Overview
ISO 8723:1986 is an international standard developed by the International Organization for Standardization (ISO) that specifies a solvent extraction method to determine the oil content in calcined coke used in aluminium production. Calcined coke often undergoes treatment with various oils to minimize dust formation during handling and transport. Accurate measurement of residual oil content is critical for quality control and environmental safety in aluminium manufacturing.
This standard outlines a reliable process for extracting oil adhering to coke particles using dichloromethane (methylene chloride) as the solvent. It quantifies oil content by measuring the mass loss of calcined coke after solvent extraction. Adopted by ISO Technical Committee ISO/TC 47, Chemistry, this method ensures consistency and repeatability in testing carbonaceous materials in the aluminium industry.
Key Topics
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Scope and Purpose
ISO 8723:1986 applies specifically to calcined coke treated with oil to reduce dust during loading and transport. It provides a precise methodology for extracting and measuring oil content to evaluate coke quality before use in aluminium production.
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Solvent Extraction Principle
The standard uses dichloromethane-a solvent with boiling point between 39°C and 40°C-to dissolve and remove oil from calcined coke samples. The oil extraction happens inside a specialized glass extraction apparatus, followed by drying and weighing to determine the oil percentage by mass.
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Equipment and Materials
Key apparatus include a glass extraction unit with fritted glass discs, a vacuum filtration flask, an electric oven adjustable to 110 ± 2°C, and PTFE joints for airtight sealing. The solvent must be of high purity (minimum 99%) and handled with care due to its toxicity.
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Sample Preparation and Testing Steps
Samples of calcined coke are ground and passed through a 4 mm sieve, then dried before testing. After weighing, samples undergo cyclic solvent extraction with dichloromethane, drying, and reweighing. The difference in mass before and after extraction gives the oil content.
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Accuracy and Reliability
The standard provides repeatability and reproducibility data based on interlaboratory tests involving nine laboratories, confirming the method’s precision in assessing oil content. Results must be averaged over at least two determinations for accuracy.
Applications
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Quality Control in Aluminium Industry
Ensuring the optimal oil content in calcined coke helps maintain production efficiency and workplace safety by limiting dust formation. The method supports consistent quality checking during raw material processing.
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Environmental Compliance
Accurate determination of oil residues prevents environmental contamination from oil-treated coke during transport and handling and informs corrective action when excessive oil content is detected.
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Research and Product Development
Manufacturers of calcined coke and related carbonaceous materials use this method to validate new oil treatments or modifications, ensuring their products meet industrial standards and regulations.
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Supplier Verification
Aluminium producers and coke suppliers can use ISO 8723:1986 to verify oil treatment consistency and compliance with contractual specifications.
Related Standards
- ISO 6375 – Specifies sampling requirements for carbonaceous materials used in aluminium production, including coke sampling techniques.
- ISO 565 – Covers standard sieving methods applicable to sample preparation of granular materials like calcined coke.
- ISO 5725 – Defines accuracy (repeatability and reproducibility) of measurement methods and results, supporting the reliability claims of this standard.
By following ISO 8723:1986, industries involved in aluminium production and carbon material processing can accurately quantify oil content in calcined coke, ensuring product quality, safety, and environmental protection through a recognized, standardized solvent extraction approach.
Open preview (PDF)Carbonaceous materials for the production of aluminium — Calcined coke — Determination of oil content — Method by solvent extraction