标题：Total and Soluble Aluminium Concentration and Suspended Particles Size Distribution Impacted by Sulphate and Silica After the NaOH Neutralization of Al-bearing Acid Mine Drainage
摘要：A laboratory study was conducted to evaluate the effect of sulphate and silica on both, total and soluble aluminium concentrations in Al-bearing acidic rock discharge (ARD) treatment by NaOH. Independent variables included pH and different molar Al:SO4 and Al:Si:SO4 ratios. The experimental results showed that either sulphate or silica or both in combination influenced discharge of total and suspended Al concentrations. Sulphates reduced the soluble Al concentration by forming basaluminite, which is more insoluble than amorphous aluminium hydroxide. Particle size distributions after settling showed that the fraction and diameters of particles decreased with increasing sulphate concentration. Elevated silicate results in increasing the total aluminium level in the supernatant after 48 hours of settling. The co-presence of sulphate with silica encouraged the formation of Si(OH)4, rather than Alsilica precipitates. However, the silica decreased the size of particles in the supernatant after settling, thus increasing the effluent particulate-bound Al concentration.
