Mathematical models for maximizing aggregate plant production

An aggregate production plant mainly consists of conveyors, crushers, and screens. How to set up the closed-side openings of crushers and the openings of screens is an important issue for the plant manager in order to maximize the plant's production, and to produce the aggregate with the required consistent size distribution. This research attacks the problem through a mathematical approach. A nonlinear model is first constructed by treating settings of screens and crushers as decision variables. Solving the model, the maximum production rate and the optimum settings of the plant can be directly obtained. Because of the difficulties in solving the nonlinear model, a linear mathematical model is obtained by fixing the settings of screens and crushers at specific values. Solving the linear model, the plant maximum production rate can be obtained under the given settings. Sensitivity analysis can then be conducted to identify the optimum settings of screens and crushers. A case adopted from an actual aggregate production plant is used to illustrate the modeling and optimization process. A significant improvement in the plant's production is achieved through the study.