首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 234 毫秒
1.
《矿物冶金与材料学报》2021,28(12):2001-2007
Graphene oxide (GO) wrapped Fe3O4 nanoparticles (NPs) were prepared by coating the Fe3O4 NPs with a SiO2 layer, and then modifying by amino groups, which interact with the GO nanosheets to form covalent bonding. The SiO2 coating layer plays a key role in integrating the magnetic nanoparticles with the GO nanosheets. The effect of the amount of SiO2 on the morphology, structure, adsorption, and regenerability of the composites was studied in detail. An appropriate SiO2 layer can effectively induce the GO nanosheets to completely wrap the Fe3O4 NPs, forming a core-shell Fe3O4@SiO2@GO composite where Fe3O4@SiO2 NPs are firmly encapsulated by GO nanosheets. The optimized Fe3O4@SiO2@GO sample exhibits a high saturated adsorption capacity of 253 mg·g?1 Pb(II) cations from wastewater, and the adsorption process is well fitted by Langmuir adsorption model. Notably, the composite displays excellent regeneration, maintaining a ~90% adsorption capacity for five cycles, while other samples decrease their adsorption capacity rapidly. This work provides a theoretical guidance to improve the regeneration of the GO-based adsorbents.  相似文献   

2.
《矿物冶金与材料学报》2021,28(12):1908-1916
The effect of CaCO3, Na2CO3, and CaF2 on the reduction roasting and magnetic separation of high-phosphorus iron ore containing phosphorus in the form of Fe3PO7 and apatite was investigated. The results revealed that Na2CO3 had the most significant effect on iron recovery and dephosphorization, followed by CaCO3, the effect of CaF2 was negligible. The mechanisms of CaCO3, Na2CO3, and CaF2 were investigated using X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM–EDS). Without additives, Fe3PO7 was reduced to elemental phosphorus and formed an iron–phosphorus alloy with metallic iron. The addition of CaCO3 reacted with Fe3PO7 to generate an enormous amount of Ca3(PO4)2 and promoted the reduction of iron oxides. However, the growth of iron particles was inhibited. With the addition of Na2CO3, the phosphorus in Fe3PO7 migrated to nepheline and Na2CO3 improved the reduction of iron oxides and growth of iron particles. Therefore, the recovery of iron and the separation of iron and phosphorus were the best. In contrast, CaF2 reacted with Fe3PO7 to form fine Ca3(PO4)2 particles scattered around the iron particles, making the separation of iron and phosphorus difficult.  相似文献   

3.
4.
Carbonated decomposition of hydrogarnet is one of the vital reactions of the calcification–carbonation method, which is designed to dispose of low-grade bauxite and Bayer red mud and is a novel eco-friendly method. In this study, the effect of the silica saturation coefficient (x) on the carbonation of hydrogarnet was investigated from the kinetic perspective. The results indicated that the carbonation of hydrogarnets with different x values (x = 0.27, 0.36, 0.70, and 0.73) underwent two stages with significantly different rates, and the kinetic mechanisms of the two stages can be described by the kinetic functions R3 and D3. The apparent activation energies at Stages 1 and 2 were 41.96–81.64 and 14.80–34.84 kJ/mol, respectively. Moreover, the corresponding limiting steps of the two stages were interfacial chemical reaction and diffusion.  相似文献   

5.
《矿物冶金与材料学报》2020,27(10):1347-1352
A new method of high-gravity combustion synthesis (HGCS) followed by post-treatment (PT) is reported for preparing high-performance high-entropy alloys (HEAs), Cr0.9FeNi2.5V0.2Al0.5 alloy, whereby cheap thermite powder is used as the raw material. In this process, the HEA melt and the ceramic melt are rapidly formed by a strong exothermic combustion synthesis reaction and completely separated under a high-gravity field. Then, the master alloy is obtained after cooling. Subsequently, the master alloy is sequentially subjected to conventional vacuum arc melting (VAM), homogenization treatment, cold rolling, and annealing treatment to realize a tensile strength, yield strength, and elongation of 1250 MPa, 1075 MPa, and 2.9%, respectively. The present method is increasingly attractive due to its low cost of raw materials and the intermediate product obtained without high-temperature heating. Based on the calculation of phase separation kinetics in the high-temperature melt, it is expected that the final alloys with high performance can be prepared directly across master alloys with higher high-gravity coefficients.  相似文献   

