Efficient operation of a platinum minerals processing facility requires accurate measurements of critical process parameters such as flow and density. In many cases, the accuracy and noise characteristics of older flowmeter technologies such as ultrasonic Doppler, electromagnetic or Coriolis flowmeters is inadequate for monitoring, control and process improvement purposes. The latest generation of flowmeters, based an array of sensors externally mounted to a pipe, has demonstrated superior noise performance and accuracy relative to other flowmeter technologies. In addition, entrained air bubbles in slurry streams can lead to significant inaccuracies in density measurements thus leading to appreciable offsets in mass balance calculations. Besides measuring flow from the outside of the pipe, the array based technology has demonstrated the ability to measure the volume of entrained air bubbles in a slurry stream. This information has been used to compensate the density measurement from a nuclear density gauge thus enabling the accurate calculation of true mass flow rates. The principle of operation of this technology, the use of both flow and entrained air measurements to determine true mass flow rates, will be detailed. Case studies of applying this technology to minerals processing operations including platinum facilities will be discussed.