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Luo Y, Zhang Z, Lin J, Owens G, Chen Z, Chen Z. Rare earth elements redistribution in mine tailings soil: A comparative study of sunlit and shady slopes after in-situ leaching. JOURNAL OF HAZARDOUS MATERIALS 2024; 476:135095. [PMID: 38996682 DOI: 10.1016/j.jhazmat.2024.135095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2024] [Revised: 06/29/2024] [Accepted: 07/01/2024] [Indexed: 07/14/2024]
Abstract
The in-situ leaching of rare earth minerals results in ecological differences between sunlit and shady slopes, which may be related to differences in the distribution REEs in the associated soil matrices. Studies of REEs mine tailings in Southern China indicated higher total concentrations of REEs on sunlit slopes compared to shady ones. Specifically, the exchangeable REEs fraction (F1-REEs) was higher on the shady slopes, whereas the Fe/Mn oxides bound REEs fraction (F3-REEs) was higher on the sunlit slopes. In addition, light REE (LREE) concentrations were lower at lower elevations. With the exception of the Ce fraction which remained stable, this indicated a change in all REEs distributions, moving from F1-REEs towards the residual fraction. Hierarchical cluster and principal component analysis revealed a strong correlation between F3-REEs, organic matter bound REEs (F4-REEs), and LREEs, and a positive association of F3-REEs with sunlight exposure. Partial Least Squares Path Modeling analysis suggested that OM promoted the conversion of LREEs to F3 and F4-REEs in soil driven by sunlight exposure. Additionally, as the Feo/Fed ratio decreased, more LREEs were converted to F3. This study suggests that sunlight and elevation both play a critical role in the geochemical dynamics of REEs in in-situ tailings, advocating for environmental evaluations to be undertaken in order to accurately understand the ecological impacts of rare earth mining.
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Affiliation(s)
- Yunxiao Luo
- Fujian Key Laboratory of Pollution Control and Resource Reuse, College of Environmental and Resource Sciences, Fujian Normal University, Fuzhou 350117, Fujian Province, China
| | - Zhenjun Zhang
- Fujian Key Laboratory of Pollution Control and Resource Reuse, College of Environmental and Resource Sciences, Fujian Normal University, Fuzhou 350117, Fujian Province, China
| | - Jiajiang Lin
- Fujian Key Laboratory of Pollution Control and Resource Reuse, College of Environmental and Resource Sciences, Fujian Normal University, Fuzhou 350117, Fujian Province, China.
| | - Gary Owens
- Environmental Contaminants Group, Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - Zhibiao Chen
- Key Laboratory for Humid Subtropical Eco-Geographical Processes of the Ministry of Education, Fujian Normal University, Fuzhou 350117, Fujian Province, China
| | - Zuliang Chen
- Environmental Contaminants Group, Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia.
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Shi J, Jiang L, Yang J, Guo Z, Li K, Peng Y, Ibrahim N, Liu H, Liang Y, Yin H, Liu X. Transport Behavior of Cd 2+ in Highly Weathered Acidic Soils and Shaping in Soil Microbial Community Structure. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2024; 86:73-89. [PMID: 38117305 DOI: 10.1007/s00244-023-01046-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 11/25/2023] [Indexed: 12/21/2023]
Abstract
The mining and smelting site soils in South China present excessive Cd pollution. However, the transport behavior of Cd in the highly weathered acidic soil layer at the lead-zinc smelting site remains unclear. Here, under different conditions of simulated infiltration, the migration behavior of Cd2+ in acid smelting site soils at different depths was examined. The remodeling effect of Cd2+ migration behavior on microbial community structure and the dominant microorganisms in lead-zinc sites soils was analyzed using high-throughput sequencing of 16S rRNA gene amplicons. The results revealed a specific flow rate in the range of 0.3-0.5 mL/min that the convection and dispersion have no obvious effect on Cd2+ migration. The variation of packing porosity could only influence the migration behavior by changing the average pore velocity, but cannot change the adsorption efficiency of soil particles. The Cd has stronger migration capacity under the reactivation of acidic seepage fluid. However, in the alkaline solution, the physical properties of soil, especially pores, intercept the Cd compounds, further affecting their migration capacity. The acid-site soil with high content of SOM, amorphous Fe oxides, crystalline Fe/Mn/Al oxides, goethite, and hematite has stronger ability to adsorb and retain Cd2+. However, higher content of kaolinite in acidic soil will increase the potential migration of Cd2+. Besides, the migration behavior of Cd2+ results in simplified soil microbial communities. Under Cd stress, Cd-tolerant genera (Bacteroides, Sphingomonas, Bradyrhizobium, and Corynebacterium) and bacteria with both acid-Cd tolerance (WCHB 1-84) were distinguished. The Ralstonia showed a high enrichment degree in alkaline Cd2+ infiltration solution (pH 10.0). Compared to the influence of Cd2+ stress, soil pH had a stronger ability to shape the microbial community in the soil during the process of Cd2+ migration.
