Open AccessSilicon and aluminium leaching kinetics from acidic gold mine tailings
Author(s) -
Thabo Falayi,
Tebogo Mashifana,
Freeman Ntuli
Publication year - 2019
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/652/1/012046
Subject(s) - leaching (pedology) , tailings , calcination , leachate , aluminium , alkali metal , metallurgy , materials science , selective leaching , silicon , chemistry , environmental chemistry , catalysis , environmental science , biochemistry , organic chemistry , copper , soil science , soil water
Si and Al were leached from gold mine tailings (GMT) in order to determine if the GMT could be used as precursors for the synthesis of geopolymers. Possible synthesis of geopolymers from GMT would help reduce their potential pollution effects through heavy metal immobilisations. The effect of type of alkali (NaOH/KOH), alkali concentration, temperature, milling and calcination of GMT and solid liquid ratio (S/L) on the leaching of Si and Al was investigated. The optimum conditions were 10 M KOH, S/L of 0.5% m/v and a leaching temperature of 95°C. The leaching obeyed the shrinking core model with the surface chemical reaction being the controlling step. The leaching of Si was linked to the Al leaching since the Si/Al ratio of the leachate was around 2 irrespective of leaching conditions. KOH yielded more Si and Al. as compared to NaOH, with 54.7 and 26.7 Si and Al leached respectively from as received GMT. Calcination at 900°C resulted in 18% and 22 % increase in Si and Al yield respectively for KOH based leaching. The successful leaching of Si and Al from GMT using KOH provides opportunities for the geopolymerisation of GMT thereby allowing the minimisation of their pollution effects.