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Comparative Study between D2EHPA and Cyanex 272 as Extractants of Mn(II) from a Leached Liquor Produced by Reductive Leaching of a Pyrolusite Ore with SO2  [PDF]
R. Pérez-Garibay, J. Martínez-Jiménez, A. Uribe-Salas, A. Martínez-Luévanos
Engineering (ENG) , 2012, DOI: 10.4236/eng.2012.49067
Abstract: This paper compares the efficiency of D2EHPA and Cyanex 272 to extract the divalent manganese cation from an actual leaching solution obtained by reductive leaching of a low-grade pyrolusite ore, using SO2 gas. The studied variables were the extractant concentration in the organic phase, the pH of the leached liquor and the volume ratio between organic phase and leached liquor. It was observed that D2EHPA is a better extractant than Cyanex272. Therefore, with the best experimental conditions found, both extractants reach a manganese recovery around 95% with five extraction stages conducted under the following conditions: 25?C, O/A = 2, 10% volume of extractant concentration in the organic phase, pH of the leached liquor before the mixing between 8 and 8.5, and one minute of mixing time for each extraction stage.
The extraction of zinc and other minor metals from concentrated ammonium chloride solutions with D2EHPA and Cyanex 272  [cached]
Amer, S.,Luis, A.
Revista de Metalurgia , 1995,
Abstract: A comparative study is made of the extractants D2EHPA and Cyanex 272 for the zinc and minor metal extraction from aqueous concentrated ammonium chloride solutions, as those of the leaching liquors of the CENIM-LNETI process. Extraction equilibrium data for zinc are presented as extraction isotherms at constant pH and at a temperature of 50 °C. Zinc extraction and coextraction of minor metal ions as Cu, Ca, Pb, Mg, Cd, Co, Ni and Hg are studied. Mercury does not extract from concentrated ammonium chloride solutions. Cyanex 272 shows a better selectivity for zinc with regard to the minor metals than D2EHPA, which is especially remarkable for calcium, the most coextracted element by D2EHPA. Nickel and cadmium coextraction is negligible for both extractants. The possible use of the Cyanex 272 as an alternative to D2EHPA is considered. Se realiza un estudio comparativo del comportamiento del D2EHPA y del Cyanex 272 durante la extracción del cinc y otros metales minoritarios de soluciones acuosas concentradas de cloruro amónico, como las de las soluciones de lixiviación del proceso CENIM-LNETI. Se presentan los datos de equilibrio de extracción del cinc en forma de isotermas de extracción a una temperatura de 50 °C y pH constante y se estudia la coextracción de los metales minoritarios Cu, Ca, Pb, Mg, Cd, Co, Ni y Hg. El mercurio no se extrae de las soluciones concentradas de cloruro amónico. La selectividad del Cyanex 272 para el cinc respecto de esos metales minoritarios es mejor que la del D2EHPA, siendo verdaderamente notable para el calcio, que es la impureza que más se coextrae con el D2EHPA. La coextracción de níquel y de cadmio es muy peque a para ambos extractantes. Se considera la posibilidad del uso alternativo del Cyanex 272 en lugar del D2EHPA.
Extraction and Separation of Cobalt and Nickel with Extractants Cyanex 302, Cyanex 272 and Their Mixture  [PDF]
Lenhard, Z.
Kemija u Industriji , 2008,
Abstract: The extraction and separation of cobalt(II) and nickel(II) from sulphate solutions with different initial volume fractions of commercial organophosphorus extractants Cyanex 302, Cyanex 272 and their mixture, in kerosene as diluent, were investigated. Prepared samples contained the mixture of cobalt(II) and nickel(II) in mass concentrations chosen to approximate the mass concentrations of the two metals in solutions obtained by leaching typical low-grade ores or waste materials with sulphuric acid. The experiments were carried out at two concentration ratios of nickel to cobalt(ζNi/Co), 25 and 125. The latter ratio was chosen as model for the solutions of naturally occurring ores and other materials in which the concentration of nickel is much higher than that of cobalt. In all cases, the concentration of cobalt was approximately y= 0.15 g L–1, and the concentration of nickel was approximately g= 3.80 g L–1 (at ζNi/Co = 25) and 18.80 g L–1 (at ζNi/Co = 125). Other initial values were based on conditions found to be optimal in previous investigations, and kept constant in all experiments: pH<0= 8, θ0 = 25 °C, phase volume ratio organic to aqueous ψ = 1 and 0.5, contact time 2 minutes.The tested fractions of extractants (Cyanex 302 or Cyanex 272), diluted in