Transient and Steady-State Gas Lift Transportation of Non-Newtonian Rare Earth Slurry: A Water–Gas–Slurry Modeling Study

Gas lift transportation of deep-sea rare earth mud involves the replacement of initial water by a non-Newtonian suspension and substantial axial variation in gas content along a long riser. This study develops a one-dimensional drift flux formulation that distinguishes the initial internal water from the incoming power law slurry through liquid volume accounting and material property assignment. Gas compressibility, relative phase motion, and wall resistance are included. The staggered grid finite-volume solver is assessed through outlet scalar resolution comparisons, single-phase power law verification, and published air–water discharge experiments. The pooled discharge MARD is 5.79% for the air–water cases; the non-Newtonian slurry-lifting cases are model predictions without direct experimental validation. In a 6000 m riser, comparison of two liquid property treatments illustrates the sensitivity of the predicted start-up and late-time gas-holdup distributions. Increasing slurry concentration from 2% to 10% reduces volumetric throughput from approximately 0.750 to 0.651 m3/s and increases frictional pressure loss from approximately 0.257 to 0.899 MPa. Greater injection depth and gas mass flow increase throughput with diminishing incremental gains. The 3000 m and 8 kg/s cases achieve approximately 94.7% and 95.1% of their respective series reference throughputs. A separate outlet diagnostic retains homogeneous Mach indicators above unity at the outlet and final interior center and distinguishes these from the coupled drift flux characteristics. The results quantify the hydraulic effects of slurry rheology and gas supply while distinguishing bulk transport trends from the terminal outlet response.