SULFIDATION OF Al2O3WITH CS2GAS FOR COMPACT ALUMINIUM PRODUCTION PROCESS

Xiao, Yonghou; Plas, D. W. van der; Soons, J.; Lans, S.C.; Sandwijk, A. van; Reuter, M.A.

doi:10.1179/cmq.2004.43.2.283

Cited by 6 publications

(14 citation statements)

References 2 publications

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“…However, the total time of the experiment is about 90 min, which is substantially lower than the equilibrium time of 5 h derived from solubility experiments. 9 Therefore it is possible that the reduction process is faster than the dissolution process, and the melt becomes gradually depleted of Al 2 S 3 . This may explain the gradual reduction of the current density in Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Considering the low solubility of Al 2 S 3 ͑ϳ0.32 wt %͒ in the MgCl 2 -NaCl-KCl eutectic with 10 wt % cryolite at 850°C, 9 initially only a small fraction of the total 4 wt % of Al 2 S 3 is dissolved in the melt. As the initially dissolved Al 2 S 3 is reduced, more Al 2 S 3 may dissolve.…”

Section: Discussionmentioning

confidence: 99%

“…From solubility experiments it was observed that the solubility of Al 2 S 3 in the electrolyte increases by a factor of four when adding 10 wt % of cryolite to the electrolyte. 9 In addition, the specific conductivity of cryolite ͑2.79…”

Section: Electrolysis Of Al 2 S 3 In Mgclmentioning

confidence: 99%

“…4,5 In this process, Al 2 S 3 is produced by the reaction of CS 2 and alumina. Subsequently, the aluminum metal can be extracted by electrolysis, producing sulfur gas at the anode, which can be recycled to the production of CS 2 .…”

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confidence: 99%

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Electrowinning Al from Al[sub 2]S[sub 3] in Molten Salt

Yan

Plas²,

Bohte

et al. 2007

J. Electrochem. Soc.

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In order to investigate an alternative process for the production of primary aluminum via a sulfide intermediate, the electrochemical behavior of Al 2 S 3 in molten salt has been studied on a laboratory scale. The effects of electrolyte composition, temperature, and cell design on the cell performance have been investigated. Temperature and cryolite addition have positive effects on the current density. Increasing the anode-to-cathode surface area ͑closer to unity͒ and shortening the interelectrode distance lead to higher current density. It is concluded that the electrolytic process is governed by the ohmic drop, caused mainly by the sulfur bubbles at the anode. © 2007 The Electrochemical Society. ͓DOI: 10.1149/1.2728263͔ All rights reserved.Manuscript submitted October 9, 2006; revised manuscript received February 9, 2007. Available electronically April 23, 2007. In terms of primary energy consumption, the Hall-Héroult process requires about 140 MJ energy to produce 1 kg of aluminum metal, which is about four times the theoretical thermodynamic minimum ͑34 MJ/kg Al͒. Apart from substantial CO 2 and SO 2 emissions from the production of electrical energy as well as the consumption of carbon anodes, the Hall-Héroult process creates greenhouse gas emissions such as CF 4 and C 2 F 6 stemming from the electrolyte that consists mainly of liquid cryolite ͑Na 3 AlF 6 ͒. These and other apparent disadvantages of the Hall-Héroult process have led to numerous research efforts to find an alternative route for primary aluminum production throughout the 20th century.The best investigated alternatives are inert anodes, 1 the use of AlCl 3 as an intermediate step,2 and the carbothermic reduction of alumina.3 Inert anodes would enable a closed cell concept that is more favorable in terms of environment, energy efficiency, and capital cost. The aluminum chloride process comprises the chlorination of Al 2 O 3 to AlCl 3 as an intermediate, and subsequent reduction of AlCl 3 to aluminum in an electrolysis cell. Due to the lower cell voltage required, the carbon anode remains inert and less electrical energy is required compared to an inert electrode process based on the reduction of alumina. Carbothermic reduction would eliminate the electrolysis step altogether, but high temperatures in excess of 2000°C would be required. Despite the substantial amount of capital spent on these and other processes, no proven and economically feasible alternative to the Hall-Héroult process to date exists.Another alternative is to use aluminum sulfide as an intermediate step, named the Compact Aluminum Production Process ͑CAPP™͒. 4,5 In this process, Al 2 S 3 is produced by the reaction of CS 2 and alumina. Subsequently, the aluminum metal can be extracted by electrolysis, producing sulfur gas at the anode, which can be recycled to the production of CS 2 . The simplified reactions ͑as-suming no complex ions͒ of the electrolysis process can be described as follows Due to the lower cell voltage required, the carbon anode remains inert and less el...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Electrolysis Of Al 2 S 3 In Mgclmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Electrowinning Al from Al[sub 2]S[sub 3] in Molten Salt

Yan

Plas²,

Bohte

et al. 2007

J. Electrochem. Soc.

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“…Energy efficiency is approaching about 50% of the theoretical heat of reaction, but further significant improvements in energy efficiency may be hard to achieve with the existing cell design (Beck 2008). Apart from the large energy requirements, the electrolysis of alumina requires high capital costs and is associated with a substantial environmental burden (Xiao et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Novel multi-stage aluminium production: part 1 – thermodynamic assessment of carbosulphidation of Al₂O₃/bauxite using H₂S and sodiothermic reduction of Al₂S₃

Rhamdhani

Huda

Khaliq

et al. 2017

Mineral Processing and Extractive Metallurgy

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A novel multi-stage Al production through a carbosulphidation of Al 2 O 3 , followed by a sodiothermic reduction of Al 2 S 3 , was proposed. In Stage-1, alumina (or bauxite) is reduced to Al 2 S 3 in the presence of carbon and H 2 S. In Stage-2, Al 2 S 3 is reduced to Al through reactions with Na or NaH. The thermodynamic analysis predicted Al 2 S 3 to be the main intermediate Alcompound when H 2 S is reacted with Al 2 S 3 and C at 1000-2000°C at 1 atm. Al 2 S 3 formation was predicted to be low at 1100-1300°C at 1 atm (0.1 moles/mole Al 2 O 3 ) but increased with increasing temperature (0.96 moles/mole Al 2 O 3 at 1800°C). The thermodynamic analysis of sodiothermic reduction predicted that Al metal can be extracted from Al 2 S 3 below 800°C at 1 atm. The Na 2 S produced can be hydrolysed to form H 2 S and NaOH. H 2 S can be re-used and the Na can be reproduced from NaOH and put back into the process.

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