This study focuses on the effect of an emerging source of waste, lithium iron phosphate (LFP) cathode materials, on the hydrometallurgical recycling of the currently dominant industrial battery waste that is rich in transition metals (Ni, Co, Mn, and Li). The effects of the dosage of LFP, initial acidity, and timing of LFP reductant addition were investigated in sulfuric acid (H₂SO₄) leaching (t = 3 h, T = 60 °C, ω = 300 rpm). The results showed that addition of LFP increased both transition metal extraction and acid consumption. Further, the redox potential was lowered due to the increased presence of Fe²⁺. An initial acidity of 2.0 mol/L H₂SO₄ with acid consumption of 1.3 kg H₂SO₄/kg black mass provided optimal conditions for achieving a high leaching yield (Co = 100%, Ni = 87.6%, Mn = 91.1%, Li = 100%) and creating process solutions (Co 8.8 g/L, Ni 13.8 g/L, Li 6.7 g/L, Mn 7.6 g/L, P 12.1 g/L) favorable for subsequent hydrometallurgical processing. Additionally, the overall efficiency of H₂O₂ decreased due to its decomposition by high concentrations of Fe²⁺ and Mn²⁺ when H₂O₂ was added after t = 2 h, leading to only a minor increase in final battery metals extraction levels.

Boron carbide (B₄C) holds significant application potential in the fields of lightweight, high-hardness protective and high-end wear-resistant components due to its low density and exceptional hardness. However, its strong covalent bonding leads to low sintering activity and weak grain-boundary cohesion, resulting in high brittleness and crack sensitivity. These inherent properties make it difficult to achieve simultaneous full densification and toughness enhancement, severely limiting the reliability of B₄C under complex service conditions. Although diamond is an attractive reinforcement because of its high elastic modulus and low coefficient of thermal expansion, the simultaneous realization of densification, graphitization suppression, and fracture-resistance improvement in diamond/B₄C composites remains insufficiently understood. In this study, diamond particles were introduced into the B₄C matrix and consolidated by rapid high-temperature and high-pressure (HTHP) sintering to synergistically promote densification and fracture toughening. The effects of sintering temperature and diamond content on phase evolution, densification, microstructure, and mechanical properties were systematically investigated, and the associated toughening mechanisms were analyzed. The results indicate that the hardness generally increases with rising sintering temperature and diamond content. The primary toughening mechanisms are identified as the pull-out of diamond particles and crack deflection induced by residual stresses generated during the cooling process. Although the composite with 20 wt.% diamond exhibits higher hardness, it also experiences severe macroscopic cracking. The composite with 10 wt.% diamond sintered at 1450 °C under 5.3 GPa for 4 min exhibits the optimal balance of properties, achieving a relative density of 98.85%, a Vickers hardness of 40.72 GPa, and a fracture toughness of 9.20 MPa·m^1/2. This work confirms the effectiveness of combining diamond reinforcement with HTHP sintering in simultaneously achieving densification and toughening of B₄C-based composites, providing a new pathway for developing high-performance lightweight protective ceramics.

The demand for metallic nickel has been growing steadily. Laterite nickel ore, as an oxide mineral, contains a higher nickel content than sulfide ores, enabling more economical smelting in the nickel extraction process. However, an extremely thick slag layer generated during side-blown smelting of laterite nickel ore alters the bath circulation characteristic of conventional smelting processes. To address this, this study employs a validated Multi-Fluid VOF model to analyze the flow field characteristics of the side-blown furnace bath under varying slag layer thicknesses. Within the slag thickness range of 1.5–2.5 m, the ascending air plume shifts horizontally along the furnace wall with increasing slag thickness, entraining matte into the slag and promoting its diffusion toward the settling zone. Matte diffusion is governed by bath circulation: backflow from the settling zone dominates at lower slag thickness, while vertical kinetic energy from splashed melt reflux dominates at higher thickness. This reflux-induced circulation is blocked by the dense matte layer, causing no disturbance to the bottom matte and thus favoring slag–matte separation. Increasing slag thickness raises the near-wall circulation zone and plume entry point, reducing gas holdup near the tuyere and weakening oxygen–matte contact.