ISO/TC 226 - Materials for the production of primary aluminium

This document specifies a wavelength-dispersive X-ray fluorescence spectrometric (XRF) method for the determination of cryolite (Na3AlF6) from the content of fluorine to the content of trace elements. The calibration reference materials are not specified in this method. The method is applicable to cryolite, which is primarily used for the production of aluminium. Annex A provides conversion factors for converting elements to compounds. The validity and precision of test results for concentrations outside these ranges has not been determined. The concentration range of fluorine (given as F) is from 510 g/kg to 560 g/kg. The concentration range of aluminium (given as Al) is from 120 g/kg to 150 g/kg. The concentration range of sodium (given as Na) is from 270 g/kg to 330 g/kg. The concentration range of silicon (given as SiO2) is from the lowest limit of detection (LLD) to 4,0 g/kg. The concentration range of iron (given as Fe2O3) is from LLD to 0,37 g/kg. The concentration range of sulfur (given as SO4) is from LLD to 5,0 g/kg. The concentration range of phosphorus (given as P2O5) is from LLD to 0,40 g/kg. The concentration range of calcium (given as CaO) is from LLD to 0,80 g/kg.

This document specifies a method for the determination of the resistance to physical abrasion of a cathode sample.

This document specifies a method to determine the coefficient of linear thermal expansion of carbonaceous or graphite materials (solid materials) for the production of aluminium between 20 °C and 300 °C. It applies to baked anodes and shaped carbon products.

This document specifies a method that covers the determination of linear expansion under external pressure due to sodium penetration in cathode-block materials used in the production of aluminium. The linear expansion of the blocks depends on the sampling direction due to anisotropy.

This document specifies the determination of expansion/shrinkage during baking of cold and tepid ramming pastes used in the production of aluminium.

This document specifies the ring-and-ball method, a method of using the ring-and-ball apparatus for the determination of the softening point (softening temperature) of pitch used in the production of aluminium. The method is applicable to pitches having softening points equal to or greater than 30 °C.

This document specifies a method for the determination of the electrical resistivity of granular carbon (calcined or graphitized) used in the manufacture of carbon electrodes for the production of aluminium. The measurement of electrical resistivity assists in assessing the extent of coke calcination. The electrical resistivity of the coke aggregate will influence the electrical resistivity of the coke electrodes made from it. In general, a more highly calcined coke will have a lower electrical resistivity if other factors, such as grain size, are similar.

This document describes methods for the sample preparation of smelter-grade aluminium oxide. It covers the reduction of a bulk sample between 1 kg and 20 kg to produce a sample that is suitable for chemical and physical analysis. The reduced sample produced will be representative of the initial bulk sample. The bulk sample is considered to be from one source. The methods are suitable for dry, free-flowing aluminium oxide. As the moisture content will influence many physical analyses, the method aims to minimize the exposure of the sample to the atmosphere to avoid water absorption.

This document specifies a hydrostatic method for the determination of the apparent density and the open (to water) porosity of carbonaceous products used in the production of aluminium. This hydrostatic method was developed principally to determine the open porosity but can also be used to measure the apparent density. This document is especially applicable to samples of complex on irregular geometry (due to drilling difficulties).

This document specifies a dimensions method for the determination of the apparent density of carbonaceous products used in the production of aluminium. This method is applicable to samples with a simple or well-defined geometry (for example cylindrical, rectangular parallelepipedical or cubic) and a smooth surface profile. The accuracy of measurement is strongly influenced by the equipment used for sampling, i.e. the drilling and sawing machines.

ISO 12984:2018 specifies a method for the determination of the particle size distribution of a sample of coke having a typical size distribution as normally produced by calcination of delayed petroleum coke. The same procedure is applicable to consignments of calcined anthracite. This document does not apply to fractions of carbon material prepared by sieving and crushing or to filter fines. This method is applicable to the determination of particle sizes ranging from 0,25 mm to 16 mm, as the sum of the percentages of the size distribution above and below this range is typically less than 10 %. This document does not apply to determining particle sizes below 0,25 mm where a specific test for dust is used.

ISO 19950:2015 sets out an X-ray diffraction method for the determination of the alpha alumina content of smelter grade alumina. The method is applicable to smelter grade alumina containing alpha phase at levels up to 50 %. The percentage by mass of alpha alumina is determined on an "as received" basis.

ISO 23201:2015 sets out a wavelength dispersive X-ray fluorescence spectrometric method for the analysis of aluminium oxide for trace amounts of any or all of the following elements: sodium, silicon, iron, calcium, titanium, phosphorus, vanadium, zinc, manganese, gallium, potassium, copper, chromium and nickel. These elements are expressed as the oxides Na2O, SiO2, Fe2O3, CaO, TiO2, P2O5, V2O5, ZnO, MnO, Ga2O3, K2O, CuO, Cr2O3, and NiO on an un-dried sample basis. The method is applicable to smelting-grade aluminium oxide. The concentration range covered for each of the components is also given.

