Search Results (3)

In this study, the ball milling method was used to produce superfine green tea powder (SGTP). We used the contents of chlorophyll, caffeine, tea polyphenols, and total free amino acids as indicators and combined the analytic hierarchy process (AHP) and fuzzy comprehensive evaluation to establish an AHP–fuzzy comprehensive evaluation approach applicable to SGTP. The production process of SGTP was optimized using the response surface methodology (RSM). The results showed that the three factors of grinding time, rotation speed, and ball-to-material ratio had significant effects on the content of the main components of the tea powder, and the order of the effects was as follows: ball-to-material ratio > grinding time > rotation speed. The optimal grinding time, rotation speed, and ball-to-material ratio for the preparation of SGTP were 5.85 h, 397 r/min, and 9.2:1, respectively. We also found that, compared with green tea powder made with the traditional crushing method, the SGTP prepared under these conditions possessed strong advantages in terms of particle size, the content and dissolution of major components, and antioxidant capacity. In this study, the optimization of the production process of tea powder is initially discussed, and then, a new evaluation method for tea powder is proposed, providing technical support for improving the quality of green tea powder. The AHP–fuzzy comprehensive evaluation approach, by quantifying qualitative assessments, significantly refined our optimization process, enabling a more precise determination of optimal SGTP production parameters. Full article

To reduce the structural deterioration of mass concrete structures from temperature cracks, and lower energy consumption caused by the traditional mass concrete hydration heat cooling process, this paper reports the preparation of concrete temperature-controlled phase change aggregate (PCA) by a vacuum compaction method using light and high-strength black ceramite and No. 58 fully refined paraffin wax as phase change material (PCM), and the encapsulation technology of the aggregate by using superfine cement and epoxy resin. Further, through laboratory tests, the cylinder compressive strength, thermal stability and mixing breakage rate of the encapsulated PCA were tested, and the differences in mechanical properties such as compressive strength, flexural strength and splitting tensile strength between phase change aggregate concrete (PCAC) and ordinary concrete were studied. A test method was designed to test the heat storage effect of PCA, and the temperature control effect of PCAC was analyzed based on the law of conservation of energy. The research conclusions are as follows: (1) Both superfine cement and epoxy resin shells increase the strength of the aggregate, with the epoxy resin increasing it more than the superfine cement. The thermal stabilization of the PCA is good after encapsulation of superfine cement and epoxy resin. However, PCA encapsulated in superfine cement is more easily crushed than that encapsulated in epoxy resin. (2) Under the condition of water bath heating and semi-insulation, when the water bath temperature reaches 85 °C, the temperature difference between the PCA and the common stone aggregate can be up to 6 °C. Based on the law of energy conservation, the test results will be converted to mass concrete with the same volume of aggregate mixture;, the difference of PCAC and ordinary concrete temperature can be up to 10 °C, so the temperature control effect is significant. (3) The mechanical properties of PCAC with 100% aggregate replacement rate compared to ordinary concrete are reduced to varying degrees, and the performance decline of the epoxy-encapsulated PCA is smaller than that encapsulated with superfine cement; in an actual project, it is possible to improve the concrete grade to make up for this defect. Full article

In our previous studies, we demonstrated the performance of novel superfine crusher and pneumatic planar magnetic separator as energy-efficient technologies for dry processing of magnetite ores. The present study investigates the economic and socio-environmental benefits of applying these technologies in conceptual dry magnetite ore processing flowsheet. The outcome of the study is compared with that of a conceptual wet processing flowsheet for the same ore. The cost estimations used are based on the Brook Hunt C1 methodology whilst revenue estimations are based on the Platts Iron Ore Index specification. The demonstrated economic and socio-environmental benefits show that dry processing flowsheet offers significant energy and cost savings and improved revenue generation compared with the wet process flowsheet. These findings are vital to the magnetite industry, particularly in water- and energy-scarce regions as a benchmark for future studies aimed at deepening and expanding the knowledge base of dry beneficiation of magnetite ores. Full article