Measuring the sintering tendency of ash by a laboratory method

Mikko Hupa, Bengt-Johan Skrifvars, Antero Moilanen

Research output: Contribution to journalArticleScientificpeer-review

25 Citations (Scopus)


A laboratory method for measuring ash-sintering tendency was developed and applied to peat gasification ashes and to flue gas dust from recovery furnaces of kraft pulp mills. The method is based on compression-strength measurements of sintered pellets, and it can be used in two ways: for comparing the sintering tendency of different fly ashes collected from flue gases; and for testing the influence of different factors on fly ash sintering by means of synthetic samples.
The synthetic sample - which can be a laboratory ash or a mixture of chemical compounds - is first melted in a controlled gas atmosphere, and the slag obtained in this way is crushed and screened. The particle size of is selected for pelletizing and sintering tests; variations in particle size are thus eliminated. If sintering of fly ash collected from flue gases is investigated, the pre-melt crushing and screening stage is excluded, and pellets are made directly from the collected fly ash. Examples are presented of results obtained from synthetic samples and fly ash collected from flue gases, and from microscopic studies of sintered samples. Sintering is significantly affected by, for example, the potassium and chloride contents of the recovery boiler dust. Various peat-gasification ashes differed in their sintering tendency; the main variable was iron content. The reproducibility of strength tests was good, as a consequence of the controlled particle size. This makes the method particularly suitable for studying the influence on sintering tendency of temperature, gas composition and chemical composition.
Original languageEnglish
Pages (from-to)131-137
JournalJournal of the Institute of Energy
Issue number452
Publication statusPublished - 1989
MoE publication typeA1 Journal article-refereed


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