6.
Computational simulations and high-temperature measurements of velocities near the surface of a mold were carried out by using the rod deflection method to study the effects of various operating parameters on the flow field in slab continuous casting (CC) molds with narrow widths for the production of automobile exposed panels. Reasonable agreement between the calculated results and measured subsurface velocities of liquid steel was obtained under different operating parameters of the CC process. The simulation results reveal that the flow field in the horizontal plane located 50 mm from the meniscus can be used as the characteristic flow field to optimize the flow field of molten steel in the mold. Increases in casting speed can increase the subsurface velocity of molten steel and shift the position of the vortex core downward in the downward circulation zone. The flow field of liquid steel in a 1040 mm-wide slab CC mold can be improved by an Ar gas flow rate of 7 L·min?1 and casting speed of 1.7 m·min?1. Under the present experimental conditions, the double-roll flow pattern is generally stable at a submerged entry nozzle immersion depth of 170 mm.  相似文献   

7.
Electroslag remelting (ESR) gives a combination of liquid metal refining and solidification structure control. One of the typical aspects of liquid metal refining during ESR for the advanced steel and alloy production is desulfurization. It involves two patterns, i.e., slag–metal reaction and gas–slag reaction (gasifying desulfurization). In this paper, the advances in desulfurization practices of ESR are reviewed. The effects of processing parameters, including the initial sulfur level of consumable electrode, remelting atmosphere, deoxidation schemes of ESR, slag composition, melting rate, and electrical parameters on the desulfurization in ESR are assessed. The interrelation between desulfurization and sulfide inclusion evolution during ESR is discussed, and advancements in the production of sulfur-bearing steel at a high-sulfur level during ESR are described. The remaining challenges for future work are also proposed.  相似文献   

8.
We report the picosecond laser ablation of aluminum targets immersed in a polar organic liquid (chloroform, CHCl3) with ~2 ps laser pulses at an input energy of ~350 μJ. The synthesized aluminum nanoparticles exhibited a surface plasmon resonance peak at ~340 nm. Scanning electron microscopy images of Al nanoparticles demonstrated the spherical morphology with an average size of (27 ± 3.6) nm. The formation of smaller spherical Al nanoparticles and the diminished growth could be from the formation of electric double layers on the Al nanoparticles. In addition to spherical aluminum nanoparticles, triangular/pentagonal/hexagonal nanoparticles were also observed in the colloidal solution. Field emission scanning electron microscopy images of ablated Al targets demonstrated laser induced periodic surface structures (LIPSSs), which were the high spatial frequency LIPSSs (HSF-LIPSSs) since their grating period was ~280 nm. Additionally, coarse structures with a period of ~700 nm were observed.  相似文献   

9.
The mineral transition and formation mechanism of calcium aluminate compounds in CaO?Al2O3?Na2O system during the high-temperature sintering process were systematically investigated using DSC?TG, XRD, SEM?EDS, FTIR, and Raman spectra, and the crystal structure of Na4Ca3(AlO2)10 was also simulated by Material Studio software. The results indicated that the minerals formed during the sintering process included Na4Ca3(AlO2)10, CaO·Al2O3, and 12CaO·7Al2O3, and the content of Na4Ca3(AlO2)10 could reach 92wt% when sintered at 1200°C for 30 min. The main formation stage of Na4Ca3(AlO2)10 occurred at temperatures from 970 to 1100°C, and the content could reach 82wt% when the reaction temperature increased to 1100°C. The crystal system of Na4Ca3(AlO2)10 was tetragonal, and the cells preferred to grow along crystal planes (110) and (210). The formation of Na4Ca3(AlO2)10 was an exothermic reaction that followed a secondary reaction model, and its activation energy was 223.97 kJ/mol.  相似文献   

10.
Ore particles, especially fine interlayers, commonly segregate in heap stacking, leading to undesirable flow paths and changeable flow velocity fields of packed beds. Computed tomography (CT), COMSOL Multiphysics, and MATLAB were utilized to quantify pore structures and visualize flow behavior inside packed beds with segregated fine interlayers. The formation of fine interlayers was accompanied with the segregation of particles in packed beds. Fine particles reached the upper position of the packed beds during stacking. CT revealed that the average porosity of fine interlayers (24.21%) was significantly lower than that of the heap packed by coarse ores (37.42%), which directly affected the formation of flow paths. Specifically, the potential flow paths in the internal regions of fine interlayers were undeveloped. Fluid flowed and bypassed the fine interlayers and along the sides of the packed beds. Flow velocity also indicated that the flow paths easily gathered in the pore throat where flow velocity (1.8 × 10?5 m/s) suddenly increased. Fluid stagnant regions with a flow velocity lower than 0.2 × 10?5 m/s appeared in flow paths with a large diameter.  相似文献   

