From Iterative Balance Models to Directly Calculating Explicit Models for Real-time Process Optimization and Scheduling

Abstract

Optimal utilization of complex processes involves realtime operational optimization and scheduling, especially in cases where the production line consists of both continuous and batch operated unit processes. This kind of real-time optimization requires process models which can be computed significantly faster than realtime. Iterative balance calculation is typically far too slow for these cases. This paper presents a method for converting an iterative balance model to a directly calculating model suitable for on-line process optimization. The approach is demonstrated with the first unit process in the copper smelting line, the flash smelting furnace (FSF). The method consisted of formulating an equation group based on the constrained FSF HSC-Sim model and solving the unknown parameters and static states with use of a symbolic calculation software. The solution was implemented as a function whose calculation time fulfilled the requirements for scheduling use.

Modelling copper smelting – the flash smelting plant, process and equipment

“…An increased throughput with minimum CAPEX requires de-bottlenecking of the smelter and its combined refinery flow-sheet. It is benefitted from feed-forward and feed-backward information of the product streams as well as from the state and performances of the unit processes [7][8], such as off-gas train and its gas handling capacity, or solution purification of the tank house and its limits in, e.g., arsenic elimination from the electrolyte. Sometimes, this approach can be applied from ore mining to refining, and even linked with metal prices [9].…”

“…The smooth linking a continuous (Flash Smelting) and batch (Peirce-Smith matte converting) steps at the smelter requires accurate scheduling of matte tapping and the materials transport operations because of a limited storage capacity for melts at the copper smelters (Björkqvist et al 2018).…”

“…Most copper smelters of today run with essentially continuous smelting step and use batch-wise operating matte converting and blister copper fire-refining steps. The smooth linking a continuous (Flash Smelting) and batch (Peirce-Smith matte converting) steps at the smelter requires accurate scheduling of matte tapping and the materials transport operations because of a limited storage capacity for melts at the copper smelters (Björkqvist et al 2018).…”