After the successful implementation of a Blue Cube MQi on their UG2 final concentrate line, Northam Platinum installed a second Blue Cube MQi in their flash flotation concentrate line.

The benefits of flash flotation have long been known, but the Blue Cube MQi application adds a valuable new dimension to this flotation technology.

The Blue Cube MQi unit measures the PGM (g/t) and Cr2O3 (%) concentration of the flash flotation cell concentrate in real time. This flash flotation concentrate then joins up with the re-cleaner concentrate in feeding the final cleaner columns.

Spearheading this application at Northam were metallurgical manager, Danie Minnaar, and Technical superintendent, Daan Smit. Together with the rest of the team, they implemented an automatic Cr2O3 grade controller on the flash flotation cell.

The PI controller utilises the Blue Cube MQi output to control the chromite (Cr2O3) content at a desired set point by adjusting the airflow rate to the flash flotation cell.

The Flash Flotation Blue Cube unit   Shown left is the In-line Blue Cube MQi unit with the poppet sampler assembly. Northam Technical superintendent Daan Smit with Van Wyk du Plessis, the Blue Cube Systems engineer responsible for commissioning the unit.

The illustration, below, shows the schematic of the automatic control loop.

The following graphs show the chromite grades from the flash cell concentrate for a number of hours. Figure 1 shows the substantial deviations before control. After tuning the control loop, the chromite grade is controlled at a stable value between 3 % and 4 %, as shown in Figure 2.

Figure 1. Chromite variation: 2 February 2009

Figure 2. Chromite variation: 6 February 2009

Blue Cube directors visited Northam to congratulate the Northam staff on their achievements.   Pieter de Waal and Francois du Plessis, both directors of Blue Cube Systems (Pty) Ltd, with Northam metallurgists Daan Smit and Johan Janse van Vuuren.