COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2021
·
IF 4.539
Shuxin Huang,Jian Feng,Junxia Yu,Yi Wang,Jiequan Liu,Ruan Chi,Haobo Hou
Release of the remaining ammonium salts from the weathered crust elution-deposited rare earth ore (WCE-DREO) would pose a serious threat to the environment. Thus, in this study, the adsorption and desorption performances of the WCE-DREO and four minerals that composed it were investigated to select an efficient eluent for the remained ammonium removal. Results showed that the ammonium ion adsorbed on the WCE-DREO and the clay minerals as a monolayer, and the calculated adsorption capacities were as follows: montmorillonite > WCE-DREO > halloysite > illite > kaolinite due to their different structure. pH experiment showed that it had great effects on ammonium adsorption on both the WCE-DREO and the investigated clays. Kinetic experiments showed that ammonium sorption and desorption process were both a fast process. Co-ions experiments showed that Mg 2+ showed the highest inhibition effect on the ammonium adsorption on the WCE-DREO due to its ionic character. Based on this data, magnesium salt was chosen as the eluent, and results showed that more than 93 % of the remaining ammonium ion could be removed from the WCE-DREO in the batch and column experiments.
研究领域:
环境科学
·
矿物学
✓ 已验证
DOI
高影响因子
Minerals
·
2024
·Vol. 14
·期 4
·360
·
IF 2.2
Gaofeng Wang,Bowen Ling,Xiaoliang Liang,Jie Xu,Shichang Kang,Jingming Wei,Wei Tan,Runliang Zhu,Jianxi Zhu,Hongping He
Electrokinetic mining (EKM) is a novel method for rare earth element (REE) mining that can achieve green and efficient recovery of REEs. However, as yet, there is no accurate model for describing the electrokinetic transport of REEs in weathering crusts, and this hinders the wider application of EKM. The conventional model fails to capture the microscale transport physics occurring in the nanochannels that exist ubiquitously in weathering crusts. Consequently, the existing models cannot distinguish the mobilities of different REEs. Here, we report a new model for a more faithful description of the electrokinetic transport of REEs in weathering crusts that considers the ionic size, which has previously been neglected. We reveal that the electrokinetic transport of heavy REEs (HREEs) is faster than that of light REEs (LREEs) in weathering crusts, which is contrary to the predictions of conventional models. Our model was validated experimentally by measurements of the electrokinetic transport of two LREEs (La and Sm) and an HREE (Er) in weathering crusts. The speed of electrokinetic transport follows the order Er > Sm > La. Our findings suggest that the ionic size is a non-negligible factor affecting the electrokinetic transport of REEs in weathering crusts containing nanochannels. This work offers a constitutive model to describe the electrokinetic transport of REEs in weathering crusts, which promotes both theoretical developments and practical applications of EKM.
研究领域:
环境科学
·
矿物工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
MINERALS ENGINEERING
·
2022
·
IF 5.479
Fang Zhou,YiXin Zhang,Qi Liu,Suhua Huang,Xiaoyan Wu,Zhiwei Wang,Lisen Zhang,Ruan Chi
Weathered crust elution-deposited rare earth ores tailings are mainly composed of clay minerals, which can be used as efficient adsorption materials. In order to explore the possibility of recovering rare earth ions using tailings from mine waste liquid, the weathered crust elution-deposited rare earth ores tailings were modified to adsorb La 3+ and Y 3+ with respect to initial concentrations of La 3+ and Y 3+ , temperatures and impurity ions, and the adsorption kinetics and thermodynamics were further discussed to analyze the adsorption behavior. The results show a higher adsorption capacity of heavy rare earth Y 3+ than that of light rare earth La 3+ . The presence of impurity ions does not adversely affect adsorption of rare earth ions by the modified tailings. The adsorption performance is well fitted with the Langmuir adsorption isotherm model rather than the Freundlich adsorption isotherm model, and the maximum adsorption capacity is 0.0226 mmol/g and 0.0197 mmol/g for Y 3+ and La 3+ , respectively. Pseudo-first-order, pseudo-second-order, intraparticle diffusion and Elovich model were applied to fit the adsorption results. The results show that the adsorption process of modified tailings for La 3+ and Y 3+ is more in line with the pseudo-second-order kinetic model, suggesting the dominated chemical adsorption. The adsorption activation energies of La 3+ and Y 3+ on modified tailings are 11.60 KJ/mol and 7.60 KJ/mol, respectively. Thermodynamic studies show that the adsorption process of modified tailings for La 3+ and Y 3+ is a spontaneous endothermic reaction in the experimental temperature range. The recovery of rare earth ions form the modified tailings can be carried out by the leaching solution of weathered crust elution-deposited rare earth ores, 0.2 mol/L (NH 4 ) 2 SO 4 solution. In addition, the modified tailings are reversible and keep functionality to reuse in several cycles after elution process.