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Diss Factsheets

Physical & Chemical properties

Melting point / freezing point

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Endpoint:
melting point/freezing point
Type of information:
calculation (if not (Q)SAR)
Remarks:
Thermodynamic modelling calculations by MTDATA software package
Adequacy of study:
supporting study
Study period:
not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Remarks:
The results were based on the use of thermodynamic modelling calculations using the well accepted MTDATA software package.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Melting point calculations were performed using the MTDATA computational software package developed by the UK National Physical Laboratory, with the standard SGYE database provided with the MTDATA as part of the package and the NPL-NIRO MTOX database.
GLP compliance:
no
Type of method:
other: Thermodynamic modelling
Melting / freezing pt.:
> 1 000 °C
Atm. press.:
ca. 1 atm
Decomposition:
no
Sublimation:
no
Conclusions:
Calculations were performed by a thermodynamic modelling using the MTOX thermodynamic database by the UK National Physical Laboratory for use with its MTDATA software for two different iron sinter compositions under an atmosphere oxygen in an inert container. It is estimated that the melting point of the substance is >1000 °C.
Endpoint:
melting point/freezing point
Type of information:
calculation (if not (Q)SAR)
Remarks:
Thermodynamic modelling calculations by FACTSAGE software package
Adequacy of study:
key study
Study period:
not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
accepted calculation method
Remarks:
The results were based on thermodynamic modelling calculations using the well accepted FACTSAGE software package.
Qualifier:
no guideline followed
Principles of method if other than guideline:
Melting point calculations were performed for five different sinter compositions using the FACTSAGE computational software package.
GLP compliance:
no
Type of method:
other: Thermodynamic modelling study
Melting / freezing pt.:
> 1 200 °C
Atm. press.:
ca. 1 atm
Decomposition:
no
Sublimation:
no

Melting point calculations were performed for five different sinter compositions using the FACTSAGE computational software package.

Conclusions:
The melting temperature of five different sinter compositions was estimated by thermodynamic modelling using the FACTSAGE thermodynamic software package. It is estimated that the melting point of the substance is >1200 °C.
Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
key study
Study period:
not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
The study was performed under the auspices of the ECSC (European Coal and Steel) research programme and the research results were monitored and reviewed by the iron making expert group, consisting of European experts in the field of ironmaking, agglomeration and cokemaking.
Qualifier:
no guideline followed
Principles of method if other than guideline:
The softening and melting properties were studied of iron sinter and pellets using a laboratory-scale test facility that simulates the blast furnace process to a temperature of 1530 °C.
GLP compliance:
no
Type of method:
other: simulated blast furnance process
Melting / freezing pt.:
> 1 100 °C
Atm. press.:
>= 1 atm
Decomposition:
no
Sublimation:
no

Tests performed under reducing atmosphere to simulate blast furnace process so reduction of iron oxides to iron occurred during the test.

Conclusions:
The softening and melting properties were studied of iron sinter and pellets using a laboratory-scale test facility that simulates the blast furnace process to a temperature of 1530 °C. The studies showed that the incipient melting of iron sinter occured at >1000 °C.
Endpoint:
melting point/freezing point
Type of information:
other: handbook data
Adequacy of study:
key study
Study period:
not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Qualifier:
no guideline followed
Principles of method if other than guideline:
not applicable - handbook data
GLP compliance:
not specified
Type of method:
other: not specified
Key result
Melting / freezing pt.:
> 1 000 °C
Atm. press.:
1 atm
Decomposition:
no
Sublimation:
no
Remarks on result:
other: iron sinter
Melting / freezing pt.:
1 565 °C
Atm. press.:
1 atm
Decomposition:
no
Sublimation:
no
Remarks on result:
other: diiron trioxide
Conclusions:
Based on the reference melting point for di-iron trioxide of 1565 °C, it is concluded that the melting point of iron sinter is >1000 °C.

Description of key information

The melting behaviour of iron sinter was inferred from reference data for pure diiron trioxide, thermodynamic modelling studies on iron sinter and iron oxides, and laboratory-scale experiments performed under the auspices of the ECSC research programme. These studies all indicate that incipient melting of iron sinter begins at >1000 °C with complete melting taking place at temperatures >1300 °C.

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:
1 000 °C

Additional information

Iron sinter is a heterogeneous material and experimental determination of its melting behaviour is extremely difficult, even if near-homogeneity of a sample can be obtained by grinding the material to a fine particle size. Owing to the different phases present e.g., iron oxides, silicates, silicoferrites, aluminosilicates etc., melting takes place over a significant temperature range and the degree to which melting has occurred is very difficult to determine with any degree of accuracy. This is one of the motivating factors leading to the development of the thermodynamic modelling approaches by the UK National Physical Laboratory in its MTDATA software, and by the Ecole Polytechnique and McGill University in the FACT software. The methods for melting point determination listed in the ECHA guidance are not applicable for substances with melting points > 1000 °C and therefore direct measurements of the melting point or, to be more correct, the melting point range are not available from reference sources. The only relevant studies are those carried out by Clixby (1987) under the auspices of the ECSC research programme. In this work a robust laboratory scale apparatus was developed to study the softening and melting properties of iron sinter and iron ores, agglomerates under reducing atmospheres that simulated the blast furnace process. These studies confirm the results of the mathematical modelling studies and indicate that melting of iron sinter begins to occur at temperatures >1000 °C and only becomes fully liquid at temperatures >1300 °C.