Abstract
This study demonstrates the feasibility of recycling lead–zinc tailing (LZT) as a cemented paste backfill (CPB) by considering the mechanical properties and environmental effects, thus providing an approach for safe and environmentally friendly treatment of LZT. First, the mechanical properties of CPB samples were tested. When the cement/tailing ratio was 1:6 and the slurry concentration was 70%, the maximum unconfined compressive strength (UCS) of the CPB cured for 28 days reaching 2.05 MPa, which could ensure safe mining. Then, the metals with pollution potential in the backfill slurry were investigated through static leaching. Finally, after adding immobilisation materials to stabilise excessive metals, the environmental stability of the CPB was demonstrated through dynamic leaching and a toxicity characteristic leaching procedure. The results show that the lead leached from the backfill slurry still exceeds the Chinese standard for groundwater quality (GB/T14848-2017 Class III). The addition of 2 mg/L polyaluminium sulfate (PAS) can further improve the strength of the CPB and maintain the environmental friendliness of the CPB. Therefore, the technology of recovering LZT as a CPB proposed in this study is an effective alternative to deal with LZT, which can help lead–zinc mines meet the requirements of cleaner production.
Highlights
Lead and zinc resources are abundant in China, and the total output of lead and zinc ranks first in the world
The cemented paste backfill (CPB) slurry was prepared on the ground and transported to the underground through the pipeline during the production process in the mine site
9% to 13% higher than the original unconfined compressive strength (UCS) value from Table 6, which may because aluminium sulfate about 9% to 13% higher than the original UCS value from Table 6, which may because aluminium accelerates the hydration of tricalcium silicate
Summary
Lead and zinc resources are abundant in China, and the total output of lead and zinc ranks first in the world. Lead has uses in new nuclear and petroleum industries. The current development of the lead and zinc industry faces a prominent bottleneck, which is the contradiction between the continuous mining of lead and zinc and the protection of the ecological environment [2]. Large-scale mining of lead and zinc will inevitably produce a large amount of tailing. In China, lead–zinc mines have more poor ores and fewer rich ores and are often associated with heavy metals, such as cadmium, nickel, and arsenic. Incompletely separated lead and zinc are left in the tailings [3]. These toxic heavy metals pose a great threat to the ecological environment
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