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排序方式: 共有1111条查询结果,搜索用时 15 毫秒
1.
《Advanced Powder Technology》2022,33(11):103833
Eliminating the gold preg-robbing effect of carbonaceous matter in carbonaceous gold ores is crucial for gold leaching. In this study, suspension oxidation roasting was proposed to accelerate the decarbonization of carbonaceous gold ore. The characteristics of oxidation reaction process and gas release were analyzed by TG-DTA-FTIR. The phase transformation and microstructure evolution of samples during roasting were analyzed by XRD, SEM and BET. The results show that the gold preg-robbing effect was eliminated after the gasification of carbonaceous matter, and the CaO generated by decomposition of carbonates can effectively capture the SO2. After roasting for 75 min at 650 °C in a 20% O2 atmosphere, the total carbon removal rate reached 99.42%, the distribution of exposed gold increased from 28.85% to 77.10% and the gold leaching efficiency increased from 4.55% to 84.83%. In addition, about 70% sulfur was mainly fixed in the roasted products in the form of sulfate. Therefore, the suspension oxidation roasting process is an efficient and clean pretreatment method for carbonaceous gold ores. 相似文献
2.
《International Journal of Hydrogen Energy》2019,44(11):5108-5113
Recovery hydrogen from hydrogen sulfide is an effective way of utilizing exhaust gas. In this paper, removal of hydrogen sulfide by indirect electrochemical process was studied using acidic aqueous solution of Fe3+/Fe2+ as the electrochemical intermediate. Solid polymer electrolyte was applied to hydrogen production by indirect electrolysis of H2S, in which the anode was graphite cloth, the cathode was the platinized graphite cloth, and the membrane was proton exchange membrane. The results of electrolysis experiments showed the relationship of current density as a function of electrolytic voltage at constant flow rate of electrolyte, temperature, and electrolyte composition. The effect of the cathode liquid velocity on current density was small. When the flow rate of anode electrolyte was greater than 200 L/hr., the current density tended to be stable. When [Fe3+]>0.20 mol/L, the concentrations of Fe2+ and Fe3+ ions in the anode solution had no significant impact on the current density. The current density gradually increased with temperature. In the electrolytic process of hydrogen production, the Fe2+ ions diffused from the anode to the cathode. The amount of diffusing Fe2+ ions gradually increased with time. The effect of Fe2+ ions diffusion from anode to cathode on hydrogen production was discussed. 相似文献
3.
Shanke Liu Hui Jin Yan Yang Lijun Yu 《International Journal of Hydrogen Energy》2021,46(54):27473-27482
Benzothiophene (BT) is a key sulfur-containing intermediate product in the thermal conversion process of coal and heavy oil. The migration process of the sulfur element may affect the thermal utilization design of BT. In this paper, BT was used as a model compound to simulate the supercritical water gasification (SCWG) process by molecular dynamics with a reactive force field (ReaxFF) method, and the laws of hydrogen production and sulfur migration mechanisms were obtained. Increasing the molecule number of supercritical water (SCW) and increasing the reaction temperature can enhance the generation of hydrogen and promote the conversion of organic sulfur to inorganic sulfur. Water was the main source of H2, and H2S was the main gaseous sulfur-containing product. SCW had a certain degree of oxidation due to a large number of hydroxyl radicals, which could increase the valence of sulfur. The conversion process of BT in SCW was mainly divided into four stages, including thiophene ring-opening; sulfur separation or carbon chain broke with sulfur retention; carbon chain cleaved, and gas generation. The lumped kinetic parameters of the conversion of sulfur in BT to inorganic sulfur were calculated, and the activation energy was 369.98 kJ/mol, which was much lower than those under pyrolysis conditions. This article aims to clarify the synergistic characteristics of hydrogen production and sulfur migration in the SCWG process of BT from the molecular perspective, which is expected to provide a theoretical basis for pollutant directional removal during hydrogen production by sulfur-containing organic matters in SCW. 相似文献
4.
