High efficiency slime water settlement is very important for ensuring washing water recycling in coal preparation plants. In order to improve the sedimentation of coal slime water, an iron ion-based coagulant was prepared by titanium ion complexation action using titanium sulfate as a main raw material, Fe³⁺ and NaH₂PO₃ as a stabilizer and NaHCO₃ as an alkalizing agent. The particle size distribution of coal slime was measured, and the sedimentation test for coal slime water was carried out with PAM, polyaluminum chloride and polymerized titanium ferric sulfate (PTFS), respectively. Then, coal slime water sedimentation was investigated at different PAM dosages and polyaluminum chloride or coal slime water of PTFS with various molar ratios of PAM and ferrotitanium. The results showed that PAM and polyaluminum chloride could not make coal slime settle down, and PTFS showed a poor settlement effect. When polyaluminum chloride and PTFS were used together with PAM, it produced a molecular weight of 3 million respectively. Polyaluminum chloride needs 6.66 × 10⁻¹⁰ mol of PAM, PTFS needs 0.66 × 10⁻¹⁰ mol of PAM and the effect of sedimentation is improved. When the molar ratio of PTFS was 1:7, polymerization performance was effective. The sedimentation effect of PTFS was better than that of polymeric aluminum chloride coagulant usually used in coal preparation plants, especially when combined with flocculant, and high efficiency was reached. The surface potential and surface free energy of coal slime particles before and after adding coagulant were measured and analyzed by XDLVO theory to explain the action mechanism of PTFS coagulant. Experimental results demonstrated that PTFS can significantly improve the sedimentation of coal slime water, save the dosage of PAM and increase economic benefit.

The copper oxide ore in Zambia exhibits complex mineralogical characteristics, with copper primarily occurring in mica. The local hydrometallurgical plant employs heating–agitation acid leaching, which is hindered by a low leaching rate and prolonged leaching period, resulting in high energy consumption. To enhance the copper leaching efficiency, a systematic study was conducted on the use of organic cationic surfactants to enhance the leaching of the copper oxide ore. The results indicated that the primary copper-bearing mineral in the raw ore is cupriferous biotite, which is the reason for the difficulty in leaching. Under optimal conditions: a sulfuric acid dosage of 45 kg/t, a CTAB dosage of 75 g/t, a leaching temperature of 65 °C, a liquid-to-solid ratio of 2:1, and a leaching time of 120 min, the copper leaching rate reached 78.32%. Compared to the optimal result of regular heating–agitation acid leaching, this approach increased the copper leaching rate by 3.06%, reduced the leaching time by 80 min, and lowered leaching energy consumption without destroying the structure of cupriferous biotite. Mechanistic studies show that organic cations in CTAB neutralize excess anions, thereby weakening the electrostatic Coulomb forces between the interlayer cations and the hexagonal structure. This increases the interlayer spacing of biotite, facilitating the entry of H⁺ from sulfuric acid into the interlayer. The H⁺ then reacts with the copper in the biotite, enhancing the copper leaching rate and reducing leaching time. Because CTAB has high degradability, it will not cause persistent pollution to the environment. The use of CTAB as a leaching aid can reduce the energy consumption of heating–agitation acid leaching and reduce the heating cost per ton of ore by USD 6.11–9.36.