GB/T 44032-2024Identification method for iron ore and materials containing iron (English PDF)

3 Terms and definitions

The terms defined in GB/T 20565 apply together with three terms given here. Iron-bearing dusts and sludges (3.1) are the solid waste obtained after dry dust removal, wet dust removal and waste water treatment in the raw material preparation, sintering, pelletizing, ironmaking, steelmaking and rolling processes of an iron and steel works, excluding metallurgical auxiliary dusts and sludges, fuel dusts and sludges and dusts and sludges from the processing of special ores; a note divides them by origin into raw material preparation, sintering, pelletizing, blast furnace, steelmaking and rolling dusts and sludges. The definition is taken with modification from GB/T 28292-2012, 3.2.

Mill scale (3.2) is the iron swarf produced when the surface oxide layer comes off a steel ingot or billet during forging or rolling; it is in strip form and is also called iron scale, and the definition is taken from SN/T 3102-2012, 3.2. Iron-bearing smelting slag (3.3) is the iron dominated by-product of the smelting of iron ore; a note lists blast furnace pig iron slag, foundry pig iron slag, ferromanganese ore slag and similar furnace slags, the acid liquid slag of steelmaking, the oxidizing slag of top blown, bottom blown and combined blown converters and of electric furnaces and the electric furnace reducing slag, and the pyrite cinder produced when pyrite, sulfur concentrate or ferrous sulfate is roasted in a fluidized bed furnace for desulfurization.

4 Principle

A sensory examination of the goods is carried out and a sampling and sample preparation plan is drawn up. The composition, the phases, the particle size, the acidity and alkalinity of the leachate and the content of the leached ions, the ore phases and the microscopic morphology of the sample are analysed and tested, and the results, together with the information on the origin and use of the goods supplied by the client, are compared with the main physical and chemical characteristics of typical iron ore and iron-bearing materials in order to identify the source attribute of the sample. The identification flow is shown in Figure 1.

Four footnotes accompany Figure 1. Where the goods contain parts of different character, for example different colours or blocks partly full of gas holes, these are sorted out, their masses recorded and each identified separately. Semi-quantitative analysis is carried out on the major and minor components of the sample, and other quantitative analysis, such as metallic iron or carbon content, is carried out as needed. On the basis of the sensory examination and of the composition and phase results, further techniques may be chosen where necessary, such as particle size, leachate acidity and alkalinity, leached ion content, ore phase analysis and microscopic morphology analysis. The documentary sources include the main physical and chemical characteristics of iron ore and of iron-bearing materials from different production processes, and the production process and use of the goods supplied by the client; comparing the documentary sources with the test information allows the source attribute of the goods to be inferred.

5 Instruments and equipment

The instruments and equipment listed are a wavelength dispersive X-ray fluorescence spectrometer, an X-ray diffractometer, a laser particle size analyser, a forced air drying oven, a pH meter, an inductively coupled plasma atomic emission spectrometer, an inductively coupled plasma mass spectrometer, an ore microscope and a scanning electron microscope with energy dispersive spectrometer.

6 Sensory examination

The shape, colour and lustre, surface morphology, smell and other apparent characteristics of the goods are examined by the senses in order to confirm that the appearance of the goods is consistent and uniform. Where parts of the same consignment differ clearly in their apparent characteristics, those parts are sampled and prepared separately. The result of the sensory examination is recorded in writing, in photographs or on video.

Clause 7 requires sampling according to SN/T 5571 and sample preparation according to HJ/T 20; sampling and preparation may also follow the corresponding sampling and preparation standards for the iron ore or iron-bearing material concerned.

8 Analysis and testing

8.1 The document gives the recommended standard methods for the analysis and testing, and a laboratory may also choose other standard methods that reach the same testing objective. 8.2 The major and minor components of the sample are analysed according to GB/T 16597, and where necessary particular constituents may be determined quantitatively according to the relevant iron ore standards. 8.3 The phase composition of the sample is analysed according to SN/T 3011.1.

