Development and utilization of detailed process and technology models at RUSAL alumina refineries

Abstract

RUSAL is completing the development of detailed steady-state mathematical models of the process technology of its alumina refineries in the current year. Models have been developed for refineries based on different technologies: Bayer process, parallel Bayer-Sinter and Sinter processes. Each model includes equipment specifications for the production sites, mud disposal and Combined Heat and Power Plants (CHPP). The control logic of the models reproduces a refinery control system. Particular attention was paid to the creation of kinetics relationships for digestion processes, which help to predict recovery of alumina and alkali, as well as the thermodynamic equilibrium of impurities in liquors. A large number of laboratory studies have been performed for the development of these thermodynamic and kinetic models. Several types of problems are solved using these mathematical process models, such as sensitivity investigations, “What-if” analyses, production optimization, business planning and estimation of capital investment efficiency. RUSAL has organized departments for mathematical modeling at their refineries and a central development team in its St. Petersburg office. Refinery specialists monitor the production process, and perform routine daily calculations. They propose solutions for managing the production process to achieve maximum refinery efficiency based on their experience and modelling results.