Potential for CO2 sequestration as mineral carbonate within Ni laterite processing

Steel, Karen, Alizadehhesari, Kimia, Fox, Kristiane and Balucan, Reydick (2013). Potential for CO2 sequestration as mineral carbonate within Ni laterite processing. In: Proceedings of ALTA 2013 Nickel-Cobalt-Copper Sessions. ALTA 2013: Nickel-Cobalt-Copper, Uranium-REE and Gold Conference & Exhibition, Perth, Australia, (424-431). 27-30 May 2013.

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Name Description MIMEType Size Downloads
Author Steel, Karen
Alizadehhesari, Kimia
Fox, Kristiane
Balucan, Reydick
Title of paper Potential for CO2 sequestration as mineral carbonate within Ni laterite processing
Formatted title
Potential for CO2 sequestration as mineral carbonate within Ni laterite processing
Conference name ALTA 2013: Nickel-Cobalt-Copper, Uranium-REE and Gold Conference & Exhibition
Conference location Perth, Australia
Conference dates 27-30 May 2013
Proceedings title Proceedings of ALTA 2013 Nickel-Cobalt-Copper Sessions
Place of Publication Melbourne, Australia
Publisher ALTA Metallurgical Services Publications
Publication Year 2013
Sub-type Fully published paper
Open Access Status
ISBN 9780987126269
Start page 424
End page 431
Total pages 8
Language eng
Formatted Abstract/Summary
Worldwide there is a large research effort into technologies for the sequestration of CO2 due to the overwhelming concern of what might happen if there is a runaway greenhouse effect. One potential technology being pursued examines whether the enormous reserves of magnesium silicates in the earth could be converted to magnesium carbonate which is considered to be a safer option than the storage of supercritical CO2 deep underground. But a viable technology has not been found because the use of acid and base, in the traditional processing sense, is prohibitive due to the scale and need for both low energy and low cost. One idea that might circumvent this problem is to use a regenerable buffer to enable both low pH for Mg dissolution and high pH for MgCO3 carbonation.

Given that the magnesium silicate reserves of interest also contain significant levels of Ni, it could be worthwhile to combine the CO2 sequestration pursuit with the pursuit of Ni extraction, whereby a symbiotic relationship exists and the two operations can assist each other to achieve technical, environmental and economic process goals.

This paper presents our work to date on the use of a tertiary amine as a regenerable buffer, including a process concept. We have found that both tripropylamine and triethylamine are capable of raising the pH of an acidic solution to over 8 and therefore able to precipitate MgCO3 when added to the extract solution from the treatment of serpentinite with HCl while low pressures of CO2 are also sparged into the solution. Precipitation of the carbonate was found to occur within minutes. It has been found that the amine can be regenerated through heating to over 80ºC. Preliminary work has shown that the pH can be decreased to 3.4. The precise mechanism for regeneration is still being established, however, it appears that when heated, the miscibility of triethylamine in water decreases dramatically and that phase separation of it might be the driving force for the dissociation of protons from the amine.

Future work is focused on: Potential for amines to be regenerated such that the corresponding acid concentration is capable of dissolving both Mg and Ni from serpentinites in a reasonable timeframe; evaluation of technical feasibility of each unit operation needed for the overall process; determination of potential for selective precipitation of Mg and Ni carbonates; identification of optimum amine and acid counter ion. If the process is successful with a sulphate counter ion there is also the potential to treat Mg sulphate tailings to regenerate sulphuric acid.
Q-Index Code EX
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Conference Paper
Collection: School of Chemical Engineering Publications
 
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Created: Mon, 31 Mar 2014, 13:45:50 EST by Dr Karen Steel on behalf of School of Chemical Engineering