Overview
ISO/TS 4699:2022 specifies a manual laboratory method for determination of plastometric indices of hard coal. The standard defines two key plastometric parameters: the maximum thickness of the plastic layer (Y, mm) and the final contraction value (X, mm). It applies to hard coals with ash content less than 15% on a dry basis (see ISO 11722 and ISO 1171). ISO/TS 4699:2022 serves as a reference method against which faster instrumental plastometers can be validated.
Key Topics and Requirements
- Test principle: Unidirectional heating of a packed coal bed from the base under a constant applied pressure while the evolution of a plastic layer is monitored and recorded.
- Measured indices:
- Y (maximum plastic layer thickness) - calculated as the maximum perpendicular distance between fitted upper and lower plastic-layer displacement curves.
- X (final contraction) - perpendicular distance from the displacement-curve endpoint at 730 °C to the zero line defined at 250 °C (note: the standard explains the numerical relationship between measured displacement and actual displacement).
- Apparatus and consumables: Manual plastometer assembly (retort, electric furnace, pressure plate, probe, thermocouples, recording device, rotary drum), balance masses (optional), refractory pads, paper tube (cigarette rolling paper), filter paper, abrasive cloth, ceramic wool/cord.
- Sample preparation and loading: Specific guidance on crushing, sieving (1.5 mm), retort packing, and aligning thermocouple and probe positions is provided.
- Data processing: Manual periodic probing of upper/lower interfaces, recording the displacement curve, and fitting layer curves using least-squares to compute Y and X.
- Quality and precision: Clause 11 provides repeatability and reproducibility limits; instrumental methods must be demonstrated free from bias relative to this manual reference.
Applications and Users
ISO/TS 4699:2022 is intended for:
- Coal testing laboratories performing rheological characterization of coking/hard coals.
- Coke producers and metallurgical plants needing to assess coal plasticity for coke-making performance and blending.
- Research organizations studying coal thermoplastic behavior.
- Manufacturers of plastometers and laboratory equipment validating new instrumental methods against a manual reference.
- Quality assurance teams requiring standardized, traceable methods for regulatory or contractual testing.
Practical uses include coal selection and blending for coke quality, process control in coke ovens, validation/calibration of automated plastometers, and research into coal thermoplastic properties.
Related Standards
Relevant cross-referenced documents include:
Keywords: ISO/TS 4699:2022, plastometric indices, hard coal testing, manual plastometer, plastic layer Y, final contraction X, coal laboratory method, coking coal.