Quantification of the CO 2 mineralization potential of ironmaking and steelmaking slags under direct gas-solid reactions in flue gas

Corey A. Myers, Takao Nakagaki, Kosei Akutsu

Research output: Contribution to journalArticle

Abstract

The potential for slag to reduce CO 2 emissions in the iron and steelmaking industry through CO 2 mineralization has long been recognized. Direct, gas-solid CO 2 mineralization has major benefits of simplicity, cost, and CO 2 accounting but has been historically plagued by ‘slow kinetics’. To determine the cause of the slow kinetics, 22 crystalline minerals and 13 amorphous compounds common to slag were synthesized and reacted with CO 2 in an incubator held at 30 °C, a relative humidity of 90%, and a molar CO 2 concentration of 5% and 20%. It was found that diffusivity through the product layer varies by ˜8 orders of magnitude between minerals, with several minerals displaying complete passivation after only a few nanometers of mineralization. Such unreactive materials can effectively occlude mineralization of more reactive minerals (‘mineral locking’). Quantitative theories were developed to determine the influence of mineral locking and diffusivity variability on the bulk CO 2 mineralization rate. By reducing the size ratio of slag particle to the internal mineral grains the effects of mineral locking can be removed. Such alteration can be achieved by grinding or by generating larger mineral grains via a slow solidification of molten slag. As grinding is ultimately a necessary activity of direct, gas-solid CO 2 mineralization, the mineral-specific grinding energy for 39 common slag compounds was calculated and used to determine the CO 2 emissions associated with grinding. These data, along with a modification to the Shrinking Core Model, were used to determine the rate of CO 2 mineralization and the net CO 2 mineralization of blast furnace, basic oxygen furnace, and electric arc furnace slag. Results indicate that direct, gas-solid CO 2 mineralization can be achieved in 1 h at very high net CO 2 mineralization efficiencies, especially when renewable energy is the power source and when slag has been slowly solidified. Globally, this method could provide gigatonnes of CO 2 emissions reduction by the end of the century.

Original languageEnglish
Pages (from-to)100-111
Number of pages12
JournalInternational Journal of Greenhouse Gas Control
Volume87
DOIs
Publication statusPublished - 2019 Aug 1

Fingerprint

Steelmaking
slag
Flue gases
Slags
Minerals
mineralization
mineral
Gases
gas
grinding
diffusivity
flue gas
Basic oxygen converters
kinetics
Kinetics
Electric arcs
solidification
Blast furnaces
Passivation
Solidification

Keywords

  • CCUS
  • CO sequestration
  • Mineral carbonation

ASJC Scopus subject areas

  • Pollution
  • Energy(all)
  • Industrial and Manufacturing Engineering
  • Management, Monitoring, Policy and Law

Cite this

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title = "Quantification of the CO 2 mineralization potential of ironmaking and steelmaking slags under direct gas-solid reactions in flue gas",
abstract = "The potential for slag to reduce CO 2 emissions in the iron and steelmaking industry through CO 2 mineralization has long been recognized. Direct, gas-solid CO 2 mineralization has major benefits of simplicity, cost, and CO 2 accounting but has been historically plagued by ‘slow kinetics’. To determine the cause of the slow kinetics, 22 crystalline minerals and 13 amorphous compounds common to slag were synthesized and reacted with CO 2 in an incubator held at 30 °C, a relative humidity of 90{\%}, and a molar CO 2 concentration of 5{\%} and 20{\%}. It was found that diffusivity through the product layer varies by ˜8 orders of magnitude between minerals, with several minerals displaying complete passivation after only a few nanometers of mineralization. Such unreactive materials can effectively occlude mineralization of more reactive minerals (‘mineral locking’). Quantitative theories were developed to determine the influence of mineral locking and diffusivity variability on the bulk CO 2 mineralization rate. By reducing the size ratio of slag particle to the internal mineral grains the effects of mineral locking can be removed. Such alteration can be achieved by grinding or by generating larger mineral grains via a slow solidification of molten slag. As grinding is ultimately a necessary activity of direct, gas-solid CO 2 mineralization, the mineral-specific grinding energy for 39 common slag compounds was calculated and used to determine the CO 2 emissions associated with grinding. These data, along with a modification to the Shrinking Core Model, were used to determine the rate of CO 2 mineralization and the net CO 2 mineralization of blast furnace, basic oxygen furnace, and electric arc furnace slag. Results indicate that direct, gas-solid CO 2 mineralization can be achieved in 1 h at very high net CO 2 mineralization efficiencies, especially when renewable energy is the power source and when slag has been slowly solidified. Globally, this method could provide gigatonnes of CO 2 emissions reduction by the end of the century.",
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T1 - Quantification of the CO 2 mineralization potential of ironmaking and steelmaking slags under direct gas-solid reactions in flue gas

AU - Myers, Corey A.

