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 basic balance criterias for energy coals which are common in Polish deposits.
Criterias mentioned above were the basis while assessing prognostic brown coal resources which were calculated to be equal 27,540.71 million tonnes as of 31.12.2009(1). This figure is more than 40 % higher than anticipated economic resources calculated as of 31.12.2010. Prognostic resources occur in 90 prognostic deposits or prognostic areas near documented deposits within 7 coal-bearing regions: bełchatowski, koniński, legnicki, łódzki, północno-zachodni, wielkopolski i zachodni. The most important are prognostic resources in satellite deposits for mine-power boards.
At the end of 2011 Poland’s anticipated economic resources of brown coals amounted to 22,663 million tonnes.
Table 1 shows resources and the current state of exploration and development of brown coal deposits in Poland.
Anticipated economic resources were equal 22,663.08 million tonnes as of 31.12.2011 and increased by 2,844.21 million tonnes in comparison with the previous year, mostly due to amounts of resources documented in D and higher categories in 9 deposits (3,050.07 million tonnes of new resources).
Anticipated economic resources within exploited deposits amounted to 1,668.42 million tonnes (7 % of total anticipated economic resources).
Strip mining of brown coal of the Czempin, Krzywin and Gostyń deposits with total reserves 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.
Production amounted to 62,889 thousand tonnes in 2011, being 6,373 thousand tonnes higher than in the previous year. The most important is Bełchatów deposit (39.77 % of domestic production from Bełchatów area and 21.56 % of domestic production from Szczerców area). 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 given below shows changes in resources and production of brown coal in Poland in the years 1989-2011.
Economic resources of brown coal as of 31.12.2011 amounted to 1,287.03 million tones and decreased by 23.92 million tonnes.
Prepared by: Janina Dyląg
(1)J. R. Kasiński, 2011 - "Węgiel brunatny" w "Bilans perspektywicznych zasobów kopalin Polski wg stanu na 31 XII 2009 r." pod red. S. Wołkowicza, T. Smakowskiego, S. Speczika. PIG-PIB Warszawa.