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GB/T 6730.62-2005 PDF in English


GB/T 6730.62-2005 (GB/T6730.62-2005, GBT 6730.62-2005, GBT6730.62-2005)
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GB/T 6730.62-2005: PDF in English (GBT 6730.62-2005)

GB/T 6730.62-2005
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 73.060.10
D 31
Iron ores - Determination of calcium, silicon, manganese,
titanium, phosphorus, magnesium, aluminium and barium
content - Wavelength dispersive X-ray fluorescence
spectrometric method
ISSUED ON: JULY 21, 2005
IMPLEMENTED ON: JANUARY 01, 2006
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC.
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Principles ... 5
4 Reagents and materials ... 5
5 Instruments and equipment ... 7
6 Sampling and specimen preparation ... 8
7 Preparation of molten samples ... 8
8 Analytical conditions and analytical procedures ... 10
9 Calculation of results ... 12
10 Test report ... 15
Appendix A (Normative) Flowchart of acceptance procedures for sample analysis value
... 16
Appendix B (Normative) Calculation of inter-element correction factors and unknown
sample content ... 17
Appendix C (Normative) Standard deviation of specimen preparation ... 19
Appendix D (Informative) Source program of "Self-consistent correction program" 21
Iron ores - Determination of calcium, silicon, manganese,
titanium, phosphorus, magnesium, aluminium and barium
content - Wavelength dispersive X-ray fluorescence
spectrometric method
WARNING - Persons using this standard shall have practical experience in formal
laboratory work. This Part does not address all possible safety issues. It is the
user's responsibility to take appropriate safety and health measures and ensure
compliance with the conditions stipulated in the relevant national laws and
regulations.
1 Scope
This standard specifies the method for determining the content of calcium, silicon,
magnesium, titanium, phosphorus, manganese, aluminum, barium in iron ore, by
wavelength dispersive X-ray fluorescence spectrometer.
This standard is applicable to the determination of the content of 8 elements, as listed
in Table 1, in iron ore and artificial rich ore. The determination range (mass fraction) of
each element is as shown in Table 1.
Table 1 -- Determination range of each element
2 Normative references
The provisions in following documents become the provisions of this Standard through
reference in this Standard. For the dated references, the subsequent amendments
Element Determination range (mass fraction)/%
(excluding corrections) or revisions do not apply to this Standard; however, parties who
reach an agreement based on this Standard are encouraged to study if the latest versions
of these documents are applicable. For undated references, the latest edition of the
referenced document applies.
GB/T 6379 Precision of test methods - Determination of repeatability and
reproducibility for a standard test method by interlaboratory tests (GB/T 6379-1986,
neq ISO 5725:1986)
GB/T 6730.1 Methods for chemical analysis of iron ores - Preparation of predried
test samples for chemical analysis (GB/T 6730.1-1986, eqv ISO 7764:1985)
GB/T 10322.1 Iron ores - Sampling and sample preparation procedures (GB/T
10322.1-2000, idt ISO 3082:1998)
JJG 810-1993 National Metrology Verification Regulations of the People's Republic
of China - Wavelength Dispersive X-Ray Fluorescence Spectrometers
3 Principles
The sample is prepared as a borate glass-like molten sample, to measure the X-ray
fluorescence intensity of the element to be measured. Measure the background at the
position of the analysis line of the blank molten sample; subtract it as the sample
background. The melt samples are synthesized and corrected by pure chemical reagents,
to obtain the results, after correcting the matrix effect between elements, by applying
the principle of self-consistent correction.
4 Reagents and materials
Unless otherwise stated in the analysis, only approved reagents of analytical grade are
used.
4.1 Ferric oxide (Fe2O3), guaranteed reagent.
Burn ferric oxide at 1000 °C for at least 1 h. Then cool it in a desiccator.
4.2 Silicon dioxide (SiO2), guaranteed reagent.
Heat the silica to 1000 °C. Burn for at least 1 h. Then cool it in a desiccator.
4.3 Calcium carbonate (CaCO3), guaranteed reagent.
Bake the calcium carbonate at 105 °C for 1h. Then cool it in a desiccator.
4.4 Magnesium oxide (MgO), guaranteed reagent.
Burn the magnesium oxide at 1000 °C for 1 h. Then place it in a desiccator. Weigh it
immediately, after cooling.
