold mass fraction ≥ 0.5g/t; silver mass fraction
≥ 20g/t.
2 Method summary
The sample is dissolved in sulfuric acid. The gold and silver precipitates
obtained after copper removal by filtration are ashed, compounded and
melted to obtain an appropriate amount of lead buckle. The gold and silver
contents are determined gravimetrically after the lead buckle is cupellated.
The correction method is carried out by adding pure copper as a matrix and
adding pure gold and pure silver along with the sample for determination. It is
corrected according to its recovery rate or corrected by the cupel and slag
melting method.
3 Reagents
Unless otherwise stated, only analytically pure reagents and distilled or
deionized water or water of comparable purity are used in the analysis.
3.1 Sodium carbonate: industrial pure, powdery.
3.2 Lead oxide: industrial pure, powdery (gold mass fraction ≤ 0.05μg/g;
silver mass fraction ≤ 5μg/g).
3.3 Borax: powdery.
3.4 Starch: industrial pure, powdery.
3.5 Silicon dioxide: industrial pure, powdery.
3.6 Sodium chloride: industrial pure, powdery.
3.7 Gold (mass fraction ≥ 99.99%).
3.8 Silver (mass fraction ≥ 99.99%).
3.9 Copper (mass fraction ≥ 99.95%).
3.10 Sulfuric acid (ρ1.84g/mL).
3.11 Nitric acid (1+1).
3.12 Nitric acid (1+7).
3.13 Mercuric sulfate solution (23g/L).
3.14 Sodium chloride solution (10g/L).
3.15 Acetic acid (1+3).
4 Instruments and equipment
4.1 Balance.
4.1.1 Ultra-micro balance: with a sensitivity of 0.001mg.
4.1.2 Microbalance: with a sensitivity of 0.01mg.
4.1.3 Analytical balance: with a sensitivity of 1mg.
4.1.4 Counter balance: with a sensitivity of 1g.
4.2 Assay furnace.
4.3 Cupel machine.
4.4 Porcelain crucible: low profile, 30mL.
4.5 Clay crucible: with a height of 120mm, an upper outer diameter of 90mm,
and a lower outer diameter of 50mm.
4.6 Cupel: Ash cement cupel or magnesia cupel.
General specifications: with a height of 30mm, an upper inner diameter of
35mm, a lower outer diameter of 40mm, and a depth of 17mm or so.
5 Analytical procedure
5.1 Specimen
5.3.1.3 TRANSFER all sediments to the filter paper. USE warm water to
wash the sediments until there is no blue color. PLACE the glass rod and filter
paper on the cup wall, together with the filter paper loaded with the sediments,
in a clay crucible, and then PLACE it in an assay furnace. RISE from room
temperature to about 500°C for ashing until ashing is completed.
5.3.2 Ingredients
COOL the clay crucible containing the ash compound to room temperature.
ADD 20g of sodium carbonate (3.1), 60g of lead oxide (3.2), 7g of borax (3.3),
7g of silicon dioxide (3.5), and 3g of starch (3.4). STIR well, and COVER
10mm thick sodium chloride (3.6).
5.3.3 Melting
PLACE the prepared clay crucible in an assay furnace at 800°C. RISE
temperature to 1,100°C within 30min to 40min, and INSULATE for 15min
(total melting time is 45min to 55min) before discharging. POUR the melt into
a preheated and oiled cast iron mold. After cooling, BEAT the lead buckle into
a square shape. COLLECT the slag into the original clay crucible for later use
(corrected by the method B).
5.3.4 Cupellation
5.3.4.1 PLACE the lead buckle in a cupel preheated in an assay furnace at
900°C for 20min, and CLOSE the furnace door. After the floating film on the
surface of the lead liquid disappears (uncoating), slightly OPEN the furnace
door to lower the furnace temperature to 840°C to 860°C for cupellation. The
cupellation ends when the particles appear to flash. MOVE the cupel to the
furnace door, and PLACE it in a cupel tray after slight cooling.
5.3.4.2 USE a small tweezers to remove the gold and silver particles from
the cupel. PLACE them in a porcelain crucible, and ADD 15mL of acetic acid
(3.15). REMOVE when boiled to about 5mL on an electric hot plate. WASH
with warm water three times, and DISCARD the cleansing solution. PLACE
the gold and silver particles retained in the porcelain crucible on a
high-temperature electric furnace to bake dry, REMOVE and WEIGH
(accurate to 0.01mg) after cooling to room temperature. KEEP the cupel for
later use (corrected by the method B).
5.3.5 Parting
PLACE the weighed gold and silver particles on a small steel anvil to beat into
a sheet. PLACE it in a porcelain crucible. ADD about 5mL of hot nitric acid
(3.12). PLACE it on a low-temperature heating plate for parting. When
steaming to about 2mL, ADD about 5mL of hot nitric acid (3.11). STEAM to
about 2mL, REMOVE, COOL, and WASH three times with hot water. PLACE
m12 - Gold content measured in the second correction, in milligrams (mg);
m13 - Blank content of gold in the total content of lead oxide used in the
ingredients in the absence and presence of correction, in milligrams (mg);
m4 - Content of gold and silver particles measured in the absence of
cor...