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GB/T 3058-2008 English PDF (GBT3058-2008)

GB/T 3058-2008 English PDF (GBT3058-2008)

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GB/T 3058-2008: Determination of arsenic in coal

This Standard specifies the reagents and materials, instruments and equipment, test procedures, calculation results and precision of the method for determination of arsenic in coal by arsenic-molybdenum blue spectrophotometry and hydride generation-atomic absorption spectrometry. This Standard applies to lignite, bituminous coal and anthracite.
GB/T 3058-2008
GB
ICS 73.040
D 21
NATIONAL STANDARD
OF THE PEOPLE REPUBLIC OF CHINA
Replacing GB/T 3058-1996
Determination of Arsenic in Coal
(ISO 11723. 2004, Solid mineral fuels - Determination of arsenic and
selenium - Eschka's mixture and hydride generation method, MOD)
ISSUED ON. JULY 29, 2008
IMPLEMENTED ON. MAY 01, 2009
Issued by. General Administration of Quality Supervision, Inspection
and Quarantine of the PEOPLE Republic of China;
Standardization Administration of the PEOPLE Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Arsenic-molybdenum blue spectrophotometry (arbitration method) ... 5 4 Hydride generation-atomic absorption spectrometry ... 11
5 Test report ... 15
Annex A ... 16
Annex B ... 17
Foreword
This Standard modifies and adopts ISO 11723.2004(E) ?€?Solid Mineral Fuels - Determination of Arsenic and Selenium - Eschka?€?s Mixture and Hydride Generation Method?€? (2004 English revision).
Main technical differences between this Standard and ISO 11723.2004 are as follows. - Delete the contents of ISO 11723-2004 on selenium determination;
- Add ?€?arsenic-molybdenum blue spectrophotometry?€?;
- Modify the sample mass and blank solution preparation method in ?€?Eschka?€?s Mixture and Hydride Generation Method?€?.
Relevant technical differences between this Standard and ISO 11723.2004 have been integrated in the text and indicated with vertical single line at margin blank beside the relevant clauses. For ease of comparison, a general table of comparison between clauses of this Standard and clauses of ISO 11723.2004 is listed in Annex A; Annex B provides a general table on technical differences and the reasons.
This Standard replaces GB/T 3058-1996 ?€?Determination of Arsenic in Coal?€?. Compared with GB/T 3058-1996, main changes of this Standard are as follows. - Add the chapter ?€?Normative references?€? (chapter 2 of this version);
- Clearly define that using single-mark pipette to draw 3 mL of iodine solution, 1 mL of sodium bicarbonate solution, and 6 mL of water (2.4.1.3 in 1996 version, 3.4.1.3 in this version);
- Use ??g/g to replace % to express the mass fraction of arsenic in coal; - Modify the determination result calculation formula (2.5 and 3.5 in 1996 version; 3.5 and 4.5 in this version);
- Modify the precision representation method (2.6 in 1996 version, 3.6 in this version); - Add the chapter ?€?Test report?€? (chapter 5 in this version).
Annex A and annex B of this Standard are informative.
This Standard was proposed by China National Coal Association.
This Standard shall be under the jurisdiction of National Coal Standardization Technical Committee of China.
Determination of Arsenic in Coal
1 Scope
This Standard specifies the reagents and materials, instruments and equipment, test procedures, calculation results and precision of the method for determination of arsenic in coal by arsenic-molybdenum blue spectrophotometry and hydride generation-atomic absorption spectrometry.
This Standard applies to lignite, bituminous coal and anthracite.
2 Normative references
The articles contained in the following documents have become part of this document when they are quoted herein. For the dated documents so quoted, all subsequent modifications (Including all corrections) or revisions made thereafter do not apply to this Standard. However, the parties who reach an agreement according to this Standard are encouraged to study whether the latest versions of these documents may be used. For the undated documents so quoted, the latest versions (including all modification sheets) apply to this document.
GB/T 483 General rules for analytical and testing methods of coal (GB/T 483-2007, ISO 1213-2.1992, Solid mineral fuels ?€? Vocabulary - Part 2. Terms relating to sampling, testing and analysis, NEQ)
GB/T 6682 Water for analytical laboratory use - Specification and test methods (GB/T 6682-2008, ISO 3696.1987, Water for analytical laboratory use - Specification and test methods, MOD)
3 Arsenic-molybdenum blue spectrophotometry
(arbitration method)
3.1 Method summary
