Research on Resource Recovery and Disposal of Copper-Containing Sludge.

Copper-containing sludge is a common by-product of industrial activities, particularly electroplating and metal processing. This type of sludge contains high concentrations of heavy metals such as copper, which can pose a potential threat to the environment. Therefore, its treatment and disposal require special attention. Due to its efficient mass and heat transfer characteristics, the suspended state technology has shown significant potential for application in a number of key processes, including the drying, decomposition, and reduction of copper-containing sludge. This paper presents an in-depth analysis of the current status of the application of the suspended state technology in the treatment of copper-containing sludge. Based on this analysis, a device for the treatment of copper-containing sludge in the suspended state was designed, through which the characteristics of copper-containing sludge in the oxidative decomposition and reduction phases are investigated. The research objects were gas concentration, temperature, contact state, and particle size time. Orthogonal experiments were initially employed to investigate the relationship between the influencing factors and the conversion rate of copper oxides. This was followed by a single-factor influence study, which led to the determination of the optimal process parameters for the decomposition experiments of the Cu-containing sludge in an oxidizing atmosphere. The 100 µm Cu-containing sludge was reacted with 10% O2 gas at a flow rate of 1 m/s for 3 min under the condition of 900 °C. The process parameters were then determined as follows: The research objects were gas concentration, temperature, contact state, and particle size time. Orthogonal experiments were employed to investigate the relationship between the influencing factors and the copper conversion rate. This was followed by a single-factor influence study, which determined the optimal process parameters for the copper-containing sludge reduction experiments. The 200 µm copper-containing sludge was reacted for 5 min at a flow rate of 7% carbon monoxide at a flow rate of 1.5 m/s under the condition of 800 °C.

Preparation and Performance Study of SiC-Reinforced Fe-Based Wear-Resistant Composite Grinding Media.

During industrial and laboratory processes involving material grinding, the grinding media endure prolonged high-collision and friction environments, resulting in substantial wear. Consequently, this study adopts the hot-pressing sintering technique in powder metallurgy to prepare SiC-reinforced Fe-based wear-resistant composite grinding media, aiming to increase wear performance. For this purpose, Fe with 10 wt% SiC powders were milled for the fabrication of the composite. Then, sintering was performed by hot press at 1100 °C in a furnace. Scanning electron microscopy (SEM) and X-ray diffraction were employed to investigate the microstructures and phase of SiC-reinforced Fe-based matrix composite. Subsequently, comparative performance evaluations of the newly developed grinding media and traditional chromium-based media were conducted in terms of wear rate and grinding efficiency. The wear resistance tests revealed that the SiC-reinforced composite media displayed significantly superior wear resistance across various abrasives compared to the chromium-containing alternatives. Specifically, the composite media achieved a wear rate reduction of 2.9 times against standard sand over 1 h, and 2.3 and 2.4 times against sandstone and iron slag, respectively. Moreover, extended grinding for 3 hours further enhanced these reductions to 3.1, 2.4, and 2.7 times, respectively. Additionally, efficiency assessments indicated that at a 1:1 material ratio, the composite media outperformed the chromium-containing media in grinding efficiency by 7.5%, 12.5%, and 10.3% for standard sand, sandstone, and iron slag, respectively. Further increasing the material ratio to 3:1 resulted in efficiency improvements of 7.4%, 17.5%, and 11.3%, correspondingly.

Evaluation and Analysis of Cement Raw Meal Homogenization Characteristics Based on Simulated Equipment Models.

In recent years, the variability in the composition of cement raw materials has increasingly impacted the quality of cement products. However, there has been relatively little research on the homogenization effects of equipment in the cement production process. Existing studies mainly focus on the primary functions of equipment, such as the grinding efficiency of ball mills, the thermal decomposition in cyclone preheaters, and the thermal decomposition in rotary kilns. This study selected four typical pieces of equipment with significant homogenization functions for an in-depth investigation: ball mills, pneumatic homogenizing silos, cyclone preheaters, and rotary kilns. To assess the homogenization efficacy of each apparatus, scaled-down models of these devices were constructed and subjected to simulated experiments. To improve experimental efficiency and realistically simulate actual production conditions in a laboratory setting, this study used the uniformity of the electrical capacitance of mixed powders instead of compositional uniformity to analyze homogenization effects. The test material in the experiment consisted of a mixture of raw meal from a cement factory with a high dielectric constant and Fe3O4 powder. The parallel plate capacitance method was employed to ascertain the capacitance value of the mixed powder prior to and subsequent to treatment by each equipment model. The fluctuation of the input and output curves was analyzed, and the standard deviation (S), coefficient of variation (R), and homogenization multiplier (H) were calculated in order to evaluate the homogenization effect of each equipment model on the raw meal. The findings of the study indicated that the pneumatic homogenizer exhibited an exemplary homogenization effect, followed by the ball mill. For the ball mill, a higher proportion of small balls in the gradation can significantly enhance the homogenization effect without considering the grinding efficiency. The five-stage cyclone preheater also has a better homogenization effect, while the rotary kiln has a less significant homogenization effect on raw meal. Finally, the raw meal processed by each equipment model was used for clinker calcination and the preparation of cement mortar samples. After curing for three days, the compressive and flexural strengths of the samples were tested, thereby indirectly verifying the homogenization effect of each equipment model on the raw meal. This study helps to understand the homogenization process of raw materials by equipment in cement production and provides certain reference and data support for equipment selection, operation optimization, and quality control in the cement production process.

