Influence of time and temperature on rheology and flow performance of cemented paste backfill

The Cemented Paste Backfill (CPB) technology can provide effective solutions to mining-related environmental and safety problems, and access to achievement of green mining and deep mining. Rheological properties of paste are important factors that affecting the flow characteristics and pipeline resistance calculation. The rheology of fresh cemented paste is influenced by time and temperature typically in pipeline transportation and is in dynamic evolution. By analyzing the effect of time and temperature on paste rheology, a calculation model of the resistance was established, which was implemented with the numerical software, COMSOL Multiphysics, thus the distribution of the flow parameters was obtained. The results show that, with increase in shear time, the yield stress decreases negative exponentially and the plastic viscosity decreases linearly. The rheological parameters gradually become stable after a certain time. The yield stress declines with increase in temperature, and the process could be described with a negative exponential function. Meanwhile, the variation of plastic viscosity is linear and slight. It is concluded that the rheological behavior of paste has time-temperature equivalent effect, and the transformation equation of time-temperature effect was established. Combined with the Buckingham equation, a calculation model of pipeline resistance with time-temperature effect was proposed, implemented in the numerical software, and a new equation of conservation of momentum was established. In this paper, the changes in paste theological characteristics with shear rate, thixotropic time and temperature are clarified, and a calculation model of paste resistance considering the effects of time and temperature is established. Through three-dimensional simulation, the processes of velocity distribution of paste with time and temperature were displayed vividly. The mathematical model has been verified and is of guiding significance for pipeline transportation in paste backfill engineering. (C) 2019 Elsevier Ltd. All rights reserved.