Lithium slag and fly ash-based binder for cemented fine tailings backfill

Area of Science:

• Materials Science
• Geotechnical Engineering
• Waste Management

Background:

• Cemented fine tailings backfill (CFTB) is crucial for underground mine stability.
• Traditional binders like ordinary Portland cement (OPC) have environmental and economic drawbacks.
• Recycling industrial byproducts like lithium slag (LS) and fly ash (FA) is an ongoing challenge.

Purpose of the Study:

• To investigate the feasibility of a novel binder composed of LS and FA for CFTB applications.
• To optimize the binder composition for maximum strength and performance.
• To evaluate the potential of this binder as a sustainable alternative to OPC.

Main Methods:

• Experimental preparation of binders with varying ratios of OPC, LS, and FA.
• Testing of unconfined compressive strength (UCS), micromorphology, and slump values of CFTB specimens.
• Analysis of binder performance at different curing ages (7, 28, and 56 days).

Main Results:

• An optimal binder ratio (OPC:LS:FA) of 2:1:1, termed LFB, was identified, yielding the highest strength.
• CFTB specimens with 10 wt% LFB achieved UCS values of 0.95 MPa (7 days), 2.28 MPa (28 days), and 3.37 MPa (56 days), exceeding mine requirements.
• LFB demonstrated effective pore-filling and pozzolanic activity, contributing to both early and long-term strength.
• LFB reduced slurry slump by 2.6%-9.4%, ensuring acceptable fluidity and reduced transportation resistance.

Conclusions:

• The developed LS and FA-based binder (LFB) is a viable alternative cementitious material for CFTB.
• LFB meets the required mechanical strength for supporting surrounding rock in mines.
• Utilizing LFB provides an economical and safe method for recycling LS and FA in underground mining operations.