Overview
ISO 923:2022 - "Coal - Density separation equipment for coal - Performance evaluation" defines principles, test methods and presentation formats for evaluating density-based coal cleaning equipment. The third edition (2022) updates performance measures and example calculations, and is intended to enable consistent evaluation, comparison and prediction of separation performance for equipment that uses relative density (RD) as the primary separation characteristic (e.g., dense‑medium separators, jigs, spiral separators, hindered‑settling cleaners, shaking tables and water‑only cyclones).
Key topics and technical requirements
- Scope and applicability: Performance evaluation for RD‑based coal cleaning equipment; applicable equipment types are explicitly listed.
- Performance measures: Feed rate, reference density of separation (partition density / equal‑errors cut‑point), sharpness of separation (probable error, imperfection), correctly placed vs misplaced material, ash error, yield error, degree of difficulty (near‑density material), and bypass fractions (low‑density tail at RD 1.20 and high‑density tail at RD 2.70).
- Sampling & testing procedures: Representative sampling from feed and each product stream, size fractionation and float/sink analysis in line with established standards; maintain and report uniform feed-rate and test conditions.
- Analytical procedures: Use ISO 1953 (size analysis) and ISO 7936 (float and sink) approaches; determine RD ranges for floats and sinks for each size fraction.
- Expression and reporting of results: Multiple methods provided (partition curves, M‑curves/washability curves, ash/yield error, partition coefficients, imperfection). Annexes include recommended tabulations and graphical presentations for consistent reporting.
- Performance prediction & guarantees: Formulations permit comparison, prediction and contractual performance checks; test conditions and possible impacts of differing operational conditions must be reported.
Practical applications
- Standardizes how laboratories, plant engineers and equipment manufacturers:
- Evaluate and benchmark separator accuracy and efficiency
- Diagnose separation problems (sharpness, bypass, misplaced material)
- Prepare performance guarantees and acceptance tests
- Predict product quality (ash, yield) from test data
- Useful for commissioning, process optimization, tendering and regulatory/commercial reporting in coal preparation plants.
Who should use ISO 923:2022
- Coal preparation and beneficiation engineers
- Equipment manufacturers and suppliers (dense‑medium systems, jigs, cyclones, tables)
- Test laboratories and quality assurance teams
- Mine/process consultants and contract/claims specialists
Related standards (referenced)
Keywords: ISO 923:2022, density separation equipment, coal cleaning, relative density, partition density, partition curves, ash error, yield error, bypass fractions, float and sink, performance evaluation.
