1 Scope
This standard specifies the reagents, apparatuses, procedures, result expression and precision for the determination of total phosphorus in coke.
This standard is applicable to semi-coke and coke.
2 Normative References
The following documents contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, all the editions indicated are valid. All standards are subject to revision. All parties coming to an agreement according to this standard are encouraged to study whether the latest edition of the normative document is applicable.
GB/T 1997-1989 Coke - Sampling and Preparation of Samples
GB/T 2001-1991 Coke - Determination of Proximate Analysis
3 Method Summary
After ashing, the sample is decomposed with hydrofluoric acid - sulfuric acid to remove silicon dioxide. Then ammonium molybdate and ascorbic acid are added to generate phosphomolybdenum blue, then to subject to colorimetric determination.
4 Reagents
Unless otherwise specified, analytical reagents, distilled water or water of same purity are used in this standard.
4.1 Hydrofluoric acid (GB/T 620): above 40% in mass fraction.
4.2 Sulfuric acid: c(1/2H2SO4)＝10mol/L; measure 278mL of concentrated sulfuric acid (GB/T 625), slowly add it in water while stirring and then dilute with water to 1,000mL.
4.3 Ammonium molybdate solution: dissolve 60g of ammonium molybdate (GB/T 657) in 1,000mL of water.
4.4 Ascorbic acid solution: dissolve 5g of ascorbic acid in 100mL of water; it is prepared immediately before use.
