Analytical methods for determination of sulfur content in oil shalePikkor, Heliis16th International Symposium "Topical Problems in the Field of Electrical and Power Engineering. Doctoral School of Energy and Geotechnology III" : Pärnu, Estonia, January 16-21, 20172017 / p. 213-215 : ill http://www.ester.ee/record=b4650094*est

Characterization and enhancement of oil shale fly ash from CFB boilerPikkor, Heliis; Järvik, Oliver; Lees, Heidi; Konist, Alar; Siirde, Andres; Maaten, Birgit6th International Conference on Smart and Sustainable Technologies, SpliTech 20212021 / p. 1-4 https://doi.org/10.23919/SpliTech52315.2021.9566470

Characterization of oil shale kerogen semi-coke and its application to remove chemical pollutants from aqueous solutionsLees, Heidi; Jõul, Piia; Pikkor, Heliis; Järvik, Oliver; Mets, Birgit; Konist, AlarOil shale2023 / p. 115-132 : ill https://doi.org/10.3176/oil.2023.2.02

Co-combustion of coal and oil shale blends in circulating fluidized bed boilersKonist, Alar; Pikkor, Heliis; Nešumajev, Dmitri; Loo, Lauri; Järvik, Oliver; Siirde, Andres; Pihu, TõnuOil shale2019 / p. 114–127 : ill https://doi.org/10.3176/oil.2019.2S.03 http://www.kirj.ee/public/oilshale_pdf/2019/issue_2S/OS-2019-2S-114-127.pdf Journal metrics at Scopus Article at Scopus Journal metrics at WOS Article at WOS

Comparison of the porous structure of oil shale fly ashes from two different CFB boilersPikkor, Heliis18th International Symposium "Topical Problems in the Field of Electrical and Power Engineering". Doctoral School of Energy and Geotechnology III : Toila, Estonia, January 14-19, 2019 : [proceedings]2019 / p. 99-100 : ill https://www.ester.ee/record=b5183874*est

Determination of the total sulphur content of oil shale by using different analytical methodsMaaten, Birgit; Pikkor, Heliis; Konist, Alar; Siirde, AndresOil shale2018 / p. 144-153 : ill https://doi.org/10.3176/oil.2018.2.04 Journal metrics at Scopus Article at Scopus Journal metrics at WOS Article at WOS

Effect of steam activation on oil shale semi-coke surface propertiesPikkor, Heliis; Konist, Alar; Maaten, Birgit; Järvik, Oliver; Lees, HeidiInternational Multidisciplinary Conference on Computer and Energy Science (SpliTech)2021 / 5 p https://doi.org/10.23919/SpliTech52315.2021.9566397

Fast pyrolysis as a new approach to the upgrading of oil shale retorting methodsPikkor, Heliis; Maaten, Birgit; Siirde, AndresInternational IX Oil Shale Conference 2017 "Oil Shale Industry in Circular Economy" : 15th-16th November 2017, [Jõhvi], Ida-Viru County, Estonia : summary2017 / p. 23 http://www.ester.ee/record=b4751282*est

Fluidized bed pyrolysis as a new approach for shale oil productionPikkor, Heliis; Siirde, Andres17th International Symposium “Topical Problems in the Field of Electrical and Power Engineering”. Doctoral school of energy and geotechnology. III : Kuressaare, Estonia, January 15-20, 20182018 / p. 277-279 : ill http://ise.elnet.ee/record=b2950220~S2*est

Steam activation of oil shale to enhance the porosity of produced semicokePikkor, Heliis; Lees, Heidi; Konist, Alar; Järvik, Oliver; Maaten, BirgitEnergy Sources, Part A : Recovery, Utilization, and Environmental Effects2022 / p. 9064-9073 https://doi.org/10.1080/15567036.2022.2128471 Journal metrics at Scopus Article at Scopus Journal metrics at WOS Article at WOS

Surface area of oil shale and its solid pyrolysis products depending on the particle sizePikkor, Heliis; Maaten, Birgit; Baird, Zachariah Steven; Järvik, Oliver; Konist, Alar; Lees, HeidiChemical engineering transactions2020 / p. 961−966 https://doi.org/0.3303/CET2081161 Journal metrics at Scopus Article at Scopus

Surface characterisation of Estonian oil shale semi-cokePikkor, Heliis; Lees, Heidi; Maaten, Birgit; Järvik, Oliver; Konist, AlarChemical engineering transactions2020 / p. 853-858 : ill https://doi.org/0.3303/CET2081143 Journal metrics at Scopus Article at Scopus

Utilization of pyrolytic wastewater in oil shale fired CFBC boilerKonist, Alar; Järvik, Oliver; Pikkor, Heliis; Nešumajev, Dmitri; Pihu, TõnuJournal of cleaner production2019 / p. 487-493 : ill https://doi.org/10.1016/j.jclepro.2019.06.213 Journal metrics at Scopus Article at Scopus Journal metrics at WOS Article at WOS