ISO 18842:2015 describes methods for the determination of tapped and untapped bulk density of smelter grade aluminium oxide primarily used for the production of aluminium. Methods using the fall of sample into a receptacle have been found to be sensitive to flow rate variations, which are caused by physical properties of the aluminium oxide. ISO 18842:2015 minimizes flow rate variations.

ISO 18843:2015 sets out a method for determining the amount of time taken for a given quantity of smelter-grade alumina to flow by gravity through a precisely constructed standard funnel. NOTE Variations in the apparatus and other test variables can create significant inter-laboratory differences in results. (See Table A.1.)

ISO 15379-2:2015 specifies a method that covers the determination of linear expansion under external pressure due to sodium penetration in cathode-block materials used in the production of aluminium. The linear expansion of the blocks depends on the sampling direction due to anisotropy.

ISO 12986-1:2014 specifies a three-point method to determine the flexural strength of carbon and solid graphite materials at room temperature.

ISO 18515:2014 specifies a method to determine the compressive strength of solid carbon and graphite materials at room temperature.

ISO 12986-2:2014 specifies a four-point method to determine the flexural strength of carbon and solid graphite materials at room temperature.

ISO 18142:2014 specifies a method to determine the dynamic modulus of elasticity of specimens made of solid carbonaceous or graphite materials at room temperature by the resonance method.

ISO 2926:2013 specifies a dry sieve method using electroformed sieves for determining the mass distribution of the particle sizes in aluminium oxide used for the production of primary aluminium. This method is applicable to calcined aluminium oxide containing a maximum of 20 % mass fraction of particles having a mean diameter exceeding 150 µm, and containing a maximum of 15 % mass fraction of particles having a mean diameter less than 45 µm. This method is not applicable to the use of woven wire sieves.

ISO 12926: 2012 describes an X-ray fluorescence spectrometric (XRF) method for the determination of aluminium fluoride (AlF3) from the content of fluorine and the content of trace elements in the test specimen. The method does not determine the oxygen content. The calibration reference materials are not specified in this method.

ISO 11706:2012 describes a method for the determination of the fracture energy at room temperature. This property is relevant for the thermal shock resistance of prebaked anodes used in the electrolytic cell.

ISO 12315:2010 describes methods for calculating and reporting the Al2O3 content of smelter-grade alumina, on either a dry or ignited basis, from the results of the determinations in accordance with ISO 806 and AS 2879.7.

ISO/TR 4277:2009 describes a conventional test for the evaluation of the free fluorides content of natural, artificial and recovered cryolite. This method is applicable to products having free fluorides content greater than 0,15 % (mass fraction) of AIF3 or 0,4 % (mass fraction) of NaF.

ISO 20292:2009 covers materials for the production of primary aluminium. ISO 20292:2009 specifies a method for the determination of the resistance of dense refractory bricks to cryolite melt with excess sodium fluoride.

ISO 15906:2007 describes a method for the measurement of the air permeability of baked anodes, by determining the resistance to airflow of a specimen of specified volume at room temperature, within the range of air permeability between 0,01 nPm (nanoperms) and 10 nPm. "Green" anodes are considered to be impermeable to gas. Therefore, this test is most applicable to "baked" carbon material.

ISO 5940-2:2007 specifies a method to determine the softening point of pitches by the Mettler method, within the range of 50 °C to 180 °C. It can be used for other organic materials that are used as binder and impregnating agents, where they have a Mettler softening point within the range of 50 °C to 150 °C.

ISO 21687:2007 specifies a method for the determination of the density of green and calcined petroleum coke and similar solid materials (e.g. electrodes). ISO 21687:2007 is also suitable for hydrocarbons with a high-temperature boiling range and for other solid materials. This method is not suitable for graphitized material.

ISO 23202:2006 sets out a wet-sieving procedure for the determination of the percentage by mass of particles of smelter-grade alumina passing a 20 micrometre aperture sieve. This procedure is applicable for aluminas with a minus 20 micrometre content up to 4 %.

ISO 17500:2006 specifies a procedure for the determination of the attrition index of smelter-grade alumina.

ISO 17499:2006 covers carbonaceous materials used in the production of aluminium. ISO 17499:2006 specifies the determination of the equivalent temperature of one anode or cathode in a baking furnace, and the calculation of the overall baking level in a section in the baking furnace.

ISO 8008:2005 specifies an instrumental method for the determination of specific surface area of smelter-grade alumina by nitrogen adsorption by a single- or multi-point method. A multi-point method is recommended due to the higher accuracy obtained; if a single-point method is used, a lower result will be obtained. ISO 8008:2005 is applicable to aluminas having a surface area between 50 m2/g and 90 m2/g.

