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1

The removal of dolomite from collophane using reverse flotation process enhanced by compound collector

Liu Liu, Tian Mengjie, Deng Xiangyi, Luo Huihua, Chi Ruan, Wu Kang

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 1

art. no. 159965

EN

To improve the magnesia removal effect of collophane and increase the P2O5 grade of phosphorus concentrate, the fatty acid collector mixed with sodium dodecyl sulfate (SDS) was used as the compound collector in reverse flotation for magnesia removal in acid system. Solution surface tension measurement, Zeta potential test and infrared spectrum analysis were conducted to analyze the intensified effect of compound collector for dolomite removal. The results showed that under the conditions of grinding fineness -0.074 mm accounted for 89.8%, sulfuric acid dosage 12.0 kg/t, phosphoric acid dosage 3.0 kg/t, SDS compound proportion 3%, collector dosage 1.0 kg/t, the P2O5 grade of concentrate is increased from 25.7% to 29.94%. SDS can reduce the surface tension of slurry, which is conducive to the formation and stability of flotation foam. Zeta potential became negative due to the compound collector adsorbed on the mineral surface. Moreover, the -CH2 antisymmetric stretching vibration peak originated from fatty acid and SDS were detected after the interaction of collectors with dolomite. The compound collector was effectively adsorbed on the surface of dolomite, enhancing the magnesium removal effect of collophane.

2

Effects of cations on rare earth adsorption and desorption in binding sites of montmorillonite

He Zhengyan, Nie Wenrui, Yang Huifang, Tang Yuchen, Sha Aoyang, Qu Jun, Xu Zhigao, Chi Ruan

Physicochemical Problems of Mineral Processing

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2023

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Vol. 59, iss. 3

art. no. 168280

EN

The exchangeability of rare earth (RE) in weathered crust elution-deposited rare earth ores largely depends on its interaction with clay minerals, which may be significantly influenced by various cations. Therefore, the effects of K+, Ca2+ and Al3+ on RE3+ adsorption and desorption in binding sites of montmorillonite (MMT) were investigated. Through the pre-saturation, the interlayer ions of MMT had been replaced by K+, Ca2+ or Al3+. RE3+ can adsorb on the interlayer sites of Ca-MMT and K-MMT, but nearly not Al-MMT. The basal spacing of Ca-MMT is larger than K-MMT, which provides a smaller hinder effect of interlayer collapse for the interlayer diffusion of RE3+. The adsorption capacity followed the order: Ca-MMT＞K-MMT＞Al-MMT and La3+＞Y3+＞Eu3+. It can predict that the grade of the exchangeable RE in ores abundant in Ca2+ is the most, followed by the ore rich in K+ and Al3+ the least. Clay minerals tend to adsorb light RE and hard to adsorb middle and heavy RE. The reversibility of RE adsorbed in interlayers, especially in collapsed interlayers, is far worse than that on externals. The desorption rates of RE were in the order of RE-Al-MMT＞RE-K-MMT＞RE-Ca-MMT and Eu3+＞Y3+＞La3+. For the desorption of interlayer RE3+, NH4+ is better than Mg2+ because the larger change of the basal spacings (Δd) provides more minor activation energy barriers (ΔE) for NH4+ diffusion within interlayers. It can enrich the metallogeny theory of weathered crust elution-deposited rare earth ores and provide a certain theoretical basis for its efficient exploitation.

3

The intensified effect of nitrogen removal properties using Pseudomonas fulva K3 and MgBC for the weathered crust rare earth wastewater treatment

