Virtualization of a tube digester in alumina production

Abstract

In this work, we develop a digital twin of a tube digester and a software application automatically calculating the aluminate solution quality based on mass balance equations with the purpose of improving the quality of hydro-chemical process management at the Rusal Achinsk JSC alumina plant. A mimic diagram of the nepheline sinter leaching process was visualized using the Wonderware InTouch software package. Quick scripts were created to display the process animation. The input parameters include the solution temperature, the consumption of sinter and recycled solution, as well as the chemical composition of raw materials. The air temperature, vibrations and equipment malfunction were used as the main disturbing effects. Output parameters consisted of sludge and aluminate solution yields, power consumed by the drive and the silicon ratio of the resulting solution. Based on the mass balance of sinter and recycled solution, calculated using industrial laboratory data, an algorithm for modelling variations in the digestion process and a software application for calculating the quality of aluminate solution were developed using the InTouch built-in capabilities of scripting in its own programming language. A digital twin of a tube digester was developed on the basis of an operating unit utilized at the Rusal Achinsk JSC. It was shown that the developed software application predicts the quality of the finished product (aluminate solution) using a simple balance model under variations in both the composition of raw materials (cake and recycling solution) and the rate of fed raw materials, as well as present the results of calculations performed using a mimic diagram of the process. Thus, the developed interface can be used to simulate various technological operations performed in a tube digestor, including solution drainage, sludge discharge and variations in the inlet flows. At the same time, it becomes possible both to observe current changes in process parameters and archive plots, as well as to select the optimal composition of raw materials to obtain an aluminate solution of higher quality.