Preparation and characterization of polyaluminum titanium chloride (PATC) and its performance in the treatment of coal slime water

Efficient sedimentation of coal slime water (CSW) is essential for the recycling of washing water in coal preparation plants. Polyaluminum titanium chloride (PATC) was synthesized from AlCl3·6H2O and TiCl4. Coagulation experiments showed that the optimal preparation conditions for PATC were a Ti/Al molar ratio of 1:5 and a basicity (B value) of 0.4. Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis indicated that PATC was an Al-Ti polymer composed of titanium and aluminum, with the formation of Ti-O-Al bonds and bridging by hydroxyl groups. For CSW with a mass concentration of 40 g/L, PATC alone requires a lower dosage and exhibits better coagulation performance when used alone. When combined with cationic polyacrylamide (CPAM), PATC reduces the CPAM consumption by 25% compared with polyaluminum chloride (PAC), AlCl3, and CaCl2. After PATC addition, the overall Turbiscan Stability Index (TSI) of the CSW system reached 21.4, which was 2.12, 3.51, and 26.75 times higher than those of PAC, AlCl3, and CaCl2, respectively. Under the action of PATC, the absolute zeta potential of the coal slime particles was reduced to 5.9 mV. The resulting flocs exhibited large particle sizes and compact structures, leading to excellent sedimentation performance.