Modem controllers are based on the use of mathematical models. However the models are always obtained through a reduction in the complexity of reality. Consequently, their ability to properly represent the general behavior of the processes is very limited. Therefore, it is advantageous to analyze the problem resulting from model uncertainty in the control of mineral processing plant. This problem has often been ignored in theoretical studies and in practical process control. This paper will first show an H infinity (H∞) method on how to achieve the benefit of feedback in the face of uncertainties. Then it will present grinding process example which illustrates the use of robust control to provide satisfactory performance despite of system uncertainties in mineral processing plant.