kerosene, were j = 2.5, 5.0, 7.5 and φ = 10 %. The studies of the mixture of extractants were carried out at two sets of fractions. In the first set, the fraction of Cyanex 302 was kept at φ = 10 %, and Cyanex 272 was varied in the range φ = 2.5 –10 %. In the second set, the mass concentration of each of the two extractants was varied in the range φ = 2.5–10 % so that the total fraction of the two extractants always added up to φ= 10 %.The obtained results describe the influences of type and initial volume fraction of extractant on the separation and extraction of cobalt and nickel. Under the investigated range of conditions, Cyanex 302 outperformed Cyanex 272 in cobalt-nickel separation, which is obvious from the distributionratios for cobalt (Figs. 1 and 2) and nickel (Figs. 3 and 4) as well as from the cobalt-nickel separation factors (Table 1).In the extraction of cobalt and nickel with different mixtures of Cyanex 302 and Cyanex 272, no evidence for any synergistic effects were found, as indicated by the obtained synergistic coefficients (Table 2 and 3) and separation factors for cobalt and nickel (Table 4).In the follow-up work to this study, we plan to investigate new mixtures of extractants for their ability to separate cobalt from nickel in solutions with properties similar to those encountere
Study of coupled pyrite leached pyrolusite by functional microflora

MA Xiao-Mei,HAN Yi-Fan,LU Fu-Ping,ZHANG Xiao-Xi,WEN Dan,LIU Yong-Jin,BAI Li-Ming,HU Ying,HUANG Zhi-Yong,

微生物学通报 , 2012,
Abstract: Objective] Three different environmental samples were mixed and inoculated into 100 mL fresh medium containing 1% pyrolusite and 1% pyrite. After enrichment we got bioleaching microflora. Methods] Obtained microorganism consortia were used to leach pyrite and low-grade pyrolusite. Non-inoculation system was conducted as control group. Results] Series of parameter were monitored during the process, including dynamic of consortia construction, pH value, leaching ratio of manganese, and XRD analyze of leaching residual. Leaching ratio of manganese was 92.48% after 15 days cultivation. And it was much higher than control group (40.34%). Within microbial consortia, Thiomonas sp. was the dominant species and its proportion increased from 2% to 93% of the consortia. Value of pH was declined from 4 to 2.5 in experimental group. Jarosite was observed in bioleaching residual. Conclusion] Decrease of pH value and formation of jarosite indicated abundant sulfuric acid produced by bacterial metabolism. Result suggested that increasing bioleaching ratio of pyrite and pyrolusite due to dissociation of pyrite and decline of pH value by bacterial activity. This study could provide the basis for the further research of bioleaching mechanism and improvement of industrial art of low-manganese ore mineral resource.
Study of Zirconium and Hafnium Separation by Solvent Extraction Technique from Nitric and Hydrochloric Solutions with Acid, Basic and Neutral Extractants  [PDF]
Janúbia Cristina B. S. Amaral, Carlos Ant?nio de Morais
World Journal of Engineering and Technology (WJET) , 2016, DOI: 10.4236/wjet.2016.43D017
This paper describes the study of the extraction of Zr and Hf in nitric and hydrochloric media by solvent extraction technique using different types of extractants. The effect of the extractants DEHPA, IONQUEST?801 and CYANEX?272, TBP, CYANEX?923, PRIMENE?JTM, ALAMINE?336 and ALIQUAT?336 was investigated. For acid extractants in both nitric and hydrochloric media, a high degree of extraction was observed, although they had low selectivity in separating the metals. For the acid extractants also, it was not possible to strip the metals from the organic phase through acid solutions. In this case, a stripping solution with very high acidity would be required, and this is not viable. When the basic extractants were used, no metal extraction was observed under the conditions investigated, indicating no extractable anionic species in either media. The optimum zirconium/hafnium separation was achieved using an acidity of 7.0 mol?L?1, nitrate concentration of 9.2 mol?L?1 and 1.5 mol?L?1 of TBP. In these conditions, a separation factor of 12.6 was obtained.
YX Hua,

金属学报(英文版) , 1997,
Abstract: The microwaves were used to stimulate the decomposition process of pyrolusite under air atmosphere. It was shown that the overall rate of the process was significantly enhanced when using microwaves instead of conventional heating. The applications of microwaves in the decomposition of pyrolusite could appreciably lower the reaction temperatures.