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Affiliation(s)
- Jiaxin Shi
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Luhua Jiang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China.
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China.
| | - Jiejie Yang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Ziwen Guo
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Kewei Li
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Yulong Peng
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Nazidi Ibrahim
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Hongwei Liu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Yili Liang
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Huaqun Yin
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
| | - Xueduan Liu
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
- Key Laboratory of Biometallurgy of Ministry of Education, Central South University, Changsha, 410083, China
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Jia YG, Yan Z, Shang L, Chen J. Environmental risk of ion-absorbed rare earth ores: concentration of leaching agent and fractionation of Pb. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024; 31:6425-6436. [PMID: 38151558 DOI: 10.1007/s11356-023-31516-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 12/08/2023] [Indexed: 12/29/2023]
Abstract
Rare earth (RE) is an important strategic resource; however, there has been a growing concern about the environmental problems caused by RE mining, such as ammonia nitrogen pollution and heavy metal pollution. There is a limited research about the behavior of leaching agents and the fractionation of RE and heavy metal during the mining process for ion adsorption of rare earth ore (IRE-ore) in the previously available papers. In this study, (NH4)2SO4 solution, which commonly used in the production of mining IRE-ore, was used as a leaching agent. The adsorption behavior of ore soils on ammonium ions was explored by batch experiments. The adsorption process of IRE-ore on ammonium ions followed a pseudo-second-order equation and was controlled by the kinetics of surface adsorption and intra-particle diffusion; the ammonium ion adsorption isotherm conformed to the Freundlich isotherm equilibrium equation, and the higher concentration advantage made the ore soils possess a higher adsorption capacity of ammonium ion. In addition, the fractionation characteristics of lanthanum (La), cerium (Ce), and lead (Pb) in the ore soil during the leaching process were simulated based on the batch and column leaching experiments. The results demonstrated that the exchangeable states of La and Ce in IRE-ore were high, and the exchangeable, carbonate-bound La and Ce were almost all leached out by (NH4)2SO4 leaching agent, while the most of exchangeable Pb flowed out along with leaching agent, and a small amount of leached Pb in the ore soil was converted to iron and manganese oxide-bound Pb and enriched in the direction of migration of the leaching solution, and when the environment (e.g., pH and Eh) changed, this part of Pb may be re-activated. Our research might serve as crucial baseline knowledge for the adsorption of ammonium ions by ore soils, and provide a data reference for reducing the use of leaching agents and developing sustainable technologies for green mining of ion-adsorption RE ores.
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Affiliation(s)
- Ying Gang Jia
- China University of Geosciences, Beijing, 100083, China
| | - Zhenli Yan
- China University of Geosciences, Beijing, 100083, China
| | - Liannan Shang
- China University of Geosciences, Beijing, 100083, China.
