Direct gas-solid carbonation of serpentinite residues in the absence and presence of water vapor: a feasibility study for carbon dioxide sequestration

Our plain-English summary of Direct gas-solid carbonation of serpentinite residues in the absence and presence of water vapor: a feasibility study for carbon dioxide sequestration, by S.P. Veetil, L.C. Pasquier, J.F. Blais, et al (Environmental Science and Pollution Research International, 2015).

The study

• Authors: S.P. Veetil, L.C. Pasquier, J.F. Blais, E. Cecchi, S. Kentish, G. Mercier
• Journal: Environmental Science and Pollution Research International
• Published: 2015;22(17):13486-95
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Mineral carbonation of serpentinite mining residue offers an environmentally secure and permanent storage of carbon dioxide. The strategy of using readily available mining residue for the direct treatment of flue gas could improve the energy demand and economics of CO2 sequestration by avoiding the mineral extraction and separate CO2 capture steps. The present is a laboratory scale study to assess the possibility of CO2 fixation in serpentinite mining residues via direct gas-solid reaction. The degree of carbonation is measured both in the absence and presence of water vapor in a batch reactor. The gas used is a simulated gas mixture reproducing an average cement flue gas CO2 composition of 18 vol.% CO2. The reaction parameters considered are temperature, total gas pressure, time, and concentration of water vapor. In the absence of water vapor, the gas-solid carbonation of serpentinite mining residues is negligible, but the residues removed CO2 from the feed gas possibly due to reversible adsorption. The presence of small amount of water vapor enhances the gas-solid carbonation, but the measured rates are too low for practical application. The maximum CO2 fixation obtained is 0.07 g CO2 when reacting 1 g of residue at 200 °C and 25 barg (pCO2 ≈ 4.7) in a gas mixture containing 18 vol.% CO2 and 10 vol.% water vapor in 1 h. The fixation is likely surface limited and restricted due to poor gas-solid interaction. It was identified that both the relative humidity and carbon dioxide-water vapor ratio have a role in CO2 fixation regardless of the percentage of water vapor.

In plain English

This laboratory chemistry study did not examine health. In a small batch reactor, the authors tested whether ground serpentinite residue from the American chrome chromite mine near Coleraine, Québec, could fix CO2 from a simulated cement-plant flue gas (18 vol.% CO2). Without water vapor, the residue removed CO2 from the gas, more at higher pressure: 0.08 g CO2 per g at 25 °C and about 1 bar CO2 partial pressure. However, the reacted solids showed no detectable carbon or carbonates; the authors suggested possible reversible adsorption. Adding water vapor produced two magnesium carbonates (nesquehonite and hydromagnesite). Fixation peaked at 10% water vapor and fell at 15% and 20%. For American chrome residue, the maximum was 0.07 g CO2 per g, at 200 °C, 25 bar gauge pressure and 10% water vapor in 1 hour. In this one-hour test, heat-treated and untreated residue gave equal results, which the authors linked to the short reaction time. Black Lake chrysotile-mine residue fixed 0.08 g CO2 per g under the same conditions. The authors concluded that fixation was very low and surface-limited.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory-scale batch reactor experiment (mineral carbonation chemistry)
• Who was studied: Ground serpentinite mining residue (mainly lizardite) from the American chrome chromite mine near Coleraine, Southern Québec (ACR). A comparison sample of serpentinite mining residue (SMR) came from a chrysotile extraction mine at Black Lake, Quebec. No people were studied.
• Exposure: Residue was reacted with a simulated flue gas (18 vol.% CO2, 78 vol.% N2, balance O2) at 25 to 300 °C and 5 to 25 bar gauge pressure. Runs were done without water vapor and with water vapor at 5 to 20%. Some residue was first heat-treated at 650 °C for 30 min.
• Main results:
  • Without water vapor (raw ACR), carbon in the reacted solids was below the detection limit, and X-ray diffraction showed no carbonate species.
  • Without water vapor, CO2 removal from the gas by raw ACR increased with pressure. It plateaued near 15 bar gauge at 25 °C and near 20 bar gauge at 250 °C.
  • Without water vapor, at 25 °C and 1 bar CO2 partial pressure, ACR removed 0.08 g CO2 per g of residue.
  • With heat-treated ACR at 200 °C and 25 bar gauge pressure for 1 h, both CO2 removal and CO2 fixation rose up to 10% water vapor and then fell. Fixation capacity was 0.06 (5%), 0.07 (10%), 0.04 (15%) and 0.02 (20%) g CO2 per g of residue.
  • After reaction with 10% water vapor, the solid contained two hydrated magnesium carbonates, confirming carbonation.
  • In the one-hour comparison under identical conditions (200 °C, 25 bar gauge pressure, 10% water vapor), fixation capacity was 0.07 g CO2 per g of residue for both heat-treated and raw ACR, and 0.08 g CO2 per g of residue for the raw Black Lake residue (SMR). The authors linked the equal results for treated and untreated ACR to the short experiment time, and expected heat-treated residue to do better over longer times.
  • For American chrome residue, the maximum CO2 fixation as carbonates was 0.07 g CO2 from 1 g of residue, at 200 °C, 25 bar gauge pressure and 10 vol.% water vapor in 1 h.
  • Blank runs, with an empty reactor and with non-reactive quartz, showed no CO2 removal.
• The authors' conclusion: The authors concluded that water vapor enhanced carbonation but that CO2 fixation was very low and surface-limited. They called the work only a first step.
• Limitations the authors state:
  • The proposed fixation mechanism rests on assumptions from earlier published work; more extensive studies may be needed to understand it.
  • The authors linked the lack of difference between heat-treated and untreated samples to the short experiment time.
  • The authors said a more sophisticated setup with better gas-solid interaction would be needed.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Lake Asbestos of Quebec, Black Lake, Quebec

All asbestos mines

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Serpentinite.

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