Several modifications of lead anode for zinc electrowinning have been studied. The results are summarized as follows;(1) By using a Pb-Ag-Ca alloy anode, the bath voltage decreased compared with the conventional Pb-1%Ag anode, and the anode potential decreased with increasing in the content of Ca and Ag in Pb-Ag-Ca anodes.(2) At the beginning of the electrolysis, the amount of the generated gas on the Pb-0.5%Ag-0.6%Ca anodes was larger than that on Pb-1%Ag anodes and the increase in Ca content in the Pb-Ag-Ca anodes caused a larger gas.(3) The original microstructural features before electrolysis were investigated with the EPMA. In the Pb-0.9%Ag alloy, the fine particles of Ag-rich phase was found to be homogeneously distributed around the Pb grains. In case of the Pb-0.5%Ag-0.6%Ca alloy, the Ag-rich phase was scattered in the grain boundaries.The content of Ag in the Ag-rich phase of the Pb-0.5%Ag-0.6%Ca alloy was higher than that in the Pb-1%Ag alloy.In the Pb-0.8%Ca and Pb-0.5%Ag-0.6%Ca alloy, the CaPb3 phase appeared.
In order to clarify the conditions to produce a dense and large pellet required from the MEBIOS method, some basic sintering experiments were conducted. Consequently, the pellet having a sufficient strength as a blast furnace burden was able to be produced by selecting the composition of the pellet and the temperature so that the liquid phase ratio in the CaO–Fe2O3–SiO2 system was about 40 mass%. Moreover, it was confirmed by the sintering pot experiment using X-ray CT that a void was formed around the pellet when this pellet was placed in the sintering mixture. The crushing strength of the pellet collected from the sinter cake was low. However, increasing of the basicity of the pellet and extension of the retention time at high temperature were effective for improving the crushing strength of the pellet.
In order to examine the feasibility of the carbothermic reduction process using the composite pellets of iron ore and coal fines in their combustion packed bed, laboratory scale experiments were conducted. To prevent the reoxidation of the reduced pellets, attempts were made by coating the composite pellets with different fine materials such as iron ore, limestone, dolomite, serpentine and SiO2 reagent. The isothermal reduction experiment using a single composite pellet shows that SiO2 bearing material, such as serpentine fine and SiO2 reagent, give a reasonable suppression effect on the reoxidation at high temperature. The metallization degree of about 70% has been attained. On the basis of this result, the carbothermic reduction experiment in the combustion packed bed was conducted using the composite pellet coated with SiO2 reagent powder. In this case, the maximum metallization degree was as much as 45% because of the reoxidation of metallic iron could not be perfectly suppressed during the process. Further reduction experiment was carried out using the composite pellet coated by the fine mixture of CaO-SiO2-Al2O3 system to form a melt of the coating layer in high temperature. It gives the maximum metallization degree of about 60%. It suggests that the proposed carbothermic reduction process has a possibility to produce the partially-reduced iron burdens for the blast furnace, although its production rate is necessary to be improved.
The anodic dissolution reaction of copper in copper electro-refining was studied by considering the reaction of galvanic couples with different metals as impurities. In this study, zinc was chosen as a typical anodic impurity and silver as a cathodic impurity, and electrochemical measurements of galvanic couples with silver or zinc wires winding around a copper wire and in situ observation of the electrode surface using a stereo microscope were carried out. For comparison, copper wire with zinc or silver plating was used. As a result, even the simple method of winding silver or zinc wire around copper wire was able to capture the characteristic behavior of the galvanic reaction of silver and zinc on copper wire. It was also confirmed that zinc dissolution was accelerated by copper and copper dissolution was accelerated by silver, and that the effects were more promoted under anodic polarization. The crystallization and passivation of copper sulfate on the copper electrode surface and the dissolution behavior of silver were also observed. These results indicate that the experimental method presented in this study is an effective way to investigate the effects of impurities on the solubility and passivation of crude copper metal.
