scholarly journals Experimental Research on the Impact of Ion Exchange and Infiltration on the Microstructure of Rare Earth Orebody

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Xiaojun Wang ◽  
Yulong Zhuo ◽  
Shuqiang Deng ◽  
Yongxin Li ◽  
Wen Zhong ◽  
...  
Keyword(s):  
Rare Earth ◽  
Ion Exchange ◽  
Pore Structure ◽  
Pore Size ◽  
Size Structure ◽  
Impact Factors ◽  
Leaching Process ◽  
Structure Changes ◽  
The Impact ◽  
Sole Action

To detect the evolutional characteristics of pore structure in ore leaching process of ion-type rare earth, this paper analyzes the influence mechanism of ion exchange seepage action on the microstructure of orebody, and an experiment for remodeling rare earth saturated samples and ore leaching was designed. Using nuclear magnetic resonance technology obtains the pore structure T2 map of H2O and (NH4)2SO4 solution in the ore leaching process and inverts and reconstitutes the pore structure distribution image. The results of contrastive analysis experiments indicate that impact factors of the ore leaching process on the microstructure of rare earth orebodies include two aspects: solution seepage and ion exchange. The main factor of pore structure distribution is the ion exchange action, determined by a dual effect. The sole action of solution seepage leads to an increase in pore size, which means that pore size structure is changing from small and medium to macro. Ion exchange gives rise to the movement and restructuring of particles, which results in a decrease in pore sizes. The pore structure changes from loose to compact; in the entire ore leaching process, the ion exchange action advances in a layered shape along the direction of seepage, and the chemical replacement and physical seepage alternately impact the microstructure of the orebodies.

scholarly journals Dynamic pore structure evolution of the ion adsorbed rare earth ore during the ion exchange process

2019 ◽  
Vol 6 (11) ◽  
pp. 191107 ◽  
Author(s):  
Lingbo Zhou ◽  
Xiaojun Wang ◽  
Yulong Zhuo ◽  
Kaijian Hu ◽  
Wen Zhong ◽  
...  
Keyword(s):  
Rare Earth ◽  
Ion Exchange ◽  
Pore Structure ◽  
Exchange Process ◽  
Structure Evolution ◽  
Seepage Rate ◽  
Leaching Process ◽  
Ion Exchange Process ◽  
Ore Body ◽  
Leaching Solution

During the leaching process of the ion-adsorbed rare earth (RE) ore, the pore structure evolution of the ore body plays a vital role in the seepage of the leaching solution. To investigate the evolution of the pore structure during the leaching process, experiments have been carried out with remodelled RE ore samples based on the physical characteristics of in situ ores. The seepage rate difference between deionized water leaching solution and 2% NH 4 Cl leaching solution during the active leaching period was analysed. The porosity and the dynamic pore size evolution of pore structures in the ore body are discussed. Results indicate that along with ion exchange between the RE ore and the leaching solution, the porosity of the sample remains constant and the pore structure shows a decreasing trend in the first part and an increasing trend in the second part. Specifically, during the ion exchange process, the number of minimal pores (0–5 µm), small pores (5–10 µm) and medium pores (10–25 µm) increases significantly and the number of medium–large pores (25–60 µm), large pores (60–120 µm) and mega pores (greater than 120 µm) decreases dramatically. Along with the completion of the ion exchange process, the evolution of porous structure shows an opposite trend. The mechanism study reveals that the evolution of pore structure is induced by the difference of ionic strength in the leaching solution during the ion exchange process, where the RE ore microparticles will be absorbed or desorbed on to the solid phase.

