Dissolution of serpentine fibers under acidic flotation conditions reduces inter-fiber friction and alleviates impact of pulp rheological behavior on Ni ore beneficiation

Abstract

In beneficiation of Ni ores containing fibrous serpentines in large amounts, flotation pulps exhibit high viscosity, impacting Ni recovery and grade. Fibers entangle in pulp with formation of inter-fiber networks made up of micro floccs that spread across the pulp volume. These networks are sturdy and difficult to disentangle as inter-fiber frictional forces which are the predominant among the inter-particle forces restrict sliding of fibers at the inter-fiber contact points. The net force from numerous contact points in a network is significant. Therefore, the pulp yield stress value, a measure of net inter-particle forces, is considerably higher than that is typical in flotation. According to this study, the pulp yield stress decreases upon addition of H2SO4 to the pulp, which also correlates to the extent of serpentine dissolution. The continuation of fiber dissolution is necessary to maintain the inter-fiber frictional forces to a lower value, and serves as an inter-fiber lubricant for loosening of these networks. Thus, acidic conditions alleviate the impact of pulp rheological behavior on Ni ore beneficiation.