1 Scope
This standard specifies the principle, reagents and materials, equipment, test procedures, calculation of results and precision for determination of carbon and hydrogen in coal and coal water mixture by Liebig method, determination of hydrogen in coal and dry coal samples of coal water mixture by coulometric method, and determination of carbon by grametric method.
This standard is applicable to lignite, soft coal, anthracite and coal water mixture.
2 Normative References
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this standard. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 212 Proximate Analysis of Coal (GB/T 212-2008, ISO 11722:1999, ISO 1171:1997, ISO 562:1998, NEQ)
GB/T 218 Determination of Carbon Dioxide Content in the Mineral Carbonates Associated with Coal (GB/T 218-1996, eqv ISO 925:1980)
GB/T 18856.1 Test Methods for Quality of Coal Water Mixture — Part 1: Sampling
3 Liebig Method (Three-section Furnace and Two-section Furnace)
3.1 Principle
A known mass of coal sample or coal water mixture is burnt in a current of oxygen in a tube impervious to gases, and the water and carbon dioxide generated are absorbed by water absorbent and carbon dioxide absorbent respectively. The mass fraction of carbon and hydrogen in coal is calculated by the increment of absorbent. The interference of sulfur and chlorine on carbon determination in coal samples was eliminated by lead chromate and silver coil in three-section furnace, and by pyrolysis products of silver permanganate in two-section furnace. The interference of nitrogen to carbon determination was eliminated by granular manganese dioxide.
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3.2 Reagents and materials
3.2.1 Magnesium perchlorate, anhydrous, particle size 1 mm to 3 mm; or anhydrous calcium chloride: anhydrous, particle size 2 mm to 5 mm.
3.2.2 Granular manganese dioxide: chemically pure, commercially available or prepared from manganese sulfate and potassium permanganate.
Preparation method: 25 g manganese sulfate was weighed and dissolved in 500 mL distilled water, and 16.4 g potassium permanganate was weighed and dissolved in 300 mL distilled water. The two solutions were heated to 50°C to 60°C respectively. The potassium permanganate solution is slowly injected into the manganese sulfate solution under constant agitation and is stirred vigorously. Then add 10 mL (1+1) sulfuric acid. The solution was heated to 70°C to 80°C and stirred for 5 min, then the heating was stopped. Keep it still for 2 to 3 h. Wash to neutral by pouring hot distilled water. The precipitate was moved to a funnel for filtration to remove water, and then put into a drying oven to dry at 150°C for 2 to 3 h to obtain brown and loose manganese dioxide. It was carefully broken and screened, and the particle size was 0.5 mm to 2 mm for use.
3.2.3 Copper wire coil: of wire diameter approximately 0.5mm. Copper gauze: 0.15mm (100 mesh).
3.2.4 Copper oxide, chemically pure, wire form (approximately 5 mm long).
3.2.5 Lead chromate, anhydrous, fused, size range 1 mm to 4 mm.
Preparation method: The commercially available lead chromate is made into a paste with distilled water and extruded. Put them into muffle furnace and burn them at 850°C for 2 h. Take them out and cool them for reserve.
3.2.6 Copper wire coil: of wire diameter approximately 0.25mm.
3.2.7 Oxygen: 99.9%. Hydrogen-free. Oxygen cylinders shall be fitted with pressure gauges with adjustable flow reducing valves (medical oxygen inhalers may be used).
3.2.8 Tungsten trioxide: anhydrous.
3.2.9 Alkali asbestos: chemically pure, particle size 1 mm to 2 mm; or alkali lime: chemical pure, particle size of 0.5 mm to 2 mm.
3.2.10 Vacuum silicone grease.
3.2.11 Pyrolysis products of silver permanganate: When two-section furnace is used, pyrolysis products of silver permanganate shall be prepared. The preparation method is as follows:
Dissolve 100 g potassium permanganate (chemically pure) in 2 L distilled water and boil. In addition, take 107.5g of silver nitrate (chemically pure) and dissolve it in about 50 mL distilled water, and slowly injected into boiling potassium permanganate solution under constant agitation. After being stirred evenly, it shall be gradually cooled and left standing overnight. The dark purple crystals generated shall be washed several times with distilled water and dried at 60°C to 80°C for 1 h. Then a small part of the crystals shall be placed in a porcelain dish and slowly heated on an electric furnace until they suddenly decomposed into silver-gray loose products, which are put into a grinding bottle for reserve.
Warning: Undecomposed silver permanganate is vulnerable to heat decomposition and shall not be stored in large quantities.
3.2.12 Sulfuric acid: chemically pure.
3.2.13 Glass tube or small dryer with grinding stopper (without desiccant).
3.3 Apparatus
Foreword II
1 Scope
2 Normative References
3 Liebig Method (Three-section Furnace and Two-section Furnace)
4 Coulometric and Gravimetric Method
5 Precision
6 Test Report
Annex A (Informative) Comparison of Clause Numbers in This Standard and the Equivalent Clauses in ISO 625:1996
Annex B (Informative) Technical Deviations between This Standard and ISO 625:1996 and Their Justifications