The increase in the production of acid gas consisting of H2S, CO2, and associated impurities such as ammonia and hydrocarbons from oil and gas plants and gasification facilities has stimulated the interest in the development of alternative means of acid gas utilization to produce hydrogen and sulfur, simultaneously. The present literature lacks a detailed reaction mechanism that can reliably predict the thermal destruction of NH3 and its blend with H2S and CO2 to facilitate process optimization and commercialization. In this paper, a detailed mechanism of NH3 pyrolysis is developed and is merged with the reactions of NH3 oxidation and H2S/CO2 thermal decomposition from our previous works. The mechanism is validated successfully using different sets of experimental data on the pyrolysis and oxidation of NH3, H2S, and CO2. The proposed mechanism predicts the experimental data on NH3 pyrolysis remarkably better than the existing mechanisms in the literature. The mechanism is used to investigate the effects of NH3 concentration (0–20%) and reactor temperature (1000–1800 K) on the thermal decomposition of H2S and CO2. A synergistic effect is observed in the simultaneous decomposition of NH3 and CO2, i.e., NH3 conversion is improved in the presence of CO2 and the decomposition CO2 to CO is enhanced in the presence of NH3. The presence of H2S suppressed NH3 conversion, while the conversion of H2S remained unchanged with increasing NH3 concentration at temperature below 1400 K due to the low conversion of NH3 (up to 18%). At temperature above 1400 K, NH3 conversion increased rapidly and it triggered a decrease in H2S conversion as well as the yields of H2 and S2. The major reactions involved in the decomposition of H2S, CO2, and NH3 and the production of major products such as H2, S2, and CO are identified. The detailed reaction mechanism can facilitate the design and optimization of acid gas thermal decomposition to produce hydrogen and sulfur, simultaneously. 相似文献
5.
6.
Zhi Ying Jingyang Yang Xiaoyuan Zheng Yabin Wang Binlin Dou 《International Journal of Hydrogen Energy》2021,46(45):23139-23148
A novel sulfur–iodine (SI or IS) cycle integrated with HI–I2–H2O electrolysis for hydrogen production was developed and thermodynamically analyzed in this work. HI–I2–H2O electrolysis was used to replace the conventional concentration, distillation, and decomposition processes of HI, so as to simplify the flowsheet of SI cycle. And then the new cycle was divided into Bunsen reaction, H2SO4 decomposition and HI–I2–H2O electrolysis sections. Through incorporating the user-defined module of HI–I2–H2O electrolysis with Aspen Plus, the cycle was simulated and 0.448 mol/h (10 L/h) of H2 was produced. The overall energy and exergy efficiencies of the novel SI system were estimated to be 15.3–31.0% and 32.8%, respectively. Most exergy destruction occurred in the H2SO4 decomposer and condenser for H2SO4 decomposition and Bunsen reaction sections, which accounted for 93.0% and 63.4%, respectively. A high exergy efficiency of 92.4% for HI–I2–H2O electrolysis section with less exergy destruction was determined, mostly due to the transformation of the overall electricity in electrolytic cell to exergy. Appropriate internal heat exchange and waste heat recovery will favor improving the energy and exergy efficiencies. 相似文献
7.
《International Journal of Hydrogen Energy》2022,47(1):57-68
Three different proton conducting polymeric membrane materials (Nafion® 115, Nafion® 212, and sulfonated Diels-Alder polyphenylene [SDAPP]) were evaluated for use in SO2-depolarized electrolyzers for the production of hydrogen via the hybrid sulfur cycle. Their performance was measured using different water feed strategies to minimize overpotential losses while maintaining high product acid concentration. Both thin membranes (Nafion® 212 and SDAPP) showed performance superior to that of the thicker Nafion® 115. The SDAPP membrane electrode assembly (MEA) performed well at higher acid concentrations, maintaining low ohmic and kinetic overpotentials. Finally, short-term (100-h) stability tests under constant current conditions showed minimal degradation for the SDAPP and Nafion® 212 MEAs. SDAPP MEA performance approached the targets needed to make the hybrid sulfur cycle a competitive process for hydrogen production (product acid concentration ≥65 wt% H2SO4 at ≤ 0.6-V cell potential and ≥0.5 A-cm?2 current density). 相似文献
8.