4.5 Aluminum oxide (Al2O3), guaranteed reagent, α-type.
Burn the aluminum oxide at 1000 °C for at least 2 hours (if the aluminum oxide is not
in the α-type, it shall be heated to 1250 °C for at least 2 hours, to convert it into the α-
type); then cool it in the desiccator.
4.6 Titanium dioxide (TiO2), guaranteed reagent.
Burn the titanium dioxide at 1000 °C for at least 1 h. Then cool it in a desiccator.
4.7 Manganese oxide (Mn3O4), guaranteed reagent.
Place the manganese dioxide (MnO2) in a platinum crucible. Burn it at 1000 °C for 24
h. Cool it. Break the resulting bulk material into fine powder. Sinter it at 550 °C for 1
h. Then cool it in a desiccator.
4.8 Potassium dihydrogen phosphate (KH2PO4), guaranteed reagent.
Bake the potassium dihydrogen phosphate at 105 °C for 1h. Then cool it in a desiccator.
4.9 Barium carbonate (BaCO3), guaranteed reagent.
Dry the barium carbonate at 105 °C for 1 h. Then cool it in a desiccator.
4.10 Potassium carbonate (K2CO3), guaranteed reagent.
Bake the potassium carbonate at 105 °C for 1 h. Then cool it in a desiccator.
4.11 Sodium nitrate (NaNO3)
Bake the sodium nitrate at 105 °C for 1 h. Then cool it in a desiccator.
4.12 Ammonium iodide (NH4I)
Ammonium iodide does not need to be dried, BUT shall be stored in a desiccator.
4.13 Desiccant
The desiccant shall be freshly regenerated self-indicating silica gel.
4.14 Flux
Use guaranteed reagent anhydrous lithium tetraborate (Li2B4O7). Burn it at 500 °C for
4 hours. Then cool and store it in a desiccator.
4.15 Synthetic calibration sample (S)
950 °C).
5.3 Crucible and mold
The crucible and the mold (or the crucible also used as a mold) are made of non-wetting
platinum-gold or platinum-gold-rhodium, which is not easy to deform, after heating and
melting operation. The crucible shall have sufficient capacity, to hold the flux and
specimen required for melting. The mold shall have a flat bottom, which is thick enough
to prevent deformation. (It should not be used, when the thickness of the bottom is less
than 1 mm).
Since the bottom surface of the melted sample is the analysis surface, the inner surface
of the bottom of the mold shall be flat; it is regularly polished with a diamond abrasive
of about 12 μm.
6 Sampling and specimen preparation
Take samples and prepare specimens, according to the provisions of GB/T 10322.1.
Prepare pre-dried specimens, according to the provisions of GB/T 6730.1.
7 Preparation of molten samples
7.1 The preparation accuracy of the molten sample shall meet the requirements in
Appendix C.
7.2 Preparation of calibration S samples, calibration samples, blank samples
Weigh the reagents, according to the amount of reagents listed in Table 3, accurate to
0.0002 g. Add 6.000 g of flux (4.14) and 0.360 g of sodium nitrate (4.11). After fully
mixing, place it in a crucible (5.3). Pre-oxidize it at 700 °C, for 8 min ~ 10 min. Then
heat up to 1050 °C ~ 1100 °C for 10 min to melt. Shake the melt in the crucible, during
this time. After cooling, add 0.03 g of ammonium iodide (4.12) and melt for 3 min.
After taking out, cool and strip the melt in the crucible (or the melt is injected into the
mold for cooling and stripping).
Use the independently produced calibration samples (S), to prepare duplicate
calibration S samples, calibration samples, blank samples.
m0 - The specimen weight, in grams (g);
m1 - The specimen weight after burning, in grams (g).
7.4 Preparation of unknown samples
Weigh 0.6000 g of the burned sample (7.3) and 0.1548 g of potassium carbonate (4.10),
accurate to 0.0002 g. The rest operations follow the requirements of 7.2.
7.4.1 Visual inspection
After the molten sample is prepared, visually inspect the molten sample for defects such
as unmolten substances, crystals or air bubbles. The defective molten sample shall be
discarded; a qualified molten sample shall be prepared again.
7.4.2 Storage of molten samples
In order to prevent the molten sample from absorbing water or being contaminated,
quickly put the molten sample into the desiccator (when the molten sample is still
warm); do not touch the analysis surface with hands; do not handle it in any way,
especially do not rinse with water or other solvents, grinding or polishing.