Deng Xiangyi, Chi Ruan, Xiao Chunqiao, Zhang Zhenyue, Liu Xuemei, Hu Jingang

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 3

84--96

EN

A new bacteria named Pseudomonas fulva K3 (P. fulva) strain was isolated from the surroundings of weathered crust rare earth tailing with efficient NH4+-N removal ability via heterotrophic nitrification and aerobic denitrification. The nitrogen removal properties could be intensified by the synergistic effect between as-prepared magnesium-modified biochar (MgBC) and P. fulva strain. The results show that P. fulva exhibited a rod-shaped morphology and NH4+-N can be completely biodegraded under the optimal conditions of pH=7.0~8.0, temperature 30 oC and initial NH4+-N concentration of 100 ~150 mg/L. The NH4 +-N tolerant concentration for P. fulva was determined to be 300 mg/L. The magnesium-modified biochar (MgBC) worked as an adsorbent of NH4+-N. The kinetics and isotherm model for adsorption could be described by the pseudo-secondorder kinetic and Freundlich model, respectively. The XPS results showed that NH4+-N was mainly adsorbed on the surface by chemical adsorption. Furthermore, the P. fulva could be immobilized on MgBC due to its large surface area, adjusting the concentration of NH4+-N to a proper range for the growth of P. fulva by adsorption and desorption equilibrium, and leading to the intensified effect on nitrogen removal. The total nitrogen removal efficiency of the eluted weathered crust rare earth tailing reached 84.7 % in MgBC + P. fulva system.

4

Screening of high-efficiency potassium-dissolving strains and optimization of the potassium-dissolving process

Xue Yongping, Xiao Chunqiao, Zhang Yantu, Chi Ruan

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 2

1--13

EN

The biosolubilization of potassium feldspar (K-feldspar) by potassium-dissolving microorganisms has become a hot research topic. However, the screening of highly efficient potassiumdissolving strains from the soils of mining areas has not been reported. In this study, 82 strains with potassium-dissolving ability were screened from soils collected from a K-feldspar mining area in Suizhou, Hubei Province, China. One of them, JX-20, was a gram-positive is spherical bacteria with smooth edges, which was identified as a new strain by 16S rRNA gene sequencing. Simultaneously, the influences of temperature, initial pH value, inoculation volume, incubation time, shaking speed, Kfeldspar concentration, K-feldspar granularity, and the ammonium sulfate dose on the potassium releasing ability of the JX-20 strain were investigated. The results showed that the JX-20 strain had an obvious dissolution effect on K-feldspar. The optimum conditions for the JX-20 strain to remove potassium from K-feldspar were as follows: cultured at 28-30℃ for ten days, initial pH value of 7.4-8, 60 mL medium in a 250 mL conical flask, and 170 r/min shaking speed on a rotary shaker. The Kfeldspar concentration, inoculation volume, K-feldspar granularity, and ammonium sulfate dose were 2 g/L, 20%, 0.02-0.03 mm, and 0.4 g/L, respectively. Under the above conditions, the highest corrosion efficiency of 39.75% was achieved.

5

Effect of polyacrylamide on the process of removing impurities in the rare earth leachate

Wu Xiaoyan, Zhou Fang, Liu Chufan, Feng Jian, Zhang Zhenyue, Chi Ruan

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 1

182--191

EN

The impurity removal process of the rare earth (RE) leachate is usually accompanied by the formation of flocs, and a certain amount of polyacrylamide flocculant needs to be added in this process. However, few studies have investigated the effect of the flocculant on the impurity removal process. Therefore, this paper compares the influence on the process of removing impurities with or without the adding of polyacrylamide (PAM). The results showed that the addition of PAM had little effect on the removal rate of impurities, but it was conducive to the recovery of RE. When ammonium bicarbonate was firstly adopted to regulate the solution pH to 5.0, and then sodium sulfide was used to adjust the pH to 5.2, and 0.5 mL/100 mL of PAM was added to the leachate, 96% Al3+ and 98% Zn2+ were removed from the leachate, while 95% RE was maintained. In addition, PAM could accelerate the settlement of flocs and then shorten the production cycle. The increase in RE recovery rate may be due to the addition of PAM to shorten the settling time of the flocs, thereby reducing the RE ions adsorbed during the flocculation process and increasing the recovery rate of the RE.

