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D4596-22 – Standard Test Method Technical Guide
ASTM D4596-22 standardizes the collection of channel samples from coal seams in mines. This practice is essential for obtaining representative samples for quality characterization, rank classification, and resource assessment.
🔍 Scope and Significance
This practice describes the procedure for collecting a coal sample from a channel cut in the face of a coal seam, extending from top to bottom. The values stated in SI units are standard. Proper collection ensures a representative cross-section, which is critical for coal quality evaluations, mining planning, and classification per D388. Channel samples should not be used for commercial shipment evaluation, as per Note 2.
🛠️ Required Apparatus and Specifications
The following apparatus are necessary for accurate channel sampling:
| 🛠️ Apparatus | 📏 Requirement |
|---|---|
| Steel Measuring Tape | Not less than 3 m (8 ft) long |
| Miner’s Pick or Similar Tool | With file for sharpening; pneumatic chain saw with tungsten carbide teeth may be used |
| Brush or Broom | For removing loose particles from the coal face |
| Chalk | For marking the sampling area |
| Sample Containers with Closures | Must limit weight loss to less than 0.05% for moisture determination |
💡 Technical Note: For inherent moisture determination, use containers that prevent moisture loss exceeding 0.05% of the sample weight.
📝 Sampling Procedure and Key Considerations
At each selected site, clean the coal face of weathered material and debris, and even the surface. Cut a channel of uniform horizontal cross-section from the seam, collecting all coal. The sample should include the total coal bed interval to ensure representativeness. Due to lateral variability, multiple samples may be necessary. Channel samples are not suitable for evaluating commercial shipments; use Methods D2234/D2234M for that purpose.
⚠️ Caution: Channel samples are intended for in-mine quality assessment and not for commercial shipment evaluation. Refer to Note 2 for more details.
❓ Frequently Asked Questions
🔍 What does a channel sample represent?
A properly collected channel sample provides a representative cross-section of the coal bed at the sampling point, useful for quality and rank determination.
💡 How is the sampling site prepared?
The face of the seam is cleaned of weathered coal and debris, and the face is evened to ensure a uniform channel sample.
⚡ What are the key apparatus requirements?
A steel measuring tape of at least 3 m (8 ft), miner’s pick or similar tool, brush, chalk, and sample containers with closures limiting moisture loss to less than 0.05%.
📌 When should channel samples not be used?
Channel samples should not be used for evaluating the quality of commercial shipments; instead, use Methods D2234/D2234M for mine product sampling.