A comparison between fly ash- and basic oxygen furnace slag-modified gold mine tailings geopolymers

Abstract

Fly ash (FA) and Basic oxygen furnace (BOF) slag were used to as additives in the geopolymerisation of gold mine tailings (GMT).The aim of the research was to determine the effects of the two additives on the strength formation and mechanism of metal immobilisation by modified GMT geopolymers. GMT, FA and BOF were mixed, respectively, and made into a paste with the addition of potassium hydroxide (KOH) before curing at various conditions. 50% replacement of GMT in the starting materials gave the highest unconfined compressive strength (UCS). The UCS for BOF-based geopolymer was 21.44 Mega Pascals (MPa), whilst the one for FA-based geopolymer was 12.98 MPa. The BOF-based geopolymer cured at lower temperature (70 °C) as compared to the FA-based geopolymer (90 °C). The optimum KOH concentration was 10 and 15 M for BOF-and FA-based geopolymers, respectively. BOF-based geopolymers resulted in the formation of calcium silicate hydrate (CSH) phases which contributed to higher strength; whereas in FA-based geopolymers, no new structures were formed. BOF-based geopolymers resulted in over 94% iron (Fe) immobilisation, whereas FA-based geopolymers had 76% Fe immobilisation. Fe immobilisation was via incorporation into the CSH or geopolymer structure, whilst other metal immobilisations were thought to be via encapsulation. 12-month static leaching tests showed that the synthesised geopolymers posed insignificant environmental pollution threat for long-term use.

An Experimental Investigation on the Fill Properties of Industrial By-Products Generated in Turkey

“…Çelik cürufunun şişmesini azaltmak için kullanılabilecek bir başka yöntem de, çelik cürufunu başka malzemelerle karıştırarak yeni geo-malzemeler üretmektir [47,48]. Literatürdeki çalışmalarda çelik cürufu karışımlarında kullanılabilecek malzemeler içinde uçucu kül öne çıkmaktadır [49][50]. Yildirim ve Prezzi (2015), uzun süreli şişme deney sonuçlarına dayanarak sıkıştırılmış BOF çelik cürufu-%10 uçucu kül karışımı örneklerine ait genleşme yüzdelerinin sıkıştırılmış sade çelik cürufu ile kıyaslandığında çok daha düşük ve önemsiz seviyelerde olduğunu göstermiştir [30].…”

Mine tailings-based geopolymers: Mechanical and physical properties

“…ˑFor ˑthis ˑreason, ˑmetakaolin ˑis ˑthe ˑmost frequently ˑutilized ˑas a supplementary source ˑof ˑAl ˑin ˑthe ˑchemical ˑindustry ˑ [28,[91][92][93][94][95][96][97] ˑbecause ˑof ˑthe ˑuniformity ˑand ˑpurity ˑof ˑits ˑcomposition, as well as its high interaction [28,76,[80][81][82][88][89][90]. Falayi [98] has indicated ˑthat ˑfly ˑash ˑand ˑblast ˑfurnace ˑslag ˑ(BFS) ˑare ˑemployed ˑa ˑbit ˑless ˑfrequently ˑthan ˑother ˑsubstances. It has been reported that volcanic glass and waste glass have been utilized, ˑas ˑwell ˑas ˑaluminum ˑoxide ˑand ˑaluminum ˑsludge, ˑcalcined ˑhalloysite, ˑand ˑlow-calcium ˑslag ˑ [25,99].…”

Alkaline Activation of Basic Oxygen Furnace Slag Modified Gold Mine Tailings for Building Material

“…e temperature of 90°C was the optimum temperature that yielded the highest UCS. Advances in Civil Engineering UCS after the optimum strength was attained which is attributed to free Ca 2+ ions as the dissolution of CaO [48].…”