Ion-adsorption Rare Earth Research Articles

Theoretical investigation of hydrated [Lu(OH)2]+ adsorption on kaolinite(0 0 1) surface with DFT calculations

Kaolinite is a major mineral present in ion-adsorption rare earth ores, which are the primary source of lutetium (Lu). In those ores, Lu is mainly found to be adsorbed on the kaolinite surface in the form of hydrated or hydroxyl-hydrated ions, and can therefore be desorbed by ion-exchange leaching. This study used density functional theory calculations to investigate the adsorption mechanisms and bonding nature of hydrated [Lu(OH)2]+ ions on the kaolinite (0 0 1) surface. Lu3+ exhibited directed tendency geometry with high coordination number of nine. [Lu(OH)2(H2O)6]+, the most stable ion in aqueous system, was considered as the initial structure for the adsorption models. To investigate bonding between hydrated [Lu(OH)2]+ and the kaolinite surface, outer-layer (related to hydrogen bonding) and inner-layer (related to coordination bonding) adsorption models were applied. The surface charge and HOMO distribution of the deprotonated Al-OH surface were also investigated. Owing to the high reactivity of the deprotonated hydroxyls, inner-layer adsorption was dominated by coordination bonds between Lu and surface oxygen, with bidentate complexation at Ol site giving the largest adsorption energy (-663.86 kJ/mol). Moreover, partial density of state projections and Mulliken bond populations showed that the antibonding combination of Lu 5d and Os 2p is the dominant orbital contribution of Lu and surface oxygen. These insights into the Lu adsorption mechanism can aid in developing improved ion-exchange leaching techniques.

Simultaneous hyperaccumulation of rare earth elements, manganese and aluminum in Phytolacca americana in response to soil properties

The plant Phytolacca americana L. simultaneously hyperaccumulates manganese (Mn) and rare earth elements (REEs), but the underlying mechanisms are largely unknown. In this study, P. americana and the corresponding rhizosphere soil samples were collected from an ion-adsorption REE mine area in China, and the elemental composition and soil properties were analyzed in order to explore the relationship between metal accumulation and soil properties. The results show that P. americana accumulates high concentrations of REEs (up to 1040 mg kg−1), Mn (up to 10400 mg kg−1) and aluminum (Al) (up to 5960 mg kg−1) in leaves. The REE concentrations in leaves were positively correlated with those of Al, Fe and Zn, while light REE concentrations were negatively correlated with P concentrations (p < 0.05). The soil properties explained 81.7%, 72.9% and 67.1% of REEs, Mn and Al accumulated in P. americana, respectively. The variation of REE accumulation in P. americana was primarily explained by plant available P (24.4%), pH (12.9%), TOC (9.4%) and total P (7.7%). The accumulation of Mn was primarily explained by plant available REEs (42.9%) and available Al (13.1%) while Al in P. americana was primarily explained by soil pH (14.4%). This study suggests the potential by regulation of soil properties in improving the efficiency of phytoextraction for REEs by hyperaccumulators.

Extraction mechanism and separation behaviors of low-concentration Nd3+ and Al3+ in P507–H2SO4 system

In order to clarify the solvent extraction and separation behaviors of rare earths and impurity of Al during the extraction and enrichment of low-concentration leach solution of ion-adsorption rare earth ore, the extraction mechanism and separation behaviors of Nd3+ and Al3+ in the Nd2(SO4)3–Al2(SO4)3 mixed solution using P507 were studied in this work. The extraction of Nd3+ and Al3+ follows the cation exchange mechanism. With the increase of the equilibrium pH, βNd/Al in the extraction of the Nd2(SO4)3–Al2(SO4)3 mixed solution using P507 is always higher than that in the extraction of single Nd2(SO4)3 and Al2(SO4)3 solutions. It can be attributed to the fact that the extraction of Nd3+ using P507 is much faster than that of Al3+, and Al3+ is more prone to be hydrolyzed at lower pH. βNd/Al in the extraction of the Nd2(SO4)3–Al2(SO4)3 mixed solution decreases gradually with the increase of mixing time within the equilibrium pH range of 1.5–1.9. The extraction of Nd3+ using P507 is much faster than that of Al3+, but the stability of Al3+-loaded organic phase is better than that of Nd3+-loaded organic phase, thus Nd3+ in the Nd3+-loaded organic phase is gradually replaced by Al3+ in the aqueous phase with the increase of mixing time.

