Drying kinetics and energy efficiency of soot ash of smelting silicon manganese alloys under microwave heating.

When smelting silicon manganese alloy in an industrial electric furnace, it will produce smoke and dust waste gas, which can be utilized again back to the furnace and improve the utilization rate of raw materials after a particular trapping device and collection treatment. However, at higher moisture levels, they are prone to explode. Effects of various initial masses, initial moisture contents, and microwave output powers on the soot ash of smelting silicon manganese alloy were studies. The findings indicate that the microwave drying rate increases with all three variables. The time for complete microwave drying is directly proportional to the sample's initial moisture content and the sample's initial mass, and the time for complete microwave drying is inversely proportional to the microwave output power. The results demonstrate that the Modified Page model can accurately describe the microwave drying process. The experimental data were fitted experimentally by drying kinetic models. Microscopic characterization of soot ash from refining silico­manganese alloys before and after drying was carried out using FTIR and SEM. Through FTIR characterization, the peak value of the -OH absorption peak decreases upon drying, and SEM results in no agglomeration caused by microwave drying and better dispersion of the soot ash of the dried smelted silica­manganese alloys, all of which proved that microwaves could effectively remove water. It was discovered that the diffusion coefficient increased gradually with increasing power when it was computed using Fick's second law. The diffusion coefficient increases and then decreases as the moisture content increases. The diffusion coefficient decreases as the initial mass increases. Activation energy of microwave drying of soot ash from the refining of silicomanganese alloys was calculated to be -1.4467 W/g. Its purpose is to offer a detailed guide for the industrial drying of soot ash from silicomanganese alloy refinement using microwave drying technology.

Effect of different types of Tai Chi exercise programs on the rate of change in bone mineral density in middle-aged adults at risk of osteoporosis: a randomized controlled trial.

OBJECTIVE: To evaluate three Tai Chi (TC) exercise programs as intervention measures to compare their effects on improving rate of change in bone mineral density (BMD) in elderly individuals with osteoporosis (OP) and to propose the optimal exercise duration. METHODS: A randomized controlled trial (RCT) was conducted to identify study participants based on inclusion and exclusion criteria. Due to subject attrition, the number of participants analyzed decreased from 60 to 49. These participants were divided into four groups: 24-style TC Chuan group (24TCCG) (n = 13, 7 males/6 females), TC Kung Fu Fan group (TCKFFG) (n = 12, 5 males/7 females), TC Softball group (TCSBG) (n = 11, 6 males/5 females), and a control group (CG) (n = 13, 6 males/7 females). Except for the control group, each group received different TC exercise programs four times a week for 60 min per session, lasting for 16 weeks. BMD was measured using dual-energy X-ray absorptiometry (DXA) at the L2-L4 lumbar vertebrae, Ward's triangle, femoral neck, and greater trochanter. The rate of change of BMD was calculated using the formula. RESULTS: Compared with CG, all three TC groups showed significant improvements in BMD changes (P < 0.05), but their effects on the improvement of femoral neck and greater tuberosity BMD change rates were similar (P > 0.05). In addition, compared to the other exercise regimens, 24TCCG demonstrated more significant improvements in BMD at the L2-L4 lumbar vertebrae region and exhibited a more pronounced improvement in Ward's triangle BMD after only 8 weeks (P < 0.05). Short-term (≤ 4 weeks) TCKFFG was more effective than TCSBG in enhancing femoral neck BMD (P < 0.05). However, statistical significance was not found (P > 0.05) in all other cases. CONCLUSION: These three TC exercise programs have similar positive effects on the BMD of the femoral neck and greater trochanter. However, compared with other exercise schemes, 24TCC showed a more significant improvement in BMD of the L2-L4 lumbar vertebrae region after just 8 weeks, as well as a more pronounced improvement in BMD of Ward's triangle. In terms of improving femoral neck BMD, TCKFF was found to be more effective than TCSB in less than 4 weeks. This study provides evidence for the effectiveness of TC exercise in improving BMD and preventing OP in the middle-aged and elderly high-risk population.

Drying Kinetics of Microwave-Assisted Drying of Leaching Residues from Hydrometallurgy of Zinc.

In the hydrometallurgical process of zinc production, the residue from the leaching stage is an important intermediate product and is treated in a Waelz kiln to recover valuable metals. To ensure optimal results during the Waelz kiln process, it is necessary to pre-treat the residues by drying them first due to their higher water content. This work studies the residue's drying process using microwave technology. The study results indicate that microwave technology better removes the residue's oxygen functional groups and moisture. The dehydration process's effective diffusion coefficient increases as the microwave's heating power, the initial moisture content, and the initial mass increase. The Page model is appropriate for imitating the drying process, and the activation energy of the drying process for the residues is -13.11217 g/W. These results indicate that microwave technology efficiently dries the residues from the leaching stage. Furthermore, this study provides a theoretical basis and experimental data for the industrial application of microwave drying.