• 4th International Symposium on the Reclamation Treatment and Utilization of coal mining wastes. (printed paper). Date: 6-10 September, 1993, Krakow, Poland
• 8th International Conference on Coal Science (printed paper). Date: 10-15 September, 1995, Oviedo, Spain
• 9th International Conference on Coal Science (printed paper). Date: 7-12 September, 1997, Essen, Germany
• 2nd Balkan Conference “Industrial Polution” (printed abstract). Date: 19-21 November, 1999, Sofia, Bulgaria
• 22nd Annual International Pittsburg Coal Conference: Coal - Energy, Environment and Sustainable Development, Sept., 12-15, 2005, Pittsburg, PA, USA (printed abstract and paper on CD-ROM)
• International Conference on Coal Science and Technology (ICS&T), Oct., 9-14, 2005, Okinawa, Japan, (printed abstract and paper on CD-ROM)
• International Conference on Coal Science and Technology (ICCS&T), August 28th - 31st 2007, Nottingham, UK, (printed abstract and paper on CD-ROM).
• 11th Coal Geology Conference, May 26 to 30, 2008, Prague, Czech Republic (printed abstracts and papers in press GeoLines, 22, 2009)
• Fourth International Conference on Clean Coal Technologies CCT2009, 3rd International Freiberg Conference on IGCC & XtL Technologies (paper on CD-ROM), May 18-21, 2009, Dresden, Germany
• International Conference on Coal Science & Technology (ICCS&T), (paper submitted in Fuel Processing Technology), October 26-29, 2009 - Cape Town, South Africa.
• Mineral deposit research for a high-tech world. 12th Biennal SGA Meeting, 12-15 August 2013, Uppsala, Sweden.
• emc2016 - 2nd European Mineralogical Conference. September 11th-15th, Rimini, Italy.

Others