Experimental and molecular dynamics simulation investigation on the CaO-based gelling process of waste MgCl 2 -riched brine

The alkaline gelling backfilling technique is an important potential method for processing the brine tailings in the salt ore potash industry. It involves complicated reactions and products, which have direct influences on the backfilling process. In this study, the gelling material of the potash tailings was experimentally determined to be a 318-phase crystal structure and a corresponding molecular dynamics model was developed. The effect of proportion and crystal cluster size on the properties of paste was theoretically predicted based on the Compass II force field. The qualitative and quantitative comparison with the experimental results indicates that the model can reproduce the properties of the gelling process reasonably. Besides, the molecular diffusion, hydrogen bond network and interaction were clarified further based on the calculation results. The result indicates that the number of Mg2+ has a significant effect on the molecular diffusion of the system. The interaction energy between short-chain clusters and the other components is smaller than the energy between long-chain clusters and the other components so that the long-chain clusters can be more stable than the short-chain structures. The related results are expected to provide support for the development of low-cost gelling reagents and optimisation of the gelling backfill process.