brown coal hard coal 13 surface mining 11 coal 11 mining engineering 10 opencast quarry mining 10 metallurgy 9 more ... analytical chemistry 7 combustion 6 briquetting 4 coal energy sources 4 environment protection 4 desulphurization 4 mining 4 deposits mining 3 fluid boilers 3 geology 3 deposit geology 3 deposit prospecting 3 landscape recultivation 3 simulation and modelling 3 academic theses 3 biomass 2 mine fires 2 steam-gas cycles power stations 2 issues 2 power engineering 2 geologic basins 2 caustobiolite deposits 2 mineral deposits 2 less ...