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF RARE EARTHS
·
2024
·
IF 5.2
Aoyang Sha,Huifang Yang,Meiling Jiang,Zhengyan He,Zhenhu Liu,Zhigao Xu,Yaguang Du,Wu Ming,Ru'an Chi
Weathered crust elution-deposited rare earth ores (WREOs) are rich in medium and heavy rare earth. In order to improve the in-situ leaching process, which is prone to landslides and poor permeability, cationic hydroxyethyl cellulose (PQ-10) was used as a novel green swelling inhibitor and percolation promoter and was mixed with conventional leaching agent ammonium sulfate ((NH 4 ) 2 SO 4 ) to form a composite leaching agent to study the performance and mechanism of swelling inhibition and percolation promotion. Adding PQ-10 can inhibit the hydration swelling of WREOs, promote the percolation effect of the leaching agent, improve the rare earth (RE) leaching efficiency, and reduce the impurity aluminum (Al) leaching efficiency. Compared with the conventional leaching agent 2 wt% (NH 4 ) 2 SO 4 , the percolation time is reduced by 50% by using the composite leaching agent (0.02 wt% PQ-10+2 wt% (NH 4 ) 2 SO 4 ). PQ-10 has positively charged quaternary ammonium groups and hydrophilic group hydroxyl groups, which makes it easy to adsorb on WREOs multiple sites through electrostatic interaction and hydrogen bonding, weakening the electrostatic repulsion between mineral particles, reducing the WREOs interlayer spacing, compressing the double electric layer thickness at the solid-liquid interface, weakening the mineral hydration swelling and increasing the percolation rate. The long carbon chains of the polymer entangle and link the fine mineral particles to agglomerate them, increasing their particle size and reducing their hydration dispersion, and preventing blockage of the percolation pores caused by migration of the fine particles through the ore body with the solution. PQ-10 molecules also insert the mineral interlayer and expulsion of the internal water, further inhibiting the swelling of WREOs. Adding PQ-10 reduces the surface tension of (NH 4 ) 2 SO 4 solution, improving the spreading and spreading ability of the solution, reducing the adhesion work between molecules in the solid-liquid phase and the adhesion work reduction factor. It proves that PQ-10 promotes the percolation effect of the leaching process of WREOs. In addition, PQ-10 expands the leaching pore size and seepage channels, further improving the percolation rate.
研究领域:
矿物学
·
环境科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF RARE EARTHS
·
2022
·
IF 4.632
Zhengyan He,Rong Zhang,Aoyang Sha,Qin Zuo,Zhigao Xu,Ming Wu,Ru’an Chi
In order to inhibit the swelling of the clay minerals in the in-situ leaching process of weathered crust elution-deposited rare earth ores (WCE-DREO), diallyl dimethyl ammonium chloride (DMDACC) was introduced as an anti-swelling agent and combined with (NH 4 ) 2 SO 4 as a novel composite leaching agent. It can be found that the novel composite leaching agent exhibits a good anti-swelling performance and leaching capacity of rare earth , and has great potential on the actual exploitation of WCE-DREO. The anti-swelling mechanism of DMDACC was studied by characterization analysis. The results show that DMDACC with positive charges can be adsorbed on the clay particles by the electrostatic attraction and hydrogen bonds , and neutralize the negative charge of the clay particles. The double electrical layers are suppressed and the repulsion force between clay sheets decreases. It causes the clay particles prone to aggregate. Moreover, DMDACC can enter the interlayer and expel out the water molecules in interlayer. The interlayer spacing is decreased and the hydration swelling of the clay particles is weakened. It can provide a theoretical basis for the development of novel anti-swelling agents.
