Process Control of Ball Mill Based on MPC-DO

Xisong Chen,Zhijie Zhong,Jiawei Yang,Junyong Zhai,Omar-Jacobo Santos

doi:10.1155/2021/9994666

Abstract

The grinding process of the ball mill is an essential operation in metallurgical concentration plants. Generally, the model of the process is established as a multivariable system characterized with strong coupling and time delay. In previous research, a two-input-two-output model was applied to describe the system, in which some key indicators of the process were ignored. To this end, a three-input-three-output system is proposed to improve the model accuracy. Moreover, some practical and effective control strategies have been studied. The common control methods, including model predictive control (MPC), disturbance observer (DO), and so on, show poor performance when strong external and internal disturbances exist. In this paper, a composite control strategy based on MPC-DO is put forward to realize the control of the three-input-three-output ball mill system. The disturbances of the system consist of external disturbances including fluctuation of ore hardness and internal disturbances including model mismatches and strong couplings. The proposed MPC-DO controller includes a feedback control component based on MPC and a feed-forward compensation component based on DO. The simulation results indicate that the composite control scheme based on MPC-DO has good performance of tracking and anti-interference in process control of the ball mill.

Highlights

Grinding and classification process (GCP) is a key process in the beneficiation production process of the metallurgical industry
A compound control strategy for process control of the ball mill is proposed to describe the grinding process precisely where disturbances exist. It consists of two types of controllers—a feedback regulation component based on model predictive control (MPC) and a feed-forward compensation component based on disturbance observer (DO)
A three-input-three-output model is introduced in the paper to deal with the problem that traditional two-input-two-output model cannot describe the characteristics of the system precisely. en, a compound control strategy including a feedback regulation component based on MPC and a feed-forward compensation component based on DO is proposed in order to improve the performance of anti-disturbance

Summary

Introduction

Grinding and classification process (GCP) is a key process in the beneficiation production process of the metallurgical industry. Different from the traditional two-input-twooutput model of the ball mill grinding process, a three-inputthree-output system considering the influence of three factors (i.e., fresh ore feed, dilution water, and mill feed water) is put forward to improve the accuracy of modeling. A compound control strategy for process control of the ball mill is proposed to describe the grinding process precisely where disturbances exist It consists of two types of controllers—a feedback regulation component based on MPC and a feed-forward compensation component based on DO. As the MPC-DO controller inherits advantages of both MPC and DO, it shows great performance in the following three aspects: (1) good decoupling property, (2) ability to deal with processes with time delay, and (3) capability in dealing with strong disturbances.

Grinding Process of Ball Mill

Design of Controller

Simulations

Findings

Conclusion