scholarly journals Leaching Kinetics of Weathered Crust Elution-Deposited Rare Earth Ore with Compound Ammonium Carboxylate

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 516
Author(s):  
Xiuwei Chai ◽  
Guoqing Li ◽  
Zhenyue Zhang ◽  
Ruan Chi ◽  
Zhuo Chen
Keyword(s):  
Rare Earth ◽  
Ammonium Acetate ◽  
Experimental Temperature ◽  
Ammonium Citrate ◽  
Molar Ratio ◽  
Utilization Rate ◽  
Ammonium Concentration ◽  
Leaching Kinetics ◽  
Weathered Crust ◽  
Leaching Efficiency

Due to the special properties of the ammonium salts, ammonium acetate and ammonium citrate were used to explore the best leaching conditions of rare earth with compound ammonium carboxylate. This paper explored the influence of the molar ratio, ammonium concentration, experimental temperature, and pH of the compound leaching agents on the leaching efficiency of rare earth and aluminum, and it analyzed the leaching process based on the leaching kinetics, which provides a new method for leaching rare earth from the weathered crust elution-deposited rare earth ore. The results showed that under the conditions where the molar ratio of ammonium acetate and ammonium citrate was 7:3 and the ammonium concentration was 0.15 mol/L, the leaching efficiency of rare earth was the highest when the pH of leaching agent was 4.0 and the experimental temperature was 313 K. Meanwhile, when CH3COONH4 and (NH4)3Cit were used to leach rare earth ore, the leaching reaction kinetics equation of rare earth and aluminum were obtained. In the temperature range of 283–323 K, the apparent activation energy of rare earth was 14.89 kJ/mol and that of aluminum was 19.17 kJ/mol. The reaction order of rare earth was 0.98 and that of aluminum was 0.79. The results were in accordance with the shrinking core model and indicate that the concentration of the leaching agent had a greater influence on rare earth than aluminum. This process can reduce the use of ammonium salt, and it is of great significance to extract rare earth elements from weathered crust elution-deposited rare earth ore and improve the utilization rate of resources.

Leaching behaviour of rare earth elements from low-grade weathered crust elution-deposited rare earth ore using magnesium sulfate

Clay Minerals ◽  
2018 ◽  
Vol 53 (3) ◽  
pp. 505-514
Author(s):  
Kaihua Chen ◽  
Jiannan Pei ◽  
Shaohua Yin ◽  
Shiwei Li ◽  
Jinhui Peng ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Magnesium Sulfate ◽  
Low Grade ◽  
Second Stage ◽  
Leaching Solution ◽  
Weathered Crust ◽  
Leaching Behaviour ◽  
N Pollution ◽  
Leaching Efficiency

ABSTRACTThe present study investigates the use of magnesium sulfate (MgSO4) instead of (NH4)2SO4 as a lixiviant in the recovery of rare earth elements (REEs) from clays. Experiments were carried out to investigate the influence of leaching conditions such as leaching time, lixiviant concentration and liquid:solid ratio on the leaching efficiency. The optimum leaching conditions, leading to 75.48% of total REE leaching efficiency, required a stirring speed of 500 rpm, a leaching time of 30 min, a lixiviant concentration of 3 wt.% and a liquid:solid ratio of 3:1. After extension of the leaching process by a second stage, the leaching efficiency may reach up to 96.19%, which is slightly higher than that obtained by (NH4)2SO4. Leaching varies from element to element, with Ce presenting the lowest leaching efficiency, and the partition in leaching solution is in agreement with that in raw ore other than for Ce. Based on these findings, MgSO4 lixiviant is an excellent alternative leaching agent for a sustainable REE industry because it reduces or eliminates NH4+–N pollution.

scholarly journals Effects of Ion Characteristics on the Leaching of Weathered Crust Elution-Deposited Rare Earth Ore

2020 ◽  
Vol 8 ◽  
Author(s):  
Zhenyue Zhang ◽  
Ru'an Chi ◽  
Zhuo Chen ◽  
Wendou Chen
Keyword(s):  
Rare Earth ◽  
Zeta Potential ◽  
Clay Minerals ◽  
Leaching Process ◽  
Valence States ◽  
Weathered Crust ◽  
Anions And Cations ◽  
The Relationship ◽  
Leaching Efficiency ◽  
The Rare Earth

