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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.

Liquidus projection for a quaternary oxide system

Liquidus projection for a quaternary oxide system

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