Open Access

ARTICLE

Utilization of Low-Alkalinity Cementitious Materials in Cemented Paste Backfill of Gold Mine Tailings

Jiamao Li^1,2,*, Chuimin Zhang¹, Lin Li¹, Chuangang Fan^1,*, Zhaofang He³, Yuandi Qian³

1 School of Materials Science and Engineering, Anhui University of Technology, Maanshan, 243032, China
2 Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials, Ministry of Education, Maanshan, 243002, China
3 China MCC17 Group Co., Ltd., Maanshan, 243000, China

* Corresponding Authors: Jiamao Li. Email: ; Chuangang Fan. Email:

Journal of Renewable Materials 2022, 10(12), 3439-3458. https://doi.org/10.32604/jrm.2022.021214

Received 01 January 2022; Accepted 18 February 2022; Issue published 14 July 2022

Abstract

The purpose of this paper was to explore the possibility of using low-alkalinity cementitious materials as binders, in which ground blast furnace slag and fly ash acted as a partial replacement of ordinary Portland cement, and CaSO₄, Na₂SO₄, and CaO were used as a sulfate activator and alkali-activated additives, to solidify gold mine tailings for preparation of a green, inexpensive cemented paste backfill (CPB). For this target, the effects of cement/ tailings ratio, superplasticizer dosage, solid content, tailings fineness on the mechanical properties of the CPB were investigated. Additionally, the hydration mechanism of the CPB was analyzed based on X-ray diffraction and scanning electron microscopy results. The results showed that the fluidity of the CPB slurry could be improved by adding polycarboxylic acid superplasticizer. The unconfined compressive strength (UCS) of the CPB specimens was increased with the increase of cement/tailings ratio and solid content. Under the same experimental conditions, the 28 d UCS of the CPB specimens was 3.8~4.9 times higher than that of ordinary Portland cement. The softening coefficient of the CPB specimens was increased with the increasing cement/tailings ratio, ranging from 0.83 to 0.92. The shrinkage rate of the CPB specimens was decreased from 0.70% to 0.54% with the increase of cement/tailings ratio from 1:12 to 1:4. The UCS of the full tailings CPB was the highest, followed by the fine tailings CPB specimens, and the UCS of the coarse tailings CPB specimens was the lowest. The low-alkalinity binder was proved to be a promising material to improve the engineering performances of the CPB. The optimal mixing ratio is 1:6 cement/tailings ratio, 0.15 wt% superplasticizer dosage, and 70 wt% solid content. Prepared by this mixing ratio, the UCS values of the CPB after 3, 7, and 28 d curing ages reached 1.85, 5.87, and 9.16 MPa, respectively, which were suitable as CPB for the Zhaoyuan gold mine in terms of strength requirements.

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