Effect of potassium silicate and aluminate on the stabilisation of gold mine tailings

Abstract

In this study, acidic gold mine tailings were alkali activated using potassium hydroxide (KOH). The effect of potassium silicate (KS) and potassium aluminate (KA) on the strength and durability of the synthesised geopolymers was investigated. An optimisation experimental programme of various conditions was used to get the best geopolymers in terms of strength and metal leachability. A 1·1 mass/mass (m/m) potassium silicate : potassium hydroxide activation solution yielded a geopolymer with an unconfined compressive strength (UCS) of 9·94 MPa after curing for 5 d at 80ºC. A 2·8 m/m potassium aluminate : potassium hydroxide activation solution yielded a geopolymer with a UCS of 18·10 MPa after curing for 5 d at 100ºC. The potassium aluminate-based geopolymer was more durable for use as a backfill material as, after 10 wet and dry cycles, it had a UCS of 4·8 MPa whereas the potassium silicate-based geopolymer had a UCS of 1·23 MPa. The potassium aluminate-based geopolymer resulted in over 85% reduction in leachability of heavy metals from the cured geopolymer. This study showed that potassium aluminate activation of acidic gold mine tailings is an attractive route to stabilise/solidify hazardous material. The use of elevated temperature to achieve high strength for the geopolymer pales in comparison to the energy requirements of cement production.

Electrodialytic remediation of municipal solid waste incineration fly ash as pre-treatment before geopolymerisation with coal fly ash

“…The reactive Al and Si of the FA and TFA was similar or even higher than of the CFA at ambient temperatures. The reactive Al and Si concentration increased with higher temperature, which has also been found for metakaolin (Granizo et al, 2014) and gold mine tailing (Falayi, 2019). Note that the increase in Si reactivity for CFA at 25 and 80 °C was two times the reactivity of Al, which means that the reactive Si/Al ratio under high temperature increases and this could favor the development of compressive strength for CFA geopolymers (Tzanakos et al, 2014).…”

Mine tailings-based geopolymers: Mechanical and physical properties

“…The geopolymer ˑconstructed ˑfrom ˑgold mine tailings and ˑdifferent ˑalkali-activated, ˑas ˑwell ˑas ˑadditional ˑalumina-silicate ˑcomponents, has been the ˑtopic ˑof ˑa ˑfew ˑstudies ˑto ˑwhich ˑresearchers ˑhave ˑgiven ˑspecial ˑattention. Gold mine ˑwaste-geopolymer ˑcomposites ˑwere ˑcreated ˑby ˑFalayi [135] ˑutilizing ˑpotassium ˑaluminate, ˑpotassium ˑsilicate, ˑand ˑpotassium ˑhydroxide ˑactivators. ˑAccording to its findings, ˑthe ˑmaximum ˑcompressive ˑstrength ˑof ˑgold ˑmine ˑtailings-geopolymer ˑcomposites was discovered ˑat ˑa ˑpotassium ˑsilicate/potassium ˑhydroxide proportion ˑof ˑ1.1.…”

Mine tailings-based geopolymers: Durability, microstructure, thermal and leaching properties

“…ˑThe ˑbeneficial ˑimpact ˑof ˑcement ˑkiln ˑdust ˑwas ˑconnected ˑto ˑimproved ˑaluminosilicate ˑdissolving, ˑproduction ˑof ˑcalcium ˑcarbonate, ˑand ˑcalcium ˑincorporation ˑinto ˑthe ˑgeopolymer ˑsystem. ˑFalayi ˑ [50] ˑdemonstrated ˑthat ˑactivating ˑwith ˑpotassium ˑaluminate ˑresults ˑin ˑa ˑbetter ˑresistance ˑof ˑgeopolymers ˑto ˑalternate ˑwetting ˑand ˑdrying ˑthan ˑpotassium ˑsilicate. ˑIn ˑevery ˑcase, ˑthe ˑUCS ˑvalues ˑdropped ˑmore ˑthan ˑthreefold ˑafter ˑ10 ˑwet ˑand ˑdry ˑcycles ˑ [51][52][53][54][55][56].…”

“…In ˑgold ˑmine ˑtailings-based ˑgeopolymers, ˑthe ˑimmobilization ˑefficiency ˑof ˑheavy ˑmetals ˑis ˑhigher ˑin ˑPA ˑand ˑKOH ˑactivated ˑgold ˑmine ˑtailings ˑgeopolymers ˑthan ˑin those synthesized by PS and KOH [50]. Kiventerä, et al [96], Kiventerä, et al [97] ˑalso ˑreported ˑeffective ˑimmobilization ˑof ˑsulfate ˑand ˑarsenic ˑin ˑgold ˑmine ˑtailings-based ˑgeopolymer ˑusing calcium hydroxide and ˑslag.…”