8.4 Particle size analysis follows GB/T 10322.7 or GB/T 19077. GB/T 10322.7 applies to particle size analysis with sieves of aperture 36 micrometres or larger, and GB/T 19077 applies to particle size analysis of samples between 0.1 micrometres and 3 mm with a laser particle size analyser. 8.5 The acidity and alkalinity of the leachate are analysed with a pH meter according to GB/T 15555.12, and the ions in the leachate are determined with an inductively coupled plasma emission spectrometer or an inductively coupled plasma mass spectrometer according to JY/T 0567 or JY/T 0568. 8.6 The ore phase characteristics are identified with an ore microscope according to DZ/T 0275.4 and DZ/T 0275.5, and the microscopic morphology and composition are analysed with a scanning electron microscope and energy dispersive spectrometer according to JY/T 0582, JY/T 0584 and GB/T 17359.

9 Judgement of the attribute

9.1 Iron ore is inferred where the main components are iron, silicon and aluminium with small amounts of calcium, magnesium, manganese, potassium, sodium, phosphorus and sulfur; where the main phases are one or more of magnetite, hematite, goethite, lepidocrocite, limonite, maghemite, martite and siderite together with gangue such as quartz and silicate rock; where the leachate pH is neutral or alkaline and the main leached ions are iron, silicon, aluminium, calcium, magnesium and sodium at a mass concentration generally below 10 micrograms per millilitre; and where the microscopic morphology shows compact particles with the angular edges typical of minerals. Annex A gives the characteristic information of typical iron ore.

9.2 Direct reduced iron is inferred where the main component is iron, present mainly as metallic iron, with small amounts of silicon, aluminium, calcium, magnesium, carbon, phosphorus, sulfur, titanium, chromium and vanadium, and where the main phase is metallic iron, possibly together with ferrous oxide, triiron tetroxide, diiron trioxide, gangue and quartz; the sample can then be inferred to be a completely or incompletely reduced direct reduced iron product of the solid state reduction of iron ore. Annex B gives the characteristic information.

9.3 Iron-bearing dusts and sludges are inferred where the particle size is fine, generally of the order of tens of micrometres; where the main components are iron, calcium, magnesium, silicon, aluminium, phosphorus, titanium, manganese, zinc, carbon, sulfur, sodium and potassium, possibly with a high content of zinc, carbon or fluorine; where the main phases are magnetite, hematite, goethite, ferrous oxide, iron, graphite, periclase, calcium hydroxide and the metal oxides formed at high temperature between iron and other metals, such as magnesioferrite, zinc ferrite spinel and manganosite; where the leachate pH is neutral to alkaline with a high concentration of calcium and sodium ions, from tens to several hundred micrograms per millilitre; and where the particles are loose under the microscope and show no angular mineral edges. Annex C gives the characteristic information.

9.4 Mill scale is inferred where the sample is in strip or flake form, smooth and metallic on one face and rough on the other, where the total iron content generally reaches more than 68 % and silicon, aluminium, calcium and magnesium are also present, and where the main phases are ferrous oxide, iron oxide and triiron tetroxide. Annex D gives the characteristic information.

9.5 Iron-bearing smelting slag is inferred where the surface shows a glassy state or fused pores, the main components are iron, silicon, aluminium, calcium and magnesium with small amounts of manganese, sulfur, potassium, sodium, phosphorus, chromium and fluorine, the phases are complex and often include glassy matter with the metallic elements present mainly as silicates, aluminates and ferrites, the leachate pH is alkaline to weakly alkaline and the calcium ion content is high, from tens to several hundred micrograms per millilitre; the sample may then be inferred to be smelting slag from ironmaking or steelmaking. The same subclause continues, in the same paragraph and with no separate heading, that where the main components are iron, silicon, aluminium, calcium, magnesium and sulfur, the main phases are hematite, magnetite, limonite, pyrrhotite and calcium sulfate, and the leachate is clearly acidic, the sample may be inferred to be pyrite cinder from the roasting of pyrite. Annex E gives the characteristic information.

9.6 Where the composition of the sample is complex and it fits part of the characteristics of more than one of the materials of 9.1 to 9.5, it may be inferred to be a mixture of several iron-bearing materials. A note warns that, because iron ore and iron-bearing materials come from many sources and are of many kinds, the criteria given in the document do not rule out exceptions.

10 Identification report

The identification report shall contain the unique identification of the sample, the result of the sensory examination recorded in writing, in photographs or on video, the sampling and sample preparation record and the basis for it, the results of each physical and chemical characteristic analysis and the basis for them, the identification conclusion, and any other factor that bears on the judgement of the source attribute.