To reveal the ion-exchange mechanism in the leaching process of weathered crust elution-deposited rare earth ores with different leaching agents, the effects of a variety of cations and anions at different concentrations on the leaching process were investigated, including Al3+, Fe3+, Ca2+, Mg2+, Na+, K+, NH4+ and Cl−, NO3-, and SO42-. Meanwhile, the relationships between different concentrations of cations and anions and leaching efficiency were investigated, as was the relationship between different concentrations of cations and anions and zeta potential. The effect of different ions on the swelling of clay minerals during leaching process was also investigated. The results shown that NH4+ was the most affected electrolyte cation in terms of rare earth leaching efficiency during the leaching process of weathered crust elution-deposited rare earth ore among three different cationic valence states, and the leaching efficiency was 86.93% at the optimal leaching concentration. The influence of the three anions on the leaching efficiency of rare earth was NO3->Cl->SO42-, and the leaching efficiency of rare earth were 83.21, 81.52, and 80.12% at the optimal leaching concentration, respectively. The NH4+ had the greatest effect on the zeta potential of weathered crust elution-deposited rare earth ore, and the zeta potential was −18.1 mV at the optimal leaching concentration. Additionally, the order of the effect of three anions on zeta potential was SO42->NO3->Cl-. Combined with the effect on the rare earth leaching process, anions and cations were considered separately, and NH4+ and Cl− were selected; the relationship between the rare earth leaching efficiency and zeta potential conforms to the follow equations: NH4+:Y = −0.48X2 – 13.51X – 1.58, R2 = 0.98133 and Cl−:Y= −1.22X2 – 17.64X + 23.29, R2 = 0.99010. It was also found in the swelling experiment of the weathered crust elution-deposited rare earth ore that the swelling ratio of clay minerals was the lowest when the cation and anion were NH4+ and Cl− and the swelling ratios were 1.874 and 2.015%, respectively.

scholarly journals Soil-water characteristics of weathered crust elution-deposited rare earth ores

2021 ◽  
Vol 31 (5) ◽  
pp. 1452-1464
Author(s):  
Zhong-qun GUO ◽  
Jian-rong ZHOU ◽  
Ke-fan ZHOU ◽  
Jie-fang JIN ◽  
Xiao-jun WANG ◽  
...  
Keyword(s):  
Rare Earth ◽  
Soil Water ◽  
Water Characteristics ◽  
Weathered Crust

Effect of potassium chloride on leaching process of residual ammonium from weathered crust elution-deposited rare earth ore tailings

2021 ◽  
Vol 163 ◽  
pp. 106800
Author(s):  
Jian Feng ◽  
Junxia Yu ◽  
Shuxin Huang ◽  
Xiaoyan Wu ◽  
Fang Zhou ◽  
...  
Keyword(s):  
Rare Earth ◽  
Potassium Chloride ◽  
Leaching Process ◽  
Weathered Crust

Development of pore structure characteristics of a weathered crust elution-deposited rare earth ore during leaching with different valence cations

2021 ◽  
Vol 201 ◽  
pp. 105579
Author(s):  
Lingbo Zhou ◽  
Xiaojun Wang ◽  
Chengguang Huang ◽  
Hao Wang ◽  
Huachang Ye ◽  
...  
Keyword(s):  
Rare Earth ◽  
Pore Structure ◽  
Structure Characteristics ◽  
Weathered Crust

Extraction of rare earths from the leach liquor of the weathered crust elution-deposited rare earth ore with non-precipitation

2011 ◽  
Vol 98 (3-4) ◽  
pp. 125-131 ◽  
Author(s):  
Tian Jun ◽  
Yin Jingqun ◽  
Chen kaihong ◽  
Rao Guohua ◽  
Jiang Mintao ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Leach Liquor ◽  
Weathered Crust

Synthesis of Rare Earth Catalyst LLa[N(TMS)2]•DME(L=3,5-But2-2-HO-C6H2CH-NH-C5H4N) and Catalytic Behavior for Polymerization of Rac-Lactide

2012 ◽  
Vol 184-185 ◽  
pp. 1302-1306
Author(s):  
Xi Zhu ◽  
Yao Rong Wang
Keyword(s):  
Rare Earth ◽  
Ring Opening ◽  
Ring Opening Polymerization ◽  
Molar Ratio ◽  
Elimination Reaction ◽  
Catalytic Behavior ◽  
Rare Earth Catalyst

A dianionic phenoxyamido ligand was the first to be used to stabilize organo-rare-earth mental amido complex. Amine elimination reaction of La[N(SiMe3)2]3(THF)2 with 3,5-But2-2-HO-C6H2CH-NH-C5H4N in a 1 : 1 molar-ratio gave the anionic phenoxyamido neodymium amide LLa[N(TMS)2]•DME (1) in a high isolated yield. Furthemore, the catalytic behavior of complex 1 for the ring-opening polymerization of rac-lactide was explored.

