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D2492-02 – Standard Test Method Technical Guide
🧪 Scope and Test Method Summary
ASTM D2492-02 (Reapproved 2012) specifies the determination of sulfate sulfur and pyritic sulfur in coal, with organic sulfur calculated by difference. This method is strictly applicable to coal and is not intended for coke or other carbonaceous materials. The standard notes that while monosulfides of iron and elements such as cadmium, lead, vanadium, and zinc can be present in coal, their contribution is considered insignificant in the range of 0 to 100 ppm.
⚠️ Key Note: In the range of 0 to 100 ppm, monosulfides do not contribute significantly to the total inorganic sulfide content in coal.
⚙️ Analytical Procedures for Sulfur Forms
Sulfate Sulfur: The analysis sample is extracted with dilute hydrochloric acid. Pyritic and organic sulfur remain insoluble while the sulfate sulfur is extracted into solution and determined gravimetrically.
Pyritic Sulfur: Calculated through a stoichiometric relationship with iron. The Referee Method extracts iron with dilute nitric acid from the coal residue remaining after the sulfate extraction step. The iron is quantified using atomic absorption techniques. Plasma emission methods can yield equivalent results but are susceptible to interferences from other dissolved analytes.
💡 Technical Guidance on Iron Analysis: Plasma emission techniques can give results equivalent to atomic absorption, but are highly susceptible to interferences from other analytes dissolved during the iron extraction.
| 🧪 Sulfur Form | 📌 Extraction Method | 🎯 Quantification Technique |
|---|---|---|
| Sulfate Sulfur | Dilute Hydrochloric Acid | Gravimetric |
| Pyritic Sulfur (Referee) | Dilute Nitric Acid (on residue) | Atomic Absorption (Iron) |
| Organic Sulfur | N/A (Calculated) | Calculation by Difference |
The method relies on several key ASTM practices for sample preparation and analysis, including D2013 for sample preparation and D3173 for moisture determination.
| 📐 Designation | 🟦 Description |
|---|---|
| D2013 | Practice for Preparing Coal Samples for Analysis |
| D3173 | Test
📥 Standard Documents Download |