A system and method for providing raw mix proportioning control in a cement plant. A raw mix proportioning controller determines the correct mix and composition of raw materials to be transported to a mixer. The raw mix proportioning controller uses an inverse controller to determine the proper mix and composition of raw materials. The inverse controller takes targeted set points and the chemical composition of the raw material as inputs and generates the proportions of the raw material to be provided as an output for the next time step. The output is generated by using a geometric interpretation of the control process and a non-linear constrained optimization.