研究领域:
矿物学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
Journal of Central South University
·
2024
·Vol. 31
·期 2
·317-329
·
IF 3.7
Yang Hui-fang,Sha Ao-yang,He Zheng-yan,Wu Ming,Qu Jun,Wu Chen-jie,Xu Zhi-gao,Chi Ru-an
In order to solve landslides and slow infiltration rate in in-situ leaching process of weathered crust elution-deposited rare earth ore (WCE-DREO), the swelling inhibition performance and mechanism of polyethyleneimine (PEI) on montmorillonite (MMT) and WCE-DREO were investigated. The swelling inhibition effect on MMT and WCE-DREO increased gradually with increasing concentration of PEI. The leaching efficiency of rare earths was increased from 93.94% to 95.24% by the compound leaching agent consisting of 0.4% PEI and 2% ammonium sulfate compared to 2% ammonium sulfate alone, and the leaching time was reduced by about 33%. PEI can produce a large amount of —NH 3 + by hydrolysis, which can neutralize the negative charge on the interlamination and surfaces of clay minerals, reduce the electrostatic repulsion, and weaken the hydration and swelling of clay minerals. A polymeric film was formed on the clay particles by PEI coating, which changed the hydrophilicity of the particle surface, reduced water intrusion. Small particles were agglomerated by the wrapping and linking effects of long-chain PEI, thus increasing the particle size and facilitating the percolation of leaching agent. PEI skeleton also could embed in the clay interlayer and extrude the interlayer water, which inhibits the swelling of clay minerals.
研究领域:
土壤学
·
矿物学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF RARE EARTHS
·
2023
·
IF 4.9
Aoyang Sha,Huifang Yang,Zhengyan He,Zhigao Xu,Chenjie Wu,Wu Ming,Ru'an Chi
To solve the problems of the long development period, low mass transfer efficiency and high impurity content in the in-situ leaching process of weathered crust elution-deposited rare earth ores (WCE-DREO), cationic hydroxyethyl cellulose (PQ-10) was composited with conventional leaching agent ammonium sulfate ((NH 4 ) 2 SO 4 ) to form a novel composite leaching agent. The effects of PQ-10 concentration, leaching temperature and leaching flow rate of the composite leaching agent on the leaching kinetics and mass transfer processes of rare earth (RE) and aluminum (Al) were investigated. Compared to the single leaching agent (NH 4 ) 2 SO 4 , the composite leaching agent (2 wt% (NH 4 ) 2 SO 4 +0.02 wt% PQ-10) can reduce the RE leaching equilibrium time from 465 to 130 min and increase the RE leaching efficiency and decrease the Al leaching efficiency. It also facilitates the leaching process of WCE-DREO by increasing the peak concentrations of RE and Al, reducing the theoretical tower plate height (HETP) and improving the leaching mass transfer efficiency. It is indicated that PQ-10 can promote the leaching of WCE-DREO. The leaching process of the composite leaching system conforms to the diffusion kinetic control model. When the PQ-10 concentration is in the range of 0.005 wt% – 0.020 wt%, the reaction orders of RE and Al are 0.73 and 0.54, respectively, which shows a positive effect on the leaching velocity; when the PQ-10 concentration is in the range of 0.030 wt% – 0.060 wt%, the reaction orders of RE and Al are – 1.16 and – 0.75, respectively, which show a negative effect on the leaching velocity. In the range of 10 – 50 °C, the apparent activation energies of RE and Al are 15.02 and 17.31 kJ/mol, respectively, and the higher the leaching temperature, the smaller the HETP and the higher the leaching velocity and mass transfer efficiency. The increase in leaching flow rate contributes to the increase in the longitudinal diffusion velocity of the leaching agent within WCE-DREO, causing a shorter time for RE and Al to reach leaching equilibrium. In addition, the flow rate and HETP are consistent with the Van Deemter equation. At a flow rate of 0.8 mL/min, HETP was minimized and the optimal mass transfer efficiencies is achieved for RE and Al.
