Optimisation of the three-product cyclone at Greenside Colliery

¹ Metallurgical Engineer, Metallurgy Department, Greenside Colliery, South Africa
² Metallurgical Manager, Greenside Colliery, Thungela Resources, South Africa
³ Processing Manager, Thungela Resources, South Africa
⁴ Head of Coal Processing and Business Improvement, Thungela Resources, South Africa

^* Corresponding author: Tsireledzo.Maliehe@thungela.com

Abstract

Greenside Colliery implemented the three-product cyclone in 2013 to reduce discard footprint. Over time, changes in primary product specifications and inherent ROM characteristics caused a lower quality middling fraction below RB4 specifications. This required optimising of the three product cyclone operational settings to mitigate the above impacts. The objective of this test work was to optimise the middling product via two steps, namely (1) manipulating the vortex finder length and (2) testing different water injection flow rates. Four vortex finder lengths were tested and the results showed that a 75% (10.5 cm) vortex finder length was the ideal setting. Similarly, for the water injection, four flow rates were tested resulting in 50 m3/hr being the ideal flow rate. At these settings, the secondary cyclone achieved a calorific value (CV) within the required RB4 specifications. Optimising the three-product cyclone is essential for the revenue of the plant and to ensure that the middlings revenue stream is maximised. Continuous test work is recommended because, as ore types and characteristics change, the optimum secondary cyclone settings will need adjustments. As well as changes within the process, any changes that impact the DMS will necessitate a review of the secondary cyclone settings