Chlorination of Euxenite Concentrates

Henderson, A. W.; May, Sibylle; Higbie, Kenneth B.

doi:10.1021/ie50580a028

Cited by 16 publications

(4 citation statements)

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“…Activation of Cl 2 on the carbon surface b. Chlorination of Ta 2 O 5 [5] c. Oxidation of carbon [6] [7] [8] d. Formation of phosgene [9] e. Phosgene as chlorinating agent [10] f . Activation of Cl 2 on the carbon surface b. Chlorination of Ta 2 O 5 [5] c. Oxidation of carbon [6] [7] [8] d. Formation of phosgene [9] e. Phosgene as chlorinating agent [10] f .…”

Section: Reaction Mechanismmentioning

confidence: 99%

Kinetics of chlorination of tantalum pentoxide in mixture with sucrose carbon by chlorine gas

Ruiz

González

Rivarola

2004

Metall Mater Trans B

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The mechanism and kinetics of ␤-Ta 2 O 5 chlorination, mixed with sucrose carbon, have been studied by a thermogravimetric technique. The investigated temperature range was 500°C to 850°C. The reactants and reaction residues were analyzed by scanning electronic microscopy (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller method for surface area (BET). The effect of various experimental parameters was studied, such as carbon percentage, temperature, chlorine partial pressure, and flow, use of the multiple sample method, and carbon previous oxidation. The carbon percentage and previous treatment have an effect on the system reactivity. The temperature has a marked effect on the reaction rate. In the 500°C to 600°C temperature interval, the apparent activation energy is 144 kJ/mol of oxide, while at higher temperatures, the activation energy decreases. With high chorine partial pressures, the order of reaction is near zero. The kinetic contractile plate model, X ϭ kt, considering carbon oxidation as the controlling stage, is the one with the best fit to the experimental data. A probable mechanism for the carbochlorination of ␤-Ta 2 O 5 is proposed: (1) activation of chlorine on the carbon surface, (2) chlorination of Ta 2 O 5 , (3) oxidation of carbon, and (4) recrystallization of ␤-Ta 2 O 5 .

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Section: Reaction Mechanismmentioning

confidence: 99%

Kinetics of chlorination of tantalum pentoxide in mixture with sucrose carbon by chlorine gas

Ruiz

González

Rivarola

2004

Metall Mater Trans B

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“…minutes, and the constant k 0 is in min Ϫ1 m 0.7 kPa Ϫ0. 6 REPO 4 ϩ 3C ϩ 3Cl 2 → RECl 3 ϩ POCl 3 ϩ 3CO [7] F. Reaction Mechanism of Xenotime with CCl 4 ϩ N 2 REPO 4 ϩ3/2Cϩ3Cl 2 →RECl 3 ϩPOCl 3 ϩ3/2CO [8] Unfortunately, there are not many reports dealing with chlorination of rare earth elements, even their ores, [12][13][14][15][16][17] REPO 4 ϩ 3Cl 2 → RECl 3 ϩ POCl 3 ϩ 3/2 O 2 [9] and most of them concern the reaction with chlorine and carbon. Moreover, as far we know, not many efforts have 2C ϩ O 2 → 2CO…”

Section: Effect Of Temperaturementioning

confidence: 99%

“…[14][15][16][17] Hartley and Wylie [12] reported the preparation of C ϩ O 2 → CO 2 [11] lanthanide chlorides by reacting chlorine with monazite ore at temperatures above 973 K, using carbon and carbon mon-2CO ϩ O 2 → 2CO 2 [12] oxide as reducing agents. They also investigated the influence of particle size, gas flow rate, temperature, and carbon…”

Section: Effect Of Temperaturementioning

confidence: 99%

“…ϩ 1/2COCl 2 REPO 4 ϩ3Cϩ3/2Cl 2 →RECl 3 ϩ1/4P 4 ϩ4CO [15] and then, as the reaction was carried out, we had the production of the following products: Ozaki et al [17] studied the chlorination of monazite with carbon tetrachloride and concluded that the reaction follows REOCl ϩ 1/2CCl 4 → RECl 3 ϩ 1/2CO 2 [17] a topochemical process and obeys the relationship 1 Ϫ (1 Ϫ X ) 1/3 ϭ kt. Moreover, the authors suggested that the kinetic control step was the reaction at the interface.…”

Section: Effect Of Temperaturementioning

confidence: 99%

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Kinetics of chlorination and microstructural changes of xenotime by carbon tetrachloride

Augusto

Oliveira

2001

Metall Mater Trans B

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Among the rare earth minerals, fluorides, phosphates, and oxides have received attention from the rare earth industry. Traditional methods of decomposition of these minerals, usually alkaline or acid processes, involve several operations. Another possibility to obtain lanthanide chlorides or oxychlorides is reacting the mineral with chlorinating agents, such as gaseous chlorine, hydrogen chloride, thionyl chloride, and carbon tetrachloride, reducing the operation costs and making the process less complicated. In this context, we investigated the decomposition of xenotime using carbon tetrachloride at temperatures from 873 to 1173 K and kinetic and mechanistic studies have been performed. Powder X-ray diffraction, scanning electronic microscopy, energy dispersive X-ray spectrometry, ultra-violet/ visible spectroscopy, and thermal analysis techniques were used in this study. The results showed that the reaction follows the shrinking-unreacted-core model with formation of a product layer (lanthanide oxychloride), confirmed by powder X-ray diffraction. Moreover, microstructural changes of xenotime grains during the chlorination reaction were verified.

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Chlorination of ores and concentrates

Henderson¹

1964

JOM

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Chlorination of Euxenite Concentrates

Cited by 16 publications

References 0 publications

Kinetics of chlorination of tantalum pentoxide in mixture with sucrose carbon by chlorine gas

Kinetics of chlorination of tantalum pentoxide in mixture with sucrose carbon by chlorine gas

Kinetics of chlorination and microstructural changes of xenotime by carbon tetrachloride

Chlorination of ores and concentrates

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