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D167 – Standard Test Method Technical Guide
The ASTM D167/D167M standard provides a rigorous methodology for determining the apparent specific gravity, true specific gravity, and porosity of lump coke larger than 25 mm [1 in.] in size. These physical properties are critical indicators of coke quality, directly influenced by the carbonization process and directly impacting performance in subsequent metallurgical applications such as blast furnaces and foundries.
📐 Scope and Apparatus for Apparent Specific Gravity
The standard outlines specific dimensional requirements for the apparatus used in the water displacement method for apparent specific gravity. The container must be large enough to accommodate a representative sample in a wire basket without submersion interference. The table below summarizes the critical apparatus specifications derived from Sections 5.1.1 through 5.1.5.
| 🟦 Component | 📏 Dimensional Requirement | 🎯 Critical Notes |
|---|---|---|
| Container (Rectangular or Elliptical) | ~560 mm (22 in.) length x 280 mm (11 in.) width x 330 mm (13 in.) height | Features a 13 mm (0.5 in.) spout at 267 mm (10.5 in.) height |
| Wire Cage / Basket | ~13 mm (0.5 in.) square-mesh screen with cover & handles | Must fit entirely inside the container below the spout level |
| Receiving Vessel (Bucket) | 11 L (3.0 gal) | Suitable for capturing all displaced water |
| Drying Pan | ~380 mm (15 in.) square x 76 mm (3 in.) deep | Equivalent pans of the same volume are acceptable |
| Balance | Sensitivity of 0.05 kg (0.1 lb) | Minimum requirement for mass determination |
💡 Technical Note: The balance sensitivity of 0.05 kg is crucial for maintaining the accuracy of the apparent specific gravity calculation, as small discrepancies in mass can lead to significant errors in the final porosity results.
⚙️ Sampling and Core Procedure
Proper sampling is essential for representative results. For run-of-oven by-product coke, the standard mandates a sample of approximately 20 kg (50 lb), collected systematically from the entire coke wharf. This involves dividing the wharf into several equal areas and selecting an equivalent number of pieces from each area to ensure a representative bulk sample.
| ⚡ Parameter | 📐 Specification (from Section 6) |
|---|---|
| Coke Type | Run-of-oven Lump Coke (> 25 mm) |
| Sample Mass | Approximately 20 kg (50 lb) |
| Collection Location | Coke Wharf |
| Selection Method | Divide wharf into equal areas, pick equal pieces from each area |
The apparent specific gravity test involves saturating the coke pieces with water, measuring their mass in air and suspended in water, and calculating the volume via water displacement. Following this, the true specific gravity test (Sections 10-14) uses a finely ground sample to measure the volume of the solid material excluding internal pores.
📊 Porosity and Key Measured Properties
The porosity of the lump coke (Section 15) is calculated directly from the apparent and true specific gravity data. This value represents the percentage of the total volume occupied by pores, critical for understanding reactivity and strength. The properties are heavily influenced by the type of coals carbonized and the operating conditions of the prepared coals, such as charge bulk density, heating rate, and pulverization level.
✅ Standard Compliance Requirement: The values stated in either SI units or non-SI units are to be regarded separately as standard. To ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
⚠️ Safety and Regulatory Note: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
❓ Frequently Asked Questions
🔍 What specific size of lump coke does this standard apply to?
The standard explicitly covers the determination of specific gravity and porosity for lump coke larger than 25 mm [1 in.] in size. Pieces must be greater than this size threshold to be tested under this method.
💡 Why are both apparent and true specific gravity tested separately?
Apparent specific gravity measures the density of the entire lump, including its internal pores. True specific gravity measures the density of the solid coked material itself (with pores eliminated through grinding). Comparing the two values allows the calculation of the total porosity of the coke lump.
⚡ Where is the sample taken for a standard porosity test according to this method?
According to Section 6, when testing run-of-oven coke, the sample shall be collected from the coke wharf. The standard specifies selecting a total of about 20 kg (50 lb) of representative pieces.
📌 How are the results from this standard typically used in industry?
The apparent and true specific gravity measurements are critical quality control parameters. They are heavily influenced by the carbonization conditions (charge bulk density, heating rate, pulverization level) and directly influence the performance of coke in downstream processes like ironmaking in blast furnaces.