Air bearing has been widely applied in ultra-precision machine tools, aerospace and other fields. The restrictor of the porous material is the key component in air bearings, but its performance is limited by the machining accuracy. A combination of optimization design and material modification of the porous alumina ceramic membrane is proposed to improve performance within an air bearing. Porous alumina ceramics were prepared by adding a pore-forming agent and performing solid-phase sintering at 1600 °C for 3 h, using 95-Al₂O₃ as raw material and polystyrene microspheres with different particle sizes as the pore-forming agent. With 20 wt.% of PS50, the optimum porous alumina ceramic membranes achieved a density of 3.2 g/cm³, a porosity of 11.8% and a bending strength of 150.4 MPa. Then, the sintered samples were processed into restrictors with a diameter of 40 mm and a thickness of 5 mm. After the restrictors were bonded to aluminum shells for the air bearing, both experimental and simulation work was carried out to verify the designed air bearing. Simulation results showed that the load capacity increased from 94 N to 523 N when the porosity increased from 5% to 25% at a fixed gas supply pressure of 0.5 MPa and a fixed gas film thickness of 25 μm. When the gas film thickness and porosity were fixed at 100 μm and 11.8%, respectively, the load capacity increased from 8.6 N to 40.8 N with the gas supply pressure having been increased from 0.1 MPa to 0.5 MPa. Both experimental and simulation results successfully demonstrated the stability and effectiveness of the proposed method. The porosity is an important factor for improving the performance of an air bearing, and it can be optimized to enhance the bearing’s stability and load capacity.

Energy savings and consumption reduction of ball mills are crucial for industrial production. The grinding medium is an important component of a ball mill. In theory, using higher-density grinding media can yield better grinding results. However, for materials with varying grindability, employing grinding media of different densities can reduce energy consumption while maintaining the same grinding effect. This study simulates the motion of the grinding media in the mill using three different densities of balls and the same material (iron ore). The results reveal that balls with densities of 5.8 g/cm³ and 7.8 g/cm³ achieve faster grinding of materials into finer particles, but balls with a density of 5.8 g/cm³ consume less energy. Therefore, replacing a ball with a density of 5.8 g/cm³ in a ball mill can significantly reduce energy consumption. This study will assist in selecting the optimal grinding medium density for different materials, ultimately contributing to energy savings and reduced carbon emissions.

Cement is a widely used construction material, but its high temperature after milling can lead to issues such as gypsum dehydration, cement agglomeration, and increased slump, all of which negatively affect concrete performance. Existing cement heat exchangers have several limitations, such as low efficiency, high energy consumption, and strict processing precision requirements. This study introduces a novel layered-plate heat exchanger and analyzes its cooling performance using ANSYS Fluent 2024 R1 software. The results indicated that increasing the height of the cooling unit group significantly improved cooling efficiency from 7.83% at 1 m to 35.99% at 10 m. When the cooling unit group height was maintained constant, adding fins and increasing the cooling water flow rate were key methods to improve cooling efficiency. At a 10 m height, adopting 100 mm (F-1) and 200 mm (F-2) fin spacings and increasing the cooling water usage of over 90t/h can reduce the temperature of 130 °C cement powder to below 80 °C, with a cooling efficiency exceeding 38.47%. This study offers an effective method for lowering the temperature of freshly milled cement, providing theoretical support for cement manufacturers to effectively address the issue of high-temperature cement.