Abstract
Several technologies have been developed to treat acid mine drainage (AMD) and attention is shifting towards the removal of sulphate. The formation of ettringite, a hydrous calcium aluminium sulphate mineral, is an option to treat AMD and can reduce the sulphate concentration to well below the discharge specifications. The process modelled in this study includes the formation of ettringite and the recovery of gibbsite through the decomposition of recycled ettringite. The modelling of this process was done using PHREEQC and the results presented in this paper are based on the outcome of different case studies that investigated how the process is affected by a change in parameters. These include, changing the feed water pH, altering the split fractions in the hydrocyclone for the gibbsite recovery and varying the pH for ettringite formation.
Highlights
South Africa is the 30th driest country in the world with its water resources termed as scarce and extremely limited (Government Communication and Information System, 2015)
Whereas the mining sector is a key contributor to the South African economy, it is a major consumer of water and the production of acid mine drainage (AMD) from abandoned mines poses a threat to the water quality if it seeps into the groundwater supply or if it enters the surface water environment
This presents a challenge in reconciling the need for growth with the protection and sustainability of water resources, whilst still cultivating the economic benefit gained from the mining sector (DWAF, 2009)
Summary
South Africa is the 30th driest country in the world with its water resources termed as scarce and extremely limited (Government Communication and Information System, 2015). Whereas the mining sector is a key contributor to the South African economy, it is a major consumer of water and the production of acid mine drainage (AMD) from abandoned mines poses a threat to the water quality if it seeps into the groundwater supply or if it enters the surface water environment. This presents a challenge in reconciling the need for growth with the protection and sustainability of water resources, whilst still cultivating the economic benefit gained from the mining sector (DWAF, 2009). The discharge of sulphate increases the salinity of the receiving water bodies and contributes considerably to the total dissolved solids in mineimpacted water (Liang et al, 2015)
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