Industrial Ramie Growing on Reclaimed Ion-Adsorption Rare Earth Elements Mine Tailings in Southern China: Defibration and Fibers Quality

Ramie plants (Boehmeria nivea) have been cultivated on ion-adsorption rare earth elements (REEs) mine tailings and showed a low ability to accumulate REEs, especially in the stems (ΣREE = 24 ± 17 mg kg−1) with higher concentration in leaves and roots (ΣREE = 57 to 66 mg kg−1). Ramie individual fibers were isolated using three degumming processes: a traditional alkali treatment (AT), a steam explosion (SE) treatment after a neutral (SEN) or after a basic (SEB) impregnation. Cellulose-rich (> 80%) fine fibers with very low amounts of non-cellulosic sugars (< 5%), low REE concentrations (ΣREE ≈ 4–6 mg kg−1) and a high mechanical strength (tensile strength ≈ 260–540 cN/fiber, breaking point ≈ 20–50 cN/fiber) have been produced. However, SE degumming resulted in more degraded fibers with cracks slightly affecting their tensile properties.

Adsorption of hydrated [Y(OH)2]+ on kaolinite (001) surface: Insight from DFT simulation

Yttrium (Y) is a crucial rare earth element, and it is found in the ion-adsorption rare earth ore of Jiangxi province, China, at a percentage of up to 64.9%. This study used density functional theory calculations to investigate the adsorption behaviour and bonding mechanisms of the Y ion on the surface of kaolinite (001). Understanding these would be beneficial for its mineralisation processing and exploitation. [Y(OH)2(H2O)7]+ was studied as the initial adsorption structure with the lowest binding energy of −1629.19 kJ/mol in an aqueous system. The adsorption models were divided into outer-layer and inner-layer adsorption models based on the adsorption energy and bonding mechanisms. It was found that [Y(OH)2(H2O)7]+ preferred to adsorb on the Al-OH surface with inner-layer adsorption mainly via the coordination bond of Y–Os, and through hydrogen bonds for outer-layer adsorption. In the outer-layer adsorption, the adsorption energy of [Y(OH)2(H2O)7]+ on the Al-OH surface was higher than that on the Si–O surface because of the steric hindrance effect of the H in the hydroxyl of the Al-OH surface. The Mulliken bond populations of Y–Os for inner-layer adsorption showed that it was primarily dominated by the bonding orbital.

Scandium recovery from ion-adsorption rare earth concentrate with HEHEHP as extractant

An excellent extraction selectivity towards Sc over other REEs in 4 mol/L HCl solution was achieved with the separation factor βSc/REEs over 8000 by 2-ethylhexyl phosphoric acid mono 2-ethylhexyl ester (HEHEHP) and the extraction equilibrium can be obtained within 20 min. The extracted Sc can be stripped using 5 mol/L NaOH solution as eluent at 363 K with the stripping rate of 92.1% obtained. The extraction mechanism was clearly elucidated by slope analysis, saturation extraction, IR, and NMR analysis. It was revealed that the extraction of Sc in 4 mol/L HCl solution is still dominated by cation exchange process between P—O—H and Sc, and coordination process between P=O and Sc, with 6 molecules of extractant as dimer participating in the process. Finally, a flowsheet for the recovery of Sc from ion-adsorption rare earth elements (REEs) concentrate was proposed and proved in lab-scale experiment.

Ion-adsorption rare earth ores of China

Geology and geochemistry of China’s ion-adsorption rare earth ores are discussed. The structure and material constitution of Lognan, Huashan, Guposhan and Heling deposits are compared. The weathered layer structure, as well as the distribution, differentiation and occurrence forms of rare earth elements (REE) in the weathered layer are described. The prospecting indicators and criteria of readily dissociated adsorbed REE ore are identified to find this type ores in the territory of Russia. The weathered layer enclosing ion-adsorption rare earth ore features specific differentiation of REE. General composition of such ores is governed by the composition of the primary rare earth mineralization in mother granites. If granites contain much yttrium and heavy lanthanides, then ion-adsorption rare earth ore contain also much yttrium and heavy lanthanides. Regarding differentiation of REE, yttrium and heavy lanthanides mainly concentrate in the middle, most clayey part of the weathered layer, while cerium accumulates in subsurface lateritic soil. The prime feature of ion-adsorption rare earth ore is the prevalence of readily dissociated REE, which can reach a quantity of 80% and more but not less than a half. The rest REE concentrate in relict rock-forming minerals and accessories. The quantitative estimation of adsorption form of REE is necessary for the geological and economic appraisal of a deposit. It is assumed that the quantity of readily soluble REE should be not less than 0.05–50% of the total content. Russia has many regions with such geotectonic environment. It is required to explore ion-adsorption rare earth ore occurrences in these regions.

