Microelement distribution during matte smelting

Kho, T 2006, Microelement distribution during matte smelting, Doctor of Philosophy (PhD), Civil and Chemical Engineering, RMIT University.


Document type: Thesis
Collection: Theses

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Title Microelement distribution during matte smelting
Author(s) Kho, T
Year 2006
Abstract Element distribution studies provide part of the necessary framework for improving the sustainability of base metal production by opening future opportunities for profitable recovery or by anticipating future legislative restrictions that impact on profitability. Determining the distribution of microelements between the phases present during copper smelting by classical methods is often very difficult, and because there are potentially so many of them, very time-consuming and expensive. The main focus of the present study was to develop a generic model to predict the distribution behavior of minor and microelements and then to validate it.

The distribution of elements between matte & slag was examined thermodynamically to develop the generic model. The procedure involved predicting the likely form of the species present in matte and slag, determining the equilibrium constant for the interaction between those species, making an assumption about the value of the activity coefficient ratio for them and then calculating the distribution ratio. When activity coefficient data was available in the literature it was used, otherwise they were assumed to be unity. The model was first validated against published distribution data available and the agreement found was generally satisfactory.

Since distribution data is only available for a limited range of elements, experiments were performed to obtain the necessary data for other elements. The distribution of microelements was studied at 1523 K using industrial matte and slag as well as with matte and slag samples synthesized from laboratory reagents. The industrial matte and slag samples provided the distribution behavior of many microelements naturally present, whereas the synthetic phases were used to determine the distribution behavior of two selected elements, cobalt and tungsten. The predicted distribution coefficients again compared very well with the experimental data derived from this study.

Two cases were identified where the generic model predicted the distribution behavior poorly, with failure in both cases being due to difficulties with activity coefficient data. Group I and II elements in the Periodic Table form very basic oxides which interact very strongly with oxides in typically acidic copper smelting slags. Their activity coefficients are very much smaller than unity. Metals which can be present as neutral atoms in slag and/or matte also behave very non-ideally, and there is almost no published data on their activity coefficients. That which is available indicates activity coefficient values much greater than unity.

In general, the results documented in this study shows that the generic model developed can be used as a reliable predictive tool when experimentation is inconvenient or inadvisable.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Civil and Chemical Engineering
Keyword(s) Microelement
Impurity element
Distribution coefficient
Activity coefficient
Matte smelting
Copper matte
Iron silicate slag
Saturation
Cobalt
Tungsten
Distribution thermodynamics.
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