Borate autocausticizing equilibria in recovery boiler smelt

Daniel Kristoffer Lindberg, R Backman, Mikko Hupa, S Kochesfahani, H Rickards, L Perander

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

    2 Citations (Scopus)


    Partial borate autocausticizing is an interesting option for eliminating bottlenecks at the recaust plant and the lime kiln of a kraft pulp mill chem. recovery process.  The autocausticizing reactions may to some extent occur already in the early stages of the black liquor droplet combustion, but they can also occur in the recovery boiler smelt, mainly as a reaction between sodium carbonate and sodium metaborate.  It is of vital importance to understand the equil. of borate compds. in the smelt to obtain optimum conditions for the autocausticizing reactions in the recovery boiler.  The effect of the potassium and boron concn. in the salt mixt. and CO2 in the gas on the autocausticizing reactions in the recovery boiler smelt was studied by thermogravimetry and thermal anal.  Results show that the autocausticizing reaction is readily reversible with 1 % CO2 or higher in the gas atm. in pure sodium systems.  Higher CO2 and potassium concn. lead to lower autocausticizing.  In pure potassium systems, the autocausticizing is low and the wt. loss is irreversible.  In potassium-​rich systems volatilization of alkali- and​/or boron-​components becomes more prominent than in sodium systems.
    Original languageUndefined/Unknown
    Title of host publication2004 International Chemical Recovery Conference
    EditorsTechnical Association of the Pulp, Paper Industry
    PublisherTAPPI Press
    ISBN (Print)1-59510-039-3
    Publication statusPublished - 2004
    MoE publication typeA4 Article in a conference publication
    Eventconference; 2004-06-06; 2004-06-10 - Charleston, SC, USA
    Duration: 6 Jun 200410 Jun 2004


    Conferenceconference; 2004-06-06; 2004-06-10

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