Leaching behaviors of calcium and magnesium in ion-adsorption rare earth tailings with magnesium sulfate

Abstract The leaching behaviors of calcium and magnesium in the rare earth tailings leached with magnesium sulfate using deionized water, CaCl2 solution and lime water were investigated. Experimental data indicated that magnesium in the tailings was easy to be leached out since most of the magnesium was in the form of water-soluble phase. Most of calcium in the lime water was electrostatically adsorbed on the clay mineral of the tailings, and the water-soluble magnesium was also gradually converted into exchangeable phase because of back-adsorption of Mg2+ on the clay mineral with increasing the pH values. When the liquid-to-solid ratio was 0.80, the contents of readily-available magnesium and calcium were 104.4−207.6 and 201.7−1426.3 mg/kg, respectively, which could meet the requirements for plants. These results suggest a promising route for the environmental remediation of ion-adsorption rare earth ore after in-situ leaching.

Microscopic analyses of weathered granite in ion-adsorption rare earth deposit of Jianxi Province, China

Weathered granite of ion-adsorption rare earth elements (REEs) ore collected at Jiangxi Province, China was investigated to identify the minerals abundant in REEs. The analyses of scanning electron microscopy (SEM)-energy dispersive spectrometry (EDS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for individual mineral particles of the weathered granite showed that kaolinitic particles formed by K-feldspar weathering contained large amounts of REEs. Scanning transmission electron microscopy (STEM)-EDS analyses revealed that the kaolinitic particles were mainly composed of kaolinite, illite and hematite. The elemental maps by Nano-SIMS for the kaolinitic particle clarified that La and Y are particularly concentrated in illite. The presence of illite presumably contributes to the formation of the REE accumulation zone in weathered granite. Furthermore, in the in-situ desorption experiment, nearly half the REEs (45.5%) remained in the kaolinitic particle after the treatment with 0.5 M ammonium sulfate solution. The desorption ratio of heavy REEs (HREEs: Gd–Lu) (60.4%) was lower than that of light REEs (LREEs: La–Eu) apart from Ce (69.0%). These results suggest that REEs form inner-sphere complexes on the kaolinitic particle. It can be assumed that the inner-sphere complexation suppresses the extraction ratio of REEs from the ores by ion-exchange treatment.

Microbial communities in rare earth mining soil after in-situ leaching mining

In-situ leaching technology is now widely used to exploit ion adsorption rare earth ore, which has caused serious environmental problems and deterioration of mining soil ecosystems. However, our knowledge about the influences of mining operation on the microbiota in these ecosystems is currently very limited. In this study, diversity and composition of prokaryote and ammonia-oxidizing microorganisms in rare earth mining soil after in-situ leaching practice were examined using quantitative Polymerase Chain Reaction (qPCR) and Illumina high-throughput sequencing. Results showed that in-situ leaching mining considerably impacted microbial communities of the mining soils. The abundances of bacterial, archaeal, and ammonia-oxidizing archaea (AOA) were significantly and negatively correlated with ionic rare earth elements (REEs), while their diversities were relatively stable. Total rare earth elements (TREEs) and ammonium were the strongest predictors of the bacterial community structure, and organic matter was the key factor predicting the variation in the archaeal community. Chloroflexi, Proteobacteria, Acidobacteria, and Actinobacteria were the most abundant bacterial phyla, and archaeal communities were dominated by Thaumarchaeota. Phylogenetic analysis indicated that unclassified Thaumarchaeota and Crenarchaeota were the predominant AOA groups. The non-detection of ammonia-oxidizing bacteria (AOB) and the abundance of AOA indicated that archaea rather than bacteria were predominantly responsible for ammonia oxidation in the mining soil. Network analysis demonstrated that positive interactions among microorganisms could increase their adaptability or resistance to this harsh environment. This study provides a comprehensive analysis of the prokaryotic communities and functional groups in rare earth mining soil after mining operation, as well as insight into the potential interactive mechanisms among soil microbes.