6

Application of chromatographic plate theory on the weathered crust elution-deposited rare earth ore with carboxylate

Zhang Zhenyue, Wang Guangshuai, Li Chunhua, Chi Ruan, Long Fei, Chen Zhuo, Chi Xiao Wang, Liu Defeng

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 4

48--62

EN

To improve the leaching process of rare earth and reduce the impurities in the leachate, the carboxylate ammonium, such as ammonium acetate, ammonium citrate and ammonium tartrate, were selected as lixiviant to compare the effects of concentration, flow rate, pH and temperature on leaching mass process of rare earth and aluminum. Meanwhile, the leaching behaviors of rare earth and aluminum leached by three kinds of carboxylate ammonium were analyzed by chromatographic plate theory. The relationship between the flow rate and height equivalent (HETP) could fit well with the Van Deemter equation and there was an optimal flow rate (uopt) for the leaching of the rare earth and aluminum. Besides, the conditions of carboxylate ammonium lixiviant were optimized. The optimum concentrations of ammonium acetate, ammonium tartrate and ammonium citrate were 15 g/L, 25 g/L and 5 g/L respectively, the leaching flow rate was 0.50 mL/min, the pH value was approximatively 7.00 and the leaching temperature was 293 K to 303 K. At these conditions, the mass transfer efficiencies of three ammonium carboxylates for rare earth and aluminum was in the order of ammonium acetate > ammonium tartrate > ammonium citrate. Moreover, the ammonium acetate could commendably inhibit aluminum ions entering the lixivium.

7

Seepage mechanism during in-situ leaching process of weathered crust elution-deposited rare earth ores with magnesium salt

Liu Defeng, Zhang Zhenyue, Chi Ruan

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 2

350--362

EN

To reveal seepage mechanism during in-situ leaching process of weathered crust elution deposited rare earth ores with magnesium salt, the effects of particle gradation, particle migration, Atterberg limit on the permeability coefficient were investigated, and the relation between the particle size and rare earth content was discussed. The results showed that the ore in the humic layer (HL) with high porosity and permeability was uniformly graded particles. The ore in the completely weathered layer (CWL) with low porosity and permeability belonged to dense-graded particles. The ore in the partly weathered layer (PWL) was open-graded particles, whose permeability fell in between the HL and the PWL. The change of -0.075mm particles content was the largest in the leaching process. When - 0.075mm particle content was less than 30%, the migration ability of fine particles and the permeability coefficient decreased gradually. On the contrary, the migration ability of fine particles gradually remained stable, and the change in the permeability coefficient was not obvious. The liquid limit (LL) in the Atterberg limit of HL, CWL and PWL was inversely proportional to the permeability coefficient, and followed the order: LLHL < LLPWL < LLCWL. With the -0.075mm particle content increasing, the LL of the ore samples increased gradually and finally tended to be stable. The peak value of rare earth concentration appeared earlier and the rare earth content decreased gradually with the increase of the ore particle size. This work provided a theoretical basis for achieving high-efficient mining of weathered crust elution-deposited rare earth ores.

8

Process mineralogy of Bayan Obo rare earth ore by MLA

Xu Caili, Chi Ru’an, Zhang Yantu, Zhong Chengbin, Ruan Yaoyang, Lyu Renliang, Zhou Fang

Physicochemical Problems of Mineral Processing

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2020

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Vol. 56, iss. 4

737--745

EN

The maximum recovery of rare earth resource from the Bayan Obo ore deposit is a difficult task, especially without the sufficient data of mineralogy. In this paper the mineralogy of Bayan Obo ore deposit by comprehensively research with the application of mineral liberation analyzer (MLA) is reported. The MLA was applied to quantitatively analyze the complicated element/mineral compositions, the REE occurrence, the size distribution and the degree of liberation of the Bayan Obo ore. Mineralogical analysis of the rare earth ore has shown that REEs are present mainly as bastnaesite and monazite-(Ce) to a small extent as parisite-(Ce). 5.85% of the REEs, 34.99% of iron and 0.12% of niobium occur in the ore sample. There are 76.99% of iron occurred in hematite and the remaining iron is mainly distributed in magnetite and goethite. The degree of liberation of bastnaesite and monazite(Ce) was 79.65% and 75.67% respectively when the grinding fineness was 83.57% passing 75 μm sieves. Un-liberated or partly liberated rare earth minerals are associated closely mainly with other rare earth minerals and gangues. These theoretical data could be employed to further comprehensively utilize the rare earth ore.

