Modeling and design of multi-stage separation systems

Interest in recycling has surged in recent years due to shifting material costs, environmental concerns over material production and disposal, and laws in many countries designed to improve material recycling rates. In response, recycling systems are becoming more complex as increasing material recovery is required from products with complicated material mixtures such as WEEE (Waste Electric and Electronic Equipment). One common approach to increasing system separation performance is the use of multi-stage separation systems. The problem of estimating the performance and designing multi-stage separation processes has rarely been tackled from a system engineering perspective, resulting in poor integration and sub-optimal configuration of industrial multi-stage separation systems. This paper presents a systematic approach to modeling and analyzing multi-stage separation processes. Individual separation processes modeled as Bayesian binary separation steps are incorporated into network models through mass flow rate equations. The model can be used to evaluate the performance of these multi-stage separations under varying conditions, informing decisions about system configuration and process performance. Several basic examples demonstrate the utility of this model for design decisions. The industrial value is demonstrated through a real case study featuring PET plastic and aluminum flake separation in the beverage container recycling industry.