Process simulation in the mining and metals industry was introduced in the early 1960s, with the invention of the computer, and has been rapidly evolving since that time. Programming languages and calculation methodologies have been constantly expanding to encompass innovative technology and equipment into metallurgical software for use by engineers and operators. Essentially no longer bound by data storage space or model convergence time, the next stage of this evolution is the incorporation of valuable process models into operations. “Digital twin” is the commonly accepted term for this, and certainly defines the overall simulation system accurately, though does not stress the importance of the well-calibrated, robust process models required. Constructing a multi-disciplined metallurgical, engineering and operational team ensures reliable results and recommendations from any operation’s digital twin.