- Center of Xi'an Mineral Resources Survey, CGS, Xi'an, 710100, China.
| | - Jian Chen
- China University of Geosciences, Beijing, 100083, China
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Qi S, Li X, Luo J, Han R, Chen Q, Shen D, Shentu J. Soil heterogeneity influence on the distribution of heavy metals in soil during acid rain infiltration: Experimental and numerical modeling. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2022; 322:116144. [PMID: 36067661 DOI: 10.1016/j.jenvman.2022.116144] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/12/2022] [Accepted: 08/28/2022] [Indexed: 06/15/2023]
Abstract
Acid rain is a global environmental problem that mobilizes heavy metals in soils, while the distribution and geochemical fraction of heavy metals during acid rain infiltration in heterogeneous soils are still unclear. In this study, we performed column experiments to investigate the distribution and geochemical fraction of Cu, Pb, Ni and Cd in heterogeneously layered soils during continuous acid rain infiltration. Chloride ion used as a conservative tracer was found to be uniformly distributed during acid rain infiltration, showing insignificant preferential flow effects in the column. In contrast, however, the distribution of heavy metals was highly non-uniform, especially in the silty soil at the lower part of the column, indicating a heterogeneous distribution of adsorption capacity. In addition, in the control experiments with neutral rain infiltration, uniform distribution of heavy metals was observed, indicating that the heterogeneous distribution of adsorption coefficient during acid rain infiltration was mainly caused by different pH buffering capacities. A numerical model considering water flow and solute transport was developed, where the average water-solid distribution coefficient (Kd) in Layer 2 was only 1.5-12.5% of that in Layer 1 during acid rain infiltration. The model could predict the variation of heavy metal concentrations in soil with the majority of error less than 35%, confirming that different Kd induced the heterogeneous distribution of heavy metals. In addition, the geochemical fraction of heavy metals in the upper coarse sand layer remained stable, while the acid-extractable fractions in the lower loam and silt loam layer gradually increased. Our findings suggest that soil heterogeneity, especially chemical heterogeneity affected by rainfall acidity, has an important influence on the infiltration, migration and geochemical fraction of heavy metals in soils. This study could help guide the risk assessment of heavy metal-contaminated sites that were polluted by acid rain or landfill leachate.
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Affiliation(s)
- Shengqi Qi
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Gongshang University, Hangzhou, 310012, PR China; Instrumental Analysis Center of Zhejiang Gongshang University, Hangzhou, 310012, PR China; International Science and Technology Cooperation Platform for Low-Carbon Recycling of Waste and Green Development, Zhejiang Gongshang University, Hangzhou, 310012, China
| | - Xiaoxiao Li
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Gongshang University, Hangzhou, 310012, PR China
| | - Jian Luo
- School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0355, United States
| | - Ruifang Han
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Gongshang University, Hangzhou, 310012, PR China
| | - Qianqian Chen
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Gongshang University, Hangzhou, 310012, PR China
| | - Dongsheng Shen
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Gongshang University, Hangzhou, 310012, PR China; Instrumental Analysis Center of Zhejiang Gongshang University, Hangzhou, 310012, PR China; International Science and Technology Cooperation Platform for Low-Carbon Recycling of Waste and Green Development, Zhejiang Gongshang University, Hangzhou, 310012, China.
| | - Jiali Shentu
- Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Zhejiang Gongshang University, Hangzhou, 310012, PR China; Instrumental Analysis Center of Zhejiang Gongshang University, Hangzhou, 310012, PR China; International Science and Technology Cooperation Platform for Low-Carbon Recycling of Waste and Green Development, Zhejiang Gongshang University, Hangzhou, 310012, China.
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5
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Tang J, Qiao J, Xue Q, Liu F, Fan X, Liu S, Huang Y. Behavior and mechanism of different fraction lead leach with several typical sulfate lixiviants in the weathered crust elution-deposited rare earth ore. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:31885-31894. [PMID: 33619617 DOI: 10.1007/s11356-021-13039-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
Recently, some new leaching agents without ammonium, such as magnesium sulfate (MgSO4) and aluminum sulfate [Al2(SO4)3], have been developed to eliminate ammonia nitrogen pollution in in situ mining process of the weathered crust elution-deposited rare earth ore (WCED-REO), but they might cause heavy metal contamination. In this study, characteristics and mechanisms of different fractions of lead (Pb) released by (NH4)2SO4, MgSO4 and Al2(SO4)3 leaching agents were investigated using batch experiments and column leaching tests. The experimental results showed that the amounts of Pb released by the different leaching agents followed the trend of Al2(SO4)3 > (NH4)2SO4 > MgSO4 under the same total cationic charge, and both the acid extractable and reducible fractions of Pb were released. The release of acid extractable fraction Pb was related to the cation hydration radius of NH4+, Mg2+, and Al3+, whereas the release of reducible fraction Pb was mainly influenced by the concentration of H+, especially at pH < 4.0. Furthermore, column leaching tests indicated that pH has little effect on the Pb contents of different fractions released by (NH4)2SO4 and MgSO4 in leaching the WCED-REO. Although Al2(SO4)3 released the largest contents of rare earth and Pb in leachate, the content of residual acid extractable fraction Pb in soil was the most after water injection (simulating the cleaning process after mining). This work can provide a scientific method and theoretical basis for comprehensively assessing the environmental impact of new leaching agents on WCED-REO mining.
