Dense medium cyclones (DMCs) have become the workhorse of the coal preparation industry due to their high efficiency, large capacity, small footprint and low maintenance requirements. Although the advantages of DMCs make them highly desirable, size-by-size partitioning data collected from industrial operations suggest that DMC performance can suffer in response to fluctuations in feed coal quality. In light of this problem, a multi-stream monitoring system that simultaneously measures the densities of the feed, overflow and underflow medium around a DMC circuit was designed, installed and evaluated at an industrial plant site. The data obtained from this real-time data acquisition system indicated that serious shortcomings exist in the methods commonly used by industry to monitor and control DMC circuits. This insight, together with size-by-size partition data obtained from in-plant sampling campaigns, was used to develop an improved control algorithm that optimizes DMC performance over a wide range of feed coal types and operating conditions. This document describes the key features of the multi-stream monitoring system and demonstrates how this approach may be used to potentially improve DMC performance. / Master of Science