Online spiral grade control

Abstract

Online control of gravity spiral concentrators has not been widely implemented, despite the scale of industrial spiral circuits and the associated labour requirements of manually adjusting the spiral splitter positions to counter disturbances. Previous industrial and academic attempts at automation initially showed some promising results, but have thus far not resulted in the implementation of large-scale control system at industrial sites. A new technique making use of jets of process water for the control of spiral product quality is proposed, and which is suitable for retrofitting to existing spiral circuits. A test programme carried out at a chromite plant processing UG2 flotation tailing at a site on the eastern limb of the Bushveld Complex in South Africa showed that online control of the spiral plant concentrate grade using this technique is feasible.