Status and prospects of research on the rheology of paste backfill using unclassified tailings (Part 2): rheological measurement and prospects

Cemented paste backfill (CPB) technology is a significant approach for the development of green mining in metal mines and can provide safe, environmentally friendly, and efficient technical support for deep underground mining. As the theoretical basis of paste backfill, the rheological concepts, characteristics, and models of paste had been systematically reviewed, and the rheological measurement methods were analyzed herein. Rheological measurement enables the quantitative characterization of the rheological behavior of paste, and on this basis, a series of studies, such as the rheological constitutive equations of paste, evaluation of the influence of both internal and external factors on paste rheology, and quality control of CPB, was conducted. Generally, the rheology of paste is influenced by certain constituents, including solids concentration, particle size distribution, density, and cement hydration, and various external conditions, such as shear stress and temperature. The rheological properties of paste differ significantly, and currently, a unified method is not yet available for the rheological measurement of paste. Hence, comprehensive knowledge of rheological measurement is essential to achieve a better combination of rheology and CPB engineering, particularly in consideration of the specific physical and chemical properties of tailings and the common practice in the mining field. Therefore, the principles and applications of commonly used approaches, including the vane rheometer, slump cone, L-shaped tube, inclined pipe, and loop facility, were summarized, with emphasis on the measurement of yield stress because of its influence on the paste, that is, a non-Newtonian fluid. Furthermore, the applicability of the aforementioned measurement methods was comprehensively discussed. Given that rheological measurement has a profound effect on the development of paste rheology theory and paste backfill technology, the key problems were discussed by emphasizing the importance of the establishment of rheological measurement standards and the application of rheological measurement to paste backfill processes in real time. The development trend of research on paste rheology was also explored.