Selective Separation of Light and Heavy Rare Earth Elements from the Pregnant Leach Solution of Apatite Ore with D2EHPA  [PDF]
Ariuntuya Battsengel, Altansukh Batnasan, Kazutoshi Haga, Atsushi Shibayama
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2018, DOI: 10.4236/jmmce.2018.65037
Abstract: Different separation techniques such as solvent extraction, ion exchange, and precipitation are often used for recovery of rare earth elements (REEs) from pregnant leach solutions obtained from acid leaching. Solvent extraction is generally accepted as the most appropriate commercial technology for separating REEs due to the need to be able to handle larger volumes of diluted pregnant solutions. This study focused on the development of selective separation of light and heavy REEs from the pregnant leach solution obtained from leaching of apatite ore in 1 M sulfuric acid (H2SO4) using solvent extraction. Three different commercial organophosphorus extractants (di-(2-ethylhexyl) phosphoric acid (D2EHPA), 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC88A) and tributyl phosphate (TBP)), and the influences of experimental parameters such as extractant concentration, organic/aqueous phase ratio, diluent type, pH, extraction time and stripping agent concentration were examined. Results showed that light REEs (LREEs) and heavy REEs (HREEs) in the pregnant leach solution were selectively separated with D2EHPA via a two-stage extraction process. In the first-stage of solvent extraction, >90% of (0.05 g/L) HREEs was extracted with 1.8 M D2EHPA in kerosene while the vast majority (>95%) of LREEs was remained in raffinate. In the second-stage, >93% (1.01 g/L) of LREEs was extracted from the raffinate with 1.8 M D2EHPA dissolved in kerosene at pH 1.6. HREEs (>95%) and LREEs (>90%) loaded with D2EHPA after the first and second-stage of extraction were stripped by 4 M H2SO4 and 1 M H2SO4 solutions, respectively. Distribution of middle rare earth elements (MREEs) was discussed through the extraction processes in this study.
Extraction and separation of titanium(IV) with D2EHPA and PC-88A from aqueous perchloric acid solutions
Journal of the Serbian Chemical Society , 2002,
Abstract: The liquid-liquid extraction of Ti(IV) from perchlorate media using, di(2-ethylhexyl) phosphoric acid (D2EHPA) and 2-ethylhexyl prosphonic acid mono-2-ethylhexyl ester (PC-88A) in toluene as the extractant was studied. Quantitative extraction of Ti(IV) was observed in the lower acidity range of 0.01 to 0.1 mol dm-3 with 0.003 mol dm-3 D2EHPA and 0.01 mol dm-3 PC-88A in toluene, respectively, and in the higher acidity range of 9.0 to 10.0 mol dm-3 with 0.1 mol dm-3 D2EHPA and PC-88A in toluene. Ti(IV) was completely stripped from the metal loaded organic phase of both the extractants with 3 % H2O2 in 1 M H2SO4 and determined spectrophotometrically. The stoichiometry of the extracted species was determined on the basis of slope analysis. The extraction in the lower acidity range was found to proceed by a cation-exchange mechanism with the extracted species being TiOR2·2HR, while in the higher acidity range it was by solvation with the extracted species being Ti(OH)3ClO4·4HR. Separation of Ti(IV) was also carried out from some associated metals like Fe(III), Al(III), V(V), Ce(IV), Mg(II) and Mn(II). The developed methods were extended for the determination of Ti(IV) in real samples like ilmenite, magnetite and red mud in order to show the practical utility of the extractants.
Optimization of reaction conditions for the electroleaching of manganese from low-grade pyrolusite  [PDF]
Xing-ran Zhang,Zuo-hua Liu,Xing Fan,Xin Lian,Chang-yuan Tao
- , 2015, DOI: https://doi.org/10.1007/s12613-015-1176-x
Abstract: In the present study, a response surface methodology was used to optimize the electroleaching of Mn from low-grade pyrolusite. Ferrous sulfate heptahydrate was used in this reaction as a reducing agent in sulfuric acid solutions. The effect of six process variables, including the mass ratio of ferrous sulfate heptahydrate to pyrolusite, mass ratio of sulfuric acid to pyrolusite, liquid-to-solid ratio, current density, leaching temperature, and leaching time, as well as their binary interactions, were modeled. The results revealed that the order of these factors with respect to their effects on the leaching efficiency were mass ratio of ferrous sulfate heptahydrate to pyrolusite > leaching time > mass ratio of sulfuric acid to pyrolusite > liquid-to-solid ratio > leaching temperature > current density. The optimum conditions were as follows: 1.10:1 mass ratio of ferrous sulfate heptahydrate to pyrolusite, 0.9:1 mass ratio of sulfuric acid to pyrolusite, liquid-to-solid ratio of 0.7:1, current density of 947 A/m2, leaching time of 180 min, and leaching temperature of 73°C. Under these conditions, the predicted leaching efficiency for Mn was 94.1%; the obtained experimental result was 95.7%, which confirmed the validity of the model.
YUAN Meng,LUO Aiqing,WANG Chun,LI Deqian,
,LUO Aiqing,WANG Chun,LI Deqian

金属学报(英文版) , 1995,
Abstract: Solvent extraction of trivalent lanthanides (except for Pm with Cyanex 302 Bis (2,4,4-trimethylpentyl)monothiophosphinic acid] in heptane was studied at various aqueous pH values, extractant concentrations and different temperatures. Cyanex 302 shows pretty good behaviours on the extraction of lanthanides, especially when extracting heavy lanthanides. However,purified Cyanex 302 exhibits signi ficantly lower extractability to lanthanides than raw extractant. The roles ofdifferent components ofraw Cyanex 302 were discussed to understand the reason of good extractability of the raw extractant. The lanthanides extraction stoichiometry is discussed on the basis ofexperimental results, which can be expressed as follows:
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