ISO 12989-2:2004

Overview

ISO 12989-2:2004 specifies a standardized thermogravimetric method for determining the reactivity to air and the air dusting rate of carbonaceous materials used in aluminium production, specifically baked anodes and sidewall blocks. By setting out clear procedures for thermogravimetric analysis (TGA), this international standard ensures that measurements of reactivity and dusting are reliable, comparable, and can be reproduced across different laboratories and types of apparatus.

These measurements are crucial for evaluating the quality and performance of carbon electrodes, which directly impact the efficiency and operational costs of aluminium smelting processes. Reactivity to air influences the lifespan of carbon artifacts and determines how much carbon is available for the primary reduction of alumina.

Key Topics

• Thermogravimetric Analysis (TGA): Provides guidelines for sample preparation, specification of apparatus, control of reaction temperature, and gas flow rates to determine changes in mass as carbon reacts with air.
• Reactivity Parameters: Defines and standardizes the calculation of initial, final, and total air reactivity, as well as the air dusting rate, based on precise mass loss measurements and exposed surface areas.
• Apparatus and Calibration: Specifications for furnaces, reaction chambers, sample suspension devices, gas preheating, and measurement instrumentation to ensure repeatable and accurate results.
• Test Procedure: Detailed steps for preparing and conditioning samples, conducting the thermal reaction under controlled conditions, measuring mass loss, collecting dust, and recording results.
• Precision and Reproducibility: Establishes statistical criteria for repeatability and reproducibility, increasing confidence in test results when used for material certification or research.
• Reporting Requirements: Outlines the necessary elements of an effective test report, ensuring the traceability and integrity of results.

Applications

• Raw Material Selection: Air reactivity data supports the selection of carbonaceous raw materials for anode and sidewall block production, optimizing for performance and durability in aluminium reduction cells.
• Quality Control: Provides a reliable benchmark for routine quality assurance, helping manufacturers ensure product consistency and compliance with industry requirements.
• Process Optimization: Reactivity and dusting rates are vital for both research and plant operations to evaluate and improve beneficiation processes, electrode formulations, and smelting efficiency.
• Performance Assessment: Enables producers and users of baked carbon artifacts to compare materials from different sources objectively, informing decisions on purchasing and process parameters.
• Standardized Testing: Supports globally harmonized approaches to the evaluation of carbon used in aluminium production, reducing variability between labs and facilitating international trade.

Related Standards

• ISO 12989-1: Carbonaceous materials used in aluminium production - Baked anodes and sidewall blocks - Determination of the reactivity to air - Part 1: Loss in mass method.
• ASTM D 6559: Standard that provides the basis for the thermogravimetric method outlined in ISO 12989-2.
• ASTM D 6353: Standard Guide for Sampling Plan and Core Sampling for Prebaked Anodes Used in Aluminum Production.
• ASTM D 6354: Standard Guide for Sampling Plan and Core Sampling of Carbon Cathode Blocks Used in Aluminum Production.

ISO 12989-2:2004 is indispensable for quality control laboratories, aluminium smelters, and carbon product manufacturers seeking robust, replicable, and internationally recognized test methods for the evaluation of baked anodes and sidewall blocks. Employing this standard ensures consistent product performance and enhances process optimization across the industry.