Comparison of Phosphogypsum-Steel Slag-Based cement and Portland cement for stabilization of heavy metals in oil-based drillings cuttings

Abstract

This research compared Portland cement and Phosphogypsum-Steel Slag-Based (PSSB) cement in terms of their capabilities to stabilize heavy metals (specifically lead and nickel) in Oil-Based Drill Cuttings (OBDC). In the experimental section, the qualitative analysis of heavy metal constituents in OBDC was captured by X-ray Photoelectron Spectroscopy (XPS). Additionally, an acetic acid leaching test was implemented for the heavy metal leaching concentration to evaluate the ceramsite stabilization effect on OBDC. In the simulation phase, cement models, heavy metal ion models, and stabilization models were constructed to explore the stabilization mechanism of heavy metals. Results demonstrated that PSSB cement exhibits superior stabilization effects on OBDC compared to Portland cement. Flame Atomic Absorption Spectrophotometry (FAAS) tests showed that PSSB cement reduced Ni and Pb leaching by 21.87 % and 47.32 %, respectively, compared to Portland cement. In PSSB cement, the diffusion coefficients for Ni and Pb ions were observed to decrease by 42.92 % and 79.63 %, respectively, as revealed through Mean Square Displacement (MSD) analysis. The cohesive energy of PSSB cement was 76.73 % lower than that of Portland cement, and its interaction energies for stabilizing Ni and Pb ions were 59.43 % and 76.22 % lower, respectively, demonstrating greater stability and efficiency in metal stabilization. PSSB cement exhibited lower heavy metal concentration and better structural stability than Portland cement.