Electroosmotic dewatering and consolidation of mineral waste tailings

Abstract

Effective dewatering of mineral waste tailings and subsequent disposal are important issues which confront the mining and mineral processing industry world-wide. Conventional, ore treatment and hydrometallurgical processes used in the extraction of value metals from low grade ores involve the production of fine particles via grinding for desired liberation.They require the utilisation of voluminous amounts of water, generating equivalently large volumes of intractable waste tails of low solid density. For clay slimes, flocculation and thickening operations used for dewatering produce fast settling rate but low sediment consolidation, even after several years of impoundment in dams; warranting alternative, cost-effective methods for enhanced dewaterability. In the present work, electroosmotic dewatering and consolidation of model and real kaolinite and smectite clay mineral pulps were investigated. The study focused on probing the specific influence of variables such as the dispersion pH, supernatant (electrolyte) concentration, voltage input, and current reversal/intermittence on electrical energy consumption during electroosmosis and establishing optimum physico-chemical conditions conducive to the electroosmotic dewatering process. Remarkable efficacy in electroosmotic consolidation, reflecting a dramatic increase in clay slimes sediment loading by 20-30 wt per cent to 'spadeable' pulps was readily achieved at acceptable power consumption rates under laboratory scale conditions.