7.4.3 Cleaning of crucibles and molds
Between two melting operations, the crucible and mold need to be cleaned. Usually
soak in hot hydrochloric acid (1 + 1) for about 1 h. Visually check that all residual melts
have been removed. Use distilled water to rinse it clean. Use it after drying.
Conditional laboratories can also use the quick cleaning method. Put the crucible or
mold into a beaker, which is filled with hydrochloric acid (about 2 mol/L). Put it in an
ultrasonic bath, until all residual melt is removed. Use distilled water to rinse it clean.
Use it after drying.
8 Analytical conditions and analytical procedures
8.1 Analytical conditions
This standard recommends the use of the following analysis conditions:
1) See Table 4, for analysis lines and analysis crystals;
2) The X-ray fluorescence measurement intensity of each element in the calibration
S sample is not lower than the count value, which is listed in Table 4;
3) Using proportional counters and (or) scintillation counters, pulse height selectors;
the specimen rotates during measurement;
9 Calculation of results
9.1 Calculation of inter-element correction factor and specimen content
According to the methods listed in B.2.1.1 ~ B.2.1.3 in Appendix B, take the average
of the two sets of calibration S samples prepared independently and the X-ray
fluorescence intensity of the calibration samples; input it into the computer program, to
calculate the inter-element correction factor.
Note 1: This correction factor can be used for a long time, for the same wavelength dispersive
X-ray fluorescence spectrometer, under the same equipment and experimental conditions.
Note 2: If the sample to be tested contains a component that seriously interferes with the element
to be measured, this component needs to be used as a residue item, to synthesize a residue
calibration sample. According to the principle of self-consistent correction, a parameter is added
in the correction factor calculation program, to calculate the correction factor of the residue to
each analyte.
Note 3: When using a different production batch of flux, the flux blank shall be re-measured.
Note 4: When using 100% Si sheet as the blank sample, the measurement of manganese element
content needs to be chemically corrected.
According to the methods listed in B.2.2 ~ B.2.3 in Appendix B, input the X-ray
fluorescence intensity of the unknown sample into the computer program, to calculate
the specimen content.
9.2 General processing of analysis results
9.2.1 Repeatability and tolerance
The precision of this standard is determined, according to the statistics of GB/T 6379
based on the results of 8 laboratories, by measuring 6 horizontal specimens. The
precision is as shown in Table 5.
Appendix B
(Normative)
Calculation of inter-element correction factors and unknown sample content
B.1 Scope
This Appendix specifies the method for calculating inter-element correction factors and
unknown sample contents, using a computer program.
B.2 Operation
B.2.1 Calculation of factor
B.2.1.1 Registration of measurement components
Run c:\tk\tk.prg under MicrosoftVisualFoxPro6.0. Enter the 'Registration of
measurement component' in the 'Coefficient calculation program'. Register the content
of each element (oxide content) in the S sample, in the ratio column, such as: Fe: 0.6700;
Si: 0.10; Ca: 0.065; Mg: 0.05; Al: 0.05; Ti: 0.015; Mn: 0.02; P: 0.02; Ba: 0.01. In the
column of S amount, register the proportion of standard mixture S in each calibration
sample, Fe: 0.50; Si: 0.50; Ca: 0.75; Mg: 0.75; Al: 0.75; Ti: 0.75; Mn: 0.75; P: 0.75; Ba:
0.75. Save the registered data and return it.
B.2.1.2 Registration of standard intensity
Enter 'Standard intensity registration'. Register the fluorescence intensity of each
sample after subtracting the intensity of the blank sample, in the order of S sheet, Fe
sheet, Si sheet, Ca sheet, Mg sheet, Al sheet, Ti sheet, Mn sheet, P sheet, Ba sheet. Close
the database and return to the previous menu.
B.2.1.3 Calculation of correction factor
Return to the previous menu, after entering 'Correction factor calculation'. After the
correction factor calculation is completed, click "Exit", to return to the main menu.
B.2.2 Content calculation
B.2.2.1 Registration of blank strength
Enter "Content calculation program" in the main menu. Enter 'Registration of blank
intensity'. Record the X-ray fluorescence intensities of Si, Ca, Mg, Al, Ti, P in 100% Fe
sheet and the X-ray fluorescence intensity of Fe, Mn, Ba in 100% Si sheet. Close the
database and return to the previous menu.
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.