Control strategy for a column flotation process

• Published in: Control engineering practice 2004-08, Vol.12 (8), p.963-976
• Main Authors: Persechini, Maria Auxiliadora Muanis, Peres, Antônio Eduardo Clark, Jota, Fábio Gonçalves
• Format: Article
• Language: English
• Subjects: Mineral processing; Modelling; Process control
• ISSN: 0967-0661; 1873-6939
• DOI: 10.1016/j.conengprac.2003.11.003

The flotation column is a multivariable process whose main control objective is to guarantee the metallurgical yield set for the process operation, expressed by the grade and the recovery of the valuable mineral in the concentrate. From the control technique standview, the three controlled variables, which severely affect the grade and the recovery in the flotation column, are the froth layer height, the air holdup in the collection zone and the bias. Three manipulated variables, namely wash water, air and non-floated fraction flowrates, are selected to keep the three controlled variables in stable operating conditions. A 3×3 transfer function matrix is used for representing the dynamics of this process. By using this transfer function matrix, an analysis technique based on the relative gain array is employed to determine the interaction between the variables and to help in the choice of proper pairing between controlled and manipulated variables. With the help of that analysis, the corresponding PI controllers are designed. In order to validate the proposed control strategies, the controllers are tested in a pilot-scale plant, at first for water–air operation and then for ore operation.