Dust control performance enhancement of red sand via the synergistic application of Na- and Ca-lignosulfonates

Dust emission from bauxite residue (red sand) is of great concern for its dramatic occupational and environmental detriments. The utilization of lignin-based stabilizers can effectively mitigate this issue. However, few studies analyzed the effect of two lignosulfonates combination on red sand dust control. Thus, this paper investigated the relationship between crust properties and dust control performance via the synergistic application of sodium (LS-S) and calcium lignosulfonate (LS-C). Results illustrated that the synergistic application of lignosulfonates enhances the dust erosion resistance of red sand more effectively than individual application. The improvement in LS mixtures on crust thickness, unconfined compressive strength and penetration resistance is 20.45% to 145.74%, 34.91% to 123.51% and 236.10% to 522.90%, respectively, compared with individual application. The crust longevity of LS mixtures is also increased by 26.12% to 100.08%. The optimum mix ratio to achieve the best dust control performance is in accordance with the unconfined compressive strength and penetration resistance. “LS-S: LS-C = 1:3” resulted in thickest crust while “LS-S: LS-C = 2:2” achieved the best moisture retention capacity. The crust failure time of “LS-S: LS-C = 3:1” is 8.26 times longer than the control group and 1.28 to 1.52 times longer than the individual application. Penetration resistance of formed crust is more competitive in predicting the dust control performance of LS for its higher average coefficient of determination of 0.982. According to this optimized model, the maximum crust protective period 1271.35 s could be achieved by LS mixture with 70.7% LS-S at 10% concentration.