9

Enhanced biosolubilization of mid-low grade phosphate rock by formation of microbial consortium biofilm from activated sludge

Xiao Chunqiao, Wu Xiaoyan, Zhu Lei, Yu Tong, Xu Zhenghe, Chi Ruan

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 1

217--224

EN

Mid-low grade phosphate rock (PR) is a potential source of free phosphate to facilitate crop growth, but a cost effective and environmentally responsible extraction process is required. In this study, the capacity of a microbial consortium from activated sludge to solubilize PR in a laboratory-scale column reactor was investigated. The microbial consortium proved capable of efficiently releasing soluble phosphate in the reactor effluent over the 90-day trial. The microbial consortium grew well in the column system as evidenced by reduced chemical oxygen demand (COD) in the reaction solution. Biofilm formation was identified as critical for biosolubilization of the mid-low grade PR. Imaging of the biofilm by scanning electron microscopy (SEM) revealed a dense network of microbial cells embedded in extracellular polymeric substances (EPS). The biofilm contained both oxic and anoxic zones. The pH decreased significantly in both the biofilm and the reaction solution during operation, indicating healthy growth of the microbial consortium with corresponding acid generation and subsequent enhancement of phosphate solubilization.

10

Direct reuse of rare earth oxalate precipitation mother liquor for rare earth leaching

Wu Xiaoyan, Zhou Fang, Feng Jian, Liu Xueme, Zhang Zhenyue, Chi Ruan

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 3

760--769

EN

In the recovery process of rare earth (RE) from the weathered crust elution-deposited rare earth ore, ammonium sulfate is used as the leaching liquor to leach RE, and then the leachate containing RE3+ can be precipitated by oxalic acid and the RE oxalate precipitation mother liquor is reused for RE leaching process after removing the residual oxalic acid by precipitation with calcium hydroxide. However, the reuse process of precipitation mother liquor cannot proceed in the strong acid and alkali restricted areas and the discharge of mother liquor which contains a large amount of ammonium salt will cause ammonia-nitrogen waste and pollution. In order to realize the reuse of the precipitation mother liquor in this area, the direct reuse of RE oxalate precipitation mother liquor for RE leaching was investigated in this study. The RE oxalate precipitation process and the RE leaching process with oxalic acid were studied. The results showed that the residual oxalic acid concentration in the mother liquor can be controlled lower than 0.8 g/dm3 at pH 2-3 when the RE concentration in the leachate was 0.1- 1.5 g/dm3 and the RE precipitation rate reached to 94%. In addition, RE leaching efficiency was up to 90% while the oxalic acid concentration in the prepared mother liquor was 0.2-0.8 g/dm3, pH 2-3. Therefore, the precipitation mother liquor with oxalic acid concentration less than 0.8 g/dm3 could be directly reused for RE leaching. However, considering the different performance of RE ores, the recommended oxalic acid concentration in the direct used precipitation mother liquor was lower than 0.6 g/dm3.

11

Adsorption of lanthanum(III) and yttrium(III) on kaolinite: kinetics and adsorption isotherms

Zhou Fang, Feng Jian, Xie Xiong, Wu Baihong, Liu Qi, Wu Xiaoyan, Chi Ruan

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 4

928--939

EN

Experimental investigations were carried out using kaolinite to adsorb two rare earth ions, lanthanum ion (La3+) and yttrium ion (Y3+), which will provide some useful information and new insights on the mineralization process and fractionation phenomenon of weathered crust elution-deposited rare earth ores. The results showed that the equilibrium adsorption capacity of Y3+ is greater than La3+ under the same experimental conditions. The adsorption of rare earth ions presents strongly temperature dependent indicating an endothermic adsorption process. The pseudo-first-order kinetic model and the pseudo-second-order kinetic model were applied to discuss the adsorption kinetics. It was found that the adsorption rate of rare earth follows the pseudo-second-order kinetic model among the adsorption temperature range. Furthermore, the adsorption process of rare earth ions on kaolinite followed the Langmuir isotherm model confirmed by the correlation of experimental equilibrium data to standard isotherm model, Langmuir and Freundlich isotherms. The activation energies for the adsorption of La3+ and Y3+ on kaolinite are 28.1903 kJ/mol and 25.4190 kJ/mol, respectively. All kaolinite before and after adsorption were characterized by XRD and SEM-EDX to understand the adsorption mechanism. The obtained results suggested that the adsorption of La3+ and Y3+ on kaolinite is an endothermic and chemisorption process.