Leaching kinetics of copper and valuable metal extraction from copper-cadmium residues of zinc hydrometallurgy by oxidation acid leaching

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jihao Guo ◽  
Hongao Xu ◽  
Bo Li ◽  
Yonggang Wei ◽  
Hua Wang
Keyword(s):  
Hydrogen Peroxide ◽  
Acid Concentration ◽  
Acid Leaching ◽  
Metal Extraction ◽  
Agitation Rate ◽  
Leaching Kinetics ◽  
Solid Ratio ◽  
Zinc Hydrometallurgy ◽  
Kinetics Of ◽  
Leaching Efficiency

Abstract Multiple purification of zinc sulfate solution is an important process for zinc hydrometallurgy, and large quantities of copper-cadmium residues are generated as byproducts in this process. Copper-cadmium residues contain a large number of valuable metals that must be recovered. A comprehensive extraction process has been proposed using sulfuric acid as the leaching reagent and hydrogen peroxide as the oxidizing reagent. The effects of acid concentration, leaching temperature, leaching time, liquid-to-solid ratio, hydrogen peroxide dosage and stirring speed on the leaching efficiency were investigated. The optimum conditions were determined as an acid concentration of 150 g/L, liquid-to-solid ratio of 4:1, hydrogen peroxide amount of 20 mL, time of 60 min, temperature of 30 °C, particle size of −d75 μm, and agitation rate of 300 r/min. It was concluded that the leaching efficiency of copper and cadmium reached 97%, but because of the existence of zinc sulfide in the residues, a lower leaching efficiency of zinc was obtained. Furthermore, the leaching kinetics of copper was also studied based on the shrinking core model. The activation energy for copper leaching was 5.06 kJ/mol, and the leaching process was controlled by the diffusion through the product layer.

Rare-earth metal bis(aminobenzyl) complexes supported by pyrrolyl-functionalized arylamide ligands: synthesis, characterization and styrene polymerization performance

2018 ◽  
Vol 47 (29) ◽  
pp. 9709-9716 ◽  
Author(s):  
Min Li ◽  
Chaopan Wang ◽  
Hongzhen Xie ◽  
Zehuai Mou ◽  
Yunjie Luo
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Molar Ratio ◽  
Acid Base ◽  
Styrene Polymerization ◽  
Catalyst Systems

Acid–base reaction between Ln(CH2C6H4NMe2-o)3 and 2,5-Me2C4H2NCH2SiMe2NHC6H4R (R = H, (HL1); R = Cl-p, (HL2) in 1 : 1 molar ratio gave L1Ln(CH2C6H4NMe2-o)2 (Ln = Sc (1), La (2), Lu (3) and L2Ln(CH2C6H4NMe2-o)2 (Ln = Sc (4), La (5), Lu (6). The catalyst systems of 2 or 5/[Ph3C][B(C6F5)4] were active for syndio-specific styrene polymerization.

scholarly journals Chemical synthesis of all-trans-β-retinoyl phosphate

1976 ◽  
Vol 159 (3) ◽  
pp. 799-801 ◽  
Author(s):  
J P Frot-Coutaz ◽  
L M de Luca
Keyword(s):  
Retinoic Acid ◽  
Chemical Synthesis ◽  
Cellulose Acetate ◽  
Silica Gel ◽  
Absorption Maximum ◽  
Ammonium Acetate ◽  
Deae Cellulose ◽  
Thin Layers ◽  
Molar Ratio ◽  
Chloroform Methanol

all-trans-β-Retinoic acid is phosphorylated to retinoyl phosphate by bis(triethylamine) phosphate with yields of 10-15%. The product is soluble in methanol and is eluted from DEAE-cellulose acetate at a concentration of 0.1M-ammonium acetate in 99% (v/v) methanol. Its phosphate/retinoic acid molar ratio is 1. Retinoyl phosphate has an absorption maximum at 360nm in methanol, whereas retinoic acid has a maximum at 350 nm. The compound is hydrolysed at pH2 and pH13 for 20 min at 37 degrees C, but is relatively stable under the same conditions at pH4, 6, 8 and 10. Retinoyl phosphate (RF 0.1) can be separated from retinyl phosphate (RF 0.2) by chromatography on thin layers of silica gel in chloroform/methanol/water (60:25:4, by vol.).

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