With FactSage 5.3 & 5.4 there have been many changes, not only in the content of the databases, but in the way they are organized and used.  Be sure to read the general documentation "How to use the databases with FactSage 5.4" on the previous menu.  

FThall

FACT Hall-Héroult Database

 

The FThall Database has been developed for thermodynamic and phase equilibrium calculations involving liquid metal – cryolitic bath – Al2O3-based oxides in alumina reduction electrolysis cells, and for molten aluminum treatment with fluoride fluxes.

 

The FThall Database is a self-contained database for the Al-Mg-Na-Li-Ca-F-O system.  No extra phases from other databases are needed for this 7-component system (except Al-Ca and Mg-Ca stoichiometric intermetallic phases Al4Ca, Al2Ca, Mg2Ca, etc…, and the Li-Mg-BCC and Mg-Li-HCP solid solutions).

 

The Gibbs energy parameters of the FThall Database have been obtained by a critical analysis and optimization of all available thermodynamic data and phase equilibrium data of the Al-Mg-Na-Li-Ca-F-O system.  These include electromotive force (emf), calorimetry (mixing enthalpies, dissolution enthalpies, heating curves, etc…), metal-salt-gas equilibria (vapor pressures, equilibrium alkali-content of molten Al with different bath compositions), phase diagram data (liquidus, solubilities, eutectic temperatures, etc…).

 

In general, the simultaneous use of data from Fthall and any other database may give rise to problems of compatibility.

 

 

PHASES

 

The following SOLUTIONS are found in the FThall Solution Database:

 

Cryolitic bath                                                                            FThall - Bath

High-temperature Na3AlF6 solid solution                                   FThall - CryH

Low-temperature Na3AlF6 solid solution                                   FThall - CryL

Very low-temperature Li3AlF6 solid solution                              FThall - LiCB

Low-temperature Li3AlF6 solid solution                         FThall - LiCG

High-temperature Li3AlF6 solid solution                         FThall - LiCD

Cryolithionite Na3Li3Al2F12 solid solution                                   FThall - CrLt

NaF rocksalt solid solution                                                        FThall - NaF

LiF solid solution                                                                      FThall - LiF

MgF2 solid solution                                                                   FThall - MgF2

Liquid alloy                                                                               FThall - Liq

FCC Al-rich solid solution                                                        FThall - FCC

HCP Mg-rich solid solution                                                       FThall - HCP

BCC Ca- or Na-rich solid solution                                            FThall - BCC

Al12Mg17 gamma solid solution                                      FThall - AlMg

MgAl2O4 spinel solid solution                                        FThall - Spin

Monoxide CaO – MgO solid solution                                       FThall - Mono

The following COMPOUNDS are found in the FThall Compound Database:

 

Li                             S    L   

Li2O                           S    L   

Li2O2                          S   

LiF                            S    L   

Na                             S    L   

NaO2                           S   

Na2O                           S1   S2   S3   L   

Na2O2                          S1   S2  

NaF                            S    L    G    

(NaF)2                         G   

Mg                             S    L   

MgO                            S    L   

MgF2                           S    L   

NaMgF3                         S   

Al                             S    L   

Al2O3                          S1   S2   S3   S4   L   

LiAlO2                         S   

AlF3                           S1   S2   L   

Li3AlF6                        S1   S2   S3  

NaAlO2                         S1   S2  

NaAl9O14                       S   

Na2Al12O19                     S   

Na3AlF6                        S1   S2  

Na5Al3F14                      S   

Na2LiAlF6                      S1   S2  

Al8Mg5                         S   

Al29Mg21                       S   

MgAl2O4                        S   

Na2MgAlF7                      S   

Ca                             S1   S2   L   

CaO                            S    L   

CaO2                           S   

CaF2                           S1   S2   L   

CaAl2O4                        S    

CaAl4O7                        S   

CaAl12O19                      S   

Ca3Al2O6                       S   

CaAlF5                         S1   S2  

Ca2AlF7                        S   

LiCaAlF6                       S   

NaCaAlF6                       S1   S2   S3  

NaCaAl2F9                      S   

 

Note: all gaseous species (NaAlF4, Na2AlF5, AlF3, AlF, AlOF, etc..) are found in the FACT53 Compound Database.

 

Note: the FThall database is compatible with C(graphite), CO(g), CO2(g) and other C-O species in the FACT53 Compound Database.

 

 

The following limitations should be considered when using FThall:

 

·                    Metal dissolution in the bath - NaF-AlF3-[Na-Al]:         the model covers the whole liquid range for P < 3 atm (the Na-NaF liquid miscibility gap cannot be "closed" at high pressures).  Metal dissolution outside the NaF-AlF3-Al2O3 system is approximate

 

·                    Alumina dissolution in the bath - NaF-AlF3-Al2O3:        the model has good predictive capabilities for CR < 5 and CR > 1.5 and for T < 1100oC.  A spurious miscibility gap appears for very high CR at NaAlO2-NaAl9O14 co-saturation.

 

·                    Fluoride additives:         In the oxide-free system, the model covers the whole range of composition in the LiF-NaF-MgF2-CaF2-AlF3 system but predictions in the LiF-MgF2-AlF3 system rich in AlF3 are not very good.  The error in the calculated liquidus of AlF3 may also be large in the CaF2-AlF3 system.