Performance Study of Diamond Powder-Filled Sodium Silicate-Based Thermal Conductive Adhesives.

With the development of miniaturized, highly integrated, and multifunctional electronic devices, the heat flow per unit area has increased dramatically, making heat dissipation a bottleneck in the development of the electronics industry. The purpose of this study is to develop a new inorganic thermal conductive adhesive to overcome the contradiction between the thermal conductivity and mechanical properties of organic thermal conductive adhesives. In this study, an inorganic matrix material, sodium silicate, was used, and diamond powder was modified to become a thermal conductive filler. The influence of the content of diamond powder on the thermal conductive adhesive properties was studied through systematic characterization and testing. In the experiment, diamond powder modified by 3-aminopropyltriethoxysilane coupling agent was selected as the thermal conductive filler and filled into a sodium silicate matrix with a mass fraction of 34% to prepare a series of inorganic thermal conductive adhesives. The thermal conductivity of the diamond powder and its content on the thermal conductivity of the adhesive were studied by testing the thermal conductivity and taking SEM photos. In addition, X-ray diffraction, infrared spectroscopy, and EDS testing were used to analyze the composition of the modified diamond powder surface. Through the study of diamond content, it was found that as the diamond content gradually increases, the adhesive performance of the thermal conductive adhesive first increases and then decreases. The best adhesive performance was achieved when the diamond mass fraction was 60%, with a tensile shear strength of 1.83 MPa. As the diamond content increased, the thermal conductivity of the thermal conductive adhesive first increased and then decreased. The best thermal conductivity was achieved when the diamond mass fraction was 50%, with a thermal conductivity coefficient of 10.32 W/(m·K). The best adhesive performance and thermal conductivity were achieved when the diamond mass fraction was between 50% and 60%. The inorganic thermal conductive adhesive system based on sodium silicate and diamond proposed in this study has outstanding comprehensive performance and is a promising new thermal conductive material that can replace organic thermal conductive adhesives. The results of this study provide new ideas and methods for the development of inorganic thermal conductive adhesives and are expected to promote the application and development of inorganic thermal conductive materials.

Performance Study of a Leaf-Vein-like Structured Vapor Chamber.

As optoelectronic products continue to advance rapidly, the need for effective heat dissipation has become increasingly crucial due to the emphasis on miniaturization and high integration. The vapor chamber is widely used for cooling electronic systems as a passive liquid-gas two-phase high-efficiency heat exchange device. In this paper, we designed and manufactured a new kind of vapor chamber using cotton yarn as the wick material, combined with a fractal pattern layout of leaf veins. A comprehensive investigation was conducted to analyze the performance of the vapor chamber under natural convection circumstances. SEM showed that many tiny pores and capillaries were formed between the cotton yarn fibers, which are very suitable as the wick material of the vapor chamber. Additionally, experimental findings demonstrated the favorable flow and heat transfer characteristics of the cotton yarn wick within the vapor chamber, which makes the vapor chamber have significant heat dissipation capability, compared to the other two vapor chambers; this vapor chamber has a thermal resistance of only 0.43 °C/W at a thermal load of 8.7 W. In addition, the vapor chamber showed good antigravity capability, and its performance did not show significant changes between horizontal and vertical positions; the maximum difference in thermal resistance at four tilt angles is only 0.06 °C/W. This paper also studied the influence of vacuum degree and filling amount on the performance of the vapor chamber. These findings indicate that the proposed vapor chamber provides a promising thermal management solution for some mobile electronic devices and provides a new idea for selecting wick materials for vapor chambers.

Quantitative susceptibility-weighted imaging may be an accurate method for determining stroke hypoperfusion and hypoxia of penumbra.

