Comparison of static tests and dynamic tests for coal dust surfactants evaluation: A review

Coal workers' pneumoconiosis is one of the most severe occupational diseases due to long-term exposure to high concentrations of coal dust. Water spray with surfactant addition is an effective and commonly used method to control the coal dust in coal mines. Usually, the surfactant evaluation methods can be divided into two categories, including static and dynamic tests. The performance of surfactants may vary with different evaluation methods, which make the results hard to conclude. By critically reviewing previous studies, this paper highlighted the four surfactants' evaluating methods for coal dust suppression, including the surface tension test, the sink test, the field test, and the wind tunnel test. Firstly, the basics of four evaluating methods were described, and the general result was concluded and presented. Secondly, static and dynamic tests were compared to reveal the consistency and discrepancy. It was found that the surface tension test takes dominations at lower concentrations of surfactants, while it cannot further take advantage after a critical concentration. The anionic and nonionic surfactants showed better performance than cationic surfactants mostly in static tests. The field test and the wind tunnel test can directly evaluate the suppression efficiency of surfactants, with consideration of environmental factors such as the particle collision and the contact time. This paper is important for producing comparable results between static and dynamic tests and revealing the consistency and discrepancy. The outcomes of this study could be a guidance for evaluating and selecting the optimum surfactants for coal dust suppression.

Automated summary

This study summarized four surfactants' evaluating methods for coal dust suppression, compared the consistency and discrepancy between static and dynamic test results, and found that the efficacy of surface tension testing can vary under different conditions.