Recovery of rare earth elements from Dicranopteris dichotoma by an enhanced ion exchange leaching process

2018 ◽  
Vol 130 ◽  
pp. 208-213 ◽  
Author(s):  
Zeinab Chour ◽  
Baptiste Laubie ◽  
Jean Louis Morel ◽  
Yetao Tang ◽  
Rongliang Qiu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Ion Exchange ◽  
Rare Earth Elements ◽  
Leaching Process ◽  
Dicranopteris Dichotoma

PORE STRUCTURE RECONSTRUCTION AND MOISTURE MIGRATION IN POROUS MEDIA

Fractals ◽  
2014 ◽  
Vol 22 (03) ◽  
pp. 1440007 ◽  
Author(s):  
JIAYI ZHENG ◽  
XING SHI ◽  
JUAN SHI ◽  
ZHENQIAN CHEN
Keyword(s):  
Porous Media ◽  
Water Vapor ◽  
Diffusion Process ◽  
Pore Structure ◽  
Pore Size ◽  
Spectral Dimension ◽  
Anisotropic Porous Media ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion ◽  
The Impact

Three kinds of porous media (isotropic, perpendicular anisotropic and parallel anisotropic porous media) with the same porosity, different pore size distributions and fractal spectral dimensions were reconstructed by random growth method. It was aimed to theoretically study the impact of microscopic pore structure on water vapor diffusion process in porous media. The results show that pore size distribution can only denote the static characteristics of porous media but cannot effectively reflect the dynamic transport characteristics of porous media. Fractal spectral dimension can effectively analyze and reflect pores connectivity and moisture dynamic transport properties of porous media from the microscopic perspective. The pores connectivity and water vapor diffusion performance in pores of porous media get better with the increase of fractal spectral dimension of porous media. Fractal spectral dimension of parallel anisotropic porous media is more than that of perpendicular anisotropic porous media. Fractal spectral dimension of isotropic porous media is between parallel anisotropic porous media and perpendicular anisotropic porous media. Other macroscopic parameters such as equilibrium diffusion coefficient of water vapor, water vapor concentration variation at right boundary in equilibrium, the time when water vapor diffusion process reaches a stable state also can characterize the pores connectivity and water vapor diffusion properties of porous media.

The impact of sulfate ions on the ion exchange of rare earth elements

2019 ◽  
Vol 186 ◽  
pp. 12-20 ◽  
Author(s):  
Michael J. Page ◽  
James E. Quinn ◽  
Karin H. Soldenhoff
Keyword(s):  
Rare Earth ◽  
Ion Exchange ◽  
Rare Earth Elements ◽  
Sulfate Ions ◽  
The Impact

scholarly journals Strength Analysis of Porous YSZ Ceramics With the Same Porosity and Different Pore Structure

2021 ◽  
Author(s):  
ying lang ◽  
xin dai ◽  
lin zhao ◽  
Hong-Kang wei ◽  
chang-an wang
Keyword(s):  
Pore Structure ◽  
Pore Size ◽  
Young’S Modulus ◽  
Volume Fraction ◽  
Size Structure ◽  
Young's Modulus ◽  
Porous Ceramics ◽  
Strength Analysis ◽  
Large Pore ◽  
Small Pore

Abstract Porous YSZ ceramics with different pore structure were prepared by volume limiting foaming technology. Accurate porosity could achieve by this technology[1], so all samples were adjusted to density of 1g/m3 (porosity of about 82.6%). For the same density, the influence of porosity change on the strength was excluded. The effects of different pore structure on mechanical properties (compressive strength, strength-deformation curve and Young's modulus) were studied. The results showed that for porous ceramics with uniform pores the larger the pore size was, the smaller the Young's modulus and the lower the strength was. In addition, for samples with mix pores (large pore and small pore), when the volume fraction of macropores is large, the strength is the same as that of porous ceramics with uniform small pore size structure; when the volume fraction of small pores is large, the strength is the same as that of porous ceramics with uniform large pore size structure.

scholarly journals The impact of changes in pore structure on the compressive strength of sulphoaluminate cement concrete at high temperature

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
J.J.K. Tchekwagep ◽  
P. Zhao ◽  
S. Wang ◽  
S. Huang ◽  
X. Cheng
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Elevated Temperatures ◽  
Nitrogen Adsorption ◽  
Cement Concrete ◽  
Constant Weight ◽  
Sulphoaluminate Cement ◽  
Structure Changes ◽  
The Impact ◽  
The Relationship

