Radioactive Element Distribution Characteristics of Red Mud based Field Road Cement before and after Hydration

2018 ◽  
Vol 33 (2) ◽  
pp. 452-458 ◽  
Author(s):  
Xiao Wang ◽  
Juntao Ma ◽  
Lei Zhang ◽  
Jiujun Yang
Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 500 ◽  
Author(s):  
Leonid Chaikin ◽  
Andrei Shoppert ◽  
Dmitry Valeev ◽  
Irina Loginova ◽  
Julia Napol’skikh

One of the potential sources of rare-earth elements (REE) is the industrial waste known as red mud (bauxite residue), in which the majority of REE from the initial bauxite are concentrated via the Bayer process. Therefore, the studies of the subject, both in Russia and outside, focus almost exclusively on red mud processing. This article looks into the possibility of REE concentration into red mud by leaching an intermediate product of the bauxite sintering process at Russian alumina refineries, namely electrostatic precipitator (ESP) dust. The experimental works were performed by X-ray diffraction (XRD)and electron probe microanalysis (EPMA) of the sinter and sinter dust. The determination of major and rare-earth elements in the sinter from the rotary kilns and in the ESP dust before and after leaching was carried out by X-ray fluorescence (XRF) and plasma mass spectrometry (ICP-MS). The study showed that it is possible to obtain red mud that contains three times more REE than traditional waste red mud after two-stage leaching ESP dust in the water at 95 °C followed by leaching in an alkaline-aluminate liquor at 240 °C. The shrinking core model was used to study the kinetics of leaching of the original ESP dust and water-treated dust in alkaline-aluminate liquor. The study showed the change in the limiting stage of the alkaline leaching process after water treatment, with the activation energy growing from 24.98 to 33.19 kJ/mol.


2014 ◽  
Vol 65 (1) ◽  
pp. 96-106 ◽  
Author(s):  
T. Kucserka ◽  
Kata Karádi-Kovács ◽  
M. Vass ◽  
G. Selmeczy ◽  
Katalin Hubai ◽  
...  

2012 ◽  
Vol 518-523 ◽  
pp. 5030-5034
Author(s):  
Ning Zhu ◽  
Tong Qian Zhao ◽  
Chun Yan Xiao ◽  
Li Heng Jiao ◽  
Kun Feng Zhang

Abstract: This article describes the distribution characteristics of soil microbial in different vegetable types in artificial wetland restoration. The results show that quantity of microbial had a significant increase before and after restoration. The value of Polygonum hydropiper sample was largest. The sequence of increase was Polygonum hydropiper,Phragmites communis Trin,Typha angustifolia and bare land; Referring to the change of three types of microorganisms, bacteria enhance 2.16 times largest; Meanwhile fungi go up 1.11 times least. The range of microbial diversity value before restoration is 0.2437-0.7633, and after is 0.1163-0.4069;Bacteria amount had significant correlation with TN.


2020 ◽  
Author(s):  
Jiaojiao Liu ◽  
Yuhu Li ◽  
Huiping Xing ◽  
Daodao Hu ◽  
Xiaolian Chao ◽  
...  

Abstract As a kind of textile, hemp artifact is a valuable cultural heritage. Suffering from several degradation factors in the preservation of cultural relics, some ancient hemp colored-paintings have been damaged, further affected their ornamental values. Therefore, it is urged to take the suitable conservation measures to protect the precious hemp artifacts for the historical culture succession. In this paper, an examination and analysis of the hemp colored paintings were the first step to propose an appropriate conservation treatment. Ultra-depth-of-field microscope was used to identify the kinds of fiber, and scanning electron microscope (SEM) was utilized to observe their condition and surface morphology. The element distribution and composition were identified by SEM, energy disperse spectroscopy (EDS) and X-ray fluorescence spectroscopy (XRF). Gas chromatography-mass spectrometer (GC-MS) was applied to identify the kinds of binding media and amino acid composition. Moreover, novel reinforcement materials and technology were proposed with the principle of compatibility and feasibility. The properties of tensile strength, aging resistance and chromatic aberration were tested before and after dry heat aging, wet heat aging and UV light aging. After systematic examination and evaluation of the hemp colored paintings and reinforcement materials, the optimal conservation treatment was finally established, and the Chinese hemp painting as an example has been protected successfully. This paper provides new methods and ideas for the restoration and protection of the linen cultural relics, which would promote the progress of protecting valuable cultural heritages.


Author(s):  
Xinxing Li ◽  
Zirun Yang ◽  
Hongxia Wang ◽  
Lin Li ◽  
Naifei Ren

Abstract ZrO2/Ni3Al-Ni3Al double-layer coating on stainless steel was prepared by powder sintering one-step forming process. The surface-interface morphologies, chemical element distribution and phase compositions of the coatings before and after thermal oxidation or hot corrosion were analyzed using scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD). The microstructure of the coating was Ni3Al matrix with dispersed ZrO2 particles, which was pure and compacted. The Ni3Al intermediate layer compactly formed between stainless steel substrate and ZrO2/Ni3Al composite coating, with good metallurgical bonding interfaces. The ZrO2/Ni3Al-Ni3Al double-layer coating exhibited a relatively high outmost microhardness of about 500 HV, and then gradually decreased from the coating to the substrate. When thermal oxidized or hot corroded at 1050 ℃, a mixed oxide layer of NiO, Al2O3 and NiAl2O4 formed on the coating surface, which effectively acted as a diffusion barrier for oxygen and corrosive substances, and thus demonstrated the good protective effect of ZrO2/Ni3Al coating.