AU - Nakagaki, Takao

AU - Akutsu, Kosei

PY - 2019/8/1

Y1 - 2019/8/1

N2 - The potential for slag to reduce CO 2 emissions in the iron and steelmaking industry through CO 2 mineralization has long been recognized. Direct, gas-solid CO 2 mineralization has major benefits of simplicity, cost, and CO 2 accounting but has been historically plagued by ‘slow kinetics’. To determine the cause of the slow kinetics, 22 crystalline minerals and 13 amorphous compounds common to slag were synthesized and reacted with CO 2 in an incubator held at 30 °C, a relative humidity of 90%, and a molar CO 2 concentration of 5% and 20%. It was found that diffusivity through the product layer varies by ˜8 orders of magnitude between minerals, with several minerals displaying complete passivation after only a few nanometers of mineralization. Such unreactive materials can effectively occlude mineralization of more reactive minerals (‘mineral locking’). Quantitative theories were developed to determine the influence of mineral locking and diffusivity variability on the bulk CO 2 mineralization rate. By reducing the size ratio of slag particle to the internal mineral grains the effects of mineral locking can be removed. Such alteration can be achieved by grinding or by generating larger mineral grains via a slow solidification of molten slag. As grinding is ultimately a necessary activity of direct, gas-solid CO 2 mineralization, the mineral-specific grinding energy for 39 common slag compounds was calculated and used to determine the CO 2 emissions associated with grinding. These data, along with a modification to the Shrinking Core Model, were used to determine the rate of CO 2 mineralization and the net CO 2 mineralization of blast furnace, basic oxygen furnace, and electric arc furnace slag. Results indicate that direct, gas-solid CO 2 mineralization can be achieved in 1 h at very high net CO 2 mineralization efficiencies, especially when renewable energy is the power source and when slag has been slowly solidified. Globally, this method could provide gigatonnes of CO 2 emissions reduction by the end of the century.

AB - The potential for slag to reduce CO 2 emissions in the iron and steelmaking industry through CO 2 mineralization has long been recognized. Direct, gas-solid CO 2 mineralization has major benefits of simplicity, cost, and CO 2 accounting but has been historically plagued by ‘slow kinetics’. To determine the cause of the slow kinetics, 22 crystalline minerals and 13 amorphous compounds common to slag were synthesized and reacted with CO 2 in an incubator held at 30 °C, a relative humidity of 90%, and a molar CO 2 concentration of 5% and 20%. It was found that diffusivity through the product layer varies by ˜8 orders of magnitude between minerals, with several minerals displaying complete passivation after only a few nanometers of mineralization. Such unreactive materials can effectively occlude mineralization of more reactive minerals (‘mineral locking’). Quantitative theories were developed to determine the influence of mineral locking and diffusivity variability on the bulk CO 2 mineralization rate. By reducing the size ratio of slag particle to the internal mineral grains the effects of mineral locking can be removed. Such alteration can be achieved by grinding or by generating larger mineral grains via a slow solidification of molten slag. As grinding is ultimately a necessary activity of direct, gas-solid CO 2 mineralization, the mineral-specific grinding energy for 39 common slag compounds was calculated and used to determine the CO 2 emissions associated with grinding. These data, along with a modification to the Shrinking Core Model, were used to determine the rate of CO 2 mineralization and the net CO 2 mineralization of blast furnace, basic oxygen furnace, and electric arc furnace slag. Results indicate that direct, gas-solid CO 2 mineralization can be achieved in 1 h at very high net CO 2 mineralization efficiencies, especially when renewable energy is the power source and when slag has been slowly solidified. Globally, this method could provide gigatonnes of CO 2 emissions reduction by the end of the century.

KW - CCUS

KW - CO sequestration

KW - Mineral carbonation

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