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Affiliation(s)
- Jie Tang
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, 100083, People's Republic of China
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, People's Republic of China
| | - Jiyang Qiao
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, 100083, People's Republic of China
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, People's Republic of China
| | - Qiang Xue
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, 100083, People's Republic of China.
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, People's Republic of China.
| | - Fei Liu
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, 100083, People's Republic of China
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, People's Republic of China
| | - Xin Fan
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing, 100083, People's Republic of China
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, People's Republic of China
| | - Siwen Liu
- National Research Center for Geoanalysis, Beijing, 100037, China.
- Key Laboratory of Ministry of Natural Resources for Eco-geochemistry, Beijing, 100037, China.
| | - Yuanying Huang
- National Research Center for Geoanalysis, Beijing, 100037, China
- Key Laboratory of Ministry of Natural Resources for Eco-geochemistry, Beijing, 100037, China
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Migration and Transformation of Heavy Metals in the Soil of the Water-Level Fluctuation Zone in the Three Gorges Reservoir under Simulated Nitrogen Deposition. J CHEM-NY 2021. [DOI: 10.1155/2021/6660661] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The accumulation of heavy metals (HMs) in the water-level fluctuation zone (WLFZ) of the Three Gorges Reservoir (TGR) area is potentially harmful to the water environment. In order to reveal whether nitrogen (N) deposition is a potential driving factor for the migration and transformation of HMs (Cd, Cr, Cu, Ni, and Pb), a simulated N deposition experiment was performed on the soil in the WFLZ of the TGR. The results showed that the accumulative release amounts of HMs increased with the increase of N deposition. It was found that the Elovich equation, double-constant equation, and parabolic diffusion equation could well describe the release process of Cu, Cd, Cr, and Ni, while the double-constant equation, parabolic diffusion equation, and first-order equation could be applicable for Pb. The exchangeable fractions of HMs increased to varying degrees after the N deposition treatment, wherein Ni was most significant, indicating that N deposition could increase the ecological risk of HM pollution in the TGR area. The results provide insight into the major factors affecting the release of different HMs under N deposition in this vulnerable region ecologically.
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Fan X, Xue Q, Liu S, Tang J, Qiao J, Huang Y, Sun J, Liu N. The influence of soil particle size distribution and clay minerals on ammonium nitrogen in weathered crust elution-deposited rare earth tailing. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 208:111663. [PMID: 33396173 DOI: 10.1016/j.ecoenv.2020.111663] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/31/2020] [Accepted: 11/12/2020] [Indexed: 06/12/2023]
Abstract
Even after being abandoned for many years, a large number of weathered crust elution-deposited rare earth (WCED-RE) tailings continue to release ammonia nitrogen (AN) pollution into their surrounding environments. However, the influences of particle size distribution and clay minerals on AN pollution caused by these tailings have been insufficiently studied, and its causes are poorly understood. In this study, soil samples at different depths (5, 7, 9, 11 and 14 m) were collected from a rare earth tailing in Ganzhou City, Jiangxi Province, China. Particles were screened by size into six groups (2-1, 1-0.5, 0.5-0.25, 0.25-0.1, 0.1-0.075 and < 0.075 mm), and AN forms were extracted. The results showed that as soil particle size decreases, both soil specific surface area and clay content increase, leading to stronger AN enrichment ability. With increased sampling depth, the distribution of clay across the six particle fractions became more uniform, such that the accumulation of AN in soil with fine particle size was less obvious. Clay minerals with different capacities for AN enrichment vary with sampling depth. This variation is responsible for the profile of AN distribution in the mine, where AN first increases and then decreases as vertical depth is increased. Although AN content was highest at 11 m, water soluble AN content was higher in the upper part of the completely weathered layer (5 and 7 m), which poses a higher environmental risk. This study provides significant information to deepen our understanding of the distribution characteristics of AN and its main influencing factors, as well as a foundation for the prevention and remediation of nitrogen pollution from WCED-RE tailings.