2021 ◽  
Author(s):  
Changqing Ye ◽  
Yi Zou ◽  
Yanhu He ◽  
Youwen Lin ◽  
Dan Li ◽  
...  

Abstract Most studies of temporal and spatial distribution characteristics of droughts and floods analysis were conducted only from the perspective of a single factor (precipitation), while ignoring the impact of the characteristics of the underlying surface on the formation of droughts and floods. Using the daily precipitation data of 88 meteorological stations in Hainan province from 1970 to 2019, the 30m resolution DEM data, land use dataset, etc, the precipitation Z index is used to evaluate the drought and flood levels in Hainan province. The analysis results were revised by underlying surface data to evaluate the spatiotemporal characteristics of the drought and flood area in Hainan province. The drought-prone areas and flood prone areas in Hainan province were divided, and on this basis, the set pair analysis method was used to identify the regions with alternating drought and flood areas in Hainan. The results show that the overall arid area shows an obvious downward trend, while the flood area presents an increasing trend. The drought-prone areas throughout the year are more concentrated in the northeast of Hainan Province, while flood prone areas are mainly distributed in the eastern coastal areas. The regions where drought and flood occur alternately are small but concentrated. The drought and flood prone areas and alternate drought and flood areas before and after the revision by the underlying surface were compared. It can be seen that the overall trend is relatively similar and obvious before and after the revision. The result of drought areas before revision is 20.43 times larger than that after revision. The flood prone areas before revision are 8.50 times larger than that after revision. The alternating drought and flood areas before underlying surface revision in spring and summer are 17.50 times larger than that after revision. Similarly, it is 48.64 times in summer and autumn, and 17.62 times in autumn and winter. Finally, combining climate and underlying surface factors, suggestions are put forward for drought and flood prevention.


Processes ◽  
2018 ◽  
Vol 6 (8) ◽  
pp. 131 ◽  
Author(s):  
Zhipeng Li ◽  
Shucai Li ◽  
Haojie Liu ◽  
Qingsong Zhang ◽  
Yanan Liu

Subsection split grouting technology can effectively improve the grouting efficiency and homogeneity of grouting in a target reinforcement area. It is therefore necessary to clarify the reinforcement mechanism and characteristics of the soft filling medium under the condition of split grouting. A three-dimensional grouting simulation test of segmented split grouting in a soft filling medium was conducted. The distribution characteristics and thicknesses of the grouting veins were obtained under the condition of segmented grouting. The mechanical mechanism of segmented split grouting reinforcement, based on the distribution characteristics of different grouting veins, was revealed. After grouting, a uniaxial compression test and an indoor permeation test were conducted. Based on the method of the region-weighted average, the corresponding permeability coefficient and the elastic modulus of each splitting-compaction region were obtained. The quantitative relationship between the mechanical properties and the impermeability of the soft filling medium before and after grouting was established. The results revealed that three different types of veins were formed as the distance from the grouting holes increased; namely, skeleton veins, cross-grid grouting veins, and parallel dispersed grouting veins. The thicknesses of the grouting veins decreased gradually, whereas the number of grouting veins increased. Moreover, the strikes of the grouting vein exhibited increased randomness. The reinforcement effect of segmental split grouting on soft filling media was mainly confirmed by the skeleton support and compaction. The elastic modulus of the grouting reinforcement solid increased on average by a factor that was greater than 100, and the permeability coefficient decreased on average by a factor that was greater than 40 in the direction of the parallel grouting vein with the most impermeable solid. The research results may be helpful in the investigation of the split grouting reinforcement mechanism under the condition of segmented grouting.


2018 ◽  
Vol 232 ◽  
pp. 03014
Author(s):  
Ruilang Cao ◽  
Shijie Pang ◽  
Chang Huang ◽  
Chen Chen

In the construction of a deep tunnel with rich water and soft rock, accurate evaluations of the distribution characteristics of seepage field and water inflow are important bases for predicting the stability of tunnel surrounding rock and the disturbance state of groundwater environment. This paper used the Flac3D finite difference software seepage module, based on field geological borehole, measured seepage parameters and groundwater level. A three-dimensional numerical model of geological seepage in engineering area was established. The distribution characteristics of groundwater seepage field, the variation law of seepage field before and after tunnel excavation, and the water inflow during construction period were studied. As the tunnel was excavated, the excavated surface became a drainage channel, the isoline of groundwater pressure was changed into parallel non-parallel curve set by the parallel line of the initial seepage field. The nearer the tunnel centre was, the more obvious the variation tendency of groundwater pressure was. Grouting measures were very effective for tunnel water gushing, which not only reduced water inflow, but also effectively reduced the external water pressure of lining. It was infeasible to plug water when blocking the water without grouting and only adjusting the permeability of the lining.


1984 ◽  
Vol 85 (1) ◽  
pp. 95-101 ◽  
Author(s):  
S. S. Iyer ◽  
A. Choudhuri ◽  
M. B. A. Vasconcellos ◽  
U. G. Cordani

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