Pyrometallurgy Advanced Computing Introduction Facilities Research

Thermal Radiation Modelling
One of the principal uses of the advanced facilities is for the detailed modelling of thermal radiation interchange occurring over three-dimensional surfaces. In order to compute the energy interchange over arbitrarily shaped surfaces, the surfaces are approximated with large numbers of triangular elements. View factors are computed between all elements in the model, which requires enormous amounts of computer power (when accurate shadowing is calculated, the size of the problem scales as N³, where N is the number of elements in the model). This sort of model is frequently used in our field for the design and analysis of the freeboard gas spaces of DC plasma arc (and other) furnaces.

Computational Fluid Dynamics Modelling
Currently under development is a partially-coupled 3D magnetohydrodynamic model of the DC plasma arc, which is the source of thermal energy in our smelting furnaces. The plasma arc is an increadibly intense gas jet flow, which at industrial scale may exceed temperatures of 20,000^oC and travel at several kilometers per second. Video footage of the arc region taken on our pilot plants suggests that it is an extremely dynamic environment, so our modelling work is focussing on the time-dependence of the arc motion, and how it interacts with both the liquid slag surface beneath it and the freeboard gas space around it.

Molecular Mechanics Modelling
Also under development are some relatively simple models of molecular structure for components of networked slags. The covalent bonds found between Silicon and Oxygen in particular can lead to very complex structures in silicate-rich slags, and an understanding of the physical shape and means of formation of such structures is potentially of great value to metallurgical processes making heavy use of these slags.

Data Visualisation
As a large portion of the advanced computing work performed here has a strongly qualitative component, we try to present results in a way that has both physical meaning and is immediately accessible to someone unfamiliar with the inner workings of the mathematical models used. Visualisation techniques based on the graphical capabilities of the modern desktop PC have thus been developed extensively - we use a mixture of both in-house and open source software which renders results as static ray-traced images, interactive web-capable VRML, hardware-accelerated 3D surface graphics, or frame-by-frame animations for time-dependent data.

In addition, we investigate the use of alternative 3D rendering techniques in the CAD and related fields, using for example modern computer game graphics engines coupled with cheap consumer 3D accelerator cards to massively reduce the cost of operating an advanced graphics workstation.

Snapshots from a VRML 3D model showing the thermal profile over the interior surfaces of a DC smelting furnace:

A frame from an animation result of three arc columns interacting magnetically:

Selected frames from an animation showing the result of a CFD plasma arc simulation with three arc columns. The first shows the 5000K temperature contour around the arcs, the second shows the velocity vectors greater than 50m/s, and the third shows the deformation that the arc jets are causing on the liquid slag below them:

Static rendered images, ray-traced and VRML, of some silicate molecular structures. The first three show various views of a large SiO anion (red are Si atoms, blue are O atoms, and grey are O^- anions), and the last two are images of a small SiO anion with its structure being modified by the presence of different types of cation (Na⁺ are yellow, and Mg²⁺ are light blue):