OBJECTIVES: To quantitatively evaluate the volume of the ischemic penumbra using susceptibility-weighted imaging and mapping (SWIM) of asymmetrical prominent cortical veins (APCVs) in patients with acute ischemic stroke. METHODS: Eighty-five eligible patients with acute ischemic stroke on admission within 12 h from symptom onset were studied. The APCVs on SWIM were quantitatively (SWI-volume) and semi-quantitatively (SWI-Alberta Stroke Program Early CT Score, SWI-ASPECTS) evaluated to calculate mismatch. To assess the diagnostic efficacy of APCVs on SWIM, comparative analyses were performed between SWIvolume-DWI mismatch and SWIASPECTS-DWI mismatch, using PWI-DWI mismatch as a reference. Correlations were calculated between the mismatches, as well as between SWI-volume and time-to-maximum (Tmax) > 6 s volume. Additionally, each of these mismatches was correlated with the National Institute of Health Stroke Scale (NIHSS). RESULTS: The sensitivity, negative predictive value, and accuracy of SWIvolume-DWI mismatch were demonstrably higher than SWIASPECTS-DWI mismatch (100% vs. 53.7%, 100% vs. 9.5%, 97.7% vs. 54.5%, respectively). A significant positive correlation was found between SWIvolume-DWI and PWI-DWI mismatch (r = 0.691, p < 0.01), as well as between SWI-volume and Tmax > 6 s volume (r = 0.786, p < 0.001). A significant negative correlation was found between SWIvolume-DWI mismatch and NIHSS (r = - 0.360, p = 0.022), as well as between SWIASPECTS-DWI mismatch and NIHSS (r = - 0.499, p = 0.001). CONCLUSIONS: SWIvolume-DWI mismatch had higher diagnostic efficacy than SWIASPECTS-DWI mismatch in defining the ischemic penumbra and showed good consistency with PWI-DWI mismatch in acute ischemic stroke. Quantitation of APCVs using SWIM provided an accurate method for determining hypoperfusion and provided a reliable method to reflect the hypoxia of penumbra. KEY POINTS: • SWIvolume-DWI mismatch has higher diagnostic efficacy than SWIASPECTS-DWI mismatch in defining the ischemic penumbra. • SWIvolume-DWI mismatch shows good consistency with PWI-DWI mismatch in managing penumbra in acute ischemic stroke. • Quantitation of APCV volume using SWIM provided an accurate method for determining the hypoperfusion area and provided a reliable method to reflect the hypoxia of penumbra.

[Independent prognostic factors and survival prediction model for 117 patients with advanced oral squamous cell carcinoma].

PURPOSE: To investigate the independent prognostic factors and establish survival prediction model for advanced oral squamous cell carcinoma (OSCC). METHODS: At the time of admission, the general information and past medical history of 177 patients with advanced OSCC were collected in detail. All patients underwent radical resection. After surgery, radiotherapy and chemotherapy with hydroxycampothecin (HCPT) and pingyangmycin (PYM) were performed according to the patient's condition. All patients were followed up for 5 years after surgery, and the survival rate during that period and the risk factors for prognosis were analyzed. The data were analyzed by SPSS 20.0 software package. RESULTS: During the follow-up period, 2 patients died due to other causes, 4 were excluded due to lost to follow-up, 42 of the remaining 111 patients died, 69 survived, the total survival rate was 62.16%. The survival status of patients with advanced OSCC with different age, T stage and M stage had no significant difference (P>0.05), while significant difference was found among patients with different gender, tissue differentiation degree, N stage and chemotherapy (P<0.05). Gender, N stage and HCPT in combination of PYM chemotherapy were independent risk factors (P<0.05), while histological differentiation degree was not an independent risk factor for survival of patients (P>0.05). The survival curves of gender, N stage and HCPT in combination of PYM chemotherapy had certain predictive value on the survival of patients with advanced OSCC. CONCLUSIONS: Gender, N stage and HCPT in combination of PYM chemotherapy are independent risk factors for the survival of patients with advanced OSCC, and their survival curves can be used as a survival prediction model.

Phosphorus removal from aqueous solutions using a synthesized adsorbent prepared from mineralized refuse and sewage sludge.

Mineralized refuse and sewage sludge generated from solid waste from municipal landfills and sewage treatment plants were sintered as a cost-effective adsorbent for the removal of phosphorus. Compared with the Freundlich model, phosphorus adsorption on the synthesized adsorbent, zeolite and ironstone was best described by the Langmuir model. Based on the Langmuir model, the maximum adsorption capacity of the synthesized adsorbent (9718 mg kg(-1)) was 13.7 and 25.4 times greater than those of zeolite and ironstone, respectively. The desorbability of phosphorus from the synthesized adsorbent was significantly lower than that of zeolite. Moreover, phosphorus removal using the synthesized adsorbent was more tolerant to pH fluctuations than zeolite and ironstone for the removal of phosphorus from aqueous solutions. The immobilization of phosphorus onto the synthesized adsorbent was attributed to the formation of insoluble calcium, aluminium and iron phosphorus. The heavy metal ion concentrations of the leachate of the synthesized adsorbent were negligible. The synthesized adsorbent prepared from mineralized refuse and sewage sludge was cost-effective and possessed a high adsorptive capacity for phosphorus removal from aqueous solutions.