Synthesis of a paste backfill geopolymer using pure acidic gold mine tailings

Gold mine tailings (GMT) were characterised and alkaline activated into geopolymers so as to reduce their pollution potential. The GMT was activated because they are aluminosilicate materials and as such they have the potential to be geopolymerised under alkaline conditions. The main parameters tested were the effect of type of alkali (NaOH and KOH), concentration of alkali, liquid to solid ratio, curing time and temperature. The optimum synthesis conditions were 10 M KOH, liquid solid ratio of 0.26, curing temperature and time of 90°C and 5 days respectively. The reduction in the intensity of XRD peaks coupled with the decrease in FTIR wavenumbers for the major peak may be used as a sign for geopolymerisation of GMT. This study provides an opportunity for the use of GMT as raw material for the production of paste although there is still need to allow the curing to take place at room temperature to reduce energy consumption associated with the geopolymerisation process.