Analysis of Dynamic Damage-Induced Porosity Changes of Granites in Leaching Mining Technique Based on SHPB Test

In situ leaching was a very important technical approach in ion-adsorption rare earth mining, because it can effectively avoid the geological hazards, protect the environment, and reduce the mining costs. The critical issue of this mining technique was to increase the permeability of ion-adsorption rare earth deposits. Due to the close relationship between the permeability and the porosity, in this paper, several experiments were conducted to find the dynamic characteristics of the granite deposit and the relationship between the dynamic characteristics and the porosity. Moreover, the SHPB test system was equipped to conduct the dynamic test, and the ultrasonic wave detector with high precision was employed to obtain the damage factor of granites. The test results showed that the failure mode under dynamic load and static load was close, and they both had splitting failure. Besides, when cyclic dynamic loading velocity was between 5.8 m/s and 8.4 m/s, the specimen was not a failure, but it caused the damage and changed the porosity. And the dynamic thresholds of failure stress and damage stress were found. Finally, a linear relationship between the porosity and the damage factor was found, which would help to analyze and predict the change of porosity under different dynamic loading velocities.

Phytoextraction of rare earth elements from ion-adsorption mine tailings by Phytolacca americana: Effects of organic material and biochar amendment

Phytoextraction is a promising technology for decontamination and recovery of rare earth elements (REEs) from REE-rich wastes. However, the improvement of REE phytoextraction efficiency on ion-adsorption REE mine tailings remains a challenge because the substrate can hardly support the growth of hyperaccumulators. In this study, REE phytoextraction using a REE hyperaccumulator, Phytolacca americana, grown on ion-adsorption REE mine tailing materials amended with organic material (OM) and biochar (BC) was explored through a pot experiment. Results show that under 1% OM, 5% OM, 1% BC, and 5% BC treatments, the shoots biomass of P. americana was 4.17, 7.85, 3.41, and 5.14 times higher than the control (without organic amendment) respectively, whereas the REE concentrations in shoots were 2.02, 68.4, 0.16, and 1.98 times lower than the control (524 ± 82.8 mg kg−1) respectively. The highest REE yield was obtained under 1% BC treatment and was 3.56 times that of the control. Both OM and BC treatments largely improved the soil physico-chemical properties. However, compared with OM and 5% BC treatments, 1% BC treatment induced a smaller increase in pH, and the amount of organic carbon and nutrients in the soil solution, thereby minimizing the reduction of REE bioavailability. We conclude that amendment with a low dosage of BC could be a potential way to improve REE phytoextraction efficiency by P. americana on ion-adsorption REE mine tailings.

Reclamation with organic amendments and plants remodels the diversity and structure of bacterial community in ion-adsorption rare earth element mine tailings

The success of phytoremediation relies on beneficial plant-microbe interactions. However, the changes of soil microbiota, during the phytoremediation of ion-adsorption rare earth element (REE) mine tailings, are far from understood. The present study was conducted to reveal the co-occurrence patterns and key regulating factors of bacterial communities in ion-adsorption REE mine tailings with phytoremediation. A field experiment was conducted on an ion-adsorption REE mine tailing to test three phytoremediation strategies: (i) phytostabilization with grasses, (ii) phytostabilization with economic crops, and (iii) phytoextraction with REE hyperaccumulators. The bacterial community diversity, co-occurrence patterns, and the key regulating environmental factors in bulk and rhizospheric soils after 16 months of reclamation were studied by 16S Illumina high-throughput sequencing. The soils of plots with REEs-hyperaccumulators had significantly higher α-diversity than those planted with non-accumulators. After phytoremediation, the diversity and relative abundances of bacteria assisting in nutrient acquisition pronouncedly increased in the bulk soil of the reclaimed plots. Some plant growth–promoting bacteria (PGPB), e.g., Rhodanobacter, Streptomyces, and Bacillus, were enriched in the rhizospheric soil samples. Meanwhile, soil nutrient (total carbon and total nitrogen) concentration and REE availability were the most significant factors shaping the bacterial communities. Furthermore, special bacterial consortia of Bacilli took up the positions of the keystone species. The results revealed the co-occurrence patterns and key regulating factors of bacterial communities in ion-adsorption REE mine tailings, which will provide more crucial information for the optimization of the reclamation of REE tailings.

