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NPL Oxide Database
The materials and process optimisation problems
faced by industry tend to be complex in nature, involving interactions
between many different types of material, such as slags, mattes,
ceramics, glasses, cements and minerals as well as gases and aqueous
solutions. This complexity has often stood in the way of the kind of
in-depth understanding necessary for successful and efficient process
control. Now, through the NPL oxide database, the tools are available
for oxide based systems which make such an understanding possible.
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Liquidus
projection for a quaternary oxide system
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The basic principle which underlies these projects is that phase
equilibria for multi-component systems can be calculated reliably from
critically assessed thermodynamic data for smaller sub-systems using
MTDATA, thermodynamics and phase equilibria software from NPL. Models
have already been developed and thermodynamic parameters derived for
liquid oxides, crystalline solutions and stoichiometric substances in
the Co-Cr-Cu-Fe-Ni-S-O matte / metal system and in the oxide systems
K2O-Na2O-CaO-MgO-Cu-Fe-O-Al2O3-SiO2-S and
CaO-CoO-Cu-Cr-Fe-O-MgO-NiO-Al2O3-SiO2 with selective additions of
As2O3, As2O5, B2O3, CaF2, CdO, Li2O, MnO, Nb2O5, TiO2, P2O5, PbO,
V2O3-V2O5, ZnO, ZrO2. Dilute solutions of OH-, SO42-, CO32- in selected
liquid oxides have also been covered. In addition models and parameters
have been developed to allow the calculation of condensed phase volume
and density changes and liquid oxide viscosities in the
Na2O-CaO-CoO-Cu-Cr-Fe-O-MgO-NiO-Al2O3-SiO2 system and the prediction of
critical cooling rates for glass formation.
Current work, determined by the wishes of the
NPL/MIRO RC211 project's industrial partners, includes increased
coverage of Nb2O5, B2O3 and Li2O containing oxide systems, the
introduction of additional Mn oxidation states, work on Pb, Mn, As, Sb,
Zn containing matte / metal systems and the introduction of NaF, TeO2,
Sb2O3 and SnO2. Complementary work on modelling the electrical
conductivity of liquid oxides is also under consideration.
Exploratory work on modelling hydrated phases such
as the calcium aluminate silicate hydrate gels important in cement
chemistry, their interactions with aqueous solutions of different
salinities over a range of temperature and their interaction with heavy
metals in aqueous solution has proved successful. Further work to
generate a practical database for use in predictive calculations
relating to cements is planned.
Combined with existing data for alloys and gases,
the NPL oxide database has already been used successfully to solve
problems associated with iron formation in zinc blast furnaces, to
assist in the extraction of copper and precious metals, to provide
information on liquidus temperatures, primary phases and interactions
with furnace atmospheres in glass making, to assess the consequences of
a nuclear reactor core meltdown and to model the behaviour of fly ash
in coal combustion. The power of this database as a predictive tool
will increase still further as its coverage continues to grow.
The RC211 project’s partners are able to
use the existing database to make predictive calculations which are
directly relevant to their own particular processes and which cover
composition and temperature ranges beyond the scope of paper based
phase diagram compilations. The feasibility of more economic and
environmentally sound routes can be explored, better choices of
materials can be made and experimental and pilot plant studies can be
directed more efficiently. In addition, partners will continue to steer
the project in terms of the choice of systems to be covered and the
priority assigned to each as well as gaining access to the MTDATA
calculation software under preferred terms.
For more information about the RC211 project or
associated projects at NPL please contact John Gisby.
Updated
1 March 2010
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