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Affiliation(s)
- Xin Fan
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China; Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Qiang Xue
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China; Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China.
| | - Siwen Liu
- National Research Center for Geoanalysis, Beijing 100037, China; Key Laboratory of Ministry of Natural Resources for Eco-geochemistry, Beijing 100037, China
| | - Jie Tang
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China; Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Jiyang Qiao
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China; Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - Yuanying Huang
- National Research Center for Geoanalysis, Beijing 100037, China; Key Laboratory of Ministry of Natural Resources for Eco-geochemistry, Beijing 100037, China
| | - Jingmin Sun
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China; Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China
| | - NanNan Liu
- MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences (Beijing), Beijing 100083, China; Beijing Key Laboratory of Water Resources and Environmental Engineering, China University of Geosciences (Beijing), Beijing 100083, China
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8
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Zhang Q, Ren F, Li F, Chen G, Yang G, Wang J, Du K, Liu S, Li Z. Ammonia nitrogen sources and pollution along soil profiles in an in-situ leaching rare earth ore. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 267:115449. [PMID: 33254692 DOI: 10.1016/j.envpol.2020.115449] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/18/2020] [Accepted: 08/15/2020] [Indexed: 06/12/2023]
Abstract
The ammonium sulphate ((NH4)2SO4) in-situ leaching process is the most widely used extraction technology for weathered crust elution-deposited rare earth ores (WCED-REOs). Highly concentrated (NH4)2SO4, a representative leaching agent, is often used in the leaching process of WCED-REOs. However, this in-situ leaching process causes nitrogen pollution in the soil, surrounding surface and ground water due to the high concentrations of (NH4)2SO4 solutions used as a long term leaching agent. To date, the mechanism behind the variations in ammonia nitrogen (AN) in deep soil profiles is unclear. We conducted vertical and lateral soil sampling and analyzed the collected samples for soil moisture, pH, ammonia forms, and AN contents in soil profiles deeper than 500 cm in an in-situ leaching mining area of Ganzhou, Jiangxi Province, southern China. The results show that primary chemical pollutants in the soil are derived from residual leaching agents with high acidities and concentrations of AN. Twelve years after the mining process was completed, the mean pH values of the tailings in the mining area were 3.90 and 4.87 in its lower reaches. Due to the presence of chemical residues, the AN concentration was 12-40 times higher than that of the raw ore soil before it was mined. The percentages of different ammonium forms in the rare earth tailing soil were 65%, 30%, and 5% for the water-soluble, exchangeable, and fixed ammonium forms, respectively. The results of this study support effective prevention and remediation treatment of environmental problems caused by AN pollution of the soil in WCED-REOs.
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Affiliation(s)
- Qiuying Zhang
- Chinese Research Academy of Environmental Sciences, Beijing, China.
| | - Futian Ren
- College of Water and Architectural Engineering, Shihezi University, Shihezi, China; Institute of Geographic Sciences and Natural Resources Research, Beijing, China; Xinjiang Production and Construction Group Key Laboratory of Modern Water-Saving Irrigation, Shihezi, China.
| | - Fadong Li
- College of Water and Architectural Engineering, Shihezi University, Shihezi, China; Institute of Geographic Sciences and Natural Resources Research, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
| | | | - Guang Yang
- College of Water and Architectural Engineering, Shihezi University, Shihezi, China; Xinjiang Production and Construction Group Key Laboratory of Modern Water-Saving Irrigation, Shihezi, China.
| | - Jianqi Wang
- Institute of Geographic Sciences and Natural Resources Research, Beijing, China.
| | - Kun Du
- Institute of Geographic Sciences and Natural Resources Research, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Shanbao Liu
- Institute of Geographic Sciences and Natural Resources Research, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Zhao Li
- Institute of Geographic Sciences and Natural Resources Research, Beijing, China; University of Chinese Academy of Sciences, Beijing, China.