Comparison of characteristics and geochemical behaviors of REEs in two weathered granitic profiles generated from metamictized bedrocks in Western Peninsular Malaysia

Rare earth elements (REEs), an important group of non-energy minerals, are vital to industrialized societies worldwide. Southeast Asian granitic belts are potential sources of ion-adsorption REE clays comprising large weathered granitic crusts that often have high-grade ion-adsorbed REEs. Characterization studies were conducted on representative samples from two sites, namely Lumut (LU) and Telok Murok (TM), located within the Malaysian Western granite belt. In both profiles, parent rocks were documented as medium-grained mica (phlogopite)-rich, S-type, peraluminous, ilmenite-series granite with metamict texture. Quartz, K-feldspar, and mica were major minerals, while REE-bearing accessory minerals were apatite, allanite, monazite, xenotime, and zircon. Al2O3 and LOI contents increased with depth in both weathered profiles, whereas P2O5 tended to be constant. Long-tube halloysite and kaolinite are abundant clays in the upper portions of the profiles, whereas the lower parts were rich in short-tube halloysite with smectite. Moreover, the depletion of REE + Y (REY) content in horizon A (B1) was clear, whereas REY was abundant in horizon B and/or C. The maximum content of REY could reach up to approximately 850 and 2350 ppm in horizon B2 and/or C in the LU and TM sites, respectively. Total REE content of the weathered crust was relatively elevated compared with that of the parent rocks (3–7 times) in the lower portions of both sites due to “high adsorption capacity” of abundant clay minerals in the deep profiles. Enrichment in LREE and HREE was indicated in the LU and TM sites, respectively. Trial leaching experiments with high-grade samples from both sites were conducted using ammonium sulfate. High recovery in the results proved REE adsorption by the clays in the lower parts of the profiles.

Removal of thorium and uranium from leach solutions of ion-adsorption rare earth ores by solvent extraction with Cextrant 230

The removal of radioactive elements thorium and uranium from the leach solution of ion-adsorption rare earth ores by aluminum sulfate was studied using di(2-ethylhexyl) [N-(2-ethylhexyl)aminomethyl] phosphonate (Cextrant 230, L).The extraction of thorium, uranium, rare earths, aluminum and other elements was investigated in detail, especially for uranium. The extracted complex was inferred to be UO2SO4·2L, in which phosphoryl oxygen atom of Cextrant 230 was involved in the coordination of UO22+. The thermodynamic parameters, such as ΔH, ΔG, ΔS were calculated. The negative value of ΔH suggests that the extraction of U(VI) by Cextrant 230 is an exothermic process. The extraction capacities of 5% (v/v) Cextrant 230 for Th(IV) and U(VI) were determined to be 4.08 g/L and 6.16 g/L, respectively. The loaded U(VI) and Th(IV) can be stripped using common inorganic acids. By just one stage extraction, the concentrations of thorium and uranium in the simulated leaching solution decreased obviously from 2.73 mg/L and 0.82 mg/L to <0.1 mg/L.

Removal of Radionuclide Uranium from South China’s Ion-adsorption Rare Earth Leach Liquor Using Solvent Extraction with Naphthenic Acid

Removal of Radionuclide Uranium from South China’s Ion-adsorption Rare Earth Leach Liquor Using Solvent Extraction with Naphthenic Acid

Rare earth elements in paddy fields from eroded granite hilly land in a southern China watershed.

There are large amounts of ion-adsorption rare earth resources in the granite red soil region of southern China, and exploitation of rare earth elements (REEs) has caused serious soil erosion and soil pollution in the area. In this study, the spatial variability of soil REEs in Zhuxi watershed, Changting County, southern China, was analyzed using a geostatistics method. The analysis produced several important results: (1) The content of total rare earth elements (TREEs) in the soil samples ranged from 56.04 to 951.76 mg kg−1, with a mean value of 255.34 mg kg−1, which was higher than the background value of soil in China. The REE variables showed strong positive Ce anomalies and strong negative Eu anomalies, with mean values of 2.26 and 0.44, respectively. (2) The contents of TREEs in five subtypes of the soils were different, but they had broadly similar curves of chondrite-normalized REE patterns, with steeper patterns from La to Eu and flatter patterns from Eu to Y. (3) The spatial variability of light rare earth elements (LREEs) was mainly affected by natural factors, but the spatial variabilities of heavy rare earth elements (HREEs) and TREEs were influenced by the combination of natural factors and anthropogenic factors. Soil erosion can contribute significantly to REE migration, especially for HREEs. (4) The distribution of TREEs showed that the high content of TREEs was in the lowland of the western watershed. By comparing the distributions of TREEs in paddy fields and hilly land, we found that the area with a high content of TREEs was greater in paddy fields than in hilly land, so we deduced that REEs migrate from hilly land to the paddy field and accumulate in the soil there.

