1. An Introduction to MTDATA
MTDATA Users’ Group 2001
MTDATA
DATA ISSUES
John Gisby, Hugh Davies
NPL Materials Centre,
National Physical Laboratory
March 2002
John Gisby

2. DATA ISSUES MODELS KCl-CaCl2 as an example DATA ASSESSMENT
NiO-Al2O3 as an example
DATA FOR OXIDE SYSTEMS
MIRO project RC132

3. MODELS Gibbs energy of each phase is expressed as a function of
temperature, composition and possibly pressure
KCl-CaCl2 as an example

4. Stoichiometric substance or solution phase “end member”
GCaKCl3 = A + BT + CTlnT + DT2 + ET3 + F/T
Solution phase (Redlich-Kister model for Gex)
GLIQUID = xKCl GKCl + xCaCl2 GCaCl2
+ RT xKClln xKCl + RT xCaCl2ln xCaCl2
+ Gex
Gex = (L00+L01T) xKClxCaCl2
+ (L10+L11T) xKClxCaCl2 (xKCl-xCaCl2)
+ (L20+L21T) xKClxCaCl2 (xKCl-xCaCl2)2
+ …

5. GCaKCl3 = A + BT + CTlnT + DT2 + ET3 + F/T

6. Gex = (L00+L01T) xKClxCaCl2 + (L10+L11T) xKClxCaCl2 (xKCl-xCaCl2)

7. Gex = (L00+L01T) xKClxCaCl2 + (L10+L11T) xKClxCaCl2 (xKCl-xCaCl2)

8. NOT “JUST CURVE FITTING”
Underlying thermodynamic properties must be taken into account
as well as phase boundaries
Enthalpy of mixing
Activity of KCl

9. “MISSING DATA”
If GEX data for a particular interaction are “missing”, calculations can be performed assuming ideal mixing…
…likely to be OK for interactions between minor species,
but not for major species

10. DATA ASSESSMENT NiO-Al2O3 as an example EXPERIMENTAL DATA
phase diagram (1963)
liquidus points (1932)
compositions of spinels in equilibrium with Al2O3 (1965, 1981 and others)
thermodynamic properties of NiAl2O4 spinel
“degree of inversion” of NiAl2O4 spinel (1989, 1992 and earlier)

11. SPINEL MODEL (Ni2+, Al3+)1 (Ni2+, Al3+, Va)2 (Va)2 (O2-)4
“normal” NiAl2O4 - (Ni2+) (Al3+ Al3+) (Va)2 (O2-)4
“inverse” NiAl2O4 - (Al3+) (Ni2+ Al3+) (Va2) (O2-)4
“degree of inversion”
is the fraction of sites on the first sublattice occupied by Al3+

12. AND DEGREE OF INVERSION
INITIAL PHASE DIAGRAM
AND DEGREE OF INVERSION

13. CHANGING ENTHALPY / ENTROPY DATA FOR TWO SPINEL UNARIES
TO MODEL DEGREE OF INVERSION,
GIBBS ENERGY OF FORMATION AT K,
AND MELTING POINT OF NiAl2O4 SPINEL

14. AND DEGREE OF INVERSION PLOT
NEW PHASE DIAGRAM
AND DEGREE OF INVERSION PLOT

15. NOW INTRODUCE INTERACTION PARAMETERS IN SPINEL PHASE
TO MODEL EQUILIBRIA WITH Al2O3 (CORUNDUM)

16. NOW INTRODUCE INTERACTION PARAMETERS IN LIQUID PHASE
TO MODEL LIQUIDUS

17. (AND COMPARISON BETWEEN CALCULATED AND EXPERIMENTAL DATA)
FINAL PHASE DIAGRAM
(AND COMPARISON BETWEEN CALCULATED AND EXPERIMENTAL DATA)

18. MIRO (Mineral Industry Research Organisation) Projects RC54, RC81 and RC132
To develop a high quality, comprehensive thermodynamic database for oxide and sulphur containing systems of industrial interest for use in predictive phase equilibrium calculations
Facilitates calculations directly relevant to industrial processes for temperature and composition ranges outside the scope of hard copy phase diagram compilations
Systems and priorities determined by the sponsors
Database validated against plant / process data by sponsors

19. SPONSORS (current sponsors in white)
Johnson Matthey AEA Technology
Rio Tinto Outokumpu Oy
Corus Pilkington
Federal Mogul BNFL
Amplats MetalEurop
Sheffield University Shell
Britannia Zinc DTI

20. CURRENT ELEMENTS CURRENT SYSTEMS
Al, B, Ba, Ca, Cr, Cu, Fe, K, La, Li, Mg, Mn, Na, Ni, O,
Pb, S, Si, Sr, U, Zn, Zr
CURRENT SYSTEMS
Na2O-K2O-CaO-Fe-O-MgO-Al2O3-SiO2-S
Na2O-CaO-Fe-O-MgO-Al2O3-B2O3-SiO2
Li2O-Na2O-B2O3-SiO2
CaO-Cu-O-Fe-SiO2 (-MgO-Al2O3)
CaO-Fe-O-MnO-MgO-Al2O3-SiO2
CaO-Fe-O-PbO-ZnO-Al2O3-SiO2
CaO-MgO-Al2O3-SiO2-ZrO2
CaO-Cr-O-Fe-MgO-Al2O3-SiO2
CaO-Fe-O-MgO-NiO-Al2O3-SiO2
Cu-Fe-Ni-S-O (mattes / alloys)
Some BaO, La2O3, SrO, UO2 containing binary systems

21. AREAS BEING CONSIDERED FOR FUTURE WORK
CONTINUE TO EXTEND COVERAGE OF CURRENT OXIDES
plus
addition of Co, Mn, Pb to matte / metal phase
addition of CoO, TiO2, V2O3, rare earth oxides to oxide phases
molten salt - oxide systems
(including addition of CaF2 to oxide phases)
inclusion of P, As
inclusion of H2O (at high and low temperatures)
modelling volume changes in oxide phases

22. APPLICATIONS Preventing iron formation in zinc blast furnace
Analysing possible consequences of nuclear reactor accident
Modelling inclusion formation in steels
Analysing problems associated with glass making
Optimising recovery of Cu, Ni, precious metals
Investigating refractory wear
Improving understanding of cement manufacturing process
Modelling of corrosion
Pollution control
Process modelling (links with other commercial software)
Analysing why borax additions to steelmaking slags reduce
dust generation after solidification