Dong Sun Lin Yang Ning Liu Wenju Jiang Xia Jiang Jianjun Li Zhengyou Yang Zhengping Song 《中国化学工程学报》2020,28(3):864-870
An environmentally friendly and resource-conserving route to the clean production of electrolytic manganese was developed, in which the electrolytic manganese residue(EMR) was initially calcined for cement buffering;then the generated SO_2-containing flue gas was managed using manganese oxide ore and anolyte(MOOA) desulfurization; at last, the desulfurized slurry was introduced to the electrolytic manganese production(EMP). Results showed that 4.0 wt% coke addition reduced the sulfur of calcined EMR to 0.9%, thereby satisfying the cement-buffer requirement. Pilot-scale desulfurization showed that about 7.5 vol% of high SO_2 containing flue gas can be cleaned to less than 0.1 vol% through a five-stage countercurrent MOOA desulfurization. The desulfurized slurry had 42.44 g·L~(-) Mn~(2+) and 1.92 g·L~(-1) S_2 O_6~(2-), which was suitable for electrowinning after purification, and the purity of manganese product was 99.93%, satisfy the National Standard of China YB/T051-2015.This new integrated technology fulfilled 99.7% of sulfur reutilization from the EMR and 94.1% was effectively used to the EMP. The MOOA desulfurization linked the EMP a closed cycle without any pollutant discharge, which promoted the cleaner production of EMP industry. 相似文献
9.
Mohammad Dana Mohammad Amin Sobati Shahrokh Shahhosseini Aminreza Ansari 《中国化学工程学报》2020,28(5):1384-1396
A continuous-flow ultrasound-assisted oxidative desulfurization(UAOD) of partially hydro-treated diesel has been investigated using hydrogen peroxide-formic acid as simple and easy to apply oxidation system. The effects of different operating parameters of oxidation stage including residence time(2–24 min), formic acid to sulfur molar ratio(10–150), and oxidant to sulfur molar ratio(5–35) on the sulfur removal have been studied using response surface methodology(RSM) based on Box–Behnken design. Considering the operating costs of the continuous-flow oxidation stage including chemical and electrical energy consumption, the appropriate values of operating parameters were selected as follows: residence time of 16 min, the formic acid to sulfur molar ratio of 54.47, and the oxidant to sulfur molar ratio of 8.24. In these conditions, the sulfur removal and the volume ratio of the hydrocarbon phase to the aqueous phase were 86.90% and 4.34, respectively. By drastic reduction in the chemical consumption in the oxidation stage, the volume ratio of the hydrocarbon phase to the aqueous phase was increased up to 10. Therefore, the formic acid to sulfur molar ratio and the oxidant to sulfur molar ratio were obtained 23.64 and 3.58, respectively, which lead to sulfur removal of 84.38% with considerable improvements on the operating cost of oxidation stage in comparison with the previous works. 相似文献
10.
Materials resistance to corrosion by I2–HI–H2O mixtures for the realization of a sulfur-iodine plant
《International Journal of Hydrogen Energy》2019,44(49):26816-26834
The substances involved in the sulfur-iodine (SI) thermochemical cycle to produce H2 by water splitting are very corrosive and may attack reactors, pumps, catalysts supports, and whatever part of the plant. This paper investigates the corrosion exerted by HI solutions in liquid, boiling, and gaseous phase at different temperatures. It shows the broadest overview of the behavior of different materials, ranging from pure metals to metallic alloys, from carbon materials to organic polymers, from ceramic materials to composite ones. Commercial nickel alloys and the effect of a specific element in their composition have here considerable attention. Regarding the composites materials, the impact of the substrate as well as the coating nature and thickness is studied, also through SEM-EDS (Scan Electron Microscope Energy Dispersive Spectroscopy) investigations.Carbon materials performed well, while most of the analyzed materials showed intergranular corrosion, pitting phenomena, and sometimes, carbide precipitation in the higher energy zones. 相似文献