Investigation on the radiation decontamination of lanthanum oxide during its production from ion-adsorption rare earth ores in China

A systematic study on radiation decontamination in lanthanum oxide production from ion-adsorption rare earth ores in China was conducted. The distribution characteristics of radiation levels during the production process was clarified, and effective measures for radiation decontamination were proposed. The results showed that during the lanthanum oxide production process, radiation would be separated from lanthanum and enter the production wastewater along with calcium, which is easily decontaminated through sodium carbonate precipitation. The percentage decontamination of calcium was close to and less than those of total α and total β, and it could be used for evaluating the percentage decontamination of radiation to ensure that the radiation level is controlled at a low level, as required in practice, instead of waiting for 140 days to analyse the values of total α and total β. Under the optimal condition of maintaining the terminal pH at 8.0–10.0, 99.66% of total α and 99.56% of total β in the production wastewater were decontaminated, and the radiation level of total α and total β could be drastically decontaminated to much lower than the national discharge standard of China, GB8978-1996 (total α < 1.0 Bq/L and total β < 10.0 Bq/L).

Rare Earth Elements and Other Critical Metals in Deep Seabed Mineral Deposits: Composition and Implications for Resource Potential

The critical metal contents of four types of seabed mineral resources, including a deep-sea sediment deposit, are evaluated as potential rare earth element (REE) resources. The deep-sea resources have relatively low total rare earth oxide (TREO) contents, a narrow range of TREO grades (0.049–0.185%), and show characteristics that are consistent with those of land-based ion adsorption REE deposits. The relative REO distributions of the deep-seabed resources are also consistent with those of ion adsorption REE deposits on land. REEs that are not part of a crystal lattice of host minerals within deep-sea mineral deposits are favorable for mining, as there is no requirement for crushing and/or pulverizing during ore processing. Furthermore, low concentrations of Th and U reduce the risk of adverse environmental impacts. Despite the low TREO grades of the deep-seabed mineral deposits, a significant TREO yield from polymetallic nodules and REE-bearing deep-sea sediments from the Korean tenements has been estimated (1 Mt and 8 Mt, respectively). Compared with land-based REE deposits, deep-sea mineral deposits can be considered as low-grade mineral deposits with a large tonnage. The REEs and critical metals from deep-sea mineral deposits are important by-products and co-products of the main commodities (e.g., Co and Ni), and may increase the economic feasibility of their extraction.

Leaching ion adsorption rare earth by aluminum sulfate for increasing efficiency and lowering the environmental impact

The leaching efficiency (LE) of ion adsorption rare earth (IARE) by the sulfate and chloride of ammonium, magnesium and aluminum were comparatively determined using column leaching method. It is found that at equal equivalent concentration of cation, the LE of IARE by aluminum sulfate is the highest, and the zeta potential of clay mineral particles in the tailing is near to zero, which means a lower risk of landslide and pollutant emission. Furthermore, the optimum concentration of aluminum sulfate is determined to be 0.02 mol/L, which is much lower than that of ammonium sulfate and magnesium sulfate. To reduce the production cost and environmental impact, we proposed a multi-stage leaching process, which was firstly leaching with ammonium sulfate and then with aluminum sulfate, following by water washing and lime neutralizing. With the ratio of ammonium sulfate to aluminum sulfate varying from 1:0 to 0.5:0.5, the residual ammonium in tailing decreases from 11.2% to 0.6%, however, the LE of RE shows an optimum value at 0.8:0.2. By neutralizing the pH of tailing with lime water to over 6, the ion concentration in water rinsing solution can meet the requirement for water discharge. At the same time, the zeta potential of clay particles is found to be around −5 mV, means a relatively lower risk of landslide. These facts indicate that the LE of IARE can be increased and the danger caused by tailings landslides and pollutant emissions can be reduced by replacing ammonium sulfate with aluminum sulfate as leaching reagent.