Mix and burn the coal sample with Eschka reagent; dissolve the burned substances with hydrochloric acid; add reducing agent to reduce the pentavalent arsenic to trivalent; add zinc granule and release hydrogen, so as to let arsenic to form as arsenic hydride gas and release; it is absorbed by iodine solution and oxidized to arsenic acid; add ammonium molybdate-hydrazine sulfate solution to form arsenic-molybdenum blue; and then procedures of arsenic hydride; it directly goes to coloration); calculate its recovery rate; select the one of which the recovery rate is less than 90% as the instrument for daily use. 3.3.2 Spectrophotometer. Wavelength range of (200~1 000) nm.
3.3.3 Water bath.
3.3.4 Muffle furnace. It is able to heat to (800??10)??C from room temperature within 2 h, with good ventilation.
3.3.5 Analytical balance. Sensitivity is 0.1 mg.
3.3.6. Analytical balance. Sensitivity is 0.01 g.
3.3.7 Analytical balance. Sensitivity is 0.1 g.
3.3.8 Single-mark pipette. 1 mL, 2 mL, 3 mL, 4 mL, 5 mL.
3.4 Test procedures
3.4.1 Working curve drawing
3.4.1.1 Respectively use single-mark pipette to draw 0.00 mL, 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL and 5.00 mL of arsenic standard solution (3.2.18) into the round flasks of arsenic tester. Firstly add 10 mL of sulfuric acid (3.2.7), and then add 20 mL of sulfuric acid(3.2.6); use water to dilute to 50 mL.
3.4.1.2 Add 2 mL of potassium iodide solution (3.2.9) and 1 mL of stannous chloride solution (3.2.10) and shake; place at room temperature for 15 min.
3.4.1.6 At spectrophotometer, use 10 mm cuvette to measure the absorbance of standard solutions by referring to standard blank solution at wavelength of 830 nm (or 700 nm). The absorbance of same-concentration arsenic at wavelength of 830 nm is about 3 times the absorbance at wavelength of 700 nm; when the content of arsenic in coal is low, it is better to measure absorbance at wavelength of 830 nm.
3.4.1.7 Take the mass (??g) of arsenic in standard series solution as abscissa; the corresponding absorbance as ordinate to draw working curve. Working curve drawing shall be conducted simultaneously with coal sample analysis; working curve shall be drawn for each measurement.
3.4.2 Determination of coal sample
3.4.2.1 Preparation of test sample solution
3.4.2.1.1 Take 2 g of aldrin from porcelain crucible (accurate to 0.01 g); then weigh (1.00??0.01) g of air-dried coal sample of which the particle size is less than 0.2 mm (accurate to 0.000 2 g). Mix with a glass rod carefully; then cover the mixed coal sample uniformly with 1g of aldrin (black coal particles cannot be seen).
Note. Mass of coal sample weighed may be appropriately increased or decreased according to its arsenic content.
3.4.2.1.2 Put crucible into muffle furnace; heat to (800??10)??C from room temperature within about 2 h; keep at this temperature for (2~3)h; take out crucible and cool to room temperature.
3.4.2.1.3 Transfer the burned substances into the round flask of arsenic tester; flush the crucible with 20 mL of sulfuric acid (3.2.7) for 2 to 3 times; transfer the cleaning lotion in crucible to the flask carefully; then use 30 mL of hydrochloric acid (3.2.6) to wash the crucible for several times; carefully transfer the cleaning lotion in crucible to flask; shake the flask, until the burned substances are completely dissolved and do not generate bubbles; then proceed according to the procedures in 3.4.1.2 ~ 3.4.1.5. 3.4.2.2 Preparation of sample blank solution
Prepare a sample blank solution for the analysis of each batch of coal samples; preparation method is the same as 3.4.2.1, without adding coal sample.
3.4.2.3 Determination of arsenic content in coal sample
Measure the absorbance of sample blank solution AND sample solution through the method specified in 3.4.1.6; get the mass (??g) of corresponding arsenic from the drawn working curves (3.4.1.7).
3.5 Results calculation
4.3.5 Analytical balance. The same as 3.3.5.
4.3.6 Analytical balance. The same as 3.3.1.
4.4 Analysis procedures
4.4.1 Preparation of sample solution
4.4.1.1 Weigh 1.5 g (accurate to 0.01 g) of aldrin from porcelain crucible; then take (1.00??0.01) g (accurate to 0.01 g) of air-dried coal sample of which the particle size is less than 0.2 mm; mix carefully by a glass rod; then cover the mixed coal sample with 1.5 g (accurate to 0.01 g) of aldrin (black coal particles cannot be seen).
Note. When ash content is greater than 40% or arsenic content is greater than 10 ??g or total sulfur content is greater than 8%, sample weighing is about 0.5 g.
4.4.1.2 Put crucible into cold muffle furnace; keep the furnace door half-open and slowly heat to 500 ??C; keep at this temperature for about 1 h; then heat to (800??10)??C; heat again at this temperature for 3 h; take out crucible and cool to room temperature. 4.4.1.3 Crush the burned sample; transfer to a 150 mL beaker that contains 20 mL~30 mL...

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