A-E Annexes A to E (informative) Characteristic information of the typical materials

Annex A describes the apparent physical characteristics of iron ore: magnetite is black grey with a black streak, has a metallic or semi-metallic lustre, a fine dense structure and strong magnetism; hematite is dark red, the colour deepening with the iron content until it is almost black, with a red streak; limonite is yellow brown, brown or black brown with a yellow brown streak. The gangue of natural iron ore is mostly clay matter or quartzite, fine ore looks like earth and feels sticky, and lump ore often has small particles stuck to its surface. Iron ore is divided into natural and processed ore and includes lump ore, fine ore, concentrate, pellets and sinter; Table A.1 has two columns and five rows and pairs each of those five names with its typical particle size range.

Table A.2 gives the main components and mass fraction ranges of typical iron ore samples over two printed blocks, with the four ore types as row groups and a maximum and a minimum line for each; a note explains that a dash means not detected. The row groups and the element column headings did not stay aligned in the extraction, so the figures are not reproduced here. A.3 lists the common phases of iron ore, one or more of magnetite, hematite, goethite, lepidocrocite, limonite, maghemite, martite and siderite together with gangue such as quartz and silicate rock, sinter usually carrying calcite, almandine and fayalite in addition. A.4 states that under the scanning electron microscope with mineral analysis software the iron ore particles show the angular edges typical of minerals and a compact structure, the main mineral being iron ore with a small amount of other minerals.

Annex B covers direct reduced iron: it is generally in powder, ball, tile or rod form and may be further briquetted hot or cold; its main component is iron, present mainly as metallic iron, the total iron content of the product generally being above 90 % and the metallization degree generally above 90 %, with small amounts of silicon, aluminium, calcium, magnesium, carbon, phosphorus, sulfur, titanium, chromium and vanadium; the main phase is metallic iron, with ferrous oxide, triiron tetroxide and diiron trioxide possibly present where reduction was incomplete, together with gangue and quartz.

Annex C covers iron-bearing dusts and sludges: their colour ranges from light grey to dark brown according to composition, they are generally powdery and may form lumps that crumble under light pressure, and the powder is fine, the twenty-fifth percentile of the particle diameter being about 10 micrometres or less and the ninetieth percentile from tens to a little over two hundred micrometres. Table C.1 gives the composition and mass fraction ranges of thirteen types of dust and sludge over two printed blocks, with a maximum and a minimum line for each type and a note explaining that a dash means not detected and a slash means not tested; the rows and the element column headings did not stay aligned in the extraction, so the figures are not reproduced here. In the first block the two lines of the converter OG sludge row are both labelled maximum value, where the second should be the minimum, and that is how the original is printed. C.3 and C.4 add that the phases are complex, with iron, graphite, periclase, calcium hydroxide, calcium aluminium silicates and high temperature metal oxides such as magnesioferrite, zinc ferrite spinel and manganosite alongside the magnetite, hematite, goethite and quartz common in iron ore, and that under the microscope the particles are fine and mostly loose, with no angular mineral edges.

Annex D covers mill scale: it is in strip or flake form, smooth and metallic on one face and rough on the other; Table D.1 gives its composition and mass fraction ranges in two blocks of maximum and minimum lines, which did not stay aligned in the extraction and are therefore not reproduced here; the main phases are ferrous oxide, triiron tetroxide and diiron trioxide, the ferrous oxide content usually being very high, and a good deal of elemental iron is present in many mill scales. Annex E covers iron-bearing smelting slag: its colour ranges from light grey to dark brown according to composition, the sample is in lumps or a mixture of lumps and powder, and the lumps often show a glassy state and fused pores. Table E.1 gives the composition and mass fraction ranges of six types of slag with maximum and minimum lines, and did not stay aligned either. E.3 states that the phases are complex, that magnetite, hematite and goethite are not marked in the slags from ironmaking and steelmaking, whose main phases are wuestite, dicalcium silicate, tricalcium silicate, periclase, feldspar as calcium sodium aluminium silicate, fayalite, spinel olivine and iron spinel, and that the main phases of pyrite cinder are hematite, magnetite, limonite, pyrrhotite, sulfates such as calcium sulfate, chalcopyrite, cuprite, quartz, feldspar and silicates.