Li, D, Liu, B, He, J, Li, X & Jian, M 2017, 'Strength and transportability of cemented phosphogypsum paste backfilling slurry', in A Wu & R Jewell (eds), Paste 2017: Proceedings of the 20th International Seminar on Paste and Thickened Tailings, University of Science and Technology Beijing, Beijing, pp. 328-336, https://doi.org/10.36487/ACG_rep/1752_36_Li (https://papers.acg.uwa.edu.au/p/1752_36_Li/) Abstract: In order to investigate the strength of cemented phosphogypsum (PG) backfill, a batch of PG backfilling slurry with different concentrations were tested at different curing times. Furthermore, a full-scale pipe test loop system was also established to investigate the pressure drop of the paste slurry with varied slurry concentrations and mix proportions flowing through the pipes. The test results showed that the compressive strength of the cemented PG backfill specimens was influenced by the ratio of the cementitious material to PG, the slurry concentration and the curing time. For example, under 28 days of curing time, the compressive strength of the cemented PG backfill specimens with the slurry concentration of 68wt%, mixed with the ratio of cementitious material to PG being 1:2, can reach 3.4 MPa. Based on the pipe test loop system, the fitting calculation formulas for the pressure drop of cemented PG paste backfill slurry (CPPB) with two ratios of cementitious materials to PG (1:4 and 1:5) flowing in horizontal straight pipes have been put forward. A field test was also conducted that proved the reliability of the fitting calculation formula.