Effect of Synergistic Aging on Bauxite Residue Dust Reduction Performance via the Application of Colloids, an Orthogonal Design-Based Study.

The application of polymer colloids is a promising approach for bauxite residue dust pollution control. However, due to the existence of synergistic aging, the efficiency of colloid dynamic viscosity to predict the dust control performance of bauxite residue is unclear. Previous studies were also rarely performed under synergistic aging conditions. Thus, this paper investigates the relationship between colloids' viscosity and dust control performance under synergistic aging modes. Results illustrated that the binary colloid achieved better dust control performance than unitary colloid for their higher viscosity and penetration resistance. For both unitary and binary colloid, higher viscosity results in better crust strength. A logarithmic relationship was found for viscosity and dust erosion resistance under unitary aging. However, Only the dynamic viscosity of colloids in solid-liquid two-phase conditions, rather than dissolved in deionized water, can effectively predict the dust control performance under synergistic aging conditions.

Characterization of red sand dust pollution control performance via static and dynamic laboratorial experiments when applying polymer stabilizers.

Red sand dust pollution is of great concern for its occupational and environmental detriments. The current remediation technique includes water spray and non-traditional stabilization via the application of polymer stabilizers. The dust erosion resistance plays a significant role in quantifying the effectiveness of red sand dust suppression. The aim of this paper is to evaluate the reliability and accuracy of five static and dynamic laboratorial methods that are commonly utilized to quantify the dust erosion resistance in the presence of polymers in previous studies, which are wind tunnel simulation, dynamic viscosity test, crust thickness test, penetration resistance test, and unconfined compressive strength test. The advantages and shortcomings of these methods were comprehensively demonstrated. The results illustrated that the penetration resistance test is the most reliable method in terms of the highest accuracy and relatively simpler operation. It also reveals excellent universality for effectively quantifying the dust erosion resistance of red sand with different particle sizes and for different polymers with various concentrations, while the rest of the methods failed to identify. The application of polymers contributes to improved dust erosion resistance for longer crust failure time, higher solution dynamic viscosity and crust penetration resistance, and higher unconfined compressive strength of rending sand samples. PAM outperformed guar gum and xanthan gum on the base of polymer ionicity and molecular weight. This study offers a better understanding in guiding the selection of optimum evaluation methods and polymers for the study of bauxite residue dust control.

Effect of synthetic and natural polymers on reducing bauxite residue dust pollution.

Dust emission from the bauxite residue drying areas is of great concern for its serious environmental and health impacts. The application of polymer stabilizers is a promising approach to mitigate such issues. However, limited studies have been done on their application on red sand and the investigation of the effect of polymers on penetration resistance, which is a key mechanical property closely related to the dust control performance. Stabilizers reduce the dust emission potential by forming a crust on the surface of treated material. This paper investigates the relationship of crust properties and dust control performance by applying synthetic (polyacrylamide) and natural (xanthan gum and guar gum) polymers. Results illustrated that the water retention property of treated sand is greatly improved after the application of stabilizers. The thickness of the formed crust decreases with stabilizer concentration. Results from wind tunnel simulation illustrated that the polymer stabilizer offers nearly 8 times longer protective period than water when used as a stabilizing agent. Cationic PAM performed the best, and cationic guar gum outperformed anionic xanthan gum. The penetration resistance is proved in this study to be a primary index for predicting dust control performance of polymer stabilizers.

Research and application of non-traditional chemical stabilizers on bauxite residue (red sand) dust control, a review.

Bauxite residue is a by-product of aluminium processing. It is usually stored in large-scale residue drying area (RDA). The bauxite residue is highly alkaline and contains a large percentage of metal oxides which are hazardous to the environment and human health. Therefore, the generated dust is a major environmental concern that needs to be addressed and efficiently managed. One of the major dust generation sources is from the coarse fraction of the bauxite residue named red sand. To minimize the environmental and health impacts, non-traditional chemical stabilizers can be applied to construct a binding surface crust with certain hardness and strength. Dust emission is reduced due to the increased moisture retention capacity and strong cohesion between sand particles. There are limited number of refereed publications that discuss the application of this method to alleviate dust generation from red sand. By critically reviewing the literature and the application of non-traditional chemical stabilizers to sand-like materials in other fields, this paper introduces some non-traditional chemical stabilizers that can be potentially used for controlling red sand dust. Commonly used evaluation methods in various studies are compared and summarized; the stabilization mechanisms are examined; and the performance of three types of stabilizers are compared and evaluated. This review potentially serves as a reference and guide for further studies in red sand dust control. The findings are especially useful for developing suitable quantitative methods for evaluating the dust suppression efficiency of soil stabilizers, and for determining the appropriate additive quantities that achieve both economic and performance effectiveness.