Process efficiency and optimisation of precipitated calcium carbonate (PCC) production from steel converter slag

Hannu Petteri Mattila, Inga Grigaliunaite, Arshe Said, Sami Filppula, Carl Johan Fogelholm, Ron Zevenhoven

    Research output: Chapter in Book/Conference proceedingConference contributionScientificpeer-review

    1 Citation (Scopus)

    Abstract

    CO2 emissions could be reduced with capture and storage (CCS) methods. CCS causes costs for the industry, creating an extra barrier for implementation of these techniques. A recently developed mineral carbonation process producing a valuable product covering process implementation costs is advanced towards commercial scale. In this two-step process, calcium-rich steel converter slag is treated with an aqueous ammonium salt solution to selectively extract the calcium. Then the dissolved calcium is removed from the process liquid as pure precipitated calcium carbonate (PCC) by introducing gaseous CO2 to the system. This concept would utilise waste material from steel industry, and spare the natural resources used for conventional PCC production. Experimental results have shown that papermaking grade PCC can be produced with ammonium nitrate, chloride or acetate solvents. The used solvent has also been regenerated and recycled between the process stages, which reduces the need for fresh solvent and lowers the process costs. To maximise the PCC production in a continuous process, a thermodynamic process model in Aspen Plus is now constructed. The modelling results are validated with a series of semi-continuous experiments. It is found that by using staged carbonate precipitation the yield of pure product is increased. Ammonium nitrate is observed to enable the highest conversion of calcium from steel slag to calcium carbonate also in continuous operation. At ambient conditions the process steps generate heat but this low temperature heat cannot be utilised. The mixing and pumping energies for process operation are small in comparison to the heat duties in chemical reactors. Preliminary results on solid-liquid separation studies, on washing of the solid outlet streams, as well as on recovery and make-up needs of process chemicals are discussed. The work is a continuation of work presented by Said et al. at 22nd ECOS in Brazil 2009.

    Original languageEnglish
    Title of host publicationProceedings of the 25th International Conference on Efficiency, Cost, Optimization and Simulation of Energy Conversion Systems and Processes, ECOS 2012
    PublisherÅbo Akademi University
    Pages218-232
    Number of pages15
    ISBN (Print)9788866553229
    Publication statusPublished - 2012
    MoE publication typeA4 Article in a conference publication
    Event25th International Conference on Efficiency, Cost, Optimization and Simulation of Energy Conversion Systems and Processes, ECOS 2012 - Perugia, Italy
    Duration: 26 Jun 201229 Jun 2012

    Publication series

    NameProceedings of the 25th International Conference on Efficiency, Cost, Optimization and Simulation of Energy Conversion Systems and Processes, ECOS 2012
    Volume6

    Conference

    Conference25th International Conference on Efficiency, Cost, Optimization and Simulation of Energy Conversion Systems and Processes, ECOS 2012
    CountryItaly
    CityPerugia
    Period26/06/1229/06/12

    Keywords

    • Ammonium salt solution
    • Chemical thermodynamics
    • Mineral carbonation
    • PH swing process
    • Steel converter slag

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