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9
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Qiao J, Tang J, Xue Q. Study on Pb release by several new lixiviants in weathered crust elution-deposited rare earth ore leaching process: Behavior and mechanism. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2020; 190:110138. [PMID: 31901809 DOI: 10.1016/j.ecoenv.2019.110138] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/22/2019] [Accepted: 12/25/2019] [Indexed: 06/10/2023]
Abstract
New leaching agents could lead to a reduction in ammonia nitrogen pollution and the supplementation of soil nutrients during in-situ mining. They could also result in the release of even more toxic heavy metals, which has an impact on the environment as well as human health. In this study, column leaching experiments were used to simulate in-situ leaching, and the leaching behavior and fractional changes of lead in weathered crust elution-deposited rare earth ore by different leaching agents were studied. The experimental results showed that the amount of lead that was leached followed the order of CLA (60% CaCl2 + 25% NH4Cl + 15% MgSO4) > (NH4)2SO4 > MgSO4. The lead leaching process was comprised of both an acceleration and deceleration stage that followed the first order kinetic model. The amount of Pb when using compound agent was the greatest most likely because of the presence of Cl-. The soil heavy metal morphology test showed that the three leaching agents primarily leached acid extractable lead, and the compound leaching agent leached the greatest amount of acid extractable Pb, which mainly due to the presence of NH4Cl. The reducible fraction was enriched in the direction of migration of the leachate, which was due to the presence of SO42-. These results indicate that the introduction of leaching agents during the mining process pose a greater risk for the release of heavy metals and provide a theoretical basis for the prevention and remediation of heavy metal pollution in mining areas where new leaching agents were used.
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Affiliation(s)
- Jiyang Qiao
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China
| | - Jie Tang
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China
| | - Qiang Xue
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences (Beijing), Beijing, 100083, PR China.
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Tang J, Qiao J, Xue Q, Liu F, Chen H, Zhang G. Leach of the weathering crust elution-deposited rare earth ore for low environmental pollution with a combination of (NH 4) 2SO 4 and EDTA. CHEMOSPHERE 2018; 199:160-167. [PMID: 29438942 DOI: 10.1016/j.chemosphere.2018.01.170] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Revised: 01/26/2018] [Accepted: 01/31/2018] [Indexed: 06/08/2023]
Abstract
High concentration of ammonium sulfate, a typical leaching agent, was often used in the mining process of the weathering crust elution-deposited rare earth ore. After mining, a lot of ammonia nitrogen and labile heavy metal fractions were residual in tailings, which may result in a huge potential risk to the environment. In this study, in order to achieve the maximum extraction of rare earth elements and reduce the labile heavy metal, extraction effect and fraction changes of lanthanum (La) and lead (Pb) in the weathering crust elution-deposited rare earth ore were studied by using a compound agent of (NH4)2SO4-EDTA. The extraction efficiency of La was more than 90% by using 0.2% (NH4)2SO4-0.005 M EDTA, which was almost same with that by using 2.0% (NH4)2SO4 solution. In contrast, the extraction efficiency of Pb was 62.3% when use 0.2% (NH4)2SO4-0.005 M EDTA, which is much higher than that (16.16%) achieved by using 2.0% (NH4)2SO4 solution. The released Pb fractions were mainly acid extractable and reducible fractions, and the content of reducible fraction being leached accounted for 70.45% of the total reducible fraction. Therefore, the use of 0.2% (NH4)2SO4-0.005 M EDTA can not only reduce the amount of (NH4)2SO4, but also decrease the labile heavy metal residues in soil, which provides a new way for efficient La extraction with effective preventing and controlling environmental pollution in the process of mining the weathering crust elution-deposited rare earth ore.
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Affiliation(s)
- Jie Tang
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Jiyang Qiao
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Qiang Xue
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China.
| | - Fei Liu
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Honghan Chen
- Beijing Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing, 100083, PR China
| | - Guochen Zhang
- Beijing Z.D.H.K. Environmental Science & Technology Co., Ltd, Beijing, 100011, PR China
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