Abstract The internal pore structure of sulphoaluminate cement concrete (SACC) significantly affects its mechanical properties. The main purpose of this study was to establish the relationship between pore structure changes and compressive strength after exposure to elevated temperatures. SACC samples that had been cured for 12 months were dried to a constant weight and then exposed to different temperatures (100 °C, 200 °C and 300 °C), after which the compressive strength and pore structure were measured. The pore structure of SACC was quantitatively described by mercury intrusion porosimetry (MIP) and nitrogen adsorption results. The results showed that with increased temperature, the porosity of the SACC samples also increased and the pore structure was gradually destroyed. Moreover, the SACC’s compressive strength gradually decreased with increasing temperature. The relationship between compressive strength and porosity was in close agreement with the compressive strength–porosity equation proposed by Schiller. Therefore, after extensive exposure to elevated temperature, the changes in SACC’s compressive strength can be quantitatively described by the Schiller equation.

scholarly journals Evolution of the pore structure during the early stages of the alkali-activation reaction: an in situ small-angle neutron scattering investigation

2017 ◽  
Vol 50 (1) ◽  
pp. 61-75 ◽  
Author(s):  
Claire E. White ◽  
Daniel P. Olds ◽  
Monika Hartl ◽  
Rex P. Hjelm ◽  
Katharine Page
Keyword(s):  
Neutron Scattering ◽  
Pore Structure ◽  
Pore Size ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Average Pore Size ◽  
Alkali Activation ◽  
Average Pore ◽  
Free Silica ◽  
The Impact

The long-term durability of cement-based materials is influenced by the pore structure and associated permeability at the sub-micrometre length scale. With the emergence of new types of sustainable cements in recent decades, there is a pressing need to be able to predict the durability of these new materials, and therefore nondestructive experimental techniques capable of characterizing the evolution of the pore structure are increasingly crucial for investigating cement durability. Here, small-angle neutron scattering is used to analyze the evolution of the pore structure in alkali-activated materials over the initial 24 h of reaction in order to assess the characteristic pore sizes that emerge during these short time scales. By using a unified fitting approach for data modeling, information on the pore size and surface roughness is obtained for a variety of precursor chemistries and morphologies (metakaolin- and slag-based pastes). Furthermore, the impact of activator chemistry is elucidated via the analysis of pastes synthesized using hydroxide- and silicate-based activators. It is found that the main aspect influencing the size of pores that are accessible using small-angle neutron scattering analysis (approximately 10–500 Å in diameter) is the availability of free silica in the activating solution, which leads to a more refined pore structure with smaller average pore size. Moreover, as the reaction progresses the gel pores visible using this scattering technique are seen to increase in size.

The Impact of Anglicizing Former German-Language Psychology Journals on Authorship and Citation Frequencies

2012 ◽  
Vol 17 (3) ◽  
pp. 190-198 ◽  
Author(s):  
Günter Krampen ◽  
Thomas Huckert ◽  
Gabriel Schui
Keyword(s):  
Side Effects ◽  
English Language ◽  
General Trend ◽  
Native Language ◽  
Impact Factors ◽  
German Language ◽  
Journal Articles ◽  
Number Of Citations ◽  
The Impact ◽  
Number Of Authors

Exemplary for other than English-language psychology journals, the impact of recent Anglicization of five former German-language psychology journals on (1) authorship (nationality, i.e., native language, and number of authors, i.e., single or multiple authorships), (2) formal characteristics of the journal (number of articles per volume and length of articles), and (3) number of citations of the articles in other journal articles, the language of the citing publications, and the impact factors (IF) is analyzed. Scientometric data on these variables are gathered for all articles published in the four years before anglicizing and in the four years after anglicizing the same journal. Results reveal rather quick changes: Citations per year since original articles’ publication increase significantly, and the IF of the journals go up markedly. Frequencies of citing in German-language journals decrease, citing in English-language journals increase significantly after the Anglicization of former German-language psychology journals, and there is a general trend of increasing citations in other languages as well. Side effects of anglicizing former German-language psychology journals include the publication of shorter papers, their availability to a more international authorship, and a slight, but significant increase in multiple authorships.

Sign in / Sign up

Export Citation Format

Share Document