研究领域:
冶金工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2024
·
IF 8.2
Shichang Kang,Bowen Ling,Gaofeng Wang,Yongjin Xu,Jie Xu,Xiaoliang Liang,Jingming Wei,Wei Tan,Lingya Ma,Jianxi Zhu,Hongping He
In modern industries, rare earth elements (REEs) are considered as essential metals and invaluable natural resources . Ion-adsorption deposits (IADs) are repositories of REE in the weathering crust soils , in which REEs are adsorbed on clay minerals. In the last few decades, the mining of REEs from IADs has caused substantial environmental damage owing to the overuse of leaching agents for the desorption and transport of REEs in weathering crust soils . These environmental issues have sparked extensive research interest in modeling REE transport dynamics in weathering crust soils. Nevertheless, because current models treat REE adsorption and transport independently, they do not accurately describe REE transport dynamics. Therefore, in this study, a unified workflow that synergizes adsorption and transport dynamics is proposed to predict REE transport. The adsorption of REEs on IADs was found to follow the Freundlich isotherm with the coefficient of determination exceeding 0.9826. The adsorption capacities of La 3+ , Sm 3+ , Er 3+ , and Y 3+ reach 1.3127, 1.4423, 1.5793, and 1.1061 mg g −1 at 300 ppm, respectively. For the breakthrough curve , an advection–dispersion–adsorption–equation (ADAE) model was developed and utilized to accurately and reliably predict REE transport dynamics in soil columns. It was found the saturation time of REEs in soils is 39.22, 44.15, 50.64, and 32.17 h, respectively at 2 mL min −1 and decreased with the increase of flow velocity. The upper and lower limits of REE transport are ADAE-Freundlich and ADAE-Toth. More importantly, the model was applied to simulate REEs transport in field-scale weathering crusts over 100 years and predict REE accumulation in the highly weathered layered, which is found in natural weathering crusts. The qualitative prediction of REE transport dynamics in weathering crusts may help fundamentally lower the usage of leaching agents and mitigate concomitant the environmental impacts of mining.
研究领域:
环境科学
·
土壤学
·
工业生态学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
MINERALS ENGINEERING
·
2023
·
IF 4.8
Aoyang Sha,Huifang Yang,Zhengyan He,Qin Zuo,Zhigao Xu,Chenjie Wu,Ming Wu,Ru'an Chi
In-situ leaching process of weathered crust elution-deposited rare earth ore (WCE-DREO) often faces problems such as poor permeability and occurrence of landslides. The main reasons are the swelling of clay minerals by water absorption and blockage of seepage channels by fine particles. This study proposed using hydroxypropyl methyl cellulose (HPMC) as a novel green swelling inhibitor with the combination of ammonium sulfate ((NH 4 ) 2 SO 4 ) as an efficient composite leaching agent. The swelling inhibition performance of HPMC on swelling inhibition was evaluated through linear swelling tests and mud ball immersion tests. The mechanisms of HPMC on swelling inhibition and seepage promotion were analyzed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Scanning electron microscopy (SEM), Surface area analysis (BET), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TGA), and the contact angle, zeta potential and particle size distribution were characterized. The results indicated that HPMC showed a good performance on swelling inhibition, which improved with the increase of HPMC concentration. HPMC expels the water from the interlayer. Moreover, HPMC adsorbs onto the surface of clay minerals by hydrogen bonding to form a hydrophobic film, which can prevent the clay minerals from hydration swelling. Due to the electric neutrality property of HPMC, the electrostatic repulsion of clay minerals can be reduced. Therefore, the fine particles of the clay minerals can be bridged to form larger particles by the long carbon chain of HPMC which leads to expansion of the seepage channels as well as the improvement of the permeability of the ores. According to the column leaching tests, the novel leaching agent composed of 0.05 wt% HPMC and 2 wt% (NH 4 ) 2 SO 4 not only showed a good leaching capacity of rare earth, but also inhibited the swelling of clay and enhanced the seepage when comparing with traditional leaching agent ((NH 4 ) 2 SO 4 ). Developing a novel leaching agent benefits the green, safe and high-efficiency exploitation of WCE-DREO.
研究领域:
环境科学
·
材料科学
·
化学工程
·
采矿工程
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）