11.
安全监管是提高煤矿安全生产水平的有效途径.运用演化博弈理论构建了单一煤矿群体安全生产行为博弈模型和非对称煤矿安全监察博弈模型,通过复制动态方程的动态趋势和稳定性分析对煤矿安全监管进行了深入的探讨.结果表明:降低煤矿安全生产成本,降低监察成本和提高监察效率,提高惩罚力度等都将使煤矿安全监管博弈向着良好的方向演化.  相似文献   

12.
吴海军 《科技资讯》2013,(15):156-156,158
随着社会经济的发展,煤矿机电设备得到了广泛的应用,机电安全设备直接影响到矿山的安全和经济效益,为促进我国的煤炭生产和煤炭工业的可持续发展,煤矿机电事故预防,本文从煤矿机电设备、管理等方面进行分析。  相似文献   

13.
袁世凯集团几十个人,为挽回开平煤矿之主权及利权,群策群力,经过几十年的奋斗,创办了滦州煤矿,力求以滦州矿兼并开平矿,最后终于使滦州矿与开平矿合办为开滦煤矿,大力发展中国近代煤炭事业及交通运输事业,取得了光辉成就,功不可没。  相似文献   

14.
煤矿机电事故原因探析及对策思考   总被引:3,自引:0,他引:3  
艾井石 《科技信息》2008,(2):311-311
近年来,煤矿机电事故已开始成为制约我国煤矿行业生产的一个重要因素。因此,预防煤矿机电事故的发生,就成为我国煤矿安全工作和煤矿行业可持续发展的重要一环。笔者归纳、分析了当前我国煤矿机电事故发生的主因,并提出相应的改进措施和对策。  相似文献   

15.
为了对煤矿应急救援能力进行综合评价研究,分析了应急救援能力的内涵,重新界定了应急救援能力的概念;在分析煤矿应急救援能力的影响因素的基础上,构建了多层次煤矿应急救援能力评价指标体系,建立了基于灰色-模糊综合评价法的煤矿应急救援能力评价模型.通过实例表明,该方法能对煤矿应急救援现状进行较为准确的评价,为煤矿提升自身应急救援能力提供依据.  相似文献   

16.
针对我国水资源短缺的状况,阐述了矿区矿井水处理及综合利用的必要性,分析了矿井水的主要来源及对煤矿生产的影响,根据煤矿井下排水的水质分类,提出了矿井排水的处理与利用方法。  相似文献   

17.
建立新体制下煤矿安全培训体系的研究   总被引:2,自引:1,他引:2  
分析了全国煤矿安全形势以及煤矿安全技术培训现状和存在的问题,指出了建立新体制下煤矿安全技术培训体系的必要性,提出了在新的煤矿安全监察体制下,进一步贯彻落实(安全生产法),加强煤矿安全技术培训的对策。同时对煤矿从业人员实行安全资格制度,并推行执业资格制度,建立健全煤矿安全技术培训的管理机制和保障措施等进行了探讨。  相似文献   

18.
云南恩洪盆地煤层气异常分析   总被引:1,自引:0,他引:1  
云省恩洪盆地是我省煤层气的主要集聚地之一。鉴于煤层气采样数据的空间性特点,文章利用趋势面方法和剩余分析对煤层气进行异常分析,识别煤层气富集区域,为煤层气的勘探和开发提供定量依据。  相似文献   

19.
通过对天湖山矿区铅坑矿井找煤的实践 ,充分认识该矿井的地质特征和规律 ,有针对性地开展地质找煤复采工作 ,提高煤炭回采率 ,减少煤炭资源损失 ,确保矿井持续生产 ,延长矿井服务年限  相似文献   

20.
为了解决煤矿安全投入与安全绩效的关系问题,采用系统动力学进行煤矿安全投入与安全绩效的仿真模拟。研究结果表明:在初期煤矿生产过程中,安全投入对各因素的安全水平影响有一定的滞后性;从长期来看,增加安全投入对煤矿企业的安全绩效有明显的促进作用;煤矿企业初期安全水平高低影响煤矿达成期望安全绩效的快慢;人为因素水平和管理因素水平与煤矿安全绩效呈正相关性。该成果为煤矿安全管理决策提供理论依据。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号