Anionic Polyacrylamide and Carboxymethyl Cellulose on Flotation Performance of a Cu-Ni-PGM Ore in Degrading Water Quality

• Higher amount of solids reported to the concentrates in the presence of 100 g/t PAM. • Water recoveries were the lowest in the presence of 100 g/t PAM compared to 100 g/t CMC. • Ni recoveries were the highest in the presence of 100 g/t PAM compared to 100 g/t CMC. • Cu and Ni grades were the highest in the absence of PAM and CMC. • The settling rate of tailings was the poorest in PAM compared to CMC. Water scarcity is one of the leading environmental concerns, globally. South Africa as a mining rich economy is also faced with this threat. To respond to this global threat, most mining operations, recycle process water within mineral processing plants. This approach to onsite water management reduces the dependence on municipal or potable water. Within minerals processing plants, froth flotation, which is used to separate valuable minerals from gangue minerals contained within an ore, is water-intensive and may contain some substances which are harmful to the environment and/or the process performance. The recycling of the process water within operations may, therefore, benefit the environment as the discharge of effluent is minimised. Furthermore, since the process water is recirculated from the concentrates and tailings dewatering unit operations, there may be some residual reagents present in the recirculated water, this may be beneficial or detrimental to flotation depending on how residual reagents affect flotation chemistry. However, the recycling of water also leads to a build-up of ions which may have a negative impact on flotation performance. How the accumulated ions affect the flotation performance and tailings dewatering in the presence of flotation reagents such as PAM and CMC are topics of interest and fundamental to understanding the control and management of water quality together with its associated effects on the process. Hence, this study makes a comparative analysis between PAM and CMC on flotation performance and tailings dewatering in different water qualities of increasing ionic strength. Batch flotation results indicate that polymers and ionic strength of plant water significantly impact the flotation performance of Cu-Ni-PGM ore. PAM generally led to higher solid recovery in concentrates compared to CMC or no polymers. Increased ionic strength enhanced water recovery and froth stability, but slightly reduced solids recovery with PAM, while improving it in the absence of polymers or with CMC due to gangue activation. Ionic strength had no effect on copper and nickel recoveries but negatively impacted concentrate grades with CMC, while PAM showed no influence. Settling rates improved with CMC as ionic strength rose, but decreased with PAM, although PAM consistently had a faster settling rate overall.