ISO 20203:2005 describes a test method for the determination of the mean crystallite height of a representative, pulverized sample of calcined petroleum coke by interpretation of an X-ray diffraction pattern produced through conventional X-ray scanning techniques. ISO 20203:2005 applies to carbonaceous materials used in the production of aluminium.

ISO 8005:2005 specifies a method for the determination of ash in green and calcined coke used in the production of aluminium.

ISO 14435:2005 applies to carbonaceous materials for the production of aluminium. ISO 14435:2005 describes a test method which covers the analysis for commonly determined trace metals in test specimens of raw and calcined petroleum coke by inductively coupled plasma atomic emission spectroscopy. It can also be applied to other heat-treated carbonaceous materials e.g. coal-tar pitch coke, anthracite.

ISO 806:2004 specifies a method for the determination of loss of mass on heating of aluminium oxide at 300 °C and further loss of mass on ignition at 1 000 °C. By industry convention, these mass losses are often referred to as "moisture (MOI)" and "loss on ignition (LOI)" respectively. This method is suitable for calcined alumina in the range 0,2 % to 5 % loss of mass at 300 °C and 0,1 % to 2 % loss of mass at 1 000 °C. This method provides for samples to be treated on an "as-received" basis for determination of actual MOI and LOI in alumina samples. To improve precision of analysis in cases where "as-received" results are not required, samples can be "air-equilibrated" prior to analysis. "Air-equilibration" can greatly affect MOI results and significantly alter LOI results. The "air-equilibration" procedure and its effects are discussed. Instrumental methods are also discussed.

ISO 12988-2:2004 describes a test method for the thermogravimetric (TGA) determination of CO2 reactivities and dusting of shaped carbon anodes used in the aluminium reduction industry. Many types of apparatus are available with a wide variety of thermal conditions, sample-size capability, materials of construction and procedures for determining the mass loss and subsequent rate of reaction. This test method standardizes the variables of sample dimensions, reaction temperature, gas velocity over the exposed surfaces, and reaction time such that results obtained on different types of apparatus are correlatable.

ISO 17544:2004 describes a method of producing a compaction curve indicating the rammability of carbonaceous ramming pastes used to line cathodes utilized in the production of aluminium.

ISO 14427:2004 describes the preparation of unbaked test specimens made by compacting carbonaceous ramming pastes. It also includes a method for the determination of the apparent density after compaction.

ISO 20202:2004 describes a method of baking green test specimens made by compacting carbonaceous ramming pastes. It includes the baking procedure (heating rate and holding time) and the determination of the loss on baking (relative mass loss).

ISO 12987:2004 specifies a method for the determination of thermal conductivity of carbonaceous material in the temperature range of 20 °C to 60 °C. The typical range of thermal conductivity for these materials is 2 W/(K·m) to 100 W/(K·m). This method can be used for other carbon materials, such as graphitized electrodes for other applications.

ISO 12989-2:2004 covers the thermogravimetric analysis (TGA) of air reactivities and dusting of shaped carbon electrodes used in the aluminium-production industry. Many types of apparatus are available, with various thermal conditions, sample-size capability, materials of construction and procedures for determining the mass loss and subsequent rate of reaction. This test method sets standard reaction times and temperatures, and provides a mathematical method to normalize the gas velocity over the exposed surfaces, such that results obtained on different types of apparatus are correlatable.

ISO 8007-3:2003 describes procedures for sampling consignments of blocks and taking test samples from single sidewall blocks used in the production of aluminium.

ISO 6257:2002 specifies methods for sampling and preparing samples prior to testing of binder pitch used in the manufacture of electrodes for the electrolytic production of aluminium. These methods are applicable to grades of pitch in liquid or solid form, the latter having softening points higher than 30 °C (determined according to the method specified in ISO 5940), in bulk, or in a number of containers making up one batch at sites of manufacture, storage, or delivery. Sampling methods and sampling plans for large consignments, or lots, of pitch in liquid form during the loading and unloading of ships are included.

This part of ISO 12982 describes an ignition temperature method for the determination of the reactivity to air of calcined petroleum coke used in the manufacture of anodes for the production of aluminium. A heating rate of is used for petroleum coke specifications, whereas is used for statistical process control of calcination kilns and for anode butt quality control. NOTE ISO 12982-2 (in preparation) will give a thermobalance method for the determination of the reactivity to air of calcined coke.

This International Standard specifies a reference method for determining the total sulfur content of calcined coke and calcined carbon products by the Eschka method, provided that they contain a minimum of by mass and preferably less than by mass of sulfur.

This International Standard specifies a method for the determination of the electrical resistivity of cathode blocks and baked anodes used in the production of aluminium, using samples at ambient temperature.

This part of ISO 12989 specifies a loss-in-mass method for the determination of the reactivity of carbonaceous products to air. The method was developed especially for anodes used in the production of aluminium.