The cemented paste backfill (CPB) is defined as a manufactured material made up of dehydrated tailings from the mills, water, and hydraulic binder which fills the excavated mines (Du et al., 2024). In the case of a fast-growing underground mine, mining operations take place at a faster pace thus a constant and high need for ground support. It is crucial to size a proper paste backfill plant in such cases. An undersized plant means there will be no backfill leading to an operational constraint within the whole mine system.
The main criterion used to establish the sizing of the plant will be the mining rate at which ores are extracted from the mine site. This is because an operation that advances quickly needs to have a plant that has an output capacity capable of sustaining or surpassing the rate at which cavities are created within the mine (Pornillos, 2009). The designer will have to determine the maximum size of simultaneous open stopes and calculate the necessary speed of filling the cavities.
In addition to quantity of production, physical qualities of the tailings themselves and the specific formulation design used will greatly affect the plant sizing process. The amount of solid material and its rheology, which is sometimes determined by tailing mineralogical composition, establish the water-to-binder ratio to keep an optimal fluidity of the mass (Menasria et al., 2025). Moreover, the use of chemical additives such as superplasticizers can greatly change paste’s consistency and rate of hydration and strength development in the initial period of the process (Zhang et al., 2018).
Apart from these considerations, when designing the plant, the operators should take into account the appropriate process of either continuous or batch mixing for their mines’ advancement rates. In general, the former option tends to be preferable in case of quickly advancing mines since such systems are capable of delivering paste flows continuously in high volume, in contrast to batch systems that are highly regarded for their high-quality control standards (Pornillos, 2009). Whichever of these options the operators decide on, the plant should contain the appropriate buffer capacities in the form of large agitated holding tanks and additional larger cement silos in order not to interrupt the continuous pouring of large paste volumes.
Moreover, the capacity of a mining plant is ultimately limited by its underground reticulation system. Large volumes of paste created at the surface are useless if they are unable to be delivered via the underground pipeline system efficiently. Such characteristics as the rheology of the paste are extremely important here since although the higher viscosity of paste decreases the amount of water runoff and increases its compressive strength, it increases significantly the friction within pipelines (Al-Bakri et al., 2023).
To summarize, the sizing of the paste backfill plant with respect to a fast growing mine is a multidisciplinary problem. This is because it involves much more than simply ensuring that there is enough volume of the mined product available. The solution to the problem will involve taking into consideration both aggressive scheduling plans as well as challenging rheology and spatial constraints.
References
Al-Bakri, A. Y., Ahmed, H. M., & Hefni, M. A. (2023). Eco-Sustainable Recycling of Cement Kiln Dust (CKD) and Copper Tailings (CT) in the Cemented Paste Backfill. Sustainability, 15(4), 3229. https://doi.org/10.3390/su15043229
Du, Z., Chen, D., Li, X., Jian, Y., Zhang, W., Zhang, D., & Tian, Y. (2024). Study on the Partial Paste Backfill Mining Method in a Fully Mechanized Top-Coal Caving Face: Case Study from a Coal Mine, China. Sustainability, 16(11), 4393. https://doi.org/10.3390/su16114393
Menasria, H. G., Mbonimpa, M., Belem, T., & Maqsoud, A. (2025). Consistency and Rheological Properties of Cemented Paste Backfills Prepared with Tailings with Varying Free Muscovite Content. Mining, 5(1), 10. https://doi.org/10.3390/mining5010010
Pornillos, E. (2009). Paste Fill Plant Designs for Underground Mines — A Comparison of Batch Process and Continuous Process. Proceedings of the International Seminar on Paste and Thickened Tailings, 364–374. https://doi.org/10.36487/acg_repo/963_40
Zhang, J., Deng, H., Taheri, A., Deng, J., & Ke, B. (2018). Effects of Superplasticizer on the Hydration, Consistency, and Strength Development of Cemented Paste Backfill. Minerals, 8(9), 381. https://doi.org/10.3390/min8090381