The early elevation of cardiac troponins within 24 hours after noncardiac surgery is reportedly associated with increased postoperative morbidities. Several predisposing factors, including the frequent occurrence of hypoxia and increased pulmonary arterial pressure, may likely contribute to this elevation, especially after intrathoracic surgery. Therefore, this retrospective study aimed to elucidate the incidence and characteristics of the early elevation of cardiac troponin I after intrathoracic surgery. This study included 320 patients who underwent intrathoracic surgery between January 1, 2018, and June 30, 2021. Specific perioperative variables were retrospectively collected from their electrical clinical records. The serum concentration of high-sensitivity cardiac troponin I (hs cTnI) was measured twice immediately after the intensive care unit arrival and on the following day. We grouped these patients into two: the early elevation of hs cTnI (EECT) group (hs cTnI value > 26.2 ng/L by at least 1 measurement) and the non-early elevation (non-EECT) group. Patient characteristics were then compared between these groups. The hs cTnI level elevated within 24 hours postoperatively in 103 patients (32.2%). In univariate analysis, intraoperative variables, including the duration of unilateral ventilation (199.2 minutes, P = .0025) and surgery (210.6 minutes, P = .0012), estimated blood loss volume (406.7 mL, P = .0022), percentage of stored red blood cell (RBC) transfusion (10.7%, P = .0059), and percentage of lobectomy or combination of other lung resection types (88.3%, P = .00188), were significantly higher in the EECT group than in the non-EECT group. In the log-rank test, prolonged hospitalization was more prevalent in the EECT group ( P = .0485). Furthermore, multivariate analysis revealed 3 independent risk factors for the early elevation of hs cTnI: coexisting chronic renal failure (odds ratio [OR], 3.25), lobectomy or combined resections (OR, 2.65), and stored RBC transfusion (OR, 3.41). The early elevation of hs cTnI commonly occurs after intrathoracic surgery, with an incidence of 32.2%. Its 3 independent risk factors are coexisting chronic renal failure, lung resection type, and stored RBC transfusion.
For the recycling of valuable metals contained in the printed circuit board wastes (PCBW), the effect of temperature on chlorination-volatilization behavior of metals under valuable chlorine resource was investigated. For the experimental sample powder of two types PCBW: crushed PCBW and roasted PCBW was used. The samples were heated at predefined temperatures ranging from 300°C to 900°C with chlorine, argon gas atmosphere or CaCl2 as a solid chlorine source. Chlorine/Argon gas flow into furnace was set at a rate of 100 mL/min. As a result, most of metals in crushed PCBW did not volatilize regardless the temperature, argon gas atmosphere and CaCl2 as chlorine source. In contrast, in the Cl2 gas atmosphere, a lot of metals in crushed and/or roasted PCBW volatilized by raising temperature. Compering the experimental samples, volatilization rate of crushed PCBW is higher than roasted PCBW. This is considered to be influenced by the chemical composition of metals in the samples. When using the crushed PCBW, most metals were volatilized over 90% at 900°C. In addition, in 70% of volatilized metals that were recovered, Cu, Au, Ni were concentrated. According to the results, valuable metals could be recovered by chlorination volatilization from PCBW.
The fluidity of melt formed in the iron ore sintering process seems to be an important factor for agglomeration of raw mixtures, since the formed melt plays the role of bonding the un-fused coarse iron ores. In the present study, sintering experiment was conducted in order to find the optimal particle size of fine iron ore for maintaining the fluidity of melt under the condition with low slag ratio and a large amount of limonite ore in the raw mixtures. As the results, it was found that the fluidity of melt lowered by decreasing the slag ratio and by increasing the amount of limonite ore in the raw mixtures. Furthermore, the optimal particle size of fine iron ore to maintain the fluidity was found to be different depended on the slag ratio in the raw mixtures and the combined water content in the iron ore.
