GB/T 4633-2014Determination of fluorine in coal (English PDF)

Foreword

This Standard is drafted according to the rules of GB/T 1.1-2009.

This Standard replaces GB/T 4663-1997 Determination of fluorine in coal. Compared with GB/T 4663-1997, the major changes of this standard are as follows.

- ADD normative references (see Chapter 2);

- ADD result reports (see Chapter 10);

- MODIFY the calculation formula of fluorine content in coal;

1 Scope

This Standard specifies the method abstract, reagents and materials, apparatus and device, measurement steps, result calculation, method precision, and test reports of using high temperature combustion hydrolysis - fluoride ion selective electrode (abbreviated as. fluoride electrode) method to determine the fluorine content in coal. This Standard applies to lignite, bituminous coal, and anthracite.

2 Normative references

The following documents are essential for the application of this document. For dated references, only the dated editions apply to this document. For undated references, the latest editions (including all corrections) of the referenced documents apply to this document.

GB/T 483 General rules for analytical and testing methods of coal

GB/T 6682 Water for analytical laboratory use - specification and test methods

3 Method abstract

Samples of coal are burned and hydrolyzed in the mixed gas stream of oxygen and vapor.

4 Reagents and materials

Unless otherwise indicated, it shall only use the analytic reagents and distilled water that are confirmed qualified, or deionized water, or water with equivalent purity.

4.1 Water. GB/T 6682, Grade 2.

4.2 Silica sand (SiO2). Particle size is 0.5mm~1.0mm.

4.8 Fluorine standard stock solution. 1000µg/mL. Weigh 2.2101g of guaranteed-reagent sodium fluoride, which has been dried at 120°C for 2 hours, into a beaker. Add water to dissolve. Use water to wash it into a 1000 mL volumetric flask. And dilute to the scale. Shake well. Store it in the plastic bottle that does not contain fluorine as the stock solution for spare use.

4.9 Fluorine standard working solution. 100µg/mL, 250µg/mL, 500µg/mL. Use fluorine standard working solution to respectively prepare 100µg/mL, 250µg/mL, and 500µg/mL of standard working solution. Store it in the plastic bottle that does not contain fluorine for spare use.

4.10 Bromocresol green indicator. Ethanol solution, 10g/L. Weigh 1 g of bromocresol green indicator to dissolve into 100mL of anhydrous ethanol.

4.12 Injection push rod. The mental rod with silicon stopper; the top is bent into disc-shaped; and temperature resistance is above 1100°C.

4.13 One-mark volumetric flask. 100mL. Class.

4.14 One-mark pipette. 1mL, 2mL, 5mL, and 10mL. Class.

5 Apparatus and device

6 Coal combustion temperature hydrolysis

7 Potential measurement

8 Results presentation

8.1 Fluorine content in coal (Fad) shall be calculated according to Formula (1). The determination result is rounded to the integer.

8.2 The fluorine content in coal shall be based on the average value of 2-times repeated determination results. It shall be rounded to integer according to GB/T 483.

9 Precision of methods

Repeatability limit and reproducibility critical difference of determination results for fluorine in coal is specified in Table 1.

10 Test report

Test report shall at least contain the following information. […]