In Poland, brown coal deposits occur in young geological formations, mainly the Tertiary. Older brown coal deposits are known to occur also in the Jurassic, Carboniferous and locally even Cretaceous and Triassic in several places in the world. The brown coals are intermediate in qualification between hard coal and peat. Their characteristics and properties were markedly influenced by the type of parent plant material and environment in which they originated.
Brown coal deposits originated both in platform areas and sedimentary basins in orogenic belts. The coals form extensive seams or lenses a few meters to several dozen meters in thickness. Thickness of overburden is usually quite small which makes possible opencast mining of the deposits.
There are brown coal deposits occurying in Poland presented on the map.
Seams of older brown coals are often situated too deep underground for opencast mining and require underground mining. This is also the case of coal seams occurring in glacitectonic folds. The methods of underground mining were lately used in Poland to mine coals in the Babina and Sieniawa deposits.
Brown coal resources are calculated to the maximum depth of deposit base of 350 m, the minimum brown coal layer thickness in bed of 3 m and maximum overburden/deposit thickness ratio of 12 : 1. The minimum weighted-average calorific value in bed (with intercalations) should equal 6.5 MJ/kg (at brown coal humidity of 50 %) and maximum medium sulphur content equal 2 % (for brown coal bed with intercalations and at humidity of 50 %). These are the limit values of parameters that defines the deposit and qualitative parameters for energy coals which are common in Polish deposits.
Poland’s anticipated economic resources of brown coals amounted to 22,683.98 million tonnes as of the end of 2013. The resources comprise 0.8 million tonnes of bituminous coal, about 2,390 million tonnes of coals usable for production of briquettes and about 1,418 million tonnes of coals suitable for production of coal tar and liquid through distillation. Nevertheless, all these coals are used and treated as energy coals only.
Table 1 shows resources and the current state of exploration and development of brown coal deposits in Poland.
Anticipated economic resources within exploited deposits amounted to 1,514.49 million tonnes (6.8 % of total anticipated economic resources). Brown coal is being exploited by five mines: Bełchatów, Turów, Adamów, Konin and Sieniawa.
Strip mining of brown coal of the Czempin, Krzywin and Gostyń deposits with total resources of 3,690 million tonnes is nowadays precluded on environmental grounds and in connection with high class and value of agricultural lands in area of the planned open strip mine. Table 2 shows basic parameters of major non-exploited deposits with anticipated economic resources over 75 million tonnes.
Anticipated economic resources of brown coal amounted to 22,683.98 million tonnes in 2013 and increased by 100.15 million tonnes in comparison with the previous year. There was one new deposit documented – Grochowy Siąszyce (with resources equal 48.21 million tonnes).
Economic resources of brown coal as of 31.12.2013 amounted to 1,164.67 million tonnes and decreased by 54.45 million tonnes.
Production amounted to 66,139 thousand tonnes in 2013, being 1,842 thousand tonnes higher (2.86 %) than in the previous year. The most important is Bełchatów-pole Bełchatów deposit (32.94 million tonnes – 49.8 % of domestic production) and Bełchatów-pole Szczerców deposit (with production equal 9.12 million tonnes – 13.8 % of domestic production). Almost the whole production of the largest brown coal strip mines (Bełchatów, Turów, Adamów and Konin) was used as energy coal in power plants.
The figure shows changes in resources and production of brown coal in Poland in the years 1989-2013.
Prepared by: Janina Dyląg