brown coal hard coal 13 mining engineering 11 coal 11 metallurgy 9 analytical chemistry 7 history 7 more ... surface mining 7 combustion 6 briquetting 5 mining 5 environment protection 4 desulphurization 4 landscape recultivation 4 coal energy sources 3 fluid boilers 3 geology 3 caustobiolite deposits 3 deposit geology 3 deposit prospecting 3 simulation and modelling 3 academic theses 3 biomass 2 deposits mining 2 steam-gas cycles power stations 2 issues 2 geologic basins 2 deep mining 2 mineral deposits 2 carbon dioxide 2 less ...