ISO 7992:2007
(Main)Iron ores for blast furnace feedstocks — Determination of reduction under load
Iron ores for blast furnace feedstocks — Determination of reduction under load
ISO 7992:2007 specifies a method to provide a relative measure for evaluating the structural stability of iron ores, when reduced under conditions resembling those prevailing in the reduction zone of a blast furnace. ISO 7992:2007 is applicable to lump ores and hot-bonded pellets.
Minerais de fer pour charges de hauts fourneaux — Détermination de la réduction sous charge
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Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 7992
Second edition
2007-10-15
Iron ores for blast furnace feedstocks —
Determination of reduction under load
Minerais de fer pour charges de hauts fourneaux — Détermination de la
réduction sous charge
Reference number
ISO 7992:2007(E)
©
ISO 2007
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ISO 7992:2007(E)
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ISO 7992:2007(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Principle. 1
5 Sampling, sample preparation and preparation of test portions. 2
6 Apparatus . 2
7 Test conditions . 3
8 Procedure . 4
9 Expression of results . 5
10 Test report . 6
11 Verification . 7
Annex A (normative) Flowsheet of the procedure for the acceptance of test results . 11
Annex B (informative) Derivation of equation for reducibility. 12
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ISO 7992:2007(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7992 was prepared by Technical Committee ISO/TC 102, Iron ore and direct reduced iron, Subcommittee
SC 3, Physical testing.
This second edition cancels and replaces the first edition (ISO 7992:1992), which has been revised to
homogenise with other physical test standards.
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ISO 7992:2007(E)
Introduction
This International Standard concerns one of a number of physical test methods that have been developed to
measure various physical parameters and to evaluate the behaviour of iron ores, including reducibility,
disintegration, crushing strength, apparent density, etc. This method was developed to provide a uniform
procedure, validated by collaborative testing, to facilitate comparisons of tests made in different laboratories.
The results of this test should be considered in conjunction with other tests used to evaluate the quality of iron
ores as feedstocks for blast furnace processes.
This International Standard may be used to provide test results as part of a production quality control system,
as a basis of a contract, or as part of a research project.
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INTERNATIONAL STANDARD ISO 7992:2007(E)
Iron ores for blast furnace feedstocks — Determination of
reduction under load
CAUTION This International Standard may involve hazardous materials, operations and equipment.
This standard does not purport to address all of the safety issues associated with its use. It is the
responsibility of the user of this International Standard to establish appropriate safety and health
practices and determine the applicability of regulatory limitations prior to its use.
1 Scope
This International Standard specifies a method to provide a relative measure for evaluating the structural
stability of iron ores, when reduced under conditions resembling those prevailing in the reduction zone of a
blast furnace.
This International Standard is applicable to lump ores and hot-bonded pellets.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 2597-1:2006, Iron ores — Determination of total iron content — Part 1: Titrimetric method after tin (II)
chloride reduction.
1)
ISO 3082:2000 , Iron ores — Sampling and sample preparation procedures
ISO 9035:1989, Iron ores — Determination of acid-soluble iron(II) content — Titrimetric method
ISO 9507:1990, Iron ores — Determination of total iron content — Titanium (III) chloride reduction methods
ISO 11323:2002, Iron ore and direct reduced iron — Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11323 apply.
4 Principle
o
The test portion is isothermally reduced in a fixed bed, at 1 050 C, under static load, using a reducing gas
consisting of CO, H and N , until a degree of reduction of 80 % is obtained. The differential gas pressure
2 2
across the bed and the change in the test bed height are measured at 80 % reduction.
1) Under revision to incorporate ISO 10836 – Iron ores – Method of sampling and sample preparation for physical testing.
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ISO 7992:2007(E)
5 Sampling, sample preparation and preparation of test portions
5.1 Sampling and sample preparation
Sampling of a lot and preparation of a test sample shall be in accordance with ISO 3082.
The size range for pellets and lump ores shall be − 12,5 mm + 10,0 mm.
A test sample of at least 6,0 kg, on a dry basis, of the sized material shall be obtained.
Oven-dry the test sample to constant mass at 105 °C ± 5 °C and cool it to room temperature before
preparation of the test portions.
NOTE Constant mass is achieved when the difference in mass between two subsequent measurements becomes
less than 0,05 % of the initial mass of the test sample.
5.2 Preparation of test portions
Collect each test portion by taking ore particles at random.
NOTE Manual methods of division recommended in ISO 3082, such as riffling, can be applied to obtain the test
portions.
At least 5 test portions, each of approximately 1 200 g (± the mass of 1 particle) shall be prepared from the
test sample: 4 test portions for testing, 1 for chemical analysis.
Weigh the test portions to the nearest 1 g and register the mass of each test portion on its recipient label.
6 Apparatus
6.1 General
The test apparatus shall comprise:
a) ordinary laboratory equipment, such as an oven, hand tools, a time-control device and safety equipment;
b) a reduction-tube assembly, including a loading device, manometer and height-measuring device;
c) a furnace, equipped with a balance for permitting the mass loss of the test portion to be read at any time
during the test;
d) a system to supply the gases and regulate the flow rates;
e) a weighing device.
Figure 1 shows an example of the test apparatus.
6.2 Reduction tube, with a double wall made of non-scaling, heat-resistant metal to withstand
temperatures higher than 1 050 °C and resistant to deformation. The internal diameter of the inner reduction
tube shall be 125 mm ± 1 mm. A removable perforated plate, made of non-scaling, heat-resistant metal to
withstand temperatures higher than 1 050 °C, shall be mounted in the reduction tube to support the test
portion and to ensure uniform gas flow through it. The perforated plate shall be 10 mm thick, with a diameter
1 mm less than the tube internal diameter. The holes in the plate shall be 3 mm to 4 mm in diameter, at a pitch
center distance of 5 mm to 6 mm. The internal diameter of the outer reduction tube shall be enough to allow
gas flow preheating before entering the inner reduction tube.
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ISO 7992:2007(E)
Figure 2 shows an example of a reduction tube. Figure 3 shows the principle for oxygen flushing of
thermocouples to avoid mismeasurement due to carbon deposition.
6.3 Loading device, capable of supplying a total static load of 50 kPa ± 2 kPa evenly to the test portion.
The load shall be transferred by means of a ram with a rigid perforated footplate, so as to distribute it evenly to
the surface of the porcelain balls placed on top of the test portion. The foot-plate shall be 10 mm thick, with a
diameter 1 mm less than the tube internal diameter. The holes in the plate shall be 3 mm to 4 mm in diameter,
at a pitch center distance of 5 mm to 6 mm.
6.4 Device for measuring differential gas pressure, having a resolution of 0,01 kPa.
6.5 Height-measuring device, having a resolution of 0,1 mm.
6.6 Porcelain balls, having a size range between 10,0 mm and 12,5 mm.
6.7 Furnace, having a heating capacity and temperature control able to maintain the entire test portion, as
well as the gas entering the bed at 1 050 °C ± 10 °C.
6.8 Balance, capable of weighing the reduction-tube assembly, including the test portion, to an accuracy of
1
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